bluuebunny/crossref_metadata_2025_split huggingface dataset:
A NB-IoT based intelligent combiner box for PV arrays integrated with short-term power prediction using extreme learning machine and similar days
Authors: Zhang Caigui , Chen Zhicong , Wu Lijun , Cheng Shuying , Lin Peijie 
Published: April 2020

Abstract
The grid-connected photovoltaic (PV) power stations are instability and volatility due to meteorological factors. A way to improve this problem is PV power forecasting. This paper proposed an improved short-term PV power prediction model that combines an extreme learning machine (ELM) neural network and similar day method. Firstly, a narrow-band Internet of Things (NB-IoT) intelligent combiner box data monitoring system is designed to collect multivariate meteorological factors and original PV output power datasets in different seasons. Secondly, the corresponding training set is selected according to the season type of the forecast day, and the Euclidean distance (ED) between the training set and the forecasting day is calculated, and the M-day with a small Euclidean distance is selected. Then, the N-day similar day data is divided among the M days as the new training set input, and the P-day optimal similar day data and the multivariate meteorological of the prediction day are divided as test set inputs. Finally, the ELM neural network prediction model is used to predict the output power of the predicted day. The experimental results show that the proposed method has the highest prediction accuracy in contrast to other two prediction models.
Measurement and analysis of the in-cylinder process of a LNG engine under transient operations
Authors: Xia Yan , Liu Jingping , Song Rongfeng , Zhang Shijia , Fan Mingxiang 
Published: April 2020

Abstract
Parameters reflecting the in-cylinder process in a turbocharged, LNG fuelled, spark ignited engine, such as the intake manifold pressure, air/fuel ratio (AFR), fuel mass flow-rate, as well as the dynamic in-cylinder pressure traces, are measured cycle-by-cycle for a series of transient operations via external air injection into the engine intake system. During the transient load step process, the engine experiences not only abrupt change of boost pressure and AFR, but also rapid engine load change. The changes in the in-cylinder combustion process during the transient operations, which were rarely revealed before, are illustrated with the rate of heat release (ROHR) characteristics cycle-by-cycle. The influences on the combustion characteristics under the transient operation conditions, of the operational parameters, such as AFR, air and fuel flow, boost pressure, etc. are examined and discussed. Existence of abnormal combustion such as late combustion, misfiring and severe variation of IMEP, etc. are pointed out. The possible causes of those abnormal combustion phenomena are also analyzed. The in-cylinder process detection method presented in this paper is universal and can be extended to other similar applications.
Research on doubly-fed wind power system based on MATLAB/Simulink software
Authors: Guo Yaqin 
Published: April 2020

Abstract
With wind randomness and burstiness, output power of wind turbine will be fluctuated, and fluctuating power affected the operation of power grid in the grid-connected. Therefore, it is necessary to research wind power system. The structure and principle of Doubly-fed wind power system are introduced in the paper, by analysing the principle, we build simulation model of Doubly-fed wind power system using MATLAB/Simulink software. In order to test the performance of the model, the phase-voltage, phase-current and active power of the system are tested under three status, which are steady-state operation, different wind speed and three-phase short circuit. The experimental results show that Doubly-fed wind power system has strong anti-interference and good safety.
The study for MPPT of photovoltaic system based on terminal sliding mode control method
Authors: Zheng Dandan , Li Jian , Wu Wei , Yu Hui , Du Jiawei , Sun Wenbing , Xiao Shiyi , Shao Zhuxing 
Published: April 2020

Abstract
Aiming at the problem of the Maximum Power Point Tracking (MPPT) of PV system, based on the requirements of improving the tracking speed and reduce the steady-state oscillation, a terminal sliding mode control method is proposed to complete MPPT control in this paper. Mathematical model of the PV module is realized by four parameters with standard condition. Unlike traditional methods, it is proposed that the tracking current and power reference at the maximum power point at arbitrary conditions can be obtained directly from the established model. It is simple and can avoid the tracking error. In this paper, we tracked the outputs of the PV module under different conditions and compared the proposed method with the Incremental Conductance (INC) algorithm, the results show that the proposed control method can enhance the track speed and accuracy, decrease the steady-state oscillation and improve the efficiency of PV system.
Analysis method of the influence of electric bus optimal charging on the renewable energy power consumption
Authors: Tian Xu , Wang Wei , Liu Fei , Liang Guoyong , Zhang Wei , Wang Shibin , Fu Yanan 
Published: April 2020

Abstract
To analyze the influence of the optimal charging of electric buses on the consumption of power generated from renewable energy sources, an optimal charging model with the electricity price revision is proposed. The revision helps to promote consistency between the charging load and renewable energy power. Then the analysis of the influence of electric bus optimal charging on the renewable energy power consumption can be achieved. Based on the revised electricity price, a 0-1 integer linear programming model for the optimal charging of electric buses is established, aiming to derive the lowest charging cost. The method takes into account the demand of buses’ drive range, continuous charging and the number of charging piles.
Mathematical modelling of gasification processes of the biofuel in the conditions of chemical equilibrium
Authors: Pavlenko Anatoliy , Slowak Anna Maria 
Published: April 2020

Abstract
The article presents the results of experimental studies of the process of biomass heat treatment. The method of mathematical modeling of the biomass gasification process is improved on the basis of the thermodynamic model of Gibbs free energy minimization In most countries, their energy strategies involve an increase in the share of renewable energy sources, including using a sufficiently large biomass potential. The solution of the Lagrangian function made it possible to determine the composition of the generator gas and the efficiency of the process. The accuracy of the proposed mathematical is estimated. The obtained results of the work can be used to determine the optimal conditions for gasification in the development of biomass gasification technologies.
Typical fault analysis and preventive measures of 110kV XLPE cable fully prefabricated dry terminal
Authors: Duan Yubing , Zhang Hao , Hu Xiaoli , Liu Rong , Liu Hui , Liu Chuanbin 
Published: April 2020

Abstract
With XLPE cables are widely put into operation in the city underground power system, it is more and more important of the stability of 110kV cable lines. The prefabricated dry terminal due to lack of firmly fixed and other shortcomings, Cable breakdown faults are easy. In recent years, several terminal breakdown prefabricated dry cable typical case in shandong power network, a comprehensive analysis of the breakdown faults reason, combined with the operation experience, put forward the new 110kV cable line prefabricated dry terminal platform installed in the transport line, the new 110kV cable line prefabricated dry terminal comprehensive inspection, strengthen the infrared temperature measurement of charged detection, transformation timely preventive measures. Through the development of 110kV cable line full prefabricated dry terminal breakdown prevention measures, it can effectively reduce the probability of the faults and improve the reliability of high voltage cable line operation.
DC/DC half-bridge SST based on energy router
Authors: Chen Yang , Li Pengfei , Li Zichen , Zhang Yanchi , Xie Da 
Published: April 2020

Abstract
In this paper, a DC/DC half-bridge SST (Solid state transform) based on energy router is proposed. The structure mainly includes high-frequency transformer circuit, half-bridge circuit and control circuit. The DC side is converted to a high frequency AC signal through a half-bridge circuit. Then the high-frequency transformer circuit transmits the AC signal to the secondary side, and the secondary side is connected to the same half-bridge circuit for rectification to make electrical energy output in the form of DC. The whole circuit adopts symmetrical structure, which is beneficial to the bidirectional flow of energy. The simulation results verify the correctness and feasibility of the design scheme.
Simulation and contrast study on flywheel energy storage control strategy for dynamic stabilization of power fluctuation in power grid
Authors: Zhou Feng , Liu Mingliang , Jiang Peng , Xu Mingyu , Hao Wenbo , Wang Bing , Wang Luxin 
Published: April 2020

Abstract
Flywheel Energy Storage System can not only effectively reduce the impact of energy fluctuation on the power grid, but also fully improve the utilization of distributed energy system because of its characteristics of energy storage and rapid charging. In this study, permanent magnet brushless DC motor is selected as flywheel motor for wind power system. The mathematical model of flywheel energy storage system in rectangular coordinate system is established. The double closed-loop simulation model of speed and current of flywheel energy storage system is built by using MATLAB/Simulink. In order to improve the control performance of flywheel energy storage system, three different control strategies, PID control, sliding mode variable structure control and ADRC control, were used to simulate the charging and discharging dynamic process of FESS. Considering the particularity of flywheel energy storage system as a limited energy storage unit, the controller parameters of three traditional control modes are adjusted effectively on the premise of keeping the parameters of the flywheel motor unchanged. The simulation results are compared from rotation rate and torque, and the advantages and disadvantages of three control strategies and the dynamic performance of flywheel energy storage system under different control strategies are analyzed.
Data transmission of cyber physical power system
Authors: Hu Yishuang , Jiang Zhengwei , Sun Yikai , Ding Yi , Xu Chenbo , Jin Xueqi 
Published: April 2020

Abstract
Aiming at monitoring the behaviour of power system to make it work correctly and better, cyber physical power system (CPPS) was introduced. However, due to the high integration of cyber system, the complexity of power system is greatly enhanced, which puts forward higher requirements for the reliable and safe operation of CPPS. Moreover, when the cyber system is under attack, abnormal information flow may lead to abnormal energy flow. Therefore, this paper proposes a data transmission mechanism to analyse the information flow among CPPS. A data transmission optimization model based on the transmission matrix is constructed. The data transmission from the cyber system to the power system is quantified by the model. The practicability of the proposed data transmission mechanism is given by numerous cases.
Robust coordinated capacity allocation for wind generation and energy storage in power systems
Authors: Wang Xiaobin , Fan Sheng , Wang Gang 
Published: April 2020

Abstract
Aiming at locating and sizing of wind generation and energy storage in power system planning stage simultaneously, a bi-level optimization model is constructed. The first stage is mainly used to allocate the capacity of wind farms considering the total cost of establishment, operation and maintenance from both wind generation and energy storage. The second stage is applied for allocating energy storage to address the violations of wind generation. Robust optimization theory and genetic algorithm are used to solve the model. The effectiveness of the proposed model is validated by the Garver’s 6-bus system.
Control strategy of grid-connected inverter droop based on GMPPT method
Authors: Zhang Xuyang , Teng Jun , Zhang Pengqiao , Jia Minglei , Yu Cong , Sun Yifei , Sun Jia , Ma Pengran , Zhou Bowen , Cao Nanjun , Liu Hengyu , Yu Zhiwei 
Published: April 2020

Abstract
The conductance increment method (INC) can be quickly and accurately stabilized at the maximum power point (MPP) but easily falls into the local extreme point (LMPP) in the shadow environment. Considering the particle swarm optimization (PSO) can quickly achieve global optimal search but the number of iterations is too large when local convergence, leading to fluctuation and energy loss. Therefore, a global maximum power point tracking (GMPPT) is proposed, which combined the PSO and INC and improved them. In this paper, the research object is the single-phase two-stage PV grid-connected system. The GMPPT needs a stable DC voltage (Udc) to track accurately and the grid-connected inverter needs a stable Udc in order to ensure the quality of grid power. Therefore, the goal of the inverter control is to achieve the combination of GMPPT and grid-connected control. Based on the characteristics of PV power generation, a PV grid-connected droop control strategy based on GMPPT is proposed, which realizes the stability of Udc and the output of MPP and meets grid-connected requirements. Finally, the simulation model of PV grid-connected system based on Matlab/Simulink software is used to verify the effectiveness of the proposed control strategy.
Water quality assessment using comprehensive water quality index and modified Nemerow index method: A case study of Jinghui Canal, North China
Authors: Zhang Yuting , Hou Kai , Qian Hui 
Published: April 2020

Abstract
Groundwater is an essential part of water resources for human survival in irrigation regions. In this study, water quality of jinghui canal irrigation area were assessed using the comprehensive water quality index method (CWQI), normal Nemerow index assessment method (NNI) and modified Nemerow index assessment method (MNI). 47 groundwater samples were collected from unconfined aquifers through shallow well during November 2009. The results showed that groundwater quality in the area was poor due to the industrial and agricultural activities. Most of the groundwater samples were identified as Grade IV and Grade V by the comprehensive water quality index method. While majority of groundwater samples were assessed as Grade IV by both NNI and MNI. Besides, the water quality assessed by MNI was better than NNI and NNI was better than CWQI, which was caused by parameter value and weight value, so we should not only stick to a certain assessment method, but also need to comprehensively consider the purpose of evaluation.
Gas-water two-phase discharge phenomenon in PEF chamber for water treatment
Authors: Wang Zhiyuan , Zhang Ruobing , Chen Zhihao 
Published: April 2020

Abstract
Pulsed Electric Field treatment is a critical technology in waste water treatment and sterilization. However, the discharge of the treatment chamber that causes the damage of pulse generators is one of the main technical issues of its applications. Bubbles under water are the most vulnerable sections and could cause breakdown since it is too difficult to generate discharge in the bulk of water under microsecond-pulse and relatively low electric field(<70kV/cm). Uniform discharging images of gas bubbles under water are captured. The influence of γ approach on breakdown in short gas gap (under 1cm) with water electrode under atmospheric pressure is confirmed. The influence of conductivity of aqueous solution and the repetitive frequency of voltage pulses is discussed. It can be confirmed that the breakdown phenomenon of the PEF treatment chamber is mainly caused by air bubbles, which are generated by Joule heat process as well as cavitation and then discharge under the metal cathode. This work presents vital references for improving the design of PEF treatment chambers.
Multivariate analysis of phytoplankton community structure in Changli Gold Coast National Nature Reserve of Hebei Province in Spring, 2019
Authors: Guo Xiaqing , Yu Yang , Zhu Haoran , Zhao Xinggui , Liu Xianbin 
Published: April 2020

Abstract
In order to research the characteristics of phytoplankton community structure in Changli Gold Coast National Nature Reserve, China, 14 survey stations were set up in this area in May 2019. The basic characteristics of phytoplankton community composition, cell abundance and community diversity were analyzed, and the Multi-Dimensional Scaling (MDS) was used to divide the structure of phytoplankton community. The results showed that a total of 30 species of phytoplankton were identified in this area, mainly diatoms, and the main ecological types were temperate inshore wide temperature and wide salt species. The average cell abundance of phytoplankton in May was 54.38×104 cells/m3, and the main dominant species were Nitzschia sp., Skeletonema costatum and Noctiluca scientillans. The average value of Shannon-Wiener index was 2.26, The average value of evenness index was 0.75. The average of richness index was 0.73. The phytoplankton divided into 6 zones with significant differences by CLUSTER Analysis (P<0.001).
Analysis of Suaeda heteroptera cover change and its hydrology driving factors in the Liao River Estuary wetlands, China
Authors: Wang Yini , Ji Yongpeng , Sun Zhen , Li Jin , Zhang Mingliang , Wu Guanglu 
Published: April 2020

Abstract

Suaeda heteroptera (S. heteroptera) is the most common indicator plant of solonchak in coastal wetlands of the Liao River Estuary, the influence of meteorology, hydrology environment on vegetation distribution is of growing interest. With the help of satellite remote sensing (RS) technology and geographic information system (GIS), we investigated the spatial-temporal distribution and area change of S. heteroptera in the wetlands of the Liao River Estuary from 1997 to 2016, and the identification of the main driving mechanisms in the S. heteroptera evolution was analyzed in this coastal wetland. The SPSS Statistics 22 software was used to calculate the correlation coefficients between total area of S. heteroptera and each driving factor based on available long-term (1997-2016) and medium-term (2007-2016) data. Correlation analysis results indicated that the change in S. heteroptera coverage had insignificant correlations (correlation coefficients r=−0.241, r=−0.188 and r=−0.269) with annual mean temperature, precipitation, and sunshine duration, respectively. The results also showed that the growth of S. heteroptera was extremely relevant to runoff from the Liao River from April to June (r=0.889) over the last 10 years. This study revealed that some potential factors, such as river discharge may be related to the large-scale degeneration of S. heteroptera in Liao River Estuary wetlands.
Simulation investigation of effect on nanoparticles discharging pattern of a car caused by a following one on a typical city road
Authors: Hao Feilin , Shen Mingwei 
Published: April 2020

Abstract
Vehicle emission is supposed to contribute a great part to the urban air pollution in China, and many relative studies were carried out on a macro base at “city valley” scale. This article, on the “micro” individual scale otherwise, attempts to explore the fine particles’ spreading process after leaving the tailpipe of a typical car equipped with the inner-combustion engine in city main road through 3D CFD simulation. two geometries of typical cars driving in typical city road were built up with detailed structures: one is one car driving on the main city street and the other is two cars, one followed the former established car, all with a driving speed of 40 km/h. Eulerian multiphase model is adopted to describe the dynamics of the multiphase: air, particles in 10nm diameter, and particles in 70nm diameter. The simulation results show that the diffusion process of 70nm particles is mainly governed by gravity, more than 80% of which concentrate within the region behind the car with a volume of 4.0m in length, 3.0m in height, and 2.0m in horizontal width along the centreline of tailpipe, while the 10nm particles exhibit a wider and more random distribution pattern, it spreads throughout the simulation volume with noticeable volume fraction: above, beneath, and behind the driving car, the high volume fraction regions mostly occur within a volume of 12.0m in length, 4.0m in height, and 4.0m in width associated with the tailpipe. The followed car causes a “compressing and lifting” effect, it is found that the high-volume fraction regions of particles are compressed to, in one hand, move around to the bodies of the two cars, and the other hand move towards the sides of the road. The particles in 70nm diameter are less affected by the followed car than that 10nm, especially the lifting effect of high-volume fraction regions of 10nm particles. This suggests some nonconventional management measures should be taken to control the urban air pollution of vehicles.
Research progress on migration and transformation model of heavy metal pollutants
Authors: Liu Chuan , Ma Xiaoye , Huang Xu , Cai Mingxuan , Hei Liang 
Published: April 2020

Abstract
With the continuous development of the economy, the pollution of heavy metals to the environment is becoming more and more serious. It is more and more urgent to study the migration and transformation of heavy metals. This paper reviews the classification of heavy metal migration and transformation models, which can be divided into: chemical thermodynamic model, chemical reaction kinetics model, migration and transformation kinetic model (overall model, phase separation model, empirical model), and introduces the applications of the model in different aspects.
Water quality simulation of sewer plant discharge considering long-term and short-term conditions
Authors: Wang Junmin , Fu Lei , You Aiju 
Published: April 2020

Abstract
The development of economy and society in China leads to a huge amount of wastewater discharge, which becomes a serious problem in most of Chinese cities. Therefore, the construction of sewer plant is more popular than before in lots of these cities. The wastewater discharge from the plant is then considered as a point source in most of the important rivers and channels. In this study, a typical wastewater treatment plant is introduced, a monitoring experiment is designed and executed to observe current river status. Additionally, a two-dimensional model is established to predict the water quality downstream of the plant. It is confirmed that the water quality will not significantly deteriorate, however, systematic control of wastewater discharge and protect of current river environment is still encouraged.
Study on harmless and resource utilization of spent cathode carbon washing process
Authors: Zhi Pengkuo , Ou Yujing , Li Chunlei , Wang Yiru , Zhao Dan 
Published: April 2020

Abstract
Spent cathode carbon is the main hazardous waste in the electrolytic aluminum industry, which seriously pollutes the environment. In this paper, the spent cathode carbon is treated by the water washing process to change it from hazardous waste to solid waste, so that the environment is protected and NaF is also utilized. The optimum conditions were determined by experiment: t=50 min, T=80°C, L/S = 20:1. The raw materials and the washed products were characterized by elemental analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM).