Dissertations / Theses on the topic 'Performance-Influence Modeling'

This research investigated the relationship between several firm-controlled, marketing and management factors and firm performance. Hypotheses describing the relationship between the strategic, geographic, tactical, technological and organizational factors and firm performance of hardwood lumber manufacturers were tested. These factors were operationalized, measured in a mail survey and used in statistical analysis to identify relationships among the variables. An adjusted response rate of 19.8% was obtained from the mail survey. Non-response bias was not found to be a significant problem in the data. A twelve measure performance indicator was developed and utilized to evaluate the performance of hardwood lumber manufacturers who were predominantly privately-held companies. The averages for the profit and costs performance measures were the lowest of all twelve performance measures and this suggested that firms should focus improvement on these measures. The current marketing tactics, including species mix, product mix, customer mix, and promotion mix was determined. The utilization of advanced production technology has increased in the industry since it was last measured in 1999. The majority of respondents (60%) had dry kiln operations and 49% had a surfacing mill. Thirty five percent of respondents indicated that their company was certified by either forest, chain-of-custody, or both. Of the five firm-controlled factors investigated in this research, four of them were found to be related to firm performance. Geographic location was not found to be related to the performance of hardwood sawmills. Firms who were backward integrated and firms who were both backward integrated and forward integrated performed significantly better than firms who were not vertically integrated or forward integrated. Higher performance scores were associated with larger firms, firms who had multiple sawmills and firms who were members of the NHLA. There was no relationship found between diversification of the product mix, species mix, customer mix variables and performance. The diversification of a firm's promotion expenditures was positively correlated to performance. Firms that used optimized headrigs, optimized edgers and optimized trimmers performed significantly better than did firms not using all three of these technologies. Firms that used computer based log tallying, lumber tallying or inventory control performed significantly better than firms utilizing none of these technologies. An increase in the use of business strategy from previous studies along with a shift towards the use of a differentiation strategy was discovered. Firms interpreted to be following a hybrid differentiation/cost leadership strategy performed better than firms following a cost leadership, focus, or differentiation strategy. The implication of these results is that larger, vertically integrated firms are likely to perform better than smaller, non-integrated hardwood lumber manufacturers. It is recommended that firms diversify their use of promotion media and venues in order to attract new customers. Adoption of production and information technology will help some hardwood lumber manufacturers improve their performance. It is recommended that hardwood lumber manufacturers control costs and differentiate their products in order to gain competitive advantage.
Ph. D.

Wave engines are a class of unsteady, air-breathing propulsion devices that use an intermittent combustion process to generate thrust. The inherently simple mechanical design of the wave engine allows for a relatively low cost per unit propulsion system, yet unsatisfactory overall performance has severely limited the development of commercially successful wave engines. The primary objective of this investigation was to develop a more detailed physical understanding of the influence of gas dynamic nonlinearities, unsteady combustion processes, and engine shape on overall wave engine performance. Within this study, several numerical models were developed and applied to wave engines and related applications. The first portion of this investigation examined the influence of duct shape on driven oscillations in acoustic compression devices, which represent a simplified physical system closely related in several ways to the wave engine. A numerical model based on an application of the Galerkin method was developed to simulate large amplitude, one-dimensional acoustic waves driven in closed ducts. Results from this portion of the investigation showed that gas-dynamic nonlinearities significantly influence the properties of driven oscillations by transferring acoustic energy from the fundamental driven mode into higher harmonic modes. The second portion of this investigation presented and analyzed results from a numerical model of wave engine dynamics based on the quasi one-dimensional conservation equations in addition to separate sub-models for mixing and heat release. This model was then used to perform parametric studies of the characteristics of mixing and engine shape. The objectives of these studies were to determine the influence of mixing characteristics and engine shape on overall wave engine performance and to develop insight into the physical processes controlling overall performance trends. Results from this model showed that wave engine performance was strongly dependent on the coupling between the unsteady heat release that drives oscillations in the engine and the characteristics that determine the acoustic properties of the engine such as engine shape and mean property gradients. Simulation results showed that average thrust generation decreased dramatically when the natural acoustic mode frequencies of the engine and the frequency content of the unsteady heat release were not aligned.

This project attempts to research the manufacturing cost, with an emphasis on machining, of high performance flanges for Turbine Rear Structure (TRS) applications, as well as the tradeoffs with structural performance and weight. A combination of traditional cost modelling techniques from the literature, as well as, the non-conventional manufacturing complexity index, as cost indicator are implemented. A multidisciplinary study is carried out with the aid of ANSYS Workbench in the form of computer simulated experiments to investigate tradeoffs in flanges. It is concluded that multidisciplinary studies of cost, performance and weight lacked model robustness to draw sound conclusions about flange design. However, the manufacturing complexity index after partial validation with experienced engineers shows promising results, and could be a way forward to estimate final machining operation cost for flanges in the future.
Syftet för detta projekt är att undersöka tillverkningskostnaden, med tonvikt på bearbetning av högpresterande flänsar för turbinapplikationer (TRS), samt dess relation till strukturella prestanda och vikt. Traditionella kostnadsmodelleringstekniker kombineras med det ickekonventionella tillverkningskomplexitetsindexet och används som kostnadsindikator. En tvärvetenskaplig studie genomförs med hjälp av ANSYS Workbench i form av dator simulerade experiment för att undersöka flänsavvägningar. En slutsats av studien är att multidisciplinära modeller av kostnad, prestanda och vikt saknade robusthet för att kunna dra djupgående slutsatser om prestandan för en flänsdesign. Tillverkningskomplexitetsindexet visar dock, efter partiell validering med erfarna ingenjörer, lovande resultat och kan vara framgångsrikt ett sätt att uppskatta den slutliga bearbetningskostnaden för flänsar.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Air-cooled steam condensers (ACSCs) are used in the power generation industry to directly condense turbine exhaust steam in areas where cooling water is expensive or unavailable. Large axial flow fans force ambient air through A-frame heat exchanger bundles made up of a number of rows of finned tubes through which the steam is ducted and consequently condensed during the heat transfer process to the air. The heat rejection rate or performance of an ACSC is proportional to the air mass flow rate, determined by fan volumetric performance, and the temperature difference between the finned tubes and the air. The air flow through a 30 fan ACSC (termed the generic ACSC) operating under windy conditions is solved using the commercial computational fluid dynamics (CFD) code FLUENT and the required data is extracted from the solution to calculate performance trends. It is found that fan performance is reduced due to a combination of factors. The first is additional upstream flow losses caused by separated flow occurring primarily at the leading edge of the ACSC and secondarily at the fan bellmouth inlets. The second factor leading to reduced fan performance is the presence of distorted flow conditions at the fan inlets. Hot plume air recirculation is responsible for decreased ACSC thermal performance due to increased fan inlet air temperatures. It is found that reduced fan performance is the greater contributor to reduced ACSC performance. The performance effects of varying two geometrical parameters of the generic ACSC, namely the fan platform height and the windwall height, are investigated under windy conditions. It is found that each parameter is linked to a specific mechanism of performance reduction with the fan platform height affecting fan performance and the windwall height affecting recirculation. The respective platform and windwall heights specified for the generic ACSC are found to provide acceptable performance results. To mitigate wind induced performance reductions a number of modification and additions to the ACSC are investigated. These primarily aim at improving fan performance and included the addition of walkways or skirts, the addition of wind screens beneath the fan platform, removing the bellmouth fan inlets, using different types of fans and increasing fan power. The addition of a periphery walkway and windscreens is considered to be the most practical methods of improving ACSC performance under windy conditions. The generic ACSC is modified to include both modifications and under high wind conditions the performance is found to increase measurably. The modifications also resulted in the ACSC performance being less sensitive to wind direction effects.
AFRIKAANSE OPSOMMING: Lugverkoelde kondensators word in die kragopwekkings industrie gebruik om turbine uitlaatstoom te kondenseer, veral in gebiede waar verkoelingwater duur of onbeskikbaar is. Aksiaalvloei-waaiers forseer omgewingslug deur A-raam warmteuitruiler bondels wat bestaan uit verskeie rye vinbuise. Die uitlaatstoom vloei in die vinbuise en kondenseer as gevolg van die warmteoordrag na die lug. Die warmteoordragkapasiteit van die lugverkoelde stoom kondensator is eweredig aan die massavloei-tempo van die lug, wat bepaal word deur die waaierwerkverigting, en die temperatuur verskil tussen die vinbuise en die lug. Die lugvloei deur 'n 30 waaier lugverkoelde stoom kondensator (genoem die generiese lugverkoelde stoom kondensator) onderworpe aan winderige toestande word opgelos deur die gebruik van die kommersiële vloeidinamika-pakket, FLUENT. Die nodige data is onttrek uit die oplossing en werkverrigting neigings is bereken. Dit is gevind dat waaierwerkverigting verminder as gevolg van 'n kombinasie van faktore. Die eerste is bykomende vloeiverliese wat veroorsaak word deur vloeiwegbreking wat plaasvind primêr by die voorste rand van die lugverkoelde stoom kondensator asook by die klokvormige waaier-inlate. 'n Tweede faktor wat lei tot vermindere waaierwerkverigting is die teenwoordigheid van lugvloeiversteurings by die waaier-inlate. Hersirkulering van warm pluim lug is ook verantwoordelik vir verminderde lugverkoelde stoom kondensator werkverrigting. Daar word bevind dat die vermindering in waaierwerkverrigting die grootste bydraende faktor tot vermindere lugverkoelde stoom kondensator werkverrigting is. Die effek van verandering van twee geometriese lugverkoelde stoom kondensator parameters, naamlik die waaierplatformhoogte en die windwandhoogte is ondersoek onder winderige toestande. Daar word bevind dat elk van die parameters gekoppel is aan 'n spesifieke meganisme van vermindere lugverkoelde stoom kondensator verrigting: Die waaierplatformhoogte beïnvloed waaierverrigting terwyl die windwandhoogte hersirkulering beinvloed. Daar word ook bevind dat die onderskeie waaierplatform- and windwandhoogtes van die generiese lugverkoelde stoom kondensator, van so 'n aard is dat dit aanvaarbare werkverrigting tot gevolg het. Om verlaging in werksverrigting in winderige toestande te verminder is verskeie modifikasies en byvoegings tot die lugverkoelde stoom kondensator ondersoek wat primêr gemik is op verbetering in waaierwerkverigting. Die ondersoek dek die byvoeging van 'n loopvlak, die byvoeging van windskerms onder die waaierplatform, verwydering van die klokvormige waaier-inlate, die gebruik van verskillende waaiers en die verhoging van waaierdrywing. Daar was besluit dat die byvoeging van 'n loopvlak rondom die rand van die lugverkoelde stoom kondensator en die byvoeging van windskerms die mees praktiese manier was om die lugverkoelde stoom kondensator verigting te verbeter. Die generiese lugverkoelde stoom kondensator was aangepas om beide veranderings in te sluit en meetbare verbetering in werkrigting was verkry. Die veranderings het ook meegebring dat die lugverkoelde stoom kondensator minder sensitief is vir windrigting effekte.

Cette thèse s'intéresse aux Services d'Accompagnement à l'Export proposés par les acteurs de l'accompagnement. Les pouvoirs publics s'interrogent sur l'efficacité de ces aides. La littérature fait état de résultats contradictoires sur cette question, notamment à cause de l'absence d'une mesure valide de l'accompagnement à l'export qui rend difficile la comparaison des résultats. Cette difficulté est exacerbée par la diversité des entreprises accompagnées. En effet, les aides ont été pensées pour les entreprises à internationalisation par étapes. Pourtant, il apparaît que les Exportatrices Précoces, type d'entreprise à internationalisation précoce le plus répandu mais aussi le plus fragile, utilisent les mêmes aides. Dès lors, deux questions se posent ; d'une part, la manière de mesurer l'accompagnement à l'export reçu par l'entreprise et, d'autre part, la question de l'efficacité des Services d'Accompagnement à l'Export pour les Exportatrices Précoces. Pour répondre à la première question, une démarche de construction d'une échelle de mesure de l'accompagnement à l'export est mise en œuvre en s'appuyant sur le paradigme de Churchill (1979). Une étude exploratoire est menée auprès de treize acteurs de l'accompagnement à l'export et cinq entreprises accompagnées afin de faire émerger des items de mesure. Ensuite, 288 questionnaires d'entreprises accompagnées à l'export sont récoltés et utilisés pour tester les qualités psychométriques de l'échelle. Cette démarche aboutit à une échelle de mesure multidimensionnelle composée de neuf items et distinguant accompagnement informationnel, opérationnel et financier. Cet outil permet de mesurer plus précisément les Services d'Accompagnement à l'Export utilisés par l'entreprise. Pour répondre à la seconde question, la théorie des ressources est mobilisée afin d'identifier les ressources stratégiques des Exportatrices Précoces et l'influence que les différents types d'accompagnement à l'export peuvent avoir sur elles. Ces relations aboutissent à un modèle conceptuel testé par la méthode des équations structurelles à partir de 196 questionnaires d'entreprises accompagnées à l'export. Il en ressort que les Services d'Accompagnement à l'Export sont moins efficaces pour les Exportatrices Précoces, notamment en ce qui concerne l'accompagnement financier qui n'a aucune influence sur leur performance internationale. Les résultats soulignent ainsi la nécessité d'élaborer de nouveaux services pour accompagner efficacement les Exportatrices Précoces. Plusieurs propositions sont faites en ce sens
This thesis focuses on Export Support Services offered by the public and semi-public actors. Public authorities are questioning the effectiveness of these services. The literature reports conflicting results on this issue, especially because of the lack of a valid measure of export support which makes it difficult to compare results. This difficulty is exacerbated by the diversity of firms supported. Indeed, the services was thought to firm with internationalization by stages. Yet it appears that Early Exporters, the most common but also the most fragile type of International New Ventures, use the same services. Therefore, two questions arise; first, how to measure the export support received by the firm and, secondly, the question of the effectiveness of the Export Support Services for Early Exporters. To answer the first question, a process of construction of a scale measurement of Export Support based on the Churchill paradigm (1979) is implemented. An exploratory study was conducted with thirteen support export actors and five companies to make measurement items. Then 288 questionnaires of supported firms are harvested and used to test the psychometric properties of the scale. This approach results in a multidimensional measurement scale with nine items and distinguishing informational, operational and financial Export Support. This tool can measure more accurately Export Support Services used by the firm. To answer the second question, the theory of resources is mobilized to identify the strategic resources of Early Exporters and influence that different types of Export Support can have on them. These relationships lead to a conceptual model tested by the method of structural equation from 196 questionnaires of supported companies. It shows that the Export Support Services are less effective for Early Exporters, especially with regard to the financial support that has no influence on their international performance. The results thus highlight the need to develop new services to effectively support Early Exporters. Several proposals are made in this direction

This thesis examined the validity of allometric models (Y = aXbg) in scaling physiological and human performance data (Y) for differences in body size (X). 1) Anaerobic performance. External peak power output (PPO) derived from supramaximalleg ergometry was compared in young adult males and females, using a multivariate allometric model. Estimated fat free mass (FFM) and thigh muscle-and-bone cross-sectional area served as indicators of involved musculature. Male PPO was greater than female (P < 0.05), after allometric adjustment for body size differences. This finding is questionable, however, as the within-gender goodness-of-fit values for the regression models were very poor. 2) Cardiac dimensions. The proper relationships between echocardiographic dimensions [left ventricular (LV) mass, and LV internal dimensions] and various indicators of overall body size [height, body mass (BM), FFM, and body surface area (BSA)] were examined in young, apparently healthy, adult males and females. Scaling by FFM was associated with the least residual error in these samples. The obtained relationships were generally dimensionally consistent, that is, LV mass proportional to FFM to the first power, and LV internal dimensions related to the 1/3 power ofFFM. 3) Methodological issues. The multivariate allometric scaling of peak oxygen uptake by height and BM was investigated. Regression diagnostics revealed that the obtained exponents were unstable, and potentially numerically inaccurate, due to severe collinearity between height and BM in the sample. For elite weightlifting performance, detailed examination of the allometric regression residuals revealed that the model was poorly specified. Re-specification of the model using secondorder polynomials provided the optimal scaling of this data set.

The productivity of most gas condensate wells is reduced significantly due to condensate banking when the bottom hole pressure falls below the dew point. The liquid drop-out in these very high rate gas wells may lead to low recovery problems. The most important parameter for determining condensate well productivity is the effective gas permeability in the near wellbore region, where very high velocities can occur. An understanding of the characteristics of the high-velocity gas-condensate flow and relative permeability data is necessary for accurate forecast of well productivity. In order to tackle this goal, a series of two-phase drainage relative permeability measurements on a moderate permeability North Marmara &ndash
1 gas well carbonate core plug sample, using a simple synthetic binary retrograde condensate fluid sample were conducted under reservoir conditions which corresponded to near miscible conditions. As a fluid system, the model of methanol/n-hexane system was used as a binary model that exhibits a critical point at ambient conditions. The interfacial tension by means of temperature and the flow rate were varied in the laboratory measurements. The laboratory experiments were repeated for the same conditions of interfacial tension and flow rate at immobile water saturation to observe the influence of brine saturation in gas condensate systems. The laboratory experiment results show a clear trend from the immiscible relative permeability to miscible relative permeability lines with decreasing interfacial tension and increasing velocity. So that, if the interfacial tension is high and the flow velocity is low, the relative permeability functions clearly curved, whereas the relative permeability curves straighten as a linear at lower values of the interfacial tension and higher values of the flow velocity. The presence of the immobile brine saturation in the porous medium shows the same shape of behavior for relative permeability curves with a small difference that is the initial wetting phase saturations in the relative permeability curve shifts to the left in the presence of immobile water saturation. A simple new mathematical model is developed to compute the gas and condensate relative permeabilities as a function of the three-parameter. It is called as condensate number
NK so that the new model is more sensitivity to temperature that represents implicitly the effect of interfacial tension. The new model generated the results were in good agreement with the literature data and the laboratory test results. Additionally, the end point relative permeability data and residual saturations satisfactorily correlate with literature data. The proposed model has fairly good fitness results for the condensate relative permeability curves compared to that of gas case. This model, with typical parameters for gas condensates, can be used to describe the relative permeability behavior and to run a compositional simulation study of a single well to better understand the productivity of the field.

Organizations depend upon ever greater levels of information technology (IT), such as big data and analytics, a trend which shows no sign of abating. However, not all organizations have benefited from such IT investments, resulting in mixed perceptions on the value of IT. Organizations must be knowledgeable in order to properly utilize IT tools and be able to apply that knowledge to create unique competencies in order to gain sustained advantage from IT investments. Organizational learning (OL) has been proposed as the mechanism to accomplish this task. Existing empirical research demonstrates that OL may indeed act as a mediator for the effect of IT on organizational outcomes. Yet, these studies are not consistent in their conceptualizations of the relationships involved, nor in their definitions and measurement of OL. Many use a descriptive measure of OL despite theory suggesting that a normative measure may be more appropriate. This study aims to address these concerns in a Canadian setting by using structural equation modelling (SEM) to compare the effectiveness of descriptive and normative measures of OL as mediating variables in knowledge-intensive organizations. Survey results support OL as a mediator between IT and organizational performance in addition to normative measures of OL outperforming descriptive measures. Implications for research and practice are discussed.

[EN] The injection system is one of the topics that has been paid most attention to by researchers in the field of direct injection diesel engines, due to its key role on fuel atomization, vaporization and air-fuel mixing process, which directly affect fuel consumption, noise irradiation and pollutant emissions. The increasing injection pressures in modern engines have propitiated the need of studying phenomena such as cavitation, compressible flow or the effect of changes in the fuel properties along the process, whose relative importance was lower in early stages of the reciprocating engines development. The small dimensions of the injector ducts, the high velocities achieved through them and the transient nature of the process hinder the direct observation of these facts. Computational tools have then provided invaluable help in the field. The objective of the present thesis is to analyse the influence of the thermal effects on the performance of a diesel injector. To this end, the fuel temperature variation through the injector restrictions must be estimated. The influence of these changes on the fuel thermophyisical properties relevant for the injection system also needs to be assessed, due to its impact on injector dynamics and the injection rate shape. In order to give answer to the previous objectives, both experimental and computational techniques have been employed. A dimensional and a hydraulic experimental characterization of a solenoid-actuated Bosch CRI 2.20 injector has been carried out, including rate of injection measurements at a wide range of operating conditions, with special attention to the fuel temperature control. A 1D computational model of the injector has been implemented in order to confirm and further extend the findings from the experiments. Local variations of fuel temperature and pressure are considered by the model thanks to the assumption of adiabatic flow, for which the experimental characterization of the fuel properties at high pressure also had to be performed. The limits of the validity of this assumption have been carefully assessed in the study. Results show a significant influence of the fuel temperature at the injector inlet on injection rate and duration, attributed to the effect of the variation of the fuel properties and to the fact that the injector remains in ballistic operation for most of its real operating conditions. Fuel temperature changes along the injector control orifices are able to importantly modify its dynamic behaviour. In addition, if the fuel at the injector inlet is at room temperature or above, the temperature at the nozzle outlet has not been proved to importantly change once steady-state conditions are achieved. However, a significant heating may take place for fuel temperatures at the injector inlet typical of cold-start conditions.
[ES] El sistema de inyección es uno de los elementos que más interés ha despertado en la investigación en el campo de los motores diésel de inyección directa, debido a su papel clave en la atomización y vaporización del combustible así como en el proceso de mezcla, que afectan directamente al consumo y la generación de ruido y emisiones contaminantes. Las crecientes presiones de inyección en motores modernos han propiciado la necesidad de estudiar fenómenos como la cavitación, flujo compresible o el efecto de los cambios de las propiedades del combustible a lo largo del proceso, cuya importancia relativa era menor en etapas tempranas del desarrollo de los motores alternativos. Las pequeñas dimensiones de los conductos del inyector, las altas velocidades a través de los mismos y la naturaleza transitoria del proceso dificultan la observación directa en estas cuestiones. Por ello, las herramientas computacionales han proporcionado una ayuda inestimable en el campo. El objetivo de la presente tesis es analizar la influencia de los efectos térmicos en el funcionamiento de un inyector diésel. Para tal fin, se debe estimar la variación de la temperatura del combustible a lo largo de las restricciones internas del inyector. La influencia de estos cambios en las propiedades termofísicas del combustible más relevantes en el sistema de inyección también debe ser evaluada, debido a su impacto en la dinámica del inyector y en la forma de la tasa de inyección. Para dar respuesta a estos objetivos, se han utilizado técnicas experimentales y computacionales. Se ha llevado a cabo una caracterización dimensional e hidráulica de un inyector Bosch CRI 2.20 actuado mediante solenoide, incluyendo medidas de tasa de inyección en un amplio rango de condiciones de operación, para lo que se ha prestado especial atención al control de la temperatura del combustible. Se ha implementado un modelo 1D del inyector para confirmar y extender las observaciones extra\'idas de los experimentos. El modelo considera variaciones locales de presión y temperatura del combustible gracias a la hipótesis de flujo adiabático, para lo cual también se ha tenido que llevar a cabo una caracterización experimental de las propiedades del combustible a alta presión. Los límites de la validez de esta hipótesis se han analizado cuidadosamente en el estudio. Los resultados muestran una influencia significativa de la temperatura del combustible a la entrada del inyector en la tasa y duración de inyección, atribuida al efecto de la variación de las propiedades del combustible y al hecho de que el inyector permanece en operación balística para la mayoría de sus condiciones de funcionamiento. Los cambios en temperatura del combustible a lo largo de los orificios de control del inyector son capaces de modificar su dinámica considerablemente. Además, si el combustible a la entrada del inyector se encuentra a temperatura ambiente o por encima, se ha observado que la temperatura a la salida de la tobera no varía de manera importante una vez se alcanzan condiciones estacionarias. No obstante, un calentamiento significativo puede tener lugar para temperaturas de entrada típicas de las condiciones de arranque en frío.
[CAT] El sistema d'injecció és un dels elements que més interés ha despertat en la investigació en el camp dels motors dièsel d'injecció directa, degut al seu paper clau en l'atomització i vaporització del combustible, així com en el procés de mescla, que afecten directament el consum i la generació de soroll i emissions contaminants. Les creixents pressions d'injecció en motors moderns han propiciat la necessitat d'estudiar fenòmens com la cavitació, flux compressible o l'efecte dels canvis de les propietats del combustible al llarg del procés, la importància relativa dels quals era menor en les primeres etapes del desenvolupament dels motors alternatius. Les menudes dimensions dels conductes de l'injector, les altes velocitats a través dels mateixos i la natura transitòria del procés dificulten l'observació directa en estes qüestions. Per això, les ferramentes computacionals han proporcionat una ajuda inestimable en el camp. L'objectiu de la present tesi és analitzar la influència dels efectes tèrmics en el funcionament d'un injector dièsel. Per a tal fi, es deu estimar la variació de la temperatura del combustible al llarg de les restriccions internes de l'injector. La influència d'estos canvis en les propietats termofísiques del combustible més relevants en el sistema d'injecció també ha de ser avaluada, degut al seu impacte en la dinàmica de l'injector i en la forma de la tasa d'injecció. Per tal de donar resposta a estos objectius, s'han utilitzat tècniques experimentals i computacionals. S'ha dut a terme una caracterització dimensional i hidràulica d'un injector Bosch CRI 2.20 actuat mitjançant solenoide, incloent mesures de tasa d'injecció en un ampli rang de condicions d'operació, per al que s'ha prestat especial atenció al control de la temperatura del combustible. S'ha implementat un model 1D de l'injector per tal de confirmar i estendre les observacions extretes dels experiments. El model considera variacions locals de pressió i temperatura del combustible gràcies a la hipòtesi de flux adiabàtic, per la qual cosa també s'ha hagut de dur a terme una caracterització experimental de les propietats del combustible a alta pressió. Els límits de la validesa d'esta hipòtesi s'han analitzat acuradament en l'estudi. Els resultats mostren una influència significativa de la temperatura del combustible a l'entrada de l'injector en la tasa i duració d'injecció, atribuïda a l'efecte de la variació de les propietats del combustible i al fet que l'injector roman en operació balística per a la majoria de les seues condicions de funcionament. Els canvis en temperatura del combustible al llarg dels orificis de control de l'injector són capaços de modificar la seua dinàmica considerablement. A més, si el combustible a l'entrada de l'injector es troba a temperatura ambient o per damunt, s'ha observat que la temperatura a l'eixida de la tobera no varia de manera important una vegada s'han assolit condicions estacionàries. No obstant això, un escalfament significatiu pot tenir lloc per a temperatures d'entrada típiques de les condicions d'arrancada en fred.
Carreres Talens, M. (2016). Thermal effects influence on the Diesel injector performance through a combined 1D modelling and experimental approach [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/73066
TESIS

Information systems are used to increase business performance to gain competitive advantage. Information systems affect both financial measures and internal processes, thus providing different benefits to organisation. The main objective of the thesis is to create a model for evaluation of business performance through implementation of information systems. The thesis consists of three parts. In the theoretical part definition on what are information systems, enterprise resource planning systems and how do they correspond to each other were given. Explanation on how information systems can increase business performance and what business processes and indicators might be affected were analyzed. Integrated information system that refers to enterprise resource planning systems group is presented in the more detailed way. In the second part description was provided on how model was created for evaluation of influence of information systems on business performance. Information how the hierarchical organizational structure and selected performance indicators might be used for evaluation the general business performance index. In the practical model approbation part the results on the evaluation of information Systems, implemented in different branch offices in different countries of company providing engineering consultancy services , was made. Research results analysis has revealed that information systems have a great effect on business performance and can enhance performance... [to full text]
Informacinės sistemos naudojamos siekiant pagerinti įmonės veiklos rodiklius ir įgyti konkurencinį pranašumą. Informacinės sistemos turi poveikį tiek finansiniams, tiek ir vidaus procesų rodikliams, taip suteikdamos naudą įmonei. Baigiamojo darbo pagrindinis tikslas yra sukurti informacinių sistemų poveikio įmonių veiklai vertinimo modelį. Baigiamąjį magistro darbą sudaro trys dalys. Teorinėje studijoje pateikiami informacinės sistemos, įmonių vidinių išteklių planavimo sistemų apibrėžimai ir aiškinama sąsaja tarp šių dviejų reikšmių. Analizuojama, kaip diegiamos informacinės sistemos didina verslo efektyvumą, gerina rodiklius, paveikia verslo procesus. Antroje dalyje nagrinėjamas informacinių sistemų poveikio įmonių veiklai vertinimo modelis. Išanalizuota, kaip esama hierarchinė organizacijos struktūra ir pasirinkti veiklos rodikliai gali būti panaudoti bendro verslo veiklos rodikliui paskaičiuoti. Praktinėje dalyje buvo atliktas modelio aprobavimas inžinierines konsultacines paslaugas teikiančioje įmonės filialuose, įsteigtuose skirtingose šalyse. Tyrimo rezultatai parodė, kad informacinės sistemos turi didelį poveikį verslo rodikliams ir gali padidinti įmonės efektyvumą. Baigiamojo darbo pabaigoje pateiktos išvados ir pasiūlymai. Baigiamojo darbo apimtis – 79 p. teksto be priedų, 24 pav., 22 lent., 82 bibliografiniai šaltiniai.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.
Title as it appears in M.I.T. Graduate List, Feb. 1988: A modelling study of the influence of spark-ignition engine design parameters on engine thermal efficiency and performance.
Bibliography: leaves 63-65.
by Robert Todd Chang.
M.S.

La réduction du poids des avions est l'un des grands défis de l'industrie aérospatiale. Afin d'atteindre les objectifs ambitieux en matière de consommation de carburant et de réduction des émissions, des composites renforcés de fibres de carbone, ont été introduits sur le marché. Ces matériaux suscitent un intérêt croissant, néanmoins, ils possèdent une faible conductivité électrique, ne permettant pas de garantir une protection contre la foudre. Pour cette raison, les composites chargés de particules conductrices font l'objet d'activités de recherche en cours. L'objectif est le développement de composites multifonctionnels avec des propriétés électriques accrues. Pour l'heure, la matrice thermoplastique de référence est le PEEK mais ce polymère reste toutefois cher, et sa température d'élaboration élevée. Dans ce but, des matrices thermoplastiques, telles que le PEKK, sont à nouveau étudiées. Entre la matière première et la pièce finale, la matrice thermoplastique subit plusieurs cycles de traitement à haute température (imprégnation, consolidation, procédés d'assemblage) au cours desquelles sa capacité à cristalliser évolue sans cesse. Afin d'évaluer l'impact du procédé et des constituants du composite sur les propriétés du composite, la cristallisation a fait l'objet d'une attention particulière. Deux dispositifs expérimentaux complémentaires ont été utilisés afin de caractériser la cristallisation : une platine chauffante, permettant d'appliquer un cycle thermique et d'observer la cristallisation en microscopie optique ainsi que la calorimétrie différentielle à balayage. L'influence des fibres de carbone et des particules conductrices sur la cinétique de cristallisation a été évaluée. Une diminution des temps de cristallisation a été observée à travers l'augmentation du taux de germination. Les données recueillies ont servi à développer un modèle de cinétique de cristallisation identifié à travers une approche originale en se basant sur des données microscopiques et enthalpiques. Ce modèle permet de prédire les cinétiques de cristallisation des composites à matrice PEKK mais il ne permet pas de rendre compte de la microstructure finale engendrée. Or, cette dernière a un impact non négligeable sur les propriétés mécaniques comme cela a été prouvé à travers des essais de nano-indentation. Pour prévoir la microstructure finale, un modèle basé sur l'approche pixel coloring a été développé. L'influence des fibres de carbone a été introduite à travers la formation d'une phase transcristalline. Une bonne corrélation est constatée entre l'approche analytique, la simulation et les données expérimentales en termes de cinétique de cristallisation. Des caractérisations mécaniques et électriques ont été effectuées afin d'évaluer les performances de ces nouveaux matériaux. Sur les matériaux étudiés, la réponse mécanique n'est pas homogène comme observé sur des essais de traction suivis en stéréo-corrélation. L'étude de la santé matière montre l'existence de défauts, en particulier, à l'échelle de la microstructure. Afin de prendre en compte ces particularités, il est ainsi nécessaire de décrire plus finement la microstructure. Pour cela, la tomographie à rayons X a été utilisée afin de caractériser le composite. Les récents développements de cette technique permettent, en combinaison avec des outils de segmentation, de reconstruire une géométrie représentative du matériau. Cette géométrie est utilisée pour simuler le comportement mécanique ainsi que la cristallisation. Les simulations numériques d'un VER sont capables de prédire les propriétés d'un pli, puis celles du stratifié. Cette modélisation multi-échelle pourrait réduire le nombre et le coût des campagnes expérimentales. Ainsi, déterminer les propriétés de la structure finale en se basant sur des caractérisations et simulations à l'échelle de la microstructure est un enjeu scientifique et industriel stratégique. Ce travail constitue une contribution vers cette approche
Reducing aircraft weight is one of the major challenges facing the aerospace industry. In order to achieve the ambitious goals of fuel consumption and emission reduction, carbon-fiber reinforced composites have been introduced to the market. These materials are attracting increasing interest, however, they have low electrical conductivity to ensure protection against lightning strike. For this reason, composites filled with conductive particles are the subject of ongoing research activities. The objective is the development of multifunctional composites with enhanced electrical properties. Actually, the most used thermoplastic matrix is PEEK, but this polymer remains expensive, and its processing temperature is high. For this purpose, thermoplastic matrices, such as PEKK, are again studied. Between the raw material and the final part, the thermoplastic matrix undergoes several thermal steps with high temperature exposure (impregnation, consolidation, forming and assembly processes) during which its ability to crystallize evolves continuously. In order to evaluate the impact of the process and the composite constituents on its properties, crystallization has been the subject of particular attention. Two complementary experimental devices were used to characterize the crystallization. The heating stage, allows to apply a thermal cycle and observe the crystallization in optical microscopy and differential scanning calorimetry. The influence of carbon fibers and conductive fillers on the crystallization kinetics was evaluated. A decrease in crystallization times was observed through the increase of the nucleation rate. The collected data were used to develop a kinetic model identified through an original approach based on microscopic data. This model makes it possible to predict the crystallization kinetics of PEKK composites. Nevertheless, it does not make it possible to predict the final microstructure. However, the microstructure has a significant impact on mechanical properties as it has been proven through nano-indentation tests. To predict the final microstructure, a model based on the pixel coloring approach has been developed. The influence of carbon fibers has been introduced through the formation of a transcrystalline phase. A good correlation is found between the analytical approach, the simulation and the experimental data in terms of crystallization kinetics. Mechanical and electrical characterizations were performed to evaluate the performance of these new materials. On the studied materials, the mechanical response is not homogeneous as observed on tensile tests followed in stereo-correlation. The study of matter health shows the existence of defects, in particular, at the microstructure level. In order to take this particularity into account, it is thus necessary to describe the microstructure more finely. For this, X-ray tomography was used to characterize the composite. Recent developments in this technique allow, in combination with segmentation tools, to reconstruct a representative geometry of the material. This geometry is used to simulate the mechanical behaviour as well as the crystallization. The numerical simulations of an RVE are able to calculate the properties of a ply, then those of a laminate. This multi-scale modelling could reduce the number and cost of experimental campaigns. Thus, determining the properties of the final structure based on characterizations and simulation at the microstructure scale is a strategic scientific and industrial issue. This work is a contribution towards this approach

La problématique de la performance des marins en navigation extrême, n’a été que très peu étudiée avec des méthodes scientifiques rigoureuses de façon systématique et sous un angle de vue global en conditions écologiques. Nos travaux se sont attachés à évaluer le comportement humain en conditions écologiques avec une approche environnementaliste et transactionnelle. L’objectif principal de cette thèse a été de comprendre quel est l’impact des facteurs environnementaux tels que la force du vent et la quantité de sommeil ainsi que d’une stimulation cognitive à l’aide d’un vidéo self-modeling sur la perception de l’anxiété, de la fatigue et la tolérance à l’effort à vitesse maximale aérobie. Les résultats de la première étude, en condition écologique, où l’influence du vent et de la privation du sommeil ont été modélisées grâce à l’outil des fonctions transferts, a permis de comprendre que le marin opère une régulation liée temporellement à son engagement et aux efforts ou privations comme par exemple celle du sommeil. Cette régulation est liée à la perception de l’anxiété et l’intensité de l’effort perçu et est influencée par les facteurs environnementaux comme le vent ou la privation de sommeil. Cette étude a aussi montré qu’il existe une relation entre la durée de l’engagement, mesurée par le nombre de jours passés en mer, et la quantité de sommeil nécessaire, permettant ainsi de résister aux conditions environnementales. Une seconde étude en milieu extrême, cette fois en équipage de deux personnes, en utilisant le même protocole a confirmé que la quantité de sommeil était le meilleur activateur pouvant agir sur l’anxiété et permettre au mieux sa régulation. Une troisième étude nous a permis de montrer que la tolérance à un effort, mesuré par la perception de l’effort, n’était pas couplée exclusivement à une réponse physiologique mais aussi à des facteurs cognitifs. Le résultat principal de cette étude pilote a été de montrer que l’utilisation du feedback vidéo comme stimulation cognitive diminue significativement la perception de l’effort à partir 50% de la durée de l’épreuve. Contrairement à ce qui aurait pu être attendu, aucun effet n’a été observé sur la fréquence cardiaque. L’ensemble de ces résultats tend à montrer l’importance de l’interaction environnement – individu en milieu extrême, ainsi que lors d’une épreuve menée jusqu’aux limites de l’épuisement. Ces résultats ouvrent des perspectives intéressantes dans les domaines de l’entraînement sportif et de la rééducation
The problem of performance in extreme sailing navigation has been very little studied using rigorous scientific methods consistently and at an angle of view in global environmental conditions. Our work sought to evaluate human behavior in ecological conditions with environmentalist and transactional approach. The main objective of this thesis was to understand what the impact of environmental factors such as wind strength and the amount of sleep as well as cognitive stimulation using a video self-modeling on perception of anxiety, fatigue and exercise tolerance in maximal aerobic speed. The results of the first study, ecological condition, where the influence of wind and sleep deprivation were modeled using the tool transfers functions, has to understand that the sailor makes a time- dependent regulation of its commitment and efforts and hardships such as that of sleep. This regulation is related to the perception of anxiety and intensity of perceived fatigue and is influenced by environmental factors such as wind or sleep deprivation. This study also showed that there is a relationship between the duration of the engagement, as measured by the number of days at sea, and the amount of sleep needed, allowing withstand environmental conditions. A second study in extreme conditions, this time with a crew of two people using the same protocol confirmed that the amount of sleep was the best activator can act on anxiety and allow its better regulation. A third study, we showed that the tolerance to stress, as measured by perceived exertion, was not exclusively coupled to a physiological response but also cognitive factors. The main result of this pilot study was to show that the use of video feedback as cognitive stimulation significantly reduces the perception of effort from 50 % of the duration of the event. Contrary to what might be expected, no effect was observed on heart rate. All of these results suggest the importance of the interaction environment - individual in extreme environments, and in a test conducted to the limits of exhaustion. These results open interesting perspectives in the fields of sports training and rehabilitation

Delay of gratification is the ability to forego an immediate indulgence in lieu of a later, greater reward. Past research has shown that using behavioral strategies may help children to delay gratification longer. The current project tests whether children can learn one such strategy, covering the eyes, through imitation. Four-year-olds saw a model delay gratification using a strategy, using no strategy, or saw no model. They then participated in an accumulation task, where they could earn an incremental sticker reward. Children who saw a strategy showed evidence of imitation by covering their eyes. Unexpectedly, however, this had an adverse influence on their ability to delay gratification. Thus, although children can apply a strategy, its effectiveness may be limited by the type of task used (accumulation) or from an incomplete understanding of the strategy’s function. Additional research is needed to investigate whether delay performance can be promoted by a social example.

This work aims to identify and rank a set of Lean and Green practices and supply chain performance measures on which managers should focus to achieve competitiveness and improve the performance of automotive supply chains. The identification of the contextual relationships among the suggested practices and measures, was performed through literature review. Their ranking was done by interviews with professionals from the automotive industry and academics with wide knowledge on the subject. The methodology of interpretive structural modelling (ISM) is a useful methodology to identify inter relationships among Lean and Green practices and supply chain performance measures and to support the evaluation of automotive supply chain performance. Using the ISM methodology, the variables under study were clustered according to their driving power and dependence power. The ISM methodology was proposed to be used in this work. The model intends to provide a better understanding of the variables that have more influence (driving variables), the others and those which are most influenced (dependent variables) by others. The information provided by this model is strategic for managers who can use it to identify which variables they should focus on in order to have competitive supply chains.

碩士
國立東華大學
企業管理學系
95
An empirical analysis of the results and important findings for the research are as follows: 1. Differences among Leadership Styles, Job Satisfaction, Organization Commitment on Job Performance in Demographic Variables According to statistical analysis, there are significant differences among leadership styles, job satisfaction, organization commitment and job performance in different sex, age, education, position, tenure, marital status. 2. The Influential Relationships among Leadership Styles, Job Satisfaction, Organization Commitment on Job Performance In the overall model, the study found that the biggest factor affecting performance is the job satisfaction construct. Leadership style can indirectly affect job satisfaction and organizational commitment performance. Job satisfaction can directly affect the performance; organizational commitment can also indirectly influence performance. Organization commitments can directly affect performance.

碩士
國立東華大學
企業管理學系
94
Abstract: This research bases on personality specialty and demography to create the cause-effect model of leadership, organizational culture, organizational commitment, organizational learning, knowledge management, and the organizational performance. Finally, through the application of structural equation modeling, probe into the leadership, organizational cultures, organizational commitment, organizational learning, knowledge management, and the organizational performance in real world. Through empirical example analysis, this research can get most of every variable, and understand the variable and variable existence relation and intensity of one. The result of this study is helpful life insurance finance industries factory according to different industries and companies to fond their own strategies. And the overall qualitative control and variables of leadership, organizational cultures, organizational commitment, organizational learning, knowledge management, and the organizational performance, can be the foundation of the relevant topic for other researchers.

碩士
國防大學管理學院
運籌管理學系
98
When the enterprise faces global competition, the staff become gradually important property and to be a successful factor to the organization. So, how to manage the staff, listen attentively to the staff’s aspiration, help promoting the efficiency of administration and so on are the methods to aid the enterprise. The manager of the enterprise how to support and encourage the staff to make them in ability and psychology to meet the organization’s demand and expectation, then achieves the organization goal. This research aid is through the questionnaire discussing the influence of perceived supervisor support, psychological capital, job satisfaction, organization commitment and work performance. The result shows that perceived supervisor support along with the age increase and presents the U pattern relation. The influence of psychological capital, and work performance is greater than the influence of organization commitment and work performance, because the work characterization and environment. In addition, the influence of perceived supervisor support, psychological capital, job satisfaction, organization commitment and work performance are all positive influences. The empirical result could provide support, encourage the staff when the company manager execute the organization strategy. That could make staff in good situation to execute works and increases the staff psychology capital, job satisfaction, organization commitment. Then, promote the aspect of work performance. So, it could be a decision-making reference.

碩士
國立東華大學
企業管理學系
94
This research create the cause-effect model of leadership, organizational culture, organizational learning, job satisfaction, organizational commitment and the organizational performance. Then, through the application of SEM, probe into the leadership, organizational culture, organizational learning, job satisfaction, organizational commitment and the organizational performance in real world. The result of this study is helpful for life insurance industry according to this result the companies can find their own strategies. And the leadership, organizational culture, organizational learning, job satisfaction, organizational commitment and the organizational performance, can be a foundation of the relevant topic for other researchers. Depending on the analysis of real evidences, this research results to four main implications: 1.Statistics Analysis and Scheffé Test Discovery From the sex the female is more over than male. And the age distribution, the major workforce is on the meridian of life; the level of education is college or university; the seniority is around 1~5 years, The job position major is basic employee.The major department is Customer Service Dept. The amount of total employees are over 3001. At Scheffé test, we find that there has difference between different industries and the population statistics. 2.Research Theory Model Fit Discovery Overall, the entire model fit is acceptable. It is pointed that the whole theory model of this study completes the standard of the fit test. To sum up, the result shows the indeed influential relationship among the six concepts. 3.The Influential Relationship among Leadership, Organizational Culture, Organizational Learning, Organizational Commitment, Job Satisfaction and the Organizational Performance. Leadership and organizational culture only influence organizational performance indirectly through other concepts. The highest influence on organizational performance is organizational learning. Second is job satisfaction. These two concepts are key point. 4.The Differences among Leadership and Organizational Culture result to different relation and influence through other concepts to organizational performance. Though Leadership and Organizational Culture don’t effect organizational performance directly, however it is still quite important to influence staff’s responsing. Transformational leadership and creative culture have highest influence on the total results.