石英晶体板非线性高频振动的拓展伽辽金法分析

针对考虑几何和材料非线性的石英晶体板厚度剪切振动和弯曲振动的方程组,利用扩展伽辽金法对该方程组进行转化和求解,分别获得了强烈耦合的厚度剪切振动模态和弯曲振动模态的频率响应关系,绘制了不同振幅比和不同驱动电压影响下的频率响应曲线图。数值计算结果表明可以选取石英晶片的最佳长厚比尺寸来避免两种模态的强烈耦合。驱动电压的变化将引起石英晶体谐振器厚度剪切振动频率的明显改变,必须将振动频率的漂移值控制在常用压电声波器件的允许值之内。扩展伽辽金法对石英晶体板非线性振动方程组的求解为非线性有限元分析和偏场效应分析奠定了基础。     

On Necessary Optimality Conditions with Higher-Order Complementarity Slackness for Set-Valued Optimization Problems

Set-Valued and Variational Analysis - We aim to establish Karush-Kuhn-Tucker multiplier rules involving higher-order complementarity slackness under Hölder metric subregularity. These rules...     

Hierarchical motion planning at the acceleration level based on task priority matrix for space robot

Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to...     

Consolidation of composite cathodes with NCM and sulfide solid-state electrolytes by hot pressing for all-solid-state Li metal batteries

Journal of Solid State Electrochemistry - In this study, hot pressing was evaluated as a method of cell fabrication to increase the energy density of next-generation all-solid-state batteries with...     

CdS/Si nanofilm heterojunctions based on amorphous silicon films:Fabrication,structures,and electrical properties

Shortening the distance between the depletion region and the electrodes to reduce the trapped probability of carriers is a useful approach for improving the performance of heterojunction.The CdS/Si nanofilm heterojunctions are fabricated by using the radio frequency magnetron sputtering method to deposit the amorphous silicon nanofilms and Cd S nanofilms on the ITO glass in turn.The relation of current density to applied voltage(I-V)shows the obvious rectification effect.From the analysis of the double logarithm I-V curve it follows that below~2.73 V the electron behaviors obey the Ohmic mechanism and above~2.73 V the electron behaviors conform to the space charge limited current(SCLC)mechanism.In the SCLC region part of the traps between the Fermi level and conduction band are occupied,and with the increase of voltage most of the traps are occupied.It is believed that Cd S/Si nanofilm heterojunction is a potential candidate in the field of nano electronic and optoelectronic devices by optimizing its fabricating procedure.     

Amorphous High-Entropy Hydroxides of Tunable Wide Solar Absorption for Solar Water Evaporation

The high-entropy materials have raised much attention in recent years due to their extraordinary performances in mechanical, catalysis, energy storage fields. Herein, a new type of high-entropy hydroxides (e.g., NiFeCoMnAl(OH)_x) that are amorphous and capable of broad solar absorption is reported. A facile one-pot co-precipitation method is employed to synthesize these amorphous high-entropy hydroxides (a-HEHOs) under ambient conditions. The a-HEHOs thus obtained display widely tunable bandgap (e.g., from 2.6 to 1.1 eV) due to their high-entropy and amorphous characteristics, enabling efficient light absorbance and photothermal conversion in the solar regime. Further solar water evaporation measurements show that the a-HEHOs delivered a considerable energy conversion efficiency of 55%, comparable to black titanium oxides that are synthesized using more complex and expensive methods.     

Uncertain random data envelopment analysis for technical efficiency

Fuzzy Optimization and Decision Making - Data envelopment analysis (DEA) is a classical and prevailing tool for estimating relative efficiencies of multiple decision making units (DMUs). However,...     

Oscillation-preserving Legendre-Galerkin methods for second kind integral equations with highly oscillatory kernels

Numerical Algorithms - The original solutions of highly oscillatory integral equations usually have rapid oscillation, which means that conventional numerical approaches used to solve these...     

Extension/Compression-Controlled Complete Band Gaps in 2D Chiral Square-Lattice-Like Structures

Achieving tunable band gaps in a structure by external stimuli is of great importance in acoustic applications. This paper aims to investigate the tunability of band gaps in square-lattice-like elastic periodic structures that are usually not featured with notable band gaps.Endowed with chirality, the periodic structures here are able to undergo imperfection-insensitive large deformation under extension or compression. The influences of geometric parameters on band gaps are discussed via the nonlinear finite element method. It is shown that the band gaps in such structures with curved beams can be very rich and, more importantly, can be efficiently and robustly tuned by applying appropriate mechanical loadings without inducing buckling. As expected, geometry plays a more significant role than material nonlinearity does in the evolution of band gaps. The dynamic tunability of band gaps through mechanical loading is further studied. Results show that closing, opening, and shifting of band gaps can be realized by exerting real-time global extension or compression on the structure. The proposed periodic structure with well-designed chiral symmetry can be useful in the design of particular acoustic devices.