• Energy Research
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• 14. Life underwater close

The increasing energy demand has led to more explorations in the oil and gas industry. To achieve this, marine risers and pipelines are used to convey fluid and other resources to meet the increasing demand. In recent years, hybrid flexible composite risers have become more adaptable. Flexible risers have already proven to be a popular riser solution for various floating production systems in shallow to deepwater in many parts of the world due to their good dynamic behaviour and dependability. The hybrid flexible composite riser is made up of numerous layers of plastics, flexible pipes, composites, and steel. Some innovative monitoring methods, such as Fiber Optics Bragg Gratings (FBG), are based on a clamped composite structure with embedded optical fibre. This study presents characteristics of the monitoring techniques of composite flexible riser technology. The advantages of the monitoring techniques include aiding composite riser measurements, recording data from riser deformation, improving integrity assurance, and dependability of design from stable readings. It also proposes some design approaches as guidelines that are advised, with some policy implications.

The increasing energy demand has led to more explorations in the oil and gas industry. To achieve this, marine risers and pipelines are used to convey fluid and other resources to meet the increasing demand. In recent years, hybrid flexible composite risers have become more adaptable. Flexible risers have already proven to be a popular riser solution for various floating production systems in shallow to deepwater in many parts of the world due to their good dynamic behaviour and dependability. The hybrid flexible composite riser is made up of numerous layers of plastics, flexible pipes, composites, and steel. Some innovative monitoring methods, such as Fiber Optics Bragg Gratings (FBG), are based on a clamped composite structure with embedded optical fibre. This study presents characteristics of the monitoring techniques of composite flexible riser technology. The advantages of the monitoring techniques include aiding composite riser measurements, recording data from riser deformation, improving integrity assurance, and dependability of design from stable readings. It also proposes some design approaches as guidelines that are advised, with some policy implications.

In the present research, we have proposed a new adaptive kernel density estimation method formulated on the theory of linear diffusion processes. By examining the calculation results we have found that in the tail region, our proposed new adaptive kernel density estimation distribution curve becomes very smooth and fits quite well with the histogram of the measured ocean wave dataset at the US National Data Buoy Center station 46026. Carefully studying the calculation results also reveals that the 50-year extreme Power-Take-Off heaving force value forecasted based on the environmental contour derived using the new method is 3021700N, which is much larger than the value 2458700N forecasted via the Rosenblatt-inverse second-order reliability method contour method. Consequently, our proposed new adaptive kernel density estimation method formulated on the theory of linear diffusion processes can forecast well and efficiently forecast the 50-year extreme design force values for offshore sustainable energy systems.

In the present research, we have proposed a new adaptive kernel density estimation method formulated on the theory of linear diffusion processes. By examining the calculation results we have found that in the tail region, our proposed new adaptive kernel density estimation distribution curve becomes very smooth and fits quite well with the histogram of the measured ocean wave dataset at the US National Data Buoy Center station 46026. Carefully studying the calculation results also reveals that the 50-year extreme Power-Take-Off heaving force value forecasted based on the environmental contour derived using the new method is 3021700N, which is much larger than the value 2458700N forecasted via the Rosenblatt-inverse second-order reliability method contour method. Consequently, our proposed new adaptive kernel density estimation method formulated on the theory of linear diffusion processes can forecast well and efficiently forecast the 50-year extreme design force values for offshore sustainable energy systems.

{"references": ["A. Babarit, J. Hals, M.J. Muliawan(2012). Numerical benchmarking study of a selection of wave energy converters. Renewable Energy, 6(7), 131~142.", "Meyer NI, McDonalArnskov M, VadBennetzen CE, etc(2002). B\u00f8lgekraftprogram, Afslutningsrapport, Virum, Denmark RAMB\u00d8LL, Teknikerbyen 31, 2830.", "Previsic M, Bedard R, Hagerman G(2002). E2I EPRI assessment, offshore wave energy conversion devices. Electricity Innovation Institute;Technical report E2I EPRI WP - 004 - US - Rev 1.", "Manases(2010). Dynamics and hydrodynamics for floating wave energy converters. Ph.D. thesis, Lisboa University, Lisboa.52~59", "Nicolai F. HEILSKOV and Jacob V(2012). A non-linear numerical test bed for floating wave energy converters. Book of extended abstracts for the 2ndSDWED Symposium, Copenhagen 524-532.", "Newman J N(1994). Wave effects on deformable bodies .Applied Ocean Research, 16: 47~59.", "Gou Ying, TengBin(2004). Interaction effects between wave and two connected floating bodies. Engineering Science, 6(7), 75~80.", "L. Sun, R. Eatock Taylor and Y.S. Choo (2011). Responses of interconnected floating bodies. The IES Journal Part A: Civil & Structural Engineering, 4(3), 143\u2013156", "Chuankun Wang,Wei Lu (2009) Analysis on ocean energy resources and storage, Ocean press, Beijing, China, 110-116\n[10]\tQin Ye, Zhongliang Yang, Weiyong Shi(2012), The preliminary research on the offshore wave energy resources in Zhejiang province, Journal of Marine Sciences, 30(4) 13-19\n[11]\tJ.N.Newman (1986). Marine Hydrodynamic. Massachusetts Institute of Technology Press, Massachusetts, America, 40-45\n[12]\tYishan Dai, WenyangDuan(2008). Potential Flow Theory of Ship Motions in Waves. National Defence Industry Press, Beijing, China,80-86\n[13]\tZhengban Sheng, YingzhongLiu(2003). Ship manoeuvringandseakeeping, Shanghai Jiao Tong University Press, Shanghai, China, 283-210.\n[14]\tPizer, D.J, Retzler, C.H.Yemm, R.W(2000). The OPD pelamis. Experimental and numerical results from the hydrodynamic work program. European wave energy conference, Aalborg (Denmark), 227-234."]} Based on three dimensional potential flow theory and hinged rigid body motion equations, structure RAOs of Pelamis wave energy converter is analyzed. Analysis of numerical simulation is carried out on Pelamis in the irregular wave conditions, and the motion response of structures and total generated power is obtained. The paper analyzes influencing factors on the average power including diameter of floating body, section form of floating body, draft, hinged stiffness and damping. The optimum parameters are achieved in Zhejiang Province. Compared with the results of the pelamis experiment made by Glasgow University, the method applied in this paper is feasible.

{"references": ["A. Babarit, J. Hals, M.J. Muliawan(2012). Numerical benchmarking study of a selection of wave energy converters. Renewable Energy, 6(7), 131~142.", "Meyer NI, McDonalArnskov M, VadBennetzen CE, etc(2002). B\u00f8lgekraftprogram, Afslutningsrapport, Virum, Denmark RAMB\u00d8LL, Teknikerbyen 31, 2830.", "Previsic M, Bedard R, Hagerman G(2002). E2I EPRI assessment, offshore wave energy conversion devices. Electricity Innovation Institute;Technical report E2I EPRI WP - 004 - US - Rev 1.", "Manases(2010). Dynamics and hydrodynamics for floating wave energy converters. Ph.D. thesis, Lisboa University, Lisboa.52~59", "Nicolai F. HEILSKOV and Jacob V(2012). A non-linear numerical test bed for floating wave energy converters. Book of extended abstracts for the 2ndSDWED Symposium, Copenhagen 524-532.", "Newman J N(1994). Wave effects on deformable bodies .Applied Ocean Research, 16: 47~59.", "Gou Ying, TengBin(2004). Interaction effects between wave and two connected floating bodies. Engineering Science, 6(7), 75~80.", "L. Sun, R. Eatock Taylor and Y.S. Choo (2011). Responses of interconnected floating bodies. The IES Journal Part A: Civil & Structural Engineering, 4(3), 143\u2013156", "Chuankun Wang,Wei Lu (2009) Analysis on ocean energy resources and storage, Ocean press, Beijing, China, 110-116\n[10]\tQin Ye, Zhongliang Yang, Weiyong Shi(2012), The preliminary research on the offshore wave energy resources in Zhejiang province, Journal of Marine Sciences, 30(4) 13-19\n[11]\tJ.N.Newman (1986). Marine Hydrodynamic. Massachusetts Institute of Technology Press, Massachusetts, America, 40-45\n[12]\tYishan Dai, WenyangDuan(2008). Potential Flow Theory of Ship Motions in Waves. National Defence Industry Press, Beijing, China,80-86\n[13]\tZhengban Sheng, YingzhongLiu(2003). Ship manoeuvringandseakeeping, Shanghai Jiao Tong University Press, Shanghai, China, 283-210.\n[14]\tPizer, D.J, Retzler, C.H.Yemm, R.W(2000). The OPD pelamis. Experimental and numerical results from the hydrodynamic work program. European wave energy conference, Aalborg (Denmark), 227-234."]} Based on three dimensional potential flow theory and hinged rigid body motion equations, structure RAOs of Pelamis wave energy converter is analyzed. Analysis of numerical simulation is carried out on Pelamis in the irregular wave conditions, and the motion response of structures and total generated power is obtained. The paper analyzes influencing factors on the average power including diameter of floating body, section form of floating body, draft, hinged stiffness and damping. The optimum parameters are achieved in Zhejiang Province. Compared with the results of the pelamis experiment made by Glasgow University, the method applied in this paper is feasible.

Abstract Although the International Maritime Organization (IMO) introduced the energy efficiency requirements for ships more than a decade ago, to date, inland navigation has not been affected by corresponding regulations at all. Therefore, inland waterway vessels are left with no mandatory requirements that could push their technology into more energy efficient design. Fortunately, there are certain pioneering attempts to define energy efficiency criteria for inland vessels. This paper tries to gather and provide a review of such methods. Moreover, a typical Danube cargo inland vessel’s data are used to evaluate their current energy efficiency levels with respect to provisional criteria. Consequently, two methods are found and used here. They are both based on IMO’s energy efficiency concept but modified for the inland waterway vessels. The methods delivered a significant difference in applicability and were difficult to compare. Moreover, shallow and deep-water effects are explored in the same regard but provided unsound conclusions. The final results displayed discrepancies in energy efficiency levels for the same vessels and so the methodology should be improved and harmonised, if it is to be introduced as mandatory for inland waterway vessels. The analysis provided a glimpse into the current condition of the traditional design of the Danube inland fleet, with respect to the emerging energy efficiency policies.