考虑多米诺效应的LNG储罐区池火灾风险分析

针对目前对LNG储罐的风险分析多数仅以单个储罐为研究对象,鲜有考虑储罐间的相互影响这一研究现状,提出将多米诺效应分析引入到LNG储罐区的风险分析当中。首先,对单个LNG储罐进行风险分析;其次,运用固体火焰模型计算各目标储罐接收的热辐射量,求得多米诺效应失效概率,进而对LNG储罐区池火灾进行风险分析;最后,绘制个人风险等值线图,将考虑多米诺效应前后的风险进行对比。实例分析表明,考虑了多米诺效应风险后,储罐区的风险要明显增大。     

Forest fire retardancy evaluation of carbonate minerals using DTG and LOI

Two methods were employed for measuring fire retardancy of minerals hydromagnesite, huntite and natural hydromagnesite/huntite mixtures, on forest species. The first was based on DTG under N₂ atmosphere, to isolate pyrolysis of forest species and the second on LOI for combustion measurements. The selected forest species: Pinus halepensis Mill. and Cistus incanus L., were collected from a WUI zone and were treated with 5, 10, 15 and 20 mass/mass% of minerals. Regarding DTG analysis, the minerals decrease pyrolysis rate and increase mass residue of forest species. Regarding LOI tests, minerals increase pilot ignitability of forest fuels. Hydromagnesite exhibits the best overall performance.     

Polypropylene Nanocomposites,Study of the Influence of the Nanofiller Nature on Morphology and Material Properties

Summary: In this paper we investigate the influence of various nanofilllers' aspect ratio, chemical nature and organic modification on some selected polypropylene properties, such as crystallinity, thermal and mechanical resistance and fire behaviour. Materials were prepared by twin-screw extrusion and characterized by means of scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, tensile and cone calorimeter tests. Fillers characteristics were found to influence at different extents, and for different reasons, the material final properties.     

Computations via Newtonian and relativistic kinematic systems

We are developing a rigorous methodology to analyse experimental computation, by which we mean the idea of computing a set or function by experimenting with some physical equipment. Here we consider experimental computation by kinematic systems under both Newtonian and relativistic kinematics. An experimental procedure, expressed in a language similar to imperative programming languages, is applied to equipment, having the form of a bagatelle, and is interpreted using the two theories. We prove that for any set A of natural numbers there exists a two-dimensional kinematic system B_A with a single particle P whose observable behaviour decides n∈A for all n∈N. The procedure can operate under (a) Newtonian mechanics or (b) relativistic mechanics. The proofs show how any information (coded by some A) can be embedded in the structure of a simple kinematic system and retrieved by simple observations of its behaviour. We reflect on the methodology, which seeks a formal theory for performing abstract experiments with physical restrictions on the construction of systems. We conclude with some open problems.     

Models and heuristic algorithms for a weighted vertex coloring problem

We consider a weighted version of the well-known Vertex Coloring Problem (VCP) in which each vertex i of a graph G has associated a positive weight w _i . Like in VCP, one is required to assign a color to each vertex in such a way that colors on adjacent vertices are different, and the objective is to minimize the sum of the costs of the colors used. While in VCP the cost of each color is equal to one, in the Weighted Vertex Coloring Problem (WVCP) the cost of each color depends on the weights of the vertices assigned to that color, and it equals the maximum of these weights. WVCP is known to be NP-hard and arises in practical scheduling applications, where it is also known as Scheduling on a Batch Machine with Job Compatibilities. We propose three alternative Integer Linear Programming (ILP) formulations for WVCP: one is used to derive, dropping integrality requirement for the variables, a tight lower bound on the solution value, while a second one is used to derive a 2-phase heuristic algorithm, also embedding fast refinement procedures aimed at improving the quality of the solutions found. Computational results on a large set of instances from the literature are reported.     

Robustness study of a reversed-phase liquid chromatographic method for the analysis of carboxylic acids in industrial reaction mixtures

The robustness study of the reversed-phase liquid chromatographic method developed for the quantitative analysis of carboxylic acids is a real asset to prepare method transfer because it provides an indication of its reliability during routine use. Indeed, it was possible to predict the consequences of small variations in operating conditions on the responses. The design of experiments approach was applied to model the effects and interactions of a high number of factors varying simultaneously with a limited number of runs. First we identified the factors which potentially affect the chromatographic responses used for carboxylic acids quantitation: detection wavelength (λ), column temperature (T), acetonitrile ratio in mobile phase (Me), duration of the plateau before the gradient (L) and gradient slope (S). Then we estimated the order of magnitude of realistic variations to assign factor levels. Finally a central composite design was carried out around the nominal conditions defined during method optimization. The statistical treatment of responses (retention factors, and concentrations) showed that the column temperature, the acetonitrile ratio in the mobile phase, the duration of the plateau before the gradient and the gradient slope were the most influent factors. The building of the robust domain from response-surfaces allowed us to give tolerance limits for the factors (216 nm < λ < 222 nm, 49.3 °C < T < 51.4 °C, 4.90% < Me < 5.18%, v/v, 4.5 min < L < 5.4 min, 9% < S < 11%) for which the performances of the method were maintained.     

Stability analysis for a fully discrete spectral scheme for Boussinesq systems

In this paper we perform a stability analysis of a fully discrete numerical method for the solution of a family of Boussinesq systems, consisting of a Fourier collocation spectral method for the spatial discretization and a explicit fourth order Runge–Kutta (RK4) scheme for time integration. Our goal is to determine the influence of the parameters, associated to this family of systems, on the efficiency and accuracy of the numerical method. This analysis allows us to identify which regions in the parameter space are most appropriate for obtaining an efficient and accurate numerical solution. We show several numerical examples in order to validate the accuracy, stability and applicability of our MATLAB implementation of the numerical method.     

对普通本科院校开设计算化学实验的思考

计算化学已成为化学、物理、生物、材料等专业最活跃的研究领域之一,是目前重要的科研手段和实验方法．本文分析了普通本科院校开设计算化学实验的可行性和必要性,并提出了开设计算化学实验应注意的问题．     

生物物理课题引入生物类专业大学物理创新实验体系初探

传统的大学物理实验课程内容与生物类专业课程间缺乏联系,很难激发生物类专业学生的实践兴趣,难以培养学生的科研动手和自主创新能力。如将生物物理课题引入大学物理创新实验体系,可让生物类专业学生充分认识到物理学和生物学的紧密联系,从而激发学生学习物理的兴趣和热情,提高教学质量。     

VMware在计算机实验教学中的应用

针对计算机实验对计算机教学的重要性,而部分计算机实验在实际开展中会存在一定的难度,比如破坏性较强的实验、费用较高的一些网络实验和磁盘阵列实验,文章给出Vmware解决这些实验的方法。利用这些方法能够很好解决机房维护困难、资金紧张等问题。大大改善了计算机的实验教学效果。体现了VMware在计算机实验教学中的重要作用。