128 research outputs found
Effect of Antioxidants on the Outcome of Therapy in Paraquat-intoxicated Patients
Purpose: The present study was conducted to determine the effect of vitamins C and E administration on the outcome of therapy in patients with paraquat intoxication admitted in the Poisoning EmergencyDepartment (PED) of Noor Teaching General Hospital, Isfahan, Iran.Methods: We studied retrospectively medical records of 186 patients admitted to the PED in two different study periods: 157 patients were evaluated from 1985 to 2001 (first study period) in which patients received conventional treatment protocol consisting of fluid replacement, oral absorbents, haemodialysis, etc, Also, 29 other patients were assessed from 2001 to 2005 (second study period) in which vitamins C and E had been administered to the patients, in addition to the conventional protocol.The patients' mortality rate after the first study period was compared to that of the second one, with regard to the impact of the additional therapeutic intervention (use of antioxidant vitamins).Results: Most of the patients (40.5 %) had ingested more than 20 mL of 20 % paraquat solution and were admitted to the hospital during the first 4 h after exposure. Paraquat poisoning was more common in men (76.6 %), young adults in the age group 19 - 34 (47 %) and during summer (43.3 %). Mean (± SE) length of hospital stay was 62.6 ± 15.6 h. Overall mortality rates were 31 and 55.2 % in the first and second periods, respectively.Conclusion: Although the addition of antioxidants (vitamins C and E) to the conventional therapy did not reduce the mortality rate, other dependent variables including different doses of antioxidants may beconsidered for future studies
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Geothermal reservoir management
The optimal management of a hot water geothermal reservoir was considered. The physical system investigated includes a three-dimensional aquifer from which hot water is pumped and circulated through a heat exchanger. Heat removed from the geothermal fluid is transferred to a building complex or other facility for space heating. After passing through the heat exchanger, the (now cooled) geothermal fluid is reinjected into the aquifer. This cools the reservoir at a rate predicted by an expression relating pumping rate, time, and production hole temperature. The economic model proposed in the study maximizes discounted value of energy transferred across the heat exchanger minus the discounted cost of wells, equipment, and pumping energy. The real value of energy is assumed to increase at r percent per year. A major decision variable is the production or pumping rate (which is constant over the project life). Other decision variables in this optimization are production timing, reinjection temperature, and the economic life of the reservoir at the selected pumping rate. Results show that waiting time to production and production life increases as r increases and decreases as the discount rate increases. Production rate decreases as r increases and increases as the discount rate increases. The optimal injection temperature is very close to the temperature of the steam produced on the other side of the heat exchanger, and is virtually independent of r and the discount rate. Sensitivity of the decision variables to geohydrological parameters was also investigated. Initial aquifer temperature and permeability have a major influence on these variables, although aquifer porosity is of less importance. A penalty was considered for production delay after the lease is granted
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Modeling the Risks of Geothermal Development
Geothermal energy has emerged as a promising energy source in recent years and has received serious attention from developers and potential users. Despite the advantages of this resource, such as potential cost competitiveness, reliability, public acceptance, etc., the commercial development and use of geothermal energy has been slow. Impediments to the development of this resource include technical, financial, environmental and regulatory uncertainties. Since geothermal power is unique in that the generation facility is tied to a single fuel at a single site, these uncertainties are of particular concern to utility companies. The areas of uncertainty and potential risks are well known. This paper presents a method for quantifying the relevant uncertainties and a framework for aggregating the risks through the use of submodels. The objective submodels can be combined with subjective probabilities (when sufficient data is not available) to yield a probability distribution over a single criterion (levelized busbar cost) that can be used to compare the desirability of geothermal power development with respect to other alternatives
Detecting False Data Injection Attacks in Linear Parameter Varying Cyber-Physical Systems
In this paper, we investigate the process of detection of False Data Injection (FDI) in a Linear Parameter Varying (LPV) cyber-physical system (CPS). We design a model based FDI detector capable of detecting false data injections on output measurements and scheduling variables. To improve the detection accuracy of FDI attacks, the attack detector design uses the performance metric H- to maximize the detection capability of the detector module to effectively detect FDI attacks. On the other hand, it uses the H? metric to minimize the effect of disturbance on the detector module given an unreliable network. We assume that the network unreliability comes from packet dropout that we modeled as Bernoulli process. The FDI attack detector is designed such that H- and H? performance metrics are maintained despite packet dropout. Based on stochastic stability, we define a set of sufficient Linear Matrix Inequalities (LMI) that we solve as a multi-objective optimization problem to obtain the detector gain. The obtained detector gain is used for estimating the current system state and current output measurement using the system input, manipulated measurements and manipulated scheduling variables. Then, the output of the detector is compared with the actual sensor measurement. The resulting residual signal carries the information about the FDI attack. The proposed approach is tested and validated on a two-tank system. The evaluation results demonstrate that the proposed detector is able to detect FDI attacks. - 2019 IEEE.This work was made possible by NPRP grant # NPRP9-005-1-002 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu
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