基于Simulink的异步电机拖动系统动态仿真

在Simulink平台的基础上,构建了异步电机拖动系统仿真模型,对异步电机的机械特性、三级串电阻启动和能耗制动进行了试验.仿真结果有效地体现了拖动系统的基本原理和规律.     

基于Simulink的异步电机拖动系统动态仿真

在Simulink平台的基础上,构建了异步电机拖动系统仿真模型,对异步电机的机械特性、三级串电阻启动和能耗制动进行了试验.仿真结果有效地体现了拖动系统的基本原理和规律.     

高温高压蒸汽改性落叶松木材力学性能预测模型的建立

利用RBF神经网络和支持向量机两种算法建模,分析落叶松高温高压蒸汽改性工艺参数与其力学性能关系;以落叶松热处理的温度、相对湿度、处理时间3个主要工艺参数作为网络输入,建立了RBF神经网络和支持向量机预测模型,并对两者进行比较。结果表明:支持向量机模型,在网络建立结构、收敛速度和泛化能力上更具优势。     

小型船舶综合全电力推进实验平台的研制

介绍了小型船舶综合电力推进实验平台的机械和电气设计方案及相应的系统控制模型．平台主要由推进、模拟负载和测量三个子系统组成．推进系统主要由变频驱动装置、操作监控台、推进电机构成;模拟负载系统由交流电动机、四象限变频驱动装置、监控系统及负载模型软件组成;测量系统由转速传感器、转矩传感器以及PLC组成．     

基于神经网络的机器人驱动系统数学模型辨识

以轮式移动机器人驱动系统为主要研究对象,提出一种基于神经网络的分析与试验相结合的建模方法。该方法在分析理想直流电动机数学模型的基础上,采用串一并行辨识结构的神经网络确定系统输出与输入的关系,实现了机器人驱动系统的数学模型辨识。最后,通过试验证明了该方法的有效性,为未采工、农业等领域机器人的精确运动和动力控制的研究提供了技术支持。     

轻便型摩托结构动态分析计算模型

运用模态综合技术，建立了计及轻便型摩托车身弹性的具有１０个自由度的整车“刚－弹”组合力学模型；同时，为了检验车体弹性对整车振动的贡献。又建立了一个不计车体弹性的具有５个自由度的整车“刚－刚”组合力学模型。     

Predicting soil chemical composition and other soil parameters from field observations using a neural network

Characterisation of soils in relation to a particular use or classification system is often heavily dependant on their chemical properties, requiring detailed, time-consuming and often expensive laboratory analysis. If it were possible to gain even partial knowledge of the status of a soil in terms of parameters that normally require this kind of analysis, but instead to be able to do so, based on simple field observation information, then an observer in the field would be able to more effectively characterise the soil they were investigating. Using data from the NSIS (National Soil Inventory of Scotland) database, we have produced a neural network model that predicts a wide range of soil chemical and physical properties with varying accuracy levels. This neural network model is supplied with field observation inputs that require only a limited degree of training to determine, and limited field equipment. These inputs include colour, texture classification and site information (topography, climate and vegetation). Several model outputs are predicted with a high degree of accuracy, including organic matter content, Mg, Ca, Ni, total base saturation and pH amongst others. We discuss the outputs that are predicted well and those that are not in terms of their relationships to the model input parameters and their significance within the soil, and consider possible uses and limitations of this prediction system.     

Physical properties determining self-organization of motors and microtubules

In eukaryotic cells, microtubules and their associated motor proteins can be organized into various large-scale patterns. Using a simplified experimental system combined with computer simulations, we examined how the concentrations and kinetic parameters of the motors contribute to their collective behavior. We observed self-organization of generic steady-state structures such as asters, vortices, and a network of interconnected poles. We identified parameter combinations that determine the generation of each of these structures. In general, this approach may become useful for correlating the morphogenetic phenomena taking place in a biological system with the biophysical characteristics of its constituents.     

Neurobiological bases of rhythmic motor acts in vertebrates

The general principles governing the nervous control of innate motor acts in vertebrates are discussed. Particular consideration is given to the control of locomotion in both mammals and lower vertebrates. One in vitro model of the lamprey central nervous system has been developed. It can be maintained in vitro for several days and the motor pattern underlying locomotion can be elicited in isolated sections of the spinal cord. These findings now allow a detailed analysis of the underlying neural mechanisms. The hypothesis that different parts of the network controlling locomotion can be used in a variety of other motor acts, including learned ones, is reviewed.     

Predictions of viscoelastic behavior of pomegranate using artificial neural network and Maxwell model

Stress relaxation is one of the defined tests to characterize the viscoelastic properties of food and agricultural materials. Stress relaxation data are very important because they provide useful and valuable information such as fruit firmness and ripening, food processing and predicting changes in the material during mechanical loading. Viscoelastic behavior of some varieties of pomegranate that are cultivated in Iran has been studied in current research. For this purpose, stress relaxation test was conducted with three cultivars of pomegranate (Ardestani, Shishekap and Malas) for three sizes (small, medium and large). In this article the potential of artificial neural network (ANN) technique is evaluated as an alternative method for Maxwell model to predict the viscoelastic behavior of pomegranate. Neural stress relaxation models were constructed to describe stress relaxation behavior of pomegranate with respect to time. The neural models were built based upon relaxation time as input network and stress relaxation as output network. The results revealed that both ANN model and Maxwell model have high capability of producing accurate and reliable predictions for stress.     

Simulink在机电传动控制教学中的应用

简要介绍Matlab中Simulink的功能和模块组成,分析了"机电传动控制"课程的特点,给出将这一仿真方法与课程中相关的内容相结合的实例;在深入分析电动机数学模型的基础上,构造出它的仿真模型,利用它分析电动机固有机械特性、动态品质等问题;将它用于教学实践中,取得了较好的效果.     

人工神经网络技术在机械故障诊断中的应用探讨

阐述了人工神经网络模型的一般结构和算法，并设计了机械故障诊断神经网络的模型和学习过程。通过对集材-50拖拉机变速箱的实验诊断和测试，结果表明人工神经网络技术可以快速、准确地诊断出机械故障类型。     

基于RBF神经网络整定PID的PMLSM控制研究

介绍了直线永磁同步电机(permanent magnet linear synchronous motor,PMLSM)的数学模型。由于直线永磁同步电机具有非线性、耦合性和负载扰动等特性,常规PID控制器不能达到理想的控制效果,而径向基函数(radial basis function,RBF)神经网络具有学习速度快、无局部极小和良好的逼近能力,提出了将RBF网络与增量式PID控制结合在一起应用的方法。matlab仿真结果表明:该控制系统具有良好的逼近能力、较强的适应性和抗干扰能力。     

In vitro reconstruction of the respiratory central pattern generator of the mollusk Lymnaea

Most rhythmic behaviors such as respiration, locomotion, and feeding are under the control of networks of neurons in the central nervous system known as central pattern generators (CPGs). The respiratory rhythm of the pond snail Lymnaea stagnalis is a relatively simple, CPG-based behavior for which the underlying neural elements have been identified. A three-neuron network capable of generating the respiratory rhythm of this air-breathing mollusk has been reconstructed in culture. The intrinsic and network properties of this neural ensemble have been studied, and the mechanism of postinhibitory rebound excitation was found to be important for the rhythm generation. This in vitro model system enables a better understanding of the neural basis of rhythm generation.     

Plastic deformation with reversible peak broadening in nanocrystalline nickel

Plastic deformation in coarse-grained metals is governed by dislocation-mediated processes. These processes lead to the accumulation of a residual dislocation network, producing inhomogeneous strain and an irreversible broadening of the Bragg peaks in x-ray diffraction. We show that during plastic deformation of electrodeposited nanocrystalline nickel, the peak broadening is reversible upon unloading; hence, the deformation process does not build up a residual dislocation network. The results were obtained during in situ peak profile analysis using the Swiss Light Source. This in situ technique, based on well-known peak profile analysis methods, can be used to address the relationship between microstructure and mechanical properties in nanostructured materials.     

基于离散元法玉米秸秆双层粘结模型力学特性研究

针对玉米秸秆外表皮与内穰力学特性存在显著差异问题,建立离散元玉米秸秆双层粘结双峰分布模型,通过力学试验与虚拟仿真试验对比,标定玉米秸秆外表皮和内穰力学参数,校正离散元模型,探究玉米秸秆力学特性.结果表明,采用离散元Hertz-Mindlin with bonding颗粒接触方法可建立玉米秸秆双层粘结双峰分布模型.完善DEM方法建立玉米秸秆颗粒粒度随机分布的双层粘结模型方法.通过力学试验得出青贮玉米秸秆外表皮弹性模量和剪切模量分别为982.52和387.58 MPa,青贮玉米秸秆内穰弹性模量和剪切模量分别为28.64和8.13 MPa,外表皮木质部与内穰纤维部力学特性差异显著.计算得出外表皮-外表皮、外表皮-内穰、内穰-内穰之间粘结参数.通过单轴压缩试验,剪切与虚拟仿真试验对比验证离散元模型可靠性.文章所建立玉米秸秆双层粘结双峰分布离散元模型表征两者力学特性差异,为青贮玉米饲料数值化研究提供理论依据.     

应用改进的RBF方法预测粘土料力学指标的研究

 坝土料力学指标是土石坝结构稳定分析的重要依据,其传统获取方法为实验方法。本文尝试采用改进RBF神经网络模型,以不同物理指标组合为输入因子,力学指标为输出项。然后,通过改进最近邻聚类算法训练模型进行测试样本模型效果检验。结果表明,改进RBF神经网络模型可以较为快速、准确地预测粘土料力学指标。     

施氮量和留叶数互作对烤烟NC297产量和质量的影响

以促进NC297产量和质量协调和最优化为目的，研究施氮量和留叶数互作对NC297的物理特性、化学成分、经济性状的影响。结果表明：在施氮量7.5～60 kg/hm2、留叶数17～26片时，NC297叶长、叶宽、叶面积、叶厚、单叶重均随施氮量的增加而增加；含梗率、叶质重随施氮量的增加先降低后升高；烟碱和总氮含量随着施氮量的增加而上升显著，随着留叶数的增加而显著下降；产量持续上升，产值、均价、中上等烟比例随着施氮量和留叶数的增加先增大后减小；在物理性状、化学成分、经济性状上，除还原糖和糖碱比外，施氮量对其余各指标的影响均最大，留叶数的影响次之，二者交互作用产生的影响最小。NC297的适宜施氮量为30 kg/hm2，适宜留叶数为20～23片。     

全过程基于MATLAB的直流电机调速系统快速设计

直流电机调速系统是典型的闭环控制系统，是机电控制的典型课题。本文提出一种基于MATLAB的快速高效的控制系统开发方法，克服传统的控制系统设计周期长、效率低的缺点。将MATLAB多个工具箱巧妙结合应用，实现全过程基于MATLAB的直流电机调速系统的快速设计。应用MATLAB中的System Identification工具箱实现直流电机的数学建模，应用Simulink对控制系统进行仿真，应用Simulink Design Optimization工具箱实现PID参数的自动寻优，应用RTW技术免去繁琐的编程过程，实现代码自动生成，将生成的代码下载至DSP目标板，完成整个控制系统设计。相对传统的设计方法，该方法具有高效、快速和方便调整等特点，对其他控制系统设计具有一定的借鉴意义。