滚压对6061铝合金微动磨损性能的影响

应用一种恒力式滚压工具,依据Box-Behnken中心组合设计原理,以车削进给量、滚压力和滚压次数为自变量,以在SRV IV实验机上实现的100℃下的无润滑条件和润滑条件下的微动磨损体积为响应值,对6061铝合金进行滚压后的微动实验,推导出了非平面微动磨损体积的计算公式,并对微动实验中的摩擦系数、试样初始表面粗糙度和磨...     

TFT-LCD液晶材料焚烧产物及反应过程分析

以TFT-LCD液晶为实验材料,研究了其焚烧失重特征,分析其焚烧产物并对其过程进行推测。结果表明,由多种单体化合物组成的TFT-LCD液晶材料焚烧反应过程主要发生在150～380℃,该过程导致约90%液晶损失;在焚烧过程中液晶材料首先发生分解反应,分解产物生成的先后顺序取决于其单体化合物的主要化学键键能大小;分解过程产生的烃类自由基和芳香族自由基极不稳定,前者进一步分解生成C原子更少的丙烯等烃类,后者会因高温进一步分解乃至脱F,同时自由基团之间重组发生再合成反应;液晶焚烧产生由多种芳香族化合物组成的混合物,焚烧温度高易生成PAHs和HF。TFT-LCD焚烧产物绝大多数是有毒有害物质,不宜进行焚烧处理。     

干线协调交叉口多相公交信号优先控制策略

针对干线协调交叉口多个相位有公交车到达的情况,为降低公交车延误,建立了以不破坏协调绿波带为前提的多相位公交优先控制策略.在该策略中,提出了“就近原则”以解决多个相位的公交优先申请冲突,对公交优先级别进行排序,并建立了多相位公交优先控制流程;考虑最高优先级别公交车的不同相位属性,采用绿灯延长和绿灯提前起亮两种优先方式,分...     

一种包边模边界缩进控制方法

 将确定性优化方法用于板料包边设计.汽车板料包边仿真中变形区域小导致有限元模型在变形区域的网格很小,模型计算时间太长.本文针对影响板料包边后边界缩进较大的3个参数,建立目标函数的径向基函数近似模型,并用确定性优化方法对近似模型进行优化,近似模型计算效率高,提高了优化方法计算效率,使板料包边的优化设计成为可能,并为生产中的汽车板料控制包边后的边界缩进提供了一种新的思路.     

并行埋地管道准周期土壤温度场的数值模拟

并行埋地管道中,常温输送的成品油管道会影响热原油管道的温度场,从而与单根输油管道的温度场不同.热油管道周围土壤温度场是管道停输再启动和管道运行的基础,只有准确掌握管道周围土壤温度场的变化规律,才能使管道安全运行,避免凝管事故发生.为了研究并行管道周围土壤温度场在准周期内的变化规律,以西部原油成品油管道四堡进站位置为例,在实测管道周围土壤物性的基础上,采用非结构化有限容积法对并行埋地管道周围土壤温度场进行模拟研究.模拟计算结果与现场实测结果基本吻合,表明提出的计算模型正确,计算结果能够为工程实际提供参考.     

基于低碳经济模式的山东省产业结构调整对策研究

在低碳经济时代,以山东省为研究对象,定量分析了其产业结构变化,估算了2005年以来的耗能情况和三次产业碳排放量.山东省三次产业结构模式与其产业能源消费模式和产业碳排放量模式具有一致性,在此基础上提出了山东省产业结构调整的对策建议,即改善产业能源结构,开发利用新能源;大力发展第三产业;强化行政铁腕,优化工业结构;开展低碳试点,发挥示范作用.     

An overview of resistive random access memory devices

With recent progress in material science, resistive random access memory (RRAM) devices have attracted interest for nonvolatile, low-power, nondestructive readout, and high-density memories. Relevant performance parameters of RRAM devices include operating voltage, operation speed, resistance ratio, endurance, retention time, device yield, and multilevel storage. Numerous resistive-switching mechanisms, such as conductive filament, space-charge-limited conduction, trap charging and discharging, Schottky Emission, and Pool-Frenkel emission, have been proposed to explain the resistive switching of RRAM devices. In addition to a discussion of these mechanisms, the effects of electrode materials, doped oxide materials, and different configuration devices on the resistive-switching characteristics in nonvolatile memory applications, are reviewed. Finally, suggestions for future research, as well as the challenges awaiting RRAM devices, are given.     

Evaluating the reliability of microsatellite genotyping from low-quality DNA templates with a polynomial distribution model

Molecular studies using trace DNA, such as from museum specimens, ancient or forensic samples and samples obtained noninvasively, often have a common problem of low quality of DNA templates. Amplification errors, such as allelic dropout and false allele, may arise during polymerase chain reaction (PCR) using such samples. A mathematical model which treats homozygotes and heterozygotes discriminately has been developed to measure sample quality and compute the confidence level of using multipletube approaches. We use plucked hair samples collected from 26 individual Sichuan snub-nosed monkeys (Rhinopithecus roxel- lana) to test the model. In this case, a confidence level of 99% can be achieved by three positive PCRs. If the sample quality is very poor and requires many PCR replicates, an alternative multiplestep genotyping method is recommended. This model enables researchers to optimize experimental protocols through pilot studies and obtain reliable genetic information using noninvasive sampling method.     

Aero-optical wavefront measurement technique based on BOS and its applications

A collimated light beam will be refracted if it propagates through a flow-field with index-of-refraction variations,and its wavefront will be distorted.If we measure the deflection angle of the light beam,the gradient of the wavefront can be obtained using the Malus law,and the wavefront aberration can be computed with a reconstruction algorithm.Two characteristics of background oriented schlieren(BOS) are conducive to wavefront aberration measurement:BOS can be used to measure the deflection angle of a light beam by measuring the displacement field between the reference image and the experiment image.Moreover,in a BOS system of Schlieren mode,only the ray perpendicular to the background image can be captured with a camera.This is helpful to measure wavefront aberrations that occur after a planar wavefront has passed through the flow-field.Based on these characteristics of BOS of Schlieren mode,a new wavefront measurement technique,which is called the BOS-based wavefront technique(BOS-WT),is proposed in this paper.It works by constructing the relationship between the displacement of the background image and the aero-optical wavefront gradient and uses the Southwell wavefront reconstruction algorithm.A BOS-WT system was assembled,and its temporal resolution was found to be 6 ns,and its temporal-correlation resolution reached 0.2 μs.A BOS-WT can measure the time-correlation transient wavefront quantitatively.It is simple and easy to operate.In this paper,we also present a study of the aero-optical performance of supersonic mixing layer based on our BOS-WT transient wavefronts at an interval of 5 μs.The results showed the wavefront was transient and distorted after it had passed through the mixing layer.Through the analysis of the data at the 5 μs interval,the temporal evolution of wavefront can be obtained.     

Development of cryogenically-cooled low noise amplifier for mobile base station receivers

A new circuit model for designing and manufacturing an S-band low noise amplifier(LNA) with the software,Advanced Design System(ADS),is introduced in this paper.The proposed model involves shunted impedance at the grid to achieve a stable LNA without measuring the S-parameters of transistors at low temperatures.The LNA was measured over the operation band of 2.2-2.3 GHz,which has input and output standing wave ratios below 1.2.The noise figure of the manufactured LNA was about 0.2 dB and the gain was above 22 dB,which indicated that our LNA worked well at 77 K.