Pub Date : 2023-10-04DOI: 10.24200/sci.2023.62258.7738
Hossein Tavakoli, Mohammad Shams Esfand Abadi
This paper presents a new spline adaptive filtering (SAF) algorithm based on signed regressor (SR) of input signal. The algorithm is called SR-SAF normalized least mean squares (SR-SAF-NLMS). The SR-SAF-NLMS is established through $L_{1}$-norm constraint to the proposed cost function. In this algorithm, the polarity of the input signal is used to adjust the weight coefficients and control point vectors. Therefore, the computational complexity, especially the number of multiplications, is significantly reduced. Furthermore, the performance of the SR-SAF-NLMS is close to the conventional SAF-NLMS. The good performance of the proposed algorithm is demonstrated through several simulation results in different scenarios.
{"title":"Spline NLMS Adaptive Filter Algorithm based on the Signed Regressor of Input Signal","authors":"Hossein Tavakoli, Mohammad Shams Esfand Abadi","doi":"10.24200/sci.2023.62258.7738","DOIUrl":"https://doi.org/10.24200/sci.2023.62258.7738","url":null,"abstract":"This paper presents a new spline adaptive filtering (SAF) algorithm based on signed regressor (SR) of input signal. The algorithm is called SR-SAF normalized least mean squares (SR-SAF-NLMS). The SR-SAF-NLMS is established through $L_{1}$-norm constraint to the proposed cost function. In this algorithm, the polarity of the input signal is used to adjust the weight coefficients and control point vectors. Therefore, the computational complexity, especially the number of multiplications, is significantly reduced. Furthermore, the performance of the SR-SAF-NLMS is close to the conventional SAF-NLMS. The good performance of the proposed algorithm is demonstrated through several simulation results in different scenarios.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135647148","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}
Pub Date : 2023-10-04DOI: 10.24200/sci.2023.61263.7229
Mahnaz Ebrahimi-Sadrabadi, Bakhtiar Ostadi, Ali Husseinzadeh Kashan, Mohammad Mehdi Sepehri
In recent high-risk and changing world, optimal resource allocation is significant, which in case of inappropriate resource allocation, will cause significant damage to organizations. In resource allocation and where there is a lack of resources, it is imperative to processes continue and the process's resilience and the risks posed by these lack and unsuitable allocations. If resource allocation is not done properly or is done in short supply, there will be consequences, e.g., processes do not continue properly or are not resilient, or they will be increase in the risks of the processes. So, addressing the three mentioned issues such as organizational resilience, business continuity, and risks of the operational processes is of great importance in the problem of resource allocation. Also, the lack of integrated attention to the mentioned issues in the modeling of resource allocation in order to process optimization will lead to a decrease in resources’ utilization. Therefore, in this paper, a novel integrated mathematical model has been developed for resource allocation with considering the process resilience and continuity. Thus, the objective functions of the model are defined according to the four measures of optimal resource allocation such as return, risk, resilience and process continuity.
{"title":"A risk-return based mathematical model for resource allocation with considering the process resilience and continuity","authors":"Mahnaz Ebrahimi-Sadrabadi, Bakhtiar Ostadi, Ali Husseinzadeh Kashan, Mohammad Mehdi Sepehri","doi":"10.24200/sci.2023.61263.7229","DOIUrl":"https://doi.org/10.24200/sci.2023.61263.7229","url":null,"abstract":"In recent high-risk and changing world, optimal resource allocation is significant, which in case of inappropriate resource allocation, will cause significant damage to organizations. In resource allocation and where there is a lack of resources, it is imperative to processes continue and the process's resilience and the risks posed by these lack and unsuitable allocations. If resource allocation is not done properly or is done in short supply, there will be consequences, e.g., processes do not continue properly or are not resilient, or they will be increase in the risks of the processes. So, addressing the three mentioned issues such as organizational resilience, business continuity, and risks of the operational processes is of great importance in the problem of resource allocation. Also, the lack of integrated attention to the mentioned issues in the modeling of resource allocation in order to process optimization will lead to a decrease in resources’ utilization. Therefore, in this paper, a novel integrated mathematical model has been developed for resource allocation with considering the process resilience and continuity. Thus, the objective functions of the model are defined according to the four measures of optimal resource allocation such as return, risk, resilience and process continuity.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135646960","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}
Pub Date : 2023-10-01DOI: 10.24200/sci.2023.60769.6979
M. Spertip, F. Karbalaei, A. Yazdaninejadi
Conservation voltage reduction (CVR) as a readily available technology can easily tackle line congestion besides meeting the energy conservation by a marginal reduction in the voltages of user-end nodes. Although CVR can help to yield clean and sustainable electrifications, application of this technology is limited owing to some unclear technical aspects such as response to industrial loads, load modeling type, and load estimation error. This paper aims at presenting a comprehensive analysis of the CVR process to shed light on the various aspects of this technology for operators who seek to implement it. To this end, CVR process is explored based on load composition on a typical feeder with three zones. Different sizes for active and reactive powers in consumers of those zones are taken into consideration. By doing so, not only CVR process with different load arrangements is explored but also effect of the dominant loads on feeders is unveiled. This study also deals with identifying which load modeling type show better robustness to modeling errors. Moreover, CVR process in the pointed cases are performed with a considerable error on the parameters of load models. The obtained results show that in spite of expectations, CVR may have different outputs.
{"title":"Conservation Voltage Reduction Technology Yields Sustainable Electrifications: An Exploratory Study on Implementation Capability","authors":"M. Spertip, F. Karbalaei, A. Yazdaninejadi","doi":"10.24200/sci.2023.60769.6979","DOIUrl":"https://doi.org/10.24200/sci.2023.60769.6979","url":null,"abstract":"Conservation voltage reduction (CVR) as a readily available technology can easily tackle line congestion besides meeting the energy conservation by a marginal reduction in the voltages of user-end nodes. Although CVR can help to yield clean and sustainable electrifications, application of this technology is limited owing to some unclear technical aspects such as response to industrial loads, load modeling type, and load estimation error. This paper aims at presenting a comprehensive analysis of the CVR process to shed light on the various aspects of this technology for operators who seek to implement it. To this end, CVR process is explored based on load composition on a typical feeder with three zones. Different sizes for active and reactive powers in consumers of those zones are taken into consideration. By doing so, not only CVR process with different load arrangements is explored but also effect of the dominant loads on feeders is unveiled. This study also deals with identifying which load modeling type show better robustness to modeling errors. Moreover, CVR process in the pointed cases are performed with a considerable error on the parameters of load models. The obtained results show that in spite of expectations, CVR may have different outputs.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136059093","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}
Pub Date : 2023-10-01DOI: 10.24200/sci.2023.62478.7883
Khadijeh Moosavi, Hossein Mokhtari
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.
{"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":null,"pages":null},"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}
Pub Date : 2023-10-01DOI: 10.24200/sci.2023.62911.8101
Reza Heibati, Ramin Alipour-Sarabi, Seyed Mohammad Taghi Bathaee
In the previous paper, diverse data acquisition methods based on data types for condition monitoring wind turbines is explored. The present study investigates advanced signal processing techniques in the field of condition monitoring of wind turbines. Methods include synchronous sampling, signal decomposition, envelope analysis, statistical evaluation, model-based approaches, Bayesian methods, and artificial intelligence techniques. Comparison and analysis of these methods and their applications in wind turbine fault detection and diagnosis are presented in this coming study. Moreover, the survey encompasses innovative approaches using various data sources, addressing challenges in components like bearings, gearboxes, blades, and generators. Insights into the evolution of data-driven decision-making in the wind energy sector are provided, with a focus on strengths, limitations, and future directions. A summarized table offers an overview of studies, highlighting monitored components, data types, and methods.
{"title":"A survey on the most practical signal processing methods in conditional monitoring in wind turbines","authors":"Reza Heibati, Ramin Alipour-Sarabi, Seyed Mohammad Taghi Bathaee","doi":"10.24200/sci.2023.62911.8101","DOIUrl":"https://doi.org/10.24200/sci.2023.62911.8101","url":null,"abstract":"In the previous paper, diverse data acquisition methods based on data types for condition monitoring wind turbines is explored. The present study investigates advanced signal processing techniques in the field of condition monitoring of wind turbines. Methods include synchronous sampling, signal decomposition, envelope analysis, statistical evaluation, model-based approaches, Bayesian methods, and artificial intelligence techniques. Comparison and analysis of these methods and their applications in wind turbine fault detection and diagnosis are presented in this coming study. Moreover, the survey encompasses innovative approaches using various data sources, addressing challenges in components like bearings, gearboxes, blades, and generators. Insights into the evolution of data-driven decision-making in the wind energy sector are provided, with a focus on strengths, limitations, and future directions. A summarized table offers an overview of studies, highlighting monitored components, data types, and methods.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136128344","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}
Pub Date : 2023-09-20DOI: 10.24200/sci.2023.61721.7456
Shadi Khalil Moghadam, Farimah Mokhatab Rafiei, Mohammad Ali Rastegar
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%.
{"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":null,"pages":null},"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}
Pub Date : 2023-09-20DOI: 10.24200/sci.2023.59427.6248
Mohammad Ebrahimi, Arezoo Atighehchian, Majid Esmaelian
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.
主手术调度(MSS)程序用于手术室调度的战术层面，其优化创建可以减少患者的等待队列，降低医院成本。患者的住院时间(LOS)对下游资源管理有很大的影响。LOS和手术需求的不确定性增加了MSS创建的挑战。本文的目的是确定与各块手术室手术相结合的MSS方案。为此，提出了一种新的具有概率LOS的多目标MSS问题的数学模型。然后，采用机会约束规划方法处理不确定需求。ε-约束方法用于求解小尺度问题。此外，设计了多目标灰狼优化算法(MOGWO)和非支配排序遗传算法- ii (NSGAII)两种元启发式算法来处理大规模问题。基于结果，MOGWO在MID度量和运行时间方面都优于NSGAII。通过对不同需求不确定性水平下病房容量参数的敏感性分析，帮助管理人员确定合适的病房容量。
{"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":null,"pages":null},"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}
Human behavior analysis and visual anomaly detection are important applications in fields such as video surveillance, security systems, intelligent houses, and elderly care. People re-identification is one of the main steps in a surveillance system that directly affects system performance; and variations in appearance, pose and scene illumination may be challenging issues for such system. Previous re-identification approaches faced limitations while considering appearance changes in their tracking task. This paper proposes a new approach for people re-identification using a descriptor which is robust to appearance changes. In our proposed method the enhanced Gaussian of Gaussian (GOG) and the Hierarchical Gaussian Descriptors (HGDs) are employed to extract feature vectors from images. Experimental results on a number of commonly used people re-identification databases imply the superiority of the proposed approach in people re-identification compared to other existing approaches.
{"title":"Re-Identification in Video Surveillance Systems Considering Appearance Changes","authors":"Zahra Mortezaie, Hamid Hassanpour, Azeddine Beghdadi","doi":"10.24200/sci.2023.57617.5331","DOIUrl":"https://doi.org/10.24200/sci.2023.57617.5331","url":null,"abstract":"Human behavior analysis and visual anomaly detection are important applications in fields such as video surveillance, security systems, intelligent houses, and elderly care. People re-identification is one of the main steps in a surveillance system that directly affects system performance; and variations in appearance, pose and scene illumination may be challenging issues for such system. Previous re-identification approaches faced limitations while considering appearance changes in their tracking task. This paper proposes a new approach for people re-identification using a descriptor which is robust to appearance changes. In our proposed method the enhanced Gaussian of Gaussian (GOG) and the Hierarchical Gaussian Descriptors (HGDs) are employed to extract feature vectors from images. Experimental results on a number of commonly used people re-identification databases imply the superiority of the proposed approach in people re-identification compared to other existing approaches.","PeriodicalId":21605,"journal":{"name":"Scientia Iranica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136073423","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}
Pub Date : 2023-09-10DOI: 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
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.
{"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":null,"pages":null},"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}
Pub Date : 2023-09-03DOI: 10.24200/sci.2023.60029.6559
Mohamad Taghi Ahmadi, F. Ershadi
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.
{"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":null,"pages":null},"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}
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