Effect of Iron Coating on Thermal Properties of Aluminum‐Lithium Alloy Powder

Aluminum‐lithium alloys are widely studied to improve performance in energetic materials. However, their high reactivity causes severe surface oxidation over micro‐Al particles in storage, resulting in significant deterioration in the overall performance. This study deals with the effect of iron coating on thermal properties and aging stability of aluminum‐lithium alloy powder. Gas atomized Al‐3Li (3 wt. %) alloy powder was prepared and then successfully coated with nano‐sized iron film by modified chemical liquid deposition method. The morphology, thermal properties and combustion enthalpies were characterized by SEM/EDX, TG/DTA and oxygen bomb calorimeter. The results showed that Fe/Al‐3Li composite powder presented obvious core‐shell structure and the outer iron film was very uniform and compact. Significantly enhanced thermal reactivities of Al‐3Li alloy powder and Fe/Al‐3Li composite powder were achieved compared with pure Al. In addition, aging studies indicated that, after coating, the reactivity decay rates of alloy powder decreased significantly, and the mass combustion enthalpies remained basically stable, which demonstrated that iron coating indeed prevented pre‐oxidation of the alloy powder and improved its aging stability.     

Effects of Age and Hypertension Status on Cognition: The Veterans Affairs Normative Aging Study.

The authors examined the influence of age and hypertensive status (normotensive, controlled, untreated, or uncontrolled) on several cognitive tests via multiple regression in 357 nondemented, community-dwelling older men (mean age = 67 years) whose hypertensive status was stable over 3 years and who had no medical comorbidities. Age was negatively associated with performance on all but 1 test. Age interacted with hypertensive status on verbal fluency and word list immediate recall; older uncontrolled hypertensives exhibited significantly larger age decrements on these tests compared with normotensives. These findings suggest that uncontrolled hypertension produces specific cognitive deficits beyond those attributable to age alone. These and previous findings illustrate that health conditions such as hypertension should be regularly considered in studies of "normal" cognitive aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of a 3-D simulation analysis system for PWR control rod drive mechanism

A 3-D virtual analysis system to analyze the motion of control rod drive mechanism (CRDM) was developed. The analysis system consists of a 3-D model established as per the actual dimensions and interfaces of CRDM parts and a routine to calculate the forces acting on the mechanism, and was verified by mock-up test using the same equipment as the actual product. The analysis system is useful for functional evaluation in maintenance or to factor out root causes in the case of malfunction of CRDM.     

老龄化背景下中国西部丘陵县城镇化特征与趋势研究 ——以四川省岳池县为例

在西部丘陵县劳动人口长期大量外流, 并叠加日益严重的人口老龄化社会背景下,为探究 中国西部丘陵县在老龄化时代下的城镇化新特征 和新趋势,以四川省岳池县为例,基于第七次人口 普查数据,并结合大量的问卷调查和实地调研访 谈数据展开研究。研究发现：一是岳池县虽然城 镇化水平不高,但老龄化乡村已没有富余劳动力, 上阶段支撑城镇化发展的“教育城镇化”和“返乡 置业”因素都已减弱,未来可能进入老人进城养 老为主的城镇化阶段。二是“60后”退休人群、高 龄返乡人群将促使老龄人口继续增长,同时年轻 人流出的现象还将持续,育龄人口大量流出使得 县内新生代儿童的数量趋于下降,人口将进一步走 向“倒金字塔”结构。三是展望到2035年的城镇 化进程,未来县域人口总数将面临收缩,城乡养老 职能将持续显著增强,而劳动力短缺的问题会明 显加剧,尤其是丘区农业人口面临缺少“接班人” 的风险,城乡经济社会发展的基础将深刻变化。 最后,研究建议应加强县级养老服务职能,建设 养老型的城镇和乡村;要重视人力资源积累,培养高素质的城镇、农村的劳动者;应创新规划建设模 式,适应动态集中的城乡居民点格局。研究有助于推动以县城为重要载体的新型城镇化高质量发展和 国家乡村振兴战略建设。     

Configuring retroreflective markings to enhance the night-time conspicuity of road workers

This study investigated whether the night-time conspicuity of road workers can be enhanced by positioning retroreflective strips on the moveable joints in patterns that convey varying degrees of biological motion. Participants were 24 visually normal adults (12 young M = 26.8 years; 12 older M = 72.9 years). Visual acuity, contrast sensitivity and glare sensitivity were recorded for each participant. Experimenters acting as road workers walked in place on a closed road circuit within simulated road work sites, facing either the oncoming driver or the roadway (presenting sideways to the driver) and wearing one of four clothing conditions: (i) standard road worker vest; (ii) standard vest plus thigh-mounted retroreflective strips; (iii) standard vest plus retroreflective strips on ankles and knees; (iv) standard vest plus retroreflective strips positioned on the extremities in a configuration that conveyed biological motion (“biomotion”). As they drove along the closed road participants were instructed to press a button to indicate when they first recognized that a road worker was present. The results demonstrated that regardless of the direction of walking, road workers wearing biomotion clothing were recognized at significantly (p < 0.05) longer distances (3×), relative to the standard vest alone. Response distances were significantly shorter for the older drivers. Contrast sensitivity was a better predictor of the ability to recognize road workers than was visual acuity or glare sensitivity. We conclude that adding retroreflective strips in the biomotion configuration can significantly improve road worker conspicuity regardless of the road worker's orientation and the age of the driver.     

固溶时效处理对TM60合金组织和力学性能的影响

通过对8型钛合金TM60进行不同制度的固溶时效处理,研究了各制度下其显微组织、相结构和力学性能的变化。研究结果表明：α相的含量和体积分数对合金性能有较大影响,固溶处理温度选择在700℃,时效处理温度应选择在400℃~450℃,β型钛合金TM60具有最佳的强塑性。     

Microstructure and shear strength of Sn37Pb/Cu solder joints subjected to isothermal aging

The effects of isothermal aging on the microstructure and shear strength of Sn37Pb/Cu solder joints were investigated. Single-lap shear solder joints of eutectic Sn37Pb solder were aged for 1–10 days at 120 °C and 170 °C, respectively, and then loaded to failure in shear with a constant loading speed of 5 × 10⁻³ mm/s. The growth of the interfacial Cu–Sn intermetallic compounds (IMC) layer (Cu₆Sn₅ + Cu₃Sn) of Sn37Pb/Cu solder joints subjected to isothermal aging exhibited a linear function of the square root of aging time, indicating that the formation of Cu–Sn IMC was mainly controlled by the diffusion mechanism. And the diffusion coefficient (D) values of IMC layer were 1.07 × 10⁻¹⁷ and 3.72 × 10⁻¹⁷ m²/s for aged solder joints at 120 °C and 170 °C, respectively. Shear tests results revealed that as-reflowed solder joint had better shear strength than the aged solder joints and the shear strength of all aged solder joints decreased with increasing aging time. The presence of elongated dimple-like structures on the fracture surfaces of these as-reflowed or aged for short time solder joints were indicative of a ductile failure mode. As aging time further increased, the solder joints fractured in the mixed solder/IMC mode at the solder/IMC interface.     

Martensitic transformation and shape memory properties of Ti-Ta-Sn high temperature shape memory alloys

The effects of Ta and Sn contents on the martensitic transformation temperature, crystal structure and thermal stability of Ti-Ta-Sn alloys are investigated in order to develop novel high temperature shape memory alloys. The martensitic transformation temperature significantly decreases by aging or thermal cycling due to the formation of ω phase in the Ti-Ta binary alloys. The addition of Sn is effective for suppressing the formation of ω phase and improves stability of shape memory effect during thermal cycling. The amount of Sn content necessary for suppressing aging effect increases with decreasing Ta content. High martensitic transformation temperature with good thermal stability can be achieved by adjustment of the Ta and Sn contents. Furthermore, the addition of Sn as a substitute of Ta with keeping the transformation temperature same increases the transformation strain in the Ti-Ta-Sn alloys. A Ti-20Ta-3.5Sn alloy reveals stable shape memory effect with a martensitic transformation start temperature about 440 K and a larger recovery strain when compared with a Ti-Ta binary alloy showing similar martensitic transformation temperature.     

Roadwise Review has limited congruence with actual driving performance of aging drivers

The Roadwise Review (RR) CD-ROM has been proposed as one way for older drivers to self-evaluate the skills that support safe driving. To better gauge the utility of RR for that purpose, further validation of RR vis-à-vis measures of driving performance is needed. We carried out this study to provide such validation. We correlated the results of the standard Useful Field of View subtest 2 (UFOV-2) and Trail Making Test (TMT) parts A and B to the corresponding RR subsections on visual information processing and visual search. We further examined the correlations between on-road performance (based on demerit points) and RR results (absolute scores and number of problems identified). The correlations between UFOV-2, TMT and the relevant RR sections ranged from .46 to .61. The correlations between demerit points and RR absolute values ranged from −.40 to .50. The correlations between demerit points and the number of problems identified by RR ranged from −.24 to .45. Using a “pass/fail” approach we also failed to find a relationship with the number of problems. These results indicate limited convergence between findings obtained with RR and actual performance using standardized approaches. Such results emphasize the importance of developing a rigorous data synthesis process before attempting knowledge translation of material aimed at older drivers.     

苹果营养醋的生产工艺研究

为研究苹果汁的最适发酵工艺条件及醋酸发酵过程中总酸和总酯的变化,选择糖度分别为8、10、12和15°Bx的苹果汁进行酒精发酵,对发酵产品的气味和酒精含量进行测定,并以影响醋酸发酵过程的重要因素——接种量、发酵温度、发酵时间做三因素三水平正交试验,测定了醋酸发酵过程中的总酸及总酯的变化。结果表明:采用糖度为12°Bx的苹果汁进行酒精发酵,酒精含量高,风味好,成本低;最佳发酵条件是醋酸菌接种量10%,发酵温度32～34℃,发酵时间72h,发酵后采用1～2个月陈酿,所得产品的有机酸含量高,风味好。苹果汁酒精发酵和醋酸发酵采用适宜的糖度、发酵条件与陈酿工艺,产品的总酸含量较高,风味较好。