新型36/42V汽车系统高功率电池--电池工作者笔记

根据有关文献预计,新型汽车将在2～3 a内形成产业化,推向市场.相应而来需要一种高功率的电池,这种电池将与现行12 V电池产品完全不同.作者根据国外有关文献对众多候选电池进行比较之后,对VRLA、Ni-MH和锂电池等3种主要候选电池进行了较详细的论述,得出了VRLA36/42 V电池将是最良的发展机遇,重点论述了VRLA 36/42 V高功率电池的"标准"、设计参数和推荐方案与制造诸方面.     

稀土改性固体超强酸SO42-/TiO2-MoO3-La2O3催化合成环己酮1,2-丙二醇缩酮

报道了以稀土改性固体超强酸SO42-/TiO2-MoO3-La2O3为多相催化剂,通过环己酮和1,2-丙二醇反应合成了环己酮1,2-丙二醇缩酮,探讨了SO42-/TiO2-MoO3-La2O3对缩酮反应的催化活性,采用正交试验法系统地研究了酮醇量比,催化剂用量,反应时间诸因素对产品收率的影响。实验表明,稀土改性固体超强酸SO42-/TiO2-MoO3-La2O3是合成环己酮1,2-丙二醇缩酮的良好催化剂,在n(环己酮)∶n(1,2-丙二醇)=1∶1.6,催化剂用量为反应物料总质量的0.4%,环己烷为带水剂,反应时间1.0 h的优化条件下,环己酮1,2-丙二醇缩酮的收率可达88.8%。     

固体超强酸催化合成丁酸已酯的研究

针对目前酯化工艺过程中存在的环境污染问题,应用溶胶凝胶法制备了SO42-/TiO2型固体超强酸.利用IR、XRD等分析手段对固体超强酸催化剂进行结构表征,结果表明,该氧化物载体微观结构为锐钛型,并且SO42-/TiO2型固体超强酸在合成丁酸己酯的反应中表现出很强的催化活性及选择性.     

SA-213 T2钢内螺纹管的性能研究

介绍了ASMESA -213T2钢内螺纹管冷拔生产工艺对内螺纹管形状尺寸的影响和不同热处理规范对钢的持久强度的影响。试验结果表明 ,冷拔减壁量与内螺纹高度成正比 ;不同热处理规范对T2钢的持久强度影响不明显     

Target search of burglars: A revised economic model

Abstract. This article investigates home attributes that attract residential burglars in choosing a target. These attributes are the location of the home, its physical appearance, demographic characteristics of the residents, and the security precautions present. The theoretical foundation of the empirical model is the criminal utility maximization behavior that considers costs and benefits as formulated by Becker. However, this article introduces to the model the spatial dimension of the burglar's search for a target. The incidence of burglary is the dependent variable and is measured in a dichotomy scale. The empirical analysis utilizes a survey database of burgled and non-burgled homes that was conducted by the researchers. A logit model is used for the investigation, and the effects of the explanatory variables are calculated as probabilities. The database is unique in the wealth of attributes of individual homes that are relevant to burglars'decision process.     

Microstructural modification and mechanical property improvement in friction stir zone of thixo-molded AE42 Mg alloy

Thixo-molded AE42 Mg alloy was friction stir welded, and the soundness of joints was evaluated, together with the microstructure evolution and mechanical properties in friction stir zones. According to X-ray radiography, the optimum FSW condition range of AE42 alloy exists between AZ61 and AZ31 alloys, and it seems that the optimum welding condition range increases with decreasing Al content in the Mg alloys. There are mainly two kinds of compounds in the thixo-molded AE42 alloy, and FSW has little influence on the grainy Al₁₀RE₂Mn₇ compound, but it has great influence on Al₁₁RE₃ phase, which is changed from lamellar eutectic to small particles after welding. Furthermore, the average diameter of Al₁₁RE₃ particles in SZ decreases with increasing the traveling speed at constant rotation speed due to less heat input. The hardness in SZ is higher than that in BM, and tensile strength and elongation are both improved after welding because the stirring refines and uniforms the microstructure and intermetallic compounds.     

Do vertical tax externalities lead to tax rates being too high? A note

When both vertical and horizontal externalities are at work in a federation, they generally distort levels of taxation in opposite directions. This article is an extension of the Keen and Kotsogiannis (Am Econ Rev March: 363–370, 2002) model. It focuses on state tax policy when states provide an industrial public good increasing firms’ marginal productivity rather than a residential public good intended to households. We find that some results related to whether equilibrium state taxes are likely to be too high or too low are much more complex when state-provided industrial public goods are considered. First, we show that in the presence of industrial public goods, a dominant vertical externality may result in state tax rates being too low (and not too high as it is the case with residential public goods). Second, we find that under certain conditions, horizontal and vertical externalities may point in the same direction and reinforce each other towards tax rates being too high or too low.     

55CrMo钢感应淬火工艺的数值模拟及工艺优化

借助工艺实验和数值模拟技术,优化了55Cr Mo钢精密滚珠丝杠感应加热及冷却工艺参数,改善了丝杠感应淬火后的淬硬层分布。构建了丝杠单感应圈加热的有限元模型,通过数值模拟得到了单感应圈加热时沟道区域的温度曲线。数值模拟结果表明:沟道区域的温度场分布不合理是导致淬硬层分布不合理的主要原因。针对单感应圈感应淬火工艺的不足,提出了双感应圈加热工艺。数值模拟结果表明,采用双感应圈加热工艺、喷水冷却带宽度为40 mm时,可保证丝杠沟道顶部的淬硬层深度约为6.2 mm,沟道底部的淬硬层深度约为3.0 mm。工艺实验结果表明,丝杠沟道区域的淬硬层分布得到较大的改善,数值模拟结果与工艺实验结果吻合得较好。     

镀镍金属化42CrMo钢的微观组织与传感特性研究

采用化学镀镍和电镀镍相结合的方法,对光纤光栅传感器进行保护,然后用钎焊方式将传感器嵌入42Cr Mo钢基体中获得智能金属结构,对其微观组织和传感特性进行研究。结果表明,智能金属结构的灵敏度大大提高,比光纤光栅的灵敏度高1倍。     

β-asarone对Aβ1-42激活的ACM所致PC12细胞损伤的保护作用研究

目的：探讨不同浓度β-淀粉样蛋白（Aβ1-42）激活的星形胶质细胞条件培养液（ACM）对PC12细胞存活率及脑源性神经营养因子（BDNF）、乙酰胆碱酯酶（AChE）蛋白表达的影响,以及β-细辛醚（β-asarone）的保护作用。方法：首先,将对数生长期的PC12细胞随机分为正常对照组、ACM（Aβ1-42 3.3 μmol/L）组、ACM（Aβ1-42 10 μmol/L）组、ACM（Aβ1-42 30 μmol/L）组,分别采用实时无标记动态细胞分析技术（Real Time Cell Analysis, RTCA）和MTT法检测各组PC12细胞的存活率,Western blot检测PC12细胞BDNF、AChE蛋白的表达;其次,将对数生长期的PC12细胞随机分为正常对照组、ACM（Aβ1-42 10 μmol/L）组、β-asarone（18.5、55.5、166.7 μg/mL）组,RTCA法检测PC12细胞存活率的改变,Western blot检测PC12细胞BDNF、AChE蛋白表达的变化。结果：ACM作用24 h,各组PC12细胞存活率无统计学差异（P>0.05）,ACM作用36 h,ACM（Aβ1-42 10 μmol/L）组、ACM（Aβ1-42 30 μmol/L）组PC12细胞存活率显著降低(P<0.01);BDNF、AChE蛋白表达随Aβ1-42 浓度增加显著升高(P<0.05或P<0.01);β-asarone(18.5、55.5、166.7 μg/mL)能显著提高PC12细胞的存活率,β-asarone(55.5、166.7 μg/mL)组AChE表达相比于模型组显著下降(P<0.05或P<0.01),β-asarone(55.5 μg/mL)组与模型组比较BDNF表达增加(P<0.05)。结论：β-asarone能抑制AChE的上调,对BDNF的表达有促进作用,提示β-asarone对神经元细胞有一定的保护作用。