Advanced Materials Research Vols. 546-547

Abstract: Quantitative structure-property relationship (QSPR) models were developed in the present work for photodegradation rate constants (kp) of fifteen individual polybrominated diphenyl ethers (PBDEs) in methanol/water (8:2) by UV light in the sunlight region. The molecular descriptors used in the QSPR models were calculated by the two semi-empirical quantum mechanical methods, RM1 and PM6, respectively. Both multiple linear regression (MLR) and artificialneural network (ANN) were applied in this study. The statistic qualities of the MLR models based on the molecular parameters obtained by RM1 and PM6 calculations were both good with the R values of 0.987 and 0.990, respectively. The QSPR model built by the ANN method with the molecular parameters calculated with PM6 is slightly better than that with RM1.

Abstract: For the purpose of the study of the mechanical mechanism of beam-reduction and rib-addition strengthening method as well as the difference between hinged beam method and rigidly connected beam method, finite element models are established for hollow slab bridge before and after strengthening respectively with the finite element software Ansys. The stress distributions on hollow slab bridge before and after strengthening are compared through numerical simulation analysis. The improvement effects of beam-reduction and rib-addition method on the transverse connection and stress state of hollow slab bridge are analyzed at the same time. It is proved that this strengthening method is of obvious effect and the bearing capacity of the existing bridge can be greatly enhanced. Meanwhile, the result of numerical simulation analysis shows that the beam-reduction and rib-addition hinged beam method and rigidly connected beam method have the similar effects. Both of them result in much improvement of transverse distribution and enhancement of transverse connection. But the rigidly connected beam method has a better overall rigidity and a tighter transverse connection. Its improvement effect on the stress state of the old beam slab is superior to that of the hinged beam method.

Abstract: In the mechanical design process for continuous overload high dynamic flight simulator, a large centrifugal force will be generated, if the arm is very heavy, the motor driving force and energy consumption will be high, so the design objective is minimization of the volume meeting the strength of selected material, this paper established the admissible design domain according to the initial model with the UG. The design variables are the volumetric densities of material in the admissible design domain for the structure. it's very small compared with centrifugal force for gravity, so the influence of gravity is negligible, with the Saint-Venant's principle to simplify constraints. Importing the model into hyperworks software, meshing with hypermesh module, Designing with topology optimization of optistruct module, got the best structure of a flight simulator's arm, and finally designed the actual structure of the arm based on the best structure. Conclusion: topology optimization of the arm flight simulator with hyperworks can reduce design cycle, and reduce weight, resulting in better dynamics.

Abstract: The paper is based on the influence of surrounding environment for heaving motion of Mother-ship during installation exercise in deep water. The relevant information of heave compensation system and research achievements in similar areas and the research status and trends of heave compensation system are mentioned. Literature survey, understanding the key link and technical difficulties of heave compensation system is carried out. According to current development and engineering needs of China's offshore deepwater installation technology, the heave compensation system dynamics model, which meets our deepwater installation requirements, is established using nonlinear dynamic theory and elastic vibration system. Basic principles of Hydraulic drive system, the law of movement response, and the factors affecting the response characteristics have been explored and the results of various factors are analyzed and researched.

Abstract: Through the establishment of the ship form coefficients and calculation conditions of the given Deep-sea installation workboat, and use the 2-d strip theory to build the mathematical model of working ship moving in waves, obtaining the significant height of heaving motion of ship, according to different wave directions and working conditions, then using the AQWA to achieve the modeling calculation, by which the response time registration curves of heaving motion under typical working conditions can be given, while making a comparative analysis of the results obtained by the two different methods, it is indicated that the differences between them are not so significant, thus satisfying the requirements of the engineering.

Abstract: This thesis firstly introduces Back-Propagation Network, the model for the theory and the common process. And we view from two perspectives: the running hour of vehicles and passenger distributed capacity, and adopt Back-Propagation Network into vehicle coordination. We prove that coordination based on Back-Propagation Network is correct through examples.

Abstract: In this paper, the geology characteristics of loess gulch area were summarized. The mechanical models of the influence of landslide, debris flow and soil erosion on the safety of the pile foundation were created. The influence of the geology casualty on the safety of the pile foundation were analyzed. The analyses showed, when the pile foundation located the varied position of the loess gulch, the influence of soil erosion on the pile foundation character (acting force of pile side, free length of the pile, the first zero point position of the flexure curve, drawdown of the maximum bending moment, the increment of the lateral displacement, the drawdown of the lateral bearing capacity, the drawdown of the stability, etc.) were strikingly different. The calculation method of the pile and pier internal force was put forward under the function of landslide thrust and pressing force of debris flow. The corresponding prevention measures to different influencing factors were presented in the end.

Abstract: Engine is a core component. It’s performance is important to the production safety, it will affect production efficiency. At the conclusion of other types of fault diagnosis method, proposed the engine fault diagnosis technology is based on SVM and noise analysis and do some pilot studies. The method can be used to early diagnosis, and can quickly and easily find fault.

Abstract: This article is the study of alternating stress of flexible wheel in harmonic gear drive system. Firstly, according to elasticity theory to theoretically analyze flexible wheel stress; then, based on the basic principle of sub-structure modal synthesis method , use the software of UG、PATRAN and ADAMS to carry out co-simulation; Finally, based on the dynamics simulation, to analyze the alternating stress simulation results of flexible wheel and compare theoretical results and simulation results to come conclusion. The results show that: altering stress simulation results of flexible wheel are coincident with theoretical simulation results, have a deeper understand the stress change trend in the drive process of flexible wheel, lay a foundation for further carrying out dynamics simulation of harmonic gear drive system.

Abstract: In this paper, weld stress field of Non-preheating with t-joint weld process of high strength low alloy steel Q550 is simulated applying the coupling analysis of temperature and stress field in finite element method(FEM) software ANSYS. The research proves that weld joins can achieve equal strength with the base metal using low alloy high strength steel flux-cored welding wire PK-YJ707A of low hydrogen slag type system. Impact absorbing energy comes up with 107J at -20°C and comes up with 80J at -40°C. After the results of bending, the weld joins have no crack or smaller than 3mm. The mechanical property meets the requirements of the HSLA Q550. In addition, the simulation result is able to more accurately predict the welding stress field that can provide theoretical basis for guiding production practices, reducing cost and improving working environment.