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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.
321

Applying Kalman Filter to Estimate the OTF of a Polluted Lens in an Image System

Chiu, Hung-chin 05 September 2005 (has links)
The lenses are important elements in optical imaging systems. However, lenses are liable to defects such as dusts and thus deteriorate their imaging quality. The polluted lens can be verified equivalent to a polluted random screen set against a clean lens. In our model, the defects on random screen are assumed poison-distribution, overlapped and the transmittance effect of each defect is multiplicative. In this thesis, we will apply Kalman filter to estimate the optical transfer function for a defected imaging system. The experiments are set up by the instruments including the video camera, capture card, and personal computer. Kalman filter addresses an estimation problem defined by two models: the signal model and the observation model. Kalman filter was originally developed in the field of optimal estimation for application of controlling and tracking. Recently Kalman filter has been very often applied to the problems of image restoration. In this thesis, the signal model is obtained from a ratio of the defected and clean pictures in frequency domain. The observation model is built for an additive measurement noise from electronic sampling. Experimental results have demonstrated that the estimated optical transfer function is useful for image restoration.
322

The Use of Kalman Filter in Handling Imprecise and Missing Data for Mobile Group Mining

Hung, Tzu-yen 01 August 2006 (has links)
As the advances of communication techniques, some services related to location information came into existence successively. On such application is on finding out the mobile groups that exhibit spatial and temporal proximities called mobile group mining. Although there exists positioning devices that are capable of achieving a high accuracy with low measurement error. Many consumer-grades, inexpensive positioning devices that incurred various extent of higher measurement error are much more popular. In addition, some natural factors such as temperature, humidity, and pressure may have influences on the precision of position measurement. Worse, moving objects may sometimes become untraceable voluntarily or involuntarily. In this thesis, we extend the previous work on mobile group mining and adopt Kalman filter to correct the noisy data and predict the missing data. Several methods based on Kalman filter that correct/predict either correction data or pair-wise distance data. These methods have been evaluated using synthetic data generated using IBM City Simulator. We identify the operating regions in which each method has the best performance.
323

A tuning circuit for MOSFET C filter

Lin, Chang-Chih 16 January 2007 (has links)
MOSFET-C filters is popular in analog filters, the major reason is the simplicity. They are easily implemented with opamps and have similar architectures to active RC filters [1], this saves much of the design time. The frequency response of analog continuous time filters is determined by resistors, capacitors, inductors or transconductors. However, the process variation, temperature drift and aging, make the integrated RC time constants vary about 30 percent [2]~[3]. We proposed a switched-capacitor tuning circuit , which can be used in MOSFET-C Filter and the novel tuning circuit doesn¡¦t need off chip capacitor. The novel circuit has following advantages (1). Small chip size. (2). Simplicity (3). Low reference clock frequency.
324

Fabrication and Measurement of Semiconductor Optical Amplifiers¡BFabry-Perot Laser and Ring Cavity Filter

Lin, Shin-Hung 09 July 2007 (has links)
In this thesis, we have established an optical measurement system to measure the device characteristics. We focus on the investigation of semiconductor optical amplifier, Fabry-Perot laser, and ring cavity filter. We used InP-based multiple quantum wells epitaxial wafer with modulation doping in the active layer. A 1.41 £gm symmetric InGaAlAs/InP quantum well structure is used to fabricate the optical waveguide ring resonator devices for the optical communication region at 1.55£gm wavelength. For the semiconductor optical amplifier and lasers, we designed two different types: Fabry-Perot Amplifier (FPA), and Traveling Wave Amplifier (TWA). The InGaAlAs-FPA structure has three lasing peaks at 1514 nm, 1528 nm, and 1544 nm. The InGaAlAs-TWA-a structure has only one peak at 1510 nm. The InGaAsP-TWA-b structure has a gross gain = 8.5 dB (wavelength = 1575 nm) at pumping current = 22 mA. We used Hakki-Paoli method and transparency current to calculate gain spectrum. For ring cavity filter, the optical spectrum has a FSR = 41.25 GHz.
325

Using Resampling to Optimizing Continuous Queries in Wireless Sensor Networks

Liu, Pin-yu 17 July 2007 (has links)
The advances of communication and computer techniques have enabled the development of low-cost, low-power, multifunctional sensor nodes that are small in size and capable of communicating in short distances. A sensor network is composed of a large number of sensor nodes that are densely deployed either inside the phenomenon to be observed or very close to it. Sensor networks open up new opportunities to observe and interact with the physical world around us. Despite the recent advances in sensor network applications and technology, sensor networks still suffer from the major problems of limited energy. It is because most sensor nodes use battery as their energy srouce and are inconvenient and sometimes difficult to be replaced when the battery run out. Understanding the events, measures, and tasks required by certain applications has the potential to provide efficient communication techniques for the sensor network. Our focus in this work is on the efficient processing of continuous queries, by which query results have to be generated according to the sampling rate specified by the user for an extended period of time. In this thesis, we will deal with two types of continuous queries. The first type of queries requires data from all sensor nodes; while the other is only interested in the data returned by some selected nodes. To answer these queries, data have to be sent to the base station at some designated rate, which may consume much energy. Previous works have developed two methods to reduce the energy consumption. They both base on the error range which the user can tolerate to determine whether current sensing data should be transmitted. While the first uses simple cache method, the second uses complex multi-dimensional model. However, the proposed methods required the user to specify the error range, which may not be easy to specify. In addition, the sensed data reported by the sensors were assumed to be accurate, which is by no means true in the real world. This thesis is based on Kalman filter to correct and predict sensing data. As a result, the sampling frequency of each sensor is dynamically adjusted, referred to as resampling which systematically determine the data sensing/transferring rate of sensors. We evaluate our proposed methods using empirical data collected from a real sensor network.
326

A Study of Coupled-Resonator Bandpass Filters on Organic Substrates

Li, Hsiao-Chun 24 July 2007 (has links)
This thesis is mainly divided into two parts. The first part discusses in detail design flow of the coupled-resonator bandpass filters, including basic theory of synthesis and the procedure of electromagnetic (EM) simulation. In the second part, by using the above-mentioned design flow, different structure filters have been implemented on organic substrates. The coupled-resonator BPF designs are verified to overcome the elements¡¦ parasitic effects, and thus can be optimized with high degree of freedom. In practice, a 3rd-order bandpass filter by coupling three spiral resonators has been proposed and implemented, having miniature and wide stopband characteristics. Finally, a two-layer 4th-order cross-couple bandpass filter with a pair of transmission zeros has been also proposed and implemented, achieving a significant size reduction of 50% compared with the single-layer design. The simulation and measurement results have good agreement for all design cases in this thesis.
327

1.Treatment of 2-Ethyl Hexanol in an air stream by a pilot-scale Biotrickling Filters. 2.Treatment of gaseous VOC emissions from a resin manufacturing plant by a full-scale Biotrickling Filters.

Chen, Liang-Chi 05 July 2000 (has links)
The subject of this thesis is divided into two parts: (1) Treatment of 2-ethyl hexanol (2-EH) in an air stream by a pilot-scale biotrickling filter, and (2) Treatment of gaseous VOC emissions from a resin manufacturing plant by a full-scale biotrickling filter. Treatment of 2-Ethyl Hexanol in An Air Stream by A Pilot-Scale Biotrickling Filter 2-Ethyl Hexanol (2-EH) may release from the thermal breakdown of di-isooctyl phthalate (DOP), a commonly-used plasticizer, in the curing stage when manufacturing PVC synthetic leather and gloves. This paper reports the results of studies using a biotrickling filter (BTF) with blast-furnace slag packings (sizes = 2-4 cm and specific surface area = 120 m2/m3) for treatment of 2-EH in an air stream. The experimental setup consisted of a set of two-stage-in-series biotrickling filters. Each stage of the biotrickling filter was constructed from a 19.5-cm x 200-cm (ID x H) acrylic column packed with slags of 125 cm in height. The operation started with the conditions of recirculation liquid pH = 8.0 and rate (VL) = 8.83 m3/m2.h, a steady nutrient (ammonia nitrogen and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packing slags could be observed in one week and well developed in two weeks after the start-up operation. The effects of volumetric 2-EH loading (L) and superficial gas velocity (U0) on the 2-EH elimination capacity (K) and the removal efficiency (K/L) were tested. Long-term experimental results show that, in the conditions of influent 2-EH concentration C0 = 250 mg/m3, U0 = 162 m3/m2.h, and gas empty-bed-retention time EBRT = 55 s, K/L could be correlated by the equation K/L = 71.9/(72.4+L) with a correlation coefficient (R) of 0.9988. The 2-EH elimination rate was mass-transfer controlled when L<16 g/m3.h and reaction-controlled when L>16 g/m3.h. Results also indicate that nutrient addition and liquid recirculation were important for the normal operation of the BTF in eliminating the influent 2-EH. Treatment of Gaseous VOC Emissions from A Resin-Manufacturing Plant by A Full-Scale Biotrickling Filter A resin and chemical company located in Tainan County, Taiwan engages in the manufacture of PU (poly urethane), PVAC (poly vinyl acetate), PS (poly styrene), and PMMA (poly methyl methacrylate) resins from various chemical stocks. Gaseous volatile organic compounds (VOCs) emitted from the reactors include toluene, methyl ethyl ketone (MEK), acetone, vinyl chloride, styrene, butyl acetate, 2-ethyl hydroxyl acetate, and methyl methacrylate. These VOCs should be properly eliminated before discharging the reactor vents to the atmosphere. This paper reports the performance results of using a biotrickling filter (BTF) with wood packings (sizes = 2-12 cm and specific surface area = 97 m2/m3) for treating the reactor vents with a total flowrate of 80 m3/min at 20-30¢J. The BTF was constructed from a 7.0 m x 6.0 m (ID x H) SUS 304 column with wood packings of 4.0 m in height. The operation started with the conditions of recirculation liquid pH = 7.0-8.0 and rate (VL) = 1.56 m3/m2.h, a steady nutrient (urea and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packings could be observed in one week and well developed in two weeks after the start-up operation. Long-term operation results show that, in the conditions of influent VOC concentration C0 = 200-10000 ppm (expressed in terms of methane), U0 = 125 m3/m2.h, and gas empty-bed-retention time EBRT = 115 s, K/L could be correlated by the equation K/L = 345/(467+L) with a correlation coefficient (R) of 0.9913. The VOC elimination rate was mass-transfer limited when L<45 g/m3.h, with the mass of VOCs expressed as that of methane. Results also indicate that the liquid recirculation might be interrupted for a hour without influencing the performance. Toluene was the most difficult one to eliminate among the VOCs in the gas stream.
328

Mpeg Video Coding Improved by Mask Operation

Shieh, Jia-Horng 13 July 2000 (has links)
MPEG is a primary standards for dynamic image compression. The error can be introduced in the quantization process of the block DCT transformation . In this sense, the shape compensation by Boolean filter is proposed by us to adjust the intensity distribution of the motion compensated image. That is, our dynamic images are coded by the kinds of Boolean filter in addition to motion vectors after DCT coding. Boolean operation is usually applied to the binary images. The minterms of Boolean operations can be reprensented by masks. For the gray level images the mask operation is changed to be the more complex window operations. More clearly, there are two masks for a miniterm. One is a complement mask. The other is a maximum or minium window. For coding efficiency, in this paper a common complemented mask is used for two miniterms. In this sense, our Boolean filters are limited in a category of two miniterms with a same complemented structure. Experiment results have demonstrated that images going through the extra Boolean filtering have better visual quality than images processed by motion compensation only. The price is paid by the coding complexity and a relatively simple decoding structure. However, it is the decoding process which is more crucial in real time play. Therefore, we successfully integrated the Boolean filtering into MPEG-1 system in software implementation.
329

CMOS Current Controlled Conveyor and Tunable IF Filter Application

Wu, Yi-Ming 26 July 2000 (has links)
A second-generation CMOS current controlled conveyor (CCCII) and a tunable IF bandpass filter based on the CCCII are developed. The high frequency property and the control ability of the current conveyor makes the bandpass filter tunable in the range between 55MHz~410MHz, which is suitable for the IF filter application that is around 200MHz~300MHz. The Q-factor is also tunable and has a maximum value up to 800.
330

An ISM-Band Frequency Synthesizer with Closed-Loop GFSK Modulation

Chen, Hsing-Hung 04 July 2001 (has links)
An ISM-band frequency synthesizer is introduced in this thesis. The technique allows digital phase/frequency modulation to be achieved in a closed phase locked loop (PLL) without mixers and D/As. According to the simulation results using ADS, quantization noise will be filtered by the PLL bandwidth. But the data rate is also bounded by the PLL bandwidth. Two key components of this closed-loop architecture, Gaussian filter and delta-sigma modulator have been implemented by FPGA together with the Qualcomm Q3236 synthesizer IC.

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