We designed a broadband quarter wave plate in the visible range using a twisted nematic liquid crystal film sandwiched between two compensation films. The quarter wave plate exhibits much wider bandwidth than the comm...
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We designed a broadband quarter wave plate in the visible range using a twisted nematic liquid crystal film sandwiched between two compensation films. The quarter wave plate exhibits much wider bandwidth than the commercial product, which is composed of a half wave plate and a quarter wave plate.
Infrastructure Wireless Mesh Networks promise a flexible and cost-effective means for providing last-mile delivery for broadband access, particularly in rural areas. Each customer forwards traffic between their neighb...
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ISBN:
(纸本)9781424406968
Infrastructure Wireless Mesh Networks promise a flexible and cost-effective means for providing last-mile delivery for broadband access, particularly in rural areas. Each customer forwards traffic between their neighbors and an Internet gateway, thus providing high coverage for little upfront investment. However particularly during the early stages of deployment, seed nodes may be necessary to provide acceptable levels of coverage. This is particularly problematic since it is generally unknown in advance which households will subscribe. In this paper we present an optimization algorithm for the placement of seed nodes tinder uncertain user subscription. Experimentation with the algorithm is used to demonstrate the trade-off between coverage and infrastructure investment at various levels of consumer demand.
This paper describes the application of biologically-inspired algorithms and concepts to the design of wideband antenna arrays. In particular, we address two specific design problems. The first involves the design of ...
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ISBN:
(纸本)9780819466853
This paper describes the application of biologically-inspired algorithms and concepts to the design of wideband antenna arrays. In particular, we address two specific design problems. The first involves the design of a constrained-feed network for a Rotman-lens beamformer. We implemented two evolutionary optimization (EO) approaches, namely a simple genetic algorithm (SGA) and a competent genetic algorithm. We conducted simulations based on experimental data, which effectively demonstrate that the competent GA outperforms the SGA (i.e., finds a better design solution) as the objective function becomes less specific and more "general." The second design problem involves the implementation of polyomino-shaped subarrays for sidelobe suppression of large, wideband planar arrays. We use a modified screen-saver code to generate random polyomino filings. A separate code assigns array values to each element of the tiling (i.e., amplitude, phase, time delay, etc.) and computes the corresponding far-field radiation pattern. In order to conduct a statistical analysis of pattern characteristics vs. tiling geometry, we needed a way to measure the "similarity" between two arbitrary filings to ensure that our sampling of the tiling space was somewhat uniformly distributed We ultimately borrowed a concept from neural network theory, which we refer to as the "dot-product metric," to effectively categorize filings based on their degree of similarity.
The problems related to practical realization (as a computer program) of difference schemes of the solution of diffusion equations that describe pollutants transport in the river water are considered in this paper. In...
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The problems related to practical realization (as a computer program) of difference schemes of the solution of diffusion equations that describe pollutants transport in the river water are considered in this paper. In particular, the problems of optimum choosing of the algorithm parameters on which depend the accuracy, the time and the possibility of practical realization of the equation solution are considered. The demand to reduce as much as possible the time and the errors of calculations, and also the simplicity of the functions of certain classes used in mathematical models and their maximum accordance to real physical conditions are considered as criteria of optimality. (c) 2006 Elsevier Inc. All rights reserved.
An optimization strategy for high speed machining of hardened die/mold steel based on machining feature analysis was studied. It is a further extension of the previously presented study on the thermal mechanism of end...
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An optimization strategy for high speed machining of hardened die/mold steel based on machining feature analysis was studied. It is a further extension of the previously presented study on the thermal mechanism of end milling and constant cutting force control. An objective function concerning machining cost and associated optimization algorithm based on machining time and cutting length calculation was proposed. Constraints to satisfy specific machining strategies when high speed machining the hardened die/mold steel, trochoid tool path pattern in slot end milling to avoid over-heat and feed rate adaptation to avoid over-load, were also discussed. As a case study, the tool selection problem when machining a die part with multiple machining features was investigated.
A new artificial immune algorithm （AIA） simulating the biological immune network system with selfadjustment function is proposed in this paper. AIA is based on the modified immune network model in which two methods ...
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A new artificial immune algorithm （AIA） simulating the biological immune network system with selfadjustment function is proposed in this paper. AIA is based on the modified immune network model in which two methods of affinity measure evaluated are used, controlling the antibody diversity and the speed of convergence separately. The model proposed focuses on a systemic view of the immune system and takes into account cell-cell interactions denoted by antibody affinity. The antibody concentration defined in the immune network model is responsible directly for its activity in the immune system. The model introduces not only a term describing the network dynamics, but also proposes an independent term to simulate the dynamics of the antigen population. The antibodies＇ evolutionary processes are controlled in the algorithms by utilizing the basic properties of the immune network. Computational amount and effect is a pair of contradictions. In terms of this problem, the AIA regulating the parameters easily attains a compromise between them. At the same time, AIA can prevent premature convergence at the cost of a heavy computational amount （the iterative times）. Simulation illustrates that AIA is adapted to solve optimization problems, emphasizing muhimodal optimization.
Topology optimization method is a novel design method for MEMS actuators. In this paper, a multi-objective design method is introduced into topology optimization for MEMS actuators. Some important factors for multi-ob...
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ISBN:
(纸本)9781424401390
Topology optimization method is a novel design method for MEMS actuators. In this paper, a multi-objective design method is introduced into topology optimization for MEMS actuators. Some important factors for multi-objective design of MEMS actuators are deeply researched. A multi-objective topology optimization method based on minimal structural compliance and maximal structural output displacement of MEMS actuators is proposed and the corresponding governing equation for topology optimization is established. A sensitivity analysis of adjoint method is proposed to analyze topology optimization design of multi-objective MEMS actuators. Meanwhile, GCMMA (globally convergent version of the method of moving asymptotes) algorithm is used in optimization. Two numerical examples of MEMS actuators verified the effectiveness of above theory and algorithm.
To have efficient data mining systems, we need powerful algorithms to extract and mine the data. In the case of genomes data mining system, the algorithms search for genomes/proteins that share similar properties. Pro...
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To have efficient data mining systems, we need powerful algorithms to extract and mine the data. In the case of genomes data mining system, the algorithms search for genomes/proteins that share similar properties. Proteins that have a significant biological relationship to one another often share only isolated regions of sequence similarity. When identifying relationships of this nature, the ability to find local regions of optimal similarity is advantageous over global alignments that optimize the overall alignment of two entire sequences. The paper describes a new method for genome sequence comparison. This algorithm can be used in a genomes data mining system. It provides a good theoretical improvement in accuracy with a modest sacrifice in speed as compared to the most commonly used alternatives. The method is based on the popular progressive approach, the dot plot method, but avoids the most serious pitfalls caused by the greedy nature of this technique. The new approach pre-processes a data set of all pair-wise alignments between the sequences. This provides a library of alignment information that can be used to guide the comparison. The algorithm is based on the similar segment method, i.e. having n similar identities in window of size L. The paper presents some results about the termination and correctness of the algorithm and how to include this algorithm into other comparison algorithms. The paper introduces the mechanism to create random sequences. These data will be our main benchmarks for comparing our algorithms. (c) 2005 Elsevier Ltd. All rights reserved.
In Taiwan, due to its relatively low development cost, groundwater has been the main source of water supply for most aquacultural industry in costal areas. The overdraft of groundwater has caused serious land-subsiden...
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In Taiwan, due to its relatively low development cost, groundwater has been the main source of water supply for most aquacultural industry in costal areas. The overdraft of groundwater has caused serious land-subsidence in many parts of Taiwan. In addition to providing enough surface water for aquaculture freshwater demand, revising the aquaculture structure is one approach to reduce the reliance on fresh groundwater. Due to the most serious land-subsidence in Tachen Village, Changhua County, Taiwan, which may be caused by overusing groundwater for mainly raising freshwater clams, alternative techniques, such as changing the method of water use or revising the kinds of fish with less freshwater demands and higher gross profits, were studied in the study to reduce the dependence on fresh groundwater. The fuzzy multi-objective function comprising three single-objectives, viz. reducing saltwater demand, reducing freshwater demand, and increasing the total fisheries gross profit, was coupled with a global optimization algorithm to find suitable aquaculture scenarios in the study area. Analytical results can be provided to the fisheries authorities as references for revising the aquaculture structure.
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