Advanced Materials Research Vol. 663

Abstract: Making sure the safety of wind turbine tower structure in service is particularly important with the development of offshore wind turbine facility. In order to make mechanical characteristics of structure explicit, dynamic responses of structure under three different types of seismic waves were analyzed by m method and considering monopile-soil-structure interaction, then comparison with the situation when structure was consolidated in the bottom was made. The result shows, dynamic response was most obvious under the action of far-field seismic wave in such high-rise structure as wind turbine tower. When the acceleration peak of far-field seismic wave was in the level of 8-degree rare earthquake, structure would be unsafe with an oversize displacement at the top of tower. Compared with structure consolidated in the bottom, dynamic response of structure was effected by the intensity and stiffness of soil around the pile. The interaction of soil and foundation was needed to be considered in the analysis of dynamic response.

Abstract: FEA method was conducted to investigate static stress and buckling analysis of a certain all-composite landing gear strut. The critical buckling load and bucking mode shapes of the landing gear is obtained using ANSYS finite element analysis code. The first six buckling mode shapes and static stress distribution are given. According to the analysis results, the dynamic characteristics of the landing gear are discussed. The analysis method and results in this paper can be used for further study on making maintenance plan and safety verification for the landing gear.

Abstract: Power MOSFET device driven by voltage is designed as a power switching device in large capacity power supply system. It is also widely used in converters and motor controllers. However, the on-resistance characteristic during the increase of breakdown voltage is a problem. The on-resistance of super junction power MOSFET is lower by 1/3 than existing planar power MOSFET on 600V basis. This study designed 600V planar MOSFET/super junction MOSFET and compared their operation characteristics for lower on-resistance and higher breakdown voltage. The result suggested that super junction power MOSFET is better than planar power MOSFET by having 40% better on-state voltage drop performance.

Abstract: Cement Asphalt Mortar (CAM) layer is the key to the structure of slab track in the high-speed railways. In the running of high-speed railways, the CAM layer must bear the action of temperature change, initial defects and trains loading, it will lead to the degradation of CAM. This paper designed the experiments to study its mechanical property under confining pressure or water erosion, tensile property, fatigue property, interface stress of CAM and concrete roadbed; it will help us to establish the failure criterion and degradation model of CAM layer. Preliminary experiment chose three confining pressures to study the mechanical property of CAM; the results indicate that peak stress and ductility of CAM greatly increase with increase of confining pressure.

Abstract: Patients may lose part of the hand-gripping force, because of the diseases of stroke, carpal tunnel syndrome, nerve damage etc, which lead to greatly inconvenience during their daily life. The research work in this area has been really investigated in the world, and is with significant importance in medical and military areas. A mechanical exoskeleton system is designed in this project for improving hand-gripping force of these patients. The designed mechanical exoskeleton system in this project includes five parts: exoskeleton framework, finger motion intention detecting system, extra force output system, joints’ angle holding system and central construe system. In this study, titanium alloy are eventually adopted as the material of the exoskeleton framework after the mechanical analysis. A contact type sensor system for detecting finger motion intention, gripping or releasing object is also adopted in this project. Titanium-Nickel (Ti-Ni) shape memory alloy (SMA) plates are used here to provide extra 2N force for helping patients grip an object under 140g. A Ti-Ni plate based joint lock system has also been designed here for holding the angles of fingers’ joints.

Abstract: This study systematically designs a grating coupler with gradually etched depth on the silicon-on-insulator (SOI) substrate. We focus on the modulation design of the grating coupler with gradually etched depth. The proposed grating coupler is suitable for single TE-mode fiber coupling at the wavelength of 1.55μm. Its fiber coupling efficiency can be up to 57%, fiber coupling angle is 8o and the 1dB bandwidth is 73 nm. These results are better than those of conventional uniform grating coupler without gradually etched depth in terms of efficiency. The grating coupler proposed here is easier to design as compared with the non-uniform grating couplers using lag effect.

Abstract: Multi-heat source co-heating networks have become the main trend of future development. However, the research for the thermal optimization and dispatch of multi-heat source co-heating networks is quite few in our country. In this paper, the general process of the optimal dispatch for multi-heat source co-heating systems is proposed, and the mathematical model for optimal thermal dispatch of multi-heat source co-heating systems is established. In addition, formulas and parameter selection method for the typical thermal schemes were given. By taking an actually heating network as an example, procedure and method for some thermal dispatch schemes are provided, and the optimal operating scheme based on technical and economic analysis is given. The method provided in this paper may supply the theoretical basis for operation scheduling of realistic engineering heating network. It is very meaningful for saving energy and improving environment.

Abstract: In this paper, we investigate the problem of allocating transmission data rates to users in multi-user multi-carrier networks. The paper provides a general problem of power and rate allocation that the utility functions can be nonconcave and nondifferetiable. This constrained optimization problem turns utility maximization into nonconvex, which is well-known to be difficult. To solve this problem, the dual optimization is analyzed to decompose the original optimization problem, and then a simple bisection algorithm is proposed.

Abstract: In this study, one-dimensional model for the solid distribution of flocculated suspensions in clarifier blanket is investigated by considering both up-flow velocity and hydrodynamic dispersion effects. The solution of the model equation predicts that the solid concentration will decrease remarkably along with the height of the blanket. And according to the characters of flocs, operational conditions such as up-flow flux, flocculent dosage and stirring speed affect the variation of SS. The following lab-scale experimental works with synthetic ferric-sludge flocculated with PAM confirm the numerical predictions. SS in various blanket heights under different PAM dosage was analyzed to recover the relationship between SS distribution and flocculant dosage. The results show that higher dosage of PAM will cause more dramatically SS variation due to the larger diameter of the agglomerated particles. The experiment also shows that up-flow flux has slight effect on the solid distribution inside the flocs blanket. Moreover, various stirring speeds within fitful range has no significant effect on the blanket. But too fast stirring will cause SS increasing at the top of the blanket due to the breakage of flocs.

Abstract: Resorption of nutrients (C, N, P, Ca, Mg, Fe and Mn) from senescent leaves of Zostera japonica and the concentration of nutrients (C, N, P, Ca, Mg, Fe and Mn) in the sediment from three subtropical seagrass meadows (Guchenling, Zhulin and Ronggenshan) in Beihai, Guangxi, China were studied. Resorption efficiencies were quantitatively assessed by comparing nutrient content between the leaf with the highest content and the senescent leaves. In addition, the relationship between nutrient resorption efficiencies and nutrient sources (the sediment and the adult leaf) were evaluated. During the course of leaf development in Z. japonica (young leaf – adult leaf – senescent leaf), C content first rose and then declined; N and P contents gradually declined; but Ca, Mg, Fe and Mn gradually rose. During leaf senescence, resorption efficiencies of C, N, P, Ca, Mg, Fe and Mn were 2.1%, 19.5%, 45.1%, −61.1%, −12.0%, −27.1% and −72.3%, respectively. For Z. japonica, C, N and P contributed to new leaf growth, whereas Ca, Mg, Fe and Mn was not. The nutrient contents of the sediment and adult leaf were not significantly correlated to leaf nutrient resorption efficiencies. It was calculated that for Z. japonica approximately 13.8% of total N demand and 31% of total P demand could be met by internal resorption.