查询词典 method of work

This thesis contributed to the comprehensive study of the Finite-Difference Time-Domain method and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies. The work includes mainly three parts: the study on the performance of PML absorbing boundary condition applied to pseudo low frequency electromagnetic problems; the validation of the FDTD method with PML absorbing boundary conditions and the corresponding computer software based on the numerical study of the electromagnetic field of an electric dipole antenna, and its application to the numerical computation of radiated electromagnetic fields in switched mode power supplies; the development of an improved alternating direction implicit finite-difference time-domain method.

在综合前人工作基础上，本文对时域有限差分法及其在开关电源辐射电磁场数值计算中的应用进行了系统的分析和研究，其核心内容包括：伪低频电磁场数值计算中PML吸收边界条件性能的研究；基于基准问题—电偶极子天线三维辐射电磁场，验证了本文构造的基于PML吸收边界条件的三维FDTD法及其计算软件，并应用于高频开关电源辐射电磁场的数值分析；提出了一种改进的交替方向隐格式时域有限差分法。

The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

Stability analysis of Sanjiaoping slope under diverse work condition indicates that the result of strength reduction method is approximate to classical limit equilibrium method. The shape and the position of sliding surface are similar. So, the suggested method is rational.

通过对三交坪边坡不同工况下的稳定性分析表明，强度折减所确定的边坡安全系数与传统极限平衡法所得的结果十分接近，滑面的形状及位置也极为相似，因此认为该方法是合理可行的。

At the same time, combining with the actual condition of delivery pipeline of our country and some prevalent leak detection and location methods, this paper raised a method, which is based on wavelet analysis and negative- pressure-wave to detect and locate the leakage. Jobs in the paper are as follows:As affected by gas density, pressure, specific heat and pipe material, the velocity of negative-pressure-wave improved depending on the energy conservation. At one time, taking the affection of velocity of gas flow, the location formula was modified in some degree.When locating the leaks with location formula, the iterative approach algorithm was adopted as a new method to increase the location accuracy level of system.Multi-scale decomposition and reconstruction of wavelet transform is utilized to filter the noise of negative-pressure-wave, which was brought by leakage. With the capacity to detect the signal singularity fast and accurately, wavelet transform was used to catch the break point of pressure signal. The work improved the accuracy of At in location formula, accordingly improved the location accuracy.Wavelet is a suitable tool for signal analysis. The distinct character is that the mother-wavelet is of optional. That means choosing different mother-wavelet will get different analysis result. So we studied how to choose mother-wavelet and its scale for signal singularity detection. The method is to choose a wavelet by regularities of the wavelet and the signal.Finally, a plan, which bases on SCADA system for inspection and detection of natural gas leakage, is proposed in the article.

其中，主要进行了以下几方面的工作：针对泄漏产生的负压波在管道中的传播速度受媒介的密度、压力、比热及材质等因素的影响，而非声波在空气中传播的速度，本文利用能量守恒原理，对其进行了修正；考虑到管内气体流速对压力波速的影响，对原始的负压波定位公式进行了一定程度的改进，并在利用定位公式进行泄漏点定位时采用逐步迭代逼近算法，提高了系统的定位精度；利用小波变换的多分辨率分解和重构技术，对采集到的管道发生泄漏时产生的负压波信号进行了降噪处理；并利用小波变换技术对信号奇异点的快速、准确的识别能力，对经上述消噪后的负压波信号进行了奇异点捕捉，精确捕捉的结果提高了定位公式中上下游站点采集到的负压波奇异点的时间差△t的精度，从而进一步提高了定位的精度；考虑到小波变换是一种基波可变的信号分析工具，也就是说，不同的小波基波对信号分析的结果将有很大差别，这势必影响最终的处理结果，因此，我们又对比分析了本课题中小波基及尺度的选择问题，依据规则性系数相似性原理对母小波的选择进行了探索性研究；最后，还提出了基于SCADA的泄漏检测与定位系统的软件开发构想及系统的嵌入方案。

The coordinate transformation and numerical integration was executed on the discretized tetrahedral elements based on which the 3-D MT vector-finite element method was implemented. A whole computation framework for 3-D vector-finite element method with unstructured mesh was given. Based on this some typical models were tested which has demonstrated that our algorithm could distinctively avoid problems caused by the fake solution and both the accuracy and efficiency were enhanced which made our algorithm has a bright future for further application.3. According to theory of Sobolev vector space and the discretization of Helmholtz space, the error estimate which was suitable for 3-D MT vector-finite element modeling was deduced by which the procedure of adaptive technique was guaranteed.4. Based on the fully unstructured tetrahedralization and optical strategy, the 3-D magnetotelluric h-adaptive vector-finite element method was presented through combining the error estimate. With this work, the accuracy and creditableness for 3-D MT complicatedly modeling was guaranteed.5. The 3-D magnetotelluric h-adaptive vector-finite element algorithm with unstructured mesh was implemented.

针对非结构化的四面体单元，采用坐标变换和数值积分方法，实现了MT三维矢量有限单元分析，建立起基于非结构化网格的三维MT矢量有限元计算流程，并对典型模型和国际标准电磁模型进行了数值模拟，结果对比和分析表明，基于非结构化网格的三维MT矢量有限元不仅消除了节点型有限元的伪解，而且具有很高的计算精度和速度，有广阔的应用前景。3、根据Sobolev函数的向量空间和Hemlholtz空间的分解，推导出基于残差的三维大地电磁矢量有限元后验误差估计公式，为三维大地电磁自适应矢量有限元数值模拟的实现奠定了基础。4、在完全非结构化四面体单元剖分及优化基础上，结合三维大地电磁矢量有限元后验误差估计公式，提出了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算策略，保证了对复杂大地电磁模型数值计算的精度和可靠性。5、实现了基于非结构化网格的三维大地电磁h-型自适应矢量有限元计算流程，对典型模型和国际标准电磁模型进行了数值模拟。

In this paper, we consider hyperbolic conservation laws, and the following work has been done to the finite volume method on unstructured meshes :In preface , we introduce the backupground of the oringe of the finite volume method, and point out the limitation of the finite difference methods and the finite element methods, and import the finite volume method.

本文主要考虑双曲型守恒律方程，对二维非结构三角形网格有限体积方法作了如下工作：介绍了有限体积方法的产生背景，指出了有限差分方法和有限元方法中的特点，对有限体积方法的产生和发展给出了比较详细的分析。

I from as follows 5 go to design teaching method, effort practice, brave reform, promote student of overall development:let the student is in the reality scenario experience and comprehension mathematics, development its space idea;encouragement student independence thinking, leading student independence investigate, cooperation exchanges;in the teaching process adoption of the method should make student thoroughly from each aspect comprehension, encouragement work°out problem strategy of diversification;in the teaching process should availably usage indirect method;in the teaching process should progressively the development student's mathematics speech.

我从如下五个方面去设计教法，努力实践，大胆革新，促进学生的全面发展：让学生在现实情境中体验和理解数学，发展其空间观念；鼓励学生独立思考，引导学生自主探索，合作交流；教学过程中采用的方法应使学生深入地从各个方面理解，鼓励解决问题策略的多样化；教学过程中应有效地使用间接法；教学过程中应积极地发展学生的数学言语。

A new knowledge acquirement way is presented based on the reliability data of product, then the fuzzy semantic net which consists of FEPM and fuzzy fault tree is regard as fault knowledge representation. The formalization of the fuzzy semantic net is described, and the relative concepts and relations are summarized. A stereo-knowledge representation which consisted of FFTF, rule and fuzzy neural network which make up of the shallow knowledge of the product is presented. The integrated fault diagnosis method based on the stereo-knowledge representation is suggested. The method is as follows. The fuzzy search inference is carried out on FFTF firstly. If the node being diagnosing can be decided if it failed or not in the fuzzy search inference, the rule inference to the node is carried out with the rules which being in symptom-fault way. An equivalent method, pattern recognization inference using fuzzy neural network, can fulfill the same work.

提出了以FFTF模糊语义网络为主、基于浅知识的产生式规则、模糊神经网络为辅的产品故障知识的立体知识表示方式，并提出了基于该多种知识表示的综合性故障诊断方法，即：首先对故障产品进行基于FFTF模糊语义网络的模糊搜索推理，如果在模糊搜索推理过程中不能确定当前诊断节点故障与否，则对当前诊断节点进行基于征兆-故障形式的验证式规则推理或者对包含该诊断节点的部件／子系统进行基于模糊神经网络的模式识别推理，如果在完成或者不再进行基于模糊语义网络的故障推理，仍然不能诊断出故障节点，则对基于模糊语义网络诊断过程中形成的故障诊断子图进行神经网络推理。

On the basis of objectives, principle, contents, method and summary of strategy experience in social work service adolescent people in the community of Shanghai, the writer puts forward the concept of the type of amalgamated social work service with adolescent in community, the process of formation of which reflects the characters of nativism in social work practice in China.

本人在对上海社区青少年服务目标、服务原则、服务内容、服务方法和策略经验研究的基础上提出"融和型"社区青少年社会工作服务模式的概念。"融和型"社区青少年社会工作服务模式的形成，反映了中国社会工作实践的本土性特点。

We study the properties of $BR_0$-algebra and the total complication triple I method on complete $BR_0$-algebra, and we apply the results to $R_0$-Unite interval $\overline{W}$. Not only we have simplified the proof of the results of $R_0$-type triple I method on $R_0$-Unite interval $\overline{W}$, but also we make the proof to combine with the formal deductive system for fuzzy propositional calculus. This work also explains that the $R_0$-type triple I method is a matching fuzzy inference with $B{\cal L}^*$ system.

研究了基础$BR_0$-代数的性质和基于完备基础$BR_0$-代数的全蕴涵三I算法，对一般蕴涵算子给出了三I算法解存在的一个充分条件，并将结果应用于$R_0$-单位区间$\overline{W}$，不但极大的简化了$R_0$-单位区间$\overline{W}$的$R_0$-型$\alpha$-三I算法结果的证明，而且使其证明过程与相应的模糊命题演算系统结合起来，说明了$R_0$-型三I算法是与$B{\cal L}^*$系统相匹配的模糊推理方法。

It has been put forward that there exists single Ball point and double Ball points on the symmetrical connecting-rod curves of equilateral mechanisms.

从鲍尔点的形成原理出发，分析对称连杆曲线上鲍尔点的产生条件，提出等边机构的对称连杆曲线上有单鲍尔点和双鲍尔点。

The factory affiliated to the Group primarily manufactures multiple-purpose pincers, baking kits, knives, scissors, kitchenware, gardening tools and beauty care kits as well as other hardware tools, the annual production value of which reaches US$ 30 million dollars.

集团所属工厂主要生产多用钳、烤具、刀具、剪刀、厨具、花园工具、美容套等五金产品，年生产总值3000万美元，产品价廉物美、选料上乘、质量保证，深受国内外客户的青睐