Papers by Keyword: Overload

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Authors: Bing Xi, Hong Yu Wang, Er Rong Pei
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.
Authors: Wen Guang Zhang, Jun Wei Lei, Jie Cheng
Abstract: A simple differential sliding mode control law was designed for the missile overload control system without considering the uncertainties of air-dynamic coefficients. The sliding mode was composed of overload error and the differential error of overload. Finally, a numerical simulation was down and it testified that it is unable to make the system stable with only pure overload control strategy. Although the sliding mode was arrived , Oscillation phenomenon was caused by the poles in imaginary axis.
Authors: Ming Xu Pan, Li Hai Wang
Abstract: Based on the development of forestry machinery and the causes for tractor accident, this paper analyzed the necessity of improving the small skidding tractors. Then the automatic overload alarm and automatic anti-tipping alarm were designed through the research on overload and tipping point of small skidding tractors. The main parameters of the devices were calculated, the operational principle was described and the two wiring diagrams were given. The feasibility of these two alarm devices is proved theoretically in this paper. Two ways are provided to improve the safety of logging operations of the tractor and an effective research method for its intelligent development in China is planed.
Authors: Xu Yan, Han Ping, Chi Cheng
Abstract: Research on the power flow transferring identification method based on DC sensitivity factors is carried out. According to the analysis of transfer power flow sensitivity factors matrix, the disadvantage of this method is proposed that it may identify incorrectly due to the only criterion of active power when fault occurs. In order to improve its performance, the criterion of impedance angle is put forward. The combination of the two criteria is applied to the improved flow transferring identification scheme. The improved scheme can identify non-faulted overload reliably and block zone 3 distance protection to prevent cascading trips effectively. The simulation results of IEEE 10-machine 39-bus system have proved its superiority and practicality.
Authors: Yun Bo Shi, He Zhang, Jun Tang, Rui Zhao, Jun Liu
Abstract: High-g acceleration sensors are used in high-impact environment, the ability of resisting high-overload is demand higher requirements.In order to determine the Shock-resistibility of the sensors, tests were performed using Hopkinson bar. Analysis of the failure mechanism of the sensor.The results show that the critical load resulting in sensor failure is about 200000g. Main failure mode of the sensor chip is broken.
Authors: Qiang Fu, Chun Ping Wang
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.
Authors: Zhi Min He, Ya Dong Liu, Wen Shen, Xu Ri Sun, Hong Jie Wang, Ge Hao Sheng, Xiu Chen Jiang
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.
Authors: Chong Xi Bai, Xin Yan Shao, Qiu Ping Wang
Abstract: Concrete blocks were arranged on both sides of the strip foundation to simulate overload. Model tests with overload or not were conducted, for four test programs including pure sand ground, single plate reinforced ground, double plates reinforced ground and single plate with two anchorage ends reinforced ground. The influence of overload on bearing capacity and settlement of ground, earth pressure and strain of FRP was analyzed. The test results showed that overload can enhance the bearing capacity, and reduce the ground settlement in a certain extent, with the beneficial effects of overload on reinforcement effect being decreased while the amount of reinforcement was increased.
Authors: J. Heidemann, J. Albrecht, G. Lütjering
Abstract: The influence of variable amplitude loading on fatigue crack propagation was investigated for two high purity versions of the alloy Al 2024 in sheet form, one with fine equiaxed grains, and the other with coarse elongated grains. Fatigue tests on center cracked specimens were conducted in vacuum at constant amplitude (R-ratio of 0.1) and with periodically applied single tensile overloads with an overload ratio of 1.5. The number of intermittent baseline cycles between consecutive overloads was varied (n=100 and n=10.000). Detailed fractographic investigations were carried out for the identification of changes in the fracture surfaces due to the overloads. Crack closure measurements were performed in all cases. The results revealed a strong influence of the overloads on the crack propagation rate. Whether overloads are retarding or accelerating the fatigue crack propagation depends on the crack propagation mechanism at constant amplitude loading and the number of intermittent baseline cycles. For n=100 retardation occurred for the fine grained alloy exhibiting homogeneous slip at constant amplitude while acceleration was observed for the alloy with coarse elongated grains showing pronounced slip band fracture at constant amplitude. For n=10.000, the formation of steps parallel to the direction of crack propagation by overloads is assumed to be the reason for the observed increase in fatigue crack propagation resistance resulting in retardation for both alloys compared to constant amplitude and n=100. The influence of crack closure on the overload effects was minor. This was verified by additional tests at R=0.5.
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