Article History: Received: 03 Mar. 2020 Accepted: 29 June. 2021 The small microwave skin depth of sea water as well as the small penetration depth of laser signal in water impose limitations on the application of SAR and Lidar in sea surveillance systems. On the other hand, vessels travelling at sea bring about hydrodynamic anomalies in the sea water called as wake. These hydrodynamic disturbances can be detected by using some techniques such as airborne radio imaging and Extremely Low Frequency (ELF) electromagnetic signal processing. In practice, the motion of conductive sea water anomalies in the natural earth's magnetic field induces ELF magnetic wakes which can be measured via accurate magnetic sensors and detected through signal processing schemes. The physical properties of the hydrodynamic wake as well as those relating to the corresponding magnetic wake are directly related to the vessel parameters such as hull shape, speed and heading. In this work, we firstly derive and formulate the mathematical expressions relating to the aforementioned hydrodynamic and magnetic wakes. By employing derived expressions, a novel detection scheme is proposed based on constructing the 2-dimentional image of the vessel’s magnetic wake through the magnetic signals captured from an array of magnetic sensors, and finally, the relation between the spectral image of the magnetic wake and the vessel heading is studied. We will show that our proposed scheme can detect the existence of a remote vessel as well as its heading from the constructed image with high accuracy, and moreover, it does not have common limitations of existing single-sensor based heading detection schemes.
{"title":"Determination of Vessel Heading using Magnetic Wake Imaging","authors":"M. Fallah, M. Monemi","doi":"10.52547/ijcoe.5.3.19","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.19","url":null,"abstract":"Article History: Received: 03 Mar. 2020 Accepted: 29 June. 2021 The small microwave skin depth of sea water as well as the small penetration depth of laser signal in water impose limitations on the application of SAR and Lidar in sea surveillance systems. On the other hand, vessels travelling at sea bring about hydrodynamic anomalies in the sea water called as wake. These hydrodynamic disturbances can be detected by using some techniques such as airborne radio imaging and Extremely Low Frequency (ELF) electromagnetic signal processing. In practice, the motion of conductive sea water anomalies in the natural earth's magnetic field induces ELF magnetic wakes which can be measured via accurate magnetic sensors and detected through signal processing schemes. The physical properties of the hydrodynamic wake as well as those relating to the corresponding magnetic wake are directly related to the vessel parameters such as hull shape, speed and heading. In this work, we firstly derive and formulate the mathematical expressions relating to the aforementioned hydrodynamic and magnetic wakes. By employing derived expressions, a novel detection scheme is proposed based on constructing the 2-dimentional image of the vessel’s magnetic wake through the magnetic signals captured from an array of magnetic sensors, and finally, the relation between the spectral image of the magnetic wake and the vessel heading is studied. We will show that our proposed scheme can detect the existence of a remote vessel as well as its heading from the constructed image with high accuracy, and moreover, it does not have common limitations of existing single-sensor based heading detection schemes.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49132827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nadia Talebpour, M. Akbarinasab, Masoomeh Rasoolian, Abolfazl Delbari
1 MSc., Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; n.talebpur@stu.umz.ac.ir 2* Associate Professor, Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; m.akbarinasab@umz.ac.ir 3 MSc., Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; m.rasoolian@stu.umz.ac.ir 4 Assistant Professor, Department of Physical Oceanography, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran; abolfazl_delbari@yahoo.com
{"title":"Simulation of Tidal in Khowr-e Musa by Using the TELEMAC Numerical Model","authors":"Nadia Talebpour, M. Akbarinasab, Masoomeh Rasoolian, Abolfazl Delbari","doi":"10.52547/ijcoe.5.3.49","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.49","url":null,"abstract":"1 MSc., Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; n.talebpur@stu.umz.ac.ir 2* Associate Professor, Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; m.akbarinasab@umz.ac.ir 3 MSc., Faculty of Marine and Oceanic Sciences, University of Mazandaran, Iran; m.rasoolian@stu.umz.ac.ir 4 Assistant Professor, Department of Physical Oceanography, Faculty of Marine Science, Khorramshahr University of Marine Science and Technology, Khorramshahr, Iran; abolfazl_delbari@yahoo.com","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46241205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 03 Mar. 2020 Accepted: 29 June. 2021 The primary objective of this paper is probabilistic quantification of the fatigue life of tension-leg platforms (TLP) using reliability methods. The need for such methods stems from the significant uncertainty in the loads exerted on offshore structures. The scope of this paper is limited to the study of fatigue in TLP tendons. For this purpose, nonlinear time-history of force response of the TLP tendon under random-wave load is computed via MOSES software and the damage due to fatigue is estimated in accordance with the Palmgren-Miners rule. Assuming a Rayleigh distribution for stress variation and eight different sea states, the ultimate fatigue damage is computed by accumulating the damage over all individual sea states. This cumulative damage enters the limit-state function that is based on the Palmgren-Miners rule. Prevailing sources of uncertainty in this problem are those in the estimation of fatigue stresses, fatigue strength, and the Palmgren-Miners rule. Finally, reliability analysis is carried out for four different service lives using the firstand second-order reliability methods (FORM and SORM) and Monte Carlo sampling. The results indicate that FORM computes the probability of failure sufficiently accurate. It is concluded that the probability of failure increases drastically with the service life. The importance vector from the sensitivity analysis in FORM reveals that the model error is the most influential source of uncertainty on the probability of failure.
{"title":"Reliability analysis of Tension-Leg Platform Tendon with Respect to Fatigue Failure under Environmental Condition of Caspian Sea","authors":"M. R. Tabeshpour, M. Mahmoudi","doi":"10.52547/ijcoe.5.3.1","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.1","url":null,"abstract":"Article History: Received: 03 Mar. 2020 Accepted: 29 June. 2021 The primary objective of this paper is probabilistic quantification of the fatigue life of tension-leg platforms (TLP) using reliability methods. The need for such methods stems from the significant uncertainty in the loads exerted on offshore structures. The scope of this paper is limited to the study of fatigue in TLP tendons. For this purpose, nonlinear time-history of force response of the TLP tendon under random-wave load is computed via MOSES software and the damage due to fatigue is estimated in accordance with the Palmgren-Miners rule. Assuming a Rayleigh distribution for stress variation and eight different sea states, the ultimate fatigue damage is computed by accumulating the damage over all individual sea states. This cumulative damage enters the limit-state function that is based on the Palmgren-Miners rule. Prevailing sources of uncertainty in this problem are those in the estimation of fatigue stresses, fatigue strength, and the Palmgren-Miners rule. Finally, reliability analysis is carried out for four different service lives using the firstand second-order reliability methods (FORM and SORM) and Monte Carlo sampling. The results indicate that FORM computes the probability of failure sufficiently accurate. It is concluded that the probability of failure increases drastically with the service life. The importance vector from the sensitivity analysis in FORM reveals that the model error is the most influential source of uncertainty on the probability of failure.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41500994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 20 Nov. 2020 Accepted: 28 Aug. 2021 This research investigates the morphodynamic classification of beaches of Iran according to the dimensionless fall parameter (Ω) and the relative tide range (RTR). According to RTR parameter, the southern Iranian coast (Hormozgan province) is mixed wave and tide and the northern Iranian coast (Mazandaran province) is wave-dominated. By using some schemes, the beach states in the north regions of the eastern and central parts of the Mazandaran province are dissipative and in the western part it is intermediate. Also, in the south section in most of the regions of the Hormozgan province, the beach states are ultradissipative, but in some areas low tide terrace and low tide bar/rip occur.
{"title":"Impact of Hydrodynamic Forces on Morphodynamic Classification of Beaches in some parts of the Iranian coasts","authors":"Maryam Shiea-Ali, A. Valipour","doi":"10.52547/ijcoe.5.3.26","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.26","url":null,"abstract":"Article History: Received: 20 Nov. 2020 Accepted: 28 Aug. 2021 This research investigates the morphodynamic classification of beaches of Iran according to the dimensionless fall parameter (Ω) and the relative tide range (RTR). According to RTR parameter, the southern Iranian coast (Hormozgan province) is mixed wave and tide and the northern Iranian coast (Mazandaran province) is wave-dominated. By using some schemes, the beach states in the north regions of the eastern and central parts of the Mazandaran province are dissipative and in the western part it is intermediate. Also, in the south section in most of the regions of the Hormozgan province, the beach states are ultradissipative, but in some areas low tide terrace and low tide bar/rip occur.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46534615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 07 Dec. 2020 Accepted: 16 Sep. 2021 Two numerical models of tsunami generation/propagation have been run in the Makran region. These models are one of the necessary components in the warning systems in this region. The outputs of these models are not in regular international data model standards. In order to get the best result from these models, the models’ outputs must be managed in a database system. An ideal data management system for tsunami warning system has three essential parts included: data convertor, Geographical Information System (GIS) and Relational Database Management System (RDBMS). The schematics and properties of the proposed data management system have been shown in this paper. 3D, spatial, temporal and statistical analysis of tsunami models data exported to the proposed system based on GIS capabilities and data processing routines. Some examples of data analysis of tsunami propagation in the Makran region (north of the Arabian Sea) have been shown.
{"title":"Integration of Geographical Information System and Tsunami generation/propagation models in the Makran region (North of the Arabian Sea)","authors":"M. Moradi","doi":"10.52547/ijcoe.5.3.40","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.40","url":null,"abstract":"Article History: Received: 07 Dec. 2020 Accepted: 16 Sep. 2021 Two numerical models of tsunami generation/propagation have been run in the Makran region. These models are one of the necessary components in the warning systems in this region. The outputs of these models are not in regular international data model standards. In order to get the best result from these models, the models’ outputs must be managed in a database system. An ideal data management system for tsunami warning system has three essential parts included: data convertor, Geographical Information System (GIS) and Relational Database Management System (RDBMS). The schematics and properties of the proposed data management system have been shown in this paper. 3D, spatial, temporal and statistical analysis of tsunami models data exported to the proposed system based on GIS capabilities and data processing routines. Some examples of data analysis of tsunami propagation in the Makran region (north of the Arabian Sea) have been shown.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44254573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 13 Apr. 2021 Accepted: 23 Aug. 2021 Two major research programs on the use of heuristics in decision-making exist, and each has its own set of followers. The first program was initiated by Kahneman and Tversky in the 70s. They primarily concentrated on the errors caused by using heuristics. This has now grown into many heuristics named after their associated biases. The second program was initiated by Gigerenzer and colleagues in Germany. Gigerenzer argues that although simple heuristics sometimes leads to “biased” decisions, they can deliver better answers in some situations. This is particularly true for uncertain or complex environments, where there is only a small data sample or there is no time to formally seek an optimized decision. Gigerenzer and colleagues have generated a substantial body of evidence that humans use simple heuristics, often with great results. Like Kahneman and Tversky, Gigerenzer’s work has attracted researchers exploring the power of “Fast and Frugal” Heuristics, and how they are used by humans. This part, of the four-part paper, discusses Kahneman and Gigerenzer's findings concerning engineering decision making. Avoiding errors when using simple heuristics is discussed in Part IV.
{"title":"Rationality for Engineers Part II- Heuristics and Biases","authors":"S. Yasseri","doi":"10.52547/ijcoe.5.3.7","DOIUrl":"https://doi.org/10.52547/ijcoe.5.3.7","url":null,"abstract":"Article History: Received: 13 Apr. 2021 Accepted: 23 Aug. 2021 Two major research programs on the use of heuristics in decision-making exist, and each has its own set of followers. The first program was initiated by Kahneman and Tversky in the 70s. They primarily concentrated on the errors caused by using heuristics. This has now grown into many heuristics named after their associated biases. The second program was initiated by Gigerenzer and colleagues in Germany. Gigerenzer argues that although simple heuristics sometimes leads to “biased” decisions, they can deliver better answers in some situations. This is particularly true for uncertain or complex environments, where there is only a small data sample or there is no time to formally seek an optimized decision. Gigerenzer and colleagues have generated a substantial body of evidence that humans use simple heuristics, often with great results. Like Kahneman and Tversky, Gigerenzer’s work has attracted researchers exploring the power of “Fast and Frugal” Heuristics, and how they are used by humans. This part, of the four-part paper, discusses Kahneman and Gigerenzer's findings concerning engineering decision making. Avoiding errors when using simple heuristics is discussed in Part IV.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41443992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ahmad Ghafarzadeh, Gholamreza Memarzadeh Tehran, N. Hamidi, N. Mohammadi
1 PhD Student, Department of management, Zanjan Branch, Islamic Azad University, Zanjan , Iran. 2* Associate Professor, Department of management and Economic, Science and research branch، Islamic Azad University, Tehran, Iran (Corresponding Author).Email: Gmemar@gmail.com. 3 Associate Professor, Department of management, Qazvin Branch, Islamic Azad University, Qazvin, Iran. 4 Assistant professor, Department of management, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
{"title":"Application of Fuzzy Cognitive Map to Design the Causal Structure and Analyze the Factors Affecting Good Governance in the Ports and Maritime Organization","authors":"Ahmad Ghafarzadeh, Gholamreza Memarzadeh Tehran, N. Hamidi, N. Mohammadi","doi":"10.52547/ijcoe.5.2.34","DOIUrl":"https://doi.org/10.52547/ijcoe.5.2.34","url":null,"abstract":"1 PhD Student, Department of management, Zanjan Branch, Islamic Azad University, Zanjan , Iran. 2* Associate Professor, Department of management and Economic, Science and research branch، Islamic Azad University, Tehran, Iran (Corresponding Author).Email: Gmemar@gmail.com. 3 Associate Professor, Department of management, Qazvin Branch, Islamic Azad University, Qazvin, Iran. 4 Assistant professor, Department of management, Zanjan Branch, Islamic Azad University, Zanjan, Iran.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43337586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 15 Jan. 2021 Accepted: 27 Apr. 2021 Steel rebar corrosion because of the cracks in marine reinforced concrete (RC) structures is the main type of deterioration that leads to decrease the loadcarrying capacity, ductility, and service life. The use of different fibers such as steel fiber (SF), glass fiber (GF), and polypropylene fiber (PF) in RC beams can reduce the cracks and increase the load-bearing capacity and toughness of RC beams. Moreover, it seems that RC beams containing hybrid of SF, GF, and PF have been higher flexural capacity and toughness rather than RC composites with only one type of fiber. However, the role of mono or hybrid fiber will be depended on environmental conditions. Consequently, load-bearing capacity and toughness of Green RC beam with 15% metakaolin (MK) as a cement replacement, containing SF, PF, GF, (S+P)F, and (S+G)F as fibers, at 28, 90, and 180 days in tidal zone of Oman Sea were determined. The dimension of the beams was 200×200×750 mm. The fibers included macro and microfibers. Macro fiber was steel with 50 mm length. Microfibers were GF and PF with 12 mm length. Results indicated that by the addition of PF, GF, SF, (S+P)F, and (S+G)F to RC beams the load-bearing capacity and toughness are increased up to 41%. Meanwhile, the hybrid effect of fiber was more than the mono one.
{"title":"Effects of Hybrid Fiber on Flexural Behavior of Green RC Beams in Oman Sea","authors":"Hamed Safayenikoo","doi":"10.52547/ijcoe.5.2.1","DOIUrl":"https://doi.org/10.52547/ijcoe.5.2.1","url":null,"abstract":"Article History: Received: 15 Jan. 2021 Accepted: 27 Apr. 2021 Steel rebar corrosion because of the cracks in marine reinforced concrete (RC) structures is the main type of deterioration that leads to decrease the loadcarrying capacity, ductility, and service life. The use of different fibers such as steel fiber (SF), glass fiber (GF), and polypropylene fiber (PF) in RC beams can reduce the cracks and increase the load-bearing capacity and toughness of RC beams. Moreover, it seems that RC beams containing hybrid of SF, GF, and PF have been higher flexural capacity and toughness rather than RC composites with only one type of fiber. However, the role of mono or hybrid fiber will be depended on environmental conditions. Consequently, load-bearing capacity and toughness of Green RC beam with 15% metakaolin (MK) as a cement replacement, containing SF, PF, GF, (S+P)F, and (S+G)F as fibers, at 28, 90, and 180 days in tidal zone of Oman Sea were determined. The dimension of the beams was 200×200×750 mm. The fibers included macro and microfibers. Macro fiber was steel with 50 mm length. Microfibers were GF and PF with 12 mm length. Results indicated that by the addition of PF, GF, SF, (S+P)F, and (S+G)F to RC beams the load-bearing capacity and toughness are increased up to 41%. Meanwhile, the hybrid effect of fiber was more than the mono one.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 25 Feb. 2021 Accepted: 04 Jun. 2021 The truly complex element of modern times is not the technology, but the engineers who develop, design, manufacture, and maintain it. An engineer’s job is to change/improve existing situations into more desirable ones, as well as to respond to the demands or needs of society. Engineers cannot wait until all phenomena and their implications are well understood. Engineers have worked for centuries solving problems with limited information and knowledge and are presumed to be rational decision-makers. Then, how do engineers make their decisions with limited knowledge, time, and cognitive capacity in a variety of domains? Engineers require understanding what part of information can be ignored, and what situations require fast, and timely response, resulting hopefully in a better decision by freeing cognitive capacity to make it. A rational decision-maker should choose an option that maximizes the expected benefits (utilities), although there may be significant hurdles in achieving such goals, especially in emergencies where time pressure is acute. To overcome these hurdles, most engineers revert to “rules-of-thumb”, also known as heuristics. Heuristics are experience-based methods of gut feelings that can be used as an aid to solve specific problems in a particular environment. Heuristics, however, are imperfect; thus, engineers must understand their limitations. Their applicability is also limited by the context under which they were derived as well as their fit with the environment of the problem at hand. The overall objective of these four-part papers is to discuss heuristics and how they can make decision-making easier and faster for engineers. These papers also remind them of their own cognitive biases and describe ways of avoiding them. This first part aims to set the scene by providing background information. These papers address the type of rationality that engineers need to be effective build on the existing literature and liberally draws from them. Engineers cannot march on the spot while thinking for a solution, they must think while moving forward, thus there is a danger not starting on the right foot.
{"title":"Rationality for Engineers: Part I- Setting the scene","authors":"S. Yasseri","doi":"10.52547/ijcoe.5.2.22","DOIUrl":"https://doi.org/10.52547/ijcoe.5.2.22","url":null,"abstract":"Article History: Received: 25 Feb. 2021 Accepted: 04 Jun. 2021 The truly complex element of modern times is not the technology, but the engineers who develop, design, manufacture, and maintain it. An engineer’s job is to change/improve existing situations into more desirable ones, as well as to respond to the demands or needs of society. Engineers cannot wait until all phenomena and their implications are well understood. Engineers have worked for centuries solving problems with limited information and knowledge and are presumed to be rational decision-makers. Then, how do engineers make their decisions with limited knowledge, time, and cognitive capacity in a variety of domains? Engineers require understanding what part of information can be ignored, and what situations require fast, and timely response, resulting hopefully in a better decision by freeing cognitive capacity to make it. A rational decision-maker should choose an option that maximizes the expected benefits (utilities), although there may be significant hurdles in achieving such goals, especially in emergencies where time pressure is acute. To overcome these hurdles, most engineers revert to “rules-of-thumb”, also known as heuristics. Heuristics are experience-based methods of gut feelings that can be used as an aid to solve specific problems in a particular environment. Heuristics, however, are imperfect; thus, engineers must understand their limitations. Their applicability is also limited by the context under which they were derived as well as their fit with the environment of the problem at hand. The overall objective of these four-part papers is to discuss heuristics and how they can make decision-making easier and faster for engineers. These papers also remind them of their own cognitive biases and describe ways of avoiding them. This first part aims to set the scene by providing background information. These papers address the type of rationality that engineers need to be effective build on the existing literature and liberally draws from them. Engineers cannot march on the spot while thinking for a solution, they must think while moving forward, thus there is a danger not starting on the right foot.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70686888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Article History: Received: 16 Oct. 2020 Accepted: 29 Apr. 2021 Dynamic performance of the 3D train–bridge system (TBW model) subjected to different hydrodynamic loads and applying AAR track irregularity is established in this study. By taking a continuous bridge (32 + 48 + 32) m with box girders as a case study, the dynamic responses of the bridge which is under train passing and subjected to several sea hydrodynamic loads are analyzed. The substructure of the bridge includes four concrete solid piers with rectangular sections and piers are fixed at seabed. Piers and decks are designed and analyzed based on dynamic finite elements methods, and hydrodynamic forces are applied on piers according to Morison's theory. Also, car body is modeled by a 27-DoFs dynamic system. Model validation has been performed with another research by considering vessel collision load. Then, the dynamic responses of the bridge and the running safety indices of the train on the bridge under several types of sea wave states when train speed is 300 km/h analyzed. Results of TBW's sensitive analyzes have shown the importance of sea-states conditions for train safe and comfortable running. Also, irregularity has an obvious effect on the dynamic responses of the bridge. It has greater effect on vertical acceleration and displacement than horizontal ones in presence of hydrodynamic load. Combination of these two phenomena (wave and irregularity) jeopardizes the running safety of train when crossing the bridge.
{"title":"Dynamic Stability Analysis of High-Speed Trains Moving over Sea-Cross Bridge subjected to Rail Irregularities","authors":"Amin Razzaghi Kalajahi, M. Esmaeili, J. Zakeri","doi":"10.52547/ijcoe.5.2.56","DOIUrl":"https://doi.org/10.52547/ijcoe.5.2.56","url":null,"abstract":"Article History: Received: 16 Oct. 2020 Accepted: 29 Apr. 2021 Dynamic performance of the 3D train–bridge system (TBW model) subjected to different hydrodynamic loads and applying AAR track irregularity is established in this study. By taking a continuous bridge (32 + 48 + 32) m with box girders as a case study, the dynamic responses of the bridge which is under train passing and subjected to several sea hydrodynamic loads are analyzed. The substructure of the bridge includes four concrete solid piers with rectangular sections and piers are fixed at seabed. Piers and decks are designed and analyzed based on dynamic finite elements methods, and hydrodynamic forces are applied on piers according to Morison's theory. Also, car body is modeled by a 27-DoFs dynamic system. Model validation has been performed with another research by considering vessel collision load. Then, the dynamic responses of the bridge and the running safety indices of the train on the bridge under several types of sea wave states when train speed is 300 km/h analyzed. Results of TBW's sensitive analyzes have shown the importance of sea-states conditions for train safe and comfortable running. Also, irregularity has an obvious effect on the dynamic responses of the bridge. It has greater effect on vertical acceleration and displacement than horizontal ones in presence of hydrodynamic load. Combination of these two phenomena (wave and irregularity) jeopardizes the running safety of train when crossing the bridge.","PeriodicalId":33914,"journal":{"name":"International Journal of Coastal and Offshore Engineering","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70687005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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