Table of contents

We are glad to introduce you that the 2021 International Conference on Energy Engineering, New Energy Materials and Devices (NEMD 2021) was carried out in the form of virtual conference on January 15-17, 2021. Due to the impact of COVID-19 and travel restrictions, NEMD 2021 was held via online collaboration tool, Zoom, which is different from the traditional way. NEMD 2021 aimed to provide a flexible platform for experts and scholars in the field of energy engineering, new energy materials and devices to disseminate the latest research achievements and advanced technologies, as well as to promote the cooperation between each other.

Firstly, we were honored to invite Prof. Hong Qi, Harbin Institute of Technology, China as conference chair and keynote speaker. Prof.Qi is the director of Department of refrigeration and thermal control in Harbin Institute of Technology, and deputy director of Key Laboratory of aerospace thermophysics, Ministry of industry and information technology. Main research fields: thermal radiation transmission and coupled heat transfer, inverse problem and intelligent optimization algorithm, microalgae new energy utilization, near infrared optical imaging, high temperature flame temperature reconstruction, etc. During the conference, the conference model was divided into four sessions, including keynote speeches, invited speeches, oral presentations and online Q&A discussion.

In the keynote speeches session, keynote speakers were each allocated 30-40 minutes to hold their speeches. We were honored to invite four distinguished experts as keynote speakers to present their insightful speeches. Prof. Hong Qi from Harbin Institute of Technology, China, made a speech about Integrated technology of biological photothermal precise diagnosis and treatment based on multifunctional nanoparticles. Prof. Roger Ruan from University of Minnesota, USA, shared his study on Catalytic microwave assisted pyrolysis of solid waste for fuels, energy and chemicals production. Prof. Gangtao Liang from Dalian University of Technology, China and his speech title is: Microscale Heat Dissipation Surface for High-Heat-Flux Cooling. Prof. Jun He from University of Nottingham Ningbo China, China, held a speech on the topic of Cost-effective Non-precious Metal Catalysts for Low-temperature Formaldehyde Decomposition.

In the invited speeches session, invited speakers were each allocated 20-30 minutes to hold their speeches. We were pleased to invite two excellent experts as keynote speakers to present their insightful speeches. Prof. Wenbin Yang from Southwest University of Science and Technology, China, his speech is about Design and preparation of phase change microcapsules and nanocapsules. Prof. Xijun Hu from The Hong Kong University of Science and Technology, China, made a speech about Advanced Catalysts Design Towards Overall Water Splitting.

In the oral presentation's session, some scholars were given about 10-15 minutes to perform their oral presentations one by one. We were honored to invite Prof. Roger Ruan from University of Minnesota, USA as Session Chair of the Oral Presentation's Session. There were fifteen scholars to present their speech on the topic of energy and environmental engineering, etc. In the Q&A session, all participants were invited to join in academic groups to discuss and explore the academic issues after the presentations. The discussion session will last 40 minutes.

The proceedings collected the latest research and results in the field of energy and environmental engineering. The topic of this collection is related to energy engineering, electric power engineering, energy conservation and emission reduction and environmental engineering and so on. All manuscripts published in the proceeding have been through rigorous review and process to meet the requirements of International publication standard.

Finally, we would like to express our sincere gratitude to the Chairman, the distinguished keynote speakers, as well as all the participants. Because of your enthusiastic participation, the conference was successfully held as planned. Thanks to the information technology, the online conference made it easier for more people join in our conference. We had around 80 attendees this time, and we are expecting more and more experts and scholars from all over the world to join this international event next year. We also want to thank the publisher for publishing the proceedings. We are grateful to all those who have contributed to the success of NEMD 2021. We hope that all participants and other interested readers benefit scientifically from the proceedings.

The Organizing Committee of NEMD 2021

List of Organizing Committees are available in this pdf.

All papers published in this volume of IOP Conference Series: Earth and Environmental Science have been peer reviewed through processes administered by the Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

• Type of peer review: Double-blind

• Conference submission management system: Ais Electronic Submission System

• Number of submissions received: 127

• Number of submissions sent for review: 124

• Number of submissions accepted: 58

• Acceptance Rate (Number of Submissions Accepted / Number of Submissions Received X 100): 46%

• Average number of reviews per paper: 2

• Total number of reviewers involved: 34

• Any additional info on review process:

• Contact person for queries: Yunqiu He, Tongji University, yunqiuhe@aliyun.com

Thermoelectric generators (TEG) is the device that can directly convert heat into electricity by the Seebeck effect, which is fascinated for waste heat recovery. An experiment was setup to study the influence of heat flux through the thermoelectric module on the power output and efficiency of a commercial Bi₂Te₃-based thermoelectric modules. The experimental result indicated that the power output evidently increased with the increasing heat flux through the thermoelectric module (TEM), while the conversion efficiency increased significantly at first then the tendency became mild with the increasing heat flux for a given air flow velocity and flow temperature. The temperature differences across the thermoelectric module are almost identical with various air velocity, while the power output and efficiency increased with the increase of cooling flow velocity with a fixed heat flux through the TEM. The power output and efficiency almost linearly decreased with the increase of cooling flow temperature with a fixed heat flux through the TEM and a fixed cooling flow velocity. The maximum output power can be obtained by maximization heat flux without exceeding the upper temperature limit of thermoelectric module.

Under abuse conditions, the temperature of lithium-ion battery increases rapidly and brings high safety risk. To monitor the high temperature incident of battery with a simple and reliable method, a novel design scheme was presented and validated by thermal numerical calculation, in which phase change material (PCM) block is bonded with the battery shell and gets melt down when the battery temperature exceeds its phase-transition point. The melting process is irrecoverable and can be perceived by easy visual observation. Computation results show that the temperature rising of the PCM block gets slower when it meets the melting point, but it generally increases synchronously with the shell of the battery and can be used to reflect the temperature rising of the inner cell. Thus the design scheme is valid, and may possess a good applied perspective in the after-sales maintenance and second-hand transactions of lithium-ion battery.

Traditional researches concerning the damping mechanisms of materials are limited to the phases and structures of materials, ignore the damping-related characteristics of the vibration source and of the materials themselves, and thus have great one-sidedness. This paper combines vibration science and material science on the basis of the models of mechanical vibration. Based on summarizing existing damping mechanisms, it proposes three mechanisms of damping: wave-type, particle-type and molecular force-type. By considering the macroscopic morphology of materials and the structures of molecules composing materials, it provides a guideline for preparing damping materials and studying their performance. Drawing on various research results, it also presents some inference based on available theories, creates a new perspective for researching damping mechanisms, and thus it is of high reference value for future research.

In order to solve the problem of hole collapse and low construction efficiency in the process of soft media gas extraction. A full hydraulic drilling machine with high drilling speed, cross belt construction ability and strong process adaptability has been developed. Through the industrial test, the high efficiency of the drilling machine in the construction of soft coal gas extraction hole is verified, and a method of drilling efficiently in the soft broken coal seam is explored.

The hydrocarbon accumulation conditions of carbonate buried hills in Hexiwu structural belt are superior, and the hydrocarbon accumulation is controlled by multiple factors such as stratum, structure and reservoir, so it is the focus of oil and gas exploration to find high quality reservoirs. Through the analysis of drilling, logging and core data, it is clear that the carbonate reservoir space in Hexiwu structural belt is mainly composed of intergranular pore, tectonic dissolution fracture and tectonic fracture. Sedimentary facies, diagenesis and tectonic movement are the main controlling factors of carbonate buried hill reservoir formation. The favorable sedimentary facies belt is the foundation of reservoir development, the favorable diagenesis is the guarantee of reservoir development, and the favorable tectonic movement is the key to reservoir development. Through the stratified section to carry out comprehensive reservoir prediction, the accuracy of reservoir prediction results is significantly improved, which provides a foundation for oil and gas development.

Heat storage performance of an open thermochemical heat storage (TCHS) system using composite salt hydrates of Wakkanai siliceous shale (WSS) - 9.6 wt.% LiCl was investigated numerically. A two-dimensional model considering the combined heat and mass transfer was developed. The calculation results were validated by the experimental results obtained in our previous study. The inlet air temperature, inlet air relative humidity, humid air flow rate, the ratio of the thickness of air channel and the thickness of composite solid wall, and length of the TCHS unit were evaluated to evaluate the heat storage performance. When the ratio of the thickness of air channel and the thickness of composite solid wall is 5 and the length of the heat storage unit is 0.1 m, the volumetric heat storage density of the open TCHS system can reach 510 MJ/m³.

According to the complex construction conditions in China, such as coal mines roadway cross section is small and the space is little, a new type of down hole drill was designed in this paper. In order to improve the mobility under the coal mines, the split type and narrow body structure was adopted in the design drill process, the compact type and more range combined frame with the ability which can construct for more rows level drill holes in the coal roadways and all–round pitching angle drilling in the rock. The industrial test showed that the new type drilling has well application effect in complex conditions with flexible mobility and process adaptability under the coal mines, the workers labor intensity was obviously reduced.

This study describes the trade pattern of UK fossil energy in terms of imports and exports from 1962 to 2019 and deeply explores the internal causality between the comparative advantage of export and policy interventions including import restriction and export promotion. We document that the UK has been deliberately promoted the import of fossil energy. Granger causality tests show that in the short-run, the policy intervention in import is respectively affected by the policy intervention in export and the comparative advantage of export negatively. Moreover, there are Granger causality running from comparative advantage of exports to import restriction with negative effect in the short-run and with positive effect in the long-run. When it comes to the relationship between policy intervention in export and import, export promotion causes import restriction negatively in the short-run and long-run.

In this paper, a novel junction termination design for 6500V IGBT is proposed. A floating P+ rings termination where the P+ rings are highly doped is less than 2500um. The termination is immune to interface charges at the Si/SiO₂ interface and other layers at the top as well as in the moulding compound. The simulation results show that the breakdown voltages are all above 7000V when the interface charges change from -3E11cm⁻² to 5E11cm⁻². This device was fabricated and the test results show that the breakdown voltage is more than 7000V, which is agreement with the simulation results.

Presulfided NiMoP/Al₂O₃-SiO₂ catalysts were synthesised. The BET surface area and BJH pore volume gradually decrease with P loading due to the ingress of active phases into the pores of the support. No bulk Ni sulfide phase is observed either in the XRD pattern or in the HRTEM micrographs of all catalysts. The mainly high active center is multilayered Ni-Mo-S type II phase benefited from the weak bond between Al₂O₃-SiO₂ support and active components. The incorporation of phosphorous enhances the dispersion of MoS₂ particles and formed more multilayered Ni-Mo-S type II phase. The route of hydrogenation activity increases with the content of P up to 1.2 wt.%, and the route of direct desulfurization activity in the hydrodesulfurization of dibenzothiophene decreases simultaneously. This is attributed to the higher MoS₂ stacking number and shorter MoS₂ slab length.

This paper presents a modified inverse method for retrieving the spectral absorption and transport scattering coefficients of participating medium, the method combines (i) several analytical expressions obtained from the modified two-flux (TF) approximation, (ii) the Monte Carlo (MC) method for predicting normal-hemispherical transmittance T_nh and reflectance R_nh generally obtained from experiments, as well as (iii) an optimization method employing the genetic algorithm (GA). Three types of typical participating medium, the green glass, the low-iron glass, and the silica aerogel with known radiative properties taken form the literatures, were used to illustrate the accuracy and robustness of the modified method by retrieving the input properties from the inverse identification in which the T_nh and R_nh 'experimental data' were obtained from the MC predictions. The results show that the modified inverse method was able to retrieve accurately the absorption and transport scattering coefficients of participating medium.

Feature selection is one of the key factors in predicting. Different feature selection algorithms have their unique preferences for elemental analysis of the data. This results in failing to determine the optimal features when a dataset goes through different feature selection algorithms to get different pools of input features, which in turn affects the prediction quality. To address this problem, the method integrates and fuses the feature importance values of two different feature selection methods. Then the input feature pools are optimized and filtered for the prediction model. Finally, the multifeature pool importance fusion based GBDT (MPIF-GBDT) is developed, which integrates the different feature selection methods and predicts the short-term power load in combination with the gradient boosting decision tree algorithm. In this paper, the tree model feature selection and the Recursive Feature Elimination (RFE) are chosen as feature selection methods. The experimental results show that MPIF-GBDT can significantly improve the accuracy of the prediction compared with the benchmark model.

At present, China has entered the stage of centralized decommissioning of power batteries. If the retired power battery can not be effectively recovered, it will pose a serious threat to the ecological environment and public safety. At present, China's power battery recycling industry has not yet formed a very mature technology line. Against this background, China's government needs to further strengthen the policy system and standard system, increase support for power battery recycling enterprises, and promote the rapid development of power battery recycling industry.

The development of prefabricated building is a transformation of the traditional construction mode, a new cut-in point for the sustainable development of the construction industry, and can promote the supply-side structural reform of the construction industry in China. As an important city in the development of the western region, the development and promotion of prefabricated buildings in Chongqing has played an exemplary role for other cities. Therefore, this research provides a certain degree of theoretical exploration and practical application. In this paper, SWOT analysis is used to analyze the advantages, disadvantages, opportunities and challenges of the prefabricated building, and to gain a full understanding of the development conditions of the prefabricated building. On this basis, the paper summarizes the four major constraints on the development of prefabricated building, including policy factors, economic factors, technological factors and industrial factors, and analyzes the weight of these constraints, in view of each restriction factor proposed the corresponding solution countermeasure.

New energy market competition incentive, how to improve the product accurately, so as to attract consumers, will become the key point for enterprises to occupy the market. From the perspective of improving products, this paper constructs a review information dimension mapping theme emotion analysis model. Firstly, LDA model is used to extract the topic of comment information. Secondly, topic mapping is carried out on the comment information to get the correlation degree between each comment information and each dimension topic. Finally, the LSTM model is constructed for sentiment analysis, and the emotional intensity of consumers in each dimension theme is measured.

The stable configuration of double perovskite LaMgO₃ was constructed by CASTEP module in Materials Studio. How the B sites doping (Sc³⁺, Ti⁴⁺, Zr⁴⁺) affect the structure and physical properties was theoretical investigated. Three configurations of doping are structural geometry and energy optimized by GGA+WC correlation function, according to the principle of minimum energy, the most stable geometry structure is obtained, based on this structure, the physical properties are calculated. The results show that: The energy of LaMg_0.5Ti_0.5O₃ is the lowest and it is deduced as semiconductor according to the band gap. In the vicinity of Fermi level, the interaction between p-electron and d-electron is obvious, which contributes the most to the density of states. By optical properties simulation, the frequency of absorption peaks of the three materials becomes lower and lower in low frequency range, while the absorption peaks of LaMg_0.5Sc_0.5O₃ and LaMg_0.5Zr_0.5O₃ appear earlier than LaMg_0.5Ti_0.5O₃ in high frequency range, but the peak intensity is lower.

Coalbed Methane(CBM) production enhancement for single wells is a big problem to CBM industrialization. Low production is due to insufficient gas generation by thermogenic. Luckily, Biogenic gas was found in many areas and its supply is assumed to improve coalbed methane production. Therefore, microbial simulation experiment will demonstrate the effectiveness of the assumption. From microbial simulation experiment on different coal ranks, it is found that microbes can use coals to produce biogas under laboratory conditions. With different temperatures for different experiments, it turns out that the gas production at 35 °C is greater than that at 15 °C, indicating that 35 °C is more suitable for microbes to produce gas. According to quantitative experiments, adding exogenous nutrients or exogenous bacteria can improve CBM production. Moreover, the production enhancement ratio can reach up to 115% under the condition of adding exogenous bacterial species, while the ratio for adding nutrients can be up to 144%.

Compared with traditional wind turbine performance evaluation methods such as operating power curve fitting, the wind turbine performance model construction method using SCADA data on machine learning has gradually attracted attention in the industry in recent years. In this technical route, the choice of input SCADA data type will directly affect the accuracy of the wind turbine performance model construction. However, in the past, selecting key SCADA data types in the performance evaluation of wind turbines were mostly subjective judgments or correlation analyses. This paper proposed a key SCADA data type selection method based on mutual information calculation and a wind turbine performance model construction method based on deep neural network training. The selected key SCADA data types based on mutual information were applied to the deep neural network to construct the wind turbine performance model, and the actual SCADA operation data of the wind farm was applied to test the model. The results show that the model construction method's accuracy and generalizability using the above technical route can satisfy the industry demand in the same wind farm with the same wind turbine type.

Improving the accuracy of short-term wind power forecasting is critical to wind power consumption. This paper establishes a short-term wind power prediction model based on the multi-feature extraction and deep learning network CNN-LSTM. Muti-features are extracted from original data to improve the accuracy of training. In addition, clustering algorithm is used to classify training data and train the models corresponding to those classes. CNN-LSTM prediction models are established for each cluster and compared with ARIMA, RNN, CNN and LSTM models.

The increase and decrease of non-linear load and impact load of power grid lead to lower and lower power quality, which has become a hot issue in reactive power compensation and harmonic suppression technology research. As one of the AC output equipments, the static synchronous compensator has strong compensation performance and can provide technical support for no power compensation. Therefore, based on the theory of instantaneous reactive power, the current detection method and related control technology of the static synchronous compensator are proposed, and finally the experimental simulation is carried out. The simulation results show that the improved detection algorithm can detect the reactive current of the system efficiently and accurately. Using STATCOM current detection method and control technology, it can adjust reactive power in time, compensate for actual power demand, further suppress system voltage fluctuations and improve system performance.

This article studies the influencing factors of hydrogen refueling station construction from the macro, meso, and micro levels, based on the first-hand questionnaire data and using factor analysis to analyze influencing factors. It is concluded that industry development factors have the greatest impact on the construction of hydrogen refueling stations, and on this basis, the influence weights of various specific factors are calculated. On the basis of the above analysis, relevant suggestions are put forward for the construction of hydrogen refueling stations in my country.

The mechanical and electronic properties of black phosphorene nanoribbons are studied using the first-principles calculations. The armchair black phosphorene nanoribbons (APNR) are obtained and the atomic reconstruction is found at the edge of the nanoribbons. In addition, the strain field is applied on the nanoribbons, and its stress-strain curve, Young's modulus, and Poisson's ratio are calculating by stretching APNR. It is found that the Young's modulus enhanced with the increase of nanoribbons width. It is significantly lower than the Young's modulus of monolayer black phosphorene. On the contrary, the Poisson's ratio hardly changes with the increase of nanoribbons width. Finally, it is found that the band gap of APNR decreases with the increase of nanoribbons width and increases monotonically with the increase of strain.

Aiming at the problem that the value density of variables in the state-aware network of complex industry system is low, which leads to poor timeliness of state evaluation, a key variable screening method for state-aware network is proposed. Firstly, a causal network model that can accurately reflect the interaction mode between the monitoring variables of the system is established. Secondly, each node of the causal network can be ranked by the LeaderRank algorithm and the variable set can be divided into multiple sets of variables. Finally, each variable set can be used to evaluate the performance state of the system, and the effectiveness index of variable screening is constructed to evaluate the accuracy and timeliness of the evaluation results of each variable set, then the key variables can be obtained. The Tennessee Eastman (TE) process data is used to test the proposed method, the result shows that the key variables obtained by the method can effectively improve the evaluation efficiency of the performance state.

In this paper, the suitability of using seawater source heat pump in a seaside refrigeration station in Qingdao was evaluated. A systematic evaluation was made on the conventional chiller with cooling tower system, the conventional chiller with titanium plate heat exchanger system and the seawater source heat pump system, including energy saving evaluation, economic evaluation (initial investment cost and operating cost) and environmental evaluation. The evaluation results showed that the initial investment cost was slightly increased, the operating cost was low, the cop value was high and the impact on the marine environment was small when the seawater source heat pump system was directly used.

Computational fluid dynamics numerical simulation method was used to numerically simulate the combustion process in 700 °C ultra-supercritical compact swirl opposed coal-fired boiler. The flow field distribution, composition distribution and NO distribution in the furnace were obtained through simulation. Simulating the NO generation in the boiler when the burner is put into different operation modes under different loads. The results show that the velocity and temperature fields in the ultra-supercritical compact boiler have the same characteristics as the typical swirl opposed coal-fired boiler. The O₂ concentration showed good consistency with the main gas products CO and CO₂ concentration. To a certain extent, NO generation and distribution characteristics are related with the temperature field. When the burner is put into operation in different ways, NO generation and distribution are different correspondingly. The simulation and test can provide theoretical basis for the technical implementation and structural optimization of the ultra-supercritical compact boiler at 700 °C.

Borophene has received considerable investigations in recent five years that it is reported to possess a series of marvelous properties. However, most of the researches are about its monolayer form, the bilayer borophene, especially the twisted bilayer form which is a hot topic recently, has not been studied in detail. Herein, the first-principles calculations based on the density functional theory (DFT) method was performed to study the electronic properties of three kinds of twisted bilayer borophene that each kind of bilayer borophene is twisted to a certain angle in the plane. For the consideration of structural stability and calculation cost, the bilayer borophene are optimized to be 32.2°, 58.0° and 83.6° using an algorithm based on crystal matching theory. The charge density of relaxed twisted bilayer borophene shows the proximity of boron atoms. The analysis of band structure reveals that the twisted bilayer structure could separate the degenerate band and transform the bands to direct type, thus, modulating the resistance. In addition, a near-zero density of states could be found when bilayer borophene is twisted. This research could provide a basis for the applications of borophene, such as integrated electronic devices and micro/nano electronics.

Insulated Gate Bipolar Transistor(IGBT) is a fully controlled power electronic device with excellent comprehensive performance, which is widely used in various inverter units. At present, Infineon's IPOSIM simulation is usually used to obtain the power consumption and junction temperature fluctuation of IGBT modules, but it is only applicable to IGBT modules produced by Infineon. In this paper, the power consumption of IGBT and diode is calculated, and the expression of junction temperature fluctuation is obtained based on junction-shell transient thermal resistance, which is suitable for common IGBT modules. Finally, simulation verifies the correctness of the calculation method.

Given the current situation that there is no parallel experiment of multiple stacks in China, this paper uses a fuel cell test platform independently designed and produced by a company to study the performance of three fuel cells. This article describes the construction of the experimental test platform and the multi-stack load-up experiment. The experimental results show that the power generation of the three fuel cells is almost the same, which are 9475W, 9385W, and 9512W. When carrying out multi-stack load-up experiments, it was found that as the number of stacks increased, the voltage efficiency continued to decrease. The Analysis revealed that the parallel gas supply method caused uneven gas distribution, which caused some fuel cells to be in a state of hydrogen deficiency. This article proposes amendments to this problem.

Because the wind turbine system is complex and involves a wide range of disciplines, the model-based system engineering (MBSE) method is used to effectively process demand analysis, system function analysis, and system logic architecture design synthesis and verification in a graphical manner, forming a standard Sequential design process reduces costs and improves design efficiency. Requirement analysis is the key to system design and the key to the forward design process of MBSE system architecture model. It is of great significance to the entire system and subsequent development. This article mainly describes the application of MBSE in wind turbine system demand analysis.

In order to obtain a good stability of micro-encapsulated phase change suspension, then study its rheological properties, herein formulated a phase change micro-capsulated suspension and utilized isopropanol/water mixed solution as the base fluid. The particle size distribution, viscosity and rheological properties of micro-encapsulated phase change suspension were measured at different concentrations. The effects of mass fraction, temperature on viscosity were discussed. Based on the classic viscosity formula, a correction factor was introduced to get higher precision viscosity formula. The results show that: a volume ratio of 1:1.75 of isopropanol/water suspension, suspension stability is up to 48h. It is also found that the viscosity decreases with the increase of temperature, but it increases with the increases of mass concentration. The fitted Tomas viscosity formula is reliable when the volume concentration is less than 15.58%, the error could be controlled within 5.7%.

With the steady progress of the energy transition, the proportion of renewable energy in my country has continued to increase, and the market-oriented trading of renewable energy power has become an important link in promoting the construction of Chinese low-carbon clean energy system.Under the background of the new quota system policy, through the analysis of Chinese renewable energy distribution and market-oriented transaction needs and characteristics,research the application method of BlockChain technology in renewable energy power transactions,from the three aspects of transaction system architecture, BlockChain support technology selection, and transaction process management, an intelligent transaction model suitable for Chinese renewable energy power consumption is proposed, building an automatic matching and automatic settlement method for renewable energy power transactions based on BlockChain technology, optimizing the transaction process, and reduce transaction management costs, providing a certain reference for the development of Chinese renewable energy power market trading.

The generation, propagation and distribution of power transformer vibration and noise are studied by modeling and simulation. Based on the theoretical analysis of the mechanism of power transformer vibration and noise, the correlation between the characteristics of power transformer vibration noise and the influencing factors is determined. The solid model of single-phase power transformer is established by using multi physical field finite element analysis software. The multi physical field coupling simulation of electromagnetic field, structural force field and pressure acoustic field is carried out. The spatial distribution and frequency characteristics of vibration and noise signal of single-phase power transformer in each solution domain are displayed. It provides theoretical and technical support for smart grid equipment detection and environmental noise comprehensive control.

Many parameters can influence performance of a distributed energy system as it involves various kinds of equipment. Proper sizing of various equipment is of great significance for its efficient operation of such systems. This paper took a business district as the research object, predicted and analyzed the hourly cooling/heating load of the system during typical days of different seasons. Based on comprehensive consideration of the user's usage pattern, load, equipment characteristics and other issues, gas engine was selected as the system's prime mover, and the system structure was designed accordingly. Mathematical model was developed including gas engine, gas boiler, absorption chiller and other equipment. The differential evolution (DE) algorithm was applied to optimize the equipment capacity of the energy system, with the multi-objective of lower annual total cost and less annual emission. The annual pollutant emission of the plan C is the lowest in the results, which is more suitable for the business district. Compared with the traditional energy system, the annual total cost and pollutant emission of the optimized system were about 22% and 27% lower, respectively. The distributed energy system shows significant advantages.

It is difficult to obtain the accurate small signal modeling by traditional modeling method especially for the complex converter. System identification is a new method to construct the high voltage cascade converter small signal modeling. The first-stage and the second-stage can be analyzed on the whole. The improved least-square parameter estimation is used to analyze the sampling data of input and output. Furthermore, the system parameter and accurate system modeling can be acquired. Comparing the step response of system model with the Pspice stimulating result, the validity of the method is verified.

Insulated Gate Bipolar Transistor(IGBT) is the most widely used fully-controlled power electronic device at present, and the rated DC current and maximum pulse current given in the manual can't reflect the working limit current. In this paper, considering the influence of temperature, the electrical model of IGBT is extended to electro-thermal model, and the stable point, unstable point and critical point of junction temperature are obtained by combining IGBT power consumption-temperature curve and heat transfer curve, thus the limit power consumption at the critical point is obtained, and the limit current is designed. Finally, experimental verification is carried out.

Researches of igneous intrusion in Fuxin basin on more complex formation mechanism of low-rank coalbed methane(CBM)reservoir are not only the focus and critical problem of basic geology, but also contribute to improvement of the exploration effectiveness of the same type of reservoirs, serving as one of rare achievement examples of low-rank CBM development. This paper presents a comprehensive research of the reservoir characteristics of the Wangying-Liujia CBM formation, such as the intense control action of the dolerite dike invasion so as to further confirm the effects of igneous intrusion on low rank CBM reservoir formation. The result shows that the dolerite dike invasion not only facilitates large hydrocarbon regeneration, but also obviously improves the Ro of the thick bituminite at the bottom of Fuxin formation. It also greatly improves the coal reservoir property, which helps the groundwater double replenishment along the coal seams outcrop and dolerite dike and the closed pressure water condition formation. Moreover, the research shows that there exists much free gas clearly for the closed fault-preventing gas diffusion. So the cokeite growing area is the most advantageous where the high production CBM wells will distribute in the girdle band along the dike. In summary, concerning low-rank CBM exploration, this paper proposes gas evaluation by using CBM and conventional means.

The electro-thermal model of Insulated Gate Bipolar Transistor(IGBT) can be used to simulate the operating characteristics of devices at different temperatures. Considering the relationship between internal parameters, semiconductor physical constants and temperature, the electrical model of IGBT at a single temperature is extended to an electro-thermal model which can reflect the working characteristics at different temperatures. This model takes into account both simulation accuracy and simulation speed. Finally, the IGB model is selected, and the IGBT switching transient at different temperatures is verified by experiments.

Important load users are the lifeline of urban development, and their energy security system is not yet complete. According to the existing power load classification guarantee principle, the comprehensive energy load classification and guarantee measures of important users are discussed. At the same time, it analyzes the characteristics of existing security resources, selects the semiconductor manufacturing industry as the application scenario, and explores more possibilities for flexible configuration of security resources for users with important loads. Finally, the distributed energy system is proposed as a security resource for semiconductor companies, and it is used as a backup with the mains, replacing conventional diesel generating sets, and switching from cold standby to hot standby. This will reduce the initial investment in enterprise construction, improve the utilization of security resources, and the reliability of energy supply for important load users.

In this paper, the near-field radiative heat transfer between two semi-infinite plates with different temperatures, which are composed of homogeneous lossy media, has been studied firstly. Attributed to the evanescent wave generated by total internal reflection, the near-field radiative heat transfer is much larger than the far-field radiative heat transfer. And, the closer the distance between the two plates is, the greater the heat transfer is. Then, a graphene layer has been used to cover on the surface of the plate with lower temperature to study the effect of graphene on the near-field radiative heat transfer. The results show that the existence of graphene can promote the near-field radiative heat transfer due to the excitation of surface plasmon polaritons on the surface of graphene. In addition, the heat transfer varies with chemical potential of graphene, which indicates that the near-field radiative heat transfer can be controlled by an external gate circuit. In the presence of graphene, the thermal resistance between the two plates ranges from 6.7×10⁻⁴ to 0.18 K/(W/m²) and increases with the increase of the thickness of vacuum gap between the plates.

Taking the axial exhaust condenser of one gas-steam combined cycle unit as the research object, the steam flow in the shell side of the condenser was simulated under summer operating conditions. The flow distribution of the condenser in the shell side was obtained. Through the extraction of simulation data, the pressure of the condenser was obtained. The simulation results of single factor influence showed that the main factors leading to high operating pressure of the condenser under summer working condition were steam load, circulating water inlet temperature, circulating water flow and vacuum tightness.

Wuerxun depression is a secondary structural unit of Beier lake depression in Hailaer basin. It is located in the middle of the basin and has a high degree of exploration, with the gradual deepening of exploration degree, the previous studies on sequence division and sedimentary facies cannot meet the requirements of high-precision exploration. In this paper, the Nantun Formation is divided into three third-order sequences and eight fourth-order sequences through the study of high-resolution sequence stratigraphy in Wuerxun depression, in the study, firstly, multiple exploration wells with complete sequence development are selected in Wunan area of Wuerxun depression, because Wuerxun depression on the whole is characterized by complex structural features, multiple provenances, short provenances and rapid phase transformation, so we should try our best to make the distribution of preferred wells in all the fourth order structural zones, in order to facilitate the next step of stratigraphic correlation between the structural zones and the whole region. After that, the original sequence of all the selected wells is further subdivided according to the rock and electrical characteristics of single well, and a set of scheme for dividing the fourth-order sequence is determined. Finally, through the tracing of seismic horizon between exploration wells and the fine comparison of well and well seismic in the development area, the traceability and comparability of the newly divided fourth-order sequence are determined, and a set of reasonable fourth-order sequence division scheme in Wuerxun depression is finally determined, which effectively guides the geological oil and gas exploration deployment and lays a solid foundation.

The regional scale source network load storage coordination system is an effective organization form to increase the proportion of clean energy and absorb distributed renewable energy. However, due to the different ownerships of various distributed resources in the system, balancing the interests of different stakeholders in the operation is an important issue to be considered. The types of distributed resources contained in the regional scale source network load and storage system and their belongingness are analyzed in different perspectives, and then the optimal operation strategy of distributed resources is proposed to balance the interests of different stakeholders. Based on this strategy, a bi-layer optimization model with energy supply cost minimization and the power consumption satisfaction maximization is established. It takes the power supply of the energy supplier and the power demand of consumer as the correlation variable of the upper and lower layer models, the analytical target cascading (ATC) theory is used to adjust the correlation variables iteratively until the power supply meets the power demand, and obtains the distributed resources trade-off operation plan satisfying different objectives. YALMIP modeling tool is used to call CPLEX solver on MATLAB platform to solve the model in parallel. An example based on the data of a regional scale source network load storage system shows that the optimization model and its solution strategy can effectively balance the optimization objectives of different stakeholders.

This paper presents a new maximum power point tracking (MPPT) method which can improve the dynamic tracking ability under two varying external conditions, rapid irradiance variation and grid voltage fluctuation. Different from irradiance variation, the dynamic error of tracking voltage caused by grid voltage fluctuation is usually ignored by MPPT methods. The dynamic error of tracking voltage can make the unexpected power change of photovoltaic system and influence the dynamic MPPT efficiency. According to the different current increment changes under the irradiance variation and the grid voltage fluctuation, the reasons of dynamic voltage errors are analyzed and distinguished. And two corresponding modes of variable step size are designed in the tracking algorithm to regulate the voltage deviation from MPPs. The effectiveness and the improved dynamic tracking performance of the proposed MPPT method are verified by simulation results under the above two varying external conditions.

This paper reviews the origin of artificial floating islands at home and abroad and introduces the principle of purifying water quality of artificial floating island, including the selection and combination of plants in floating island. The mechanism of microbial and plant combined action to remove organic matter in water is discussed one by one. The development trend of the new artificial floating island is discussed in order to provide reference for the new artificial floating island technology in the future.

In recent years, water pollution and eutrophication are becoming increasingly serious, plankton represented by Cyclops and algae frequently appear in many urban micro-polluted water sources. The current methods to remove algae include catching, adding algicide, adding oxidant, enhanced coagulation and so on, and the current methods to remove the Cyclops include adding oxidant, coagulant precipitation treatment, biological activated carbon filtration, etc. This paper analyzes the effect of different methods on removing plankton in the water, and their advantages and disadvantages, to solve the problem of algae and Cyclops due to seasonal reasons for short outbreaks.

Thermochemical flooding is becoming more popular nowadays as a subsequent EOR method after thermal recovery in extra-heavy oil reservoirs. During this process, in-situ emulsions could happen due to interfacial active components existing in heavy crude oil. The enhanced oil recovery is inevitably related with the formation of emulsions, which is one of the main mechanisms and deserves a thorough study. Also, the features of relative permeability curves during thermochemical flooding should be investigated further, because they are very important but usually are difficult to obtain since physical reactions could happen.

Based on core-flooding experiments, combined with careful observation of produced crude oil emulsion morphology, this paper compared and analyzed the features of relative permeability curves and displacement efficiency at different conditions, and the mechanisms of extra-heavy oil production by surfactant displacement is then investigated. The surfactant used are provided by the oilfield at a varied mass fraction of 0.1%, 0.2% and 0.3% and under temperature of 100, 150 and 180 °C. The relative permeability data were processed with JBN method.

The experimental results show that both the oil and water relative permeability increase as the temperature increases. As surfactant concentration increases, the relative permeability of the aqueous phase decreases as opposite to oil. The ultimate recovery increased with the increase of temperature and surfactant concentration. Except for the oil viscosity reduction by surfactant, it is interesting to note that the formation of crude oil emulsions (mainly O/W emulsions) are observed to be positively impacting the oil recovery factor. As surfactant concentration increases, larger size of dispersed phase in the emulsions were observed in the effluent corresponding to a higher oil recovery factor. This work is of great significance for heavy oil research and field development.

To make the complicated environmental protection work simple, environmental protection GIS is widely used. Direction relation reasoning is an important branch of spatial reasoning, it is also one of the most basic theoretical issues in the Environmental Protection Geographic Information System. This paper proposes a modelling method of combining the cone-shaped direction relation model with the direction relation matrix to determine the fuzzy direction relation between spatial entities on the basis of the cone-shaped direction relation model and direction relation matrix in Environmental Protection Geographic Information System, the advantages of the two models are fully utilized to overcome the disadvantages of them. Firstly, "central-region" is divided into nine equal internal sub-regions on the basis of the Minimum Bounding Rectangle (MBR) model. Then, the central-region of the direction relation matrix is divided again by using the cone-shaped direction relation model, and a fuzzy formal description model is given by taking point entity and area entity as research objects. The application of direction relation reasoning model in Environmental Protection GIS is helpful to improve the efficiency of judging the direction of pollution sources and the level of environmental protection.

Plant landscape design is one of the main contents of highway design. This paper sums up the principles and methods for plant landscape design based on the compositions of expressway landscape, and discusses in detail the point of plant landscape design for the green belt on both sides of the expressway, the central separation belt and the subsidiary green area.

Anammox, as one of the most revolutionary new denitrification technologies so far, has broad application prospects. In order to explore the start-up process of the anaerobic ammonia oxidation process, the experiment was conducted to domesticate anaerobic sludge in an up-flow anaerobic sludge bed reactor. The results showed that the reactor reached a stable operation stage from the 95th day to the 112th day. The removal rate of NH₄⁺-N and the removal rate of NO₂⁻-N were stabilized at 94.12% and 97.70%, respectively. According to the removal of NH₄⁺-N and NO₂⁻-N in the reactor, the start-up process can be divided into 4 stages, and there is denitrification and synergistic anaerobic ammonia oxidation in the reactor.

Molecularly imprinted polymers (MIPs) of sulfamethazine (SMZ) were prepared initiated by election beam irradiation in acetonitrile (ACN) with the use of SMZ as template molecule, acrylamide (MAA) as a functional monomer and ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent. The combination of SMZ with MaA and EGDMA was studied by infrared spectroscopy. The adsorption kinetics experiment and selectivity of sulfamethazine imprinted polymers were investigated by ultraviolet spectrometry. The experimental results showed that there was a binding effect among SMZ, MAA and EGDMA. When the molar ratio of SMZ, MAA and EGDMA was 1 : 4 : 20, and the irradiation dose was 150 kGy, the adsorption capacity of MIP for sulfamethazine (Q_MIP) was the largest (31 mg·g⁻¹). Furthermore, the imprinting factor (F) was 12.91, and the separation factor (α) for SMZ and sulfonamide (SNM) was 1.77.

This paper introduces a new type of toxic and harmful gas analyzer based on DOAS (differential optical absorption spectroscopy) technology. Combined with the least square method, it can monitor H₂S, NH₃, SO₂, NO₂ and CH₃SH online at the same time, and the prescribed minimum is as low as 0.1ppb, the detection breadth and accuracy are higher than those of the current common DOAS instruments.

Western Hunan is the core and key area of ecological restoration and protection in the mountain areas of southern China and the middle and upper reaches of the Yangtze River. How to make a good trade-off in land-using between ecological conservation and economic development is the primary issue for the regional sustainable development. We analyzed the spatial-temporal changes of land use and socio-economic development in this area. The results showed that: 1) The change of cropland, woodland and urban construction land from 1980 to 2018 was significant, and cropland was evolving towards the hollowing pattern, while the urban construction was expanding from the center to the periphery; 2) With the high speed of socio-economic development in recent years, rural population and the production industry proportion of each county deceased, while urban population, the manufacturing industry proportion and the service industry proportion were increasing; 3) There was a strong correlation between the area proportion of cropland, woodland and the proportion of rural population and the production industry, and the correlation decreased first and then increased with the annual economic development, while the urban construction land had a certain correlation with urban population and the manufacturing industry and the service industry, especially with the service industries. On the basis of further analysis, it was concluded that the social and economic development were the important driving factors to land use change, the capacity of ecosystem services reduced in recent years. The results could be used as the basis for the local government to make decision on the effective land protection. It was also a reference information for researchers to carry out in-depth optimization and integrated management on land resources, so as to achieve the good synergistic effect for both socio-economic development and land protection and promote the sustainable development of human society and economy.

In order to broaden the processing conditions of the Fenton method, under the premise of adding a catalyst, the operating conditions of the Fenton-like system were studied. When studying Fe3O4-MnO2-PAC composite material as a catalyst,this experiment find the influence of different single factors on the Fenton-like system. Research shows that when the pH is 2-5, the dosage of Fe3O4-MnO2-PAC is 800mg/L, the dosage of H2O2 is 0.8mol/L, the reaction temperature is 10°C-50°C, Fe3O4-MnO2-PAC catalyst. When used less than five times, it has a better degradation effect on methylene blue wastewater.

The dormant Sedum aizoon L.seedlings were treated with different days(1d, 3d, 5d and 7d) of low temperature (5°C), and restored to grow for 40d (25°C).The growth indexes, photosynthetic characteristics and carbohydrate metabolism indexes were measured to compare the dormancy relieving effects of the seedlings. The results showed that Sedum aizoon L. was physiologic dormancy, and the effect was the best when it was treated at 5°C for 5 days, and the dormancy was completely relieved.

Fractal theory can be applied to study the complexity of spatial structures in nature, and operates by extracting the deterministic parameters driving complex processes. However, to date there has been little reported application of fractal theory to the analysis of the sources of soil heavy metal pollution. This study aimed to determine the sources of heavy metal accumulation in the shallow soil of the Youjiang River Basin. A total of 71 shallow soil samples were collected across an area of 1,000 km2 for the analysis of Cd and Pb to determine the spatial distribution of heavy metal pollution in the basin. The fractal characteristics of Cd and Pb for the eastern, central and western parts of the study area were analyzed using a content-frequency fractal model. The results showed that the content-frequency fractal distributions of Cd and Pb in the area were similar and multifractal. Linear models described the three different groupings of the sample points well with a scattering of several high points, indicating a chaotic distribution of high-content Cd and Pb areas. Two linear models similarly could describe the fractal distributions of these two elements in the eastern part of the study area, with a scattering of several high-value points, whereas although the fractal distributions of the central and western parts of the study area also showed linear distributions, the linear fit for the western part of the study area was slightly worse. The fractal distributions indicated that the spatial distributions of soil Cd and Pb show several trends, which indicates the influence of multiple geochemical processes. When combined with regional industrial and mining enterprises and high density population, the fractal Cd and Pb distributions infer that soil Cd and Pb in the area originate from the same sources, and four major geochemical process are responsible for the distribution of Pb and Cd: 1) the soil formation process; 2) modern agricultural production; 3) industrial sources and dense population; 4) aluminum resources development and utilization. Among these, exploitation and utilization of aluminum resources is the most complex, resulting in a chaotic distribution of Cd and Pb.

In Pingxiang mining area of Jiangxi Province, a large amount of non-spontaneous combustion coal gangue is piled up into mountains, which not only occupies the land, but also seriously pollutes the ecological environment. In order to solve this problem and improve the utilization rate of coal gangue, the study of coal gangue without spontaneous combustion in Pingxiang mining area was carried out, and the differences of chemical composition, physical characteristics and thermal activation characteristics of coal gangue were analyzed. On this basis, the coal gangue was used as coarse aggregate instead of some natural stones, and the influence of different temperatures on the compressive properties of coal gangue aggregate concrete was studied. The results show that the compressive strength of gangue concrete is lower than that of ordinary concrete at room temperature. At high temperature, under the influence of secondary hydration of cement and thermal activation of gangue, the compressive strength of concrete test blocks in each group presents an upward trend before 400°C, and reaches its maximum strength at 400°C, among which the mechanical strength of concrete with 30% gangue coarse aggregate is the best. This study provides a basis for the resource utilization of coal gangue in Pingxiang.

The long-distance water transfer project alleviates the situation of water supply tension in various parts of China. In the process of raw water transportation, the nitrification reaction will be carried out by microorganisms due to the existence of a pipe wall biofilm, which converts ammonia nitrogen in water into nitrite nitrogen and nitrate nitrogen. Nitrification of pipeline biofilm is affected by many factors, including temperature, dissolved oxygen concentration, nutrient content, type, and concentration of disinfectants. These factors can change the activity, quantity of nitrifying bacteria, and the conversion rate of ammonia nitrogen, which leads to the effect of nitrification.

The northeastern part of the Ordos Basin is the main recharge area of regional groundwater, the groundwater resources are relatively scarce. The main water supply source in the area is shallow groundwater, and there are many industrial and mining enterprises in the district. The potential groundwater pollution risk is high, and the the shallow groundwater vulnerability evaluation in the region is of great significance for groundwater resources protection.The weight of each indicator of the traditional DRASTIC model is fixed and does not change with the regional conditions, which may cause deviations in the evaluation results. This time, based on the DRASTIC model, the entropy weight coefficient method is introduced to determine the index weight, and the DRASTIC entropy weight model is established to obtain a more scientific and close to the actual conditions of the study area, and provide an important reference and basis for the protection of regional groundwater resources.