Combining make to order and make to stock

In inventory control and production planning one is tempted to use one of two strategies: produce all demand to stock or produce all demand to order. The disadvantages are well-known. In the make everything to order case (MTO) the response times may become quite long if the load is high, in the make everything to stock case (MTS) one gets an enormous inventory if the number of different products is large.In this paper we study two simple models which combine MTO and MTS, and investigate the effect of combining MTO and MTS on the production lead times.     

开采沉陷信息处理软件系统模块划分方法的探讨

对开采沉陷信息处理软件系统各个模块间的关系及设计原则进行了探讨．利用文中讨论的设计划分方法开发的“地表移动与三下采煤数据管理及处理”软件收到了良好的运行效果     

Interpolative approximation for the Hubbard and the emery model

Calculations in Green's function technique apply an interpolation ansatz for the self-energy between the weak and strong coupling regime to the doped case of correlated models. The DOS of the one-band Hubbard model with the Kondo-like peak at the chemical potential is in good agreement with recent numerical results. In the doped three-band model a singlet correlation band from copper and oxygen states appears at the Fermi surface with dispersion similar to the free bands but with strongly renormalized bandwidth. The Fermi surface changes from closed hole type to closed electron type upon doping and is perfectly nested for some doping valuen1.25.     

c-axis phonons and the enhancement of pairing correlations in high-temperature superconductors

We consider the two-dimensional Hubbard model including electron-phonon interaction. Strong local correlations (U limit) are taken into account within the mean-field approximation for auxiliary boson fields. Phonon-assisted transitions between intraand interlayer states are introduced as the source of coupling between two-dimensional CuO₂ layers. This type of processes effectively leads to the nonlinear (quadratic) interaction of intralayer electrons withc-axis phonons. We construct the Eliashberg equations for the resulting Hamiltonian and evaluate the superconducting transition temperatureT _c. Our model calculation demonstrates that a pronounced enhancement ofT _c in thed-wave channel is possible. The largest enhancement ofT _c tends to take place for small hole concentrations. This means that the coupling toc-axis phonons could compete with two-dimensional correlations responsible for the onset of antiferromagnetic order. It is remarkable that the two-dimensional features in the normal state are hardly affected by this specific interlayer interaction. Therefore,c-axis two-phonon-mediated interlayer coupling can cooperate with interlayer pair tunneling and substantially contribute to an increased pairing.     

Thermal conductivity of CVD diamond films

Diamond films 60 and 170 µm in thickness were grown by PACVD (plasma-assisted chemical vapor deposition) under similar conditions. The thermal diffusivity of these freestanding films was measured between 100 and 300 K using AC calorimetry. Radiation heat loss from the surface was estimated by analyzing both the amplitude and the phase shift of a lock-in amplifier signal. Thermal conductivity was calculated using the specific heat data of natural diamond. At room temperature, the thermal conductivity of the 60 and 170 m films is 9 and 16 W-cm^–1. K^–1 respectively, which is 40–70% that of natural diamond, The temperature dependence of thermal conductivity of the CVD diamond films is similar to that of natural diamond, Phonon scattering processes are considered using the Debye model, The microsize of the grain boundary has a significant effect on the mean free path of phonons at low temperatures. The grain in CVD diamond film is grown as a columnar structure, Thus, the thicker film has the larger mean grain size and the higher thermal conductivity. Scanning electron microscopy (SEM) and Raman spectroscopy were used to study the microstructure of the CVD diamond films. In this experiment, we evaluated the quality of CVD diamond film of the whole sample by measuring the thermal conductivity.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.     

Polymer solutions confined in slit-like pores with attractive walls: An off-lattice Monte Carlo study of static properties and chain dynamics

Summary Using a bead spring model of flexible polymer chains, the density profiles and chain configurational properties of polymer solutions confined between parallel plates were studied. A wide range of density , chain length N, and strength of a short-range attractive wall potential was investigated. Both a temperature T in the good solvent regime (T > , being the Theta temperature where a chain in unconfined bulk three-dimensional solution would behave ideally) and a temperature in the bad solvent regime (T < ) were considered. It is shown that phase separation in a polymer-rich and polymer-poor solution in the slit competes with polymer adsorption at the walls. A qualitative connection to the wetting behavior of semi-infinite polymer solutions is drawn. The acceptance rate for monomer motions was studied for various conditions, and profiles of monomer mobility across the slit were recorded. Also, average chain relaxation times were extracted from the time dependence of mean-square displacements. Although with increasing density the chain radii (at T > ) show a crossover from two-dimensional excluded volume behavior (R_g N² with = 3/4) to ideal random walk behavior ( = 1/2), the relaxation times show effective exponents Z_eff ( N^{Z eff}) that clearly deviate from the Rouse prediction in concentrated confined solutions.     

Robust procedures in multiple regression: P-subsets and a computational proposal

A number of robust and diagnostic techniques for the linear regression are in terms of p-dimensional subsets of the original sample. In a sample of size n this leads to consider ⁿ C _p subsets. To reduce the computational burden, a limited number of subsets can be selected by means of a sub-sampling scheme. In this paper we suggest and discuss the use of a Balanced Incomplete Block design plan.     

基于角色的用户权限管理在养猪场信息化平台中的应用

分析和总结了养猪场信息化管理平台生产管理模块对用户管理和权限拉制的具体需求;采用基于角色的访问控制模型,对权限管理的数据库表与功能模块进行了设计;对用户权限管理模块对外接口进行了简要的分析与操作流程设计.     

通信网络安全验收技术体系研究

该文采用分层模型,对通信网络安全验收技术体系进行深入研究,明确工程建设各个阶安全目标,分析了通信网络各层安全因素及安全要求,建立了安全验收技术体系框架,为通信网络工程安全验收工作提供理论指导,进而推动通信工程安全验收工作的规范化、流程化和标准化.