Journal of Northeastern University(Natural Science)

Modeling of Coal Mill Process Monitoring Based on Instance-based Transfer Learning

CHANG Yu-qing， ZHAO Wei-wei， LIU Le-yuan， KANG Xiao-yun

2021, 42 (10): 1369-1375. DOI: 10.12068/j.issn.1005-3026.2021.10.001

Abstract ( 710 )

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Considering the shortage of industrial process data， process monitoring model based on data statistics is difficultly established， resulting in an adverse impact on the accuracy and timeliness of monitoring. Transfer learning provides an effective way for the above situation. In view of the fact that the coal mill process data in the target domain is less， on the basis of the source domain coal mill data， a target domain coal mill process monitoring model based on the instance-based transfer Gaussian mixture model(GMM)is established. The instance-based transfer learning is used to assign weight of source domain production process and target domain process data， using the modified algorithm of GMM to automatically optimize the number of Gaussian components and corresponding model parameters. The global probability index of the process monitoring is applied to realize the cross-domain monitoring of the coal mill process. The research results of the coal mill process verify the feasibility and effectiveness of the proposed method.

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Sliding Mode Observer of Lithium Battery SOC Based on Order Adaptive AR Equivalent Circuit Model

LIU Fang， LI Zhuo， SU Wei-xing， LIU Yang

2021, 42 (10): 1376-1385. DOI: 10.12068/j.issn.1005-3026.2021.10.002

Abstract ( 582 )

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Based on the equivalent circuit model， the estimation method of the remaining state of charge (SOC) of a type of vehicle power battery shows that the estimation accuracy is highly dependent on the model accuracy and the model accuracy is directly proportional to the model complexity， so that it is difficult to be better applied to the embedded control unit problem. A new equivalent circuit model with relatively low complexity and capable of adaptively determining the optimal model order， i.e.， a gray box model of the equivalent circuit of the vehicle power battery based on the order adaptive AR model is proposed. Based on this gray box model， the design derivation of the sliding mode observer for the state of lithium-ion battery SOC and the proof of observability and convergence are given. The results show that the sliding mode observer SOC estimation method (adaptive autoregressive-sliding mode observer， AAR-SMO) based on the order-adaptive equivalent circuit gray box model proposed in this paper has low model complexity， high accuracy， strong robustness and fast convergence performance.

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Process and Distribution of Droplet Coalescence Based on Dielectrophoresis Effect

HU Sheng， CHEN Yue-jiang， LYU Xiao-yong， WU Dong-xu

2021, 42 (10): 1386-1391. DOI: 10.12068/j.issn.1005-3026.2021.10.003

Abstract ( 605 )

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Based on Cahn-Hilliard， a multiphysics coupling model of Navier-Stokes two-phase fluid dynamics and electric field Maxwell stress tensor method is established，which is used for the simulation of droplet coalescence of parallel plate， pointer and ring electrodes. The research results show that the stronger electric field intensity induces a shorter time for the coalescence of the dispersed phase droplets， and the structure and uniformity of the droplet chain are greatly affected by the electrode shape and the spatial uniformity of the electric field. The uniform electric field induces the droplets to form a more uniform chain and is not affected by the number of droplets. The non-uniform electric field generated by the pointer-type and ring-type electrodes can only realize the generation of regular droplet chains under the condition of a small number of droplets. The multi-physics model and simulation results involved in this article can provide a theoretical basis for complex microfluidic electrical control such as electrospinning， droplet merging， and bubble recovery.

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Fast Chaotic Image Encryption Algorithm Combined with DNA Encoding

ZHOU Hong-liang， LIU Hong-juan

2021, 42 (10): 1391-1399. DOI: 10.12068/j.issn.1005-3026.2021.10.004

Abstract ( 1066 )

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Aiming at the speed of encryption and decryption of existing image encryption algorithms， a fast image encryption algorithm combined with DNA encoding is proposed using the chaotic sequence generated by the new 4-D chaotic system as the index sequence to indicate the specific position to be exchanged during the permutation process. DNA encoding is performed on the permuted image， and the diffusion process is completed by the DNA addition and DNA XOR of rule 1， then different rules are used for DNA decoding to complete the secondary encryption.The experimental results show that the proposed method reduces the number of loop traversals of permutation process while ensuring the security of the image encryption system， thereby increasing the speed of encryption and decryption.

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Effect of Metastable Austenite on Mechanical Properties of High-Strength Steel in Oceaneering

ZHOU Cheng， LIU Wen-peng， YE Qi-bin， WANG Zhao-dong

2021, 42 (10): 1400-1406. DOI: 10.12068/j.issn.1005-3026.2021.10.005

Abstract ( 527 )

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The effects of critical annealing and tempering at different temperatures on the microstructure and mechanical properties of marine engineering steels were studied. The results show that the microstructure of the tested steel contains tempered martensite and different volume fraction (0~6%) retained austenite after two-phase zone annealing and tempering at different temperature. When the volume fraction of retained austenite increases from 0 to 6%， the yield strength decreases from 753~506MPa and the tensile strength ranges from 794~843MPa， the yield ratio decreases from 0.9 to 0.6， and the elongation increases from 31.3%~36.2%. The retained austenite in the tested steel can improve the impact work for plastic deformation and hinder the crack propagation. The impact energy at -80℃ reaches 236J. However， due to the poor thermal stability， the retained austenite prefers to transform into martensite at low temperature， leading to a reduction of low-temperature toughness and the impact energy at -80℃ drops to 136J.

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High-Temperature Viscoplastic Constitutive Model and Rheological Behavior Analysis for Axle Steel

LIU Gan， NING Xin-yu， LI Tian-xiang， LI Hai-jun

2021, 42 (10): 1407-1414. DOI: 10.12068/j.issn.1005-3026.2021.10.006

Abstract ( 473 )

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A high-temperature viscoplastic constitutive model is the basis of numerical simulation on the deformation behaviors of continuous casting billet in a near-solidification-finishing reduction(NSFR) process. However， the lack of the stress and strain data under this condition extremely limits the development of new continuous casting processes. The rheological behaviors of axle steel under the NSFR and conventional hot deformation processes are studied through thermal simulation experiments. Based on the theory of dynamic recovery and recrystallization， a revised constitutive model in the NSFR process is established. The results show that the austenite grains are coarser and the rheological stress is lower under the NSFR process， compared with those under the conventional one. Under the same reduction， the volume fraction of dynamic recrystallization grain is higher. The predicted stresses from the constitutive model under different conditions are in good agreement with the experimental ones and the average relative error is about 2.62%.

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Effect of Quenching and Tempering Treatment on Mechanical Properties of V-microalloyed Steel for Oil Well Pipe

CAI Zhi-hui ， WEN Guang-qi， HAN A-kang， ZHANG Kai-hua

2021, 42 (10): 1414-1420. DOI: 10.12068/j.issn.1005-3026.2021.10.007

Abstract ( 601 )

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In order to cope with in complex and harsh work environments， a new-typed steel for oil well pipe has been developed， whose tensile strength， compressive strength and collapse resistant can reach steel grade of Q125.The effect of quenching and tempering(Q&T)treatment on microstructure and mechanical properties of the V-microalloyed steel was studied. The results show that the microstructure of the experimental steel after Q&T treatment contains tempered martensite， a little bainite and a large number of carbide precipitations， so that the steel has good comprehensive mechanical properties. Lower tempering temperature and longer tempering time can increase the amount of of carbide precipitations， leading to a higher precipitation hardening. Mechanical properties of the steel after tempering at 610℃ for 70min has the best performance， where the yield strength， tensile strength and elongation can reach 954MPa， 989MPa and 13.5%， respectively. The impact energy at 0℃ is 25J in transverse direction and 46J in rolling direction， which meets the requirements of steel grade of Q125 for oil well pipe.

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Effect of Cu Content on Pore Structure of Aluminum Foams After Rolling Process

WEI You， LUO Hong-jie， LU Xiao-tong， YANG Shi-jie

2021, 42 (10): 1421-1426. DOI: 10.12068/j.issn.1005-3026.2021.10.008

Abstract ( 458 )

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The liquid phase composite-rolling technology is used to prepare foamable preforms with different content of w_○Cu and closed-pore aluminum foams. The effect of w_○Cu on the pore structure of the aluminum foams was studied. The results show that with the increase of w_○Cu， the uniformity of the pore structure increases， and the pore size and the number of large pores produced by pore merging decrease， while the collapsing and aging characteristics of the foam are enhanced. After comparing the expansion curves of preforms with different w_○Cu， it is found that when the w_○Cu increases， _○the maximum expansion rate of the preform firstly increases and then decreases and the foaming time to reach the maximum expansion rate is greatly shortened. The microstructure analysis shows that CuAl₂O₄ and CuAl₂can be formed after adding Cu into AlSi₉ alloy. CuAl₂O₄ increases the viscosity of the melt， reduces the effect of gravity drainage and capillary action， and improves the stability of the foam. CuAl₂ melts prior to AlSi₉ alloy， forming a molten pool on the grain boundary， and the bubbles nucleate and grow in advance， so that the foaming process is completed ahead of schedule.

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Research on Tool-Changing Trajectory Planning of Tool-Changing Robots Based on Hybrid Spline Curves

QIAN Wen-xue， SONG Shuai， LI Hao， WANG Ying-hua

2021, 42 (10): 1427-1434. DOI: 10.12068/j.issn.1005-3026.2021.10.009

Abstract ( 520 )

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In order to study the issue that the tool-changing robot can move smoothly along a specific route， kinematics analysis and trajectory planning of the robot model are carried out. The kinematics model of the robot is derived by using the screw theory combined with Monte Carlo simulation to obtain the distribution of the working space at the end of the robot. A trajectory planning method for multi-node and multiple-curve motion is proposed. The joint displacement， angular velocity and angular acceleration are used as the evaluation indicators， and 3-3-3， 5-5-5 and 4-5-5 spline curves are used to plan the trajectories respectively. The prototype platform test shows that the 4-5-5 mixed polynomial can obtain a relatively stable acceleration curve， which effectively solves the problem of excessive steps and sudden change in acceleration. The research provides a basis for the trajectory planning of complex tool-changing paths of manipulators.

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Modification of Discrete Element Contact Parameters of Coal Bulks Based on Rotary Transport Test

LI Bo， WANG Zi-sheng， LIANG Chao， WANG Xue-wen

2021, 42 (10): 1435-1443. DOI: 10.12068/j.issn.1005-3026.2021.10.010

Abstract ( 497 )

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To obtain the accurate discrete element simulation results of scraper conveyors， the contact parameters of coal bulks were corrected by the response surface method based on the rotary transport test. The Plackett-Burman test was used to investigate the effect of contact parameters on the force and stacking angles， and it was found that the static friction coefficient of coal-steel and the friction coefficient of coal-coal have significant positive effects. According to the results of the climbing test， the Box-Behnken test was planned with force and stacking angle as the response value， and the quadratic regression polynomials between forces， stacking angles and significant terms were established respectively. The optimal parameters were obtained with the measured data as the target value and the results showed that the static friction coefficient of coal-steel is 0.401， the static friction coefficient of coal-coal is 0.333， and the rolling friction coefficient of coal-coal is 0.041. The accuracy of the parameters was verified by the rotary test under different transportation conditions， which provides a reference for the discrete element study of scraper conveyors.

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Active Learning Algorithm of Structural Reliability Based on Kriging and MCMC

ZHANG Hao-yan， BI Qiu-shi， LI Bo， GUO Guang-yong

2021, 42 (10): 1444-1450. DOI: 10.12068/j.issn.1005-3026.2021.10.011

Abstract ( 572 )

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Because the performance functions of many engineering problems are more complicated and the calculation cost is high in the reliability analysis of mechanical structures， the agent model is often used to fit the implicit performance function to reduce the calculation cost. In order to use less sample information and obtain higher reliability calculation accuracy， the Kriging agent model is combined with the learning function， and an active learning reliability analysis and calculation method is proposed. This method finds the sample points with the best learning effect to update the Kriging model， which improves the fitting accuracy of the model. Markov chain Monte Carlo(MCMC)method is used to evaluate the reliability of the structure， which speeds up the convergence speed of sample points and saves sample space. Analyzing the results of 4 calculation examples shows that compared with the other methods， this method can obtain higher precision calculation results with fewer sample points， and reduce the calculation cost.

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Effect of Microwave Radiation on Pore Structure and Tensile Strength of Metagranulite

YU Hong-wen， AN Long， LI Yuan-hui， GAO Chuan-bo

2021, 42 (10): 1451-1458. DOI: 10.12068/j.issn.1005-3026.2021.10.012

Abstract ( 516 )

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In order to reveal the damage law of metagranulite under microwave radiation， the microwave radiation experiments were carried out on metagranulite of gold-bearing ore body from Danyin Mining Co.， Ltd.. The results show that the localized high-temperature melting zone is an iron-rich zone，where a large number of pores formed with pore size up to 0.11mm.Obvious macro cracks and dense micro-fracture networks can be observed near the periphery of the melting zone. With the increase of the distance away from the high temperature zone， the microscopic cracks are obviously reduced， and the porosity gradually decreases. As the microwave radiation time increases， the tensile strength and damage increment decrease continuously. The tensile strength of the rock after microwave radiation depends on the distribution of cracks and the strength and range of the melting zones. The results are of great significance for optimizing the microwave radiation time and improving the efficiency of the microwave radiation cracking.

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Bingham Fluid Seepage Model in Rock Fractures

WANG Zhe-chao， ZHANG Hao-wei， LONG Qiu-xi， LIU Jie

2021, 42 (10): 1459-1467. DOI: 10.12068/j.issn.1005-3026.2021.10.013

Abstract ( 1018 )

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In order to study the seepage law of Bingham fluid in a rough single fracture， a seepage model describing the viscous and viscous inertial flow of Bingham fluid in rock mass fractures was proposed， and the model was verified by numerical simulation and laboratory tests. The seepage simulation of Bingham fluid with different rheological parameters in rough fractures under a wide range of pressure gradients was carried out. Combined with the modified Forchheimer equation， the non-Darcy coefficient β， critical Reynolds number Re_c， non-Darcy effect factor E and other variation characteristics of Bingham fluid under different geometric parameters and rheological parameters of fractures were analyzed. The results show that the viscosity model derived from the Bingham fluid constitutive equation can better describe the viscous flow. The modified Forchheimer equation can better describe the visco-inertial seepage characteristics of Bingham fluid in rough fractures. Roughness and rheological parameters have a significant impact on seepage characteristics: the larger the fracture roughness， the larger the yield stress of the slurry; the larger the plastic viscosity of the slurry， the stronger the inertia effect.

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Extraction and Adsorption Properties of Extracellular Polymeric Substance

XU Xiao-hui， WEI De-zhou， ZHANG Lan-he

2021, 42 (10): 1467-1474. DOI: 10.12068/j.issn.1005-3026.2021.10.014

Abstract ( 1737 )

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In order to quickly and efficiently extract extracellular polymeric substances(EPS)from activated sludge， four methods were used to extract tightly bound EPS(TB-EPS). The advantages and disadvantages of different extraction methods were compared， the effect of TB-EPS on the adsorption performance of Mn²⁺was investigated， and the adsorption mechanism of TB-EPS was studied. The results show that the heating method is simple and efficient with no damage to cell structure.When adsorbing heavy metal Mn²⁺， the maximum adsorption rate of TB-EPS extracted by heating method is 53.8%. The adsorption process conforms to the second-order reaction kinetic characteristics and the Langmuir adsorption isotherm equation， which is mainly the chemical adsorption. The main adsorption mechanism of TB-EPS is the interaction of hydrophobic tryptophan and tyrosin.

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Calculation Method of the Critical Force of Support Structure System Based on Stability Function

WANG Shu-hong， YAO Qian， ZHANG Chao， WANG Peng-yu

2021, 42 (10): 1475-1482. DOI: 10.12068/j.issn.1005-3026.2021.10.015

Abstract ( 509 )

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Based on the stability function， a calculation method for solving the critical force of the support structure system was given， and the calculation formula for the critical force of three double-layer support structure systems at different load positions was derived. The results show that the analytical solution derived from formula based on the stability function theory is similar to the numerical solution of the second-order elastic analysis with an error less than 3%. The accuracy of the calculation method for the critical force of the support structure system was verified by the the theoretical and experimental values of the total bearing capacity of the double-layer 1~3-span rocking column support structure system. The critical force calculation method of the support structure system provides a theoretical basis for engineering applications due to its universal applicability and high calculation accuracy.

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Air Permeability and Pore Axis Reliability of Tailing-Ball Concrete Under Chloride Salt Dry-Wet Cycle

LI Yi， LI Shao-feng， GAO Yan

2021, 42 (10): 1483-1490. DOI: 10.12068/j.issn.1005-3026.2021.10.016

Abstract ( 429 )

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In order to study the effect of chloride corrosion on tailing-ball concrete， the air permeation tests and pore structure tests were carried out on the ordinary concrete(C)， the tailing-ball concrete(T)and the steel fiber tailing-ball concrete(TF 8)respectively. The variation rules of chloride air permeability coefficient， air volume fraction， bubble frequency and pore axis reliability with the increase of the age of chloride salt dry-wet cycle erosion were obtained. The relationship between concrete air permeability， pore structure and pore axis reliability was given. The results show that with the increase of the age of the chloride salt dry-wet cycle erosion， the air volume fraction and the bubble frequency of C， T and TF 8 increase， and the reliability of pore axis reduces， which lead to the increase of air permeability coefficient. Results also show that the chloride dry-wet cycle can increase the permeability of concrete， make the pore size distribution worse， increase the pore size and decrease the reliability of pore axis.

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Spontaneous Combustion Characteristics and Critical Conditions of Spontaneous Combustion of Polished Aluminum Powder Based on F-K Theory

WANG Xin-yang， LI Gang

2021, 42 (10): 1491-1498. DOI: 10.12068/j.issn.1005-3026.2021.10.017

Abstract ( 701 )

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The wire-mesh basket experiment was used to study the spontaneous combustion characteristics， the critical conditions of spontaneous combustion and the temporal and spatial distribution of temperature in the oxidation process of polished aluminum powder. According to the Frank-Kamenetskii(F-K)theory， the difference method and the cross-point temperature method were used to analyze the experimental data， calculate the oxidation reaction kinetic parameters and extrapolate the experimental results， and predict the minimum spontaneous combustion critical temperature at the industrial site accumulation scale. The research results show that the oxidation process of polished aluminum powder conforms to the Arrhenius kinetic mechanism， and the reaction activation energy is 105.4kJ/mol. The critical temperature of aluminum powder is 215.5℃ when the small size baskets are stacked in the laboratory. When the stacking size is increased to the size of the dust collecting bucket on the industrial site， the critical temperature drops to 129℃. The research results can provide a theoretical reference for the prevention and control of spontaneous combustion disasters during the production， storage and transportation processes of aluminum powder.

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Product Competitiveness Analysis Method Based on Online Reviews

TIAN Jin-ni， YOU Tian-hui， YUAN Yuan

2021, 42 (10): 1498-1505. DOI: 10.12068/j.issn.1005-3026.2021.10.018

Abstract ( 590 )

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With the development of e-commerce， online reviews have been regarded as important data resources for enterprises to analyze the competitiveness of their products. Product feature dimensions that consumers pay most attention to were extracted from review texts. The sentiment analysis of review texts was performed based on the sentiment lexicon method to obtain the feature-sentiment score pairs. The opportunity scores of feature dimensions were calculated by the importance degree and satisfaction degree， and an opportunity landscape diagram was drawn to analyze the competitiveness of the target product itself. Feature dimension satisfaction degree was calculated to compare the competitive advantages and disadvantages between the target product and its competitive products. Competitiveness improvement strategies of the target product were given by considering the competitiveness analysis results from two perspectives comprehensively. The online reviews provided by Zol.com.cn were used to conduct experiments to illustrate the feasibility and effectiveness of the proposed method.

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Research on Software Product Sales Channel Strategies Considering Maladjustment Costs

ZHANG Cui-hua， ZOU Yu-feng， LI Zhi-tang， MA Yong

2021, 42 (10): 1506-1513. DOI: 10.12068/j.issn.1005-3026.2021.10.019

Abstract ( 480 )

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The diversified background of software product sales channels can be divided into five categories: direct sales(D)， value-added retail(V)， agent(A)， direct marketing and value-added retail(DV)， value-added retail and agent(VA). Considering customers’ maladjustment costs of software products， a consumer utility model was established， and the decision-making problem of the sales channels of software companies was studied. Stackelberg game was used to solve and analyze， whose results showed that the dual-channel model is better than the single-channel model in general scenarios; when the cost is not suitable， software companies tend to choose the VA model. Only when the company’s bargaining power and customization costs are both low， software enterprises should adopt the DV mode for sales. When the cost is not too high， software companies will abandon the agency channel， and the service level of agents in the VA mode is always higher than that in the A mode.

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Will Mental Simulation Make Customers Delighted? A Mediated Moderation Model

ZHANG Yue-xian， YU Pei-yu， YANG Yong

2021, 42 (10): 1514-1520. DOI: 10.12068/j.issn.1005-3026.2021.10.020

Abstract ( 480 )

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By examining the mechanism between outcome valence and customer delight， it explains whether mental simulation can make customers more delighted. The research hypothesis was validated using the simulated situational experimental design and regression analysis methods. The results showed that the relationship between mental simulation adjustment outcome valence and customer delight， that is， the difference between good and bad results under the mental simulation of attention result is significantly smaller than the difference between good and bad results under the mental simulation of attention process. The relation between outcome valence and customer delight was selected by the mediation role of expectation discrepancy. The interaction between outcome valence and mental simulation affects customer delight through the mediation of expectation discrepancy. This research provides new perspectives and ideas for online retailers to drive customer delight.

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