1,112 research outputs found

    The atmospheres of mars, venus and jupiter

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    Planetary atmosphere composition, temperature, and pressure of Mars, Venus, and Jupite

    Results of the Mariner 6 and 7 Mars occultation experiments

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    Final profiles of temperature, pressure, and electron density on Mars were obtained for the Mariner 6 and 7 entry and exit cases, and results are presented for both the lower atmosphere and ionosphere. The results of an analysis of the systematic and formal errors introduced at each stage of the data-reduction process are also included. At all four occulation points, the lapse rate of temperature was subdadiabatic up to altitudes in excess of 20 km. A pronounced temperature inversion was present above the surface at the Mariner 6 exit point. All four profiles exhibit a sharp, superadiabatic drop in temperature at high altitudes, with temperatures falling below the frost point of CO2. These results give a strong indication of frozen CO2 in the middle atmosphere of Mars

    Emergence of hexatic and long-range herringbone order in two-dimensional smectic liquid crystals : A Monte Carlo study

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    Using a high resolution Monte Carlo simulation technique based on multi-histogram method and cluster-algorithm, we have investigated critical properties of a coupled XY model, consists of a six-fold symmetric hexatic and a three-fold symmetric herringbone field, in two dimensions. The simulation results demonstrate a series of novel continues transitions, in which both long-range hexatic and herringbone orderings are established simultaneously. It is found that the specific-heat anomaly exponents for some regions in coupling constants space are in excellent agreement with the experimentally measured exponents extracted from heat-capacity data near the smecticA-hexaticB transition of two-layer free standing film

    Towards the Application of Uncertainty Analysis in Architectural Design Decision-Making

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    To this day, proper handling of uncertainties -including unknown variables in primary stages of a design, an actual climate data, occupants` behavior, and degradation of material properties over the time- remains as a primary challenge in an architectural design decision-making process. For many years, conventional methods based on the architects' intuition have been used as a standard approach dealing with uncertainties and estimating the resulting errors. However, with buildings reaching great complexity in both their design and material selections, conventional approaches come short to account for ever-existing but unpredictable uncertainties and prove incapable of meeting the growing demand for precise and reliable predictions. This study aims to develop a probability-based framework and associated prototypes to employ uncertainty analysis and sensitivity analysis in architectural design decision-making. The current research explores an advanced physical model for thermal energy exchange characteristics of a hypothetical building and uses it as a test case to demonstrate the proposed probability-based analysis framework. The proposed framework provides a means to employ uncertainty and sensitivity analysis to improve reliability and effectiveness in a buildings design decision-making process

    Fungal infections in patients with chronic liver disease: mortality and associated risk factors

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    Background: Patients with chronic liver disease are immunocompromised and prone to different opportunistic infections. Fungal infections in patients admitted with liver cirrhosis are not rare and they may increase mortality and morbidity of these patients. Aims of the study is to determine the mortality and its risk factors associated with fungal infections in patients with chronic liver disease.Methods: In this retrospective study, patients admitted with chronic liver disease during the last four years on this hospital were studied for diagnosed fungal infections. A matched control group of cirrhosis patients with a ratio of 1:2 admitted without fungal infections was also studied and mortality was compared between the two groups.Results: Seventy admitted patients of liver cirrhosis with microbial and histopathological evidence of fungal infection were found while 140 patients of the control group had no evidence of fungal infection. Hepatitis C virus infection was the major cause of cirrhosis (65%) and most of the patients were in child class C(63%). Urinary tract infection, esophageal candidiasis, and mucormycosis were major fungal infections. Mortality was much higher in the fungal infections group (34.3%) as compared to the non-infectious group (16%). On multivariate analysis, high WBCs count, hypo-albuminemia and high creatinine levels were the worst factors affecting mortality.Conclusions: Fungal infections are a significant cause of morbidity and mortality in patients with decompensated cirrhosis. Advanced cirrhosis, renal insufficiency, and leucocytosis are independent predictors of fatal outcome in these patients

    Experimental Study of PV Panel Performance Using Backside Water Cooling Chamber

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    Received: 10 December 2022. Accepted: 28 March 2023.The authors would like to express their appreciation to the staff of the research center laboratory at Erbil Polytechnic University, Erbil, Iraq.Due to high solar irradiation and the high ambient temperature in Iraq, the solar cell temperature rises, and the electrical power output drops accordingly. In this study, an experimental photovoltaic (PV) panel prototype was developed to study the PV module's performance and power production efficiency. The developed photovoltaic module uses a water-cooling chamber for cooling. This experimental study uses a water-cooling system chamber technique at the rear side of the PV panel. The cooling system solar panel is a closed cycle, and the cooling water contacts the panel directly through the rear side of the PV panel using different flow rates. The results showed that the electrical efficiency increased by 10.42%, 11.87%, 13.77%, 18.1%, and 19.72% when mass flow rates of 1.5, 2, 2.5, 3, and 3.5 l/min, respectively, were used. The thermal efficiency at 1.5 and 3.5 l/min is 49.7% and 79.2%, respectively

    Intrusion Detection Systems in Cloud Computing: A Contemporary Review of Techniques and Solutions

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    Rapid growth of resources and escalating cost of infrastructure is leading organizations to adopt cloud computing. Cloud computing provides high performance, efficient utilization, and on-demand availability of resources. However, the cloud environment is vulnerable to different kinds of intrusion attacks which involve installing malicious software and creating backdoors. In a cloud environment, where businesses have hosted important and critical data, the security of underlying technologies becomes crucial. To mitigate the threat to cloud environments, Intrusion Detection Systems (IDS) are a layer of defense. The aim of this survey paper is to review IDS techniques proposed for the cloud. To achieve this objective, the first step is defining the limitations and unique characteristics of each technique. The second step is establishing the criteria to evaluate IDS architectures. In this paper, the criteria used is derived from basic characteristics of cloud. Next step is a comparative analysis of various existing intrusion detection techniques against the criteria. The last step is on the discussion of drawbacks and open issues, comprehended from the evaluation, due to which implementation of IDS in cloud environment face hurdles

    Influence of shock wave propagation on dielectric barrier discharge plasma actuator performance

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    Interest in plasma actuators as active flow control devices is growing rapidly due to their lack of mechanical parts, light weight and high response frequency. Although the flow induced by these actuators has received much attention, the effect that the external flow has on the performance of the actuator itself must also be considered, especially the influence of unsteady high-speed flows which are fast becoming a norm in the operating flight envelopes. The primary objective of this study is to examine the characteristics of a dielectric barrier discharge (DBD) plasma actuator when exposed to an unsteady flow generated by a shock tube. This type of flow, which is often used in different studies, contains a range of flow regimes from sudden pressure and density changes to relatively uniform high-speed flow regions. A small circular shock tube is employed along with the schlieren photography technique to visualize the flow. The voltage and current traces of the plasma actuator are monitored throughout, and using the well-established shock tube theory the change in the actuator characteristics are related to the physical processes which occur inside the shock tube. The results show that not only is the shear layer outside of the shock tube affected by the plasma but the passage of the shock front and high-speed flow behind it also greatly influences the properties of the plasma
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