共查询到20条相似文献，搜索用时 203 毫秒
1.
Product data management (PDM) is a unique technique that integrates and manages all applications, information and processes defining a product from design to manufacture, and to end-user support. However, exploration of valuable information and knowledge from the PDM system has become a key in improvement of efficiency and implementation of knowledge management in an enterprise. This paper introduces a data mining prototype system model based on PDM, and emphasizes some important techniques such as design of the prototype system framework, methods of data selection and integration of data mining prototype system and PDM. The model basically solves the problem of functional losses in mining and analyzing data in PDM. Application of data mining to PDM is meaningful to the ideas and techniques of PDM, and to the rapid development of data mining application itself. Also, it is useful in improving development and usage of enterprise databases. 相似文献
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Dynamic Responses Analysis of a Building Structure Subjected to Ground Shock from a Tunnel Explosion
Dynamic responses of a multi-storey building without or with a sliding base-isolation device for ground shock induced by an in-tunnel explosion are numerically analyzed. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation , is considered in the analysis. Different modeling methods, such as the eight-node equal-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition, and the multi-storey building with or without the sliding base-isolation device. In numerical calculations , a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated. The final conclusions based on the numerical results will provide some guidance in engineering practice. 相似文献
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Shuai Guo Hua-Wei Li Jian-Cheng Ji Zhi-Fa Ming 《上海大学学报(英文版)》2014,(4):295-302
Common methods, such as Denavit-Hartenberg （D-H） method, cannot be simply used in kinematic analysis of special robots with hybrid hinge as it is difficult to obtain the main parameters of this method. Hence, a homogeneous transformation theory is presented to solve this problem. Firstly, the kinematics characteristic of this special structure is analyzed on the basis of the closed-chain theory. In such a theory, closed chains can be transformed to open chains, which makes it easier to analyze this structure. Thus, it will become much easier to establish kinematics equations and get the solutions. Then, the robot model can be built in the Simmechanics （a tool box of MATLAB） with these equation solutions. It is necessary to design a graphical user interface （GUI） for robot simulation. After that, the model robot and real robot will respectively move to some spatial points under the same circumstances. At last, all data of kinematic analysis will be verified based on comparison between data got from simulation and real robot. 相似文献
4.
肖剑 《重庆大学学报(英文版)》2005,4(1):59-62
1 Introduction a The bi-level decision-making is a complex majorized problem. Its effective solution is not easy to obtain by traditional majorized methods. Reported methods to solve the bi-level decision making problem with continuous variables include neural network [1], Monte Carlo simulated annealing algorithm [2], etc. However, the efficiency and accuracy of such neural network methods are ideal and accompanied with a long iterative time and a slow convergence speed. In this paper, the … 相似文献
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1 Introduction We will extend the classical ruin model withthe twomain components of premium income and clai mpayment[1 ,2].The third component reflects the randomrates of interest to the free reserve such as a currencydevaluation or credit event[3].Inthelatter case we as-sume that the free reservexis invested in bonds withcredit risk . Upon a credit event the value of the freereserve drops according to the recovery ratezfromxtozx. Then the free reserve is reinvested in bondswith si milar ris… 相似文献
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Fuzzy finish time modeling for project scheduling 总被引：1，自引：0，他引：1
This research aims at developing a new fuzzy activity finish time estimation model for project scheduling management.With the application of the fuzzy quality function deployment （FQFD） and fuzzy analytic hierarchy process （FAHP） methods,the degree of fuzziness for every project activity is calculated in accordance with considerations of project uncertainties.These uncertainties are measured by the risk level of such project-related characteristics as time limit,activity start time,budget,manpower,technological difficulty,and facility requirements.In this paper,rather than applying the de-fuzzification technique to obtain the crisp activity duration for project scheduling,the fuzzy finish time estimation method for every activity is proposed based on the degree of fuzziness.The corresponding fuzzy activity duration time plot is also developed in a new fuzzy Gantt chart.The proposed model can provide a reasonable fuzzy finish time estimation for every activity,while most scheduling methods only provide the finish time of the entire project.Compared to existing models,this time estimation model and its corresponding Gantt chart are predicted to have higher reliability and practical application in project management and scheduling. 相似文献
7.
Deborah K. Zuercher Cristy Kessler Jon Yoshioka 《美中教育评论》2011,(1):1-13
The CAST （content area specialized training） model of professional development enables sustainable teacher leadership and is responsive to the need for culturally relevant educational practices. The purpose of this paper is to share the background, methods, findings and recommendations of a case study on the CAST initiative in Guam. The case study is worth a look given that 100% of the participants in the CAST initiative indicated that they were satisfied with the CAST model of professional development. 相似文献
8.
Two experimental tests of three-storied reinforced concrete structural walls having large openings were performed.Based on an original macro model,a multiple modified macro-model was proposed to develop a simple method to design a reinforced concrete structural wall with large openings and various opening locations.The interaction between reinforcement ties and concrete struts formed along the perimeter of openings was neglected in the original model.However,the strut-and-tie node was proposed to take account of such interaction in the proposed model.The predicted behavior of two specimens using such a proposed model was compared with the experimental results.It is shown that the behavior of structural walls with large openings could be modeled well using the proposed model.Moreover,the study indicates that the proposed model is applicable even in cases of multi-story structural walls having large openings and various opening locations. 相似文献
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After China’s entry into the WTO,the interchange and communication between China and the international community has increased,which exerts great influence on pushing forward the modernization and construction of the various industries in China and requires a large number of people with good command of English.Under these circumstances,English education becomes extremely important.Guangxi,an old revolutionary base area inhabited by minority ethnic groups,is falling behind with its economy,culture and education in comparison with eastern regions of China.A number of English teachers,especially those in middle schools of the rural areas,are provided with little education and few opportunities for advanced study;most of them lack the new teaching ideas,models or methods which could replace the traditional teaching model that centers on the teacher and textbook.As a result,students can’t give full play to their subjective initiative with low communication and application capability in English.To confer impetus to English language teaching reform,researchers and scholars have made great efforts in experimenting various teaching models with the hope to find a language teaching model which can meet the demands of the new era and B-SLIM model put forward by Dr.Olenka Bilash is such a model. 相似文献
10.
Ti-6A1-4V super alloy is an important engi- neering material with good strength to weight ratio and a wide range of applications in a number of engineering fields because of its excellent physical and mechanical properties. This work determines optimum process parameters such as pulse on time, peak current, gap voltage and flushing pressure, which influence the micro-electro discharge machining （EDM） process during machining of Ti-6AI-4V using combined methods of response surface methodology （RSM） and fuzzy-technique for order pref- erence by similarity to ideal solution （TOPSIS）. Central composite design （CCD） is used in the experimental investigation. A decision making model is developed to identify the optimum process parameters in the micro- EDM process, which influences several machining criteri- ons such as material removal rate （MRR）, tool wear rate （TWR）, overcut （OC） and taper. Triangular fuzzy numbers are used to determine the weighting factor for each process criterion. Further a fuzzy-TOPSIS method is used to select the most desirable factor level combinations. The proposed technique can be used to select optimal process parameters from various sets of combinations of process parameters in a micro-EDM process. 相似文献
11.
针对场景照明变化、模型初始化以及阴影等问题, 提出了一种用于视频监视系统运动物体检测的统计多模态背景模型. 通过相隔固定的帧差值阈值化得到背景样本值, 并采用高斯核密度估计方法计算背景灰度的概率密度函数. 利用像素的邻域信息来去除由于摄像机抖动和场景小运动产生的噪声. HMMD色彩信息用来检测和抑制运动投射阴影. 实验结果验证了算法在交通监控前景物体分割中的有效性. 相似文献
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依据吉林省的微观数据,文章分析了社会背景和家庭背景对个人教育收益的影响。在收入方程中引入社会背景变量后,明显地降低了个人教育收益率的估计值。而且,应用隐变量模型采用家庭背景变量作为工具变量之后得到修正的个人教育收益率的估计值为7.5%左右。估计结果表明,社会背景和家庭背景确实对个人教育收益有着显著的影响。 相似文献
15.
针对运动目标检测中背景模型的获取和更新,描述了自适应背景模型常用的几种背景模型,并对这些背景建模和更新进行了分析和比较,最后通过试验验证了各自的有效性. 相似文献
16.
Reading comprehension is undoubtedly one of the most important abilities for English learners. This paper firstly makes a brief introduction to the reading theory and cultural background knowledge. Then using schema theory and typical examples,the paper demonstrates the role of cultural background knowledge in reading comprehension. The application of cultural background knowledge in reading practice is proposed as the keys to the improvement of reading comprehension ability. 相似文献
17.
苹果是我国年产量最高的水果,但出口量不足总产量的 2%,采用基于图像处理的水果表面缺陷检测技术可促进水果的分级与销售。以红富士苹果为研究对象,首先采集苹果的 RGB 图像,并根据转换公式得到图像的 HSV 彩色模型,对饱和度 S 分量进行阈值分割与孔洞填充,获得苹果背景分离模板|然后根据背景分离模板得到 R 分量的背景分离图,并对分离背景后的 R 分量进行亮度校正|最后采用单阈值分割法提取缺陷。实验共采集 300 个苹果样本,包括缺陷果 200 个,正常果 100 个,其中对缺陷果的识别率达到 96.5%,对正常果的识别率达到 100%。实验结果表明,采用 S 分量获取背景分离模板,并结合亮度校正算法,可在不增加额外拍摄装置的情况下获得较好的缺陷提取效果。 相似文献
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实时背景更新是数字视频监控中进行运动目标检测的关键技术,与基于PC的监控系统不同,嵌入式系统资源有限,难以执行复杂算法。为此提出一种帧间差分和背景减除法相结合的新方法,通过引入备份帧,有效实现了监控系统的自适应背景更新,并在嵌入式处理器DM6437上实现。实验结果表明该方法可以自动检测物体进出所引起的背景变化并进行背景更新,更新速度快,能够满足实时监控系统目标检测的需要。 相似文献
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许大宏 《连云港职业技术学院学报》2011,24(1):9-13
为了提高公路交通运输量的预测精度和公路运输行业的管理水平,研究了GM（1,1）模型特性、GM（1,1）在背景值和初始值选择两方面所存在的缺陷;提出一种新的背景值计算方法;最后,利用2000-2004年的公路客运量的实际数据进行了验证,结果表明：改进模型的预测精度要高于GM（1,1）模型的预测精度,前者比后者具有更高的预测精度和可靠性. 相似文献
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柯宏胜 《安庆师范学院学报(社会科学版)》2007,26(6):115-118
电视新闻背景对更完整、更全面、更充分地认识电视新闻事实的本质,突出新闻事实的新闻价值,可发挥不可替代的重要作用。选择新闻背景,既要与主体有关,又要便于表达主题,应在服从新闻主题的基础上,不拘一格、灵活机动地选择、布置背景材料。电视新闻背景材料的运用,除了要像广播解说、报纸文字那样交代背景外,还要更注意发挥其自身特点和优势,尽可能用电视媒介所提供的各种手段交代背景材料。 相似文献