Amine corrosion and amine cracking of API 5L X52 carbon steel in the presence of hydrogen sulphide and carbon dioxide

In this research, stress corrosion cracking (SCC) and corrosion behaviour of API 5L X52 carbon steel in 25?wt-% diethanolamine solution, saturated/unsaturated with carbon dioxide and containing 0 and 200?ppm hydrogen sulphide at different temperatures were investigated using slow strain rate test, electrochemical measurement and microscopic analysis. In addition, the presence of heat stable amine salts (HSASs) in the test solution was studied using spectrophotometry and Fourier transform infra-red spectroscopy. Analysis of the results showed that the primary components to form HSASs exist in the solution. The results indicated that SCC is more likely in solutions without amine. Increase in corrosion rate of carbon steel by increase in temperature was clearly observed and concluded that the simultaneous presence of hydrogen sulphide and carbon dioxide in the solution can increase the corrosion rate of carbon steel more than having one of the gases in the solution.     

Survey on location information services for Vehicular Communication Networks

Vehicular Communication Networks (VCNs) are used to supply a communication platform for Intelligent Transportation Systems services also for value added services in different road systems. In comparison to other communication networks, VCNs come with major challenges: high mobility and velocity of vehicles that cause rapidly change topology of network and fast change of vehicle’s locations. Location information services (LISs) or location management systems (LMSs) are used to provide location information about vehicles such as current location, speed, direction and report this information to other vehicles or network entities that require this information. We present a survey for LISs in VCNs and introduce 11 approaches in literature. Moreover, we present a classification for LISs and compare mentioned approaches based on our classification. Finally we evaluate studied LISs by some performance properties to measure their overall efficiency.     

Comparison of interwell connectivity predictions using percolation, geometrical, and Monte Carlo models

Reservoir connectivity is often an important consideration for reservoir management. For example, connectivity controls waterflood sweep efficiency and it affects decisions concerning well placement and spacing. The uncertainty of sandbody distributions, however, can make interwell connectivity prediction extremely difficult. Percolation models are a useful tool to simulate sandbody connectivity behavior to estimate interwell connectivity.This study applies a percolation method to estimate interwell connectivity. Using results derived by Andrade, King, and others for fluid travel time between locations in a percolation model, we develop a method to estimate interwell connectivity. Four parameters are needed to use this approach: the net-to-gross ratio p_sand, the typical sandbody size, reservoir length and well spacing. To evaluate this new percolation method, the results are compared to results from geometrical models, Monte Carlo, and reservoir simulation.These methods were applied to estimate interwell connectivity for three non-communicating stratigraphic intervals in Monument Butte oil field, Utah. The results suggest that the percolation method can estimate the probability of interwell connectivity reliably for thin intervals for any values of p_sand, well spacing, and reservoir length. The geometrical model also performs well, but can only be applied in fields where the well spacing is less than one-half of the sandbody size.The proposed method requires that the reservoir interval for evaluation be sufficiently thin so that 2D percolation results can be applied. For thick intervals or heterogeneous sandbody distributions, the percolation method developed here is not suitable because it assumes thin layers. Future percolation research will be needed to adapt this new method to 3D cases.     

Self-esteem stability and depressive symptoms in acute stroke rehabilitation: Methodological and conceptual expansion.

Objectives: Explore the relationship of self-esteem level, self-esteem stability, and other moderating variables with depressive symptoms in acute stroke rehabilitation. Measures: One hundred twenty participants completed measures of state self-esteem, perceived recovery, hospitalization-based hassles, impairment-related distress, and tendency to overgeneralize negative self-connotations of bad events. Self-report of depressive symptoms was collected at admission and on discharge. Four regression analyses explored the relationship of self-esteem level and stability and each of 4 moderating variables (perceived recovery, hassles, impairment-related distress, and overgeneralization) with depressive symptoms at discharge. Results: Analyses indicated significant 3-way interactions in the 4 regression models. In general, individuals with unstable high self-esteem endorsed greater depressive symptoms under conditions of vulnerability (e.g., lower perceived recovery) than did individuals with stable high self-esteem. Under conditions of vulnerability, participants with stable low self-esteem indicated the highest levels of depressive symptoms. Implications: Self-esteem level and stability interact with psychological, environmental, and stroke-specific variables to predict depressive symptoms at discharge from stroke rehabilitation. This suggests the viability of self-esteem stability in exploring depressive symptoms in this setting and the complexity of emotional adjustment early after stroke. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nanoscale vibration analysis of embedded multi-layered graphene sheets under various boundary conditions

The present article deals with the vibrational analysis of multi-layered graphene sheets with different boundary conditions amongst sheets. An elastic multiple-plate model is utilized in which the nested plates are coupled with each other through the van der Waals interlayer force. The interaction of van der Waals forces between adjacent and non-adjacent layers and the reaction from the surrounding media are included in the Reissner–Mindlin-type field equations on which the theoretical formulation is based. The set of coupled equations of motion for the multi-layered graphene sheets is then solved by the generalized differential quadrature method. The numerical analysis presented herein provides the possibility of considering various combinations of layerwise boundary conditions in a multi-layered graphene sheet. Based on exact solution, explicit formulas for the frequencies of a double-layered graphene sheet with all edges simply supported are also obtained. The results of the present numerical solution are shown to be in excellent agreement with those of exact solution for simply supported graphene sheets.     

Terrorist targeting and energy security

Sudden, short-term disruptions seriously endangering energy security can be triggered by a variety of events—among them attacks by terrorists. This study investigates terrorist attack practices against energy infrastructures and discusses how we may understand them. Our results indicate that attacks against energy infrastructures are comparatively few. Also, we find no strong connection between the ideologies of various terrorist groups and their proclivity to attack. In addition, the highly disproportionate number of attacks in a handful of countries highlights the strong geographic concentration of attacks. To explain these findings, we analyze terrorist targeting incentives including intimidation levels, symbolism, attack feasibility, and concerns for stakeholders. We argue that terrorists in general have comparatively few incentives to attack energy supply infrastructures based on our assessment of these factors. Moreover, higher levels of terrorist incidents in states more prone to internal violent conflict may suggest stronger incentives to attack energy infrastructures. When outlining energy security policies, the low frequency of worldwide attacks coupled with the high concentration of attacks in certain unstable countries should be taken into consideration. Energy importing countries could benefit from developing strategies to increase stability in key energy supply and/or transit countries facing risks of internal instability.     

An Experimental Investigation of Parameters Affecting Oil Recovery Efficiency Alteration during a Microbially Aided Water Flooding Process

Abstract

In order to evaluate the potential of microbial recovery in the Iranian Maroon oilfield, laboratory core flood tests were designed and conducted. The effect of biosurfactant production on the recovery of crude oil during waterflooding and the effect of bioproducts on wettability alteration of the cores was investigated. Three different kinds of microbes in two different kinds of growth media as nutrient media were studied. The results showed that the oil recovery was affected by adjustment time, source of carbon, type of microorganism, phosphorus and nitrogen quantity, and salt concentration. In addition, it was found that there are optimum values of adjustment time, phosphorus and nitrogen quantity, and salt concentration that maximize the oil recovery factor. The results of this work can be helpful for designing and developing successful microbial-enhanced oil recovery (MEOR) operations.     

Characterization of film-coated aerosol canisters using electrochemical impedance spectroscopy

Drug adhesion to the walls of an aerosol canister can be prevented/reduced by coating the canister with a hydrophobic polymer (e.g., a fluoropolymer). In this study, three batches of fluoropolymer-coated canisters were investigated by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The EIS technique showed that only one of the batches presented as a monolithic, non-porous film. The other two batches were either partially porous or highly porous. Scanning electron micrographs showed evidence of cracks, within the films, but could not alone establish the porous nature of these defects. For the non-porous and partly porous films it was possible to use the EIS data to determine the approximate film thickness. Estimates of 2-4 µm were obtained for the mean film thickness. These values compared favorably with micrometer estimates obtained following acid dissolution of the aluminum canister. It remains to be seen whether the properties of the films (i.e., the porosity and film thickness, determined by EIS) translate to differences in drug adhesion. Nevertheless, the EIS technique was shown to be a powerful, non-destructive method that lends itself to the rapid analysis of batch-to-batch variation in film-coated canisters.