首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 265 毫秒
1.
花卉植物形态与生长可视化仿真研究   总被引:4,自引:0,他引:4  
花卉植物形态结构复杂,叶片、花瓣等组织器官的可视化建模和生长仿真成为虚拟花卉的研究瓶颈。基于花卉图像和植物生态学,提出一种通用的草本花卉形态结构建模和生长可视化仿真算法。结合花卉图像信息和双三次Bezier曲面模拟组织器官的形态,利用定义的花卉植物拓扑结构建立单株花卉。为了忠于植物生长特性,采用Logistic方程模拟叶片和花瓣的生长过程。通过郁金香、石竹、茉莉等多种代表性草本花卉植物验证了算法的有效性,模拟的花卉逼真自然。  相似文献   

2.
任正云  张红 《控制工程》2006,13(2):141-144
提出了基于二阶非振荡及振荡加纯滞后的预测PID控制器的结构形式。这种控制器既具有PID控制器的优点;简单的结构形式、良好的鲁棒性和可靠性,又具有预测的功能;即可以根据以前的控制作用来预测以后的控制作用。通过仿真表明:在干扰、噪音存在和模型失配的情况下,预测PID控制器具有良好的控制性能,特别适合大纯滞后系统的控制。同时运用Monte-Carlo方法分析了其鲁棒稳定性,结果表明:它是一种值得在实际工程中推广应用的新型控制器。  相似文献   

3.
植物与昆虫间有史以来就存在战争,但胜利始终偏向昆虫一方.昆虫采用侦察手段获得了优势,受损害方之一是普通的芹菜,当芹菜受到毛虫攻击时,会像许多其他植物一样释放出化学"求救"信号--茉莉属化合物和水杨酸盐,SOS信号还可以作为植物自身的化学武器库进行战争准备.当这种信号成功被毛虫获截获,它们会分泌出一种胃酶和破坏性毒素,分泌这些毒素只是企图增加自己一份食物而已.  相似文献   

4.
预测蛋白质二级结构,是当今生物信息学中一个难以解决的问题.由于预测蛋白质二级结构的精度在蛋白质结构研究中起到非常重要的作用,因此在基于KDTICM理论基础上,提出一种基于混合SVM方法的蛋白质二级结构预测算法.该算法有效地利用蛋白质的物化属性和PSI-SEARCH生成的位置特异性打分矩阵作为双层SVM的输入,从而大大地提高了蛋白质二级结构预测的精度.实验比较分析表明,新算法的预测精度和普适性明显优于目前其他典型的预测方法.  相似文献   

5.
对于模式识别系统而言,不同的训练样本在建立分类模型时所起的作用不同,以往的蛋白质关联结构预测方法都是从样本集中随机选取一部分样本作为分类器的训练样本,这将降低蛋白质关联结构分类器的预测精度,为改善训练样本对预测精度的影响,本文提出一种基于样本选择及BP神经网络的蛋白质关联结构预测方法.该方法选取与蛋白质关联结构相关的属性进行编码,并采用样本选择技术从编码后的样本集中选取一定的高质量样本构建预测模型,从而有效地对蛋白质关联结构进行预测.本文根据提出的编码方式对从蛋白质数据库PDB中获取的200个蛋白质进行编码,然后用最近邻算法选择训练样本,并使用BP神经网络建立相应的预测模型.实验结果表明,进行训练样本选择能够有效提高蛋白质关联结构的预测精度.  相似文献   

6.
针对具有执行器饱和特征的不确定系统,提出了一种带有状态观测器的新型预测控制器设计方法.该方法在滚动优化的每一步,采用带有饱和特性的反馈控制结构得到一个最优控制律.使无穷时域性能指标最小.考虑在状态不完全已知的情况下,设计了带有状态观测器的预测控制器,并通过观测器参数调整使闭环系统渐近稳定.通过仿真实验验证了所设计控制器的有效性.  相似文献   

7.
陈俊  陈雄  薛海峰  于溪 《计算机仿真》2013,30(1):78-81,187
研究了一种新型复合结构燃气舵动力学特性问题。针对传统采用钨渗铜材料的燃气舵重量大、价格贵、工作效率低等问题,提出了一种新型的由高温合金钢(30CrMnSiA)骨架和耐高温的碳/酚醛复合材料模压制成的复合结构燃气舵。利用Ansys软件对新型复合结构燃气舵的三种不同骨架结构进行了模态分析及瞬态动应力分析。得到了三种舵片的固有频率及相应振型以及在固定冲击载荷作用下燃气舵的瞬态动应力响应曲线及变形响应特性。仿真研究表明,新型复合结构燃气舵具有良好的尺寸稳定性、低密度、价格低廉等优点,且结构动力学特性满足实际工程要求。  相似文献   

8.
基于时空图卷积循环神经网络的交通流预测   总被引:1,自引:0,他引:1  
针对交通流预测模型中路网空间结构刻画和交通流时空特性挖掘不充分的问题,构建一种新型的有向时空图,通过定义节点相对临近度来表征路网结构关系,通过学习邻域节点对预测节点的影响权重来表征节点间时空维度的作用关系,从而能更好表达交通流的时空特性.将时空图作为预测模型的输入,采用图卷积获取交通流数据空间依赖关系,采用门控循环神经网络获取交通流数据的时空依赖关系,建立一种基于时空图卷积循环神经网络的交通流预测模型(STG-CRNN).在美国公路交通数据集上对模型预测效果进行验证,其结果表明:STG-CRNN模型的预测结果在平均绝对误差、均方根误差和平均绝对百分误差方面,均优于自回归移动平均模型、门控循环单元模型,以及扩散卷积循环神经网络模型.  相似文献   

9.
基于液体智能材料的被动力反馈数据手套   总被引:1,自引:0,他引:1  
王爱民  戴金桥 《测控技术》2007,26(11):10-12
磁流变液体是一种液体智能材料,在磁场作用下,其流变学特性能在毫秒级时间内发生剧烈的变化.利用磁流变液体的特殊性能,设计了一种新型力反馈数据手套.详细地阐述了组成该新型数据手套的力反馈装置,包括其原理、结构和控制电路等.在遥操作机器人系统中,利用这种新型力反馈数据手套,操作者能够在本地虚拟环境中,充分获取和控制机器人与环境之间相互作用,实现良好的力觉临场感.  相似文献   

10.
在可见光探测器结构优化设计问题的研究中,为保证可见光探测器在交变力作用下的成像精度,设计了一种新型可见光探测器结构.通过材料选取和结构的设计,提高了可见光探测器的整体刚度.建立有限元模型,分析计算了结构在载荷作用下的变形量,用以检验所设计的可见光探测器结构的刚度性能;对模型进行了模态分析,可验证结构固有频率远离系统成像帧频,能够避免因共振引起的成像质量下降.最后,通过设计实验的方法来验证可见光探测器结构的刚度性能及沿Y方向的固有频率.实验结果表明可见光探测器设计方案满足各项指标要求.  相似文献   

11.
大滞后系统数字内模控制器的设计及仿真研究   总被引:1,自引:0,他引:1  
对于带有严重纯滞后的工业对象,目前的控制策略是史密斯预估控制,或者是内模控制,他们都要使用连续域的数学模型。而在目前的对象辨识中,辨识出来的对象往往是离散形式的数学模型,这就需要连续到离散模型的转换。在转换的过程中,难免会出现一些偏差,使得辨识出来本来就不是很精确的数学模型变得更加偏离实际系统,进而使得控制效果不尽理想。该文针对这种情况,提出一种基于离散对象模型的数字内模控制(DIMC)算法。该算法直接利用对象辨识给出的离散模型,导出离散的内模控制器,直接用于工业生产的计算机控制。仿真结果表明,该方法能克服被控对象参数变化和时滞变化对控制性能的影响,具有很强的鲁棒性能。  相似文献   

12.
The bottling of beverages is carried out in complex plants that consist of several machines and material flows. To realize an efficient bottling process and high quality products, operators try to avoid plant downtimes. With actual non-productive times of between 10% and 60%, the operators require diagnosis tools that allow them to locate plant components that cause downtime by exploiting automatically acquired machine data.This paper presents a model-based solution for automatic fault diagnosis in bottling plants. There are currently only a few plant-specific solutions (based on statistical calculations or artificial neural networks) for automatic bottling plant diagnosis. In order to develop a customizable solution, we followed the model-based diagnosis approach which allows the automatic generation of diagnosis solutions for individual plants. The existing stochastic and discrete-event models for bottling plants are not adequate for model-based diagnosis. Therefore, we developed new first-principle models for the relevant plant components, validated them numerically, and abstracted them to qualitative diagnosis models. Based on the diagnosis engine OCC’M Raz’r, application systems for two real plants and one virtual plant (based on discrete-event simulation) were generated and evaluated. Compared to the reasons for downtime identified by experts, we obtained up to 87.1% of compliant diagnosis results. The diagnosis solution was tested by practitioners and judged as a useful tool for plant optimization.  相似文献   

13.
Plant three-dimensional (3D) computer-aided design (CAD) models typically consist of logical configuration, equipment specifications and ports, and 3D shapes. Because 3D CAD models are used as master information throughout a plant’s entire lifecycle and many stakeholders are involved in such lifecycle, providing a method for sharing plant 3D CAD models among various stakeholders is very important. Standard 15926 from the International Organization for Standardization (ISO 15926) is a family of standards that is intended to support the sharing and integrating of all information during the life of a process plant. Therefore it is important for ISO 15926 to support plant 3D CAD models. In order to address this issue, this study investigates a standardized method to exchange plant 3D CAD models using ISO 15926. Information requirements regarding plant 3D CAD models are established, and then ISO 15926 reference data (classes, attributes, and templates) are extended to cover information requirements. For demonstration of the proposed method, we developed a prototype platform where plant 3D CAD models in ISO 15926 are loaded and retrieved.  相似文献   

14.
The optimal control for a high-order model of the plant is approximated by some functions obtained from two low-order models, the second being the sensitivity model of the first. The resuiting system is optimally sensitive with respect to the change of model order. The method is aimed at improving the "low-order design" in critical cases when the plant order is too high for the iterative optimization procedures to be practical.  相似文献   

15.
A study was conducted to evaluate the use of discrete event simulation (DES) to predict human performance in a nuclear power plant control room environment. Computer simulation models of two disturbance scenarios were built using a simulation software program, Micro Saint. In parallel, data were also collected at a full-scope training simulator at the Halden man-machine laboratory (HAMMLAB) in Halden, Norway, using crews of commercial nuclear power plant operators from the Loviisa nuclear power plant in Loviisa, Finland. Comparisons were made between predicted operator performance data generated by the simulation models and crew performance in the HAMMLAB experiment to determine the degree of agreement between the simulated data and the data from operators. The models were then used to extrapolate advanced control room conditions and alarm systems that were not tested in the HAMMLAB experiment. This report summarizes these findings and provides recommendations for improvements to the DES approach for use by a regulatory agency.  相似文献   

16.
乙苯装置工艺仿真培训系统开发   总被引:1,自引:0,他引:1  
以8万吨/年苯乙烯乙苯装置仿真培训系统的开发,对该装置工艺复杂,涉及组分多,无法应用经验模型仿真,故采用严格的机理模型,开发了多个化学单元设备的仿真模块,并采用序贯模块法开发了整个系统的仿真模型,通过有效的计算法,保证仿真速度的实时性和外部特性的逼真。通过验证仿真系统能较真实地反映装置的开停车、生产及事故状态的动态效果,可用于培训操作工,也可用于专家研究生产工艺的优化、诊断和控制方案,在实践中效果良好。  相似文献   

17.
Plant structure,representing the physical link among different organs,includes many similar substructures.In this paper,a new method is presented to construct plant architectural models of most plant species.The plant structure is decomposed into a stem,a set of lateral substructures and a terminal substructure,which is called substructure decomposition;then based on substructure decomposition,the plant structures are expressed in an iterative way;and further the derivative formula is employed to compute the number of organs in plant structures to get the geometrical sizes of 3D plant organs by borrowing Hydraulic Model.Using 3D organs,a substructure library is built.Based on the substructures stored in substructure library,one can construct 3D plant structure according to certain topological and geometrical rules.The experiments with different plant species are included in this paper to demonstrate the validity of the new method for constructing plant structures.The experimental results show that the approach follows botanical knowledge with high efficiency in constructing plant structures of most plant species.In addition,this method enables users to check the detail information of plant structure.  相似文献   

18.
Assessing forage quantity and quality through remote sensing can facilitate grassland and pasture management. However, the high spatial and temporal variability of canopy conditions may limit the predictive accuracy of models based on reflectance measurements. The objective of this work was to develop this type of models, and to challenge their capacity to predict plant properties under a wide range of environmental conditions. We manipulated Paspalum dilatatum canopies through different stress treatments (flooding, drought, nutrient availability, and control) and by artificially varying the amount of senescent biomass. We measured canopy reflectance and constructed simple models, based on either normalized vegetation indices or a few selected wavebands, to estimate biomass and two variables related to forage quality: proportion of photosynthetic vegetation and biomass C:N ratio. General models satisfactorily predicted plant properties for the whole set of environmental conditions, but failed under specific conditions such as drought (for estimates of plant biomass), fertilization (for estimates of C:N ratio), and different levels of senescent tillers (for estimates of the proportion of photosynthetic vegetation). Where general models failed, specific models, based on different bands, achieved satisfactory accuracy. The general models performed better when based on a few selected bands than when based on two-band vegetation indices, having better accuracy (higher R2) and parsimony (lower BIC). However specific models performed similarly for both approaches (similar R2 and BIC). These results indicate that these plant properties can be predicted from reflectance information under a broad range of conditions, but not for some particular conditions, where ancillary data or more complex models are probably needed to increase predictive accuracy.  相似文献   

19.
Scheduling control of a deaerator plant   总被引:1,自引:0,他引:1  
The deaerator of a power plant may experience severe two-phase steam/water problems especially during restart of the power plant following a unit trip. Unless suitable control strategies are adopted, cavitation in the suction area and choking in the deaerator can occur. Cavitation can cause expensive damage to the feedwater pumps, while choking will interrupt the operation of the deaerator. These all lead to failure of the restart. Some models and control schemes have been developed in recent years to study cavitation. A model that can predict the transient behaviour of the deaerator plant for possible cavitation and choking has been developed. In this paper, a scheduling control for deaerator operation based on this model is proposed. This scheme utilises operational status and process variables to predict possible cavitation or choking, and then takes the necessary action to avoid the loss of head in the suction area and high velocity of steam in the deaerator equalisers. The simulation results show that the control scheme will ensure safe operation, even during restart of the power plant.  相似文献   

20.
The simulation of sewage systems and wastewater treatment plants is strategic for assessing the effect of new dwellings on the existing water facilities. This paper introduces an integrated framework made by a land use change model, a sewage system simulator, and a wastewater treatment plant simulator. This is a complex system since each element is characterized by different dynamics. The land use change model simulates the annual expansion of an urban area according to planners’ guidelines; the sewage system simulator investigates the response of the drainage system to the expansion. The wastewater treatment plant is simulated in order to assess the impact of the new outflows on the existing plant. The three models are integrated into a Simulink model. Two components of the developed framework are based on models well established in literature. The proposed framework is tested on a simple case study of a small town located in south west of Scotland.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号