多输入的二阶广义分布参数系统的控制综合问题

广义分布参数系统具有广泛的实际背景.如复合材料中的温度分布,电缆中的信号传播,电磁耦合超导线路中的电压分布,飞行器姿态控制等问题研究中都会出现这样的系统.极点配置与反馈稳定性是这类系统研究的重要方面.本文应用泛函分析及算子理论讨论了Hilbert空间中多输入的二阶广义分布参数系统的极点配置与反馈稳定性问题,获得了这类系统极点可配置与可镇定的一些充分条件,并利用复分析、复级数、有界线性算子的广义逆等方法建立了反馈控制律的构造性表达式.本文结论不仅具有重要的实际意义,而且对广义分布参数系统的控制综合问题研究具有重要的理论价值.     

Characteristics of entropy generation and heat transfer in a microchannel with fan-shaped reentrant cavities and internal ribs

Three-dimensional laminar fluid flow and heat transfer in a micro heat sink with cavities and internal ribs are investigated us-ing numerical methods. Moreover, according to the second law of thermodynamics, the model of entropy generation is also established for variable cross section of the microchannel. The simulation encompasses Reynolds number of 198-600, relative cavity height e1/Dhvalues of 0-0.65, relative rib height e2/Dhrange of 0-0.2167. The results show that the effect of relative rib height on entropy generation is significant, while the relative cavity height has little effect on it. The combined effect of cavities and ribs in the microchannel has better performance of heat transfer than the smooth microchannel under similar conditions. Extensive simulations are conducted to collect data on the characteristics of heat transfer and fluid flow in a micro heat sink with cavities and internal ribs. Using these data, correlations for Nusselt number and friction factor in terms of Reynolds number and the geometry of cavity and rib have been developed.     

Fabrication of submicrometer- to micrometer-scale ferroelectric copolymer particles by solution mixture method

In this paper we reported the fabrication of submicrometer- to micrometer-scale ferroelectric copolymer particles by a simple solution mixture method. Particle diameter could be controlled by the second solvent and/or the volume ratio of the second solvent to copolymer butanone solution. These particles were also ferroelectric and could be re-dispersed into water to form a suspension, as facilitated by the potential applications of these particles.     

Integrated energy-oriented cruising control of electric vehicle on highway with varying slopes considering battery aging

Eco-driving strategies for vehicles with conventional powertrains have been studied for years and attempt to reduce fuel consumption by optimizing the driving velocity profile. For electric vehicles(EVs) with regenerative braking, the speed profile with the best energy efficiency should be different from conventional vehicles. This paper proposes an energy-oriented cruising control strategy for EVs with a hierarchical structure to realize eco-cruising on highways with varying slopes. The upper layer plans the energy-optimized vehicle velocity, and the lower layer calculates the torque allocation between the front and rear axles.However, the resulting speed profile with varying velocity may cause a high charge and discharge rate of the battery, resulting in rapid battery fading. To extend the battery life, we make a tradeoff between the energy consumption and wear of the battery by formulating an optimal control problem, where driving comfort and travel time are also considered. An indirect optimal control method is implemented to derive the optimal control rule. As an extension, the control rule for avoiding rear-end collisions is presented and simulated for driving in the real world.     

Comparison of ablative and compressive mechanical behavior of several PICA-like ablative materials

It is significant to compare the ablative and compressive mechanical behavior of different PICA-like materials in the engineering applications. The plasma wind tunnel ablation tests with high-entropy air and CO_2 atmospheres, and compressive experiments in the ambient and 150℃, were conducted for three kinds of PICA-like materials(CF/PR-Si, CBCF/PR-SiOC and NQF/PR-Si composites). The traditional carbon/phenolic(C/PR) braided composites were also used for comparison. PICA-like materials have the better thermal insulation than traditional C/PR composite, especially for CBCF/PR-SiOC composite. The ablation behavior of CF/PR-Si and CBCF/PR-SiOC PICA-like materials in the CO_2 atmosphere can produce a large amount of SiO_2 in the form of coatings, oxide layers and skeletons on the ablated surface, which are greatly different from that in the air atmosphere.The compressive behavior of PICA-like material is greatly depended on the fiber fabrics, and exhibits the large discrete characteristics. The longer fiber in the PICA-like materials plays the role in maintaining the material integrity, while it may increase the thermal conductivity.     

我国ADI的发展思路探讨

综述了等温淬火球墨铸铁(Austempered Ductile Iron,简称ADI)的基本性能优点及国内外的现状;分析了我国ADI与工业发达国家的差距;提出了我国ADI在发展过程中存在的主要问题和建议;阐述了大力发展我国ADI产业的迫切性,并探讨了发展我国ADI产业的思路与对策.     

EBZ／H132型掘采一体机的研制与应用

目前，我国一些大型矿井可用于综采开采的工作面已寥寥无几，却留下大量的不规则采区、残采区，“三下”压煤问题也没有解决。因此，研究开发适用于残采区和“三下”采煤的短壁开采装备和技术已迫在眉睫。EBZ／H132型掘采一体机的研制，无疑对延长矿井服务年限，提高资源回收率，稳定职工队伍，保证煤炭工业的持续稳定发展具有现实意义。EBZ／H132型掘采一体机为纵轴式、横轴式截割机构互换的部分断面掘采一体机，纵轴式截割机构用于煤及半煤岩巷掘进，横轴式截割机构用于“三下”采煤及回收煤柱等短壁开采。EBZ／H132型掘采一体机采用本机、离机和遥控三种操作方式，这是我国首次研发的具有独立知识产权、实现了离机遥控操作的掘进机，它的研制成功标志着我国掘进机的研究与制造水平迈上了一个新台阶。EBZ／H132型掘采一体机见图1。     

Evaluation of numerical ablation model for charring composites

Charring composites are widely used in the thermal protection system(TPS) to consume the intense aerodynamic heating during vehicle reentry. The ablation and thermal responses for the charring composites can be studied by using a numerical ablation model, in which the surface ablation and volume ablation could be taken into account. The coupling interactions among temperature, gas motion and interior pressure producing the pyrolysis gas could make the computation more complicated. A multi-physics model is developed to simulate the thermal response coupled with volume ablation and surface ablation. After studying four typical ablation cases, the model is validated, and then the heat transfer mechanisms in ablation are investigated. It is found that the viscous dissipation energy by the motion of pyrolysis gas can be neglected in the simulation. Also, the flow of pyrolysis gas plays an important role in the temperature response, especially under high heat flux condition.     

一种改进BP网络及其在智能传感器非线性校正中的应用

主要分析了神经网络存在的一些缺陷,研究了一种改进BP神经网络学习算法的相关技术,设计并实现了一种改进型BP神经网络算法,并将其应用于智能传感器的非线性自校正系统。通过在某无人机机载高度传感器上试验研究,证明了这种算法的可靠性、先进性、稳定性。     

基于RFID技术的智能小区巡更系统开发与实现

本文针对智能小区安防系统的实际,提出一种基于RFID和GPRS技术的巡更系统。系统由巡更节点、巡更终端机及监控管理上位机构成。巡更节点采用非接触式智能卡,实现电子标签功能;巡更终端机具有节点信息读取、信息处理、无线通信功能;设计采用AT89S52作为控制器,扩展相应的外围电路,并通过GPRS无线接口与监控管理上位机进行通信。监控管理上位机具有无线接口,接收终端机发来的信息,实现远程信息监控。系统采用了最新的物联网技术,经实际运行巡更系统工作稳定,满足了智能小区安防的需要。