Remote photovoltaic, standalone systems

The initiation of electrification of small farm villages in the Southern States of Mexico is described by examining a one-year history of one village's experience. The system is based on distributed power sources, as the individual residences are a collection of farms rather than contiguous houses. Distributed power systems, with very small loads, require a small modular generator and energy storage system that are reliable, inexpensive, readily available, and easily understood by the populace. The component selection, system design, integral training, installation, and maintenance programs were created to produce a system that would be independent of outside suppliers     

Battery management considerations for multichemistry systems

The performance advantage of Li-ion batteries versus NiCd and NiMH technology has created a worldwide demand for Li-ion cells that is much greater than current manufacturing capacity. This is keeping prices high and supplies scarce-a situation expected to continue for at least several more years. Multichemistry chargers, while challenging to design, keep price-performance points flexible and guard against interruptions in supply. This paper surveys the design issues in implementing chargers that handle NiCd, NiMH, or Li-ion cells interchangeably     

Period selection for integrated controller tasks in cyber-physical systems

Performance optimization of cyber-physical systems(CPS)calls for co-design strategies that handle the issues in both computing domain and physical domain.Periods of controller tasks integrated into a uniprocessor system are related to both control performance and real-time schedulability analysis simultaneously.System performance improvement can be achieved by optimizing the periods of controller tasks.This paper extends an existing model to select task periods in real-time for CPS with fixed priority controller tasks scheduled by rate-monotonic algorithm.When all the tasks can be integrated,the analytic solution of the problem is derived by using the method of Lagrange multipliers and gradient descent method is evaluated to be suitable online.To further deal with the condition that the system is overloaded,an integrated method is proposed to select periods of tasks online by selecting a subset of tasks first and then optimizing the periods for them.Experimental results demonstrate that our method yields near-optimal result with a short running time.     

MPPT of photovoltaic systems using extremum - seeking control

A stability analysis for a maximum power point tracking (MPPT) scheme based on extremum-seeking control is developed for a photovoltaic (PV) array supplying a dc-to-dc switching converter. The global stability of the extremum-seeking algorithm is demonstrated by means of Lyapunov's approach. Subsequently, the algorithm is applied to an MPPT system based on the "perturb and observe" method. The steady-state behavior of the PV system with MPPT control is characterized by a stable oscillation around the maximum power point. The tracking algorithm leads the array coordinates to the maximum power point by increasing or decreasing linearly with time the array voltage. Off-line measurements are not required by the control law, which is implemented by means of an analog multiplier, standard operational amplifiers, a flip-flop circuit and a pulsewidth modulator. The effectiveness of the proposed MPPT scheme is demonstrated experimentally under different operating conditions.     

Nonlinear controller design for switched reluctance drive systems

A nonlinear speed-loop controller for a switched reluctance motor (SRM) drive system is proposed. The details of the controller design and analysis are discussed. In addition, to extend the controllable speed range, the commutating angle of the drive system is suitably adjusted as the motor speed goes beyond base-speed. By using a 32-bit microprocessor, a fully digital drive system including a digital speed-loop controller and a digital current-loop controller is implemented here. The hardware circuit of the drive system is very simple. The system has satisfactory performance in both the pulsewidth modulated (PWM) region and the single pulse region. The adjustable speed range of the system is from 10 r/min to 3000 r/min. In addition, the proposed drive system performs well in tracking ability, load disturbance rejection capability, and robustness. Several experimental results are presented to validate the theoretic analysis.     

面向悬浮光力系统的集成化反馈控制器研究

悬浮光力系统具有高灵敏度、高稳定性和低耗散等特点,有望发展成为新型高性能力学传感器。针对目前悬浮光力系统存在的反馈控制器兼容性差、软硬件成本高、集成度低等问题,提出了一种兼容多种反馈控制模式的软硬件设计方案,并研制了一套高度集成的反馈控制器,在160 mm×170 mm×42 mm的尺寸上集成了六通道模数/数模转换器、滤波器、现场可编程门阵列+微处理器(FPGA+ARM)等功能模块,并且开发了基于数字锁相环和比例积分微分(PID)控制器的控制算法,最终在同一套硬件系统上实现了跨尺度微粒的运动信息采集和反馈控制,以及数十赫兹至亚兆赫兹的感知带宽。实验结果表明,该集成反馈控制器能够实现超高真空(10^-6 Pa量级)下亚微米及微米尺度微粒的稳定悬浮和运动控制。在扩展系统感知带宽的同时减小了整体体积,为悬浮光力传感技术的器件化奠定了基础。     

Interfacial characteristics in CNTs-AgCuTi systems

AgCuTi-based composite fillers reinforced with Carbon Nanotubes（CNTs） were prepared by mechanical ball milling and ultrasonic agitation. The morphological features, chemical components, and melting characteristics of the composite fillers with different content of CNTs addition were investigated using Field Emission Scanning Electron Microscopy（FESEM）, XRay Diffraction（XRD） and a Differential Scanning Calorimeter（DSC）. After being heated at 900 ℃, the microstructure of the composite fillers was ...     

飞控系统模糊控制器设计及稳定性分析

建立了飞控系统的Ｔａｋａｇｉ－Ｓｕｇｅｎｏ（Ｔ－Ｓ）模糊模型;给出了设计模糊状态反馈控制器,保证闭环系统全局渐近稳定、具有一定衰减率稳定的两个充分条件;提出了采用线性矩阵不等式（ＬＭＩ）方法,将该充分条件转化为对线性矩阵不等式族寻求ＬＭＩ可行解的凸优化问题,得到了稳定性分析和模糊状态反馈控制器设计的新方法。仿真结果表明,所提出的设计方法方便有效,控制器鲁棒性好。     

Feedforward maximum power point tracking of PV systems using fuzzy controller

A feedforward maximum power (MP) point tracking scheme is developed for the interleaved dual boost (IDB) converter fed photovoltaic (PV) system using fuzzy controller. The tracking algorithm changes the duty ratio of the converter such that the solar cell array (SCA) voltage equals the voltage corresponding to the MP point at that solar insolation. This is done by the feedforward loop, which generates an error signal by comparing the instantaneous array voltage and reference voltage. The reference voltage for the feedforward loop, corresponding to the MP point, is obtained by an off-line trained neural network. Experimental data is used for off-line training of the neural network, which employs back-propagation algorithm. The proposed fuzzy feedforward peak power tracking effectiveness is demonstrated through the simulation and experimental results, and compared with the conventional proportional plus integral (PI) controller based system. Finally, a comparative study of interleaved boost and conventional boost converter for the PV applications is given and their suitability is discussed.     

Optimized one-cycle control in photovoltaic grid connected applications

The use of one-cycle control (OCC) for maximum power point tracking (MPPT) and power factor correction (PFC) in grid connected photovoltaic (PV) applications is discussed. Circuit and operating parameters of the one cycle-based controller of a cost-effective single-stage inverter are optimized in order to obtain the best performances of the system under different irradiance levels. Firstly, design constraints are formulated which allow to get a very efficient OCC operation in terms of power extracted from the PV array, stability, and PFC. Afterwards, such constraints are used to perform the parametric optimization of the one cycle controller by means of suitable heuristic approaches. Various selection criteria of the best parameters set under different conditions are discussed and applied. Finally, a customized perturb and observe (P&O) control is applied to the optimized one cycle controlled single-stage inverter in order to perform a real MPPT in presence of varying irradiance conditions. Subjects described here are covered by the Italian Patent Application SA2005A000014-13.07.2005 and PCT Application PCT/IT2005/000747-20.12.2005     

Turbulent and unsteady flow characteristics of delta wing vortex systems

This paper presents an overview of experimental investigations on a 65 deg swept delta wing as part of the International Vortex Flow Experiment 2 (VFE-2). Results obtained in low-speed wind tunnel facilities include oil flow and laser light sheet flow visualization, mean and unsteady surface pressure distributions as well as mean and turbulent velocity components of the flow field and close to the wing surface. Thus, field and near wall distributions of all components of the Reynolds stress tensor are available. Details of the delta wing vortex structure and breakdown phenomenon are discussed and analyzed. Vortex bursting leads to specific spectral densities of velocity and surface pressure fluctuations characterized by narrow band distributions associated with the helical mode instability of the vortex breakdown flowfield. Further, special emphasis is on the occurrence of an inner vortex detected for the low Reynolds number and Mach number regime. This inboard vortex results from a laminar separation close to the apex due to the spanwise pressure gradient in the area of relatively large thickness while the classical leading-edge vortex progressing from the rear part to the apex is fed from the turbulent shear layers shed at the wing upper and lower side.     

空间推进系统静态特性通用仿真方法

针对采用液体推进剂的空间推进系统，提出了一种基于图论和面向对象技术的通用数值仿真方法，该方法适用于空间推进系统各种形式设计方案的检验及推进系统静态工作过程的仿真研究。应用此方法开发的软件对某空间推进系统进行了静态特性的仿真，获得良好效果，显示了很好的通用性。     

加强管制员资质能力建设的探索

安全是民航的根本,管制员是安全保障链条上重要的组成部分。在高高的塔台上、在雷达屏幕前,头戴耳机、手拿话筒、专注蓝天的管制员,他们的每一道指令都关系到生命财产的安全。管制员的工作,职业神圣,责任重大,因此,管制员不仅要具备丰富的专业知识、灵活的处置能力、高超的沟通技巧,还必须具有坚毅的意志品质以及     

粒子群算法在机动指令跟踪控制器中的应用

基于Backstepping的设计思想设计了机动轨迹跟踪控制律,以实现战机某些预定的战术机动动作。首先,将飞行动力学模型和运动学模型分解为三轴方向的相对简单的子系统,然后采用反步法分别设计控制律,使得整个系统渐近稳定。由于控制器中含有可调参数,每次跟踪不同的参考轨迹都需要重新设定控制器参数值才能达到良好的跟踪效果,因此利用粒子群算法对控制器参数进行了优化整定,从而保证控制器的自适应性。最后,以机动动作库中战机的某些机动动作为参考轨迹实现全局渐进跟踪,取得了良好的跟踪效果,验证了粒子群算法在控制器参数寻优中的有效性和可行性。     

边界扫描技术在电子控制器测试中的应用

航空发动机电子控制器向更高性能和更高集成度的方向发展,使得传统测试方法难以满足需要.提出了通过边界扫描技术来解决电子控制器核心电路的测试问题.设计了边界扫描测试技术验证平台,主要包括边界扫描测试适配器和被测电路.对被测电路开展了基于边界扫描的测试试验,完成了主要指令的测试.同时通过扫描链实现了对被测电路的故障注入,通过这种方法注入故障可对航空发动机电子控制器的机内测试(BIT)能力进行验证.      

涡扇发动机轴对称分开和混合排气系统红外辐射特征的对比

用数值模拟的方法对比研究了涡扇发动机轴对称分开和混合排气系统的红外辐射特征.排气系统的流场采用商业软件进行模拟,红外辐射特征采用根据反向蒙特卡洛法自主开发的软件进行计算,计算分析了两种排气系统在3~5μm波段红外辐射的空间分布以及喷管内不同固体部件在探测方向上的辐射贡献.在红外辐射特征计算过程中,考虑了喷管内壁的发射和反射以及燃气组分二氧化碳、水和一氧化碳的吸收-发射等影响.结果表明:两种排气系统红外辐射的空间分布特性不同;混合排气喷管的积分辐射强度在方位角为0°~10°时大于分开排气喷管,在其他方位角范围内均小于分开排气喷管.      

镉镍电池正极浸渍液中钴含量的分析

简述了运用AIR－C2H2原子吸收光谱法进行镉镍电池正极浸渍液中钴含量的测试，分析了钴最佳测定条件以及呈良好线性范围的浓度，同时对样品消化处理条件，干扰因素进行了综合考虑，实验表明，该方法具有很好的灵敏度，重现性，干扰小，方法简单，操作容易掌握等特点。对样品然含量的测定，相对标准偏差均小于1．0％（n=6)，标准加入回收率均在97．0％－102．0%(n=5)范围内，达到了实验室分析质量控制的要求，完全适用于镉镍电池正极浸渍液中钴含量的控制分析和样品系统分析。     

无人机空中加油自主编队控制器设计

针对自主空中加油(AAR)任务中的飞行器编队形成问题,提出了一个完整的自主控制器方案。采用基于视线的编队制导律控制队形,产生制导指令。针对加油编队过程中产生的模型误差和尾涡扰动等不确定性,基于RBF神经网络和自适应Backstepping方法,设计了UAV姿态和速度非线性控制律来在线逼近和补偿不确定性,保证系统的鲁棒性和稳定性。使用协调转弯方式将航迹角指令转换为姿态指令,以实现控制律对航迹角指令的精确跟踪。最后,仿真结果验证了制导律和控制律的有效性。     

两种涡扇发动机排气系统红外辐射特性的比较

针对弹用涡扇发动机，计算和比较了3μm-5μm波段轴对称分开排气喷管和轴对称混合排气喷管的红外辐射特性，并与模型实验的结果进行了比较。结果表明，两种类型的排气喷管在红外辐射的空间分布和光谱分布特性方面具有相似的特征，但是红外辐射强度的数值有较大差别；内、外涵混合排气，可以显著降低喷管空腔、尾喷流和整个排气系统的红外辐射。     

Expected charge states of energetic ions in the magnetosphere

This paper reviews major developments in our understanding of the physics of energetic heavy ions in the Earth's plasma environment during the past four years (1974–1977). Emphasis is placed on processes that influence or are influenced by the ion charge states. This has been a period of growing awareness of the important role heavy ions play in space plasmas. Large fluxes of helium ions and even heavier ions have been observed at the geostationary altitude and in the heart of the radiation belts. Such ions have also been observed on low latitude rockets and satellites, and oxygen ion precipitation exceeding that of protons has been reported. In the outer parts of the Earth's plasma envelope there is mounting evidence for significant fluxes of heavy ions: in the magnetotail, the magnetosheath and in the polar cusp regions. In the inner magnetosphere there is a limited theoretical understanding of equatorially mirroring ions, but generally only radial diffusion at one pitch angle and pitch angle diffusion at one L- shell have been studied; for ions the coupled equations are yet unsolved even for the simplest case of only one charge state (protons). Theoretical modeling of the charge state structures of geophysical heavy ion populations is in part frustrated by the lack of adequate laboratory measurements of the pertinent charge exchange cross sections. A first attempt has, however, been made to treat the charge state transformation processes in the radiation belts for equatorially mirroring atomic oxygen ions. Wave-particle interactions in the magnetosphere become much more complex in multi component and multi charge state plasmas where hybrid resonances and wave-particle interaction induced non-linear species-species coupling could be important. Heavy ion plasma physics in the Earth's magnetosphere and in the magnetospheres of other planets should be a field of fruitful study for both experimentalists and theoreticians in the years ahead.Proceedings of the Symposium on Solar Terrestrial Physics held in Innsbruck, May–June 1978.