A self-adaptive weighted affinity propagation clustering for key frames extraction on human action recognition

In this paper, we propose a novel approach for key frames extraction on human action recognition from 3D video sequences. To represent human actions, an Energy Feature (EF), combining kinetic energy and potential energy, is extracted from 3D video sequences. A Self-adaptive Weighted Affinity Propagation (SWAP) algorithm is then proposed to extract the key frames. Finally, we employ SVM to recognize human actions on the EFs of selected key frames. The experiments show the information including whole action course can be effectively extracted by our method, and we obtain good recognition performance without losing classification accuracy. Moreover, the recognition speed is greatly improved.     

Triphenyl phosphine oxide-bridged bipolar host materials for green and red phosphorescent organic light-emitting diodes

Two wide band gap functional compounds of phenylbis(4-(spiro [fluorene-9,9'-xanthen]-2-yl)phenyl)phosphine oxide (2SFOPO) and (4-(9-ethyl-9H- carbazol-3-yl)phenyl)(phenyl)(4-(spiro[fluorene-9,9′-xanthen]-2-yl)phenyl)phosphine oxide (SFOPO-CZ) were designed, synthesized and characterized. Their thermal, photophysical, electrochemical properties and device applications were further investigated to correlate the chemical structure of bipolar host materials with the electroluminescent performance for phosphorescent organic light-emitting diodes (PhOLEDs). Both of them show high thermal stability with glass transition temperatures in a range of 105–122 °C and thermal decomposition temperatures at 5% weight loss in a range of 406–494 °C. The optical band gaps of compound 2SFOPO and SFOPO-CZ in CH₂Cl₂ solution are 3.46 and 3.35 eV, and their triplet energy levels are 2.51 eV and 2.52 eV, respectively. The high photoluminescent quantum efficiency of emissive layer of doped green device up to 50% is obtained. Employing the developed materials, efficient green and red PhOLED in simple device configurations have been demonstrated. As a result, the green PhOLEDs of compound SFOPO-CZ doped with tris(2-phenylpyridine) iridium shows electroluminescent performance with a maximum current efficiency (CE_max) of 52.83 cd A⁻¹, maximum luminance of 34,604 cd/m², maximum power efficiency (PE_max) of 39.50 lm W⁻¹ and maximum external quantum efficiency (EQE_max) of 14.1%. The red PhOLED hosted by compound 2SFOPO with bis(2-phenylpyridine)(acetylacetonato) iridium(III) as the guest exhibits a CE_max of 20.99 cd A⁻¹, maximum luminance of 33,032 cd/m², PE_max of 20.72 lm W⁻¹ and EQE_max of 14.0%. Compound SFOPO-CZ exhibits better green device performance, while compound 2SFOPO shows better red device performance in PhOLEDs.     

银包铜复合材料的界面研究

采用复合铸造方法制备了银包铜复合材料,研究了扩散退火温度和时间对复合材料显微组织和扩散层厚度的影响。结果表明:随着扩散热处理温度升高和保温时间的延长,扩散层厚度逐渐增加,在500℃和600℃保温60 min,出现了界面组织的球化现象。扩散层厚度与扩散处理时间的平方根成正比,扩散层生长激活能为51.9 kJ/mol。     

Real-Time monitoring of III-V molecular beam epitaxial growth using spectroscopic ellipsometry

We report the real-time monitoring of monolayer thickness changes in AlAs and GaAs layer growth on rotating GaAs substrates using spectroscopic ellipsometry (SE). A phase-modulated spectroscopic ellipsometer was integrated with a III-V MBE system by triggering spectral acquisition synchronously with substrate rotation. Absolute thickness accuracy was verified using ex situ SE measurement. Reasonable agreement was also obtained between in situ growth rate measurements by SE and reflection high energy electron diffraction. The precision and speed of this method appears suitable for real-time control of quantum devices, such as resonant-tunneling diodes.     

Phase and magnetic properties of iron oxide clusters in 20CaO·20SiO2·7Fe2O3·6FeO glasses

The annealing of 20CaO·20SiO₂·7Fe₂O₃·6FeO glasses at 973K in vacuo produced clusters of iron oxide, the shape of which was nearly spherical and the diameter distributed in the narrow range 25–115Å. The phase of clusters was identified to be Fe³⁺(Fe³⁺ _{poststagger|1.30}Fe²⁺ _{poststagger|0.55}V_0.15)·O₄ in the inverse spinel structure based upon the Mössbauer spectra and x-ray diffraction profiles. The clusters exhibited superparamagnetism and their effective anisotropy energy constant was inversely proportional to the cluster diameter. The magnetization of the glasses measured by a vibrating sample magnetometer was 7.2 × 10^-6 Wbmkg^-1 at 10 kOe at room temperature and smaller than the value calculated assuming that the whole clusters have superparamagnetism. These results suggest the pinning of spins near the cluster surface.     

Rolling Friction Enhanced Free‐Standing Triboelectric Nanogenerators and their Applications in Self‐Powered Electrochemical Recovery Systems

Heavy metals contained in wastewater are one of the most serious pollutions in natural resources. A self‐powered electrochemical recovery system for collecting Cu ions in wastewater by incorporating a rolling friction enhanced freestanding triboelectric nanogenerator (RF‐TENG) is developed here. The RF‐TENG utilizes integrated cylindrical surfaces using the conjunction of rolling electrification and freestanding electrostatic induction, which shows outstanding output performance and ultrarobust stability. By using the kinetic energy of flowing water, a collection efficiency of up to 80% for Cu²⁺ ions in wastewater has been achieved. Self‐powered electrochemical systems are one of the most promising applications of TENGs for independent and sustainable driving of electrochemical reactions without the need for any additional power supply. This research is a substantial advancement towards the practical applications of triboelectric nanogenerators and self‐powered electrochemical systems.     

Tribotronic Phototransistor for Enhanced Photodetection and Hybrid Energy Harvesting

Tribotronics is a new field developed by coupling triboelectricity and semiconductor, which can drive triboelectric‐charge‐controlled optoelectronic devices by further introducing optoelectronics. In this paper, a tribotronic phototransistor (TPT) is proposed by coupling a field‐effect phototransistor and a triboelectric nanogenerator (TENG), in which the contact‐induced inner gate voltage by the mobile frictional layer is used for modulating the photodetection characteristics of the TPT. Based on the TPT, alternatively, a coupled energy‐harvester (CEH) is fabricated for simultaneously scavenging solar and wind energies, in which the output voltage on the external resistance from the wind driven TENG is used as the gate voltage of the TPT for enhancing the solar energy conversion. As the wind speed increases, the photovoltaic characteristics of the CEH including the short‐circuit current, open‐circuit voltage, and maximal output power have been greatly enhanced. This work has greatly expanded the functionality of tribotronics in photodetection and energy harvesting, and provided a potential solution for highly efficient harvesting and utilizing multitype energy.     

A delay and energy aware coordination mechanism for WSAN

In this paper, a delay and energy aware coordination mechanism (DEACM) has been devised for wireless sensor–actor networks. In DEACM, a two‐level hierarchical K‐hop clustering mechanism is used to organize the sensors and actors for communication. In the first level, sensors form a K‐hop cluster using actors as cluster heads, and sink is made as the cluster head in the second level to form a cluster among actors. Sensor nodes, which are 1‐hop away from the actors, also called as relay nodes are elected as backup cluster head (BCH) based on the residual energy and node degree. BCH collects the data from sensors when an actor is away to perform actions in the affected area. The scheme is evaluated through exhaustive simulation in NS2 along with other existing schemes. Different parameters like average event waiting time, event reliability, and average energy dissipation are compared, varying the number of sensors, actors, and data transfer rate. In general, it is observed that the proposed DEACM outperforms other existing schemes. Copyright © 2016 John Wiley & Sons, Ltd.     

基于EPON智能电能表光通信模块的设计与实现

智能电能表光通信模块的研究,在智能电网建设中发挥着重要作用。通过对EPON(以太网无源光网络)、PLC(电力载波通信)和WiMAX(全球微波互联接入)技术的对比分析,选择EPON作为智能电能表通信接入网技术,并设计了通信流程。基于QCA8829嵌入式芯片,在Redhat Linux 2.6.x开发平台上采用可接入EPON系统的光纤接口技术,实现了智能电能表主站与从站的通信系统。经测试表明,基于EPON智能电表光通信模块实现了智能电网配电侧信息全采集、全覆盖,并使远程电费控制及负载控制到户。     

一种基于多跳光旁路的IP over WDM节能网络设计方法

针对IP over WDM网络,基于多跳光旁路和流量疏导,以减少能耗为目标对网络链路配置进行设计;考虑多跳光旁路会增大业务传输距离的问题,分析了光路建立顺序对业务传输距离的影响;通过优先路由短距离业务和限制最大传输跳数来减少业务的平均传输跳数。仿真结果表明,优先建立短距离光路的启发式算法与Dijkstra算法相比可以减少25%～55%的能耗,业务平均物理跳数与Dijkstra算法相差在1跳之内。