Harmonic potential in media of inhomogeneous hydraulic conductivity

The hydraulic conductivityK of inhomogeneous isotropic saturated stable porous media is computed from the observed or known piezometric head for the special case of harmonic potentials when the streamlines and the iso-K lines are orthogonal to the isopiestic or equipotential surfaces.     

On spatially explicit models of cholera epidemics

We generalize a recently proposed model for cholera epidemics that accounts for local communities of susceptibles and infectives in a spatially explicit arrangement of nodes linked by networks having different topologies. The vehicle of infection (Vibrio cholerae) is transported through the network links that are thought of as hydrological connections among susceptible communities. The mathematical tools used are borrowed from general schemes of reactive transport on river networks acting as the environmental matrix for the circulation and mixing of waterborne pathogens. Using the diffusion approximation, we analytically derive the speed of propagation for travelling fronts of epidemics on regular lattices (either one-dimensional or two-dimensional) endowed with uniform population density. Power laws are found that relate the propagation speed to the diffusion coefficient and the basic reproduction number. We numerically obtain the related, slower speed of epidemic spreading for more complex, yet realistic river structures such as Peano networks and optimal channel networks. The analysis of the limit case of uniformly distributed population sizes proves instrumental in establishing the overall conditions for the relevance of spatially explicit models. To that extent, the ratio between spreading and disease outbreak time scales proves the crucial parameter. The relevance of our results lies in the major differences potentially arising between the predictions of spatially explicit models and traditional compartmental models of the susceptible–infected–recovered (SIR)-like type. Our results suggest that in many cases of real-life epidemiological interest, time scales of disease dynamics may trigger outbreaks that significantly depart from the predictions of compartmental models.     

Variational approach to the analysis of steady‐state thermo‐elastic wear regimes

A transient wear process on frictional interface of two thermo‐elastic bodies in a relative steady sliding motion induces shape evolution of contact interface and tends to a steady state for which the wear process occurs at fixed contact stress and strain distribution. The temperature field generated by frictional and wear dissipation on the contact surface is assumed to reach a steady state. This state is assumed to correspond to minimum of the wear dissipation power and the temperature field corresponds to maximum of the heat entropy production. The stationarity conditions of the response functionals provide the contact pressure distribution and the corresponding temperature field. The present approach extends the authors previous analyses of optimal or steady‐state contact shapes by accounting for coupled wear and thermal distortion effects. The wear rule is assumed as a non‐linear relation of wear rate to shear stress and relative sliding velocity. The analysis of disk and drum brakes is presented with account for thermal distortion effect. It is shown that the contact shape in a steady thermo‐elastic state essentially differs from that specified for mechanical loading with neglect of thermal effects. The thermal instability regimes are not considered in the paper. Copyright © 2009 John Wiley & Sons, Ltd.     

坑道口部内爆炸冲击波传播速度规律的数值分析

准确计算坑道口部内爆炸条件下冲击波传播速度的变化,是确定坑道内主动消波设备时间响应指标的关键。为此,基于AutoDyn进行5种不同工况的坑道内爆炸计算。采用量纲分析构建了冲击波传播速度的工程模型,通过对数值计算结果的拟合确定了模型的系数。与坑道化爆实验的实测值进行分析比较表明,所拟合的坑道内冲击波传播速度的经验模型最大误差为15%,作为一种工程方法而言具有较强适用性。     

盐水方肠的品质优化

通过单因素和正交试验,确定大豆分离蛋白、大豆组织蛋白和卡拉胶在盐水方肠中的最适添加比例分别为22%、15%和0.99%。     

逻辑力学原理--大统一理论·引力理论

为现代物理学提供新的研究方法,解决其前沿领域里的一些疑难问题．从物质的基本存在形式入手,将时空的本质归结为纯逻辑问题．通过对“对立统一规律”的量化处理,给出了构成时空的基本单元——逻辑量子的场方程 Ｗ （ｔ,θ,φ） ＝ Ｗ ０ｅｘｐ［ｊ（ωｔ＋ Φ（ｒ,θ,φ））］, 以及逻辑量子相互作用势场方程ｕ ＝ Ｒｅ｛ Ｋ Ｖ０ｅｘｐ［ｊΔΦ（ｒ,θ,φ）］｝ ．进而导出了基本粒子电磁结构的统一场方程 Ｑ ＝ Ｑ０２π２ Ｒ０ ＴΩ ∫ Ｔ０ Δ Ｒ（ｔ,θ,φ）ｅｘｐ［ｊΦ（ｔ,θ,φ）］ｄｔ ｄθｄφ和弱、电、强 ３ 种相互作用的大统一场方程 ｍ ２ ｄ２ｒｄｔ２ ＝ －  Ｒｅ｛ｈω１ｅｘｐ［ｊ（ΔΦ１２（θ,φ） ＋ ΔΨ（ｒ））］｝ 等．利用这些场方程并与现代物理学的有关实验成果相结合,结果证明或解释了：（１） 强相互作用的夸克囚禁和渐近自由性质,（２） 夸克的分数电荷值± ｅ／３ 和 ±２ｅ／３,（３） 核力,（４） 基本粒子的自旋 本质上是粒子表面复相位场的旋转, 其自旋量子数只能为 Ｊ＝ ± Ｎ／２　（ Ｎ ＝ ０,１,２,…）, （５） 弱、电、强 ３ 种相互作用的强度及作用力程以及为什么它们都是汤川型的相互作用,（６）基本粒子的波粒二象     

状态估计在最小方差控制中的应用

通过引入状态变量,将普通的控制系统改写为状态空间模型,应用时域上的现代时间序列分析方法和射影理论,基于ARMA新息模型和白噪声估值器,给出状态变量的滤波估值,并用状态变量的滤波代替控制系统中的观测,从而得到含有新息补偿的最小方差控制律,它比直接由控制系统得到的最小方差控制律更加准确,也更具应用价值。     

蜗舌间隙对离心泵流动噪声影响的研究

应用基于声相似律的旋转流体机械噪声声源分离方法,实现离心泵声源特性与管道声响应特性的分离。通过建立离心泵管道试验系统,根据分离得到的声源特性对蜗舌间隙与离心泵流动噪声源的定量关系进行试验研究。结果表明,当蜗舌间隙由2.5mm增加至5mm,各阶次噪声有大于10dB的下降,当蜗舌间隙超过8.5mm后,间隙的增大不会导致各阶次噪声显著下降。     

食品安全管理协同保障措施的探讨

本文论述了企业作为食品责任承担第一者,在解决好食品安全问题上必须通过道德和自律,以及依法监管来实现对危害的防范和对风险的控制。     

注塑机合模系统的优化模型研究

连杆式合模机构设计中最优参数的选择是一个很难解决的问题，本文采用现代设计的理论与方法对该形式的合模机构进行优化研究，建立了综合有合模机构的力学特性、运动特性及结构尺寸的多目标优化设计模型，详细分析了该模型的约束要求，并通过算例验证所建模型在实际工程设计中非常有效。