Characterizing big data analytics workloads on POWER8 SMT processors

Big data analytics is emerging as one kind of the most important workloads in modern data centers. Hence,it is of great interest to identify the method of achieving the best performance for big data analytics workloads running on state-of-the-art SMT( simultaneous multithreading) processors,which needs comprehensive understanding to workload characteristics. This paper chooses the Spark workloads as the representative big data analytics workloads and performs comprehensive measurements on the POWER8 platform,which supports a wide range of multithreading. The research finds that the thread assignment policy and cache contention have significant impacts on application performance. In order to identify the potential optimization method from the experiment results,this study performs micro-architecture level characterizations by means of hardware performance counters and gives implications accordingly.

Characterization of Power-Function Distribution through Expectation

For the characterization of the power function distribution, one needs any arbitrary non constant function only in place of independence of suitable function of order statistics, linear relation of conditional expectation, recurrence relations between expectations of function of order statistics, distributional properties of exponential distribution, record valves, lower record statistics, product of order statistics and Lorenz curve, etc. available in the literature. The goal of this research is not to give a different path-breaking approach for the characterization of power function distribution through the expectation of non constant function of random variable and provide a method to characterize the power function distribution as remark. Examples are given for the illustrative purpose.

NONLINEAR CHARACTERIZATION OF CONCURRENT DUAL-BAND RF POWER AMPLIFIERS

In this paper, the synchronous concurrent dual-band RF signal is used to drive the RF Power Amplifier (PA). The nonlinear characterization of a concurrent dual-band RF PA is discussed while two band signals in the dual-band are modulated by CDMA2000 and WCDMA signals. When the two band signals in the dual-band of the PA are modulated with the same signals, it is found that the nonlinearity of the PA can be expressed by any of the two corresponding baseband data. On the other hand, when the two band signals in the dual-band of the PA are modulated with two different signals, the PA nonlinearity cannot be characterized by any of the two corresponding baseband data. In this case, its nonlinearity has to be denoted by a composite signals consisting of the two baseband signals. Consequently, the requirements for the speed of the A/D converter can be largely reduced. The experimental results with CDMA2000 and WCDMA signals demonstrate the speed of the A/D converter required is only 30 M Sample Per Second (SaPS), but it will be at least 70 M SaPS for the conventional method.

电厂粉煤灰、炉渣和污泥复合陶粒对低浓度Pb^(2+)的吸附特性

针对重金属污染具有来源广、危害大等特点,通过以电厂废物(粉煤灰、炉渣)和脱水污泥为原料制备一种高效且价廉的陶粒吸附剂,采用吸附影响因素实验、解吸再生实验、吸附动力学模型和等温吸附模型的拟合以及陶粒表征分析,探究陶粒对Pb^(2+)的吸附特性,同时为实现废物资源化利用提供新思路.结果表明:陶粒去除Pb^(2+)的较佳吸附条件为粒径4 mm、pH 4.5~5.0、吸附时间360 min、吸附温度25℃.陶粒再生所用较佳解吸剂为0.5 mol/L的HCl溶液,较佳解吸时间和次数分别为120 min和5次,解吸5次后陶粒对Pb^(2+)的去除率为92.67%.此吸附过程更好地遵循了准二级动力学模型和Freundlich等温吸附模型.陶粒上的O-H、Si-O和金属氧化键在吸附Pb^(2+)的过程中起主要作用.陶粒吸附Pb^(2+)后,出现了新的物相Pb_(2)Cl_(3)OH和PbO,陶粒与Pb^(2+)之间发生化学吸附,为自发进行的放热反应.陶粒处理实际废水中Pb^(2+)的去除率可达93.70%,Pb^(2+)浓度由3.74 mg/L降至0.24 mg/L.研究显示,电厂粉煤灰、炉渣和污泥复合陶粒对Pb^(2+)具有一定的去除效果,可为以固体废物为原料制备的吸附剂在重金属废水处理应用中提供数据支撑.

飞机货舱可燃物在干扰源状态下火灾特征参数研究

目前民用飞机货舱主要采用传统光电式烟雾探测器来识别火灾烟雾,但由于飞机货舱中悬浮有其他干扰颗粒(灰尘、水蒸气等)会触发火灾探测器报警,传统光电式烟雾探测器存在误报率高的问题。采用基于双波长及索特平均粒径的光电式烟雾探测器采集飞机货舱典型燃烧物、干扰源的红外光散射功率、蓝光散射功率,以此作为火灾参数,通过对颗粒物红外光散射功率与蓝光散射功率进行分析,结合索特平均粒径分析,为研发复合型烟雾探测器优化火灾参数。结果表明:红外光和蓝光对火灾烟雾颗粒有较好地响应,结合索特平均粒径,可以有效区分火灾烟雾颗粒与非火灾烟雾颗粒,降低误报率,干扰源误报率不超过6.7%。

Voltage Sag Characterization in a Distribution Systems: A Case Study

Voltage sags caused by the short-circuit faults in transmission and distribution lines have become one of the most important power quality problems facing industrial customers and utilities. Voltage sags are normally described by characteristics of both magnitude and duration, but phaseangle jump should be taken into account in identifying sag phenomena and finding their solutions. In this paper, voltage sags due to power system faults such as single phase-to-ground, phase-tophase, and two-phase-to-ground faults are characterized by using symmetrical component analysis and their effect on the magnitude variation and phase-angle jumps for each phase are examined. A simple and practical method is proposed for voltage sag detection, by calculating RMS voltage over a window of one-half cycle. The industrial distribution system at Bajaj hospital is taken as a case study. Simulation studies have been performed by using MATLAB/SIMULINK and the results are presented at various magnitudes, duration and phase-angle jumps.

Characteristics of GaN Thin Films Using Magnetron Sputtering System

The paper presents a polycrystalline GaN thin film with a hexagonal wurtzite structure under the optimized sputtering conditions of 40 W RF power, 5 mT working pressure, using pure nitrogen gas with a substrate temperature of 700°C. The study examines the effects of surface disorders and incorporates it in the thin films characteristics. A radio frequency (RF) Ultra High Vacuum (UHV) Magnetron Sputtering System has been used for the deposition of Gallium Nitride (GaN) on silicon, sapphire and glass substrates with different parameters. The power is varied from 40 W to 50 W, and the pressure from 4 mT to 15 mT. The effects of the RF sputtering powers and gas pressures on the structural properties are investigated experimentally. Sputtering at a lower RF power of 15 W does increase the N atomic percentage, however the deposition rate is substantially slower and the films are amorphous. GaN deposited on both silicon and sapphire wafer resulted in thin films close to stoichiometric once the N2 concentration is 60% or higher. It is also observed that the substrate cooling/heating effects improve the quality of the thin films with fewer defects present at the surface of the GaN epi-structure.

基于折纸结构的摩擦电-电磁复合风速传感器研究

本文基于三浦折纸结构和摩擦纳米发电机原理,设计了一种具有自供电功能的复合风速传感器,实现了自然环境中风能向电能的转换,并根据折纸结构受圆柱轮-旋转模块的按压而折叠时所产生的摩擦电信号,实现风速准确测量;沿圆周分布的折纸TENG能量转换组件具有较快的充电效率;将摩擦静电感应与电磁感应技术相结合,提高了能量收集效率,实现了自供电;与商用风速仪的测量对比,其风速测量范围为(2~10)m/s,测量准确度>95%。

面向空间引力波探测的程控低噪声高精度电压基准源

引力波探测打开了探索宇宙的新窗口,开启了多信使天文学时代.大型激光干涉仪作为空间及地基引力波探测装置,需要使用低噪声激光光源,通过光电负反馈降噪技术可以抑制激光噪声,提高大型激光干涉仪的灵敏度.光电负反馈控制需要将光电探测器信号与电压基准源信号相减,之后经过比例积分微分器得到误差信号,来控制泵浦电流驱动器的输出功率,从而实现激光噪声抑制.由于光电探测器信号受激光强度影响,其输出电压在一定范围内变化,这就需要电压基准源信号的输出电压可变;另外,电压基准源的性能直接影响反馈控制环路的整体性能,是激光噪声抑制的下限.本文通过选定低噪声基准芯片及数模转换芯片,设计外控电路、采用低温漂系数元件、通过精密布板及电磁屏蔽等方案,研发高精度低噪声程控电压基准源;并通过可编程逻辑门阵列模块编程控制数模转换,实现程控电压基准源输出电压精密变化.结果表明:所研发的电压基准源输出电压范围为-10V—+10 V,输出电压分辨率达20 bit,在空间引力波频段输出电压的相对噪声谱密度低于9.6×10^(-6)Hz^(-1/2),基准源噪声性能均优于相应引力波探测中对激光强度噪声要求,为引力波探测中激光强度噪声抑制等方面提供关键器件支撑.

奋斗精神的哲学省思

奋斗精神是人有意识、有目的地付出体力脑力劳动的精神先导,是人积极行动的内在精微动力。以哲学的方法洞察奋斗精神的深刻意蕴,其学术旨趣在于以奋斗精神的思想文化本性与人的实践活动为主题,从奋斗精神的语意流变中理解奋斗精神所指向的驱使人做出具有正向价值的行为、行动、活动、动作的内在因素之维度;从人的精神世界的丰富构成中揭示奋斗精神与理想信念、价值选择、道德情操、意志品质等相互区别又相互联动的关系网络;从奋斗精神的外化呈现探究由奋斗主体、奋斗动机、奋斗目标、奋斗实践等构建的表征体系。

“华龙一号”安全级三相交流调功器的设计与鉴定

为解决核电厂调功器全部依赖进口、进口产品价格昂贵且供货周期长的问题,以“华龙一号”项目为例,创新性地研制了国产化安全级三相交流调功器。根据核电厂调功器的性能需求完成了外形、接线、原理设计,实现了对电加热器的功率调整功能,顺利通过了所有型式试验及K3类鉴定试验。试验结果证明:自主研发的三相交流模拟量调功器可以满足各项性能指标及鉴定试验的相关要求,符合核电厂安全级/非安全级设备使用要求;大幅度缩短了供货周期,保证了现场施工进度,降低了工程造价;为后续核电厂安全级仪控设备出口项目奠定了技术基础。

功率型锂离子动力电池的内阻特性

为了深入分析功率型锂离子电池的内阻特性及影响因素之间的关系,本文利用混合脉冲功率特性测试方法(Hybrid Pulse Power Characterization,HPPC)测试锂离子电池在不同温度环境、荷电状态(Stage of Charge,SOC)下的内阻变化规律,实验结果表明锂离子电池内阻在低温环境和较低SOC下变化明显.最后利用多项式最小二乘法拟合得到锂离子电池内阻与环境温度之间的关系表达式,为下一步实现电池功率在线预测提供了数据支持和理论基础.

片状金属粉体在颜料及电子浆料中的应用

二维平面结构的片状金属粉体,由于具有良好的附着力、显著的屏蔽效应、较强的反射光线的能力以及优良的导电性能,使其在颜料及导电浆料等领域得到了广泛的应用。本文中在对片状粉体结构表征方法进行阐述的同时,对几种重要的片状金属粉体的制备、性能及应用进行了探讨。颜料用金属粉体对金属光泽要求高,在制备过程中要求片状粉体的表面具有较高的平整度和光亮度,而作为导电浆料用的贵金属粉体要求产品纯度高、粒子结构均匀、具有优良的导电性能,选择适宜的制备方法尤为重要。

基于大平板热管的电池热管理实验及仿真

热特性是影响锂离子电池性能的主要因素之一,当电池以较高倍率进行充放电时,热量聚集使温度迅速上升,影响电池性能,甚至会产生燃烧或爆炸。本工作搭建了一种基于大平板热管的高效高均温性电池散热模型。电池组置于大平板热管上,底部辅以风冷散热,在不同工况下对电池表面平均温度及最大温差进行数值计算,并通过实验验证了热管理模型准确性。结果表明,当环境温度为20℃、冷却风速为5 m/s、以1 C放电至截止电压时,电池组平均温度为38℃,最大温差为1.9℃;在大平板热管散热端适量布置翅片可增大换热面积,提高换热效率。

基于PNGV电路模型的航空钴酸锂电池内阻研究

对航空钴酸锂离子电池进行PNGV建模。通过模型的建立,可依据测试出的外部变量值来估算电池的内部状态变量。实验使用HPPC(hybrid pulse power characterization)法来获取锂电池在脉冲加载和过渡过程中的各项参数。最后通过Matlab/Simulink对电池的PNGV等效模型进行仿真分析。研究表明:所选取的PNGV模型精度高,能真实地模拟电池充放电特性;在固定温度和已知SOC的情况下,模型参数能得到较准确的估计。本实验结论可为锂电池的内部状态变量估算提供理论依据。

从话轮转换看权势关系、性格刻画和情节发展

话轮转换是新兴的戏剧文体学研究方法。试在前人的基础上 ,进一步完善话轮转换量化分析的研究框架 ,并以阿瑟·米勒的剧本《推销员之死》片断为例 ,研究话轮转换与戏剧人物权势关系、性格刻画和情节发展的关系。实例分析表明 ,本框架不仅有描述充分性 。

强激光光束质量评价和测量方法研究

长期以来对于强激光光束质量一直没有统一的评价标准和规范的测量方法,这给强激光系统的试验鉴定带来很大困难,也给科学研究和工程应用带来诸多不便。针对系统性能测试评价的迫切需要,对此问题进行了分析和研究,提出了一种光束质量的评价方法和具体的测量方法及技术。

超精密加工表面特性的功率谱密度表征与分析

为了了解加工方法和参数对加工表面特性PSD表征结果的影响规律,采用功率谱密度方法(PSD)对超精密磨削加工表面进行了表征与分析.应用Dimension 3100原子力显微镜对超精密加工表面进行测量,得到三维微观形貌和数据,以空间波长为横坐标,功率谱密度为纵坐标输出PSD图像,简单直观地分析了加工表面空间波长分布及不同波长在表面所占的比重,对比分析了加工方法和参数对PSD表征结果特征的影响.实验结果表明,超精密加工表面PSD图像的主导频率、波长分布特点以及各波长的PSD值大小等参数不仅可以同时体现横向尺寸及高度尺寸特性,而且能够得到表面误差的空间频率分布和方向特性信息.

基于工业合金激光熔覆制备Fe基非晶涂层

以FeCoCrMoCBY块体合金为熔覆材料,采用激光熔覆在低碳钢表面制备非晶涂层,探讨不同激光功率对涂层成形及组织的影响,通过显微硬度仪、电化学工作站测试涂层显微硬度及耐腐蚀性能。研究结果表明,其他参数不变,激光功率为17.6~20.8 W时,涂层成形良好,与基材呈典型冶金结合。随激光功率增加,涂层稀释率升高,裂纹倾向增大,非晶化程度降低。激光功率为17.6 W时,涂层主要由非晶组成,稀释率低于24.2%,结构致密,包括热影响区、熔合区和熔覆区;涂层平均显微硬度为1 330HV,约高于基材9倍,在3.5%NaCl溶液中的耐腐蚀性能明显优于316L不锈钢。