Scientia Iranica最新文献_第3页

Online Estimation of Transformer Hot Spot Temperature by Considering the Effects of Load Profile Modeling 考虑负荷剖面建模影响的变压器热点温度在线估计

4区工程技术

Scientia Iranica Pub Date : 2023-10-01 DOI: 10.24200/sci.2023.62478.7883

Khadijeh Moosavi, Hossein Mokhtari

{"title":"Online Estimation of Transformer Hot Spot Temperature by Considering the Effects of Load Profile Modeling","authors":"Khadijeh Moosavi, Hossein Mokhtari","doi":"10.24200/sci.2023.62478.7883","DOIUrl":"https://doi.org/10.24200/sci.2023.62478.7883","url":null,"abstract":"One of the most valuable components in power systems is power transformer whose failure may result in a significant power loss. Therefore, one of the critical issues in power transformer operation is its health monitoring. Moreover, it was shown that the aging rate of transformers is very sensitive to the hot spot temperature, and when this temperature exceeds a threshold value, the aging rate increases. Given the fact that using temperature sensors in prefabricated and built-in transformers is not practical, thermal models are used to estimate transformer hot spot temperature. Since the transformer hot spot temperature is a key factor in the condition monitoring of a transformer, and in case it will exceed a threshold value, preventive actions should be taken in the proposed algorithm, the sensitivity of this important parameter with respect to the load profile sampling time is investigated. This paper proposes a fast online algorithm for the estimation of power transformer hot spot temperature by reducing the number of calculations without sacrificing accuracy. The proposed algorithm is applied to a 250 MVA transformer using MATLAB software. The results were compared with the actual factory test results and the efficiency of the proposed algorithm was shown.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134977974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A survey on the most practical signal processing methods in conditional monitoring in wind turbines 风电机组状态监测中最实用的信号处理方法综述

4区工程技术

Scientia Iranica Pub Date : 2023-10-01 DOI: 10.24200/sci.2023.62911.8101

Reza Heibati, Ramin Alipour-Sarabi, Seyed Mohammad Taghi Bathaee

引用次数: 0

Comprehensive Process of Multiportfolio Selection and Ordering 多投资组合选择与排序的综合过程

4区工程技术

Scientia Iranica Pub Date : 2023-09-20 DOI: 10.24200/sci.2023.61721.7456

Shadi Khalil Moghadam, Farimah Mokhatab Rafiei, Mohammad Ali Rastegar

{"title":"Comprehensive Process of Multiportfolio Selection and Ordering","authors":"Shadi Khalil Moghadam, Farimah Mokhatab Rafiei, Mohammad Ali Rastegar","doi":"10.24200/sci.2023.61721.7456","DOIUrl":"https://doi.org/10.24200/sci.2023.61721.7456","url":null,"abstract":"Portfolio optimization studies have traditionally assumed that portfolio managers manage only one portfolio. However, in reality, often manage multiple portfolios that can impact each other. This creates a need for fairness to all customers, which has led to the emergence of a new topic called \"multiportfolio optimization\". Previous studies have paid little attention to this issue, and the models used were not developed using real stock market data. These models were also limited to the selection phase and did not consider the ordering phase.This research provides a comprehensive process for addressing the multiportfolio problem, covering all sections from selection to ordering. It also implements the process using real stock market data. During this process, the market impact function is estimated using the I-STAR model for different stocks. The proposed model for market impact costs includes both permanent and temporary sections. The proposed models were tested using the Tehran Stock Exchange data in 2019.A comparison of the MPO model output with classical models indicates that the proposed model improves utility by an average of 15%. In the next phase, comparing the proposed ordering model with other models shows a reduction in market impact costs by an average of 26%.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"165 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136378951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Optimizing a multi-objective master surgical scheduling under probabilistic length of stay and demand uncertainty 基于概率住院时间和需求不确定性的多目标主手术调度优化

4区工程技术

Scientia Iranica Pub Date : 2023-09-20 DOI: 10.24200/sci.2023.59427.6248

Mohammad Ebrahimi, Arezoo Atighehchian, Majid Esmaelian

{"title":"Optimizing a multi-objective master surgical scheduling under probabilistic length of stay and demand uncertainty","authors":"Mohammad Ebrahimi, Arezoo Atighehchian, Majid Esmaelian","doi":"10.24200/sci.2023.59427.6248","DOIUrl":"https://doi.org/10.24200/sci.2023.59427.6248","url":null,"abstract":"The Master surgical scheduling (MSS) program is used at the tactical level of operating room scheduling, and its optimal creation can reduce the waiting queue of patients, as well as hospital costs. The patients’ length of stay (LOS) has a great impact on the downstream resources management. The uncertain nature of LOS and surgeries demand increases the challenges of MSS creation. The aim of the article is to determine the MSS program integrated with combination of surgical operations of each block of the operating rooms. For this purpose, a novel mathematical model was proposed for multi-objective MSS problems with a probabilistic LOS. Then, the chance-constrained programming method was employed to cope with the uncertain demands. The ε-constraint method was used for small-scale problems. Moreover, two metaheuristic algorithms including the multi-objective gray wolf optimizer (MOGWO) and the non-dominated sorting genetic algorithm-II (NSGAII) were designed to deal with large-scale problems. Based on the results, the MOGWO outperforms the NSGAII in terms of both the MID measure and the run time. The sensitivity analysis on the capacity of the wards parameter at different levels of demand uncertainty was performed to help managers to decide about the appropriate capacity of the wards.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136378952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Re-Identification in Video Surveillance Systems Considering Appearance Changes 考虑外观变化的视频监控系统的再识别

4区工程技术

Scientia Iranica Pub Date : 2023-09-10 DOI: 10.24200/sci.2023.57617.5331

Zahra Mortezaie, Hamid Hassanpour, Azeddine Beghdadi

引用次数: 0

A review of convective heat transfer in cavity-channel assemblies 腔道组件对流换热研究进展

4区工程技术

Scientia Iranica Pub Date : 2023-09-10 DOI: 10.24200/sci.2023.61315.7246

Ahmed Kadhim Hussein, Amaal Abdul Razaq Abdul Hussein, Awatef Abidi, Muneer A. Ismael, Ahmed B. Mahdi, Bashar S. Bashar, Farhan Lafta Rashid, Raad Z. Homod, Obey Younis, Lioua Kolsi, Ali J. Chamkha

{"title":"A review of convective heat transfer in cavity-channel assemblies","authors":"Ahmed Kadhim Hussein, Amaal Abdul Razaq Abdul Hussein, Awatef Abidi, Muneer A. Ismael, Ahmed B. Mahdi, Bashar S. Bashar, Farhan Lafta Rashid, Raad Z. Homod, Obey Younis, Lioua Kolsi, Ali J. Chamkha","doi":"10.24200/sci.2023.61315.7246","DOIUrl":"https://doi.org/10.24200/sci.2023.61315.7246","url":null,"abstract":"Convective heat transfer induced in open cavities is one of the main pillars that the topic of energy saving relies on. Thus, scanning and evaluation of works dealing with such a topic is of crucial importance. This article reviews and categorizes the results of researches on mixed convection in open cavity connected with a channel, and highlighting the gap that researchers should fill in future works. It is found that the best heat and mass transfer is attained when the source of heat and/or species is located at a vertical wall of the cavity where it opposites the direction of the flow. The review has demonstrated that the Reynolds number augments the mixed convection, while the magnetic field suppress it. The review has revealed that the experimental studies are relatively scare where it 10% of the total reviewed studies, while those dealing with nanofluids and porous media are 9% for each. It is found that the process of injection or aspiration of the flow have received very few studies despite its promised improvement of the heat and mass transfer. Furthermore, few researches have studied the contamination removing from the cavity. Thus, more attention is required to fill these two gaps.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136073424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of groundwater table on buried pipeline response to a surface explosion 地下水位对地下管线对地面爆炸响应的影响

4区工程技术

Scientia Iranica Pub Date : 2023-09-03 DOI: 10.24200/sci.2023.60029.6559

Mohamad Taghi Ahmadi, F. Ershadi

{"title":"Effects of groundwater table on buried pipeline response to a surface explosion","authors":"Mohamad Taghi Ahmadi, F. Ershadi","doi":"10.24200/sci.2023.60029.6559","DOIUrl":"https://doi.org/10.24200/sci.2023.60029.6559","url":null,"abstract":"Groundwater table is a fluctuating factor changing soil structure and affecting pipes' response to any load, such as an explosion. After validation with the results of previous studies, several numerical models were elaborated with ten different groundwater levels and two states of 1. Empty, 2. Pressurized for a buried pipe to investigate this for an explosion load. These simulations were solved by a Finite Element Method (FEM) solver. This research only studies the effects of non-cohesive soils and neglects the semi-saturated part of the soil for simplicity. The pipe's effective stress and plastic strain in each scenario were studied. The results state that the most critical scenario is when the water table is around the pipe crown, whether the pipe is empty or pressurized, with considerable excess stress compared to the absence of groundwater table. The deformation mode is also hugely affected by the water table, changing from local, forming a dent, to non-local. The internal pressure of the pipe also considerably reduces the pipe stresses and strains whether the surrounding soil is saturated or dry. Such results are certainly impactful in efficiently designing buried pipelines, which most existing guidelines and codes have not considered.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948648","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sustainable thermochemical energy storage through eco-friendly zeolites - A characterization study 生态友好型沸石可持续热化学储能的表征研究

4区工程技术

Scientia Iranica Pub Date : 2023-09-03 DOI: 10.24200/sci.2023.59415.6231

Ankammarao Padamurthy, Jalaiah Nandanavanam, Parameshwaran Rajagopalan

{"title":"Sustainable thermochemical energy storage through eco-friendly zeolites - A characterization study","authors":"Ankammarao Padamurthy, Jalaiah Nandanavanam, Parameshwaran Rajagopalan","doi":"10.24200/sci.2023.59415.6231","DOIUrl":"https://doi.org/10.24200/sci.2023.59415.6231","url":null,"abstract":"Judicious utilization of natural resources always helps protect the environment from several ill-effects. This paper was aimed at exploring the merits of natural and environment friendly zeolites towards sustainable thermochemical energy storage. Sorption behaviour of selected zeolites were investigated using a differential thermogravimetric analyser. The desorption kinetics was studied by heating the materials from room temperature to 600 °C. The materials lose their water molecules on heating and become anhydrous mostly around 300 °C. The desorption enthalpies due to heating were noted to decrease with increase of heating rate, and found low for Zeolite-Mordenite (334.5 J g-1) and high for Molecular Sieves-4A (1060 J g-1). Materials’ adsorption enthalpies were determined by subjecting them to single cycle tests comprising of heating, cooling and hydration processes in sequence. The desorption and adsorption enthalpies of a single cycle were found to vary with the material and temperature program used. To understand the desorption and adsorption kinetics better, the materials were also tested on X-ray photoelectron spectroscopy, Brunauer–Emmet–Teller, and thermal constants analysers respectively for their elemental composition, structural properties, and thermal conductivity. This paper concludes that many of the naturally available zeolites stand as potential candidates for a sustainable thermochemical energy storage and recovery.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"337 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Functionally graded nanobeams subjected to large deflection by considering surface effects 考虑表面效应的功能梯度纳米梁的大挠度

4区工程技术

Scientia Iranica Pub Date : 2023-09-03 DOI: 10.24200/sci.2023.60997.7113

Yasser Taghipour, Moslem Zeinali

{"title":"Functionally graded nanobeams subjected to large deflection by considering surface effects","authors":"Yasser Taghipour, Moslem Zeinali","doi":"10.24200/sci.2023.60997.7113","DOIUrl":"https://doi.org/10.24200/sci.2023.60997.7113","url":null,"abstract":"In the current study, structurally graded nanobeams with distributed load are subjected to a large deflection analysis that takes surface effects into account. The nanobeams Young's elasticity modulus changes with thickness under a power-law function. The displacement elements are presented, generalization of the Young-Laplace formula is employed to account for the surface effects, and the total Lagrangian finite element formulation is utilized to get the outcomes by cracking the system of nonlinear differential equations founded on the Timoshenko beams theory. The reliability and correctness of the findings are confirmed by comparison with previously published publications. The investigation is done into how various characteristics, including length-to-thickness ratio, material gradient index, boundary conditions, and surface effects, affect the outcomes. The findings demonstrate that, in the presence of surface effects, residual surface tension plays a significant influence on the deflection of nanobeams. Additionally, a comparison of the power-law and exponential kinds of FG distribution is conducted in this study, and it is discovered that the FG materials with the power-law distribution are more applicable since they are less susceptible to surface effects than the exponential type.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Moving Average Control Charts using Uncertain Information for Various Sampling Schemes 使用不确定信息的各种抽样方案的移动平均控制图

4区工程技术

Scientia Iranica Pub Date : 2023-09-03 DOI: 10.24200/sci.2023.59210.6111

Muhammad Aslam, Srinivasa Rao Gadde, Nasrullah Khan

引用次数: 0