1,521 research outputs found
Improving the Efficiency of a Nuclear Power Plant Using a Thermoelectric Cogeneration System
The efficiencies of nuclear power plants are rather poor having the ratio %30 by using the conventional energy/exergy tools. According to that information, large amount of energy is wasted during condensation and thrown out to the environment. Thermoelectric generator (TEG) system has a potential to be used as a heat exchanging technology to produce power with a relatively low efficiency (about 5%) and it can transform the temperature difference into electricity and generate clean electrical energy. In the present study, we offer a novel system to recover the waste heat from a VVER-1000 nuclear power plant. The heat transfer of the TEG is analyzed numerically with respect to the various temperature ranges and constant mass flow rate of the exhaust steam entering the system. In the analyses, different hot temperature ranges (35ÂșC, 45ÂșC and 55ÂșC) and a constant cold temperature (i.e. 18ÂșC) are used for a HZ-20 thermoelectric module and it has been proven that the designed TEG can produce the maximum output power of 76,956 MW for a temperature difference âT=37 and the conversion efficiency of 3.854% sits. The TEG is designed for the condenser of a 1000 MW nuclear power plant. It\u27s shown that about 2.0% increasing in the power plant efficiency is expected by using the selected thermoelectric generator in the condensation cycle.Article History: Received: July 15th 2017; Received: October 17th 2017; Accepted: February 13rd 2018; Available onlineHow to Cite This Article: Terzi, R. and Kurt, E. (2018), Improving the efficiency of a nuclear power plant using a thermoelectric cogeneration system, Int. Journal of Renewable Energy Development, 7(1), 77-84.https://doi.org/10.14710/ijred.7.1.77-8
Optimal Multiple Crop Price Hedging: Robust Estimates Under Yield/Basis Risk
This paper examines how commodity futures can optimally be used by farmers to reduce exposure to price risk in the presence of production uncertainty. The multiple-crop hedging problem is modeled under conditions of price risk, production risk, and basis risk. The results are of general significance for producers with concave utility functions of expected wealth.Optimal hedges are obtained that are quantitatively robust for different wealth levels and for variations in utility functions spanning the plausible range from decreasing to increasing relative risk aversion and for relative risk aversion coefficients of any plausible value.Extensions to the existing literature include a closed form solution that provides robust estimates of optimal hedging strategy for the multiple crop hedging problem under uncertain yields, estimation of the optimal hedge variation as a function of distance from the geographical center of crop production, and optimal hedge estimates for state average crop mixes by state for forty-two states
INVESTIGATING HOW PARENTS, WHO GUIDE THEIR PRESCHOOL CHILDREN TOWARDS SPORTS, PERCEIVE SPORTS ACTIVITIES
Objectives: The aim of this study was to investigate parentsâ expectations about general sport activities for their pre-school children. It is well documented that the awareness of sports knowledge of the parents are essential for the development of healthy life and acquiring a social dimension with a growth of healthy generations. Method: We administrated the ââParents' Expectations of Their Children Questionnaireââ developed by Keskin (2006). The questionnaire was a Likert type scale from ââtotally agreeââ to ââtotally disagreeââ and validity and reliability studies were reported by Keskin as Cronbachâs alpha was 0,86. A total of 125 participants (male; N = 39, Mage=35, 24 ± 5,48 , female; N = 86 and Mage=37,92 ± 6,65) were voluntarily participated from 10 different kinder gardens in Bursa province. The evaluation of the data was analysed with the Chi Square Test. Result: Our results revealed a statistical differences (p < .05) according to the sex groups of parents ââI believe my child will gain good eating habits by getting involved with sports activitiesââ and age groups of parents; ââI believe by getting involved with sport activities, my child will stay away from psychological stressââ. Conclusion: According to parentsâ belief and their expectations, attending sports activities for children provides physical, cognitive and social development for them. Developing countries (as well as developed ones) that are aware of the role of the parents on development of human being via sport and exercise activities should take into account their expectations especially in terms of sports policies. Article visualizations
Smoking among Nurses in Turkey: Comparison with Other Countries
The purpose of this study was to obtain baseline information on smoking among nurses. An attempt was made to contact, in person, all 301 nurses working for the university hospital in Sivas, Turkey, and when contacted they were asked to complete an anonymous questionnaire. Each unit of the hospital was visited three times, and 239 (79%) nurses were reached who all completed the questionnaire. Of the 239 respondents, 107 (45%) were current smokers, reflecting a substantially higher prevalence compared to that among the adult female population. The quit ratio was 22.5%. Of 127 ever-smoker nurses who responded to the related item, 90% started smoking during or after nursing education. This pattern of smoking initiation was different from the pattern in developed countries where nurses had already started smoking before beginning that training. Nurses with a high school education had a significantly higher prevalence of ever-smoking. Most respondents frequently or sometimes saw doctors smoking in rooms for nurses and in rooms for doctors in inpatient services. In-depth qualitative studies are needed to determine the reasons for the different smoking-initiation pattern
Group Size and Social Conflict in Complex Societies
Conflicts of interest over resources or reproduction among individuals in a social group have long been considered to result in automatic and universal costs to group living. However, exploring how social conflict varies with group size has produced mixed empirical results. Here we develop a model that generates alternative predictions for how social conflict should vary with group size depending on the type of benefits gained from being in a social group. We show that a positive relationship between social conflict and group size is favored when groups form primarily for the benefits of sociality but not when groups form mainly for accessing group-defended resources. Thus, increased social conflict in animal societies should not be viewed as an automatic cost of larger social groups. Instead, studying the relationship between social conflict and the types of grouping benefits will be crucial for understanding the evolution of complex societies
Using learned affordances for robotic behavior development
âDevelopmental roboticsâ proposes that, instead of trying to build a robot that shows intelligence once and for all, what one must do is to build robots that can develop. These robots should be equipped with behaviors that are simple but enough to bootstrap the system. Then, as the robot interacts with its environment, it should display increasingly complex behaviors. In this paper, we propose such a development scheme for a mobile robot. J.J. Gibsonâs concept of âaffordancesâ provides the basis of this development scheme, and we use a formalization of affordances to make the robot learn about the dynamics of its interactions with its environment. We show that an autonomous robot can start with pre-coded primitive behaviors, and as it executes its behaviors randomly in an environment, it can learn the affordance relations between the environment and its behaviors. We then present two ways of using these learned structures, in achieving more complex, intentional behaviors. In the first case, the robot still uses its pre-coded primitive behaviors only, but the sequencing of these primitive behaviors are such that new more complex behaviors emerge. In the second case, the robot makes a âblendingâ of its pre-coded primitive behaviors to create new behaviors that can be more effective in reaching its goal than any of the pre-coded behaviors
Biological Institutions: The Political Science of Animal Cooperation
Social evolution is one of the most rapidly developing areas in evolutionary biology. A main theme is the emergence of cooperation among organisms, including the factors that impede cooperation. Although animal societies seem to have no formal institutions, such as courts or legislatures, we argue that biology presents many examples where an interaction can properly be thought of as an informal institution, meaning there are evolved norms and structure to the interaction that enable parties to reach mutually beneficial outcomes. These informal institutions are embedded in the natural history of the interaction, in factors such as where and when parties interact, how long and how close they stay together, and so on. Institutional theory thus widens the scope of behavioral ecology by considering not only why animals evolve to choose the strategies they choose, but also asking both why it is that they find themselves in those particular interaction setups and how these particular interactions can be sustained. Institutions frequently enable interacting parties avoid inefficient outcomes and support efficient exchange among agents with conflicting interests.
The main thesis of this paper is that the organization of many biological interactions can properly be understood as institutions that enable mutually beneficial outcomes to be achieved relative to an unstructured interaction. To do this, institutions resolve or regulate the conflicts of interests among parties. The way conflicts of interests affect the outcome depends on the structure of the interaction, which can create problems of commitment, coordination and private information. Institutional theory focuses on how to address each of these issues, typically focusing on the development of social norms, rules, and other constraints on individual behaviors. We illustrate our thesis with examples from cooperative breed and genes as within-body-mechanism-design
Kinematic landslide monitoring with Kalman filtering
International audienceLandslides are serious geologic disasters that threat human life and property in every country. In addition, landslides are one of the most important natural phenomena, which directly or indirectly affect countries' economy. Turkey is also the country that is under the threat of landslides. Landslides frequently occur in all of the Black Sea region as well as in many parts of Marmara, East Anatolia, and Mediterranean regions. Since these landslides resulted in destruction, they are ranked as the second important natural phenomenon that comes after earthquake in Turkey. In recent years several landslides happened after heavy rains and the resulting floods. This makes the landslide monitoring and mitigation techniques an important study subject for the related professional disciplines in Turkey. The investigations on surface deformations are conducted to define the boundaries of the landslide, size, level of activity and direction(s) of the movement, and to determine individual moving blocks of the main slide. This study focuses on the use of a kinematic deformation analysis based on Kalman Filtering at a landslide area near Istanbul. Kinematic deformation analysis has been applied in a landslide area, which is located to the north of Istanbul city. Positional data were collected using GPS technique. As part of the study, conventional static deformation analysis methodology has also been applied on the same data. The results and comparisons are discussed in this paper
CD10 expression in urothelial carcinoma of the bladder
Background. CD10 antigen is a 100-kDa-cell surface zinc metalloendopeptidase and it is expressed in a variety of normal and neoplastic lymphoid and nonlymphoid tissues. The aim of this study was to evaluate CD10 expression in urothelial carcinoma of the urinary bladder and to determine the correlation between immunohistochemical (IHC) CD10 expression and histopathologic parameters including grade and stage. Methods. 371 cases of urothelial bladder carcinomas, all from transurethral resections, were included in this study. Hematoxylin-eosin (HE) stained sections from each case were reevaluated histopathologically according to WHO 2004 grading system. The TNM system was used for pathologic staging. Selected slides were also studied by IHC and a semiquantitative scoring for CD10 expression based on the percentage of positive cells was performed. Results. 157 cases (42.3%) showed immunostaining while 214 cases (57.7%) were negative for CD10. 1+ staining was seen in 65 CD10 positive cases (41.4%), and 2+ in 92 cases (58.6%). Overall CD10 expression as well as 2+ immunostaining was significantly correlated with high histologic grade. Overall CD10 expression was also significantly higher in invasive pT1 and pT2-3 tumors compared to noninvasive pTa tumors. pT1 and pT2-3 tumors were also significantly correlated with 2+ immunostaining. Conclusion. To date, only a few comparative IHC studies have assessed CD10 expression in urothelial carcinoma of the urinary bladder and this study represents the largest series. Our findings indicate that CD10 expression is strongly correlated with high tumor grade and stage in urothelial carcinoma of the bladder, and that CD10 may be associated with tumor progression in bladder cancer pathogenesis. © 2009 Bahadir et al; licensee BioMed Central Ltd
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