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The reactant pressure of the fuel cell stack is crucial to the efficiency and lifespan of high pressure fuel cell engine. Plenty of researches have done to achieve precisely pressure control, and taking electronic throttle (ET) as back-pressure valve to control pressure is one of the most ideal techniques. In this paper, a detailed nonlinear dynamic model of back-pressure valve is provided firstly. Then, several algorithms are designed to estimate the unknown parameters in the model. Finally, the previous model and identified parameters are verified based on the xPC Target technique. The simulations show that the model and identified parameters provided in this paper have certain reliability and are important to the development of high-performance fuel cell engine controller.

For modern management and full resource sharing among libraries and scientific departments both in Chinese and worldwide observatories, we established the computer system of library management and information retrieval during the period 1984-1987.The system is composed of ten component sub-systems: 1.Book ordering system. This system can produce orders for books and periodicals, balance accounts, produce statistics as well as claims for outstanding book orders.2.Book cataloguing system. This system can catalogue books under certain rules while appending new records of books to the databases. It can also produce catalogue cards and produce written reports about the new books.3.Book retrieval system has the ability to search for a specific book in several ways.4.Book lending or circulation system. This system is a complete circulation system; including book lending, renewals, waiting lists, and recall of borrowed books.5.Periodical management system. This system is in charge of processing of periodicals and magazines in the library, including cataloguing, management, and lending.6.Scientific information retrieval system. One can retrieve scientific information by keywords or in many other ways.7.Internal material booking system. It can make orders of internal materials, claims for materials outstanding and make exchanges with other observatories and institutions both in or outside the country.8.Internal material management system. It can do the work that is analogous to that done with books and periodicals.9.Information relationship system. It handles exchanges of information between institutions. Computer system of library management ... at Shaanxl 18310.Scientific information network management system. It manages affairs within a certain information network.