Implementing Information Systems: Some Practical Advice and a Richer Model

Recent research suggests that implementing information systems presents considerable difficulties and that many implementations are total or partial failures. This paper argues that what both practitioners and students require are richer and more acceptable models of information systems implementation. Accordingly, case study data concerning the introduction of manufacturing resource planning (MRP II) are used to illustrate five patterns of behaviour (rites) which capture important social actions; and four components of changing psychological orientation. It is argued that appreciation of the rites and psychological developments identified here will support effective change programmes. Guidelines based on our model are provided for practitioners.     

Phase equilibria of quasi-binary systems consisting of multicomponent polymers 1 and 2. IV: Poly(ethylene oxide)/poly(propylene oxide) systems

To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi-binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23 (1990)285; 23 (1990)299; Polym. Int., 29 (1992)219), could point curves (CPC), two-phase volume ratios ( R ) and critical solution points (CSP) have been determined experimentally for the quasi-binary mixtures of poly(ethylene oxide) (M¯_w = 647, M¯_w/M¯_n = 1.15; M¯_w and M¯_n, the weight-average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯_w = 2028, M¯_w/M¯_n = 1.08; and M_w = 2987, M_w/M_n = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18 (1977)164). The thermodynamic interaction parameter between both polymers, χ₁₂, and the concentration dependence parameters for the above quasi-binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23 (1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally.     

The 'Conceptual Change In Science' project

Abstract This paper outlines the work of the Conceptual Change in Science project, funded as part of the ESRC InTER programme. The aims of this research project are to clarify and describe the process of change in learners' conceptual understandings of natural phenomena. The domain of reasoning selected for study is that of mechanics. Computer software which may be useful in exploring and developing pupils' reasoning and promoting conceptual change in this domain is being developed and evaluated. The group that is carrying out the research is based at the Universities of Leeds, Glasgow and the Open University.     

VARIATIONS IN ALFALFA JUICE SOLUTE CONCENTRATIONS AS WATER IS EVAPORATED

Alfalfa juice was extracted from plants during the graving phases of the first and second crops. The alfalfa juice was dried and solute concentrations were measured periodically during the process using freezing point depression (FPD) as an indicator. Solute/solvent weight ratios were calculated from the freezing point depression of fresh unconcentrated 'uice extracted from both firsc and second crops. At the time of harvest, tie FPD was a function of this ratio. The first and second crops behaved distinctively different during the drying process, with the second having a larger soluce concentration and a greater FPD at a given moisture content. The appearance of preci itate during the drying process and the general1 large FPD makes this materiay a questionable product for drying vitg low temperature processes.     

Molten salts/ceramic-foam matrix composites by melt infiltration method as energy storage material

A new type of high temperature energy storage material was obtained through the melt infiltration method, using compounding SiC ceramic foam as matrix and Na₂SO₄ as phase change material. The resulting composite material was measured by XRD, SEM, TG-DSC methods. The experimental results indicate that the composite is composed of silicon carbide, sodium sulfate and square quartz, and no chemical reactions occurs between Na₂SO₄ and SiC matrix. Na₂SO₄ has a good bonding with the SiC ceramic foam matrix. As the composite material is characterized by high thermal energy storage density and high thermal conductivity, it is suit for energy storage under high temperature. Funded by the “863” Hi-Tech Research and Development Program of China (2008AA05Z418)     

Molecular simulation of phase coexistence: Finite-size effects and determination of critical parameters for two- and three-dimensional Lennard-Jones fluids

Abstact The subject of this paper is the investigation of finite-size effects and the determination of critical parameters for a class of truncated Lennard-Jones potentials. Despite significant recent progress in our ability to model phase equilibria in multicomponent mixtures from direct molecular simulations, the accurate determination of critical parameters remains a difficult problem. Gibbs ensemble Monte Carlo simulations with systems of controlled linear system size are used to obtain the phase behavior in the near-critical region for two- and three dimensional Lennard-Jones fluids with reduced cutoff radii of 3, 3.5, and 5. For the two-dimensional systems, crossover of the effective exponent for the width of the coexistence curve from mean field ( = 1/2 in the immediate vicinity of the critical point to Ising-like (= 1/8) farther away is observed. Critical parameters determined by fitting the data that follow Ising-like behavior are in good agreement with literature values obtained with finite-size scaling methods. For the three-dimensional systems, no crossover to mean field-type behavior was apparent. Extrapolated results for the critical parameters are consistent with literature estimates for similar fluids. For both two- and three-dimensional fluids, system size effects on the coexistence curves away from the critical point are small, normally within simulation statistical uncertainties.Invited paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder. Colorado, U.S.A.     

Influence of ions on the critical behavior of a binary mixture near the consolute point

The lower critical point of stratification of a 3-methylpyridine (MP)+heavy water (D₂O) mixture in the presence of Na⁺ and CI^– ions has been studied by the Toepler shadow method. Addition of 0.3% ions lowered the critical temperature and reduced the equilibration time and the gradient of the refractive index (compressibillity). The analysis of the form of the near-critical isotherm demonstrated the ionic mixture to be described by the index = 3.05 ± 0.15. which corresponds to the classical mean-field theory. The results obtained provide evidence that even small admixtures of charged particles result in a substantial suppression of fluctuations near the critical point by the long-range Coulomb interaction.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A.