bluuebunny/crossref_metadata_2025_split huggingface dataset:
AGC unit capacity planning model considering auxiliary service market under the background of China’s new electricity reform
Authors: Huang Hua , Gu Jiu , Xie Da 
Published: March 2021

Abstract
With the advancement of a new round of power system reform and the continuous access to renewable energy, the auxiliary service market has received extensive attention as an important service to ensure the safe and reliable operation of the power grid. However, it is difficult for the automatic generation control (AGC) units in the system to meet real-time fastness requirements of the power market. Based on the premise that “market electricity” and “planned electricity” coexist under the background of new electricity reform, this paper focuses on the upgrade and reconstruction of AGC units in “planned electricity”. With capacity matching and speed matching as the planning objectives, the optimization and reconstruction algorithm and model of the AGC units are established. Taking capacity matching and speed matching as research targets, the optimization and reconstruction algorithm and model of the AGC units are established. Finally, the effectiveness of the model and the specific scheme of the AGC unit optimization and reconstruction are established through simulation.
Dynamic reactive power optimization of distribution network based on variable step size beetle antennae search algorithm
Authors: Xie Yejun , Liu Zhendong , Pan Yongchao , Liu Lijuan , Du Ke , Yang Zhilong 
Published: March 2021

Abstract
To solve the dynamic reactive power optimization problem in the distribution network, a novel optimization algorithm (variable step size beetle antennae search algorithm, VBAS) is introduced. Meanwhile, from the economic point of view, the minimum network loss and capacitor switching cost are taken as the objective functions, and the dynamic reactive power optimization model is established. In contrast with the majority of existing traditional algorithms that are intricate in process, the conducted algorithm is of less calculate and easier achieved. Besides, the variable step size strategy is introduced to improve optimization accuracy. The effectiveness of this algorithm is verified by simulation analysis on the IEEE 33- bus system, and the results show that VBAS obtains the optimum operation point and outperforms traditional algorithms significantly.
Location planning of smart charging station based on fuzzy TOPSIS method
Authors: Zhao Xuliang , Xue Jiguang , Zhang Xiaoqi , Qin Yuewei , Zhang Xiaoyi , Yu Kun 
Published: March 2021

Abstract
With the increasing demand of electric vehicle charging, it is necessary to plan the location of electric vehicle charging station scientifically and reasonably. By considering the intelligent characteristics of unattended smart charging station, this paper studies the location problem of charging station under the influence of multiple factors, and the evaluation index system of smart charging station location is established. In the light of experts’ evaluation and a lot of experience, the fuzzy number is adopted to express the evaluation value and corresponding weight of indexes. The technique for order preference by similarity to an ideal solution (TOPSIS) method of multi-criteria decision-making (MCDM) is employed to sort the schemes and select the best one. Finally, the rationality and feasibility of the proposed method are verified by simulation results, and the influence of index weight on scheme selection is analyzed.
Combustion comparison analysis on two typical Shenhua chars
Authors: Xiang Baixiang , Huang Jun , Tan Houzhang , Li Yan , Han Binqiao 
Published: March 2021

Abstract
Shenhun and Shitan coal are two types of typical Shenhua coals in Shenhua Group. To compare the ignition and burn out characters of this two coals, the pyrolysis process was adopted and Shenhun, Shitan two chars were acquired. The thermogravimetric method(TGA) was used to evaluate two chars combustion characters. Results show that the combustibility of Shenhun char samples are better than that of Shitan char samples. Both the two types of chars DTG peak temperature are approximate 600-650 °C, indicating an easier ignition tendency. The increase of pyrolysis temperature is adverse to the coke combustion. The DTG peak temperature in 700 °C pyrolysis temperature condition is 50 °C larger than that in 900 °C. In addition, the larger particle size is not beneficial to burn out. From the results in this paper, the particle size below 125 μm is recommended.
Nucleation and recombination dependent desorption performance of Mg-based hydrides
Authors: Xie Lishuai , Wu Tong 
Published: March 2021

Abstract
High desorption temperature and sluggish desorption kinetics hinder the large-scale application of Mg-based hydrogen storage materials. Fundamental understanding of the dehydrogenation process and underlying mechanism is crucial for further modifying the desorption performance. Aiming at elucidating the dehydrogenation process of Mg-based hydrides, partially desorbed pure MgH2 and MgH2-Mg2NiH4-CeH2.73 composite have been prepared to investigate the effects of metal phase nucleation on overall desorption performance. It is found that metal Mg is formed on the surface of partially desorbed MgH2 and MgH2-Mg2NiH4-CeH2.73. Correspondingly, the desorption temperature of partially desorbed samples is significantly decreased, indicating an important role nucleation plays in desorption process. With minor Ni addition, the desorption temperature and kinetics of MgH2-Mg2NiH4-CeH2.73 are significantly improved. Promoting hydrogen recombination is another essential aspect to modify the desorption properties of Mg hydrides.
Steady combustion test and numerical simulation analysis of a single direct-flow pulverized coal burner at low load
Authors: Wang Jingjie , Xia Liangwei , Xu Yanhui , Song Xin , Yan Yanfei , Han Shengli , Yu Qiang , Wei Guohua , Huang Ying , Wang Minghao , Shen Tao , Zhu Lingkun , Shu Zhenyang 
Published: March 2021

Abstract
In this paper, the low load steady combustion test of a single burner was carried out on the 30MW thermal test bench of the State Key Laboratory of efficient and clean coal-fired power plant boiler. Combined with numerical simulation, the lower limit of the minimum stable combustion load of the burner was tried to find out, which provided the basic test data for the furnace combustion stability during the deep peak load regulation of the boiler. The experimental and numerical simulation results show that under 40% rated load, the outlet flame is stable and bright, and the negative pressure in the furnace is stable, which can realize the stable combustion of a single burner.
The modal and harmonic response analysis of final superheater based on workbench
Authors: Wan Yu 
Published: March 2021

Abstract
In order to avoid pipe failures affecting the operation of thermal power plants, the modal and harmonic response analysis method were carried out through the finite element software ANSYS Workbench to solve the long-term vibration of the final superheater at high temperature. Modal analysis can predict the natural frequencies of each stage of the structure and provide the frequency range for the harmonic response analysis. Then the response curve of stress to the frequency under the forced vibration was obtained on the base of harmonic response analysis, and observed the stress corresponding to the peak frequency. Furthermore, the fatigue life of the system was analyzed by the fatigue tool module in ANSYS Workbench. The results show that the fatigue safety factor of the final superheater pipe is greater than the allowed safety factor, and the fatigue life could meet the requirements for safe operation. The research results have certain reference value for further research on vibration fatigue of superheater pipelines.
Hydraulics analysis of the U-tubing effect in a riserless drilling system
Authors: Wang Echuan 
Published: March 2021

Abstract
As a newly developed marine drilling technology, riserless drilling (RD) shows obvious advantages for use in deep-water and ultra-deepwater petroleum resources exploitation. However, the available published hydraulic analysis models for RD are rare or imperfect, especially regarding the lack of accounting for the out-of-hole time. To analyse the actual flow characteristics of drilling mud in an RD system after the surface mud pumping is complete, this paper presents a new hydraulic simulation model of the U-tubing effect. The specific calculation methods of pressure loss in the drilling string and the wellbore annulus at different flow regimes (turbulent flow, transition flow, and laminar flow) are provided based on the Herschel-Bulkley (HB) rheological model. A case study shows that a critical volumetric flow rate (CVFR) exists for a specific RD system to just cause the standpipe pressure to become zero. Only when the initial pump circulation rate is greater than the CVFR can it ensure the normal operation of the RD. Otherwise, the fluid mud level inside the drilling string will drop, resulting in the u-tubing effect. In the first few seconds after the surface pump is shut down, the wellbore transient flow rate is influenced strongly by the initial circulation rate. When the initial flow rate is less than the CVFR, the transient flow rate is accelerated during the first few seconds, which is not the expected behaviour. The influence of the drilling string size, fluid density and rheological parameters of the drilling fluid on the transient flow rate and the Bottom Hole Pressure (BHP) are also considered. The results proved that the smaller values of the rheological parameters are beneficial for reducing the fluctuation of the BHP during the U-tubing process.
The transfer law of exergy in the lines (pipes) and exergy loss analysis
Authors: Xie Pingping , Mao Tian , Xuan Peizheng , Lu Siyu 
Published: March 2021

Abstract
In order to explore the transfer law of exergy in the lines (pipes), based on the generalized expression equation of exergy and the generalized exergy transfers and conversion equation, the transfer law of exergy in the lines (pipes) is derived, and then the exergy loss of three typical energies are analyzed based on the exergy loss model, which are electric exergy loss, pressure exergy loss and heat exergy loss. This paper reveals the change mechanism of exergy transfer process, which can provide more comprehensive guidance for energy saving.
The structural characteristics and electrical of MoS2 and MoS2/graphene: a first-principles study
Authors: Xu Ke , Liao Ningbo 
Published: March 2021

Abstract
MoS2/graphene, as a promising composite candidate of lithium anode, is widely used because of high capacity and high capability of rate. The hetero interface of MoS2/graphene plays a critical role on its electrochemical performance. In this paper, first principles investigations are conducted to study the details of the DOS, band structure, electron density of MoS2 / graphene hetero junction by first principles calculations, which prove that this system is promising to be used in lithium batteries, gas sensors and other domains, for example, like super capacitors and catalysis.
Numerical study on the impact of interface contact resistance on the performance of a PEMFC with serpentine flow field
Authors: Chen Shuyu , Feng Sheng , Lu Wenbo , Chen Qi 
Published: March 2021

Abstract
The performance of a proton exchange membrane fuel cell (PEMFC) strongly relies on the flow-field design. In this study, a three-dimensional, multiphase, and non-isothermal PEMFC model with single serpentine flow field has been developed to investigate the effect of interface contact resistance (ICR) between the bipolar plate (BP) and gas diffusion layer (GDL) on the flow field dimension. In the cases of 25 different combinations of channel and rib width, polarization curves and power density curves of the PEMFC without ICR and with ICR of 7.418 mΩ.cm2 as well as 21 mΩ.2 are investigated. The results show that ICR has little effect on channel pressure drop but on liquid water accumulation. The value of ICR affects both the ohmic loss stage and concentration loss stage of the polarization curves. The power density of the PEMFC without ICR at the operating voltage 0.5V decreases as the rib width increases, while that with ICR increases as the rib width increases. Furthermore, the influence of invalid active area in BPs caused by flow field configuration on the cell performance should not be neglected when the ICR value is lower than 10 mΩ.2.
The effect of thermal hysteresis on the performance of a regenerative Ericsson refrigeration cycle with MnFe-based composite material
Authors: Li Yan , Lin Guoxing , Chen Jincan 
Published: March 2021

Abstract
MnFe-based magnetocaloric materials exist a giant magnetocaloric effect so that they can be used as the working substance for room-temperature magnetic refrigeration. But there are two key problems to be solved before employing them as the working substance: one is that for single MnFe-based material, its giant magnetocaloric effect only arise in a small temperature range and the other is that these materials exist generally thermal hysteresis. For these reasons, a novel composite material based on MnFe-based materials is designed optimally, and a regenerative Ericsson refrigeration cycle using the composite material as the working substance is established. Furthermore, the performance of the refrigeration cycle with the composite is analyzed and evaluated. The influences of thermal hysteresis on main thermodynamic parameters of the refrigeration cycle are revealed by numerical calculation. The research results can provide some significant guidances for the parametric design and performance improvement of room-temperature magnetic refrigerators.
The effect of propionic acid accumulation on methane production in dry mesophilic anaerobic fermentation
Authors: Li Hongli , Wang Yan 
Published: March 2021

Abstract
The dry anaerobic digestion performances were investigated at the temperature of 35±1°Cwith addition of propionic acid at different concentrations in five lab-scale reactors (R1-R5) to investigate the effect of propionic acid accumulation on methane production in dry mesophilic anaerobic digestion. And the volatile fatty acids, biogas and microbial community were detected. The active of microbial community and the methane generation would be inhibited when the propionic acid exceeded 30 gL1, which affected not only syntrophic propionate-oxidizing bacteria but also acetate-utilizing methanogens. Eubacteria decreased sharply accompany with the higher concentration of propionic in R4 and R5. The relative abundance of acetoclastic methanogens was directly correlated with volatile solids removals and methane generation in dry anaerobic reactors. Otherwise, the quantity of syntrophic propionate-oxidizing bacteria was positively linear correlated with propionic acid when the concentration was below 30 gL1. The methanogenic bacteria activity in R3 was the best with the methane yield of 27.01 mLCH4 g-1 VS d-1. The results suggested that appropriate propionate could enhance methane production in the dry anaerobic fermentation.
The parametric study of a novel methanol steam reforming system combining Pd membrane purification and purification retentate combustion
Authors: Zhou Yaodong , Wang Lintao , Deng Bicai , Li Qiyu , Lin Zhimin 
Published: March 2021

Abstract
A hydrogen production process combining methanol steam reforming, Pd membrane purification and purification retentate combustion is proposed and simulated by Aspen plus. The influence of key components’ performance like the methanol conversion rate and hydrogen recovery rate on the methanol consumption is calculated and analyzed. Simulation results show that the overall methanol consumption only reduces by 0.8% when the methanol conversion rate or hydrogen recovery rate increases by 5 percent point. The main benefit is the CO2 emission reduction.
The effect of ion exchange membranes on the bipolar membrane electrodialysis of ammonium chloride wastewater
Authors: Li Ya , Li Wei , Shi Shaoyuan , Wu Xinmin 
Published: March 2021

Abstract
The different bipolar membranes and their configurations with monopolar ion exchange membranes from different manufacturers such as FAB-FBM-FKB, AHA-(BP-1E)- CMB, and JAM-(BMP-1)-JCM are used in the bipolar membrane electrodialysis (BMED) of simulated NH4Cl wastewater to examine the effect of membrane properties on the generation of HCl and NH3∙H2O. The results indicated that the configuration of AHA-(BP-1E)-CMB presented the promising performance among all the ion exchange membranes according to the generated acid and base concentration. And the configuration of FAB-FBM-FKB presented the expected performance on the membrane stack voltage, energy consumption, current efficiency of the BMED system. The stability of different ion exchange membranes in strong acid and base solution were investigated further by the analyses of SEM, contact angle and membrane resistance. It was found that the membranes AHA and FKB had better chemical stability than other membranes.
Effects of temperature on electrochemical impedance spectroscopy of the LiFePO4 battery
Authors: Wu Xijin , He Zhenyu , Wang Tianqi , Li Xin , Yang Dongmei , Wang Qingshan , Li Yan 
Published: March 2021

AbstractChange in temperature affects cycle life and performance of the LiFePO4battery. Thus, different temperature (-20°C∼45°C) performance of the LiFePO4battery was investigated by electrochemical impedance spectroscopy (EIS). The prismatic 40 Ah batteries testing was utilized to show the effect of increasing temperature on ohmic impedance (RΩ) and charge transfer internal resistance (Rct), and evaluate electrical performance consistency of a batch of batteries The results showed that the effect of increasing temperature on RΩ was very slight and on Rctwas more obvious. The change was believed to result from ion moving speed, chemical reaction speed and ion charge transfer process at the electrode/electrolyte interface. At low-temperature (-20°C), the standard deviation of R was larger than other higher temperature, indicating that the electrical performance difference of the battery pack was large under low temperature condition.
Determination of Presence Iron and Manganese in Tasik Chini
Authors: Nadiatul Adilah A A G , Muhammad Syukri L 
Published: March 2021

Abstract
This study investigates the current concentration of heavy metal in Tasik Chini which is iron and manganese. Status of water quality index (WQI) in the rivers at Tasik Chini namely Melai River, Jemberau River, Jerangking River and Gumum River was identified. The water quality results were classified based on the National Water Quality Standard, Malaysia (NWQS). Physical and chemical parameters such as pH, temperature, turbidity, Electrical Conductivity (EC), Suspended Solids (SS), Total Suspended Solids (TSS), Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ammonia Nitrogen (NH3-N), Phosphorus (P) were analysed on site and by laboratory experiments. Two types of heavy metals have been tested to determine the concentration of Iron (Fe) and Manganese (Mn) contained in the water samples in Melai River, Jemberau River, Jeranking River and Gumum River using laboratory tools named as Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). This (ICP-MS) method is conducting by Central Laboratory in Universiti Malaysia Pahang. Based on the results of the study conducted according to the Water Quality Index (WQI) and National Water Quality Standard, Malaysia (NWQS), the water quality at selected locations which are Melai River, Jemberau River, Jerangking River and Gumum River at Tasik Chini was classified in Class II where conventional treatment are required. According to the results of the study, there are activities conducted around Tasik Chini which have caused water pollution which involves the release of heavy metals. Among the activities identified as the main cause of water pollution in Tasik Chini are iron mining, agriculture, illegal logging and waste disposal.
Influence of Doping Concentration on the Zinc Doped Nickel Oxide Nanostructures: Morphological, Structural, and Optical Properties
Authors: Parimon N , Mamat M H , Shameem Banu I B , Vasimalai N , Suriani A B , Mohamed A , Ahmad M K , Rusop M 
Published: March 2021

AbstractThe zinc doped nickel oxide (Zn:NiO) nanostructures with 0 at.% (UD), 1 at.% (1ZNO), and 2 at.% (2ZNO) of Zn concentrations were successfully deposited on the NiO seed-coated glass substrates. The films were successfully produced from two synthesis techniques: the sol-gel spin coating for NiO seed-coated and the solution immersion for the Zn:NiO nanostructures. The films were then pre-baked at 150 °C and subsequently annealed at 500 °C. The Zn doping concentrations affecting NiO in terms of morphological, structural, and optical properties were investigated. The surface morphologies and cross-sectional images of the Zn:NiO nanostructures were observed by field emission scanning microscopy. The observation showed that the groups of nanoflower (NF), which were grown above the nanosheet (NS) array were gradually decreased with the increasing percentage of the Zn doping. The thickness of the NS also drastically decreases as the Zn dopant is increased. The thicknesses measured are 910 nm, 410 nm, and 100 nm for UD, 1ZNO, and 2ZNO, respectively. The X-ray diffraction analysis showed the Zn:NiO peak intensities were affected and decreased as the Zn doping is increased. Take into account the significant differences in the (200) plane, the crystal parameters were calculated. The dislocation density, interplanar spacing, lattice parameter, and unit cell volume increased as the Zn doping increased. Meanwhile, the average crystallite size reduces when the percentage of Zn doping is increased. This condition makes the Zn:NiO nanostructures are promising for sensing applications due to enhanced surface area. The strain and stress values of the Zn:NiO showed the tensile strain and compressive stress, respectively. The transmittance spectra showed the transparencies in the visible region within 400 to 800 nm wavelength increases when the percentage of Zn doping is increased. The average transmittance percentages are 32.1 %, 62.8 %, and 67.0 % for UD, 1ZNO, and 2ZNO, respectively. The optical bandgap increases sharply as the Zn doping increased from 3.55 to 4.75 eV.