摘要：Piezoelectric ceramic based high-temperature acoustic emission(AE)sensor is required urgently in the structural health monitoring of high-temperature *** this research,a series of 0.45(BiSc_(x)O_(3)-BiFe_(1-x)O_(3))-0.48PbTiO_(3)-0.07BaTiO_(3)(BSc_(x)Fe_(1-x)-PT-BT,n(Sc)/n(Fe)=0.4/0.6-0.6/0.4)ceramics with both high Curie temperature and large piezoelectric constant were *** structure and electrical properties of BSc_(x)Fe_(1-x)-PT-BT ceramics as a function of n(Sc)/n(Fe)have been systematically *** the ceramics possess a perovskite structure,and the phase approaches from the rhombohedral toward the tetragonal phase with the decrease of n(Sc)/n(Fe).The BSc_(0.5)Fe_(0.5)-PT-BT and BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramics exhibit good piezoelectricity(d_(33)=250-281 pC/N),high Curie temperature(T_(C)=430-450℃)and excellent temperature *** improvements are greatly attributed to the balance between rhombohedral and tetragonal phase near morphotropic phase boundary with dense microstructure of *** sensor based BSc_(0.5)Fe_(0.5)-PT-BT piezoelectric ceramic was designed,prepared and *** high-temperature stability of AE sensor was characterized through pencil-lead breaking with in situ high-temperature *** noise of AE sensor is less than 40 dB,and the acoustic signal is up to 90 dB at 200℃.As a result,AE sensors based on BSc_(x)Fe_(1-x)-PT-BT piezoelectric ceramics are expected to be applied into the structural health monitoring of high temperature fields.

摘要：以深圳市大铲湾为研究对象,针对其潮流特征提出将原设计方案“一渠双闸”优化为“一渠一闸”,并基于MIKE21二维数学模型对海闸调度优化后大铲湾的水交换情况进行了数值模拟。结果表明:受西乡河影响的湾尖区域水质,无降雨情况下在第9 h恢复到初始值;初小雨情况下在第106 h(降雨结束后第3.4 d)恢复到初始值。即海澜路闸保持原运行方式,取消湾顶闸对湾尖区域水交换改善几乎无影响。该优化方案节约了工程投资,也为类似海湾水交换改善的海闸调度方案设计提供了参考。

摘要：针对池河国控断面水质不达标问题,分析潜在污染源,利用相关性分析方法,找到与国控断面水质变化趋势一致的污染源,再通过建立水环境数学模型,验证主要污染源,提供针对性治理措施。找准污染源是水环境治理的重要前提,该判定方法的推广能够在保证水体水质达标的前提下,大大减少治理资金的投入,达到事半功倍的效果。

摘要：关联理论是一种认知语用学理论,对古典名著单元教学具有指导意义。针对教材解读和教学实践中存在的“失联”现象,古典名著单元教学可以通过认知关联、学用关联和循证关联架构单元教学内容,进阶设计单元教学策略,推进课内外阅读,从而建构精读、略读、课外阅读三位一体的教学样态,提升学生语文综合素养。

摘要：The main reason why the application of nuclear technology in petroleum exploration has not yet been accepted by most exploration workers is that they are not clear about the homologous distribution features of oil and gas fields and radioactive radiation. The authors hold that the disequilibrium of uranium, radium and radon as a natural radioactive series is the basic feature in the use of this technology in petroleum exploration. The invention Gamma-ray Spectral Measurement of the Equilibium Coefficient Kp and Its Embodiment of the senior author now can readily solve that problem and replace the impedient measure of normalization of uranium and potassium to thorium that had to be proposed before. Application of this impedient measure has some limitations. In areas where the surface is covered by beach or river sands, thorium minerals such as monazite may be concentrated by placering. This could result in local thorium highs that would yield local uranium and potassium lows after normalization to thorium, and these would constitute false anomalies.

摘要：针对大跨度双曲桁架拱钢闸门结构的优化设计,采用拉丁超立方随机抽样方法建立试验抽样点,通过对抽样点的训练建立人工神经网络(ANN)预测模型;同时协同遗传算法(GA)的全局搜索能力,基于ANN模型构造相应的适应度函数,提出了一种ANN-GA协同优化的结构优化模型,并对某拟建60 m大跨度双曲桁架拱钢闸门关键构件进行结构优化设计。结果表明,ANN模型可有效应用于结构尺寸与闸门总质量及最大折算应力的非线性建模,训练后的ANN-GA模型可根据结构尺寸准确预测该结构尺寸下所对应的闸门总质量及最大应力值;通过建立基于ANN模型构建的适应度函数,GA可实现在ANN模型预测的基础上快速全局寻优并快速收敛,基于ANN-GA的协同优化方法对于闸门结构尺寸优化切实有效。研究成果可为闸门结构优化设计提供参考。

摘要：Molybdenum-based catalysts have demonstrated significant potential in the electrocatalytic hydrogen evolution reaction(HER).However,the limited exposure of active sites and strong hydrogen adsorption result in suboptimal ***,a Mo_(2)N±MoSe_(2) heterojunction is prepared on carbon cloth(MNS/CC)to enhance the *** strong electronic interaction between Mo_(2)N and MoSe_(2),combined with the lower work function of Mo_(2)N,creates an intrinsic electric field at the heterojunction interface,which markedly improves charge transfer ***,the optimized electronic structure of Mo sites further enhances charge transfer and intrinsically catalytic activity in *** a result,MNS/CC requires overpotentials of mere 65 and 210 mV to achieve current densities of 20 mA cm^(−2) and 1 A cm^(−2),respectively,with a Tafel slope of only 96 mV dec−***,MNS/CC maintains stable operation at 1 A cm^(−2) for 240 h without significant *** results offer insights into the design of non-precious metal-based electrocatalysts for industrial hydrogen production.

摘要：The fuel consumption associated with some interplanetary transfer trajectories using chemical propulsion is not affordable. A solar sail is a method of propulsion that does not consume fuel. Transfer time is one of the most pressing problems of solar sail transfer trajectory design. This paper investigates the time-optimal interplanetary transfer trajectories to a circular orbit of given inclination and radius. The optimal control law is derived from the principle of maximization. An indirect method is used to solve the optimal control problem by selecting values for the initial adjoint vari- ables, which are normalized within a unit sphere. The conditions for the existence of the time-optimal transfer are dependent on the lightness number of the sail and the inclination and radius of the target orbit. A numerical method is used to obtain the boundary values for the time-optimal transfer trajectories. For the cases where no time-optimal transfer trajectories exist, first-order necessary conditions of the optimal control are proposed to obtain feasible solutions. The results show that the transfer time decreases as the minimum distance from the Sun decreases during the transfer duration. For a solar sail with a small lightness number, the transfer time may be evaluated analytically for a three-phase transfer trajectory. The analytical results are compared with previous results and the associated numerical results. The transfer time of the numerical result here is smaller than the transfer time from previous results and is larger than the analytical result.

摘要：A conventional Fowler flap is designed to improve the take-off and landing performances of an aircraft. Because the flight states of general aviation aircraft vary significantly. A Fowler flap with a double-sliding track has been designed, which is ca- pable of changing airfoil camber while cruising and climbing as well as meeting low-speed performance requirements. The aerodynamic characteristics of the variable camber Fowler flap were studied by computational simulation, and cambering was found to be beneficial for improving the lift-to-drag ratio when the lift coefficient was larger than the critical value, below which decambering was more effective; this critical value differed somewhat under different conditions. Taking the mecha- nism into account, the take-off and landing configurations were optimized on the basis of the GA （W）-1 airfoil with a 30% chord Fowler flap. Compared with reference configuration, the maximum lift coefficient of optimized take-off configuration was increased by 6.6% as well as the stalling angle and the lift-to-drag ratio were increased by 1.3° and 7.58%, respectively. Moreover, the maximum lift coefficient of the optimized landing configuration was increased by 6.3%, and the stalling angle was increased by 1.1°; however, the nose-down pitching moment of both configurations increased. Similar results were at- rained on a general aviation aircraft wing/body combination nism was established in a computer-aided design system, achieved by the double-sliding track. A 3D model of the variable-camber Fowler flap driving mecha- and the results showed that all design configurations could be

摘要：为了分析风扇转子叶片前缘侵蚀对压缩系统不同内外涵工况气动特性的影响,通过多级联算数值分析了某型大涵道比发动机压缩系统气动特性变化。研究结果表明,在峰值效率点工况下,前缘侵蚀后的发动机压缩系统总压比、等熵效率和通道流量分别相对下降0.18%、0.879%和0.972%。对风扇转子叶片而言,前缘侵蚀导致外涵道近喘点工况下95%叶高处表面静压系数曲线轴向0~24%区间的斜率下降,静压降低,轴向24%~40%区间的斜率上升,使叶型负荷降低,增压能力下降,激波向前移动。此外,前缘侵蚀会使外涵道近喘点处整体风扇叶片的攻角增大2°左右,导致叶片气动效率和失速裕度产生变化,偏离原始叶型设计。