Exact analytical solution for a thermal boundary layer in a saturated porous medium

The forced convection thermal boundary layer in a porous medium as an analytically tractable special case of a mixed convection problem is considered. It is shown that some general features of the mixed convection solutions reported recently by other authors [B. Brighi, J.-D. Hoernel, On the concave and convex solutions of mixed convection boundary layer approximation in a porous medium, Appl. Math. Lett. (published online, 2005); M. Guedda, Multiple solutions of mixed convection boundary layer approximations in a porous medium, Appl. Math. Lett. (published online, 2005)] can already be recovered from this exactly solvable case.     

Optimization Method for the Selection of the Appropriate Fuzzy Implication

In this paper, we introduce a method allowing us to choose the most suitable fuzzy implication in an inference system application. We introduce also a similarity measure, which we call degree of sameness of two fuzzy implications in an inference system application.     

Database diversity assessment: New ideas, concepts, and tools

We present some new ideas for characterizing and comparing largechemical databases. The comparison of the contents of large databases is nottrivial since it implies pairwise comparison of hundreds of thousands ofcompounds. We have developed methods for categorizing compounds into groupsor series based on their ring-system content, using precalculatedstructure-based hashcodes. Two large databases can then be compared bysimply comparing their hashcode tables. Furthermore, the number of distinctring-system combinations can be used as an indicator of database diversity.We also present an indepen- dent technique for diversity assessment calledthe saturation diversity approach. This method is based on picking as manymutually dissimilar compounds as possible from a database or a subsetthereof. We show that both methods yield similar results. Since the twomethods measure very different properties, this probably says more about theproperties of the databases studied than about the methods.     

Surface Study of Polymers by Static Secondary Ion Mass Spectrometry Using a Magnetic-Sector Mass Spectrometer

Results from static SIMS analysis of six thermoplastic polymers — polytetrafluoroethylene (PTFE), polyethylene (PE), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polystyrene (PS) and polycarbonate (PC) — using a magnetic-sector SIMS instrument and O₂⁺ primary beam are presented. For PTFE as a representative sample, the charging effect is reduced only with a metal grid when analyzing positive secondary ions. When negative secondary ions are analyzed, excessive charges are self-compensated with a normal-incidence electron gun. Positive-ion spectra collected agree with spectra obtained using either a quadrupole or time-of-flight SIMS instrument and noble-gas ion beams. The agreement is objectively demonstrated by means of the capability to compare spectra in the NIST/EPA/MSDC mass spectral database. The merits of the use of high-mass resolution, of which magnetic-sector SIMS is inherently capable, to provide analytical information about the molecular species native to the sample are demonstrated in distinguishing three ambiguous peaks with nominal mass ratios m/z = 27, 39 and 59 from PMMA.     

Similarity and complexity of the shapes of square-cell configurations

Summary An equivalence relation on square-cell configurations, which we call animals, is formulated precisely, using the similarity criterion of seeing parts of the shape of the animal from its interior, and an operation called squashing, leading to a smaller animal. It is noted that there is a unique smallest animal in each resulting equivalence class, called the canonical animal of its class. It is proposed that the number of cells in a canonical animalA serves as a measure of complexity of any animal similar toA. The formulation of the canonical animal is suggested as a tool for characterizing shapes of monolayer clusters of adsorbed molecules on square lattices, a problem of importance in chemical catalysis.     

菌陈挥发油GC-MS指纹图谱分析

建立了菌陈挥发油GC-MS指纹图谱，将正交投影算法用于不同样本中共有峰的提取，提高了共有峰的识别能力，降低了由于保留时间的漂移、质谱检索匹配度不高以及色谱峰重叠而引起的共有峰识别的难度．采用共有峰率、变异率及相似度等几个指标对4个不同产地的菌陈挥发油成分进行了评价，从共性、差异和整体性等多个方面全面表征菌陈挥发油的化学模式特征．结果表明，不同产地的菌陈挥发油成分大致相同，该指纹图谱可用于菌陈中挥发油成分的质量控制．     

Symmetry groups and similarity solutions for the system of equations for a viscous compressible fluid

Here, using Lie group transformations, we consider the problem of finding similarity solutions to the system of partial differential equations (PDEs) governing one-dimensional unsteady motion of a compressible fluid in the presence of viscosity and thermal conduction, using the general form of the equation of state. The symmetry groups admitted by the governing system of PDEs are obtained, and the complete Lie algebra of infinitesimal symmetries is established. Indeed, with the use of the entailed similarity solution the problem is transformed to a system of ordinary differential equations(ODEs), which in general is nonlinear; in some cases, it is possible to solve these ODEs to determine some special exact solutions.     

错误系统结构的相似变换研究

分析了现实世界中事物的可变性,以及人们利用事物可变性的可能性.在此基础上,我们研究了对串联、并联、扩缩、蕴含、反馈等六种基本结构的相似变换的系统结构的图示表示,并利用错误函数和逻辑命题去形式化描述它们的变化形式和规律.接着给出了事物可变性的结构图示和六种基本变换的变换方式,变换参数和变换体系.     

Weighted logics for artificial intelligence – an introductory discussion

Before presenting the contents of the special issue, we propose a structured introductory overview of a landscape of the weighted logics (in a general sense) that can be found in the Artificial Intelligence literature, highlighting their fundamental differences and their application areas.     

Similarity solutions for MHD thermosolutal Marangoni convection over a flat surface in the presence of heat generation or absorption effects

The problem of steady, laminar, thermosolutal Marangoni convection flow of an electrically-conducting fluid along a vertical permeable surface in the presence of a magnetic field, heat generation or absorption and a first-order chemical reaction effects is studied numerically. The general governing partial differential equations are converted into a set of self-similar equations using unique similarity transformations. Numerical solution of the similarity equations is performed using an implicit, iterative, tri-diagonal finite-difference method. Comparisons with previously published work is performed and the results are found to be in excellent agreement. Approximate analytical results for the temperature and concentration profiles as well as the local Nusselt and sherwood numbers are obtained for the conditions of small and large Prandtl and Schmidt numbers are obtained and favorably compared with the numerical solutions. The effects of Hartmann number, heat generation or absorption coefficient, the suction or injection parameter, the thermo-solutal surface tension ratio and the chemical reaction coefficient on the velocity, temperature and concentration profiles as well as quantitites related to the wall velocity, boundary-layer mass flow rate and the Nusselt and Sherwood numbers are presented in graphical and tabular form and discussed. It is found that a first-order chemical reaction increases all of the wall velocity, Nusselt and Sherwood numbers while it decreases the mass flow rate in the boundary layer. Also, as the thermo-solutal surface tension ratio is increased, all of the wall velocity, boundary-layer mass flow rate and the Nusselt and Sherwood numbers are predicted to increase. However, the exact opposite behavior is predicted as the magnetic field strength is increased.