REVERSE DESIGN APPROACH FOR MECHANISM TRAJECTORY BASED ON CODE-CHAINS MATCHING

Aiming at the problem of reverse-design of mechanism, a method based on the matching of trajectory code-chains is presented. The motion trajectory of mechanism is described with code-chain, which is normalized to simplify the operation of geometric transformation. The geometric transforma-tion formulas of scale, mirror and rotation for trajectory code-chain are defined, and the reverse de-sign for mechanism trajectory is realized through the analysis and solution of similarity matching between the desired trajectory and the predefined trajectory. The algorithm program and prototype system of reverse design for mechanism trajectory are developed. Application samples show that the method can break the restriction of trajectory patterns in matching, meet the demand of partial match-ing, and overcome the influence of geometric transformation of trajectory on the reverse design for mechanism.

BIMATCHING DESIGNS

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REQUIREMENTS AND DESIGN METHOD FOR MATCHING AIRCRAFT GUNS WITH THEIR SUPPORTING STRUCTURE

In aircraft structural dynamic design the matching of guns with their supportingstructure is one of the most important tasks on which hinges the success or failure of thestructural design.The design curves for matching guns with their supporting structure can be obtained fromresponse calculations of the plate-spring system supporting the gun on the ground,the modelstructure tested on the ground and the actual structure.A set of matching curves is given forengineering application.Then,the matching design can be accomplished by means of impactload spectrograms so as to perform an optimal structural design and to make further improvementson dynamic design program.

Structural optimization design of semi-rigid base asphalt pavement using modulus matching criterion and multi-indicator range analysis

Damage to semi-rigid base asphalt pavement is related to improper matching of the pavement structure moduli.This study mainly focused on the modulus matching of structural layers and the development of a pavement structure optimization method.First,the modulus loss of existing pavement structures was analysed,and a three-dimensional finite element model was established based on the existing pavement.Second,the influence of the modulus of each structural layer on the mechanical response indicators and fatigue life was analysed.Based on the results,a pavement structure design method using the smoothness of the stress-strain curve as the modulus matching criterion of the structural layers was proposed.And it was found that a strain convex point was present and that the stress mutation between the structural layers was significant when the modulus matching of the pavement structure was reasonable.Further,the evaluation indicators were divided into two groups,namely,mechanical indicators and fatigue life indicators.And it was proposed an optimized pavement structure design method based on modulus matching and multi-indicator range analysis.Finally,the optimal modulus combination of pavement structure was determined by this method.The research systematically studied the influence of the modulus of each structural layer on the mechanical response and fatigue life of the pavement,and proposed the concept and specific executive criteria of modulus matching for the first time.Meanwhile,it also provided an effective optimization method for pavement structure design.

Error Searching System with Keyword Extraction and Keyword Fuzzy Matching

This paper has proposed an error searching method to search the solutions of errors that occurred in the unified commanding platform mix-deployed software (UCPMD). Because those errors belong to different stages or may be happened in different services, applications, IP ports, system software, or different versions of software, and those errors are also can be classified into different types. It is necessary to locate accurate reason that cause an error as well as find out its solution. The proposed error searching system applies Chinese keyword extraction and Chinese fuzzy matching between keywords, which considers the processed keywords as the index to find out the solutions of errors. Besides, the error searching system had made correspondence among errors, reasons, and solutions, and put them to different categories in terms of their characteristics, such that it is easy to manage, search, and use. Among others, we have added specialized thesaurus as the index of keywords, which enriches and completes the searching results. Because of the proposed error searching system evolves keyword extraction and keyword fuzzy matching technologies;it is more accurate to find out user-interested solutions.

Cumulative logit model in the analysis of endometrial cancer under a matched pair case-control design

Background: Binary as well as polytomous logistic models are widely used for estimating odds ratios when the exposure of prime interest assumes unordered multiple levels under matched pairs case-control design. In our previous studies, we have shown that the use of a polytomous logistic model for estimating cumulative odds ratios when the outcome (response) variable is ordinal (in addition to being polytomous) under matched pairs case-control design. The cumulative odds ratios were estimated based on separate fitting of the model at each of the cutpoint level as compared to less than equal to that level. In this paper we propose an alternative method of estimating the cumulative odds ratios and reanalyze the Los Angeles Endometrial Cancer data in the context of dose levels of conjugated oestrogen exposure and development of endometrial cancer under the matched pair case-control design. Methods: In the present study, the cumulative logit model is fitted using a single multinomial logit model for the data. For this, the full maximum likelihood estimation procedure is adopted. A test for equality of the cumulative odds ratios across the exposure levels is proposed. Results: The analysis revealed that there is a strong evidence of risk for developing endometrial cancer due to oestrogen exposure above each of the three dose level as compared to less than equal to that level. The estimated values at the three cutpoint levels were found to be 6.17, 3.60 and 5.16 respectively. Conclusions: The odds of developing endometrial cancer are very high for the users of any amount of oestrogen, even if it is the least dose, as compared to the non-users.

Shape design of the reinforcement for bending load-carrying capacity of under-matched butt joint under four-point bending load

To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry

Solving the Maximum Matching Problem on Bipartite Star123-Free Graphs in Linear Time

The bipartite Star123-free graphs were introduced by V. Lozin in [1] to generalize some already known classes of bipartite graphs. In this paper, we extend to bipartite Star123-free graphs a linear time algorithm of J. L. Fouquet, V. Giakoumakis and J. M. Vanherpe for finding a maximum matching in bipartite Star123, P7-free graphs presented in [2]. Our algorithm is a solution of Lozin’s conjecture.

Component Matching Based on Low Bypass Ratio Mixed Exhaust Turbofan Engine

In order to study component matching which exists in off-design situation at the initial design stage of turbine engine,by establishing performance analysis model of low bypass ratio mixed flow turbofan engine and components characteristic data,and by applying Newton-Raphson method to solve the nonlinear equations of offdesign points in flying envelop,the factors which affect matching between engine components are studied.The results show that low pressure turbine(LPT)must not operate in a critical condition,and the partial derivative(slope)of pressure ratio to similitude mass flow ratio of working point in LPT characteristic map affects the stability of engine.The smaller the slope is,the more stable the engine is.In addition,the engine is more stable when the fan characteristic map is steep.

数学对服装色彩的匹配与调和的影响

在服装设计中,色彩的选择主要依靠设计师的直觉与经验,带有一定的主观性与不确定性,但在科学技术的发展以及多学科交叉领域的不断发展下,运用数学可以在服装设计中进行合理的颜色匹配与调和,可以有效提升产品的品质。因此,针对数学对服装色彩的匹配与调和的影响展开探究,以期为服装设计师提供理论参考。

数智时代科技成果供需对接机制

为探究我国数智时代科技成果供需对接影响因素和机制作用,梳理我国科技成果供需对接模式及演变历程,构建科技成果供需对接影响因素概念模型,运用扎根理论和文献分析方法归纳出供方、需方、平台、政策、资金和技术因素等影响因素,运用DEMATEL方法分析影响因素之间的影响度。基于分析结果,提出我国科技成果供需对接机制为从应需引供模式转变为掘需育供模式,从上下游关系转变为共同体关系,从局域平台转变为广域平台,从信息化转变为智慧化,从单点服务转变为全链条服务,从技术发展转变为多要素融合发展。

基于MATLAB的射频微波电路阻抗匹配教学软件设计

阻抗匹配是射频微波电路设计的重要内容,然而阻抗匹配方案众多且计算繁杂,原有教学大多以中心频率匹配的数学公式推导为主,学生难以理解不同匹配方案在较宽频带内的整体性能表现。为此,基于MATLAB App Designer开发了一款阻抗匹配设计和分析软件,可实现包含集总参数电感电容和分布参数微带线在内的多种宽带、窄带匹配方案,通过输入技术指标要求便可直接得到对应的电路结构、元件值以及S参数曲线。该软件操作简单、实时性强,可快速比较多种匹配方案的性能,加强学生对阻抗匹配的深层次理解,极大地辅助了教学和科研。

超声波无线电能传输的声电通道设计

为了解决磁耦合方式无线电能传输技术在金属障碍环境下因涡流效应而效率低下问题,该文开展了金属障碍环境下超声无线电能传输技术研究。首先从声学的角度分析能量传输通道参数对声波透射系数的影响规律,并指导完成通道参数的配置。然后,采用同时共轭阻抗匹配技术完成通道输入端口与输出端口的阻抗匹配网络设计,并通过实验验证阻抗匹配网络的有效性。测试结果表明,该文所设计的超声波无线电能传输系统透11 mm厚304不锈钢障碍的理论最佳传输效率为68%,进行同时共轭阻抗匹配后通道的实际能量传输效率为56.25%,传输功率达51.53 W。该研究所达到的能量传输效率和传输功率均能满足绝大部分使用需求。该技术在军事、航天等领域具有较好的应用前景。

基于连续变焦的大口径长焦距的探测成像一体化光学系统设计

为实现空间目标的探测与精确识别,设计了一种基于连续变焦结构兼顾大孔径和长焦距的探测成像一体化光学系统,实现了短焦大视场探测,长焦小视场成像的目的。系统采用里奇-克列基昂(RC)结构加校正镜与变焦结构通过光瞳匹配进行结合的方式,使用两片反射镜压缩光路,系统工作于450~850 nm的光谱范围内,焦距为700~3500 mm;探测端焦距为700 mm,F数为2.5,视场角为0.5°×0.5°;成像端焦距为1400~3500 mm,F数为5~12.5,视场角为0.18°×0.18°。该系统具有探测能力强、成像质量佳、系统总长短、变焦凸轮曲线升角小等优点。

一种幅相联合调制雷达波形设计与处理方法

随着脉内特征识别、信号分选等电子侦察技术的发展,雷达波形设计正面临严峻的挑战。幅度调制作为一种新型脉冲调制方式,能够增加信号时域的复杂性,提升波形的反识别能力。本文提出一种幅相联合编码雷达波形,通过幅度相位联合调制提升雷达波形的复杂度,具有良好的反侦察潜力;利用幅度上的稀疏采样特点,提出匹配滤波与压缩感知相结合的回波信号处理方法处理此信号,有效提升低信噪比条件下的检测概率。最后通过仿真实验证明了所提幅相联合调制雷达波形设计与处理方法的有效性。

产品匹配信息揭露与产品线设计

探究顾客对产品匹配信息不确定下,垄断企业的信息揭露策略与产品线的质量设计.首先分析企业对产品匹配信息的揭露策略如何影响产品线的质量设计,进而探讨企业在哪些情形下会揭露产品的匹配度信息.为探究这些研究问题,构建了一个垄断企业向高估值顾客和低估值顾客销售高端产品和低端产品的模型.研究发现,企业应根据产品匹配度信息的披露策略对应地调整产品线的质量设计.具体而言,相较于不揭露产品信息,如果只揭露高(低)端产品的匹配度信息,低端产品的质量设计应向上提升(向下扭曲),高端与低端产品的质量设计差异减少(增加);如果同时揭露高端和低端产品的匹配度信息,低端产品质量设计的扭曲程度取决于不同类型顾客认为产品合适的概率.另外,企业如何选择产品匹配度信息的揭露策略取决于市场特征.当低估值顾客对产品水平维度的认知价值较高时,企业倾向于只揭露低端产品的匹配度信息.本研究为广大电商的信息披露与产品线设计的联合决策提供重要的管理学启示.

基于Ansoft Designer的射频功放电路阻抗匹配优化设计

针对工作频率为433MHz 的射频功率放大电路中的阻抗匹配问题,提出了基于 EDA 软件——Ansoft designer 的阻抗匹配优化设计方法。运用 Ansoft designer 对射频功放电路进行了阻抗匹配优化设计,并对电路进行了仿真分析。仿真结果表明射频功放电路的增益得到了明显的提高,反射系数得到了显著的改善,达到了阻抗匹配优化设计的目的。

基于改进飞蛾扑火优化算法的船机桨匹配设计研究

基于改进飞蛾扑火优化(Improved Moth-Flame Optimization,IMFO)算法,以两艘现有船舶为计算实例,展开了综合考虑螺旋桨推进效率、空泡性能和桨叶强度的船机桨匹配工作。以遗传算法(Genetic Algorithm,GA)和原始飞蛾扑火优化(Moth-Flame Optimization,MFO)算法为对比算法,分析了IMFO辅助船机桨匹配工作时的性能。数值实验的结果表明,在解决船机桨匹配问题时,IMFO算法的收敛时间相比GA算法在两个算例中分别缩短了44.24%和54.14%,相比MFO算法分别缩短了23.9%和23.12%。此外,在求解精度方面,在计算示例1中,IMFO算法相比GA算法和MFO算法略有提升;而在计算示例2中,IMFO算法相比GA算法提高了3.66%,较MFO算法提高了0.98%。最后,通过对两个算例的可行解空间进行可视化表示,进一步讨论了IMFO算法的求解性能。上述结果对比证明了IMFO算法具备强大的全局搜索能力,在解决船机桨匹配问题时具有良好的竞争力和鲁棒性。

配对设计中风险差的置信区间构造

风险差在配对设计中常用来对比某种疾病治疗前后或某种政策措施实施前后的有效性.文中针对风险差(Risk Difference)在配对设计中的置信区间估计问题,利用Delta法,改进Wald法,反双曲正切变换法,似然比检验法,鞍点逼近法方法进行置信区间构造,并通过Monte Carlo模拟计算区间覆盖率和区间长度,以比较这5种方法的表现性能.结果显示:不同方法的区间表现均不相同.其中鞍点逼近法明显优于其他4种方法;改进Wald法的表现仅次于鞍点逼近法,且随着样本量的增大,改进Wald法和反双曲正切变换法的性能差距逐渐减小;最后通过一个实例来验证这5种区间估计方法.