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Abstract For the past two decades, extensive research has been conducted to evaluate the performance of urban form scenarios such as sky view factors, solar radiation, or energy performance. Simulation-based performance analysis has been applied for optimizing urban design using multiple performance criteria of energy demands, daylighting, or radiance. Two major limitations exist in the performance evaluation methods of urban design: 1) the number of urban design alternatives or scenarios has been limited, and 2) various performance criteria and metrics have not been assessed synthetically. In this respect, we aim to generate all possible alternatives under constraints such as a city policy or development requirements. This paper addresses the integration of generative design and multi-criteria performance analysis for urban design decision making. The relationships between geometric urban forms and multiple performance criteria are identified. The proposed methodology incorporates the reinforcement learning algorithm, an advanced machine learning technique, along with parametric modeling techniques, to enhance urban design decisions based on various performance criteria. This methodology was tested on the design of an international campus of the Georgia Institute of Technology, located in Shenzhen, China. An algorithm generates numerous geometrical alternatives of campus design under site constraints and development requirements of the campus. Those alternatives are then evaluated based on performance criteria of sky openings, solar radiation, or energy consumption synthetically. The method enables an integrated performance analysis for all possible design under constraints. The paper proposes a data driven urban design approach that connect generative design and multi-criteria performance analyses. The relationships between urban geometric forms and performance criteria function derive guidelines for a sustainable and green campus. In future conduct multivariate analysis to examine the relationships between geometric elements and performance measurement metrics. [ABSTRACT FROM AUTHOR]

Abstract By constructing a dynamic spatial Durbin model based on C-D production function that includes energy consumption and air pollution, this paper explains the driving factors of urban economic output in the "2+26" cities of Beijing-Tianjin-Hebei and its surrounding areas during 2006-2015. The result shows the significant spatial autocorrelation of energy consumption and air pollution in the "2+26" cities. The increase in economic output of neighbouring cities will bring about economic radiation and promote the economic output of the city, which provides strong evidence for the necessity of joint prevention and control policy. Further considering effects of the inputs of neighbouring cities, the paper finds that the driving force of economic increase mainly came from the capital and energy input of the city itself, as well as the air pollution dividends of neighbouring cities. Therefore, Beijing-Tianjin-Hebei and its surrounding areas should make the best of the resource advantages of neighbouring cities to achieve complementarity and coordinated development. Governments should construct comprehensive cross-city air pollution prevention mechanism, such as regional air pollution compensation mechanism and fund for air pollution joint control. [ABSTRACT FROM AUTHOR]

Abstract Shipping is a major contributor to the global CO 2 emissions. In order to reduce the ship emissions, various mitigation strategies have been proposed including technical and operational strategies. As it is usually not possible to implement all these mitigation strategies, it is important to evaluate the efficiency of these strategies. For mitigation strategies evaluation, ship energy systems are often used for assessment from a systems perspective. However, ship energy systems are usually quite complex for analysis. This is because they are constructed by many components and these components may have non-linear correlations. In this paper, a Gaussian process metamodel based method is proposed to evaluate the ship mitigation strategies. This method is much more efficient than directly analyzing the ship energy systems when they are computationally expensive to assess. A ship energy system of a chemical tanker is analyzed in this paper. The results indicate that speed reduction has a large abatement potential and all the considered strategies have correlations with each other. [ABSTRACT FROM AUTHOR]

Abstract The paper reviews the processes of Geodesign, as it is currently used in practice, and explore its capability and limitation to adapt to new smart city design and technology. Predictions about the future city are being attempted based on data that is for all intents and purposes based on the distant past. In the smart city, where data is both ubiquitous and continuous, it is possible to use metadata to quickly gain an understanding of how the future city is designed and how the current urban system can be altered. Existing building energy data of eight housing units in the Sumida neighborhood of Tokyo was collected using smart meters. This data was analyzed to determine how the buildings perform in real-time, compared to how the energy models predict the building performance. This comparison showed that the existing buildings are using more energy than the current models predict. There is potential that better utilizing data can help designers and planners come closer to meeting community goals. There is also potential that as we integrate more smart city technologies into our cities for improving future city model, or the change model in Geodesign. This paper discussed how other variables that can be incorporated into larger-scale problems, in which an object-oriented city design model is proposed based on a network of objects and multiple system boundaries. [ABSTRACT FROM AUTHOR]

Abstract Thermal energy storage (TES) has a crucial role to play in conserving and efficiently utilising energy, dealing with mismatch between demand and supply, and enhancing the performance and reliability of our current energy systems. A competitive TES technology requires a number of scientific and technological challenges to be addressed including TES materials, TES components and devices, and integration of TES devices with energy networks and associated dynamic optimization. This paper concerns mainly about TES materials challenges with a specific focus on using shape stable composite phase change materials (CPCMs) for medium and high temperature application. The paper first briefly reviews the state-of-the-art development of materials research for thermal energy storage. The focus is then on CPCMs for medium to high temperatures applications, covering materials screening, formulation based on molecular modelling validated at a different length scale through experiments, formulation based on chemical and physical compatibility, and manufacture of material modules via innovative use of conventional powder technology. The properties of the materials and materials modules are characterised and analysed with an aim to establish property-structure relationships. This includes a particularly interesting aspect of the motion of PCM and nanoscale objects with the PCMs for heat transfer enhancement during thermal cycling, which explains the mechanisms of the encapsulation of PCMs in the composite. [ABSTRACT FROM AUTHOR]

Abstract This paper reviews different methods for determination of specific heat capacity of lithium-ion batteries. Thermal modelling of lithium-ion battery cells and battery packs is of great importance. The specific heat capacity of the battery is an essential parameter for the establishment of the thermal model, and it is affected by many factors (such as SOC, temperature, etc.). The scientific purpose of this paper is to collect, sort out and compare different measurement methods of specific heat capacity of battery. The advantages and disadvantages of different methods are discussed. The applicability of each measurement method for various battery types and the required experimental conditions are discussed. The factors influencing the specific heat capacity of the battery are also summarized. [ABSTRACT FROM AUTHOR]

Abstract In China, renewable energy is expected to account for a larger proportion of electric power systems although regional and intermittent characteristics have led to enormous unused wind and solar power stations in western and northern China. In the mean-while, there exists a large demand on energy in central and eastern areas. The energy storage capability of hydrogen makes it a significant medium for emerging energy storage systems. But the formidable challenge of hydrogen storage and long-distance transportation restricts its development. To address this issue, this paper proposes a scheme for an ammonia-based energy storage system in which ammonia, an environmentally benign hydrogen carrier, is expected to compromise the conflicts of renewable energy supply and consumption in China. By utilizing abandoned wind power and solar power, we get electrolyze water to generate hydrogen and get air to generate nitrogen. Compositing ammonia with hydrogen and nitrogen using Hubert's method also need much electricity. And the power stored in ammonia can be released in form of thermal energy or electricity when needed. This paper then presents some typical applications of ammonia that can meet people's needs of fuel, power, electricity, and zero-carbon fertilizer. The proposed scheme is particularly useful for storing discarded power in western and northern China in ammonia which can be transported and used in eastern regions without regional and seasonal restrictions. As an extra advantage, oxygen as a side product associated with the production of ammonia may play a significant role in oxygen-riched combustion plants. [ABSTRACT FROM AUTHOR]

Abstract The temperature of exhaust gas can exceed 800K, which is much higher than surroundings. It's easy to demonstrate IR and get bombed. Therefore, it's necessary to lower the temperature of exhaust gas. In this paper, a kind of infrared suppressor which uses engine exhaust to eject cold air and water spray is designed. Water spray is produced by ultrasonic atomization. The mixing process of the ejector is revealed by CFD. CFD results are validated with the experimental values. After validation is satisfied, this paper analyzes the temperature field inside the ejector and compares the performances of ejectors with varying geometries. According to CFD results, a device is made. Test results show that a good performance is achieved: radiation energy is only 36% of the original. [ABSTRACT FROM AUTHOR]

Abstract Quantum dots (QDs) are the potential material for the application in optical thermometry, and have been successfully applied to solar cells, LEDs, bio-labeling, structural health monitoring, etc. In this paper, we study the fluorescence properties of CdSe/ZnS QDs in toluene under the action of heating-cooling cycles. The experimental results show that, in a heating-cooling cycle, increasing temperature causes red-shift of the emission peak and the decrease of the PL intensity, and decreasing temperature causes blue-shift of the emission peak and the increase of the PL intensity. The surface structures of the QDs likely are dependent on the cycle numbers, which cause the change of the excited energy state of the QDs in toluene. The results presented in this paper reveals the strong effects of cyclic temperature on the photoluminescence characteristics of QDs. [ABSTRACT FROM AUTHOR]

Abstract This paper introduces the similarity between the mechanism of carbon trading and blockchain, then it elaborates on the application of blockchain in carbon trading. In corporate carbon trading, blockchain technology can record and transfer information flow reliably, realize point-to-point transactions between suppliers and demanders to achieve "decentralization", help to reduce the entry threshold for the carbon trading market. At the same time, an analysis of social environment for blockchain-based carbon trading on person is made. Finally, the paper confirms the value of "blockchain + carbon trading" and looks forward to the future. [ABSTRACT FROM AUTHOR]

Abstract To match for the different temperature of the geothermal resource and strengthen the flexibility of organic Rankine cycle (ORC), this paper proposes a variable capacity power generation superstructure based on Flash and ORC for geothermal energy. A combined Flash-ORC experimental prototype is established to investigate its performance on both steady and dynamic conditions in this paper. Pressured hot water is adopted as the extensive worldwide existed hydrothermal geothermal resource, eliminating the influence of the used heat transfer oil on evaporating process. The experiment results show that there is an optimal mass flow rate of R245fa under the condition of different heat source temperature; Flash and binary power system dominate the flash-binary power system respectively when the heat source temperature are 120 ℃and 130℃;The isotropic efficiency of modified compressor just between 0.2 and 0.25; the power output of per geofluid mass flow rate are 0.78 kWh·t-1and 1.31 kWh·t-1 respectively when the heat source temperature are 120 ℃and 130℃. [ABSTRACT FROM AUTHOR]

Abstract Wind power, solar power and hydropower can form a good complementary effect in space and time. Research on Wind-Solar-Hydro power generation system has gradually become a hot research topic. In this paper, a large-scale hydropower station in southwestern China and its surrounding wind fields and solar fields are taken as examples to establish an optimal scheduling model with the objectives of maximizing system total power generation, maximizing the minimum monthly joint output of the whole scheduling period, and minimizing the ecological over-and-short discharge. The paper presents a multi-objective dragonfly algorithm base on reference point to obtain the non-dominated solutions in the wet year, normal year and dry year. Meanwhile, the scheduling processes of four representative plans on the obtained Pareto front are selected to analyze its certain practical significance. It is found that the established multi-objective optimal model and the proposed algorithm have certain reference value for the optimal operation of Wind-Solar-Hydro power generation system. [ABSTRACT FROM AUTHOR]

Abstract In this paper, based on the study of the effect of indoor natural ventilation, application of earth-air heat exchanger cooling technology in an office was investigated. Taking an office building in Jinan City as an example, this research analyzed the performance of interactions between earth-air heat exchanger cooling technology and building indoor thermal environments. Indoor thermal environment was analyzed with numerical simulation of computational fluid dynamics, the Airpak software was applied for numerical calculation to gain the indoor temperature field, velocity field and the distribution of the PMV index. In addition, energy utilization efficiency was also analyzed in this paper; results showed that reasonable airflow organization is a significant content in airflow design of office rooms under the small temperature difference of earth-air heat exchanger conditions. This will provide basic reference for design of earth-air heat exchanger cooling system. [ABSTRACT FROM AUTHOR]

Abstract Generally, the hourly average wind speed is used in determining the spare capacity and real-time dispatch in power system, but the actual wind speed on the wind turbine is the actual instantaneous wind speed. An indicator (instantaneous variance) that quantify the variability of wind speed (WS) and wind power (WP) is used in this paper, and the experiments prove the rationality of it. Meanwhile, the relationship between the fluctuation of WS and the fluctuation of WP is discussed by using local maximum and minimum points distributions. According to the methods mentioned in this paper, the index applied to quantification of fluctuation is applicable to the schedule of system spinning capacity and the strong consistency of the fluctuations of WS and WP has been proved. [ABSTRACT FROM AUTHOR]

Abstract To realize the commercialization of SOFC, it must be ensured that it can work efficiently and stably. SOFC fault diagnosis becomes an essential part of the research. Due to the strong coupling of faults in the stack, this paper uses neural network algorithm to detect and diagnose faults. The simulation results verify that through the diagnosis of the test sample, the recognition rate of the test sample by the network is found to be 95%, which explains the neural network fault diagnosis model established in this paper on identifying the normal working state of the stack, the electrode stacking of the stack, and the gas leakage fault of the stack has good effectiveness and accuracy. [ABSTRACT FROM AUTHOR]

Abstract The admittance model for the three-phase AC micro-grid is proposed in the paper considering the imbalance of the local load and active compensation of the multi-functional grid-connected inverter (MFGCI). By adopting complex variables, the model unified the positive-sequence and negative-sequence admittances for both the grid-connected inverter and the load. Moreover, the dq transformation based imbalance compensation algorithm is integrated into the model according to the harmonic linearization principle. The theoretical analysis and simulation verify the accuracy of the proposed admittance model. The analysis also indicates that while the adoption of the active compensation can decrease the imbalance of the system, the magnitude and phase characteristics of the equivalent admittance of the compensated load are significantly changed. The admittance model proposed in this paper can be the foundation work for the system stability study for the AC micro-grid. [ABSTRACT FROM AUTHOR]

Abstract Solid oxide fuel cell is a device that can convert chemical energy directly into electricity. Its advantages, such as high efficiency, low emission, quiet operation, fuel flexibility, bring about the broad application prospect. However, it is difficult to obtain the temperature distribution in the existing planar cross flow solid oxide fuel cell through the experiment. In this paper, a control orient two-dimensional differential equation model is established for a planar cross flow solid oxide fuel cell based on the finite node method, and an iterative algorithm for calculating the real time voltage of the fuel cell is proposed for the model. Based on the model, the temperature distribution of the fuel cell in the test and system configuration is simulated. The simulation results show that the model can reflect the thermoelectric characteristics of the planar cross flow solid oxide fuel cell, especially the temperature distribution of the fuel cell. The SOFC temperature distribution modeling in this paper is helpful for the development of temperature distribution observers and design related control methods in later studies. [ABSTRACT FROM AUTHOR]

Abstract This paper describes an integrated power unit (IPU) supplying bleed air and shaft power for main engine starting, aircraft environment control, and in-flight emergency power demand. The zero-dimension steady-state numerical simulation model of the IPU is built for both the normal air breathing (NAB) mode and the stored energy (SE) mode. The design point of the IPU is set in the NAB mode and the off-design performance calculations are accomplished for both modes. The Altitude-Mach characteristic of the NAB mode and the altitude characteristic of the SE mode are discussed and the fundamental control laws of the SE mode are established to minimize stored air consumption. The overall efficiency of the IPU is illustrated in the paper for the two modes. [ABSTRACT FROM AUTHOR]

Abstract The diversity of both organic fluids and performance criteria makes the selection and evaluation of working fluids for organic Rankine cycles (ORCs) full of challenge. To overcome this challenge, this paper first reports on second-law-based analytical expressions for thermal efficiency and a turbine size parameter, which reveal key dimensionless parameters relating to operating temperatures and thermodynamic properties of organic fluids. This paper systematically screens more than 70 working fluids involving a wide range of physical and chemical properties. This study shows that specific turbine size generally increases with critical temperature, reduced ideal gas heat capacity, and the atom number of working fluids. Different-family fluids may lead to ten-fold relative differences in specific turbine size even though they have the same atom numbers. The thermal efficiency of ORCs appears to be independent of critical temperature, or at most, a weak function of critical temperature for low boiling point wet fluids and other halocarbons. This is a result of Jacob number being independent of or dependent weakly on the critical temperature of organic fluids such as alkanes, alkenes, and benzenes. [ABSTRACT FROM AUTHOR]

Abstract Air pollution and increased CO 2 concentration in atmosphere and other energy related issues caused a transformative shift in energy system which contributes to increased utilization of renewables as alternative to generate green energy carriers. The potential of renewable resources in different region and potential energy conversion have been largely considered by many researcher in many countries. The energy conversion technologies to produce heat, electricity, and transportation fuels have made impressive technical advances. Sweden has also been challenging with mitigation of CO 2 emission and trying to shift into a fossil fuel free system in all energy sectors. This paper deals with the current status of fuel demand and supply in the transport sector in a County in Sweden. A scenario for a fossil fuel free transport sector at a regional level is developed to investigate the potential biofuel production from regionally produced straw. The results and analysis indicate that the potential for cereal based bioethanol production in the region is sufficient to meet the biofuel demand of the County. Using the fallow land for cereal cultivation, it is feasible to shift into a fossil fuel free transportation system where all passenger cars are fueled by bioethanol. The results and finding from the current paper will be used to develop further study on optimization of local biofuel production integrated with CHP plants considering application of other feedstock such as municipal wastes. [ABSTRACT FROM AUTHOR]