Assessing the impact of regulatory reforms on China's electricity generation industry

In the past two decades, China has experienced a series of regulatory reforms in its electricity industry, aimed at improving power production efficiency. The central planning system was broken up and the market-oriented modern enterprise system was established. Furthermore, the former vertically integrated electricity utilities were divested and the generation sector was separated from the transmission and distribution networks. In this paper, we intend to estimate the impact of regulatory reforms on production efficiency of fossil-fired generation plants using the plant-level national survey data collected in 1995 and 2004. Applying the econometric method of Differences-in-Differences, we estimate the effects of these reforms on the demand for inputs of employees, fuel and nonfuel materials. The results show that the net efficiency improvement in labor input associated with the regulatory reforms is roughly 29% and the gains in nonfuel materials are about 35%, while there is no evidence of efficiency gains in fuel input associated with the electricity reforms.Electricity restructuring Production efficiency Differences-in-Differences

Assessing the impact of regulatory reforms on China's electricity generation industry

In the past two decades, China has experienced a series of regulatory reforms in its electricity industry, aimed at improving power production efficiency. The central planning system was broken up and the market-oriented modern enterprise system was established. Furthermore, the former vertically integrated electricity utilities were divested and the generation sector was separated from the transmission and distribution networks. In this paper. we intend to estimate the impact of regulatory reforms on production efficiency of fossil-fired generation plants using the plant-level national survey data collected in 1995 and 2004. Applying the econometric method of Differences-in-Differences, we estimate the effects of these reforms on the demand for inputs of employees, fuel and nonfuel materials. The results show that the net efficiency improvement in labor input associated with the regulatory reforms is roughly 29% and the gains in nonfuel materials are about 35%, while there is no evidence of efficiency gains in fuel input associated with the electricity reforms. (C) 2008 Elsevier Ltd. All rights reserved

Research Status and Prospects of Control Strategies for High Speed On/Off Valves

As the working conditions of host equipment become more complex and severe, performance improvement and increased intelligence of high speed on/off valves (HSV) are inevitable trends in the development of digital hydraulic technology. The characteristics of HSVs can be regulated by control strategies, which determine the comprehensive performance of the system. This paper discusses the development of control strategies for HSVs. First, the results of research in relation to the discrete voltage and pulse control of single HSVs and the coding control of parallel HSVs are summarized. In addition, the advantages, disadvantages and application scope of different control strategies are analyzed and compared. Finally, the development trends are predicted from the performance regulation, intelligent maintenance, intelligent coding and function programmability

On the In-Die Conditions and Process Parameter Settings in Indirect Squeeze Casting

The current study investigated the relationship between the process settings and in-die conditions to understand the transitions between the different filling stages and the final pressure settings in indirect squeeze casting. A pressure sensor was placed in the die cavity to indirectly measure the evolution of pressure over time and monitor the filling process to study the in-die conditions. The pressure–time profile was analysed, and the maximum pressure and acceleration of the pressure were investigated empirically. The main conclusion of this paper is that the use of increasing intensification pressures is positive for the casting soundness. However, it must be stressed that there is a strong effect from the intensification pressure on the acceleration that has a far more reaching influence than the actual speed setting. A direct practical outcome is that a high intensification pressure has a more substantial effect than the second stage fill speed. This translates directly to a possibility of reducing the second stage fill speed to stabilise the fill front. Furthermore, this also pinpoints the need for improvements in hydraulics system designs to decouple the intensification pressure from the filling piston motion control

On the Part Quality, Process Parameters and In-Die Pressures in Indirect Squeeze Casting

Squeeze casting is a process that can produce the highest quality castings. In the current study, the effect of the process settings and the in-die conditions on rejection rates is studied through a full-scale experimental study. Factors affecting the as-cast part quality were investigated in the current study from two different viewpoints. The first part of the study was to investigate the influence of the process settings on the part rejection rate, and the second was to understand the conditions in the die and the effects on the part rejection rate to understand better the reasons and sensitivity of the squeeze casting process

On the In-Die Conditions and Process Parameter Settings in Indirect Squeeze Casting

The current study investigated the relationship between the process settings and in-die conditions to understand the transitions between the different filling stages and the final pressure settings in indirect squeeze casting. A pressure sensor was placed in the die cavity to indirectly measure the evolution of pressure over time and monitor the filling process to study the in-die conditions. The pressure–time profile was analysed, and the maximum pressure and acceleration of the pressure were investigated empirically. The main conclusion of this paper is that the use of increasing intensification pressures is positive for the casting soundness. However, it must be stressed that there is a strong effect from the intensification pressure on the acceleration that has a far more reaching influence than the actual speed setting. A direct practical outcome is that a high intensification pressure has a more substantial effect than the second stage fill speed. This translates directly to a possibility of reducing the second stage fill speed to stabilise the fill front. Furthermore, this also pinpoints the need for improvements in hydraulics system designs to decouple the intensification pressure from the filling piston motion control

First-principles study of hydrogen incorporation into the MAX phase Ti 3 AlC 2

International audienceFirst-principles calculations have been performed to study hydrogen incorporation into the MAX phase Ti3AlC2. It is found that H atoms are thermally favorable to be incorporated into the interstitial sites of Ti-Al layers in stoichiometric Ti3AlC2. Only when C vacancies exist, H atoms can be incorporated into Ti-C layers. In Ti-Al layers, the hexagonal interstitial site (Ihexa) consisting of three Al atoms and two Ti atoms, the tetrahedral interstitial site (Itetr-2) consisting of one Al atom and three Ti atoms, and the octahedral interstitial site (Ioct-3) consisting of three Ti atoms and three Al atoms are all possible sites for H incorporation. Among them, Itetr-2 is the most stable one, followed by Ioct-3, and the last one is Ihexa sites. The linear synchronous transit optimization study shows that the diffusion of H in the Ti-Al layers is feasible which could be helpful for the continuous insertion and the following extraction of H in Ti3AlC2

Enhancing Segregation Behavior of Impurity by Electromagnetic Stirring in the Solidification Process of Al-30Si Alloy

Increasing the removal efficiency of impurities during non-equilibrium solidification of hypereutectic Al-Si alloy remains a great challenge for the upgrading of metallurgical silicon (MG-Si) to solar grade Si (SOG-Si). Hence, a manageable method was provided to enhance the segregation behavior of impurities at the interface front of primary Si/Al-Si melt by introducing a rotating magnetic field (RMF) in the present work. Experimental results showed that electromagnetic stirring can improve the removal efficiency of impurities while achieving the separation of primary Si. The apparent segregation coefficients of the major impurities Fe, Ti, Ca, Cu, B and P were reduced to 7.5 × 10−4, 4.6 × 10−3, 7.9 × 10−3, 3.5 × 10−3, 0.1 and 0.16, respectively, under RMF of 25 mT and cooling rate of 2.5 °C/min. We confirmed that improving the transport driving force of impurities in the growth interface front of primary Si is an effective way to improve the segregation behavior of impurities, which would bring us one step closer to exploiting the economic potential of the Al-Si alloy solidification refining