Papers by Keyword: Overload

Abstract: MEMS technology has been widely used in military industry, in order to further expand the scope of the MEMS pressure sensor applications in military industry, to make fuze development toward miniaturization and intelligent, do the study on special fuze MEMS pressure sensor. Environment of MEMS pressure sensor application in fuze is analyzed, consist service treatment environment and using environment, which can provide indicators for the development of the sensor. The paper analyzes several key technology of the fuze MEMS pressure sensor, including the technique of high temperature resistant, acceleration compensation, leadless, high frequency resistant and overload resistant and so on. To sum up, the continuous development of MEMS technology can make its products meet the use environment of fuze, and the development trend of the fuze also needs the support of MEMS technology, so it is necessary and feasible to carry out the research of the fuze MEMS pressure sensor.

Abstract: For the sinusoidal maneuvering missile, its important but difficulty to distinguish the Base Course with Constant Velocity Model and the Tangential Arcs Model as the trajectory model. Their similarities and differences are studied to find out the selection method firstly, and their mathematical models are set up in the base-course coordinate system based on the existing references. Using the kinematical equations, the control complexities are derived. Then with the premise of same amplify, same max tangential velocity, same base-course pitch, their overloads and plane trajectories are compared, and drawn out some useful conclusions, such as TA model should be the prior selection for route planning, while BCCV model could be its approximate solution under certain conditions.

Abstract: The influence of single overloads on the fatigue crack initiation and propagation of an EN AW 7475-T761 alloy was investigated using SEN-specimens. Into a base load with an amplitude of 80 MPa and an Rvalue of R=-1 tension compression overloads with an amplitude of 240 MPa have been introduced every 10,000 cycles. The crack length was measured with a DC-Potential drop method. The experiments have shown that cracks are initiated in the first 5% of the total lifetime and, therefore, the cyclic lifetime is dominantly determined by crack propagation. The investigation of the crack surfaces exhibit that a different number of individual cracks propagates within the specimens. The differences in the cyclic lifetimes indicate that the interaction between these cracks directly influences the cyclic lifetime. This shows that the differences in the crack propagation behaviour are responsible for the scatter of the determined cyclic lifetimes.

Abstract: In order to improve the economy of operation of transformer, this study presents a strategy to ensure the safety of power transformer for the situation of overload operation of parallel transformer. According to the variation of actual transformer operation, the authors divide the daily load curve into two typical time periods. In the high load operation period, except the constraint of minimum power loss for the economic operation, the factor for hot-spot temperature rise of the transformer should also be considered, so that an economic operation mode and parallel switching time could be obtained. This strategy estimates the hot spot temperature by the finite difference method, and obtains the optimal switching time through binary searching, according to the environment temperature and load curve. The analysis of the example of the operation of two sets of three winding transformers in parallel with different capacity shows that the method of optimization of the operation could reduce the loss. In the meantime, it could ensure the operation safety of the transformer, and prolong the service life of transformer.

Abstract: In this test, PVC insulated wire is connected to self-made large current generator, so that different high-multiple overload currents (3Ie, 3.5Ie, 4Ie, 4.5Ie and 5Ie) passes through, with the increase of overload time, observe the change of insulation material of wire and ignition situations of different combustible substance (paper scrap, absorbent cotton and fire-retardant pipe). The results show that the higher the overload multiple, the larger the ignition capability of wire to combustible substance; even though it takes short time for fire-retardant pipe to smolder, but it takes longer time for fire-retardant pipe to become burned black and fail, and both cases are free from ignition, therefore, in case there is no collapse or burn-through, a certain degree of fire retardation is available in fire-retardant pipe in comparison with other two combustible substances.

Abstract: On the basis of experimental studies on the bending resistance of FRP reinforce bridges under the effect of limited overload with high preloading amplitude values, the relationship between FRP amounts and ultimate loads is analyzed and influences of limited overload on flexural strength, deflection, crack width and height of bridges are fatherly studied. Thus damage effect rules of FRP reinforce bridges are concluded which provide scientific technology supports for the application of fiber reinforce plastic on bridge reinforcement.

Abstract: Economic development and urbanization give rise to the excavation complexion, and higher requirements on design work are put forward. The risk of excavation in soft clay area is high and the design shall be comprehensive. While in practice, the dynamic characteristic of vehicle loads is seldom calculated. In this paper, conventional one-side plane method (beam on elastic foundation method) and three-dimensional finite element method were adopted to analyze the effects of vehicle loads on the retaining strutting system of braced excavation. Moreover, the reinforcement scheme of excavation after collapse was given as references for similar situations.

Abstract: The modern aircrafts flying height is strictly limited by the conditions on the sea. Terrible conditions may lead overturning or dropping into the water to the aircraft. Whats more, the structure of the aircraft may be broken by water-impact force. The affection of the water impact must be considered to promise the safety of the aircraft. This paper focuses on the water impact to a typical symmetrical aircraft flying above sea. The water impact force related to the trajectory angle and equivalent pitch angle is researched based on the water impact force model of a two-dimensional wedge. In addition, concerning with the limitation of the aircrafts overload, the water-contact condition is proposed to avert attitude overturning and structure broken of the aircraft.

Abstract: In recent years, the phenomenon of vehicle overload in highway transportation is more and more serious. The three-dimensional dynamic FEM was adopted and a three-dimensional simulative model for asphalt pavement with subgrade based on cross-anisotropy under moving load was established by the large-scale finite element analysis software ABAQUS. The response of the stress in the pavement structure was got by using ABAQUS/Standard code. During deceleration, The simulation analysis results under the rated load were compared with those under the different overload ratio. The results show that, under moving load, the surface course of pavement is mainly in three dimension compressive stress state. The horizontal load caused by deceleration has a remarkable effect on the longitudinal stress and the horizontal shearing stress. The stress of the pavement structure under overload is much greater than that caused by the rated load. And the greater the overload ratio, the greater the deviation between them.

Abstract: Hierarchical Mobile IPv6 (HMIPv6) reduces the amount of signaling overhead between the Mobile Node (MN) and its Correspondent Node (CN) by introducing a mobility anchor point (MAP). However, handling both intra-domain handovers and tunneling traffic for MNs may cause a single point overload. In this paper, we present a MAP (Mobile Anchor Point) selection scheme based on Multi-attribute Decision Making (MADM). In our proposed scheme, the Pref and Dist in MAP option message are used as two attributes of MAP, and MN can set different weights for these two attributes according its velocity. After testing, it indicates this scheme can handle high level MAP overload and achieve better communication performance.