Numerical verification of stationary solutions for Navier–Stokes problems

We present a numerical method to enclose stationary solutions of the Navier–Stokes equations, especially 2-D driven cavity problem with regularized boundary condition. Our method is based on the infinite dimensional Newton's method by estimating the inverse of the corresponding linearized operator. The method can be applied to the case for high Reynolds numbers and we show some numerical examples which confirm us the actual effectiveness.     

几何位置对封闭方腔内水平孤立平板自然对流换热的影响

本文以冰箱蒸发器等实际问题为背景，以空气为介质用数值模拟方法研究了封闭方腔内水平孤立平板层流自然对流时Ｒａ数及平板位置变化对Ｎｕｍ的影响，得出了可供工程应用参考的结论。同时用烟可视化的实验验证了计算结果的正确性。     

农村有线广播用音箱的设计

本文介绍了有线广播用音箱的设计,对动圈扬声器的基本原理与特性及动圈式扬声器的选择,作了深入的分析,对今后研制和生产高质量的音箱很有参考价值。     

信息技术显示设备的外壳防火性能要求

信息技术显示设备塑料外壳的阻燃性是安全防火方面的重要指标,关系到信息技术显示设备的安全性能是否能符合国家标准的要求.主要从GB4943.1-2011与IEC62368-1这两个标准着手,分别阐述了两个标准对信息技术显示设备的防火要求,并剖析了两个标准对防火要求的异同,进而为今后信息技术显示设备防火防护外壳材料和结构的选择上提供依据.     

Enclosure of the Zero Set of Polynomials in Several Complex Variables

The zero set of one general multivariate polynomial is enclosed by unions and intersections of simple unbounded sets. Sets in which multivariate real polynomials exhibit constant sign or stay positive are found. Families of stable and unstable polynomials are explicitly given. Stability means here zero-free in the closed unit n-disk or the n-disk complement. The results achieved are discussed and illustrated by examples.     

基于短时傅里叶变换的扬声器共振频率求解

通过分析在单一频率正弦信号和连续对数扫频信号下扬声器响应信号频谱的特点,提出在短时傅里叶变换的基础上,对扬声器共振频率进行求解。对扬声器扫频范围内的响应信号进行采集和短时傅里叶变换,并分析各个窗对应谐波分量的大小,进而得出共振频率。该方法能够快速获取扬声器的共振频率,测量结果准确,为扬声器在共振频率附近区域的检测提供保证。     

Interaction of mixed convection in two-sided lid driven differentially heated square enclosure with radiation in presence of participating medium

The current study addresses the mathematical modeling aspects of transport phenomena in steady, two-dimensional, laminar flow accompanied by heat transfer in a lid-driven differentially heated cavity in presence of radiatively absorbing, emitting and scattering gray medium. The walls of the enclosure are considered to be opaque, diffusive and gray. Mixed convection is the outcome of the interaction of forced convection induced by the moving vertical hot and cold wall with the natural convection induced due to the differentially heated enclosure. Two different orientations of the wall movement have been considered to simulate opposing and aiding mixed convection phenomenon and to study its interaction with radiation. Vorticity-stream function formulation of N–S equation has been employed. The discrete ordinate method has been used in modeling the radiative transport equation followed with finite volume method as discretisation technique. The effect of influencing parameters on fluid flow and heat transfer has been studied.     

关于微型扬声器阻抗曲线的一些探讨

通过对微型扬声器的阻抗曲线测试分析,说明微型扬声器在测试电压加大的条件下微型扬声器所特有的现象．对此特有现象进行了初步分析。并对通常条件下微型扬声器阻抗曲线测试时的电压怎样选择和怎样测试作了说明。     

PA纸盆发展趋势及研发的一些探讨

介绍了目前市场上对PA纸盆的要求和发展趋势;阐述了研发PA纸盆的一些技术要求(要点)和思路、方法,重点说明了对PA纸盆音质起关键性影响的因素,对纸浆打浆工艺、纸浆纤维配比等作了较深入细致的探讨.     

音频功率放大器的防火安全设计

依据音视频电子产品安全标准,介绍了音频放大器的防火要求,分析了各种音频功率放大器的防火设计.