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This paper demonstrates the capabilities of the Simulink simulation environment for tuning the parameters of Power system stabilizers (PSS), which play a key role in damping the low-frequency oscillations in the electric power systems. First, the theory and algorithms for optimization of the parameters are examined, focusing on the phase compensation (P-Vr) method, which was selected and implemented in Simulink. The different steps of the tuning algorithm are explained, as well as the formulation of the objective function. The theoretically described steps were practically applied to a single-machine system, as well as to the well-known four-machine system of Kundur. The available solvers were also tested and compared in terms of speed and efficiency.

Developing a low-carbon economy is the only way for countries to achieve sustainable development. Carbon emission reduction policies and low-carbon technology (LCT) innovation play key roles in developing low-carbon economy. Under government reward and punishment regulations, based on the bilateral matching and evolutionary theories, this paper constructs an evolution model consisting of a manufacturer investing LCT and a supplier offering LCT to analyze multi-phase LCT investment strategies. Firstly, the profit optimization model of a green supply chain is constructed from the perspectives of centralized-matching (CM), decentralized-matching (DM), and mismatching (MM), and the spatial information internal evolution law of multi-phase LCT investment is described by the Markov chain. Then, a bilateral matching algorithm is proposed to solve the equilibrium solutions, and the evolution process of the three modes is analyzed by numerical simulation. Finally, based on the product green degree, we analyze the impact of subsidies and taxes on investment-production decisions. Analytical results show that the matching mechanism proposed in this paper can help supply chain firms to obtain stable matching and has a significant effect on the realization of "triple wins" of society, economy, and environment. The investment utility of CM is higher than that of DM and MM. Manufacturers are inclined to adopt LCT, and the investment level tends to be stable over time. Government reward and punishment regulations are helpful to motivate supply chain firms to invest in LCT, and the synergistic effect of subsidies and taxes is better than that of a single policy.

A new approach for the electromagnetic control and propulsion of a current carrying electric arc plasma ring is described. The essence of the approach is to form and manipulate the arc plasma outside rather than inside a magnetic field producing coil so that pulsed plasma thrusts can be produced in a choice of different directions. The interaction of the electric arc, formed in atmospheric pressure air, with such a magnetic field has been investigated. It has been shown that a stable azimuthal plasma ring can be rapidly produced by the simple process of separating two annular contacts. Pulsed plasma propulsion is obtained when the arc plasma and B-field sustaining current is reduced to zero whereby the constraining electromagnetic forces are removed and, as a consequence, the resulting plasma ring expands radially outwards. Several different measurement techniques have been deployed for investigating the behavior of the plasma ring. These include electrical probing, B-field probing and high-speed plus video photography. The results suggest that the plasma control and propulsion is governed by a combination of effects including ablation of the material around which the plasma ring is formed and self-pressurization related to the device geometry, as well as the electromagnetic forces. Preliminary results indicate that through the use of appropriate device geometries, the arc plasma may be propelled in axially opposite directions as well as radially.

Abstract We present a production-theoretical approach to decomposing the change of aggregate CO2 emissions over time using the Shephard input distance functions and the environmental data envelopment analysis (DEA) technology in production theory. Application of the proposed approach requires only some aggregate data and the change of aggregate CO2 emissions can be decomposed into contributions from seven factors. These contributions are obtained through solving a series of DEA models. The key features of the proposed approach are the use of panel data to estimate the production frontier and the inclusion of several production technology related components. Using the proposed approach, we present two application studies on decomposing the CO2 emissions for world regions and OECD countries. A comparison between the proposed approach and other decomposition analysis methods is also presented.

As a financial innovation model to promote sustainable economic development, carbon finance promotes green and inclusive economic development by reshaping the financial system. As a big energy consumer, China has been committed to the green transformation of energy structure, and carbon finance has been regarded as an important tool to support carbon emission reduction. This paper divides carbon finance from three levels, financial macro, environmental governance, and technological development, and selects 17 indexes to measure the development level of carbon finance in China. Time series regression model and the entropy weight method (EWM) are used to analyze the impact of carbon finance on China's energy consumption structure. The empirical results show that carbon finance plays a positive role in promoting China's energy consumption structure, and developing carbon finance is conducive to the use of clean energy and the optimization of energy consumption structure in China; carbon finance can further optimize China's energy consumption structure by investing capital, resources, and technology in industries related to promoting clean energy consumption. Therefore, China should continue to develop carbon finance and promote the establishment of a unified national carbon trading market; at the same time, China should use the CCER trading mechanism to promote the development of renewable energy and enhance the endogenous driving force of energy transformation by promoting technological progress.

Accelerating the development of renewable energy is seen as an effective way for achieving the goals of carbon peak and carbon neutrality. The polices of Renewable Electricity Standard (RES) and Renewable Energy Certificates (REC) play increasing and important roles in developing renewable energy. In this paper, we develop an analytical model to analyze the impacts of the interaction of RES and REC polices on the renewable energy investment levels of an electricity generation firm and the carbon emissions. Our analysis reveals several interesting insights. First, we find that the green tags price under REC policy has a non-monotonic effect on the renewable energy investment, which highly depends on the quota (i.e., the required percentage of renewable electricity consumption on total electricity consumption) under the RES policy. Specifically, when the quota in RES policy is set too high, an increase in the green tags price will increase renewable energy investment; otherwise it will reduce the electricity generation firm's incentive to invest in renewable energy. Second, we show that the green tags price also has a non-monotonic effect on the carbon emissions. Specifically, when the quota in RES policy is set small enough, an increase in the green tags price will decrease the carbon emission. However, when the quota in RES policy is high enough, an increase in the green tags price will increase the carbon emission.

Abstract Global environmental change is driven by food production. Biogas from food waste is a better source of clean energy. Ghana’s energy strategy targets a 10% increase in renewable energy and modern biomass in the national electricity generation mix. Studies on the assessment of electricity generation potential and economic feasibility of biogas to electricity projects in Ghana’s major cities are scarcely available. This study assesses the electricity generation potential of biogas from food waste through anaerobic digestion technology. The municipal solid waste generation potential of Accra and Kumasi was estimated from 2020 to 2039. The potential theoretical methane yield from food waste was calculated using Buswell’s equation. The study analyzed anaerobic digestion projects’ economic feasibility using the total life cycle cost, net present value, investment payback period, levelized cost of energy, and internal rate of return methods. A sensitivity analysis based on two scenarios (optimistic and pessimistic) was performed to analyze the influence of changes in the composition of food waste, per capita waste generation rate, population growth rate, per capita GDP growth rate, discount rate, capacity factor, electricity generation efficiency, waste collection efficiency, and methane production potential on the economic feasibility of the projects. The main findings indicate that the amount of waste generation in Accra during the project life cycle is 899,000 t/y to 3,359,000 t/y, while that of Kumasi is 915,000 t/y to 3,159,000 t/y. The power generation potential of the project in Accra ranges from 80.43 to 300.49 GWh/y, and in Kumasi ranges from 60.63 to 209.31 GWh/y. Economically, the project is feasible in Accra and Kumasi. The net present value of the project in Accra and Kumasi is $217,800,000 and $156,100,000. The sensitivity analysis shows that the project is infeasible in all the cities with a discount rate exceeding 20%. When the discount rate exceeds 20%, the project becomes highly infeasible in Accra compared to Kumasi. This study will offer itself as scientific guidance for investment in biogas to electricity projects in Ghana’s cities.

A p-NiO/n-KNbO3 heterojunction photocatalyst was synthesized via a photodeposition method and for the first time applied in photocatalytic N2 fixation under simulated sunlight.

The thermal performance of a novel solar air collector with metal corrugated packing in the buildings of cold regions is studied in this paper. Mathematical models are developed to investigate the thermal performance of the collector and the results are verified by experiments. The hydraulic analysis is conducted experimentally to study the pressure drops of the air flows in the corrugated packing. Effects of the structural and operating parameters, such as the collector width, height, specific surface area and solar radiation intensity, ambient air temperature, air inlet temperature and velocity are studied to optimize the thermal performance of the collector. Comparisons are conducted among the metal corrugated packing solar air collector, the unglazed transpired solar collector, the glazed transpired solar collector and the packed bed solar collector with iron chips. The results indicate that the metal corrugated packing solar air collector is more appropriate to be used in the rural buildings of cold regions for its advantages of large heat transfer area, high heat transfer coefficient and good economic performance.