1,721,276 research outputs found
Understanding Role of Crystal Violet and Its Polarity on MoS2 Growth Scrutinized by Ab Initio Calculations
No full textStrained MoTe2 Monolayer as Photon Absorber in the Telecom Range
No full textThis upload contains all the data that is produced, analyzed, and its finding are summarized in a research article, soon to be published, with the title "Strained MoTe2 Monolayer as Photon Absorber in the Telecom Range" authored by Muhammad Sufyan Ramzan and Caterina Cocchi
Battery management optimization and lifecycle impact analysis for microgrid operation with V2G implementation / Muhammad Sufyan
Full text linkThe electric power system has been transformed and evolved towards decentralized systems, which interact with each other and within the whole electrical system. In this way, microgrids are essential components to increase the reliability and efficiency of the power system. The critical issue in isolated microgrid is the energy demand balance in the presence of intermittent renewable energy sources. Energy storage systems are the adequate solution to balance the demand/supply issue and support the ancillary services such as voltage regulation and reserve requirement. However, due to high installation cost of storage system, their sizing is essential for optimized operation of microgrid. The first part of this work proposes energy management system to reduce the operating cost of isolated microgrid. The economic scheduling using firefly algorithm is implemented for the optimization of distributed energy sources and ascertain optimal size of energy storage while meeting the load demand. The efficacy of the optimization algorithm is compared with other metaheuristic techniques for economic and reliability indices such as cost of electricity and loss of power supply probability. In the second part, electric vehicles (EV) are incorporated as flexible load in the power system. The EVs charge coordination with vehicle to grid (V2G) technology is performed with respect to economic and technical perspective. The economic objectives encompass cost minimization and profit maximization whereas technical objectives constitute power loss minimization and peak load reduction. The EV users are certainly concerned for cost of battery replacement due to degradation with active participation in V2G energy exchanges. Therefore, battery degradation model is formulated for real time analysis by considering the depth of discharge at each time interval. The operating cost and V2G profit are analyzed with different penetrations of renewable power generation, EV battery capacity and travelling time. The results indicate that proposed energy management approach effectively reduced the operating cost, ensuring the reliability of the
microgrid. Since battery sizes influence the operating cost, optimal battery size is calculated to have minimum cost of electricity and prolong the battery lifetime. The proposed method results in 50% cost reduction when compared with the conventional method. The proposed energy management approach is solved using firefly algorithm, artificial bee colony, harmony search algorithm and particle swarm optimization. It was found that firefly algorithm is robust and computationally effective. In addition, EV charge coordination improves the system performance, minimize the power losses and restricts grid overloading. The integration of renewable energy sources (RES) reduces the system cost and maximizes the profit for the EV users. The system losses and cost of electricity is minimum when the RES penetration is increased while different EV capacities yields minimum profit
A new hybrid geoid model over Perlis region / Muhammad Sufyan Zakwan Hirwandy
Full text linkA hybrid geoid model can be defined as a geoid that combines the geometrical geoid derived from GNSS leveling with the gravimetric geoid to improve its accuracy and resolution for a specific region. The accuracy of a hybrid geoid model primarily depends on the corrective surface between the geoid and the leveling datum, which is derived using GNSS leveling points and the gravimetric geoid. Although Malaysia has developed a hybrid geoid model known as MyGEOID, the limited number of GNSS leveling points over the Perlis region used in the MyGEOID modeling process could affect the model's accuracy in this region. Furthermore, the accuracy of a hybrid geoid also depends on the parametric models applied to model the corrective surface.Therefore, this study has developed a new hybrid geoid model for the Perlis region using a new gravimetric geoid model derived using the KTH method and new GNSS leveling points. Three distinct parametric models were used in the hybrid geoid model development to identify the optimum model: the 2nd polynomial, the 3rd polynomial, and the 4-parameter datum shift.Each geoid was compared with the gravimetric geoid using 38 GNSS leveling points, showing that the geoid accuracy produced in this study is approximately ±0.0379 m. Meanwhile, the hybrid geoid derived in this study, known as UITM Perlis Hybrid Geoid 2024 (UITM-PGH24), was evaluated using 21 GNSS leveling points. Based on the comparison, the accuracy of UITM-PGH24 is approximately ±0.055 m, which is 2 cm better than the accuracy of the existing hybrid geoid, MyGEOID. The results generally show that UITM-PGH24 could be a useful substitute for the present modern height system applied in hybrid geoid applications for surveying and mapping in the Perlis regio
Understanding Oxidation Mechanism of MoS2 Slab and Ribbon: Frist Principles Calculations
No full textTunable Exciton Modulation and Efficient Charge Transfer in MoS 2 /Graphene van der Waals Heterostructures
Full text linkMonolayer transition metal dichalcogenides (TMDs) are direct gap semiconductors where the optical properties are dominated by strongly interacting electron–hole quasi-particles. Understanding the interactions among these quasi-particles is crucial for advancing optoelectronic applications. Here, we examine the electrical tunability of light emission from the A and B excitons in monolayer MoS 2 and MoS 2 /graphene heterostructures and unravel the competition between the A exciton to trion formation and charge transfer processes. Our results show significant gate-tunable quenching of the photoluminescence intensity from A excitons with notable differences due to charge transfer in the heterostructure. Furthermore, we observe a distinct superlinear correlation between the A exciton photoluminescence intensity and high doping levels in MoS 2 , which continues until the density of photoexcited excitons exceeds and saturates the free carrier density. This phenomenon ceases to occur in MoS 2 /graphene, where MoS 2 remains almost undoped across all values of the applied external voltage. In contrast, the B exciton photoluminescence is unaffected by doping in MoS 2 , while it decreases analogously to that of the A excitons in the MoS 2 /graphene heterostructure, indicating the relevance of gate-tunable charge transfer from hot electrons before any internal recombination
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evaluation system on haemodynamic parameters for stented carotid artery: stent pictorial selection method
No full textnormal blood pressure (NBP), pre-hypertension (PH) and hypertension stage one (HS1) through computational fluid dynamic (CFD) method. The hemodynamic performance of stent was analyzed based on parameters namely time averaged wall shear stress (TAWSS), time averaged wall shear stress gradient (TAWSSG), oscillatory shear index (OSI), relative residence time (RRT) and flow separation parameter (FSP). Meanwhile, Pictorial Selection Method was used to evaluate the best hemodynamic stent performance based on a scoring system. From observation, stent Type II was seen to show the highest score for TAWSS, which about 3.44 regardless of any physiological conditions. For TAWSSG, the lowest score was observed for Type V stent with 0.36. Furthermore, Type VI stent displayed the highest score for OSI while Type IV has the lowest score for FSP with 3.09 and 1.23, respectively. On the other hand, RRT was seen varying according to the physiological condition where the highest score in NBP condition was achieved by Type I while PH and HS1 condition was achieved by Type VI. In conclusion, Type VI has the best stent performance, whereas Type IV has the worst stent performance regarding the scoring system based on hemodynamic parameters. Further, Type I, Type II, Type III and Type V stents showed moderate hemodynamic performances for all physiologicalconditions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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