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  • 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.
341

The study of film bulk acoustic resonator using ZnO thin film

Lin, Re-Ching 25 December 2008 (has links)
In this study, T-ladder type thin film bulk acoustic wave filters had been fabricated based on thin film bulk acoustic wave resonators. The titanium (Ti) seeding layer and platinum (Pt) for bottom electrode were deposited on silicon substrates by a dual-gun DC sputtering system. Field-emission scanning electron microscopy, atomic force microscopy and the four-point probe method showed that the Pt bottom electrode deposited on the Ti seeding layer exhibited favorable characteristics, such as a surface roughness of 0.69 nm and a sheet resistance of 2.27 £[/¡¼. The ZnO piezoelectric film was deposited using the two-step deposition method by RF magnetron sputtering. Field-emission scanning electron microscopy, atom force microscopy and X-ray diffraction revealed that ZnO piezoelectric film exhibited excellent characteristics, such as a the high preferred c-axis orientation and a rigidly precise surface structure with surface roughness of 7.37 nm. The wet etching process is adopted to fabricate cavity of device. The concentration of 30 wt% KOH and etching temperature of 100 ¢J had been indicated appropriate for etching processes. Finally, the top electrodes of the devices are varied to approach the performances of device applications. The results showed the highest coupling coefficient (kt2) of FBAR device can be obtained using platinum top electrode. The high coupling coefficient of FBAR device is appropriate for wide passband filter. The annealing processes had been used in order to improve the characteristics of piezoelectric films. The stress of ZnO film has been improved from -1.656 Gpa to 0.611 Gpa through the annealing process. At the annealing temperature of 400¢J, the ZnO piezoelectric film exhibited excellent characteristics, such as a large grain size with smooth surface. The quality factor of FBAR device using ZnO film with 400¢J annealing was better than that without annealing. The optimal conditions of fabrication processes are adopted to fabricate top electrode, bottom electrode and piezoelectric film. The T-ladder type FBAR band pass filter was constructed by FBAR resonators. The frequency response is measured using an HP8720 network analyzer and a CASCADE probe station. The 3-dB bandwidth, insertion loss and band rejection of the T-ladder type thin film bulk acoustic wave filter are 79MHz, -3.5 dB and 8.4dB at 2,379MHz, respectively.
342

Dual-IMM System for Target Tracking and Data Fusion

Shiu, Jia-yu 30 August 2009 (has links)
In solving target tracking problems, the Kalman filter (KF) is one of the most widely used estimators. Whether the state of target movement adapts to the changes in the observations depends on the model assumptions. The interacting multiple model (IMM) algorithm uses interaction of a bank of parallel Kalman filters to solve the hypothetical model of tracking maneuvering target. Based on the function of soft switching, the IMM algorithm, with parallel Kalman filters of different dimensions, can perform well by adjusting the model weights. Nonetheless, the uncertainty in measured data and the types of sensing systems used for target tracking may still hinder the signal processing in the IMM. In order to improve the performance of target tracking and signal estimation, the concept of data fusion can be adapted in the IMM-based structures. Multiple IMM based estimators can be used in the structure of multi-sensor data fusion. In this thesis, we propose a dual-IMM estimator structure, in which data fusion of the two IMM estimators is achieved by updating associated model probabilities. Suppose that two sensors for measuring the moving target is affected by the different degrees of noise, the measured data can be processed first through two separate IMM estimators. Then, the IMM-based estimators exchange with each other the estimates, model probabilities and model transition probabilities. The dual-IMM estimator will integrate the shared data based on the proposed dual-IMM algorithm. The dual-IMM estimator can be used to avoid degraded performance of single IMM with insufficient data or undesirable environmental effects. The simulation results show that a single IMM estimator with smaller measurement noise level can be used to compensate the other IMM, which is affected by larger measurement noise. Improved overall performance from the dual-IMM estimator is obtained. Generally speaking, the two IMM estimators in the proposed structure achieve better performance when same level of measurement noise is assumed. The proposed dual-IMM estimator structure can be easily extended to multiple-IMM structure for estimation and data fusion.
343

The Research of Taiwan Leading Indicators of Business Cycle

Syu, Sheng-yuan 01 September 2009 (has links)
Taiwan business indicators are announced by CEPD(Council For Economic Planning And Development) , and divided into three categories ¡V business monitoring indications, business expectation indicators and industrial business expectation survey. Business expectation indicators are further divided into the Composite Index of Leading Indicators and the Composite Index of Coincident Indicators. Leading indicators, which are expected to forecast business cycles, are widely used to monitor or even predict the fluctuations of economic activities. They are also used to provide early signals of economic trend and, therefore, considered as a tool to adjust the government¡¦s economic policy. CEPD use the compilation of the USA National Bureau of Economic Research as a reference for a long time, and has announced Taiwan¡¦s ex-business indicators since 1977 without making any revision in the past years, so they announced new business indicators in 2007. As we know, it is difficult to find the leading indicator to make the stable variable of predicting the business cycle, which raises doubts of whether the current leading indicators can done the work concisely. CEPD make the indicators a little bit subjective because of considering government¡¦s policy and the meaning of containing widely economic fields and the convenience of static, so this research try to examine the effect of current seven leading indicators. This thesis focuses on leading indicators to investigate how the seven components are related to the general economy. Composite Index of Leading Indicators is made up of seven indicators in order to predict the business cycle. The seven indicators include Index of export orders, Monetary aggregates, M1B, Stock prices index, Index of producer's inventory, Average monthly overtime in industry & services, Building permits, SEMI book ¡Vto¡Vbill ratio. In the purpose of getting more sample data, we take Industrial production index, one of coincident indicators announced by CEPD as the variable of current economy.
344

FPGA Implementation of an Adaptive LMS decorrelating transversal filter for CDMA System

Chen, Kuan-Nan 02 September 2009 (has links)
In this thesis, we investigate the CDMA (Code Division Multiple Access) multi- user detection scheme where the DD (Decorrelating Detector) is used to eliminate the multiple access interference. The DD algorithm need to compute the inverse of the matrix involves a great deal of computation, especially when the number of users is large. A recursive method with the LMS (Least-Mean-Square) algorithm, namely the decorrelating transversal filter, to detect users¡¦ signals adaptively can reduce greatly the computational complexity of a CDMA multi-user detector. In this thesis, we focus on the hardware FPGA (Fdield Programmable Gate Array) implementation of the decorrelating transversal filter. The functional system simulation of the decorrelating transversal filter is carried out by using Matlab first. Then this filter is implemented by the Xilinx FPGA and its system performance is also verified.
345

Improved Particle Filter for Target Tracking in Decentralized Data Fusion System

Lin, Yu-Tsen 06 September 2009 (has links)
In this thesis, we investigate a decentralized data fusion system with improved particle filters for target tracking. In many application areas, it becomes essential to use nonlinear and non-Gaussian elements to accurately model the underlying dynamics of a physical system. Particle filters have a great potential for solving highly nonlinear and non-Gaussian estimation problems, in which the traditional Kalman filter and extended Kalman filter may generally fail. To improve the tracking performance of particle filters, initialization of the particles is studied. We construct an initial state distribution by using least square estimation. In addition, to enhance the tracking capability of particle filters, representation of target velocity by another set of particles is considered. We include another layer of particle filter inside the original particle filter for updating the velocity. In our proposed architecture, we assume that each sensor node contain a particle filter and there is no fusion center in the sensor network. Approximated a posteriori distribution at the sensor is obtained by using the local particle filters with the Gaussian mixture model (GMM), so that more compact representations of the distribution for transmission can be obtained. To achieve information sharing and integration, the GMM-covariance intersection algorithm is used in formulating the decentralized fusion solutions. Simulation results are presented to illustrate that the performance of the improved particle filter is better than standard particle filter. In addition, simulation results of target tracking in the sensor system with three sensor nodes are given to show the effectiveness and superiority of the proposed architecture.
346

Effects of heat treatment on properties of color filter

Chang, Ming-chih 08 January 2010 (has links)
ITO is a wide band gap semiconductor material, its band gap is from 4.7 eV to 5.2 eV. Due to the low resistivity, high transmittance to visible light, great absorption to UV light, and high reflection to IR, ITO is wide used to photovoltatic application; such as anodic electrode of Liquid Crystal Display (LCD) and photovoltaic devices. In the thesis, samples are deposited with an ITO layer on color filter (CF) by magnetron sputtering. The conductivity of samples is measured by 4-probe measurement, and the transmittance is characterized by visible spectroscopy. In this work is heat treatment parameters of temperature and annealing time of ITO thin film know been studied, and found an optima condition. From the experiment results, an optima heat treatment condition is temperature of 200¢Jfor 40 minutes, which reveals lower resistivity and improved transmittance of ITO samples. And, it is less process time and lower treatment temperature to used condition for industry presently. The reducing time of heat treatment will increase 9.9 % production, and enhancing the properties of color filter. Depending on the results of this work, there is space to improve performance and reduce power for fabrication of color filter.
347

Implementierung eines Mono-Kamera-SLAM Verfahrens zur visuell gestützten Navigation und Steuerung eines autonomen Luftschiffes

Lange, Sven 21 February 2008 (has links) (PDF)
Kamerabasierte Verfahren zur Steuerung autonomer mobiler Roboter wurden in den letzten Jahren immer populärer. In dieser Arbeit wird der Einsatz eines Stereokamerasystems und eines Mono-Kamera-SLAM Verfahrens hinsichtlich der Unterstützung der Navigation eines autonomen Luftschiffes untersucht. Mit Hilfe von Sensordaten aus IMU, GPS und Kamera wird eine Positionsschätzung über eine Sensorfusion mit Hilfe des Extended und des Unscented Kalman Filters durchgeführt.
348

Anwendung des Kalman-Filters zur Komplexitätsreduktion im Controlling /

Strukov, Urs. January 2001 (has links)
Thesis (doctoral)--Universität St. Gallen, 2001.
349

Humidity effects on hygroscopic particles deposited on HEPA filters and silicon wafer surfaces

Ponkala, Mikko Juha Viljami 24 April 2013 (has links)
Semiconductor wafer manufacturing facilities (fab) must maintain extremely clean air environments to minimize the number of wafers scrapped due to contamination which would result in reduced yields. The fab air is cleaned bypassing it through either HEPA or ULPA filters. A number of airborne fab contaminants may be hygroscopic causing them to exist as a solid or a liquid when in equilibrium with their environment's relative humidity. The effect of relative humidity on such contaminants is poorly documented whether they were to be captured in a filter or deposited on a wafer. The work presented here experimentally characterizes NaCl evolution within HEPA filters when exposed to humidity fluctuations and the effect of humidity on NH4Cl corrosiveness when deposited on cobalt coated wafers with a TiN layer. Successive deliquescence and efflorescence fluctuations were imposed on particles captured on a glass fiber HEPA filter. Scanning Electron Microscopy (SEM) and Environmental SEM (ESEM) studies of the filters showed that the NaCl, under humidity excursions, did not penetrate deep into the filter but deliquesced and effloresced near the top surface of the filter. Pressure drop measurements for filters containing NaCl particles showed differences in pressure drop associated with relative humidity changes. These pressure drop changes suggested some redistribution particle properties. When exposed to a relative humidity of 20%, the NH4Cl particles did not corrode the cobalt wafer beyond the location of the initial deposit. At 61% relative humidity, the surrounding areas of the particles were corroded with a solid artifact left at the original location. At 76% relative humidity the NH4Cl particles were observed to have deliquesced, which is below the expected deliquescence relative humidity. The corrosion of the cobalt wafer was most extensive when the NH4Cl particles had deliquesced. / text
350

Using a biotrickling filter for degradation of cypermethrin, an insecticide frequently used in Tahuapalca, Bolivia

Enstedt, Henric January 2013 (has links)
The feasibility of using bench-scale biotrickling filter reactors inoculated with the fungus UBAF004, isolated from soil in Tahuapalca, for treatment of water contaminated with cypermethrin was investigated. Wood chips, gravel and ceramics were tested as packing materials for the reactors in batch experiments in small glass flasks. Wood proved to be the material on which the fungus grew best and was thus chosen as the packing material for the reactors. It was determined that UBAF004 had quite low competitive strength compared to other microorganisms when growing on wood and gravel but not necessarily on ceramics. UBAF004 grew slowly in the reactors leading to poor degradation performance. The results obtained indicate that it will be challenging to use UBAF004 for treatment of water contaminated with cypermethrin in Tahuapalca. The single largest issue is to find a way to establish a stable population of the fungus in the reactor and to protect it from being out competed by other microorganisms. / <p>Opponent: Veronika Granat</p>

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