bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on the Mechanism of Slagging and Fire-off for different capacity boilers
Authors: Wang Shuai , Wang Kai , Lu Kun , Zhang Qingguo
Published: March 2020

For slag extinguishing process of different capacities boilers (1000MW, 670MW, 300MW, 150MW), the slag extinguishing mechanism is analysed in terms of equipment, slagging characteristics, coal quality, furnace heat load, and operation mode. Prevention measures for slag extinguishing are put forward in terms of fire coal controlling, operation optimization, and technical transformation. Analyses results show that there are mainly three types of furnace pressure change during the slag extinguishing process. The common feature is that the furnace pressure goes up first, which is because of combustible gas explosion in the lower part of the furnace (primary reason) and the entry of a large amount of water vapor into the furnace (secondary reason). The degree of slagging for these four boilers is aggravated by the factors such as high ash content and sulfur content, the low input frequency of soot blower, and the large fineness of the pulverized coal.
Blockchain Auditing Technology for Inter-provincial Generation Right Trading
Authors: Lv Jianhu , Zhou Lin , Liu Shuo , Zhang Shuo , Si Liangqi , Li Guodong , Chen Ailin
Published: March 2020

This paper proposed an auditing method for medium and long-term inter-provincial generation right trading based on blockchain technology, ensuring that market participants’ private data and trade secrets cannot be tampered, and the transaction process can be traced back. In this way, trading institutions and regulatory authorities can obtain credible data. The method can provide a two-way book to trace the flow of energy and financial assets, provide data verification services to confirm the integrity and validity of the data, and it can provide data auditing service to identify contents that have been tampered. This paper took the generation right trading between the East and the West of China as an example, a blockchain testing environment was established to verify the feasibility of the auditing method for generation right trading. This paper offered an auditing solution for registration, declarations, clearing, and settlement of data involved in inter-provincial generation right trading.
Research on the development trend of virtual power plant in the spot market
Authors: Mu Yicheng
Published: March 2020

With the continuous promotion of power market reform, the spot market of electric power is gradually opened, and more and more flexible renewable energy can participate in market transactions. In order to ensure the safe and stable operation of power grid, virtual power plant has been developed. In the spot market, virtual power plants gather different resources and take part in market transactions as a whole. This not only benefits the virtual power plant itself, but also the whole power system. In order to study the impact of the spot market on the virtual power plant, this paper starts with the basic theory of the virtual power plant, then combined with the development of the spot market, studies the basic process of the virtual power plant participating in the market transaction, and explores the future development trend of the virtual power plant.
The preventive measure of power system blackout considering the thermal stability and voltage stability
Authors: Wang Jialin , Yu Qun
Published: March 2020

In order to ensure the reliable transmission of electric energy, some preventive measures are adopted to improve the stability of the power system. The thermal stability of the system can be improved by increasing the transmission capacity. And the voltage stability of the system can be improved by installing reactive power compensation device. In this paper, the above two methods are integrated. Firstly, the objective functions of thermal stability, voltage stability and economy of the system are established. Then the multi-objective particle swarm optimization (MOPSO) algorithm is used to solve the optimal configuration scheme of the thyristor controlled series capacitor (TCSC) and the static var compensator (SVC). Finally, according to the simulation results of the classical power failure model, the effectiveness of the proposed method is verified.
Prediction technology and application of primary frequency regulation capability of thermal power unit
Authors: Gao Song , Wang Jin , Wang Ming , Yan Qing , Yu Qingbin , Liu Enren , Li Yuanyuan , Meng Xiangrong
Published: March 2020

As one of the important functions of grid connected thermal power generation units, the primary frequency regulation function aims to increase and decrease load rapidly when the grid frequency changes, so as to achieve the stability of grid frequency. The primary frequency regulation capability of the unit is easy to be affected by the current main parameters of the unit operation and the operation mode of the equipment, which will lead to the phenomenon that the primary frequency regulation capability of the unit is insufficient. This paper introduces the basic principle of primary frequency regulation of thermal power units, and puts forward the main technical methods for prediction of primary frequency regulation capacity of units. Through the real-time prediction of the primary frequency regulation capability of the thermal power generation unit, the operation parameters and equipment operation mode of the thermal power generation unit can be changed in time, so as to avoid the lack of primary frequency regulation capability when the grid frequency changes. Finally, a typical industrial case is used to verify the effectiveness of this technology.
Research on new blast and fire stopping system of valve hall for UHVDC converter stations
Authors: Zhong Bo , Zhang Jia-Qing , Zhao Chang-Zheng , Zhang Ze-Jiang , Jiang Ya-Qiang , Fan Ming-Hao , Liu Xiao-Sheng
Published: March 2020

In this paper, a new blast and fire stopping system of valve hall for UHVDC converter station is proposed. With the hydrocarbon temperature rise curve, the fire resistance test of a 1.4m×1.8m sample was carried out, a numerical model for blast resistant analysis of the firestop structure was established, and the blast resistant performances of the original firestop structure and the new structure were calculated. The results show that the new fire and blast stopping system proposed in this paper has a fire endurance time limit of more than 4 hours with the hydrocarbon heating curve. At the same time, compared with the original system, the blast resistant capability of the new firestop structure is greatly improved.
A Novel Design Method for Resonance Network Parameters of Bi-directional CLLLC Resonance Converter
Authors: Hu Fangzhou , Qi Chengchao , Yu Xiaohang , Zhao Hongtao , Liu Anbo
Published: March 2020

In order to solve the problem that there are many resonant elements and it is difficult to design the full bridge CLLLC resonant converter, an improved resonant network parameter design method combined with simulation analysis is proposed in this paper. Accurate DC voltage gain curves are obtained under different resonant parameters. A 3.5 kW simulation circuit is constructed based on the parameters of the proposed method. The simulation results confirm the correctness and feasibility of the proposed improved design method.
Automatic logic optimization of denitrifying ammonia system for supercritical unit
Authors: Du Zhizheng , Song Ruifu
Published: March 2020

Based on the optimization of the automatic logic of the supercritical unit denitrifying ammonia system in a power plant, a cascade control system with the output NOx concentration as the main control loop and the supply ammonia flow as the secondary control loop is proposed, and on the basis of the cascade control system, the control strategy for eliminating system interference is added. Increase the response rate of the system. In particular, when the NOx concentration at the entrance fluctuates considerably, the optimized ammonia injection system quickly issues instructions to the ammonia flow regulator to adjust the NOx concentration at the flue gas outlet so that it tends to set values in a short period of time.
The Design of Controller for BLDC Based on STM32
Authors: Zhang Fengcan , Kong Xiangyu , Li Fang , Zhang Yulin
Published: March 2020

According to the characteristics and operation principle of brushless DC motor (BLDC), a drive controller of brushless DC motor is designed from the aspects of hardware and software. The control system uses STM32F103RBT6 as the control chip, including power supply circuit, drive circuit and detection circuit. According to the structure and characteristics of the brushless DC motor, the control system adopts the FOC vector control strategy and the double closed loop control strategy of the PI speed loop and the current loop. The experimental results show that the control system can control the motor to run stably and fast, and the control effect is good and the response speed is fast.
Fault and safety protection of ship power station
Authors: Yang Yuxin , Jin Zhemin
Published: March 2020

With the continuous development of the shipbuilding industry, there are more and more ship types, and the tonnage of ships is getting bigger and bigger. Traditional low-voltage ship power systems are no longer sufficient for navigation, and 6600 V high-voltage power supply systems are increasingly being used on large ships. High-voltage equipment is different from traditional low-voltage equipment, and incorrect operation can easily lead to safety accidents. In the process of building a ship, the shipyard has a complex environment. How to do safe operation and protection is especially important. This paper focuses on the safe operation characteristics of equipment, analyzes common faults, analyzes the requirements of on-site personnel for high-voltage safety protection, and ensures that the mooring test is carried out smoothly, and the test personnel and high-voltage power equipment are not damaged.
Research on application scheme of UPFC in UHV power grid based on multi-objective evaluation
Authors: Shen Xuhui , Luo Hongmei , Gao Wenman , Feng Yuyao , Feng Nan
Published: March 2020

UPFC can distribute the line transmission power rationally and improve the stability of power grid operation, which is not only the focus of the current attention of the engineering community, but also the hot spot in the academic field. Aiming at the application of UPFC in UHV power grid, this paper first introduces UPFC’s principle and function. Based on the analysis of the problems in UHV power grid planning, this paper proposes the UPFC application scenarios in UPFC power grid. Then using BPA simulation platform, this paper calculates and analyzes the feasibility of each UPFC alternative location in different scenarios. Finally, based on the fuzzy evaluation, the comprehensive evaluation of each scheme in technical level is carried out. The results show that UPFC has strong capability in improving the transmission capability and improving the system voltage, which can solve the problems that UHV Power Grid will face effectively.
Analysis and Treatment of Generator Vibration Faults in a Power Plant
Authors: Chai Baotong , Zeng Qing Meng , Wu Zhengfeng
Published: March 2020

This paper presents a detail research on a vibration high fault after overhaul occurred on a generator. During the overhaul, the generator rotor is returned to factory for processing and replaces section across the line of the generator excitation end. The gas turbine unit vibrates high in the idle 3000 r·min−1 and full load. The large vibration of the generator is mainly caused by the following two factors:the imbalance in the overhanging end of the generator rotor and the electrical fault in the generator itself. The unbalanced amount of generator overhang was successfully eliminated by dynamic balance test. The electrical fault of generator itself needs to be returned to the factory to handle.
Construction and Application of Data Mining Model of Unit Scale Cost of Electric Grid Project
Authors: Rong Peng , Liu Guoming , An Peng , Qi Xiang , Wang Qing , Yue Caiyang , Zhang Wei , Zhang Han , Dai Yong
Published: March 2020

With the further promotion of the power system reform, the transmission and distribution price reform is in-depth, from “building mechanism” to “strong supervision”, and the effectiveness of investment has become the focus of supervision, so that grid enterprises must pay more attention to the efficiency and efficiency of investment. This paper mainly studies how to build a project cost analysis and data mining model based on the massive feasibility study estimate, preliminary design estimate and final account data of power grid infrastructure projects, mining the value laws and characteristics of power grid infrastructure projects from multiple scenes and perspectives, supporting the investment amount estimate in the planning stage, the investment estimate review in the feasibility study stage, and the investment control target prediction in the planning stage, so as to improve the investment efficiency of electric grid project.
Distributed Energy Storage Optimization Location Method Based on Improved Voltage Distribution
Authors: Zhu Haifeng , Tian Fangyuan , Li Yan , Deng Kai , Feng Yulong , Tang Xiaobo
Published: March 2020

Aiming at the problem of voltage overrun caused by large-scale distributed generation (DG) access to distribution network, a distributed energy storage optimization location method based on improved power quality is proposed. Firstly, the voltage governance mechanism of distributed energy storage access to distribution network with large-scale distributed generation is analyzed. Secondly, a distributed energy storage optimization site selection model is proposed, which can be solved in two stages: In the first stage, the power flow calculation is performed based on the typical time section, and the set of energy storage grid-connected nodes is determined by using the weighted voltage sensitivity. In the second stage, the distribution network voltage offset and active power loss optimization are taken as the objective functions. Each node in the set is selected as a parallel node for power flow calculation to determine the final grid-connected node by using the enumeration method. Finally, the improved IEEE33 node distribution network system is taken as an example to verify the correctness of the proposed model. The results of the example show that the distributed energy storage access can effectively support the voltage, and the proposed location model has good practicability.
Improved Droop Control Strategy of Energy Storage in Islanded Microgrid
Authors: Zhu Haifeng , Tian Fangyuan , Li Yan , Chen Xiao , Feng Yulong , Tang Xiaobo
Published: March 2020

In islanded AC microgrid, droop control strategy is usually adopted for independent distributed generators (DG) which can realize coordinated operation of each unit under the conditions of less data communication. For different capacity of energy storages (ES) system, due to the difference of SOC value, capacity and other state parameters, some units may reach the threshold quickly, thus affecting the system stability. Therefore, on the basis of traditional droop control, combined with the SOC value of energy storage unit, the droop curve which is automatically adjusted with the change of SOC value is constructed. At the same time, the bus voltage is corrected to run at a predetermined point through the voltage feedback link to eliminate the voltage fluctuation. Finally, a microgrid model with dual energy storage system is built inMatlab/Simulink simulation environment. Theresults show that the improved droop control method can make the SOC values of the two energy storages consistent.
Research on Releasing Plans of Power Generation and Power Utilization in China
Authors: Wu Zechen , Zhang Fan , Tang Chenghui , Xue Song
Published: March 2020

Chinese government intends to fully liberalize the power generation and utilization plans for operating power users. This paper analyzes the problems faced when power generation and utilization plans fully liberalized, that is priority electricity unbalance problem and power grid enterprises’ income problem. Then three schemes for priority generation and purchase matching as well as two schemes for price adjustment are proposed. After comparing the advantages and disadvantages of each schemes, we recommend the partly decoupling mode for priority generation and purchase matching, that is allocating priority purchase power to clean energy first, and sharing the shortfall to conventional units in proportion. We also recommend cost sharing mode for price adjustment, that is determining priority generation plans in advance, and calculating related costs in transmission and distribution prices for market-oriented users.
Study on characteristics and calculation method of VSC-HVDCshort circuit current under three-phase AC short circuit
Authors: Huo Qidi , Su Qingmei , Tang Xiaojun , Lu Yingquan , Huang Ting , Li Kewen , Huang Daoshan
Published: March 2020

VSC-HVDC has been widely used at home and abroad, but there is no clear conclusion about the characteristics and calculation method of the short-circuit current contributed by VSC-HVDC during the AC Short-Circuit Fault near the converter station. The calculation methods in the field of short-circuit current engineering have not been unified, and the adaptability and error of different methods have not been analyzed in detail. Through electromagnetic transient simulation, this paper analyzes the transient characteristics of VSC-HVDC contribution short-circuit current, and combs the key influencing factors of VSC-HVDC contribution short-circuit current. Finally, taking a VSC-HVDC system in China as an example, the adaptability of the commonly used short-circuit current algorithm is analyzed. It is verified that the existing engineering algorithms have made great progress compared with the original. However, compared with the electromagnetic transient refined simulation, there is still a large error in the calculation results of individual nodes under some control modes / fixed values.
Research and application of non-invasive intelligent power system
Authors: Feng Liu , Li Xiaolan , Jin Guanghua , Ji Guang , Fang Delong , Xu Xianglei
Published: March 2020

Most of the traditional intelligent power systems collect data information through sensors installed on the user’s equipment side, and then conduct intelligent operation, resulting in poor user experience. With the increase of all kinds of electrical equipment, the number of sensors to be installed is also increasing, resulting in waste of resources. It is an important direction of customer side service upgrading to build ubiquitous power Internet of things and explore a new type of intelligent power consumption mode that is customer-centric and market-oriented. Based on the requirements of the current Ubiquitous Power Internet of Things, this paper proposes a new mode of intelligent power system based on non-invasive load monitoring and identification technology. This new mode realizes diversified value-added services for power consumption, also, this mode is applied to the customization of user’s personalized business, precise management and control of power equipment, so as to enhance the user’s power consumption experience and build a market-oriented customer side business application has important application value.
Analysis of Load Characteristics Changes in the Case of Large-scale Electric Energy Substitution Load Connected-in
Authors: Li Zhuonan , Liu Jun , Jin Yanming
Published: March 2020

Global energy development trends and resource endowments determine that clean substitution and electric energy substitution will be important directions for the sustainable development of world energy. Electricity has the advantages of cleanness, safety, and convenience. The implementation of electric energy substitution is of great significance to promote the energy consumption revolution, implement the national energy strategy, and promote clean energy development. At present, many provincial and municipal governments are committed to promoting electrical energy substitution to complete the energy revolution on the consumer side, which has put the local power system to the test. In this paper, a load characteristic change model based on artificial bee colony algorithm for large-scale access of electric energy substitution load is established. In addition, the power load in a typical area is used as an example, and its load change is also calculated.
Framework for exploratory modeling of power system evolution
Authors: Wu Shengyu , Jiao Bingqi , Wang Shuhui
Published: March 2020

One of the challenges power system evolution research facing is deep uncertainties, which could not be described by Knightian uncertainty. This paper reviews three types of research methods involving power system evolutionary research, one is power system planning modeling, the other is complex network theory, and the third is exploratory modeling, of which exploratory modeling could handle with deep uncertainties. This paper combines the first and the third method, and proposes an exploratory modeling framework of power system evolution, which embeds the power planning model as the core to reflect the operating characteristics of the power system in the framework.
Development and Application of Lightweight Coring Drilling Rig in Tunnel
Authors: Fan Dong , Tian Hongliang , Wang Ruize
Published: March 2020

This paper introduces ZDY1200G lightweight underground drilling rig. The feeding device was designed with light alloy material and the deformation of the fuselage was measured by 3D DIC speckle deformation measurement. A high-speed gyrator with large through hole for hard rock coring was designed. A hydraulic system based on constant pressure variable displacement pump was developed, which included feed linkage and rotary linkage. The drilling rig has been applied in the Cangyuan lead-zinc mine in Yunnan Province. A rope coring drilling hole with 512.68 m depth and 76 mm diameter has been completed. The reliability and technological advancement of the whole set of equipment have been verified, which provided technical support for the exploration of the Cangyuan lead-zinc mine and also mining areas with similar conditions.
Research on Convergence of Artificial bee colony algorithm based on crossover and consistency distribution–good point set
Authors: Zhang Pinghua
Published: March 2020

A new artificial bee colony (ABC) algorithm based on crossover and consistency distribution–good point set is proposed. In the iterative search process, we use the consistency distribution and good point set principle of number theory to establish the initialization model of the algorithm, thereby ensuring the uniform distribution of the population in the search space. The location is updated iteratively to maintain the diversity of the population and prevent the algorithm from falling into the local optimum. Finally, the method that the artificial bee colony algorithm improved by consistency distribution-good point sets is proven and it conforms to Markov process from the point of view of number theory, thus proving the convergence of the algorithm.
Experimental study on permeability and expansion characte-ristics of expansive soil
Authors: Peng Kai , Li Xiaogang , Yang Ronghao , Liu Chong , He Hao
Published: March 2020

Expansive soil is used as a high-plastic clay, the bearing capacity is gradually attenuated due to the penetration of water, which greatly limits the application range of practical engineering. In this paper, the permeability and expansibility test of remolded soil and undisturbed soil in expansive soil were carried out. Ability coefficient of remolded soil and undisturbed soil under different overburden values was compared and analyzed. Overburden load, head height and water content were studied. The effect of the rate on the permeability coefficient of remolded soil and further analysis of the expansion and expansion forces at different initial moisture contents The results show that the permeability coefficient of remolded soil and undisturbed soil decreases with the increase of overlying load. As the water content increases, the permeability coefficient decreases first within a certain range. After reaching a certain level, the permeability coefficient gradually increases. As the initial water content increases, the amount of expansion progressive decreases and the expansion force progressive decreases.
Analysis on seismic behavior of different structural systems of small high-rise buildings
Authors: Luo Ruofan , Feng Zhuojun , Ouyang Zhiyong , Liu Yimei
Published: March 2020

In order to study the seismic performance of small high-rise building under different structural systems, an ordinary residential tower building of 11 floors in 7 degree area was designed as a frame structure, frame-shear wall structure and shear wall structure respectively. Elastic calculation of all structures was conducted based on FE model built by the software of YJK and elasto-plastic time-history analyses were conducted by the software of PERFORM-3D. The numerical results confirm that all of the three kinds of structure system can meet the requirement that the beam yield firstly, but vertical force component dose not yield in rare earthquake. On the frame-shear wall structure, the inter-story drift angle can be controlled better. The proportion of plastic energy dissipation of the frame structure is the highest and of the shear wall structure is the least among the three structures. All kinds of structure systems show good seismic behavior.
Rapid co-extraction of coal and coalbed methane techniques: a case study in Zhangji coal mine, China
Authors: Tang Bin , Tang Yongzhi , Wang Chuanbin , Li Yanqing , Yu Yan , Dai Mai , Wang Zhenhua
Published: March 2020

Coalbed methane (CBM) is one of elements of coal mine hazards, the high CBM content and low permeability coefficients of coal seams in Huainan coal filed result in high difficulty of coal exploitation and CBM drainage, and the potential risk of gas explosion and combustion. The CBM drainage works are time-consuming and they typically delay the coal mining operations. A set of novel techniques of rapid co-extraction of coal and CBM are proposed in this paper. In the practice of 1413A longwall panel of Zhangji coal mine, a set of overlying and underlying drainage galleries were replaced by two overlying drainage galleries which were excavated by TBM, thereby the stress of excavation works was reduced. The pre-drainage and roadway excavation are conducted simultaneously and the overlying drainage gallery can also be used for post-drainage purposes. The bolter miners and automatic or remote control of longwall mining have also been used in the practice. The 1413A longwall extracted 2.31 million tons of coal and 15.02 m3 of CBM with the extraction rates of 93.5% and 63.8% respectively in 448 days. The speed and efficiency of co-extraction operations were improved significantly.
Research on gas leakage mechanism and detection technology of coal mine gas drainage
Authors: Ba Quanbin
Published: March 2020

Aiming at the low concentration of gas in the percolation borehole, the paper analyzes the mechanism of gas leakage in the sealing hole of the pumping hole based on the multi-physics coupling theory based on the distribution of the surrounding rock stress field of the mining borehole and the roadway. The drilling hole sealing detection device and the determination method are used to detect gas concentration at different depths in the borehole in the normal extraction state, and analyze the variation law of the gas drainage concentration along the hole depth distribution to achieve fast and accurate judgment of the leak position and sealing test of the pumping hole. The test proves that the method and the device can effectively detect the leaking position and sealing effect of the extraction drilling hole, and can provide a simple and rapid detection method and science for the improvement of the sealing process, the adjustment of the sealing depth and the fine management of the coal mine site.
Study on the law of artificial crack propagation and fracturing technology in strong heterogeneous conglomerate strata: a case study of the Mahu glutenite in Xinjiang Oilfield
Authors: Duan Guifu , Tian Gang , Guo Dingfei , Zhang Jingchen , He Chunming , Yu Huiyong , Chen Jin
Published: March 2020

The glutenite reservoir of the Triassic Baikouquan Formation in the Mahu sag with a large amount of resources, is the main block for Xinjiang oilfields and even domestic oil production in recent years. The reservoir is characterized by deeper burial, fewer natural cracks, low fluidity, high pressure coefficient, high horizontal stress difference and special lithology. For these geological problems, researches on fracture extension law, proppant placement law and fracturing technology have been developed to form an integrated volume fracturing technology of heterogeneous glutenite geological engineering. The contributions are as follows:(1) The lithofacies reservoir in Mahu includes matrix support, particle support and mixed support, which makes the conglomerate reservoir have large differences in many respects. The mechanical parameters of granular-supported conglomerate are higher than those of complex-base-supported conglomerate, and the brittleness index is higher.(2) Fracture regularity of glutenite varies greatly at different scales. As the ratio of fracture size to gravel size enlarges gradually, the influence of gravel on fracture extension weakens.(3) The fracture roughness of glutenite has great influence on fluid flow and proppant migration. The sand-laden fluid flows by fingering in small fracture. The crack with larger width is the dominant flow channel and will influence proppant placement.
Establishment and Application of Sand Prediction Model Based on Monte Carlo Method in Offshore Oil-gas Field
Authors: He Hanping , Guo Fang , Liu Liming , Li Menggang , Wang Xin
Published: March 2020

Accurate assessment of reservoir sanding risk is a key link in the optimization design of offshore oil-gas fields. Based on the Monte Carlo risk probability assessment method, three factors affecting sand production, such as rock Poisson’s ratio, rock density and acoustic time difference, are considered. At the same time, combined with the existing sand production index prediction theory, the probability distribution calculation model of sand risk is established and analyzed. The established prediction model is used to analyze the sand production case. The model was combined with the logging data and seismic data of some layers in Oilfield HZ 32-5 to form the probability distribution map of the sand production index of the J22, J50 and K08 horizons in HZ 32-5 Oilfield. The probability of different sand production levels of the three reservoir rock horizons is predicted, and the corresponding sand control risk prevention and control plan is formulated. Through the on-site application of HZ 32-5 Oilfield, it is proved that the model can more accurately assess the sand production risk in offshore oilfields, and has a good guiding significance for the design of oil-gas well completion schemes.
Research on Support Type Selection of Foundation Pit of Rail Transit Station Based on Improved AHP Method
Authors: Liu Yan , Lu Linhai , Liu Junyan , Zhao Jianjun
Published: March 2020

With the rapid development of underground space, a large number of complex foundation pit projects have emerged. It is undoubtedly an important task to select a safe, economic, scientific and reasonable support scheme and seek a scientific and reasonable optimization method of foundation pit support scheme in combination with regional characteristics. This paper tries to find a simple and practical method of scheme selection which meets people’s psychological comparison scale. The traditional analytic hierarchy process (AHP) is improved, the grade of traditional evaluation index is improved, and the index scale is introduced. An analytic hierarchy process based on the seven grade index scale is put forward to make it more suitable for people’s psychological comparison scale. Through consistency test, the scientificity and rationality of the improved layer analysis method are verified, and applied to the foundation pit engineering with close proximity to rail transit. Through the establishment of the tomographic structure model and judgment matrix, the calculation and optimization are carried out. It is found that the support scheme of diaphragm wall + internal support is the optimal scheme of the project. This method can provide theoretical support for the establishment of regional foundation pit support selection.
Study on stress distribution under pillar floor of room in Potash mine with room and pillarmining technology
Authors: Chen Mingcheng
Published: March 2020

Room and pillar mining is a traditional mining method in the world. Carnallite/potash salt is easy to absorb water and has a strong cohesive force, its physical and mechanical properties are completely different from those of coal. The span of the room and pillar in the potash mine is small, generally ranging from 8 to 15m. Taking a solid potash mine in Laos as engineering background, basing on the elastic semi-infinite space theory, this paper sets up the mechanical model of room and pillar mining, adopts Flamant and Boussinesq solution under linear load to make research on the additional stress caused by mining in the transmission, distribution and impact depth of floor. The results indicate that depth 6 m under pillar bottom, the σz at various points is around 0.1 p. If 0.1p is used as the judgment basis for the critical impact depth of additional stress, it can be considered that the impact depth of stress concentration on bottom plate caused by mining is about 6b.
Study on the Performance of Foundation Pit Supporting System Considering the Process of Anchor Recycling
Authors: Zheng Quanming , Liu Yan , He Donglin , Zhang Xiwen
Published: March 2020

The technology of recoverable anchors / cable greatly avoids the disadvantage of traditional anchors / cable, such as non-recyclable, waste of resources and occupy underground space. However, there are many problems existed in the development, design and application processes. Taking a foundation pit project in the city of Jinan as an example, the numerical analysis of the whole construction processes was conducted to study the mechanical behaviour of supporting systems. It is found that the supporting pile has major deformation during the excavation and anchors recycle. For the process of anchor recycle, the bending form of supporting pile transformed from outward to inward. Moreover, the horizontal displacement of pile top increased by 21.4%. The axial force of upper anchor increased during the recycle of lower anchor, for example, the axial force of uppermost anchor increased by 21.3% comparing to the state that no anchor was recycled. Therefore, for the real project of anchor recycling, the internal force redistribution and deformation property of supporting system should be fully considered, to avoid the influence to the surrounding buildings and the foundation pit itself.
Analysis of the Influence of Boundary Conditions on the Mechanical Characteristics of Arch Bridge with Composite Arch
Authors: Li Changchang , Wu Ling-Ling , Chai Shengbo , Zhao Yu , Zhou Yong-Jun
Published: March 2020

Mid-through arch bridge with a composite arch rib of the main arch and vice-arch is novel and reliable in rigidity. It belongs to the high-order statically indeterminate structures, and the boundary form has a great influence on the internal force and deflection of the structure. In this paper, in order to study the influence of different boundary conditions on the static and dynamic characteristics of the structure, relying on a practical project, the static and dynamic characteristics of the bridge under different boundary conditions of the main arch foot are analyzed and compared by using finite element method, which provides scientific basis for the design of the arch bridge with composite arch. The results show that the boundary conditions of the main arch foot have obvious effects on the deflection and internal force of the arch under dead and moving loads, but have little effect on the dynamic characteristics and stability of the bridge.
Girder Lattice Model and Single Beam Model In Load Test of Continuous Box Bridge Computational Comparison and Analysis
Authors: Gui Peng , Su Shengjiang , Peng Cheng , Qi Wei
Published: March 2020

The static load test of a three-span continuous box girder in Huzhou City, Zhejiang Province is analyzed and calculated by using the grillage method and the single main girder method. The rationality of the two calculation models is compared with the field load test data. The calculation results show that the results of grillage method are more consistent with the experimental results than that of single girder method, and the safety of the calculation results is higher. Therefore, in the load test of multi-compartment box girder bridge, the grillage method is more reasonable and can better reflect the mechanical characteristics of the bridge structure.
Science mapping approach to assisting the review of mine water disaster prediction and evaluation in China between 2009 and 2019
Authors: Liu Beizhan , Feng Rao , Liu Anqiang , Dong Lihong
Published: March 2020

Mine water inrush occurs frequently in China, and it can cause serious economic losses and heavy casualties. Thus, it is very important to realize risk assessment of mine water inrush. After collecting 4082 journal documents on risk assessment of mine water inrush from 2009 to 2019 in CNKI journal database, and using CiteSpace visualization software to do data analysis, the research hotspot and frontier trend in mine water inrush research in China are obtai ned. The prevention and prediction of different types of water disasters is a major trend in this field.
Construction and Application of Groundwater Environmental Health Assessment Model Based on Entropy Weight and Fuzzy Matter Element
Authors: Wang Feng , Xu Zhenghe , Pan Weiyan , Zhang Shanshan
Published: March 2020

Groundwater overdraft has become a major challenge, most serious in northwestern and northern China. A series of environmental geological problems caused by groundwater overdraft will be more extreme, which restrict the development of society. In this study, matter-element theory is introduced. Moreover, a matter-element evaluation model is established, and a matter-element evaluation algorithm based on fuzzy entropy weight is proposed. The algorithm takes nature, environment, economy and society as the characteristic indexes of the evaluation category. Four kinds of typical regions were chosen including Core Economic Zone (A), Bearing Industry and Trade Economic Zone (B), Agricultural Machinery and Trade Economic Zone (C) and Ecological Agricultural Economic Zone (D) as the study region. The risk assessment of groundwater is evaluated using the groundwater environmental health assessment model in this study. The results showed that the constructed model can be used for the assessment of environment health of groundwater successfully. The simulation results showed that the groundwater was in a medium health state in Linqing City. The results showed that groundwater environment of ‘healthy’ state of nearness concentrated between 0.2 and 0.4. The descending order for typical regions groundwater environment ‘healthy’ state of nearness from high to low are B, D, A, and C.
Adptive Multi-scale Finite Element Considering Local Buckling of Members for Latticed Frames
Authors: Liu Haifeng , Wang Changzhi , Hu Xiaoguang
Published: March 2020

To consider the local buckling of the members in the reticulated frames, based on the multi-scale simulation, the part of member that having local buckling is divided by the shell elements as a micro-model, and the other part of the member was simulated by beam elements as a macro-model. The incremental displacement constraint equations for the nodes on the section between the two models are established based on the plane section premise of classical beam theory. A method to introduce the constraint equations is derived based on the Updated Largrangian method. The location of the micro-model is predicted by the deflection function of the beam, and the length of the collapsed part is estimated. Its accuracy proves to be satisfied by the pure shell element model.
Recovery Characteristics of Weak Alkali ASP Flooding in Second Oil Reservoir
Authors: Huang Mei
Published: March 2020

Taking two weak alkali ASP flooding test blocks as the research object, the injection-production characteristics, effective characteristics, agent recovery characteristics, reservoir inhalation condition, pressure characteristics and emulsification characteristics were analyzed. The results showed that the weak alkali ASP flooding had strong injection-production ability, high oil recovery rate, improved suction condition, established effective driving pressure system, obvious emulsification, and not serious chromatographic separation. The apparent inhalation index decreased by 23%-33%, and the liquid production index decreased by 31-42%; The inhalation thickness ratio were 89.5%-92.7%, and the water cut decreased by 16%-20%; The enhanced recovery increased by over 20% in the weak alkali ASP flooding of the second oil reservoir.
Summary of surface information extraction based on remote sensing technology
Authors: Bin Liang , Lei Tian , Sili Shen , Likai Jia
Published: March 2020

Man machine interactive remote sensing interpretation method of satellite image is an important means to understand the basic situation of land background and human interference activities. This paper briefly summarizes the remote sensing interpretation methods and the information extraction experience of different spatial resolution data in different research areas.
Study on Formula of Retarded Acid for Acidizing and Blocking of Coalbed Methane Wells
Authors: Zhen Huanbin , Zhang Shuling , Chen Shuai , Chen Gaojie , Bian Liheng
Published: March 2020

Acid plugging removal technology is an effective measure to remove the pollution in the near-well zone of oil and gas reservoirs and restore the productivity of oil and gas wells. It is to use the chemical dissolution of acid solution to dissolve formation plugs, expand or extend formation fractures and holes, so as to restore and improve formation permeability, reduce oil inflow resistance or water injection resistance, thus achieving the purpose of increasing oil well production and water injection. Therefore, the acid formula is particularly important. The commonly used acid formula is the soil acid formula. However, due to the shortcomings of the Soil Acid Formula itself, as well as higher safety risks and construction costs, this paper has studied a new acid formula. X-ray diffraction analysis was carried out on the experimental slime samples from 8 wells in Linfen block of Shanxi province, and it was found that the main mineral composition of the blockage was a mineral that can react with acid. The dissolution rate and corrosion rate of the blockage were tested with Southwest Solid Acid and Soil Acid Formula. The advantages and usability of Southwest Solid Acid were found by comparing the experimental results. Through a large number of experiments, the formula of retarded acid liquor with excellent performance, economy and effectiveness has been selected.
Development technology status of low permeability sandstone oil reservoirs
Authors: Liu Xuefen , Li Jianfeng
Published: March 2020

The development of oil in low permeability sand stone resources is of great significance. The paper first presented the present situation of domestic and foreign technologies in water injection, gas injection, stimulation and enhanced oil recovery of low permeability sandstone reservoirs. Then the main problem in the development of oil reservoirs with ultra-low permeability was analyzed. Finally, the paper proposed the trend of the future development of these oil reservoirs.
Development of Portable Shallow Hole Inclinometer in Coal Mine
Authors: Long Chen , Jiaru Yang
Published: March 2020

Due to the special requirements of borehole measurement work in coal mines, in this paper, a portable shallowhole inclinometer is developed in response to the current situation of shallow borehole trajectory measurement relying on the pushing of drilling machine. This instrument is mainly composed by three parts of inclinometerprobe tubes, orifice display controllers, and conveying rods. The probe tube can be used to measure the attitude parameters such as the inclination, azimuth and tool facing angle of the borehole, and the orifice display controller works synchronously and records the drilling depth and measuring time.Finally, the track of the current borehole can be displayed in the mine. The test results show that the instrument is stable, reliable, and practical.
Optimization Design Analysis of Large Span Cantilevered Cross Bracing Truss of Tai’an Tourism Distribution Center
Authors: Jiao Hong , Liu Xiaohan
Published: March 2020

The main structure of Tai’an Tourism Distribution Center is a steel frame structure system. On its west side, there is a large span cantilever structure with a maximum cantilever length of 22 meters, which adopts a space steel truss structure. The cantilever structure has great visual impact and excellent ornamental value, but it also has irregular items such as irregular torsion, irregular vertical lateral stiffness, and sudden change of floor bearing capacity. The overall stress of the structure is complex, and the design and construction of seismic performance are highly required. The seismic performance of the structure is calculated and analyzed by performance-based seismic design method, and the cantilever structure is modeled and analyzed by 3D3S, a space steel structure design software. The results show that cross support is more reasonable for cantilever structure. In view of the difficulties in the design analysis, this paper also proposes effective strengthening measures to ensure the safety of the structure, and makes technical reserves for later construction of the project, which is also of certain reference significance for similar projects.
Design of Electromagnetic Wave Resistivity Logging Toolfor Underground Coal Mine
Authors: Jiguan Zhang
Published: March 2020

Electromagnetic wave resistivity logging is an important method in oil logging, but it has not been applied in underground coal mine due to special working conditions and explosion-proof requirements. In this paper, through theoretical analysis and simulation, an electromagnetic wave resistivity logging tool is designed, which is suitable for underground coal mine. The detection of amplitude ratio and phase difference of weak signal is realized, and its performance index meets the actual working conditions.
Finite Element Analysis on the Influence of the Change of Characteristic Parameters of Brake Pad on Structural Modal
Authors: Li Da , Zheng Zhongcai , Gao Yan , Shan Ping , Luo Wei , Liu Fengliang , Han Dongyue , Zhang Yifan , Lv Qiaoya
Published: March 2020

The modal coupling of disc brake disc and brake pad is one of the main causes of brake noise, so the structural modal of the disc and brake pad is very important for the research of brake noise. In this paper, finite element theory is used to analyze the influence of the characteristic parameters of the brake pad on the structural modal. We use modal analysis to calculate the modal frequency and modal shape of the brake pad that has the different thickness, the depth and width of the groove, and the chamfer. According to the simulation results, the thickness of the brake pad, thegroove depth of the brake pad, the groove depth of the brake pad and the size of the brake pad chamfer all have influence on the modal characteristics of the brake pad structure, especially, the thickness of the brake pad has the greatest influence.Therefore, changing the thickness of the brake pad and the depth of the brake pad groove can be a potential way to reduce the brake noise of disc brakes.