期刊文献+
共找到13篇文章
< 1 >
每页显示 20 50 100
结构参数大修改时的特征值重分析方法 被引量:5
1
作者 杨晓伟 陈塑寰 《力学学报》 EI CSCD 北大核心 2001年第4期555-560,共6页
就结构参数发生大修改的情况提出了两种高精度的特征值重分析方法:Pade 逼近法和推广的Kirsch混合法.利用这两种方法,计算了一个具有202个结点,357个梁单元的平面框架的近似特征值.计算结果表明,所提出的方法是... 就结构参数发生大修改的情况提出了两种高精度的特征值重分析方法:Pade 逼近法和推广的Kirsch混合法.利用这两种方法,计算了一个具有202个结点,357个梁单元的平面框架的近似特征值.计算结果表明,所提出的方法是结构参数修改时的特征值重分析的有效方法. 展开更多
关键词 结构参数大修改 特征值重分析 Padé逼近法 Kirsch混合法 平面框架 结构优化 近似特征值
下载PDF
结构拓扑大修改的动力学重分析方法 被引量:3
2
作者 何建军 姜节胜 康兴无 《振动工程学报》 EI CSCD 北大核心 2007年第4期407-411,共5页
针对自由度增加的结构拓扑大修改,提出了一种基于改进的动力缩聚和独立质量正交化处理以及瑞利-里兹法结合起来的动力学重分析新方法。方法根据初始自由度和新增加自由度上特征向量的独立和耦合作用,采用独立和耦合质量正交化处理来改... 针对自由度增加的结构拓扑大修改,提出了一种基于改进的动力缩聚和独立质量正交化处理以及瑞利-里兹法结合起来的动力学重分析新方法。方法根据初始自由度和新增加自由度上特征向量的独立和耦合作用,采用独立和耦合质量正交化处理来改善近似特征向量的逼近质量。该方法与完全再分析相比,能够大量减少计算量,且操作简单,易于实现。两个数值算例表明,所提出的方法对于结构拓扑大修改能给出高精度的逼近结果,是一种有效的新方法。 展开更多
关键词 结构拓扑大修改 动力学重分析 瑞利-里兹分析
下载PDF
大型结构大修改下的静力重分析方法 被引量:3
3
作者 黄冀卓 王湛 《力学学报》 EI CSCD 北大核心 2011年第2期355-361,共7页
对于大型结构发生参数大修改时,采用组合近似算法进行结构位移重分析会使所得的近似解与真实解误差较大.为了解决组合近似算法在大型结构发生参数大修改时的求解精度不足缺陷,提出了3种改进的结构静力重分析方法.该3种改进算法都是基于... 对于大型结构发生参数大修改时,采用组合近似算法进行结构位移重分析会使所得的近似解与真实解误差较大.为了解决组合近似算法在大型结构发生参数大修改时的求解精度不足缺陷,提出了3种改进的结构静力重分析方法.该3种改进算法都是基于组合近似算法,并分别通过位移迭代修正、刚度逐步逼近等措施使求解精度不断提高.通过2个算例验证了3种改进算法的有效性和高效性,并对3种改进算法之间的求解效率进行了比较. 展开更多
关键词 静力重分析 近似重分析 组合近似法 大型结构 大修改
下载PDF
重频结构大修改动力重分析的矩阵摄动法
4
作者 刘志军 王晓军 干为民 《振动.测试与诊断》 EI CSCD 北大核心 2015年第5期837-840,988,共4页
为拓展矩阵摄动法在结构重分析中的适用范围,提高重分析计算精度,针对重频结构参数大修改提出了重频结构动力重分析的矩阵摄动法。采用高次增量法将反映重频结构参数改变的质量矩阵和刚度矩阵的增量分别表示为小参数ε的一次与二次幂项... 为拓展矩阵摄动法在结构重分析中的适用范围,提高重分析计算精度,针对重频结构参数大修改提出了重频结构动力重分析的矩阵摄动法。采用高次增量法将反映重频结构参数改变的质量矩阵和刚度矩阵的增量分别表示为小参数ε的一次与二次幂项之和,根据矩阵摄动理论推导得到重特征值的二阶摄动解及相应特征向量的一阶摄动解。数值算例表明,所提出方法极大提高了重频结构大修改下的动力重分析计算精度。 展开更多
关键词 重频结构 结构动力重分析 结构大修改 矩阵摄动法
下载PDF
大修改结构特征向量重分析的混合基展开法
5
作者 刘志军 邓兆祥 《振动.测试与诊断》 EI CSCD 北大核心 2015年第3期559-562,597,共4页
为拓展基于矩阵摄动理论的结构重分析方法在实际工程中的适用范围,提高重分析计算精度,针对结构模态空间不完备和参数大修改提出了结构动力重分析的混合基展开法。利用已知的少数几个可能不连续的低阶模态构造出整个模态空间的一个混合... 为拓展基于矩阵摄动理论的结构重分析方法在实际工程中的适用范围,提高重分析计算精度,针对结构模态空间不完备和参数大修改提出了结构动力重分析的混合基展开法。利用已知的少数几个可能不连续的低阶模态构造出整个模态空间的一个混合基,同时将反映结构参数改变的质量矩阵和刚度矩阵的增量表示为高次增量形式,保留了经典摄动法简单易行的特点。数值算例表明,所提出方法适用范围广,极大提高了结构大修改下的动力重分析计算精度。 展开更多
关键词 结构动力重分析 结构大修改 矩阵摄动法 混合基展开法
下载PDF
住建部修改工程施工招标投标管理办法
6
《中国勘察设计》 2018年第11期7-7,共1页
为贯彻落实国务院深化“放管服”改革,优化营商环境的要求,近日,住建部发布关于修改《房屋建筑和市政基础设施工程施工招标投标管理办法》的决定,对《房屋建筑和市政基础设施工程施工招标投标管理办法》(建设部令第89号)作出了大... 为贯彻落实国务院深化“放管服”改革,优化营商环境的要求,近日,住建部发布关于修改《房屋建筑和市政基础设施工程施工招标投标管理办法》的决定,对《房屋建筑和市政基础设施工程施工招标投标管理办法》(建设部令第89号)作出了大修改。 展开更多
关键词 招投标管理 7大修改
下载PDF
Epsilon算法在汽车结构设计分析中的应用 被引量:3
7
作者 吴晓明 陈塑寰 黄志东 《吉林大学学报(工学版)》 EI CAS CSCD 北大核心 2006年第B03期8-11,共4页
基于矩阵摄动法和Epsilon算法,给出了一种新的结构修改静态重分析方法。该方法直观、容易实施,计算量比重新求解小。将该方法应用于汽车车架的设计计算中,结果表明:与 Kirsch组合近似法比较,即使汽车车架结构参数修改比较大时,应用该方... 基于矩阵摄动法和Epsilon算法,给出了一种新的结构修改静态重分析方法。该方法直观、容易实施,计算量比重新求解小。将该方法应用于汽车车架的设计计算中,结果表明:与 Kirsch组合近似法比较,即使汽车车架结构参数修改比较大时,应用该方法也能得到满意的结果。 展开更多
关键词 工程力学 静态位移重分析 Epsilon算法 矩阵摄动 汽车车架结构参数大修改
下载PDF
Control for Modified University of Cape Town Process Using Oxidation-Reduction Potential in the Second Anoxic Zone
8
作者 王晓玲 林英姿 +3 位作者 李娜 张芳 谢添 董利鹏 《Journal of Donghua University(English Edition)》 EI CAS 2013年第3期215-221,共7页
The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential (ORP) control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhi... The aim of this work is to evaluate the feasibility of applying the technology of oxidation-reduction potential (ORP) control on the municipal wastewater treatment system for nitrogen and phosphorus removal. Meanwhile the relation between the optimal ORP ( ORPopt ) and influent C/N ratio was evaluated, in which the influent chemical oxygen demand ( COD ) concentration was stabilized at (290 ± 10 ) mg/L, the influent total phosphorus (TP) concentration was stabilized at (7.0 ± 0.5 ) mg/L. The results indicated that: (1) the ORP in the second anoxic zone had effect on nitrogen and phosphorus removal capability, and the average percentages of phosphorus uptake in ANO2 zone ( ηa ) increased with increasing ORP, i. e. , increasing from 12. 0% at - 143 mV to 22.0%,30.0%,37.0%, and45.0% at -123, -111, -105 and -95 mV, respectively; (2) the ORPopt as function of influent C/N ratio could be calculated by the equation: y ffi 252. 73e〈 -x/3.39) _ 131.01 ; the maximum percentage of phosphorus uptake in ANO2 as function of the ORPopt could be calculated by the equation: y ffi -0.49e(x/15.58) + 1. 51. The ORPopt was the important process control parameter that must be optimized for operation of enhanced biological phosphorus removal ( EBPR ) system. Moreover, ORP sensor is very simple, and the industrial applications of this strategy is practical. 展开更多
关键词 modified University of Cape Town (MUCT) process NITRATE oxidation-reduction potential (ORP) phosphorus uptake
下载PDF
Black Hole Entropy with Modified Dispersion Relations
9
作者 WANG Fu-Jun GUI Yuan-Xing ZHANG Yu 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第8期261-263,共3页
There is much interest in resolving the quantum corrections to Bekenstein-Hawking entropy with a large length scale limit. The leading correction term & given by the logarithm of black hole area with a model-dependen... There is much interest in resolving the quantum corrections to Bekenstein-Hawking entropy with a large length scale limit. The leading correction term & given by the logarithm of black hole area with a model-dependent coefficient. Recently the research for quantum gravity implies the emergence of a modification of the energy-momentum dispersion relation (MDR), which plays an important role in the modified black hole thermodynamics. In this paper, we investigate the quantum corrections to Bekenstein-Hawking entropy in four-dimensional Sehwarzschild black hole and Reissner-Nordstrom black hole respectively based on MDR. 展开更多
关键词 black hole ENTROPY dispersion relation
下载PDF
Thermal Ionization Method of Modifying the Atmospheric Processes
10
作者 Vladimir Kozlov Nikolay Korshun 《Journal of Earth Science and Engineering》 2014年第9期558-571,共14页
The paper discusses the influence of ions on the formation of clouds, precipitation and thunderstorm electricity. Thermal ionization method is based on two core concepts: electrical micro- and macro-instability of cl... The paper discusses the influence of ions on the formation of clouds, precipitation and thunderstorm electricity. Thermal ionization method is based on two core concepts: electrical micro- and macro-instability of clouds. Cloud droplets increase in sizes in the ascending air under the influence of electric micro-instability. Macro-instability is responsible for the formation of space charges in convective clouds. Artificial rainfall and discharge of space charges of clouds may be caused by means of the electrical modification techniques. The key role in these processes belongs to thermionic production of artificial light and heavy ions, which are formed as the result of applying a pyrotechnic composition of potassium-magnesium compounds. Negative ions are hydrated and adsorbed by cloud droplets leading to their growth and further rainfall. An artificial ionized channel allows to change cloud conductivity, which prevents clouds from accumulating thunderstorm electricity. Electrical methods of cloud modification can be used for the artificial induction of precipitation, prevention of natural hazards, thunderstorms, tornadoes and heavy rains. 展开更多
关键词 IONS convective clouds types of electrical instability thermal ionization modification of precipitation and thunderstorms.
下载PDF
Developing a Coherent Stratigraphic Scheme of the Albertine Graben-East, Africa
11
作者 Joshua Lukaye David Worsley +9 位作者 Lyoidah Kiconco Proscovia Nabbanja Dozith Abeinomugisha Catherine Amusugut Nurudin Njabire Richard Nuwagaba Frank Mugisha Tonny Ddungu Tonny Sserubiri Vivienne Sempala 《Journal of Earth Science and Engineering》 2016年第5期264-294,共31页
The Albertine Graben is one of the most petroliferous onshore rifts in Africa. It forms the northemmost termination of the western arm of the East African Rift System. Its surface exposures were first studied by Wayla... The Albertine Graben is one of the most petroliferous onshore rifts in Africa. It forms the northemmost termination of the western arm of the East African Rift System. Its surface exposures were first studied by Wayland [1] and Pickford et al. [2] among others. Pickford et al. [2] especially developed the basic stratigraphic framework of the graben which was later modified by the government geoscientists and international oil companies using subsurface data. However, the stratigraphic units were not fully and formally described, and have been used informally in different and often confusing ways. The current study therefore aims to solve this challenge by establishing a coherent stratigraphic scheme for the entire graben through an integral study of surface and subsurface data. The study involves precise description of the type and reference sections for various formations both in exposure and wells; and has therefore led to the development of lithostratigraphic columns of different basins in the graben. The approach reveals that the Semliki area, south of Lake Albert, has the most complete sedimentary succession in the graben, spanning the period from middle Miocene (ca 15 Ma) to Recent. It also reveals that platform deposits, which form a small fraction of the thickness of the basinal succession, represent a highly condensed sequence which only saw deposition at times of Lake highstand. 展开更多
关键词 LITHOSTRATIGRAPHY subsurface and surface sediments correlation Albertine Graben.
下载PDF
Modified Augmented Lagrange Multiplier Methods for Large-Scale Chemical Process Optimization 被引量:6
12
作者 梁昔明 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2001年第2期167-172,共6页
Chemical process optimization can be described as large-scale nonlinear constrained minimization. The modified augmented Lagrange multiplier methods (MALMM) for large-scale nonlinear constrained minimization are studi... Chemical process optimization can be described as large-scale nonlinear constrained minimization. The modified augmented Lagrange multiplier methods (MALMM) for large-scale nonlinear constrained minimization are studied in this paper. The Lagrange function contains the penalty terms on equality and inequality constraints and the methods can be applied to solve a series of bound constrained sub-problems instead of a series of unconstrained sub-problems. The steps of the methods are examined in full detail. Numerical experiments are made for a variety of problems, from small to very large-scale, which show the stability and effectiveness of the methods in large-scale problems. 展开更多
关键词 modified augmented Lagrange multiplier methods chemical engineering optimization large-scale non- linear constrained minimization numerical experiment
下载PDF
Locomotor adaptations in Plio-Pleistocene large carnivores from the Italian Peninsula: Palaeoecological implications
13
作者 Carlo MELORO 《Current Zoology》 SCIE CAS CSCD 北大核心 2011年第3期269-283,共15页
Mammalian carnivores are rarely considered for environmental reconstructions because they are extremely adaptable and their geographic range is usually large. However, the functional morphology of carnivore long bones... Mammalian carnivores are rarely considered for environmental reconstructions because they are extremely adaptable and their geographic range is usually large. However, the functional morphology of carnivore long bones can be indicative of locomotor behaviour as well as adaptation to specific kind of habitats. Here, different long bone ratios belonging to a subsample of extant large carnivores are used to infer palaeoecology of a comparative sample of Plio-Pleistocene fossils belonging to Italian paleo-communities. A multivariate long bone shape space reveals similarities between extant and fossil carnivores and multiple logistic regression models suggest that specific indices (the brachial and the Mt/F) can be applied to predict adaptations to grassland and tropical biomes. These functional indices exhibit also a phylogenetic signal to different degree. The brachial index is a significant predictor of adaptations to tropical biomes when phylogeny is taken into account, while Mt/F is not correlated anymore to habitat adaptations. However, the proportion of grassland-adapted carnivores in Italian paleo-communities exhibits a negative relationship with mean oxygen isotopic values, which are indicative of past climatic oscillations. As climate became more unstable during the Ice Ages, large carnivore guilds from the Italian peninsula were invaded by tropical/closed-adapted species. These species take advantage of the temperate forest cover that was more spread after 1.0 Ma than in the initial phase of the Quaternary (2.0 Ma) when the climate was more arid [Current Zoology 57 (3): 269-283, 2011]. 展开更多
关键词 CARNIVORA Long bones QUATERNARY Climate change
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部