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1
Quinlan, Angela. "Mechanical Activation Of Valvular Interstitial Cell Phenotype." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-dissertations/355.
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"During heart valve remodeling, and in many disease states, valvular interstitial cells (VICs) shift to an activated myofibroblast phenotype which is characterized by enhanced synthetic and contractile activity. Pronounced alpha smooth muscle actin (alpha-SMA)-containing stress fibers, the hallmark of activated myofibroblasts, are also observed when VICs are placed under tension due to altered mechanical loading in vivo or during in vitro culture on stiff substrates or under high mechanical loads and in the presence of transforming growth factor-beta 1 (TGF-beta 1). The work presented herein describes three distinct model systems for application of controlled mechanical environment to VICs cultured in vitro. The first system uses polyacrylamide (PA) gels of defined stiffness to evaluate the response of VICs over a large range of stiffness levels and TGF-beta 1 concentration. The second system controls the boundary stiffness of cell-populated gels using springs of defined stiffness. The third system cyclically stretches soft or stiff two-dimensional (2D) gels while cells are cultured on the gel surface as it is deformed. Through the use of these model systems, we have found that the level of 2D stiffness required to maintain the quiescent VIC phenotype is potentially too low for a material to both act as matrix to support cell growth in the non-activated state and also to withstand the mechanical loading that occurs during the cardiac cycle. Further, we found that increasing the boundary stiffness on a three-dimensional (3D) cell populated collagen gel resulted in increased cellular contractile forces, alpha-SMA expression, and collagen gel (material)stiffness. Finally, VIC morphology is significantly altered in response to stiffness and stretch. On soft 2D substrates, VICs cultured statically exhibit a small rounded morphology, significantly smaller than on stiff substrates. Following equibiaxial cyclic stretch, VICs spread to the extent of cells cultured on stiff substrates, but did not reorient in response to uniaxial stretch to the extent of cells stretched on stiff substrates. These studies provide critical information for characterizing how VICs respond to mechanical stimuli. Characterization of these responses is important for the development of tissue engineered heart valves and contributes to the understanding of the role of mechanical cues on valve pathology and disease onset and progression. While this work is focused on valvular interstitial cells, the culture conditions and methods for applying mechanical stimulation could be applied to numerous other adherent cell types providing information on the response to mechanical stimuli relevant for optimizing cell culture, engineered tissues or fundamental research of disease states."
2
Andersson-Östling, Henrik C. M. "Mechanical Properties of Welds at Creep Activation Temperatures." Doctoral thesis, KTH, Materialvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12077.
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Welds in materials intended for service at temperatures above the creep activation temperature often develop damage before the base metal. The weld is a discontinuity in the material and stresses and strains often accumulate in the weld. Knowledge of the properties of the weld is essential to the safe operation of the component containing the weld. The work in this thesis has been aimed at the study of welds in service at high temperatures: The work is divided into two main chapters. The first chapter deals with welds in stainlesssteels and dissimilar metal welds and includes three papers, and the second chapter dealswith welds in copper intended for nuclear waste disposal, also including three papers. Common to both parts is that the temperature is high enough for most of the damage in the welds to result from creep. In the first part the role of the weld microstructure on the creep crack propagation properties has been studied. Experiments using compact tension specimens have been performed on service exposed, low alloyed heat resistant steels. The results show good correlation with the crack tip parameter, C*, during steady state creep crack growth. The test methodology has also been reviewed and sensitive test parameters have been identified. The results from the creep crack propagation tests on service exposed material has been modeled using uniaxial creep data on both new and ex-service material. The development of the weld microstructure in a dissimilar metal weld between two heat resistant steels has also been investigated. A weld was made between one ferritic and one martensitic steel and the development of the microstructure during welding and post-weldheat treatments has been studied. The results show that the carbon depleted zone that develops near the weld metal in the lower alloyed steel depends on the formation and dissolution of the M23C6-carbide. Variations of the weld parameters and the post-weld heat treatment affect the size and shape of this zone. The process has been successfully modeled by computer simulation. The second part focuses on oxygen free copper intended for nuclear waste disposal containers. The containers are made with an inner core of cast nodular iron and an outer core of copper for corrosion protection. The copper shell has to be welded and two weld methods has been tested, electron beam welding and friction stir welding. Creep specimens taken from both weld types have been tested as have base metal specimens. The technical specifications of the waste canisters demand that the creep ductility of both the copper shell and the welds has to be as high as possible. The creep test results show that base material doped with at least 30 ppm phosphorus has high creep ductility, and friction stir welds made from this material has almost as high creep strength and creep ductility. Copper without phosphorus does not exhibit the same ductility. The creep properties evaluated from testing has been modeled and extrapolated for the intended purposeQC20100719
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Throm, Quinlan Angela M. "Mechanical Activation of Valvular Interstitial Cell Phenotype: A Dissertation." eScholarship@UMMS, 2012. https://escholarship.umassmed.edu/gsbs_diss/640.
Full textAbstract:
During heart valve remodeling, and in many disease states, valvular interstitial cells (VICs) shift to an activated myofibroblast phenotype which is characterized by enhanced synthetic and contractile activity. Pronounced alpha smooth muscle actin (αSMA)-containing stress fibers, the hallmark of activated myofibroblasts, are also observed when VICs are placed under tension due to altered mechanical loading in vivo or during in vitro culture on stiff substrates or under high mechanical loads and in the presence of transforming growth factor-beta1 (TGF-β1). The work presented herein describes three distinct model systems for application of controlled mechanical environment to VICs cultured in vitro. The first system uses polyacrylamide (PA) gels of defined stiffness to evaluate the response of VICs over a large range of stiffness levels and TGF-β1 concentration. The second system controls the boundary stiffness of cell-populated gels using springs of defined stiffness. The third system cyclically stretches soft or stiff two-dimensional (2D) gels while cells are cultured on the gel surface as it is deformed. Through the use of these model systems, we have found that the level of 2D stiffness required to maintain the quiescent VIC phenotype is potentially too low for a material to both act as matrix to support cell growth in the non-activated state and also to withstand the mechanical loading that occurs during the cardiac cycle. Further, we found that increasing the boundary stiffness on a three-dimensional (3D) cell populated collagen gel resulted in increased cellular contractile forces, αSMA expression, and collagen gel (material) stiffness. Finally, VIC morphology is significantly altered in response to stiffness and stretch. On soft 2D substrates, VICs cultured statically exhibit a small rounded morphology, significantly smaller than on stiff substrates. Following equibiaxial cyclic stretch, VICs spread to the extent of cells cultured on stiff substrates, but did not reorient in response to uniaxial stretch to the extent of cells stretched on stiff substrates. These studies provide critical information for characterizing how VICs respond to mechanical stimuli. Characterization of these responses is important for the development of tissue engineered heart valves and contributes to the understanding of the role of mechanical cues on valve pathology and disease onset and progression. While this work is focused on valvular interstitial cells, the culture conditions and methods for applying mechanical stimulation could be applied to numerous other adherent cell types providing information on the response to mechanical stimuli relevant for optimizing cell culture, engineered tissues or fundamental research of disease states.
4
Ni, Xinchen. "Activation of conductive pathways via deformation-induced instabilities." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92170.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014."June 2014." Cataloged from PDF version of thesis.
Includes bibliographical references.
Inspired by the pattern transformation of periodic elastomeric cellular structures, the purpose of this work is to exploit this unique ability to activate conductive via deformation-induced instabilities. Two microstructural features, the contact nub and the conductive pathway, are introduced to make connections within the void and between the voids upon pattern transformation. Finite element-based micromechanical models are employed to investigate the effects of the contact nub geometries, conductive pathway patterns and elastic properties of the coating and substrate materials on the buckling responses of the structure. Finally, a flexible circuit that can be switched on and off by an applied uniaxial load is fabricated based on the finite element analysis and demonstrated the ability to activate conductive pathways in response to an external triggering stimulus.
by Xinchen Ni.
S.M.
5
Depasquale, Roberto. "Mechanical activation of secondary processed orally inhaled active pharmaceutical ingredients." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665449.
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The physicochemical properties and surface chemistry of orally inhaled active pharmaceutical ingredients (API) are critical to the quality attributes of dry powder inhaler (DPI) formulations. The requirement to reduce the particle size distribution of the APIs to a respirable range, largely performed through air-jet micronisation, imparts large amounts of energy to the drug particles, which together with particle fracture and size reduction, it is accompanied by the generation of structural defects and, at the limit, the formation of amorphous regions. This is known as mechanical activation, which may cause instability in the physicochemical properties and interfacial chemistry at the particle surface as it undergoes structural relaxation. During the thermodynamically driven relaxation process, differing drug properties may lead to DPI formulations with unpredictable formulation structure and product functionality. A fundamental understanding of the structural relaxation dynamics is therefore essential in the development and commercialisation of a quality-by-design led inhalation product. This thesis investigated the structural relaxation dynamics of micronised fluticasone propionate (FP), salmeterol xinafoate (SX) and glycopyrrolate bromide (GLY). Physicochemical properties and surface interfacial chemistry, via cohesive-adhesive balance (CAB) measurements, of micronised drug are assessed as a function of environmental stressed laagering over well-defined periods of time and in situ conditioning in hydrofluoroalkane (HFA). The influence of these dynamics upon DPI performance was also examined in both binary (FP, SX, GLY) and tertiary formulations (FP-SX). The results indicated how structural relaxation of hydrophobic and hydrophilic APIs trigger off different stress relaxation pathways with different sensitivities to laagering conditions. These data suggested that the introduction of a post-micronisation conditioning step may expedite structural relaxation of hydrophobic APIs. Whilst the physical properties of hydrophobic APIs are largely unaffected by mechanical activation, surface interfacial chemistry governing inter-particulate forces between API and the lactose carrier is directly affected by environmental conditions of temperature and relative humidity during structural relaxation. The study also showed the potential use of post-micronisation conditioning to tailor the surface chemistry properties of APIs. For hydrophilic APIs, data suggested that post-micronisation conditioning is essential in enabling physical and chemical stability of inhaled formulations. Furthermore, in vitro aerosolisation studies suggested that the aerodynamic particle size distribution and fine particle mass were directly affected by post-micronisation laagering conditions. The importance of generating a well defined, understood and controlled design space throughout product development dictates the need for more robust API processing prior to DPI formulation. This work highlights how a tailored post-micronisation laagering strategy can have a significant effect on physicochemical and interfacial properties as well as product performance of binary and tertiary carrier based DPI formulations.
6
Woolman, Joseph N. "Dense nanometric microalloyed MoSi₂ synthesized through mechanical and field activation /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.
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Li, Jiajie. "Mechanical activation of ultramafic mine waste materials for enhanced mineral carbonation." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61039.
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The potential success of integrating mineral carbonation, as a pathway to CO₂ sequestration, in mining projects, is dependent on the mineralogical composition and characteristics of its waste rock and tailings. Ultramafic rocks have proven the best potential substrate for mineral carbonation and their ability to alter and to convert CO₂ into its carbonate mineral form is dependent on the original mineralogy and particle surface area. CO₂ conversion kinetics is complex and with the application of appropriate comminution technologies, its efficiency can be enhanced. The objective of this research is to evaluate mechanical activation to enhance the carbonation storage capacity of mine waste material. Three approaches were taken in this research. The first approach was to characterize the microstructure of the mechanically-activated mineral olivine, a predominant mineral constituent of ultramafic rocks, using X-ray diffraction patterns and line profile analysis methods with full pattern fitting method. The second approach was to compare the structural and chemical changes of mine waste with pure olivine, both of which were activated by various mechanical forces under both wet or dry conditions and subsequently carbonated in a direct aqueous carbonation process. Regardless of milling conditions, forsterite (Mg₂SiO₄), the olivine mineral variety in the mine waste, was found to be the main mineral being mechanically-activated and carbonated. It was determined that lizardite (Mg₃(Si₂O₅)(OH)₄), a hydrated magnesium silicate also common in ultramafic hosted mineral deposits, acted as catalyzer assisting forsterite reaching high levels of activation. This condition generated a greater CO₂ conversion to carbonate than that of pure olivine with the equal specific milling energy input. The stirred mill proved to be the most efficient form of mechanical activation vis-a-vis the direct aqueous carbonation process, followed by the planetary mill and the vibratory mill. The third approach analyzes the feasibility of mechanical activation in an integrated mineral carbonation process in a nickel mine considering the life cycle of the process. The minimum operating cost for 60% CO₂ sequestration efficiency was 105-107 $/t CO₂ avoided. At this point, the Turnagain project can potentially sequester 238 Mt/y CO₂ using its waste during the 28-year life of mine.Applied Science, Faculty of
Mining Engineering, Keevil Institute of
Graduate
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Colin-York, Huw. "Investigating the active role of mechanical force during T-cell activation." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:0b35bf22-f37f-4286-872d-ea174be82c77.
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The role of mechanical force has gained increasing interest in the field of cell biology owing to the realisation that cells are continually subject to stresses and strains induced by the cellular environment. Cells are known to be able to sense and react to forces imposed on them by their local environment as well as being able to directly impart force during motility, adhesion and cell division. This is also true for cells of the adaptive immune system, specifically during the intimate cell-cell interaction occurring between the T-cell and Antigen Presenting Cell (APC), known as the Immunological Synapse (IS). This highly selective process by which a T cell is able to bind, recognise and react to only foreign antigens has been the focus of intense study due to its crucial importance in the adaptive immune response. The actin cytoskeleton is known to play an essential role in the formation and maintenance of the IS, but questions remain regarding the influence of forces generated by actin during this process. With the aim of measuring mechanical force generated at the IS, we present a novel method combining the super resolution imaging technique, Stimulated Emission Depletion (STED) microscopy and Traction Force Microscopy (TFM). Using the tunable kinetics of the 1G4 Jurkat T-cell system in combination with high spatial and temporal resolution microscopy we demonstrate that actin dynamics at the IS is antigen dependent and show by TFM that force generation occurs on two distinct time scales during activation, mediated by the actin cytoskeleton. Together, the results highlight the intimate links between the dynamics of the actin cytoskeleton, force generation and the antigen response of T cells during activation.
9
Tole, Ilda. "Mechanical activation of clay : a novel route to sustainable cementitious binders." Licentiate thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76362.
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EU Sustainable Development Strategy planned to achieve improvement of life-quality by promoting sustainable production and consumption of raw materials. On November 2018, EU Commission presented a long-term strategy, aiming among others a climate-neutral economy by 2050. Cement production is contributing to 6-10% of the anthropogenic CO2 emissions. Thus, several strategies for total or partial replacement of Portland cement in concrete production have been developed. The use of supplementary cementitious materials (SCM) and alkali-activated materials (AAM) is considered the most efficient countermeasure to diminish CO2 emissions. The broadening of knowledge with particular attention to the sustainable goals is the primary requirement to be fulfilled when novel materials are investigated. This study aims to develop a novel clay-based binder that can be used as a sustainable alternative to produce SCM as well as AAM. Clay is a commonly occurring material, with large deposits worldwide. However, natural clay has a low reactivity and various compositions, depending, e.g. on the weathering conditions. The present research aims exactly at enhancing the reactivity of natural clays occurring in Sweden subjecting them to mechanical activation in a planetary ball mill. Ball milling (BM) is considered a clean technology able to enhance the reactivity of crystalline materials without resorting to high processing temperatures or additional chemicals. BM was able to induce amorphization in clay minerals and to transform the layered platy morphology to spherical shape particles. The efficiency of the process was strictly related to the used process parameters. Higher ball to processed powder (B/P) ratio, longer time of grinding and higher grinding speeds increased the degree of the obtained amorphization. However, an undesired extensive caking and agglomeration occurred in certain setups. The potential of activated clay as a SCM was investigated in specific case studies. The measured compressive strength results showed a direct correlation between the enhanced amorphization degree of the mechanically activated clay and the increased strength values. The pozzolanic activity was induced and enhanced after the mechanical activation of the clay. The reactivity was assessed by the strength activity index (SAI). Furthermore, preliminary tests have shown that the alkali activation of the processed clays produced solidified matrixes with considerable strength.
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Zhu, Ting 1971. "Atomistic characterization of stress-driven configurational instability and its activation mechanisms." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17954.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (p. 145-156).
Cleavage decohesion and shear dislocation nucleation are two basic modes of localized deformation in crystal lattices, which normally result from instability of the atomic configuration driven by mechanical forces. The critical state of instability and its thermal activation mechanisms can be quantitatively determined by analyzing the energetics of the lattice system. In this thesis, the unit processes of configurational instability of crystal lattices under various non-uniform structural and/or chemical environments are characterized by systematically probing the atomistic potential energy landscape of each system using the state of the art configurational space sampling schemes. The problems studied are homogeneous dislocation nucleation in a perfect crystal by nanoindentation, dislocation emission and cleavage decohesion at atomically sharp crack tips, and chemically-enhanced bond breaking in a wet silica nanorod. These processes are studied in a unified manner such that two important types of properties are determined: one is the athermal load at which the instability takes place instantaneously without the aid of thermal fluctuations, and the other is the stress-dependent activation energy used for an estimate of the kinetic rate of transition. Along the way, important aspects concerning the atomistic characterization of configurational instability are revealed. Of particular note is extending the continuum instability criterion to detect atomic defect nucleation. We demonstrate that a local instability criterion can be applied to identify dislocation nucleation in the case of indentation, considering that the relatively small strain gradient beneath the indenter will lead to a mode of long wavelength phonon instability suitable for a study
(cont.) by the local continuum approach. In addition, the chemical effect on stress-driven lattice instability is revealed via the study on reactivity of a silica nanorod with water. We identify distinct competing mechanisms of hydrolysis which are rate-controlling at different load regimes. The ensuing stress-mediated switch of rate-limiting steps of hydrolysis quantitatively demonstrates the impact of finding the detailed molecular mechanisms on a realistic estimate of the activation rate when configurational instability occurs within a chemically reactive environment. Implications regarding the analysis of chemically-assisted brittle fracture are also discussed.
by Ting Zhu.
Ph.D.
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Siddiqui, E. M. "Optimisation of mechanical activation of aluminium for an economical on-demand hydrogen production." Thesis, London South Bank University, 2017. http://researchopen.lsbu.ac.uk/2225/.
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Hydrogen gas, H2 is generated when aluminium metal is reacted with water. Due to the protective oxide layer, the reaction does not take place at ambient conditions. Different activation schemes are possible however most are either expensive or not very practical for H2 generation. This work attempted to address this issue of activation of aluminium particles by means of a reactive ball milling technique. A number of studies based on the activation (preparing it to react with water without the aid of any external heat or catalyst) of aluminium Al, by this method, was reported previously where the energy investment was substantial. This gap in knowledge motivated us to perform milling with a different approach. Milling protocols were identified and devised and presented a milling programme which aided in reducing the energy investment considerably. The motivation behind this work is to use the Al powder prepared by milling in a hydrogen generator connected to fuel cells for in situ generation. Due to the sensitive nature of fuel cell, it was necessary to produce hydrogen gas at a steady rate. It was found that the powder made up of a mixture of metal oxides and salt prepared in-house, provided an excellent base to achieve this. It was also seen that milling of the Al particles to 40 μm proved to perform the best for hydrogen production with yield reaching 85 % in 3 hrs reaction time using only 0.3 g of activated aluminium at ambient conditions. Reaction time can be improved by increasing milling time it would not be economically attractive. After reactive milling and reactions were examined/ inspected using SEM, EDX and XRD techniques for in-depth analysis of Al particle crystalline structure, morphology and size. Milling modifies the surface of the aluminium particles promoting hydrogen gas production. It was also noted that this reaction does not require any heat and that it can generate hydrogen gas at the ambient conditions. It was noticed that when the initial temperature of the solution is increased the reaction rate first improves up to 32 oC than it declines at 45 oC and beyond when larger Al particles are used. This work revealed that reaction requires agitation throughout the process in order to maintain a high yield of hydrogen. While this presented work used deionised water, it should be mentioned that other solvents (aqueous solutions) may be used for hydrogen production as shown in the research. However, the highest amount of yield was produced when deionised water and urea solution was used at 25 oC. “If we had a hydrogen economy worldwide, every nation on earth could create its own energy source to support its economy and the threat of war over diminishing resources would just evaporate” - Dennis Weaver.
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Scheibelein, Christoph [Verfasser]. "Mechanical Activation of Polymer Brushes and the Evolution of Stable Brush Architectures / Christoph Scheibelein." München : Verlag Dr. Hut, 2018. http://d-nb.info/1168535026/34.
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Hockley, James Robert Frederick. "Multiple roles for NaV1.9 in visceral afferent activation by noxious mechanical and inflammatory stimuli." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9105.
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Chronic visceral pain affects millions of individuals worldwide, remains poorly understood, and current therapeutics are constrained by undesirable adverse events. Inflammation and distension of visceral organs are common causes of pain, suggesting drugs targeting these signalling pathways may be efficacious visceral treatments. The voltage-gated sodium channel subtype 1.9 (NaV1.9) has been strongly associated with the development of inflammatory pain by rodent studies and more recently, by the identification of channelopathies in man. The aim of these studies was to investigate the role of NaV1.9 in visceral afferent signalling in the gut. Data from this thesis demonstrates that NaV1.9 is expressed by approximately half of gut-projecting rodent dorsal root ganglia sensory neurons. Consistent with significant expression in visceral afferents, NaV1.9 is required for normal mechanosensation, and for the direct excitation and mechanical hypersensitisation of mouse colonic afferents by inflammatory mediators applied as an inflammatory soup (bradykinin, ATP, histamine, PGE2, and 5HT) or derived from man (as inflammatory bowel disease tissue supernatants). Additionally, the importance of P2Y receptor activation in both rodent and human gut to algogenic purinergic signalling was demonstrated. Collectively, these results demonstrate that NaV1.9, is required for persistence of responses to intense mechanical stimulation, contributes to inflammatory mechanical hypersensitivity, and is essential for activation by noxious inflammatory mediators, including those from diseased human bowel. These findings suggest that NaV1.9 represents a high-value target for development of visceral analgesics.
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Bouchenafa, Othmane. "Mécanosynthèse et matériaux de construction : optimisation et application pour la clinkérisation et la géopolymérisation." Electronic Thesis or Diss., Paris Est, 2019. http://www.theses.fr/2019PESC1003.
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Les matériaux de construction constituent un besoin indispensable pour les êtres humains. Le béton est, après l’eau, le matériau le plus utilisé dans le monde et la production de ciment est en perpétuelle augmentation du fait de l’accroissement de la population mondiale. En 2010 la production annuelle de ciment a atteint les 3,3 milliards de tonnes. Une progression de +6,9% a été constatée en 2015 pour une production qui a atteint 4,6 milliards de tonnes.Des études menées sur l’impact environnemental du procédé de fabrication du clinker ont révélé que pour une production d’une tonne de clinker, une quantité de l’ordre de 0,7 à 0,8 tonne de CO2 est rejetée dans l’atmosphère, soit une émission annuelle de 2,8 milliards de tonnes de CO2. Ces rejets de gaz à effet de serre sont responsables de 5% des émissions mondiales. Afin de réduire cet impact, des solutions ont déjà été proposées telles que l’utilisation de combustibles alternatifs pour la fabrication du clinker, la substitution partielle du ciment par des coproduits industriels ou le captage et stockage du carbone.Cette thèse s’inscrit dans une volonté de réduire l’impact carbone dans la fabrication des matériaux de construction et cela par l’introduction du procédé de mécanosynthèse dans le processus de production du clinker et du ciment ainsi que des géopolymères.Le travail de thèse a été divisé en 3 grandes parties :La première concerne l’optimisation du procédé de mécanosynthèse par l’ajout d’agents de contrôle (process control agents) « PCA ». L’utilisation de ces agents pour le broyage de cendres volantes et de laitiers de hauts fourneaux a permis de réduire la durée du broyage à 15 minutes, alors que sans PCA un broyage de 1h est nécessaire, voire 3h pour un broyage optimal. Les pâtes cimentaires pour lesquelles nous avons substitué jusqu’à 50% de clinker par des coproduits industriels activés par mécanosynthèse avec des PCA (nous avons utilisé de l’alcool et l’eau) ont montré des performances mécaniques supérieures à celles préparées avec 100% de ciment Portland.Les pâtes cimentaires préparées avec une substitution de 50% de laitier broyé 15 min + 4% d’alcool ont montré une amélioration des performances mécaniques (compression) de + 10%, + 15% et + 40% par rapport à une pâte de ciment référence respectivement pour 7, 28 et 90 jours.La deuxième partie vise à proposer un procédé de clinkérisation par mécanosynthèse indirecte. Dans cette partie nous avons utilisé dans un premier temps du calcaire et de l’argile (produits classiques pour la fabrication du clinker) pour la production d’un clinker équivalent. Pour atteindre notre objectif nous avons utilisé la mécanosynthèse indirecte qui consiste à coupler une activation mécanique de courte durée et un traitement thermique ne dépassant pas les 900°C. Cette technique nous a permis de produire les composés indispensables au clinker, l’alite C3S (Ca3SiO5), la belite β-C2S (Ca2SiO4) et les aluminates C3A.La dernière partie avait pour but d’utiliser le procédé de mécanosynthèse directe pour la production d’une poudre géopolymère prête à l’emploi seulement par addition d’eau. Ce procédé consiste à mélanger des aluminosilicates tels que des laitiers, des cendres volantes ou du métakaolin avec des activateurs chimiques par broyage pour l’obtention d’un produit géopolymère final.Des formulations de pâtes géopolymères ont été faites et des résultats encourageants en terme de résistance à la compression ont été obtenusConstruction materials are an essential need for humans. After Water, concrete is the most widely used material in the world and cement production is constantly increasing due to the increase in the world population. In 2010, the annual cement production reached 3.3 billion tonnes. An increase of +6.9% was recorded in 2015 for a production that reached 4.6 billion tonnesStudies conducted on the environmental impact of the clinker manufacturing process have revealed that for a production of one tonne of clinker, a quantity of 0.7 to 0.8 tonnes of CO2 is released into the atmosphere or an annual emission of 2.8 billion tonnes of CO2. These greenhouse gas emissions are responsible for 5% of global emissions. In order to reduce this impact, solutions already proposed such as the use of alternative fuels for clinker manufacture, the partial substitution of cement by industrial co-products or carbon capture and storage.This thesis is part of a desire to reduce the carbon impact in the manufacture of construction materials by introducing the mechanosynthesis process into the production process of clinker and cement as well as geopolymers.The thesis work has been divided into 3 main parts:The first part concerns the mechanosynthesis process optimization by adding process control agents (PCAs). The use of these agents for the grinding of fly ash and blast furnace slag has reduced the milling time to 15 minutes, whereas without PCA, 1 hour milling time is required, or even 3 hours for optimal milling. Cement pastes which we have substituted up to 50% clinker with industrial co-products activated by mechanosynthesis with PCAs (we have used alcohol and water) have shown higher mechanical performance than those prepared with 100% Portland cement.Cement pastes prepared with a substitution of 50% milled slag 15 min + 4% alcohol has shown an improvement in mechanical performance (compression) of + 10%, + 15% and + 40% compared to a reference cement paste for 7, 28 and 90 days respectively.The second part aims to propose a clinkerization process by indirect mechanosynthesis. We have used limestone and clay (traditional products for clinker manufacturing) to produce an equivalent clinker. To achieve our objective, we have used indirect mechanosynthesis, which consists of coupling a mechanical activation with short milling time and a heat treatment not exceeding 900°C. This technique has allowed us to produce the essential compounds of clinker, C3S alite (Ca3SiO5), β-C2S belite (Ca2SiO4) and C3A aluminates.The last part is focused on the direct mechanosynthesis process used for the production of a ready-to-use geopolymer powder only by adding water. This process consists of mixing aluminosilicates such as slag, fly ash or metakaolin with chemical activators by grinding to obtain a final geopolymer product.Geopolymer paste formulations have been made and encouraging results in terms of compressive strength have been obtained
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Riosbaas, Miranda Tiffany. "Phase Change Activation and Characterization of Spray-Deposited Poly(vinylidene) Fluoride Piezoelectric Thin Films." Thesis, University of California, Davis, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1585118.
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Structural safety and integrity continues to be an issue of utmost concern in our world today. Existing infrastructures in civil, commercial, and military applications are beginning to see issues associated with age and environmental conditions. In addition, new materials are being put to service that are not yet fully characterized and understood when it comes to long term behavior. In order to assess the structural health of both old and new materials, it is necessary to implement a technique for monitoring wear and tear. Current methods that are being used today typically depend on visual inspection techniques or handheld instruments. These methods are not always ideal for large structures as they become very tedious leading to a substantial amount of both time and money spent. More recently, composite materials have been introduced into applications that can benefit from high strength-to-weight ratio materials. However, the use of more complex materials (such as composites) leads to a high demand of structural health monitoring techniques, since the damage is often internal and not visible to the naked eye. The work performed in this thesis examines the methods that can be used for phase change activation and characterization of sprayable poly(vinylidene) fluoride (PVDF) thin films in order to exploit their piezoelectric characteristics for sensing applications. PVDF is widely accepted to exist in four phases: alpha, beta, gamma, and delta. Alpha phase PVDF is produced directly from the melt and exhibits no piezoelectric properties. The activation or transition from α phase to some combination of beta and/or gamma phase PVDF leads to a polarizable piezoelectric thin film to be used in sensing applications. The work herein presents the methods used to activate phase change in PVDF, such as mechanical stretching, annealing, and chemical composition, to be able to implement PVDF as an impact detection sensor. The results and analysis provided in this thesis will present the possibilities of spray-deposited PVDF thin films in both small-scale and large-scale sensing applications that can be applied to both simple and complex geometries.
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Seaton, Robert L. "The influence of temperature and composition on the activation energy for creep in binary aluminum lithium alloys." Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA242299.
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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990.Thesis Advisor(s): McNelley, Terry R. ; Kalu, Peter N. "December 1990." Description based on title screen as viewed on April 2, 2010. DTIC Identifier(s): Aluminum alloys, lithium, creep, binary alloys, strength weight ratio, stress tests, stress strain relations, microstructure, aerospace craft, isothermal tests, theses. Author(s) subject terms: Temperature, composition, activation energy, creep binary aluminum lithium alloys. Includes bibliographical references (p. 89-90). Also available in print.
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Pourghahramani, Parviz. "Mechanical activation of hematite using different grinding methods with special focus on structural changes and reactivity /." Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1544/2007/08/.
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Заулічний, Я. В., О. І. Дудка, Ю. В. Яворський, and М. О. Коломійчук. "Зміна морфології сумішей SiO2/ γ - Fe2O3 внаслідок механоактивації." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47773.
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Механоактивація (від англ. mechanical activation) – активування зв’язків між поверхневими атомами частинок твердих речовин механічною обробкою. Розмелювання в вібраційному млині призводить до накопичення структурних дефектів, фазовим перетворенням і навіть аморфізації кристалів, що впливає на хімічну активність суміші. В результаті високих локальних тисків в деякій області нанокомпозиту утворюється напруження з подальшою релаксацією.
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Pourghahramani, Parviz. "Effects of grinding variables on structural changes and energy conversion during mechanical activation using line profile analysis (LPA) /." Luleå : Luleå tekniska universitet/Chemical Engineering and Geosciences/Mineral Processing, 2006. http://epubl.ltu.se/1402-1757/2006/19/index.html.
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Fagiani, Ramona. "Tribological activation of tactile receptors by vibrations induced at the finger contact surface." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00715822.
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This thesis deals with the tribological and dynamic aspects of tactile perception given by the scanning of the finger on a surface. The attention is focused on a direct analysis of the vibration spectrum characteristics, induced by the surface features that is a relatively new research field. In fact, it is accepted that vibrations activate the tactile afferents and their essential role for the perception of fine textures (duplex theory of tactile texture perception) but it is still unknown the link with the surface texture characteristics and the features of the induced vibration spectra. The work is aimed to contribute to a better understanding of the mechanisms of the tactile sense, that is basilar for manifold different applications: textile quality quantification, ergonomics of everyday objects (which largely affects their commercial competitiveness), identification of surface imperfections, the design of tactile communication devices, the development of artificial tactile sensors for intelligent prostheses or robotic assistants, the development of human-machine interfaces for interaction with virtual realities or teleoperation systems, such as for telediagnosis or microsurgery, reproducing real perception (virtual reality), increasing the human perception (augmented reality), development of tests for evaluation of tactile sensitivity during diagnosis or monitoring process in rehabilitation. The study of a finger that moves on a surface involves different difficulties that are related to the material characteristics and to the measurements themselves. For these reasons, a new experimental set-up, named TriboTouch, has been developed to reproduce the finger/surface scanning phenomena under real values of the contact feature (scanning velocity and amplitude, surface roughness, etc..), avoiding undesired vibrations. The test bench has been designed to guarantee the measurements reproducibility and to perform measurements without introducing external noise. The set-up permits to carry out both measurements of the global dynamics and local ones (at the contact zone) employing a silicone fake finger. In the presented analysis, the behavior of the right hand index finger scanning on the surface sample with periodical and isotropic roughness and on textiles has been investigated for different scanning speed, highlighting the role of fingerprints A simple numerical model have been developed for reproducing the behavior of the induced vibrations when sliding two periodical surfaces and the numerical results have been compared with the experimental ones. The presented work has shown the possibility to obtain objective indexes for the tactile perception characterization, by means of the friction induced vibration spectrum analysis, in agreement with the neurophysiological studies present in literature.
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Mollica, Molly Y. "DNA Origami Breadboard: A Platform for Cell Activation and Cell Membrane Functionalization." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461163132.
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Rocha, Claudio Jose da. "Mecanismos de ativação mecânica de misturas de Níobio e Alumínio para a síntese por reação do NbAl3." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-11102011-142444/.
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Neste trabalho, a moagem com alta energia foi utilizada para a ativação mecânica de misturas de pós de alumínio e nióbio, na proporção de 75% atômico de alumínio, para a síntese por reação de combustão do NbAl3. O objetivo foi investigar os mecanismos de ativação atuantes e a eventual preponderância de um deles. A moagem foi realizada tanto nos pós de alumínio e de nióbio separadamente (pré-ativação), como nas misturas. O processo de síntese por reação foi realizado no modo combustão simultânea, em pastilhas compactadas a partir de misturas com e sem ativação mecânica. O comportamento térmico das pastilhas foi registrado durante todo o ciclo térmico de aquecimento e, as principais características térmicas da reação de combustão, foram determinadas. O parâmetro de rede, o tamanho de cristalito e a microdeformação elástica do alumínio e do nióbio foram determinados por difratometria de raios X, mediante análise pelo método de Rietveld. A microscopia eletrônica de varredura foi utilizada para caracterização microestrutural dos pós moídos e da pastilha reagida. Constatou-se que o mecanismo preponderante de ativação mecânica é o aumento da área de interface, que ocorre durante a formação de agregados de partículas de alumínio e nióbio. A eficiência na formação de interfaces diminuiu com a utilização de nióbio pré-ativado (encruado) e com o aumento da quantidade de ácido esteárico (utilizado como agente controlador de processo durante a moagem). O efeito principal da ativação mecânica na síntese por reação de combustão foi a redução da temperatura de ignição com o aumento do tempo de moagem. A alta densidade de defeitos cristalinos, gerada durante a pré-ativação dos pós de alumínio e nióbio e na ativação mecânica das misturas, não produziu efeitos mensuráveis sobre o comportamento térmico das pastilhas.In this work, mechanical activation of mixtures of niobium and aluminum powders (75 at.% of Al) was carried out by high energy ball milling, in order to produce NbAl3 by combustion synthesis. The purpose was to investigate activation mechanisms present and the eventual preponderancy of one of them. Beside mixtures, aluminum and niobium powders were separately activated by milling (pre-activation). Reaction synthesis, by simultaneous combustion mode, was conducted on compacted pellets made of activated and non-activated powder mixtures. The thermal behavior of the compacted pellets upon heating was recorded and main thermal characteristics of the combustion reaction were evaluated. Lattice parameter, crystallite size and microstrain for niobium and aluminum were measured by X-ray diffraction analysis, using the Rietveld method. Scanning electron microscopy was used for microstructural characterization of milled powders and reacted pellets. The growth of interface area in the aggregates of aluminum and niobium, formed during milling, was shown to be the main activation mechanism. Both pre-activated niobium and increased quantities of stearic acid (milling process control agent) hinder the interface formation. The main effect of mechanical activation in the reaction synthesis was to reduce the ignition temperature with the increase of the milling time. High density of crystal defects attained during milling (pre-activation of single powders or activation of the mixtures) produced no measurable effects to the thermal behavior of pellets.
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Fallon, Anna Marie. "The Development of a Novel in vitro Flow System to Evaluate Platelet Activation and Procoagulant Potential Induced by Bileaflet Mechanical Heart Valve Leakage Jets." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/10451.
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Bileaflet mechanical heart valves (BMHVs) are prone to thrombus formation in the hinge region due to high shear stress combined with stagnation regions. This thesis research addresses the hypothesis that models that isolate and mimic BMHV hinge geometries can be used to quantitatively characterize procoagulant potential using a novel in vitro blood flow system. Furthermore, these results can be correlated with digital particle image velocimetry (DPIV) measurements detailing flow fields for the same models.
The significant findings were that: 1) recalcification of recirculating citrated blood markedly increases the magnitude of thrombus forming reactions and the sensitivity for their detection; 2) platelet activation, and the presence of adequate platelet numbers are essential for the activation of coagulation under conditions of high shear; and 3) thrombin formation can be inhibited by blocking the platelet receptors that facilitate platelet aggregation.
The DPIV studies give some insight into why different channel geometries resulted in varying propensities for coagulation. The channel geometries with abrupt changes in diameter induced significantly higher levels of TAT and also formed jets that were subject to increased entrainment of the stagnant fluid in the chamber. This entrainment enables more mixing of the shear-activated platelets with the surrounding flow, which can propagate the coagulation cascade, thus increasing the chance for thrombus formation.
The influence of abrupt changes in diameter was also evident in the BMHV human blood studies. The MP valve, which has a tortuous hinge pathway, induced significantly more TAT formation than the SJM Standard valve with a smoother hinge channel. Thus, BMHV hinge geometry should be as smooth and free of diameter changes as possible to eliminate stagnation regions that enable activated platelets to congregate and propagate the coagulation cascade.
Leakage gap width also had a significant effect not only on procoagulant potential but also on platelet activation. Both the low and high leaker prototype valves had significantly higher levels of platelet activation compared to the SJM Standard valve, but only the low leaker valve demonstrated a higher propensity for coagulation. Thus, to minimize both platelet activation and thromboemboli formation, an optimal gap width should be maintained for BMHVs.
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Sohn, Mark Hongchul. "Assessing functional stability of predicted muscle activation patterns for postural control using a neuromechanical model of the cat hindlimb." Thesis, Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42869.
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The underlying principles of how the nervous system selects specific muscle activation pattern, among many that produce the same movement, remain unknown. Experimental studies suggest that the nervous system may use fixed groups of muscles, referred to as muscle synergies, to produce functional motor outputs relevant to the task. In contrast, predictions from biomechanical models suggest that minimizing muscular effort may be the criteria how a muscle coordination pattern is organized for muscle synergies. However, both experimental and modeling evidence shows that stability, as well as energetic efficiency, also needs to be considered.
Based on the hypothesis that the nervous system uses functionally stable muscle activation pattern for a muscle synergy, we investigated the stability of muscle patterns using a neuromechanical model of the cat hindlimb. Five unique muscle patterns that generate each of the five experimentally-identified muscle synergy force vectors at the endpoint were found using a minimum-effort criterion. We subjected the model to various perturbed conditions and evaluated functional stability of each of the five minimum-effort muscle synergies using a set of empirical criteria derived from experimental observations.
Results show that minimum-effort muscle synergies can be functionally stable or unstable, suggesting that minimum-effort criterion is not always sufficient to predict physiologically relevant postural muscle synergies. Also, linearized system characteristics can robustly predict the behavior exhibited by fully dynamic and nonlinear biomechanical simulations. We conclude that functional stability, which assesses stability of a biomechanical system in a physiological context, must be considered when choosing a muscle activation pattern for a given motor task.
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Вишегородцева, М. Є., Христина Володимирівна Берладір, Кристина Владимировна Берладир, Khrystyna Volodymyrivna Berladir, Тетяна Павлівна Говорун, Татьяна Павловна Говорун, and Tetiana Pavlivna Hovorun. "Дослідження впливу механічної активації на структуру та властивості композитів на онові політетрафторетилену." Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/46999.
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Tillin, Neale A. "The influence of training and athletic performance on the neural and mechanical determinants of muscular rate of force development." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/8524.
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Neuromuscular explosive strength (defined as rate of force development; RFD) is considered important during explosive functional human movements; however this association has been poorly documented. It is also unclear how different variants of strength training may influence RFD and its neuromuscular determinants. Furthermore, RFD has typically been measured in isometric situations, but how it is influenced by the types of contraction (isometric, concentric, eccentric) is unknown. This thesis compared neuromuscular function in explosive power athletes (athletes) and untrained controls, and assessed the relationship between RFD in isometric squats with sprint and jump performance. The athletes achieved a greater RFD normalised to maximum strength (+74%) during the initial phase of explosive contractions, due to greater agonist activation (+71%) in this time. Furthermore, there were strong correlations (r2 = 0.39) between normalised RFD in the initial phase of explosive squats and sprint performance, and between later phase absolute explosive force and jump height (r2 = 0.37), confirming an association between explosive athletic performance and RFD. This thesis also assessed the differential effects of short-term (4 weeks) training for maximum vs. explosive strength, and whilst the former increased maximum strength (+20%) it had no effect on RFD. In contrast explosive strength training improved explosive force production over short (first 50 ms; +70%) and long (>50 ms; +15%) time periods, due to improved agonist activation (+65%) and maximum strength (+11%), respectively. Explosive strength training therefore appears to have greater functional benefits than maximum strength training. Finally, the influence of contraction type on RFD was assessed, and the results provided unique evidence that explosive concentric contractions are 60% more effective at utilising the available force capacity of the muscle, that was explained by superior agonist activation. This work provides a comprehensive analysis of the association between athletic performance and RFD, the differential effects of maximum vs. explosive strength training, and the influence of contraction type on the capacity for RFD.
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Marashdeh, Wajeeh. "Relaxation Behavior and Electrical Properties of Polyimide/Graphene Nanocomposite." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1595850361812632.
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Rolseth, Anton, and Anton Gustafsson. "Implementation of thermomechanical laser welding simulation : Predicting displacements of fusing A AISI304 T-JOINT." Thesis, Högskolan i Skövde, Institutionen för ingenjörsvetenskap, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-19946.
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Laser welding is an advanced joining technique with the capability to form deep, narrow, and precise welds. Numerical models are used to simulate the process in attempts of predicting distortions and stresses in the material. This is done to reduce physical testing, optimize processes and enable integrated product- and process development. The Virtual Manufacturing Process research group at University of Skövde wishes to increase their knowledge on modeling options of thermomechanical simulations to grant local industries these benefits. A numerical model for the laser welding process was developed in ABAQUS. This was done by examining the macrograph structure of a simple weld and applied to a stainless-steel T-joint welding application. The macrograph data was used to calibrate a mathematical heat source model. User subroutine DFLUX was used to enable movement of the heat source and element activation was used to simulate the fusion of the two parts. A T-joint welding experiment was carried out to measure deflection and the result was compared to numerical simulations. Different combinations of heat source models, coupling type and element activation was compared in relation to predicting the deflection. Computational time and modeling complexity for the techniques was also considered.The results showed that a 3D Gaussian heat source model will imitate the keyhole weld achieved superior to the compared 2D model. The 3D model provides greater flexibility since it enables combinations of any geometrical bodies. It was shown that element activation has a significant contribution on part stiffness and thus resulting distortions. To implement element activation a fully coupled analysis is required. The deflection of the fully coupled 3D simulation with element activation showed a 9% deviance in deflection compared with experiments.
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Hüller, Florian [Verfasser], Friedlinde [Akademischer Betreuer] Götz-Neunhoeffer, and Friedlinde [Gutachter] Götz-Neunhoeffer. "Hydration mechanisms of CA2 and alumina-rich calcium aluminate cements: Effects of mechanical activation, critical CA contents and crystallinity of AH3 / Florian Hüller ; Gutachter: Friedlinde Götz-Neunhoeffer ; Betreuer: Friedlinde Götz-Neunhoeffer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1187523283/34.
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Prince, Agbodjan William. "Etude de la reactivite de materiaux naturels actives par voie thermique ou mecanique en vue de leur utilisation comme liant." Toulouse 3, 1987. http://www.theses.fr/1987TOU30077.
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Etude de la reactivite des silicoaluminates avec la chaux en presence de sulfates et de chlorures en vue de leur utilisation comme liant. On synthetise preferentiellement la gehlinite hydratee malgre la presence de portlandite, ce qui accroit la resistance et la stabilite des liants. Deux liants ternaires, a base d'argile activee et de chaux ont pu etre obtenus
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Bergold, Sebastian Tobias [Verfasser], and Jürgen [Gutachter] Neubauer. "The process of alite hydration: Implications from quantitative phase analysis of Calcium-Silicate-Hydrate during hydration and from acceleration of the hydration reaction by mechanical activation / Sebastian Tobias Bergold ; Gutachter: Jürgen Neubauer." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1124233946/34.
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Mizerová, Cecílie. "Binární alkalicky aktivované kompozitní materiály s cihelným prachem." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372259.
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The thesis is focused on the application of brick powder in production of binary alkali-activated binders with metakaolin, slag and fly ash. The theoretical part summarizes recent fields of use of the ceramic waste in construction and binder industry and prerequisite properties of the brick powder for alkaline activation. Brick powder based geopolymers made in the experimental work were tested for their mechanical properties, porosity and microstructure, flow properties of the fresh geopolymers were evaluated by rheometric measurements. In accordance with the results it can be concluded that brick powder could be a suitable precursor for blended binders with metakaolin and slag, these samples exhibited good mechanical properties and microstructure characteristics. The combination with fly ash was less applicable due to a rapid setting, hardening retarder used in these binders caused significant deterioration of the mechanical properties of the material.
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Novák, Václav. "Vliv velikosti částic odpadního skla na vlastnosti alkalicky aktivovaných aluminosilikátových kompozitů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392355.
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The diploma thesis is focused on the use of the waste glass with different fineness on alkali - activated composites, mainly based on slag and fly ash. The theoretical part is focused on materials that are most used for alkaline activation - slag, fly ash and their composites with waste glass. The theoretical part also deals with the alkaline activation of composites from these materials and the factors that influences the microstructure and properties of these composites. In the experimental part were prepared composites from slag and fly ash with a waste glass as substitute. These composites then have been examined on mechanical properties and microstructure, also how different fineness of glass influences these properties. Then it will be decided whether it is economically advantageous grinding waste glass to finer fractions
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Білоус, Олена Анатоліївна, Елена Анатольевна Белоус, Olena Anatoliivna Bilous, Христина Володимирівна Берладір, Кристина Владимировна Берладир, Khrystyna Volodymyrivna Berladir, and Д. С. Лаврик. "Моделювання деформаційної характеристики політетрафторетиленової матриці." Thesis, Сумський державний університет, 2017. http://essuir.sumdu.edu.ua/handle/123456789/66529.
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Метою роботи є вивчення результатів процесу механічної активації
політетрафторетилену (ПТФЕ) методами математичного моделювання та
оптимізації [1]. Так дослідження залежності деформаційної характеристики
матриці від параметрів процесу активації виконували методом
ортогонального планування експерименту. За допомогою двохфакторного
регресійного аналізу були визначені оптимальні рівні основних факторів і їх
взаємодії. Функцією відгуку (параметра оптимізації) була деформаційна
характеристика – відносне подовження (δ).
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Hladík, Václav. "Vliv různé technologie mletí a mechanické aktivace na vlastnosti hydraulických pojiv." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371917.
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This diploma thesis mainly tracks the effect of grinding technology on the final properties of portland cement and selected pozzolanic materials. For grinding of portland cement, was also observed the effect of storage time on the final mechanical properties and hydratation process. Pozzolan activity of selected materials was monitored by evaluation of the reaction with CaO by differential thermal analysis.
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Ledo, Mário Tiago Igreja Ferreira. "Avaliação do potencial de incorporação de resíduos mineiros em geopolímeros." Master's thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17131.
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Mestrado em Engenharia GeológicaAo longo das últimas décadas a emissão de gases com efeito de estufa e a produção de resíduos tem sido crescente, sendo a indústria extrativa responsável por uma quota-parte. Deste modo, surge cada vez mais a necessidade de encontrar alternativas credíveis para substituir materiais responsáveis por elevadas emissões poluentes assim como reutilizar materiais que são categorizados como resíduos. O presente trabalho visa avaliar o potencial de incorporar resíduos mineiros em misturas geopoliméricas. Assim para responder a esse problema, num primeiro momento, a parte experimental incidiu na avaliação das características físicas, químicas e térmicas de lamas residuais provenientes de uma exploração mineira de sulfuretos polimetálicos do sul de Portugal. Seguindo-se uma fase de desenvolvimento de misturas geopoliméricas utilizando esses mesmos resíduos mineiros conjuntamente com metacaulino ou escória, tendo-se avaliado a resistência mecânica dessas misturas por intermédio dos ensaios de resistência à flexão e compressão 28 e 60 dias após o fabrico dos corpos de prova. Sobre os dados recolhidos anteriormente, foram reajustadas composições, produzidos novos corpos de prova e realizados ensaios de resistência à flexão e compressão assim como o ensaio de absorção de água por capilaridade. Como resultado da campanha experimental, verificou-se que a incorporação de resíduos mineiros nas composições com metacaulino não apresentam problemas no que à resistência mecânica e durabilidade diz respeito, no entanto ocorre uma maior retração nestas quando comparadas com as composições com escória. Tendo-se também verificado que a durabilidade das composições com escória é bastante limitada quando se encontram sob a influência de água.
Over the last decades emission of greenhouse gases and production of residues as been growing, being the extractive industry responsible for a share. As so, raises more and more the need to find credible alternatives to replace the materials responsible for the high emissions and how to reuse the materials categorized as residues. The present work aims to evaluate the potential incorporation of mining waste materials in geopolymers mixtures. Thereby to answer the issue, in a first moment, the experimental part focus on evaluation of the physical, chemical and thermal characteristics of waste mining mud’s coming from polymetalic sulphides mining exploration in the south of Portugal. Followed by a development phase of geopolymers mixtures using the same mineral residues together with metakaolin or slag, having assessed the mechanical resistance of these mixtures via flexural strength and compression essays 28 and 60 days after the manufacture of the test specimens. Over the data previously collected, composition rearrangements were performed, new test specimens were produced and flexural strength and compression essays were conducted as well a test of water absorption by capillarity. As result of the experimental campaign, was verified the incorporation of mineral residues on metakaolin compositions didn´t reveal any issues concerning is mechanical composition and durability, however it occurs a bigger retraction on this compositions comparing to the ones composed with slag. As been also established the durability of slag compositions is significant limited when they find under water influence.
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PINEDO, CARLOS E. "Estudo morfologico e cinetico da nitretacao por plasma pulsado do aco inoxidavel martensitico AISI 420." reponame:Repositório Institucional do IPEN, 2000. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10826.
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Made available in DSpace on 2014-10-09T12:44:26Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T13:56:39Z (GMT). No. of bitstreams: 1 06912.pdf: 10380955 bytes, checksum: 3e22ae9dda613db66c72f121ed37b278 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Skoss, Ann Rachel Locke. "Stabilisation of the human ankle joint in varying degrees of freedom : investigation of neuromuscular mechanisms." University of Western Australia. School of Human Movement and Exercise Science, 2002. http://theses.library.uwa.edu.au/adt-WU2003.0021.
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Previous research investigating the stability of the ankle joint complex may be categorised into two methodological groups, employing either an actuator to perturb the limb, or a form of standing balance disturbance such as a tilting platform, both of which test the joint in single degree of freedom (DOF). The aim of this thesis was to investigate how we control foot position and stabilise the joint when there is potential for movement in three DOF. A secondary aim of the thesis was to model the intrinsic mechanical properties of the ankle joint complex in three dimensions when coupled movement of the tibio-talar and talo-calcaneal joints are possible. This thesis details (i) the development of a perturbation rig that allows foot movement in single- or three-DOF with associated real-time visual target-matching software, and (ii) the use of the rig to investigate the stabilisation of the ankle joint complex in single- and three-DOF. The experimental procedure used a common task performed in three experimental conditions. Subjects were required to maintain a neutral foot position while developing varying levels of plantar-flexion torque. A perturbation was applied to the foot if subjects were within specified tolerance for both foot position and torque, represented by the visual display. Performance of the task in the first condition required the subject to only match torque as the foot position was fixed, with the perturbation being applied in dorsi-flexion (ie, single-DOF). The second experimental condition allowed the foot to move in the sagittal plane, hence subjects were required to control both torque and foot position in single-DOF, with perturbation applied in dorsi-flexion. The third condition enabled movement in dorsi/plantar-flexion, inversion/eversion and adduction/abduction (three-DOF) in both task and perturbation. Subjects were required to maintain the neutral foot position and the necessary torque level. There were three areas of interest common to each experimental protocol. The muscle strategy used to complete the task was investigated using a combination of surface and fine-wire electromyography on lower leg and thigh muscles. The 500ms period prior to perturbation was investigated to determine if synergies were evident between muscles such as medial and lateral gastrocnemius, soleus and peroneus longus. Two classes of activation strategies for the three-DOF condition emerged from the subject population: differential activation of the triceps surae group, and co-contraction. The former strategy may take advantage of the distinct morphology of the lateral gastrocnemius and peroneus longus muscles to best perform the position-matching component of the 3D task. The results suggest that the ankle joint is mostly stabilised in 3D by the intrinsic mechanical actions of the muscles producing plantar flexion moments. The muscles stabilised the foot in inversion, but not in eversion where there was very little motion. However, the different activation strategies employed may have varied efficacy in contributing to joint stability. This form of active stabilisation means that the previous literature focus on reflexes to stabilise the joint may need to be reassessed. Likewise, it may be appropriate to use the perturbation rig to quantify active ankle joint stability in order to assess the probability of ankle injury, rather than the current clinical measures employed. The reflexive response due to the perturbation was examined in the 200ms following perturbation. Variation in the modulation of monosynaptic reflexes was observed between subjects in various muscles in the higher DOF tasks. This is likely due to the differing activation strategies used to perform the task, and the variability in the kinematic response to perturbation. An attempt was made to calculate the intrinsic mechanical properties of the joint in 3-D using the kinematic and kinetic data during the first 15 ms period of perturbation. The system was modelled as a spring-damper using a constrained non-linear least squares, with stiffness and viscous terms for each axis, and inertial tensor elements as variables in the routine. The effect of increased muscle activation on the displacement of the foot about each of the anatomical axes was to significantly lower the movement of the sub-talar joint.
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Oliveira, Maria Angela Loyola de. "Émission et développement de dislocations en tête de fissure dans le silicium : analyse tridimensionnelle de l'interaction dislocation/fissure." Vandoeuvre-les-Nancy, INPL, 1994. http://www.theses.fr/1994INPL067N.
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Des éprouvettes monocristallines, sans dislocations, fissurées a 20c par clivage limite, sont chargées progressivement a une température suffisante (700c environ) pour que le silicium devienne ductile du fait de l'activation thermique du glissement des dislocations. Les concentrations de contraintes existant en pointe de fissure provoquent la nucléation et le développement de boucles de dislocations qui exercent en retour sur la fissure des contraintes s'opposant en moyenne a sa propagation: cet effet est appelé écrantage. La partie expérimentale de cette étude est consacrée à la localisation des sources de dislocations, à la caractérisation des systèmes de glissement actives et à l'influence du chargement sur la ténacité du matériau. Le chargement en deux étapes qui a été développe permet d'activer un nombre limite de sources, puis de suffisamment étaler les configurations de dislocations pour qu'elles puissent être caractérisées par topographie aux rayons X, tout en évitant l'émission de nouvelles dislocations. L'objectif de la partie théorique de cette étude est de poser les concepts fondamentaux de l'interaction dislocation-fissure puis de l'évaluer quantitativement. Le calcul de l'écrantage et de l'ouverture de la fissure a pu être effectué analytiquement, grâce à la simplicité du formalisme lié aux états plans. Dans le cas réel, tridimensionnel, le calcul de l'écrantage a été réalisé par intégration numérique du champ de contrainte d'une boucle circulaire pondère par une fonction de poids, en utilisant le théorème de superposition
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Pernička, Jan. "Studie variant čištění specifických odpadních vod." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226164.
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This diploma thesis explores treatment options of wastewater with a low presence of organic pollution produced by minor pollution sources. The research part describes objects with a low presence of organic pollution in wastewater and possible treatment methods in dependence of pollution source's size. The practical part contains the design of technological options of treatment of wastewater with a low presence of organic pollution for a specific object.
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Castro, Mauricio de. "ESTUDO COMPARATIVO DA ATIVAÇÃO MECÂNICA POR MOINHOS DE ALTA ENERGIA E CARACTERIZAÇÃO DOS PRODUTOS OBTIDOS DURANTE REAÇÃO DE REDUÇÃO DO ÓXIDO DE CROMO POR ALUMÍNIO." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2015. http://tede2.uepg.br/jspui/handle/prefix/1470.
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This study aims to compare the supply capacity of power each of the three main types of high-energy mills: The "SPEX", Planetary and "Attritor" mills. The system used was chromium oxide with metallic aluminum, both are powders. The reduction reaction of chromium oxide with aluminum in the milling does not occur instantaneously, but is stimulated with mechanical activation of the reagents. The mechanical activation in milling, together with the subsequent heat treatment is that makes a reaction. The energy comparison was made between the mill in two steps: In the first step the milling power was varied for the three mills to be able to identify the milling resulted in the highest exotermic energy peak in the reaction, whereas in the second stage ranged -if the time for milling time find themselves exhibited higher energy released in the reaction. This comparison between the reaction energy peaks confirmed the SPEX as the mill with greater power supply capacity, ie: The mill with the largest peak energy released, followed by the Planetary mill and finally by Attritor mill. In the energy comparison, we studied the influence of the presence of a process control agent in the reaction energy peaks at different milling powers. The milled samples had their power surges reaction determined by thermal analysis of the post. This energy released in the process varied, tending to exhibit a higher peak energy for each of the evaluated parameters (milling power and milling time). There was the use of x-ray diffraction to show the reduction of ground and treated material. Some samples of the powders were pressed only ground and heat treated in an oven. In order to observe the structures formed in the scanning electron microscope, and correlate the structures formed by reactive process studied. Obtained structures consisting of chromium beads dispersed among a substrate of aluminum oxide, both products of the reduction reaction.
Este trabalho tem como objetivo comparar a capacidade de fornecimento de energia de cada um dos três principais tipos de moinhos de alta energia: Os moinhos “SPEX”, Planetário e “Attritor”. O sistema usado foi o óxido de cromo com alumínio metálico, ambos na forma de pós. A reação de redução do óxido de cromo pelo alumínio não ocorre instantaneamente na moagem, mas é estimulada com a ativação mecânica dos reagentes. A ativação mecânica na moagem, aliada ao tratamento térmico posterior é que faz a reação ocorrer. A comparação energética entre os moinhos foi feita em duas etapas: Na primeira etapa variou-se o poder de moagem para os três moinhos a fim de identificar o poder de moagem que proporcionou o maior pico de energia na reação, enquanto que na segunda etapa variou-se o tempo para encontrar-se o tempo de moagem que exibiu maior energia liberada na reação. Esta comparação entre os picos de energia de reação confirmou o SPEX como o moinho com maior capacidade de fornecimento de energia, ou seja: O moinho com o maior pico energia liberada, seguido pelo moinho Planetário e por fim pelo moinho Attritor. Além da comparação energética, estudou-se a influência da presença de um agente controlador de processo nos picos de energia de reação em diferentes poderes de moagem. As amostras moídas tiveram seus picos de energia da reação determinados por análises térmicas dos pós. Essa energia liberada no processo variou, tendendo a exibir um maior pico de energia para cada um dos parâmetros avaliados (poder e tempo de moagem). Fez-se o uso da difração de raios x para evidenciar a redução do material moído e tratado. Algumas amostras dos pós apenas moídos foram prensadas e tratadas termicamente em forno. A fim de se observar as estruturas formadas em microscópio eletrônico de varredura, bem como correlacionar as estruturas formadas ao processo reativo estudado. Obteve-se estruturas constituídas por esferas de cromo dispersas em meio a um substrato de óxido de alumínio, ambos produtos da reação de redução.
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Antunes, Isabel Alexandra Gonçalves. "Mechanochemistry of high temperature fuel cell materials." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/18657.
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Doutoramento em Ciência e Engenharia de MateriaisNos últimos anos, a mecanoquímica tem sido uma temática muito abordada na formação de materiais, motivada pelo grande interesse na preparação de nanopós. A sobressaturação estrutural de lacunas e a heterogeneidade química dos pós preparados por via mecanoquímica permitem melhoria na sinterabilidade, enquanto a elevada densidade dos agregados e a reduzido tamanho de cristalite produzem densidade em verde elevada. Estes fatores são extremamente atrativos na preparação de materiais cerâmicos óxidos densos, como é requerido na preparação de membranas eletroquímicas. Além disso, o processamento cerâmico por via mecanoquímica possibilita a síntese de novos materiais, que não conseguem ser sintetizados por outros métodos. Esta tese apresenta um estudo detalhado do processamento por via mecanoquímica de potenciais materiais de eletrólito e elétrodo para pilhas de combustível de óxido sólido de alta temperatura, e sua caracterização estrutural e eletroquímica. Por manipulação das variáveis do processo mecanoquímico pretende-se melhorar a capacidade de processamento e desenvolver novos materiais para aplicação em tecnologias de pilhas de combustível. A investigação foca-se, especificamente, no desenvolvimento de materiais de estrutura perovesquite à base de BaZrO3 e BaPrO3, com possíveis aplicações como condutores protónicos e condutores mistos, eletrónicos e protónicos, respetivamente.
In recent years, mechanochemistry has become an increasingly hot topic for the formation of materials, motivated by an explosion of interest in the preparation of nanopowders. The structural supersaturation by vacancies and chemical non-uniformity of mechanochemical powders promote enhanced sinterability, while the high density of aggregates and reduced crystallite density produce high green-densities. Such factors are highly attractive for preparation of dense ceramic oxide materials, as required for the formation of electrochemical-membranes. Additionally, mechanochemical ceramic processing may allow the synthesis of novel materials, which cannot be synthesized by other methods. In this thesis one offers a detailed study of mechanochemical processing for important potential electrolyte and electrode materials for high temperature solid oxide fuel cells and their subsequent structural and electrochemical characterisation. By mechanochemical manipulation one aims to improve the processing ability and to develop novel materials for fuel cell technologies. The research work is focused specifically on the development of perovskite materials based on BaZrO3 and BaPrO3, with potential applications as proton and mixed proton-electron conductors, respectively.
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Kleis, Kevin Michael. "Eccentric Workloads Generated by a Powered Rowing Machine and its Effects on Muscular Contraction and Metabolic Cost." Cleveland State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=csu1534697072520532.
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Minakata, Daisuke. "Development of aqueous phase hydroxyl radical reaction rate constants predictors for advanced oxidation processes." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37127.
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Emerging contaminants are defined as synthetic or naturally occurring chemicals or microorganisms that are not currently regulated but have the potential to enter the environment and cause adverse ecological and/or human health effects. With recent development in analytical techniques, emerging contaminants have been detected in wastewater, source water, and finished drinking water. These environmental occurrence data have raised public concern about the fate and ecological impacts of such compounds. Concerns regarding emerging contaminants and the many chemicals that are in use or production necessitate a task to assess their potential health effects and removal efficiency during water treatment.
Advanced oxidation processes (AOPs) are attractive and promising technologies for emerging contaminant control due to its capability of mineralizing organic compound via reactions with highly active hydroxyl radicals. However, the nonselective reactivity of hydroxyl radicals and the radical chain reactions make AOPs mechanistically complex processes. In addition, the diversity and complexity of the structure of a large number of emerging contaminants make it difficult and expensive to study the degradation pathways of each contaminant and the fate of the intermediates and byproducts. The intermediates and byproducts that are produced may pose potential effects to human and aquatic ecosystems. Consequently, there is a need to develop first-principle based mechanistic models that can enumerate reaction pathway, calculate concentrations of the byproducts, and estimate their human effects for both water treatment and reuse practices.
This dissertation develops methods to predict reaction rate constants for elementary reactions that are identified by a previously developed computer-based reaction pathway generator. Many intermediates and byproducts that are experimentally identified for HO* induced reactions with emerging contaminants include common lower molecular weight organic compounds on the basis of several carbons. These lower carbon intermediates and byproducts also react with HO* at relatively smaller reaction rate constants (i.e., k < 109 M-1s-1) and may significantly affect overall performance of AOPs. In addition, the structures of emerging contaminants with various functional groups are too complicated to model. As a consequence, the rate constant predictors are established based on the conventional organic compounds as an initial approch.
A group contribution method (GCM) predicts the aqueous phase hydroxyl radical reaction rate constants for compounds with a wide range of functional groups. The GCM is a first comprehensive tool to predict aqueous phase hydroxyl radical reaction rate constants for reactions that include hydrogen-atom abstraction from a C-H bond and/or a O-H bond by hydroxyl radical, hydroxyl radical addition to a C=C unsaturated bond in alkenes and aromatic compounds, and hydroxyl radical interaction with sulfur-, nitrogen-, or phosphorus-atom-containing compounds. The GCM shows predictability; factor of difference of 2 from literature-reported experimental values. The GCM successfully predicts the hydroxyl radical reaction rate constants for a limited number of emerging contaminants.
Linear free energy relationships (LFERs) bridge a kinetic property with a thermochemical property. The LFERs is a new proof-of-concept approach for Ab initio reaction rate constants predictors. The kinetic property represents literature-reported and our experimentally obtained hydroxyl radical reaction rate constants for neutral and ionized compounds. The thermochemical property represents quantum mechanically calculated aqueous phase free energy of activation. Various Ab initio quantum mechanical methods and solvation models are explored to calculate the aqueous phase free energy of activation of reactantas and transition states. The quantum mechanically calculcated aqueous phase free energies of activation are within the acceptable range when compared to those that are obtained from the experiments. These approaches may be applied to other reaction mechanisms to establish a library of rate constant predictions for the mechanistic modeling of AOPs. The predicted kinetic information enables one to identify important pathways of AOP mechanisms that are initiated by hydroxyl radical, and can be used to calculate concentration profiles of parent compounds, intermediates and byproducts. The mechanistic model guides the design of experiments that are used to examine the reaction mechanisms of important intermediates and byproducts and the application of AOPs to real fields.
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Gabriel, David Abraham. "Muscle activation patterns for goal-directed multijoint arm movements." Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28748.
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The purpose of this dissertation was to determine if the CNS produces relatively simple alterations in muscle activity to accomplish goal-directed reaching motions of the upper limb under a variety of movement conditions.To this end, six subjects performed goal-directed arm movements in the horizontal plane. Two movement amplitudes (300 mm and 400 mm) were completed at a moderate speed (1050 mm/s) and as-fast-as possible. The speed and amplitude conditions were repeated for the 45$ sp circ$ and 90$ sp circ$ movement directions. Finally, each of the movement conditions mentioned thus far, were performed within the right and left sections of the work-space. Surface electro-myographic activity was recorded from the pectoralis major, posterior deltoid, biceps brachii short head, brachioradialis, triceps brachii long head, and triceps brachii lateral head. Motion recordings were obtained with a spatial imaging system that monitored the positions of infrared emitting diodes attached to the subject's upper arm and forearm-hand complex.
Several simplification schemes were found to be operative at the level of the electro-myogram. These include: (a) simple timing relationships for agonists between joints and agonist/antagonist intermuscle latencies within each joint; (b) tightly coupled timing between agonists within a single joint; (c) for a particular movement direction, the form and shape of EMG burst activity followed a strategy associated with modulation of pulse height and width; (d) the slope, duration, and onset were further affected by the direction of hand movement which resulted in the greatest RMS-EMG signal amplitude, changing in a predictable manner, and finally (e) there was tuning in which elbow muscles were activated earlier for goal-directed arm movements in the left area of the work-space.
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Кравченко, Олег Вікторович. "Теоретичні та методологічні основи інтенсифікації хіміко-технологічних процесів видобування та переробки вуглеводневих енергоносіїв." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/31864.
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Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.17.08 – процеси та обладнання хімічної технології. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена створенню теоретичних та методологічних основ інтенсифікації хіміко-технологічних процесів для удосконалення існуючих та розробки нових ефективних хімічних технологій і обладнання видобутку та переробки вугле-водневих енергоносіїв. За допомогою використання системного аналізу процесів енергоперетворення встановлено, що лімітуючі стадії хіміко-технологічних (дифузійних, теплових, гідромеханічних, масообмінних та хімічних) процесів в технологіях видобутку та переробки вуглеводнів можна подолати, використовуючи метод об'єктно-орієнтованої активації. Доведено, що запропонований метод водневої активації процесу дифузії разом з використанням методів хімічної та механохімічної активації дозволяють суттєво збільшувати проникність ущільнених колекторів продуктивних пластів, а разом з термобарохімічною обробкою здійснювати гідрокрекінг асфальтосмолистопарафінових відкладень безпосередньо в привибійній зоні пласта. На цьому підгрунті створено технологію комплексного водневого та термобарохімічного впливу на продуктивні горизонти свердловин, ефективність якої підтверджено дослідно-промисловими впровадженнями на нафтових та газових свердловинах, в тому числі при видобутку метану вугільних родовищ. Теоретично обґрунтовано і розроблено принципово нову методологію гідро-кавітаційної активації вуглеводневовмісних емульсій і суспензій, що дає змогу завдяки інтенсифікації в них фізико-хімічних і тепломасообмінних процесів отримувати та ефективно спалювати композиційні палива з заданими енергетичними й екологічними характеристиками.Dissertation to obtain Academic Degree of Doctor of Engineering by the specialty 05.17.08 – Processes & Equipment of Chemical Technology. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2017. The Dissertation deals with creating theoretical and methodological basis of i chemical technological processes ntensification in order to improve the current and develop new efficient technology and equipment for hydrocarbon energy carriers' production and refining. System analysis of the energy transformation processes proved that the limiting stages of chemical technological (diffusive, thermal, hydro-mechanical, mass-exchanging and chemical) processes in hydrocarbons production and refining could be hurdled with the help of object oriented activation. It has also been proved that the proposed water activation method for the diffusion process together with chemical and mechanical-chemical activation provide for considerable increase of permeability of pay section compacted reservoirs. Together with thermo-baro-chemical processing the method ensures hydro-cracking of asphalt-resin-paraffin depositions directly in the bottom-hole formation zone. This foundation was used to create technology for integrated water and thermo-baro-chemical impact on wells' pay horizons, the efficiency of which was proved by experimental and industrial implementations at oil and gas wells including also methane production from coal fields. Principally new methodology for hydro-cavitational activation of hydrocarbon- containing emulsions and suspensions was theoretically substantiated and developed. It provides for obtaining composite fuels with the assigned energy and environmental characteristics due to intensification of physical, chemical and heat-mass-exchange processes.
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Кравченко, Олег Вікторович. "Теоретичні та методологічні основи інтенсифікації хіміко-технологічних процесів видобування та переробки вуглеводневих енергоносіїв." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/31863.
Full textAbstract:
Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.17.08 – процеси та обладнання хімічної технології. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена створенню теоретичних та методологічних основ інтенсифікації хіміко-технологічних процесів для удосконалення існуючих та розробки нових ефективних хімічних технологій і обладнання видобутку та переробки вугле-водневих енергоносіїв. За допомогою використання системного аналізу процесів енергоперетворення встановлено, що лімітуючі стадії хіміко-технологічних (дифузійних, теплових, гідромеханічних, масообмінних та хімічних) процесів в технологіях видобутку та переробки вуглеводнів можна подолати, використовуючи метод об'єктно-орієнтованої активації. Доведено, що запропонований метод водневої активації процесу дифузії разом з використанням методів хімічної та механохімічної активації дозволяють суттєво збільшувати проникність ущільнених колекторів продуктивних пластів, а разом з термобарохімічною обробкою здійснювати гідрокрекінг асфальтосмолистопарафінових відкладень безпосередньо в привибійній зоні пласта. На цьому підгрунті створено технологію комплексного водневого та термобарохімічного впливу на продуктивні горизонти свердловин, ефективність якої підтверджено дослідно-промисловими впровадженнями на нафтових та газових свердловинах, в тому числі при видобутку метану вугільних родовищ. Теоретично обґрунтовано і розроблено принципово нову методологію гідро-кавітаційної активації вуглеводневовмісних емульсій і суспензій, що дає змогу завдяки інтенсифікації в них фізико-хімічних і тепломасообмінних процесів отримувати та ефективно спалювати композиційні палива з заданими енергетичними й екологічними характеристиками.Dissertation to obtain Academic Degree of Doctor of Engineering by the specialty 05.17.08 – Processes & Equipment of Chemical Technology. – National Technical University "Kharkov Polytechnic Institute", Kharkov, 2017. The Dissertation deals with creating theoretical and methodological basis of i chemical technological processes ntensification in order to improve the current and develop new efficient technology and equipment for hydrocarbon energy carriers' production and refining. System analysis of the energy transformation processes proved that the limiting stages of chemical technological (diffusive, thermal, hydro-mechanical, mass-exchanging and chemical) processes in hydrocarbons production and refining could be hurdled with the help of object oriented activation. It has also been proved that the proposed water activation method for the diffusion process together with chemical and mechanical-chemical activation provide for considerable increase of permeability of pay section compacted reservoirs. Together with thermo-baro-chemical processing the method ensures hydro-cracking of asphalt-resin-paraffin depositions directly in the bottom-hole formation zone. This foundation was used to create technology for integrated water and thermo-baro-chemical impact on wells' pay horizons, the efficiency of which was proved by experimental and industrial implementations at oil and gas wells including also methane production from coal fields. Principally new methodology for hydro-cavitational activation of hydrocarbon- containing emulsions and suspensions was theoretically substantiated and developed. It provides for obtaining composite fuels with the assigned energy and environmental characteristics due to intensification of physical, chemical and heat-mass-exchange processes.
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Bampouras, Theodoros M. "Assessment of muscle activation capacity : methodological considerations of muscle mechanics and implications for testing." Thesis, Manchester Metropolitan University, 2016. http://e-space.mmu.ac.uk/617472/.
Full textAbstract:
Muscle activation capacity assessment could be affected by the mechanical behaviour of the muscle, but this aspect has received little attention. Understanding the effect the muscle's mechanical behaviour has on muscle activation capacity assessment can be paramount in achieving a better understanding of muscle function. The aim of the present Thesis was to examine the methodological implications of the mechanical behaviour of the muscle during muscle activation capacity assessment. Four studies were designed to examine the effect of the muscle-tendon unit on a) muscle activation capacity calculation methods and number of stimuli used, by manipulating quadriceps muscle length and consequently stiffness, b) stimulation intensity required and associated discomfort, by examining whether a lower than supramaximal stimulation intensity threshold, sufficient to stretch the muscle-tendon, exists, and c) the interplay between muscle mechanics and activation, by manipulating the testing position on the dynamometer, stabilisation and concurrent activation of remote muscles. Isometric knee extensions were used for all studies, and electrical stimuli was delivered to the muscle to quantify muscle activation capacity or induce muscular contractions by circumventing the voluntary neural drive. The results showed that a) altered muscle stiffness affects muscle activation values depending on the calculation method and number of stimuli used, suggesting caution to testing where muscle stiffness is likely to change, b) a lower stimulation intensity exists that can reduce subject discomfort while obtaining valid activation capacity results, widening the application of electrical muscle stimulation, and c) muscle activation must be considered in musculoskeletal models for more accurate predictions but the level of activation will ultimately depend on how stabilised the muscle is. Collectively, these results demonstrate the considerable effect muscle mechanics have on muscle activation capacity and that muscle strength assessment must take into account this aspect for more accurate inferences on muscle function.
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Cazzitti, Anne. "Etude de la phase amorphe de polyamides plastifies par spectroscopie micromecanique thermostimulee." Toulouse 3, 1988. http://www.theses.fr/1988TOU30007.
Full textAbstract:
Etude par fluage thermostimule de l'influence des parametres chimiques et physiques sur la structure de la phase amorphe de polyamides. Etude de la plastification des polyamides 11 et 12. Influence de la mise en oeuvre sur l'evolution des proprietes mecaniques de polyamides plastifies
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Prokopec, Zdeněk. "Mechanické aktivace příměsí do betonů a ověření dopadů na fyzikálně-mechanické vlastnosti čerstvých a zatvrdlých betonů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2012. http://www.nusl.cz/ntk/nusl-225684.
Full textAbstract:
This work is devoted to describe the possibilities of mechanical activations of admixtures used in concrete. Then, the verification options of grind fly ash, both from brown and black coal, from the classical as well as fluidized combustion and examination their impact on physical and mechanical properties of concrete, especially on long-term development to old age 180 days. Further attention is paid to assessing the impact of the use of mechanically activated fly ash on hydration heat evolution and the associated volume changes in the age of 1 to 90 days. In this work are presented the results of basic technological tests on concretes using admixtures, especially fly ash.