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Structural topology optimization under stationary random base acceleration excitations
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作者 Fei HE Hongqiang LIAO +1 位作者 Jihong ZHU Zhongze GUO 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第6期1416-1427,共12页
Structural topology optimization subjected to stationary random base acceleration excitations is investigated in this paper. In the random response analysis, the Large Mass Method(LMM) which attributes artificial larg... Structural topology optimization subjected to stationary random base acceleration excitations is investigated in this paper. In the random response analysis, the Large Mass Method(LMM) which attributes artificial large mass values at each driven nodal Degree Of Freedom(DOF) to transforming the base acceleration excitations into force excitations is proposed. The Complete Quadratic Combination(CQC) which is commonly used to calculate the random responses in previous optimization has been proven to be computationally expensive especially for large-scale problems. In order to conquer this difficulty, the Pseudo Excitation Method(PEM) and the combined method of PEM and Mode Acceleration Method(MAM) are adopted into the dynamic topology optimization, and random responses are calculated using these two methods to ascertain a high efficiency over the CQC. A density-based topology optimization method minimizing dynamic responses is then formulated based on the integration of LMM and PEM or the combined method of PEM and MAM. Numerical examples are presented to verify the accuracy of the proposed schemes in dynamic response analysis and the quality of the optimized design in improving dynamic performance. 展开更多
关键词 Dynamic response Large mass METHOD Mode ACCELERATION METHOD PSEUDO excitation METHOD RANDOM BASE ACCELERATION EXCITATIONS Topology optimization
泵站单机组变角运行优化方法对比研究 预览
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作者 盛喆 《江苏水利》 2019年第6期67-72,共6页
针对江都四站泵站单机组变角运行优化问题,提出了解决该问题的数学模型及求解方法。在优化算法的外部提前计算出了各时段满足功率约束的叶片角,降低了优化计算的复杂度。通过实验比较,得出了动态惩罚函数法能更有效地处理提水量约束条... 针对江都四站泵站单机组变角运行优化问题,提出了解决该问题的数学模型及求解方法。在优化算法的外部提前计算出了各时段满足功率约束的叶片角,降低了优化计算的复杂度。通过实验比较,得出了动态惩罚函数法能更有效地处理提水量约束条件。将动态惩罚函数遗传算法的计算结果和算法运行时间分别与动态规划法、枚举法进行对比,3种方法按照总费用从小到大排序依次是:枚举法、动态惩罚函数遗传算法、动态规划法,3种优化方法相互之间的单位提水费用偏差率均小于0.2%。运算时间方面,动态惩罚函数遗传算法和动态规划法几乎相同,枚举法耗时接近前2种方法的6倍。综合比较,动态惩罚函数遗传算法更适合江都四站泵站单机组变角运行优化问题的计算。 展开更多
关键词 泵站单机组 约束条件 动态惩罚函数遗传算法 动态规划法 枚举法
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基于SIMPACK建模的某特种车辆动力学计算结果的后处理分析
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作者 邹建军 黄志辉 《机车电传动》 北大核心 2019年第1期61-63,67共4页
讨论在SIMPACK后处理中常用的4种滤波方法,并以计算曲线工况下的动力学指标为例,采用图形对比的方式,将使用4种滤波方法得出的计算结果与未进行后处理的波形图进行图形对比,较为直观地选出了比较吻合实际结果的滤波方法。从对比结果中... 讨论在SIMPACK后处理中常用的4种滤波方法,并以计算曲线工况下的动力学指标为例,采用图形对比的方式,将使用4种滤波方法得出的计算结果与未进行后处理的波形图进行图形对比,较为直观地选出了比较吻合实际结果的滤波方法。从对比结果中可以看出,采用第99.75百分位数的结果更为可靠。研究可为今后使用SIMPACK软件进行动力学计算结果的后处理分析时对滤波方式的选取提供参考。 展开更多
关键词 SIMPACK 动力学指标 车辆动力学 滤波方法 曲线通过
动态在线扩展Web测试系统 预览
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作者 张飞 王亚雄 郭开卫 《现代信息科技》 2019年第11期101-104,共4页
现有的Web测试系统一般分为需求分析、架构设计、编码测试、上线运维等几个阶段,在这种情况下开发需求分析工作至关重要,因为系统一旦开发上线完毕,对系统的任何更改都是一件代价比较昂贵的事情。作为测试系统,其输入的特殊性决定了其... 现有的Web测试系统一般分为需求分析、架构设计、编码测试、上线运维等几个阶段,在这种情况下开发需求分析工作至关重要,因为系统一旦开发上线完毕,对系统的任何更改都是一件代价比较昂贵的事情。作为测试系统,其输入的特殊性决定了其需求的多变性,测试接口的多变也使得很难在需求分析阶段就能够对测试接口进行确定。这些外部约束注定了该类系统的开发代价相对其他系统来说比较高昂。针对系统需求多变、接口多变难以确定设计的特点,本文提供一种能够针对命令进行动态编辑、动态选择、动态执行的Web测试系统和Web测试方法来试图在一定程度上解决这些问题。 展开更多
关键词 动态扩展 Web测试系统 动态编辑 测试方法
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Evaluation and scenario simulation for forest ecological security in China 预览
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作者 Qin Zhang Guangyu Wang +4 位作者 Feng Mi Xuanchang Zhang Lianzhen Xu Yufang Zhang Xiaoli Jiang 《林业研究:英文版》 CAS CSCD 2019年第5期1651-1666,共16页
Continuously growing populations and rapid economic development have led to the excessive use of forest resources,and the forest ecosystem is threatened.In response,forest ecological security(FES)has attracted attenti... Continuously growing populations and rapid economic development have led to the excessive use of forest resources,and the forest ecosystem is threatened.In response,forest ecological security(FES)has attracted attention.In this study,an integrated dynamic simulation model was constructed using the system dynamic method,and it was used to evaluate the FES in China from 1999 to 2014.A scenario analysis was then used to evaluate the changes in the FES under five forestry policy scenarios for the 2015–2050 period,including the baseline,afforestation policy,harvesting policies,management policy,investment policy,and a policy mix.The results showed that the evaluation values of the FES increased during the period from 1999 to 2002,the period from 2004 to 2010 and the year 2014,and they decreased in 2003 and during the period from 2011 to 2013.During the 2015–2050 simulation period,the FES improved continuously.In particular,China would enter a new stage when the economic systems,social systems and ecosystems were in harmony after 2040.To improve the FES and the current status of the FES,a scenario analysis showed the most suitable scenario to be Scenario 5 from 2015 to 2020 and Scenario 2 from 2021 to 2050.To relieve pressure,the most suitable scenario would be Scenario 5 from 2015 to 2040 and from 2046 to 2050,and the most suitable scenario would be Scenario 4 for 2041–2045.A policy mix(Scenario 5)would be most efficient under current conditions,while the effects of all the benefits of the forestry policies would weaken over the long term.The integrated method can be regarded as a decision support tool to help policy makers understand FES and promulgate a reasonable forestry policy. 展开更多
关键词 DYNAMIC change TREND FOREST ECOLOGICAL security Integrated EVALUATION method System DYNAMIC model POLICY simulation
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动态法与静态法测定电池三元材料比表面积对比研究 预览
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作者 梁华妹 曾勇 +1 位作者 黄诗健 李树鹏 《广东化工》 CAS 2019年第6期61-63,共3页
它主要采用贝世德3H-2000A(动态法)测定电池三元材料(镍钴锰氢氧化物以及镍钴锰酸锂材料)的比表面积(BET)的大小,并和3020麦克物理吸附仪测定结果(静态法)进行对比。动态法测定不同比表面积的相对标准偏差在3.0%以内,数据可靠,尤其在测... 它主要采用贝世德3H-2000A(动态法)测定电池三元材料(镍钴锰氢氧化物以及镍钴锰酸锂材料)的比表面积(BET)的大小,并和3020麦克物理吸附仪测定结果(静态法)进行对比。动态法测定不同比表面积的相对标准偏差在3.0%以内,数据可靠,尤其在测定小比表面积的镍钴锰酸锂材料时精密度较高;研究对比了不同参比样测定不同比表面积结果与静态法结果,以贝世德标样作为参比样测试时,两种测试结果差异较大;以静态法测定结果为参比样时,动态法和静态法测试结果几乎一致;研究对比了更改动态法修正系数所得结果和静态法结果,当以1.20的修正系数,测定镍钴锰酸锂材料,以1.05的修正系测定镍钴锰氢氧化物时,所得结果与静态法几乎一致。 展开更多
关键词 动态法 静态法 比表面积 三元材料
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单晶高温合金弹性模量和泊松比测试方法的现状分析 预览
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作者 赵澎涛 于慧臣 何玉怀 《航空材料学报》 CAS CSCD 北大核心 2019年第3期25-34,共10页
针对单晶高温合金等材料弹性常数表现出的各向异性特点,归纳了现有用于单晶高温合金弹性模量和泊松比的两种主要测试方法:静态法和动态法。分析单晶高温合金弹性模量和泊松比的国内外研究现状,总结目前国内外研究中存在的主要问题及可... 针对单晶高温合金等材料弹性常数表现出的各向异性特点,归纳了现有用于单晶高温合金弹性模量和泊松比的两种主要测试方法:静态法和动态法。分析单晶高温合金弹性模量和泊松比的国内外研究现状,总结目前国内外研究中存在的主要问题及可行的解决途径,并指出:单晶高温合金弹性模量和泊松比测试缺乏专门的测试标准;相比国外,国内在测试与表征技术研究方面还存在明显的差距,工程应用中往往忽视晶体取向对弹性模量和泊松比的影响,因此有必要针对现有的测试标准和方法对测量单晶高温合金弹性常数的误差影响进行评估,制定适用于单晶高温合金的测试标准。同时,详细阐述在考虑晶体取向的影响下,通过对晶体取向指数与弹性模量的线性回归分析,建立单晶高温合金DD6材料弹性模量和泊松比与晶体取向的定量关系的过程。 展开更多
关键词 单晶高温合金 弹性模量和泊松比 静态法 动态法 晶体取向
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Ballistic Trajectory Extrapolation and Correction of Firing Precision for Multiple Launch Rocket System 预览
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作者 ZHA Qicheng RUI Xiaoting +1 位作者 WANG Guoping YU Hailong 《南京航空航天大学学报:英文版》 EI CSCD 2019年第2期232-241,共10页
The research on multiple launch rocket system(MLRS)is now even more demanding in terms of reducing the time for dynamic calculations and improving the firing accuracy,keeping the cost as low as possible.This study emp... The research on multiple launch rocket system(MLRS)is now even more demanding in terms of reducing the time for dynamic calculations and improving the firing accuracy,keeping the cost as low as possible.This study employs multibody system transfer matrix method(MSTMM),to model MLRS.The use of this method provides effective and fast calculations of dynamic characteristics,initial disturbance and firing accuracy.Further,a new method of rapid extrapolation of ballistic trajectory of MLRS is proposed by using the position information of radar tests.That extrapolation point is then simulated and compared with the actual results,which demonstrates a good agreement.The closed?loop fire correction method is used to improve the firing accuracy of MLRS at low cost. 展开更多
关键词 multi-body SYSTEM transfer matrix method(MSTMM) multiple LAUNCH rocket system(MLRS) dynamic modeling BALLISTIC trajectory EXTRAPOLATION fire CORRECTION METHOD
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Similarity comprehensive evaluation of humanoid robot arm motion 预览
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作者 李立明 Zhao Jing +1 位作者 Yan Chaojie Wang Chunrong 《高技术通讯:英文版》 CAS 2019年第1期88-96,共9页
A suitable comprehensive evaluation method for similarity comprehensive evaluation of humanoid motion (mainly to robotic arm) is proposed.For different robotic arms, a static comprehensive evaluation model is establis... A suitable comprehensive evaluation method for similarity comprehensive evaluation of humanoid motion (mainly to robotic arm) is proposed.For different robotic arms, a static comprehensive evaluation model is established by projection pursuit evaluation based on indexes of humanoid robot arm motion in robotics and ergonomics field. Based on projection pursuit evaluation with timing information entropy and time degrees, a dynamic comprehensive evaluation method is proposed by linear weighting to each time’s static model’s indexes weight according to timing weighted vectors. Through comparing similarity comprehensive evaluation result based on static and dynamic comprehensive evaluation model, the results show that similarity based on dynamic comprehensive evaluation model is high. By comparing reliability, similarity and dispersion of static and dynamic comprehensive evaluation models, the results show that dynamic comprehensive evaluation result has better accuracy, stability and lower dispersion, and the result is more reasonable and real. Therefore, the dynamic comprehensive evaluation method proposed in this paper is more suitable for similarity comprehensive evaluation of humanoid robot arm motion. 展开更多
关键词 HUMANOID robot arm MOTION SIMILARITY COMPREHENSIVE EVALUATION projection pursuit EVALUATION METHOD dynamic COMPREHENSIVE EVALUATION METHOD relative efficiency
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An overview of particle-based numerical manifold method and its application to dynamic rock fracturing 预览
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作者 Xing Li Jian Zhao 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第3期684-700,共17页
This review summarizes the development of particle-based numerical manifold method(PNMM)and its applications to rock dynamics.The fundamental principle of numerical manifold method(NMM)is first briefly introduced.Then... This review summarizes the development of particle-based numerical manifold method(PNMM)and its applications to rock dynamics.The fundamental principle of numerical manifold method(NMM)is first briefly introduced.Then,the history of the newly developed PNMM is given.Basic idea of PNMM and its simulation procedure are presented.Considering that PNMM could be regarded as an NMM-based model,a comparison of PNMM and NMM is discussed from several points of view in this paper.Besides,accomplished applications of PNMM to the dynamic rock fracturing are also reviewed.Finally,some recommendations are provided for the future work of PNMM. 展开更多
关键词 Dynamic rock fracturing NUMERICAL modeling NUMERICAL MANIFOLD method(NMM) Particle-based NUMERICAL MANIFOLD method(PNMM)
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球形移动机器人的研究进展与发展趋势
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作者 战强 李伟 《机械工程学报》 EI CAS CSCD 北大核心 2019年第9期1-17,共17页
球形移动机器人(简称球形机器人)是一种拥有球形外壳的全封闭机器人,它通过质心偏移或者动量守恒等原理来实现运动。该类机器人具有良好的密封性,平衡性强且运动灵活性高,不存在侧翻问题,因此球形机器人在星球探索、危险环境探测等领域... 球形移动机器人(简称球形机器人)是一种拥有球形外壳的全封闭机器人,它通过质心偏移或者动量守恒等原理来实现运动。该类机器人具有良好的密封性,平衡性强且运动灵活性高,不存在侧翻问题,因此球形机器人在星球探索、危险环境探测等领域具有较大优势和广泛应用前景。然而球形机器人具有非完整约束、欠驱动、非链式等特点,导致其运动控制问题非常复杂且常规控制方法无法应用到它的运动控制上,阻碍了球形机器人的应用和发展。对国内外在球形机器人的机构设计、运动学和动力学建模方法以及控制方法等方面的研究进展进行回顾、综述与分析,其中也包括作者所在实验室对BHQ系列球形机器人研究工作的全面回顾;按照驱动方式对球形机器人进行归纳分类,并从运动学建模、动力学建模、开环控制和闭环控制四个方面介绍球形机器人研究的关键技术和发展趋势;最后针对球形机器人的研究进展和发展趋势给出五点结论。 展开更多
关键词 球形机器人:机构设计 运动学模型 动力学模型 控制方法
基于动态图的复杂系统建模方法 预览
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作者 李慧 欧阳鑫玉 《计算机时代》 2019年第8期49-52,56共5页
为解决具有动态拓扑结构的复杂系统的建模问题,提出一种对其进行解释结构建模和数学建模的新方法。该方法基于动态图理论,利用可达矩阵对系统进行强连通子集和区域划分;利用缩减矩阵,对系统的子系统进行级别划分;再通过缩减逆变换求取... 为解决具有动态拓扑结构的复杂系统的建模问题,提出一种对其进行解释结构建模和数学建模的新方法。该方法基于动态图理论,利用可达矩阵对系统进行强连通子集和区域划分;利用缩减矩阵,对系统的子系统进行级别划分;再通过缩减逆变换求取系统的骨架矩阵,并利用得到的骨架矩阵,建立系统的结构模型,该模型就是一个分级动态图。该方法有利于计算机实现,具体算例验证了该方法的有效性。 展开更多
关键词 动态图 复杂系统 解释结构 建模方法
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多级组合型大角度变幅机构的动力学特性 预览
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作者 朱振新 朱建新 +2 位作者 唐博豪 顾林坤 钱奂云 《中南大学学报:自然科学版》 EI CAS CSCD 北大核心 2019年第6期1334-1342,共9页
为研究自主设计的多级组合型大角度变幅机构的动力学特性,采用层次化的求解方法,计算该变幅机构的位置正解方程、位置反解方程、一阶速度雅可比矩阵和二阶加速度海森矩阵,再建立该变幅机构关于主动副的标准形式拉格朗日动力学方程。基于... 为研究自主设计的多级组合型大角度变幅机构的动力学特性,采用层次化的求解方法,计算该变幅机构的位置正解方程、位置反解方程、一阶速度雅可比矩阵和二阶加速度海森矩阵,再建立该变幅机构关于主动副的标准形式拉格朗日动力学方程。基于MATLAB仿真分析2种变幅方式下前液压缸和后液压缸的载荷情况,搭建多级组合型大角度变幅机构的试验平台并进行试验研究。研究结果表明:该动力学模型能够预测多级组合型大角度变幅机构的动力学特性,与后液压缸先收缩再前液压缸收缩的变幅方式相比,前液压缸先收缩再后液压缸收缩的变幅方式具有更优的力学性能。 展开更多
关键词 变幅机构 动力学方程 变幅方式 仿真分析
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机车走行部动态检测方法研究
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作者 陈德君 王雅军 刘长智 《电力机车与城轨车辆》 2019年第6期40-43,78,共5页
机车车载安全防护系统(6A系统)中的机车轮对轴承检测系统是进段后检测机车轴承等运转部件的唯一手段,其不能反映机车实际运行时的工况,检测过程中轴承状态与实际相反,驱动方式操作繁琐。针对此情况,文章对轴承动态检测方法进行深入研究... 机车车载安全防护系统(6A系统)中的机车轮对轴承检测系统是进段后检测机车轴承等运转部件的唯一手段,其不能反映机车实际运行时的工况,检测过程中轴承状态与实际相反,驱动方式操作繁琐。针对此情况,文章对轴承动态检测方法进行深入研究,以提高轴承故障识别的准确度,压减机车停时,实现轴承的高效、精准检测。 展开更多
关键词 机车 走行部 轴承 动态检测 方法
Numerical study on variation characteristics of the unsteady bearing forces of a propeller with an external transverse excitation 预览
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作者 Min-hua Shu Ke Chen +2 位作者 Yun-xiang You Tian-qun Hu Remfeng Wang 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第2期400-412,共13页
The unsteady bearing forces of a propeller can be significantly affected by external transverse excitations.This paper numerically studies the unsteady variation characteristics of the bearing forces of a three-blade ... The unsteady bearing forces of a propeller can be significantly affected by external transverse excitations.This paper numerically studies the unsteady variation characteristics of the bearing forces of a three-blade conventional propeller with external transverse excitations or without excitations.The dynamic mesh method combined with the RANS turbulence model is employed.The numerical simulation shows the frequency response in the frequency domain of KT,Kq under external transverse excitations.The frequency of the response is found always equal to twice of the excitation frequency.If the amplitude of the external transverse excitation keeps constant,the amplitude of the response increases with the in crease of the excitation frequency.If the excitation frequency keeps constant,the amplitude of the response increases with the increase of the excitation amplitude,in a power-law relationship.The pressure distribution can be significantly affected by the external transverse excitation,leading to a high irregularity of the flow field. 展开更多
关键词 EXTERNAL TRANSVERSE EXCITATION UNSTEADY bearing forces EXCITATION frequency PROPELLER dynamic mesh method
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动态法测杨氏模量实验中的双共振峰现象 预览
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作者 洪子昕 郭无筝 白在桥 《物理实验》 2019年第9期48-53,共6页
利用LabVIEW测量了杆的频率响应曲线,确认存在2个相近甚至几乎重叠的共振峰.通过拟合理论曲线,比较精确地定出了2个共振频率以及相应的宽度,还研究了悬挂位置以及悬线对共振频率的影响.
关键词 动态法 杨氏模量 LABVIEW 双共振峰
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Seismic wave input method for three-dimensional soil-structure dynamic interaction analysis based on the substructure of artifi cial boundaries 预览
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作者 Liu Jingbo Tan Hui +2 位作者 Bao Xin Wang Dongyang Li Shutao 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第4期747-758,共12页
The method of inputting the seismic wave determines the accuracy of the simulation of soil-structure dynamic interaction. The wave method is a commonly used approach for seismic wave input, which converts the incident... The method of inputting the seismic wave determines the accuracy of the simulation of soil-structure dynamic interaction. The wave method is a commonly used approach for seismic wave input, which converts the incident wave into equivalent loads on the cutoff boundaries. The wave method has high precision, but the implementation is complicated, especially for three-dimensional models. By deducing another form of equivalent input seismic loads in the fi nite element model, a new seismic wave input method is proposed. In the new method, by imposing the displacements of the free wave fi eld on the nodes of the substructure composed of elements that contain artifi cial boundaries, the equivalent input seismic loads are obtained through dynamic analysis of the substructure. Subsequently, the equivalent input seismic loads are imposed on the artifi cial boundary nodes to complete the seismic wave input and perform seismic analysis of the soil-structure dynamic interaction model. Compared with the wave method, the new method is simplifi ed by avoiding the complex processes of calculating the equivalent input seismic loads. The validity of the new method is verifi ed by the dynamic analysis numerical examples of the homogeneous and layered half space under vertical and oblique incident seismic waves. 展开更多
关键词 soil-structure dynamic interaction SEISMIC WAVE INPUT WAVE method EQUIVALENT INPUT SEISMIC loads SUBSTRUCTURE of artifi cial boundaries
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前列腺癌的演化动力学模型以及治疗策略的优化 预览
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作者 高鑫 史书毓 李方廷 《北京大学学报:自然科学版》 CAS CSCD 北大核心 2019年第6期987-994,共8页
前列腺癌是男性常见的恶性肿瘤。临床上常用的干扰雄激素的治疗药物是阿比特龙,但长期高剂量的阿比特龙治疗常导致患者前列腺肿瘤细胞进化至药物抵抗。为了揭示前列腺癌发展的动力学机制,本文引入给药剂量因素,建立二变量的肿瘤演化定... 前列腺癌是男性常见的恶性肿瘤。临床上常用的干扰雄激素的治疗药物是阿比特龙,但长期高剂量的阿比特龙治疗常导致患者前列腺肿瘤细胞进化至药物抵抗。为了揭示前列腺癌发展的动力学机制,本文引入给药剂量因素,建立二变量的肿瘤演化定量模型。通过分析固定给药和适应性给药策略的动力学性质,并绘制势能景观图,从动力学角度展示适应性给药策略的优势,揭示高剂量药物导致体系演化为不可逆药物抵抗状态的动力学机理。此外还构建治疗策略的评分体系,以便优化治疗策略。 展开更多
关键词 前列腺癌 阿比特龙 药物抵抗 动力学模型 策略优化
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Quantitative division of succession and spatial patterns among different stand developmental stages in Changbai Mountains
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作者 GONG Zhi-wen KANG Xin-gang GU Li 《山地科学学报:英文版》 SCIE CSCD 2019年第9期2063-2078,共16页
Broadleaf-Korean pine forests exhibit high species richness and distinctive species composition, which are currently becoming more dominant among natural forests in Changbai Mountains of northeastern China. Understand... Broadleaf-Korean pine forests exhibit high species richness and distinctive species composition, which are currently becoming more dominant among natural forests in Changbai Mountains of northeastern China. Understanding the ecological process of restored vegetation is quite important for ecosystem reconstruction. Distinguishing stand development stages and analyzing the dynamic spatial patterns could provide insights into significant community coexistence mechanisms. In the present study, eight permanent study areas were established according to the substituting space for time method in Changbai Mountains of north-eastern China. The optimal division method was used to quantify the successional series into different stand development stages, and the point pattern analysis method(L(r) function) was used to analyse the dynamic changes in spatial patterns and interspecific associations. Our results suggested that:(1) The stand development process was divided into five stages: the first three stages were poplar-birch secondary forests in different stages of recovery, the fourth stage was thespruce-fir mixed forest, and the last stage was the primary broadleaf-Korean pine forest;(2) The spatial pattern showed an aggregated distribution at a small scale and changed to a random distribution as the scale increased in poplar-birch secondary forests, but the spatial pattern appeared to be randomly distributed in spruce-fir mixed forest and broadleafKorean pine forest;(3) The interspecific associations between pioneer species and climax species changed from negative to positive among the different stand stages, and environmental resources were shared among these species. Interspecific differences in shade tolerance among the tree species were key determinants of forest dynamics and structure. Our study is vital to the understanding of the forest development;thus, the spatial change features should receive greater attention when forest management is being planned and restoration strategies are being developed for the Changba 展开更多
关键词 Dynamic spatial patterns INTERSPECIFIC association Optimal DIVISION method STAND DEVELOPMENTAL STAGES Space for time substitution
基于动态参数的仿真模型验证方法 预览
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作者 孙茂义 王志恒 《计算机仿真》 北大核心 2019年第3期261-263,417共4页
模型可信度是仿真是否有效的关键环节,合适的验证方法是仿真模型可信度的重要保证。为了检验模型可信度,围绕基于动态性能一致性分析的仿真模型验证方法,从基本原理、计算步骤、适用范围等方面,对各类模型验证方法进行了归纳总结,并进... 模型可信度是仿真是否有效的关键环节,合适的验证方法是仿真模型可信度的重要保证。为了检验模型可信度,围绕基于动态性能一致性分析的仿真模型验证方法,从基本原理、计算步骤、适用范围等方面,对各类模型验证方法进行了归纳总结,并进行了实例验证,仿真数据与实际数据一致性好,模型可信度较高。结果表明,基于动态参数的仿真模型验证方法科学合理。 展开更多
关键词 动态参数 仿真模型 验证方法
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