Freely movable wave energy converters(WECs) will greatly improve their adaptability to the marine environment.In this paper, a dual-mode oscillating water column(OWC) WEC with potential sailing capability is proposed....Freely movable wave energy converters(WECs) will greatly improve their adaptability to the marine environment.In this paper, a dual-mode oscillating water column(OWC) WEC with potential sailing capability is proposed. By opening and closing a gate on the side facing the waves, the WEC converts wave energy in the vertical duct(called VD mode) with low sailing resistance or in the backward bend duct(called BBD mode) with high sailing resistance.A small model and a medium model were designed and manufactured. The capture width ratio(CWR) of the small model in the two modes was experimentally studied. The CWR under bidirectional airflow and conversion characteristics under unidirectional airflow of the medium model in the BBD mode were obtained. Tests of the small model show that the peak CWR is 145.2% under regular waves and 90.1% under random waves in BBD mode, and in VD mode the peak CWR is about 60% of that in the BBD mode. Tests of the medium model show that the peak CWR is 228.96% under regular waves, the maximum wave-to-battery efficiency is 63.36% under regular waves and 30.17%under random waves, respectively.展开更多
A multi-body wave energy converter,consisting of three floats and modeled as a two body problem,is optimised to enhance its mean absorbed power using the Response Surface Optimisation Method.The optimisation focuses o...A multi-body wave energy converter,consisting of three floats and modeled as a two body problem,is optimised to enhance its mean absorbed power using the Response Surface Optimisation Method.The optimisation focuses on two input parameters namely;the floats’diameters and the spacing,in various sea states and at different PTO dampings.A frequency domain analysis is performed for the WEC model scaled at 1∶50 in regular and irregular waves.Obtained results are validated against numerical and experimental data available in the literature.Validations show good agreement against the unmoored model’s added mass,radiation damping,response amplitude operator,mean absorbed power and,capture width ratio.The sea states selected for optimisation are represented by a JONSWAP wave spectrum with,a range of significant wave heights(0.04 to 0.06 m)and a range of peak periods(0.8 to 1.3 s).This corresponds to(2 to 3 m)significant wave heights and(5.6 to 9.2 s)peak periods in full scale.Results show that the optimised WEC model demonstrates good and consistent enhancement of its mean absorbed power and capture width ratio.展开更多
Pseudotolithus typus is one of the two commercially important Sciaenids off Benin nearshore waters mainly fished by beach seining. Unfortunately, since 1994, the production of this species has been decreasing, and inc...Pseudotolithus typus is one of the two commercially important Sciaenids off Benin nearshore waters mainly fished by beach seining. Unfortunately, since 1994, the production of this species has been decreasing, and increasingly more small-sized fishes are regularly harvested, while little is known about the species’ population structure and its life history. Therefore, population structure, probability of capture and size at first capture were investigated using length-frequency data of 1144 specimens sampled from beach seine hauls over a period of 18 months. A total of 54.3% of this population was immature, confirming the domination of smallsized fishes in the catches. Gonad maturation stages were also examined. Frequency distribution of oocyte size exhibited two cohorts of mature oocytes suggesting two spawning periods per year. Monthly averages of gonado-somatic index confirmed that P. typus spawned twice a year during the major warm season (March - May) and during the transition minor warm to minor cold season in October - November. Length at first capture (L75 = 22.76 cm) was smaller than the length at first sexual maturation (L50% = 23.6 cm) indicating a heavy pressure of the beach seine on this resource. To give each fish the chance of reproducing at least once in its lifetime to recruit into the stock, necessary measures such as the size-limit regulation by gradually increasing beach seine mesh size should be developed. Community-based management of the nearshore fishery could contribute to reducing fishing effort during the reproductive periods from February to May and from October to December each year.展开更多
The proton-capture reactions 12C(p,γ)13N and 13C(p,γ)14N have been studied to determine 13C enrichments. The system has been calibrated by measuring the gamma-rays yield from the 12C(p,γ)13N and 13C(p,γ)14N reacti...The proton-capture reactions 12C(p,γ)13N and 13C(p,γ)14N have been studied to determine 13C enrichments. The system has been calibrated by measuring the gamma-rays yield from the 12C(p,γ)13N and 13C(p,γ)14N reactions as a function of known 13C enrichment.This technique is applicable to the analysis of samples with 13C enrichments between 1% and 90%.展开更多
“30*60”双碳背景下,为实现低碳排放,需从低碳政策和低碳技术两个路径进行协调。为此建立了含P2G-CCS(power to gas and carbon capture system,P2G-CCS)耦合和燃气掺氢的虚拟电厂(virtualpowerplant,VPP),并提出了基于阶梯碳交易机制...“30*60”双碳背景下,为实现低碳排放,需从低碳政策和低碳技术两个路径进行协调。为此建立了含P2G-CCS(power to gas and carbon capture system,P2G-CCS)耦合和燃气掺氢的虚拟电厂(virtualpowerplant,VPP),并提出了基于阶梯碳交易机制的VPP优化调度策略。首先,在低碳技术层面,针对P2G-CCS耦合和燃气掺氢子系统,建立了掺氢燃气轮机、掺氢燃气锅炉、两段式电转气(power to gas,P2G)和碳捕集系统(carboncapturesystem,CCS)的数学模型;其次,在低碳政策层面,建立了阶梯碳交易模型对系统碳排放进行约束;最后,在建模基础上,提出了以碳交易成本、购气和煤耗成本、碳封存成本、机组启停成本和弃风成本之和最低为目标函数的优化调度策略。对建立的模型线性化处理后,采用MATLAB调用CPLEX和粒子群算法进行求解,通过设置不同的情景进行对比,验证了所提模型的有效性,并分析了不同固定掺氢比、变掺氢比、不同的阶梯碳交易参数对VPP低碳性和经济性的影响。展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51879253 and U20A20106)。
文摘Freely movable wave energy converters(WECs) will greatly improve their adaptability to the marine environment.In this paper, a dual-mode oscillating water column(OWC) WEC with potential sailing capability is proposed. By opening and closing a gate on the side facing the waves, the WEC converts wave energy in the vertical duct(called VD mode) with low sailing resistance or in the backward bend duct(called BBD mode) with high sailing resistance.A small model and a medium model were designed and manufactured. The capture width ratio(CWR) of the small model in the two modes was experimentally studied. The CWR under bidirectional airflow and conversion characteristics under unidirectional airflow of the medium model in the BBD mode were obtained. Tests of the small model show that the peak CWR is 145.2% under regular waves and 90.1% under random waves in BBD mode, and in VD mode the peak CWR is about 60% of that in the BBD mode. Tests of the medium model show that the peak CWR is 228.96% under regular waves, the maximum wave-to-battery efficiency is 63.36% under regular waves and 30.17%under random waves, respectively.
文摘A multi-body wave energy converter,consisting of three floats and modeled as a two body problem,is optimised to enhance its mean absorbed power using the Response Surface Optimisation Method.The optimisation focuses on two input parameters namely;the floats’diameters and the spacing,in various sea states and at different PTO dampings.A frequency domain analysis is performed for the WEC model scaled at 1∶50 in regular and irregular waves.Obtained results are validated against numerical and experimental data available in the literature.Validations show good agreement against the unmoored model’s added mass,radiation damping,response amplitude operator,mean absorbed power and,capture width ratio.The sea states selected for optimisation are represented by a JONSWAP wave spectrum with,a range of significant wave heights(0.04 to 0.06 m)and a range of peak periods(0.8 to 1.3 s).This corresponds to(2 to 3 m)significant wave heights and(5.6 to 9.2 s)peak periods in full scale.Results show that the optimised WEC model demonstrates good and consistent enhancement of its mean absorbed power and capture width ratio.
文摘Pseudotolithus typus is one of the two commercially important Sciaenids off Benin nearshore waters mainly fished by beach seining. Unfortunately, since 1994, the production of this species has been decreasing, and increasingly more small-sized fishes are regularly harvested, while little is known about the species’ population structure and its life history. Therefore, population structure, probability of capture and size at first capture were investigated using length-frequency data of 1144 specimens sampled from beach seine hauls over a period of 18 months. A total of 54.3% of this population was immature, confirming the domination of smallsized fishes in the catches. Gonad maturation stages were also examined. Frequency distribution of oocyte size exhibited two cohorts of mature oocytes suggesting two spawning periods per year. Monthly averages of gonado-somatic index confirmed that P. typus spawned twice a year during the major warm season (March - May) and during the transition minor warm to minor cold season in October - November. Length at first capture (L75 = 22.76 cm) was smaller than the length at first sexual maturation (L50% = 23.6 cm) indicating a heavy pressure of the beach seine on this resource. To give each fish the chance of reproducing at least once in its lifetime to recruit into the stock, necessary measures such as the size-limit regulation by gradually increasing beach seine mesh size should be developed. Community-based management of the nearshore fishery could contribute to reducing fishing effort during the reproductive periods from February to May and from October to December each year.
文摘The proton-capture reactions 12C(p,γ)13N and 13C(p,γ)14N have been studied to determine 13C enrichments. The system has been calibrated by measuring the gamma-rays yield from the 12C(p,γ)13N and 13C(p,γ)14N reactions as a function of known 13C enrichment.This technique is applicable to the analysis of samples with 13C enrichments between 1% and 90%.
文摘“30*60”双碳背景下,为实现低碳排放,需从低碳政策和低碳技术两个路径进行协调。为此建立了含P2G-CCS(power to gas and carbon capture system,P2G-CCS)耦合和燃气掺氢的虚拟电厂(virtualpowerplant,VPP),并提出了基于阶梯碳交易机制的VPP优化调度策略。首先,在低碳技术层面,针对P2G-CCS耦合和燃气掺氢子系统,建立了掺氢燃气轮机、掺氢燃气锅炉、两段式电转气(power to gas,P2G)和碳捕集系统(carboncapturesystem,CCS)的数学模型;其次,在低碳政策层面,建立了阶梯碳交易模型对系统碳排放进行约束;最后,在建模基础上,提出了以碳交易成本、购气和煤耗成本、碳封存成本、机组启停成本和弃风成本之和最低为目标函数的优化调度策略。对建立的模型线性化处理后,采用MATLAB调用CPLEX和粒子群算法进行求解,通过设置不同的情景进行对比,验证了所提模型的有效性,并分析了不同固定掺氢比、变掺氢比、不同的阶梯碳交易参数对VPP低碳性和经济性的影响。
