构建中国海外投资促进体系研究综述

基于经典海外投资理论、发达国家促进海外投资的经验,分析了海外投资的宏观环境,包括海外投资发展阶段分析、环境分析和影响因素分析,并从政府和企业的角度阐述了两者在促进海外投资中的作用,最后结合目前实际,分析了金融危机背景下我国企业的应对策略。     

无人机地面站飞行监控系统软件设计

介绍了飞行监控系统软件的组成、设计原理和工作流程,以及采用的关键技术,并说明了系统在联试过程中出现的问题和处理方法;飞行试验结果表明,本系统能够实时显示无人机的飞行姿态、飞行轨迹、位置及参数,实现任务航线的编辑、装订与显示,发送飞行控制指令,实时性高,操作方便,连续工作48小时无异常。     

Effects of NCO/OH molar ratio on miscibility and properties of semiinterpenetrating polymer networks from polyurethane and benzyl konjac glucomannan

Semi‐interpenetrating polymer network (semi‐IPN) films with different NCO/OH molar ratios of the urethane prepolymer, coded as UB, were prepared from polyurethane (PU) and benzyl konjac glucomannan (B‐KGM) by a casting method. The effect of the NCO/OH molar ratio of the urethane prepolymer on the miscibility and properties of the UB films was investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, thermogravimetric analysis, and swelling and tensile tests. The results indicated that, with an increase of the NCO/OH ratio, the crosslink density of the UB films increased, resulting in improved miscibility between PU and B‐KGM and a relatively high light transmittance of the UB films. However, the thermal stability of the UB films decreased with increase of the NCO/OH ratio of the urethane prepolymer, due to the depolymerization of the urethane bonds of the PU networks. When the NCO/OH ratio increased from 2 to 4, the tensile strength of the UB films increased from 15 to 27 MPa, while the breaking elongation decreased from 72 to 16%, resulting from the chemical and physical crosslinks, namely, the enhancement of the covalent bonds and hydrogen‐bonding networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1304–1310, 2003     

面板堆石坝面板顺坡向挤压破坏机理的试验研究

本文针对面板堆石坝面板顺坡向挤压破坏的钢筋压曲凸起问题开展了试验研究,采用了配有单根立筋的混凝土柱受压试验来模拟面板顺坡向的挤压破坏。试验结果证实了以往研究中无箍筋钢筋混凝土立柱抗压强度低于素混凝土柱、且钢筋保护层厚度越小强度越低的推测。与素混凝土柱相比,保护层厚5 cm钢筋混凝土柱的强度降低约10％。根据试验的破坏荷载结果,通过已有理论解反推出了立柱的侧向支撑刚度k,对于保护层厚5 cm和8 cm立柱k值相应为0.841 N·mm^-2和1.032 N·mm^-2。经过试验结果分析,发现钢筋混凝土立柱各截面不服从应变平面假设,受压中钢筋没有同混凝土一起协调变形,钢筋与混凝土之间相互作用强烈。本研究结果再次说明,限制钢筋的侧向变形是防止面板顺坡向挤压破坏的根本措施。应开展可模拟混凝土中钢筋压曲的挤压破坏数值模拟研究,为这些措施的量化设计提供依据。     

云计算环境基于客体属性匹配的逆向混合访问控制方案

云计算提高了大数据的使用、分析和管理的效率,但也给数据贡献者带来了对云服务的数据安全及隐私信息泄露的担忧。针对这个问题,结合了基于角色的访问控制、基于属性的访问控制方法并采用了下一代访问控制的体系结构,提出了云计算环境下的基于客体属性匹配的逆向混合访问控制方法。首先,数据贡献者设置共享文件访问权限级别,逆向规定了访问客体的最低权值;然后,采用变异系数加权的方法直接计算各属性的权值,取消了以属性为中心的基于角色的访问控制中策略规则匹配的过程;最后,把数据贡献者对数据文件设定的权限值定为数据访问者被允许访问的阈值,这样既实现了数据访问控制,又保障了对隐私数据的保护。实验结果表明,随着访问次数的增多,所提方法对恶意行为、权限不足行为等的判断基准趋于稳定,检测能力越来越强,成功率趋于一个较为平稳的水平。该方法在用户访问数量较大的环境下相较传统的访问控制方法能够实现更高的决策效率,验证了所提方法的有效性和可行性。     

不确定单机无穷大系统的预测变结构控制

将不确定单机无穷大系统的非线性三阶模型转换成二阶模型,以便在相平面中直观地设计变结构控制律。使用系统不确定参数的上下限来设计控制律,以获得良好的鲁棒性。通过预测相轨线的走势确定控制切换时机,保证了系统轨迹以指数速率收敛到平衡点。由于控制律的切换不是连续的,因此避免了传统变结构控制中的抖振。在仿真时,系统的初始状态较大地偏离了平衡点,在仿真过程中,机械功率遭受了30%的临时干扰,仿真结果表明,系统轨迹能够快速地回到原来的平衡点,控制律具有很好的鲁棒性。     

我国铝业生产的物质流分析——基于2010年我国铝行业的数据

本文基于2010年我国铝行业的数据,应用质量守恒定律及输入-输出模型,对我国铝业生产的物质流进行了分析,通过废品率、单元金属收得率、资源效率等指标的测算与比较,总结我国铝业生产取得的成绩,发现我国铝业生产中所存在的差距与问题,提出改善生产、消费与进出口结构,减少铝损耗量,提高我国铝业生产资源利用效率的建议.     

完善培训机制 塑造培训品牌

通过分析新员工的培训需求,可以树立正确的培训目标,从而有利于采用合适的培训方法,制定完善的培训机制。作为新入职的员工,最渴望就是要了解公司的现状,公司未来的发展．自己在公司有哪些机会,需要付出什么,又将得到什么？因此新员工培训的目的主要是使他们能了解企业,尽快融入企业,胜任工作,产生绩效,即加速实现个人和企业的协同发展,同时塑造培训品牌。     

Thermal stability and performance of optimized ZrCx diffusion barriers in ceramic coating systems for ATF applications

Surface-modified Zr alloy claddings with advanced ceramic coatings are promising materials for accident-tolerant fuel (ATF) systems to meet stringent safety regulations concerning light water reactors. The applications of ceramic coatings are, however, limited as a result of inferior thermal stability when used in conjunction with Zircaloy-4 (Zry-4) substrates. Herein, the thermal stability of sub-stoichiometric zirconium carbide barrier layers as a function of composition was studied. Integrated ceramic coatings comprising ZrC_0.55 diffusion barriers and a Cr₂AlC top layer were synthesized via a magnetron sputtering method. After rapid thermal annealing, the ZrC_0.55 barrier layer having a thickness of 0.5 μm effectively prevented the inter-diffusion between Cr₂AlC and the Zry-4 substrate, thereby ensuring retention of the structural integrity of the integrated ceramic coating system for ATF applications.     

Ionic liquid modified graphene oxide for enhanced flame retardancy and mechanical properties of epoxy resin

In this work, to improve its dispersion and flame retardancy, graphene oxide (GO) was functionalized by silane coupling agent KH550 and 1-butyl-3-methylimidazole hexafluorophosphate (PF₆-ILs), and characteristics of the PF₆-ILs@GO was obtained by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Then, the synergistic flame retardant of GO or PF₆-ILs@GO and melamine pyrophosphate (MPP) were applied for epoxy resin (EP) materials. Specifically, the limiting oxygen index (LOI) value of EP with 0.1 wt% PF₆-ILs@GO was increased to 29.2% from 27.5% of EP/MPP composites, and the UL-94 test reached the V-0 rating. The CCT results showed that the total heat release (THR) and total smoke release (TSP) of EP/MPP/PF₆-ILs@GO composites were significantly 24.4% and 53.4% lower than that of EP/MPP composites. Besides, the thermal behavior investigated by TGA indicated that the char-forming effect of GO and PF₆-ILs@GO was great, the residual char of EP/MPP/PF₆-ILs@GO composites was as high as 19.5% at 700°C, and its thermal stability was higher than that of EP/MPP composites. On the other hand, the tensile strength of EP/MPP/GO and EP/MPP/PF₆-ILs@GO composites were increased by 15.6% and 28.3% compared with EP/MPP composites. According to SEM analysis, the EP/MPP/GO composites formed a good protective char layer, which can effectively improve flame retardancy of EP. This research represents a new method of flame retardant modified GO to improve the flame retardancy and mechanical properties of polymers.