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Gera Bhuvaneshwar,Verma Vishnu,Chattopadhyay Jayanta 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9
In water-cooled power reactor, hydrogen is generated in case of steam zirconium reaction during severe accident condition and later on in addition to hydrogen; CO is also generated during molten corium concrete interaction after reactor pressure vessel failure. Passive Autocatalytic Recombiners (PARs) are provided in the containment for hydrogen management. The performance of the PARs in presence of hydrogen and carbon monoxide along with air has been evaluated. Depending on the conditions, CO may either react with oxygen to form carbon dioxide (CO2) or act as catalyst poison, reducing the catalyst activity and hence the hydrogen conversion efficiency. CFD analysis has been carried out to determine the effect of CO on catalyst plate temperature for 2 & 4% v/v H2 and 1e4% v/v CO with air at the recombiner inlet for a reported experiment. The results of CFD simulations have been compared with the reported experimental data for the model validation. The reaction at the recombiner plate is modelled based on diffusion theory. The developed CFD model has been used to predict the maximum catalyst temperature and outlet species concentration for different inlet velocity and temperatures of the mixture gas. The obtained results were used to fit a correlation for obtaining removal rate of carbon monoxide inside PAR as a function of inlet velocity and concentrations
A novel framework to improve the performance of crowdfunding platforms
Jaya Gera,Harmeet Kaur 한국통신학회 2018 ICT Express Vol.4 No.2
This work presents a framework for evaluating and promoting campaigns that are launched over a crowdfunding platform. Campaigns are evaluated on the basis of campaign features and pledge performance. To promote a campaign, a recommender model is designed that filters campaigns to be promoted using association rule mining and based on backer’s interests. Framework also assesses creators’ using their past records and their profile text. This system deals with the issues faced by three stakeholders of crowdfunding and strives to satisfy their requirements and maximizes the utility of tool.
Mengistu Gera,Sahilu Geremew,Alakangas Lena,Mulat Worku,Kloos Helmut 한국자원공학회 2023 Geosystem engineering Vol.26 No.1
Tailings dam is the main heavy metal pollution source in mining areas. In this study, the concentration of heavy metals in soil and water from upstream and downstream of the tailings dam was analyzed. The concentration of As, Cd, Cu, Ni, Pb, and W in tailings soil exceeded the standard value but Hg and Zn in the tailings soil were far below the standard. Average concentrations of As, Pb, and W in soil samples were above the upstream reference soil. The level of As and Pb decreases, downstream as the distance from the tailings dam increases. The mean concentrations of the heavy metals in water for Ni, Cu, Zn, Pb, and Cd were 106.3, 57.3, 21.8, 14.5, and 8.0 μg/L, respectively. The Ni contents in all studied water samples had concentrations higher than Awata River and WHO guidelines for drinking water. Both geo-accumulation and ecological risk indices have indicated significant heavy metal pollution in the study area. The overall results of this study showed that the soil and water downstream of the tailings dam were not safe and must be protected against access to humans and domestic animals.
Pattern of Fractures in Non-Accidental Injuries in the Pediatric Population in Singapore
Sumanth Kumar Gera,Rakesh Raveendran,Arjandas Mahadev 대한정형외과학회 2014 Clinics in Orthopedic Surgery Vol.6 No.4
fracBackground:Fractures as a result of non-accidental injuries (NAI) are not uncommon among children. The purpose of our study was to describe the incidence, demographic characteristics, and associated risk factors in patients with NAI in a multiethnic Asian cohort. Methods: A retrospective record review of patients admitted to our hospital between September 2007 and 2009 with the diagnosis of NAI was conducted. Results: A total of 978 children were reported with suspicion of NAI. Among them, 570 patients (58.28%) were diagnosed with NAI. Fractures were observed in 35 children (6.14%). NAI fractures were highest among female infants (73.3%). The biological father was the most common known perpetrator of NAI (n = 155, 29.0%). The most common perpetrator sadly remained unknown (n = 14, 40%). All NAI fractures were closed (n = 35, 6.14%), and the most commonly affected bone was the humeral shaft (n = 10, 28.57%) with an oblique configuration. Age < 1 year and parental divorce were significant risk factors associated with these fractures. Conclusions: The skeletal injury pattern and risk factors highlighted in our study will help treating physicians identify patients susceptible to NAI, as many of these patients are young and vulnerable. Protective measures can be initiated early by recognizing these injuries and preventing further physical and psychological harm to the child.
Effects of Ionizing Radiation on Plants and the Radiological Protection of the Environment
Stanislav A.,Geras'kin,Kim, Jin Kyu 한국환경생물학회 2003 환경생물 : 환경생물학회지 Vol.21 No.4
Differences between the principles for the radiological protection of man and the environment are compared. The derived levels of exposure for man and biota recommended by the international agencies with dose rates for chronic radiation producing effects at different levels of biological organization were given in terms of the biological effects. Cytogenetic effects on plants after an exposure to ionizing radiation at low doses alone and in combination with other factors are discussed. A wide range of experimental data were analysed and the general conclusions were extracted to cover the topics such as non-linearity of dose response, synergistic and antagonistic effects of the combined exposure of different factors, radiation-induced genomic instability, and the phenomena of radioadaptation.
Shukla Vikram,Gera Bhuvaneshwar,Ganju Sunil,Varma Salil,Maheshwari N.K.,Guchhait P.K.,Sengupta S. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11
Hydrogen mitigation using Passive Autocatalytic Recombiners (PARs) has been widely accepted methodology inside reactor containment of accident struck Nuclear Power Plants. They reduce hydrogen concentration inside reactor containment by recombining it with oxygen from containment air on catalyst surfaces at ambient temperatures. Exothermic heat of reaction drives the product steam upwards, establishing natural convection around PAR, thus invoking homogenisation inside containment. CFD models resolving individual catalyst plate channels of PAR provide good insight about temperature and hydrogen recombination. But very thin catalyst plates compared to large dimensions of the enclosures involved result in intensive calculations. Hence, empirical correlations specific to PARs being modelled are often used in integral containment studies. In this work, an experimentally validated CFD model of PAR has been employed for developing an empirical correlation for Indian PAR. For this purpose, detailed parametric study involving different gas mixture variables at PAR inlet has been performed. For each case, respective values of gas mixture variables at recombiner outlet have been tabulated. The obtained data matrix has then been processed using regression analysis to obtain a set of correlations between inlet and outlet variables. The empirical correlation thus developed, can be easily plugged into commercially available CFD software.