This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production ...This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production efficiency.The shipbuilding process involves the complex cutting and arrangement of steel plates,making the optimization of these operations vital for cost-effectiveness and sustainability.Nesting algorithms are broadly classified into four categories:exact,heuristic,metaheuristic,and hybrid.Exact algorithms ensure optimal solutions but are computationally demanding.In contrast,heuristic algorithms deliver quicker results using practical rules,although they may not consistently achieve optimal outcomes.Metaheuristic algorithms combine multiple heuristics to effectively explore solution spaces,striking a balance between solution quality and computational efficiency.Hybrid algorithms integrate the strengths of different approaches to further enhance performance.This review systematically assesses these algorithms using criteria such as material dimensions,part geometry,component layout,and computational efficiency.The findings highlight the significant potential of advanced nesting techniques to improve material utilization,reduce production costs,and promote sustainable practices in shipbuilding.By adopting suitable nesting solutions,shipbuilders can achieve greater efficiency,optimized resource management,and superior overall performance.Future research directions should focus on integrating machine learning and real-time adaptability to further enhance nesting algorithms,paving the way for smarter,more sustainable manufacturing practices in the shipbuilding industry.展开更多
The need to transport goods across countries and islands has resulted in a high demand for commercial vessels.Owing to such trends,shipyards must efficiently produce ships to reduce production costs.Layout and materia...The need to transport goods across countries and islands has resulted in a high demand for commercial vessels.Owing to such trends,shipyards must efficiently produce ships to reduce production costs.Layout and material flow are among the crucial aspects determining the efficiency of the production at a shipyard.This paper presents the initial design optimization of a shipyard layout using Nondominated Sorting Algorithm-Ⅱ(NSGA-Ⅱ)to find the optimal configuration of workstations in a shipyard layout.The proposed method focuses on simultaneously minimizing two material handling costs,namely work-based material handling and duration-based material handling.NSGA-Ⅱ determines the order of workstations in the shipyard layout.The semiflexible bay structure is then used in the workstation placement process from the sequence formed in NSGA-Ⅱ into a complete design.Considering that this study is a case of multiobjective optimization,the performance for both objectives at each iteration is presented in a 3D graph.Results indicate that after 500 iterations,the optimal configuration yields a work-based MHC of 163670.0 WBM-units and a duration-based MHC of 34750 DBM-units.Starting from a random solution,the efficiency of NSGA-Ⅱ demonstrates significant improvements,achieving a 50.19%reduction in work-based MHC and a 48.58%reduction in duration-based MHC.展开更多
Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-...Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-repellent wall）, air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat （FPB） 57 m type model with the following main dimensions： L=2 450 ram, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.展开更多
The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed sh...The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed ship projects due to the high levels of hydrodynamic efficiency that can be achieved,compared to the mono-hull and catamaran hull forms.The purpose of this study is to identify the possible effects of using an unsymmetrical trimaran ship model with configuration（S/L） 0.1-0.3 and R/L=0.1-0.2.Unsymmetrical trimaran ship model with main dimensions： L=2000mm,B=200 mm and T=45 mm.Experimental methods（towing tank） were performed in the study using speed variations at Froude number 0.1-0.6.The ship model was pulled by an electric motor whose speed could be varied and adjusted.The ship model resistance was measured precisely by using a load cell transducer.The comparison of ship resistance for each configuration with mono-hull was shown on the graph as a function of the total resistance coefficient and Froude number.The test results found that the effective drag reduction could be achieved up to 17% at Fr=0.35 with configuration S/L=0.1.展开更多
Multihull ships are widely used for sea transportation, and those with four hulls are known as quadramarans. Hull position configurations of a quadramaran include the diamond, tetra, and slice. In general, multihull v...Multihull ships are widely used for sea transportation, and those with four hulls are known as quadramarans. Hull position configurations of a quadramaran include the diamond, tetra, and slice. In general, multihull vessels traveling at high speeds have better hydrodynamic efficiency than monohull ships. This study aims to identify possible effects of various quadramaran hull position configurations on ship resistance for hull dimensions of 2 m length, 0.21 m breadth, and 0.045 m thickness. We conducted a towing test in which we varied the hull spacing and speed at Fr values between 0.08 and 0.62 and measured the total resistance using a load cell transducer. The experimental results reveal that the lowest total resistance was achieved with a diamond quadramaran configuration at Fr = 0.1-0.6 and an effective interference factor of up to 0.35 with S/L = 3/10 and R/L = 1/2 at Fr = 0.62.展开更多
Objective:To assess the prevalence of Mycobacterium(M.)tuberculosis infection and its associated risks in children under fifteen years of age.Methods:Based on secondary data from the 2018 Indonesian Basic Health Surve...Objective:To assess the prevalence of Mycobacterium(M.)tuberculosis infection and its associated risks in children under fifteen years of age.Methods:Based on secondary data from the 2018 Indonesian Basic Health Survey(RISKESDAS 2018),this cross-sectional study employed M.tuberculosis infection in children as a dependent variable and age level,sex,region,location,family case positive,and smoking as independent variables.Geospatial analysis was applied to show the prevalence of M.tuberculosis infection and multivariate regression was performed to analyze the risk factors of getting the infection among children under 15 years of age.Results:Prevalence ranges of M.tuberculosis infection among children aged 0-14 years,babies(age<12 months),toddlers(age 12-59 months),and children aged between 5 and 14 years were 0.03%to 0.57%,0%to 0.64%,0%to 0.78%,and 0.01%to 0.53%,respectively in Indonesia.A high prevalence of M.tuberculosis infection among children under 15 years of age was found in Papua and other provinces,such as Kalimantan and Java.Contacting with tuberculosis family members was positively associated with M.tuberculosis infection in children as shown by multivariate logistic regression(OR 8.94;95%CI 5.4-14.6,P<0.05).Conclusions:Contacting with family member who has tuberculosis is related with M.tuberculosis infection among children in Indonesia.Therefore,screening the household for contact with tuberculosis patients is a preventive treatment for children.展开更多
In the shipbuilding industry,market competition is currently operating in an intense state.To be able to strive in the global market,the shipbuilders must able to produce ships that are more efficient and can be const...In the shipbuilding industry,market competition is currently operating in an intense state.To be able to strive in the global market,the shipbuilders must able to produce ships that are more efficient and can be constructed in a relatively short amount of time.The piping layouts in the engine room requires a lot of time for the designer to design the best possible route and in a way are not the most efficient route.This paper presents an automatic piping support system in the ship’s engine room based on the Dijkstra’s algorithm of pathfinding method.The proposed method is focused on finding the shortest possible route with a consideration of the following things:cost of the bend pipe,cost of the crossing pipe,cost reduction by pipe support,restriction on piping,reduction of calculation time,and design procedure of piping route.Dijkstra’s shortest path algorithm is adopted to find the shortest path route between the start and goal point that is determined based on the layout of the ship’s engine room.Genetic algorithm is adopted to decide the sequence of the pipe execution.The details of the proposed method are explained in this paper.This paper also discusses the application of the proposed method on an actual ship and evaluates its effectiveness.展开更多
文摘This review article provides a comprehensive analysis of nesting optimization algorithms in the shipbuilding industry,emphasizing their role in improving material utilization,minimizing waste,and enhancing production efficiency.The shipbuilding process involves the complex cutting and arrangement of steel plates,making the optimization of these operations vital for cost-effectiveness and sustainability.Nesting algorithms are broadly classified into four categories:exact,heuristic,metaheuristic,and hybrid.Exact algorithms ensure optimal solutions but are computationally demanding.In contrast,heuristic algorithms deliver quicker results using practical rules,although they may not consistently achieve optimal outcomes.Metaheuristic algorithms combine multiple heuristics to effectively explore solution spaces,striking a balance between solution quality and computational efficiency.Hybrid algorithms integrate the strengths of different approaches to further enhance performance.This review systematically assesses these algorithms using criteria such as material dimensions,part geometry,component layout,and computational efficiency.The findings highlight the significant potential of advanced nesting techniques to improve material utilization,reduce production costs,and promote sustainable practices in shipbuilding.By adopting suitable nesting solutions,shipbuilders can achieve greater efficiency,optimized resource management,and superior overall performance.Future research directions should focus on integrating machine learning and real-time adaptability to further enhance nesting algorithms,paving the way for smarter,more sustainable manufacturing practices in the shipbuilding industry.
基金Supported by Direktorat Riset dan Pengembangan(Directorate of Research and Development)Universitas Indonesia(NKB-690/UN2.RST/HKP.05.00/2022).
文摘The need to transport goods across countries and islands has resulted in a high demand for commercial vessels.Owing to such trends,shipyards must efficiently produce ships to reduce production costs.Layout and material flow are among the crucial aspects determining the efficiency of the production at a shipyard.This paper presents the initial design optimization of a shipyard layout using Nondominated Sorting Algorithm-Ⅱ(NSGA-Ⅱ)to find the optimal configuration of workstations in a shipyard layout.The proposed method focuses on simultaneously minimizing two material handling costs,namely work-based material handling and duration-based material handling.NSGA-Ⅱ determines the order of workstations in the shipyard layout.The semiflexible bay structure is then used in the workstation placement process from the sequence formed in NSGA-Ⅱ into a complete design.Considering that this study is a case of multiobjective optimization,the performance for both objectives at each iteration is presented in a 3D graph.Results indicate that after 500 iterations,the optimal configuration yields a work-based MHC of 163670.0 WBM-units and a duration-based MHC of 34750 DBM-units.Starting from a random solution,the efficiency of NSGA-Ⅱ demonstrates significant improvements,achieving a 50.19%reduction in work-based MHC and a 48.58%reduction in duration-based MHC.
基金Supported by the Directorate for Research and Community Service,University of Indonesia(RUUI Research Laboratory 2010),Jakarta,Indonesia
文摘Ship hull form of the underwater area strongly influences the resistance of the ship. The major factor in ship resistance is skin friction resistance. Bulbous bows, polymer paint, water repellent paint （highly water-repellent wall）, air injection, and specific roughness have been used by researchers as an attempt to obtain the resistance reduction and operation efficiency of ships. Micro-bubble injection is a promising technique for lowering frictional resistance. The injected air bubbles are supposed to somehow modify the energy inside the turbulent boundary layer and thereby lower the skin friction. The purpose of this study was to identify the effect of injected micro bubbles on a navy fast patrol boat （FPB） 57 m type model with the following main dimensions： L=2 450 ram, B=400 mm, and T=190 mm. The influence of the location of micro bubble injection and bubble velocity was also investigated. The ship model was pulled by an electric motor whose speed could be varied and adjusted. The ship model resistance was precisely measured by a load cell transducer. Comparison of ship resistance with and without micro-bubble injection was shown on a graph as a function of the drag coefficient and Froude number. It was shown that micro bubble injection behind the mid-ship is the best location to achieve the most effective drag reduction, and the drag reduction caused by the micro-bubbles can reach 6%-9%.
基金supported by the Directorate for Research and Community Service,University of Indonesia(RUUI Utama 2012),Jakarta,Indonesia
文摘The application of multi-hull ship or trimaran vessel as a mode of transports in both river and sea environments have grown rapidly in recent years.Trimaran vessels are currently of interest for many new high speed ship projects due to the high levels of hydrodynamic efficiency that can be achieved,compared to the mono-hull and catamaran hull forms.The purpose of this study is to identify the possible effects of using an unsymmetrical trimaran ship model with configuration（S/L） 0.1-0.3 and R/L=0.1-0.2.Unsymmetrical trimaran ship model with main dimensions： L=2000mm,B=200 mm and T=45 mm.Experimental methods（towing tank） were performed in the study using speed variations at Froude number 0.1-0.6.The ship model was pulled by an electric motor whose speed could be varied and adjusted.The ship model resistance was measured precisely by using a load cell transducer.The comparison of ship resistance for each configuration with mono-hull was shown on the graph as a function of the total resistance coefficient and Froude number.The test results found that the effective drag reduction could be achieved up to 17% at Fr=0.35 with configuration S/L=0.1.
基金sponsored by the Directorate of Research and Community Services,University of Indonesia(Hibah PUPT-Tambahan UI 2015)
文摘Multihull ships are widely used for sea transportation, and those with four hulls are known as quadramarans. Hull position configurations of a quadramaran include the diamond, tetra, and slice. In general, multihull vessels traveling at high speeds have better hydrodynamic efficiency than monohull ships. This study aims to identify possible effects of various quadramaran hull position configurations on ship resistance for hull dimensions of 2 m length, 0.21 m breadth, and 0.045 m thickness. We conducted a towing test in which we varied the hull spacing and speed at Fr values between 0.08 and 0.62 and measured the total resistance using a load cell transducer. The experimental results reveal that the lowest total resistance was achieved with a diamond quadramaran configuration at Fr = 0.1-0.6 and an effective interference factor of up to 0.35 with S/L = 3/10 and R/L = 1/2 at Fr = 0.62.
文摘Objective:To assess the prevalence of Mycobacterium(M.)tuberculosis infection and its associated risks in children under fifteen years of age.Methods:Based on secondary data from the 2018 Indonesian Basic Health Survey(RISKESDAS 2018),this cross-sectional study employed M.tuberculosis infection in children as a dependent variable and age level,sex,region,location,family case positive,and smoking as independent variables.Geospatial analysis was applied to show the prevalence of M.tuberculosis infection and multivariate regression was performed to analyze the risk factors of getting the infection among children under 15 years of age.Results:Prevalence ranges of M.tuberculosis infection among children aged 0-14 years,babies(age<12 months),toddlers(age 12-59 months),and children aged between 5 and 14 years were 0.03%to 0.57%,0%to 0.64%,0%to 0.78%,and 0.01%to 0.53%,respectively in Indonesia.A high prevalence of M.tuberculosis infection among children under 15 years of age was found in Papua and other provinces,such as Kalimantan and Java.Contacting with tuberculosis family members was positively associated with M.tuberculosis infection in children as shown by multivariate logistic regression(OR 8.94;95%CI 5.4-14.6,P<0.05).Conclusions:Contacting with family member who has tuberculosis is related with M.tuberculosis infection among children in Indonesia.Therefore,screening the household for contact with tuberculosis patients is a preventive treatment for children.
基金supported the Directorate of Research and Community Engagement,Universitas Indonesia,and scheme of Research Collaboration,contract number:NKB-1954/UN2.R3.1/HKP.05.00/2019.
文摘In the shipbuilding industry,market competition is currently operating in an intense state.To be able to strive in the global market,the shipbuilders must able to produce ships that are more efficient and can be constructed in a relatively short amount of time.The piping layouts in the engine room requires a lot of time for the designer to design the best possible route and in a way are not the most efficient route.This paper presents an automatic piping support system in the ship’s engine room based on the Dijkstra’s algorithm of pathfinding method.The proposed method is focused on finding the shortest possible route with a consideration of the following things:cost of the bend pipe,cost of the crossing pipe,cost reduction by pipe support,restriction on piping,reduction of calculation time,and design procedure of piping route.Dijkstra’s shortest path algorithm is adopted to find the shortest path route between the start and goal point that is determined based on the layout of the ship’s engine room.Genetic algorithm is adopted to decide the sequence of the pipe execution.The details of the proposed method are explained in this paper.This paper also discusses the application of the proposed method on an actual ship and evaluates its effectiveness.
