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LINDe-ming JINHong-zhang LIQi WUHong-mei 《船舶与海洋工程学报》2004,3(2):69-72
Now the research on the complex system is a hot spot. Brittleness is one of the basic characteristics of a complex system. In a complex system, after one of subsystems is struck to be collapsed, the whole system will collapse. Meanwhile, cellular automata is a discrete dynamic system. When the rule is given, the cellular automata could be defined. Then it can imitate the complex action. Cellular automata is used to simulate the brittleness action in this study. Entropy was used to analyze the action and get the rule. Then,three normal brittleness models were given. The result shows that the brittleness of complex system is existent and in addition some important behavior mode of complex system brittleness has been achieved. 相似文献
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系统观测目标误差渗透着系统误差和随机误差,系统误差和随机误差的分离与溯源理论和应用一直是误差分析的难点和热点。文中基于系统误差和随机误差的互相关系与传递特征,提出了以传递函数为基础的误差传递模型,并基于该模型,将复杂系统划分为若干个子系统,分析了各子系统在观测目标误差中的主次作用( primary and secondary position a-nalysis,PSPA)。算例表明,该理论能够分析得出引起观测误差灵敏度较高的子系统,这对于误差溯源、分析和控制误差,提高观测目标的精度具有一定的指导意义。 相似文献
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Research on basic characteristics of complex system brittleness 总被引:2,自引:0,他引:2
JINHong-zhang GUOJian WEIQi LINDe-ming LIQi 《船舶与海洋工程学报》2004,3(1):57-63
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基于复合建模方法的轴系扭转振动特性及仿真 总被引:3,自引:3,他引:0
为了提高主机轴系计算准确度,本文提出了一种新型的主机轴系建模方法,该方法将主机轴系分为连续子系统和离散子系统。推进轴段如螺旋桨轴、中间轴、螺旋桨及法兰划分为连续子系统,柴油机曲轴端划分为离散子系统。分别应用波分析法和多自由度动力特性分析,得到连续子系统和离散子系统的控制方程,同时通过边界条件将两个子系统动态刚度矩阵连接,推导出全局控制方程。对某型主机轴系扭转振动计算进行了仿真分析,并与传统建模方法比较。从计算结果可知,在高阶模态上,新型建模方法计算更精确,更接近真实振动状态,同时在保证相同计算精度的情况下,新型建模计算方法计算时间和计算资源占用较少,相对更为简便。同时,新型建模方法克服了当模态节点集中于轴段时,传统建模方法由于将轴系等效为一至两个质量单元而引起的节点偏移所带来的误差,这在实际主机轴系计算特别是长推进轴和刚度较低的轴系中具有重要意义。 相似文献
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将复杂系统脆性引用到船舶电力系统研究中,通过对船舶电力系统脆性概率熵、脆性综合概率熵、脆性风险熵、脆性综合风险熵定义和研究来分析船舶电力系统的脆性。通过仿真表明以上定义能很好地评价船舶电力系统的脆性。 相似文献
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机械系统中激励源传出的波将沿传输路径衰减,并会经由含源子系统边界传递出去,因而只有输入功率的残余部分以混响场的形式消耗在该子系统内。为提高应用统计能量分析法(SEA)计算振动噪声的精度,对上述过程进行深入分析,并以一个简单梁系为例,给出传入该梁系的输入功率的表达式。分析结果表明,传输波对计算结果的影响随着损耗因子的增加而增加。同时,分析将传输波的影响计入诸如舰船这种复杂空间结构的实际可行性。估算结果表明,仅对含源子结构考虑传输波的影响是充分可行的。 相似文献
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生态系统分析方法与农业科技示范园规划 总被引:1,自引:0,他引:1
现代农业科技园区建设规划目标是实现经济、生态、社会效益的协调,园区是一个复合的人工生态系统。在规划过程中的一个核心环节就是进行生态系统分析,并在分析的基础上进行生态系统设计。文中讨论了农业园区生态系统分析的目标、步骤,并提出了科技园区的复合生态系统由4个子系统组成,分别是:安全永续的生态环境资源子系统、清洁循环的生态产业经济子系统、自然和谐生态人类住区子系统、先进高效的科技支持和管理决策子系统。 相似文献
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ZHAOGuo-liang MENGHao 《船舶与海洋工程学报》2004,3(2):63-68
The problem of stabilization control of underactuated surface vessels with two independent control inputs is in vestigated inthis paper. Through transformation, a cascade property of the system is revealed. And the original nonlinear system could be divided into two subsystems: a linear subsystem and a nonlinear subsystem. The stabilization laws are derived for the two subsystems separately. A smooth time - varying feedback stabilization law with exponentially convergence rate is obtained. The proposed stabilization law guarantees all the system states converge to the equilibrium exponentially. The aim of stabilization control of underactuated surface vessels is achieved. At last, the effectiveness of the proposed algorithm is illustrated by simulation tests. 相似文献
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In the normal operation condition, a conventional square-root cubature Kalman filter (SRCKF) gives sufficiently good estimation results. However, if the measurements are not reliable, the SRCKF may give inaccurate results and diverges by time. This study introduces an adaptive SRCKF algorithm with the filter gain correction for the case of measurement malfunctions. By proposing a switching criterion, an optimal filter is selected from the adaptive and conventional SRCKF according to the measurement quality. A subsystem soft fault detection algorithm is built with the filter residual. Utilizing a clear subsystem fault coefficient, the faulty subsystem is isolated as a result of the system reconstruction. In order to improve the performance of the multi-sensor system, a hybrid fusion algorithm is presented based on the adaptive SRCKF. The state and error covariance matrix are also predicted by the priori fusion estimates, and are updated by the predicted and estimated information of subsystems. The proposed algorithms were applied to the vessel dynamic positioning system simulation. They were compared with normal SRCKF and local estimation weighted fusion algorithm. The simulation results show that the presented adaptive SRCKF improves the robustness of subsystem filtering, and the hybrid fusion algorithm has the better performance. The simulation verifies the effectiveness of the proposed algorithms. 相似文献
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WANGSan-de YANGDe-sen SHISheng-guo FANGEr-zheng 《船舶与海洋工程学报》2005,4(1):54-59
In this paper, the vibration and sound radiation of the underwater complex shell-structure which is the cylindrical shell with hemi-spherical shell on the ends are studied by statistical energy analysis (SEA). The whole shell-structure is divided into the four subsystems, and the SEA physical model and power flow balance equations among these subsystems are established. The similitude relations of input power, coupling loss factor and modal density of the subsystems between the complex shell-structure and its scaled-down model are analyzed. According to the similitude theory and power flow balance equations, when the immerged shell-structures are excited, the similar relations of spatially averaged vibration response and underwater radiating sound power are established for the complex shell-structure and its scaled-down model. 相似文献
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由于舰艇系统的复杂性,对全舰进行生命力评估需要将其分解到下一级或几级具体的子系统,通过系统生命力指标得到全舰生命力的描述。传统的模糊层次分析法(FAHP)存在两个缺陷:一方面可能导致计算结果错误;另一方面也可能造成无法计算指标权重,使模糊层次分析法的使用范围受到限制。采用一种改进的模糊层次分析法,建立三角模糊判断矩阵,确定各层次间相关因素的权重,并计算得到各子系统的权重排序。实例证明,该模型的评估结果反映了舰船系统的实际工况。根据该模型计算的评估结果,可以更好地发现舰艇生命力系统的薄弱环节,为损管决策提供科学的理论依据和方法。 相似文献
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基于元胞自动机的舰船电力系统脆性建模 总被引:3,自引:1,他引:2
为了分析复杂舰船电力系统的脆性,提高系统的可靠性,以及评价系统的脆性程度,基于熵理论,给出了包括系统自身熵变、脆性联系熵、负熵的舰船电力系统脆性熵的定义,以及舰船电力系统的脆性概率熵、脆性综合概率熵、脆性风险熵和脆性综合风险熵的定义。采用一维扩展元胞自动机(CA),对舰船电力系统脆性熵变和脆性评价分别制定了元胞自动机的演化规则,对舰船电力系统进行脆性建模,以元胞自动机构行序列形式给出了脆性建模的结果,模拟了复杂舰船电力系统在受到内外干扰后脆性演变过程。采用元胞自动机建模可避免求解复杂的微分方程组,使求解简单直观。 相似文献
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