Finite time agreement protocol design of multi‐agent systems with communication delays

In this paper, the finite‐time agreement problem of continuous‐time multi‐agent systems with communication delays is considered. First, the multi‐agent system researched in the paper is described. Second, some notations and lemmas used in the paper are given. Then, agreement protocols for continuous (but non‐smooth) multi‐agent systems are proposed, which ensure that the states of agents reach agreement in finite time. The stability analysis and simulations are presented to show the effectiveness of the method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

基于政府规制的发电市场结构演进及国际实践

通过政府规制下各国发电市场结构演进实践的考察和分析,认为政府利用准入规制控制了发电市场主体进入市场,是政府对发电市场结构进行规制的主要手段,决定着竞争性发电市场结构的形成;政府对市场力的规制可以防止发电商滥用市场力逐利,损害竞争,导致社会福利无谓损失,保护着竞争性发电市场结构形成.结论是政府规制对发电市场结构的演进起着决定性作用.     

直流输电系统用直流分压器现场检测方法研究

对直流输电系统中所用直流分压器设备的准确度进行现场检测,目前国内还没有检定规程或校准规范和实施程序。根据现场环境,提出使用桥式电阻分压器自校准的方法,提出现场实施程序,注意事项,主要仪器的选型及误差分析,分析了现场存在的影响因素,以及影响程度,并完成模拟现场环境的验证试验,试验数据表明,该方法及其实施过程符合直流分压器现场检测要求,对现场检测试验具有指导意义,并可为实验室检定提供参考价值。     

斩波串级调速系统换相失败的分析与仿真

换相失败是串级调速系统逆变器的常见故障,与许多因素有关。分析了串级调速系统换相失败的原因及其影响因素,并针对电源故障引起的换相失败,提出了控制方法,运用MATLAB/simulink对该方法进行仿真研究。结果表明该方法是准确的、可行的,便于工程上的应用研究。     

A mathematical model to analyze heat and mass transfer characteristics of a CPL evaporator porous wick

A capillary pumped loop (CPL), because of its high power thermal transport character, has been developed as an attractive system for the thermal discharge of electronic chips with high power loads, especially on spacecrafts. A working fluid having relatively larger heat of evaporation, methanol for example, may transfer significant heat flux. In this paper a new mathematic model is constructed, in which the most important character is the treatment or the unsaturated region of the evaporator porous wick. Numerical simulation of heat and mass transfer in the evaporator porous wick is carried out with a new three‐layer model. The importance of unsaturated layer to simulate the present problem is clear. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(4): 209–218, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20066     

The impact of data aggregation on the performance of wireless sensor networks

With the increasing need for different energy saving mechanisms in Wireless Sensor Networks (WSNs), data aggregation techniques for reducing the number of data transmissions by eliminating redundant information have been studied as a significant research problem. These studies have shown that data aggregation in WSNs may produce various trade‐offs among some network related performance metrics such as energy, latency, accuracy, fault‐tolerance and security. In this paper, we investigate the impact of data aggregation on these networking metrics by surveying the existing data aggregation protocols in WSNs. Our aim is twofold: First, providing a comprehensive summary and comparison of the existing data aggregation techniques with respect to different networking metrics. Second, pointing out both the possible future research issues and the need for collaboration between data management and networking research communities working on data aggregation in WSNs. Copyright © 2006 John Wiley & Sons, Ltd.     

Soft Nanotubes with a Hydrophobic Channel Hybridized with Au Nanoparticles: Photothermal Dispersion/Aggregation Control of C60 in Water

Simple glycolipid N‐alkaroyl‐β‐D‐glucopyranosylamine 1(n) selectively self‐assembles into sheets in water, nanotubes in alcohols, and helical nanocoils in toluene. All self‐assemblies consist of bilayer membranes in which 1(n) packed in an interdigitated fashion. The outer surface of the sheet is covered with the hydrophilic glucose headgroup of 1(n), whereas those of the nanotube and helical nanocoil are covered with the hydrophobic alkyl‐chain tail of 1(n). Heat treatment of the nanotube in the presence of water induces a rearrangement of the molecular packing of the outermost surface that allows the nanotube to become an effective nanocontainer for the dispersion of fullerene (C60) in water, a result of the ability of the hydrophilic outer surface of the nanotube and the hydrophobic nanochannel to encapsulate C60. The nanotube also exhibits photothermal characteristics after being hybridized with Au nanoparticles (AuNPs). The photothermal effect of the AuNPs allows the nanotube to unfold its tubular morphology and leads to compulsive release of the encapsulated C60 to the bulk water. Application of other nanotubes with similar photostimulated transformation ability should facilitate control of the dispersion/aggregation of other carbon nanomaterials, functional aromatic compounds, and drugs with low solubility in water.     

Field Emission and Cathodoluminescence of ZnS Hexagonal Pyramids of Zinc Blende Structured Single Crystals

Single‐crystal hexagonal pyramids of zinc blende ZnS are fabricated by facile thermal evaporation in an ammonia atmosphere at 1150 °C. It is found that ZnS pyramids grow along the [111] crystal axis and possess a sharp tip with a diameter of ～10 nm and a micrometer‐sized base. The structural model and growth mechanism are proposed based on crystallographic characteristics. This unique ZnS pyramid structure exhibits a low turn‐on field (2.81 V µm^?1), a high field‐enhancement factor (over 3000), a large field‐emission current density (20 mA cm^?2), and good stability with very small fluctuation (0.9%). These superior field‐emission properties are clearly attributed to the pyramid morphology, with micrometer‐sized bases and nanotips, and high crystallinity. Moreover, a stable UV emission of 337 nm at room temperature is observed and can be ascribed to the band emission of the zinc blende phase. These results suggest that the ZnS hexagonal pyramids can be expected to find promising applications as field emitters and optoelectronic devices.     

Rational Design of Charge‐Neutral,Near‐Infrared‐Emitting Osmium(II) Complexes and OLED Fabrication

A new series of charge neutral Os(II) isoquinolyl triazolate complexes ( 1 – 4 ) with both trans and cis arrangement of phosphine donors are synthesized, and their structural, electrochemical and photophysical properties are established. In sharp contrast to the cis‐arranged complexes 2 – 4 , the trans derivative 1 , which shows a planar arrangement of chromophoric N‐substituted chelates, offers the most effective extended π‐delocalization and hence the lowest excited state energy gap. These complexes exhibit phosphorescence with peak wavelengths ranging from 692–805 nm in degassed CH₂Cl₂ at room temperature. Near‐infrared (NIR)‐emitting electroluminescent devices employing 6 wt % of 1 (or 4 ) doped in Alq₃ host material are successfully fabricated. The devices incorporating 1 as NIR phosphor exhibit fairly intense emission with a peak wavelength at 814 nm. Forward radiant emittance reaches as high as 65.02 µW cm^?2, and a peak EQE of ～1.5% with devices employing Alq₃, TPBi and/or TAZ as electron‐transporting/exciton‐blocking layers. Upon switching to phosphor 4 , the electroluminescence blue shifts to 718 nm, while the maximum EQE and radiance increase to 2.7% and 93.26 (μW cm^?2) respectively. Their performances are optimized upon using TAZ as the electron transporting and exciton‐blocking material. The OLEDs characterized represent the only NIR‐emitting devices fabricated using charge‐neutral and volatile Os(II) phosphors via thermal vacuum deposition.     

Probing the electromagnetic field distribution within a metallic nanodisk

A Co nanolayer is used as a local probe to evaluate the vertical inhomogeneous distribution of the electromagnetic (EM) field within a resonant metallic nanodisk. Taking advantage of the direct relation between the magneto-optical activity and the electromagnetic field intensity in the Co layer, it is shown that the nonuniform EM distribution within the nanodisk under plasmon resonant conditions has maximum values close to the upper and lower flat faces, and a minimum value in the middle.