Reactive power optimization using adaptive excitation control of synchronous power

Synchronous machines provide a practical way to control reactive power consumption of a plant. One of the main advantages of using synchronous motors in a plant is their ability to generate reactive power for plant loads. A new control scheme for synchronous motor excitation systems is developed to automate reactive power consumption. The system performs adaptive control based on the real time data and keeps the power factor within a specified range. The system can also be used to improve voltage drop during large induction motor starts. Power system behavior as a result of applying the adaptive control is studied under different operating scenarios using power system analysis software. Results and conclusions are based on mathematical simulation and experimental measurements of a prototype system

Future regulations for the installation of Electronic Flight Bags (EFB)

This degree project studies the future regulations for the installation of electronic flight bags (EFB) with focus on the hardware and its safety implications in which the task was given by Bromma Air Maintenance (BAM). The aim is to ease the operator to handle issues dealing with EFB; such as lithium battery fire in the cockpit, placement of EFB in the cockpit, etc. This also addresses flight safety, flight controls, emergency evacuation and solutions in dealing with such issues. Flight safely is a vital factor to be considered since it jeopardizes lives. As recent reports indicate an increase in lithium battery powered devices incidents on aircrafts, this paves the way to find new solutions and procedures to mitigate them. By studying the current regulations, Acceptable Means of Compliance (AMC), Advisory Circular (AC) regarding the usage/installation of EFB and future regulation draft (NPA) this study analyzed the changes, which indicated that there were not many significant changes made to the future regulation (new AMC). Although many chapter of the current AMC have been removed and introduced into a new section under AMC & GM (Guidance Material). Different placement of the EFB in cockpit has also been studied in this degree project, which has shown that depending on the placement choice of the aircraft operator there are advantages and disadvantages. This follows by studying the lithium (Li-ion) batteries: technology, mitigation of fire and procedures for lithium battery fire while also studying the recent incidents regarding lithium batteries fire and explosion in commercial and cargo flights. The solutions consist of using the latest technology to propose a new approach to charge the batteries, and store the burning batteries as well. This lead to a smart inductive charger and a smart fire contamination bag to be integrated into the procedures.Detta examensarbete studerar de framtida installationskrav för Electronic Flight Bag (EFB) med fokus på hårdvaran och dess påverkan på säkerheten. Rapporten kan användas som manual som tydliggör vilka procedurer och rekommendationer operatören kan ta hänsyn till vid installation och användning av EFB. I flygbranschen har de flesta flygbolag redan börjat använda surfplattor istället för dokument och manualer. EFB är ett elektroniskdisplaysystem som i första hand används i flygplanets cockpit. EFB:s funktion är att förse piloten med en mängd olika data om flygplanet t.ex. prestanda, balans och vikt beräkningar, bränsle mm. Displayen är en ersättning av det traditionella ”Flight Bag” som för i tiden var i pappersform och innehöll alla kartor och manualer skriftligt. Som alla andra teknologier har EFB sina begränsningar såsom batteriproblem, påverkan på säkerheten och ”Flight Controls” i flygplanets cockpit. Genom studier och sammanfattning av skillnaden mellan nuvarande och framtida regelverk har man kommit fram till att inga märkbara förändringar har skett. Fältstudien var till nytta för att analysera vilka säkerhetsproblem varje installationstyp har. Utrustningar som smart induktiv laddare och smart brandskyddsväska har fåtts som resultat i arbetet. Dessa utrustningar är till att motverka faror som är möjliga att ske under användning av EFB i cockpit

Shear behavior of basalt FRC beams reinforced with basalt FRP bars and glass FRP stirrups: Experimental and analytical investigations

This study investigated the shear behavior of basalt fiber reinforced concrete (BFRC) beams reinforced with basalt (B) and glass (G) fiber-reinforced polymers (FRP) bars and stirrups, respectively. Fourteen beams were tested under four-point loading up to failure. The investigated parameters were the volume fractions (Vf) of basalt macro-fibers (BMF), the reinforcement ratio, the shear-span-to-depth ratio, and the stirrup spacing. An enhancement in shear capacities of the tested beams was observed with the increase of the Vf of the added BMF from 0 to 1.5%. The shear capacities of the tested beams were also improved as their reinforcement ratios increased. On the other hand, there was a significant reduction in the ultimate strengths and stiffnesses of beams with GFRP stirrups compared to their counterpart beams with steel stirrups. The experimental capacities of the tested beams and experimental results of 178 FRP-RC beams available in the literature were compared to those predicted by existing models and code equations. A good correlation between the predicted and experimental results was obtained using the equations of CAN/CSA-S806-12. A proposed modified shear equation incorporating CAN/CSA-S806-12 provisions and a model suggested by Al-Ta'an and Al-Feel predicted the shear design capacities of BFRP-BFRC reinforced concrete beams with reasonable accuracy.The authors show their gratitude to Qatar Foundation for their financial support through the UREP award no. UREP21-089-2-039 and GSRA grant no. GSRA6-1-0301-19005 from the Qatar National Research Fund (QNRF, a member of Qatar Foundation). Also, the authors would like to thank Galen LLC for providing the BFRP bars used in this study. The findings achieved herein are solely the responsibility of the authors.Scopu

Sustainable flue-gas quench : For waste incineration plants within a water-energy-environment nexus perspective

The function of a flue-gas quench is to remove additional contaminants from flue-gas and to reduce the wastewater from a waste incineration plant. The aim of this degree project is to find how the system is affected by using a quench and what factors limits the performance. This is done by modelling and simulating a waste incineration plant in Aspen Plus. Data and plant schematics were obtained by a study visit to Mälarenergi Plant 6 situated in Västerås, Sweden, which were used as model input and for model validation. The results have shown that the amount of wastewater can be reduced by more than half compared to a plant without a quench. The heat produced in the condenser, when discharging water to the boiler, would be lowered by up to 20%. For systems with a quench present when more water was discharged to the boiler both the heat production and the pollutant capturing became better. However, the system has limits regarding the amount that could be recirculated, in the form of temperature limits in different parts of the system. In addition, if the heat load is low there is an insufficient amount of wastewater generated in the condenser to run the quench. In that situation, clean (fresh) water needs to be used instead. Using clean water is unwanted since the plant will then consume more resources while still producing less heat than a plant without a quench would

Shear Behavior of Fiber Reinforced Concrete Beams with Basalt FRP Reinforcing Bars and Glass FRP Stirrups

The State of Qatar suffers from a harsh environment in the form of high temperature that prevails almost all year round in addition to severe humidity and coastal conditions. This exposure leads to the rapid deterioration and the reduction of the life span of reinforced concrete (RC) infrastructure. The full functionality and safe use of the infrastructure in such environments can only be maintained by holistic approaches including the use of advanced materials for new construction.With the developments in materials science, the advanced composites, especially fiber reinforced polymer (FRP) materials are becoming viable alternatives to the traditional construction materials. Having superior durability against corrosion, versatility for easy in-situ applications and enhanced weight-to-strength ratios compared to their counterpart conventional materials, FRPs are promising to be the future of construction materials. More recently, FRP composites made of basalt FRP (BFRP) have been introduced as an alternative to traditional steel reinforcement at a price comparable to glass fibers of about $2.5-5.0 per kg, which is significantly lower than carbon fibers. BFRP bars are characterized by their corrosion resistance, greater strain at failure than carbon fibers, and better chemical resistant than glass fibers, particularly in a strongly alkaline environment. Knowing that FRP bars are anisotropic materials with weaker strength in the transverse direction compared with the longitudinal direction, and having a relatively low modulus of elasticity compared with steel reinforcement, it is important to investigate the concrete contribution to shear strength for beams reinforced with BFRP bars. In addition, due to the elastic performance of the FRP reinforcing bars compared with steel bars, FRP bars fail in a brittle manner. Moreover, concrete itself is a brittle material. Previous investigations have shown that using discrete fibers in concrete increases its ductility due to the large compressive strains exhibited at failure. Therefore, basalt macro-fibers is proposed in this study. A total of 14 concrete beam specimens were tested under four point loading until failure. The parameters investigated included the reinforcement ratio (2rb, 3.1rb, and 4.53rb,where rb is the balanced reinforcement ratio), the span to depth ratio (a/d=2.5, and a/d=3.3), the spacing between stirrups (S1=170mm, and S2=250mm) and the basalt fiber volume fraction (0%, 0.75% and 1.5%). Test results clearly showed that both BFRP bars and basalt macro-fibers can be used as sustainable and eco-friendly alternative materials in Concrete Structures in Qatar

Bond durability of sand coated and ribbed basalt FRP bars embedded in high-strength concrete

This study examines the bond durability behavior of basalt fiber-reinforced polymer (BFRP) bars in harsh environments. The effects of surface treatment, concrete compressive strength, exposure type, and period of exposure on bond strength were examined through an experimental program. The results of 42 pull-out samples show that the bond strength of sand-coated bars was not significantly affected by concrete compressive strength. However, specimens with high-strength concrete achieved most of or above their maximum bond strength after the descending stage, while those with normal-strength concrete showed a decrease in bond strength to an approximately constant value with continuous slip. Ribbed bars had significantly higher bond strength than sand-coated bars and were less affected by the surrounding environments. After 9 months, the bond strength retentions for sand-coated bars were 29.43, 63.93, and 67.43%, and 66.10, 94.94, and 80.44% for ribbed bars under the exposure to the 50 °C seawater, sulfuric acid, and freeze–thaw cycles, respectively. The failure in sand-coated bars was governed by a complete delamination of the outer surface from the core of the bar, whereas the ribbed bars failed due to bar rupture and interlaminar shear failure between bar layers. Both BPE and CMR models correlated well with experimental findings of the sand-coated bars, but CMR was more accurate for ribbed bars.Other Information Published in: Construction and Building Materials License: http://creativecommons.org/licenses/by/4.0/See article on publisher's website: https://dx.doi.org/10.1016/j.conbuildmat.2023.133385</p

Impact de la gestion des risques sur les financements participatifs Marocain : essai de modélisation

Cet article donne un aperçu sur les différents risques propre à la banque participative marocaine qu’on a recueillie à partir des entretiens semi directifs et des questionnaires sur un échantillon de 5 banques et 3 fenêtres participatives de la place et 381 réponses. Ensuite nous avons étudié la relation entre les indicateurs de gestion des risques et les variables internes et macroéconomiques bancaires durant la période de 2017 jusqu’ à 2021. Les résultats obtenus montrent que le dispositif de gestion des risques est une autoreproduction du système classique des banques conventionnelles ainsi que le degré de gravité des risques, la gouvernance et la qualité de la surveillance du comité de gestion des risques (RMC), les variables interne et macroéconomiques corrèlent positivement avec la performance de la banque participative par contre le ratio des financements non performants (NPL) et les dépenses de personnel affectent négativement la performance des banques