Use of Hydrazine and Its Substitutes as Fuel

Due to the properties and high reactivity of hydrazine,it is mainly used as rocket fuel not only in its pure form but also in combination with 1,1-dimethylhydrazine and oxidizers(nitrogen tetroxide or nitric acid)forming a self-igniting mixture with oxidizers.Aerozine 50 and UH 25(a mixture of 75%UDMH(unsymmetrical dimethylhydrazine)and 25%hydrazine hydrate)are the best-known hydrazine mixtures with different hydrazine concentrations.The review addresses the use of hydrazine and its derivatives as fuel.Hydrazine is employed in fuel cells(with air oxygen as an oxidizer)to generate electrochemical energy for transport vehicles.Hydrazine is widely used as monopropellant to design low-thrust rocket engines for orientation and stabilization systems in space vehicles,as well as in energy units.The review also addresses such hydrazine derivatives as methylhydrazine,1,1-dimethylhydrazine,hydrazine monoperchlorate,hydrazine diperchlorate,hydrazine diammonium tetraperchlorate,hydrazine mononitrate,hydrazine dinitrate,hydrazine nitroformate,hydrazine azides,tetrafluorohydrazine,etc.as well as composite propellants,and gel rocket propellants based on hydrazine.The materials in the review can be used as reference information on hydrazine fuels.

Application of modern timber structure in short and medium span bridges in China

A series of problems about Chinese bridges with short and medium span recent years were analyzed in this paper. The necessity and feasibility of modern timber structure applied in short and medium span bridges in China were also put forward. The results showed that the short and medium span bridges had many problems, such as monotonous structural forms, seri- ous environmental pollution, multiple bridge defects and difficulty in maintenance. With the development of connection and maintenance technology of modern timber structure and its ad- vantages of light self-weight, environmental coordination, high carrying capacity, excellent durability and abundant structural forms, it was necessary and feasible to apply modern timber structure in short and medium span bridges in China. More emphasis on the construction of modern timber structure should be conducted to expand its application scopes and improve the construction proportion of short and medium span timber bridges.

BREAKING THE MONOLITH： STRATEGY, VARIETY, AND PERFORMANCE OF ENTERPRISE INFORMATION SYSTEMS

This paper intends to understand the form of implementations of Enterprise Information Systems （EISs）. EISs are usually provided as packaged software products. Due to the diversities of implementations, EISs are often characterized by their system architectures. A conceptual framework is proposed to delineate the diversity and dynamics of EIS implementations. This framework is constituted of three components, EIS strategy, variety, and process-level performance （SVP）. In particular, the variety of implementations is defined by two constructs, application scope and application depth. A Partial Least Squares structural equation modeling approach is applied to test the hypotheses according to the survey data from 223 project reports of EIS implementations in China. The results show that the EIS strategy and variety can both affect the performance of the implemented EISs. Specifically, application depth has an important mediating effect on the relationship between EIS strategy and performance. EIS strategy and application depth are breakthrough points to improve the performance of the implemented EISs. These findings suggest that the variety plays a central and effective role in the analysis of EIS implementations. This SVP framework highlights the interconnections among its components and captures the form of EIS implementations.