• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1716
  • 1007
  • 496
  • 288
  • 247
  • 157
  • 69
  • 66
  • 45
  • 40
  • 39
  • 37
  • 28
  • 28
  • 27
  • Tagged with
  • 4924
  • 461
  • 339
  • 321
  • 314
  • 277
  • 268
  • 262
  • 256
  • 252
  • 244
  • 235
  • 228
  • 212
  • 209
  • 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.
571

Study on a single-point-mooring cage system for algae culture

Su, Chien-Ning 25 July 2011 (has links)
In view of the foreign mariculture is gradually diversified, and even has a trend that the fish cage aquaculture combines with algae culture at the same facility. A submersible single-point-mooring (SPM) cage system was modified and installed in-situ to investigate the feasibility of the cage system. A numercial model was established to simulate the cage dynamic motion as well as the mooring line tension. A detailed cage construction process was described in this study. Tension meter was used to keep track of mooring line tension, while the ADCP( Acoustic Doppler Current Profiler) was utilized to record the sea state during the test period. Those data were used to validate the numerical model. The field experiements were carried out at a location north to Xiaoliuqiu island. Since the testing period was in winter, the wave height was relativly calm and found to be between 0.5 and 1.2 m, wave period 4~7 seconds, and wave current about 0.2~0.6 m/s. The numerical results indicate that the maximum mooring line tension has good agreement with the meauresments of the tension meter. These comparisons verify that this numerical model is sufficient to simulate this kind of alage cage systems.
572

The Design and Implement of Digital Chip for Power Line Communication

Tsai, Dong-Ruei 08 August 2011 (has links)
In recent years, the development of power line communication and relational application is gradually attracted much attention. The use of power line system is able to achieve home network automation, automatic meter reading, and demand supply management, so it can be a great help for the current emphasis on energy conservation ideas. Therefore, many international organizations and national programs involve in researches. The signal is vulnerable to the environment causing data error in the power line transmission, so that we reduce the use of power line communication. For making great application of power line system, the main purpose of the thesis is to study that ensure the data accuracy, integrity and security through power line transmission. Therefore, we designed the digital chip for power line communication. We achieve the signal transmission with the half-duplex ability through power line by digital chip designing and solve error problems about transmitting data. By designing the modules of digital circuit, the chip can encrypt/decrypt data, correct error-bits of data, detect accuracy of data, process control signals, and modulate/demodulate signals. The purpose is for increasing data accuracy in PLC transmission. The chip design adopts TSMC 0.18£gm process as full digital circuits and applies to the energy meter management.
573

Wireless Location with Inertial Assisted NLOS Mitigation in UWB

Liu, Ting-Wei 19 August 2011 (has links)
The thesis is mainly focused on a hybrid location system, which processes wireless and inertial measurements by extended Kalman filtering. Inertial location system is usually used with Dead-Reckoning method, which calculates the present location and heading direction from a previous known state by using measurements of accelerometer and gyroscope, which have immunity from the environment. The system estimates the position by integrates the measurements of sensors, resulting in high accuracy during a short period. However, the unreliability grows with time due to the bias effect on sensors. By combining the wireless location and inertial system, the uncertainty of estimation can be reduced. In wireless communications, the locations of base stations and the times of signal arrival can be used in locating a mobile station. However, signal propagation could be blocked by objects. The non-line of sight (NLOS) effects cause arrival delay and is usually modeled as exponential distributions. Previously, the improved biased Kalman filters were designed to mitigate the NLOS effect in base station measurements. The system design has difficulty in accommodating inertial measurements. The inertial has immunity to the environment. The property is of help in the NLOS mitigation. Therefore, we propose a hybrid location system that integrating the wireless and inertial measurements by using a hybrid biased extended Kalman filter at the stage of positioning. The system provides better prediction with the assistance of enviroment-free inertial measurements. The NLOS mitigation with prediction feedback scheme results in better mitigation performance. Simulations of different situations have been conducted based on parameters in the IEEE 802.15.3a ultra-wideband environment. The performance differences between the proposed method and other approaches show that inertial assisted system effectively reduces the NLOS effects. Also, the proposed hybrid location system has more efficient mitigation performance and better tracking results.
574

A Study on Internet Marketing For On-Line Accommodation Reservation¡GA Case Study of EasyTravel

Ho, Ken-Yen 28 December 2011 (has links)
Since the tourism industry is thriving and robust recently in Taiwan, it encourages the demand of domestic tourism a lot. Moreover, the internet surfers and e-commerce is keeping increasing, so that we do the study regarding the On-Line Accommodation Reservation as our case study. In order to obtain the data and samples for this study, we choose the EasyTravel as our casey, and do the individual survey via qualitative interview. EasyTravel established in 1988 and the major business is offering the On-Line Accommodation Reservation service. They started doing the Internet Marketing planning and designing as they understand the acceptance level of Hotel industry for the Online-Promotion is the highest one. For now, owing to keep ploughing and weeding the On-Line Marketing, EasyTravel always occupies on the first page of search result when doing the searching. We hope we could obtain the influence of Internet activity and communicating for the On-Line Accommodation Reservation through understanding its history, the key factors of EasyTravel, and it will be the topic of this study. We found if we long for to build efficiency Internet Marketing activity for On-Line Accommodation Reservation and then prompt the business, we must consider four factors as below: (1).Multiple Integrated Marketing¡GTo run the On-Line Accommodation Reservation more efficiency and increasing the sales, setting the SEO (Search Engine Optimization), implement topical or diversified long term Internet promotion, Blogs Marketing, Community-based social management, and Mobile Service are five main schemes for achieving the goal. (2).Community marketing¡GAs the community-orientated network is being well developed, if we could utilize community tools and its influence effectively, it would be reached yield twice the result with half the effort. (3).To Customize and develop innovative service¡GBefore establishing the innovative service, industry characteristics, customer needs, main stream, and ICT tool should be all considered. Hence, it will not only create the uniqueness and the non-substitutable capabilities but also high up the barriers to entry level for other rivals. (4).Concentrating on core business with a continuous investment.¡GEasyTravel starts earning the profit since 2008, nevertheless they still ought to input more resource in original sales continuously. It is much more vital than step into new business at a profit.
575

The Application of Power Line Carrier Technology to Demand Response and Asset Management of Smart Grid

Chen, Chien-Pin 11 July 2012 (has links)
This thesis develops a power line carrier(PLC) communication module using FSK modulation technology by integration of PLC chip, with various hardware circuits such as DSP, signal coupling and amplifier circuits, filter. The communication performance and conduction EMI tests and executed for the communication module developed. The PLC module is then applied for appliance control of commercial customers to fulfill the demand response function for energy conservation by reducing the summer peak loading. Besides sending the load control command from central station in the smart grid, the power consumption of various appliances can also be collected and transmitted back to the control station via two way communication with the PLC communication module. Finally, the broadband PLC (BPLC) is applied for the CCTV supervision in system to support asset management of distribution room to prevent the power equipment from steal. With the remote control of light brightness and CCTV lens with high data transmission rate provided, the communication performance of PLC can therefore be verified in this study.
576

Communication synthesis of networks-on-chip (noc)

Bhojwani, Praveen Sunder 15 May 2009 (has links)
The emergence of networks-on-chip (NoC) as the communication infrastructure solution for complex multi-core SoCs presents communication synthesis challenges. This dissertation addresses the design and run-time management aspects of communication synthesis. Design reuse and the infeasibility of Intellectual Property (IP) core interface redesign, requires the development of a Core-Network Interface (CNI) which allows them to communicate over the on-chip network. The absence of intelligence amongst the NoC components, entails the introduction of a CNI capable of not only providing basic packetization and depacketization, but also other essential services such as reliability, power management, reconguration and test support. A generic CNI architecture providing these services for NoCs is proposed and evaluated in this dissertation. Rising on-chip communication power costs and reliability concerns due to these, motivate the development of a peak power management technique that is both scalable to dierent NoCs and adaptable to varying trac congurations. A scalable and adaptable peak power management technique - SAPP - is proposed and demonstrated. Latency and throughput improvements observed with SAPP demonstrate its superiority over existing techniques. Increasing design complexity make prediction of design lifetimes dicult. Post SoC deployment, an on-line health monitoring scheme, is essential to maintain con- dence in the correct operation of on-chip cores. The rising design complexity and IP core test costs makes non-concurrent testing of the IP cores infeasible. An on-line scheme capable of managing IP core test in the presence of executing applications is essential. Such a scheme ensures application performance and system power budgets are eciently managed. This dissertation proposes Concurrent On-Line Test (COLT) for NoC-based systems and demonstrates how a robust implementation of COLT using a Test Infrastructure-IP (TI-IP) can be used to maintain condence in the correct operation of the SoC.
577

Numerical simulation of three-dimensional combined convective radiative heat transfer in rectangular channels

Ko, Min Seok 15 May 2009 (has links)
This dissertation presents a numerical simulation of three-dimensional flow and heat transfer in a channel with a backward-facing step. Flow was considered to be steady, incompressible, and laminar. The flow medium was treated to be radiatively participating. Governing momentum equations, energy equation, and the radiative equation were solved by a finite volume method. Extensive validation studies were carried out. As part of the validation study, three-dimensional combined convection and radiation in a rectangular channel without a backward-facing step was studied. The SIMPLE algorithm was used to link pressure and velocity fields. The combined convective-radiative heat transfer were studied by varying three parameters, i.e. optical thickness ( H τ =0.1, 0.2, and 0.4) and scattering albedo ( ω=0, 0.25, 0.5, 0.75 and 1). Variation of thermophysical properties with temperature was considered in this study. In this work consideration was given only to cooling. Effects of those radiative parameters on velocity, bulk temperature, and Nusselt number are presented in detail. The fluid with a hot inlet compared to a cold wall was cooled in a relatively short distance from the channel inlet because of the radiation effect. The thermal penetration decreased with a decrease in optical thickness and an increase in scattering albedo. Thermal penetration increased with increasing optical thickness and decreasing scattering albedo. The reattachment length varied with temperature due to variation of thermophysical properties with temperature.
578

A Compact Parallel-plane Perpendicular-current Feed for a Modified Equiangular Spiral Antenna and Related Circuits

Eubanks, Travis Wayne 2010 May 1900 (has links)
This work describes the design and measurement of a compact bidirectional ultrawideband (UWB) modified equiangular spiral antenna with an integrated feed internally matched to a 50-Ohm microstrip transmission line. A UWB transition from microstrip to double-sided parallel-strip line (DSPSL) soldered to a short (1.14 mm) twin-line transmission line feeds the spiral. The currents on the feed travel in a direction approximately perpendicular to the direction of the currents on the spiral at the points where the feed passes the spiral in close proximity (0.57 mm). Holes were etched from the metal arms of the spiral to reduce the impedance mismatch caused by coupling between the transmission line feed and the spiral. This work also describes a low-loss back-to-back transition from coaxial line to DSPSL, an in-phase connectorized 3 dB DSPSL power divider made using three of those transitions, a 2:1 in-phase DSPSL power divider, a 3:1 in-phase DSPSL power divider, a radial dipole fed by DSPSL, an array of those dipoles utilizing the various power dividers, and a UWB circular monopole antenna fed by DSPSL. Measured and simulated results show good agreement for the designed antennas and circuits.
579

An Analysis of the Magnetic Field of Transmission Lines and its Suppression Approaches

Su, Feng-chi 26 June 2006 (has links)
This thesis presents a computational analysis of the magnetic field of low-frequency power transmission lines, and the approaches to its suppression. First, according to the structure of Taiwan's three-phase A.C. transmission network, this research calculated the distribution of conducting wires' magnetic field under specific configuration by applying the theories of Near-field effect, Biot Savart's law, and double complex number. Second, this research explored the features of various approaches to magnetic field suppression with magnetic-field vector analyses and Matlab simulations. Finally, two magnetic-field cancellation methods, the ¡§circuit space arrangement¡¨ and ¡§time phase permutations¡¨ were adopted to investigate their magnetic effects under various structures and combinations of transmission lines. This study reveals that the magnetic field can be effectively suppressed by using appropriate configuration of transmission lines in space and phase. By applying the result to the design and construction of transmission lines, we can meet not only the requirements of magnetic field reduction, but also the needs of the least cost.
580

Improved Equivalent Transmission Line Method for the Shielding Effectiveness of Metal Enclosures with Apertures

Lee, Wei-Kuo 03 July 2006 (has links)
Because the metal enclosure with apertures is the structure of the cavity form, FDTD method belonging to full-wave analytical algorithm isn¡¦t efficient for analyzing such case. Thereby the ETL method belonging to analytical formulation provides another way to analyze it. Although the structure which it can apply to isn¡¦t as complex as that in full-wave analytical algorithm, the computing time is shorter than FDTD. In contrast, the method can¡¦t get good agreement. Thus two improved ways are introduced in this paper. One is to make the suitable structure wider and the other is to consider the higher mode original ETL method isn¡¦t included to improve the accuracy. Further these two ways make the suitable range of the method wider and the method has good practicability.

Page generated in 0.0327 seconds