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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.
391

Multi-View Imaging of Drosophila Embryos

Groh, Paul January 2008 (has links)
There are several reasons for imaging a single, developing embryo from multiple view points. The embryo is a complex biomechanical system and morphogenesis movements in one region typically produce motions in adjacent areas. Multi-view imaging can be used to observe morphogenesis and gain a better understanding of normal and abnormal embryo development. The system would allow the embryo to be rotated to a specific vantage point so that a particular morphogenetic process may be observed clearly. Moreover, a multi-view system can be used to gather images to create an accurate three-dimensional reconstruction of the embryo for computer simulations. The scope of this thesis was to construct an apparatus that could capture multi-view images for these applications. A multi-view system for imaging live Drosophila melanogaster embryos, the first of its kind, is presented. Embryos for imaging are collected from genetically modified Drosophila stocks that contain a green fluorescing protein (GFP), which highlights only specific cell components. The embryos are mounted on a wire that is rotated under computer control to desired viewpoints in front of the objective of a custom-built confocal microscope. The optical components for the orizontallyaligned microscope were researched, selected and installed specifically for this multi-viewing apparatus. The multiple images of the stacks from each viewpoint are deconvolved and collaged so as to show all of the cells visible from that view. The process of rotating and capturing images can be repeated for many angles over the course of one hour. Experiments were conducted to verify the repeatability of the rotation mechanism and to determine the number of image slices required to produce a satisfactory image collage from each viewpoint. Additional testing was conducted to establish that the system could capture a complete 360° view of the embryo, and a time-lapse study was done to verify that a developing embryo could be imaged repeatedly from two separate angles during ventral furrow formation. An analysis of the effects of the imaging system on embryos in terms of photo-bleaching and viability is presented.
392

Scheduling in a Multi-Sector Wireless Cell

Lin, Chao-Wen January 2009 (has links)
In this thesis, we propose a scheduling problem for the downlink of a single cell system with multiple sectors. We formulate an optimization problem based on a generalized round robin scheme that aims at minimizing the cycle length necessary to provide one timeslot to each user, while avoiding harmful interference. Since this problem is under-constrained and might have multiple solutions, we propose a second optimization problem for which we try to find a scheduling that minimizes the cycle length while being as efficient as possible in resource utilization. Both of these problems are large integer programming problems that can be solved numerically using a commercial solver, but for real time use, efficient heuristics need to be developed. We design heuristics for these two problems and validate them by comparing their performances to the optimal solutions.
393

Modified bargaining protocols for automated negotiation in open multi-agent systems

Winoto, Pinata 29 March 2007 (has links)
Current research in multi-agent systems (MAS) has advanced to the development of open MAS, which are characterized by the heterogeneity of agents, free exit/entry and decentralized control. Conflicts of interest among agents are inevitable, and hence automated negotiation to resolve them is one of the promising solutions. This thesis studies three modifications on alternating-offer bargaining protocols for automated negotiation in open MAS. The long-term goal of this research is to design negotiation protocols which can be easily used by intelligent agents in accommodating their need in resolving their conflicts. In particular, we propose three modifications: allowing non-monotonic offers during the bargaining (non-monotonic-offers bargaining protocol), allowing strategic delay (delay-based bargaining protocol), and allowing strategic ignorance to augment argumentation when the bargaining comprises argumentation (ignorance-based argumentation-based negotiation protocol). <p>Utility theory and decision-theoretic approaches are used in the theoretical analysis part, with an aim to prove the benefit of these three modifications in negotiation among myopic agents under uncertainty. Empirical studies by means of computer simulation are conducted in analyzing the cost and benefit of these modifications. Social agents, who use common human bargaining strategies, are the subjects of the simulation. <p>In general, we assume that agents are bounded rational with various degrees of belief and trust toward their opponents. In particular in the study of the non-monotonic-offers bargaining protocol, we assume that our agents have diminishing surplus. We further assume that our agents have increasing surplus in the study of delay-based bargaining protocol. And in the study of ignorance-based argumentation-based negotiation protocol, we assume that agents may have different knowledge and use different ontologies and reasoning engines. <p>Through theoretical analysis under various settings, we show the benefit of allowing these modifications in terms of agents expected surplus. And through simulation, we show the benefit of allowing these modifications in terms of social welfare (total surplus). Several implementation issues are then discussed, and their potential solutions in terms of some additional policies are proposed. Finally, we also suggest some future work which can potentially improve the reliability of these modifications.
394

A Multiscale Forecasting Methodology for Power Plant Fleet Management

Chen, Hongmei 14 February 2005 (has links)
In recent years the electric power industry has been challenged by a high level of uncertainty and volatility brought on by deregulation and globalization. A power producer must minimize the life cycle cost while meeting stringent safety and regulatory requirements and fulfilling customer demand for high reliability. Therefore, to achieve true system excellence, a more sophisticated system-level decision-making process with a more accurate forecasting support system to manage diverse and often widely dispersed generation units as a single, easily scaled and deployed fleet system in order to fully utilize the critical assets of a power producer has been created as a response. The process takes into account the time horizon for each of the major decision actions taken in a power plant and develops methods for information sharing between them. These decisions are highly interrelated and no optimal operation can be achieved without sharing information in the overall process. The process includes a forecasting system to provide information for planning for uncertainty. A new forecasting method is proposed, which utilizes a synergy of several modeling techniques properly combined at different time-scales of the forecasting objects. It can not only take advantages of the abundant historical data but also take into account the impact of pertinent driving forces from the external business environment to achieve more accurate forecasting results. Then block bootstrap is utilized to measure the bias in the estimate of the expected life cycle cost which will actually be needed to drive the business for a power plant in the long run. Finally, scenario analysis is used to provide a composite picture of future developments for decision making or strategic planning. The decision-making process is applied to a typical power producer chosen to represent challenging customer demand during high-demand periods. The process enhances system excellence by providing more accurate market information, evaluating the impact of external business environment, and considering cross-scale interactions between decision actions. Along with this process, system operation strategies, maintenance schedules, and capacity expansion plans that guide the operation of the power plant are optimally identified, and the total life cycle costs are estimated.
395

Combined Digital/Wireless Link over the Multi-Mode Fiber with VCSEL using CMOS based Feedforward Equalizer

Maeng, Moonkyun 21 April 2005 (has links)
In this dissertation, the combined optical link, where the baseband digital signal and wireless signal are transmitted simultaneously over a multi-mode fiber (MMF) using an VCSEL and received through a photoreceiver and a feed forward equalizer (FFE). For this hybrid optical link, a new type of combiner is developed using the multi-layer organic (MLO) process. For the overall link simulation, a rate-equation-based VCSEL model is developed with circuit components. This model describes the high-speed modulation characteristic as well as the thermal effect on the L-I (light vs. bias current) characteristic. Additionally, The FFE is developed to further extend a MMF distance by compensating differential modal delay (DMD) in MMF. Two different implementation approaches are taken for the FFE by passive LC ladder based delay line and active inductance peaking delay line structure. To overcome the voltage headroom limitation of the conventional Gilbert cell architecture, modified Gilbert cell is presented and implemented as a multiplier cell for both FFEs. The FFEs are fully integrated on a single chip and fabricated by a standard 0.18 ?m CMOS process. The developed FFE successfully rebuild the distorted signal form the MMF at 10 Gbps data rate.
396

Modeling challenges of advanced thermal imagers

Moyer, Steven K. 03 May 2006 (has links)
With the increased technological advances of thermal imagers, existing theoretical models are not capable of predicting the advantages of advanced thermal imagers. The advanced thermal imager contains a staring focal plane array, which may be sensitive to multiple spectra, and light enough to be mounted on a rifle. Research was conducted to address portions of these three areas. Psychophysical experiments were conducted to model the impact of insufficient sampling on human observer performance for the identification of military vehicles. An information comparison metric was proposed for the comparison of different spectral images. The impact of dead pixels and thermal imager noise on the comparison metric were measured. A human performance model was then developed to predict a humans ability to identify small handheld objects. The impacts of these models on current and future research were discussed.
397

A Study on Multi-Hop Wireless Sensor Networks with Turbo Code

Chiu, Chih-ying 25 August 2010 (has links)
Wireless sensor network(WSN) is made up of a large number which are deployed in the environment to collect observations. Each sensor node preprocesses and extracts information from the raw observations. Each sensor node also has the ability to communicate with other sensor nodes or a fusion center via wireless channels. Many aspects of WSNs have been investigated recently, such as efficient routing protocols, distributed data compression and transmission, and collaborative signal processing. We investigate the information processing task at the fusion center. Radio transmission is one of the major power consumer, and the required transmission power not linear in distance between the transmitter and the receiver. Hence in this thesis, we consider a decision made at local sensor may need to go through multi- hop for minimal energy consumption. Sensor and relay employed decode and forward protocol. We investigate how to transmission reliability and how to combine the reliability and we proposed a fusion rule when observations are encoded by Turbo code.
398

Study of a Novel Vertical Non-volatile Multi-Bit SONOS Memory

Chang, Yu-Che 04 August 2011 (has links)
In this thesis, a simple vertical embedded gate (VEG) MOSFET process is proposed and demonstrated by using simulation tools of ISE TCAD and Silvaco TCAD. In fundamental electrical characteristics, we employed junctionless technology and two extra sidewall spacer gates to fabricate the Junctionless Pseudo Tri-Gate Vertical (JPTGV) MOS. According to numerical analysis, the excellent electrical characteristics such as subthreshold swing (S.S.) ~ 60 mV/dec and Ion/Ioff ~ 1010 are achieved at short gate length (Lg) 8 nm. In additional, our proposed VEG structure can also be applied for non-volatile memory. Using VEG structure to fabricate the SONOS devices have some features, it not only has three source/drain (S/D) terminals and two channels which can be operated independently, but also has two silicon nitride trap layers to provide the possible operation of multi-bit. We can apply different voltage in these three S/D terminals to achieve two bits or even four bits operation, thus the device has multi-bit characteristic is realized in this thesis.
399

An Economic Cycle-based Multi-factor Alpha Model¡X with Application in the Taiwan Market

TSENG, Miao-lien 11 August 2012 (has links)
This study aims to find an effective linear combination of factors in different economic cycle periods and then construct two factor timing multi-factor alpha models, one each for the expansion and contraction periods. Then, we wish to examine a further two effects, namely calendar effect and cross effect. The calendar periods are divided into the first half year and the second half year. The cross effect is the combination of the economic cycle and the calendar effect. In addition, this study puts different loadings in core and satellite descriptors, which means we wish to examine which descriptors are more important when we rebalance our portfolio weekly. The empirical results show that the Value factor is effective in expansion and the first half year, and the Size and Earnings Quality factors are effective in contraction and the second half year. Moreover, the Price Momentum and Trading Activity factors are effective most of the time. We find that the optimal weight for core descriptors is 0.3 and for satellite descriptors is 0.7. Finally, the information ratios of our models are superior to the Standard alpha model by Hsu et al. (2011) and the Market Trend-based alpha model by Wang (2011). Taking the AMCross as an example, when the tracking error is below 3%, the IR is 1.40, the active return is 3.09%, the tracking error is 2.20%, the turnover rate is 207% and the transaction costs are 1.2%.
400

The Development of Screenplay Interpreter for Multi-morphic Robots

Wu, Min-Chang 12 September 2012 (has links)
Controlling the robots through a robotic platform has recently been used widely; however, it is necessary to make the platform friendlier in use to bring this product deeply into the family. The screenplay based performance platform (SBPP) of robotic puppet shows proposed in this thesis is a robotic platform composed with cloud computing, User Interface (UI) and Screenplay Interpreter(SI). The users can connect to the UI to edit and setup the screenplay ubiquitously through any device which can link to the internet. Through screenplay interpreter, the robot can perform as the designed screenplay after the setup; that is, one can always designate a different robot to execute during the process of editing, and the actions of these robots will be a message communication with preset meaning. The project of SBPP is divided into two modules: the UI and SI for multi-morphic robots. The work of this thesis takes charge mainly of screenplay interpreter for a variety of robot models and interfacing between NAO(pronounced now) which is a humanoid robot and the screenplay interpreter. And we integrate UI and SI. The integration of the work provides users a friendly UI to edit scenario of NAO and DARwIn-OP such the robot, NAO and DARwIn-OP(Dynamic Anthropomorphic Robot with Intelligence - Open Platform), can play in a scenario as the screenplay describing. The system is demonstrated by a play of ¡§do-as-I-do¡¨ and recorded in a video at YouTube, http://www.youtube.com/watch?v=v8ErTOgAQSo.

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