Computer Search Techniques Research Articles

Efficient Multi-Dimensional Mapping Using QAM Constellations for BICM-ID

Bit-interleaved coded modulation with iterative decoding (BICM-ID) offers improved error performance over additive white Gaussian noise and fading channels if it uses a wisely designed signal mapping. Furthermore, error performance of BICM-ID can be significantly improved by employing multi-dimensional (MD) modulation. However, suitable MD mappings are obtained by computer search techniques, except for MD modulations that use small constellations, e.g., binary phase shift keying, quadrature phase shift keying, and 8-ary phase shift keying as basic modulation. The alphabet size of MD modulations increases exponentially as the order of the basic modulation increases and computer searching becomes intractable. In this paper, we propose a systematic mapping method for MD modulations. The innovation of our proposed method is that it generates MD mappings using 16- and 64-quadrature amplitude modulation very efficiently. The presented numerical results show that the proposed method improves the bit error rate of BICM-ID.

Bringing Bertillon Back: The Preservation and Research Application of Bertillon Materials in Museums, Archives, and Historical Societies

Bertillon cards are underutilized resources, often regarded as the remnants of an antiquated nineteenth century police identification system. Through the application of computer search techniques, data manipulation, and outreach, not only can institutions provide their patrons access to this unique information, these collections can in turn help revitalize their respective repositories. This article begins with a brief history of Alphonse Bertillon and his system (Bertillonage). The remainder describes the results from a survey submitted to eleven institutions that hold Bertillon materials and compares their preservation, storage, and accessibility; compiles common research subjects; and examines the added value of technology to these documents.

Combinatorial Testing: Principles and Methods

PDF HTML阅读 XML下载 导出引用 引用提醒 组合测试:原理与方法 DOI: 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: Supported by the National Natural Science Foundation of China under Grant Nos.60673044, 60633010 (国家自然科学基金) Combinatorial Testing: Principles and Methods Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:组合测试能够在保证错误检出率的前提下采用较少的测试用例测试系统.但是,组合测试用例集的构造问题的复杂度是NP完全的.组合测试方法的有效性和复杂性吸引了组合数学领域和软件工程领域的学者们对其进行深入的研究.总结了近年来在组合测试方面的研究进展,主要内容包括:组合测试准则的研究、组合测试生成问题与其他NP完全问题的联系、组合测试用例的数学构造方法、采用计算机搜索的组合测试生成方法以及基于组合测试的错误定位技术. Abstract:Combinatorial testing can use a small number of test cases to test systems while preserving fault detection ability. However, the complexity of test case generation problem for combinatorial testing is NP-complete. The efficiency and complexity of this testing method have attracted many researchers from the area of combinatorics and software engineering. This paper summarizes the research works on this topic in recent years. They include: various combinatorial test criteria, the relations between the test generation problem and other NP-complete problems, the mathematical methods for constructing test cases, the computer search techniques for test generation and fault localization techniques based on combinatorial testing. 参考文献 相似文献 引证文献

The Shortest Game of Chinese Checkers and Related Problems

AbstractIn 1979, David Fabian found a complete game of two-person Chinese Checkers in 30 moves (15 by each player). This solution requires that the two players cooperate to generate a win as quickly as possible for one of them. We show, using computational search techniques, that no shorter game is possible. We also consider a solitaire version of Chinese Checkers where one player attempts to move her pieces across the board in as few moves as possible. In 1971, Octave Levenspiel found a solution in 27 moves; we demonstrate that no shorter solution exists. To show optimality, we employ a variant of A* search, as well as bidirectional search.

Automated osteoporosis risk assessment by dentists: A new pathway to diagnosis

General dental practitioners use a vast amount of panoramic radiography in their routine clinical work, but valuable information about patients' osteoporotic status is not collected. There are many reasons for this, but one of the prime reasons must be the disruption involved in clinical routine with lengthy manual radiographic assessment. We have developed computer software, based on active shape modeling that will automatically detect the mandibular cortex on panoramic radiographs, and then measure its width. Automatic or semi-automatic measurement of the cortical width will indicate the osteoporotic risk of the patient. The aim of our work was to assess the computer search technique's ability to measure the mandibular cortical width and to assess its potential for detection of osteoporosis of the hip, spine and femoral neck. Mandibular cortical width was measured using the manually initialized (semi-automatic) method and, when assessed for diagnosing osteoporosis at one of the three measurement sites, gave an area under the ROC curve (A(z))=0.816 (95% CI=0.784 to 0.845) and for the automatically initialized searches, A(z)=0.759 (95% CI=0.724 to 0.791). The difference between areas=0.057 (95% Confidence interval=0.025 to 0.089), p<0.0001. For diagnosing osteoporosis at the femoral neck, mandibular cortical width derived from the manually initialized fit gave an area under the ROC curve (A(z))=0.835 (95% CI=0.805 to 0.863) and for the automatically initialized searches A(z)=0.805 (95% CI=0.773 to 0.835). The difference in A(z) values between active shape modeling search methods=0.030 (95% CI=-0.010 to 0.070), and this was not significant, p=0.138. We concluded that measurement of mandibular cortical width using active shape modeling is capable of diagnosing skeletal osteoporosis with good diagnostic ability and repeatability.

Neural response profile design: Reducing epileptogenic activity by modifying neuron responses to synchronized input using novel potassium channels obtained by parameter search optimization

Neurons obtain their dynamical electrical characteristics by a set of ion channels. These properties may not only affect the function of the neuron and the local network it forms part of, but it may also eventually affect behavior. We were interested to study whether epileptogenic activity could be reduced by adding an ion channel. In this work, we used computational search techniques to optimize ion channel properties for the goal of modifying neural response characteristics. Our results show that this type of parameter search is possible and reasonably efficient. Successful searches were generated using the direct method PRAXIS, and by systematic searches in low-dimensional sub-spaces. We also report on unsuccessful searches using a simplex-type method, a gradient-based method, and attempts to reduce goal function evaluation time. Importantly, using this search strategy, our study has shown that it is possible to change a neuron's characteristics selectively with regard to response to degree of synchronicity in synaptic input.

Hybrid algorithm for determination of dimensional accuracy of automobile front chassis module using laser measurement data

Measurement data obtained from an inspection system need to be analyzed using appropriate algorithms to estimate dimensional errors and to obtain reliable inspection results. This paper proposes a hybrid algorithm based on computational geometric and simplex search techniques to determine the dimensional errors in manufactured components. The proposed hybrid algorithm works in two stages. First, it establishes a measurement coordinate system using basic computational geometric techniques such as convex hull and Voronoi diagrams. Next, the proposed hybrid algorithm modifies the initial measurement coordinate system by the simplex search technique. This helps to reduce the error between design and measurement coordinate systems. After determining the measurement coordinate system, the dimensional errors in the inspected components are estimated to verify the conformity of manufactured components to the design and tolerance specifications. In the present work, the proposed algorithm has been successfully implemented for inspecting the automobile chassis module. The required measurement data are obtained from a laser vision system developed for inspecting the automobile front chassis module that comprises the subframe and lower arm assembly. The measurement data from the subframe are used for establishing the measurement coordinate system. The dimensional errors in the lower arm are determined using the measurement coordinate system, established earlier. The details of the algorithm and the results obtained for the sample data are presented in this paper. The dimensional error values obtained using the proposed algorithms are compared to those obtained using the least-squares method.

Design optimization of a switched reluctance motor by electromagnetic and thermal finite-element analysis

This paper presents the design optimization of a switched reluctance motor (SRM) by using a combination of two-dimensional electromagnetic and thermal finite-element analysis, three-dimensional correction factors, and computer search techniques. To achieve the required performance within a specified space envelope, the physical dimensions of the SRM were optimized, subject to a minimal total material cost including motor and power electronics. A prototype SRM was built and its test results validated the design methodology.

The A-Design approach to managing automated design synthesis

This paper presents an approach to managing the complexities of design synthesis techniques. Often computational approaches model design as a search process or as an optimization problem. The nature of such techniques, however, does not allow the user to interact with the search process once it has begun. Furthermore, traditional computational search lacks the ability to learn from experience. While computational search techniques have the ability to search many design alternatives quickly, the human engineer can often arrive at a more elegant and robust solution by applying heuristics learned from past experiences. The method introduced here improves the capabilities of design synthesis methods by allowing for user input and by making decisions based on previous experience. In studying past candidate designs the process learns to be more effective in searching for solutions. Results show how such a technique improves the quality of designs and efficiency of an existing search process.

Body image in boys: a review of the literature.

Both scientific research and popular attention have begun to focus on the neglected issue of body image in boys. We reviewed the findings of this emerging literature. Using computer and manual search techniques, we located 17 studies that assessed body image attitudes in boys under age 18. We located 17 studies, most performed within the last 10 years. Eight studies used exclusively questionnaires or interviews; the rest also used figure drawings from which the subjects could choose specific images in answer to questions. Although boys generally displayed less overall body concern than girls, many boys of all ages reported dissatisfaction with their bodies, often associated with reduced self-esteem. Whereas girls typically wanted to be thinner, boys frequently wanted to be bigger. However, most studies failed to distinguish between "bigness" due to increased muscle and that due to fat. Body image dissatisfaction in boys is common and often associated with distress. To better assess this phenomenon, future studies should take care to separate the indices of muscle and fat.

On the equation $\sum_{p|N}\frac1p+\frac1N = 1$, pseudoperfect numbers, and perfectly weighted graphs

We present all solutions to the equation Σ p|N 1/p + 1/N = 1 with at most eight primes, improve the bound on the nonsolvability of the Erdos-Moser equation Σ m-1 j=1 j n = m n , and discuss the computational search techniques used to generate examples of perfectly weighted graphs.

Construction of uniform-balanced cross-over designs for any odd number of treatments.

Cross-over designs balanced for simple carry-over effects are commonly applied in clinical studies for the comparison of treatments for chronic conditions such as hypertension or asthma. Uniform-balanced cross-over designs have the desirable property that the treatment sequences are arranged so that, in the full design, each treatment is followed by every other treatment equally often. Such designs for an even number of treatments and the same number of sequences and periods are readily constructed using suitable cyclic Latin squares. For an odd number of treatments, pairs of squares may be combined to give uniform-balanced designs. Recently, computer search techniques have been used to find nearly-balanced Latin squares which may be combined in pairs or in sets of three to produce designs with the overall properties of uniformity and balance. In this paper, simple generating formulae are described which will give, for any odd number of treatments t > 3, uniform-balanced cross-over designs with p = t periods and n = kt treatment sequences for any k > or = 2. Tables of cross-over designs obtained from these simple formulae are presented for t < or = 15.

Computer-optimised smooth-torque current waveforms for switched-reluctance motors

The paper discusses the design of current waveforms for switched-reluctance motors, which give rise to a constant (ripple-free) torque. The waveforms are optimised by computer search techniques, to give the lowest RMS current per phase consistent with producing smooth torque. Furthermore, the waveforms are constrained to be within the converter's VA rating. Current waveforms and the associated voltage waveforms are given for an example motor over a wide speed range. At low speeds it is demonstrated that the waveforms increase the thermally limited output of the drive compared with 'conventional' low-speed current waveforms, in addition to providing smooth torque. However, they give less output than waveforms optimised to give the most, thermally limited, mean torque irrespective of torque ripple.

Analysis and design optimisation of magnetic couplings using 3D finite element modelling

Accurate analysis and optimal design of magnetic couplings are essential to minimise the volume of magnet material and to avoid the construction and testing of multiple models to achieve a given design goal. This paper compares the results of using 3D and 2D finite element analysis (FEA) and analytical methods with experiment. It is found that 3D analysis provides superior agreement. Design of FEA meshes in 3D and 2D are discussed. A method of correcting 2D FEA for end leakage is presented. Optimisation using 3D FEA, combined with computer search techniques, is demonstrated.

Toward a more efficient handling of conformational flexibility in computer-assisted modelling of drug molecules

Several computational search techniques are described to map the conformation space of flexible organic molecules. A vast multiplicity of geometries is produced that has to be minimized according to a particular energy function. Comparative studies on a nine-membered cyclic lactam are taken as an example. They show that thoroughly tailored search conditions can obtain roughly comparable search efficiencies. Out of the vast multiplicity of geometrically possible and computationally accessible conformers, only a limited number will be of relevance for the problem under consideration. In ligand design for drug discovery, a relative energy ranking determined on isolated conformers is only of limited use for the selection of biologically relevant conformers. This is due to an unsatisfactory transferability of energy scales between different energy functions and the strong modulation of conformational energies of isolated molecules once exposed to a structured molecular environment. A knowledge-based approach, using torsionangle libraries as retrieved for common fragments in small-molecule crystal structures, allows one to map more efficiently the biologically relevant part of conformation space. The relevance of these libraries for the conditions at the binding pocket of a protein is evidenced by experimental data. Sets of well-distributed conformers can be used to compare different drug molecules binding to common targets. Such comparisons reveal new modes of structural superposition of the molecules and consideration of their physicochemical properties leads to interesting pharmacophore hypotheses. They indicate possible binding geometries at the recognition site of a protein and highlight the structural similarities and differences that correlate with changes in the biological properties. Comparisons of GP IIb/IIIa receptor antagonists and of thrombin inhibitors are discussed.

New very high rate punctured convolutional codes

New very high rate punctured convolutional codes suitable for Viterbi decoding are presented. These codes extend recent results on high rate convolutional codes by employing an efficient computer search technique and are optimum in that they minimise the residual bit error rate over all puncturing patterns given a particular basis code. Tables of new codes of rate (n–1)/n are given for n = 9, 10, 11 and 12.

Ligament length relationships in the moving knee.

This article presents an investigation of potential ligament attachment sites for surgical reconstruction of the anterior and posterior cruciate ligaments as well as for the lateral extraarticular iliotibial band tenodesis. Our methodology was based on quantitative measurements of knee anatomy and motion in fresh cadavers, not on biomechanical modeling. Using computer search techniques, we located all the ligament insertion sites that were nearly isometric for motion of the intact knee.

Optimizing off-highway truck characteristics for minimum haulage cost

Critical equipment characteristics are isolated and analysed by traditional operations research techniques, using off-highway trucks as an archetype. A computer search technique has been developed, employing various production and cost analyses. With this model, the optimum combination of horsepower, capacity, velocity, and total cost can be found, minimizing haulage cost per ton. Horsepower is treated as the most important characteristic. An example of the program's use and interpretation of its results conclude the paper. The optimization is useful as an aid to off-highway truck selection, evaluation, and design. Model limitations are offered and advantages to its use are given.

A Multifactor Priority Rule for Jobshop Scheduling Using Computer Search

Abstract Priority rules are widely used in jobshop scheduling to determine the sequence in which jobs are to be processed. The research in this area has been directed at developing generally applicable priority rules. This paper presents a method for determining an effective priority rule specific to the jobshop scheduling problem to be solved. First, a generalized objective function is formulated which is the sum of costs of tardiness, carrying in-process inventory and machine idleness. Second, a multifactor priority rule is developed which is a weighted average of four factors used in simple priority rules. Third, a method is presented for using a computer search technique to determine the best weights to use in the priority rule. Finally, a computer simulation for testing this approach versus using other priority rules is described and the experimental results are reported.

Behavioral disorders in multiple sclerosis, temporal lobe epilepsy, and amyotrophic lateral sclerosis. An epidemiologic study.

Certain CNS diseases can produce specific behavioral abnormalities. We used a computer search technique to identify all inpatients at Strong Memorial Hospital, Rochester, NY, who had received diagnoses of multiple sclerosis (MS), temporal lobe epilepsy (TLE), and amyotrophic lateral sclerosis (ALS) between 1965 and 1978. We found 368 patients with MS, 402 patients with TLE, and 124 patients with ALS. These groups were matched against the Monroe County (New York) Psychiatric Register to determine patterns of behavioral pathology. Prevalence rates for psychiatric contact were not significantly different between MS and TLE (19.3% v 22.9%), but both were higher than the prevalence rate for ALS (4.8%). When behavioral patterns were assessed, patients with MS demonstrated a significantly higher rate of depressed affective disorders (61.97% of register matches) than patients with the other two diseases. Multiple sclerosis may present a neurologic model for mood disturbance.