5 results
Search Results
Now showing 1 - 5 of 5
Article Citation - WoS: 24Citation - Scopus: 34Optimization and Thermal Analysis of Radial Ventilated Brake Disc To Enhance the Cooling Performance(Elsevier, 2022) Jafari, Rahim; Akyuz, RecepVentilated brake discs are preferable to automobile application because of their higher heat dissipation ability than solid discs. The shape, geometry and number of the cooling fins are interested parameters to be investigated to improve the cooling performance of the discs. In the present study, the optimum design of the brake disc with radial vanes is investigated numerically using the Taguchi design of experiments with taking into account nine design parameters. Finite element method is employed to simulate the detailed airflow and temperature distribution in the disc considering adjoined components as pads, rim, tire and dust shield. It has been found that the ventilation gap width has the highest impact on the brake disc cooling. The cooling time of the disc decreases 21% as the ventilation gap increases from 8 mm to 14 mm. In addition, it reduces about 10% with the increment of the channel width between two adjacent vanes (inverse of vane numbers from 43 to 30) and the twist point from 225 mm to 266 mm. In a decreasing order of importance, fin angle, inner and outer diameters of fin, dust shield, bell link and disc material affect the cooling performance of the ventilated disc.Review Citation - Scopus: 2Coal Preparation in the World - Current Status and Global Trends: a Review("Ore and Metals" Publishing house, 2016) Rubinstein,J.B.; Swanson,A.; Holuszko,M.E.; Shaoqiang,Z.; Ziaja,D.; Anastassakis,G.; Vorobev,S.A.This article is a review composed of 14 sections prepared by representatives of the involved countries. The sections inform on: coal production volume per country; principal coal producing regions and companies; coal preparation technologies and trends of coal use in national economies, considering the environmental constraints. The review opens with the section devoted to the state of the art and prospects of coal preparation in Russia; the next sections about other countries are arranged in the way to fit the Latin alphabet. The scope of the Russian section encompasses large projects on coal preparation, prospects of coal application in power generation and the issue of coal mine waste reprocessing. The Australian section emphasizes that coal is an important export article and the key component of power generation in the country. It is mentioned that round 90 % of ROM coal needs preparation before marketing. The section on Canada gives evaluation of coal reserves and resources and a detail description of coalproducing companies in the country. China is the largest coal-producing country in the world (3.87 Bt of coal in 2014); more than 60 % of coal is subjected to preparation. Germany is running short of coal reserves (coal reserves are only sufficient until late 2018) but holds enormous reserves of lignite subjected to open pit mining. Hungary produces nearly 10 Mt of coal yearly and uses it to generate 14 % of the total power output. India is the world's third coal producer (after China and USA as of 2014). Kazakhstan takes half of produced coal to generate power and 30 % for export. Poland is the largest coal producer in Europe. All coal is mined with the underground method and approximately 60 % of coal needs preparation. The Republic of South Africa exports nearly one third of produced coal. Half of coal left in the country is spent to generate power and round 20 % of coal is converted to chemicals and fuel products. The best part of the produced coal needs preparation and coal for export is totally subjected to dressing. Turkey mines mainly lignite (95 %). The deficit of power-generating coal is compensated by the import. The coal industry of the Great Britain is at the stage of dying. It is planned to close all coal-run power plants by 2025. USA is the world's second producer of coal. Preparation embraces approximately 40 % of mined coal. The review ends with an analysis of international RandD projects in the area of coal preparation.Article Citation - WoS: 32Citation - Scopus: 39Backhaul-Aware Optimization of Uav Base Station Location and Bandwidth Allocation for Profit Maximization(Ieee-inst Electrical Electronics Engineers inc, 2020) Cicek, Cihan Tugrul; Gultekin, Hakan; Tavli, Bulent; Yanikomeroglu, HalimUnmanned Aerial Vehicle Base Stations (UAV-BSs) are envisioned to be an integral component of the next generation Wireless Communications Networks (WCNs) with a potential to create opportunities for enhancing the capacity of the network by dynamically moving the supply towards the demand while facilitating the services that cannot be provided via other means efficiently. A significant drawback of the state-of-the-art have been designing a WCN in which the service-oriented performance measures (e.g., throughput) are optimized without considering different relevant decisions such as determining the location and allocating the resources, jointly. In this study, we address the UAV-BS location and bandwidth allocation problems together to optimize the total network profit. In particular, a Mixed-Integer Non-Linear Programming (MINLP) formulation is developed, in which the location of a single UAV-BS and bandwidth allocations to users are jointly determined. The objective is to maximize the total profit without exceeding the backhaul and access capacities. The profit gained from a specific user is assumed to be a piecewise-linear function of the provided data rate level, where higher data rate levels would yield higher profit. Due to high complexity of the MINLP, we propose an efficient heuristic algorithm with lower computational complexity. We show that, when the UAV-BS location is determined, the resource allocation problem can be reduced to a Multidimensional Binary Knapsack Problem (MBKP), which can be solved in pseudo-polynomial time. To exploit this structure, the optimal bandwidth allocations are determined by solving several MBKPs in a search algorithm. We test the performance of our algorithm with two heuristics and with the MINLP model solved by a commercial solver. Our numerical results show that the proposed algorithm outperforms the alternative solution approaches and would be a promising tool to improve the total network profit.Article Citation - WoS: 7Citation - Scopus: 12Genetic Algorithm and Tabu Search Memory With Course Sandwiching (gats_cs) for University Examination Timetabling(Tech Science Press, 2020) Abayomi-Alli, A.; Misra, S.; Fernandez-Sanz, L.; Abayomi-Alli, O.; Edun, A. R.University timetable scheduling is a complicated constraint problem because educational institutions use timetables to maximize and optimize scarce resources, such as tine and space. In this paper, an examination timetable system using Genetic Algorithm and Tabu Search memory with course sandwiching (GAT_CS), was developed fora lame public University. The concept of Genetic Algorithm with Selection and Evaluation was implemented while the memory properties of Tabu Search and course sandwiching replaced Crossover and Mutation. The result showed that GAT_CS had hall allocation accuracies of 96.07% and 99.02%, unallocated score of 3.93% and 0.98% for first and second semesters, respectively. It also automatically sandwiched (scheduled) multiple examinations into single halls with a simulation time in the range of 20-29.5 seconds. The GAT_CS outperformed previous related works on the same timetable dataset. It could, however, be improved to reduce clashes, duplications, multiple examinations and to accommodate more system-defined constraints.Article Citation - WoS: 3Citation - Scopus: 7Optimization-Based Scheduling of Construction Projects With Generalized Precedence Relationships: a Real-Life Case Study(Sharif University of Technology, 2024) Aminbakhsha, S.; Ahmed, A.Concomitant reduction of cost and duration is recognized as one of the main aspects of construction planning. Expedition of project schedule naturally incurs extra costs due to implementation of more productive and/or high-price construction techniques. Meanwhile, a reduction in time is usually plausible only down to a certain limit, below which renders expeditions either technically or nancially unviable. Thus, striking a reasonable balance between project cost and duration remains a desirable yet challenging task for which there has been a myriad of advancements and literature. Despite the many studies associated with this problem-referred to as Time-Cost Trade-off Problem (TCTP) it is observed that only a few exercise TCTPs with the generalized logical relationships. This observation holds despite the fact that generalized precedence relationships are imperative to introduce parallelism and to secure a realistic overlap among the activities. In this regard, a Simulated Annealing-based (SA-based) Genetic Algorithm (GA) as proposed herein, is specically designed to provide the capability of exerting TCTPs with properly overlapped activities. Eciency of this algorithm is tested over a range of problems and its performance is validated over a large-scale real-case construction project. Results of the hybridized GA indicate fast and robust convergence to high-quality solutions. © 2024, Sharif University of Technology. All rights reserved.
