Numerical modelling of the propagation of fast landslides using the finite element method

This paper proposes a two‐dimensional (2D) model for the analysis of the propagation of fast landslides involving a fluidized material such as debris and mud flows, flowslides and avalanching flows. The model is based on the Navier–Stokes depth‐integrated equations. To incorporate the effect of steep slopes and centrifugal forces due to the high velocities characterizing the flowslides and the bed curvature, a curvilinear system of reference is used. The corresponding equations of motion are complemented by depth‐averaged constitutive equations and bed friction laws. The resulting set of differential equations are solved using the two‐step Taylor–Galerkin algorithm. This algorithm has been used by the authors to solve hydraulic and dam‐break problems using the finite element method. Owing to the importance of the source term compared to the advection component, the proposed algorithm follows a splitting scheme using a fourth‐order Runge–Kutta method for integrating the friction and slope components. The performance of the overall approach has been checked in a number of examples. The analysis of the results provides insights into the key elements of the model and shows the adequacy of the method to solve real problems where merging and splitting of the flow occur. Copyright © 2004 John Wiley & Sons, Ltd.     

超声波流量计计量系统性能的主要影响因素

随着我国天然气工业的发展，已有大量超声波流量计用于高压、大流量的天然气计量。尽管我国已于2001年颁布并实施了气体超声波流量计使用方面的国家标准GB/T18604-2001，但是随着超声波流量计越来越广泛的使用，国内外对超声波流量计计量性能的影响因素已有了进一步的研究；而且，目前我国超声波流量计在天然气计量中的应用效果也还需要进一步改善。因此，根据目前国、内外最新研究成果，对噪声、脏污、压力及温度测量对超声波流量计计量系统性能的主要影响因素以及控制对策进行了分析探讨，以期改变虽经实验室检定合格、但用于现场却不能达到预期计量性能效果的情况，使超声波流量计在现场能够得到更好的应用。     

生态平衡的伦理学意蕴解读

20世纪以来，人类采用技术工程治理、法律制裁和经济惩罚等措施，一定意义上改善了局部的生态环境，但是未能遏制住全球环境问题的恶化态势。生态危机的根本解决，关键在于人类自身必须进行深刻的利益观念和价值观念的变革。重新审视人与自然界的关系，对自然进行伦理关怀，寻求和建立以保护地球环境和人类生存与可持续发展的生态平衡理念。     

Study of hot air generator with quasi-uniform temperature using concentrated solar radiation: Influence of the shape parameters

The non-uniformity of the air temperatures and the slow flow rate at the plane collector exit constitute the main cause of the limitations of the solar drying systems. In order to obtain an uniform and a variable flow rate for different uses, a hot air generator using concentrated solar radiation is proposed. To improve the thermal efficiency of the generator, a study of the influence of different shape parameters is realized. The generator is simulated in the laboratory while investigating the flow induced by a circular disc heated uniformly by Joule effect at constant temperature. This disc is placed at the entrance of an open ended vertical cylinder of a larger diameter. Thermal radiation emitted by the hot disc heats the cylinder wall. The heating of the fluid at the cylinder-inlet generates a thermosiphon flow around the one created by the hot disc. The comparison of the velocity and the temperature profiles of the resulting flow permits to determine the influence of the cylinder height, the vertical source-cylinder spacing and the radius ratio, on the resulting flow at the system exit. Thus, a judicious choice of the shape parameters entails an improvement of the flow rate as well as the thermal flux absorbed by the air and a good homogenization of the air temperature at the generator exit.     

库车坳陷北带断裂输导天然气效率评价

在断裂输导天然气能力影响因素分析基础上,建立了断裂输导天然气能力评价参数.利用此评价参数对中国24个以断裂为主要输导通道的大中型气田断裂输导天然气能力进行了研究,并通过其天然气聚集效率和断裂输导天然气能力评价参数之间的关系研究得到:高效、中效和低效断裂输导天然气能力评价参数值应分别为大于250×10-4、250×10-4～25×10-4和小于25×10-4.根据库车坳陷北带断裂输导特征,对其下白垩统顶部断裂输导天然气效率进行了研究,得到库车坳陷北带下白垩统顶部高效断裂输导天然气区主要分布在大北1井周围、克拉1、2、3、4井周围和东秋5井-迪那2-依南2井周围3个地区,中、低效断裂输导天然气区围绕高效断裂输导天然气区分布.目前在该区发现的5个气田皆分布在高效断裂输导天然气分布区,表明高效断裂输导应是库车坳陷北带天然气成藏的重要条件.     

Effect of surfactants and liquid hydrocarbons on gas hydrate formation rate and storage capacity

Hydrate formation rate plays an important role in making hydrates for the storage and transport of natural gas. Micellar surfactant solutions were found to increase gas hydrate formation rate and storage capacity. With the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation reduced. Surfactants (an anionic surfactant, a non‐ionic surfactant and their mixtures) and liquid hydrocarbons (cyclopentane and methylcyclohexane) were used to improve hydrate formation. The experiments of hydrate formation were carried out in the pressure range 3.69–6.82 MPa and the temperature range 274.05–277.55 K. The experimental pressures were kept constant during hydrate formation in each experimental run. The effect of anionic surfactant (sodium dodecyl sulphate (SDS)) on natural gas storage in hydrates is more pronounced compared to a non‐ionic surfactant (dodecyl polysaccharide glycoside (DPG)). The induction time of hydrate formation was reduced with the presence of cyclopentane (CP). Cyclopentane and methylcyclohexane (MCH) could increase hydrate formation rate, but reduced hydrate storage capacity The higher methylcyclohexane concentration, the lower the hydrate storage capacity. Copyright © 2003 John Wiley & Sons, Ltd.     

Preparation and Properties of Rare Earth Modified Carbon Black/Natural Rubber Composites

The oxides Eu, Ho, Er and Dy were used to prepare the hydroxides of rare earth modified carbon black. Then natural rubber latex （NRL） was added into the reactor. The system reacted at 85 ℃ with stirring for 1 h to prepare powdered HAF-Ln（OH）3/NR composites. The effects of the kind and content of Ln on the particle size distribution of P [ NR/HAF-Ln （OH）3 ] and mechanical properties of its vulcanizate were studied respectively. It is found that rare earth can help to get the powder of the composite, the product particle with a diameter less than 0.9mm will be get when the composites containing the compound of Ho, Er and Dy with dosage of 1.0, 1.0, O. 5 percent, respectively. The adding of Ln can improve the tensile strength and tear strength of the vulcanizate effectively, what＇s more, Er and Dy can decrease the permanent set of vulcanizate significantly. The SEM studies shows that P[ NR/HAF-Dy （OH）3 ] vulcanizate shows superior mechanical properties that depend primarily on the absence of free carbon black, the fine dispersion of carbon black in the rubber matrix and better polymer-filler interaction.     

Performance of natural‐fiber–plastic composites under stress for outdoor applications: Effect of moisture,temperature, and ultraviolet light exposure

The effects of moisture, temperature, and ultraviolet (UV) light on performance of natural‐fiber–plastic composites (NFPC) were assessed. We conducted short‐term tests in the laboratory and long‐term tests under natural exposure and measured changes in mechanical properties and color in samples of the composite. Chemical changes of the composite's materials were measured by X‐ray photoelectron spectroscopy to elucidate the mechanisms of chemical transformations on the material surface. Relative humidity highly affected the modulus of rupture (MOR) and the modulus of elasticity (MOE), and had a greater effect than temperature and UV exposure on performance of the composite. The lightness of the composite was increased by the UV effect in the short‐ and the long‐term tests. The X‐ray photoelectron spectroscopy (XPS) analysis suggested that the composite was protected by the UV absorber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2570–2577, 2006     

天然气管网输配气量优化研究

天然气管网系统管理部门为了明确天然气管网的输气能力和提高天然气管网的利用率，需要对天然气管网系统的输配气量进行优化。为此，以天然气管网系统的最大流量为目标函数，同时考虑了管道强度、节点压力和流量限制等约束条件，建立了天然气管网输配气量优化的数学模型。在研究遗传算法和模拟退火算法的基础上，提出了一种由二者结合构成的具有全域搜索、快速收敛和鲁棒性强等特点的混合遗传算法。结合实例，采用这一新算法求解了天然气管网输配气量优化的数学模型。实例优化结果表明，所建立的数学模型和采用的混合遗传算法是可行和有效的，能够对天然气管网系统输配气量的调度运行起到指导作用。     

关于从旋涡炉渣回收铜的研究

介绍了用自然澄清法降低、回收旋涡炉渣中的铜的方法。该方法工艺简单。操作方便，不仅降低冶炼成本，同时提高了经济效益。