与工艺、电源电压和温度无关的低功耗振荡环设计

分析了传统片外时钟和片内时钟各自的特点和应用背景,在Chartered 0.35μm CMOS工艺下实现了一个低功耗PVT(工艺、电源电压、温度无关)振荡环,对片内时钟的稳定性和功耗进行改进。该振荡环无需精准的电压源,采用了误差补偿技术,通过偏置电压和延时单元的相互补偿,使得振荡频率对于工艺、温度和电源电压均有较大的容差能力。并且由于针对延时单元补偿的方式,令周期大小易于调整。蒙特卡罗仿真显示,工艺误差引起的偏差要比补偿前的偏差减小了60%。流片测试结果表明,在工作温度变化范围0~100°C时,振荡环输出的频率偏差为±3.22%;在电源电压变化范围为2.8~3.8 V时,振荡环输出的频率偏差为±3.36%;在电源电压3.3 V的情况下,整个芯片消耗的电流为950μA。     

How to Measure a City's Metabolism

Very little of what feeds and builds London comes from the city itself, and even less of the waste stays there. Instead, in order to feed, clothe, power, and build today's major metropolises you need the product of thousands of square kilometers outside the city limits. And you need thousands of square kilometers more to absorb the discards. So far, the largest urban area to have its footprint measured systematically is London. The results appeared in a report titled City Limits, released in 2002. It was found that London's ecological footprint was 49 million global hectares - 293 times its geographical area and equivalent to two United Kingdoms. On a per-person basis, Londoners took up 6.6 global hectares, putting them on a par with the Swiss and making them twice as frugal as the average American, but still more than three times as voracious as what the Earth can provide.     

Minimizing the Supply Sensitivity of a CMOS Ring Oscillator Through Jointly Biasing the Supply and Control Voltages

A method to minimize the supply sensitivity of a CMOS ring oscillator is proposed through joint biasing of the supply and the control voltage. The technique can supplement a number of common supply rejection techniques and can be exploited to compensate for the noise coupling caused by the parasitic capacitance in the loop filter of a phase-locked loop (PLL). The proposed CMOS ring oscillator is designed and implemented with a charge-pump based PLL in 65-nm technology to demonstrate the robustness against the supply fluctuation. Taking advantage of the negative static supply sensitivity of the ring oscillator with proper combination of the bias voltages, the rms jitter of the 5.12-GHz output clock is reduced from 6.41 ps to 2.38 ps while subject to supply noise at 90 MHz.      

变频器在水行业节能降耗中的巨大作用

源水输送、城市给水排水处理、各工矿企业上下水处理系统，城镇高层楼群的二次供水系统，用电大户能耗严重，必须重力研究各工艺流程的特点和能耗情况，广泛而又科学的选用合适的变频器，使传统的耗能大户，做到有效的节能降耗。     

激光推进环聚焦数值模拟研究

设计了激光推进环聚焦系统,在考虑入射激光束与光船聚焦系统主轴偏离情况下,建立研究环聚焦性能的数学模型,并数值模拟研究了环形"点火"线的形状、大小、能流密度以及点火区域空间特性.数值分析结果表明:环聚焦系统在喷管内产生半径约为49 mm的环状点火区域,比点聚焦产生的点状点火区域要大一个数量级,从而使吸收室内工质加热更加均匀;当激光束从垂直入射到偏离入射变化时,聚焦能量不再均匀地分布在圆形环线上,而是向x轴聚积,整个点火区域呈扁环状,因此,近椭圆柱状喷管设计将极大地提高激光能量转换效率.     

高压变频器PID控制压力分时赋值功能的现场应用

为响应国家节能降耗的要求,城市供水系统采用变频调速方案,不仅可以收到很好的节能效果,而且能够确保城市供水管网的运行安全。本文以吉林某市水务集团为例,结合新风光变频器的PID控制原理,详细介绍了风光变频压力分时赋值功能在城市供水系统中的应用。     

基于模糊控制的自动供水教学系统的设计

恒压供水系统是机电类专业教学中常用的典型系统。在分析和比较国内外自动控制恒压供水教学系统的前提下,以PLC为控制器,采用模糊控制技术、变频技术,设计出供水控制教学系统,该系统注重节能,符合人体工学,对于培养学生的独立思考能力,学习能力和动手能力有极大的促进作用。操作方便,功能完善,设计思路可为同类教学用控制系统提供借鉴。     

Sans sulphur-the Drax FGD project

The author discusses the reasons for the Drax coal fired power station flue gas desulphurisation (FGD) retrofit. It's National Power's biggest project, will take eight years to finish, and cost £684 million. At the end of 1993, the first phase of the project was completed with the handover by Babcock Energy, the project's principal contractor, of the first two SO₂ absorber vessels and associated plant. A further two absorbers will become operational in 1995, and the project will be completed in mid 1996 when the last two absorbers are handed over. The Drax absorbers use the limestone-gypsum process, applied in more than half the world's FGD installations, although never before on such a huge scale. The absorbers and their operation are discussed     

基于半导体纳米线的环形激光器

针对微光电子机械系统(MOMES)传感器件对微型片上光源的需求与当前半导体纳米线结构制备的进展,设计了一种基于Ⅱ-Ⅵ族半导体纳米线的激光器。将生长出来的纳米线在纯净水中超声制备均匀分布的悬浊液,再滴至载玻片表面,在显微镜50×物镜下观测得到纳米线呈现稀疏分布,约2~3根,选择尺寸较长的纳米线作为制备环形谐振腔的材料。首先使用355 nm激光激发单根的纳米线,得到半导体纳米线受激发射的以505 nm为中心波长的绿光,半高全宽(FWHM)为20 nm,然后采用光纤探针和微米位移平台操控纳米线,制备了一个半径约10μm的环形谐振腔,并得到其激发光谱,谐振峰的中心位置在521.5 nm处,FWHM为0.19 nm,由此计算得到的品质因子值为2700,制备得到的谐振腔激光器可以满足MOMES器件集成的需要。     

A Novel Optical Code Division Multiple Access Ring Network System for LAN

1　Introduction　OpticalCode DivisionMultiple Access (OCDMA )communicationsystemshavebeengivenaconsiderableinterestcurrently[1～ 8] .InanOCDMAsystem ,alluserscansimultaneouslysharethesamechannel,asyn chronouslyaccessthenetwork ,andflexiblyutilizethebroadbandwidth .ThesecharactersmakeitpossibleforanopticalnetworkemployingOCDMAtechniquesasonelayerofamultiplexinghierarchy .Forexample ,ahybridOCDMA/WDMAnetworkwillbepossiblewhenitiscombinedwithWDM[4 ] .Asaresult ,OCDMAtechniquehasbee…     

高压变频器在热电厂锅炉恒压供水上的应用

本文阐述了高压变频器在热电厂锅炉给水中的应用。利用变频调速系统自带的PID功能结合压力变送器实现闭环控制,为恒压供水提供一种可行的方案。文中所示的数据表明锅炉给水泵的高压电机的变频节能改造是可行的。     

EPON系统环网保护组网方式

提出可以实现EPON系统业务保护和故障恢复的快速环网方式。在OLT上通过快速以太网环网,在PON口采用主干光纤保护或全保护,在ONU侧通过手拉手保护组网方式,实现整个EPON系统的冗余保护。此保护方式达到了保护时间小于50 ms的电信级要求,而且具有算法简单、拓扑收敛速度快,业务恢复时间快等显著优势。EPON系统网络拓扑,采用此种组网方式能有效地提高以太网环网的可靠性和稳定性,实现较好的业务保护效果。     

SDH系统STM-16速率级CMOS注入同步环形振荡器

基于0.25μm CMOS工艺,通过在环形振荡器的基础上引入注入同步技术,实现了一种新颖的应用于SDH系统STM-16速率级的注入同步振荡器.测试结果表明,该振荡器中心频率为2.488GHz,具有150MHz的电压调谐范围,相位噪声为-100dBc/Hz@1MHz.当注入峰峰值为50mV的信号时,相位噪声为-91.7dBc/Hz@10kHz,并具有100MHz的锁定范围.应用这种注入同步振荡器于时钟恢复电路的高Q值锁相环时,可以解决窄锁定范围的问题,而无需另加复杂的锁频环.     

自来水厂监控系统中GPRS技术和PLC的运用

水是生命之源,随着经济的发展及人们对水需求量的增大,自来水厂应该逐渐改进着供水系统的运行模式,在监控系统中引进GPRS和PLC技术,不仅能使供水体系更完善,还能进一步提高其智能监管的程度.     

夹持环对换能系统振动模态影响的有限元分析

换能系统是热超声引线键合装备的核心部分,夹持环对系统起安装支撑的作用,其安装方式直接影响换能系统的能量传递与振动模态。利用有限元法分析了夹持环对换能系统振动模态的影响,结果表明,对夹持环未施加约束、施加z向约束时换能系统的夹持环会出现振动现象,而施加x向约束时,工作频率下的主振型完全不符合要求;改变夹持环的安装位置,对换能系统的节点位置及谐振频率都有一定的影响,实验测得在全约束情况下,换能系统的节点位置为58 mm,与分析结果一致;换能系统在工作频率附近包含有其他的振动模态,在键合过程中易被激发出来,由此消耗超声能量而降低芯片的键合质量,这些振动模态必须得到抑制。     

T-Ring 无线电综合测试场的构建

Outfield testing is an effective measure to check the performance of wireless networks and facilities. Current outfield testing environment has inherent fluctuation due to the wireless propagation condition and has other disadvantages such as nonsupport for multiple scenarios, and low level yet high cost auto control capability. In this paper, the conception of a radio testing environment, known as T Ring (Integrated Testing Ring), is proposed. It is based on a novel fitting degree evaluation frame. The testing ring can achieve high level of fitting degree to the real network so that the fluctuation of the wireless environment will be under control or even eliminated. This paper will choose some typical performance indicators and obtain corresponding statistical data in both the real network and system level simulation. A complete set of procedures is also given in this paper to evaluate the fitting degree of testing results and simulation results. It proves that the simulation highly fits to the real network and the simulation configuration can be used to construct the testing ring. At the same time, the advanced radio testing ring integrates multiple radio access technologies, scenarios and facilities from different manufacturers. It can improve the efficiency of wireless outfield testing and lower the cost of operators and manufacturers.     

基于PLC控制的变频调速恒压供水系统的探讨

为达到供水质量和供水系统可靠性的要求,再加上目前能源紧缺,利用先进的自动化技术、控制技术以及通讯技术,设计高性能、高节能、高适用性的恒压供水系统成为必然趋势。本文着重研究并提出了基于PLC和变频器的恒压供水系统的方案,并给出了硬件设计和PLC控制程序设计。采用PLC控制的变频调速供水系统,由PLC进行逻辑控制,由变频器进行压力凋节,再经过PID运算,通过PLC控制变频与工频切换,实现闭环自动调节恒压变量供水,通过压力传感器对水压的反馈构成闭环控制系统以及PID模块根据用水量的变化调节水泵的输出流量。运行结果表明,该系统具有压力稳定,结构简单,工作可靠等特点,并能达到有效节能的目的。     

Tunable Superparamagnetic Ring (tSPRing) for Droplet Manipulation

The manipulation of droplets via a magnetic field forms the basis of a fascinating technology that is currently in development. Often, the movement of droplets with magnets involves adding magnetic particles in or around the droplet; alternatively, magneto responsive surfaces may also be used. This work, presents and characterizes experimentally the formation and properties of a tunable superparamagnetic ring (tSPRing), which precisely adjusts itself around a water droplet, due to liquid–liquid interaction, and enables the physical manipulation of droplets. The ring is made of an oil-based ferrofluid, a stable suspension of ferromagnetic particles in an oily phase. It appears spontaneously due to the oil–water interfacial interaction under the influence of a magnetic field. The ferrofluid–water interaction resembles a cupcake assembly, with the surrounding ring only at the base of the droplet. The ring is analogous to a soft matter ring magnet, showing dipole repulsive forces, which stabilizes the droplets on a surface. It enables robust, controllable, and programmable manipulation of enclosed water droplets. This work opens the door to new applications in open surface upside or upside-down microfluidics and lays the groundwork for new studies on tunable interfaces between two immiscible liquids.     

Exact Results for Nonsymmetric Token Ring Systems

This paper derives exact results for a token ring system with exhaustive or gated service. There areNnodes on the ring and control is passed sequentially from one to the next. Messages with random lengths arrive at each node and are placed on the ring when the control arrives at that node. Exhaustive service means that the queue at a node is empty before the token is released and gated means that only those messages in the queue at the arrival of the token are served at that cycle. Generating function recursions for the terminal service time (the total sojourn time of a token at a node) and, from this, joint cycle and intervisit times are derived. Using known results relating the marginal generating functions of the waiting time and the cycle and intervisit time, it is shown that theNmean waiting times at the nodes require the solution ofN(N - 1)and N²equations for the exhaustive and gated cases, respectively. The arrival processes are assumed to be Poisson with different rates and the service processes are general and different at each node. In addition the token overhead is allowed to have an arbitrary but independent distribution at each node. Explicit, simply programmed equations are given. It is shown, arguing from the form of the equations, that there is a conservation law in effect in this system. If the nodal mean waiting times are weighted by the relative intensity, defined here as the intensity weighted mean, then the sum takes on a particularly simple form and is independent of the placement of the nodes on the ring. When the service means at each node are equal, this quantity is just the system mean waiting time.     

Core–Ring Structured NiCo2O4 Nanoplatelets: Synthesis,Characterization, and Electrocatalytic Applications

An innovative nanostructure, namely the core–ring structure, is reported in this paper. It occurs in NiCo₂O₄ nanoplatelets, synthesized by the coprecipitation decomposition method using sodium hydroxide as the precipitant. The yield of core–ring hexagonal NiCo₂O₄ nanoplatelets is greater than 80% at 200 °C. A high‐resolution transmission electron microscopy and energy dispersive spectroscopy investigation reveals the typical core–ring nanostructure, which shows a strong enrichment of Co in the core with a Co content higher than 80%. A mechanism for the core–ring structure formation is proposed. The core–ring NiCo₂O₄ can be used as an electrocatalyst for an oxygen evolution reaction (OER) in alkaline water electrolysis. Compared with the electrodes of ordinary NiCo₂O₄ and Co₃O₄, or other NiCo₂O₄ electrodes prepared by alternate methods, the electrode coated by core‐ring NiCo₂O₄ nanoplatelets exhibits the greatest electrocatalytic properties, with an over‐potential of 0.315 V at a current density of 100 mA cm^?2.