Abstract:The paper introduces a new method-QL system suggested for the first time by the author for measuring dynamic accuracy of gear cutting machine drivetrain. The system has many uses. It suits not only the measurement of mid-size machine tool but also the measurement of very slow speed, large ratio, large-size machine drivetrain

Abstract:In this paper, a calculation method of forming cutter contour of involute helical with arbitrary easement is presented, the segmantal arcs of the best uniform approximation and tolerance to fit smoothly the cutter contour points are used the profile on the cross section of the helical is calculated and the design of the cutter is examined. The method can be used to design precision forming cutter of involute helical with the arbitrary easement. It is valuable in engineering application.

Abstract:In this paper, a new PWM method-average value PWM is presented. This method has been compared with other PWM methods and realized by using a micro - processor-controlled GTR inverter. Some experimental results and discussions for them have been given.

Abstract:On the basis of the mechanism of the boiling heat transfer on low finned tube, the influence of the geometric parameters of low finned tube on boiling heat transfer is synthetically analyzed and relevant criteria which affect the optimal structure of low finned tube is deduced in this paper. The boiling heat transfer experiment on low finned tube is conducted. Distilled water and R-113 are used as test fluids The experiment is performed at local atmospheric pressure. Synthesizing a large amount of experimental data, the semiempirical equations for the optimal geometric parameters of lowfinned tube are established

Abstract:A digital power system stabilizer ( DPSS ) and its design method are presented in this paper. The mathematical model of a single machine infinite bus power system is obtained using off-line parameter identifications, and on the base of the identified model the control system is synthesized by generalized minimum variance control principles. Through feedback combination of several signals this control system has double functions of damping low frequency oscillation and automatic voltage regulating. In order to avoid static errors the very effective way is to combine discrete generalized minimum variance control with continuous integral control. Besides the proposed control strategy is very simple in structures and very easy to realize. Simulation results under several cases have shown the correctness and effectiveness of the proposed control strategy.

Abstract:In this paper, the superposition and compensation theorems are employed to calculate the electric values under the unsymmetrical open conductor states in the three-phase power systems without modifying the bus admittance or the impedance matrices of the original networks. In cotrast with conventional algorithms, the method proposed here is highly accurate, fast, convenient and flexible. It can be applied to the unsymmetrical open conductor calculations which offered in power systems for its design and operation, to determine the settings of relay and automatic deyices, as well as accident analysis.

Abstract:A flexible mathematical model used for dynamic simulation studies of HVDC systems which is based on the stale variable method is presented, and the correspongding computer program has been implemented. Generality, easy to use, and suitable to run on microcomputers are the main features of the model and the computer program. Therefore the model is easy to be extended for application. An example is given in the paper to verily the coneclness of the model and the program.

Abstract:In this paper the particular problems in transient stability study of parallel ac/dc systems are analyzed, a mathematical model together with the relevent algorithms for transient stability evaluation is proposed, and an illustrative example is given to show the effects of dc adjustment and the correctness of the model and algorithms.

Abstract:In this paper, on the base of the original shapes of discontinuities in engineering gedogy, we mainly discuss the ralations among the shape of discontinuity, the restraining effects of discontinuity deformations (including the normal deformation and the shear deformation ) and the crustal stress. Then we put forword the concept of the pseudo-dilatancy ungle which can indicate the motion direction, set up the anisotropic discontinuity model, and give some important results and formula for illustrating truly the discontinuities in rock engineering.

Abstract:In this paper, by Using Traube's Law, we presented a method with which the macromolecular structure of coal can be studied through the relation between the true density of coal and its chemical constitution Then we researched the law of the variation of the macromolecular struclure of coal with its. rank. At the same time, we discuss the rank of coal which is classified in the constitution and macromolecular structure of coal

Abstract:The mechanization of mining thinnest coal seam is a key program in the 7th five-year plan in Sichaan province, It is sponsored by The Scientific and Technieal Commission of Sichuan province. In this paper, the dynamic performance for the hydraulie servo-system of haulage party for SGW-150 shearer with coustant-power speed governing is analysed. It shows that the system designed by us is stability and reasonable for SGW-150 shearer.

Abstract:The high-precision displacement measuring technology of optic-measuring mechanics is, for the first time,successfully applied on the similar model of the model land-layer with a new-type variable modulus of elasticity. The angle of movement and the distributed displacement of upper and lower rock-layers are measured. The technology is a combination of laser's technology and the modern chemical sticker-it is called the sticking moire interferometry. Compared with the measured values, the result is very satisfactory.

Abstract:The photoelastic isodyne experimental apparatus investigated by authors is presented. The design of the integrating prism ard the relative experimental techniques are discussed,Using this apparatus the two fundamental experiments on the stress analysis of the circular disc loaded along vetical diameter and the determination of the stress intensity factor for the side crack of the extension-loaded plate are completed.

Abstract:In this paper, taking a D1201 spindle as an example, we discuss the dynamic analysis of spindle by using the theory of the complex model, we also analyse the factors which effect the dynamic characterics of spindle and give results which arc reference value to improving the structure of spindle,

Abstract:In many database applications, data have to be compressed before they can be stored. Data compression techniques with less overhead and better space saving are expected. This paper gives a data compression technique by which the size of a file may be reduced through substituting codes for its field values. The codes are the corresponding locations of the values in the hash table that is comprised of all the values of the field.The compression is effective for many applications, and the cost of the coding/decoding is equal to that of one access to the hash table. The implementation of the technique as a compression tool in DBMS for date storage and the algorithms of the coding/decoding are discussed.