Methodologies to evolve formal specifications through refinement and retrenchment in an analysis–revision cycle

The development of requirement specifications is done by accumulating knowledge about the desired systems in a progressive manner. This process can be supported by an analysis–revision cycle, in which the analysis phase checks the correctness of a given specification, and the revision phase modifies it, in case some problems are detected. To date, the analysis and revision activities have been typically considered in isolation, resulting in ineffective support to the stakeholders’ work. In response to that, this article introduces methodologies to conduct an interactive and integrated approach, grounded on the formalization of two basic types of evolutions (refinements and retrenchments) over multi-valued specification and modeling formalisms. Evaluation results are included to show that this approach can indeed help the stakeholders identify and clarify requirements through different stages of development.

Designing a benchmark for the performance evaluation of agent-based simulation applications on HPC

The Journal of Supercomputing - Agent-based modeling and simulation (ABMS) is a class of computational models for simulating the actions and interactions of autonomous agents with the goal of...     

Obtention of highly dispersed platelet-reinforced Al2O3 composites

The rheological behaviour of alumina/platelets (Al₂O₃ or SiC) suspensions has been established by measuring zeta potential versus pH and the relative viscosity as a function of pH, solids loading and platelets content. Highly homogeneous mixtures of alumina/platelets, with different platelets content (5, 8, 12 and 20 vol %), have been obtained by controlled flocculation at a pH value in the range 6–7. From these powders, very close to theoretical density ( 99% d _th) and slightly oriented platelet-reinforced alumina compacts have been obtained by hot pressing at temperatures ranging from 1500–1550 °C.     

Time-interval statistics applied to the analysis of low-polydispersity samples for low light-intensity levels

A time-interval-statistics method that is based on the measurement of the Laplace transform of the probability function of the time intervals between two successive photoelectrons has been applied to experiments of light diffusion from low-polydispersity samples from which the scattered intensity is weak (less than 1 photoelectron/characteristic fluctuation time). Computer-simulation methods have been used to simulate intensity fluctuations and positions of individual photoelectrons for different experimental situations. The parameters characterizing the diffusion-coefficient distribution function of the sample (mean and index of polydispersity) and their corresponding errors are obtained and analyzed as a function of the mean intensity and the polydispersity index.     

On approximate triangular decompositions in dimension zero

Triangular decompositions for systems of polynomial equations with n$n$ variables, with exact coefficients, are well developed theoretically and in terms of implemented algorithms in computer algebra systems. However there is much less research concerning triangular decompositions for systems with approximate coefficients.     

Isolation,identification, synthesis,and bioassay of the pheromone of the comstock mealybug and some analogs

The sex pheromone of the Comstock mealybug,Pseudococcus comstocki (Kuwana) was isolated from volatiles trapped from air passing over virgin female insects. Combined gas chromatography, mass and infrared spectroscopy, and microreactions indicated that the structure was 2,6-dimethyl-1,5-heptadien-3-ol acetate. This was confirmed by synthesis; several analogs were also prepared. The natural and synthetic pheromone caused similar trap capture of male insects. Synthetic analogs were significantly less attractive in field tests and the addition of minor amounts of the corresponding alcohol to the pheromone appeared to enhance trap capture, but the results were not statistically conclusive.     

Optimal Simultaneous Design and Operational Planning of Vegetable Extraction Processes

A general multiperiod linear optimization model is proposed in this study that targets the simultaneous design and operation planning decisions of a multiproduct batch plant for the production of vegetable extracts. A multiperiod environment is considered because of the market and/or seasonal fluctuations. Thereby, the model considers changes from period to period of demands, costs, prices and raw materials supplies. The objective function maximizes the net present value of the profit considering incomes, investments and resources costs, and both product and raw material inventory costs. In the plant design problem, the sequence of operations is already defined and the pursued goal is to determine both unit sizes and its configuration in the plant. Besides the usual duplication in parallel option, a novel design alternative is included which allows adding units in series to perform a given operation. The optimal design is determined by taking into account available discrete sizes of units which corresponds to the real procurement of equipments. The model is formulated by using the linear generalized disjunctive programming (LGDP). A particular plant that produces oleoresins (solvent extracts of herbs and spices) is used to illustrate the proposed approach. Nevertheless, the developed model is general and can thus be applied to any vegetable extraction process.     

Antitumour Activity of a pt(III) Derivative of 2-Mercaptopyrimidine

The complex [Pt(2)Cl(2)(Spym)(4)], where Spym = 2-mercaptopyrimidine, was synthesized and analyzed spectroscopically. The presence in the (195)Pt NMR spectrum, of only one signal for the Pt(III) indicates the symmetrical arrangement of the ligands and the identical setting of N, S and Cl atoms, PtS(2)ClN(2), for the two Pt atoms being different to other compounds described in the literature. The interaction of this complex with DNA was studied by several techniques, including circular dichroism, melting temperature determination, electron microscopy (EM) and atomic force microscopy (TMAFM). Preliminary results show a high activity against HL-60 and HeLa tumour lines for the Pt-2-mercaptopyrimidine complex in comparison with cisplatin activity. Higher values for IC(50) were obtained, while the values of LD(50) were lower than those for cisplatin.