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采用圆柱体胞模型分析方法,对球形微孔洞在不同加载应变率条件下的动力学响应行为进行了有限元分析,计算结果表明:在微孔洞稳定增长阶段,惯性对微孔洞的快速增长起着关键性作用,其它因素的影响基本可以忽略,微孔洞半径增长率与平均应力的平方根成正比。提出了一个微孔洞增长惯性机制的损伤度演化方程,结合逾渗软化函数描述微孔洞聚集行为,从而构建了一个新的动态拉伸断裂模型,并通过自定义材料模型子程序,把断裂模型嵌入LS-DYNA程序中,对无氧铜平板撞击层裂实验进行了数值模拟研究,计算结果与实验结果的比较令人满意,初步检验了新模型的实用性。 相似文献
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通过数学方法较为精确地建立了吸收式制冷机需满足负荷要求的数学模型,确立了蒸发器冷冻水出口温度与室外温度之间的关系式。进而建立了吸收式出水温度控制系统的动态特性模型,并采用并联程序法对水温控制系统进行仿真。 相似文献
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针对目前应用于列车驾驶仿真平台中的模拟双针气压表控制系统的硬件结构及其控制策略进行了研究;以C8051F410单片机和双电机驱动控制模块BA6239为核心设计开发了表针电机驱动系统,提出了基于PWM控制技术的转速闭环控制策略;系统能够自动计算电机控制模型参数从而得到转速与PWM控制电压的关系,并通过引入自适应模糊PI转速调节器,减小系统及计算误差,提高动态响应精度;测试结果表明,基于自适应模糊控制的模拟双针气压表能够达到真车气压表的动作要求,为构建列车驾驶仿真平台提供了可靠的硬件支持。 相似文献
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电站锅炉的烟气脱硝过程同其他电站热工过程一样存在一定迟延性和惯性;根据目前烟气脱硝系统运行情况,总结分析了氮氧化物(NOX)排放控制过程的特点、影响因素以及控制系统;为解决锅炉运行过程中系统呈现出的大迟延和大惯性问题对整个烟气脱硝控制品质产生的影响,以及实现系统的稳定性和快速性,在原有的串级回路系统中,加入了Smith预估补偿控制器提前预估系统的动态特性并对其进行补偿;根据烟气脱硝系统对象的传递函数,设计了Smith预估补偿控制系统,采用Matlab中的Simulink对控制系统的对象和改进前后的控制系统响应曲线进行仿真分析,可以看出改进后系统动态品质变好,系统的快速性和稳定性也明显提高。 相似文献
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为对静脉输液过程的滴速自动控制系统进行设计和分析,对此类型系统进行建模和仿真研究;通过实验数据拟合出输液过程的静态模型,进而得到非线性的动态模型;采用一阶惯性环节对执行机构的动态特性进行描述,采用定积分对基于红外光电对管的滴速检测环节进行建模;在静态工作点对过程模型进行基于增量法的近似线性化处理,对给定值小范围变化的情况设计了PID控制律,对给定值大范围变化的情况采用先开环控制后闭环控制的控制策略;仿真结果表明,该模型能较准确反映被控过程和控制系统的特性,对控制系统的实施有较好的参考价值。 相似文献
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单轴恒速回热燃气轮机的变工况解析特性及初步经济分析 总被引:2,自引:0,他引:2
本文给出单轴恒速回热燃气轮机变工况特性的显式解析解,并且总结了其变工况的典型情况;发现当对所有参数都用与其设计值的比值表达时,燃气轮机效率可以基本总结为单一曲线,并定量论证了恒速单轴燃气轮机采用回热后变工况效率反而相对有所下降。利用得出的解析解,还对采用回热的经济评价给出了初步分析,给出了采用回热合适与否的判别公式。 相似文献
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A new approach to design control systems for an industrial furnace with flue gas recirculation (FGR) is presented. To facilitate the control system design, a linear dynamic model is needed for the furnace. Full-scale computational fluid dynamics (CFD) simulations are used to generate the required small signal input and output data sets. Subsequently, a least squares based system identification technique is used to obtained the linear dynamic models. After model validation, feedback controller is designed based on these linear dynamic models. Finally, the performance of the designed closed-loop control system is also evaluated using both linear dynamic model and full-scale nonlinear CFD model. The comparison shows that the control system designed using the proposed approach can minimize the deviation of nitric oxides (NO) emission from the design point by minimize the dynamic NO formation, hence to prevent any excessive NO formation in the combustion process when the system subjects to disturbances. 相似文献
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In this paper, the nonlinear dynamic characteristics of a FGR furnace have been analysed around the furnace design point. Based on the steady-state results of full-scale nonlinear CFD simulations, the maximal allowable range on the variations of the furnace inputs can be determined, once for the maximal error bound between nonlinear system and its linear counterpart is specified. It is interesting to note that for a reheating furnace, the nonlinearities associated with the heat load are less severe than that associated with NO emission. With due consideration of the established input signal linear ranges, the linearized dynamic models of the furnace are derived by applying system identification technologies using the data generated from the CFD simulations. Analysis and validation of the models are also carried out. It is concluded that this technique is applicable to weak nonlinear systems around the design point. The results of the analysis provide additional insights on the nature of the nonlinearities as well as guidelines for selecting the input amplitude if system identification techniques are used. So long as the amplitudes of the probing signals satisfy the respective input constraints, the obtained linearized models will be applicable around the design point. Subsequently, these models can be used to design feedback controllers to maintain the furnace operated around the design point. 相似文献
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冷凝器动态性能仿真研究 总被引:2,自引:0,他引:2
本文应用移动边界法(MB)对冷凝器建立了动态仿真数学模型,模型体现了冷凝器内各个相区长度随时间的变化,模型最终可以化为常微分线性方程组的形式,在求解上更为方便且兼顾了仿真的效率和精度,模型可提供冷凝器详细的性能参数;研究了在系统不同的控制参数阶跃情况下冷凝器的动态响应,获得了冷凝器的动态特性,冷凝器的动态特性是冷凝器动态优化设计和编制系统控制规律的基础。本文中的冷凝器建模方法适合于系统级仿真研究。 相似文献
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建立了双级压缩空气源热泵的动态仿真模型。对压缩机、膨胀阀以及换热器分别建立部件模型。由于压缩机和膨胀阀的热惯性较小,所以采用稳态模型来描述。蒸发器和冷凝器部件建立动态模型时,针对制冷剂侧、管壁、以及载冷剂侧三个控制容积,分别建立控制方程。最后,通过参数耦合,建立系统仿真模型。 相似文献
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Marine propulsion unit (MPU) is one of the dominant vibration and noise sources onboard ship. Its vibration can be attenuated effectively by isolating MPU with low-frequency mounting system. But this is difficult to implement due to the stringent requirement of MPU alignment with the propulsion shafting. In this paper a novel air spring mounting system (ASMS) for propulsion system is proposed consisting of air spring subsystem, alignment control subsystem and safety protection subsystem. The load distribution optimization method and dynamic model of ASMS are presented. The factors that affect system stability and natural frequencies are analyzed, as well as the design measures to enhance system performance. A theoretical model is presented to estimate the isolation effect of ASMS. The monitoring model of alignment between MPU and propulsion shafting is established, followed by the alignment control algorithm and converge rule which assures the fast and uniform convergence of both air springs? load distribution and alignment control process. Safety protection mechanism is designed to ensure that the MPU can operate safely in case of ASMS failure or other extreme circumstances. A scaled ASMS prototype is manufactured and tested on a special experimental setup. Experimental results validate the effectiveness of theoretical models and show that the performance of ASMS satisfies the operation requirements of MPU. 相似文献