Дисертації з теми "Energetic study"
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1
Zhu, Jin-Qian. "Evaluation of the energetic contribution from gut fermentation in growing pigs." Thesis, University of Aberdeen, 1988. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU016517.
Анотація:
The aim of this study was to evaluate the growth supporting value of DE derived from gut fermentation in growing pigs. Unmolassed sugar beet pulp (SBP) was selected as a model material for fermentation. For a reference material which would be digested in the small intestine by the endogenous enzymes, maize starch (MS) was selected. A cereal-based control diet was formulated to fulfil the needs of pigs for all essential nutrients apart from energy. To this control diet, either SBP (150 & 300 g/kg) or MS (100 & 200 g/kg) were added. The study consisted of two phases. The first phase (digestion trial and growth trial) was devoted to studying the digestion of these diets and to comparing the effects on growth of pigs of the two DE sources (SBP and MS). The second phase was to determine the production of VFA resulting from the fermentation of SBP. Methods used included stoichiometric calculations based on measurements of the molar proportions of VFA combined with CH4 production, and a direct assessment of the true fermented materials using antibiotics to suppress fermentation. The results of the first phase showed that the energy in SBP and MS had an apparent digestibility of 0.74 and 0.98. The DE from SBP was used for supporting carcass gain with an efficiency of 0.57 of the DE from MS. The results of the second phase indicated that measurements of methane production alone or even with inclusion of free hydrogen could underestimate the extent of fermentation in the gut of pigs. The results also suggest that with the cereal-based control diet, fermentation could supply up to 13.6% of the dietary DE in the form of VFA or 18.0% in the form of fermented energy. For this control diet incorporating 30% SBP, the respective values were 25.4% and 33.4%. The absorbed VFA resulting from the fermentation of SBP had a growth supporting value of 0.763 of that of absorbed glucose from MS.
2
Yamaguchi, Hiroyuki. "Simulation study of energetic particle physics in perturbed helical plasmas." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215531.
3
Hammel, Benjamin Diethelm. "Study Of Intense Energetic Electron Beams In X-Pinch Experiments." Thesis, University of Nevada, Reno, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10161337.
Анотація:
High-energy electron beams, with electron kinetic energies (∼1 MeV) much greater than the surrounding plasma temperature (<1 keV), are a common feature in Z-pinch pulsed power experiments. Their existence is indicated by non-thermal spectral signatures, such as high-energy Bremsstrahlung photons from the anode hardware and characteristic X-ray emission not representative of the pinch "hot-spot" temperatures. Despite their regular occurrence, the properties of these beams (kinetic energy, current) are not well known.
This dissertation describes an experimental study of X-pinch generated high-intensity electron beams, performed on the 1 MA pulsed power generator at the Nevada Terawatt Facility, and the feasibility of a novel method for inferring the total kinetic energy in the beam, through time-resolved measurements of the beam-induced shock that propagates through the anode.
4
Scott, Chris. "A computational study of surface topography arising from energetic particle interactions." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10090.
Анотація:
A computational investigation into the development of surface topographies subjected to energetic particle bombardment has been undertaken. Classical Molecular Dynamics (MD) and on-the- y kinetic Monte Carlo (otfKMC) techniques were employed and di erent bombardment conditions were considered. Surface topography development is of interest due to applications such as ion etching, which can be used in the manufacture of semiconductor devices. Crater formation on a HfO2-MgO interface system was investigated using a variety of methods. Initially single atom and cluster bombardments were performed, highlighting the radiation tolerance of the interface system. Subsequently, swift heavy ion bombardment of the interface was considered using a MD thermal spike model and an electron stripping with recombination model. Both models gave similar results to those seen experimentally: hillocks forming on the surfaces over the impact points of the ions; and ion tracks forming around the paths of the ions in the material. Hillock heights and sputtering yields were shown to increase linearly with the electronic stopping force of the bombarding ion, for the range of systems we considered. Bullet impacts on armour plating (SiC) have been simulated using MD. The bullet was modelled by a hard sphere that was forced into the substrate to the target depth. Both 4H and 6H SiC polytypes were considered with di erent bullet sizes and speeds. The 4H system resulted in the displacement of less atoms and also a much lower sputtering yield than for the similar 6H system. However dislocations were seen to propagate through the 4H system but not the 6H one. A large amount of sputtering was observed in the higher speed 6H simulations, with the ejection of many big clusters of atoms. These clusters generally had a high temperature (around 1,500 K) with speeds typically in excess of 1,000 m/s. Surface topography development by way of multiple impacts on Au was investigated using two di erent methodologies. Initially a traditional, MD based, methodology was used to model Au self bombardment of the high index f3 11 0g surface, which has been shown to produce interesting features. The disadvantage of this type of method is that MD cannot simulate time scales long enough to allow di usion between impacts. The MD method was shown to lead to a build up of defects in the systems: a result of the artificially high dose rate. An improved method was then used to model Ar and Au bombardment of both f0 1 0g and f3 11 0g Au surfaces. This hybrid MD-otfKMC technique enabled realistic time scales to be achieved. MD was used to model the ballistic phase while otfKMC was used to model di usion between events. The erosion rate of the surface was shown to be almost linear with time while the roughness of the surface was shown to oscillate: indicative of the healing process that occurs between bombardment events.
5
Masip-Sanchis, Ximo. "Energetic study of a residential building in Skutskär and savings proposal." Thesis, Högskolan i Gävle, Avdelningen för bygg- energi- och miljöteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-21665.
Анотація:
This project consists on the Energy audit carried out on a residential building in Skutskär, property of the company Älvkarlebyhus, which is placed in the Älvkarleby municipality, belonging to Uppsala County in Sweden. The aim of the Energy audit is to obtain how much Energy is used, when is it used and how is it used. As well as the costs of the Energy use. The aim of the Energy audit also consists in reduces the Energy use applying efficiency measures. The audit carried out consist on identifying the heat losses and heat gains of the building, thus establishing an Energy balance that will reflect the Energy state of the building and finally propose some efficiency measures that could be applied. With this purpose, a strong method was developed in order to obtain as accurate results as possible. This method studies separately each component of the balance in order to get a better approach. The idea when working and present the results is to manage all the information in an easy way and present it in an easily understandable way for everyone, thus was used a spreadsheet. The expected results have been achieved; the difference between the heat losses and gains is of 0 MWh, which represents the balance 0 and all the values obtained are according to the experience values, which achieve the expected results. The total heat gain of the balance accounts for 1575,23 MWh. It is compounded by the District heating consumption which accounts 742,22 MWh that represents the 47 % of the heat gain and by the free heating which accounts for 832,79 MWh that represents the 53 %. The free heating is compounded by solar radiation which accounts for 643,36 MWh representing 41 % and for Internal heating which accounts for 189,43 MWh that represents 12 %. The total heat loss of the balance accounts for 1575,23 MWh. It is compounded by transmission losses which accounts for 875,46 MWh that represents 56 %, mechanical ventilation which accounts for 369,89 MWh that represents the 23 %, natural ventilation which account for 182,88 MWh that represents 12 % and hot tap water which account for 147 and represents 9 %. The efficiency measures will improve the Energy use in the buildings; especially in the cases were the Energy usage is too high, as in the case of transmission losses. Thus, the efficiency measures will be proposed mainly to alleviate the high values but also to improve other inefficient uses of the Energy. There are some efficiency measures proposed for every component of the balance and there is also some recommendation for the company in order to implement the most attractive ones, taking into account its profitability. These measures are only proposed and not studied deeply because of the main limitation of this thesis. Therefore, it is recommended to continue the study in order to examine and analyse deeply each measure, according to the energetic survey already done.
6
Nakayama, Yohei. "Simulation Study on Enhancements of Energetic Heavy Ions in the Magnetosphere." Kyoto University, 2017. http://hdl.handle.net/2433/218015.
7
Asamura, Kazushi. "Study of energetic neutral atoms precipitating into the low-latitude upper atmosphere." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/181172.
8
Šimko, Vladimír. "Studie proveditelnosti projektu." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2014. http://www.nusl.cz/ntk/nusl-224311.
Анотація:
The Master’s Thesis deals with project management issues in the field of energetic, specifically diversification of fuel base with usage of renewable resources. The thesis is divided into two parts, from which the first part is focused on theoretical background of project, project management and feasibility study issues. In the second part particular feasibility study is elaborated. The goal of this thesis is to create feasibility study, which is one of the requested appendixes of grant application.
9
Abduljabbar, Ahmed A. "Energetic and exergetic study for cross-corrugated membrane-based total recovery exchanger for ventilation." Thesis, Cranfield University, 2017. http://dspace.lib.cranfield.ac.uk/handle/1826/13097.
Анотація:
Indoor air quality is an important component of the air conditioning of buildings due to its major effect on the health of the occupants, thus the air supplied to these buildings by the ventilation system should be sufficient, clean and healthy. A most promising development was the heat recovery system which offers better thermal energy efficiency and comfort with adequate fresh air. An energetic and exergetic analysis has been conducted on a cross-corrugated membrane based total heat exchanger core for ventilation of single dwellings. In order to enhance the sensible and latent effectiveness of the heat and mass transfer intensification was achieved by selecting Polyethersulfone for the membrane material, and a cross-corrugation arrangement of different dimensions for the primary surface exchanger. The design was tested against a ventilation air volume flow rate for an individual household; from 85 to 100 m3/hr. The dimensions of the exchanger were based on the polymer core being developed by Redring-Xpelair, Peterborough UK, with core dimensions of width and length both 250 mm, and a range of heights 100 – 500 mm. The cross-corrugated design of the test core had triangular openings with pitch lengths of 5, 10 and 25 mm. The ambient conditions were for a cold and humid winter in the UK. The ambient temperature test values were 2, 4, 6, 8 and 10 °C, and the inlet air velocities in the core were 0.5, 1.0, 1.5 and 2 m/s, with Reynolds numbers not exceeding 2200. CFD studies were conducted to investigate the thermal-fluid performance of the core, the Transition-SST model was used in the simulations within ANSYS Fluent 17.1 software and was validated using experimental data in the literature. The proposed model performed successfully in this study and proved that it was compatible with the test conditions. The exergetic analysis was conducted using the IPSEpro modelling software, by creating a system consisting of membrane core, a domestic dwelling, fresh air and exhaust fans. The energetic analysis results were the basis of the IPSEpro modelling to determine the exergy, the exergetic efficiency and exergy destruction in the system. The study concluded from both the energetic and the exergetic analysis that the membrane based exchanger core showed promising performance as a total heat and moisture recovery application with sensible and latent effectiveness values varying from 65% to 82%; and exergetic efficiency values varying from 30% to 60%, depending on core geometry and ambient conditions. The chemical exergy was the dominant factor in the performance in all cases, and the membrane core had the highest exergy destruction percentage comparing to the other system components. Decreasing the pitch length of the exchanger core intensified its performance, the 5 mm case showed the best performance, but there are likely to be difficulties in manufacturing such a compact core. But, and more directly, its use would mean unpleasant compromises due to the extremely higher pressure drop across such a core even at low Reynolds numbers. The 10 mm case gave a better performance than the 25 mm, but not substantially different, therefore, the optimum choice lies between the better heat and mass transfer performance of the 10 mm case and the lower pressure drop and relative ease of manufacture of the 25 mm.
10
Camur, Yakup. "A Computational Study On Nitrotriazine Derivatives." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609362/index.pdf.
Анотація:
In this study, all possible mono, di and trinitro-substituted triazine compounds as potential candidates for high energy density materials (HEDMs) have been investigated by using quantum chemical treatment. Computational chemistry is a valuable tool for estimating the potential candidates for high energy density materials. Geometric features and electronic structures of these nitro-substituted triazines have been systematically studied using ab initio and density functional theory (DFT, B3LYP) at the level of 6-31G(d,p), 6-31+G(d,p), 6-311G(d,p), 6-311+G(d,p), cc-pVDZ. Detonation performances were evaluated by the Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that 2G derivative with the predicted densities of 1.9 g/cm3, detonation velocities of 9.43 km/s, and detonation pressures of 40.68 GPa may be novel potential candidates of high energy density materials (HEDMs). Moreover, thermal stabilities were investigated by calculating bond dissociation energies (BDE) at B3LYP/6-311G(d,p) level. Detailed molecular orbital (MO) investigation have been performed on these potential HEDMs.
11
Cui, Peng. "First Principle Study on Interfacial Energetic Alignment and Charge Transfer in Quantum Dots Functionalized via Metal-Organic Dye." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25925.
Анотація:
Quantum dots (QDs) are promising materials for applications in solar energy conversion because of tunable band gap, multi-exciton generation, photon-upconversion, etc. One of the main challenges of increasing solar energy conversion is to extend the lifetime of photoexcited charge-carriers in conduction band, and one of the strategies is to functionalize QD with mediator molecules. Functionalizing QD with metal-organic dye serves as the additional channel of manipulating charge transfer ? the key process increasing solar energy conversion. When metal-organic dye is attached to QD, the interfacial charge transfer direction as well as the rates are determined by a balance between the energetic alignment, QD-dye interaction as well as charge-carrier relaxation dynamics. In this dissertation, we explore the effect of dye functionalization on these elements. We change the metal ion, organic ligands as well as binding geometry of dye, size of QD, polarity of solvent, and use density functional theory to study their effects on energetic alignment. Embedding density functional calculation is used to study the dipole interaction between QD and dye providing additional controllability on charge transfer excitation. At last, we apply Tully surface hopping scheme in combining with density functional theory in time domain to study the charge-carrier relaxation dynamics and charge transfer across the heterogeneous interface in QD/dye nanocrystal composite.
12
Morace, A. "STUDY OF FAST ELECTRON TRANSPORT AND ENERGETIC PROTON GENERATION AT HIGH LASER INTENSITY AND APPLICATION TO FAST IGNITION." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/219123.
Анотація:
Fast Ignition is a very promising, alternative way to achieve energy gain in Inertial Confinement Fusion (ICF) research. It is based on the decoupling of the compression and heating stages of an equi-molar Deuterium-Tritium (DT) plasma, allowing to loose the very tight constraints of the classic central hot spot (CHS) ignition concept, and attaining higher energy gain. The compression of the DT capsule is performed by symmetrically focusing an array of energetic, long (ns) laser pulses on the capsule, inducing its implosion by ablation pressure driven convergent shocks. The heating of the compressed DT plasma is produced by energetic particle beams (electrons or protons), generated by an energetic, ultra-intense (I approx 10^20 W/cm2) short (approx 20 ps) laser pulse, focused at the instant of DT peak compression.
The study of generation and transport of laser produced fast electrons and protons is therefore fundamental for the achievement of Fast Ignition ICF.
In this work I present the experimental as well as modeling study of fast electron transport and proton beam generation, with application to Fast Ignition. In particular in this work I studied the fast electron transport in rapidly changing plasma density and temperature gradients, conditions expected in a full scale Fast Ignition experiment.
In the second part of this work I demonstrated a method to improve the laser-to-proton energy conversion efficiency in a way very suitable for Fast Ignition as well as for medical application.
13
Skandalis, Dimitri A. "The contributions of life history and inter-individual variation to the study of energetic supply and demand in Bombus impatiens." Thesis, University of Ottawa (Canada), 2011. http://hdl.handle.net/10393/28907.
Анотація:
In insects, flight energetics varies greatly among species but the source of this variation remains unknown. This thesis addresses phenotypic plasticity and matching of cellular and whole-animal metabolism in a bumblebee (Bombus impatiens). Bumblebees begin flying prior to full metabolic maturation, suggesting a window of greater metabolic plasticity. Bees were induced to fly before fully maturing, but although flight training resulted in elevated metabolic rates compared to controls, there was no change in biochemical activities of any tested enzymes. Similarly, while statistical models of flight parameters explained the majority of inter-individual variation in measures such as metabolic rate and wing beat frequency, there was no direct link between whole-animal metabolism and cellular energy production pathways. This suggests that muscle energy production and whole-animal metabolic demands are not plastically synchronised, and that inter-specific variation is likely not solely the result of phenotypic plasticity.
14
Doyle-Lucas, Ashley Faye. "The Study of a Unique Athletic Population: Health Concerns, Interventions, and Prevention in Elite Ballet Dancers." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37336.
Анотація:
Ballet dancers are a unique population of athletes in that, unlike other sports, their success strictly depends on both physical capabilities and aesthetic factors. While the physical demands of the performing sport are strenuous, ballet dancers are often required to exhibit a thin physique, frequently resulting in weights 10-12% below the ideal. These low weights are commonly achieved by low energy intakes which increase dancers' susceptibility to the development of various health conditions. Research investigating the health of dancers, however, is limited and hampered by methodological limitations. To address these issues, we tested the hypothesis that dancers would report a low habitual energy intake and, therefore, be subject to conditions comprising the Female Athlete Triad, including low energy availability, suboptimal bone density and menstrual irregularities. In addition, we hypothesized that elite female dancers would have lower than expected resting metabolic rate (RMR) based upon their fat-free mass, and thus greater energetic efficiency as a result of chronic energy deficiency. As hypothesized, dancers reported a significantly lower energy intake and exhibited a lower RMR as compared to lean, pair-matched controls. Because treatment of these metabolic abnormalities is challenging, prevention of adverse health outcomes among adolescent pre-professional dancers is key in promoting overall health and optimal performance. Through our subsequent 'formative work', we determined that the current availability of nutrition education offered to both professional and pre-professional dancers is minimal and of questionable quality. Thus, we developed, implemented, and evaluated a DVD-based educational program, entitled "Nutrition for Optimal Performance", aimed at improving health knowledge and behaviors of pre-professional adolescent ballet dancers. Our findings indicate that participants increased their knowledge of basic nutrition principles and self-efficacy for adopting healthier dietary habits, as compared to pre-program and control group scores, and that knowledge gains were sustained at a six-week follow-up assessment. Collectively, these studies provide the field of dance medicine with novel findings related to the characteristics and health conditions of professional ballet dancers, and the effectiveness of a low-resource, disseminable nutrition education program which promotes the health and optimal performance of pre-professional adolescent ballet dancers.Ph. D.
15
Fahad, Noor. "Experimental study of oxidation, ignition and combustion of aluminum based nanomaterials." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8777.
Анотація:
Aluminum based reactive nanomaterials have extensive applications in many fields including solid propellants, pyrotechnics, and catalytic reactions. One recent example is the novel concept of using nanostructured energetic particles for energy storage where the controlled exothermic reaction is the key to control the energy release process. It is of primary interest to understand the thermodynamics, kinetics, morphological and structural properties of these particles during the exothermic reaction. While the physiochemical properties of the monometallic powders are determined only by their size, the properties of bimetallic nanoalloys can be also engineered by their constituent compositions. This thesis conducts a systematic experimental investigation of the oxidation, ignition, and combustion of nano aluminum particles (nAl) and nanoalloys such as nanoscale aluminium-copper (n-AlCu) and aluminium-zinc (n-AlZn). The oxidation experiments are conducted by a TGA/DSC system with detailed characterisation of particles before and after the experiments by scanning electron microscopy (SEM), transmission electron microscopy (TEM), the Nanosizer, Brunauer–Emmett–Teller (BET), energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffractionmetry (XRD). In the TGA/DSC analysis, nanomaterials are oxidized either at constant temperature or under different heating rates in the controlled atmosphere of air or nitrogen. A unique early ignition reaction is observed at the high heating rates for nAl and n-AlCu, which is associated with the effect of polymorphic phase transformation of the alumina shell and the early melting of the aluminum core. Different to the conventional shrink-core concept, hollow structures, i.e. nanoholes, in the central regions of nAl are observed and a phenomenal model is proposed. The comparison of the thermal-chemical characteristics of different nanomaterials reveals some unique 5 features related to nano-alloys such as increased reactivity. A preliminary combustion experiment on feeding nanoparticles in a methane stream is performed with a Bunsen burner setup, where the burning characteristics of different nanoparticles are analysed.
16
SAIO, CAMILLA. "Study of the criteria and methodologies for existing buildings energetic and functional retrofit: architecture/energy systems integration towards nZEB (nearly Zero Energy Building)." Doctoral thesis, Università degli studi di Genova, 2018. http://hdl.handle.net/11567/929602.
17
Ferrer, i. Martí Ivet. "Study of the effect of process parameters on the thermophilic anaerobic digestion of sewage sludge, evaluation of a thermal sludge pre-treatment and overall energetic assessment." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/5323.
Анотація:
El consum energètic representa un 30 % dels costos d'operació en sistemes intensius de tractament d'aigües residuals urbanes. En depuradores convencionals que utilitzin un sistema de fangs activats, entorn al 15-20 % de l'energia és consumida en la línia dels fangs, que inclou el bombeig, l'espessiment, l'estabilització i la deshidratació. Per tant, la optimització de la gestió dels fangs pot contribuir substancialment en la reducció dels costos de tractament d'aigües residuals. La digestió anaeròbia termofílica és més eficient que la mesofílica i pscicrofílica, en termes de producció de biogàs i metà, eliminació de sòlids volàtils (SV) i destrucció de patògens. El procés es pot accelerar mitjançant el pre¬tractament dels fangs, afavorint la seva solubilització i hidròlisi. L'objecte d'aquesta Tesi Doctoral fou estudiar l'impacte dels paràmetres del procés en la digestió anaeròbia termofílica dels fangs de depuradora urbana, avaluar l'efecte del pre-tractament tèrmic dels fangs a baixa temperatura, i valorar processos alternatius des del punt de vista energètic.
Els resultats experimentals presentats s'obtingueren mitjançant l'operació de dos reactors de laboratori durant prop de dos anys. En aquest període es va estudiar l'efecte de la temperatura del procés, del temps de retenció dels fangs (TRF), de la velocitat de càrrega orgànica (VCO) i del pre-tractament a 70 ºC en la digestió anaeròbia dels fangs de depuradora. El procés fou avaluat en termes de la producció d'energia (biogàs i metà) i de la qualitat del fang digerit (contingut de SV i d'àcids grassos volàtils (AGV), facilitat de deshidratació i higienització). S'analitzà l'estabilitat del procés a mesura que es reduïa el TRF i s'incrementava la VCO, i es comparà l'eficiència en períodes d'estabilitat corresponents a les diferents condicions operacionals. Finalment, s'avaluaren els resultats des del punt de vista energètic, mitjançant el càlcul de balanços i ratis energètics teòrics, que es compararen amb els resultats obtinguts a partir de dades experimentals d'altres estudis. També s'utilitzà un model cinètic de primer ordre. Les conclusions que es desprenen d'aquest treball es resumeixen a continuació:
Durant la digestió anaeròbia dels fangs, la transició d'un reactor mesophilic (43 ºC) a termofílic (50 ºC) es podria dur a terme sense alterar el procés, treballant a TRF elevats (≥ 30 dies) i VCO baixes (≤ 0.5 kg SV m-3reactor d-1). En aquestes condicions, les principals diferències entre reactors termofílics (50-55 ºC) i mesofílics (38-43 ºC) fan referència a una certa acumulació d'AGV (0.5-2.5 g L-1) i millora de la destrucció de patògens (E. coli ≤ 102 UFC mL-1). La digestió termofílica a 50 ºC i 55 ºC dóna lloc a resultats similars pel que fa a la producció de biogàs, estabilització, higienització i facilitat de deshidratació de l'efluent, si no varien els altres paràmetres operacionals.
La producció de metà tendeix a incrementar proporcionalment a la VCO, és a dir al TRF i el contingut de SV als fangs alimentats. Així mateix, la qualitat de l'efluent (contingut de SV i AGV, facilitat de deshidratació dels fangs) també depèn de la VCO. D'acord amb els resultats obtinguts a 55 ºC, la producció de metà s'incrementà 2-3 vegades (de 0.2 a 0.4-0.6 m3CH4 m3reactor d-1) en disminuir el TRF de 30 a 15-10 dies, incrementant la VCO de 0.5 a 2.5-3.5 kg SV m3reactor d-1. En canvi, el procés es desestabilitzà amb la reducció del TRF a 6 dies i VCO per sobre de 5 kg SV m3reactor d-1. Les següents concentracions poden ser útils per detectar i prevenir la desestabilització d'un digestor termofílic de fangs: AGV totals
(2.5 g L-1), acetat (0.5 g L-1), rati acetat/propionat (0.5), alcalinitat intermèdia (1.8 g CaCO3 L-1), rati alcalinitat intermèdia/alcalinitat parcial (0.9), rati alcalinitat intermèdia/alcalinitat total (0.5), contingut de metà al biogàs (55 %).
El pre-tractament a 70 ºC afavoreix la solubilització dels fangs, incrementant la proporció de matèria orgànica soluble respecte la matèria orgànica total del 5 % al 50 % en 9-24 h; seguit d'una progressiva generació d'AGV després de 24h. Durant la subseqüent digestió anaeròbia de fangs pre¬tractats (9-48 h), s'incremetà la producció de biogàs en un 30-40 %, treballant a 55 ºC i 10 dies de TRF. El rendiment de producció de biogàs fou un 30 % superior amb fangs pre-tractats (0.28-0.30 vs. 0.22 L·gVS¬1) i el contingut de metà al biogàs també fou superior (69 % vs. 64 %).
La digestió anaeròbia termofílica de fangs pot donar lloc a una producció neta d'energia, durant estacions fredes i càlides, si s'utilitzen reactors amb aïllament tèrmic de les parets i amb recuperació energètica a partir del biogàs i dels fangs digerits. En aquest cas, l'eficiència energètica de reactors termofílics treballant a la meitat de TRF (10-15 dies) que reactors mesofílics (20-30 dies) seria similar, per la qual cosa el cabal diari podria ser doblat, o el volum del reactor reduït, amb el conseqüent estalvi en el cost de tractament dels fangs. A més, un sistema en dues etapes (70/55 ºC) produiria més energia neta que un sistema en una sola etapa (55 ºC) amb un TRF de 10 dies. De totes maneres, la quantitat d'energia neta generada augmenta amb el volum del digestor donat que, malgrat la disminució en la producció de metà a TRF creixents, la producció d'energia segueix essent superior al consum, i per tant com més quantitat de fangs hi hagi al digestor, més energia es produirà.
Energy consumption accounts for some 30 % of the total operating costs of intensive sewage treatment systems. In conventional wastewater treatment plants employing an activated sludge process, around 15-20 % of this energy is used in the sludge treatment line, including sludge pumping, thickening, stabilisation and dewatering. Therefore, optimisation of sludge management can substantially contribute in the reduction of wastewater treatment costs. Thermophilic anaerobic digestion is more efficient than mesophilic anaerobic digestion, in terms of biogas production, volatile solids (VS) removal and pathogens destruction. The process might be further accelerated by sludge pre-treatment, promoting sludge solubilization and hydrolysis.
The aim of this PhD Thesis was to study the impact of process parameters on the thermophilic anaerobic digestion of sewage sludge, to evaluate the effect of implementing a low temperature pre¬treatment step, and to assess alternative processes from an energy perspective.
The experimental results presented were obtained by operating two lab-scale reactors for almost two years. During this period, the effect of process temperature, sludge retention time (SRT), organic loading rate (OLR) and 70 ºC sludge pre-treatment on the anaerobic digestion of sewage sludge was studied. The process was evaluated in terms of energy production (i.e. biogas and methane production) and the quality of the effluent sludge (i.e. VS and volatile fatty acids (VFA) content, sludge dewaterability and hygienisation). Focus was put on the stability of the process at decreasing SRT and increasing OLR. Process efficiency during stable performance under each operating condition assayed was compared. Finally, the results were assessed from an energy perspective, by means of theoretical energy balances and ratios; and compared to the results obtained with experimental data from other studies. A first order kinetic model was also used. The conclusions drawn from the different issues dealt in this work are summarised as follows:
During anaerobic sludge digestion, the transition from a mesophilic (43 ºC) to a thermophilic operation (50 ºC) may be carried out without disturbing the process, by operating the reactors at high SRT ( ≥ 30 days) and low OLR (≤ 0.5 kg VS m-3reactor d-1). Under such conditions, some VFA accumulation (0.5-2.5 g L-1) and enhanced pathogen destruction (residual E. coli ≤ 102 CFU mL-1) would be the main differences of thermophilic (50-55 ºC) compared to mesophilic (38-43 ºC) reactors. Thermophilic sludge digestion at 50 ºC and 55 ºC should be similar in terms of biogas production and effluent stabilisation, hygienisation and dewaterability; provided that other process parameters are the same.
Methane production rate tends to increase proportionally to the OLR, thus to the SRT and VS concentration in the feed sludge. Similarly, the quality of the effluent sludge (VS content, VFA content and sludge dewaterability) is also affected by the OLR. According to the results obtained at 55 ºC, methane production rate increased by 2-3 times (from 0.2 to 0.4-0.6 m3CH4 m3reactor d-1) by decreasing the SRT from 30 to 15-10 days; increasing the OLR from 0.5 to 2.5-3.5 kg VS m3reactor d-1. However, process unbalance resulted from SRT reduction to 6 days, with OLR above 5 kg VS m3reactor d-1. The following concentrations might be useful to detect and prevent digester failure during thermophilic sludge digestion: total VFA (2.5 g L-1), acetate (0.5 g L-1), acetate/propionate ratio (0.5), intermediate alkalinity (1.8 g CaCO3 L-1), intermediate alkalinity/partial alkalinity ratio (0.9), intermediate alkalinity/total alkalinity ratio (0.5), methane content in biogas (55 %).
The 70 ºC sludge pre-treatment may initially promote sludge solubilization, increasing the concentration of soluble to total organic matter from 5 to 50 % within 9-24 h; which is followed by a progressive VFA generation after 24 h. Subsequent anaerobic digestion of pre-treated sludge samples (9¬48 h) could increase biogas production by 30-40 % working at 55 ºC with a SRT of 10 days. Biogas yield is some 30 % higher with pre-treated sludge (0.28-0.30 vs. 0.22 L·gVSfed-1) and methane content in biogas is also higher with pre-treated sludge (69 vs. 64 %).
Thermophilic anaerobic sludge digestion would result in net energy production, during cold and warm seasons, provided that digesters with wall insulation and with energy recovery from both the biogas produced and the effluent sludge are used. In this case, the energetic efficiency would be similar for thermophilic digesters working at half the SRT (10-15 days) of mesophilic digesters (20-30 days), meaning that the sludge daily flow rate could be doubled, or the reactor volume reduced, with subsequent savings in terms of sludge treatment costs. Furthermore, two-stage systems (70/55 ºC) may result in higher net energy production compared to single-stage systems (55 ºC) at 10 days SRT. However, the amount of surplus energy generated increases with digester volume. In spite of the decrease in methane production rate at increasing SRT, energy production is still higher than energy consumption, and therefore the bigger the amount of sludge in the digester, the higher the energy production.
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Aroua, Ayoub. "Mise à l'échelle des entraînements électromécaniques pour la conception au niveau système dans les premières phases de développement des véhicules électriques." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILN042.
Анотація:
L'industrie automobile est contrainte d'accélérer le développement et le déploiement des véhicules électrifiés à un rythme sans précédent, afin d'aligner le secteur du transport avec les objectifs climatiques. La réduction du temps de développement des véhicules électriques devient une priorité urgente. D'autre part, l'industrie est confrontée à une complexité accrue et à l'ampleur de l'espace de conception des chaînes de traction électrifiées émergentes. Les approches existantes pour aborder la conception des composants, notamment les méthodes numériques telles que la méthode des éléments finis, la mécanique des fluides numérique, etc., reposent sur un processus de conception détaillé. Cela entraîne une longue charge de calcul lorsqu'on essaie de les intégrer au niveau système. L'accélération des premières phases de développement des véhicules électrifiés nécessite de nouvelles méthodologies et de nouveaux outils, permettant d'explorer l'espace de conception au niveau système. Ces méthodologies devraient permettre d'évaluer les différents choix de pré-dimensionnement des chaînes de traction électrifiées dans les phases de pré-étude. Cette évaluation devrait se faire de manière efficace en termes de temps de calcul, tout en garantissant des résultats fiables en termes de consommation énergétique au niveau système. Pour relever ce défi, cette thèse de doctorat vise à développer une méthodologie de mise à l'échelle pour les systèmes d'entraînement électromécaniques, permettant l'étude au niveau système de différents véhicules électriques. Un système d'entraînement électromécanique se compose d'un ensemble comprenant un onduleur, une machine électrique, un réducteur mécanique et une unité de contrôle. La procédure de mise à l'échelle vise à prédire les données d'une conception nouvellement définie d'un composant donné avec des spécifications différentes sur la base d'une conception de référence, sans avoir à refaire des étapes qui demandent beaucoup de temps et d'efforts. À cette fin, différentes formulations de lois de mise à l'échelle des composants du système d'entraînement électromécanique sont examinées en détail et comparées au niveau composant en termes de mise à l'échelle de la perte de puissance. Un accent particulier est mis sur l'examen de la méthode de mise à l'échelle linéaire des pertes par une homothétie, qui est largement employée dans les études au niveau système. En effet, cette méthode présente des hypothèses discutables et n'a pas fait l'objet d'une étude approfondie. En outre, l'une des principales contributions de ce travail est la formulation des lois de mise à l'échelle des pertes de puissance des réducteurs mécaniques, qui ont été identifiées comme une lacune dans la littérature actuelle. Pour ce faire, une campagne expérimentale intensive a été menée sur des réducteurs mécaniques commerciaux. Pour intégrer les lois d'échelle au niveau système et étudier l'interaction entre les composants mis à l'échelle, le formalisme de la représentation macroscopique énergétique est utilisé. La nouveauté de la méthode proposée réside dans la structuration d'un modèle et d'une commande évolutifs du système d'entraînement électromécanique de référence à utiliser dans la simulation au niveau système. La nouvelle organisation consiste en un modèle et une commande de référence complétés par deux éléments d'adaptation de puissance du côté électrique et mécanique. Ces derniers éléments prennent en compte les effets d'échelle, y compris les pertes de puissance. La méthodologie est appliquée à différents cas d'étude de véhicules électriques à batterie, allant des véhicules légers aux véhicules lourds. Une attention particulière est accordée à l'évaluation de l'impact de la méthode de la mise à l'échelle linéaire sur la consommation d'énergie, en tenant compte de différents facteurs de mise à l'échelle de la puissance et des cycles de conduite, par rapport à d'autres méthodes de mise à l'échelle avec une haute-fidélitéThe automotive industry is required to accelerate the development and deployment of electrified vehicles at a faster pace than ever, to align the transportation sector with the climate goals. Reducing the development time of electric vehicles becomes an urgent priority. On the other hand, the industry is challenged by the increasing complexity and large design space of the emerging electrified powertrains. The existing approaches to address component design, such as numerical methods exemplified by finite element method, computational fluid dynamic, etc., are based on a detailed design process. This leads to a long computational burden when trying to incorporate them at system-level. Speeding up the early development phases of electrified vehicles necessitates new methodologies and tools, supporting the exploration of the system-level design space. These methodologies should allow for assessing different sizing choices of electrified powertrains in the early development phases, both efficiently in terms of computational time and with reliable results in terms of energy consumption at system-level. To address this challenge, this Ph.D. thesis aims to develop a scaling methodology for electric axles, allowing system-level investigation of different power-rated electric vehicles. The electric axle considered in this thesis comprises a voltage source inverter, an electric machine, a gearbox, and a control unit. The scaling procedure is aimed at predicting the data of a newly defined design of a given component with different specifications based on a reference design, without redoing time and effort-consuming steps. For this purpose, different derivations of scaling laws of the electric axle components are thoroughly discussed and compared at component-level in terms of power loss scaling. A particular emphasis is placed on examining the linear losses-to-power scaling method, which is widely employed in system-level studies. This is because, this method presents questionable assumptions, and has not been the subject of a comprehensive examination. A key contribution of the presented work is the derivation of power loss scaling laws of gearboxes, which has been identified as a gap in the current literature. This is achieved through an intensive experimental campaign using commercial gearboxes. To incorporate the scaling laws at system-level and study the interaction between the scaled components, the energetic macroscopic representation formalism is employed. The novelty of the proposed method lies in structuring a scalable model and control for a reference electric axle to be used in system-level simulation. The novel organization consists of a reference model and control complemented by two power adaptation elements at the electrical and mechanical sides. These latter elements consider the scaling effects, including the power losses. The methodology is applied for different study cases of battery electric vehicles, ranging from light to heavy-duty vehicles. Particular attention is paid to assessing the impact of the linear power-to-losses scaling method on the energy consumption considering different power scaling factors and driving cycles, as compared to high-fidelity scaling methods
19
Idouakass, Malik. "Linear and nonlinear study of the precessional fishbone instability." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4756/document.
Анотація:
L'interaction onde-particule dans les plasma est un sujet de recherche important, pour la compréhension des phénomènes physiques fondamentaux comme pour l'opération de réacteurs à fusion tels que les tokamaks. Cette intéraction peut être responsable de l'existence de modes instables, comme l'instabilité "fishbone" dans les plasmas de tokamak. Celle-ci est causée par l'interaction résonante entre un mode vivant dans la plasma et une population de particules supra-thermiques. Cette instabilité cause l'éjection d'une partie de ces particules énergétiques. Elle est par ailleurs caractérisée par une diminution de sa fréquence durant son évolution. Dans cette thèse, un modèle pour l'instabilité "fishbone", décrivant le plasma thérmique avec un traitement fluide et les particlules énergétiques avec un traitement cinétique, est développé. Ce modèle est simplifié de manière à permettre la compréhension des mécanismes les plus basiques qui causent la destabilisation du mode, sa diminution en fréquence durant son évolution ainsi que l'éjection de particules qu'il engendre. La théorie linéaire de ce modèle est faite, montrant les conditions qui permettent l'existence de l'instabilité, et permettant la caractérisation de son comportement linéaire. Les résultats analytiques sont ensuite comparés aux résultats linéaires numériques, obtenus grâce à un code développé durant cette thèse et basé sur les hypothèses du modèle, et ils sont en accord. Enfin, ce code est utilisé pour explorer le comportement non linéaire des particules énergétiques. Le mécanisme principalement responsable du changement de fréquence du mode ainsi que de l'éjection des particules est identifié et étudié en detailThe wave-particle interaction in plasmas is an important research subject, for fundamental physical understanding as well as for the operation of fusion devices such as tokamaks. This interaction can cause the existence of unstable modes, such as the fishbone instability that is observed in tokamak plasmas. It results from the resonant interaction between an electro-magnetic wave living in the plasma and a population of supra-thermal particles. This mode causes the ejection of a portion of these energetic particles, and is thus detrimental to the confinment of energy in a tokamak, and it is characterized by a frequency down-chirping, i.e. a decrease of frequency of the mode during its evolution. In this thesis, a model for the fishbone instability is developed, that describes the thermal plasma with fluid equations and the supra-thermal particles with the kinetic Vlasov equation. This model is highly simplified in order to understand the basic mechanisms leading to destabilization, frequency chirping, and particle ejection. The linear theory of this model is then done, showing the conditions that lead to the existence of an instability, and that allow the characterization of its linear behavior. The linear analytic results are then compared to numerical linear results obtained with a code, based on the assumptions of the model, that was developed during this PhD and the results are found to be in good agreement. Finally, the code is used to explore the nonlinear behavior of energetic particles in the later phase of the fishbone instability. The main mechanism responsible for the frequency chirping and energetic particle ejection is identified and studied in detail
20
Vasile, Virginia. "Experimental study of the thermal and rheological behaviour of paraffin-in-water emulsions used as a secondary refrigerants." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI056/document.
Анотація:
Une émulsion à changement de phase (PCME: phase-change material emulsion) est un fluide consistant en une émulsion d'un matériau à changement de phase (PCM, phase change material), comme de la paraffine, dispersé dans un fluide porteur (phase continue), souvent de l'eau ou une solution acqueuse de surfactant. Les PCME peuvent être envisagés comme fluides à haute performance thermique (frigoporteurs ou caloporteurs) en raison de leur potentiel de transport de chaleur latente (cristallisation ou fusion du PCM). Cette thèse présente des résultats expérimentaux concernant le comportement thermo-rheologique des differentes versions de PCME (émulsions de paraffine dans différentes solutions acqueuses de surfactant, avec une concentration massique en paraffine égale à 30 %) sur une plage de température de 0 - 20 °C. Les propriétés thermophysiques des émulsions ont été déterminées. Ensuite, une étude expérimentale du transfert de chaleur par convection forcée laminaire a été effectuée. Le coefficient de transfert de chaleur convectif de l'émulsion pendant le refroidissement a été déterminé dans une configuration expérimentale proche de celle pouvant être rencontrée dans des échangeurs thermiques à plaques. La configuration se compose principalement de deux canaux rectangulaires (80 x 6 mm²) de longueurs égale à 1 m. Des corrélations utiles pour évaluer les coefficients d'échange thermique (locaux ou globaux) ont été établies entre les nombres de Nusselt, de Reynolds et de Prandtl. Un banc d'essais spécifique a également été utilisé pour analyser le comportement rhéologique des PCME. Des essais ont été effectués à l'aide d'un viscosimètre à différentes températures. La stabilité des émulsions a été examinée sous diverses charges thermomécaniques. Les expériences ont révélé un comportement rheofluidisant. L'ensemble de ces résultats montre que les PCME sont des candidats prometteurs pour les applications à la climatisationA phase change material emulsion (PCME) is a fluid consisting of an emulsion of a phase change material (PCM), such as paraffin, dispersed in a carrier fluid (contiunuous phase), often water of an aqueous solution of surfactant. PCMEs can be considered as potential high performance thermal fluids (used as secondary refrigerants or as heat transport fluids) owing to their latent heat involved in the fusion of cristalisation of the PCM. This thesis reports experimental results concerning the thermo-rheological behavior of different versions of a PCME (30%wt. paraffin concentration in various acqueous solutions of surfactant) over the temperature range [0 – 20 °C]. The thermophysical properties of the PCMEs were determined. Then, an experimental study of forced convection heat transfer during laminar flow was carried out. The convective heat transfer coefficient of the PCMEs during cooling was determined in an experimental configuration mocking up applications in plate heat exchangers. The configuration mainly consists of two 1 m long rectangular channels (80 x 6 mm2). Correlations were developped for the prediction of the (local and overall) heat transfers coefficients, based on the Nussel, Reynolds and Prandtl numbers. A specific test bench was also used to analyse the rheological behaviour of the PCMEs. Tests were carried out using a viscometer at different temperatures. The stability of the emulsion was examined under various thermo-mechanical loads. Experiments revealed a pseudoplastic behavior for all tested versions of the PCME. All these results show that PCMEs are an attractive candidate for their applications in the field of air conditioning
21
Merlier, Lucie. "On the interactions between urban structures and air flows : A numerical study of the effects of urban morphology on the building wind environment and the related building energy loads." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0070/document.
Анотація:
Cette thèse exploratoire pose les bases scientifiques et méthodologiques d’une approche transversale visant à étudier l’énergétique urbaine et le bio-climatisme. Elle fait appel à des concepts et des outils de l’architecture et l’urbanisme, et à la physique du bâtiment et de la ville. Cette thèse étudie les relations entre la morphologie urbaine et les processus aérodynamiques qui se développent dans la canopée urbaine et leurs effets sur la demande énergétique des bâtiments induite par les infiltrations d’air et les échanges thermiques convectifs. Les spécificités de l’aérodynamique et de la physique urbaines sont d’abord synthétisées et la morphologie de tissus urbains réels est analysée. Une typologie générique de bâtiments isolés et une autre d’îlots urbains en sont déduites. Le modèle CFD est ensuite validé par comparaison des prédictions du modèle avec des résultats expérimentaux et numériques, et des expérimentations numériques sont réalisées sur les différents types morphologiques. Les écoulements moyens sont analysés dans leurs rapports avec la morphologie bâtie, et la distribution des coefficients de pression sur les façades des bâtiments est analysée. Ensuite, les échanges thermiques sont couplés aux processus aérodynamiques. L’amélioration des estimations des échanges convectifs des bâtiments grâce à la CFD est vérifiée par comparaison des résultats de simulation avec des données expérimentales et numériques, ainsi qu’avec les valeurs standard. Une adaptation des fonctions de paroi relatives au transfert thermique est proposée sur la base d’études existantes, et la distribution des échanges convectifs sur les façades de bâtiments est analysée. Enfin, la demande énergétique des bâtiments due aux infiltrations d’air et à la transmission de chaleur au travers de leur envelope est estimée pour différents types morphologiques, et comparée avec les valeurs estimées suivant une approche réglementaire. Les résultats de cette thèse mettent en évidence les effets des propriétés topologiques et métriques des bâtiments et ensembles bâtis sur le développement de recirculations d’air dans la canopée urbaine. Celles-ci induisent une distribution et intensité hétérogènes des coefficients de pression et d’échange convectif sur les façades des bâtiments, qui influent sur le comportement thermique des bâtiments non isolés et perméables à l’air. Par ailleurs, l’estimation de leur demande énergétique diffère suivant si celle-ci est basée sur les valeurs simulées ou standard des coefficients de pression et d’échange convectif. Cependant, l’influence relative de la structure bâtie sur la demande énergétique des bâtiments apparaît plus importante pour les bâtiments isolés thermiquement. La différence entre la demande énergétique par unité de surface de plancher, due aux infiltrations d’air et pertes thermiques au travers de l’enveloppe peut varier de 18% à 47% suivant si le bâtiment est isolé ou situé dans un environnement bâtiThis thesis is an exploratory study that lays the scientific and methodological foundations of a transverse approach for studying urban energy and bio-climatic issues. This approach involves concepts and tools of building and urban physics as well as urban planning and architecture. It addresses the relations between urban morphology and aerodynamic processes, and studies their effects on the building energy loads due to infiltration and convective heat losses. This thesis is divided into three main parts. The first part synthesizes the specificities of urban aerodynamics and urban physics, and analyzes existing urban fabrics from a morphological point of view. Generic typologies of isolated buildings and urban blocks for small scale aerodynamic studies are deduced. The second part validates the computational fluid dynamics (CFD) model (steady RANS RSM) against detailed experimental and numerical data, and presents the numerical experiments performed on the different morphological types. Mean flow structures that develop according to the construction shape and built environment, as well as pressure distribution on the building outer walls are examined. The last part couples heat and air fluxes to evaluate the contribution of urban air flows on the building energy loads. The improvement brought by CFD to the assessment of building convective heat transfers is verified by comparing numerical results to experimental data, detailed numerical studies and standard correlations. An enhanced temperature wall-function adapted for forced convection problems is adjusted to the model based on existing studies, and the convective heat transfers distribution on building facades is analyzed. Finally, the building energy loads due to air infiltration and heat transmission are estimated for typical constructions and compared to standard values. The results of this thesis show strong effects of the topology and dimensionality of constructions and urban structures on the development of recirculation phenomena within the urban canopy layer. The related aerodynamic conditions yield heterogeneous pressure and convective heat transfer intensities and distributions on building facades, which depend upon the considered built morphology. Their effects on building energy loads are logically particularly important in absolute value for buildings that are neither insulated nor air tight. Nonetheless, the estimates of the building energy needs based on standard or simulated pressure and convective heat transfer coefficients often show substantial deviation. Focusing on the relative contribution of the built structure, the effects of the aerodynamic context appear more influential for insulated buildings. Essentially, switching from an exposed to a sheltered building may decrease the energy needs per surface unit of floor due to air infiltration and heat transmission through outer walls by 18% up to 47% according to simulation
22
Laureta, L. V. "Trophic dynamics of a benthic community, with particular reference to the ecological energetics of Corbula gibba (Olivi)." Thesis, University of Liverpool, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381336.
23
Огірко, О. І., та O. I. Ohirko. "Інформаційна технологія для визначення енергетичних характеристик поверхневих шарів металів: дисертація". Thesis, Українська академія друкарства, 2013. http://dspace.lvduvs.edu.ua/handle/1234567890/657.
Анотація:
Огірко О. І. Інформаційна технологія для визначення енергетичних характеристик поверхневих шарів металів: дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.13.06 –інформаційні технології / Огірко Ольга Ігорівна. - Львів: Українська академія друкарства, 2013. - 163 с.Дисертація присвячена розробці інформаційної технології для відбору та опрацювання даних, які характеризують поверхневі шари металів в агресивному середовищі. Розроблено концептуальну модель комп’ютерної інформаційної технології, що передбачає використання фізико-математичних моделей для обчислення та аналізу енергетичних характеристик поверхневих шарів металів в агресивному середовищі. Моделі та відповідні алгоритми орієнтовані на опрацювання великого обсягу вхідних даних та прийняття рішень щодо антикорозійного захисту елементів конструкцій. Розроблено систему генерації програм з операцій теорії секвенційних алгоритмів і вперше застосовано для визначення енергетичних характеристик поверхневих шарiв металів. Удосконалено функціональну структуру інформаційної технології для протикорозійного захисту з використанням даних про енергетичні характеристики поверхневих і міжфазних шарів та активаційних процесів, які характеризують метал і агресивне середовище. Для розв’язання наукової задачі були використані відповідні фізико-математичні моделі, та розроблено модель інформаційної технології діагностики корозійного стану з використанням алгебри алгоритмів. Інформаційна технологія реалізована у вигляді розподіленої модульної програмної системи, яка є результатом розробленої моделі і дозволяє розв’язувати задачі діагностики корозійного стану в елементах металевих конструкцій поліграфічних машин. The thesis is devoted to the development of information technology selection and processing characteristics of the surface layers of metals in hostile environments. The conceptual model of computer information technology corrosive measuring that involves the use of physical and mathematical models for calculating and analyzing energy characteristics of the surface layers of metals in hostile environments. Models focused on processing large amounts of input data and making decisions on corrosion protection of structural elements. Systems generating programs with operations theory sequential algorithms created models for operation sequention – generation system operation, elimination of programs, systems generating programs with the transaction cycle. System generation programs with operations theory sequential algorithms first used to determine the energy characteristics of the surface layers of metals. Improved functional structure of information technology corrosion protection using data on the energy characteristics of surface and interfacial layers and activation processes that characterize metal and aggressive environment and necessary for corrosion protection. In order to solve scientific problems were used appropriate physical and mathematical models, and the model of information technology diagnostic corrosion condition using algebra algorithms. Information technology is implemented as a distributed modular software system that results from the developed model and allows to solve the problem of corrosion diagnosis.
24
Wennberg, Christian. "Energetics of cholesterol-modulated membrane permeabilities. A simulation study." Thesis, Uppsala universitet, Institutionen för cell- och molekylärbiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-147722.
Анотація:
Molecular dynamics simulations were used to study the permeation of four different solutesthrough different cholesterol containing lipid bilayers. In all bilayers the limiting permeationbarrier shifted towards the hydrophobic core, as the cholesterol concentration was increased.Cholesterols reducing effect on the permeation rate was observed, but under certainconditions results indicating an increased permeation rate with increasing cholesterolconcentration were also obtained.
25
Pearson, James Todd. "A comparative study of the energetics of avian reproduction /." Title page, summary and table of contents only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09php361.pdf.
26
Goel, Satyender. "DFT STUDY OF GEOMETRY AND ENERGETICS OF TRANSITION METAL SYSTEMS." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2125.
Анотація:
This dissertation focuses on computational study of the geometry and energetics small molecules and nanoclusters involving transition metals (TM). These clusters may be used for various industrial applications including catalysis and photonics. Specifically, in this work we have studied hydrides and carbides of 3d-transition metal systems (Sc through Cu), small nickel and gold clusters. Qualitatively correct description of the bond dissociation is ensured by allowing the spatial and spin symmetry to break. We have tested applicability of new exchange-correlation functional and alternative theoretical descriptions (spin-contamination correction in broken symmetry DFT and ensemble Kohn-Sham (EKS)) as well. We studies TM hydrides and carbides systems to understand the importance of underlying phenomenon of bond breaking in catalytic processes. We have tested several exchange-correlation functionals including explicit dependence on kinetic energy density for the description of hydrides (both neutral and cationic) and carbides formed by 3d-transition metals. We find M05-2x and BMK dissociation energies are in better agreement with experiment (where available) than those obtained with high level wavefunction theory methods, published previously. This agreement with experiment deteriorates quickly for other functionals when the fraction of the Hartree-Fock exchange in DFT functional is decreased. Higher fraction of HF exchange is also essential in EKS formalism, but it does not help when spin-adapted unrestricted approach is employed. We analyze the electron spin densities using Natural Bond Orbital population analysis and find that simple description of 3d electrons as non-bonding in character is rarely correct. Unrestricted formalism results in appreciable spin-contamination for some of the systems at equilibrium, which motivated us to investigate it further in details. In order to correct the spin contamination effect on the energies, we propose a new scheme to correct for spin contamination arising in broken-symmetry DFT approach. Unlike conventional schemes, our spin correction is introduced for each spin-polarized electron pair individually and therefore is expected to yield more accurate energy values. We derive an expression to extract the energy of the pure singlet state from the energy of the broken-symmetry DFT description of the low spin state and the energies of the high spin states (pentuplet and two spin-contaminated triplets in the case of two spin-polarized electron pairs). We validate our spin-contamination correction approach by a simple example of H2 and applied to more complex MnH system. Ensemble KS formalism is also applied to investigate the dissociation of C2 molecule. We find that high fraction of HF exchange is essential to reproduce the results of EKS treatment with exact exchange-correlation functional. We analyze the geometry and energetics of small nickel clusters (Ni2-Ni5) for several lowest energy isomers. We also study all possible spin states of small nickel cluster isomers and report observed trends in energetics. Finally we determine the geometry and energetics of ten lowest energy isomers of four small gold clusters (Au2, Au4, Au6, and Au8). We have also investigated the influence of cluster geometry, ligation, solvation and relativistic effects on electronic structure of these gold clusters. The effect of one-by-one ligand attachment in vacuum and solvent environment is also studied. Performance of five DFT functionals are tested as well; Local Spin Density Approximation (SVWN5), Generalized Gradient Approximation (PBE), kinetic energy density-dependent functional (TPSS), hybrid DFT (B3LYP), and CAM-B3LYP which accounts for long-range exchange effects believed to be important in the analysis of metal bonding in gold complexes and clusters. Our results exhibit the ligand induced stability enhancement of otherwise less stable isomers of Au4, Au6 and Au8. Ligands are found to play a crucial role in determining the 2D to 3D transition realized in small gold clusters. In order to select an appropriate theory level to use in this study, we investigate the effect of attachment of four different ligands (NH3, NMe3, PH3, PMe3) on cluster geometry and energetics of Au2 and Au4 in vacuum and in solution. Our results benchmark the applicability of DFT functional model and polarization functions in the basis set for calculations of ligated gold cluster systems. We employ five different basis sets with increasing amount of polarization and diffuse functions; LANL2DZ, LANL2DZ-P, def2-SVP, def2-TZVP, and def2-QZVP. We obtain NMe3 = NH3 < PH3 < PMe3 order of ligand binding energies and observe shallow potential energy surfaces in all molecules. Our results suggest appropriate quantum-chemical methodologies to model small noble metal clusters in realistic ligand environment to provide reliable theoretical analysis in order to complement experiments.Ph.D.
Department of Chemistry
Sciences
Chemistry PhD
27
Burkoff, Nikolas S. "Statistical approaches to the study of protein folding and energetics." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/66470/.
Анотація:
The determination of protein structure and the exploration of protein folding landscapes are two of the key problems in computational biology. In order to address these challenges, both a protein model that accurately captures the physics of interest and an efficient sampling algorithm are required. The first part of this thesis documents the continued development of CRANKITE, a coarse-grained protein model, and its energy landscape exploration using nested sampling, a Bayesian sampling algorithm. We extend CRANKITE and optimize its parameters using a maximum likelihood approach. The efficiency of our procedure, using the contrastive divergence approximation, allows a large training set to be used, producing a model which is transferable to proteins not included in the training set. We develop an empirical Bayes model for the prediction of protein β-contacts, which are required inputs for CRANKITE. Our approach couples the constraints and prior knowledge associated with β-contacts to a maximum entropy-based statistic which predicts evolutionarily-related contacts. Nested sampling (NS) is a Bayesian algorithm shown to be efficient at sampling systems which exhibit a first-order phase transition. In this work we parallelize the algorithm and, for the first time, apply it to a biophysical system: small globular proteins modelled using CRANKITE. We generate energy landscape charts, which give a large-scale visualization of the protein folding landscape, and we compare the efficiency of NS to an alternative sampling technique, parallel tempering, when calculating the heat capacity of a short peptide. In the final part of the thesis we adapt the NS algorithm for use within a molecular dynamics framework and demonstrate the application of the algorithm by calculating the thermodynamics of allatom models of a small peptide, comparing results to the standard replica exchange approach. This adaptation will allow NS to be used with more realistic force fields in the future.
28
Morganti, Teresa Maria. "In situ direct study of filtration and respiration rate of Mediterranean sponges = Estudio in situ de la filtración y la respiración de esponjas mediterráneas." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/397747.
Анотація:
Sponges play important roles in the functioning of marine ecosystem in which they are abundant. These roles range from stabilizers of substrate, to acting as major link between benthic and pelagic realms by filtering large quantities of water and retaining the particles with high efficiency. Despite sponges have been the focus of much interest in the past years our knowledge on sponge physiology is still poorly understood. This study focused on ecophysiology of five of the most prominent sponge species dwelling the coralligenous community in the NW Mediterranean Sea, and employed an energetic approach to understanding the complex interactions between physiological constrains and seasonal fluctuations of environmental factors experienced by the organism under natural conditions. In this thesis, we contributed to the still limited knowledge of energetic mechanisms that regulate seasonal dynamics and elucidated divergent metabolic profiles between high microbial (HMA) and low microbial (LMA) abundance species accordingly to their different adaptive life strategies. For this purpose we examined the in situ feeding, filtering and respiration activity over annual cycle. Firstly, we started by developing a system for quantifying the particulate and dissolved compounds processed by sponges under natural conditions. In terms of feeding, we observed that all species retained plankton at high efficiency and DOC was the main source of carbon. However, the nitrogen fluxes showed a marked different trophic niche between the two groups: HMA species mostly relied on dissolved compound as main source of N, while LMA solely relied on particulate fractions. Interestingly, natural variation of sponge pump did not follow natural temperature changes. During the period of maximum temperature the sponge pump did not reach its maximum values, suggesting that intrinsic mechanism as a decrease in choanocytes during reproductive cycle may regulate this metabolic process. On the other hand respiration clearly showed a seasonal pattern following natural temperature fluctuation. Combined, these results allowed us to estimate the overall energy budget, which appeared to be regulated by an increase of energy demand in summer as well as the availability of dissolved organic carbon fraction in the water column. Our result also showed different limited energetic profiles between HMA and LMA species accordingly to their different feeding strategies. LMA species appeared to procure sufficient energy to meet metabolic requirements for maintenance and growth by filtering suspended particulates, and dissolved fraction represented an additional input of carbon when available. On the contrary the heterotrophic nutrition in the natural environment may be insufficient to meet basal metabolic requirements in HMA species, suggesting other metabolic pathways as relevant for the energy budget of these species.Les esponges juguen un paper important en el funcionament del ecosistemes marins on hi son abundants. Les funcions atribuïdes a les esponges son molt diverses i inclouen entre altres actuar com estabilitzadores del substrat, així com fer de lligam entre la columna d'aigua i el bentos en l'anomenat acoblament bento-pelàgic; aquest procés te lloc mitjançant una captura eficient de partícules i el retorn de compostos modificats per l'activitat metabòlica de les esponges. Tot i que les esponges han estat punt de mira en l'interès científic durant els darrers anys, s'identifica encara una manca de coneixement de la seva fisiologia. Aquesta tesi es centra en l'ecofisiologia de cinc especies d'esponges emblemàtiques del coral·ligen Mediterrani. Utilitzant una aproximació energètica s'ha avaluat les interaccions entre possibles limitacions fisiològiques en les esponges i fluctuacions estacionals en els paràmetres ambientals a les que estan sotmeses en la natura. En aquesta tesi contribuïm al coneixement encara limitat dels mecanismes energètics que regulen la dinàmica estacional de les esponges així com en aportar informació sobre el perfils metabòlics divergents entre les esponges amb alta (HMA) i baixa (LMA) concentració de microbis associats segons les seves diferents estratègies adaptatives. Amb aquest objectiu examinem in situ l'alimentació, la filtració i la respiració al llarg d'un cicle anual. En primer lloc comencem desenvolupant un sistema que permeti la quantificació de compostos particulats i dissolts processats per les esponges en el seu habitat natural. En termes d'alimentació hem observat que totes les especies retenen molt eficientment el plàncton i que el carboni orgànic dissolt (DOC) es la seva principal font de carboni. Respecte als fluxos de nitrogen s'ha trobat diferents nínxols tròfics entre especies amb diferent concentració de microbis associats: especies HMA depenen bàsicament de compostos dissolts com a font de nitrogen mentre que les especies LMA depenen de la fracció particulada. Curiosament, la variació en la tassa de filtració al llarg de l'any no segueix el cicle de temperatura. El període de temperatura mes alta no va coincidir amb les tasses de filtració mes elevades suggerint que altres mecanismes intrínsecs a les esponges, com pot ser una disminució en la quantitat de coanòcits durant el cicle de reproducció, podrien regular el metabolisme de les esponges. Per altra banda la respiració ha mostrat un patró estacional seguint les fluctuacions naturals de la temperatura. La combinació d'aquests resultats ens ha permès estimar el balanç energètic global, aquest sembla estar regulat per un increment en la demanda energètica a l'estiu coincidint amb un increment en la disponibilitat de carboni orgànic dissolt en la columna d'aigua. Els nostres resultats també han mostrat diferencies en el perfil de limitació energètica entre especies HMA i LMA coincidint amb les seves diferents estratègies en la captura de nutrients. Les especies LMA sembla que obtenen suficient energia per cobrir el seu metabolisme a partir de la matèria particulada de l'aigua, essent la fracció dissolta un aportació addicional de carboni. Contràriament en especies HMA la nutrició heterotròfica sembla ser insuficient per cobrir els requeriments metabòlics basals suggerint altres vies metabòliques rellevants per cobrir el balanç energètic.
29
West, Brandi. "Study of the Energetics of Polycyclic Aromatic Hydrocarbons and their Interstellar Implications." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31552.
Анотація:
Interstellar chemistry has been a growing field over the last several decades. There is particular interest on the nature and reactivity of interstellar molecules; most notably that of polycyclic aromatic hydrocarbons (PAHs). My thesis focused on the kinetics of unimolecular dissociation of small PAH and PAH-like molecules under interstellar conditions. PAHs (naphthalene (NAP), anthracene (ANT) and pyrene (PYR)), some dihydro- equivalents (1,2-dihydronapthalene (DHN) and 9,10-dihydrophenanthrene (DHP)) and a few other small aromatic organic molecules (indene (IND), ethynylbenzene (EB), propynylbenzene (PB) and benzocyclobutene (BCB)) were studied using imaging photo-electron photo-ion coincidence spectroscopy (iPEPICO) and electron impact mass spectrometry (MS); both mass analyzed ion kinetic energy spectrometry (MIKES) and collision induced dissociation (CID). Experiments were performed at different ionization energies to produce breakdown diagrams for the various fragments. These diagrams are then fit using RRKM theory to determine the zero Kelvin activation energy (E0) and the entropy of activation (Δ‡S); these results are then compared and discussed.
All these molecules were compared in order to try and find any overlying trends which could be applied to their role in the interstellar medium (ISM). It was determined that H loss was the dominant fragmentation channel, as it was the only dissociation channel common to the majority of molecules studied. It was also seen that organic fragment loss (C2H2, CH3 and C4H2) was only observed in smaller molecules which indicates that PAHs are not likely a source of these molecules. The small fragment molecules gave insight into the stability of closed ring structures, such as PAHs, through the comparison of the dissociation of closed and open structures. The dihydro-PAHs, selected as a probe to investigate the proposed catalytic role of PAHs in the formation of molecular hydrogen, yielded very interesting results. It was seen that these molecules would readily undergo isomerisation prior to dissociation. This added an unexpected level of difficulty to the calculations but quickly demonstrated how the presence of additional hydrogen atoms could greatly disrupt the dissociations, as it was not the simple process of removing them as it was originally believed.
The overall trend observed was that it is the structure, not the size, which has the dominating effect on the dissociation. Ions of similar structure behaved similarly, regardless of a change in mass; isomers, however, had radically different behaviours which can only be attributed to their differing molecular conformations. This observation could aid in the understanding of larger PAHs, those which are believed to exist in the ISM, and what role they may play in the chemistry of the universe.
30
Vettore, Nicola [Verfasser]. "Energetics of linear polymerization: a study of amyloid fibril elongation / Nicola Vettore." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1203369840/34.
31
Arini, Ricardo Greber. "Analise energetica e exergetica de um ciclo de refrigeração por compressão de vapor utilizando HC290 em substituição ao HCFC22." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263588.
Анотація:
Orientador: Arai Augusta Bernardez PecoraDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-12T19:26:31Z (GMT). No. of bitstreams: 1 Arini_RicardoGreber_M.pdf: 5502572 bytes, checksum: c19e6a830ce67a88c8959a10cd21aef8 (MD5) Previous issue date: 2008
Resumo: Este trabalho teve como objetivo analisar experimentalmente um sistema de refrigeração por compressão de vapor operando com o hidrocarboneto propano (R290) em substituição ao refrigerante HCFC22, visando atender as necessidades do mercado atual de refrigeração comercial, que busca alternativas que atendam à exigência de substituição gradual dos refrigerantes hidroclorofluorcarbonados (HCFC's). O estudo foi realizado em um mini-tanque de resfriamento de leite, produzido comercialmente para operar com o refrigerante 22. Foram analisadas as influências da temperatura do fluido no interior do tanque e da temperatura do ar de resfriamento do condensador sobre parâmetros de desempenho do ciclo de compressão como: pressão de condensação, pressão de evaporação, coeficiente de desempenho, efeito frigorífico, trabalho de compressão, taxa específica de transferência de calor no condensador, temperatura do refrigerante na descarga do compressor e volume específico do refrigerante na aspiração do compressor. Além da análise energética, este trabalho apresenta a análise exergética do ciclo operando com R290 em comparação com o ciclo operando com R22. As medidas experimentais foram realizadas em condições de regime permanente, verificado quando não se observaram variações significativas na temperatura do refrigerante em diversos pontos do ciclo. A temperatura do fluido do tanque e a temperatura do ar de resfriamento do condensador foram mantidas constantes através de resistências elétricas imersas na água contida no tanque e na entrada do condensador, respectivamente. A análise de resultados mostrou que é possível a substituição do refrigerante R22 pelo R290 no sistema estudado, sendo observado que o sistema operando com R290 apresentou desempenho energético equivalente ao apresentado pelo R22. Foi verificado que a eficiência exergética do sistema operando com R290 foi igual ou superior à obtida com R22. Observou-se ainda um menor consumo de energia elétrica pelo sistema nos testes de resfriamento utilizando propano como refrigerante.
Abstract: In order to meet the requirements of the commercial refrigeration market, which demands for alternatives to substitute gradually the use of refrigerants such as hydroclorofluorcarbons (HCFC's), this research had the aim to analyze experimentally a mechanical vapor-compression refrigeration system operating with hydrocarbon propane (R290) as an alternative for R22. This study was made in a small tank for milk refrigeration, commercially built to operate with the refrigerant HCFC22. It was analyzed the influences of the factors: temperature of the water inside the tank and temperature of the cooling air at the entrance of the condenser, on the performance of the compression cycle. The following parameters were determined: evaporating pressure, condensing pressure, coefficient of performance, refrigeration capacity per unit mass of refrigerant flow, compression work, rate of heat transfer per unit mass of refrigerant flow at the condenser, refrigerant discharge temperature at the compressor outlet and specific volume of the refrigerant at the compressor inlet. In order to verify which refrigerant fluid realizes the best usage of the available work, it was made, besides an energetic analysis, a comparative exergetic analysis of the cycles. The experimental measures were made at steady state conditions, verified when no significant variations of refrigerant temperatures in several parts of the cycle were observed. The water temperature inside the tank and the air temperature, at the entrance of the condenser, were kept constant by using electrical resistances. The analysis of the results showed that R290 could be used as a substitute for R 22 to the studied system. It was observed that the energetic performance of the system working with R290 was better than the obtained using R22. The exergetic efficiency of the system using R290 was equal or greater than that obtained using R22. A less electrical energy consumption was obtained in the cooling experiments using R290 as refrigerant.
Mestrado
Termica e Fluidos
Mestre em Engenharia Mecânica
32
Landelle, Arnaud. "Experimental and numerical study of transcritical Organic Rankine Cycles for low-grade heat conversion into electricity from various sources." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI090/document.
Анотація:
Le Cycle Organique de Rankine (abrégé ORC de l’anglais Organic Rankine Cycle) est une technologie permettant la conversion de chaleur basse température en électricité. L’ORC transcritique a été identifié comme une solution prometteuse pour la valorisation de la chaleur fatale. Cependant, peu d’installations expérimentales ont permis de confirmer ces performances. Ce travail de thèse présente le fonctionnement et l’optimisation d’ORC sous-critique et transcritique pour la conversion de chaleur basse température en électricité à partir de différentes sources. Premièrement, les contextes thermodynamique et technologique de l’ORC sont présentés. Des critères de performance énergétiques et exergétiques sont définis et appliqués à une base de données d’installations expérimentales afin d’exposer l’état de l’art actuel des ORC. Deuxièmement, les outils numériques et expérimentaux, spécifiquement développés ou utilisé pour ces travaux, sont présentés. Trois installations expérimentales d’ORC transcritique complet ou incomplet fournissent les données expérimentales. Différents modèles numériques sont utilisés : sous l’environnement Matlab pour la modélisation en permanent, l’analyse des données expérimentales et l’analyse énergétique/exergétique ; L’environnement Modelica/Dymola pour l’analyse des transitoires et de la dynamique du système. Dans un troisième temps, ces différents outils sont utilisés pour étudier quatre différentes problématiques : - Le fonctionnement de la pompe de circulation est étudié, d’un point de vue énergétique et volumétrique. Des modèles semi-empiriques et des corrélations de performance sont présentés. - Les transferts thermiques en supercritique sont examinés, en local et en global. Les coefficients de transfert thermique sont comparés avec différentes corrélations de la littérature. - L’influence de la charge de réfrigérant sur les performances et le comportement de l’ORC est analysée. La charge optimale est estimée pour différentes conditions de fonctionnement et des mécanismes de régulation de la charge sont présentés. - Les performances énergétiques et exergétiques de l’ORC sont comparées avec la base de données. Une analyse exergétique du procédé a permis d’identifier des voies d’améliorationThe Organic Rankine Cycle (ORC) is a technology used for low-grade thermal energy conversion into electricity. Transcritical ORC has been identified as a solution for efficient waste heat recovery. However, few experimental tests have been conducted to confirm the interest of transcritical ORC and investigate its operational behaviors. The work presented focuses on the operation and the optimization of subcritical and transcritical Organic Rankine Cycles for low-grade heat conversion into electricity from various heat sources (solar, industrial waste heat). First, the thermodynamic framework of ORC technology is presented. Energetic and exergetic performance criteria, appropriate to each type of input source, are introduced and selected. The criteria are later applied to a database of ORC prototypes, in order to objectively analyze the state-of-the-art. In a second step, the experimental and numerical tools, specifically developed or used in the present thesis, are presented. Three subcritical and transcritical ORC test benches (hosted by CEA and AUA) provided experimental data. Numerical models were developed under different environments: Matlab for steady-state modeling, data processing and energy/exergy analysis. The Modelica/Dymola environment for system dynamics and transient operations. Lastly, the different tools are exploited to investigate four different topics: - The ORC pump operation is investigated, both under an energetic and volumetric standpoint, while semi-empirical models and correlations are exposed. - Supercritical heat transfers are explored. Global and local heat transfer coefficients are estimated and analyzed under supercritical conditions, while literature correlations are introduced for comparison. - Working fluid charge influence over the ORC performance and behavior is investigated. Optimal fluid charge is estimated under various operating conditions and mechanisms for charge active regulation are exposed. - ORC system performances and behavior are discussed. Through both an energetic and exergetic standpoint, performances are compared with the state-of-the-art, while optimization opportunities are identified through an exergetic analysis
33
TRIBUIANI, CHIARA. "Analisi sperimentale di componenti edilizi per la riqualificazione energetica degli edifici." Doctoral thesis, Università Politecnica delle Marche, 2021. http://hdl.handle.net/11566/291054.
Анотація:
Oggetto principale del progetto di ricerca è stata la valutazione del comportamento energetico di componenti edilizi attraverso l’analisi sperimentale in situ con la realizzazione di mock up configurati per lo scopo.
In prima battuta, lo studio si è concentrato sulle problematiche inerenti ai consumi energetici estivi, il comfort interno e la salubrità degli ambienti prefiggendosi l’obiettivo di analizzare nuove strategie per l’ottimizzazione dell’involucro edilizio. La tematica dell’isolamento termico è stata, quindi, declinata sotto diversi aspetti: tipologia dei materiali isolanti e le loro caratteristiche chimico-fisiche, tipologia delle strutture edilizie che necessitano di isolamento, principali parametri termici da considerare e infine la traduzione, in termini di sperimentazione in sito, di un modello comparativo tra involucri termici su una struttura esistente fortemente inerziale ma priva di isolamento termico: mock up realizzato a Fabriano.
La necessità di raggiungere standard energetici sempre più stringenti si è generalmente tradotta con la scelta e l’utilizzo di materiali isolanti con alte prestazioni per coibentare le pareti dei nostri edifici. Una corretta valutazione dei vantaggi e degli svantaggi legati a questa tecnica costruttiva è della massima importanza al fine di comprendere al meglio il comportamento termico delle strutture opache. Pertanto, la ricerca portata avanti, riporta i dati sperimentali e analitici ottenuti dallo studio di una parete ad elevata inerzia termica coibentata con due diversi strati isolanti esterni (metodologia in gergo definita come isolamento “a cappotto”) per soddisfare i requisiti nZEB italiani sulla resistenza termica e focalizzandosi sulle problematiche nell’ambito del clima mediterraneo.
Infatti, il surriscaldamento degli ambienti interni e, quindi, l'uso eccessivo dei sistemi di raffrescamento rappresenta uno dei principali problemi sia per la salute degli occupanti che per i consumi energetici, in particolar modo durante il periodo estivo. Ne consegue che, al fine di limitare questo problema, è necessaria una progettazione appropriata e/o un adeguamento energetico dell'involucro edilizio che utilizzi un approccio globale e sinergico.
Altro argomento di ricerca, seguito parallelamente al primo, è stato lo studio dei cool materials da applicare in sistemi di raffrescamento passivo degli edifici declinando la tecnica del cool roof alle facciate degli edifici. L’obiettivo dello studio è stato quello di valutare gli effettivi benefici che i cool materials possono avere una volta applicati su pareti verticali, al posto delle tradizionali vernici per esterni, e valutarne la convenienza in termini di costi-benefici-durabilità. Questi materiali possono contribuisce alla riduzione della temperatura superficiale dell’agglomerato abitativo grazie ad un migliore bilancio energetico relativo alle superfici in gioco favorendo la mitigazione dell’effetto di isola di calore urbana. Inoltre, l’utilizzo di pareti con corrette stratigrafie e il giusto posizionamento dell’isolamento con materiali che rispondano a condizioni al contorno dinamiche, soprattutto nei climi Mediterranei come il nostro, possono rappresentare una risposta alle problematiche riguardanti il miglioramento dell’efficienza energetica del nostro patrimonio edilizio. Il progetto di ricerca sui cool materials ha previsto una fase preliminare di studio dei materiali, formulazione delle pitture sperimentali e, infine, la preparazione del mock up sul quale installare i pannelli da monitorare durante il periodo estivo.
Riassumendo, la problematica della riqualificazione degli edifici rispetto all’isolamento estivo ha affrontato, principalmente, i seguenti argomenti:
• l’inerzia termica e la sua relazione con l’isolamento termico dell’involucro nel periodo estivo;
• lo studio dei materiali e la loro sperimentazione in condizioni reali, ovvero in regime dinamico;
• l’applicazione sperimentale dei cool materials sulle pareti verticali esterne per valutarne l’efficacia in termini di contenimento delle temperature superficiali.The main object of the research project was the evaluation of the energy behavior of construction components through in situ measurement and experimental analysis with dedicated mock-up. At first, the study has focused on issues related to energy consumption over the summertime, indoor comfort’s situations and environment’s salubrity with the aim of analysing new strategies towards building envelope’s upgrade. Therefore, the topic of thermal insulation has been listed into different aspects: the type of insulating materials and their chemical-physical characteristics, the type of building structures that require insulation, the main thermal parameters to be considered within the research and, at last, the translation, in terms of on-site test, of a comparative model between several thermal envelopes applied on a highly inertial structure lacking of thermal isolation: mock up made in Fabriano. The use of high-performance insulating materials to insulate the building walls is the necessary consequence to achieve the higher strict energy standards. The urgent need of reaching higher energetic standards has brought to choosing high-performance isolating materials to insulate buildings. A correct evaluation of pros and cons of this specific construction technique is extremely fundamental in order to achieve a better understanding of opaque structures thermal behaviour’s. Perhaps, the current research reports experimental and analytical data obtained from the study of a high thermal inertia surface insulated with two different external isolating layers, to meet the Italian nZEB requirements on thermal resistance and focusing on set of problems caused by the Mediterranean climate conditions. In fact, the indoor environment overheating and, consequently, the excessive use of cooling systems represents one of the main problems both for the occupants’ health and for energy consumption, especially during the summertime. It follows that, in order to decrease the problem, a global and synergistic approach is necessary to design energy efficient building envelopes. Another topic of the research, in line with the first one covered, has been conducted on studying cool materials to be applied to passive cooling techniques with the application of cool roof technique to the building facades. The aim of the study was to assess the benefits of those materials when applied to vertical envelopes instead of traditional outdoor coatings and evaluate their convenience in terms of costs-benefits-durability. These materials can contribute to exterior’s temperature reduction of the housing agglomeration thanks to a better energy balance of the surfaces, facilitating the mitigation of the urban heat island effect. Furthermore, resolutions to the problems concerning the energy improvement of our building heritage can be represented by the use of correct stratigraphy walls and the right placement of the insulating materials that respond to dynamic boundary conditions, especially in Mediterranean climate. The research project on cool materials involved a preliminary phase of the materials study, the formulation of the experimental paints and, at last, the mock up preparation on which to install the panels to be monitored over the summertime period. In summary, the problem of building energy upgrading in regard to summer insulation is focused on the main following topics: • thermal inertia and its relationship with the thermal insulation of the envelope over summertime period; • the study of materials and their experimentation in real conditions, or rather in a dynamic regime; • the experimental application of cool materials on external vertical walls in order to evaluate their beneficial impact on surface’s temperature.
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Drechsel, Nils Jan Daniel 1980. "Development of a multiscale protocol for the study of energetics of protein dymanics." Doctoral thesis, Universitat Pompeu Fabra, 2013. http://hdl.handle.net/10803/125071.
Анотація:
Multiscale Molecular Dynamics is a popular trend in the field of computational chemistry and physics. Coarse-grained force-fields have been around for years, and used independently, but used cooperatively with all-atom force-fields combines their advantages and cancels their disadvantages. This seems to be the case, however, only when they are both compatible. In this thesis, a Multiscale Molecular Dynamics Protocol is introduced, based on earlier work by Benjamin Messer, Z. Fan, Arieh Warshel, and in other parts by Christopher Fennel and Ken Dill. The protocol consists of the following tool-set:
• A parametrization machinery that created a new coarse-grained force-field named AmberCG.
• A multiscale thermodynamic cycle utilized within a free energy perturbation context to cooperatively use the best of coarse-grained and all-atom force-fields.
• A collective variable that performs a linearization of the phase space to improve separation of product and reactant states.
• A new algorithm to calculate functional quantities on spheres bounded by complicated solvent accessible surface areas - which as a special case calculates the amount of solvent accessible surface area.
• A novel algorithm based on simple one dimensional Depth-Buffers, to identify atoms which actively form the boundary of the solvent accessible surface areas.
Executing the protocol involves the following steps:
1. Construction of a coarse-grained force-field, based on an all-atom force-field. This involves setting up coarse-grained potentials and optimization of their parameters against selected reference structures and conformations.
2. Parametrization of a solvation model which is compatible to the force-field.
3. Usage of the coarse-grained force-field to sample the conformational space of a reaction.
4. Correction of the coarse-grained results with an all-atom force-field.
5. Analysis of the results using appropriate collective coordinates.
6. Reiteration until accuracies are met.
Alternatively, instead of using the methods in the protocol, they
can be utilized stand-alone. They simplify calculations, thus provid-
ing speed-ups, while at the same time aiming to maintain or improve
accuracy. Of course, there is no free lunch, and often the methods will
include inaccuracies that exceed an acceptable threshold. However, the
multiscale protocol is meant to be seen as an iterative technique, in
which deficiency can be detected, and the protocol adjusted to restore
balance.Las simulaciones de dinámica molecular multiescala (Multiscale Molecular Dynamics) son una tendencia al alza en el sector de la Química y la Física computacionales. Los coarse-grained force-fields o campos de fuerza de grano grueso han existido desde hace años, utilizados de forma independiente, y también en cooperación con all-atom force-fields o campos de fuerza de todos los átomos dónde se combinan sus ventajas y cancelan sus desventajas. En este último caso sólo es cierto cuando los dos force-fields son compatibles. En esta tesis, introduzco un protocolo de Multiscale Molecular Dynamics basado en parte a trabajos anteriores de Benjamin Messer, Z. Fan, Arieh Warshel, y también en los de Christopher Fennell y Ken Dill. El protocolo consiste el siguiente conjunto de herramientas: 1. Un método de parametrización con cuál creé un nuevo coarse-grained force-field llamado AmberCG. 2. Un ciclo termodinámico multiescala utilizado en un contexto de perturbación de energía libre para usar cooperativamente el mejor de los coarse-grained force-fields y el de los all-atom force-fields. 3. Una variable colectiva que realiza una liberalización del espacio de fases para mejorar la separación de los estados de productos y reactivo. 4. Un nuevo algoritmo para calcular las cantidades funcionales en esferas limitadas por complicadas superficies accesibles al solvente - que como un caso especial calcula la cantidad de superficie accesible a solvente. 5. Un nuevo algoritmo basado en un buffer de profundidad, para identificar los átomos que forman activamente el límite de las superficies accesibles al solvente. La ejecución del protocolo implica los siguientes pasos: 1. Construcción de un coarse-grained force-field, basado en un all-atom force-field. Esto implica la creación de potenciales coarse-grained y la optimización de sus parámetros contra las estructuras de referencia seleccionados y sus conformaciones. 2. Parametrización de un modelo de solvatación compatible con el force-field. 3. Uso del coarse-grained force-field para muestrear el espacio con formacional de una reacción. 4. La corrección de los resultados coarse-grained con un all-atom force-field. 5. Análisis de los resultados utilizando coordenadas colectivas adecuadas. 6. Repetición hasta alcanzar las precisiones deseadas. Alternativamente, los métodos del protocolo pueden ser utilizados de forma independiente. Esto simplifica los cálculos y procura mantener, si no mejorar, la precisión. Sin embargo, todo tiene un coste y con frecuencia, los métodos incluirán inexactitudes que superarán el umbral aceptable. Aun y así, el protocolo multiescala es una técnica iterativa, en la que la deficiencia puede ser detectada, y el protocolo ajustado para restablecer el equilibrio.
35
Shah, Shafqat Hussain. "Ab initio study of polarization, defect energetics and strain in complex ferroelectric materials." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611711.
36
Krishnamurthy, Sriram. "Feasibility study on making Van Maanenblok a near zero energy building urban neighbourhood." Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150712.
Анотація:
The rapid exhaustion of the finite reserves of fossil-fuels adds to the woes on all walks of the society, and especially on the policy-makers, scientists and engineers to devise means to mitigate the consequences. Reducing energy demand and grid-dependency by decentralized energy production can help improve energy security of a nation. A holistic approach to achieve these goals in the building sector could be through a shift towards fostering near zero-energy communities. This project is an initiative taken by the residents in Van Maanenblok, an urban residential block constructed in early 1930’s and situated at the heart of North-Rotterdam, to try to achieve self-sustainability in terms of energy consumption of the block through renovation. The objective of this study is to analyze the energy consumption of the block over the past three years and using the ‘Trias Energetica’ approach, investigate the extent to which self-sustainability is possible. This study also includes an overview on financial feasibility of this initiative together with identification of innovation opportunities. Passive energy reduction measures such as insulation, LED lighting-retrofits have been explored. Active renewable energy systems (RES) like solar photovoltaic (PV) systems, micro-windmills were designed and sized. Also, energy potential from Organic Fraction of Municipal Solid Waste (OFMSW) from within the block, and use ground-source heat pump to meet thermal energy has been investigated. The aforementioned technologies have been compared over certain financial parameters like net present value (NPV), payback period (PBP), and levelised cost of energy (LCOE) based on installation costs obtained from actual figures quoted by the installers and also general indicative market figures. Results of the study indicate that nearly 54% of present gas demand and 9% of electricity demand can be reduced by passive energy reduction measures alone. It would be possible to meet 42% and 54% of reduced electricity and gas demand respectively from RES. User-behaviour plays an important role in energy consumption and social factor largely determines the metamorphosis of projects with such complex setup. Renovation projects towards near zero energy buildings opens up several innovative opportunities and extended benefits to various actors, however stimulus from government is needed on financial and technical front in order to realize such ambitious initiatives.
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Palmer, Prem. "Structure, Energetics and Reactions of Bisketenes: An Ab Initio and Density Functional Theory Study." Thesis, University of North Texas, 1997. https://digital.library.unt.edu/ark:/67531/metadc501272/.
Анотація:
The effect of varying substituents on structure and energies of bisketenes was studied using ab initio methods. Effect of substituents on ring closing reaction of bisketenes to the corresponding cyclobutenediones was also studied using ab initio methods. One or two of the following substituents were used to study the effect of varying substituents: BH2, CH3, NH2, OH, F, AlH2, SiH3, PH2, SH, Cl. Studies were done at the Hartree-Fock (HF), Møller-Plesset (MP2), and Density Functional Theory (B3LYP) levels of theory using the 6-31G* basis set.
38
Le, navenant Adrien. "Acquisition d’une tolérance aux insecticides en vergers de pommiers et ses conséquences chez une espèce auxiliaire, le forficule Forficula auricularia L Metabolic mechanisms and acetylcholinesterase sensitivity involved to chlorpyrifos-ethyl in the earwig Forficula auricularia An exploratory study of energy reserves and biometry as potential tools for pest management strategiess on the earwig." Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0354.
Анотація:
Dans le contexte Européen visant la réduction de l’utilisation des pesticides, la connaissance des effets des insecticides sur les auxiliaires est une piste novatrice et prometteuse au développement de nouveaux programmes en Production Fruitière Intégrée (PFI). Prédateur généraliste le forficule (perce oreille), Forficula auricularia L., contribue à la lutte biologique grâce à son efficacité sur certains ravageurs tels que les pucerons en vergers de pommiers.Les forficules sont prélevés dans des vergers de pommiers (PACA, France) conduits en agriculture biologique (AB), en Production Fruitière Intégrée (PFI), en agriculture conventionnelle ou dans des vergers ne recevant aucun traitement phytosanitaire. Nos résultats montrent que cet auxiliaire est capable de développer des mécanismes de résistance/tolérance à un insecticide organophosphoré (OP), le chlorpyriphos-éthyl. Après exposition au chlorpyriphos-éthyl à la dose autorisée en vergers, les organismes provenant d’un verger conduit en agriculture conventionnelle sont caractérisés par une faible mortalité. Cette diminution de la mortalité est expliquée par une activité élevée des glutathion-S-transférases et des carboxylestérases, deux enzymes impliquées dans les voies de détoxication, et par une diminution de la sensibilité de l’acétylcholinestérase (cible moléculaire des OP au niveau du système nerveux). L’étude de la sensibilité de l’AChE vis à vis des OP, montre une dichotomie entre les mâles plus sensibles et femelles plus résistantes.Nous nous sommes également intéressés à l’induction des Hsp70 après exposition au chlorpyriphos, pour évaluer les mécanismes de défense cellulaire mis en place. Les résultats, malgré leur grande variabilité, soulignent la différence de sensibilité entre vergers, et entre sexes au sein du même verger. Il est connu que les mécanismes de défense génèrent un coût métabolique important. Nous avons donc analysé la quantité de réserves énergétiques (glucides, lipides et protéines) ainsi que certaines caractéristiques morphologiques chez F. auricularia selon le verger d’origine des forficules. Les perce-oreilles prélevés en vergers conventionnels sont généralement plus petits que ceux provenant des autres vergers. La quantité de réserves dépend des conditions environnementales liées à l’utilisation des pesticides et de la période de prélèvement des forficules en vergers. En particulier la quantité élevée de glycogène observée chez les femelles prélevées à l’automne (deux mois après la fin des traitements) dans les vergers conventionnels, est en accord avec une réallocation des réserves pour la reproduction.Cette étude met en évidence pour la première fois l’acquisition de mécanismes de résistance chez le forficule fortement exposé aux insecticides en vergers conventionnels. Elle ouvre la voie à de nouvelles pistes de recherche sur l’apparition de cette résistance en fonction de la pression anthropique exercée sur un auxiliaire des culturesIn the European context of reducing pesticide use, knowledge of the effects of insecticides on natural enemies is an innovative and promising approach for the development of new Integrated Pest Management (IPM) program. European earwigs Forficula auricularia (Linnaeus) are considered as efficient predators in apple orchards and contribute to the biological control of aphids, leaf rollers and psyllids.Earwigs were sampled in apple orchards in Provence, (South-Eastern France), managed under contrasting strategies: organic, integrated pest management (IPM), conventional, or untreated orchards. Our study underlines the differences in metabolic pathway responses in F. auricularia populations influenced by their historic management strategies. In particular, we have shown that earwigs collected in conventional orchard exhibited lower mortality and higher enzyme activities (glutathion-S-transferases and carboxylesterases) involved in detoxification, compare to organic orchard. A decrease in sensitivity of the acetylcholinesterase (the molecular target of OP insecticides, involved in the nervous system functioning) was also observed in earwigs pre-exposed in the conventional orchard with higher sensitivity of AChE in male compared to female earwigs. We have investigated the induction of Hsp70s as an efficient defense mechanism, which could play an important role in tolerance to insecticide. Our results underlined the differences previously observed depending on management strategy and for a considered orchard, depending on earwig sex.It is well known that insecticide tolerance can be associated with fitness costs. That is why energetic reserves (glycogen, lipids and proteins) and morphological traits have been quantified on earwigs from orchards with different management practices. F. auricularia from conventional orchards were smaller than the other earwigs. Moreover, we have shown that the amount of energetic reserves depended on insecticide use and on the period of sampling. The high glycogen content observed in females collected in conventional orchards, 2 months after the end of treatments, supports a reallocation of reserves to the reproduction.This work brought to light the emergence of resistance to insecticides of the natural enemy F. auricularia, exposed to pesticides in conventional apple orchard
39
Donovan, Edward Robert. "Lactate transport and metabolism: An integrative study of the energetics of brief activity in lizards." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p3190394.
40
Cremonini, Sofia. "Outlining energy retrofitting strategies in the city of Nonantola: defining a proposal for priority guidelines through the study of good practices in Nijmegen, the Netherlands." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Анотація:
In Emilia-Romagna, la legge n.24/2017 obbliga i comuni a adottare il Piano Urbanistico Generale, il quale prevede, al fine di promuovere la rigenerazione urbana, un’approfondita analisi del tessuto urbano esistente e la rilevazione degli edifici che presentano una scarsa qualità in termini di efficienza energetica. Risulta evidente dunque l’elaborazione di nuove azioni coordinate a livello di pianificazione.
L’obiettivo dello studio è la proposta di un set di scenari di rigenerazione e priorità di intervento per la riqualificazione energetica diffusa del Comune di Nonantola. Queste sono elaborate a partire dallo studio di casi applicativi e modelli di governance messi in atto dalla città di Nijmegen (Paesi Bassi), dove la transizione energetica e un tema centrale ed è ben integrata nelle strategie di pianificazione energetica.
Nei primi capitoli, la ricerca si concentra sul caso olandese, delineando i principali attori nel settore abitativo e il quadro legislativo adottato in merito alla transizione energetica. Successivamente, il focus viene spostato sulla città di Nijmegen, dove vengono analizzati sia il sistema di governance che l’amministrazione locale sta implementando sul suddetto tema, sia casi pratici a supporto della ricerca.
La seconda sezione dello studio si sofferma sul caso italiano. Si analizzano in prima istanza le principali problematiche riguardanti la riqualificazione energetica, e in particolare il quadro legislativo urbanistico emiliano-romagnolo, per mettere in luce la necessità di integrare il tema energetico degli strumenti di pianificazione e rigenerazione del territorio. Infine, il caso di Nonantola: si elabora una proposta che consiste nell’analisi del tessuto residenziale costruito in merito a tematiche rilevanti per la riqualificazione energetica, e si definiscono dunque degli areali che determinano alla scala del comparto caratteristiche tipologiche simili, accompagnate da linee guida e priorità di intervento da seguire.
41
Li, Wei. "Study of Cardiac Function and Energetics in Mouse Models of Cardiomyopathies by MRI and NMR Spectroscopy." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1269983160.
42
Barker, Alan Robert. "The study of muscle metabolism in young people using 31P-magnetic resonance spectroscopy." Thesis, University of Exeter, 2008. http://hdl.handle.net/10036/42087.
Анотація:
The purpose of this thesis is to extend understanding of the muscle metabolic responses of children and adolescents during exercise using the non-invasive technique of 31P-magnetic resonance spectroscopy (31P-MRS). The first experimental paper examined the reliability of measuring parameters of muscle metabolism in 11-12 year old children over three exhaustive incremental tests using a single-legged quadriceps ergometer. Exercise performance (peak power: ~ 10% coefficient of variation [CV]) and metabolic variables (muscle phosphate and pH intracellular thresholds [IT]: ~ 10% CV, and pH: ~ 1% CV at exhaustion) demonstrated good reliability, whereas the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) at exhaustion had poor reproducibility (~ 50% CV). The second paper examined the influence of age and sex on the muscle metabolic responses during incremental exercise in 9-12 year old children and young adults. The Pi/PCr and pH responses before and at the ITs were independent of age and sex, although during exercise above the ITs, the anaerobic energy contribution (increase in Pi/PCr, fall in pH) was higher in adults than children and in females compared with males, indicating an intensity dependence on age- and sex-related differences in muscle energetics. The third paper examined the relationship between the dynamics of muscle PCr, a putative controller of muscle respiration, and pulmonary oxygen uptake (pVO2) in 9-10 year old children during moderate intensity quadriceps and cycling exercise respectively. No differences were found between the PCr and phase II VO2 time constants at the onset (PCr 23 s [SD 5] vs. pVO2 23 s [SD 4]; P=1.000) or offset (PCr 28 s [SD 5] vs. pVO2 29 s [SD 5]; P=1.000) of exercise, suggesting an age-related slowing of the phosphate linked controller(s) of mitochondrial oxidative phosphorylation may underlie the faster pVO2 kinetics found in children compared to adults. The final experimental chapter tested this hypothesis, but no age or sex related differences were found in the PCr kinetic time constant at the onset (boys: 21 s [SD 4]; girls: 24 s [SD 5]; men: 26 s [SD 9]; women: 24 s [SD 7], P>0.200) or offset (boys: 26 s [SD 5]; girls: 29 s [SD 7]; men: 23 s [SD 9]; women: 29 s [SD 7], P>0.070) of exercise. In conclusion, this thesis has demonstrated that muscle metabolic parameters determined by 31P-MRS are suitable for the study of developmental exercise metabolism. During exercise below the metabolic ITs, the phosphate-linked regulation of muscle respiration is comparable between children and adults, although during exercise above the ITs children are characterised by a lower ‘anaerobic’ energy turnover than adults, indicating an age-related modulation of metabolic control during high intensity exercise.
43
NAPOLITANO, Davide Ferdinando. "Progettazione energetica ed ambientale degli edifici: studi sull'ottimizzazione multi-obiettivo, dal singolo edificio al distretto." Doctoral thesis, Università degli studi di Bergamo, 2022. http://hdl.handle.net/10446/207091.
44
Taylor, Shaun. "A computational study of the stagnation phase in inertial confinement fusion : hotspot energetics, diagnostics, and burn propagation." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/24688.
Анотація:
This thesis studies stagnating ICF capsules. The work is theoretical, with numerical modelling carried out primarily using a 3D multi-physics hydrocode, Gorgon. Simulations of NIF-relevant ICF stagnations are generated from the output of a 1D Hydra NIF post-shot simulation of shot N120205, with an inherently 3D perturbation imposed in the velocity field to generate asymmetries. The simulations are used to develop a detailed phenomenology of the effect of perturbations from spherical symmetry on the energy balance of the hotspot at stagnation. The main effect is an increase in the fluid velocity at the hotspot edge before the time of peak temperature, which results in early thermalisation of kinetic energy and additional compression early in time. The increase of the perturbed target's surface area above 4πR² is found to increase the thermal conduction rate. An inefficiency of thermalisation of kinetic enegy is caused by asymmetries in the ram pressure. The combination of these effects makes it possible for the yield to be reduced to experimental levels in the simulations purely by perturbation of an all-DT system. In order to study the energy balance, an accurate analytic model of the hotspot energy source terms in unperturbed targets is developed by taking advantage of the self-similar temperature profile the hotspot converges upon. This is an improvement upon 0D models such as that of Widner [1]. In particular, the thermal conduction loss is significantly lower when the thermal conductivity at the hotspot edge is used, and the 'ideal ignition temperature' is found to be lower when the ion and electron species are in equilibrium. The diagnostic signatures of hotspot asymmetries are investigated by generating synthetic diagnostic data from the 3D simulations. It is found that stagnation-phase perturbations of mode number l≳6 with amplitudes large enough to reduce the yield to experimental levels are not visible on the currently available NIF diagnostics, or are able to alias as perturbations of lower mode number. Comparisons are also made between the P0 as measured from X-ray images with the physical hotspot radius, and the neutron spectrum width with the burn-averaged and mass-averaged hotspot temperatures, including the effects of motion Doppler broadening. The effect of alpha particle transport on the burn process is investigated using the 1D Lagrangian code Medusa by comparing an accurate model of the alpha particle species with models that make various assumptions about the particle kinetics. The fraction of fusion energy deposited within the burning region χ is related empirically to the properties of the hotspot, which allows alpha particle transport to be included as a loss term in the energy balance model. Alpha transport in 3D perturbed hotspots is investigated by post-processing Gorgon data, which finds that perturbed targets have significantly increased fusion energy loss relative to equivalent unperturbed targets.
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Achilli, Isabella. "Study of a conventional Savonius rotor and optimization of a helical prototype." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15339/.
Анотація:
The aim of this Master Thesis is to study numerically the aerodynamic performance of two small examples of horizontal axis domestic wind turbines: a conventional Savonius rotor, designed and built by a group of students of the Polytech of Tours (France), and its optimization, a helical Savonius rotor. In the first research project, the exploration is conducted even experimentally, testing the turbine in a wind tunnel present in the Polytech.
The numerical investigation is carried out by the use of a software based on Computational Fluid Dynamics named Star CCM+, which helps studying the main fluid dynamics aspects as flow velocity, pressure and coefficients of performance.
The second project consists in a helical Savonius rotor: according to the literature, the helical shape, comparing with the conventional Savonius rotor, usually shows better performances. After the 3D design on Catia, the turbine was printed using the 3D printer, on a reduced scale. CFD simulations allow to study the fluid dynamic features.
Afterwards, thanks to a comparison between the two Savonius models, the performance enhancement of the new one is shown, together with a practical understanding gained of the parameters influencing aerodynamics the most.
By means of the simulations, the helical rotor presents a power coefficient of 10%, which is better than the one of the conventional rotor, found at 7% for the same Tip Speed Ratio. Consequently, even the power produced by the new turbine, resulted to be better than the conventional windmill.
46
Montanari, Luca. "Surface Plasmon Induced Luminescence as a Tool for Study of the Ageing of Polymeric Materials." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13361/.
Анотація:
Lo scopo della presente tesi, svolta presso il Laboratorio LAPLACE di Tolosa, è quello di indagare sulle proprietà ottiche di campioni composti da un substrato di materiale polimerico (bi-axially oriented polyprophilene, BOPP) ricoperto con diversi tipi di elettrodi principalmente tramite misure di elettroluminescenza e di comprendere come queste siano legate al suo deterioramento e invecchiamento
Nella prima parte della tesi, verranno illustrate le misure effettuate su due diverse strutture MIM (metal-insulator-metal), la prima ottenuta utilizzando oro e la seconda utilizzando ITO come elettrodi.
Nella seconda parte, invece, le misure sono state effettuate su campioni multistrato contenenti nano compositi a base di argento, ricoperte con uno strato di ITO che fungerà da elettrodo.
Le misure sulla prima tipologia di campioni hanno evidenziato la presenza di due componenti principali nelle emissioni dovute a elettroluminescenza, una prodotta dal materiale bulk (BOPP) e una scaturita dall’interazione tra il substrato e l’elettrodo metallico, grazie al coinvolgimento dei plasmoni di superficie.
Lo scopo della seconda parte della tesi è quello di comprendere l’effetto che le particelle di argento potrebbero avere sui plasmoni superficiali e sulle emissioni luminose dovute a elettroluminescenza. I risultati ottenuti su questi campioni hanno evidenziato un livello di luce prodotto da elettroluminescenza incredibilmente maggiore rispetto ai campioni aventi ITO e oro come elettrodi.
In conclusione l’impatto delle nano particelle di argento sulle emissioni per elettroluminescenza da BOPP possono essere molteplici e saranno necessari ulteriori studi per comprendere in modo dettagliato tale meccanismo. L’effetto mostrato qui potrebbe risultare molto utile per capire meglio l’elettroluminescenza nei materiali polimerici isolanti da un lato e dall’altro le proprietà foto-fisiche delle nanoparticelle metalliche.
47
Sýkora, Martin. "Studie připojitelnosti výrobny." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219019.
Анотація:
It is necessary to judge the influences of producers on the electric compounds while creating electrical energy or during the regulation of those existing. These analyses are sorted out by so called studies of connectivity. These calculations analyze the degree of connection of the producer and the standby unit during a break-down. The results of this report are several recommendations for creating such unit and succeeding steps leading to secure the stability and safety of the electric compound operation. The aim of this thesis is to discuss about software for PC solutions for static and dynamic network model, to draft power outlet into a network of generating high voltage, to complete a study of connectivity with respect to all the distortion factor, as increased voltage, inrush current at startup, flicker, harmonic currents, interference ripple, contribution to short-circuit current, reactive power control options, and demands for compensation.
48
Battistini, Francesca. "Ventilated façades and thermal coatings compared: environmental product declaration and energy certification in a study case." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20062/.
Анотація:
Since the construction sector is responsible for a large part of environmental pollution all around the world, the current situation is characterized by the need of rethinking the sustainability of existing buildings. My research meets the essence of combining studies of construction technologies from two different angles: the environmental impact of construction materials on one side and the energy consumption for the building management on the other side. Seven types of building technologies between thermal coatings and ventilated façades were considered as options to renovate the hospital of San Benedetto del Tronto: polyurethane, rock wool or glass wool thermal coat and ventilated façade with polyurethane, rock wool or glass wool as insulation and aluminium or ceramic as cladding. SimaPro and EPD (2008) method were performed. By carrying out a comparative analysis of the environmental results for all thermal coatings and ventilated façades studied, glass wool thermal coat had the lowest impact potentials on the environment. By adopting Edilclima software, a second research had been carried out on the quantity of CO2 (global warming impact category) released in the environment by managing the heating system during wintertime. Glass wool thermal coat resulted to be the less impactful on the environment related to the global warming category.
49
Nakajima, Hiroshi. "Study on energetics and particle acceleration on superbubbles and development of X-ray CCD cameras onboard the Suzaku satellite." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/136760.
50
Gonzalez, Ines M. "THEORETICAL STUDY OF THE STRUCTURES AND ENERGETICS OF AROMATIC CLUSTERS: DEVELOPMENT OF RELIABLE AND PRACTICAL THEORETICAL MODELS FOR INTERMOLECULAR POTENTIALS." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164652307.