The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation...The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation of green urban spaces for achieving food self-sufficiency by investigating the extent to which sustainable urban farms could be used to reduce the consumption of imported produce in the UK.It also examines urban farming stakeholders'perspective on how food self-sufficiency can help realise the SDGs especially SDG 2(Zero hunger)and SDG 13(Climate action).The study adopts a mixed method approach through a survey with 115 respondents and semi-structured interviews conducted with 12 respondents from 4 different urban farming stakeholder groups.The findings of this study presented a strong correlation between stakeholders who had concerns about where their food came from and the carbon footprint of imported produce.The research shows that,urban farms will no doubt play a vital role in the future of food security in our cities/communities and that the SDGs could be realised through sustainable urban farms implemented within the relevant planning regulations/policies.展开更多
在城市轨道交通系统中,列车的冲击性负荷严重威胁供电安全,且光伏新能源高效消纳也面临挑战。为此,该研究提出一种光伏发电支持的超级电容器混合储能系统(photovoltaic-hybrid energy storage system,PV-HESS)动态功率自洽策略。该策略...在城市轨道交通系统中,列车的冲击性负荷严重威胁供电安全,且光伏新能源高效消纳也面临挑战。为此,该研究提出一种光伏发电支持的超级电容器混合储能系统(photovoltaic-hybrid energy storage system,PV-HESS)动态功率自洽策略。该策略通过引入功率微分阈值k作为系统的动作信号,实时监测列车运行中的功率变化。当功率变化率超过设定阈值时,系统迅速响应,超级电容器释放能量以平抑尖峰负荷。为验证该策略的有效性,构建了仿真模型,并针对不同工况下的微分阈值k进行了仿真分析。结果表明,当微分阈值k设置为2.4 MW/h时,PV-HESS系统能够快速响应,最大动态功率自洽率提高到15.9%,显著降低了尖峰负荷对地铁供电系统的影响。展开更多
In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradien...In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.展开更多
文摘The exponential growth of food demand due to the increasing global population has the potential to seriously threaten the quality and quantity of food supplies due to climate change.This study explores the utilisation of green urban spaces for achieving food self-sufficiency by investigating the extent to which sustainable urban farms could be used to reduce the consumption of imported produce in the UK.It also examines urban farming stakeholders'perspective on how food self-sufficiency can help realise the SDGs especially SDG 2(Zero hunger)and SDG 13(Climate action).The study adopts a mixed method approach through a survey with 115 respondents and semi-structured interviews conducted with 12 respondents from 4 different urban farming stakeholder groups.The findings of this study presented a strong correlation between stakeholders who had concerns about where their food came from and the carbon footprint of imported produce.The research shows that,urban farms will no doubt play a vital role in the future of food security in our cities/communities and that the SDGs could be realised through sustainable urban farms implemented within the relevant planning regulations/policies.
文摘在城市轨道交通系统中,列车的冲击性负荷严重威胁供电安全,且光伏新能源高效消纳也面临挑战。为此,该研究提出一种光伏发电支持的超级电容器混合储能系统(photovoltaic-hybrid energy storage system,PV-HESS)动态功率自洽策略。该策略通过引入功率微分阈值k作为系统的动作信号,实时监测列车运行中的功率变化。当功率变化率超过设定阈值时,系统迅速响应,超级电容器释放能量以平抑尖峰负荷。为验证该策略的有效性,构建了仿真模型,并针对不同工况下的微分阈值k进行了仿真分析。结果表明,当微分阈值k设置为2.4 MW/h时,PV-HESS系统能够快速响应,最大动态功率自洽率提高到15.9%,显著降低了尖峰负荷对地铁供电系统的影响。
基金Supported by the Science and Technology Project of Guangxi(Guike AD23023002)。
文摘In this paper,we propose a three-term conjugate gradient method for solving unconstrained optimization problems based on the Hestenes-Stiefel(HS)conjugate gradient method and Polak-Ribiere-Polyak(PRP)conjugate gradient method.Under the condition of standard Wolfe line search,the proposed search direction is the descent direction.For general nonlinear functions,the method is globally convergent.Finally,numerical results show that the proposed method is efficient.
