Search results for: solar resource assessment

Authors: Ahmed N. Shmroukh, Gamal Tag Abdel-Jaber, Rashed D. Aldughpassi

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The feasibility of improving the performance of the proposed solar still unit which operated in very hot climate is investigated numerically and verified with experimental data. This solar desalination unit with proposed auxiliary device as seawater preheating system using petrol based textherm oil was used to produce pure fresh water from seawater. The effective evaporation area of basin is about 1 m². The unit was tested in two main operation modes which are normal and with seawater preheating system. The results showed that, there is good agreement between the theoretical data and the experimental data; this means that the numerical model can be accurately dependable for predicting the proposed solar still performance and design parameters. The results also showed that the fresh water productivity of the solar still in the modified preheating case which is higher than normal case, leads to an increase in productivity of 42%.

Keywords: improving productivity, seawater desalination, solar stills, theoretical model

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Authors: O. P. Tripathi, P. L. Verma

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Coronal Mass Ejections (CMEs) are mostly reached on Earth from 1 to 5 days from the Sun. As a consequence, slow CMEs are accelerated toward the speed of solar wind and fast CMEs are decelerated toward the speed of the solar wind. Coronal mass ejections (CMEs) are bursts of solar material i.e. clouds of plasma and magnetic fields that shoot off the sun’s surface. Other solar events include solar wind streams that come from the coronal holes on the Sun and solar energetic particles that are primarily released by CMEs. We have studied geomagnetic storms (DST ≤ - 80nT) during 1997-2012 with halo and partial halo coronal mass ejections and found that 73.28% CMEs (halo and partial halo coronal mass ejections) are associated with geomagnetic storms. The association rate of halo and partial halo coronal mass ejections are found 67.06% and 32.94% with geomagnetic storms respectively. We have also determined positive co-relation between magnitude of geomagnetic storms and speed of coronal mass ejection with correlation co-efficient 0.23.

Keywords: geomagnetic storms, coronal mass ejections (CMEs), disturbance storm time (Dst), interplanetary magnetic field (IMF)

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Authors: Rawaa H. El-Bidweihy, Hisham M. Abdelsalam, Ihab A. El-Khodary

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In an era where machines run and shape our world, the need for a stable, non-ending source of energy emerges. In this study, the focus was on the solar energy in Egypt as a renewable source, the most important factors that could affect the solar energy’s market share throughout its life cycle production were analyzed and filtered, the relationships between them were derived before structuring a Bayesian network. Also, forecasted models were built for multiple factors to predict the states in Egypt by 2035, based on historical data and patterns, to be used as the nodes’ states in the network. 37 factors were found to might have an impact on the use of solar energy and then were deducted to 12 factors that were chosen to be the most effective to the solar energy’s life cycle in Egypt, based on surveying experts and data analysis, some of the factors were found to be recurring in multiple stages. The presented Bayesian network could be used later for scenario and decision analysis of using solar energy in Egypt, as a stable renewable source for generating any type of energy needed.

Keywords: ARIMA, auto correlation, Bayesian network, forecasting models, life cycle, partial correlation, renewable energy, SARIMA, solar energy

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Authors: Naci Kalkan, Ihsan Dagtekin

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Passive design responds to improve indoor thermal comfort and minimize the energy consumption. The present research analyzed the how efficiently passive solar technologies generate heating and cooling and provide the system integration for domestic applications. In addition to this, the aim of this study is to increase the efficiency of solar systems system with integration some innovation and optimization. As a result, outputs of the project might start a new sector to provide environmentally friendly and cheap cooling for domestic use.

Keywords: passive solar systems, heating, cooling, thermal comfort, ventilation systems

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Authors: Mariyappan Shanmugam, Bin Yu

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Schottky-barrier solar cells are demonstrated employing 2D-layered MoS2 and WS2 semiconductor nanofilms as photo-active material candidates synthesized by chemical vapor deposition method. Large area MoS2 and WS2 nanofilms are stacked by layer transfer process to achieve thicker photo-active material studied by atomic force microscopy showing a thickness in the range of ~200 nm. Two major vibrational active modes associated with 2D-layered MoS2 and WS2 are studied by Raman spectroscopic technique to estimate the quality of the nanofilms. Schottky-barrier solar cells employed MoS2 and WS2 active materials exhibited photoconversion efficiency of 1.8 % and 1.7 % respectively. Fermi-level pinning at metal/semiconductor interface, electronic transport and possible recombination mechanisms are studied in the Schottky-barrier solar cells.

Keywords: two-dimensional nanosheet, graphene, hexagonal boron nitride, solar cell, Schottky barrier

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Authors: Monia Hassan Abdulrahman

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Resource-based view is built on many theories in addition to diverse perspectives, we extend this view placing emphasis on human resources addressing the tools required to sustain competitive advantage. Highlighting on several theories and judgments, assumptions were established to clearly reach if resource possession alone suffices for the sustainability of competitive advantage, or necessary accommodation are required for better performance. New practices were indicated in terms of resources used in firms, these practices were implemented on the human resources in particular, and results were developed in compliance to the mentioned assumptions. Such results drew attention to the significance of practices that provide enhancement of human resources that have a core responsibility of maintaining resource-based view for an organization to lead the way to gaining competitive advantage.

Keywords: competitive advantage, resource based value, human resources, strategic management

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Authors: Mustafa Al-Refai

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This paper presents the optimal design and simulation of a grid-connected Photovoltaic (PV) system to supply electric power to meet the energy demand by Electrical Department in University of Tripoli Libya. Solar radiation is the key factor determining electricity produced by photovoltaic (PV) systems. This paper is designed to develop a novel method to calculate the solar photovoltaic generation capacity on the basis of Mean Global Solar Radiation data available for Tripoli Libya and finally develop a system design of possible plant capacity for the available roof area. MatLab/Simulink Programming tools and monthly average solar radiation data are used for this design and simulation. The specifications of equipments are provided based on the availability of the components in the market. Simulation results and analyses are presented to validate the proposed system configuration.

Keywords: photovoltaic (PV), grid, Simulink, solar energy, power plant, solar irradiation

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Authors: Lin Yunuo, Seow Xing Quan, Burra Venkata Durga Kumar

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In this modern era, the cloud operating system is the world trend applied in various industries such as business, healthy, etc. In order to deal with the large capacity of requirements in cloud computing, research come up with multi-tenant cloud computing to maximize the benefits of server providers and clients. However, there are still issues in multi-tenant cloud computing especially regarding resource allocation. Issues such as inefficient resource utilization, large latency, lack of scalability and elasticity and poor data isolation had caused inefficient resource allocation in multi-tenant cloud computing. Without a doubt, these issues prevent multitenancy reaches its best condition. In fact, there are multiple studies conducted to determine the optimal resource allocation to solve these problems these days. This article will briefly introduce the cloud operating system, Multi-tenant cloud computing and resource allocation in cloud computing. It then discusses resource allocation in multi-tenant cloud computing and the current challenges it faces. According to the issue ‘ineffective resource utilization’, we will discuss an efficient dynamic scheduling technique for multitenancy, namely Multi-tenant Dynamic Resource Scheduling Model (MTDRSM). Moreover, there also have some recommendations to improve the shortcoming of this model in this paper’s final section.

Keywords: cloud computing, cloud operation system, multitenancy, resource allocation, utilization of cloud resources

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Authors: Nora Arbaoui, Rachid Tadili, Ilham Ihoume

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To improve the climatic conditions and increase production in the greenhouse during the winter season under the Mediterranean climate, this thesis project proposes a design of an integrated and autonomous solar system for heating, cooling, and conservation of production in an agricultural greenhouse. To study the effectiveness of this system, experiments are conducted in two similar agricultural greenhouses oriented north-south. The first greenhouse is equipped with an active solar system integrated into the double glazing of the greenhouse’s roof, while the second greenhouse has no system, it serves as a controlled greenhouse for comparing thermal and agronomic performance The solar system allowed for an average increase in the indoor temperature of the experimental greenhouse of 6°C compared to the outdoor environment and 4°C compared to the control greenhouse. This improvement in temperature has a favorable effect on the plants' climate and subsequently positively affects their development, quality, and production.

Keywords: solar system, agricultural greenhouse, heating, cooling, storage, drying

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Authors: Rajesh Kumar, Prabha Chand

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Fins and twisted tape inserts are widely used passive elements to enhance heat transfer rate in various engineering applications. The present paper describes the theoretical analysis of solar air heater fitted with fins and twisted tape inserts. Mathematical model is develop for this novel design of solar air heater and a MATLAB code is generated for the solution of the model. The effect of twist ratio, mass flow rate and inlet temperature on the thermal efficiency and exit air temperature has been investigated. The results are compared with the results of plane solar air heater. Results show a substantial enhancement in heat transfer rate, efficiency and exit air temperature.

Keywords: solar air heater, thermal efficiency, twisted tape, twist ratio

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Authors: Leila Ayat, Afak Meftah

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Amorphous-silicon alloys have great promise as low cost solar cell materials. They have excellent photo-conductivity and high optical absorption to sunlight. Now PIN a-Si:H based solar cells are widely used in power generation modules. However, to improve the performance of these cells further, a better fundamental under-standing of the factors limiting cell performance in the homo junction PIN structure is necessary. In this paper we discuss the sensitivity of light J-V characteristics to various device and material parameters in PIN homo junction solar cells. This work is a numerical simulation of the output parameters of a PIN a-Si:H solar cell under AM1.5 spectrum. These parameters are the short circuit current (Jsc), the open circuit voltage (Voc), the fill factor (FF), the conversion efficiency. The simulation was performed with SCAPS-1D software version 3.3 developed at ELIS in Belgium by Marc Burgelman et al. The obtained results are in agreement with experiment. In addition, the effect of the thickness, doping density, capture cross sections of the gap states and the band microscopic mobilities on the output parameters of the cell are also presented.

Keywords: amorphous silicon p-i-n junctions, thin film, solar cells, sensitivity

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Authors: D. C. Asebiah, D. Saranin, S. Karazhanov, A. R. Tameev, M. Kah

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In this paper, the mesoscopic NiO was used as a hole transport layer in the inverted planar organometallic hybrid perovskite solar cell to study the effect of hysteresis. The devices we fabricated have the structures Fluorine Tin Oxide (FTO)/mesoscopic NiO/perovskite/[6,6]-phenyl C₆₁-butyric acid methyl ester (PC₆₁BM) photovoltaic device. The perovskite solar cell was done by toluene air (TLA) method and horn sonication for the dispersion of the NiO nanoparticles in deionized water. The power conversion efficiency was 12.07% under 1.5 AM illumination. We report hysteresis in the in current-voltage dependence of the solar cells with mesoscopic NiO as a hole transport layer.

Keywords: perovskite, mesoscopic, hysteresis, toluene air

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Authors: Ahmed Aisa, Tariq Iqbal

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This letter talks about the ready-to-use design of a solar water heating system because, in Canada, the average consumption of hot water per person is approximately 50 to 75 L per day and the average Canadian household uses 225 L. Therefore, this paper will demonstrate the method of designing a solar water heating system with thermal storage. It highlights the renewable hybrid power system, allowing you to obtain a reliable, independent system with the optimization of the ingredient size and at an improved capital cost. The system can provide hot water for a big building. The main power for the system comes from solar panels. Solar Advisory Model (SAM) and HOMER are used. HOMER and SAM are design models that calculate the consumption of hot water and cost for a house. Some results, obtained through simulation, were for monthly energy production, annual energy production, after tax cash flow, the lifetime of the system and monthly energy usage represented by three types of energy. These are system energy, electricity load electricity and net metering credit.

Keywords: water heating, thermal storage, capital cost solar, consumption

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Authors: Christopher Battle

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The pursuit of a sustainable future is dependent on the ability of governments from the national to municipal level. The politics of energy and the development of state-sponsored photovoltaic cell expansion can nebulize in several ways based on a state or nation's physical and human geography. This study conducts a comparative analysis of the energy and solar program of Turkey, Pennsylvania, and Philadelphia. The study aims to assess the city of Philadelphia's solar policies in contrast with both its political history and the photovoltaic programs of Turkey, a world leader in solar system development, and Pennsylvania's history of energy regulation. This comparative study found that after hundreds of bills and regulations over decades, sustainable energy development in affordable housing and new construction is the next phase of State-Sponsored Green energy for the city of Philadelphia.

Keywords: Turkey, solar power, Philadelphia, affordable energy development

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Authors: Likewin Thomas, M. V. Manoj Kumar, B. Annappa

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The aim of this study was to develop an Artificial Neural Network0 s recommendation model for an online process using the complexity of load, performance, and average servicing time of the resources. Here, the proposed model investigates the resource performance using stochastic gradient decent method for learning ranking function. A probabilistic cost function is implemented to identify the optimal θ values (load) on each resource. Based on this result the recommendation of resource suitable for performing the currently executing task is made. The test result of CoSeLoG project is presented with an accuracy of 72.856%.

Keywords: ADALINE, neural network, gradient decent, process mining, resource behaviour, polynomial regression model

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Authors: Uğur Çakir, Erol Şahin, Kemal Çomakli, Ayşegül Çokgez Kuş

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Solar energy is thought as main source of all energy sources on the world and it can be used in many applications like agricultural areas, heating cooling or direct electricity production directly or indirectly. Greenhousing is the first one of the agricultural activities that solar energy can be used directly in. Greenhouses offer us suitable conditions which can be controlled easily for the growth of the plant and they are made by using a covering material that allows the sun light entering into the system. Covering material can be glass, fiber glass, plastic or another transparent element. This study investigates the solar energy usability rates and solar energy benefiting rates of a semi-spherical (modified arch) type greenhouse system according to different orientations and positions which exists under climatic conditions of Bayburt. In the concept of this study it is tried to determine the best direction and best sizes of a semi-spherical greenhouse to get best solar benefit from the sun. To achieve this aim a modeling study is made by using MATLAB. However this modeling study is running for some determined shapes and greenhouses it can be used for different shaped greenhouses or buildings. The basic parameters are determined as greenhouse azimuth angle, the rate of size of long edge to short and seasonal solar energy gaining of greenhouse.

Keywords: greenhousing, solar energy, direct radiation, renewable energy

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Authors: A. S. Zgalei, B. T. Al-Mabrouk

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With a particularly significant growth rate observed in the Libyan commercial and residential buildings coupled with a growth in energy demand, solar desiccant evaporative cooling offers energy savings and promises a good sharing for sustainable buildings where the availability of solar radiation matches with the cooling load demand. The paper presents a short introduction for the desiccant systems. A mathematical model of a selected system has been developed and a simulation has been performed in order to investigate the system performance at different working conditions and an optimum design of the system structure is established. The results showed a technical feasibility of the system working under the Libyan climatic conditions with a reasonable COP at temperatures that can be obtained through the solar reactivation system. Discussion of the results and the recommendations for future work are proposed.

Keywords: computer program, solar desiccant wheel cooling, system modelling, simulation, technical feasibility

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Authors: Ebrahim Behrouzian Nejad, Rezvan Alipoor Sabzevari

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Cloud computing systems are large-scale distributed systems, so that they focus more on large scale resource sharing, cooperation of several organizations and their use in new applications. One of the main challenges in this realm is resource allocation. There are many different ways to resource allocation in cloud computing. One of the common methods to resource allocation are economic methods. Among these methods, the auction-based method has greater prominence compared with Fixed-Price method. The double combinatorial auction is one of the proper ways of resource allocation in cloud computing. This method includes two phases: winner determination and resource allocation. In this paper a new method has been presented to determine winner in double combinatorial auction-based resource allocation using Imperialist Competitive Algorithm (ICA). The experimental results show that in our new proposed the number of winner users is higher than genetic algorithm. On other hand, in proposed algorithm, the number of winner providers is higher in genetic algorithm.

Keywords: cloud computing, resource allocation, double auction, winner determination

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Authors: Sulaiman Kassim Ibrahim

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Human Resource is one of the most important elements in any country. They are very important in actualizing the potential of every sector in the country, i.e Agric, Education, Finance, Judiciary and all formal and informal sectors. The purpose of this study is to investigate the loss of human resource in Nigeria through street begging. The study used intensive literature review. Finding from the review indicate that a significant number of human resource are into street begging in the country undeveloped and untapped. The paper recommend that policy should be initiated to discourage street begging, develop this resource through education and empowerment, stop rural-urban migration by providing infrastructure in the rural areas and abolish informal (Almajiri or beggars school) and transform it into formal school.

Keywords: human resource, street begging, Nigeria, Almajiri

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Authors: V. Nagaraju, G. Murali, Nagarjunavarma Ganna, Atluri Pavan Kalyan, N. Sree Sai Ganesh, V. S. V. S. Badrinath

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The present work focuses on the development of a mathematical model for the yield obtained by single slope solar still incorporated with cylindrical pipes filled with sand. The mathematical results obtained were validated with the experimental results for the 3 cm of water level at the basin. The mathematical model and results obtained with the experimental investigation are within 11% of deviation. The theoretical model to predict the yield obtained due to the capillary effect was proposed first. And then, to predict the total yield obtained, the thermal effect model was integrated with the capillary effect model. With the obtained results, it is understood that the yield obtained is more in the case of solar stills with sand-filled cylindrical pipes when compared to solar stills without sand-filled cylindrical pipes. And later model was used for predicting yield for 1 cm and 2 cm of water levels at the basin. And it is observed that the maximum yield was obtained for a 1 cm water level at the basin. It means solar still produces better yield with the lower depth of water level at the basin; this may be because of the availability of more space in the sand for evaporation.

Keywords: solar still, cylindrical pipes, still efficiency, mathematical modeling, capillary effect model, yield, solar desalination

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Authors: Nur Iffika Ruslan, Ahmad Rosly Abbas, Munirah Stapah@Salleh, Nurfaziera Rahim

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Increased concerns and awareness of environmental hazards by fossil fuels burning for energy have become the major factor driving the transition toward green energy. It is expected that an additional of 2,000 MW of renewable energy is to be recorded from the renewable sources by 2025 following the implementation of Large Scale Solar projects in Peninsular Malaysia, including Large Scale Floating Solar projects. Floating Solar has better advantages over its landed counterparts such as the requirement for land acquisition is relatively insignificant. As part of the site selection process established by TNB Research Sdn. Bhd., a set of mandatory and rejection criteria has been developed in order to identify only sites that are feasible for the future development of Large Scale Floating Solar power plant. There are a total of 85 lakes and reservoirs identified within Peninsular Malaysia. Only lakes and reservoirs with a minimum surface area of 120 acres will be considered as potential sites for the development of Large Scale Floating Solar power plant. The result indicates a total of 10 potential Large Scale Floating Solar sites identified which are located in Selangor, Johor, Perak, Pulau Pinang, Perlis and Pahang. This paper will elaborate on the various mandatory and rejection criteria, as well as on the various site selection process required to identify potential (suitable) Large Scale Floating Solar sites in Peninsular Malaysia.

Keywords: Large Scale Floating Solar, Peninsular Malaysia, Potential Sites, Renewable Energy

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Authors: Phichak Phutrakhul

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The purposes of this research were to study concepts and strategies of human resource development in the automotive manufacturers and to articulate the proposals against the government about the human resource development for automotive industry. In the present study, qualitative study was an in-depth interview in which the qualitative data were collected from the executive or the executive of human resource division from five automotive companies - Toyota Motor (Thailand) Co., Ltd., Nissan Motor (Thailand) Co., Ltd., Mitsubishi Motors (Thailand) Co., Ltd., Honda Automobile (Thailand) Co., Ltd., and Suzuki Motor (Thailand) Co., Ltd. Qualitative data analysis was performed by using inter-coder agreement technique. The research findings were as follows: The external factors included the current conditions of the automotive industry, government’s policy related to the automotive industry, technology, labor market and human resource development systems of the country. The internal factors included management, productive management, organizational strategies, leadership, organizational culture and philosophy of human resource development. These factors were affected to the different concept of human resources development -the traditional human resource development and the strategies of human resource development. The organization focuses on human resources as intellectual capital and uses the strategies of human resource development in all development processes. The strategies of human resource development will enhance the ability of human resources in the organization and the country.

Keywords: human resource development strategy, automotive industry, eco-cars, ASEAN

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Authors: N. J. Shanono, J. G. Ndiritu

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The poor performance of water resource systems (WRS) has been reportedly linked to not only climate variability and the water demand dynamics but also human behaviour-driven unlawful activities. Some of these unlawful activities that have been adversely affecting water sector include unauthorized water abstractions, water wastage behaviour, refusal of water re‐use measures, excessive operational losses, discharging untreated or improperly treated wastewater, over‐application of chemicals by agricultural users and fraudulent WRS operation. Despite advances in WRS planning, operation, and analysis incorporating such undesirable human activities to quantitatively assess their impact on WRS performance remain elusive. This study was then inspired by the need to develop a methodological framework for WRS performance assessment that integrates the impact of human behaviour with WRS performance assessment analysis. We, therefore, proposed a conceptual framework for assessing the impact of human behaviour on WRS performance using the concept of socio-hydrology. The framework identifies and couples four major sources of WRS-related values (water values, water systems, water managers, and water users) using three missing links between human and water in the management of WRS (interactions, outcomes, and feedbacks). The framework is to serve as a database for choosing relevant social and hydrological variables and to understand the intrinsic relations between the selected variables to study a specific human-water problem in the context of WRS management.

Keywords: conceptual framework, human behaviour; socio-hydrology; water resource systems

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Authors: Ehsan Gholamalizadeh, Jae Dong Chung

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Solar chimney power plant is a feasible solar thermal system which produces electricity from the Sun. The objective of this study is to investigate buoyancy-driven flow and heat transfer through a built pilot solar chimney system called 'Kerman Project'. The system has a chimney with the height and diameter of 60 m and 3 m, respectively, and the average radius of its solar collector is about 20 m, and also its average collector height is about 2 m. A three-dimensional simulation was conducted to analyze the system, using computational fluid dynamics (CFD). In this model, radiative transfer equation was solved using the discrete ordinates (DO) radiation model taking into account a non-gray radiation behavior. In order to modelling solar irradiation from the sun’s rays, the solar ray tracing algorithm was coupled to the computation via a source term in the energy equation. The model was validated with comparing to the experimental data of the Manzanares prototype and also the performance of the built pilot system. Then, based on the numerical simulations, velocity and temperature distributions through the system, the temperature profile of the ground surface and the system performance were presented. The analysis accurately shows the flow and heat transfer characteristics through the pilot system and predicts its performance.

Keywords: buoyancy-driven flow, computational fluid dynamics, heat transfer, renewable energy, solar chimney power plant

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Authors: Ruobing Liang, Jili Zhang, Chao Zhou

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A solar-heating-and-cooling (SHC) system, consisting of a hybrid photovoltaic/ thermal collector array, a hot water storage tank, and an absorption chiller unit is designed and modeled to satisfy thermal loads (space heating, domestic hot water, and space cooling). The system is applied for Dalian, China, a location with cold climate conditions, where cooling demand is moderate, while space heating demand is slightly high. The study investigates the potential of a solar system installed and operated onsite in a detached single-family household to satisfy all necessary thermal loads. The hot water storage tank is also connected to an auxiliary heater (electric boiler) to supplement solar heating, when needed. The main purpose of the study is to model the overall system and contact a parametric study that will determine the optimum economic system performance in terms of design parameters. The system is compared, through a cost analysis, to an electric heat pump (EHP) system. This paper will give the optimum system combination of solar collector area and volumetric capacity of the hot water storage tank, respectively.

Keywords: absorption chiller, solar PVT collector, solar heating and cooling, solar air-conditioning, parametric study, cost analysis

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Authors: Guillaume Schuchardt, Solenn Berson, Gerard Perrier

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Multi-junction solar cell configurations, where two sub-cells with complementary absorption are stacked and connected in series, offer an exciting approach to tackle the single junction limitations of organic solar cells and improve their power conversion efficiency. However, the augmentation of the number of layers has, as a consequence, to increase the risk of reducing the lifetime of the cell due to the ageing phenomena present at the interfaces. In this work, we study the intrinsic degradation mechanisms, under continuous illumination AM1.5G, inert atmosphere and room temperature, in single and tandem organic solar cells using Impedance Spectroscopy, IV Curves, External Quantum Efficiency, Steady-State Photocarrier Grating, Scanning Kelvin Probe and UV-Visible light.

Keywords: single and tandem organic solar cells, intrinsic degradation mechanisms, characterization: SKP, EQE, SSPG, UV-Visible, Impedance Spectroscopy, optical simulation

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Authors: Arun Kumar Yadav, Badam Singh Kushvah

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In the present work, we investigated displaced periodic orbits in the linear order in the circular restricted three-body Sun-Jupiter system, where the third mass-less body utilizes solar electric sail. The electric solar sail is a new space propulsion concept which uses the solar wind momentum for producing thrust, and it is somewhat like to the more well-known solar radiation pressure sail which is often called simply the solar sail. Moreover, we implement the feedback linearization control scheme to perform the stabilization and trajectory tracking for the nonlinear system. Further, we derived periodic orbits analytically in linear order by introducing a first order approximation. These approximate analytic solutions are utilized in a numerical search to determine displaced periodic orbit in the full nonlinear model. We found the displaced periodic orbit for the defined non-linear model and stabilized the model.

Keywords: solar electric sail, circular restricted three-body problem (CRTBP), displaced orbit, feedback linearization control

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Authors: Elmo Thiago Lins Cöuras Ford, Valentina Alessandra Carvalho do Vale

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A swimming pool heating system is presented, composed of two alternative collectors with serial PVC absorber tubes that work in regimen of forced stream that is gotten through a bomb. A 500 liters reservoir was used, simulating the swimming pool, being raised some data that show the viability of the considered system. The chosen outflow was corresponding to 100 l/h. In function of the low outflow it was necessary the use of a not popular bomb, choosing the use of a low outflow alternative pumping system, using an air conditioner engine with three different rotations for the desired end. The thermal data related to each collector and their developed system will be presented. The UV and thermal degradations of the PVC exposed to solar radiation will be also boarded, demonstrating the viability of using tubes of this material as absorber elements of radiation in water heating solar collectors.

Keywords: solar energy, solar swimming pool, water heating, PVC tubes, alternative system

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Authors: Xiaoting Shi, Xiaomei Ma

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In higher education, students' self-assessment and peer assessment of compositions in writing classes can effectively improve their ability of evaluative judgment. However, students' self-assessment and peer assessment are not advocated by most teachers because of the significant difference in scoring compared with teacher assessment. This study used a multi-faceted Rasch model to explore whether an English writing checklist containing 30 descriptors can effectively improve rating consistency among self-assessment, peer assessment and teacher assessment. Meanwhile, a questionnaire was adopted to survey students’ and teachers’ attitudes toward self-assessment and peer assessment using the writing checklist. Results of the multi-faceted Rasch model analysis show that the writing checklist can effectively distinguish the students’ writing ability (separate coefficient = 2.05, separate reliability = 0.81, chi-square value (df = 32) = 123.4). Moreover, the results revealed that the checklist could improve rating consistency among self-assessment, peer assessment and teacher assessment. (separate coefficient = 1.71, separate reliability = 0.75, chi-square value (df=4) = 20.8). The results of the questionnaire showed that more than 85% of students and all teachers believed that the checklist had a good advantage in self-assessment and peer assessment, and they were willing to use the checklist to conduct self-assessment and peer assessment in class in the future.

Keywords: english writing, self-assessment, peer assessment, writing checklist

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Authors: Abdulrahman M. Homadi

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This study focuses on how to control the outlet temperature of a solar air heater in a way simpler than the existing methods. In this work, five cases have been studied by using ANSYS Fluent based on a CFD numerical method. All the cases have been simulated by utilizing the same criteria and conditions like the temperature, materials, areas except the geometry. The case studies are conducted in Little Rock (LR), AR, USA during the winter time supposedly on 15^th of December. A fresh air that is flowing with a velocity of 0.5 m/s and a flow rate of 0.009 m³/s. The results prove the possibility of achieving a controlled temperature just by changing the geometric shape of the heater. This geometry guarantees that the absorber plate always has a normal component of the solar radiation at any time during the day. The heater has a sectarian shape with a radius of 150 mm where the outlet temperature remains almost constant for six hours.

Keywords: solar energy, air heater, control of temperature, CFD

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