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181.
This study investigates and compares five upstream petroleum fiscal systems under crude oil price uncertainty. The fiscal systems analyzed are: the Alberta Canada tax and royalty system, the Papua New Guinea (PNG) (pre-2003) traditional Rate of Return (ROR) system, the Sao Tome and Principe/Nigerian Joint Development Zone (SNJDZ) Production Sharing Contract (PSC), the Tanzanian PSC/ROR hybrid system and the Trinidad and Tobago PSC. Contingent claims analysis is used to value the governments’ tax claims under uncertainty using a numerical approach, viz., Monte Carlo simulation. Each system is tested to obtain the after-tax value accruing to firms as well as the distortionary effects introduced by the fiscal systems. The results are then ranked. The Alberta Canada and PNG fiscal systems provide companies with the highest after-tax values while also being the least distortionary. The Tanzanian system is the lowest in both rankings, providing relatively low after-tax values and introducing strong distortionary effects. The SNJDZ PSC imposed a relatively high tax burden on companies with median distortionary effects. The Trinidadian PSC generated a median tax burden on companies but has strong distortionary effects. 相似文献
182.
《Journal of Manufacturing Processes》2014,16(2):233-240
A thermo-mechanical model has been developed for modeling of hot extrusion processes. Accordingly, an admissible velocity field was first proposed by means of stream function method and then, extrusion pressure as well as temperature variations within the metal and the die were predicted employing a combined upper bound and Petrov–Galerkin finite element analysis. In order to evaluate the model predictions, hot extrusion of AA6061-10%SiCp was considered under both isothermal and non-isothermal conditions and the predicted force–displacement diagrams under various extrusion conditions were compared with the experimental ones and reasonable consistency was found between the two sets of results. 相似文献
183.
The natural, bio-degradable features and chemical constituents of the sugarcane bagasse (SCB) have been attracting attention as a highly potential and versatile ingredient in composite materials. Eco-friendly and low cost considerations have set the momentum for material science researchers to identify green materials that give low pollutant indexes. Various components of SCB is shown to possess the ability of being applied as raw material for manufacturing of composite materials at multiple levels of properties and performances. Studies on the impacts, performances and applications of SCB in its original condition; transformed forms; treated with appropriate chemicals and/or processes; in combination with materials of distinct properties and manipulation of manufacturing methodologies have been duly considered. This paper attempts to summarize a review of current literature on the extensive studies that have been undertaken in an attempt to explore plausible applications and potentials of SCB for composite material. 相似文献
184.
Capturing flue gases often require multiple stages of scrubbing, increasing the capital and operating costs. So far, no attempt has been made to study the absorption characteristics of all the three gases (NO, SO2 and CO2) in a single stage absorption unit at alkaline pH conditions. We have attempted to capture all the three gases with a single wet scrubbing column. The absorption of all three gases with sodium carbonate solution promoted with oxidizers was investigated in a tall absorption column. The absorbance was found to be 100% for CO2, 30% for NO and 95% for SO2 respectively. The capture efficiency of sodium carbonate solution was increased by 40% for CO2 loading, with the addition of oxidizer. Absorption kinetics and reaction pathways of all the three gases were discussed individually in detail. 相似文献
185.
Many utilities face conflicts between two goals: generating cost-efficient hydropower and protecting riverine fishes. Research to develop ecological simulation tools that can evaluate alternative mitigation strategies in terms of their benefits to fish populations is vital to informed decision-making. In this paper, we describe our approach to population viability analysis of riverine fishes in general and Snake River white sturgeon in particular. We are finding that the individual-based modeling approach used in previous in-stream flow applications is well suited to addressing questions about the viability of species of concern for several reasons. Chief among these are: (1) the ability to represent the effects of individual variation in life history characteristics on predicted population viability; (2) the flexibility needed to quantify the ecological benefits of alternative flow management options by representing spatial and temporal variation in flow and temperature; and (3) the flexibility needed to quantify the ecological benefits of non-flow related manipulations (i.e., passage, screening, and hatchery supplementation). 相似文献
186.
187.
CO2 utilizations are essential to curbing the greenhouse gas effect and managing the environmental pollutant in an energy-efficient and economically-sound manner.This paper seeks to critically analyze these technologies in the context of each other and highlight the most important utilization avenues available thus far.This review will introduce and analyze each major pathway,and discuss the overall applicability,potential extent,and major limitations of each of these pathways to util... 相似文献
188.
《Atmospheric Environment. Part A. General Topics》1990,24(9):2329-2347
Ten multi-hour atmospheric dispersion SF6 tracer experiments were conducted during October and November of 1987 near a large oil gathering facility in the Prudhoe Bay, Alaska, oilfield reservation. The purpose of this study was to investigate dispersion under arctic conditions and in situations where building-generated airflow disturbances dominate downwind distributions of ground level pollutant concentrations. This was accomplished with a network of micrometeorological instruments, portable syringe tracer samplers, continuous tracer analyzers, and infrared visualization of near source plume behavior.Atmospheric stability and wind speed profiles at this arctic site are influenced by the smooth (surface roughness = 0.03 cm), snow covered tundra surface which receives negligible levels of solar isolation in winter. The dispersion of pollutants emitted from sources within the oil gathering facility, however, is dominated by the influence of nearby buildings when high winds generate elevated ground level concentrations. An order of magnitude increase in maximum ground level concentration was observed as wind speeds increased from 5 to 8 m s−1 and another order of magnitude increase was observed as winds increased from 8 to 16 m s−1. Variation in maximum concentrations was also observed with changes in wind direction. Vertical plume diffusion (σz) near the buildings was a factor of 2–3 greater than that observed in open terrain and was dependent on both wind speed and the projected building width and location of nearby buildings. Wind tunnel tracer distributions for east winds agree with field observations but also indicate that a significant increase in plume downwash occurs with other wind directions. Concentration distributions were calculated using several versions of the Industrial Source Complex (ISC) model. Model estimates of ground level concentrations were within a factor of three depending on wind direction. The model predictions are extremely sensitive to the ratio of plume height to vertical plume diffusion which is significantly influenced by a complex aerodynamic wake in the field. 相似文献