• Energy Research
• physical sciences close
• 11. Sustainability close
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AbstractEnergy is the biggest crisis to humanity in the future. Nowadays, most of the energy used on earth comes from oil, gas and coal. According to the recent exploring and consuming rates, the energy will be exhausted in 50-100 years. Whether we can solve the crisis is closely related to the survival of humanity on the earth. The irradiation from the sun is the biggest energy source. Building PV power plant to utilize the energy from sun will be an only way to sustain the life cycle on the earth. However, the development of PV power plants require the huge supply of PV cell and the fabrication process may bring a quantity of pollution and waste, which is harmful to the environment. On the other hand, super large PV power plant will occupy huge land. If the land cannot be explored and used reasonably, this will not benefit the human life either. In this article, we address the discussions about the above problems and propose the initial suggestions about development trend of PV industry and the safety operation mode of super PV power plant.

AbstractUsing a low supply water temperature in heating conditions and a high water temperature during cooling can increase energy efficiency, use renewable energy sources, and provide a comfortable and healthy indoor climate. High temperature cooling and low temperature heating is achieved by reducing temperature difference in heat trans er and energy transportation process. The losses in temperature difference can be classified into three types: by heat/moisture exchange; by energy transportation through air/water circulation; by indoor terminal that releases heat/cooling to indoor condit oned space. The air handling process of HVAC system and indoor terminals are the key factor of reducing temperature differen e.Aiming at the losses in HVAC system, Annex 59, titled High Temperature Cooling & Low Temperature Heating in Buildings, is a new international cooperative work under the framework of International Energy Agency (IEA) Energy in Buildings and Communities (EBC). This paper introduc s the background, scope, objective, structure and deliverables of Annex 59. Annex 59 will try to present a new perspective and a new concept to analyze HVAC system in buildings. The goal of the Annex is to build up new concept of analyzing HVAC system from the perspective of reducing mixture loss and transfer loss and th n apply it in high temperature cooling and low temperature heating system.

With the prosperous development of the urban metro network, the characteristics of the topological structure and node importance are changing dynamically. Most studies focus on static comparisons, and dynamic evolution research is rarely conducted. It is necessary to track the dynamic evolution mechanism of the metro network from the perspective of development. In this paper, the Shenzhen Metro Network (SZMN) topology from 2004 to 2021 was first modeled in Space L. Five kinds of node centralities in eight periods were measured. Then, the dynamic evolution characteristics of the SZMN network topology and node centralities were compared. Finally, an improved multi-attribute decision-making method (MADM) was used to evaluate the node importance, and the spatiotemporal-evolution mechanism of the node importance was discussed qualitatively and quantitatively. The results show that, with the spatiotemporal evolution of the SZMN, the nodes became more and more intensive, and the network tended to be assortative. The different kinds of node centralities changed variously over time. Moreover, the node importance of the SZMN gradually dispersed from the core area of Chegongmiao–Futian to the direction of the Airport and Shenzhen North. The node importance evolves dynamically over time, and it is closely related to the changes in the node type, surrounding nodes and whole network environment. This study reveals the dynamic evolution mechanism of the complex topology and node importance in the SZMN, which can provide scientific suggestions and decision support for the planning, construction, operation management and resilient sustainable development of the urban metro.

Abstract With the plan to increase nuclear generating capacity to 58 GWe and more than 30GWe under construction by 2020, China would have to confront the challenge from the transportation safety of nuclear material. In this paper, based on the analysis of transportation systems and the accident scenarios, the safety evaluation index system of spent fuel road transportation was established by using analytic hierarchy process (AHP), and the transportation safety evaluation model was constructed by weighted nearest neighbor method. By using the model, the safety evaluation of spent fuel road transportation in DaYa Bay nuclear power plant was carried out. The evaluation results showed that the whole transportation was safe, though it has safety risk caused by the weather and the junctions of the bridges and tunnels. In addition, the results from the fuzzy comprehensive evaluation method and the weighted nearest neighbor method are compared, which indicated that the weighted nearest neighbor method supplied a better decision support during the spent fuel road transportation.

Mass transport phenomenon was first recognized by Stokes in 1847 using a Lagrangian description. Later, a basic theory for the mass transport in water waves in viscous fluid and of finite depth was derived by Longuet-Higgins in 1953. Theoretical solutions of mass transport in progressive waves of permanent type are subjected to the definitions of wave celerity in deriving the various finite amplitude wave theories. As it has been generally acknowledged that the Stokes wave theory can not yield a correct prediction of mass transport in the shallow depths, some new theories have been developed. Recently the authors(1974 § 1977) have derived a new finite amplitude wave theory in shallow water for quasi- Stokes and cnoidal waves by the so-called reductive perturbation method, in which the mass transport is formulated both in Lagrangian and Eulerian descriptions. On the experimental verification, Russell and 0sorio(1957) investigated and compared Longuet-Higgins' solution with experimental data of Lagrangian mass transport velocity obtained in a normal closed wave tank of finite length. Since then, many investigations, and nearly all of them, have employed the finite length of wave tank in carrying out their experiments. However, no experiment has yet been attempted at verifying the Stokes drift in progressive waves of permanent type in a wave tank of infinite length. It is not realistic nor economical in constructing such an infinitely long flume to investigate experimentally the mass transport velocity in progressive waves. Instead of using such an ideal wave tank, a new one incorporated with natural water re-circulation was equipped to carry out experiments by the authors(1978). It was confirmed from these experiments that mass transport in progressive waves of permanent type exists in the Same direction of wave propagation throughout the depth, and agrees with both the Stokes drift and the authors' new formulations, within the test range of experiments.