IJISA Vol. 1, No. 1, Oct. 2009
Cover page and Table of Contents: PDF (size: 128KB)
In this paper, the general problem about the orbit and attitude dynamic model is discussed. A feedback linearization control method is introduced for this model. Due to the asymmetric structure, the orbital properties of such satellites are the same as traditional symmetric ones, but the attitude properties are greatly different from the symmetric counterparts. With perturbations accumulate with time, the attitude angles increase periodically with time, but the orbital elements change much slower than the attitude angles. In the attitude dynamic model, chaos could appear. Traditional linear controllers can not compensate enough for asymmetric satellite when the mission is complex, especially in maneuver missions. Thus nonlinear control method is required to solve such problem in large scale. A feedback linearization method, one robust nonlinear control method, is introduced and applied to the asymmetric satellite in this paper. Some simulations are also given and the results show that feedback linearization controller not only stabilizes the system, but also exempt the chaos in the system.[...] Read more.
In the process of product manufacturing, control of assembly error will directly affect product operating behavior. When product running, operating loads will lead to change of assembly relation of product parts, affecting product behavior. Based on Jacobian-Torsor method, the Jacobian Torsor tolerance model, considering contribution of operating loads, was extended and corrected, the assembly error (assembly relation change) resulted from operating loads can be calculated. Variation of running behavior with assembly error was divided to three phases: compensation phase, rapid loss phase and total loss phase. Based on changing curve of product behavior, function of behavior loss was constructed to describe behavior loss resulting from assembly error of a part of product. The conception and calculating method of behavior loss index (BLI) are given to reflect behavior changing status of whole product under certain assembly accuracy. Combined with extended Jacobia -Torsor method, the calculated results can be used to predict product behavior change led by operating loads. The prediction can help to know next measurement adopted in product design phase. An example is given to demonstrate calculating procedure of given method.[...] Read more.
An operating simulation mode based on storage volume control method for multireach canal system in series was established. In allusion to the deficiency of existing controlled volume algorithm, the improved algorithm was proposed, that is the controlled volume algorithm of whole canal pools, the simulation results indicate that the storage volume and water level of each canal pool can be accurately controlled after the improved algorithm was adopted. However, for some typical discharge demand change operating conditions of canal, if the controlled volume algorithm of whole canal pool is still adopted, then it certainly will cause some unnecessary regulation, and consequently increases the disturbed canal reaches. Therefor, the idea of controlled volume operation method of continuous canal pools was proposed, and its algorithm was designed. Through simulation to practical project, the results indicate that the new controlled volume algorithm proposed for typical operating condition can comparatively obviously reduce the number of regulated check gates and disturbed canal pools for some typical discharge demand change operating conditions of canal, thus the control efficiency of canal system was improved. The controlled volume method of operation is specially suitable for large-scale water delivery canal system which possesses complex operation requirements.[...] Read more.
According to the slope in geotechnical engineering, many displacement monitoring points are usually set to obtain the displacement data to ensure slope stability, these data are typical nonlinear time series, and it has high value about how to make use of displacement monitoring data to do the next step forecast analysis. Due to a certain degree of error, smoothing filter method is used to pretreat the displacement data, eliminate the influence of the error on the results and ensure the rationality. Based on smoothing filter data, these two methods are proposed to predict the displacement of the slope: exponential smoothing and chaos neural network. Both methods are used to make predictive analysis of the displacement monitoring data of outer monitoring point TP/BM27 in high slope of Three Gorges Ship-Lock, forecasting results show that: predictive values are close to measured values, chaos neural network prediction method is better than exponential smoothing method. At the same time, the displacement data with higher reliability and smoothing filter processing are used to make predictive analysis, the results can be more reasonable, so smoothing filter processing plays an important role in the analysis of displacement prediction.[...] Read more.
In order to enhance inter-particle cooperation and information sharing capabilities, an improved particle swarm algorithm optimization model is proposed by introducing the centroid of particle swarm in the standard PSO model to improve global optimum efficiency and accuracy of algorithm, then parameter selection guidelines are derived in the convergence of new algorithm. The results of Benchmark function simulation and the material balance computation (MBC) in alumina production show the new algorithm, with both a steady convergence and a better stability, not only enhance the local searching efficiency and global searching performance greatly, but also have faster higher precision and convergence speed, and can avoid the premature convergence problem effectively.[...] Read more.
This paper mainly studies angle-measurement based track processing approach to overcome the existing problems in the applications of traditional approaches for bearing-only target locating and tracking system. First, this paper gives suited data association algorithms including track initiation and point-track association. Moreover, a new tracking filtering association gate method is presented through analysis of the target motion characteristics in polar coordinates for improving bearing-only measurement confirming efficiency of real target and limiting false track overextension with the dense clutter. Then, by analyzing the feasibility of using multi-model technology, the IMM is adopt as filtering algorithm to solve existing problem in bearing-only tracking for complicated target motion in two dimensional angle plane. As the results, the two dimensional bearing-only tracking accuracy of real target is improved and false tracking is greatly limited. Moreover, computation cost of IMM is analyzed in view of the real-time demand of bearing-only tracking. Finally, this paper gives some concrete summary of multi-model choosing principle. The application of the proposed approach in a simulation system proves its effectiveness and practicability.[...] Read more.
Soil cave foundation is a common type in the soil foundation in karst area, the stability of the foundation will be directly affected by the soil cave collapse destruction. Currently, the stability evaluation of soil cave foundation is mostly focus on the quantitative evaluation, such as the collapse mechanism and prevention, while the qualitative assessment is rare. Based on the plastoelasticity theory, firstly analyze the stress state of the soil cave wallsurrounding body in the foundation, distinguish the stress concentration influence area, then improve the soil cave foundation stability computation model by using Molecoulomb strength criterion, finally, take a soil cave foundation stability evaluation as the example in Tongren area, Guizhou, confirming the feasibility and reliability of the improvement model. The influence of the foundation bed size, buried depth, soil cave shape and groundwater level depth was further studied, which reveals the mechanism of the soil cave collapse destruction. And the research indicated that the improved model is feasible, when the foundation bed size is smaller, the buried depth is shallower, the hole shape is more spiky and the groundwater level depth is shallower, the soil cave stability coefficient will be bigger, which is more advantageous to the stability, and the influence of groundwater level depth is more sensitive to the soil cave stability, once the groundwater level depth dropped a little, the stable soil cave will become into failure and instability. Therefore, the quantitative evaluation should be paid more attention in soil cave foundation stability evaluation, particularly under the ground water environment, simultaneously, the calculation results, like soil cave foundation maximum size, the critical buried depth, the maximum water level buried depth, have the strong directive function to the soil cave foundation treatment and design.[...] Read more.
Based on fuzzy similarity degree, entropy, relative entropy and fuzzy entropy, the symmetric fuzzy relative entropy is presented, which not only has a full physical meaning, but also has succinct practicability. The symmetric fuzzy relative entropy can be used to measure the divergence between different fuzzy patterns. The example demonstrates that the symmetric fuzzy relative entropy is valid and reliable for fuzzy pattern recognition and classification, and its classification precision is very high.[...] Read more.