169 research outputs found
A framework for enabling high-end high performance computing resources as a service
No full textIn an era of data explosion and analysis, researchers across the globe are trying to convert massive quantities of complex data into useful knowledge using Computational and Data-Enabled Science and Engineering (CDS&E) applications. CDS&E applications are gaining traction as an important dimension of Science, Technology, Engineering, and Mathematics research. These applications require powerful processors with fast interconnects, extreme large scale, and elastic resources. While high-end High Performance Computing (HPC) resources provide the necessary requirements, the complexity of such systems has grown exponentially. Furthermore, due to their high cost, limited availability, and high demand, the queue wait times to run applications on these systems is in the order of months. All of the above challenges prevent their adoption as a mainstream solution. On the other hand, Cloud computing is emerging as a dominant computing paradigm that offers many advantages. Consequently, early adopters have looked into using Clouds to solve the HPC model challenges. Initially, CDS&E applications were run on commodity Clouds, but this was found to be appropriate only for certain classes of applications. Other approaches explored complementing HPC resources with Clouds but failed to address all challenges in the HPC environment. Cloud providers also tried to provide HPC as a Cloud using small HPC clusters connected to form a larger Cloud but were hindered by small scale and limited performance. These approaches fall short of providing the high performance necessary for CDS&E applications. In this document, we propose a new approach to achieve the notion of HPC as a Service. This approach targets existing high-end HPC resources and investigates how a Cloud abstraction can be applied to provide a simple interface and support real-world applications. In particular, the application of Clouds to supercomputers is discussed, tested, and validated on an IBM Blue Gene/P supercomputer. The proposed framework transforms Blue Gene/P into an elastic cloud by bridging multiple systems to create HPC federated Clouds, supporting dynamic provisioning and efficient utilization, and maximizing ease-of-use through an as a Service abstraction. In order to effectively illustrate the benefits of such a concept, the proposed framework is demonstrated using a real-world ensemble application.M.S.Includes bibliographical referencesby Moustafa AbdelBak
Differential Evolution Algorithm for Coordination of SVC Modules in MV Distribution Systems
No full textAbstract: This paper proposes a new strategy based on the differential evolution algorithm to optimize the performance of distribution networks through the optimal coordination of Static VAR Compensator modules (SVCs). Installation costs minimization and savings maximization due to reducing power losses are merged in one multi-objective function. In order to investigate the influences of varying loading conditions, various regular loadings are further combined. This framework implemented on a 37-bus real feeder connected to the Egyptian Unified Network (EUN). The findings of the simulation reveal evident technical and economical characteristics of the proposed algorithm. The reactive power compensation using SVCs based on the pro-posed scheme leads to major quality improvements of the entire nodes’ voltage with variations of loads. Especially, in light loading condition, the SVCs control their performance characteristics according to the reactive power demands in the adjacent nodes.Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP)
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Studies on mechanical contact devices for bolted Bus-Bar connections
No full textAbstract: There are several factors influencing the performance of an electrical connector. Such as design, environmental conditions, applied force, electrical loads, and installation procedures. As the performance demands on electrical networks and plants in general, and electrical connectors in particular, constantly increase, the need for more reliable rules for design and testing of electrical connectors becomes necessary. As for the bolted bus-bar design factor, a number of more or less important design parameters can be identified, including: contact force, overlapping, etc. The initial joint resistance of overlapped bolted is assessed experimentally, The parameters influencing the initial joint resistance such as overlap distance,Holes diameter, tighten torque and bolt size are investigated. A computer simulation based upon the finite element method was introduced to calculate the ideal joint resistance and compared with that obtained experimentally
Parameter Identification of Solar Photovoltaic Systems Using an Augmented Subtraction-Average-Based Optimizer
No full textSolar photovoltaic system parameter identification is crucial for effective performance management, design, and modeling of solar panel systems. This work presents the Subtraction-Average-Based Algorithm (SABA), a unique, enhanced evolutionary approach for solving optimization problems. The conventional SABA works by subtracting the mean of searching solutions from the position of those in the population in the area of search. In order to increase the search capabilities, this work proposes an Augmented SABA (ASABA) that incorporates a method of collaborative learning based on the best solution. In accordance with manufacturing, the suggested ASABA is used to effectively estimate Photovoltaic (PV) characteristics for two distinct solar PV modules, RTC France and Kyocera KC200GT PV modules. Through the adoption of the ASABA approach, the simulation findings improve the electrical characteristics of PV systems. The suggested ASABA outperforms the regular SABA in terms of efficiency and effectiveness. For the R.T.C France PV system, the suggested ASABA approach outperforms the traditional SABA technique by 90.1% and 87.8 for the single- and double-diode models, respectively. Also, for the Kyocera KC200GT PV systems, the suggested ASABA approach outperforms the traditional SABA technique by 99.1% and 99.6 for the single- and double-diode models, respectively. Furthermore, the suggested ASABA method is quantitatively superior to different current optimization algorithms
Challenges in Selection and Design the Beam Pumped Well Completions
No full textAbstract
Completion string is a critical component of the well production system and it must be efficiently designed, installed and maintained. Each production system for artificially pumped wells, have different requirements. Downhole pumps are a common means of boosting the productivity of a well by lowering the buttonmhole pressure. Rather than lowering pressure gradient in the tubing to reduce the bottomhole pressure as in gas lift.
Two types of pumps are used: positive-displacement pumps, which include sucker rod pumps and dynamic displacement pumps, which include electrical submersible pumps. With the improvement in the sucker rod pumping system capabilities in producing tough conditions wells (deep, sandy, gassy, deviated and horizontal wells), selecting the right completion components became extremely necessary to extend run life and reduce operating costs for this type of artificially lifted well.
In a standard rod pumping completion, the tubing and the pump seating nipple are the essential parts in the completion string. But for moderate and deeper wells, a tubing anchor catcher (TAC) became the third important part for successful artificial lift well operations. In case of tough well, selections of the right subsurface completion components are necessary to extend the life and reduce operating costs of the well hardware. Each case may require especial design and running tools selection.
Searching in different literatures showed that there is no adequate information about beam pumping wells completions. This paper addresses the analysis of the current well completions conditions and associated problems and then it will present practical completion solutions for normal and difficult well conditions. This paper will also present case studies from different countries.</jats:p
Effect of chain length on the photophysical properties of pyrene-based molecules substituted with extended chains
No full textThe important role played by organic conjugated compounds in the ?elds of electronics and optoelectronics has led to a vast ?eld of research concerned with synthesizing various complex structures where π-π stacking plays a vital role. Pyrene-based molecules are examples of compounds which allow ef?cient charge transfer through π-π molecular stacking. Photophysical studies of such compounds have shown similar behavior as that of pyrene, even though they bear two additional conjugated rings and four long alkyl chains. Chain length may have played an effective role in in?uencing the π-π molecular stacking of such molecules. In continuation of our earlier work(Moustafa, R. M.; Degheili, J. A.; Patra, D.; Kaafarani, B. R. J. Phys. Chem. A 2008, 113, 1235-1243), we hereby synthesize and investigate the role of the chain lengths on the photophysical aspects of 2,11-di-tert-butyl-6,7,15,16- tetrakis(alkoxy-alkythio)quinoxaline-[2′,3′:9,10]phenanthro[4, 5-ab-c]phenazine, TQPP-[t-Bu]2-[XR]4(X O, S; R C nH2n+1). Various photophysical parameters such as Stokes shift, ?uorescence lifetime, ?uorescence quantum yield, and radiative and nonradiative rate constants are evaluated for TQPP-[t-Bu]2-[OR] 4 and TQPP-[t-Bu]2-[SR]4 in tetrahydrofuran. The variation of the Stokes shift, ?uorescence quantum yield, and lifetime are also correlated with the number of carbons in the alkyl chain R for TQPP-[t-Bu]2-[OR]4 and TQPP-[t-Bu]2-[SR] 4. © 2009 American Chemical Society.Anthony JE, 2008, ANGEW CHEM INT EDIT, V47, P452, DOI 10.1002-anie.200604045; Boden N, 1999, J MATER CHEM, V9, P2081, DOI 10.1039-a903005k; Chen MC, 2008, J MATER CHEM, V18, P1029, DOI 10.1039-b715746k; Chen ZH, 2006, ORG LETT, V8, P273, DOI 10.1021-ol0526468; Katsuhara M, 2005, SYNTHETIC MET, V149, P219, DOI 10.1016-j.synthmet.2005.01.005; Kumar S, 2006, CHEM SOC REV, V35, P83, DOI 10.1039-b506619k; Lakowicz J. R., 1999, PRINCIPLES FLUORESCE; Mitzi DB, 2004, J MATER CHEM, V14, P2355, DOI 10.1039-b403482a; MOUSTAFA RM, J PHYS CHEM A UNPUB; Naraso, 2005, J AM CHEM SOC, V127, P10142, DOI 10.1021-ja051755e; Oukachmih M, 2005, SOL ENERG MAT SOL C, V85, P535, DOI 10.1016-j.solmat.2004.05.012; Palilis LC, 2003, ORG ELECTRON, V4, P113, DOI 10.1016-j.orgel.2003.08.006; Parker C.A., 1968, PHOTOLUMINESCENCE SO; Petritsch K, 1999, SYNTHETIC MET, V102, P1776, DOI 10.1016-S0379-6779(98)01035-2; Ponomarenko SA, 2003, ADV FUNCT MATER, V13, P591, DOI 10.1002-adfm.200304363; Subuddhi U, 2006, PHOTOCH PHOTOBIO SCI, V5, P459, DOI 10.1039-b600009f; Sun YG, 2007, ADV MATER, V19, P1897, DOI 10.1002-adma.200602223; van de Craats AM, 1999, ADV MATER, V11, P1469, DOI 10.1002-(SICI)1521-4095(199912)11:171469::AID-ADMA14693.0.CO;2-K; WARIS R, 1988, APPL SPECTROSC, V42, P1525, DOI 10.1366-000370288442980513131
Performance of pelican optimizer for energy losses minimization via optimal photovoltaic systems in distribution feeders.
No full textIn distribution grids, excessive energy losses not only increase operational costs but also contribute to a larger environmental footprint due to inefficient resource utilization. Ensuring optimal placement of photovoltaic (PV) energy systems is crucial for achieving maximum efficiency and reliability in power distribution networks. This research introduces the Pelican Optimizer (PO) algorithm to optimally integrate solar PV systems to radial electrical distribution grids. The PO is a novel bio-inspired optimization algorithm that draws inspiration from pelicans' intelligence and behavior which incorporates unique methods for exploration and exploitation, improving its effectiveness in various optimization challenges. It introduces a hyper-heuristic for phase change, allowing the algorithm to dynamically adjust its strategy based on the problem's characteristics. The suggested PO aims to reduce the energy losses to the possible minimum value. The developed PO version is tested on the Ajinde 62-bus network, a practical Nigerian distribution system, and a typical IEEE grid with 69 nodes. The simulation findings demonstrate the enhanced PO version's efficacy, showing a significant decrease in losses of energy. With the Ajinde 62-node grid, the suggested PO version obtains a substantial 30.81% decrease in the total energy loss expenses in contrast to the initial scenario. Similarly, the IEEE 69-node grid achieves a significant decrease of 34.96%. Additionally, the model's findings indicate that the proposed PO version performs comparably to the Differential Evolution (DE), Particle Swarm Optimization (PSO), and Satin bowerbird optimizer (SBO) algorithms
The Current State of Artificial Intelligence on Detecting Pulmonary Embolism via Computerised Tomography Pulmonary Angiogram: A Systematic Review.
No full textCopyright: © 2025 The Author(s).
https://creativecommons.org/licenses/by-nc/4.0/Pulmonary embolism (PE) is a life-threatening condition with significant diagnostic challenges due to high rates of missed or delayed detection. Computed tomography pulmonary angiography (CTPA) is the current standard for diagnosing PE, however, demand for imaging places strain on healthcare systems and increases error rates. This systematic review aims to assess the diagnostic accuracy and clinical applicability of artificial intelligence (AI)-based models for PE detection on CTPA, exploring their potential to enhance diagnostic reliability and efficiency across clinical settings. A systematic review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Excerpta Medica Database (EMBASE), Medical Literature Analysis and Retrieval System Online (MEDLINE), Cochrane, PubMed, and Google Scholar were searched for original articles from inception to September 2024. Articles were included if they reported successful AI integration, whether partial or full, alongside CTPA scans for PE detection in patients. The literature search identified 919 articles, with 745 remaining after duplicate removal. Following rigorous screening and appraisal aligned with inclusion and exclusion criteria, 12 studies were included in the final analysis. A total of three primary AI modalities emerged: convolutional neural networks (CNNs), segmentation models, and natural language processing (NLP), collectively used in the analysis of 341,112 radiographic images. CNNs were the most frequently applied modality in this review. Models such as AdaBoost and EmbNet have demonstrated high sensitivity, with EmbNet achieving 88-90.9% per scan and reducing false positives to 0.45 per scan. AI shows significant promise as a diagnostic tool for identifying PE on CTPA scans, particularly when combined with other forms of clinical data. However, challenges remain, including ensuring generalisability, addressing potential bias, and conducting rigorous external validation. Variability in study methodologies and the lack of standardised reporting of key metrics complicate comparisons. Future research must focus on refining models, improving peripheral emboli detection, and validating performance across diverse settings to realise AI's potential fully
Fame bias in editorial choice: Yes or No?
No full textRecently, Scientometrics has published a paper titled “Is there bias in editorial choice? Yes” (Moustafa 2015) in which some comments are given on our published paper in Nature titled “Is there fame bias in editorial choice?” (Mahian et al. 2015). Unfortunately, the author of above mentioned paper and many other readers might misunderstand the main aim of our correspondence. Here, we try to give some explanations to clarify the main goal of analysis presented in the paper
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