In recent years, pipeline construction of shallowly buried flexible pipes is increasing. This is due to the cost of general pipeline construction with deep excavation, having depth of cover of about 1.5-2.0 times of t...
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ISBN:
(纸本)0784406901
In recent years, pipeline construction of shallowly buried flexible pipes is increasing. This is due to the cost of general pipeline construction with deep excavation, having depth of cover of about 1.5-2.0 times of the pipe diameter. However, buried pipeline with a shallow depth of cover has a risk of large deformation caused by traffic loads. This paper presents the behavior of buried flexible pipe with shallow depth of cover under traffic live load analyzed by D.E.M.(Distinct Element Method analysis). As a result, it was found that the behavior of a shallowly buried pipe under traffic live load can not be evaluated by the current design according to Spangler's assumption.
A novel elastic image registration approach is proposed, which can register both 2D medical images and gel elec.rophoresis automatically and accurately. Firstly, the global affine registration method based on image in...
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ISBN:
(纸本)9780909925970
A novel elastic image registration approach is proposed, which can register both 2D medical images and gel elec.rophoresis automatically and accurately. Firstly, the global affine registration method based on image intensity is used to initialise a starting estimation of the robust registration algorithm. Then, by using iterative landmark based algorithm, the affine registration results are registered to further improve the accuracy in the second step, in which, the novel automatic landmark localization method is introduced and the thin-plate spline is used to refine the registration precision. Experimental results are presented for the registration of the 2D Phantom images and gel elec.rophoresis.
An important Quality-of-Service (QoS) issue in wireless multimedia networks is how to control handoff drops. In this paper, we propose admission control algorithms that adaptively control the admission threshold in ea...
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An important Quality-of-Service (QoS) issue in wireless multimedia networks is how to control handoff drops. In this paper, we propose admission control algorithms that adaptively control the admission threshold in each cell, in order to keep the handoff dropping probability below a pre-defined level. The admission threshold is dynamically adjusted based on handoff dropping events. We first present a simple admission control sch.me which brings out an important performance evaluation criterion - inter-cell fairness - and serves as a reference point. We then investigate the inter-cell unfairness problem and develop two enhanced sch.mes to overcome this problem. The performance of these protocols is benchmarked and compared with other competitive sch.mes. The results indicate that our sch.mes perform very well while, in addition, achieving significantly reduced complexity and signaling load.
Distributed Genetic Algorithms (DGAs) constitute an interesting approach to undertake the premature convergence problem in evolutionary optimization. This is done by spatial partitioning a huge panmitic population int...
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Distributed Genetic Algorithms (DGAs) constitute an interesting approach to undertake the premature convergence problem in evolutionary optimization. This is done by spatial partitioning a huge panmitic population into several semi-isolated groups, called demes, each evolving in parallel by its own pace, and possibly exploring different regions of the search space. At the center of such approach lies the migratory process that simulates the swapping of individuals belonging to different demes, in such a way to ensure the sharing of good genetic material. In this paper, we model the migration step in DGAs as an explicit means to promote cooperation among genetic agents, autonomous entities encapsulating GA instances for possibly tackling different sub-problems of a complicated task. The focus is on the characterization of adaptive migration policies in which the choice of what individuals to migrate and/or replace is not defined a priori but according to a more knowledge-oriented rule. Comparative results obtained for a data-mining task were conducted, in order to assess the performance of adaptive migration according to efficiency/effectiveness criteria.
The founding of the Computing Curricula 2001 Task Force to focus on computerengineering is discussed. One of the primary objectives is to define computerengineering as a discipline, distinct from the fields of elec....
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The founding of the Computing Curricula 2001 Task Force to focus on computerengineering is discussed. One of the primary objectives is to define computerengineering as a discipline, distinct from the fields of elec.rical engineering and computerscience. As a basis for curriculum development, computerengineering is defined in terms of the unique knowledge and activities it embodies. computerengineering focuses on the design of computing elements and computer based systems, and integrated hardware and software and provides human interfaces to produce efficient cost-effective total systems to solve technical problems.
The proposed protocol, Code Grouping Multiple Access (CGMA), partitions mobile users into virtual code groups to enhance channel utilization for multimedia traffic in a TDD-CDMA environment. CGMA performance has previ...
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The proposed protocol, Code Grouping Multiple Access (CGMA), partitions mobile users into virtual code groups to enhance channel utilization for multimedia traffic in a TDD-CDMA environment. CGMA performance has previously been evaluated for both error free and error prone uplink channels. It has been shown that CGMA allocates channel resources more fairly to mobiles while guaranteeing QoS for voice service in comparison to reservation protocol such as first come first serve algorithm. In this paper, the delay performance of CGMA and its fairness in resource distribution are evaluated assuming both uplink and downlink errors. Simulation results confirm that CGMA provides fair resource allocation under both error free as well as with uplink/downlink channel errors.
In this work, a linear position sensor with a Hall effect element for automotive applications is presented. The work involves the design of device structure, finite element analysis (FEA) computer modeling of sensor p...
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In this work, a linear position sensor with a Hall effect element for automotive applications is presented. The work involves the design of device structure, finite element analysis (FEA) computer modeling of sensor performance, fabrication of sensor prototype, and prototype characterization. The significance of the work is a low cost linear position sensor has been developed with high linearity for use in automobile control systems. The complete sensor system is designed for ease of manufacturing and the harsh automotive environments.
The simulation of print quality (PQ) defects is a process in which an image is degraded by artificially generated structures to create an impression of real defects when the image is viewed or printed. The simulation ...
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The simulation of print quality (PQ) defects is a process in which an image is degraded by artificially generated structures to create an impression of real defects when the image is viewed or printed. The simulation algorithms generate a set of defective images that can be used in diagnostic tools for printer users. These algorithms can also provide experimental images for psychophysical evaluations regarding defect perception, which requires the capability to control the level of the defects. In addition, simulation of defects aids in testing the usability of a PQ assessment page, and the development of computer algorithms for detecting PQ defects. Thus there are many applications that need high quality simulation of PQ defects. However, little research has been devoted to this work. In this paper, we characterize the common PQ defects in color laser printers such as banding, streaks, ghosting, and repetitive artifacts. We classify these defects into three categories: defects of uniformity, defects of random marks or repetitive artifacts, and color defects. We develop a simulation model for each defect based on its features such as the shape and the spatial distribution of the defect marks, or the tone dependency of the defect. The defects are simulated on RGB color continuous-tone images.
In this paper, a new learning algorithm is introduced. Its structure consists of two stages, the mapping stage and the learning stage, corresponding to three layers, namely, the input layer, the hidden layer and the o...
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In this paper, a new learning algorithm is introduced. Its structure consists of two stages, the mapping stage and the learning stage, corresponding to three layers, namely, the input layer, the hidden layer and the output layer. The input training vectors are initially mapped to the feature vectors in the mapping stage. In the learning stage, the feature vectors are fed into the least square learning module to obtain the estimated output vectors. Until accuracy saturates, a hidden node is added in each iteration, and the process is repeated. A separation validation set is used to determine the optimum dimension of the feature space. The least square learning module can be replaced by an error-correcting least square module or a linear support vector machine.
We have observed very slow surface potential transients in AlGaN/GaN HFETs induced by high drain and gate bias stresses. The surface potential has been observed to change as much as 2.5 V near the gate. It is proposed...
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ISBN:
(纸本)0780374789
We have observed very slow surface potential transients in AlGaN/GaN HFETs induced by high drain and gate bias stresses. The surface potential has been observed to change as much as 2.5 V near the gate. It is proposed that the change in surface potential is caused by elec.rons that tunnel from the gate and get trapped at the surface states. The increase in the net negative charge at the surface raises the surface barrier, which in turn reduces the 2DEG concentration. Simultaneous measurements of surface elec.rostatic potential and drain current indicate that the transients have similar transient responses and are therefore related. A spatial map of the surface potential change after stress with respect to time shows that maximum changes occur close to the gate. Exposure to UV laser light completely eliminates the transients, while large reduction in transient magnitude has been observed for devices passivated with SiNx. Contrary to the gate and drain stress, UV laser exposure of AlGaN/GaN heterostructure samples has been observed to reduce the surface barrier, which slowly increases following a stretched exponential type transient after the laser is switched off. Such an observation is explained by the creation of elec.ron-hole pairs, which decrease the net charge dipole across the AlGaN barrier and lower the barrier. The transient response is modeled by thermionic emission of elec.rons from the interface, which recombine with the holes trapped at the surface.
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