629 research outputs found
Critical behavior and phase transition of dilaton black holes with nonlinear electrodynamics
In this paper, we take into account the dilaton black hole solutions of
Einstein gravity in the presence of logarithmic and exponential forms of
nonlinear electrodynamics. At first, we consider the cosmological constant and
nonlinear parameter as thermodynamic quantities which can vary. We obtain
thermodynamic quantities of the system such as pressure, temperature and Gibbs
free energy in an extended phase space. We complete the analogy of the
nonlinear dilaton black holes with Van der Waals liquid-gas system. We work in
the canonical ensemble and hence we treat the charge of the black hole as an
external fixed parameter. Moreover, we calculate the critical values of
temperature, volume and pressure and show they depend on dilaton coupling
constant as well as nonlinear parameter. We also investigate the critical
exponents and find that they are universal and independent of the dilaton and
nonlinear parameters, which is an expected result. {Finally, we explore the
phase transition of nonlinear dilaton black holes by studying the Gibbs free
energy of the system. We find that in case of , we have no phase
transition. When , the system admits a second order phase transition,
while for the system experiences a first order transition.
Interestingly, for we observe a \textit{zeroth order} phase
transition in the presence of dilaton field. This novel \textit{zeroth order}
phase transition is occurred due to a finite jump in Gibbs free energy which is
generated by dilaton-electromagnetic coupling constant, , for a certain
range of pressure.
Evaluation of urinary iodine concentrations in pregnant women in Tehran
Background And Objective: Congenital hypothyroidism due to iodine deficiency is the most common cause of preventable mental retardation in the world. The lowest level of iodine deficiency during pregnancy could result in disorders such as miscarriage, premature delivery, intrauterine fetal death low birth IQ, mental retardation, hearing difficulty and speech impediments. This study aimed to evaluate urinary iodine concentrations during the first, second and third trimesters of pregnancy. Methods: This cross-sectional study was conducted on 354 pregnant women referring to prenatal care clinic of Akbar Abadi Hospital in Tehran. Demographic questionnaires were completed by an expert, and random urine samples were obtained to measure urinary iodine concentrations. In addition, venous blood samples were provided to determine the levels of thyroxine (T4) and thyroid stimulating hormone (TSH) during the first, second and third trimesters. Analysis of iodine status was based on the urinary iodine excretion in the patients. Urinary iodine deficiency was defined as concentrations of �100 micrograms/liter. FINDINGS: In this study, 285 patients (80.5) had urinary iodine levels of �100 µg/l with a mean of 62.35±67.7 µg/l. The mean urinary iodine concentrations during the first, second and third trimesters were 65.83±72.4, 50.34±41.5 and 62.67±68.3 µg/l, respectively. No significant difference was observed in the mean of urinary iodine between the first and second trimesters, second and third trimesters, and first and third trimesters. Moreover, no significant differences were observed between patients with urinary iodine levels of <100 µg/l and �100 µg/l in terms of the mean of maternal age, age at pregnancy and TSH level. CONCLUSION: According to the results of this study, despite the consumption of iodized salt, urinary iodine concentrations were below the standard limits in the studied pregnant women. It could be inferred that use of iodized salt may not be a proper solution for iodine deficiency in pregnant women. Therefore, it is recommended that iodine supplements be used before and during pregnancy, and iodine content of salt be increased as well. © 2015, Babol University of Medical Sciences. All rights reserved
Energy commitment: a planning of energy carrier based on energy сonsumption
Purpose. Energy consumption is one of the criteria for determining the quality of life in a country. Continued supply of energy and the possibility of long-term access to resources require a comprehensive plan. One of the key issues in the field of energy planning is energy carriers. Inthis paper, a new theory is introduced to energy network studies for planning of energy carriers called Energy Commitment. In this theory, an appropriate planning is applied for energy carriers based the final energy consumption. Energy carriers are available either naturally or after the energy conversion process. Energy commitment is modeled on an energy network with the presence of electrical energy, gas energy, transportation section, agriculture section, industrial section, residential section, commercial section, and general section.Цель. Потребление энергии является одним из критериев определения качества жизни в стране. Непрерывные поставки энергии и возможность долгосрочного доступа к ресурсам требуют комплексного плана. Одним из ключевых вопросов в области энергетического планирования являются энергоносители. В данной статье в исследования энергетических сетей для планирования энергоносителей вводится новая теория под названием Energy Commitment («энергетическое обязательство»). В этой теории для энергоносителей применяется соответствующее планирование на основе конечного потребления энергии. Энергоносители доступны либо естественным путем, либо после процесса преобразования энергии. Energy Commitment моделируется в энергетической сети с учетом электрической энергии, энергии газа, транспортной отрасли народного хозяйства, сельскохозяйственной отрасли, промышленного сектора экономики, жилищно коммунального хозяйства, реального сектора экономики и прочих видов экономической активности
Spring search algorithm for simultaneous placement of distributed generation and capacitors
Purpose. In this paper, for simultaneous placement of distributed generation (DG) and capacitors, a new approach based on Spring Search Algorithm (SSA), is presented. This method is contained two stages using two sensitive index Sv and Ss. Sv and Ss are calculated according to nominal voltageand network losses. In the first stage, candidate buses are determined for installation DG and capacitors according to Sv and Ss. Then in the second stage, placement and sizing of distributed generation and capacitors are specified using SSA. The spring search algorithm is among the optimization algorithms developed by the idea of laws of nature and the search factors are a set of objects. The proposed algorithm is tested on 33-bus and 69-bus radial distribution networks. The test results indicate good performance of the proposed methodЦель. В статье для одновременного размещения распределенной генерации и конденсаторов представлен новый подход, основанный на "пружинном" алгоритме поиска (Spring Search Algorithm, SSA). Данный метод состоит из двух этапов с использованием двух показателей чувствительности Sv и Ss. Показатели чувствительности Sv и Ss рассчитываются в соответствии с номинальным напряжением и потерями в сети. На первом этапе определяются шины-кандидаты для установки распределенной генерации и конденсаторов согласно Sv и Ss. Затем, на втором этапе размещение и калибровка распределенной генерации и конденсаторов выполняются с использованием алгоритма SSA. "Пружинный" алгоритм поиска входит в число алгоритмов оптимизации, разработанных на основе идей законов природы, а факторы поиска представляют собой набор объектов. Предлагаемый алгоритм тестируется на радиальных распределительных сетях с 33 и 69 шинами. Результаты тестирования показывают хорошую эффективность предложенного метода
A new methodology called dice game optimizer for capacitor placement in distribution systems
Purpose. Shunt capacitors are installed in power system for compensating reactive power. Therefore, feeder capacity releases, voltage profile improves and power loss reduces. However, determination optimal location and size of capacitors in distributionsystems is a complex optimization problem. In order to determine the optimum size and location of the capacitor, an objective function which is generally defined based on capacitor installation costs and power losses should be minimized According to operational limitations. This paper offers a newly developed metaheuristic technique, named dice game optimizerto determine optimal size and location of capacitors in a distribution network. Dice game optimizer is a game based optimization technique that is based on the rules of the dice game.Цель. Шунтирующие конденсаторы в энергосистеме устанавливаются для компенсации реактивной мощности. Следовательно, снижается емкость фидера, улучшается профиль напряжения и снижаются потери мощности. Однако определение оптимального местоположения и размера конденсаторов в системах распределения является сложной задачей оптимизации. Чтобы определить оптимальный размер и расположение конденсатора, целевую функцию, которая обычно определяется на основе затрат на установку конденсатора и потерь мощности, следует минимизировать в соответствии с эксплуатационными ограничениями. Данная статья предлагает недавно разработанный метаэвристический метод, называемый оптимизатором игры в кости, для определения оптимального размера и расположения конденсаторов в распределительной сети. Оптимизатор игры в кости – это игровой метод оптимизации, основанный на правилах игры в кости
Lorentzian Wormholes in Lovelock Gravity
In this paper, we introduce the -dimensional Lorentzian wormhole solutions
of third order Lovelock gravity. In contrast to Einstein gravity and as in the
case of Gauss-Bonnet gravity, we find that the wormhole throat radius, ,
has a lower limit that depends on the Lovelock coefficients, the dimensionality
of the spacetime and the shape function. We study the conditions of having
normal matter near the throat, and find that the matter near the throat can be
normal for the region , where depends on
the Lovelock coefficients and the shape function. We also find that the third
order Lovelock term with negative coupling constant enlarges the radius of the
region of normal matter, and conclude that the higher order Lovelock terms with
negative coupling constants enlarge the region of normal matter near the
throat.Comment: 13 pages, 5 figure
The Levantine Basin - crustal structure and origin
The origin of the Levantine Basin in the Southeastern Mediterranean Sea is related to the opening of the Neo-Tethys. The nature of its crust has been debated for decades. Therefore, we conducted a geophysical experiment in the Levantine Basin. We recorded two refraction seismic lines with 19 and 20 ocean bottom hydrophones, respectively, and developed velocity models. Additional seismic reflection data yield structural information about the upper layers in the first few kilometers. The crystalline basement in the Levantine Basin consists of two layers with a P-wave velocity of 6.06.4 km/s in the upper and 6.56.9 km/s in the lower crust. Towards the center of the basin, the Moho depth decreases from 27 to 22 km. Local variations of the velocity gradient can be attributed to previously postulated shear zones like the Pelusium Line, the DamiettaLatakia Line and the BaltimHecateus Line. Both layers of the crystalline crust are continuous and no indication for a transition from continental to oceanic crust is observed. These results are confirmed by gravity data. Comparison with other seismic refraction studies in prolongation of our profiles under Israel and Jordan and in the Mediterranean Sea near Greece and Sardinia reveal similarities between the crust in the Levantine Basin and thinned continental crust, which is found in that region. The presence of thinned continental crust under the Levantine Basin is therefore suggested. A β-factor of 2.33 is estimated. Based on these findings, we conclude that sea-floor spreading in the Eastern Mediterranean Sea only occurred north of the Eratosthenes Seamount, and the oceanic crust was later subducted at the Cyprus Arc
Pathology of Technology Curriculum in secondary School: Qualitative Study
Background and ObjectiveS: The field of training and learning of work and technology is one of the eleven areas included in the national curriculum and includes the acquisition of practical skills for a productive life and the acquisition of competencies related to technology related sciences. One of the main foundations of curriculum reform in the 20th century is the trend of increasing technology education. These competencies are essential for technological education and healthy life in the cyberspace, as well as readiness to enter professions and jobs in various economic and social sectors. According to Islamic teachings, work and employment have educational values and through work, human polishes their existential personality, establishes their identity and prepares the ground for their existential development and the possibility of earning a lawful livelihood and provides to meet the needs of the community. Another step in developing minimum skills is teaching design and technology in schools. Technology education, work and skills training will lead to personal development, increase productivity, participation in social and economic life, reduce poverty, and increase income and development. It should be noted that pathology is a systematic process of data collection in order to interact effectively and usefully in order to solve problems, challenges, pressures and environmental constraints in society. In fact, the pathology of the work and technology curriculum can help in determining hindrances, weaknesses and strengths, and challenges and opportunities and proposing suitable strategies. Also, warranting the quality in work and technology education is amongst the top priorities to develop the related curriculum, job selection and applied disciplines. If the quality of the curriculum of work and technology is not examined systematically, the entrepreneurship that is the top need of the country is not developed. The purpose of this study is to identify the damages in the implementation of the technology curriculum. Methods: This research is qualitative and phenomenological. This research was performed using a participatory observation tool and a semi-structured interview. The statistical society of this study was all Technology teachers and all students in secondary school in Baharestan city. Twenty of teachers were selected through available sampling, 80 of students were selected through accessible sampling and group interviews were conducted in groups of 6 to 8 people. Then the text of the interviews was analyzed in a 7-step manner. Findings: The findings of the research showed that from the perspective of teachers of technology education, five categories of "constraints, social factors, structural inadequacy, motivating strategies and curriculum planning" and ten sub-themes and from the perspective of students’ three categories of "social factors, motivational strategies and curriculum planning" and eleven sub-themes are vulnerable. Conclusion: There are many problems and damages from the point of view of teachers and students, for implementation of Technology Curriculum; Therefore, it is necessary to pay attention to the conditions for the implementation of efficient methods of Technology curriculum, as it plays an essential role in generating entrepreneurial generation. Therefore, policy makers and educators need to pay more attention to the proper implementation of this curriculum. Policymakers and educators should pay more attention to the proper implementation of this curriculum. In line with this research, the following practical suggestions are presented: in-service courses should be held for teachers regarding the complete training of skills and modules; necessary funds should be awarded to fully equip the schools with the necessary facilities to carry out activities; the content of the curriculum should be revised according to the needs of the students and the facilities of the school in order to provide the necessary context for communication with the real life of the students; a clear framework and criteria for student evaluation should be established. ===================================================================================== COPYRIGHTS ©2020 The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers. ====================================================================================
Slowly rotating charged black holes in anti-de Sitter third order Lovelock gravity
In this paper, we study slowly rotating black hole solutions in Lovelock
gravity (n=3). These exact slowly rotating black hole solutions are obtained in
uncharged and charged cases, respectively. Up to the linear order of the
rotating parameter a, the mass, Hawking temperature and entropy of the
uncharged black holes get no corrections from rotation. In charged case, we
compute magnetic dipole moment and gyromagnetic ratio of the black holes. It is
shown that the gyromagnetic ratio keeps invariant after introducing the
Gauss-Bonnet and third order Lovelock interactions.Comment: 14 pages, no figur
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