PERFORMANCE ANALYSIS OF POWER SAVING CLASS OF TYPE Ⅲ IN IEEE 802.16E WITH USER INITIATED TRAFFIC

A novel method for analysing the performance of power saving class of Type Ⅲ in IEEE 802.16e is proposed,which is applicable to design,maintenance and management for mobile wireless metropolitan area network.Considering the memoryless nature of user initiated packet arrival,a Geom/G/1 queue model with multiple vacations and setup period is built to capture the principle for the power saving class of Type Ⅲ.By using an embedded Markov chain method and the boundary state variable theory,we obtain the queueing measures such as queueing length,waiting time and busy cycle in steady state.Correspondingly,we derive explicitly the performance measures for the power saving class of Type Ⅲ in terms of handover ratio,energy saving ratio,and average packet response time.Based on numerical results,we develop a cost function to determine numerically the optimal length of sleep window and the minimal cost with different offered loads.

Novel approach to harmonic control for Class F power amplifier with high power added efficiency

This paper presents a new topology to implement Class F power amplifier for eliminating the on-resistance (R_(ON))effect.The time-domain and frequency-domain voltage and current waveforms for Class F amplifier are ana- lyzed using Fourier series analysis method.Considering the on-resistance effect,the formulas of the efficiency,output power,dc power dissipation,and fundamental load impedance are given from ideal current and voltage waveforms.For experimental verification,we designed and implemented a Class F power amplifier,which operates at 850 MHz using MGaAs/GaAs Heterostructure FET(HFET)device,and analyzed the measurement results.Test results show that the maximum PAE of 67% can be achieved at 28 dBm output power level.

A High Power-Added-Efficiency 2.5-GHz Class-F Power Amplifier Using 0.5 μm GaN on SiC HEMT Technology

This paper proposed the high-frequency, multi-harmonic-controlled, Class-F power amplifier (PA) implemented with 0.5 μm GaN Hetrojunction Electron Mobility Transistor (HEMT). For PA design at high frequencies, parasitics of a transistor significantly increase the difficulty of harmonic manipulation, compared to low-frequency cases. To overcome this issue, we propose a novel design methodology based on a band-reject, low-pass, output matching network, which is realized with passive components. This network provides optimal fundamental impedance and allows harmonic control up to the third order to enable an efficient Class-F behavior. The implemented PA exhibits performance at 2.5 GHz with a 50% PAE, 14 dB gain, and 10 W output power.

A 1.8 GHz Power Amplifier Class-E with Good Average Power Added Efficiency

This paper presents a 1.8 GHz class-E controlled power amplifier (PA). The proposed power amplifier is designed with two-stage architecture. The main advantage of the proposed technique for output control power is a high 37 dB output power dynamic range with good average power adding efficiency. The measurement results show that the PA achieves a high power gain of 23 dBm and power added efficiency (PAE) by 38%. The circuit was post layout simulated in a standard 0.18 μm CMOS technology.

Using LDMOS Transistor in Class-F Power Amplifier For WCDMA Applications

The fundamental operating principle of a Class F power amplifier and the factors aiding or affecting Class F performance were explicated previously. A Class F power amplifier design which satisfies WCDMA specifications is explained in this paper. The Class F amplifier was designed by employing Motorola’s LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor models and we simulated its performance by means of ADS. A variety of procedures were applied in the process of designing Class F amplifier, namely, DC simulation, bias point selection, source-pull and load-pull characterization, input and output matching circuit design and the design of suitable harmonic traps, which are explained here.

X-band inverse class-F GaN internally-matched power amplifier

An X-band inverse class-F power amplifier is realized by a 1-mm Al Ga N/Ga N high electron mobility transistor（HEMT）.The intrinsic and parasitic components inside the transistor,especially output capacitor Cds,influence the harmonic impedance heavily at the X-band,so compensation design is used for meeting the harmonic condition of inverse class-F on the current source plane.Experiment results show that,in the continuous-wave mode,the power amplifier achieves 61.7% power added efficiency（PAE）,which is 16.3% higher than the class-AB power amplifier realized by the same kind of HEMT.To the best of our knowledge,this is the first inverse class-F Ga N internally-matched power amplifier,and the PAE is quite high at the X-band.

Inner Mongolia builds up world's class wind power generation farm

The first phase project of Huitengxile Wind Power Generation Farm in Inner Mongolia, with nine 600 kW wind power generators installed, was formally put into commercial operation on November 28,

Analysis of the third harmonic for class-F power amplifiers with an Ⅰ–Ⅴ knee effect

The appearance of third-generation semiconductors represented by gallium nitride （GaN） material greatly improves the output power of a power amplifier （PA）, but the efficiency of the PA needs to be further improved. The Class-F PA reduces the overlap of drain voltage and current by tuning harmonic impedance so that high efficiency is achieved. This paper begins with the principle of class-F PA, regards the third harmonic voltage as an independent variable, analyzes the influence of the third harmonic on fundamental, and points out how drain efficiency and output power vary with the third harmonic voltage with an I-V knee effect. Finally, the best third harmonic impedance is found mathematically. We compare our results with the Loadpull technique in advanced design system environment and conclude that an optimized third harmonic impedance is open in an ideal case, while it is not at an open point with the I-V knee effect, and the drain efficiency with optimized third harmonic impedance is 4% higher than that with the third harmonic open.

Study of the Effect of Using Power Point in an English Class

This action research aims to work out whether the effect of using powerpoint in an English class is positive or not.This research is carried out through the researcher’s lessons to a class of 45 students,experienced teachers and a philosophy teacher after previous meeting with the researcher are invited to observe the lessons with observation forms,questionnaires are completed by the students in the class and after class discussions.The conclusion from this action research is that in the context of the time and place when research is made,the Effect of Using Power Point in an English class is positive.

Power Quality Disturbance Classification Method Based on Wavelet Transform and SVM Multi-class Algorithms

The accurate identification and classification of various power quality disturbances are keys to ensuring high-quality electrical energy. In this study, the statistical characteristics of the disturbance signal of wavelet transform coefficients and wavelet transform energy distribution constitute feature vectors. These vectors are then trained and tested using SVM multi-class algorithms. Experimental results demonstrate that the SVM multi-class algorithms, which use the Gaussian radial basis function, exponential radial basis function, and hyperbolic tangent function as basis functions, are suitable methods for power quality disturbance classification.

基于D类功放的定向声频系统设计

为解决传统声音传播发散性和无指向性所带来的噪声扰民问题,设计实现了一种以超声波为载体,依据其具有波束窄、指向性强的特点和空气非线性实现的自解调原理,以D类功率放大器为核心的定向声频系统。经过实际使用,该系统工作稳定,定向性好,可以较好的解决噪声扰民问题。

非分段GaN HEMT EF2类功率放大器理论研究

目前,增强型氮化镓高电子迁移率晶体管(GaN HEMT)的仿真模型存在仿真时间长、复杂度高且收敛性不好等问题。为了解决GaN HEMT器件在电力电子电路中仿真收敛性和准确性差的问题,提出一种非分段的GaN HEMT SPICE模型。使用非分段连续方程对GaN HEMT器件的静态和动态特性进行建模;再对GaN HEMT的输出特性进行仿真,并与Si MOSFET的仿真结果进行对比。仿真结果表明,所提模型的收敛性较好,收敛速度快,有较高的准确性。另外,将此模型应用于EF2类功率放大器中,研究该模型对传输效率的影响。仿真结果进一步表明:该模型具有良好的收敛性;且当开关频率为10~20 MHz,输入功率为75 W时,输出功率可达73 W,传输效率为95%,这也证明了GaN HEMT器件可以提高EF2类功率放大器的传输效率。

3GPP R17高功率终端标准分析

为了提升5G网络上行覆盖范围和小区边缘用户的体验,包括运营商、网络设备、终端、芯片、器件厂商在内的整个移动通信产业链都在致力于提升移动终端的发射功率。重点分析了3GPP R17标准化工作完成的5G NSA、5G SA载波聚合和5G SA FDD模式下高功率终端的标准化解决方案和相关射频指标影响。

“两个结合”视域下五四时期阶级斗争思想传播力建构研究

阶级斗争思想是五四时期中国进步知识分子借以确立无产阶级革命信仰并改变中国革命进程的经典理论之一。陈独秀等五四精英将阶级斗争思想作为新民主主义革命的武器进行传播时,并非机械而教条地照本宣科,而是结合农民阶级在中国革命事业中举足轻重、中国反对帝国主义压迫及大同思想等传统文化根深蒂固的实际,对阶级斗争理论进行了顺应性调适。同中国具体阶级状况的实际和大同思想的结合,有力助推了阶级斗争思想在中国空前成功的传播。五四时期阶级斗争思想传播力建构中的两个结合,对当下中国化马克思主义著作的国际传播力建构颇具现实启示意义。

新型连续B/J类功率放大器设计

为满足无线通信技术对高性能功率放大器的需求,提出一种新型宽带高效率B/J类功率放大器的设计方法。区别于传统连续B/J模式,设计中引入变量因子重塑其时域电压波形表达式,推导出扩展的阻抗设计空间。扩展的阻抗设计空间增加了阻抗匹配的灵活度,拓展了带宽,同时仿真表明可获得与传统连续B/J类功率放大器相同的功率和效率。基于此新型阻抗匹配技术,设计了一款工作频段为1.5~2.5 GHz的GaN HEMT宽带功率放大器。测试结果表明,在该频率范围内,输出功率大于40.6 dBm,漏极效率为72.4%~79.1%,增益为10.6~11.9 dB表明,所提出方法具有有效性.

重新打开“阶级”的视野——长篇小说《艳阳天》再解读

长篇小说《艳阳天》系浩然以自己在顺义、昌乐等地农村经历为原型撰写而成,是当时主流文学史家眼中“阶级论”痕迹最为严重的作品之一,而“阶级论”确实在其中起到了至关重要的作用。但改革开放以来,学界对《艳阳天》的认识主要局限于“阶级论”且聚焦于其负面制约效果之上,难免有过于相信詹姆逊所言意识形态“遏制策略”的嫌疑。实则马克思主义的“阶级”内涵比我们目前所理解的要更加深刻、复杂,更能深入“现实的个人”及其所置身的经济环境和社会环境,而《艳阳天》也在阶级话语的面影之下隐藏着更为广阔、芜杂的世界。只有重新打开“阶级”的视野,我们才能充分面对《艳阳天》所揭示的生气饱满的“追求着自己目的”的众生相,以及马克思主义难以解释的以关系和权力为核心的乡村中国复杂政治经济生态和生存逻辑。然而,《艳阳天》并不止于自然主义地呈现权力与关系,其目的仍在创构新的以平等为前提、兼通“小”“大”的文化共同体,这使之成为所谓“机械社会主义”在20世纪50至70年代文艺实践中的成功案例,值得今日学界重新辨识、发现。

用于非线性超声检测的高频高功率E类功率放大器研究

超声波与金属的微小缺陷相互作用可产生非线性效应,由于非线性效应信号弱,在微小缺陷检测时必须采用高频高功率的发射装置来增强非线性效应信号强度。为此研究了一款高频大功率的超声驱动放大电路,该放大电路选用开关速度快、耐高压的氮化镓晶体管设计高效率的零电压开关(ZVS)型E类功率放大器,设计开关管保护电路、输入输出匹配电路以及可独立控制导通和关断驱动强度的栅极驱动电路,确保了高频高压大功率信号的高效输出。经测试,该E类功放驱动电路在工作频率为5 MHz,供电电压100 V时瞬时输出功率为223.9 W,峰值电压为150 V,直流转换效率为76.7%,表明该驱动电路可以用做高频大功率超声发射驱动。

基于E类功率放大器的四线圈中距离无线输电系统的优化设计

E类功率放大器由于具有拓扑简单、适用频率高、电能转换效率高等优点,是高频MHz级无线输电系统的理想电源。研究分析了四线圈无线输电系统的传输特性,提出传输效率的优化设计方法。同时,考虑到E类功率放大器的工作状态,提出通过激励线圈与发射线圈的距离调节,实现输入电阻的完美匹配,搭建了采用2.81 MHz的E类功率放大器的四线圈中距离无线输电系统。当传输距离为传输线圈边长的3.6倍时,系统电源端到负载端的整体电能传输效率为8.5%。