Enhanced MIMO-DCT-OFDM System Using Cosine Domain Equalizer

Discrete Cosine Transform (DCT) can be used instead of conventional Discrete Fourier Transform (DFT) for the Orthogonal Frequency Division Multiplexing (OFDM) construction, which offers many advantages. In this paper, the Multiple-Input-Multiple-Output (MIMO) DCT-OFDM is enhanced using a proposed Cosine Domain Equalizer (CDE) instead of a Frequency Domain Equalizer (FDE). The results are evaluated through the Rayleigh fading channel with Co-Carrier Frequency Offset (Co-CFO) of different MIMO configurations. The average bit error probability and the simulated time of the proposed scheme and the conventional one is compared, which indicates the importance of the proposed scheme. Also, a closed formula for the number of arithmetic operations of the proposed equalizer is developed. The proposed equalizer gives a simulation time reduction of about 81.21%, 83.74% compared to that of the conventional LZF-FDE, and LMMSE-FDE, respectively for the case of 4x4 configuration

Modelling and Experimental Characterization of Photovoltaic/Thermal Systems for Cooling and Heating of Buildings in different climate conditions

La integración de sistemas de fotovoltaicos/térmicos (PV/T) y un eficiente aire acondicionado en los edificios permite el suministro de calefacción, refrigeración y electricidad con una reducción de las emisiones de efecto invernadero. Las configuraciones de integración de: a) sistemas fotovoltaicos (PV) con enfriadores eléctricos refrigerados por aire y sistemas de bombas de calor aire-agua; b) sistemas fotovoltaicos/térmicos (PV/T) basados en aire con sistemas de bomba de calor aire-agua; y c) Los sistemas fotovoltaicos/térmicos de baja concentración (LCPV/T) con enfriadores de compresión y absorción tienen un gran potencial para aumentar la proporción de electricidad fotovoltaica in situ. La flexibilidad de incorporar energía LCPV/T para la red bidireccional de baja temperatura en distritos urbanos reduce las pérdidas térmicas y proporciona edificios de productores y consumidores (prosumidores). En comparación con la configuración típica del enfriador de compresión integrado fotovoltaico, la configuración propuesta de LCPV/T junto con los enfriadores de compresión y absorción reduce el período de recuperación en un 10-40% en el edificio de cajas en El Cairo. Sustituir la conexión a la red de agua del campus por el uso de bomba de calor reversible reduce en un 15-30% el coste operativo de refrigeración y calefacción en el edificio de cajas en España.The integration of photovoltaic/thermal (PV/T) and efficient air conditioning systems into buildings allows the provision of heating, cooling and electricity with a reduction in greenhouse emissions. The integration configurations of: a) photovoltaic (PV) systems with air-cooled electric chillers and air-to-water heat pump (HP) systems; b) air-based PV/T systems with air-to-water HP systems; c) Low concentrated photovoltaic/thermal systems (LCPV/T) with compression and absorption chillers; and d) LCPV/T coupled with water-to-water HP have a great potential in boosting the share of onsite PV-electricity. The flexibility of incorporating LCPV/T energy for the bidirectional low temperature network in urban districts reduces thermal losses and provides producer and consumer (prosumer) buildings. In comparison to the typical configuration of PV integrated compression chiller, the proposed configuration of LCPV/T coupled with the compression and absorption chillers reduces the payback period by 10-40% in the case building in Cairo. Substituting the connection to the campus water network with the use of reversibl

Toward Effective Gamification: Lebanese Post-Secondary Students’ Perceptions on the Influence of Game Elements on Motivation to Learn

Motivation has been a topic of vast interest in the realm of education for close to four decades. Technological advancements have paved way for concepts such as gamification, a strategy intended to address motivation and engagement with learning, in the world of computerized learning. Notwithstanding, it has not yet been determined precisely what game elements work best to motivate learners when gamifying educational content, and if different types of students prefer certain game elements amongst others. In efforts to investigate those areas, this thesis explores, via surveys, the perceptions of 42 Lebanese post-secondary students on the influence of a specific set of game elements on Keller’s (1987) four components of motivation: attention, relevance, confidence, and satisfaction. Preliminary results showed that the participants perceived an overall positive influence of the selected game elements on motivation. Further analysis revealed that stories and narration topped the list as the most influential game elements on motivation. Minor differences were found in the perceptions of different types of students in terms of their age, gender, level of studies, and the hours they spend gaming per day. Keywords: game elements, gamification, motivatio

Soil types and their relations with radon concentration levels in Middle Governorate of Gaza Strip, Palestine

Determination of natural radioactivity has been carried out in surface and core agricultural soil samples collected from various sites in the Middle Governorate – Gaza Strip, Palestine. Mechanical and chemical analysis has been done to determine soil characteristics. Radon activity concentration measurements were carried out using solid state nuclear tracks detectors, Cr-39. The mechanical analysis results show that they belong to two classes, sandy loam and loamy sand. The sandy loam soil was observed in the eastern side of the study area, whereas the loamy sand was observed in western and middle parts. The radon concentration levels were higher in core samples and were proportionate to the soil depth. Also they were higher in sandy loam than loamy sand soil samples. The radon concentration levels had a positive correlation with fine grains (clay- to silt-size) of soil sample which translocated from upper to lower horizons of soil during its development. Additionally, there was a positive correlation with pH and water content, whereas a negative correlation was observed with organic matter and potassium contents. The positive correlation referred to a large specific surface of fine grains which were located in lower horizons of soil and were able to adsorb more water and consequently led to high radon concentration levels

The right of individuals to take judicial action against international persons : the case of NATO's intervention in Libya

Peer reviewedPublisher PD

Communication-Efficient Federated Learning for LEO Satellite Networks Integrated with HAPs Using Hybrid NOMA-OFDM

Space AI has become increasingly important and sometimes even necessary for government, businesses, and society. An active research topic under this mission is integrating federated learning (FL) with satellite communications (SatCom) so that numerous low Earth orbit (LEO) satellites can collaboratively train a machine learning model. However, the special communication environment of SatCom leads to a very slow FL training process up to days and weeks. This paper proposes NomaFedHAP, a novel FL-SatCom approach tailored to LEO satellites, that (1) utilizes high-altitude platforms (HAPs) as distributed parameter servers (PS) to enhance satellite visibility, and (2) introduces non-orthogonal multiple access (NOMA) into LEO to enable fast and bandwidth-efficient model transmissions. In addition, NomaFedHAP includes (3) a new communication topology that exploits HAPs to bridge satellites among different orbits to mitigate the Doppler shift, and (4) a new FL model aggregation scheme that optimally balances models between different orbits and shells. Moreover, we (5) derive a closed-form expression of the outage probability for satellites in near and far shells, as well as for the entire system. Our extensive simulations have validated the mathematical analysis and demonstrated the superior performance of NomaFedHAP in achieving fast and efficient FL model convergence with high accuracy as compared to the state-of-the-art

Utilization of Lightweight Tetrapod Aggregate Produced from a High Calcium Fly Ash in Civil Engineering Applications

Due to the increasing volumes of fly ash production in some countries that depend on coal for running their thermal power plants, new utilization areas must be found. One of these areas is to utilize large volume applications such as the production of special shape aggregate (tetrapod) to be used in different geotechnical applications and highway construction. This is beneficial in solving the disposal problem of fly ash as well as making economical use of a mineral resource. To achieve these goals, fly ash was utilized in producing tetrapod shape lightweight aggregate by pressing into a specially designed mold. Pre to the production of tetrapods, regular lightweight fly ash aggregates were produced, cured and tested. Test results on the regular lightweight fly ash aggregates were implemented in the production of tetrapods. Optimization of lime content showed that five per cent by weight lime addition to fly ash had the best performance. Tests were conducted on the cured tetrapods in order to determine their mechanical and physical properties. Absorption and other properties were improved by surface treatment with water glass and heating

Modeling and dynamic simulation of an off-grid pv cooling system for an office building in different climate locations

Solar electrical systems are an efficiency way to reduce the power consumption, therefore, the operational costs of an electrical system. In this study, a simulation and analysis of an independent solar cooling system are carried out. An air conditioner of the direct expansion type is connected to PV module without using storage batteries. Furthermore the connection to the grid is avoided. The model has been developed and simulated by TRNSYS to study the influence on the room temperature when the PV collector area is varied. The simulations applied in three different climate locations Tarragona (Spain), Cairo (Egypt) and New Delhi (India). The adequate number of PV panels selected by the minimum value of the uncomfortable hours inside the room and also by the system investment costs