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Impact loads in large iron and steel enterprise bring the power system reactive power impact, which makes the fluctuation of the system voltage, power factor and other parameters are out of the limitation of the national standard. Substation bus reactive load forecasting in large iron and steel enterprise can be introduced to determine reactive power optimization strategy and the switching of capacitors. In this paper, a combination forecasting model of quadratic self-adaptive exponential smoothing (QSES) model and converse exponential (CE) model has been proposed for substation bus reactive load forecasting. The numerical results in Jinan iron and steel Group show the application of this model is encouraging. Introduction

Background: The resonant coil design is taken as the core technology in the magnetic coupling resonant wireless power transmission system, which achieves energy transmission by the coupling of the resonant coil. This paper studies the effect of the resonant coil on energy transmission and the efficiency of the system. Combining a two-coil with a three-coil system, the optimum design method for the resonant coil is given to propose a novel coil structure. Methods: First, the co-simulation methods of Pspice and Maxwell are used. When the coupling coefficient of the resonant coil is different, the relationship between system transmission efficiency, output power, and frequency is analyzed. When the self-inductance of the resonant coil is different, the relationship between the performance and frequency of the system transmission is analyzed. Then, two-coil and three-coil structure models are built, and the parameters of the magnetic field of the coils are calculated and analyzed using the finite element method. In the end, a dual E-type simulation circuit model is used to optimize the design of the novel resonance coil. Results: The co-simulation results show that the coupling coefficients of the two-coil, three-coil, and novel coil systems are 0.017, 0.17 and 0.0126, respectively. The power loss of the novel coil is 16.4 mW. Conclusions: There is an obvious improvement in the three-coil system, which shows that the magnetic leakage of the field and the energy coupling are relatively small. The new structure coil has better performance, and the load loss is lower; it can improve the system output power and transmission efficiency.

It is very important to unseal the closed coal mine fire zone safely. Although the fire source disappears in the closed fire zone, it is uncertain whether there are still have high-temperature ignition points, and there is a risk of fire or even explosion again after unsealing. To ensure that the closed fire zone can be unsealed successfully at one time, the study puts forward the method of oxygen augmentation observation to understand the combustion state of the closed fire zone in underground coal mine from the perspective of gas analysis technology. When the mine fire is detected to be extinguished, the method is to inject 8–12% oxygen into the fire area, and the fire area shall be monitored for 2 weeks to determine whether the fire area is completely extinguished. The accuracy and practicality of the method of oxygen augmentation observation are verified by comparing and analyzing the difference results generated by two oxygen augmentation observations in closed zone of Yuwu Coal Mine. In this paper, the use conditions of unsealing in fire zone, detailed methods and steps in the whole process of unsealing and emergency rescue plan are given. The research results can provide valuable reference for one-time safe unsealing of fire zone during the process of disaster relief.

The successful electricity grid integration of solar energy into day-ahead markets requires at least hourly resolved 48 h forecasts. Technologies as photovoltaics and non-concentrating solar thermal technologies make use of global horizontal irradiance (GHI) forecasts, while all concentrating technologies both from the photovoltaic and the thermal sector require direct normal irradiances (DNI). The European Centre for Medium-Range Weather Forecasts (ECMWF) has recently changed towards providing direct as well as global irradiances. Additionally, the MACC (Monitoring Atmospheric Composition & Climate) near-real time services provide daily analysis and forecasts of aerosol properties in preparation of the upcoming European Copernicus programme. The operational ECMWF/IFS (Integrated Forecast System) forecast system will in the medium term profit from the Copernicus service aerosol forecasts. Therefore, within the MACC‑II project specific experiment runs were performed allowing for the assessment of the performance gain of these potential future capabilities. Also the potential impact of providing forecasts with hourly output resolution compared to three-hourly resolved forecasts is investigated. The inclusion of the new aerosol climatology in October 2003 improved both the GHI and DNI forecasts remarkably, while the change towards a new radiation scheme in 2007 only had minor and partly even unfavourable impacts on the performance indicators. For GHI, larger RMSE (root mean square error) values are found for broken/overcast conditions than for scattered cloud fields. For DNI, the findings are opposite with larger RMSE values for scattered clouds compared to overcast/broken cloud situations. The introduction of direct irradiances as an output parameter in the operational IFS version has not resulted in a general performance improvement with respect to biases and RMSE compared to the widely used Skartveit et al. (1998) global to direct irradiance conversion scheme. Cloudy situations and especially thin ice cloud cases are forecasted much better with respect to biases and RMSE, but large biases are introduced in clear sky cases. When applying the MACC aerosol scheme to include aerosol direct effects, an improvement especially in DNI biases is found for cloud free cases as expected. However, a performance decrease is found for water cloud cases. It is assumed that this is caused by the lack of an explicit modelling of cloud-aerosol interactions, while other meteorological forcings for cloud processes like the temperature field are modified by the aerosols.

Abstract Adding high thermal conductive fillers to base materials has been recognized as an efficient way to increase the thermal conductivity of composites materials. The heat conductive path is formed by filler contacts, this is a key point. In this paper, the effects of filler contacts are investigated based on generalized model and isolated model. The results indicate that the thermal conductivity is always linearly increased with the sphere filler contents. However, for cube filler, when the volume content exceeds 10%, the growth of thermal conductivity is accelerated along with filler contents. The 10% filler content is the inflection point and percolation threshold for cube filler. It is much lower than previously reported. The effect of filler contacts is very small for sphere fillers. Meanwhile, the deviation of thermal conductivity between two-dimensional and three-dimensional model is also very small for sphere filler. The cube fillers have substantial effects on the consequently thermal conductivity than sphere fillers. A series of new three-dimensional generalized model are proposed by numerical method. The filler contacts are considered in this model, the deviation with the experiment tested is in an acceptable range at wide filler contents.

Abstract In this paper, a novel ejector-based multi-evaporator refrigeration system using R134a is proposed to meet different working modes of refrigerated trucks running in tropical regions. The Computational Fluid Dynamics (CFD) simulation is implemented to research the performance of ejectors utilized in both air conditioning - refrigerating mode and air conditioning - freezing mode. Consequently, crucial ejector geometrical parameters such as area ratio (AR), nozzle exit position (NXP), lengths of primary nozzle and diffuser are optimized for each mode. Moreover, a novel approach by taking the deviation of the entrainment ratio or secondary mass flow rate over the deviation of the geometrical parameter into account to evaluate the ejector performance sensitivity to each geometrical parameter is first time presented to the best of the authors’ knowledge. The results show that: 1) Area ratio, NXP, lengths of primary nozzle and diffuser of the ejector in the air conditioning - freezing mode are almost twice as those in the air conditioning - refrigerating mode; 2) The performance of both ejectors is primarily influenced by area ratio and NXP; 3) The proposed sensitivity indicator can better evaluate the sensitivity of the ejector performance to geometrical parameters.

This paper built a model of tractive power supply system, analysed the influence on signal cables due to tractive power supply system through the software ATP-EMTP and found out influencing factors of the induced voltage in signal cable core of railway system. Simulation shows that: Structure and size of signal cable, earthing methods and earth resistance of the signal cable sheath are three of the most important factors. There are several ways to reduce the induced voltage in signal cable core, such as reduce the earth resistance of cable sheath and increase the number of earthing contacts of cable sheath.

After entering the 1990s, a new metal oxide semiconductor device-- insulated gate bipolar transistor (IGBT) was first widely used in the industrial driving device. The voltage source converter using IGBT has the ability to turn off current and it can also carry out passive inversion by using pulse width modulation (PWM) technology, which solves the problem of DC transmission to load points without AC supply. Because of strong function and small volume of this converter, it can reduce filtering devices in converter stations, omit converter transformers and simplify the structure of converter station, it is called HVDC light. This paper emphasizes the control technology of HVDC Light system based on VSC core research and designs the experimental system of HVDC Light, including overall design, parameter configuration of main circuit and software and hardware implementation schemes, etc; among these, converter is simulated by IGBT intelligent power module (IPM) and the control algorithm of the system is realized by DSP TMS320F2812A.

A cost efficient synergistic strategy combining mild alkaline pretreatment (0.5-5% NaOH at 70 °C for 60 min) and bovine serum albumin (BSA) blocking of lignin was evaluated for effective conversion of poplar. The highest glucose yield of 69.2% was obtained for 5% alkaline pretreated sample, which was 4.4 times that of untreated sample. The enhanced enzymatic hydrolysis was attributed to significant hemicelluloses removal with limited delignification. Delignification mainly occurred in secondary wall, leading to more open cell wall structure, thus facilitating better transport of enzyme. Hemicelluloses removal helped split adjacent microfibrils, thus increased the specific sites for cellulase binding. After BSA addition in enzymatic hydrolysis, cellulose conversion further improved to 78.4% with 33% reduction of cellulase dosage due to decreased non-specific adsorption of cellulase on residual lignin. The utilization of synergistic alkaline pretreatment - BSA strategy may improve the overall economics of biomass conversion and successful commercial implementation of biorefineries.