ZnO纳米线阵列/PVK光电二极管制备与特性

采用水热方法在氧化铟锡（ITO）涂覆的玻璃基底上生长出良好取向排列的氧化锌（ZnO）纳米线阵列,采用场发射扫描电子显微镜（FESEM）、X射线衍射仪（XRD）分别测试ZnO纳米线阵列的形貌和晶相结构。测试结果表明：在基底上形成致密、良好取向排列的ZnO纳米线阵列,纳米线的直径为40～50 nm,长度在200～300 nm,具有六方纤锌矿结构。进一步与p型聚乙烯咔唑（PVK）混合,形成p-n异质结器件,研究该器件在暗态和光照下的电流密度-电压（J-V）特性。结果显示：该器件为光电二极管,在暗态和光照下的整流率分别为216和110。

大红山铁矿二期胶带机变频传动系统谐波的估算及减少谐波措施

大红山铁矿二期胶带运输机采用变频器驱动,变频机组功率较大。设计变频传动系统时,通过对变频器不同整流形式的谐波分析,选择等效24脉波整流形式,使变频传动系统满足国标GBT14549-93对谐波的要求。该工程采用的减少谐波措施是实用的、经济的。

A Novel All-pMOS AC to DC Charge Pump with High Efficiency

A novel AC to DC charge pump with high performance is presented. Due to the pMOS structure and threshold voltage canceling technology, the efficiency and the output voltage are greatly improved. Test results show that the output voltage and power efficiency are improved by 125% and 104% respectively at 13.56MHz for a 1V sinusoidal input compared to the traditional MOS diodes structure.

Simulation and reliability analysis of shunt active power filter based on instantaneous reactive power theory

This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyristor bridge rectifier circuit is constructed. The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme.

Balancing QoE and Fairness of Heterogeneous Traffics Based on Equivalent Rate Scaling

With great increase of mobile service in recent years,high quality of experience(QoE) is becoming a comprehensive and major goal for service provider.To unify evaluations of different services,mean opinion score(MOS) as a subjective assessment is usually adopted for accurate and convincing reflection of user perceived quality.In this paper,we consider the effect of the burst transmission of best effort(BE) traffic on the uses with real time video traffic in the same cell.We extend the rate scaling process which was initially used to shape burstiness of BE users as interference to handle the scenario that BE users act as resource competitors with video users.A power reallocation strategy between the two types of users is presented and an algorithm further improving the fairness of BE users is proposed.The simulation results demonstrate that the proposed algorithm can not only promote the QoE of both types of users,but also guarantee the fairness among users.

Predictive direct power control of three-phase PWM rectifier based on TOGI grid voltage sensor free algorithm

In predictive direct power control(PDPC)system of three-phase pulse width modulation(PWM)rectifier,grid voltage sensor makes the whole system more complex and costly.Therefore,third-order generalized integrator(TOGI)is used to generate orthogonal signals with the same frequency to estimate the grid voltage.In addition,in view of the deviation between actual and reference power in the three-phase PWM rectifier traditional PDPC strategy,a power correction link is designed to correct the power reference value.The grid voltage sensor free algorithm based on TOGI and the corrected PDPC strategy are applied to three-phase PWM rectifier and simulated on the simulation platform.Simulation results show that the proposed method can effectively eliminate the power tracking deviation and the grid voltage.The effectiveness of the proposed method is verified by comparing the simulation results.

Design Consideration for High Power Density GaN Buck-Rectifier in ISOP-IPOS Converter based dc Distribution, System

GaN （gallium nitride） buck-rectifier has been proposed to realize high power density ISOP （input series and output parallel）-IPOS （input parallel and output series） converter-based dc distribution system. The ultra-low loss bi-directional switch can be developed by the GaN power device because of the low on-resistance, the high-speed switching behavior and its own device structure. The buck-rectifier using the GaN bi-directional switches has the potential to achieve higher power density than the commonly utilized boost-rectifier. Availability of the GaN-HEMT （high electron mobility transistor） for the buck rectifier has been verified taking the theoretical limit of the on-resistance and the switching loss energy into account. Design consideration for a high power density buck-rectifier has been also conducted and the application effect of the GaN bidirectional switches has been evaluated quantitatively. The ISOP-IPOS converter-based dc （direct current） distribution system takes full advantage of the buck-rectifier and the rectifier using GaN devices contributes to realizing higher power density dc distribution system.

基于ZnO纳米线阵列和P3HT的混合光电二极管特性

为了发展低成本、大面积和高性能光电二极管,采用简单的化学浴沉积方法,在氧化铟锡(ITO)玻璃基底上生长良好取向的ZnO纳米线阵列(ZNWA),然后在生长的ZNWA上旋涂规整的聚3-己基噻吩(P3HT)层,形成结构为ITO/ZNWA/P3HT/Ag的光电二极管。系统研究了此光电二极管在暗态和在太阳模拟器的光照下的电流-电压(I-V)特性。实验结果表明,器件在暗态和光照下都表现出良好的二极管特性。暗态下,在偏压±2V处的整流率为3 211,理想因子为1.8、低开启电压为0.5V和反偏饱和电流为1.13×10-7 A。在20mW/cm2光照下,在偏压±2V处的整流率为39.1、开启电压为0.3V。器件中产生了大量的光生载流子,根据器件的能级结构图和光生载流子的输运过程对此光电二极管的光响应机理进行了解释。

ZnO纳米晶薄膜/p-Si异质结制备及其光电特性

为了发展高性能、低成本和结构简单的ZnO纳米器件,在本文中,利用简便的热分解法,在p型硅(p-Si)基底上制备ZnO纳米晶薄膜,利用场发射扫描电子显微镜(FESEM)、X射线衍射仪(XRD)、紫外-可见分光光度计和荧光光谱仪,分别研究了ZnO纳米晶薄膜的形貌、晶相结构和光学特性。结果显示:在p-Si基底上形成不规则颗粒状ZnO纳米晶,为多晶六方纤锌矿结构。ZnO纳米晶薄膜在可见光区光透过率高于90%,光学带宽为3.26eV,仅在387nm处出现一个很强的近带边(NBE)发射峰。进一步发现ZnO纳米晶薄膜/p-Si异质结在暗态和365nm紫外光照射下都出现整流特性,形成了二极管。在暗态下,该二极管的整流率为3.95(±2.46V),开启电压约为0.7V,理想因子为4.65,反偏饱和电流为4.57×10-8 A。在365nm的紫外光照射下,它的整流率高达24.85(±0.65V),说明它对365nm的紫外光有很高的响应,适合用于紫外光探测器。

Direct power control for three-level PWM rectifier based on hysteresis strategy

This paper presents a mathematical model of three-level voltage PWM rectifier,and derives a power control model from the theory of instantaneous power.In the vector-space,the influences on instantaneous power exercised by all the switching vectors are studied and illustrated separately,then a direct power control(DPC) scheme for three-level PWM rectifier which uses multistage band hysteresis comparator is proposed,and a novel switching table is designed.Meanwhile,the neutralpoint voltage unbalance is inhibited by selecting the redundancy switching states of small voltage vectors.Simulation and experimental results show that the proposed strategy can not only stabilize the DC bus voltage but also realize the unity power factor operation and the balance of neutral-point voltage.Moreover,the proposed method can improve the performance of the three-level rectifier.

Generalized Symplectic Mean Curvature Flows in Almost Einstein Surfaces

The authors mainly study the generalized symplectic mean curvature flow in an almost Einstein surface,and prove that this flow has no type-I singularity.In the graph case,the global existence and convergence of the flow at infinity to a minimal surface with metric of the ambient space conformal to the original one are also proved.