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In China, the national target for energy intensity reduction, when integrated with target disaggregation and information feedback systems, constitutes a numerical management system, which is a hallmark of modern governance. This paper points out the technical weaknesses of China's current numerical management system. In the process of target disaggregation, the national target cannot be fully disaggregated to local governments, sectors and enterprises without omissions. At the same time, governments at lower levels face pressure for reducing energy intensity that exceeds their respective jurisdictions. In the process of information feedback, information failure is inevitable due to statistical inaccuracy. Furthermore, the monitoring system is unable to correct all errors, and data verification plays a limited role in the examination system. To address these problems, we recommend that the government: use total energy consumption as the primary indicator of energy management; reform the accounting and reporting of energy statistics toward greater consistency, timeliness and transparency; clearly define the responsibility of the higher levels of government.

In this paper, the moving particle semi-implicit method is applied to simulate flashing jets. Flashing jets are assumed as issuing from a short nozzle with high depressurization, which is corresponding to the actual scenarios for the above severe accidents in nuclear reactors

Abstract Examining household carbon emissions through a supply chain perspective reveals the climate impact of consumption behaviors and variations across societal structures and features. Despite the evident and expanding environmental inequality, strategies for its mitigation and prioritization remain debated. This study investigates the origins of carbon emission inequalities from household consumption, using Japan as a case study, a society characterized by aging demographics and comparatively equal income redistribution. By quantitatively analyzing household carbon footprints, we observe a U-shaped distribution in emissions as income levels increase. Notably, the carbon footprint sizes are strikingly similar between the lowest and highest income groups, yet inequalities emerge in education and investments in future generations. Integrating these findings, this study further conducts a scenario analysis to project shifts in future low-carbon lifestyles, indicating that middle-income groups are more prone to achieving personal-level decarbonization. This projection is vital in understanding how to effectively address carbon footprint inequalities, especially considering the entrenched preferences in wealthier demographics for investing in future generations.

Heat is the largest energy end-use in the world, accounting for about 50% of global final energy consumption. In 2019, the International Energy Agency pointed out that the development of renewable energy heating has become a key way for the global response to climate change, environmental pollution control, energy transformation and sustainable development. Biomass energy as a priority for the development of renewable heat sources has been valued by countries around the world. Developed earlier in the EU countries, their biomass heating technology is more mature, and their policy system is more comprehensive. Accounting for 86% of the total renewable thermal energy consumption, biothermal energy in these countries has achieved significant effect and become an important driving force for the decarbonization of the heating industry. This practice has a very high demonstration effect globally. This paper constructs a comprehensive zoning theoretical framework of biomass energy heating and utilization in the EU countries. Based on the calculation of the supply and demand potential of biomass energy heating system, the FCM method is used to quantify the status of biomass resource utilization in 28 EU countries. The results show that there are significant differences in the utilization of biomass energy heating in the EU countries, which can be divided into five categories of comprehensive zones, which are the key development category (Finland, Sweden, Denmark, Estonia, Lithuania and Latvia), resource priority category (Austria, Croatia, Bulgaria, Romania, and Slovenia), policy-oriented category (Germany, Italy, Portugal, and Cyprus), good-potential category (Czech Republic, Hungary, Greece, Spain, Poland, France, and Slovakia)and under-developed category (UK, Netherlands, Belgium, Ireland, Luxembourg and Malta). At the same time, this paper discusses the characteristics and causes of biomass heating utilization of different types of EU countries, and summarizes the mature heating systems and rich experience in the EU countries with China’s current heating situation and its future challenges concerning renewable energy development. Finally, this study provides some implications for China’s clean heating development, energy efficient use, energy supply security and energy structure upgrade.

Decentralised nonlinear control of generator excitation and turbine governor based on the feedback linearisation approach is proposed. To make the proposed nonlinear control possess adaptive ability under the changing conditions of power systems, the extended observation decoupled state space in which mechanical power is considered as variable is proposed, and the local stability of the postfault equilibrium point is established rigorously from a mathematical viewpoint. Nonlinear simulations are performed in a three-machine power system and in the ten-machine West Japan power system, and the effectiveness of the proposed nonlinear control and the convergence characteristics of the postfault equilibrium point observer are validated.

The recognition of the creepage discharge development process of oil–paper insulation under AC–DC combined voltage is the basis for fault monitoring and diagnosis of converter transformers; however, only a few related studies are available. In this study, the AC–DC combined voltage with a ratio of 1:1 was used to develop a recognition method for the creepage discharge development process of an oil–paper insulation under a cylinder–plate electrode structure. First, the pulse current method was used to collect the discharge signals in the creepage discharge development process. Then, 24 characteristic parameters were extracted from four types of creepage discharge characteristic spectra after dimensionality reduction. Finally, based on the online sequential extreme learning machine (OS-ELM) algorithm, these characteristic parameters were used to recognize the development stage of the creepage discharge of the oil–paper insulation. The results showed that when the size of the sample training set used in the OS-ELM algorithm is close to the number of hidden layer neurons, a high recognition accuracy can be obtained, and the type of activation function has little influence on the recognition accuracy. Four stages of the creepage discharge development process were recognized using the OS-ELM algorithm; the trend was the same as that of the characteristic parameters of the entire creepage discharge development process. The recognition accuracy was 91.4%. The algorithm has a high computing speed and high accuracy and can train data in batches. Therefore, it can be widely used in the field of online monitoring and evaluation of electrical equipment status.

AbstractIn this paper, a new control approach is proposed for the transient stabilization of a single‐machine infinite‐bus power system. The proposed method is based on linear parameter varying (LPV) modeling of the nonlinear power system and the design of a gain‐scheduled output feedback controller. It is well‐known that when large disturbances or a fault occurs, the nonlinearity inherent in power systems can no longer be ignored. The proposed method can handle the nonlinear model directly. First, we show that the nonlinear model can be transformed equivalently into an LPV system with the rotor angle as the scheduling parameter. Then, a gain‐scheduled output feedback controller is designed based on robust pole placement and L2‐gain minimization. Simulation results verify that the proposed method is better than well‐tuned conventional power system stabilizer (PSS) control. Copyright © 2010 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Abstract In recent years, variable refrigerant flow (VRF) systems have gained popularity in commercial and residential buildings. It is extremely significant to obtain the real performance of VRF systems in order to improve design. However, the measurement of the field cooling or heating capacity of air-cooled VRF systems has not yet been thoroughly addressed. In this paper, a novel field measurement method for the capacity of VRF systems is proposed based on the energy conservation of a compressor set. The compressor set consists of the actual compressor, oil separator, and capillary with the corresponding pipelines. The validation results indicate that the compressor set energy conservation method yields 15% accuracy for cooling capacity and 13% accuracy for heating capacity. Furthermore, the novel measurement method was applied to a VRF system in an office building over four weeks during the heating season. The field test results demonstrate that the average part-load ratio of the VRF system was 0.33, which revealed that the sizing of the VRF system was relatively excessive.

As reliable and stable operations have become critical issues in deregulated electric power markets and systems, a growing number of individuals need advanced and timely information that will allow them to understand the major trends and technologies that are moving this dynamic segment of the electric power industry and market ahead. Under such circumstances, Power System Engineering Committee in The Institute of Electrical Engineering of Japan (Chairman: Ryuichi Yokoyama) and The Consortium for Power Technology of Japan (President: Takeshi Taneichi, Secretariat: Waseda University) have organized a special symposium on “New Issues on Electric Power Markets and System Operations in Asian Countries" on May 28th, 2007, at Uchisaiwaicho Hall in Tokyo. The purposes of the symposium were to address and discuss current situations and new issues related to reliable and stable operations of power markets and systems in the competitive environment in Asian countries. This article is a summary of presentations by four prominent speakers in the special symposium.