摘要：In coastal areas with complicated flow movement, deposition and scour readily occur in submarine excavation projects. In this study, a smallscale model, with a high resolution in the vertical direction, was used to simulate the tidal current around a submarine excavation project. The finite volume method was used to solve Navier-Stokes equations and the Reynolds stress transport equation, and the entire process of the tidal current was simulated with unstructured meshes, generated in the irregular shape area, and structured meshes, generated in other water *** meshes near the bottom and free surface were densified with a minimum layer thickness of 0.05 m. The volume of fluid method was used to track the free surface, the volume fraction of cells on the upstream boundary was obtained from the volume fraction of adjacent cells, and that on the downstream boundary was determined by the water level process. The numerical results agree with the observed data, and some conclusions can be drawn: after the foundation trench excavation, the flow velocity decreases quite a bit through the foundation trench, with reverse flow occurring on the lee slope in the foundation trench; the swirling flow impedes inflow, leading to the occurrence of dammed water above the foundation trench; the turbulent motion is stronger during ebbing than in other tidal stages, the range with the maximum value of turbulent viscosity, occurring on the south side of the foundation trench at maximum ebbing, is greater than those in other tidal stages in a tidal cycle, and the maximum value of Reynolds shear stress occurs on the south side of the foundation trench at maximum ebbing in a tidal cycle. The numerical calculation method shows a strong performance in simulation of the hydrodynamic characteristics of tidal currents in the foundation trench, providing a basis for submarine engineering construction in coastal areas.

摘要：Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their ***,a novel ultra-small amorphous Fe_(2)O_(3)nanodots/graphene heterostructure(a-Fe_(2)O_(3)NDs/RGO)aerogel was facilely synthesized via excessive metal-ion-induced self-assembly and subsequent calcination route using Prussian blue/graphene oxide(PB/GO)composite aerogel as *** deliberately designed a-Fe_(2)O_(3)NDs/RGO heterostructure offers a highly interconnected porous conductive network,large heterostructure interfacial area,and plenty of accessible active sites,greatly facilitating the electron transfer,electrolyte diffusion,and pseudocapacitive *** obtained a-Fe_(2)O_(3)NDs/RGO aerogel could be used as flexible free-standing electrodes after mechanical compression,which exhibited a significantly enhanced specific capacitance of 347.4 F·g^(-1)at 1 A·g^(-1),extraordinary rate capability of 184 F·g^(-1)at 10 A·g^(-1),and decent cycling *** the as-prepared a-Fe_(2)O_(3)NDs/RGO as negative electrodes and the Co_(3)O_(4)NDs/RGO as positive electrodes,an all-solid-state asymmetric supercapacitor(a-Fe_(2)O_(3)NDs/RGO//Co_(3)O_(4)NDs/RGO asymmetric supercapacitor(ASC))was assembled,which delivered a high specific capacitance of 69.1 F·g^(-1)at 1 A·g^(-1)and an impressive energy density of 21.6 W·h·k·g^(-1)at 750 W·k·g^(-1),as well as good cycling stability with a capacity retention of 94.3%after 5,000 *** work provides a promising avenue to design high-performance graphene-based composite electrodes and profound inspiration for developing advanced flexible energy-storage devices.

摘要：The theoretical model of spatial noise passing through a spatial filter is established in high power laser system under the small signal approximation. The transmission characteristic for a noise signal passing through spatial filters with different magnifications is analyzed by numerical simulation, according to the actual structure of the high power laser system. The results show that the spatial modulation period of low-frequency noise getting through the pinhole will be proportional to the magnification of the spatial filter. When the magnification is less than 1, the safe low-frequency noise will be extruded into the high-frequency region, which is the fast increasing part, and finally develops into the most dangerous part which can damage the optical devices. The conclusion of this research improves the relay imaging theory of a spatial filter and provides an important theoretical basis for a general design of high power laser systems.

摘要：为了能够支撑微电网的电压和频率，提高微电网运行的稳定性，本文针对采用虚拟同步发电机（VSG）控制策略的微网逆变器进行了研究。由于VSG中虚拟惯性的存在，在功率调度指令突变时，微网逆变器的频率和输出功率会发生振荡，严重时将导致逆变器因过流保护而停机。本文在功率闭环传递函数根轨迹分析影响VSG稳定性和动态性能的参数变化范围的基础上，采用线性二次型最优控制，以功率和频率变化量为约束条件，提出了最优虚拟惯性控制策略，通过对VSG参数进行优化配置解决了上述问题。Matlab仿真和实验结果验证了该控制策略的正确性和有效性。

摘要：供应商选择对高速列车转向架配置设计的质量、成本、交货时间有着显著影响。针对转向架配置设计和供应商选择集成优化中未考虑不同决策之间的差异和协调问题,本文提出一种基于Stackelberg博弈理论的集成供应商选择的高速列车转向架配置优化方法。该方法基于主从决策机制构建主从关联优化模型,上层以物理模块配置方案效用最大为目标获取模块实例组合方案,下层以供应商预期总成本最小为目标获取供应商选择方案,并采用双层嵌套遗传算法进行求解。以某型高速列车转向架的“构架、轮对轴箱装置”为例,得到物理模块配置方案和供应商选择方案的均衡最优解。所提出的方法有助于企业实现考虑供应商因素的转向架配置设计,提高产品的竞争力。

摘要：为了推动生物科学专业的发展和培养人才的需要,植物生理学实验课需要不断地进行改革.分析了传统植物生理学实验课教学中存在的共性问题,从教学内容、教学方法、学生成绩评价考核和开放实验室等提出了可行性的建议.教师要适应时代的发展积极改进教学内容以及教学方法和手段,改革学生成绩的评定方式,开放实验室,设计相关实验比赛,引导学生积极参与到课堂中,全面提高学生的动手能力,开发创造力,提升创新意识,从而提高植物生理学实验的教学效果,进一步推进高校生物科学专业植物生理学课程的教学改革,培养适应社会需求的高水平人才.

摘要：lightweight design is important for the Thermal Protection System(TPS) of hypersonic vehicles in that it protects the inner structure from severe heating environment. However, due to the existence of uncertainties in material properties and geometry, it is imperative to incorporate uncertainty analysis into the design optimization to obtain reliable results. In this paper, a six sigma robust design optimization based on Successive Response Surface Method(SRSM) is established for the TPS to improve the reliability and robustness with considering the uncertainties. The uncertain parameters related to material properties and thicknesses of insulation layers are considered and characterized by random variables following normal distributions. By employing SRSM, the values of objective function and constraints are approximated by the response surfaces to reduce computational cost. The optimization is an iterative process with response surfaces updating to find the true optimal solution. The optimization of the nose cone of hypersonic vehicle cabin is provided as an example to illustrate the feasibility and effectiveness of the proposed method.

摘要：The sandwich transducer structure is comprised of threecomponents along its main axis: the back metal cap, piezoelectricceramic stack and the horn. The purpose of this work is topresent a simplified method, referred as the equivalent lengthalgorithm, to design the actuator parameters including eachsegment length and the resonance frequency fs. The actuatorlength L and the propagation wavelength λ along its main axissatisfy the standing wave theory. So, define an equivalent lengthcoefficient for each part of the actuator, and then the sandwichstructure is regarded as a single material cylindrical rod withequivalent length L′. According to the standing wave theory, theequivalent length L′ of the actuator can be determined with thegiven resonance frequency fs, or vice versa. The phase length ofeach part of the actuator in the standing wave is optimized freelyin the design procedure. The actual length of each part of theactuator is determined by the equivalent length ***, the resonance frequencies of three given actuators arecalculated with this method. They are compared with thoseobtained through Ansys simulation and those measured by animpedance analyzer. The results show agreement.

摘要：近年来,消费者的反展厅现象(即线上逛店、线下购买)已普遍存在于消费者跨渠道购物行为中.本文建立了一个由线上和线下商家组成的双寡头市场,在该市场中两位商家同时销售搜索型产品或体验型产品,以此为基础探讨反展厅现象对线上商家的影响并提出相应的定价和广告对策.通过对均衡结果的分析,得出以下结论:1)对于搜索型产品而言,消费者是否出现反展厅现象与消费者在线上购买产品所产生的隐私成本有关:当隐私成本处于较高水平时,消费者会出现反展厅现象;对于体验型产品而言,消费者是否出现反展厅现象还与消费者与线下商品的匹配概率相关;2)不论商家销售哪种类型的产品,反展厅现象的出现均会减少线上商家的收益与产品定价,同时也会在一定程度上提高线下商家的收益.此外,线上商家对搜索型产品的定价随着更高的单位旅行成本、更低的线上搜索成本和更低的隐私成本而增加;对体验型产品的定价还会随着消费者与线下商家中产品的匹配概率下降而提高;3)线上商家可以通过投放定向广告来应对反展厅现象,缓和市场竞争并提高线上商家的收益.同时,我们还得出一个反直觉的结论,即当线上商家在定向广告上的投资成本高于一定阈值时,线下商家也会获益于定向广告;4)最后,我们对比了定向广告对搜索型产品和体验型产品在应对反展厅现象时的不同表现,发现当隐私成本相对较低时,定向广告更能提高体验型产品的收益;当隐私成本相对较高时,定向广告更能提高搜索型产品的收益.

摘要：碳酸盐岩缝洞体油气藏内部结构的精细描述是该类储集体高效井位部署和效益开发的关键技术之一。研究区缝洞体地震响应为串珠状,内部多为小尺度栅状结构,横向上具有分隔性。文中基于波形差异,改进了互相关相干算法的地震道组合方式,减小横向分析窗口,进行缝洞体内部结构分析;设计理论模型进行正演模拟并偏移成像,揭示小尺度缝洞储集体内部栅状结构地震响应特征;统计研究区实钻井储层段,并与预测结果进行吻合度比对;减小地震资料处理面元,预测的串珠状缝洞体内部栅状结构有效刻画储层段和边界;在井轨迹上标定储层段,进行三维刻画,吻合精度较高。研究结果表明,相较于常规地震资料,显著提高预测精度,降低了地震资料解释的多解性。这一方法为有利油气靶区优选和井轨迹设计优化工作提供了可靠的地震解释依据。