Dissertations / Theses on the topic 'Shape improvement'
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Blocher, Richard Paul. "Predictive Tools for the Improvement of Shape Memory Alloy Performance." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1556022653899471.
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Chua, Hung Soon. "Shape sensitivity of parametric CAD models and strategies for their improvement." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546029.
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Urbina, Pons Cristina. "Improvement of the one-way and two-way shape memory effects in ti-ni shape memory alloys by thermomechanical treatments." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/37358.
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Ti-Ni phase transformation behaviour is very sensitive to the thermal and mechanical history of the alloy. Thermomechanical cycling through the full transformation range may degrade the Ti-Ni functional properties (functional fatigue). These repeated transformation cycles cause changes in the SMA phase transformation behaviour due to the formation and accumulation of defects in the alloy microstructure.
The main objective of this thesis is to establish the relationships between the changes in Ti-Ni phase transformation behaviour caused by thermomechanical processes, especially in the R-phase range, and the functional properties of the Ti-Ni shape memory alloys (SMAs). Establishing these relationships should allow us to find appropriate thermomechanical processes to substantially improve the Ti-Ni one-way and two-way shape memory effects.
To achieve this objective, several experimental techniques are used including measuring variations of the electrical resistivity with temperature, X-ray diffraction, isothermal tension testing, thermal cycling under constant stress, and thermal cycling under zero stress.
This study of the phase transformation changes caused by thermomechanical processes has led to a new way of interpreting resistivity curves for calculating the transformation temperatures. Moreover, we have determined how the R-phase influences the functional properties of SMA and, finally, we have substantially improved the properties of one-way and two-way shape memory effects by using thermal processes that avoid permanent deformation of the alloy.Las transformaciones de fase en aleaciones de NiTi son altamente dependientes de la composición de la aleación, así como de la historia térmica y mecánica previa al uso de la SMA. El objetivo principal de esta tesis es establecer los vínculos existentes entre los cambios producidos en las transformaciones de fase por procesos termomecánicos y las propiedades funcionales en aleaciones con memoria de forma de Ti-Ni, tal que nos permita hallar los procesos termomecánicos más adecuados que proporcionen una mejora substancial en las propiedades funcionales de estas aleaciones. La determinación de estas relaciones, prestando especial atención a la fase-R, nos debe proporcionar las claves para incrementar las propiedades de memoria de forma y doble memoria de forma. Para la consecución de este objetivo se han usado diferentes técnicas de caracterización experimental: variación de la resistividad eléctrica con la temperatura (ER), difractometría de rayos X (DRX), ensayos de tracción isotérmicos, ciclados térmicos a tensión constante y ciclados térmicos a tensión nula. A través del estudio exhaustivo de las transformaciones de fase, se ha aportado una nueva interpretación de las curvas de resistividad para el cálculo de las temperaturas de transformación, se ha determinado la influencia de la fase-R en las propiedades funcionales de las SMA y se han mejorado substancialmente las propiedades de memoria simple y doble memoria de forma mediante procesos térmicos que evitan deformaciones permanentes antes del uso de la aleación.
Les transformacions de fase en aliatges de NiTi són altament dependents de la composició de l'aliatge, així com de la història tèrmica i mecànica prèvia a l'ús de la SMA. L'objectiu principal d'aquesta tesi és establir els vincles existents entre els canvis produïts en les transformacions de fase per processos termomecànics i les propietats funcionals en aliatges amb memòria de forma de Ti-Ni, tal que ens permeti trobar els processos termomecànics més adequats que proporcionin una millora substancial en les propietats funcionals d'aquests aliatges. La determinació d'aquestes relacions, prestant especial atenció a la fase-R, ens ha de proporcionar les claus per incrementar les propietats de memòria de forma i doble memòria de forma. Per a la consecució d'aquest objectiu s'han usat diferents tècniques de caracterització experimental: variació de la resistivitat elèctrica amb la temperatura (ER), difractometria de raigs X (DRX), assaigs de tracció isotèrmics, ciclats tèrmics a tensió constant i ciclats tèrmics a tensió nula. A través de l'estudi exhaustiu de les transformacions de fase, s'ha aportat una nova interpretació de les corbes de resistivitat per al càlcul de les temperatures de transformació, s'ha determinat la influència de la fase-R en les propietats funcionals de les SMA i s'han millorat substancialment les propietats de memòria simple i doble memòria de forma mitjançant processos tèrmics que eviten deformacions permanents abans de l'ús de l'aliatge.
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Navajas, Valentini Elly Ana. "Carcass shape and meat eating quality in sheep : opportunities for genetic improvement using computed tomography." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/27108.
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This thesis reports on an investigation of the association between muscularity and meat quality in Scottish Blackface (SBF) and Texel (TEX) lambs, and the in vivo assessments of these traits using X-ray computed tomography (CT) with a view to their possible inclusion in breeding programmes. The objectives of this work were: (i) to develop comprehensive in vivo assessments of muscularity using spiral CT scans; (ii) examine the relationship of the new muscularity indices with carcass and eating quality; (iii) explore the associations among CT assessments of carcass composition, muscularity and muscle density, and (iv) investigate the possibility of limiting the antagonism between selection for reduced fatness and maintaining eating quality by introducing a CT predictor of intramuscular fat (IMF) as an additional selection criterion for the breeding programmes using CT. The calculation of muscularity indices requires the measurement of the muscle mass and skeletal dimension of the regions of interest. Priority was given to the hind leg (HL) and lumbar region (LR), where high priced cuts are located. The utilisation of new novel imaging technology called spiral CT scanning, which captures detailed information on any specific region, was explored. An algorithm to automatically segment the spiral CT scans (SCTS), and procedures to assess the real dimensions of skeletal structures, were developed. Compared to previous CT m uscularity measurements, the accuracy was much higher with the new index in the HL (correlations with equivalent indices bases on dissection of 0.89 vs 0.51). The accurate measurement of femur length by CT used in the calculation of the new HL index made an important contribution to the higher accuracy of the index. The improvement in accuracy was smaller for the LR (0.55 vs 0.44). The association of CT muscularity indices and carcass traits by dissection in both breeds showed that improved muscularity is not phenotypically correlated with detrimental effects on other carcass quality traits. The correlation coefficients, after adjusting for carcass weight, were positive with meat yield and low and negative, or close to zero, with fatness. This is particularly relevant for the terminal sire breeds, in which the economically important traits included in breeding programmes tend to be carcass composition traits. In the case of SBF, the CT muscularity indices provide an opportunity to improve carcass conformation, a trait included in current breeding objectives. Differences in muscularity of the HL and LR, assessed by the CT muscularity indices, and eating quality were investigated between sexes (ram vs ewe lambs), breeds (SBF vs TEX) and progeny of high- and low-muscularity sires (HM, LM). TEX lambs had 16% greater muscularity than SBF in both regions, whilst differences between sire groups were 4%. Ewe lambs had slightly higher values of muscularity for the F1L than rams but no difference was found for the LR. Meat from SBF lambs was more tender, and had stronger lamb flavour and higher overall liking scores than TEX meat. Sex had a weak influence with ram lambs having a stronger abnormal flavour and lower overall liking in the LR only. No significant differences in meat eating quality were found between HM- and LM-sired lambs, suggesting that improved muscularity would not have unfavourable effects on sensory traits. Genetic parameters for the CT muscularity indices, predictions of carcass muscle and fat weights and CT muscle density were estimated. The estimates of heritabilities of the CT muscularity indices showed they were at least moderately heritable (from 0.38 to 0.92) in both breeds. CT muscle density, measured in the LR, had a moderate to high heritability in both breeds, and strong negative genetic and phenotypic associations with IMF and carcass fat weight. Little association was found between muscularity indices and CT muscle density, implying that improved muscularity would not have a negative effect on CT muscle density. These results suggest, overall, that the effect of selection for improved muscularity of sheep is likely to be favourable for carcass quality and neutral with respect to meat eating quality. Because of the strong phenotypic and genetic associations with IMF, CT muscle density may be a promising selection tool to counteract possible negative effects of decreasing fatness on IMF and therefore eating quality. The inclusion of CT muscle density as a selection criterion allowed more favourable genetic responses in IMF, without further unfavourable increases in carcass fat weight or detrimental effects on leanness. Because increased economic values for IMF led to different expected gains in IMF and other traits in the breeding goal, the definition of the specific values depends on the desired gains in all traits by the industry. Positive returns for the industry from using CT muscle density at the second stage of selection can be obtained for all economic values included in this simulation. The economic benefits were maximised when the proportions of ram lambs CT scanned were 0.15.
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Turek, Vojtěch. "New Elements of Heat Transfer Efficiency Improvement in Systems and Units." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-234141.
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Zvýšení efektivity výměny tepla vede k poklesu spotřeby energie, což se následně projeví sníženými provozními náklady, poklesem produkce emisí a potažmo také snížením dopadu na životní prostředí. Běžné způsoby zefektivňování přenosu tepla jako např. přidání žeber či vestaveb do trubek ovšem nemusí být vždy vhodné nebo proveditelné -- zvláště při rekuperaci tepla z proudů s vysokou zanášivostí. Jelikož intenzita přestupu tepla závisí i na charakteru proudění, distribuci toku a zanášení, které lze všechny výrazně ovlivnit tvarem jednotlivých součástí distribučního systému, bylo sestaveno několik zjednodušených modelů pro rychlou a dostatečně přesnou predikci distribuce a také aplikace pro tvarovou optimalizaci distribučních systémů využívající právě tyto modely. Přesnost jednoho z modelů byla dále zvýšena pomocí dat získaných analýzou 282 distribučních systémů v softwaru ANSYS FLUENT. Vytvořené aplikace pak lze využít během návrhu zařízení na výměnu tepla ke zvýšení jejich výkonu a spolehlivosti.
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Belinski, Robert A. "An analysis, design, and improvement methodology for shape rolling processes and procedures for the compensation of dies." Ohio : Ohio University, 1999. http://www.ohiolink.edu/etd/view.cgi?ohiou1175264501.
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Adams, Ryan, and s200866s@student rmit edu au. "Evaluation of computerised methods of design optimisation and its application to engineering practice." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070130.122013.
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The ongoing drive for lighter and more efficient structural components by the commercial engineering industry has resulted in the rapid adoption of the finite element method (FE) for design analysis. Satisfied with the success of finite elements in reducing prototyping costs and overall production times, the industry has begun to look at other areas where the finite element method can save time, and in particular, improve designs. First, the mathematical methods of optimisation, on which the methods of structural design improvement are based, are presented. This includes the methods of: topology, influence functions, basis vectors, geometric splines and direct sensitivity methods. Each method is demonstrated with the solution of a sample structural improvement problem for various objectives (frequency, stress and weight reduction, for example). The practical application of the individual methods has been tested by solving three structural engineering problems sourced from the automotive engineering industry: the redesign of two different front suspension control arms, and the cost-reduction of an automatic brake tubing system. All three problems were solved successfully, resulting in improved designs. Each method has been evaluated with respect the practical application, popularity of the method and also any problems using the method. The solutions presented in each section were all solved using the FE design improvement software ReSHAPE from Advea Engineering Pty. Ltd.
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Peng, You Ph D. Massachusetts Institute of Technology. "Crystallization of calcium sulphate during phosphoric acid production : improving filtration through improvement in particle shape and size distribution." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/117887.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 155-162).
The production of phosphoric acid from phosphate mineral rock involves the addition of phosphate rock to a concentrated sulfuric acid solution. The induced reactive crystallization process produces a side product of calcium sulfate hydrates, which become the filter media in the subsequent acid separation process. For most industrial processes, the dihydrate form of calcium sulfate crystals (gypsum) precipitates and its shape and size distribution are key factors in determining the downstream filtration efficiency. Particularly, the metal ion impurities coming from raw phosphate rock play an important role as shape modifiers. The presence of impurities in the acid mixture has an impact both thermodynamically and kinetically, although most of the available literature focuses on their sole role as growth inhibitors and has neglected their potential impact on altering solution speciation. Past studies on gypsum crystallization in phosphoric acid solutions usually involve the study of crystal growth and nucleation kinetics. However, most of these works did not use the correct definition of supersaturation when quantifying kinetic parameters. The high concentrations in this multicomponent electrolyte system implies that supersaturation, which be written in terms of the solubility product ratio, as governed by nonideal thermodynamics, requires the computation of activity coefficients as well as free ion concentrations. For this purpose, the mixed solvent electrolyte (MSE) model is utilized to capture the solution speciation in order to properly quantify supersaturation at any given condition. The MSE model is a first-principles model that determines solid-liquid equilibrium by calculating excess Gibbs energy from additive pairwise interactions. When impurities are present, additional binary interactions need to be included in the databank, which is carried out by regression analysis using solubility measurements. Continuous reactive crystallization experiments are carried out with and without additives using a mixed-suspension, mixed-product removal (MSMPR) crystallizer. The crystal size distribution and supersaturation are measured once the process reaches steady state. Different conditions are imposed to acquire both the temperature and supersaturation dependency of the crystallization kinetics. A two-dimensional growth model with dispersion is developed in order to capture the needle-like crystal morphology and the temperature dependence of the crystal aspect ratio, which is made possible by performing multi-scale image segmentation and edge detection using the Canny method. Experimental and numerical results are obtained for the base system and in the presence of single and combined impurity ions. Different growth inhibition models are verified and compared for numerical quantification of step advancement retardation in the presence of impurities. This study goes beyond past studies by providing a full two-dimensional kinetic model for a highly concentrated ionic system that includes crystallization kinetics and a thermodynamically correct driving force accounting for non-ideality as well as the effects of impurities.
by You Peng.
Ph. D.
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Scheller, Johannes. "Electroactive morphing for the aerodynamic performance improvement of next generation airvehicles." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14479/1/scheller_partie_1_sur_2_2.pdf.
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The need to improve the aerodynamic performance of air vehicles is the origin of intense research on the real-time optimization of the airfoil shape. This real-time optimization can only be achieved by morphing the airfoil using adequate materials and actuators. The object of this thesis is to study smart-material actuators for aerodynamic performance optimization on different time scales (low-frequent and high-frequent actuation). First, the effects of the distinct actuation types, low-frequency large-displacement shape-memory alloy (SMA) and high-frequency low-displacement piezoelectric, on the surrounding flow are analyzed separately using dedicated time-resolved particle image velocimetry (TR-PIV) measurements. The experiments showed the deformation capacity of the SMA technology under realistic aerodynamic loads. Furthermore, it was highlighted that despite the limited actuation frequency the “quasi-static” hypothesis has to be carefully adapted for the Reynolds number range of 200.000. The PIV measurements conducted behind the piezoelectrically actuated trailing edge showed the capacity of the actuator to reduce the shear-layer instability modes. An open-loop optimum actuation frequency of 60 Hz has been identified. Secondly, a hybridization of the two previously studied technologies has been proposed. The implied actuators, SMAs and macro fiber composites (MFCs), have been modelled and the combined actuation capacity has been demonstrated. The designed prototype NACA4412 airfoil has been tested in the S4 wind-tunnel of IMFT and it was shown that the combination of the two technologies allows acting on the shear-layer vortices as well as control the lift.
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Oschmann, Tobias Sebastian [Verfasser], Harald [Akademischer Betreuer] Kruggel-Emden, Harald [Gutachter] Kruggel-Emden, and Viktor [Gutachter] Scherer. "Extension and improvement of the coupled CFD-DEM approach to describe multidimensional heat transfer and non-spherical particle shape for fluidized systems / Tobias Sebastian Oschmann ; Gutachter: Harald Kruggel-Emden, Viktor Scherer ; Betreuer: Harald Kruggel-Emden." Berlin : Technische Universität Berlin, 2019. http://d-nb.info/1184983836/34.
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GOPAL, SRIKANT. "SYNTHESIS, MODIFICATION, CHARACTERIZATION AND CATALYTIC STUDIES OF ZEOLITE BASED BIFUNCTIONAL CATALYSTS FOR HYDROISOMERIZATION REACTION." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061218813.
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Salem, Yousef. "Clinical evaluation of shade improvement after in-office vital bleaching." University of the Western Cape, 2010. http://hdl.handle.net/11394/5383.
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Magister Scientiae Dentium - MSc(Dent)Tooth discoloration has increased the demand by patients to pursue aesthetic treatment options. Bleaching is considered a conservative approach in performing an aesthetic treatment for discolored teeth; however colour rebound and post-operative sensitivity are among the adverse effects associated with vital bleaching. In-office bleaching systems employ the use of high hydrogen peroxide concentrations. The effects of in-office bleaching agents on the degree of colour change and the gender differences in relation to bleaching outcomes are questionable. Post-operative sensitivity can be considered a bleaching side effect and the number of patients that experience it is unknown.Aim: The aim of this study was to assess the outcome of an in-office vital bleaching technique. Objectives: The objectives of this study were to evaluate the degree of colour change after vital tooth bleaching using a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain), using a spectrophotometer (CM-2600d Konica, Minolta) to measure the colour change at each intervention during the bleaching process, to assess the post-operative sensitivity during the first week of the intervention, to evaluate the patients' perception of the colour change and to compare it to the colour change (ΔE) expressed in numeric values and to investigate whether gender differences exist in relation to the outcome of the bleaching procedure. Materials and Methods: The maxillary anterior teeth of 22 patients comprising of 11 males and 11 females were bleached with a 35% hydrogen peroxide gel (Yotuel® Special, Biocosmetics Laboratories, Spain). Pre-treatment readings of the two maxillary central incisors using a spectrophotometer (CM-2600d Konica, Minolta) were obtained. Subsequent readings were obtained after scaling and polishing, before bleaching (which was used as a baseline reading), immediately after bleaching, one week and one month post-operatively. Patients were requested to complete a form regarding post-operative tooth sensitivity and their colour perception toward the bleaching treatment. Results: The quantitative effect of the bleaching material on tooth colour showed an increase in L* values and a decrease in a* and b* values, the changes were significant (p values ≤ 0.05) except for the mean value of b* one month after bleaching which was only significant between five and ten percent.The mean values of colour change measured as ΔE between baseline and after bleaching was found to be 3.4 which did not exceed the visible colour change perceptible clinically at a difference of 3.7 units according to the literature. However nine patients exceeded the visible clinical colour change immediately after bleaching. There was no gender difference in the ΔE values in the entire bleaching process. Tooth sensitivity is considered a bleaching side effect and in this study sensitivity was traced until the fifth day after bleaching. The mean value of patients' tooth sensitivity was found to be 1.73 in the first day on a 4 point visual analog scale. The mean value of patients' colour perception was found to be 2.14 immediately after bleaching on a 3 point visual analog scale. Spearman correlation tests showed a positive relationship between ΔE values immediately and one week after bleaching and a weak relationship one week and one month after bleaching. There was significant consistency in the patients‟ colour perception data immediately and one week after the bleaching process and a weak relationship between ΔE values and patients' colour perception one month after bleaching. Conclusion: Yotuel® Special, Biocosmetics Laboratories, (Spain) an in-office bleaching material consisting of 35% hydrogen peroxide was able to bleach patients' teeth with a perceptible colour change however the chalky white teeth desired were not obtained for all the patients. Tooth sensitivity was a temporary side effect.
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McLaughlin, Belinda. "Corporate Social Responsibility Factors in Market Share and Financial Performance Improvement." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/4389.
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Some corporate leaders lack knowledge of CSR strategies to improve corporate financial performance. Businesses increase their profit margins when the business leaders integrate social and environmental management into core business processes. Grounded in stakeholder theory, this multicase study involved an exploration of corporate social responsibility factors that contributory to improving market share and financial performance. One-on-one interviews took place, and corporate leaders of 3 Native American owned companies that have implemented successful CSR strategies to improve market share and financial performance within the Midwestern area of the United States, including Kansas, Missouri, and Oklahoma. Data triangulation involved the use of field observations, organizational background information, and review of archival records. Modified van Kaam method was instrumental to identifying the variation of potential structural meanings embedded within textural implications as well as to expose core themes and contexts that contribute to the apparent presence of the phenomenon. Some themes that emerged from this study included corporate social responsibility strategies, core value and views, and indications. These themes developed through efforts to identify the CSR strategies and outcomes of Native-owned gaming operations. Identifying successful CSR strategies encourages more companies to participate in socially responsible initiatives. Illustrating successful CSR efforts within Native gaming operations can transform business practices, enhance social performance, and generate positive social change in communities through transforming local Native American communities into vibrant cohesive societies for families to thrive in.
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Elshenawy, Tamer Abdelazim. "Criteria of design improvement of shaped charges used as oil well perforators." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/criteria-of-design-improvement-of-shaped-charges-used-as-oil-well-perforators(d627c23e-a05b-42a2-86c3-6d67dfd7b7a7).html.
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In addition to its various military applications, shaped charges have been used in oil industry as an oil well perforator (OWP) to connect oil and gas to their reservoirs. The collapse of the liner material under the explosive load produces a hypervelocity jet capable of achieving a deep penetration tunnel into the rock formation. The achieved penetration depends on the OWP design, which includes the geometry and the material of the explosive and the liner as well as the initiation mode and the casing of the shaped charge. The main purpose of this research is to assess the performance of OWP with different design aspects in terms of its penetration depth into concrete material.This research employed the Autodyn finite difference code to model the behaviour of OWPs in the stages of liner collapse, jet formation and jet penetration. The design parameters of OWPs were studied quantitatively to identify the effect of each individual parameter on the jet characteristics and the jet penetration depth into concrete material according to the API-RP43 standard test configuration. In order to validate the Autodyn jetting analysis, this research compared the jetting simulation results of copper OWP liners with those obtained from flash x-ray measurements while the numerical jet penetration into the laminated concrete target was validated experimentally by the static firing of OWPs. Above-mentioned experiments were designed and performed in this project.The validated hydrocode was implemented in this research to study the effects of the concrete target strength, the liner material and the liner shape on the jet penetration depth into concrete targets.For the target strength, the traditional virtual origin (VO) penetration model was modified to include a strength reduction term based on Johnson’s damage number and the effect of the underground confinement pressure using Drucker-Prager model. The VO analytical model is also implemented in the liner material study to account for the jet density reduction phenomena and its induced reduction of jet penetration capability. The jets obtained from machined copper and zirconium liners and from copper-tungsten powder liner all exhibited the density reduction phenomena. The modified VO model considers the non-uniform distribution of jet density based on the jet profile analysis using Autodyn and the experimental soft recovery for some tested liners. The results lead to a modified VO penetration model including the non-uniform jet density effect.For zirconium liner material, numerical and analytical studies were conducted for different flow velocities and different collapse angles in order to determine the boundaries between the jetting and non-jetting phases and whether a coherent or a non-coherent jet will form. This study indicated that the suggested four different liner shapes (i.e. the conical, the biconical, the hemispherical and the bell) will produce coherent jet when the zirconium is used as OWP liner.The validated Autodyn hydrocode is also used in this thesis to calculate the velocity difference between two neighbouring zirconium jet fragments. The velocity difference is related directly to the breakup time of an OWP jet, and thus, it is calculated for a range of zirconium liners with different liner wall thicknesses. The calculated values of velocity difference gave a clear insight for the breakup time formulae for zirconium jet in terms of the liner thickness and the charge diameter.
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Forbes, Daniel. "Efficiency Performance Improvement Using Parallel DC-DC Converters with a Digital Controller." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/736.
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A system to improve efficiency performance of a DC-DC converter is simulated and built. The proposed system combines multiple DC-DC converters in parallel and implements a digital control scheme and load-share controller. A model of the system is developed in MATLAB Simulink and the model demonstrates the improved converter’s efficiency particularly at low load conditions. This simulation is then designed into a hardware system running three DC-DC converters in parallel, controlled by a microcontroller and a load-share controller. The hardware also confirms the simulation results, although some hardware refinements are evident as simulation results are superior. The system is designed to be scalable in the number of converters and the total output power, as well as being DC-DC converter topology-independent. Simulation results show the system maintaining better than 88 % efficiency over almost 90 % of the load range of the system. This system could be implemented where dynamic loads typically occur, such as in electric vehicle charging.
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Wikström, Jenny. "Present-day constraints and prospects for improvements in shade management in cacao cultivation in two Mayan villages in Toledo District, Belize." Thesis, Högskolan i Gävle, Akademin för teknik och miljö, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16567.
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Slash-and-burn agriculture is, under conditions with increasing pressure on resources, one cause of deforestation and land degradation. The Mayas of southern Belize use a type of slash-and-burn farming which is currently degrading the environment. On the other hand, cacao cultivation can be an integrated part of multi-storey agroforestry systems, indicated to provide capacity to maintain biodiversity. The Mayas have traditionally farmed cacao and it is now becoming an important cash crop in the district. Institutional stakeholders in Toledo district and six cacao farmers in two Mayan villages was interviewed for this study. The focus was to identify perceived constraints and prospects, as well as considerations of improvements, in shaded cacao cultivation. The farmers who participated in this study produce organic cacao under small-scale farming conditions, growing cacao under a canopy of mainly fruit and timber trees, providing income and food. Banana/plantain (Musa sp.), Salmwood (Cordia alliodora) and Cedar (Cederela odorata) are common shade species. Shade trees are randomly planted and timings for shade management is varying. Many of the farmers experience that their shade management can improve. Weather, disease, income and lack of knowledge are some of the issues in shaded cacao farming in the south of Belize. There is an on-going development of the local cacao market and the organic and Fair Trade production is constantly growing. More attention needs to be given to further research for improvements in shade management, as well as better access to resources for the local cacao farmers.
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Ukkonen, K. (Kaisa). "Improvement of recombinant protein production in shaken cultures:focus on aeration and enzyme-controlled glucose feeding." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203621.
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Abstract Efficient production of biologically functional recombinant proteins is a cornerstone of modern biotechnological research. Laboratory-scale protein production is most commonly accomplished in simple shaking bioreactors such as shake flasks. However, productivity of these cultures is often severely limited by low biomass yield and non-optimal growth conditions regarding medium composition, pH and oxygen supply. In many cases, poor culture performance can constitute a major research bottleneck. This study aims to improve recombinant protein production in shaking Escherichia coli cultures by use of enzyme-controlled, fed-batch-like glucose feeding in a rich medium, and by investigating the effects of culture aeration on different aspects of protein production. The results show that the enzymatic fed-batch medium can provide higher cell densities, volumetric protein yields and, in some cases, improved product solubility or activity compared to traditionally used media. While these improvements could be obtained in ordinary shaking vessels, the results also demonstrate that cultivation in shake flasks with elevated aeration capacity can further improve cell density and volumetric productivity in the fed-batch medium. However, enhanced aeration may also have an adverse effect on the expression of certain proteins such as Fab antibody fragments. Maximum volumetric Fab yield was achieved under reduced aeration rates, and lower oxygen availability also contributed to substantially increased accumulation of periplasmically produced Fab fragments into extracellular medium. Hence modification of aeration conditions and medium composition can be used to control periplasmic/extracellular product localization as outlined in this study. Moreover, high aeration was detrimental to expression in a glycerol-based lactose autoinduction medium, but this strict dependency on aeration level could be mitigated and robustness of expression improved by an autoinduction medium based on the enzymatic glucose feeding as the supporting carbon source instead of glycerol. The results of this study can be utilized to improve volumetric productivity, protein solubility and control of product localization in small-scale protein production, as well as to facilitate robust and efficient high-throughput protein expression for such applications as structural and functional characterizationTiivistelmä Biologisesti aktiivisten vierasproteiinien tehokas tuottaminen on yksi bioteknologisen tutkimuksen kulmakivistä. Laboratoriomittakaavan proteiinituotto toteutetaan yleisimmin yksinkertaisissa ravistelubioreaktoreissa, kuten ravistelupulloissa. Näiden viljelmien tuottavuutta rajoittaa kuitenkin usein biomassan matala saanto sekä epäoptimaaliset olosuhteet kasvualustan koostumuksen, pH:n ja hapen suhteen. Monissa tapauksissa viljelmän heikko tuottavuus muodostaa tutkimukselle merkittävän pullonkaulan. Tämän tutkimuksen tavoite on parantaa vierasproteiinien tuottoa Escherichia coli –ravisteluviljelmissä hyödyntäen entsymaattisesti kontrolloitua, panossyöttökasvatusta jäljittelevää glukoosisyöttöä rikkaassa kasvualustassa, sekä selvittää ilmastuksen vaikutusta proteiinituoton eri osatekijöihin. Tulosten mukaan glukoosisyöttöön perustuva kasvualusta mahdollistaa korkeamman solutiheyden sekä proteiinituoton verrattuna tavallisimmin käytettyihin kasvualustoihin. Joissain tapauksissa myös proteiinin liukoisuus tai aktiivisuus voi parantua. Vaikka nämä edut pystyttiin saavuttamaan myös tavanomaisissa ravistelupulloissa, voidaan panossyöttökasvualustan solutiheyttä ja tuottoa tilavuutta kohti edelleen lisätä käyttämällä korkeamman ilmastustehokkuuden ravistelupulloja. Toisaalta tehostetun ilmastuksen havaittiin olevan mahdollisesti haitallista tiettyjen proteiinien, kuten Fab-vasta-ainefragmenttien, tuotolle. Fab-fragmenttien maksimaalinen tuotto saavutettiin ilmastustehokkuutta laskemalla. Lisäksi matalampi hapen saatavuus edisti periplasmaan ohjattujen Fab-fragmenttien kerääntymistä solunulkoiseen kasvualustaan. Näin ollen ilmastusolosuhteita ja kasvualustan koostumusta muokkaamalla voidaan vaikuttaa tuotteen lopulliseen sijoittumiseen. Korkean ilmastustehokkuuden havaittiin myös olevan haitallista proteiinituotolle glyserolipohjaisessa autoinduktiokasvualustassa. Tätä riippuvuutta ilmastuksen tasosta pystyttiin vähentämään ja autoinduktion luotettavuutta parantamaan käyttämällä kasvualustaa jossa hiililähteenä toimii glyserolin sijaan entsymaattinen glukoosisyöttö. Tutkimuksen tuloksia hyödyntäen voidaan parantaa vierasproteiinien saantoa, liukoisuutta ja periplasmisen/solunulkoisen kerääntymisen säätelyä, sekä mahdollistaa luotettava ja tehokas proteiinituotto viljelmien suurta lukumäärää vaativiin sovelluksiin, kuten proteiinien rakenteen ja toiminnan tutkimukseen
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Almadi, Alaa. "Investigating mechanical properties of ordinary portland cement : investigating improvements to the mechanical properties of Ordinary Portland Cement (OPC) bodies by utilizing the phase transformation properties of a ceramic (zirconia)." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/7315.
Full textAbstract:
The effects of metastable tetragonal zirconia on the properties of Ordinary Portland Cement were observed during which the effect of crystallite size pH on the preparation solution, precursor salt, and the presence of co-precipitates, Fe(OH)3, SnO2 and SiO2 on the crystallization temperature, enthalpy and crystal structure, immediately following the crystallization exothermic burst phenomenon in ZrO2 were measured. Thermal analysis and x-ray methods were used to determine crystallite sizes and structures immediately following the exothermic burst. Comparisons were made for zirconias prepared from oxychloride, chloride and nitrate solutions. The existence of tetrameric hydroxidecontaining ions in oxychloride precursor is used to rationalise low values of crystallization enthalpy. The position of the crystallization temperature, Tmax was not dependent on crystallite size alone but also on the pH at which the gel was made, the surface pH after washing, and the presence of diluent oxides. Enthalpy v r1/2 and Tmax v (diluent vol)1/3 relationships indicate that surface coverage effects dominate a surface nucleated phenomenon. The data established for ZrO2 systems was used to develop tetragonal-ZrO2-SnO2 powders capable of improving the mechanical properties of Ordinary Portland Cement discs. The ZrO2-OPC discs were prepared by powder mixing, water hydration and uniaxial pressing. Vicat needle tests showed that tetragonal-ZrO2 increases the initial setting rate. Microscopy indicated that porosity distribution changes near to ZrO2 particles. Zirconia has also been introduced into OPC discs by vacuum infiltration methods developed for solutions and colloidal suspensions. Comparisons between OPC discs and the OPCtetragonal ZrO2 composites have been made on the basis of diametral compression strength, Young’s modulus, hardness and toughness (K1c), as estimated by the cracked indentation method. Bell-shaped curves are found for the way the mechanical properties are changed as a function of Zirconia content.
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Kašparová, Petra. "Dopad rekodifikace občanského a obchodního práva na české účetní předpisy." Master's thesis, Vysoká škola ekonomická v Praze, 2013. http://www.nusl.cz/ntk/nusl-191579.
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The Czech accounting standards have been amended many times yet. They were nevertheless adjusted in connection with the recodification of the private law on January 1st, 2014. Main output of this recodification was "The new civil code" and "The law about commercial corporations". The diploma thesis examines the impact of these legal standards on the Czech accounting standards. Apart from that, the new civil law brings also new terminology, what has consequently an impact on legislative and technical changes of the Czech accounting standards. Moreover the thesis talks about selected recodification areas, which significantly interfere in accounting. It is mainly the new concept of properties, trust, earnest payment and paying of prepayments on share on profit. Last but not least, the thesis tries to explain the new definition of technical improvement.
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Dvořáková, Monika. "Vliv zákaznické spokojenosti a dalších ukazatelů na tržní podíl společnosti." Master's thesis, Vysoká škola ekonomická v Praze, 2014. http://www.nusl.cz/ntk/nusl-192443.
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In the present hypercompetitive market environment of car producers established especially at the developed west european markets is very difficult to gain new customers and increase the market share. The car producing companies have to build and increase customer loyalty to ensure the sustainable growth of market share in the future. One possibility how to improve customer's loyality to brand is to provide the highest standard at both sales and service department and carefully monitor the customer satisfaction. From the satisfaction and performance indicators of the car producing company is possible to construct a mathematical model producing the market share in a given country as an output. Key indikators of customer satisfaction, sales and service and also the macroeconomical data has been used as the inputs for the model. As a target market for my analysis has been chosen Germany. This thesis presents a set of recommendations and proposals, whose implementation should ensure the improvement of the market share of the given brand on german market. The recommendation does not include only the tips for improvement of the key indicators but it also gives the overview of how to make the marketing strategy more efficient using Customer relationship management.
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Sanchez, Sanchez Hector. "The evaluation and improvement of 3D shape acquisition techniques." 2004. http://hdl.handle.net/1993/15759.
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Hsiu, Yang-Cheng, and 楊政修. "The Improvement of Erosion-Resistanceof TiNi Shape Memory Alloys." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/4fmypq.
Full textAbstract:
碩士逢甲大學
材料科學所
90
Abstract The Ti49Ni51 and Ti50Ni50 alloys were used and prepared by vacuum arc remelting technique. We studied the basic properties and erosion characteristics of these alloys subjected to solution treatment, aging and cold working. The erosion characteristics of these alloys have been systematically studied by using cavitation erosion, gas-solid and liquid-solid impingement tests. Experimental results show that the aged Ti49Ni51 alloy can exhibit a better erosion resistance because of the effects of precipitate hardening and stress-induced martensitic (SIM) transformation. The work-hardening increases the alloy’s strength and hardness, but the alloy’s erosion resistance decreases because of the decreased ductility and toughness. The gas-solid and liquid-solid impingement tests have similar erosion behavior. The impinged morphologies exhibit a lot of long and narrow furrows at low impingement angles, but the overlapped chips at high impingement angles. In the liquid-solid impingement tests, there appears the maximum erosion rate at the impinged angle of 30~45° . The erosion rate of gas-solid impingement is larger than that in liquid-solid impingement. The gas-solid impingement has the maximum erosion rate at impinged angle of 45~60° . After impingement tests, the lattice structures of all TiNi alloys have been distorted. This effect results in the broadened XRD peak with lower peak intensity. Mean while, the stress-induced martensitic (SIM) and stress-induced R-phase (SIR) transformation also occur during the impingement.
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Delgado, João Ricardo Ferreira. "A SDK improvement towards gesture support." Master's thesis, 2014. http://hdl.handle.net/10362/14100.
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Human-Computer Interaction have been one of the main focus of the technological community, specially the Natural User Interfaces (NUI) field of research as, since the launch of the Kinect Sensor, the goal to achieve fully natural interfaces just got a lot closer to reality. Taking advantage of this conditions the following research work proposes to compute the hand skeleton in order to recognize Sign Language Shapes.
The proposed solution uses the Kinect Sensor to achieve a good segmentation and image analysis algorithms to extend the skeleton from the extraction of high-level features. In order to recognize complex hand shapes the current research work proposes the redefinition of the hand contour making it immutable to translation, rotation and scaling operations, and a set of tools to achieve a good recognition.
The validation of the proposed solution extended the Kinects Software Development Kit to allow the developer to access the new set of inferred points and created a template-matching based platform that uses the contour to define the hand shape, this prototype was tested in a set of predefined conditions and showed to have a good success ration and has proven to be eligible for real-time scenarios.
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SU, PEI-CHEN, and 蘇培珍. "Properties Improvement of Ti49Ni51 Shape Memory Alloy by Cold-Rolling." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/84904778706639552215.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
91
Transformation behaviors and mechanical properties of Ti49Ni51 shape memory alloy after cold rolling and subsequent aging were investigated in this study. After cold rolling and aging, the martensitic transformation of Ti49Ni51 is suppressed. As the rolling reduction increases, transformation ΔH decreases as well. Under 500℃ aging for a long period, it appears a four-step multi-stage transformation (MST), which is not found in previous researches where showed mostly three-step MST. In this four-step MST, one is B2àR, and among the other three steps, two are B2àM and one is RàM. The recrystallization texture of Ti49Ni51 after cold rolling and aging is mostly <110>α-fiber II paralleled to rolling direction (RD). In the tensile test and cyclic test of 4% strain control, the direction being perpendicular to RD (90˚) exhibits the largest stress, while the direction paralleled to RD has the smallest. Besides, the orientation dependence of irrecoverable strain for long-time and short-time aged specimens are in contrast. In the cyclic test, the 25th cyclic stress-strain curve shows the linear-superelasticity, and the specimens directed 60˚ from RD behave the largest hysteresis. In the DMA tests, the same specimens also show a relaxation peak at around -70℃. This indicates that the textured Ti49Ni51 directed in 60˚ from RD has the most easily move of twin boundaries. After 400℃×24h aging, textured Ti49Ni51 specimens in each direction from RD show 100% shape memory effect(SME), which means that the texture has no explicit effect on Ti49Ni51 SME.
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Li, Zhi-Qing, and 李志清. "Analysis and Improvement of Warping andSpringback for Aluminum Alloy U-shape Bending." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/zzsdxt.
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碩士國立臺北科技大學
製造科技研究所
96
This study mainly develops a simulation algorithm to analyze the stresses and deformation behavior of aluminum sheet metal (A5052P-H32) going on U-shape bending in a circular die cavity using ABAQUS finite element programs. The diameter of the round die is 60 mm, depth of U-shape bending is 50.8 mm, and the thickness of sheet material is 1/32" (0.794 mm). The variables considered for bending simulation include different width of sheet metal ranging from 20 mm to 50 mm, two average punching speeds (63 mm/sec and 151 mm/sec), and with or without using stripper under the bottom surface of sheet metal during punching. In this study, we choose single crank type press to proceed a set of bending experiments, and use dynamometer (Kistler 9257B) to measure the varying punching forces for the purpose of comparison with present simulation results. The simulation results are very close to experimental results, and they show some features as follows: (1) When punching without using stripper, the bottom side of finished U-shape part warps more as the sheet blank increases its width, iii e.g. as the blank is 50 mm wide, the warping may reach approximately 6 mm high. (2) After retracting punch, the springback angle of U-shape part increases as the blank decreases its width, e.g. for 20 mm blank width, the springback angle is up to about 10.3 degrees. (3) The warping phenomenon and springback angle can be effectively improved or reduced when bending with stripper. (4) It can improve springback angle if we use higher punch speed.
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Liao, Che-Wei, and 廖哲暐. "A Study on Drum Shape Error in WEDM and the Improvement Strategy." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/93932780319549081994.
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碩士國立臺灣大學
機械工程學研究所
98
WEDM is a machining process using thin wire electrodes. Because of the flexibility of the wire electrodes, there would be vertical alignment geometric error left on the machined surface. In most workshop practice, the error is corrected through multiple surface-finishing process, which is not efficient in time and cost.The previous studies over this issue proposed that the vertical alignment geometric error were out of two mechanisms – either vibration of the wire electrodes, or the ineffective of debris removal – both making the uneven distribution of the electoral discharge alone the wire electrodes. In this research, with SKD11 alloy of 60mm in thickness as the workpiece, the influences of the wire electrode tension, the servo voltage, and ignition delay time (Td) over the vertical alignment geometric error were observed, and also in conjunction with the ignition delay time of electrical discharged (Td) in order to figure out the suitable control index for feedback automatic control. It showed that, as the wire electrode tension increased, the influence of the wire vibration diminished, which suppressed the removal of the debris making the uneven distribution of electrical discharges. This research also noted that the vertical alignment geometric error could be categorized into two major types: nearly linear type, and irregular type. Different types of the error were attributed to two factors – the flow of debris removal, and the width of discharged gap – which reflected to different normal discharge ratios. Under the adequate normal discharge ratio, the vertical alignment geometric error would be much reduced. Based on the finding stated above, a clean-cut feedback control strategy was proposed in this research. Under the machining setting of servo feeding (G95), the normal discharge ratio was used as the control index to change the discharge off-time for the feedback control. Through on-site experiments, it was proved that, under the machining condition setting of this research, the vertical alignment geometric error could be much decreased with the normal discharge ratio of 40%. For workpiece of 60mm in thickness, the geometric error decreased from 6μm to nearly zero. For workpiece of 80mm in thickness, the geometric error decreased from 11μm to 2μm.
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Sun, Hongtao. "Efficiency Improvement of Evolutionary Multiobjective Optimization Methods for CFD-Based Shape Optimization." Phd thesis, 2010. https://tuprints.ulb.tu-darmstadt.de/2182/1/Dissertation_Hongtao_Sun_TUD_03.pdf.
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This dissertation presents an efficient optimization methodology to solve the CFD-based shape optimization problems. This methodology is based on evolutionary algorithms (EAs) for their well-known derivative-free property as well as the advantages in dealing with multiobjective optimization problems (MOOPs) and providing the global optimal solutions. Meanwhile, the approximation models and the deterministic optimization methods are combined with EA to improve the optimization efficiency and the local convergence. The optimization process consists of two parts: the design space exploration using EA (global search) and the convergence acceleration using deterministic methods (local search). When solving a shape optimization problem, the optimizer controls the whole optimization process. The shape variation and flow simulation are incorporated to perform the objective function evaluations and construct the database for the training of the approximation models. Free form deformation (FFD) is employed for the shape variation because it directly modifies the computational grids required by the flow solver and provides a flexible deformation by only moving a small number of the control points. The flow simulation is performed using the in-house developed finite-volume flow solver FASTEST. A modified, elitist evolutionary method NSGA-II is employed as the global explorer. During the evolutionary optimization process, in some generations the online and locally trained RBFN models are utilized to substitute the expensive function evaluations conducted by the high-fidelity flow solver. The adaptive exchange between the exactly and approximately evaluated generations is accomplished through an approximation control procedure. Afterwards, using the achieved results as the starting points, two derivative-free trust-region algorithms DFO and CONDOR are chosen to perform the local search. The proposed optimization methodology is first applied to several analytical and numerical optimization problems, and the optimization results show that it works well for both convex and non-convex Pareto front. The incorporation of approximation models overcomes the requirement of large number of computationally expensive function evaluations. Compared to conventional EA, this hybrid optimization method is able to achieve a set of optimal solutions with good diversity and better convergence with much less computational cost. Furthermore, the influence of RBFN construction methods and the number of solutions in the initial database on the approximation accuracy, as well as the performance of two local search methods, DFO and CONDOR, are studied in this work. Another contribution of the present work is to provide a methodology to construct the approximation model by combining the interpolation methods (spline interpolation or radial basis function interpolation) with the proper orthogonal decomposition (POD) technique in order to approximate the complete flow region in an efficient manner. Applied in the optimization process, this kind of surrogate model has the ability not only to predict the objective functions but also to provide a detailed estimation of the underlying flow region. The efficiency and accuracy of the POD-based approximation models as well as the quality of the optimization results are investigated by two shape optimization test cases.
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Lee, Jui-Chi, and 李瑞騏. "Improvement of NiTi Shape Memory Alloy Biocompatibility by Polymerized Hexamethyldisilazane Using Pulsed-DC PECVD." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/80679370049904734444.
Full textAbstract:
碩士大同大學
材料工程研究所
91
In recent years, shape memory and superelastic nickel-titanium alloys have been increasingly used in many fields for various applications. In orthopedic surgery, NiTi applications currently include NiTi compression bone stables used in osteotomy and fracture fixation, NiTi rods for the correction of scoliosis, shape memory expansion clamps used in cervical surgery, clamps in small bone surgery, and fixator systems for suturing tissue in minimal access surgery. However, the high nickel content of NiTi could cause biocompatibility problems, since nickel may have toxic effects at high concentrations. To improve the biocompatibility of the NiTi SMAs, there are many techniques of surface modifications. The plasma-enhanced chemical vapor deposition process is well-known technique to deposite thin layers with various coating parameters. Among the various coating processes, the PECVD process has many advantages for application to various metal molds over other processes such as PVD and CVD. The pulsed-DC PECVD process has been widely applied to metal molds of complicated geometry, such as aluminum die casting and aluminum extrusion dies, because of it’s good throwing power, i.e. the ability to coat irregularly shaped objects, even at low coating temperatures. The growth rate of plasma-polymerized hexamethyldisilazane (PHMDSZ) films deposited on NiTi SMA increases with increasing the monomer vapor pressure. The FTIR and surface free energy analyses denote that the structure of PHMDSZ films are strongly depend on the monomer vapor pressure i.e. the energy density. The SEM image of PHMDSZ film using DC PECVD method shows the disadvantage of excess plasma energy density in coating dense films. The surface of the PHMDSZ films deposited by pulsed-DC PECVD is getting smooth and the deposited particles size becomes smaller as the monomer vapor pressure decreases. The corrosion resistance of NiTi SMA can be raised by polymerized HMDSZ using pulsed-DC PECVD method. The corrosion current density can be substantially decreased by 3 to 4 orders compared with the NiTi SMA substrate and the total impedance also increases from about 300k up to more than 1G. Hence, the biocompatibility of NiTi SMA can be improved by such surface modification process. AAm successfully grafted onto PHMDSZ coated NiTi SMA was confirmed from the FTIR spectra analysis. In grafting process, the concentration of AAm solution is critical to the hydrophilicity of the film. The friction coefficient μ of PAAm was determined by friction test and the value is about 0.22. The low water contact angle and low friction coefficient μ indeed provide the convenience for surgical operations.
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Sun, Hongtao [Verfasser]. "Efficiency improvement of evolutionary multiobjective optimization methods for CFD-based shape optimization / von Hongtao Sun." 2010. http://d-nb.info/1003588093/34.
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shih, chih-wen, and 史智文. "Factors Resulting in Shape Defect of Steel Billets and Strategies for Improvement on Processing Control." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/18105743931257871210.
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碩士國立中興大學
機械工程學系所
100
Rhomboidity is also called off-square. If it is serious, the billet will have diagonal crack in the interior, or crack in the corner accompanying with concave surface. Also, it would cause inconvenience in pushing billet in heating furnace and result in difficulty on biting billet between rollers. Thus reducing rhomboidity of billet is an important subject for increasing production. In this work, firstly, the effect of composition of [C] 、 [S] and [Mn] in molten steel on rhomboidity was investigated the composition and improving steel-making process, the defect was removed. Then using the orthogonal test, it was found that the most important factor on rhomboidity is casting speed, The acquired data that analyzed based on statistics. Secondly, the influence induced by continuous casting machine was considered. In the first cooling zone, the temperatures of old and new copper tubes were measured. In doing so, uneven heat removing due to worn copper tubes can be investigated. After excluding the factors in the fist cooling zone, but still have rhomboidity problem, in the secondary cooling zone an inspection of wearing at the bottom of the copper tubes and the foot roller is required. This can determine whether there is a deformation or and improper calibration of the arc. The flowrate of spray nozzle of secondary cooling water and its pressure also need to be checked .Since they might cause uneven cooling and eventually result in rhomboidity of billet.
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Liu, Xiangyu active 21st century. "Zonal isolation improvement through enhanced cement-shale bonding." Thesis, 2014. http://hdl.handle.net/2152/28660.
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The incompatibility of cement and shale and the subsequent failure of primary cementing jobs is a very significant concern in the oil & gas industry. On wells ranging from hydraulically fractured shale land wells to deepwater wells, this incompatibility leads to an increased risk in failing to isolate zones, which could possibly present a well control hazard and can lead to sustained casing pressure. The cement-shale interface presents a weak link that often becomes compromised by the loads incurred either during drilling, completion/stimulation or production phases. To formulate cements for effective zonal isolation, it is crucial to evaluate the bond strength of the cement-shale interface. Although several studies have focused on the interactions between cement and sandstone, very few studies have addressed the bonding behavior of cement with shale. The conventional push-out test protocol used to measure cement-to-sandstone shear bond strength has proven to be difficult to apply on shale due to its laminated or brittle nature that complicates sample preparation and can lead to shale or cement matrix failure instead of failure at the interface. In this paper, we present a novel, simple and versatile laboratory test procedure to measure the shear bond strength between cement and shale. The new procedure was used to develop cement formulations to improve the cement-to-shale bond. Two different design approaches were investigated. One involves introducing Gilsonite into cement to maintain shale integrity. The second design involves using surfactant to improve cement interfacial sealing property. Our results indicate that bond strength of cement with shale can be enhanced significantly incorporating surfactant in cement slurries.text
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Santos, Cláudia Sofia Vieira. "Improvement of Lipton’s business model through wholesalers and traditional supermarkets channel." Master's thesis, 2014. http://hdl.handle.net/10362/14618.
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Field Lab in Entrepreneurial Innovative VenturesAs opposed to what is happening in other categories, tea category has been increasing over the years in the Portuguese market. So, the main goal of this project is to propose measures, so that Lipton improve its business model through wholesalers and traditional supermarkets, with the ultimate objective of increase its market share. In this sense, it will be presented an evaluation of the leaf tea market and its potential, as well as Lipton’s business model, followed by a risk analysis and recommendations, in terms of product, place, promotion, communication plan and processes for Lipton increase its market share, especially through wholesalers and traditional supermarkets.
NSBE - UNL
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Chinh, Tran Trung, and 陳忠正. "Improvement on Market Share of Activities in Vietnam LPG Co., Ltd (VT-Gas)." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/85699832620393054349.
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碩士美和科技大學
經營管理研究所
100
Energy resources become more and more important in the world in general and in Vietnam in particular. In Vietnam, petroleum industry has played an important role and contributed significantly to national income. Gas section is not only a new field but also a potential part of Vietnamese Petroleum industry. In order to manage and ensure partly the strategic national energy resources, Vietnam LPG Co., Ltd (VT-Gas), a Joint Venture among three famous petroleum groups: Vietnam Oil and Gas Group (PVN), Total Outre Mer (France) and PTT Public Company (Thailand) was established with a very important duty on contributing to develop of LPG production and distribute system under VT-Gas brand. In the first years, the company implemented import- export of Liquefied Petroleum Gas (LPG) from oversea to distribute to domestic market and then becomes one of the authorized distributors of Dinh Co Gas Processing Factory and Dung Quat Gas Processing Factory as well as soon as these factories started up their operation. Recently, the economy of global and Vietnam have dramatically changed with complicated happenings, the price of LPG products with unexpected change affected directly to the market share and sale operation of VT-Gas in particular and Vietnamese enterprises in general. Besides that, since Vietnam has become a member of the World Trade Organization (WTO) in 2007, it could be said that all Vietnamese enterprises have to operate in compliance with market mechanism with diversified ownerships. This resulted in all Vietnamese enterprises including VT-Gas in facing a lot of challenges and opportunities in the active environment of business. With the outcomes mentioned above, the aim of this study is to propose and build the appropriate strategies as well as to bring out the effective solutions in target to increase the market share activities of VT-Gas.
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Lin, Wen-Yen, and 林文彥. "Performance Improvement of MPEG over ATM Networks using Shaper and Feedback-Controlled Priority Partition Scheme." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/71356191338342337814.
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碩士國立中央大學
電機工程學系
85
MPEG over ATM has become an interesting topic in the literature , Many applications such as, Video on Daemon , Video Conference and Distance Learning had getting more and more popular in the future , However ,the traffic of MPEG video is bursty , it will cause conguestion of ATM networks ,So we propose a feedback-controlled priority partition scheme to scale priority-percentage dynamically and quality ,for reduce the burstiness of traffic , we use a RC traffice shaper to smooth MPEG video. In simulation results , we observed our scheme had good improvement of perofrmance.