基于ARM的超声波调宽高压脉冲发控技术研究

提出了一种基于ARM的超声波调宽高压脉冲发控技术;该技术以超声波检测系统为背景,由ARM微处理器S3C2440A作为核心控制器,超声波激励脉冲宽度、重复频率和电压幅度均可调;高压电源采用了一种可控高压电源,能输出0～1000V电压;重点分析了激励脉冲对超声波信号的影响、电路中各个元件对超声波激励脉冲的影响以及基于ARM的PWM控制脉冲的产生;从理论上得出了发射电路中各个电阻与激励脉冲电压电流的数学关系,实验得出了1kHz重复频率的600V脉冲.该发射电路可以激励不同探头产生多种频率和发射功率可调的超声波。

舰空导弹垂直发射系统发展概况

垂直发射已成为现代海上防空武器的发展趋势,但随着反舰武器的不断发展,现有垂直发射系统的不足逐渐显露出来。新技术的应用使舰空导弹垂直发射系统得到进一步的发展。介绍了现役垂直发射系统及应用的新技术。

Discussion on the Prevention and Control Countermeasures of Sudden Disasters on Protected Vegetable in Hebei Province

Protected vegetable production made the traditional agriculture gradually get rid of the shackles of nature, broke the seasonal traditional agriculture and realized the anti season list of agricultural products. While protected vegetables often encountered sudden disasters in production and were restricted with the conditions of low temperature and weak light. Aimed at the sudden disasters of protected vegetable production in Hebei Province,the countermeasures for disaster prevention and control were put forward from the aspects of variety selection, seedling treatment technology,grafting technique,cultivation and management,flower and fruit retention technology,application of exogenous substance,rational fertilization,transgenic technology and so on,in order to reduce production risks and cut loss,realize that protected vegetable production is safe,good-quality and efficient.

Necessary and Sufficient Conditions for Consensus in Third Order Multi-Agent Systems

We deal with a consensus control problem for a group of third order agents which are networked by digraphs.Assuming that the control input of each agent is constructed based on weighted difference between its states and those of its neighbor agents, we aim to propose an algorithm on computing the weighting coefficients in the control input. The problem is reduced to designing Hurwitz polynomials with real or complex coefficients. We show that by using Hurwitz polynomials with complex coefficients, a necessary and sufficient condition can be obtained for designing the consensus algorithm. Since the condition is both necessary and sufficient, we provide a kind of parametrization for all the weighting coefficients achieving consensus. Moreover, the condition is a natural extension to second order consensus, and is reasonable and practical due to its comparatively decreased computation burden. The result is also extended to the case where communication delay exists in the control input.

Adaptive Neural Network-Based Control for a Class of Nonlinear Pure-Feedback Systems With Time-Varying Full State Constraints

Abstract--In this paper, an adaptive neural network （NN） control approach is proposed for nonlinear pure-feedback sys- tems with time-varying full state constraints. The pure-feedback systems of this paper are assumed to possess nonlinear function uncertainties. By using the mean value theorem, pure-feedback systems can be transformed into strict feedback forms. For the newly generated systems, NNs are employed to approximate unknown items. Based on the adaptive control scheme and backstepping algorithm, an intelligent controller is designed. At the same time, time-varying Barrier Lyapunov functions （BLFs） with error variables are adopted to avoid violating full state constraints in every step of the backstepping design. All closed- loop signals are uniformly ultimately bounded and the output tracking error converges to the neighborhood of zero, which can be verified by using the Lyapunov stability theorem. Two simulation examples reveal the performance of the adaptive NN control approach. Index TermsmAdaptive control, neural networks （NNs）, non- linear pure-feedback systems, time-varying constraints.

Research on Development Trend of Automobile Electronic Technology

Along with the popularization of artificial intelligence and information technology, the development of automobile industry have been closely combined with information technology, environmental protection and energy saving ideas, promotion and application of electronic control technology, which development cycle becoming shorter and shorter. In this paper, through the analysis of the present application situation and development trend of the automobile electronic technology at present, in order to provide a theoretical reference for the future development of the automobile electronic control technology.

A Review of Direct Driven PMSG for Wind Energy Systems

This paper presents a comprehensive overview study of the DDPMSG （direct driven permanent magnet synchronous generator） for wind energy generation system. Wind turbine controls are provided. The PMSG （permanent magnet synchronous generator） is introduced as construction and model. Configurations of different power converters are presented for use with DDPMSG in wind systems at variable speed operation and maximum power capture. Control techniques for the system are discussed for both machine-side and grid-side in details. Grid integration is provided with focus on how to insure power quality of the system and the performance at disturbances.

Optimization of Rotor Assembly Process of Rotor Initial Unbalance of an Aeroengine Gas Generator

The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of single disc and combined discs on rotor dynamic characteristics are firstly implemented in respect of the dispersity of rotor initial unbalance.It is found that the most important factors contributing to rotor vibration are the unbalances of the first stage compressor disc and the second stage turbine disc.However,reducing the mass of two discs conflicts with the control of the whole gas generator rotor balance resulting from the unbalance increase of single components.Thus,we further analyze the key control factors of affecting rotor initial unbalance,and give the strict control measures of centrifugal impeller runout in the assembly process by adjusting the angle of central tie rod axis.The purpose of this measures to make the assembly process simpler and more effective for timely controlling rotor initial unbalance.The efforts of this study validate that the proposed method is workable for the rotor tightened by a central tie rod and possesses the significant meaning of practical application in engineering.

Efficient Mechanisms to Improve TCP Performance over OBS Networks

Transmission Control Protocol (TCP) performance over Optical Burst Switching (OBS) is experimentally investigated on an OBS network testbed, concluding that burst losses will lead to a significant drop in the available TCP bandwidth. Two mechanisms are introduced to improve TCP performance. One is concerning the burst assembly optimization and another is based on the novel assembly and scheduling mechanism to reduce the burst losses.

Creating a Business Process Monitoring System ＂A-IOMS＂ for Software Development

In this paper, the authors establish the Amalab-integrated operation management system （A-IOMS） as a new way to carry out software development and monitor business processes. This new system puts the previously constructed the Amalab-project planning navigation system （A-PPNS） to work throughout the entire organization. The A-IOMS has several key elements. Specifically, the authors have constructed： （1） a Hi-reliability estimation system diagnostic tool that pinpoints problems with software development estimates and offers a prescription for resolving them; （2） a QA table map that allows for an immediate, thorough, and consistent quality assurance process; （3） a system for sharing software development schedules throughout the organization; and （4） a technological asset completion reporting system for passing down and cultivating software development technologies and strategically expanding them. The authors verified the effectiveness of the A-IOMS at company A, a systems integration company, and the given outcomes were obtained.

Design and Implementation on the Wind and Light Complementary LED Lighting Controller based on Novel Base Board Packaging Technology

In this paper, we conduct theoretical research on design and implementation on wind and light complementary LED lighting controller based on the novel base board packaging technology. LED, as a kind of device can convert electric power into visible light directly the homomorphism of semiconductor devices, with high efficiency and small energy consumption, good light quality, use safety, long service life, green environmental protection, flexible control as this is common lamps and lanterns is incomparable advantage. Therefore, it is considered to be 21 century of a new generation of lighting source. Based on the superiority of LED, it is widely applied in many fields of lighting. To enhance the traditional solar based pure LED system, we enhance it with the combination of the wind power and the optimized controller that holds specific meaning.

Composite core-shell microparticles from microfluidics for synergistic drug delivery

Microparticles have a demonstrated value for drug delivery systems. The attempts to develop this tech- nology focus on the generation of featured microparticles for improving the function of the systems. Here, we present a new type of microparticles with gelatin methacrylate （GelMa） cores and poly（L-lactide-co-glycolide） （PLGA） shells for syn- ergistic and sustained drug delivery applications. The mi- croparticles were fabricated by using GelMa aqueous solu- tion and PLGA oil solution as the raw materials of the mi- croflnidic double emulsion templates, in which hydrophilic and hydrophobic actives, such as doxorubicin hydrochloride （DOX, hydrophilic） and camptothecine （CPT, hydrophobic）, could be loaded respectively. As the inner cores were poly- merized in the microfluidics when the double emulsions were formed, the hydrophilic actives could be trapped in the cores with high efficiency, and the rupture or fusion of the cores could be avoided during the solidification of the micropar- ticle shells with other actives. The size and component of the microparticles can be easily and precisely adjusted by ma- nipulating the flow solutions during the microfluidic emulsi- fication. Because of the solid structure of the resultant mi- croparticles, the encapsulated actives were released from the delivery systems only with the degradation of the biopolymer layers, and thus the burst release of the actives was avoided. These features of the microparticles make them ideal for drug delivery applications.