Implementation of Sobol’s Method of Global Sensitivity Analysis to a Compressor Simulation Model

Most simulation models are complex and nonlinear and so global sensitivity analysis is becoming a popular choice to predict the performance characteristics and behavior of the model. Global sensitivity analysis methods are generally variance-based methods that greatly rely on sampling methods and input parameter distribution. These methods don’t rely on linearity or monotonicity of the model and can be applied to a diverse range of problem. Sobol’s method—a variance based global sensitivity analysis method is applied to a nonlinear function to highlight and outline the implementation details of the method. It is used to calculate the sensitivities of the input parameter on the model output. The method is then applied to a reciprocating compressor model to determine the sensitivity of gas pulsation to suction manifold design parameters, namely radius, width and depth. The same method can be readily applied to any compressor simulation model

Global Sensitivity Analysis of a Multi-Cylinder Automotive Reciprocating Compressor

The objective of this paper is to perform sensitivity analysis of a compressor simulation model using a global sensitivity analysis method. In this paper, Sobol’s method of global sensitivity analysis, which is based on decomposition of variance, is applied to a compressor simulation model. A previously developed and tested compressor simulation model is used to perform sensitivity analysis of gas pulsations in the suction manifold of a multicylinder reciprocating compressor. The focus of the research is to determine the sensitivity of gas pulsations in the suction manifold of the compressor to three design parameters, namely, radius, width and depth of the suction manifold. Sobol’s method of global sensitivity analysis was used to calculate the first order effect and total effect of the suction manifold radius, width and depth on the manifold pressure response. It was also showed that suction manifold pressure response was most sensitive to changes in manifold radius, followed by manifold width and depth. This method of sensitivity analysis can be readily extended to any compressor simulation model

Design Optimization of the Suction Manifold of a Reciprocating Compressor Using Sensitivity Analysis

A new method for the design of the suction manifold of a reciprocating compressor using sensitivity and uncertainty methods was used. The objective was to pick the optimal values of the compressor suction manifold to minimize gas pulsations. The advantage of the method is that the input parameters do not have fixed values but a range is provided. Similarly, the output is specified in terms of a probability density function. Another advantage of this method is that we can set our limit on the maximum values of the gas pulsation that are permissible and then vary the input parameters so that all the gas pulsations are within the acceptable limits. This method also provides a way to compare gas pulsation level at different cylinder locations and how variations in an input parameter affect the gas pulsations at different locations

Percutaneous Non-Stenting Approach for Distal Simultaneous Multivessel Acute Coronary Occlusions

The occurrence of distal coronary lesions causing simultaneous occlusion of two coronary arteries in the setting of ST elevation myocardial infarction is a rare occurrence. This can occur due to simultaneous plaque rupture at more than one site or embolisation in coronary arteries. We describe a case of a middle-aged man who presented with acute inferoposterior lateral wall ST elevation myocardial infarction with simultaneous occlusion of distal left anterior descending artery and distal left circumflex artery on angiogram. The patient was treated with intracoronary streptokinase, followed by glycoprotein (GP) IIb/IIIa inhibitor and Factor X inhibitor (Rivaroxaban) with full resolution of flow in the distal vessels. Thus, coronary lesions, not amenable to stenting, can be dealt percutaneously, using a combination of old and newer pharmacological agents without stenting

A Spill over Relationship - Corporate Governance and Investor Reaction: A Case of Karachi Stock Exchange

The current study aims to investigate the relation of corporate governance with reaction of investor towards investment. The sample of the study contains on 114 companies of manufacturing sectors specifically and sample is acquired from (2004-2013). Thus, single and composite correlation is applied to check relationship of variables. Moreover, univariate and multivariate both regression methods are applied and study concluded negative insignificant relationship of variables of study. Keywords: Corporate Governance, Investor Reaction, Univariate, Multivariate, Composite

Outcomes of Left Main Percutaneous Coronary Intervention

Objective: To study the outcomes of left main percutaneous coronary artery (LMCA) revascularisation. Study Design: A descriptive study. Place and Duration of Study: The Aga Khan University Hospital (AKUH), Karachi, from February till July 2016. Methodology: The study included all adult patients aged 18 years or more, who underwent percutaneous LMCA revascularisation at study centre from April 2006 till April 2015. In-hospital outcomes were ascertained of patients via charts along with telephonic follow-up for outcome ascertainment at 1-year and 5-year. Results were expressed in terms of means and standard deviation for quantitative variables and percentages for qualitative variables. Results: Of the 86 patients, the mean age was 66.05 ±12.6 years and 69% (59 cases, n=86) of them were males. Sixteen (18.6%) patients presented with cardiogenic shock and 17.4% (15 cases, n=86) required mechanical ventilation upon arrival. Among the 86 patients, 23.3% (20 patients, n=86) underwent PCI because of unstable condition for CABG and refusal by the surgeons. Mean follow up time for participants was 40.5 ±25.7 months with mean length of hospital stay of 4.36 ±2.4 days. In-hospital mortality was 12.8%, while mortality at 1-year and at mean follow-up was 7.3% and 6.9%, respectively. Conclusion: LM percutaneous coronary intervention is a viable option for patients who are hemodynamicaly unstable and require urgent revascularisation or for patients denying bypass surgery due to other reasons in Pakistan. Prospective studies in future may be required to evaluate the role of PCI for LM lesions in elective setting in contrast to existing treatment options

Gamma Radiolytic Degradation of 4-Chlorophenol Determination of Degraded Products with HPLC and GC-MS

Contamination by chlorophenols of surface water and groundwater is an emerging issue in environmental science and engineering. After their usage as pesticide, herbicide and disinfectant, these organic compounds subsequently enter the aquatic environment through a number of routes. Some of the chlorophenols are slightly biodegradable, while others are more persistent and mobile in the aquatic environment especially chlorophenols. Gamma radiolytic degradation is one of advance oxidation process that has been thought to be one of the promising treatments to deal with this problem. This radiolytic study was carried out in methanolic 4-CP (4-chlorophenol) samples. Among several factors effecting radiolytic degradation of 4-CP, dose and concentration are important that were evaluated under atmospheric conditions. A degradation yield (G –value) for 4-CP of 0.38 and 1.35 was achieved in 20 and 100mg/dm3 solution. It was observed that degradation yield decreases with increasing 4-CP concentration. Gamma radiolysis produce free radicals in solvent which further react with 4-CP molecules to generate different products. The identification of degradation products was proposed using HPLC and GC-MS

Using Carbon Capture and Storage CCS Techniques in Mulla Abdulla and Taza Power Plants to Mitigate the Impact of Climate Change

In the IPCC Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (SRES), it was projected that the number of CO2 emission sources from the electric power and industrial sectors will increase significantly until 2050. Because fossil fuel-fired power plants are responsible for around one-third of total global CO2 emissions, they are prime candidates for the application of CO2 capture and storage techniques. The aim of this work is to mitigate the impact of climate change by reducing the amount of CO2 emitted to the atmosphere in Mulla Abdulla and Taza power plants in Kirkuk/ Iraq using CCS techniques, and to calculate the cost of the system components