Memory unit is one of the fundamental hardware components in system-on-chip (SoC) design, and takes a significant portion of total area cost. Although commercial memory compilers exist, they usually contains memory unit with single-port or dual ports. However, many SoC designs require memory units that support simultaneous multiple reads and writes. They cannot be efficiently generated using the existing memory compilers in the standard cell library. In this thesis, we develop a memory generator that can automatically produce the circuits of multi-port SRAM and all the necessary models required in the standard cell-based design flow. Compared to the design based on dual-port SRAM from memory compilers which usually consists of duplicated copies of SRAM units for supporting multiple write at the same, the proposed design has smaller area cost. Furthermore, we employ various low-power design concepts, including power-gating and adaptive body-bias, to reduce the dynamic and static power of the generated SRAM circuits. Experimental results show that the proposed multi-port SRAM generator can be used to synthesize low-power and low-area register file circuits that support multiple reads and writes at the same time.

Demand is emerging for offshore wind power plant (WPP) that often has favorable capacity factor and high capacity value as compared with onshore wind farms. There are many challenges regarding power losses, economics, protection system and reliability of the wind farm. Collection system design decisions play an essential role to efficient operation of the WPP. Wind generators also have to be able to cope with grid disturbances. Low voltage ride-through (LVRT) capability of wind turbines requires generator units remain in operation for severe voltage drops during ¡@grid system faults, and be able to withstand depressed voltage for a few seconds in a recovery period. Technical requirements set out in grid codes for off shore wind farm normally relate to different connection points. A rigor LVRT requirement would increase the overall investment costs of the wind farm. In most offshore wind farm projects, radial collector systems connecting a number of wind turbines and terminated at the offshore platform have served well the requirements for an economical design. However, due to the lack of redundancy, its reliability is poor. To improve the reliability of the collector system, the inclusion of a cable section that interconnects the remote ends of two adjacent radial feeders has been proposed. The transmission system of a wind farm takes the power generated and sends it to shore. Medium voltage AC transmission is the simplest one, just gathering the cables from the collector system and taking them together until they reach the point of common coupling (PCC).Through wind farm dynamic simulations by using DIgSIENT package, this thesis demonstrates that the ride through capability which occur at the particular wind parks with different collector system topology are greater than those which the wind turbines are capable of riding through, i.e., LVRT curves of different wind farm collection system designs of an offshore WPP and a single wind generator are different. This can be exploited to reduce the cost in complying with LVRT requirement of offshore WPP.

This thesis is aimed to study the heat and mass transfer performance of a generator for the absorption cooling system. Both aqueous lithium bromide (LiBr) and lithium chloride (LiCl) solutions are studied. The generator inlet concentration and outlet concentration are set to 55% and 60%, respectively, for aqueous lithium bromide solution, and 40% and 45%, respectively, for aqueous lithium chloride solution. Therefore, the system of falling film desorption process is studied for the simulation of the generator. A finite-difference method is applied to numerically simulate the heat and mass transfer for a falling film desorption process in the generator. Parameters effects the inlet temperature, the heat source (wall) temperature, and the vapor pressure consistent with the saturation pressure of the condenser, and the solution flow rate are studied. The results of the present study provide important design references for absorption cooling systems.

In today’s competitive market, it is essential to be innovative and creative for an industry to sustain. Industry need to introduce new products to the market. Engineering idea generation plays a vital role in the development of new products. This research study is focused on the engineering idea generation. The representations of ideas have an important impact on the idea generation process. Design concepts may be represented in a variety of forms like sketches, physical models or computer based models. The goal of this research is to understand how these various representations affect design cognition. In this thesis, three studies showing the effects of two different representations in the idea generation process are presented. The first study focuses on the effects of physical models in engineers’ design cognition. This preliminary study investigates two different hypotheses: (1) Physical models supplement and improve designer’s mental models and (2) Physical models induce design fixation. The results show that physical models supplement the designer’s mental models but fail to enhance them. No evidence of design fixation is observed. The second and third studies investigate the effects of computer-based idea generation software on design cognition. The research questions investigated in this study are: (1) How does the use of this software tool assist design cognition? (2) How can the software interface be improved so that designers can generate ideas more easily? To answer these questions, a between-subjects idea generation experiment is conducted. In the experiment, the participants are asked to generate ideas to solve a design problem with and without the software. The results show that participants who generated ideas with the help of the software tool have less quantity of ideas compared to the control group. This may be due to the design fixation induced by the concepts presented. In the third study, the opinions of the participants for the improvements of the software interface are collected. Results show that participants do not have any preference of one way of clustering the concepts over the other. The results of this study also provide creative input for the future improvement of the software.

With the widespread use of doubly-fed induction generators (DFIG) in wind energy conversion systems, condition monitoring is being given importance. Non-intrusive techniques like motor current signature analysis (MCSA), which involves looking for specific frequency components in the current spectrum, are preferred over analysis of magnetic field, temperature, vibrations or acoustic noise which require additional sensors. The major difficulty in MCSA is isolation of the fault, as multiple faults produce similar signatures. Moreover, closed-loop control makes diagnostics more complicated due to inherent compensation by the controller. This thesis presents a method to diagnose static and dynamic air gap eccentricities in doubly-fed induction generators operated for closed-loop stator power control by using a modified control technique to enable detection and isolation of this fault from electrical unbalances in the stator and rotor and load torque oscillations that produce similar effects. The effectiveness of the proposed control is verified using simulations and preliminary experiments performed on a healthy machine.

This thesis includes three topics. The first topic is a low-variation 1 MHz clock generator. The second one is a high sensitivity linear voltage-to-frequency converter. The last one is a high-PSR bias circuit for NTSC SYNC separation. All of the circuits can be applied to related consumer electronic products. The low-variation 1 MHz clock generator includes a bias circuit which automatically compensates the drifting caused by temperature variations. Furthermore, the circuit contains neither BJTs nor diodes to reduce the area cost. The frequency variation is measured to be less than 2.55\% in the range of 0¢J~90¢J. The high sensitivity linear voltage-to-frequency converter is mainly constructed by a window comparator[11]. We analyze and improve the performance of accuracy to achieve both high accuracy and high sensitivity. The accuracy error is less than 1% and sensitivity is 84 KHz/V in the voltage range of 0.1V~0.8V. The high-PSR bias circuit for NTSC SYNC Separation is implemented by a bandgap reference which is controlled by a feedback loop to reduce the interference of the environment. The measurement variation of the bandgap reference is less than 1\% when the variation of power supply is 10\%. The sensitivity of the bandgap reference to temperature is measured to be 0.0006V/¢J.

Due to the consideration of economic dispatch or system operation, the regional severe unbalance between power generation and load demand will introduce large amount of power flow over the inter-area tie lines. The tripping of transmission lines due to power system fault contingency will result in the increase of power flow over the inter-area tie lines, which may violate the constraint of transient stability. The whole power system could be collapsed due to further tripping of more generators unless proper remedy actions are executed in tie. This thesis proposes an effective approach to determine the generators to be tripped for power system protection. All of the generators in the power system are divided into critical group and non-critical group based on the methods of Energy-gap and Impedance-gap. The power flow capability limit of transmission lines on inter-areas have been derived by transient stability analysis. Once fault contingency occurs on the power system, the power flow of transmission lines on inter-area is compared to the above transmission limit to determine the generators in the critical group to be tripped. By this way, the stable operation of power system can be maintained after the contingency. To demonstrate the effectiveness of the proposed methodology, the Taipower system is selected for computer simulation to verify the generator tripping by system transient stability analysis. Different scenarios of system fault contingencies on primary EHV substations with various power flow conditions over the inter-area tie lines have been investigated to confirm the power system performance by applying the proposed generator tripping.

As a result of Internet popularly, the World Wide Web, a killer application which improves the global network, is used much more frequently. Because World Wide Web is browsed through GUI (Graphic User Interface) which allows end-user to interact and operate with internet websites easily, more and more websites are created and operating. For this moment, the web based GUI proved its advantages that it can be applied not only to general website but also to electronic commerce, enterprise information system, and system resources administration. Today, the processing architecture evolves from early centralized processing architecture to recently distributed processing architecture which is composed of several servers and in which each server is responsible for a different system service. But because each system platform runs on its own unique operating system, system administrators have difficulties operating it. Due to increased numbers of servers, a well-defined systematic management architecture and remote management is necessary. This thesis contains the designs of web based system administration architecture through the designs of united library interface to increase the convenience of expansion on library. In this paper, a prototype system created during the research development will serve as theory verification and as an example for developers of future system management platforms.

In this thesis, a direct digital synthesis (DDS) based function generator design module is presented, defined and implemented using two digital hardware modeling/design languages namely SystemC and VHDL. The simulation, synthesis and applicability performances of these two design languages are compared by following all digital hardware design stages. The advantages and open issues of SystemC based hardware design flow are emphasized in order to be a reference for future studies. SystemC initially appeared as a modeling language like HDL design languages. In the last years, SystemC gained popularity also as a hardware design language and it is expected to become alternative to traditional design languages. Using a single platform for hardware modeling, design and verification reduces the spent time and cost. The designed DDS function generator module supports standard I2C and UART communication protocols and it is in ready to use format for digital applications. In this thesis, the function generator module VHDL code is implemented into Xilinx FPGA and verified on the hardware platforms.

¡@¡@The first topic of this thesis is a high-speed digital clock generator circuit is presented to provide negative delays in order to avoid a multi-locking hazard. The negative delay also results in small power consumption and shorter access time if the proposed circuit is used in the clock generator circuit of memory devices. Meanwhile, an accurately locked clock signal is also provided. The locked clock signal can be as high as 1.0 GHz at the presence of a random noise with 10% of power supply voltage when the design is implemented by TSMC (Taiwan Semiconductor Manufacturing Company) 0.35um CMOS 1P4M technol- ogy. ¡@¡@The second topic of this thesis is an 1-to-4 joystick enhanced interface which can be attached to SONY PS2 (playstation 2) is developed. The enhanced interface can allow 4 persons to play simultaneously through one port at the original game console. A total of 8 players can be supported when two of the interfaces hook up with both joystick ports of the console. The multiple player entertainment effect can be drastically enhanced by the usage of such an interface.