• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 802
  • 474
  • 212
  • 148
  • 88
  • 77
  • 70
  • 23
  • 16
  • 15
  • 13
  • 13
  • 13
  • 13
  • 13
  • Tagged with
  • 2243
  • 2243
  • 969
  • 659
  • 645
  • 442
  • 432
  • 409
  • 357
  • 335
  • 329
  • 328
  • 323
  • 317
  • 317
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
451

High Performance Digital Circuit Techniques

Sadrossadat, Sayed Alireza January 2009 (has links)
Achieving high performance is one of the most difficult challenges in designing digital circuits. Flip-flops and adders are key blocks in most digital systems and must therefore be designed to yield highest performance. In this thesis, a new high performance serial adder is developed while power consumption is attained. Also, a statistical framework for the design of flip-flops is introduced that ensures that such sequential circuits meet timing yield under performance criteria. Firstly, a high performance serial adder is developed. The new adder is based on the idea of having a constant delay for the addition of two operands. While conventional adders exhibit logarithmic delay, the proposed adder works at a constant delay order. In addition, the new adder's hardware complexity is in a linear order with the word length, which consequently exhibits less area and power consumption as compared to conventional high performance adders. The thesis demonstrates the underlying algorithm used for the new adder and followed by simulation results. Secondly, this thesis presents a statistical framework for the design of flip-flops under process variations in order to maximize their timing yield. In nanometer CMOS technologies, process variations significantly impact the timing performance of sequential circuits which may eventually cause their malfunction. Therefore, developing a framework for designing such circuits is inevitable. Our framework generates the values of the nominal design parameters; i.e., the size of gates and transmission gates of flip-flop such that maximum timing yield is achieved for flip-flops. While previous works focused on improving the yield of flip-flops, less research was done to improve the timing yield in the presence of process variations.
452

Suitability of Java for Solving Large Sparse Positive Definite Systems of Equations Using Direct Methods

Armstrong, Shea January 2004 (has links)
The purpose of the thesis is to determine whether Java, a programming language that evolved out of a research project by Sun Microsystems in 1990, is suitable for solving large sparse linear systems using direct methods. That is, can performance comparable to the language traditionally used for sparse matrix computation, Fortran, be achieved by a Java implementation. Performance evaluation criteria include execution speed and memory requirements. A secondary criterion is ease of development. Many attractive features, unique to the Java programming language, make it desirable for use in sparse matrix computation and provide the motivation for the thesis. The 'write once, run anywhere' proposition, coupled with nearly-ubiquitous Java support, alleviates the need to re-write programs in the event of hardware change. Features such as garbage collection (automatic recycling of memory) and array-index bounds checking make Java programs more robust than those written in Fortran. Java has garnered a poor reputation as a high-performance computing platform, largely attributable to poor performance relative to Fortran in its early years. It is now a consensus among researchers that the Java language itself is not the problem, but rather its implementation. As such, improving compiler technology for numerical codes is critical to achieving high performance in numerical Java applications. Preliminary work involved converting SPARSPAK, a collection of Fortran 90 subroutines for solving large sparse systems of linear equations and least squares problems developed by Dr. Alan George, into Java (J-SPARSPAK). It is well known that the majority of the solution process is spent in the numeric factorization phase. Initial benchmarks showed Java performing, on average, 3. 6 times slower than Fortran for this critical phase. We detail how we improved Java performance to within a factor of two of Fortran.
453

Evaluation of High Performance Residential Housing Technology

Grin, Aaron January 2008 (has links)
The energy consumption of residential buildings in Canada accounts for 17% of national energy use (Trudeau, 2005). Production homes represent a considerable portion of new housing. In an effort to reduce the national energy demand, the energy consumption of these homes must be addressed. Techniques, methods and materials to achieve reductions in residential energy use are readily available. The goal of this thesis is to show that it is possible to build a low-energy home for less total carrying cost than a home built to the 2006 Ontario Building Code. To show how this is possible, a range of cost-effective and practical-to-implement upgrades are identified, and quantitative projections of cost-savings and benefits gained by the homeowner are generated. The interest in, and demand for, greener less energy consumptive homes is increasing. As oil prices rise, climate changes, landfills become overburdened and water restrictions become more frequent, the public pushes harder for change. The residential housing sector has seen increased demand for energy efficient homes that incorporate green features, high efficiency appliances and mechanical systems. Increased environmental concern has put ‘Green’ in demand. This thesis reviews a variety of North American green rating systems and contrasts their energy performance requirements with those of the Ontario Building Code. The Ontario Building Code was considered the baseline. Although the R2000 program was originally developed nearly 30 years ago it has managed to maintain a standard of performance that has always exceeded the OBC. It has a wider range of requirements than either the building code or ENERGY STAR, but falls short of the LEED for homes program in terms of breadth of environmental concerns. The literature review shows that homes that use 75% less heating energy than a standard house could be built in the 1980s for a mere 5% construction cost premium. When care is taken to produce quality designs and specifications, and to ensure that details are properly finished, these types of homes can be built almost anywhere. Some of the most successful technology and strategies of the 80’s have found their way into mainstream Canadian houses. As a result, the average new Canadian home consumes less energy than its predecessors. The Ontario building code has some of the most stringent thermal insulation and energy performance requirements of all provincial codes in Canada. However, significantly more can be done to economically reduce house energy consumption. A parametric analysis of a representative urban house was performed. This analysis suggests that there is significant room for improvement in the minimum Ontario Building Code requirements, especially with regard to the insulation and air tightness specifications. In 2006 the OBC requirements for above grade wall insulation were increased from R17 to R19 whereas this investigation found that R34 could be justified financially. The fenestration requirements in the 2006 OBC require windows to attain at least R2.8, while this investigation shows that a further 25% increase to R3.5 will soon be financially sensible.
454

High Performance Digital Circuit Techniques

Sadrossadat, Sayed Alireza January 2009 (has links)
Achieving high performance is one of the most difficult challenges in designing digital circuits. Flip-flops and adders are key blocks in most digital systems and must therefore be designed to yield highest performance. In this thesis, a new high performance serial adder is developed while power consumption is attained. Also, a statistical framework for the design of flip-flops is introduced that ensures that such sequential circuits meet timing yield under performance criteria. Firstly, a high performance serial adder is developed. The new adder is based on the idea of having a constant delay for the addition of two operands. While conventional adders exhibit logarithmic delay, the proposed adder works at a constant delay order. In addition, the new adder's hardware complexity is in a linear order with the word length, which consequently exhibits less area and power consumption as compared to conventional high performance adders. The thesis demonstrates the underlying algorithm used for the new adder and followed by simulation results. Secondly, this thesis presents a statistical framework for the design of flip-flops under process variations in order to maximize their timing yield. In nanometer CMOS technologies, process variations significantly impact the timing performance of sequential circuits which may eventually cause their malfunction. Therefore, developing a framework for designing such circuits is inevitable. Our framework generates the values of the nominal design parameters; i.e., the size of gates and transmission gates of flip-flop such that maximum timing yield is achieved for flip-flops. While previous works focused on improving the yield of flip-flops, less research was done to improve the timing yield in the presence of process variations.
455

High Performance Window Systems and their Effect on Perimeter Space Commercial Building Energy Performance

Lee, Ivan Yun Tong 29 September 2010 (has links)
In the quest for improving building energy efficiency raising the level of performance of the building enclosure has become critical. As the thermal performance of the building enclosure improves so does the overall energy efficiency of the building. One key component in determining the energy performance of the building enclosure is windows. Windows have an integral role in determining the energy performance of a building by allowing light and heat from the sun to enter into a space. Energy efficient buildings take advantage of this free solar energy to help offset heating energy consumption and electric lighting loads. However, windows are traditionally the least insulating component of the modern building assembly. With excessive use, larger window areas can lead to greater occupant discomfort and energy consumption from greater night-time heat loss, higher peak and total cooling energy demand from unwanted solar gains, and discomfort glare. As a result, windows must be carefully designed to not only minimize heat loss, but also effectively control solar gains to maintain both a thermally and visually comfortable environment for the appropriate climate region and orientation. In this thesis, a complete analysis of window assemblies for commercial office buildings is presented. The analysis is divided into three sections: the Insulated Glazing Unit (IGU), the Curtain Wall Section (frames), and the overall energy performance of a typical office building. The first section investigates the performance characteristics of typical and high performance IGUs, specifically its insulating value (Ucg), its solar heat gain properties (Solar Heat Gain Coefficient, SHGC), and its visual transmittance (VT) through one-dimensional heat transfer and solar-optical modeling. Mechanisms of heat transfer across IGUs were investigated giving insight into the parameters that had the most significant effect on improving each performance characteristic. With a through understanding of IGU performance, attainable performance limits for each of property were generated from combining of different glazing materials, fill gases, and coatings. Through the right combination of materials IGU performance can be significantly altered. The U-value performance of IGUs ranges from 2.68 W/m2K (R-2.1) for a double-glazed, clear, air filled IGU to 0.27 W/m2K (R-21) for a quint-glazed, low-E, xenon filled high performance IGU. The second part of the thesis looks at the thermal performance of curtain wall sections that hold the IGU through two-dimensional heat transfer modeling. Similar to the IGUs, heat transfer mechanisms were studied to by substituting different materials to determine which components are crucial to thermal performance. From this analysis improvements were made to typical curtain wall design that significantly reduces the overall heat transfer within the frame section, producing a high performance curtain wall section. With simple modifications, a high performance curtain wall section can reduce its U-value by as much as 81% over a typical curtain wall section, going from 13.39 W/m2K to 2.57 W/m2K. Thus significantly reducing the U-value of curtain wall systems, particularly for smaller windows. The final part of the thesis examines the impact of typical and high performance windows on the energy performance of perimeter offices of a high-rise commercial building located in Southern Ontario. An hourly simulation model was set up to evaluate both the annual and peak energy consumption of a typical perimeter office space. The office faced the four cardinal directions of north, east, south, and west to evaluate the effect of orientation. The model also included continuous dimming lighting controls to make use of the available daylight. The effect of exterior shading on perimeter space energy performance was also investigated with both dynamic and static exterior shading devices. The results of the simulations revealed that window properties have very little influence on the energy performance of a high internal heat gain office, that is typical of older offices with less energy efficient office equipment and lighting and a higher occupant density. Conversely, window properties, particularly the insulating value of the window, has a greater effect on the energy performance of a mid to low internal heat gain office that is typical of most modern day commercial buildings. The results show windows with lower U-values yet higher SHGC are preferred over windows of similar U-values but with lower SHGC. The results also indicate that both static and dynamic shading have very little effect on energy performance of mid to low internal heat gain offices. From this analysis optimal window areas in the form of window-to-wall ratios (WWR) are presented for each orientation for mid to low internal heat gain offices. The optimal WWR for south-facing facades are between 0.50 to 0.66, and 0.30 to 0.50 for east-, west-, and north-facing facades, while for high internal heat gain perimeter spaces window areas should be kept to a minimum.
456

Design and Analysis of Metastable-Hardened, High-Performance, Low-Power Flip-Flops

Li, David 19 July 2011 (has links)
With rapid technology scaling, flip-flops are becoming more susceptible to metastability due to tighter timing budgets and the more prominent effects of process, temperature, and voltage variation that can result in frequent setup and hold time violations. This thesis presents a detailed methodology and analysis on the design of metastable-hardened, high-performance, and low-power flip-flops. The design of metastable-hardened flip-flops is focused on optimizing the value of τ mainly due to its exponential relationship with the metastability window δ and the mean-time-between-failure (MTBF). Through small-signal modeling, τ is determined to be a function of the load capacitance and the transconductance in the cross-coupled inverter pair for a given flip-flop architecture. In most cases, the reduction of τ comes at the expense of increased delay and power. Hence, two new design metrics, the metastability-delay-product (MDP) and the metastability-power-delay-product (MPDP), are proposed to analyze the tradeoffs between delay, power and τ. Post-layout simulation results have shown that the proposed optimum MPDP design can reduce the metastability window δ by at least an order of magnitude depending on the value of the settling time and the flip-flop architecture. In this work, we have proposed two new flip-flop designs: the pre-discharge flip-flop (PDFF) and the sense-amplifier-transmission-gate (SATG) based flip-flop. Both flip-flop architectures facilitate the usage in both single and dual-supply systems as reduced clock-swing flip-flop and level-converting flip-flop. With a cross-coupled inverter in the master-stage that increases the overall transconductance and a small load transistor associated with the critical node, the architecture of both the PDFF and the SATG is very attractive for the design of metastable-hardened, high-performance, and low-power flip-flops. The amount of overhead in delay, power, and area is all less than 10% under the optimum MPDP design scheme when compared to the traditional optimum PDP design. In designing for metastable-hardened and soft-error tolerant flip-flops, the main methodology is to improve the metastability performance in the master-stage while applying the soft-error tolerant cell in the slave-stage for protection against soft-error. The proposed flip-flops, PDFF-SE and SATG-SE, both utilize a cross-coupled inverter on the critical path in the master-stage and generate the required differential signals to facilitate the usage of the Quatro soft-error tolerant cell in the slave-stage.
457

Exploring Zirconia as a Column Packing Material

Ghugare, Tushar 01 August 2010 (has links)
Zirconia is one of the most promising column packing materials for High Performance Liquid Chromatography (HPLC). The perfect HPLC support material should be energetically homogenous, have a high surface area on which different chemical species can reversibly attach and be physically and chemically stable over a wide range of pH, temperature and solvent conditions. Most existing supports do not have all of these properties. This project is also focused on a proteomics study. Zirconia, hafnium oxide and titanium oxide which are some of the more promising materials currently available, can be used for the separation and analysis of phosphorylated proteins. Adenosine triphosphate, Adenosine diphosphate and Adenosine monophosphate were used as prototypes for phosphorylated proteins. Separation, absorption, fluorescence and SEM studies were performed to determine the adsorption of Adenosine phosphates species at a particular pH on Zirconia. Zirconia was also used for the purification of Fibrinogen Growth Factor (FGF) protein, which are a family of growth factors involved in angiogenesis, wound healing, and embryonic development. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) technique was used to analyze the off-column purification and separation of this protein. This research suggests that, at acidic conditions, adenosine monophosphate has more favorable absorption on the Zirconia surface. On the other hand, the separation study suggests that basic conditions are more favorable for the absorption of ATP, ADP and AMP when mixed together on Zirconia 500. Furthermore, it was found that Zirconia is a very promising material for the purification of FGF protein.
458

The relationship between High Performance Work Practices and Employee Well-being:An Intervening Effect of Work Motivation and Work/Family Balance

Chen, Yi-chien 05 February 2010 (has links)
High-Tech industries in Taiwan realize that employees with professional knowledge and skills are the core advantage to competition, therefore implement so call Strategic Human Resource Management(SHRM). Recently, ¡§high performance work practices(HPWPs)¡¨, one of SHRM, becomes more and more emphasized. It is one of management systems that help employees to get needed competences through commitment, involvement, and incentives and to enhance the contributions to organization. However, are employees in high performance work organization feeling well-being? The purpose of this study is to realize the relevance of these two variables, and also if mediating variables, work motivation and work-family balance, work. Literatures about HPWPs are all about the outcomes of organization, however, this study emphasizes on individual with mediating variables, work motivation and work-family balance. Questionnaires was adopted for this study and 301 valid samples are collected from individuals in high-tech industry. Through statistics analysis, the main results are as below: 1. HPWPs separately have partial positive effect on work motivation, work-family balance, and well-being. 2. HPWPs have positive effect on work motivation and this work motivation mediates the effect of HPWPs on well-being. 3. the positive effect of HPWPs on well-being is mediated by work-family balance.
459

The impacts of high performance work system on career plateau and role performance, turnover intention: Using perception of supervisor support as moderator

Liu, Szu-ying 19 August 2012 (has links)
Talented people are the key factor for enterprises to maintain their competitive advantage. Since 1980s, due to the changes of internal and external environments, reorganization and simplification have become the patterns of organizations, which indicating promotion possibility in an organization has been relatively reduced. These generate the feeling of development limitation within employees and result in the phenomenon of career plateau. However, high performance work system is regarded as a set of management system in human resources field , and it includes most types of best management practices. Therefore, this study attempts to explore antecedents and consequences of variable of the career plateau, including a negative correlation between high performance work system and career plateau as well as the impact of the career plateau on role performance and turnover intention, and whether the perceived supervisor support will be an interference effect. In this study, pairing questionnaires are offered to executives and organizational members 47 effective matching samples are received. Hierarchical linear model is used in this study to verify the hypothesis. The results show: 1. Career plateau is negatively associated with role performance; 2. Career plateau is positively associated with the turnover intention; 3. The effect of perceived supervisor support can interfere with both career plateau and turnover intention. The findings of this study indicate: 1. Organizations should establish career planning and development for employees in order to reduce the adverse effects of career plateau; 2. Organizations should find a method to increase employees¡¦ perceived of supervisor support in order to reduce the negative effects of career plateau; 3. High performance work system is a systematic system. It should be assessed in depth regarding the way of solving the career plateau. Finally, suggestions for future research and the limitation of this study are also discussed. Keywords: career plateau, high performance work system, role performance, turnover intention, perceived supervisor support
460

The Relationships among High Performance Work Systems, Employee Perceived Organizational Support, and Employee's Job change intention

Lee, Guan-Cyun 23 August 2012 (has links)
In the times of globalization, informationization, rapid changing knowledge economy, corporate are facing intensive challenges. Management team knows that they should not only focus on competitive landscape but also enhance human capital in order to strengthen competitiveness and rejuvenate the organization. Accordingly, employees are motivated by every kind of intentions. They regard the degree of support of their work in the organization, the more they satisfy, the more they feel interested with the job, which might commit themselves to meet the organization¡¦s goal and be proud to be one of the whole team. This research is to test if employee perceived organizational support has an mediating effect to high performance work systems and employee¡¦s job change intention. This study collects data along with a 2- phase questionnaire, which were filled out by first-line servicing employee, with a total of 260 valid samples. In phase I analyzed high performance work system measurement result, phase II started 2 weeks after phase I questionnaire in order to prevent common method variance, which collected perceived organizational support and employee¡¦s job change intention. In this study, the result shows that high performance work systems have a significant impact on employee perceived organizational support, and have the negative impact on employee¡¦s job change intention. Moreover, employee perceived organizational support has a negative impact on employee¡¦s job change intention while it has the mediating effect between high performance work systems and job change intention. Keywords¡GHigh Performance Work Systems, Employee Perceived Organizational Support, Employee's Job change intention

Page generated in 0.0986 seconds