Design of inverse class-E amplifier with finite D.C. feed inductance

This paper reports on a design of inverse class-E amplifier with finite D.C. feed inductance. The finite D.C. feed inductance is resonated by the parallel capacitance at the fundamental frequency. The direct design equations required to determine the optimum operations are derived in detail. Comparing with the classic inverse class-E amplifier, numerical results show that improvements in minimizing size, cost, and complexity of the circuit can be obtained by the inverse class-E topology with finite D.C. feed inductance. Comparing with the sub-harmonic and parallel-circuit class-E amplifiers, the inverse class-E topology with finite D.C. feed offers advantages for MMIC realization. Theoretical analysis is validated by numerical simulation and measurement. Excellent agreement between theory and simulation results is achieved. Comparison between simulations and measurements of an experimental circuit validate the feasibility of the design. A measured output power of 40.01 dBm, with a drain efficiency of 80.16% and power-added efficiency of 78.93% were obtained at 250 MHz with a 22-dBm input power.     

Highly Stable Graphene‐Based Multilayer Films Immobilized via Covalent Bonds and Their Applications in Organic Field‐Effect Transistors

Highly stable graphene oxide (GO)‐based multilayered ultrathin films can be covalently immobilized on solid supports through a covalent‐based method. It is demonstrated that when (3‐aminopropyl) trimethoxysilane (APTMS), which works as a covalent cross‐linking agent, and GO nanosheets are assembled in an layer‐by‐layer (LBL) manner, GO nanosheets can be covalently grafted on the solid substrate successfully to produce uniform multilayered (APTMS/GO)N films over large‐area surfaces. Compared with conventional noncovalent LBL films constructed by electrostatic interactions, those assembled using this covalent‐based method display much higher stability and reproducibility. Upon thermal annealing‐induced reduction of the covalent (APTMS/GO)N films, the obtained reduced GO (RGO) films, (APTMS/RGO)N, preserve their basic structural characteristics. It is also shown that the as‐prepared covalent (APTMS/RGO)N multilayer films can be used as highly stable source/drain electrodes in organic field‐effect transistors (OFETs). When the number of bilayers of the (APTMS/RGO)N film exceeds 2 (ca. 2.7 nm), the OFETs based on (APTMS/RGO)N electrodes display much better electrical performance than devices based on 40 nm Au electrodes. The covalent protocol proposed may open up new opportunities for the construction of graphene‐based ultrathin films with excellent stability and reproducibility, which are desired for practical applications that require withstanding of multistep post‐production processes.     

IPv6过渡研究综述

IPv6已被确定为下一代互联网所使用的协议,现有网络向IPv6网络的过渡问题正成为研究热点.由于现有使用IPv4的互联网规模已经十分庞大,如何保护现有投资,使网络平稳过渡到IPv6是一个非常重要的问题.本文对IPv6过渡中的研究问题进行了综述,总结了IPv6过渡中使用的基本技术,对不同过渡场景下IPv6过渡技术的选择进行了比较和分析,对过渡中的安全问题进行了讨论.并分别从网络拓扑和协议层次角度对IPv6过渡进行了展望,指出了未来研究的方向.     

适合于多吉赫兹应用的0.5 V CMOS cascode低噪声放大器设计

本文介绍了适用于低功耗无线通信的0.5 V 多吉赫兹CMOS cascode 低噪声放大器设计。通过对传统cascode结构进行直流分离,去除了因堆积MOS管导致的工作电压限制。同时,采用正向体偏置技术,cascode结构低噪声放大器能工作在0.5 V供电电压。文章研究了电路设计细节和射频性能。为验证研究结果,采用台积电0.18微米射频工艺的0.5 V 5.4吉赫兹低噪声放大器被设计,制造出来并进行了测量。测量结果表明,该低噪声放大器在0.5 V工作电压下工作电流为5毫安,其增益为9.1分贝,噪声系数为3分贝,输入三阶交调点为-3.5 分贝毫瓦。通过和那些已发表的cascode低噪声放大器比较,本文的低噪声放大器具有工作电压低,功耗低而射频性能相当的特点。     

Review of roll-to-roll fabrication techniques for colloidal quantum dot solar cells

Colloidal quantum dots (CQDs) are of great interest to photovoltaic (PV) technologies as they possess the benefits of solution-processability, size-tunability, and roll-to-roll manufacturability, as well as unique capabilities to harvest near-infrared (NIR) radiation. During the last decade, lab-scale CQD solar cells have achieved rapid improvement in the power conversion efficiency (PCE) from ~1% to 18%, which will potentially exceed 20% in the next few years and approach the performance of other PV technologies, such as perovskite solar cells and organic solar cells. In the meanwhile, CQD solar cells exhibit long lifetimes either under shelf storage or continuous operation, making them highly attractive to industry. However, in order to meet the industrial requirements, mass production techniques are necessary to scale up the fabrication of those lab devices into large-area PV modules, such as roll-to-toll coating. This paper reviews the recent developments of large-area CQD solar cells with a focus on various fabrication methods and their principles. It covers the progress of typical large-area coating techniques, including spray coating, blade coating, dip coating, and slot-die coating. It also discusses next steps and new strategies to accomplish the ultimate goal of the low-cost large-area fabrication of CQD solar cells and emphasizes how artificial intelligence or machine learning could facilitate the developments of CQD solar cell research.     

电站锅炉引风机提高出力的改造

通过对朝阳电厂锅炉引风机出力不足原因的分析,提出了增加叶轮直径提高引风机出力的方法,改造后实际运行表明引风机性能完全满足锅炉额定负荷的要求,从根本上解决引风机出力不足的问题。     

影响LNG槽车运输储罐压力的因素分析

应用动态模拟软件,建立LNG槽车满载和空载运输系统动态模型,研究LNG槽车运输过程中储罐内操作压力、操作温度和液位的动态变化趋势。分析表明:LNG槽车满载长距离运输储罐压力上升较小,不易造成储罐超压泄放,安全性较高;空载运输较满载运输储罐升压速率更快;LNG储罐空载液位5%可实现LNG槽车储罐处于冷却状态。     

天然气增压卸车工艺的模拟与分析

为了克服LNG槽车空温气化器自增压卸车工艺流程复杂、效率低、卸车时间长、受环境因素干扰大、占地面积大的缺点,提出了一种天然气增压卸车工艺流程。采用流程数值模拟软件,建立天然气增压卸车工艺的计算模型,研究计算天然气增压卸车过程中LNG槽车储罐内压力、温度、液位等参数随时间的变化过程,计算卸车过程所需时间及天然气流量。分析表明,天然气增压卸车流程简单、卸车时间短、效率高,且不受环境条件影响,能够大幅提高卸车撬的利用率。     

BPV-I,II型防弹背心防护效果的实验研究

从抗弹丸贯穿和防止非贯穿性损伤的角度，观察几种复合式防弹层的防护效果和ＢＰＶ－Ｉ，ＩＩ型防弹背心的防护能力。构成ＢＰＶ－Ｉ，ＩＩ型防弹背心的材料有经特殊热处理的合金铝板，高强度锦纶绸和特殊结构的减伤层。实验结果表明：Ｉ型防弹背心能有效地抵御５４式７．６２ｍｍ手枪弹，有效防护距离３．４０ｍ以上；ＩＩ型背心可防护低，中速破片，Ｖ５０为ｍ／ｓ．动物防护实验表明：Ｉ型防弹背心可十分有效地防止器官组织的非贯     

某油田深冷空分制氮工艺优化研究

目的某大型油田采用深冷空分制氮工艺获取氮气来注氮驱油,为改善该工艺比功耗高、氮收率低等问题,利用中心复合旋转设计(CCRD)响应面分析法进行生产运行参数优化。 方法基于HYSYS软件建立深冷空分制氮流程,并对工艺中的关键运行参数进行单因素分析,由此确立各参数优化选值区间,利用CCRD响应面分析法在区间内进行参数寻优。 结果以工艺的比功耗最小为目标,使用工艺运行参数的最佳组合,优化后的流程氮气产量从16 905 m³/h增加到18 541 m³/h,提高了9.68%;氮气中氧摩尔分数从0.000 26%下降到0.000 24%,降低了7.7%;氮收率从70.92%上升到77.75%,增加了9.63%;比功耗从0.374 5 kW·h/m³下降到0.345 7 kW·h/m³,减少了7.69%。 结论利用CCRD响应面法进行生产运行参数优化对存在问题的改善有明显效果。 