Properties analysis of a large flow-rate safety valve test device

In order to solve the problem of property test of large flow-rate safety, the property parameter of safety valve test system was analyzed, and a device for property oflarge flow-rate safety valve test was designed.The device used accumulators as power source and a united function cylinder, which can realized the large flow-rate output for the test system.Analyzed the test data and made a particular research on the test device by testing different flow-rate safety valves;it verifies that the test device can be used tode-sign larger flow-rate safety valve test system and can make the flow-rate test and analysis and dynamic characteristics for the large-flow safety valve.

STRONG LAW OF LARGE NUMBERS AND GROWTH RATE FOR NOD SEQUENCES

In the paper,we get the precise results of Hájek-Rényi type inequalities for the partial sums of negatively orthant dependent sequences,which improve the results of Theorem 3.1and Corollary 3.2 in Kim(2006)and the strong law of large numbers and strong growth rate for negatively orthant dependent sequences.

DYNAMIC CHARACTERISTICS OF LARGE FLOW RATING ELECTROHYDRAULIC PROPORTIONAL CARTRIDGE VALVE

A kind of cartridge servo proportional valve is discussed, which can be used for controlling large flow rate with high performance. By analyzing the structure principle of the valve, the transfer fimction of the valve is derived. With the transfer function, some structure elements that may affect its performance are investigated. Through the numerical simulation and test study, some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The test results conform to the results of the theoretical analysis and simulation, which proves the correctness of the study and simulation works. The paper provides theoretical basis for engineering applications and series expanding design works

Research on Effective Access for Strengthening and Improving the Management and Benefit use of Large Instruments

The purchasement and development as well as the benefit of utilization for the large equipment in universities of China are analyzed in this paper, the paper in dicates that in utilization of large equipment the contradictions such as urgency and necessity for the purchasement and development of large equipment and serious waste in resources since inadequacy of annual utilization rate of large equipment are existed, it also raises that the key step of giving full play to the benefit of large equipment is to strengthen management and development after the equipment are purchased, the paper regards through stressing standardized management and maintenance、opening the laboratory、improving the functions of equipment、renovating technology、fully examining and scientifically deciding before purchasement, the investment benefit for the large equipment can be raised effectively.

On Evaluating the Rate Function of Large Deviations for Jump Processes

This is a sequel to our joint paper in which upper bound estimates for large deviations for Markov chains are studied.The purpose of this paper is to characterize the rate function of large devia- tions for jump processes.In particular,an explicit expression of the rate function is given in the case of the process being symmetrizable.

Phase selection and microstructure evolution within eutectic Ti-Si alloy solidified at containerless state

Phase selection and microstructure evolution of the undercooled eutectic Ti-Si alloy were systematically investigated by the electromagnetic levitation method, and the maximum undercooling achieved was 318 K(0.2 TE). The migration of the liquidsolid interface was in-situ detected by a high-speed camera system. When the undercooling is smaller than 140 K, the liquid-solid interface is smooth. Once the undercooling arrives at 230 K, the liquid-solid interface is irregular, which reflects the growth transition from the solute control to the combined controls of solute and thermal. The eutectic growth velocity increases as an exponential function of undercooling. The electromagnetic stirring effect makes it difficult to increase undercooling, but plays an important role in accelerating the eutectic reaction velocity at low and moderate undercoolings. Primary dendritic β-Ti phase appears in the solidified alloy from 63 to 176 K undercoolings, and the microstructure is completely composed of eutectic once the undercoolings increase up to 230 K. When the undercoolings exceed 273 K, the microstructure consists of uniformly distributed irregular eutectic. For the drop tube experiments, the microstructures composed of a large amount of dendritic α-Ti phase and eutectic phase are found in a wide range of diameters from 69 to 725 μm. As the decrease of diameter, the solubility of Si in the dendritic α-Ti phase dramatically increases from 6.80% to 10.73%, and the ratio of the area occupied by the dendritic α-Ti on a cross-section of solidified alloy obviously increases from 23.52% to 41.02%, which result from the combined effects of high undercooling and large cooling rate.