一种简易制导炸弹舵机控制系统

为实时修正制导炸弹弹道轨迹从而精确命中目标,设计一种简易制导炸弹舵机控制系统.该系统硬件部分以dsPIC33EP512MC806为控制核心、以PWM信号驱动用H桥芯片BTS7970B控制直流电机、以外扩A/D采集芯片TLC2374采集经电位器测量的舵面位置反馈信号;软件采用C语言实现5个模块之间的通信.分析结果表明:该系统简化了电路设计的难度,提高了可靠性,满足了制导炸弹的性能要求.     

Synthetic polyurea extreme‐pressure greases

This paper describes the preparation of synthetic polyurea greases and evaluates their performance. The polyurea greases were prepared in situ by reacting diisocyanate with monoamines and ethylene diamine in the presence of a synthetic base oil (polyalphaolefin). Two different extreme‐pressure (EP) additives blended with the prepared polyurea greases were evaluated for their EP activity in four‐ball and Timken tests. The additivated greases gave higher loads, and higher values of weld load in the four‐ball test as compared to the polyurea grease without additive. The blended greases were also found to pass rust, corrosion, oxidative stability, and shear stability tests. The topography of the wear‐scar surfaces was investigated using scanning electron microscopy.     

基于电容模型的脉冲电解、电化学光整、蚀刻加工机理分析

用一个动态变化的电容模型来描述电化学加工过程,从一个全新的角度———电容,来解释电化学加工的机理。利用电极体系的等效阻抗的变化来解释脉冲电解中线性电解液非线性化的现象;通过界面双电层电容值的变化来解释脉冲电化学光整加工提高精度的根本原因;在脉冲电化学蚀刻中由于保护膜产生的类似电解电容效应,使该处的电容值显著变化,从而解决了在纯化学蚀刻中出现的侧向腐蚀问题。     

A tribological study of an S–P–N containing additive in polyalphaolefin

The load‐carrying capacity, antiwear, and friction reduction properties of a novel S—P—N additive (BMDDP) added to a synthetic lubricant, polyalphaolefin (PAO), were evaluated using a four‐ball test machine. The results were compared with those of a commercial S—P—N additive (T307), and show that BMDDP is an excellent extreme pressure and antiwear additive in polyalphaolefin, similar to T307. The rubbed surfaces were investigated using X‐ray photoelectron spectroscopy, and the antiwear mechanism is discussed.     

Simultaneously enhanced impact strength and dielectric properties of an epoxy resin modified with EHTPB liquid rubber

To simultaneously improve the impact strength and dielectric properties of cured epoxy (EP), herein we explore liquid rubber toughened EP based on a nonpolar epoxidized hydroxyl-terminated polybutadiene (EHTPB), where the rubber is covalently bonded to the EP. Fourier transform infrared and nuclear magnetic resonance proved the chemical reaction between EHTPB and EP, which makes the immiscible EHTPB-EP blend change to compatible one. The results indicate that both the impact strength and dielectric properties can be visibly enhanced with the addition of EHTPB and the maximum values are obtained at 10 phr of EHTPB loading. The improved mechanical toughness can be ascribed to the extensive shear yielding induced by the uniformly dispersed EHTPB domains and the enhanced interfacial compatibility between the two components. Moreover, the enhanced electrical resistivity and dielectric breakdown strength as well as the reduced dielectric constant and loss for the EHTPB-EP can be attributed to the combination of the excellent insulating properties of HTPB and dielectrically favorable interfaces. Therefore, the EHTPB-EP with a concurrent improvement in impact strength and dielectric properties can be used as promising insulating materials for high-frequency microelectronics and high-voltage electrical equipment.     

Characterization of three-dimensional multipotent adipose-derived stem cell spheroids

Human adipose stem cells (hADSCs) are reliable sources for cell therapy. However, the clinical applications are limited by the decrease in activity during in vitro culture. We used a knockout serum replacement (KSR) medium, Eppendorf (EP) tube culture, and a simulated microgravity (SMG) culture system to establish hADSC spheroids. We found that hADSCs aggregated and formed spheroids in the KSR culture medium. The EP tube culture method revealed many biological cell characteristics, such as good cell viabilities, rough surfaces, polar growth, fusion phenomenon, and injectability. The findings show its advantages for hADSCs spherical cultures. When cultured in SMG, hADSC spheroids produced large-scale spheroids. Additionally, confocal examination and viability assays revealed that SMG-cultured hADSC spheroids had higher cell viabilities and looser spherical structures, relative to those cultured in EP tubes. hADSC spheroids in static EP tube culture had tighter structures and more dead cells with rough and irregular surfaces, while hADSC spheroids in dynamic SMG condition exhibited looser structures and better cell viabilities with flat and regular surfaces. Therefore, the KSR media promotes spherical formation by hADSCs, which showed polar growth, fusion, and injectability in vitro. The dynamic SMG culture enhances the formation of a looser structure and better cell viabilities for hADSC spheroids.     

汽车用环氧树脂结构胶固化动力学研究

运用非等温DSC(差示扫描量热)法对Sikapower-492G型汽车用EP(环氧树脂)结构胶在动态升温过程中的固化动力学进行了研究。根据不同升温速率时的DSC曲线,采用Kissinger法、Crane法、Ozawa法和温度-升温速率(T-β)外推法等得到该EP胶粘剂的动力学参数。结果表明:该EP胶粘剂体系的固化动力学可用1级固化动力学模型进行表征;该EP胶粘剂的凝胶化温度、固化温度和后处理温度约分别为123、164、224℃,其表观活化能、频率因子和反应级数等动力学参数分别为117 kJ/mol、1.80×1013 s-1和0.934。     

电厂除尘器入口烟道数值模拟及改造

通过数值模拟分析某电厂超超临界4×1 000 MW机组除尘器入口飞灰流量分布不均匀的原因,认为是由于除尘器入口结构不合理所致。为此,提出了相应改进措施:(1)在烟道分配室内安装2片导流板;(2)改造原除尘器入口结构中的3号烟道和2号烟道之间的导流板;(3)在1号烟道入口下方安装导灰板。改造后,灰量分布偏差由19%降为7%,灰量均流效果显著。     

含能聚合物/硝基胍复合含能材料的制备及表征

以含能聚合物(EP)和硝基胍(NQ)为原料,采用溶剂/非溶剂法制备了EP/NQ复合含能材料,采用扫描电镜(SEM)、比表面积测试法(BET)和X射线衍射(XRD)对其形貌和结构进行了表征,用热重-差示扫描量热法(TGDSC)对比分析了EP/NQ复合含能材料及其物理共混物的热性能。结果表明,EP/NQ复合含能材料具有三维纳米网络结构,NQ沉积在EP上面,其平均粒径为49~62nm,NQ的长针状结晶消除;与EP相比,EP/NQ复合含能材料的比表面积降低,且随着NQ质量分数由40%增至60%,EP/NQ复合含能材料的比表面积由54.599m2/g降至25.02m2/g;EP/NQ复合含能材料具有单一的热分解峰特性,热分解峰温比NQ提前55~59℃,且随着NQ质量分数由40%增至60%,EP/NQ复合含能材料的热分解峰温由200.1℃升至203.7℃;EP/NQ复合含能材料的分解热显著高于EP/NQ物理共混物。