An agent-based procedure with an embedded agent learning model for residential land growth simulation: The case study of Nanjing,China

The agent-based modelling (ABM) is commonly used to simulate urban land growth. A key challenge of ABM for the simulation of urban land-use dynamics in support of sustainable urban management is to understand and model how human individuals make and develop their location decisions that then shape urban land-use patterns. To investigate this issue, we focus on modelling the agent learning process in residential location decision-making process, to represent individuals' personal and interpersonal experience learning during their decision-making. We have constructed an extended reinforcement learning model to represent the human agents' learning when they make location decisions. Consequently, we propose and have developed a new agent-based procedure for residential land growth simulation that incorporates an agent learning model, an agent decision-making model, a land use conversion model, and the impacts of urban land zoning and the developers' desires. The proposed procedure was first tested by using hypothetical data. Then the model was used for a simulation of the urban residential land growth in the city of Nanjing, China. By validating the model against empirical data, the results showed that adding agent learning model contributed to the representation of the agent's adaptive location decision-making and the improvement of the model's simulation power to a certain extent. The agent-based procedure with the agent learning model embedded is applicable to studying the formulation of urban development policies and testing the responses of individuals to these policies.     

Multi-field coupling thermo-acoustic radiation using free-standing nano-thin films in a static magnetic field

Abstract

Thermo-acoustic radiation from nano-thin film has been widely reported these years. In this paper, a static magnetic field is introduced to enhance the acoustic power in the multi-field thermo-acoustic generation. The coupled thermo-acoustic system in a static magnetic field shares the same acoustical unit with very few additional components. In the presence of a static magnetic field, thin-film vibration is excited instead of being still in the classical thermo-acoustic system. Not surprisingly, a steady magnetic field has very little impact on the thermo-acoustic generation system when a constant amplitude sinusoidal current is introduced. The oscillation perpendicular to the nano-thin film is driven by the electromagnetic force. The system response of thermo-acoustics and magneto-acoustics can be generally matched when suitable parameters are introduced. The acoustical pressure output can be significantly improved in the presence of a static magnetic field although more electrical input power should be provided in the multi-field thermo-acoustic system. Evidently, the coupled multi-field acoustical system is able to handle more electrical power input and the power input can be more easily dissipated relatively. The results show that the acoustic response of this new multi-filed coupled system can be significantly improved as compared to the classical system without magnetic effects.     

Effect of storage time and temperature on hydrogen fermentation of food waste

Practically, before being fed to the treatment plant, food waste (FW) is stored for up to a week in a storage tank under ambient temperature condition, which would have an impact on the bioenergy yield. In the present work, FW was stored at different temperatures (5 °C, 20 °C, and 35 °C) for 0 d, 1 d, and 2 d, and it was used as a feedstock for mesophilic H₂ fermentation. H₂ production curves were divided by three groups, finally attaining 1.7–1.8 mol H₂/mol hexose_added, 1.4–1.5 mol H₂/mol hexose_added, and 1.2 mol H₂/mol hexose_added, achieved from the (fresh, FW stored at 5 °C), (FW stored at 20 °C, and 35 °C for 1 d), and (FW stored at 35 °C for 2 d), respectively. The different performance was attributed to the growth of indigenous lactic acid bacteria such as Lactobacillus and Weissella during storage under high temperature condition. In addition, it was found that the activity of homoacetogenic reaction (R17, 4H₂ + CO₂ → Acetate) calculated by establishing metabolic flux balance was different depending on the H₂ production performance. The flux of R17 ranged 0.03–0.06 under low H₂ yield achieved conditions, while it increased to 0.10–0.17 those showing low H₂ yields.     

Strength and dilatancy behaviors of deep sands in Shanghai with a focus on grain size and shape effect

With rapid development of infrastructures like tunnels and open excavations in Shanghai, investigations on deeper soils have become critically important. Most of the existing laboratory works were focused on the clayey strata up to Layer 6 in Shanghai, i.e. at depth of up to 40 m. In this paper, Layers 7, 9, and 11, which were mostly formed of sandy soils at depth of up to 150 m, were experimentally investigated with respect to physico-mechanical behaviors. The stress–strain behaviors were analyzed by the consolidated drained/undrained (CD/CU) triaxial tests under monotonic loading. One-dimensional (1D) oedometer tests were performed to investigate the consolidation properties of the sandy soils. Specimens were prepared at three different relative densities for each layer. Also, the micro-images and particle size analyzers were used to analyze the shape and size of the sand grains. The influences of grain size, density, and angularity on the stress–strain behaviors and compressibility were also studied. Compared to the other layers, Layer 11 had the smallest mean grain size (D₅₀), highest compressibility, and lowest shear strength. In contrast, Layer 9 had the largest mean grain size, lowest compressibility, and highest shear strength. Layer 7 was of intermediate mean grain size, exhibiting more compressibility and less shear strength than that of Layer 9. Also, the critical state parameters and maximum dilatancy rate of different layers were discussed.     

A new method of predicting the saturation pressure of oil reservoir and its application

Saturation pressure is a vital parameter of oil reservoir which can reflect the oilfield characteristics and determine the oilfield development process, and it is determined by experiments in the laboratory in general. However, there was only one well with saturation pressure test in this target reservoir, and it is necessary to determine whether this parameter is right or not.In this work, we present a new method for quickly determining saturation pressure using machine learning algorithms, including random forest regressor (RF), support vector machine (SVM), decision trees (DT), and artificial neural network (ANN or NN). Using these approaches, saturation pressure was obtained by using the initial solution gas-oil ratio (GOR), temperature, API gravity and other reservoir-fluid data available in the oilfields. Compared with the empirical formula for saturation pressure calculation, the calculated result shows that the accuracy given from machine learning is higher than that from other formulas at home and abroad, and has a good match with the lab test. On the basis of the calculated saturation pressure, it can determine whether the reservoir enters into the stage of dissolved gas drive or not, which also provides the basis for maintaining the reservoir pressure by water injection in advance, rational development decision-making and work over measures.This approach above can provide technical guidance for predicting the saturation pressure in the development of different kinds of reservoirs, including the sandstone reservoirs and carbonate reservoirs.     

Thermal effects in H2O and CO2 assisted direct carbon solid oxide fuel cells

Thermal effects in a H₂O and CO₂ assisted tubular direct carbon solid oxide fuel cell (DC-SOFC) are numerically investigated. Parametric simulations are further conducted to study the effects of operating potential, the distance between carbon and anode, inlet gas temperature, and anode inlet gas flow rate on the thermal behaviors of the fuel cell. It is found that the fuel cell with H₂O as gasification agent performs considerably better than the cell with CO₂ as gasification agent in all cases. It is also found that the temperature field of the fuel cell is highly uneven. The breakdown of the heat sources in the fuel cell shows that the H₂O assisted DC-SOFC has much higher heat generation and consumption than the CO₂ assisted cell. Interestingly, a thermal neutral voltage is observed, at which no heating or cooling of the cell is needed. In addition, the distance between the anode and the carbon layer is required to be as small as possible, which improves the temperature uniformity of the fuel cell. The results of this study demonstrates the importance of thermal effects in DC-SOFCs and form a solid foundation for DC-SOFC thermal management.     

Using fuzzy MCDM technique to find the best location in Qatar for exploiting wind and solar energy to generate hydrogen and electricity

Hydrogen has been a promising energy carrier to meet the world's energy needs as well as reduce pollutant emissions. Although many countries have policies and programs to expand hydrogen production, the potential for hydrogen production in different regions of Qatar has not yet been evaluated. Therefore, this paper, for the first time, evaluates the possibility of an average annual cogeneration of 14 kWh of electricity and 85 kg/day of hydrogen by a home-scale solar-wind system connected to the grid in Qatar. NASA's 20-year average of meteorological data, the electricity tariff and gasoline price in 2018, along with annual real interest rate, were used as inputs to HOMER software. The techno-econo-enviro analysis was done over a one-year period hour by hour. From the results, it was found that the lowest prices of hydrogen and electricity generated, with $ 2.092/kg and $ 11.495/kWh, were related to Grid and PV-Wind-Grid scenarios, respectively. Also, results indicated that Ar-Ruways station and PV-Wind-Grid scenario were the most environmentally suitable options that resulted in a CO₂ emission rate of 1434 kg annually. To select just one station among five areas, a fuzzy method was deployed as a prioritization technique. Its results suggested that Doha Intl Airport site is the most suitable one for constructing solar-wind hybrid energy generation system.     

Study on life and path of fatigue cracks in multiple site damage plates

This paper presents experimental and numerical study of the fatigue crack growth of hollowed pre-notched plates with multiple site damages (MSD). The numerical analyses were performed using finite element method. Experiments were carried out to validate the numerical results. Fatigue tests of aluminum sheets with MSD cracks were conducted to evaluate the effects of some parameters such as the thickness, hole diameter and central distance of the holes. The results show that the distance of the holes has greatest and size of the hole has little effects on the fatigue lives. Nucleation of cracks strongly depends on the thickness, distance and hole size.