Search results for: wind generation

Authors: Rui Yin, Haojie Wang, Xun Li

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Recently, mainstream dense retrieval methods have obtained state-of-the-art results on some datasets and tasks. However, they require large amounts of training data, which is not available in most domains. The severe performance degradation of dense retrievers on new data domains has limited the use of dense retrieval methods to only a few domains with large training datasets. In this paper, we propose an unsupervised domain-adaptive approach based on query generation. First, a generative model is used to generate relevant queries for each passage in the target corpus, and then, the generated queries are used for mining negative passages. Finally, the query-passage pairs are labeled with a cross-encoder and used to train a domain-adapted dense retriever. We also explore contrastive learning as a method for training domain-adapted dense retrievers and show that it leads to strong performance in various retrieval settings. Experiments show that our approach is more robust than previous methods in target domains that require less unlabeled data.

Keywords: dense retrieval, query generation, contrastive learning, unsupervised training

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Authors: Tarek Dandashi

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WSNs may provide a fast and reliable solution for the early detection of environment events like forest fires. This is crucial for alerting and calling for fire brigade intervention. Sensor nodes communicate sensor data to a host station, which enables a global analysis and the generation of a reliable decision on a potential fire and its location. A WSN with TinyOS and nesC for the capturing and transmission of a variety of sensor information with controlled source, data rates, duration, and the records/displaying activity traces is presented. We propose a similarity distance (SD) between the distribution of currently sensed data and that of a reference. At any given time, a fire causes diverging opinions in the reported data, which alters the usual data distribution. Basically, SD consists of a metric on the Cumulative Distribution Function (CDF). SD is designed to be invariant versus day-to-day changes of temperature, changes due to the surrounding environment, and normal changes in weather, which preserve the data locality. Evaluation shows that SD sensitivity is quadratic versus an increase in sensor node temperature for a group of sensors of different sizes and neighborhood. Simulation of fire spreading when ignition is placed at random locations with some wind speed shows that SD takes a few minutes to reliably detect fires and locate them. We also discuss the case of false negative and false positive and their impact on the decision reliability.

Keywords: forest fire, WSN, wireless sensor network, algortihm

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Authors: Neel K. Shah

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Wind tunnel tests have been performed at The University of Manchester to investigate the impact of surface grooves of a trapezoidal planform on flow separation on a symmetrical aerofoil. A spanwise array of the grooves has been applied around the maximum thickness location of the upper surface of an NACA-0015 aerofoil. The aerofoil has been tested in a two-dimensional set-up in a low-speed wind tunnel at an angle of attack (AoA) of 3° and a chord-based Reynolds number (Re) of ~2.7 x 105. A laminar separation bubble developed on the aerofoil at low AoA. It has been found that the grooves shorten the streamwise extent of the separation bubble by shedding a pair of counter-rotating vortices. However, the increase in leading-edge suction due to the shorter bubble is not significant since the creation of the grooves results in a decrease of surface curvature and an increase in blockage (increase in surface pressure). Additionally, the increased flow mixing by the grooves thickens the boundary layer near the trailing edge of the aerofoil also contributes to this limitation. As a result of these competing effects, the improvement in the pressure-lift and pressure-drag coefficients are small, i.e., by ~1.30% and ~0.30%, respectively, at 3° AoA. Crosswire anemometry shows that the grooves increase turbulence intensity and Reynolds stresses in the wake, thus indicating an increase in viscous drag.

Keywords: aerofoil flow control, flow separation, grooves, vortices

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Authors: Ali Riza Perçin, Eser Bingül

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Internet technologies have created opportunities with which people share their ideologies, thoughts and products. This virtual world, named social media has given the chance of gathering individual users and people from the world's remote locations and establishing an interaction between them. However, to an increasingly higher degree terrorist organizations today use the internet and most notably social-network media to create the effects they desire through a series of on-line activities. These activities, designed to support their activities, include information collection (intelligence), target selection, propaganda, fundraising and recruitment to name a few. Meanwhile, these have been used as the most important tool for recruitment especially from the different region of the world, especially disenfranchised youth, in the West in order to mobilize support and recruit “foreign fighters.” The recruits have obtained the statue, which is not accessible in their society and have preferred the style of life that is offered by the terrorist organizations instead of their current life. Like other terrorist groups, for a while now the terrorist organization Islamic State (IS) in Iraq and Syria has employed a social-media strategy in order to advance their strategic objectives. At the moment, however, IS seems to be more successful in their on-line activities than other similar organizations. IS uses social media strategically as part of its armed activities and for the sustainability of their military presence in Syria and Iraq. In this context, “Generation Y”, which could exist at the critical position and undertake active role, has been examined. Additionally, the explained characteristics of “Generation Y” have been put forward and the duties of families and society have been stated as well.

Keywords: social media, "generation Y", terrorist organization, islamic state IS

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Authors: Diyono Harun

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Indonesia aims to reduce carbon emissions from energy generation by reaching 23% and 31% of the national energy supply from renewable energy sources (RES) in 2025 and 2030. The potential for RES in Indonesia is enormous, but not all province has the same potential for RES. Yogyakarta, one of the most travel-destinated provinces in Indonesia, has less potential than its neighbour, Central Java. Consequently, Yogyakarta must meet its electricity demand by importing electricity from Central Java if this province only wants to use electricity from RES. Thus, achieving the objective is balancing the electricity supply between an importer (Yogyakarta) and an exporter province (Central Java). This research aims to explore the RES potential and the current capacity of RES for electricity generation in both provinces. The results show that the present capacity of RES meets the annual domestic electricity demand in both provinces only with an extension of the RES potential. The renewable energy mixes in this research also can lower CO2 emissions compared to gas-fired power plants. This research eventually provides insights into exploring and using the domestic RES potentials between two areas with different RES capacities.

Keywords: energy mix, renewable energy sources, domestic electricity, electricity generation

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Authors: Minjung Maing, Sibei Liu

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This research discusses the results of a study of window opening behavior of large housing developments in the high-density megacity of Hong Kong. The methods used for the study involved field observations using photo documentation of the four cardinal elevations (north, south-east, and west) of two large housing developments in a very dense urban area of approx. 46,000 persons per square meter within the city of Hong Kong. The targeted housing developments (A and B) are large public housing with a population of about 13,000 in each development of lower income. However, the mean income level in development A is about 40% higher than development B and home ownership is 60% in development A and 0% in development B. Mapping of the surrounding amenities and layout of the developments were also studied to understand the available activities to the residents. The photo documentation of the elevations was taken from November 2016 to February 2018 to gather a full spectrum of different seasons and both in the morning and afternoon (am/pm) times. From the photograph, the window opening behavior was measured by counting the amount of windows opened as a percentage of all the windows on that façade. For each date of survey data collected, weather data was recorded from weather stations located in the same region to collect temperature, humidity and wind speed. To further understand the behavior, simulation studies of microclimate conditions of the housing development was conducted using the software ENVI-met, a widely used simulation tool by researchers studying urban climate. Four major conclusions can be drawn from the data analysis and simulation results. Firstly, there is little change in the amount of window opening during the different seasons within a temperature range of 10 to 35 degrees Celsius. This means that people who tend to open their windows have consistent window opening behavior throughout the year and high tolerance of indoor thermal conditions. Secondly, for all four elevations the lower-income development B opened more windows (almost two times more units) than higher-income development A meaning window opening behavior had strong correlations with income level. Thirdly, there is a lack of correlation between outdoor horizontal wind speed and window opening behavior, as the changes of wind speed do not seem to affect the action of opening windows in most conditions. Similar to the low correlation between horizontal wind speed and window opening percentage, it is found that vertical wind speed also cannot explain the window opening behavior of occupants. Fourthly, there is a slightly higher average of window opening on the south elevation than the north elevation, which may be due to the south elevation being well shaded from high angle sun during the summer and allowing heat into units from lower angle sun during the winter season. These findings are important to providing insight into how to better design urban environments and indoor thermal environments for a liveable high density city.

Keywords: high-density housing, subtropical climate, urban behavior, window opening

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Authors: Sallah S. El-Ammari, Mona. S. Hasan

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This research is aimed to study allelopathic effects of two wind breakers Eucalyptus camaldulensis and E.gomphocephala on germination and growth of barley using aqueous extracts of leaves at 0.5, 1, 5, and 10% concentrations for treatment of barley caryopsis in petri dishes incubated in growth chamber. Distilled water was used in the experiment as a control. Seed germination was recorded on daily basis for five days. After ten days measurements of root length, shoot length, fresh and dry weight of root and shoot were taken. With the exception of 0.5% E. gomphocephala extract effect on length and dry weight of barley root, all the tested extract concentrations for both eucalyptus species significantly decreased the percent and speed of germination, root and shoot length, fresh and dry weight of root and shoot of barley compared to the control. For both species the allelopathic effect was significantly increasing with the increase of the extract concentration. Although, higher allelopathic effect was shown by E. camaldulensis, the results indicating that both eucalyptus species should not be recommended as wind breakers for barley fields.

Keywords: allelopathy, eucalyptus, barley, Libya

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Authors: M. S. M. Anjalee Umesha Bandara

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Hela Veda Shastra is a science that is an endowment from generation to generation. There is also an individualistic science and indigenous practice of traditional herbs. There are many effective cures for snakes, fractures, head cancer, cuts, lunatics, reflexology, etc. Hela physicians who rescued them from infections caused by snakes have recognized poems to remember the medicines they used to cure the patients. Due to the harmony of the Hela Osu and Hela Knowledge poetry collection, it has become easy for the juniors of the Hela Veda generation to gain medical knowledge. It is a research problem whether it is possible to arrive at a correct conclusion about the patient form of the snake information thread through the existing Dhuta characteristics of Hela Serpa Vedakam. This research was done with the assumption that snake venom can be successfully treated according to its characteristics. In this research, two generations related to the Ratmalavatiya Vedaparamparava and the Vannihatpattu of the Kalla Veda generation have been identified as Veda Paramparas who treat and created Dutha Kavya, including the form of the Serpent Dasthana. They have collected ancient books, documents and interviews related to qualitative research on snake disease treatment. In addition, collecting data by referring to books related to Hela medicine. The ancient indigenous lineage methods that are superior to modern Western science's snake therapy should save the Hela's amazing wealth of wisdom for the future, leaving aside the selfishness of keeping the teaching to themselves.

Keywords: snake venom medicine, vedic genealogy, Dhuta characteristic, snake

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Authors: Magri Hicham, Noreddine Abghour, Mohamed Ouzzif

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The 5th generation of mobile networks is term used in various research papers and projects to identify the next major phase of mobile telecommunications standards. 5G wireless networks will support higher peak data rate, lower latency and provide best connections with QoS guarenty. In this article, we discuss various promising technologies for 5G wireless communication systems, such as IPv6 support, World Wide Wireless Web (WWWW), Dynamic Adhoc Wireless Networks (DAWN), BEAM DIVISION MULTIPLE ACCESS (BDMA), Cloud Computing and cognitive radio technology.

Keywords: WWWW, BDMA, DAWN, 5G, 4G, IPv6, Cloud Computing

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Authors: Aparna Viswanath

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Electricity spot prices are highly volatile under optimal generation capacity scenarios due to factors such as non-storability of electricity, peak demand at certain periods, generator outages, fuel uncertainty for renewable energy generators, huge investments and time needed for generation capacity expansion etc. As a result market participants are exposed to price and volume risk, which has led to the development of risk management practices. This paper provides an overview of risk management practices by market participants in electricity markets using financial derivatives.

Keywords: financial derivatives, forward, futures, options, risk management

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Authors: Bachir Bentouati, Lakhdar Chaib, Saliha Chettih, Gai-Ge Wang

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The problem of economic dispatch (ED) is the basic problem of power framework, its main goal is to find the most favorable generation dispatch to generate each unit, reduce the whole power generation cost, and meet all system limitations. A heuristic algorithm, recently developed called Stud Krill Herd (SKH), has been employed in this paper to treat non-convex ED problems. The proposed KH has been modified using Stud selection and crossover (SSC) operator, to enhance the solution quality and avoid local optima. We are demonstrated SKH effects in two case study systems composed of 13-unit and 40-unit test systems to verify its performance and applicability in solving the ED problems. In the above systems, SKH can successfully obtain the best fuel generator and distribute the load requirements for the online generators. The results showed that the use of the proposed SKH method could reduce the total cost of generation and optimize the fulfillment of the load requirements.

Keywords: stud krill herd, economic dispatch, crossover, stud selection, valve-point effect

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Authors: Junjie Wu, Hongjuan Hou, Eric Hu, Yongping Yang

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Solar aided power generation (SAPG) technology has been proven as an efficient way to make use of solar energy for power generation purpose. In an SAPG plant, a solar field consisting of parabolic solar collectors is normally used to supply the solar heat in order to displace the high pressure/temperature extraction steam. To understand the performance of such a SAPG plant, a new simulation model was developed by the authors recently, in which the boiler was treated, as a series of heat exchangers unlike other previous models. Through the simulations using the new model, it was found the outlet properties of reheated steam, e.g. temperature, would decrease due to the introduction of the solar heat. The changes make the (lower stage) turbines work under off-design condition. As a result, the whole plant’s performance may not be optimal. In this paper, the second solar filed was proposed to increase the inlet temperature of steam to be reheated, in order to bring the outlet temperature of reheated steam back to the designed condition. A 600MW SAPG plant was simulated as a case study using the new model to understand the impact of the second solar field on the plant performance. It was found in the study, the 2nd solar field would improve the plant’s performance in terms of cycle efficiency and solar-to-electricity efficiency by 1.91% and 6.01%. The solar-generated electricity produced by per aperture area under the design condition was 187.96W/m2, which was 26.14% higher than the previous design.

Keywords: solar-aided power generation system, off-design performance, coal-saving performance, boiler modelling, integration schemes

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Authors: Muhammad Minhaj Khan, Jaemin Lee, Suhong Lee, Jinyoung Chung, Johoo Whang

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The Republic of Korea has been facing strong storage crisis from nuclear waste generation as At Reactor (AR) temporary storage sites are about to reach saturation. Since the country is densely populated with a rate of 491.78 persons per square kilometer, Construction of High-level waste repository will not be a feasible option. In order to tackle the storage waste generation problem which is increasing at a rate of 350 tHM/Yr. and 380 tHM/Yr. in case of 20 PWRs and 4 PHWRs respectively, the study strongly focuses on the advancement of current nuclear power plants to GEN-IV sustainable and ecological nuclear systems by burning TRUs (Pu, MAs). First, Calculations has made to estimate the generation of SNF including Pu and MA from PWR and PHWR NPPS by using the IAEA code Nuclear Fuel Cycle Simulation System (NFCSS) for the period of 2016, 2030 (including the saturation period of each site from 2024~2028), 2089 and 2109 as the number of NPPS will increase due to high import cost of non-nuclear energy sources. 2ndly, in order to produce environmentally sustainable nuclear energy systems, 4 scenarios to burnout the Plutonium and MAs are analyzed with the concentration on burning of MA only, MA and Pu together by utilizing SFR, LFR and KALIMER-600 burner reactor after recycling the spent oxide fuel from PWR through pyro processing technology developed by Korea Atomic Energy Research Institute (KAERI) which shows promising and sustainable future benefits by minimizing the HLW generation with regard to waste amount, decay heat, and activity. Finally, With the concentration on front and back end fuel cycles for open and closed fuel cycles of PWR and Pyro-SFR respectively, an overall assessment has been made which evaluates the quantitative as well as economical combativeness of SFR metallic fuel against PWR once through nuclear fuel cycle.

Keywords: GEN IV nuclear fuel cycle, nuclear waste, waste sustainability, transmutation

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Authors: Negar Sartipzadeh

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Energy-conscious design, which coordinates with the Earth ecological systems during its life cycle, has the least negative impact on the environment with the least waste of resources. Due to the increasing in world population as well as the consumption of fossil fuels that cause the production of greenhouse gasses and environmental pollution, mankind is looking for renewable and also sustainable energies. The Iranian native construction is a clear evidence of energy-aware designing. Our predecessors were forced to rely on the natural resources and sustainable energies as well as environmental issues which have been being considered in the recent world. One of these endless energies is wind energy. Iranian traditional architecture foundations is a appropriate model in solving the environmental crisis and the contemporary energy. What will come in this paper is an effort to recognition and introduction of the unique characteristics of the Iranian architecture in the application of aerodynamic and hydraulic energies derived from the wind, which are the most common and major type of using sustainable energies in the traditional architecture of Iran. Therefore, the recent research attempts to offer a hybrid system suggestions for application in new constructions designing in a region such as Nashtifan, which has potential through reviewing windmills and how they deal with sustainable energy sources, as a model of Iranian native construction.

Keywords: renewable energy, sustainable building, windmill, Iranian architecture

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Authors: J. Karthik, G. Vinayagamurthy

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Aerodynamic flow control is achieved by interaction of flowing medium with corresponding structure so that its natural flow state is disturbed to delay the transition point. This paper explains the aerodynamic effect and optimized design of Vortex Generators on the turbine blade to achieve maximum flow control. The airfoil is chosen from NREL [National Renewable Energy Laboratory] S-series airfoil as they are characterized with good lift characteristics and lower noise. Vortex generators typically chosen are Ogival, Rectangular, Triangular and Tapered Fin shapes attached near leading edge. Vortex generators are typically distributed from the primary to tip of the blade section. The design wind speed is taken as 6m/s and the computational analysis is executed. The blade surface is simulated using k- ɛ SST model and results are compared with X-FOIL results. The computational results are validated using Wind Tunnel Testing of the blade corresponding to the design speed. The effect of Vortex generators on the flow characteristics is studied from the results of analysis. By comparing the computational and test results of all shapes of Vortex generators; the optimized design is achieved for effective flow control corresponding to the blade.

Keywords: flow control, vortex generators, design optimisation, CFD

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Authors: B. M. Alshammari, M. A. El-Kady

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This paper presents a unified framework for assessment of reserve-based reliability levels in electric power systems. The unified approach is based on reserve-based analysis and assessment of the relationship between available generation capacities and required demand levels. The developed approach takes into account the load variations as well as contingencies which occur randomly causing some generation and/or transmission capacities to be lost (become unavailable). The calculated reserve based indices, which are important to assess the reserve capabilities of the power system for various operating scenarios are therefore probabilistic in nature. They reflect the fact that neither the load levels nor the generation or transmission capacities are known with absolute certainty. They are rather subjects to random variations and consequently. The calculated reserve-based reliability indices are all subjects to random variations where only expected values of these indices can be evaluated. This paper presents a unified approach to reserve-based reliability assessment of power systems using various reserve assessment criteria. Practical applications are also presented for demonstration purposes to the Saudi electricity power grid.

Keywords: assessment, power system, reserve, reliability

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Authors: Mohsen Sheikholeslami, Zahra Khalili, Ladan Momayez

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Impacts of environmental parameters and dust deposition on the efficiency of solar panel have been scrutinized in this article. To gain thermal output, trapezoidal cooling channel has been attached in the bottom of the panel incorporating ternary nanofluid. To produce working fluid, water has been mixed with Fe₃O₄-TiO₂-GO nanoparticles. Also, the arrangement of fins has been considered to grow the cooling rate of the silicon layer. The existence of a thermoelectric layer above the cooling channel leads to higher electrical output. Efficacy of ambient temperature (Ta), speed of wind (V𝓌ᵢₙ𝒹) and inlet temperature (Tᵢₙ) and velocity (Vin) of ternary nanofluid on performance of PVT has been assessed. As Tin increases, electrical efficiency declines about 3.63%. Increase of ambient temperature makes thermal performance enhance about 33.46%. The PVT efficiency decreases about 13.14% and 16.6% with augment of wind speed and dust deposition. CO₂ mitigation has been reduced about 15.49% in presence of dust while it increases about 17.38% with growth of ambient temperature.

Keywords: photovoltaic system, CO₂ mitigation, ternary nanofluid, thermoelectric generator, environmental parameters, trapezoidal cooling channel

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Authors: William Fuentes, Melany Gil

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Numerical simulations of offshore wind turbines (OWTs) in shallow waters demand sophisticated models considering the cyclic nature of the environmental loads. For the case of an OWT founded on sands, rapid loading may cause a reduction of the effective stress of the soil surrounding the structure. This eventually leads to its settlement, tilting, or other issues affecting its serviceability. In this work, a 3D FE model of an OWT founded on sand is constructed and analyzed. Cyclic loading with different histories is applied at certain points of the tower to simulate some environmental forces. The mechanical behavior of the soil is simulated through the recently proposed ISA-hypoplastic model for sands. The Intergranular Strain Anisotropy ISA can be interpreted as an enhancement of the intergranular strain theory, often used to extend hypoplastic formulations for the simulation of cyclic loading. In contrast to previous formulations, the proposed constitutive model introduces an elastic range for small strain amplitudes, includes the cyclic mobility effect and is able to capture the cyclic behavior of sands under a larger number of cycles. The model performance is carefully evaluated on the FE dynamic analysis of the OWT.

Keywords: offshore wind turbine, monopile, ISA, hypoplasticity

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Authors: James O'Farrell, Carla Weaver

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This paper examines the transformative impact of technology in higher education, particularly in the context of the post-pandemic era, focusing on the learning needs of Digital Natives (Generation Z and Generation Alpha who grew up in the digital age). The study explores how the Covid-19 pandemic accelerated the transition to online and blended learning, highlighting the challenges and opportunities this shift presented. It delves into various technological tools such as learning management systems, collaboration technologies, video platforms, game-based learning and gamification, digital libraries, and artificial intelligence, and their role in enhancing educational delivery and student engagement. The paper also addresses the need to support faculty, predominantly comprised of Digital Immigrants (people who grew up before the digital age) to integrate these technologies effectively into their teaching practices. The findings reveal that while technology has significantly improved the flexibility and accessibility of education, it also requires educators to adapt to the changing needs of Digital Natives and the evolving educational landscape. Moreover, the paper underscores the importance of safeguarding the mental health and well-being of both faculty and students, acknowledging the stress and anxiety brought about by the rapid shift in teaching and learning modalities. The study concludes with recommendations for educational institutions to create a balanced, inclusive, and supportive learning environment. This involves continuous faculty development, prioritizing mental health, and leveraging technology to bridge generational divides, thus paving the way for a resilient and innovative future in higher education.

Keywords: generation alpha, generation z, teaching strategies, technology

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Authors: Amir B. Khoshnevis, Morteza Mirhosseini

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The paper deals with a sub-part of an extensive research program on the wake survey method in various Reynolds numbers and angles of attack. This research experimentally investigates the wake flow characteristics behind S823 and S822 airfoils in which designed for small wind turbines. Velocity measurements determined by using hot-wire anemometer. Data acquired in the wake of the airfoil at locations(c is the chord length): 0.01c - 3c. Reynolds number increased due to increase of free stream velocity. Results showed that mean velocity profiles depend on the angle of attack and location of data collections. Data acquired at the low Reynolds numbers (smaller than 10^5). Effects of Reynolds numbers on the mean velocity profiles are more significant in near locations the trailing edge and these effects decrease by taking distance from trailing edge toward downstream. Mean velocity profiles region increased by increasing the angle of attack, except for 7°, and also the maximum velocity deficit (velocity defect) increased. The difference of mean velocity in and out of the wake decreased by taking distance from trailing edge, and mean velocity profile become wider and more uniform.

Keywords: angle of attack, Reynolds number, velocity deficit, separation

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Authors: Mariem Saied, Jens Gustedt, Gilles Muller

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We present Dido, a source-to-source auto-generation and optimization framework for multi-dimensional stencil computations. It enables a large programmer community to easily and safely implement stencil codes on distributed-memory parallel architectures with Ordered Read-Write Locks (ORWL) as an execution and communication back-end. ORWL provides inter-task synchronization for data-oriented parallel and distributed computations. It has been proven to guarantee equity, liveness, and efficiency for a wide range of applications, particularly for iterative computations. Dido consists mainly of an implicitly parallel domain-specific language (DSL) implemented as a source-level transformer. It captures domain semantics at a high level of abstraction and generates parallel stencil code that leverages all ORWL features. The generated code is well-structured and lends itself to different possible optimizations. In this paper, we enhance Dido to handle both Jacobi and Gauss-Seidel grid traversals. We integrate temporal blocking to the Dido code generator in order to reduce the communication overhead and minimize data transfers. To increase data locality and improve intra-node data reuse, we coupled the code generation technique with the polyhedral parallelizer Pluto. The accuracy and portability of the generated code are guaranteed thanks to a parametrized solution. The combination of ORWL features, the code generation pattern and the suggested optimizations, make of Dido a powerful code generation framework for stencil computations in general, and for distributed-memory architectures in particular. We present a wide range of experiments over a number of stencil benchmarks.

Keywords: stencil computations, ordered read-write locks, domain-specific language, polyhedral model, experiments

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Authors: R. S. Hassani, S. Chikh, L. Tadrist, S. Radev

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A bubbly flow in a vertical miniature tube is analyzed theoretically. The liquid and gas phase are co-current flowing upward. The gas phase is injected via a nozzle whose inner diameter is 0.11mm and it is placed on the axis of the tube. A force balance is applied on the bubble at its detachment. The set of governing equations are solved by use of Mathematica software. The bubble diameter and the bubble generation frequency are determined for various inlet phase velocities represented by the inlet mass quality. The results show different behavior of bubble growth and detachment depending on the tube size.

Keywords: two phase flow, bubble growth, mini-channel, generation frequency

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Authors: Tauhidur Rahman, Dhrubajyoti Thakuria

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In this article, vibration caused by earthquake excitation, wind load and the high-speed vehicle in the superstructure has been studied. An attempt has been made to control these vibrations using passive Tuned Mass Dampers (TMD). Tuned mass damper consists of a mass, spring, and viscous damper which dissipates the vibration energy of the primary structure at the damper of the TMD. In the present paper, the concrete box girder bridge superstructure is considered and is modeled using MIDAS software. The bridge is modeled as Euler-Bernoulli beam to study the responses imposed by high-speed vehicle, earthquake excitation and wind load. In the present study, comparative study for the responses has been done considering different velocities of the train. The results obtained in this study are based on Indian standard loadings specified in Indian Railways Board (Bridge Rules). A comparative study has been done for the responses of the high-speed vehicle with and without Tuned Mass Dampers. The results indicate that there is a significant reduction in displacement and acceleration in the bridge superstructure when Tuned Mass Damper is used.

Keywords: bridge superstructure, high speed vehicle, tuned mass damper, TMD, vibration control

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Authors: Chih-Hua Chang

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This study uses a three-dimensional (3D) fully nonlinear model to simulate the wave generation problem caused by the movement of the seabed. The numerical model is first simplified into two dimensions and then compared with the existing two-dimensional (2D) experimental data and the 2D numerical results of other shallow-water wave models. Results show that this model is different from the earlier shallow-water wave models, with the phase being closer to the experimental results of wave propagation. The results of this study are also compared with those of the 3D experimental results of other researchers. Satisfactory results can be obtained in both the waveform and the flow field. This study assesses the application of the model to simulate the wave caused by the circular (radius r0) terrain rising or falling (moving distance bm). The influence of wave-making parameters r0 and bm are discussed. This study determines that small-range (e.g., r0 = 2, normalized by the static water depth), rising, or sinking terrain will produce significant wave groups in the far field. For large-scale moving terrain (e.g., r0 = 10), uplift and deformation will potentially generate the leading solitary-like waves in the far field.

Keywords: seismic wave, wave generation, far-field waves, seabed deformation

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Authors: Lamiche Chaabane

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In this study, a new method for solving sequence alignment problem is proposed, which is named ITS (Improved Tabu Search). This algorithm is based on the classical Tabu Search (TS). ITS is implemented in order to obtain results of multiple sequence alignment. Several ideas concerning neighbourhood generation, move selection mechanisms and intensification/diversification strategies for our proposed ITS is investigated. ITS have generated high-quality results in terms of measure of scores in comparison with the classical TS and simple iterative search algorithm.

Keywords: multiple sequence alignment, tabu search, improved tabu search, neighbourhood generation, selection mechanisms

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Authors: Ater Amogpai

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Hydropower and solar photovoltaic (PV) generation are crucial in sustainability and transitioning from fossil fuel to clean energy. Integrating renewable energy sources such as hydropower and solar photovoltaic (PV) into the distributed networks contributes to achieving energy balance, pollution mitigation, and cost reduction. Frequent power outages and a lack of load reliability characterize the current South Sudan electricity distribution system. The country’s electricity demand is 300MW; however, the installed capacity is around 212.4M. Insufficient funds to build new electricity facilities and expand generation are the reasons for the gap in installed capacity. The South Sudan Ministry of Energy and Dams gave a contract to an Egyptian Elsewedy Electric Company that completed the construction of a solar PV plant in 2023. The plant has a 35 MWh battery storage and 20 MW solar PV system capacity. The construction of Juba Solar PV Park started in 2022 to increase the current installed capacity in Juba City to 53 MW. The plant will begin serving 59000 residents in Juba and save 10,886.2t of carbon dioxide (CO2) annually.

Keywords: renewable energy, hydropower, solar energy, photovoltaic, South Sudan

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Authors: Naci Büyükkaracığan, Murat Ahmet Ökmen

Abstract:

In parallel with the population growth rate, the need of human being for energy sources in the world is gradually increasing incessant. The addition of this situation that demand for energy will be busier in the future, industrialization, the rise in living standards and technological developments, especially in developing countries. Alternative energy sources have aroused interest due to reasons such as serious environmental issues that were caused by fossil energy sources, potentially decreasing reserves, different social, political and economic problems caused by dependency on source providing countries and price instability. Especially in developed countries as European countries and also U.S.A particularly, alternative energy sources such as wind, geothermal, solar and biomass energy, hydrolic and hydrogen have been utilized in different forms, especially in electricity production. It includes a review of technical and environmental factors for energy sources that are potential replacements for fossil fuels and examines their fitness to supply the energy for a high standard of living on a worldwide basis. Despite all developments, fossil energy sources have been overwhelmingly used all around the world in primary energy sources consumption and they will outnumber other energy sources in the short term. Today, parallel to population growth and economy in Turkey, energy sources consumption is increasingly continuing. On one side, Turkey, currently 80% dependent on energy providing countries, has been heavily conducting fossil energy sources raw material quest within its own borders in order to lower the percentage, and the other side, there have been many researches for exploring potential of alternative energy sources and utilization. This case will lead to both a decrease in foreign energy dependency and a variety of energy sources. This study showed the current energy potential of Turkey and presents historical development of these energy sources and their share in electricity production. The research also seeked for answers to arguments that if the potential can be sufficient in the future. As a result of this study, it was concluded that observed geothermal energy, particularly active tectonic regions of Turkey, to have an alternative energy potential could be considered to be valuable on bass wind and solar energy.

Keywords: alternative energy sources, energy productions, hydroenergy, solar energy, wind energy

Procedia PDF Downloads 631

Authors: Waseim Ragab Azzam Ahmed Mohamed Nasr, Aalaa Ibrahim Khater

Abstract:

Torsional loads from offshore wind turbines, waves, wind, earthquakes, ship collisions in the maritime environment, and electrical transmission towers might affect the pile foundations. Torsional loads can also be caused by the axial load from the sustaining structures. The paper introduces the finned pile, an alternative method of pile modification. The effects of torsional loads were investigated through a series of experimental tests aimed at improving the torsional capacity of a single pile in the sand (where sand was utilized in a state of medium density (Dr = 50%), with or without fins. In these tests, the fins' length, width, form, and number were varied to see how these attributes affected the maximum torsional capacity of the piles. We have noticed the torsion-rotation reaction. The findings demonstrated that the fins improve the maximum torsional capacity of the piles. It was demonstrated that a length of 0.6 times the embedded pile's length and a width equivalent to the pile's diameter constitute the optimal fin geometry. For the conventional pile and the finned pile, the maximum torsional capacities were determined to be 4.12 N.m. and 7.36 N.m., respectively. When subjected to torsional loads, the fins' presence enhanced the piles' maximum torsional capacity by almost 79%.

Keywords: clean sand, finned piles, model tests, torsional load

Procedia PDF Downloads 70

Authors: Pawitchaya Srijaiwong, Surin Khomfoi

Abstract:

There are several solutions to supply electricity to an island in Thailand such as diesel generation, submarine power cable, and renewable energy power generation. However, each alternative has its own limitation like fuel and pollution of diesel generation, submarine power cable length resulting in loss of cable and cost of investment, and potential of renewable energy in the local area. This paper shows microgrid system which is a new alternative for power supply to an island. It integrates local power plant from renewable energy, energy storage system, and microgrid controller. The suitable renewable energy power generation on an island is selected from geographic location and potential evaluation. Thus, photovoltaic system and hydro power plant are taken into account. The capacity of energy storage system is also estimated by transient stability study in order to supply electricity demand sufficiently under normal condition. Microgrid controller plays an important role in conducting, communicating and operating for both sources and loads on an island so that its functions are discussed in this study. The conceptual design of microgrid operation is investigated in order to analyze the reliability and power quality. The result of this study shows that microgrid is able to operate in parallel with the main grid and in case of islanding. It is applicable for electricity supply to an island and a remote area. The advantages of operating microgrid on an island include the technical aspect like improving reliability and quality of power system and social aspects like outage cost saving and CO₂ reduction.

Keywords: energy storage, islanding, microgrid, renewable energy

Procedia PDF Downloads 329

Authors: Jyoti Wadhwa, Arvinder Singh

Abstract:

This work presents the theoretical investigation of an enhanced second-harmonic generation of higher-order Gaussian laser beam in plasma having a density ramp. The mechanism responsible for the self-focusing of a laser beam in plasma is considered to be the relativistic mass variation of plasma electrons under the effect of a highly intense laser beam. Using the moment theory approach and considering the Wentzel-Kramers-Brillouin approximation for the non-linear Schrodinger wave equation, the differential equation is derived, which governs the spot size of the higher-order Gaussian laser beam in plasma. The nonlinearity induced by the laser beam creates the density gradient in the background plasma electrons, which is responsible for the excitation of the electron plasma wave. The large amplitude electron plasma wave interacts with the fundamental beam, which further produces the coherent radiations with double the frequency of the incident beam. The analysis shows the important role of the different modes of higher-order Gaussian laser beam and density ramp on the efficiency of generated harmonics.

Keywords: density rippled plasma, higher order Gaussian laser beam, moment theory approach, second harmonic generation.

Procedia PDF Downloads 181