Day 3 Thu, September 29, 2022最新文献

{"title":"Development of a Segmented Model for a Medium-Sized Semi-Displacement Vessel","authors":"A. Ibrahim, M. Morabito, W. Beaver","doi":"10.5957/smc-2022-070","DOIUrl":"https://doi.org/10.5957/smc-2022-070","url":null,"abstract":"Segmented models are useful in estimating wave induced loads, particularly for new designs where experience in design loads estimate has not matured yet. Combined with numerical simulation, both methods complement each other and can provide a relatively good estimate of design hydrodynamic loads. This paper discusses efforts at the United States Naval Academy Hydromechanics Laboratory (NAHL) to design, construct and test a 6-foot segmented model of a medium-sized semi-displacement vessel. The vessel is instrumented with a backspline beam, representing the structural stiffness characteristics of the full-scale ship. Model instrumentation is presented including strain gauges placed on the beam as well as local pressure sensors and state of the art Fiber Bragg Grating (FBG) strain and pressure sensors.","PeriodicalId":404590,"journal":{"name":"Day 3 Thu, September 29, 2022","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130306651","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}

{"title":"DC Grids for Ship Propulsion: Benefits and Challenges","authors":"Will Ayers","doi":"10.5957/smc-2022-037","DOIUrl":"https://doi.org/10.5957/smc-2022-037","url":null,"abstract":"While the application of lithium-ion batteries to propulsion has dominated the marine industry’s attention, another equally important shift is occurring. The standard alternating-current (AC) backbone of a diesel-electric is being replaced with direct current (DC). AC generators and motors remain but are connected through converters. This architecture is often referred to as a DC grid. They offer advantages such as reducing volume, weight and electrical harmonics while making it easier to interconnect DC sources like batteries, supercapacitors and fuel cells. Their biggest disadvantage is developing higher fault currents in a shorter amount of time than a comparable AC network. This has required unique protection schemes and led to a challenge for existing regulatory norms.","PeriodicalId":404590,"journal":{"name":"Day 3 Thu, September 29, 2022","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134371046","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}

{"title":"Reaching IMO 2050 GHG Targets Exclusively through Energy efficiency measures","authors":"E. Lindstad, Polic Dražen, A. Rialland, Inge Sandaas, T. Stokke","doi":"10.5957/smc-2022-060","DOIUrl":"https://doi.org/10.5957/smc-2022-060","url":null,"abstract":"Maritime transport accounts for around 3% of global anthropogenic greenhouse gases (GHG) emissions (Well-to-Wake). GHG emissions must be reduced by at least 50% in absolute values by 2050 to contribute to the ambitions of the Paris agreement signed in 2015. Switching to Zero-carbon fuels made from renewable sources (hydro, wind, or solar) is seen by many as the most promising option to deliver the desired GHG reductions. However, renewable energy is a scarce resource that gives a much larger GHG reduction spent within other sectors. This study explores how to reach the IMO 2050 GHG targets exclusively through energy efficiency measures. The results indicate that by combining wind-assisted propulsion (WASP) with a slender hull form, fuel consumption and GHG emissions can be reduced by 30 – 35%, and transport cost by 5 – 10%. In comparison, GHG reductions through Zero-carbon fuels will increase transport costs by 50-200%.","PeriodicalId":404590,"journal":{"name":"Day 3 Thu, September 29, 2022","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133839176","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}

{"title":"A Deep Neural Network to Predict the Residual Hull Girder Strength","authors":"Alessandro La Ferlita, Emanuel Di Nardo, Massimo Macera, Thomas Lindemann, A. Ciaramella, Nikolaos Koulianos","doi":"10.5957/smc-2022-074","DOIUrl":"https://doi.org/10.5957/smc-2022-074","url":null,"abstract":"The main purpose of this study is to apply a Deep Neural Network (DNN) method to linear systems and to predict in a relatively short time span the ultimate vertical bending moment (VBM) for damaged ships. A Deep Neural Network approach, which is composed of multiple fully connected layers with a Rectified Linear Unit (ReLU) which is a non-linear activation function, has been applied to more than 6000 samples and validated using leave-one-out technique. The ultimate strength has been predicted for a set of completely new damage scenarios of different cross sections, enhancing that the deep neural network method can estimate the residual hull girder strength for a correlated damage index general (DIG). The predicted residual hull girder strength as well as the shift of the neutral axis are validated against Smith’s method-based results.","PeriodicalId":404590,"journal":{"name":"Day 3 Thu, September 29, 2022","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122292778","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}

{"title":"Viscous Drift Forces on a Semisubmersible in Waves and Currents","authors":"A. Dev","doi":"10.5957/smc-2022-069","DOIUrl":"https://doi.org/10.5957/smc-2022-069","url":null,"abstract":"Starting from the early sixties and then in the early eighties, it was well established that second-order wave excitation forces exist for floating bodies in regular waves. This force is not only steady (mean) in nature; it also has a low-frequency (difference frequency) and a high-frequency (sum frequency) component force in irregular waves, e.g., in a wave envelope of irregular waves. While potential drift force calculations were entirely accurate for large body structures like tankers, FPSOs, and other bluff bodies, the potential theory-based drift force calculations fell far short (seriously under-predicted) for slender body offshore structures like a semisubmersible. The drift force in a regular wave is dominated by viscous effects resulting in the force itself becoming a function of the third order in the splash zone of the semisubmersible column. Experimental results have validated this. This happens at the low diffraction parameter (κD) and high viscous parameter (H/D). In a waves-only field, the potential drift force remains purely second-order in regular waves due to first-order and second-order pressure. The presence of currents with waves increases the potential drift forces with the additional contribution. The presence of currents along with waves increases the viscous drift force in the splash zone and increases viscous effects on the submerged zone of the semisubmersible like the pontoons and the part of the columns below the splash zone. As the semisubmersible consists of vertical columns (vertical cylinders) and submerged pontoons, extensive experimental works were conducted with a vertical cylinder (resembling the column of a semisubmersible) and with fully submerged pontoons. These tests provided a fundamental understanding of the physics and mechanism of viscous effects in drift forces on semisubmersibles. Finally, numerical works were done using some of the experimental findings. The prediction matched quite well with experimental results for a complete semisubmersible in waves and waves and currents. The prediction method is also helpful in calculating the higher-order environmental forces in station keeping, like static and dynamic mooring analysis, Dynamic Positioning (DP) calculations, especially in time domain DP predictions.","PeriodicalId":404590,"journal":{"name":"Day 3 Thu, September 29, 2022","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123240650","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}