共查询到19条相似文献,搜索用时 685 毫秒
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邵文蛟 《交通部上海船舶运输科学研究所学报》1984,(1)
近年来动力松弛法(DR 法——Dynamic Relaxation Method)被认为是非线性结构问题求解中一个有前途和值得推荐的方法。DR 法根据静力解作为动力解在特殊情形下的一部份这一原理,对于任何系统 DR 法有一个标准模式。它计算简易,不必解线性方程组,能节省机时与存贮。虽然早期 DR 法只用于线性结构问题,现已发现它对具有结构与材料都是高度非线性问题也有实效。随着对迭代参数的深入讨论,DR 法的基本理论趋于成熟而且加速了求解的收敛性。但对一些复杂的问题可能要较多的迭代次数才能达到满意的收敛性。本文在分析 DR 解特性的基础上引进 Shanks 变换可以进一步加速其收敛性。实例计算表明,本文的方法是很有效的。 相似文献
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中国力争到2010年单位GDP能耗降低20% 总被引:1,自引:0,他引:1
《中国船检》2009,(6)
根据《中国应对气候变化国家方案》.中国将努力实现以下主要目标:
在控制温室气体排放方面.到2010年,单位国内生产总值能源消耗比2005年降低20%左右.可再生能源开发利用总量(包括大水电)在一次能源供应结构中的比重提高到10%左右。煤层气抽采量达到100亿立方米。工业生产过程的氧化亚氮排放稳定在2005年的水平上。森林覆盖率达到20%.碳汇数量比2005年增加约0.5亿吨二氧化碳。 相似文献
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基于嵌入式系统的软件结构覆盖测试技术 总被引:5,自引:0,他引:5
在软件测试过程中有效地监控代码覆盖率是提高软件测试有效性的一个重要途径,介绍了利用LDRA Testbed测试工具进行嵌入式软件结构覆盖测试的方法和技术。 相似文献
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基于一款嵌入式以太网控制芯片,对不同电路采用不同的低功耗DFT测试技术,以获得较低的测试成本和测试功耗:对于数字逻辑电路,采用了基于扫描链的测试技术,实现了减少翻转次数的测试电路结构;对于片内集成的SRAM、ROM存储器,采用了基于MBIST的测试技术,通过实现准单跳变测试向量生成电路,屏蔽掉无用的测试向量;同时,采用门控时钟等方法来降低CUT输入端的活动性,从而降低CUT上的动态测试功耗;通过采用这些测试方法,该芯片的故障覆盖率可达到97%。 相似文献
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提出一种超高性能混凝土蜂窝结构的浮式风机基础,并将其与具有相同外部几何特征的钢筋混凝土基础进行比较,发现文章所提新型浮式基础的比刚度和比强度显著增大。同时,发展代表体元法,将复杂蜂窝结构等效为均匀化连续体,给出工程设计中关键的弹性模量、塑性屈服点和屈服准则。该方法实现了复杂结构的参数化设计,在保证精度的同时,极大地提高了效率。浮式风机超高性能混凝土蜂窝基础结构与设计方法对于未来深水海上风电发展具有基础性的工程价值。 相似文献
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The traditional time reversal is considered a promising approach for non-destructive testing and health monitoring of key region and structure, but it is considerably time consuming. This paper presents a time reversal damage localization method, based on particle swarm optimization algorithm, which is capable of improving the real-time performance of health monitoring in ocean platform. Firstly, the virtual focusing model of time reversal is constructed, and a succinct expression of virtual focusing for sensor pairs is proposed. Then, on the definition of the evaluation index, the PSO based time reversal algorithm is proposed, and the proper coefficients is given. Finally, the finite element simulation and experimental case validate that the proposed method is capable of find the damage location within limit iterative steps. Thus, the proposed method is a hopeful method for online monitoring and damage localization of large sized structure. 相似文献
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Shangyao Yan Chun-Ying Chen Shih-Chun Lin 《Journal of Marine Science and Technology》2009,14(4):417-435
Good short-term ship scheduling and container shipment planning are very important for liner operations; however, in Taiwan,
most such carriers currently utilize a trial-and-error process. In this study, we employ network flow techniques to construct
a model for such activities. A solution algorithm, based on Lagrangian relaxation, a subgradient method, and a heuristic for
the upper-bound solution, is developed to solve the model. To demonstrate and to test how well the model and the solution
algorithm apply in the real world, we performed a case study using operating data from a major Taiwanese marine shipping company.
The test results show that the model and the solution algorithm could be useful references for ship scheduling and container
shipment planning. 相似文献
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Bend stiffeners are subjected to cyclic loading during offshore operation or when subjected to a controlled full-scale qualification test. Due to the viscoelastic nature of the polyurethane, energy is dissipated within the material volume and the structure may experience a temperature increase, a phenomenon known as self-heating. The top connection is a flexible riser critical region in terms of fatigue, being the bend stiffener the main responsible for curvature control. As the curvature distribution is highly affected by the nonlinear time–temperature bend stiffener response, a detailed thermo-mechanical assessment may become relevant for riser lifetime and polyurethane material failure assessment, specially during accelerated full-scale tests. In the present paper (Part I), the polyurethane experimental characterization and steady-state thermo-mechanical mathematical formulation are presented for the bend stiffener self-heating assessment. A steady-state formulation is derived for a temperature dependent linear viscoelastic large deflection beam model to estimate the heat generation during harmonic tip loading. The temperature field distribution is calculated through a three-dimensional steady-state thermal model considering the viscoelastic heat calculated from the mechanical model with an iterative scheme. Stress relaxation tests are performed at different temperatures to determine the viscoelastic properties followed by thermal properties characterization through differential scanning calorimetry and by the Flash method to determine the specific heat, thermal conductivity and diffusivity, respectively. In a companion paper (Part II) the iterative numerical scheme is detailed and a case study presented. 相似文献
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按照国家标准要求,可靠性试验方案的制定、判别标准和试验结果判定方法的确定均非常复杂,处理不当,易使参试方和承制方对试验结论产生分歧,导致可靠性试验难以展开,尤其对于诸如电动风机、泵组、阀门等舰船通用机电产品而言更是如此。为解决这一问题,促进可靠性试验工作的落实,依据可靠性试验的有关标准和要求,通过对标准试验方法的合理分析,提出了适用于舰船通用机电产品的可靠性试验方法。该方法简单、实用,易于理解和结果判定,可为舰船通用机电产品的可靠性试验验收工作提供新思路。 相似文献
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针对现代电子装备自动测试系统,阐述自动测试系统通用性实现方法,提出激励资源、信号接口装置设计原则,同时探讨了神经网络与自适应算法实现故障诊断与定位中的可行性,并给出一种故障诊断自适应算法实现的方法。 相似文献
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在北极航道开通的背景下,针对在冰区航行环境中船舶航行路径选择的特殊性,通过改进蚁群算法提高船舶航行路径的规划效果。综合考虑航线距离、航行操作复杂度和流冰规避在内的冰区航行路径影响因素,建立路径选择多目标规划模型,结合人工势场法对蚁群算法进行改进,通过人工势场法获得初始路径和节点间距离因素构造启发信息,并以电子海图为基础建立海冰覆盖率分别为30%和50%情况下的冰区航道环境栅格模型,将算法应用在栅格模型中对算法进行验证。结果表明:该算法实现简单,规划的路径优良,能够有效地满足船舶在冰区复杂环境中航行路径规划的需要。 相似文献
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桥吊智能制动器研制成功后,为确保其性能,对其进行测试.介绍测试准备工作和测试做法.测试表明,智能型制动器能有效减小制动冲击,保护传动链,并能有效减小结构晃动. 相似文献