bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of creep process of marine concrete
Authors: Sun Naidong , Yang Lingqiang , Liu Xiangxin
Published: March 2020

The use of marine concrete is increasingly common with the rapid development of marine economy. The corrosion and fracture of concrete in marine building structures are relatively serious, due to the strong corrosiveness of sodium and chlorine ions in seawater. Therefore, it is of great significance to study the creep laws of concrete in marine environment. A marine concrete pier is taken as the analysis object, and the elastic theory and concrete creep theory are combined to build a model of that. The creep curves of concrete in marine environment are obtained by using finite element method, and it can be compared with the creep curves of ordinary concrete in theoretical analysis. The results show that the stress relaxation of marine concrete is greater and the stress state is more unstable than that of ordinary concrete under the same conditions. The time for marine concrete to reach the same stress state is about 6-9 years earlier than that of concrete in normal environment. In addition, it takes a longer time for the stress state of marine concrete to tend to be stable.
Study on utilization access control mechanism of resources in geological cloud environment
Authors: Zhang Qine , Zhao Jinhui
Published: March 2020

In order to solve the problem in access control of open geological cloud resources, from the view of usage an access control model was proposed based on trust and role. Firstly, geological cloud resources were divided into five categories according to the actual usage of geological cloud resource, and the access control needs of various resources were analyzed in detail. Secondly, a layered access control model of geological cloud resource was designed, in which the access control process was defined and the evaluation method of user trust based on set pair analysis was given. Finally, the results and safety analysis showed the rationality and validity of proposed model.
Comparative Analysis on Artificial Freezing Design Scheme of Vertical Underground Garage
Authors: Zhang Ji-Wei , Song Zhang , Liu Shu-Jie , Hua Wang
Published: March 2020

Based on 7m length×7m weight×50m depth vertical underground garage of old residence communities in Shanghai China, the new article ground freezing (AGF) method— Box-frozen method was studied. The elastic theory calculation and numerical simulation showed that the thickness of straight (hq
) and bottom (hd
) frozen wall are 2.8m and 10m respectively, which can meet load bearing and water insulation requirements. Three artificial freezing design schemes and parameters were proposed according to different freezing hole layout, namely, 1) double row holes and cutting bottom holes;2) double row holes and leave bottom holes;3) single row holes and leave bottom holes. Evolution law of temperature field of different Box-frozen design schemes was checked by numerical simulation. The results showed that, during maintenance freezing period, both of double row holes and cutting bottom holes and single row holes and leave bottom holes schemes appear thaw phenomenon at bottom of frozen wall while double row holes and leave bottom holes stops thaw tendency basically. Three Schemes are compared in four aspects including construction period, cost, excavation difficulty and risks, which prove that double row holes and leave bottom holes scheme are a most suitable article ground freezing method due to less construction period and low risk.
Numerical Study of TBM Excavated Coal Mine Roadway Support Design
Authors: Tang Bin , Wang Zhenhua , Tang Yongzhi , Wang Chuanbin , Li Yanqing , Yu Yan , Dai Mai
Published: March 2020

In TBM excavation projects of Zhangji coal mine which is the first application of TBM at deep underground coal mine, computational modelling was conducted in surrounding rock stability study and support design of coal mine TBM excavated roadway due to lack of experience in similar projects. This paper presents a support design methodology of TBM excavated roadway at deep underground coal mine. A three-dimension finite element model was established, and the non-uniform tectonic stress filed was also been simulated in the model. Stress redistribution, displacement and plastic zone range of surrounding rock under different support patterns were analyzed and support design of the roadway was made on the base of simulation results. During roadway excavation, instrument rock bolts were installed for monitoring stress distribution and roadway convergence. The monitoring results suggest that computational simulation results correspond with in-situ monitoring data, horizontal stress concentrates on the roof and floor of roadway and vertical stress concentrates on lateral sides. The roadway convergence increased significantly after excavation and then slowed down and finally stopped after 40 days.
Improved population initialization method and its application in bridge optimization
Authors: Yang Ronghao , Zhao Yunpeng , Si Haipeng , Li Zhigang , Wang Ruizheng , Peng Kai
Published: March 2020

When solving bridge optimization problems by traditional genetic algorithms, a random method is often used to generate the initial population, which can’t ensure that the initial population is evenly distributed in the solution space and reasonably represents the solution space. In order to solve the shortcomings of random method, an improved population initialization method is proposed by combining random method with good point set. Based on it, aimed at the characteristic of implicit non-linear objective function or constraint function in bridge structure optimization, a BP neural network is used to simulate the relations between the objective function or constraint function and design variables. Then this paper takes a steel truss bridge as an example of optimization. Taken the allowable deflection of bridges as limit and aiming at minimizing the amount of steel, optimization model of bridge is established. Finally, the improved population initialization method is applied to solve the optimization model. The results show that the improved population initialization method can not only improve the uniformity of the population, but also be suitable for optimization design of bridges.
Optimal Sensor Arrangement for Cable-Stayed Bridge Based on Multiple Algorithms
Authors: Liang Jianjun , Peng Kai , Li Kai
Published: March 2020

The arrangement of sensors is one of the key points in health monitoring of long-span bridge structures. In this paper, eight algorithms are applied to the optimal sensor arrangement of a long-span cable-stayed bridge and compared. Firstly, eight algorithms and four criteria are introduced, then eight algorithms are applied to optimize the layout scheme, finally, four criteria are used to evaluate the algorithms comprehensively according to the same weight. The results show that in the optimal arrangement of sensor measuring points, it is necessary to combine the engineering practice, comprehensively consider the weight ratio of different criteria, and choose the best optimization scheme.
Analysis of Linear Influence of Long-span PC Continuous Rigid Frame Bridge during The Winter Break
Authors: Li Zhigang , Song Yifang , Zhao Yunpeng
Published: March 2020

In the construction of large-span PC continuous rigid frame bridges, linear changes occur during the winter. In order to study the influence of the girder linear change on the monitoring line shape of the bridge, the actual bridge under construction was selected as the research object. Based on the finite element analysis software combined with the measured deformation data of bridges, the main influencing factors of the main beam linear deformation during the winter break are analyzed. When the latest construction section of the cantilevered beam is untensioned and retains the beam-end hanging basket to enter the cantilever wintering stage, the final analysis results show that the linear deformation of the main beam during the period of the winter break is as follows. When the length of cantilevered beam is less than 13L/32, the linear deformation of the cantilevered main beam during the winter break period has a little influence on bridge alignment; when the length of the cantilevered main beam exceeds 13L/32, the girder will gradually produce the downward deflection during the winter break. In order to avoid the continuous downward deflection of the main beam during the winter, the prestressed reinforcement of the latest construction section need to be tensioned to reduce the amount of deflection of the main beam during the winter break.
Design of Drilling Turbine Generator under Coalmine Well
Authors: Zhang Jiguan , Chen Long , Gao Jun
Published: March 2020

Aiming at solving the problem of low endurance of detection instruments under coalmine well, a turbine generator, which relied on water drive to generate electricity in drilling, was designed based on the explosion-proof requirements of coal mine equipment. The generator structure, turbine structure, overall structure and circuit design of the turbine generator were discussed in detail. By setting up the test platform, the speed of the prototype and the driving performance of the water flow were tested. The test data shows that the prototype accords with the design goal and it can meet the requirements of underground drilling detection instrument in coal mine.
Bridge Technology Condition Degradation Prediction Based on Bayes Dynamic Model
Authors: Zhao Xiangyu , Zhang Yang
Published: March 2020

Establishing appropriate degradation model of bridge performance is the precondition of preventive maintenance. A Bayes dynamic model is proposed to predict the future performance of bridge. Bayes factor is used to evaluate whether the prediction mode is reasonable. The Bayes factors of Bayes dynamic models are tested through practical engineering. The results show that the Bayes dynamic model is fit for the bridge technology condition degradation prediction.
Parametric Analysis and Research on Full-range Mechanical Behavior of Curved Twin-I Girder Composite Bridges
Authors: Han Xiaodong , Song Yifan , Shen Chuandong , Gong Xiangjian , Liu Manhui
Published: March 2020

In order to further study the full-range mechanical behavior of the curved and small-and-medium span twin-I steel girder composite bridges, the combination of experimental verification and numerical analysis was used to study the stability safety at construction stage and ultimate strength at finished stage of the curved continuous composite beam of 35m standard span. Firstly, using the experimental data in the literature, the ABAQUS nonlinear numerical model was verified from the aspects of failure load and mid-span deflection. Secondly, the stability safety factor and the ultimate live load coefficient were used as indicators to compare and evaluate the mechanical performance of the full bridge structure with different spans and different curvature radius. The results show that the stability safety of three-span bridge improved obviously compared with the simply supported beam, but ultimate strength of bridges with different spans is similar at finished step. The stability safety and ultimate bearing capacity increased with the increase of the radius during the whole process. When the curvature radius is greater than 460m, the bearing capacity is significantly improved. According to the difference of live load coefficient of inner and outer curved girder, the design could be referred to different inner and outer girder height.
Numerical Simulation of the Influence of Cutting Slope Rate on the Stability of Highway Slope in Loess Area
Authors: Song Pei Yuan , Mao Yan Long , Huang Heng Xing
Published: March 2020

The highway project in the loess area of northern Shaanxi is to balance the earthwork and save costs, and a large number of excavation slopes are set. In the loess area, the soil is soft. If there is a structural surface, it is easy to cause damage to the airspace, causing huge losses to highway construction and transportation on the heavy rain and other working conditions, especially the roadside slope. Taking the high loess slope of a section of Zhidan-Nanliang Red Tourism Highway as an example, the indoor parameters are used to determine the appropriate parameters. The Midas-GTS NX strength reduction method is used to analyze the slope stability under different slope cutting rates.
Study on Underpinning Scheme of Shield Tunnel Crossing Pile Foundation of Viaduct
Authors: Zhang Liangliang , Liu Yan , Wang Yidi
Published: March 2020

With the increasingly dense distribution of urban metro network, it will inevitably lead to the problem of intersection between metro line and existing Viaduct Pile foundation. In order to ensure the normal operation of viaduct and complete the construction task of Metro at the same time, pile underpinning technology has been successfully applied to such projects. On the basis of theoretical analysis and relying on the ramp of Jinan Metro Line R2 production station to Lihuang station, this paper carries out numerical simulation of underpinning construction and tunnel underpass through finite element software, studies the deformation law of underpinning structure, determines the engineering risk points, and verifies the underpinning scheme to be adopted. The results show that the overall settlement of underpinning structure and the horizontal deformation of pile body presents “bow” shape. The structural deformation is mainly affected by underpinning construction, and the deformation of underpinning beam and the top of pile is the largest. The influence area of the surface is 4 m outside the underpinning beam. The above deformations meet the requirements of the code, that is, the scheme of manual piling. And the process of pre jacking up→ chisel pile→construction of underpinning beam and pile cap→passage of shield machine are safe and feasible.
Design method and detailing requirements of a new type of fully assembled beam-column joints
Authors: Zhai Wei , Jiang Wen , Yang Jinhu , Yang Junfen , Qu Kai , Chen Lei
Published: March 2020

With the innovation of steel structural joints, requirements for the reasonable design methods tend to be intensified to guarantee the effectiveness of joints’ working performance. To provide a certain reference for the design of assembled joints, related checking calculation methods and detailing requirements of a new type of fully assembled beam-column joints are given based on experimental phenomenon and according to related standards.
Study on seismic performance of high pier multi-span beam bridge
Authors: Liu Manhui , Han Xiaodong , He Yiyang , Li Zhigang , Niu Zhe , Li Zihao
Published: March 2020

Girder bridge with high piers has obvious advantages in crossing deep gorges, and is commonly applied to highway construction in the western mountainous area of China. In Qinghai province, the earthquake response is very complicated, and the seismic design is absolutely necessary. In this paper, the seismic performance of the typical span of a high-pier-girder bridge in seismic zone of Qinghai province is analyzed by the time-history analysis method based on the existing seismic design code. The seismic response characteristics and development rules of the bridge are obtained, and the methods to effectively improve the integrating stiffness and seismic performance of the bridge are discussed. The results can provide references for the seismic design of the same kind of bridges.
Layout research of settling slurry velocity distribution in vertical pipeline
Authors: Tieli Wang
Published: March 2020

Based on the research results of slurries, the author sets out from momentum transfer, and analyses the momentum change of liquid and solid particle, and puts forward calculation model of settling slurry velocity distribution, liquid velocity distribution and solids particle velocity distribution in vertical pipeline. The vertical slurry experiment has been done to obtain the data about slurry velocity distribution, liquid velocity distribution and solids particle velocity distribution. At last simple verification has been made for the calculation model which has been put forward, and it is proved that the prediction value of the author’s model is accurate.
Checking and Optimum Design of Damping Hole in Lubricating Oil Circuit of DCT Complex Valve Body
Authors: Wang Li , Qin Yiwei
Published: March 2020

The complex hydraulic valve body in the DCT is an important controlling and influencing factor to realize the function of dual clutch transmission. This paper took a damping hole in the cooling lubricating oil circuit of DCT as the research object, analyzed the flow field of the oil circuit based on the modeling software of CATIA and Fluent, discussed the influence of the size of the damping hole on pressure establishment of the complex valve body related oil circuit, checked the structural design of damping hole in lubricating oil circuit, and proposed the scheme and method of structure optimization. The analysis results after optimization reached the expected inlet pressure of the damping hole, which proved the rationality of the optimized structure.
Application of acidification parameter optimization method
Authors: Liu Qilun , Cao Jiefeng , Long Changjun , Zeng Zhiguo , Liu Wenge , Zhang Yingying , Su Dandan , Zhang Xu , Jia Jiangfen , Huang Bohua
Published: March 2020

The acidification technology is an important measure to increase the production and increase the injection of oil and water wells. However, due to the complicated working conditions of the acidification measures and the difficulty in determining the construction parameters, it is necessary to establish the acidification model of the injection wells and optimize the parameters. The paper uses the grey correlation analysis method to find the correlation between each construction parameter and the daily injection volume of the injection well, establishes the BP neural network program, trains it according to the existing data and predicts the artificial controllable parameters in turn to find the best construction parameter combination. Taking a single well as an example to predict the parameters and guide the on-site construction. The results show that combining the mathematical method with the acidification construction technology of the injection well and establishing the model prediction parameters can significantly improve the injection efficiency of the injection well.
Optimization calculation method and weighing test of static friction coefficient of RPC spherical joint based on half space contact model
Authors: Liang Jianjun , Lei Song , Li Kai
Published: March 2020

The application of new concrete materials in bridge engineering has always been a research direction of bridge scholars. Reactive powder concrete (RPC) has attracted many scholars’ attention in recent years due to its high strength, high toughness and high durability. But when it is applied to the spherical hinge in the bridge turning project, the result of static friction coefficient of RPC composite spherical hinge obtained by traditional calculation method is small. It may lead to the danger of overturning of the structure during the actual turning. For this reason, a more accurate method for calculating the static friction coefficient of this new type of spherical joint is needed. In this paper, we presented and verified a new stress distribution law and function expression of the friction surface of the spherical hinge, which was based on the contact model of half space body, combined with finite element analysis, weighing test and field measurement. This paper then proposes an optimized method for calculating the static friction coefficient of spherical joints. The results show that: The static friction coefficient of the spherical hinge obtained by the traditional calculation method is about 67% smaller than the actual static friction coefficient; The static friction coefficient of spherical hinge is 15.2% larger than that of the actual one, which is more accurate than that of the traditional method. If there is no test data, the static friction coefficient of this kind of RPC concrete composite spherical hinge is recommended to be between 0.03 and 0.06.
Discussion on harmless treatment technologies of drilling fluid waste in oil and gas fields
Authors: Wang Yandong , Wang Tengfei , Yan Xiangyang
Published: March 2020

Drilling fluid waste is the multiphase stable suspension composed of clay, drilling cuttings, weighting materials, chemical additives, inorganic salts and oil, containing a variety of substances harmful to the environment, such as oil, chemical additives, heavy metals and macromolecule organic compound. The effects of drilling fluid waste on the environment is mainly reflected in following aspects: pollution of surface water and groundwater resources; hardening of soil is harmful to plant growth or even unable to grow, resulting in the soil can not be replanted; various heavy metals and chemical additives affect the growth of animals and plants, and even are enriched in animals and plants, thus endangering human health. It is unfavourable to the implementation of the strategic objective of sustainable development of the environment and economy, so the drilling fluid should be treated innocuously after drilling.
Research and Application of Optimal Water Resources Allocation Based on Improved Multi-dimensional Dynamic Programming
Authors: Cheng Jianhua , Shi Hansheng , Zhang Yan , Zhang Muchuan
Published: March 2020

To solve the problem of the multi-dimensional dynamic programming model which including three state variables and three decision variables in each stage, we have been using discrete differential dynamic programming (DDDP) algorithm. In this paper, considering the particularity of each variable of the objective function is independent in the same stage and the variables of the constraint condition is increasing step by step, we propose a one-dimensional dynamic programming recursive optimization method to obtain the initial solution of the DDDP algorithm.
Study on vortex-induced vibration of non-uniform flow riser based on fluid-solid coupling
Authors: Lin Tiejun , Bao Xiaomin , Zhou Xu , Zuo Jinju , Mou Yisheng
Published: March 2020

Because marine riser is under complex ocean current environment, fatigue damage tends to happen due to vortex-induced vibration, which has a strong impact on the safety issue of deepwater drilling and completion. Vortex-induced vibration (VLV) induced by non-uniform flow loads on deep water riser coupling in complex Marine environments has been studied relatively infrequently at home and abroad. Therefore, CFD-FEM bidirectional fluid-solid coupling method was used to establish a vortex-induced vibration model of 1500m deep water riser and non-uniform flow in waves and currents. Vortex-induced vibration and mechanical behavior of riser in transverse and flow direction were studied from riser motion characteristics, tension factors and other aspects. The results show that the danger zone of vortex-induced vibration of riser under the action of non-uniform flow occurs in one third of the upper end. Increasing the tension can increase the riser’s natural frequency and reduce the amplitude of vortex-induced vibration, but may aggravate the riser’s high stress and low cycle fatigue damage.
Discussion on optimization design method for sidetracking wells in Bohai Oilfield
Authors: Wang Zhanling , Wang Xin , Liu Liming , Chen Liqiang , Tan Caiyuan , Guo Fang
Published: March 2020

Sidetracking of inefficient wells in Bohai Oilfield is one of the important means to stabilize production and increase production. Optimizing the sidetracking scheme to achieve cost reduction and efficiency enhancement is the research focus of refined sidetracking well design. In this paper, the theory of sidetracking technologies is introduced and optimization of sidetracking place is gived based on the location match of the low-efficient well and the sidetracking well and sidetracking plans in deep and shallow strata is identified. To aim at the shallow sidetracking scheme, The applicable conditions and difficulties are proposed in different cases for reentry technology of marine riser, sidetracking under insulator shoes, surface casing windowing sidetracking, sidetracking under surface casing shoes. Aiming at the deep sidetracking scheme, the optimal flow of the casing sidetracking scheme and sidetracking under production casing shoes is proposed. Taking two low-efficiency wells of A and B in Bohai as an example, the preferred slot and the sidetracking section are preferred, and the sidetracking point is preferred. Finally, the sidetracking location of the two wells is interchanged, and the footage is saved at 1428m. The on-site implementation results show that the two low-efficiency well sidetracking schemes are reasonable and can achieve the purpose of cost reduction and efficiency enhancement. The optimal method of low-efficiency well sidetracking proposed in this paper has certain guiding significance for the sidetracking design of low-efficiency wells in Bohai Oilfield.
Multi-scale Finite Element Method for Members for Pipe Frames
Authors: Hiu Haifeng , Wang Changzhi , Hu Xiaoguang
Published: March 2020

To consider the local buckling of the members in reticulated frames, based on the multi-scale simulation, the part of member may be collapsed were 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. By constraint variational principle, the tangent stiffness matrixes and the nodal load vectors of the micro-model and the outside structure are combined, and then the equations are solved. The location of the collapsed part is predicted by the deflection function of the beam, and the length of the collapsed part is estimated. Two case studies about a single beam and a single-layer reticulated dome are presented to show the feasibility and the validity of this method.
Design and Realization of E-MWD Instrument in Coal Mine
Authors: Jie Lian
Published: March 2020

In order to ensure safe and efficient coal mining, it is usually necessary to construct a large number of gas drainage holes and water exploring and drainage holes in the coal mine. Directional construction drilling can improve the quality of such drilling construction, measure the main parameters such as drilling inclination angle, azimuth angle and tool orientation angle in real time, draw the drilling trajectory and adjust the drilling attitude according to the needs, realize the efficient utilization of gas drainage, and advance, regional, precise prevention and control of disasters. The measurement while drilling (MWD) system is the necessary support for drilling directional construction, which is applied to various directional drilling rigs in coal mines to measure the drilling trajectory in real time to guide the design and construction of drilling.
Analysis of waterflooding characteristics of the second class oil layer in the second area of the eastern Labei block
Authors: Di Yang
Published: March 2020

This paper makes use of the new drilling in the second area of the North East block to make statistics of the watered out state of the second type reservoir section, analyzes the watered out state of the reservoir under the conditions of different thickness level, different permeability water saturation level and different sedimentary micro equal level, basically finds out the basic watered out characteristics of the reservoir in the current development stage, and provides the necessary basis for the development and adjustment of the water accumulation and two drive in the next period Based on the data and the understanding of the regularity, the foundation is laid for the further exploitation of the potential of the water drive in the second type reservoir.
Numerical simulation of rock fracture with TBM cutter
Authors: Zhu Hangyun , Feng Lingbo
Published: March 2020

In order to study the process of rock fracture with TBM, the three-dimensional discrete element model of hard rock with joints is established based on the discrete element method. Uniaxial compression test and Brazilian disk splitting test were used to calibrate the relevant parameters. The joints have different strength, spacing and inclination. The dynamic cutting simulation of single cutter is completed. The fracture characteristics of the jointed rock and the load on the tool are obtained. The results show that the joint characteristics have a great influence on the rock breaking properties of the cutter. When the thickness of the joint is unchanged, the rock breaking loadof the cutter increases with the increase of the joinsstrength. When the strength of the joint is unchanged, the rock breaking load of the cutter increases with the increase of the thickness of the joint in a certain range. Moreover, under the conditions of different strength, different spacing and different inclination, the fracture characteristics of rocks are also different.
Optimization of Microemulsion Formulation of Fracture reservoirs
Authors: Jia Jiangfen , Cao Jiefeng , Zeng Zhiguo , Long Changjun , Ning Mengmeng , Xu Zhengdong , Zhang Bin , Wang Peng , Wang Xin , Liu Qilun
Published: March 2020

In order to screen out the optimal microemulsion oil drive system, the effect of micro emulsion performance on the residual oil of pore is selected, and the remarkable effect of improving recovery rate is proved from both macro and micro aspects by analyzing the fissure core oil drive experiment and the distribution law of the residual oil of the pore. The results showed that the best microemulsion system is made of positive octane 8mL, water 8mL, 4.5% mass fraction of the beetroot, 6% mass score of positive butanol, 5% quality score of NaCI. And that microemulsion system has a smaller particle size distribution range, higher viscosity, strong stability and a smaller proportion of pore residual oil.
Study on the method of energy evolution of rock under uniaxial compression test
Authors: Liu Zhixi
Published: March 2020

For investigation evolution of energy of rock during the unconfined compression, using same loading rate were carried out uniaxial cycle loading and unloading tests, uniaxial graded loading and unloading tests, and unconfined compression tests. Through the analysis of experimental phenomena shows that the number of cycles has little effect on elastic energy. It indicates that fatigue damage has no effect on elastic energy of rock. Further comparing the elastic energy of the uniaxial cyclic loading and unloading tests and the uniaxial cyclic graded loading and unloading tests, it can be found that their elasticity energy approximately when the loads are the same. Based on above elastic energy studying, can considered that the elastic energy of the rock does not change when the load is greater than or equal to the previous load. Therefore, their elastic energy are the same when the load of unconfined compression are equal to the load of unloading point of the uniaxial graded loading and unloading tests. Based on the above analysis results, the energy real-time evolution before the peak strength of unconfined compression is studied. The method provides a new idea for real-time evolution of energy before the peak strength of rock during the unconfined compression.
The detection and response characteristics of transient electromagnetic signals caused by the deformation and fracture of overlying strata affected by mining of a thick coal seam
Authors: Zhang Pingsong , Ou Yuanchao , Hu Xiongwu , Li Shenglin
Published: March 2020

The height at which overlying strata fail is an important parameter for the prevention and control of mine water damage. High overlying strata failures during mining of a thick coal seam make testing in mines challenging. Considering the mining conditions for the thick coal seam in Ordos City, Inner Mongolia, China, this work applies ground detection using transient electromagnetics. The response characteristics of transient electromagnetic signals during strata failure were investigated using numerical simulation, and the results of that investigation will provide guidance for on-site exploration. In addition, based on the conditions of the ground and mining face, test wires were distributed within the mining work face area to obtain electromagnetic detection data using large wireframes on the ground to further construct an electrical profile of the coal mining and non-mining areas and explain the characteristics of strata failure. This method succeeded in the practical application and is provided as guidance for strata failure detection for thick coal seam mining.
A root-cause analysis methodfor faultdiagnosisin condenser
Authors: Han Banglei , Zhang Chao , Xie Chu
Published: March 2020

Condenser is an important part of thermal power units. When the condenser fails, the quick determination of the root-cause fault can effectively avoid major safety accidents in thermal power units. Most existing methods are based on the assumption of stationary relationships among the variables. However, the relationships among the variables are non-stationary in the real industrial process. These methods are not suitable for real industries. According to the process knowledge, the condenser is a typical system of non-stationary. Aiming atthe non-stationary relationships, a root-cause analysis method based on multiple regression modelsis proposed in this paper.Firstly, the bottom-up piecewise linear representation method is applied to yield qualitative trends of historical data for each variable. Secondly, qualitative trend combinations of multiple variables are obtained based on amplitudes for each variable. Finally, the contributionsof the related variables in qualitative trend combinations to the main variableare calculatedbased on multiple regression models, and the root-cause variable can be determined according to the size of the contribution. Anindustrial example is provided to illustrate the effectiveness of the proposed method.
Experimental study on sand production characteristics in natural gas hydrate deposits
Authors: Yu Tianbo , Liu Yu , Song Yongchen
Published: March 2020

During the process of natural gas hydrate exploitation, the cementation state of the stratum changes due to the decomposition of skeleton hydrate. Fine sand in the reservoir will migrate to the wellbore with the fluid, which is the so-called sand production phenomenon. Sand production will bring great harm to hydrate exploitation. In this paper, a set of visualized sand production simulator was designed to obtain the factors influencing the sand production characteristics in different working conditions. It is found that fine sand will invade and block the gravel layer and it is accompanied by the subsidence of the sand layer. Fluid flow rate and initial hydrate saturation are important factors affecting the characteristics of sand production. In addition, it is of certain guiding significance to select the appropriate median diameter ratio of gravel to sand for sand control in the actual exploitation process.
Current Situation Detection and Performance Evaluation Analysis of Existing Double-curved arch bridge
Authors: Zhou Yongjun , Wang Gangqiang , Cao Xiaozhe , Tian Ruixin
Published: March 2020

The existing design load level of the existing double-curved arch bridge is generally low, the old-fashioned inferiority and the poor overall integrity, which are likely to cause structural damage and affect the normal use of such structures. Based on the appearance inspection and static and dynamic load test of a dangerous three span double-curved arch bridge without original design data, this paper discusses the methods of structural modeling, load test and structural performance evaluation of this kind of bridge, which provides reference to the current situation evaluation of similar bridges. Through the inspection of bridge appearance defects, component cracks, deformation displacement, steel protective layer thickness, concrete carbonization depth and material strength, combined with the load test results, the comprehensive technical status of the bridge is determined to be 4 types of bridges. The bearing capacity meets the requirements of load grade Automobile-10 class, but the safety reserve is insufficient.
Preparation of cyclodextrin-modified graphene oxide and its adsorption properties for Pb (II)
Authors: Li Lingcong , Chen Bing , Su Ziwen , Wu Jinmei , Pan Zhenxing , Fu Zhiping
Published: March 2020

In this paper, the improved Hummers method was used to prepare graphene oxide (GO) and modified by cyclodextrin to prepare cyclodextrin-modified graphene oxide (CDGO) composites. The composites were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). The adsorption properties of GO and CDGO for Pb2+ were measured by atomic absorption spectrophotometer. The results showed that the number of functional groups of the modified material and the adsorption sites increased. The adsorption capacities of GO and CDGO for lead were respectively 86.47mg/g and 165.52mg/g, which were consistent with the quasi-secondary kinetic model and Langmuir isotherm adsorption model. CDGO showed better adsorption capacity.
DFT study of methane catalytic combustion on Pd-based diatomic catalysts
Authors: Pu Yunshuang , Mou Chuanlin , Yu Yang , Deng Qizheng , Wang Linyuan , Deng Hongbo , Zhang Lei
Published: March 2020

The processes of methane combustion on three Pd-based diatomic catalysts (Pd2, PdPt and PdNi) are investigated by using density functional theory (DFT) at the B3LYP/6-311++G(d,p)+SDD//B3LYP/6-311G(d,p)+LANL2DZ level. The optimized geometric structures, activation energy (Ea
), and reaction rate constant (k) of methane dehydrogenation and oxidation on Pd2, PdPt and PdNi are compared. The main reaction path for methane combustion on catalyst Pd2 is CH4→CH3→CH2→CHOH→CHO→CO→CO2. However, the main reaction paths on catalyst PdPt and PdNi are the same: CH4→CH3→CH2OH→CHOH→CHO→CO→CO2. The rate-determining steps (RDS) on catalyst Pd2 and PdPt are the same: CHOH→CHO, while the step of CH3→CH2OH is the RDS on PdNi. Further analysis shows that the catalytic activity followed the order of PdPt (k = 1.0639×104 s−1) > Pd2 (k = 1.7281×102 s−1) > PdNi (k = 1.9235×10 s−1). Thus, PdPt catalyst exhibits better performance than the other two catalysts in the methane catalytic combustion.
Numerical simulation analysis of cavitation of current limiting orifice plate
Authors: Ni Lingying , Li Bing , Geng Guangwei
Published: March 2020

In this paper, ANSYS-Fluent software is used to simulate the cavitation phenomenon that may occur in the current limiting orifice plate of the vertical oil inlet pipe with large drop in the underground water sealed oil depot. The influence of different orifice designs on the cavitation are calculated and summarized. The simulation results show that the shape of the orifice is an important factor affecting the cavitation intensity, the chamfering of the orifice can restrain the cavitation. The circular chamfer is better than the 45 ° chamfer to reduce the cavitation intensity, and the cavitation intensity will decrease with the increase of the thickness of the orifice chamfer.
Study on Dust Diffusion Law and Application of Wet Vibrating Wire Dust Removal Fan in Fully Mechanized Excavation Face
Authors: Ma Shengli , Zhang Kaiming , Zhang Heng , Zhang Qiang
Published: March 2020

Fully mechanized excavation face is the main place of dust generation in coal mines. Due to the huge dust production and long ventilation distance, the dust concentration is difficult to reach the safety standard. The purpose of this study is to improve the dust removal efficiency of 2410 roadway in Yuhua Coal Mine. Firstly, this paper carried out dust concentration and roadway wind speed measurement on the 2410 fully mechanized excavation face of Yuhua Coal Mine. According to the actual layout of fully mechanized excavation face, the geometric model is established. The distribution of wind field in fully mechanized excavation face is simulated and analyzed by Fluent software. The correctness and feasibility of the model and simulation method are verified by comparing the simulation results with the measured data. Then the paper studies the influence of the air duct outlet installation position on the airflow field and the dust distribution, and analyzes the dust removal effect of the existing wet vibrating wire dust collector dust removal system in Yuhua Coal Mine. The research conclusion is that the wet string vibration dedusting fan has remarkable dedusting effect, and the dedusting efficiency is the highest when the air duct is installed near 10 m from the working face.
Analysis of Monitoring in settlement For Vacuum Combined Stack Preloading about Soft foundation Sluice
Authors: Yong-Xin Yao , Fanng-Yi Ji
Published: March 2020

Vacuum combined surcharge preloading is a kind of drainage consolidation method, having many advantages, such as low reinforcement cost, short construction period and good reinforcement effect, and suitable used in foundation treatment in soft foundation. Based on vacuum combined surcharge preloading reinforcement project of one Sluice soft soil foundation in the east coast of Zhejiang Province, this paper introduced the in situ monitoring situation in the vacuum preloading process, mainly summarized the monitoring result of vacuum degree and surface subsidence, and found out the changes and connections of indicators in the preloading process. At the same time, the development process of vacuum combined with preloading and settlement is simulated by finite element method.
Formulating an Innovative Spatial-Autocorrelation-based Method for Identifying Road Accident Hot Zones
Authors: Feng Yiwei , Zhu Wenjun
Published: March 2020

The traditional method of identifying road accident hot zones is through the examination of accident frequency and nature, which sometimes, can be subjective and inaccurate. To overcome the limitation of the traditional method, researchers have applied Geographic Information System (GIS) approaches to identify and visualise road traffic accidences in real-time. However, these approaches still treat accidences as occasional and discrete events and can not support accurate analysis and prediction of accidences at some point. This paper takes the spatial autocorrelation nature of accidents (i.e. the interdependence of accident data and the relationship between the accident and space) into account and proposes an innovative spatial-autocorrelation-based method to identify freeway accident hot zones. Based on the spatial autocorrelation and mathematical statistics, this method constructs a point-line connectivity network to realise the space localisation and validation of accidents. Combined with GIS approaches, our approach can also automatically identify and visualise accident-prone areas. At the moment, the approach has been tentatively applied in a highway in China. The result demonstrates an algorithm behind the approach, which can effectively convert accident data into spatial data, cluster accident hot zones of any length and predict the whereabouts of likely accidents in the future. In conclusion, the robustness and accuracy of the approach innovates this study.
Analysis of Groundwater Flow Velocity and Direction along the Zihe River in the Dawu water Source
Authors: Zhan Hao , Zhu Henghua , Wei Zhengrun , Yang Lizhi , Liu Benhua , Mao Weijian , Lu Xuchun
Published: March 2020

In the observation wells installed along the Zihe River in the Dawu water source, the AquaVISION Colloidal Borescope produced by Geotech Company of the United States was used to measure the groundwater flow velocity along the Zihe River. We analyzed the measurement results based on the drilling information. The results showed that, (1)The groundwater flow velocity along the Zihe River in the Dawu water source area was between 56.798 and 122.599 m/d, and the average flow velocity was 95.380 m/d. The groundwater flow velocity of observation wells along the Zihe River was generally faster. The flow velocity of the SW447 well in the upstream of the Zihe River was the largest, and the average flow velocity was 122.599 m/d. The overall groundwater flow along the Weihe River flowed from south to north.(2)The control factors of groundwater flow velocity were mainly: large amount of water pumping, local geological structure, related hydrogeological conditions, etc.
Optimization of Fracturing Construction Parameters of Coal bed Methane Wells
Authors: Li Shuguang , Bian Liheng , Huang Ming , Yu Lizhu
Published: March 2020

The article analyzes the gas production and construction parameters of the vertical wells in the representative layer of the 15# and 3# layers in the target area due to insufficient construction strength and low gas production in the test well. The influence of the fracturing construction of the test well on its productivity was studied. The fracturing effect prediction model was established by combining the influencing factors such as construction strength, fracturing fluid, sanding strength and sand ratio. The model is used to carry out optimization research on fracturing construction parameters. Based on the analysis of influencing factors, the optimization parameters of construction parameters are proposed. The optimization scheme can obtain better test results through later engineering verification. The results show that the stable gas production of the coalbed methane well in the target block can reach an average of more than 1000m3/d through the optimization of the fracturing construction parameter system.
Research on Air-Conditioning Control Strategy of Textile Mill Based on Bidirectional Fuzzy Dynamic Decoupling Compensation
Authors: Wang Yannian , Du Kai , Wu Yunhui , Tang Hengkun
Published: March 2020

This paper introduces the main problems in the air conditioning system of China’s textile mills. Due to the coupled line problem of temperature and humidity affecting each other in the temperature and humidity regulation system, it is difficult to adjust the air conditioning system in the textile mill, and it is also more difficult to adjust the air conditioning system in the textile mill because of the influence of region, season, human activities and so on. In view of this situation, the air conditioning control system of textile mill based on TMS320F28335 was designed by dynamic decoupling control method. The reasonable adjustment and control of the equipment of the air conditioning system can achieve the stable control of the temperature and humidity of the workshop of the textile mill and reduce the energy consumption of the air conditioning control system. The practice shows that the system has good dynamic performance, high control precision and remarkable energy saving effect, and has a broad application prospect in air conditioning control in textile enterprises.
Experimental Research on Temperature Rise of Mining Explosion-proof Turbine Generator
Authors: Jun Gao , Jiguan Zhang , Zhiqin Bi , Jie Lian
Published: March 2020

In order to prevent the temperatureof a mining explosion-proof turbine generator from exceeding the safety threshold due to faults during operation, this paper monitors the temperature in real time during the operation of the turbine generator under extreme conditions by installing a temperature sensor inside the generator. This paper aims to reveal the mechanism and verify the reliability of temperature rise of the turbine generator.