基于多目标优化策略的结构可靠性稳健设计

应用可靠性稳健优化设计理论和多目标决策方法,将结构可靠性稳健优化设计转化为多目标优化问题。运用灰色理论中的关联分析法,选取粒子群算法中的全局极值和个体极值,提出了灰色粒子群算法求解可靠性稳健优化设计问题。与传统方法相比,该方法简便易行并能迅速准确地得到结构可靠性稳健优化设计信息。     

陕北地区黄土节理对公路边坡稳定性的影响

黄土节理主要分为原生节理、构造节理、风化节理和卸荷节理。陕北地区主要发育原生节理和构造节理,原生节理多分布在马兰黄土中,较密集,延伸长;构造节理多分布在离石黄土中,方向性强,区域性强。节理对边坡稳定性的影响因产状不同而不同。与边坡走向一致的顺坡斜节理对边坡稳定性影响较大,垂直节理影响较小;走向与边坡走向垂直和斜交的节理对边坡稳定性影响较小。多组节理在平面内可组成层面棋盘格式和“X”格式;在空间内可组成板状结构体、楔椎状结构体和柱状结构体。不同形状的结构体对边坡产生不同影响。最后,针对对边坡稳定性影响最大的斜节理,讨论了沿构造(斜)节理面产生边坡土体滑落的可能性的核算方法。     

Versatile protonic acid mediated preparation of partially deacetylated chitin nanofibers/nanowhiskers and their assembling of nano-structured hydro- and aero-gels

The partially deacetylated α-chitin nanofiber/nanowhisker (DEChN) aqueous dispersions were prepared by alkali deacetylation. The following mechanical treatment under acidic conditions was mediated by five different organic protonic acids, including acetic acid, gluconic acid, itaconic acid, citric acid and ascorbic acid. Thereafter, these acidic DEChN dispersions were transformed into hydrogels under an alkali gas phase coagulation bath. After solvent exchange and freeze drying, the DEChN-based aerogels were prepared. Previous research showed that the kinds of acid used for the adjustment of the pH value during the fibrillation process influenced the nanofibrillation efficiency. In this study, it was discovered that the types of protonic acid also influenced the properties of the DEChN hydrogels and aerogels under the same mass concentration (0.6%) of DEChNs, including the appearance, strength of hydrogels, the pore size and specific surface area of aerogels, as well. Nevertheless, all of the hydrogels showed good mechanical strength and all of the aerogels possessed a porous nanostructure sustained by nanofibrillar networks. The highly porous chitin aerogels showed a broad size mainly distribution from 2 to 100 nm, and the specific surface area of chitin aerogels ranged from 90 to 170 m²g^?1. Although it was not clear how the types of protonic acids influenced the properties of the hydrogel and aerogel, we were able to obtain DEChN dispersions and gels by mechanical treatment of partially deacetylated chitin at acidic conditions mediated by versatile acids. In the meantime, the observed differences among the gels provided the possibility to use the acid medium to select the gels with certain mechanical strength, porosity or specific surface area for the prospective desired applications.     

Small sample statistical condition estimation for the total least squares problem

In this paper, under the genericity condition, we study the condition estimation of the total least squares (TLS) problem based on small sample condition estimation (SCE), which can be incorporated into the direct solver for the TLS problem via the singular value decomposition (SVD) of the augmented matrix [A, b]. Our proposed condition estimation algorithms are efficient for the small and medium size TLS problem because they utilize the computed SVD of [A, b] during the numerical solution to the TLS problem. Numerical examples illustrate the reliability of the algorithms. Both normwise and componentwise perturbations are considered. Moreover, structured condition estimations are investigated for the structured TLS problem.     

Thermal transition and decomposition properties of pH- and phosphate-induced defatted soybean meals

Defatted soybean meal is a popular raw material for soybean protein products. Thermal properties of soybean meal, which is vital for its application in extruded texturized soybean protein, are influenced by storage time and processing temperature. Thus, low-temperature defatted soybean meal (LSM), low-temperature defatted one-year-stored-soybean meal (LSSM) and high-temperature defatted soybean meal (HSM) were selected to investigate the thermal transition and decomposition properties by pH induction with phosphate using differential scanning calorimetry and thermal gravimetric analysis. The results showed that the peak temperature of 11S (glycinin) in phosphate buffer at pH 7 is significantly higher than that in deionized water. Break temperatures of LSM and LSSM at around 110 °C in deionized water are significantly higher than that in phosphate buffer at pH 7; however, the break temperature of LSM at 300 °C in deionized water is significantly lower than that in phosphate buffer at pH 7. In contrast to LSM, ?H of LSSM in phosphate buffer at pH 7 is significantly lower than in deionized water. It is thus concluded that phosphate stabilizes the soybean protein quaternary structure, enhances protein–protein interactions and weakens protein-water interactions. Protein association occurs in LSSM during soybean storage, while HSM protein appears to be insensitive to these changes.     

磨粒磨损中磨粒几何外形参数的分析方法

根据Ｆｏｕｒｉｅｒ级数的频域分析方法，并且运用快速Ｆｏｕｒｉｅｒ变换的算法，在ＩＢＭ－ＰＣ机上通过自编程序进行了不同磨粒几何外形参数的数值计算，利用这种计算方法，可以获得磨粒尖锐度、粗糙度和轮廓的角形特征等信息，是对不同磨粒外部几何形状进行比较判别的一种有效方法。     

EXISTENCE AND STABILITY OF STANDING WAVES FOR A COUPLED NONLINEAR SCHRDINGER SYSTEM

We study the existence and stability of the standing waves of two coupled Schrdinger equations with potentials |x|bi(bi ∈ R, i = 1, 2). Under suitable conditions on the growth of the nonlinear terms, we first establish the existence of standing waves of the Schrdinger system by solving a L2-normalized minimization problem, then prove that the set of all minimizers of this minimization problem is stable. Finally, we obtain the least energy solutions by the Nehari method and prove that the orbit sets of these least energy solutions are unstable, which generalizes the results of [11] where b1= b2= 2.     

Efficient Copper-Catalyzed Double S-Arylation of Aryl Halides with Sodium Sulfide in Peg-400

Abstract

An efficient copper-catalyzed double S-arylation of sodium sulfide with aryl halides in PEG-400 has been developed. With CuI as a catalyst and PEG-400 as a solvent, a range of electron-withdrawing or electron-donating aryl iodides and aryl bromides were found to be applicable to the environmentally benign system. The present procedure is mild and tolerant of a variety of functional groups and the steric hindrance of ortho-substituents on aryl halides did not affect the outcome of good to excellent yields.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

A fast render algorithm of virtual and real motion blur consistence in augmented reality

Motion is a common phenomenon in the real world so the consistence of virtual and real motion is one of hot focuses in augmented reality system. This paper mainly analyzes virtual and real motion blur consistence in augmented reality system, and mainly do improvement in two aspects, one is how to get the motion blur parameters, the other is how to render motion blur. From the available literature it can be seen that, most achieved methods to get motion blur parameters are based on machine vision. But this paper first acquires the motion trajectory by magnetic tracking, and then gets motion blur parameters. Considering the available literature on motion blur rendering methods, they mainly contain convolution and accumulator caching and so on. Due to rotation translation compound motion blur, this paper does rendering in advance based on improved mathematical model, and then render virtual object through looking up table in augmented reality system. Experimental results show that the new virtual and real motion blur consistence render algorithm has low time complexity and achieve the desired effect in simulation environment and real scenes.