摘要：With comprehensive considerations of the operational safety and collection efficiency for the tracked miner collecting the seafloor poly-metallic nodules, two new improved mining paths for the miner on the deep seafloor were proposed. Compared to the conventional mining path, the design principles and superiorities of the two new paths are that the miner turning with relative long radius should avoid large sinkage and high slip, so as to ensure its operational safety, while the space between its straight-line trajectories before and after the turning is optimum, which is designed as the total width of the miner, and collect nodules as more as possible, so as to ensure its collection efficiency. To realize the new mining paths, theoretical designs and quantitative calculations were carried out to determine the exact positions for the speed controls of the miner during its whole operation process. With the new dynamic model of the miner, and through regulations of the speeds of the left and right tracks of the miner on the exact motion positions according to the theoretical calculations, the two new improved mining paths for the miner on the seafloor were successfully simulated, thus the turning radius of the miner in the simulation is about 21.8 m, while the distance between the straight-line trajectories before and after the turning is about 5.2 m. The dynamic simulation results preliminarily prove the feasibility of these two new mining paths, and further can provide important theoretical guidance and useful technical reference for the practical tracked miner operation and control on the seafloor.

摘要：To develop novel β-type biomedical titanium alloys,a series of Ti-15Mo-xNb alloys（x=0,5,10 and 15,mass fraction in%） were designed and prepared by using vacuum arc melting *** present study focused on the effect of Nb addition on the microstructure,mechanical properties and castability of Ti-15 Mo *** analysis and microstructure observation show that all the alloys consist of single β phase and the equiaxed β grain is refined with increasing Nb *** β-type Ti-15Mo-xNb alloys exhibit good plasticity and rather low compression elastic modulus（in the range of 18.388-19.365 GPa）.After Nb addition,the compression yield strength of the alloys *** increasing Nb content,the micro-hardness of the alloys *** alloys exhibit obvious fibrous strip microstructure after cold compression *** castability test shows that the castability of the alloys after Nb addition decreases and that of the Ti-15 Mo alloy is the highest（92.01%）.

摘要：This paper addresses the problem of three-dimensional trajectory tracking control for underactuated autonomous underwater vehicles in the presence of parametric uncertainties,environmental disturbances and input ***,a virtual guidance control strategy is established on the basis of tracking error kinematics,which resolves the overall control system into two cascade ***,a first-order sliding mode differentiator is introduced in the derivation to avoid tedious analytic calculation,and a Gaussian error function-based continuous differentiable symmetric saturation model is explored to tackle the issue of input *** with backstepping design techniques,the neural network control method and an adaptive control approach are used to estimate composite items of the unknown uncertainty and approximation ***,Lyapunov-based stability analysis guarantees that control error signals of the closed-loop system are uniformly ultimately ***,simulation studies are conducted for the trajectory tracking of a moving target and a spiral line to validate the effectiveness of the proposed controller.

摘要：In this study, the characteristics of nitride-based light-emitting diodes with different last barrier structures are analysed numerically. The energy band diagrams, electrostatic field near the last quantum barrier, carrier concentration in the quantum well, internal quantum efficiency, and light output power are systematically investigated. The simulation results show that the efficiency droop is markedly improved and the output power is greatly enhanced when the conventional GaN last barrier is replaced by an AlGaN barrier with Al composition graded linearly from 0 to 15% in the growth direction. These improvements are attributed to enhanced efficiencies of electron confinement and hole injection caused by the lower polarization effect at the last-barrier/electron blocking layer interface when the graded Al composition last barrier is used.

摘要：Constant current power transmission is considered a good choice for subsea observatories due to its high resistance to shunt faults. A constant current subsea observatory is planned to be constructed in the East china Sea. We discuss a constant current subsea observatory system used for scientific experiments. The power system and its heat dissipation system are carefully designed. The power conversion method is challenging due to the use of constant current power, which is considerably different from traditional power systems. Thus, we adopt power compensation circuits in the conversion system to obtain a constant 48-V output for science users. A power management system that performs overvoltage protection and real-time monitoring and control of junction box is discussed. An innovative heat dissipation structure of a junction box is designed in consideration of a sealed working environment to extend the useful life of the junction box. Simulations and experiments reveal that the system has high efficiency and stability, especially in long-term applications.

摘要：With the continuous improvement of the train speed, the dynamic environment of trains turns out to be aerodynamic domination. Solving the aerodynamic problems has become one of the key factors of the high-speed train head design. Given that the aerodynamic drag is a significant factor that restrains train speed and energy conservation, reducing the aerodynamic drag is thus an important consideration of the high-speed train head design. However, the reduction of the aerodynamic drag may increase other aerodynamic forces (moments), possibly deteriorating the operational safety of the train. The multi-objective optimization design method of the high-speed train head was proposed in this paper, and the aerodynamic drag and load reduction factor were set to be optimization objectives. The automatic multi-objective optimization design of the high-speed train head can be achieved by integrating a series of procedures into the multi-objective optimization algorithm, such as the establishment of 3D parametric model, the aerodynamic mesh generation, the calculation of the flow field around the train, and the vehicle system dynamics. The correlation between the optimization objectives and optimization variables was analyzed to obtain the most important optimization variables, and a further analysis of the nonlinear relationship between the key optimization variables and the optimization objectives was obtained. After optimization, the aerodynamic drag of optimized train was reduced by up to 4.15%, and the load reduction factor was reduced by up to 1.72%.

摘要：Poly(ε-caprolactone)(PCL)holds unique bioresorbability and competent biomechanical properties for tissueengineering ***,PCL is hydrophobic intrinsically and poor in cell-biomaterial *** this study,we prepared a composite based on PCL and bioactive tantalum(Ta)to understand the effects of direct laser micropatterning on composite surface *** PCL/Ta composite after preparation was surface-patterned by femtosecond laser and characterized with surface morphology,crystal structure,chemical composition,wettability and cellular response of *** was found that laser micropatterning enlarged the difference of wetting properties(~15°)on PCL and PCL/Ta *** wetting changes was dependent on both material composition and lasermachined *** blending of Ta enhanced surface wettability with prolonged contact time on the laser-machined line and rectangle *** vitro culture results showed beneficial effects of laser micropatterning on cell morphology of the *** the PCL/Ta surfaces with line and rectangle microarrays,the cells were more likely to bridge the sidewalls of the microgrooves,showing adaptive 3D morphologies to the micro/nano topographies on the *** findings are envisaged to facilitate surface design and micropattern optimization for favorable tuning the cell response to biomedical PCL/Ta composites.

摘要：The multi-pass scheduling method is a key issue in die-less spinning for determining the quality of the final products, including their shape deviations and wall thicknesses, and has drawn increasing interest in recent studies devoted to trying to improve the accuracy of the formed parts. In this paper, two main parameters, roller path profiles and deformation allocations in each pass, are considered in newly proposed multi-pass scheduling and optimizing methods in die-less spinning. Four processing methods with different roller path profiles and with three deformation allocation methods are proposed for investigating the influence of scheduling parameters on product qualities. The ＇similar geometry principle for restraining shape deviation＇ and the ＇small curvature principle for maintaining wall thickness＇ are presented for optimal design of roller path profiles; in addition, the ＇uniform allocation principle for maintaining wall thickness＇ and the ＇large deformation principle for restraining shape deviation＇ are brought forward as suggestions for deformation allocations. Based on these principles, a scheduling method denoted by RF＋（FP ＆ EHS） is presented to improve the comprehensive quality of a product of die-less spinning.

摘要：We present a high-definition （HD） 3D laparoscopic system including a dual channel optical system, two cameras, a camera control unit （CCU）, and an HD 3D monitor. This laparoscopic system is capable of outputting dual high-definition videos and providing vivid 3D images. A modified pinhole camera model is used for camera calibration and a new method of depth measurement to improve precision. The average error of depth measurement measured by experiment （about 1.13 mm） was small in proportion to the large range in distance of the system （10-150 mm）. The new method is applicable to any calibrated binocular vision system.

摘要：In order to support the functional design and simulation and the final fabrication processes for functional surfaces,it is necessary to obtain a multi-scale modelling approach representing both macro geometry and micro details of the surface in one unified *** on the fractal geometry theory,a synthesized model is proposed by mathematically combining Weierstrass-Mandelbrot fractal function in micro space and freeform CAGD model in macro *** issues of the synthesis,such as algorithms for fractal interpolation of freeform profiles,and visualization optimization for fractal details,are addressed.A prototype of the integration solution is developed based on the platform of AutoCAD's Object ARX,and a few multi-scale modelling examples are used as case *** the consistent mathematic model,multi-scale surface geometries can be represented ***,the visualization result of the functional surfaces shows that the visualization optimization strategies developed are efficient.