The accidental risk assessment methodology for industries (ARAMIS)/layer of protection analysis (LOPA) methodology: A step forward towards convergent practices in risk assessment?

In the last ten years, layer of protection analysis (LOPA) emerged as a simplified form of quantitative risk assessment (QRA). The European Commission funded project Accidental Risk Assessment Methodology for Industries in the context of the Seveso 2 Directive (ARAMIS) has recently been completed. ARAMIS has several modules which give a consistent simplified approach to risk assessment which does not approach the complexity or expense of full QRA. LOPA is potentially a means of carrying out the assessment of barriers required in ARAMIS. This paper attempts to explain the principles of LOPA and the means by which it can be used within ARAMIS.     

Localised corrosion of carbon steel in NaHCO3/NaCl electrolytes: role of Fe(II)-containing compounds

Pitting corrosion processes of carbon steels in 0.1 M NaHCO₃ + NaCl aqueous solutions induce rapidly the precipitation of Fe(II)-containing phases. The mechanisms leading to those transient compounds were studied by coupling classical electrochemical methods (cyclic voltammetry, chronoamperometry) with electrochemical microprobes and analyses by micro-Raman spectroscopy. Anodic polarisation above the breakdown potential induces the formation of a white corrosion product, identified as iron carbonate by Raman spectroscopy. The activity of a given pit, followed by Scanning Vibrating Electrode Technique, reaches a maximum before to decrease, in agreement with the evolution of the overall current density that stabilises whereas the number of pits increases. Iron carbonate is oxidised by dissolved O₂ into the hydroxycarbonate Green Rust. The study of the oxidation of aqueous suspensions of Fe(II) compounds precipitated from FeCl₂ · 4H₂O, NaOH and NaHCO₃ solutions allowed to clarify the mechanisms, that are governed by the concentration ratios and . The results were confronted to a thermodynamic approach.     

重复压裂选井选层分析方法

文章不仅选择了重复压裂选井选层的影响因素,而且通过因子分析法对影响因素进行分析,用几个主因子来代替所有影响因素的信息,从而达到了降维、简化数据的作用。而通过因子解释将影响因素归类分析,能够更加明确影响因素与评价指标之间的关系。同时,提出以压后日增油量为压裂效果评价标准,运用改进的BP神经网络方法建立了预测模型、评价方法,克服了由于人的主观因素等方面的不足,达到了很好的效果。并通过实例分析验证了该分析方法的可行性,对现场采取压裂措施有一定的指导意义。     

钢筋阻锈剂阻锈效果的评价

通过半电池电位测量、动电位扫描、恒电位极化等电化学方法和冷热干湿实验评价了自制HP钢筋阻锈剂的阻锈效果,并探讨了其耐蚀机理。实验结果表明,HP阻锈剂是一种阳极型阻锈剂,它通过提高钢筋的半电池电位,促进阳极极化而改善钢筋的耐蚀性能。这种阻锈剂性能稳定,受环境介质变化影响小,对钢筋基体具有良好的保护作用。几种评价方法在实验结果上具有基本规律的一致性,能正确评价钢筋阻锈剂的阻锈效果。     

Microstructure of Gas Diffusion Layers for PEM Fuel Cells

The gas diffusion layer (GDL) is a critical component of a proton exchange membrane fuel cell, and can play a key role in fuel cell performance. In order to design reliable and durable fuel cells, knowledge of the GDL microstructure is necessary. Currently, characterization of GDLs is generally based on porosity measurements to obtain a pore size distribution. However, the pore size distribution in GDLs may not be the only factor that affects the fuel cell performance. Additional microstructural characterization of GDLs manufactured by three different vendors (Toray, SGL, and Freudenberg) has been investigated. In addition to the pore size distribution, other statistical information of GDL microstructure including size, shape, orientation, and distribution of pores have been characterized and compared. Among these GDLs, the Freudenberg sample was found to have the smallest pore size and orientation analysis indicated that the pores were randomly distributed. Pore roundness was the lowest and pore clustering was highest in Toray sample. The effect of threshold setting on pore size data was also studied and found to have negligible influence on the calculated distributions. The microstructures of the GDLs were reconstructed in three‐dimension using computer simulations and good agreement with the two‐dimensional image analysis data was observed. The present work opens new opportunities for experimentalists and modelers in the area of fuel cell research to take into account the statistical characteristics of GDL microstructure.     

桩-网结构路基加筋垫层设计研究

加筋垫层的设计对于桩-网结构路基来说至关重要,而确定土工格栅的强度又是加筋垫层的设计重点。现结合遂渝线土质路基上修建的无碴轨道综合试验成果,对桩-网结构路基加筋垫层设计进行深入的探讨,为类似工程设计提供参考。     

弱碱三元复合驱采出液结垢特性及表面纳米化阻垢研究

通过现场采集垢样,采用扫描电镜（SEM）、能谱仪（EDS）、X射线衍射（XRD）等微观测试技术对垢样的成分、表面形貌进行测试分析,判断其成垢过程及成垢物质,初步分析结垢原因。采用纳米复合化学镀和纳米复合电镀两种方法对材料进行表面纳米化处理,研究经表面纳米化后材料的阻垢性能．并对其阻垢机理进行初步探讨,为表面纳米化在弱碱三元复合驱阻垢方面的应用提供了科学依据。     

Performance of IT‐SOFC with Ce0.9Gd0.1O1.95 Functional Layer at the Interface of Ce0.9Gd0.1O1.95 Electrolyte and Ni‐Ce0.9Gd0.1O1.95 Anode

In this paper we present results for a high power density IT‐SOFC and a method for dispersing nanosized Ce_0.9Gd_0.1O_1.95 (GDC) particles at the GDC electrolyte and Ni‐GDC anode interface. Dispersed nanosized particles were deposited to form an anode functional layer (AFL). Anode supports were prepared by tape casting of large micron‐sized NiO powder and sub micron‐sized GDC powder without pore former. For the cathode a La_0.6Sr_0.4Co_0.2Fe_0.8O_{3 – δ} (LSCF)‐GDC composite was used. Without an AFL the open circuit potential (OCP) and the maximum power density were 0.677 V and 407 mW cm^–2, respectively, at 650 °C using 30 sccm of hydrogen and air flow‐rate. With an AFL the OCP and the maximum power density increased to 0.796 V and 994 mW cm^–2, respectively, at the same temperature. Two point probe impedance measurements revealed that the AFL fabricated by the proposed method not only increased the OCP but also reduced the electrode polarisation by 68%. The effect of gas flow‐rate is also present in this paper. When hydrogen and air flow‐rate is increased to 90 sccm, the sample with AFL obtained 1.57 W cm^–2 at 650 °C.     

Micro Videographic Analysis of the Melt Layer of Self‐Deflagrating HMX and RDX

Micro videographic analysis of the thin molten layer on the surface of HMX (Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) and RDX (Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) during self deflagration were performed. This was done to gain a better understanding of the physical structure present in this 100–300 μm layer and give a visual picture for the development of computational models. During steady‐state combustion, RDX had a consistent melt layer with vigorous bubble formation. There was a continuous liquid layer throughout combustion and no foam was formed. The surface of HMX during steady‐state combustion at ambient initial temperatures was an uneven layer of foam. Foam appeared to convect across the surface in undulating waves. At elevated initial temperatures, the HMX molten layer was a consistent foam layer in both time and space. Micro videography was also done with a diagnostic laser sheet as illumination to measure the melt layer thickness. The RDX bubbling layer was about 217±30 μm thick. The HMX foam thickness varied from almost nothing to 660 μm, with an average value of about 234±106 μm.     

增值业务运营管理的综合业务平台

综合业务平台可以很好地解决传统垂直化的业务管理系统给运营商在运营管理上所带来的诸多弊端。通过引入该平台,并将现网增值业务向该平台集成,能够为全业务运营商的业务网络转型和网络融合提供解决的途径。