基于不平衡同频激励的密封动力特性系数识别

针对传统频域识别密封动力特性系数方法存在的问题,提出利用转子不平衡实现同频激励,在2组不平衡状态下构建4个独立方程,建立密封动力特性系数识别模型。在密封试验台上研究了转子不平衡、转速、进出口压比等因素对密封动力特性系数的影响。试验结果表明动力特性系数中直接项系数相近,交叉项大小相同,符号相反。随着进出口压比和转速的增大,8个密封动力特性系数都增大,直接刚度项增大幅度较交叉刚度项更为明显,直接阻尼项增大幅度与交叉阻尼项接近。同时发现相对振动大小对动力特性系数影响并不大。对影响动力特性系数识别精度的因素进行了分析,提出了试验转速、不平衡工况的合理选择方法。     

废旧高温合金酸浸工艺研究

以硫酸为浸出剂,采用正交法,研究了废旧高温合金浸出的最佳工艺条件。结果表明,在下述优化后的条件下,镍、钴的浸出率均达99.5%以上、铬浸出率达96%以上、钽浸出率小于2%:硫酸浓度343g/L、反应温度80℃、反应时间3h。     

近场移动支付方案研究

随着移动电子商务的发展,金融机构、电信运营商、第三方电子支付企业纷纷进入移动支付领域。目前近距离移动支付有三种主流技术方案：RFID-SIM、SIMPASS、NFC（包括NFC、eNFC和SD方案）,由于移动支付相关标准众多且不一,这已经成为移动支付发展的原因之一。本文通过对近场移动支付主流技术的阐述结合国内典型从业者的技术选择现状的分析,对未来近场移动支付技术路线的演进进行探讨。     

A RF receiver frontend for SC-UWB in a 0.18-μm CMOS process

正A radio frequency(RF) receiver frontend for single-carrier ultra-wideband(SC-UWB) is presented. The front end employs direct-conversion architecture,and consists of a differential low noise amplifier(LNA),a quadrature mixer,and two intermediate frequency(IF) amplifiers.The proposed LNA employs source inductively degenerated topology.First,the expression of input impedance matching bandwidth in terms of gate-source capacitance, resonant frequency and target S_(11) is given.Then,a noise figure optimization strategy under gain and power constraints is proposed,with consideration of the integrated gate inductor,the bond-wire inductance,and its variation.The LNA utilizes two stages with different resonant frequencies to acquire flat gain over the 7.1-8.1 GHz frequency band,and has two gain modes to obtain a higher receiver dynamic range.The mixer uses a double balanced Gilbert structure.The front end is fabricated in a TSMC 0.18-/im RF CMOS process and occupies an area of 1.43 mm~2.In high and low gain modes,the measured maximum conversion gain are 42 dB and 22 dB,input 1 dB compression points are -40 dBm and -20 dBm,and S_(11) is better than -18 dB and -14.5 dB.The 3 dB IF bandwidth is more than 500 MHz.The double sideband noise figure is 4.7 dB in high gain mode.The total power consumption is 65 mW from a 1.8 V supply.     

A multi-mode multi-band RF receiver front-end for a TD-SCDMA/LTE/LTE-advanced in 0.18-μm CMOS process

正A fully integrated multi-mode multi-band directed-conversion radio frequency(RF) receiver front-end for a TD-SCDMA/LTE/LTE-advanced is presented.The front-end employs direct-conversion design,and consists of two differential tunable low noise amplifiers(LNA),a quadrature mixer,and two intermediate frequency(IF) amplifiers.The two independent tunable LNAs are used to cover all the four frequency bands,achieving sufficient low noise and high gain performance with low power consumption.Switched capacitor arrays perform a resonant frequency point calibration for the LNAs.The two LNAs are combined at the driver stage of the mixer,which employs a folded double balanced Gilbert structure,and utilizes PMOS transistors as local oscillator(LO) switches to reduce flicker noise.The front-end has three gain modes to obtain a higher dynamic range.Frequency band selection and mode of configuration is realized by an on-chip serial peripheral interface(SPI) module.The frontend is fabricated in a TSMC 0.18-μm RF CMOS process and occupies an area of 1.3 mm~2.The measured doublesideband (DSB) noise figure is below 3.5 dB and the conversion gain is over 43 dB at all of the frequency bands. The total current consumption is 31 mA from a 1.8-V supply.     

熔盐电解法制备铝-钪合金电解质体系电化学性质研究

熔盐体系的电化学性质对熔盐电解过程有很大影响,通过选用铝电解工业通用的冰晶石-氧化铝体系作为熔盐电解制取铝钪合金的基本电解质体系,采用循环伏安法、线性伏安法和稳态极化法对Sc3+在冰晶石熔盐体系中铝电极上的电化学还原过程及氧化钪在石墨电极上的分解电压进行研究.结果表明,Sc3+在熔盐中电解还原过程为一步获得三个电子的简单电荷传递过程.     

PS版基表面麻坑产生的原因及其预防措施

介绍了铝质PS版基基带材热轧粘铝形成机理;分析了PS版基表面麻坑形成过程及原因;制定并实施了产品质量控制手段和相应的检查方法。PS版基带材的质量及产品率都有较大提高。     

白藜芦醇抗疲劳作用及其机理研究

为了探讨白藜芦醇抗疲劳作用效果及其可能的作用机理,采用力竭训练动物模型,将大鼠分为空白对照组、低剂量白藜芦醇组、中剂量白藜芦醇组、高剂量白藜芦醇组,各组连续灌胃蒸馏水或不同剂量白藜芦醇。灌胃4周后进行力竭跑步实验,测定力竭时间以及血乳酸(blood lactic acid,BLA)、血尿素氮(blood urea nitrogen,BUN)、肝糖原、肌糖原、超氧化物歧化酶(superoxide dismutase,SOD),谷胱甘肽过氧化物酶(glutathione peroxidase,GPx),过氧化氢酶(catalase,CAT)、丙二醛(malondialdehyde,MDA)等疲劳相关生化指标。结果发现,白藜芦醇具有抗疲劳作用,其能延长大鼠力竭跑步时间;降低BLA、BUN、肝组织中MDA含量;增加肝、肌糖原以及肝组织中SOD、GPx、CAT含量。白藜芦醇抗疲劳机理可能是:1)白藜芦醇能降低代谢产物的堆积或快速清除代谢产物;2)白藜芦醇能改善运动代谢控制和能量代谢活化;3)白藜芦醇能提高体内抗氧化酶活性,与内源性抗氧化剂形成协同抗氧化网络来降低氧化应激;4)白藜芦醇能减少自由基引起的脂质过氧化,保护肝细胞膜完整性。白藜芦醇有可能成为一种新的功能性食品或营养补剂应用在运动营养领域。     

基于军队EPC工程总承包项目的BIM技术应用设计

依据军队工程建设相关政策,结合当前军队工程建设实际情况与特点,通过查阅相关研究文献,基于军队EPC项目的组织结构和实施流程,分析BIM技术应用于军队EPC项目的优势.基于BIM技术的特点与内涵,归纳军队EPC工程总承包项目的BIM技术应用点,可为其他EPC项目的BIM技术应用提供参考.