异辛酸钴的制备和应用

采用硫酸钴沉淀法制备异辛酸钴,并在水相与有机相的分离过程中添加助剂的方法,可使分离后有机相不经水洗即可彻底除去SO_4~(2-)离子,简化了工艺流程。介绍了异辛酸钴催干剂在4种醇酸磁漆中的应用及其性能检测结果。检测结果表明,异辛酸钴用于醇酸磁漆的性能指标达到或超过规定标准,尤其光泽、硬度两项指标优于同类产品水平,町作为环烷酸钴等常用催干剂的更新换代产品。     

太阳能溴化锂吸收式制冷系统吸收特性的研究

太阳能溴化锂吸收式制冷系统的吸收器采用传热、传质分离装置,利用预冷器预先冷却和喷淋吸收的方法完成对传热、传质的分离。通过建立吸收器的计算模型,分析冷冻水出口温度、冷却水进口温度、热水温度、喷淋温度、喷淋密度等因素对传热、传质的影响。利用传热、传质分离方法,使系统的吸收特性得到强化,从而使系统获得较高的性能系数。     

Recent developments of cement chemistry in China: Invited review paper

In recent years, much work has been done by the cement chemists in China centering on energy saving in cement and concrete making and improving the properties of both.     

An SVD-based adaptive robust speech steganography using MDCT coefficient

Multimedia Tools and Applications - Speech is one of the essential ways of communication. The study of speech steganography provides great value in information security. To improve imperceptibility...     

A Sequential Design Approach for Switching ℌ∞ LPV Control

This paper proposes a sequential design scheme for switching ℌ_∞ LPV (Linear Parameter-Varying) control, aiming to reduce the computational complexity of the associated optimization problem. Different from the traditional approach that simultaneously designs switching LPV controllers and solves a high-dimensional optimization problem, the proposed sequential design approach renders a bundle of low-dimensional optimization problems to be solved iteratively. Individual ℌ_∞ LPV controller for each subregion is synthesized by independent PLMIs (Parametric Linear Matrix Inequalities) to guarantee ℌ_∞ performance, and controller variables are interpolated on the overlapped subregions such that the ℌ_∞ performance is also guaranteed on the overlapped subregion. Numerical examples are used to demonstrate the effectiveness of this method to reduce the computational load in each design iteration and improved ℌ_∞ performance over the conventional simultaneous design method with well-tuned interpolation coefficient.

     

损伤变量对复合材料损伤演化过程的影响分析

复合材料层合板损伤模型中的刚度退化需要通过损伤变量来实现。针对通常采用的2种损伤变量定义,给出了统一表达式。此外,损伤刚度矩阵是损伤变量的函数,基于应变等效假设推导了三维损伤刚度矩阵,从而避免了对损伤刚度矩阵的人为假定。最后,通过复合材料层合板在冲击载荷作用下的数值模拟,讨论了损伤变量的2种定义对数值结果的影响,表明损伤变量的不同定义对分层和基体损伤分布存在一定的影响,对冲击载荷的影响不大。建议在复合材料损伤模拟中,应予关注损伤变量。     

强油非导向变压器热特性分析及优化设计

本文中作者借助流体软件对强油非导向变压器进行了热特性分析,并对变压器内部散热油路及冷却器进行了优化设计.     

On the mechanical performance of closed cell Al alloy foams

The mechanical properties of three different commercially available closed cell Al alloys all made by foam casting are examined. The objective is to assess the roles of cell morphology and of imperfections in governing the basic properties: stiffness, yield strength and fracture resistance. This assessment provides goals for manufacturing strategies that enable attainment of good mechanical performance with affordable process technologies. A prevalent role of curves and wiggles in the cell walls on stiffness and strength (anticipated by models) is affirmed by the present measurements. Systematically larger stiffnesses and yield strengths found in tension than in compression are consistent with a prominent role exerted by such imperfections. Moreover, foam casting is apparently capable of cell morphologies that impart properties approaching the best achievable values for an isotropic closed cell solid, devoid of imperfections. There are associated implications for performance and affordability. Fracture measurements indicate crack growth occurring along the cell walls by a mechanism analogous to the plastic tearing of thin sheets. The crack growth resistances are in the range of 1 kJm⁻². This mechanism infers a toughness that scales with the cell wall thickness and its yield strength.     

Preparation and characterization of GaN films grown on Ga-diffused Si （111） substrates

Hexagonal GaN films were prepared by nitriding Ga2O3 films with flowing ammonia. Ga2O3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.) magnetron sputtering. This paper have investigated the change of structural properties of GaN films nitrided in NH3 atmosphere at the temperatures of 850, 900, and 950℃ for 15 min and nitrided at the temperature of 900℃ for 10, 15, and 20 rain, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the structure, surface morphology and composition of synthesized samples. The results reveal that the as-grown films are polycrystalline GaN with hexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained when nitrided at 900℃ for 15 min.     

探索中国民营企业经营模式创新之路——岷山公司推行模拟法人经营体制

中国民营企业经营现状据第一部《中国民营企业发展报告》蓝皮书统计，中国300多万家私营企业90％以上是家族企业，既有单一业主制的企业，也有合伙制的企业、共有制的企业，甚至还出现了家族成员保持临界控制权的企业集团。