Applied Mechanics and Materials Vols. 52-54

Abstract: A new algorithm, named feature-based visibility analysis is proposed. This algorithm can be used widely in manufacture and process of parts or models. Compared with conventional triangle facet algorithm, the proposed feature-based algorithm can get global visibility more efficiency and accurately. The main visibility analysis consists of two steps: 1) Local visibility analysis. All features are classified into two types-features with local visibility and without local visibility. 2) Global visibility analysis. All features with local visibility should be analyzed further to detect whether the local visibility feature is sheltered by the other part of the model. In this paper, related principle and implement process (on UG flat) are introduced detailly. At last, the case study demonstrated the validity of the proposed method.

Abstract: In order to improve the machining accuracy of precision CNC lathe, and explore the fluid motion law in the closed hydrostatic guideway, three-dimensional model of hydrostatic oil chamber was established using preprocessor GAMBIT of FLUENT. The Finite Volume Method of Fluent has been used to the simulation of fluid three-dimensional velocity field and pressure field. The fluid velocity vector and pressure distribution graphs are obtained. They reveal the flow field law in the gap fluid. The simulation result of the pressure distribution shows that the flow pressure was not changing in linear gradient all around the gap under moving condition.

Abstract: The reflective cracking is one of the main damages of semi-rigid base asphalt pavement and rigid base asphalt pavement, how to control its emergence and development is still a major problem for road engineering. At present, researches on mechanical behavior of Open-graded Large Stone asphalt Mixes (OLSM) in China almost remain in the test road observations, very few study it from the point of the finite element theory. Aiming at this problem, a method of using OLSM as the cracking alleviation layer is proposed. The calculation principles of temperature stress of lean concrete base asphalt pavement with OLSM has been introduced, on the basis of the finite element software of ABAQUS, 3-D Finite Element Method (FEM) is used to analyze temperature stress for OLSM of asphalt pavement, the influence rule of pavement design parameters for its temperature stress has been discussed, and the theoretical basis for structural design of asphalt pavement with OLSM has been found.

Abstract: This paper designed a data warehouse model of agricultural production. And it built an effective and viable agricultural production data warehouse, by using some key technologies: multidimensional data analysis, cube, materialized view selection, materialized view maintenance. Finally, it provided a solution for the effective management and maintenance problems about high-capacity heterogeneous data.

Abstract: Goods and shelves are closely and numerously put in the logistics center, so there are many hidden dangers. People’s life safety and property safety are threatened by fire. The key of putting out fire and evacuating people is to grasp the changes of the important parameters in the fire. In this paper the FDS (Fire Dynamic Simulator) software developed by the U. S. National Institute of Standards and Technology (NIST) is used to build a fire model and sets two fire scenarios to analyze the fire spreading process in logistics center. According to the numerical simulation results, reasonable suggestions are put forward in the end.

Abstract: Linear rolling guide is one of the most essential parts of the NC modern machine tools, and they play a significant supporting and guiding role in machine tools components. Especially, the joint surface between guides has great influence on machine's dynamic characteristics. According to this, in this work, taken the Japanese THK Corporation's SNS35LR rolling guide as specific study object, the finite element model of guide pair has been established with the joint surface influence considered. And by the method of the theoretical analysis with the experimental confirmation combined; the dynamic characteristics of the linear rolling guide pair's were studied relatively. Thus, the theoretical model and the finite element model established in this paper can be confirmed by the experiment. It has been found that the theoretical models established are consistent with the results of experiment. This study results can provide useful guidance for the dynamic analysis and the structure optimization of CNC machine tools, and numerical simulation in engineering and design in the development of such machines with rolling guide used.

Abstract: The conventional prediction of spudcan penetration depth in multiple strata, especially the strata with sand overlying clay profile, usually has a certain deviation with the field data. In this paper, a numerical method was proposed to analyze the ultimate penetration depth for spudcan in the multi-layered profiles with sand overlying clay, and the feasibility of this method was verified by the field data. Comparisons with the approach recommended in SNAME (2002) were also included, and the proposed method showed a significant improvement in predicting spudcan penetration depth in the multiple strata with sand-over-clay profile.

Abstract: The inductance and capacitance parameters in oscillation circuit are very important for the HVDC breakers to interrupt the heavy current. In order to know the inductance and capacitance parameters, an online monitoring system of HVDC breaker is designed, and assorted software is also design to process the data got by the data acquisition system. After tested in laboratory, this online monitoring system has proved truly and reliably getting the inductance and capacitance parameters. This system can contribute to analyze the health state of the breaker proceedings breaker.

Abstract: In order to estimate the parameters of capacitance, inductance and resistance in oscillation circuit DC circuit breaker a method of parameter estimation of High-Voltage circuit break based on genetic algorithms is proposed and which can properly assess the performance of DC circuit breaker. In this paper A genetic algorithm is introduced and applied in parameter estimation of High-Voltage circuit breaker and then compare it with the traditional MATLAB curve fitting, the result clearly reveal the advantages of genetic algorithm.

Abstract: This paper presents an analysis of the nonlinear characteristics of a bridge structure and the chaos of BHM(bridge health monitoring) information. Chongqing Masangxi bridge’s BHM information is analyzed by using the max Lyapunov index with Wolf and correlation dimension with G_P algorithm. The results show:1) all of the max Lyapunov index is nonnegative ;2)the correlation dimension is non-integeral and greater than 2.These proves that the bridge structure is in the chaos. Meanwhile, with the evolution of time, the index of chaos is sensitive with status of structure system and varies in different key sections of bridge structure. These findings lay a solid foundation for the further development of bridge safety assessment and prediction when non-linear chaotic theory is utilized to analyze the bridge health monitoring information.