An analytic solution for a fault tree with circular logics in which the systems are linearly interrelated

A circular logic or a logical loop is defined as the infinite circulation of supporting relations due to their mutual dependencies among the systems in the fault tree analysis. While many methods to break the circular logic have been developed and used in the fault tree quantification codes, the general solution for a circular logic is not generally known as yet. This paper presents an analytic solution for circular logics in which the systems are linearly interrelated with each other. To formulate the analytic solution, the relations among systems in the fault tree structure are described by the Boolean equations. The solution is, then, obtained from the successive substitutions of the Boolean equations, which is equivalent to the attaching processes of interrelated system's fault tree to a given fault tree. The solution for three interrelated systems and their independent fault tree structures are given as an example.     

Corrosion and stress corrosion cracking behavior of equal channel angular pressed oxygen-free copper in 3.5% NaCl solution

In the present study, the corrosion and stress corrosion cracking (SCC) behavior of equal channel angular pressed (ECAPed) oxygen-free copper was examined in 3.5% NaCl solution. The specimen with two ECAP process cycles was found to have the greatest resistance to corrosion and SCC in 3.5% NaCl solution among the specimens studied, while the resistance varied in a complex manner with different number of ECAP process cycles. Micrographic observation and differential scanning calorimeter study suggested that both corrosion and SCC behavior of ECAPed copper was strongly dependent on the microstructural evolution, including the change in grain size and dislocation density, during ECAP process.     

Innovation and production in the global solar photovoltaic industry

The global development of solar photovoltaic power is seen as a potentially major technology in the pursuit of alternative energy sources. Given its evolutionary nature, in terms of both technology and the market, there is some discernible divergence between the innovative capability and production capacity of certain countries. We set out in the present study to explore this issue by examining the productive and innovative performance of six countries covering the period from 1996 to 2006. Our empirical analyses, at both country level and firm level, provide a strong indication that such tendency of incongruence possibly comes as a result of differences in the business strategies adopted by the various countries, as well as the extent of their technological advantage.     

Bondline strength evaluation of cocure/precured honeycomb sandwich structures under aircraft hygro and repair environments

Effects of moisture accumulated into the adhesively bonded composite structures on their bondline mechanical strengths are investigated through a series of comparative experiments. Those composite structures include a honeycomb sandwich structures fabricated by the cocure and the precure processes. Mass of moisture accumulated into the closed cells of the honeycomb sandwich panel specimens has been calculated. A pressure due to the vapor expansion in each cell of the sandwich panel has also been obtained for the minimum repair pressure to be applied to the laminate patched area by vapor pressure–temperature relations from the thermodynamic steam table, the ideal gas state equation and two vapor pressure equations. The bondline strengths of the laminated skins on the flat surface of honeycomb have been compared by the flatwise tension test and climbing drum peel test for dry, wet and repair-after-wet specimens, respectively.     

实时GPS定位中的自适应故障检测

给出了一种GPS卡尔曼滤波的自适应方案,该方案能根据GPS导航中变化的动态来估计协方差.当增强卡尔曼滤波器时,方案可得到更精确的定位修正.此外,也可将此估计方法用于完整监测,以增强故障检测的阈值选择.采用模拟数据验证了提出方法的正确性.     

含硅光学用增透聚酯薄膜的制备与研究

通过自由基聚合将γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)分别与甲基丙烯酸甲酯MMA、甲基丙烯酸丁酯BMA、苯乙烯St进行共聚。采用旋涂法将所得聚合物涂覆于聚对苯二甲酸乙二醇酯(PET)薄膜表面。研究不同含量的硅烷偶联剂、引发剂、不同种类单体对PET薄膜表面性能的影响。数据表明,相比于PET薄膜,涂覆有共聚物的PET薄膜性能有较大变化,透光率有一定程度增大,表面自由能有所减小。     

Structural control over self-assembled crystals of pi--conjugated poly(3,3'-didodecyl-quaterthiophene) for organic field-effect transistor applications

Liquid-crystalline (LC) poly(3,3'-didodecyl-quaterthiophene) (PQT-12) was investigated to optimize its side alkyl ordering and pi-conjugated structure for high performance organic field-effect transistor (OFET) applications. Initially, low-crystal films spun-cast on OTS-treated SiO2 substrates were further crystallized via either thermal or solvent treatments. At temperatures (125-138 degrees C) driving a LC state of PQT-12, mobile chains were better migrated into preformed crystals. The resulting films showed highly crystal nanofibrils, in which pi-conjugated polymer backbones (with an conjugated backbone spacing, d(010) of 3.80 A) and the orientation of self-assembled side-chains were tilted with respect to the film surface, respectively. However, via melting or solvent exposure providing isotropic states, film crystallization generated less ordered crystals with randomly oriented side-chains, increasing d(010) up to 4.16 A. As a result, the usage of LC characteristic allowed us to consistently achieve the desirable crystal structure of PQT-12 and to robustly obtain high field-effect mobility for FET applications.