Journal of Northeastern University(Natural Science)

A De Bruijn Graph Localization Algorithm Based on Minimal Set of Edges

YU Chang-yong， JIN Jian-yu， LIU Peng， ZHAO Yu-hai

2022, 43 (2): 153-159. DOI: 10.12068/j.issn.1005-3026.2022.02.001

Abstract ( 988 )

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A DBG(de Bruijn graph)model called MiniDBG for gene sequence alignment is proposed. It can store the position list of the minimum edge set， and effectively locate any node， edge and path on the graph through the position list， so as to achieve sequence alignment of genes. The MiniDBG model and the path location algorithm based on the model are introduced， and the algorithm is proved. Meanwhile， the MiniDBG is compared with the path location method based on BWT and location list. Experimental results show that the performance of MiniDBG is better than those of the other two methods in the case of frequent alignment.

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Historical Data-Driven Multi-scale Quantum Harmonic Oscillator Optimization Algorithm

JIN Jin， WANG Peng

2022, 43 (2): 160-167. DOI: 10.12068/j.issn.1005-3026.2022.02.002

Abstract ( 743 )

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The multi-scale quantum harmonic oscillator optimization algorithm(MQHOA)is a natural calculation algorithm based on quantum physics proposed in recent years. Aiming at the problem that the algorithm fails to make full use of the historical information in the iteration， this paper proposes a historical information-driven multi-scale quantum harmonic oscillator optimization algorithm(HI-MQHOA). In the two-step iterative process， HI-MQHOA introduces historical data as a driver to form the parameters of the next generation individual distribution and dynamically adjust the scale of the algorithm. The next generation individual distribution parameters can effectively guide the development and exploration of the algorithm， and dynamic scaling can avoid premature stagnation. Verified by several classical test functions， the algorithm is superior to MQHOA， improved MQHOA and other natural computing algorithms in solution quality， accuracy and scalability.

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A General Adversarial Attack Method Based on Random Gradient Ascent and Spherical Projection

FAN Chun-long， LI Yan-da， XIA Xiu-feng， QIAO Jian-zhong

2022, 43 (2): 168-175. DOI: 10.12068/j.issn.1005-3026.2022.02.003

Abstract ( 701 )

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In general adversarial attacks oriented to sample sets， the general perturbation design that causes most sample to output errors is the key to the research. This paper takes the typical convolutional neural networks as the research object， summarizes the existing general perturbation generation algorithms， and proposes a general perturbation generation algorithm that combines batch random gradient ascent and spherical projection search. In each iteration of the algorithm， a small batch of samples are extracted from the sample set， and the general perturbation is calculated by using the random gradient rising strategy which reduces the value of the loss function. The general perturbation is then projected to the high-dimensional spherical surface with a radius of ε， so as to reduce the search space of general disturbances. The algorithm also introduces a regularization technique to improve the generation quality of general disturbances. Experimental results show that compared with the baseline algorithm， the attack success rate is significantly increased， and the solution efficiency of general perturbation is improved by about 30 times.

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Channel Estimation for MIMO-OFDM System Based on KNN-TSVR Algorithm

LI Shuo， LEI Wei-min， ZHANG Wei

2022, 43 (2): 176-182. DOI: 10.12068/j.issn.1005-3026.2022.02.004

Abstract ( 702 )

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In order to improve the channel estimation performance of MIMO-OFDM system， a channel frequency response estimation algorithm based on K-nearest neighbor twin support vector regression(KNN-TSVR)is proposed. The working process of the algorithm is that the least square algorithm is used to estimate the channel parameters of the pilot position， and the training samples are obtained. Then the KNN algorithm is used to preprocess the training samples， and the weights given to each sample are obtained. Finally， the weighted TSVR is used to interpolate the channel parameters of all the positions in the MIMO-OFDM system. The improved weighted TSVR channel estimation method proposed not only has the advantages of TSVR in nonlinear regression， but also has better regression performance and anti-noise ability compared with traditional TSVR due to the improvement of TSVR based on KNN. The simulation results of nonlinear MIMO-OFDM channel estimation confirm this conclusion.

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Hot Rolling Twinning Behavior of Strip Casting Grain-Oriented Silicon Steel

SONG Hong-yu， LIU Hai-tao， WANG Guo-dong

2022, 43 (2): 182-187. DOI: 10.12068/j.issn.1005-3026.2022.02.005

Abstract ( 696 )

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In strip casting grain-oriented silicon steels， the inheritance of coarse λ grains (〈100〉//ND， normal direction) can deteriorate their magnetic properties. To solve the problem， twinning behaviors in strip casting grain-oriented silicon steels during hot rolling were investigated in this work. It is found that after rolling at 650℃， a number of 112〈111〉deformation twins are formed in the coarse solidification microstructure of the steels， in contrast to the well-accepted view that it is difficult to trigger twinning at relatively high temperature in the grain-oriented silicon steels with high stacking-fault energy. The results indicate that the complex stress state during hot rolling may weaken the orientation dependence of deformation twinning. Due to higher stored energy， the intersections of twin/twin boundaries and twin/grain boundaries can act as the preferential nucleation sites for the recrystallized grains during normalizing annealing， leading to a significant increase of recrystallization rate. Because of the restriction from local strain partitioning and the limited size between the twins， the shape of new-formed recrystallized grains is mainly plate-shaped. Consequently， the fine grains with scattered orientations are formed in the normalized microstructure and the coarse λ grains in the solidification microstructure are eliminated.

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Tempering Stability of a 690MPa Grade Ultra-heavy Rack Steel for Offshore Platform

LIU Geng， LI Hui-jie， WANG Qing-hai， YE Qi-bin

2022, 43 (2): 188-196. DOI: 10.12068/j.issn.1005-3026.2022.02.006

Abstract ( 711 )

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The effects of long-term tempering (2h，4h and 8h) on microstructure and mechanical property of rack steel A514 GrQ for offshore platforms were studied. It is found that during the tempering process， the quenched martensite lath structure recovered， C， Cr， Mo and V elements diffused， and MC， M₂C， and M₂₃C₆ type carbides were precipitated in the martensite matrix. After tempering for 2h， the carbides tended to be stable and the Ostwald ripening occurred. With the increase of tempering time from 0h to 8h， tensile strength of the tested steel decreased from 1100MPa to 813MPa and yield strength decreased from 931MPa to 725MPa. The impact energy at -60℃ increased from 187J of the as-quenched steel to 238J after 2h tempering and then it tended to be stable with a value about 245J for further tempering. The elongation increased from 15.2% of the as-quenched steel to 16.7% after 2h tempering and further increased up to 19.5% for 8h tempering. These results indicate that in the process of tempering at 600℃ for 2-8h， the experimental steel A514 GrQ can perform the good tempering stability and the excellent combination of strength and toughness， associated with the best tempering time of 2h.

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Microstructure and Properties of WC Particles Reinforced 316L Stainless Steel Composites Prepared by Additive and Subtractive Manufacturing

ZHAO Yu-hui ， GAO Meng-qiu ， ZHAO Ji-bin ， HE Chen

2022, 43 (2): 197-205. DOI: 10.12068/j.issn.1005-3026.2022.02.007

Abstract ( 720 )

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Using the own-patented technology and equipment for additive/subtractive manufacturing， the effects of laser power(270， 300 and 330W)and WC mass fraction(0， 2.5%， 5%， 10% and 15%)on the densification， microstructure evolution and surface wear resistance of the WC particles reinforced 316L stainless steel composites were investigated. The results show that with the increase of WC mass fraction， the density firstly increases and then decreases， while the hardness and wear resistance increase gradually. Excessive WC particles will cause thermal cracks and reduce the surface quality of the additive parts. When the laser power increases from 270W to 330W， the powders are fully melted， and the non-fusion defects obviously reduce after solidification. When the mass fraction of WC particles is 5% and the laser power is 330W， the density of the additive parts can reach up to 99.6%. The findings indicate that mechanical property， wear resistance and surface quality of the 316L matrix can be significantly improved by the WC reinforcements.

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An Coupled Model of Multiphysics and Selective Reduction in Titanium Slag EAF

LI Bao-kuan， OU Hai-bin， YU Yang， LI Meng-zhen

2022, 43 (2): 206-213. DOI: 10.12068/j.issn.1005-3026.2022.02.008

Abstract ( 622 )

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Aiming at the selection and control of operating parameters of electric arc furnace， a multiphysics 3D model is established for the transport and reaction behavior of material， titanium slag and molten iron. The model equations are solved with finite volume method. The results show that， the joule heat， temperature and voltage drop are concentrated in the area around the electrodes， showing strong coupling and non-uniformity of multiple physical fields. The transverse expansion of melting pool slows down obviously with the passage of time， until it stabilizes near the furnace wall， and forms a slag layer. The mass fractions of titanium concentrate and coke in the material layer affect the position of reduction reaction， making it move towards the furnace entrance continuously. The feeding rate of EAF and the reaction rate have a similar trend. When the furnace condition tends to be stable， the formation rate of titanium slag is about 2.4kg·s^-1， and the formation rate of molten iron is about 1.5kg·s^-1.The mass flow rate ratio of the main feed， auxiliary feed and central feed is 20∶22∶9.

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Critical Axial Force Model in Helical Milling of Carbon Fiber Reinforced Composites

WANG Hai-yan， JIN Tian， ZHOU Zhi-tong， FU Qi-lin

2022, 43 (2): 214-220. DOI: 10.12068/j.issn.1005-3026.2022.02.009

Abstract ( 554 )

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Through a delamination mechanism analysis in the helical milling of carbon fiber reinforced polymers(CFRP)， a critical axial force model is put forward based on the classic theory of plates and shells， which is used to resolve the exit delamination state.The model analysis shows that the thickness of the uncut material is an important factor affecting the material’s exit delamination in the helical milling process， and with the decrease of the thickness， the probability of exit delamination increases. Experimental study on the helical milling of CFRP is carried out， and the results show that the maximum deviation of the critical axial force of the model is about 13.48%. The full-factor experimental results show that the axial force decreases with the rise of the spindle speed， increases with the rise of the feed per tooth， and increases with the rise of the axial cutting depth per revolution. The tool wear has a linear relationship with the axial force. Under the conditions of 0.02mm/t feed per tooth， 6000r/min spindle speed and 0.1mm/r axial cutting depth per revolution， the axial force is the minimum.

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Influence of Water Entry Angle on High-Speed Projectiles in the Water Entry Process

HAO Bo， DAI Hao， LUY Chao

2022, 43 (2): 221-227. DOI: 10.12068/j.issn.1005-3026.2022.02.010

Abstract ( 685 )

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The effect of water entry angles on the cavitation shape， trajectory characteristics and hydrodynamic characteristics of high-speed projectiles is studied. The VOF(volume of fluid)multiphase flow model， Schnerr and Sauer cavitation model， overlapping grid and 6DOF (degrees of freedom) technology are used to carry out the numerical simulation of the water entry process of a projectile. The results show that the cavitation shape on both sides of the projectile is asymmetric， and the size of the cavitation on the right side is larger than that on the left side. After the projectile enters the water， the smaller the water entry angle， the greater the velocity at the projectile centroid. When the water entry angle is 45°， the fluctuation range of the pitch angle， yaw angle and roll angle is smaller. When the projectile hits the water surface， the drag force and lift force show a peak， but the side force does not show a peak but a slight fluctuation. The water entry angle has little effect on the rolling moment， yawing moment and pitching moment in the stable stage of the projectile flow.

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Optimization of Power Consumption Algorithm for Pure Electric Vehicle Under the Influence of Multiple Factors

LI Lin-hui， ZHANG Xin-liang， LIAN Jing， ZHOU Ya-fu

2022, 43 (2): 228-235. DOI: 10.12068/j.issn.1005-3026.2022.02.011

Abstract ( 818 )

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Aiming at the problem of power consumption prediction of pure electric vehicles， a power consumption calculation model considering the influence of environmental temperature， battery state and vehicle speed was proposed. Firstly， based on the independently developed data acquisition device， the long-term driving data of pure electric vehicles in different cities were collected as the basis of model construction. Secondly， considering the factors such as temperature， battery and speed in the actual driving process of pure electric vehicles， combined with the road driving standard of China automobile driving conditions(CATC-LT)， the power consumption model of pure electric vehicle traveling 100km was proposed. Finally， the power consumption of 100km in the actual complex environment was optimized. The results show that the root-mean-square error (RMSE) is in the range of 0.83-4.92， and the mean RMSE is 2.00， which is 77.1% lower than the RMSE of the traditional method.

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Prediction Model for Elongation of Tension Leveling Based on Machine Learning Algorithm and Numerical Analysis

CHEN Bing， HAN Jin-yang， TANG Xiao-lei， XIA Bo-ran

2022, 43 (2): 236-242. DOI: 10.12068/j.issn.1005-3026.2022.02.012

Abstract ( 625 )

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In the process of cold rolling bending straightening， aiming at the setting of process parameters of tension straightener， the prediction accuracy of elongation models established by empirical formula and finite element simulation is not high. To improve the accuracy， the traditional analytical models and machine learning algorithms are studied. The accuracies of the two methods are compared. It is found that the elongation prediction model of machine learning algorithm has higher goodness of fit (R²) than the numerical analytical model. Comparing BP neural network algorithm with SVM (support vector machine) algorithm， the prediction model accuracies of the two machine learning algorithms are basically the same. In order to further improve the prediction accuracy， the BP neural network is optimized by Adam algorithm， and the parameters of SVM prediction model are optimized by genetic algorithm. Finally， the MAPE(mean absolute percentage error) and R^○2 of the optimal prediction model are 13.4% and 0.953 respectively， which can provide technical guidance for actual production.

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Stability Analysis of Surrounding Rock of Underground Caverns Considering Contact State of Interbedded Layered Rock Mass

ZHAO Meng， XIAO Ming， CHEN Jun-tao， ZUO Shuang-ying

2022, 43 (2): 243-250. DOI: 10.12068/j.issn.1005-3026.2022.02.013

Abstract ( 638 )

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The interlayer shearing and crushing fracture zone are the key factors affecting the stability of surrounding rock of underground caverns in interbedded layered rock mass. For the problem of the interlayer shearing and crushing failure of interbedded layered rock mass， the interface element model was introduced to simulate the interlayer contact characteristics. Based on this， the contact model algorithm was improved. In view of the possible contact states for nodes on the boundary of the contact surface such as bonding contact， slipping contact， opening and embedding contact， the corresponding contact state criterion and modified iterative algorithm were established， which can effectively simulate the nonlinear slip damage between layers of interbedded layered rock mass. Then， the proposed model was applied to the stability calculation of the surrounding rock of underground powerhouse of Azad Patan Hydropower Station in Pakistan. Compared with the calculation results of the transverse isotropic model， the stress and displacement at the interlayer transition zone vary discontinuously and increase after considering the contact; dislocation displacement occurs between layers， which is more obvious in the middle and lower parts of the side wall of the main underground caverns.

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Evaluation of Reservoir Bank Landslide Susceptibility Degree Based on Interval Number and Set Pair Analysis Theory

SONG Sheng-yuan， WU Feng， BAI Hao， WANG Hai-yu

2022, 43 (2): 251-257. DOI: 10.12068/j.issn.1005-3026.2022.02.014

Abstract ( 485 )

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The paper takes the Wudongde reservoir bank landslide as an example and fully considers the developed geological environment. The four impact factors including development feature of landslide， bank slope structure and lithology characteristics， geological structure and topography characteristics， disaster inducing factors are selected as landslide susceptibility factors. A single-factor grading standard is established to divide the susceptibility of reservoir bank landslide disasters into four levels: severe， moderate， mild and good. Based on the interval number and set pair analysis theory， a new model of connectional expectation for landslide susceptibility evaluation is introduced. This model can be used to analyze variation trend of landslide impact factors. The case study shows that the new method is reliable and can simplify the analysis process of the relationship between interval numbers.

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Optimization of Connection Parameters of Steel Tube Slab Structures Based on Fuzzy Mathematics

CAO Wen-xin， ZHAO Wen， LU Bo， JIA Peng-jiao

2022, 43 (2): 258-266. DOI: 10.12068/j.issn.1005-3026.2022.02.015

Abstract ( 481 )

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A finite element model of the standard STS specimen was established on the basis of laboratory tests on longitudinal bending performance， then the model’s feasibility was verified. The influence of the wall thickness and diameter of pipe， the bolt diameter， the spacing between pipes and the flange plate thickness on the longitudinal flexural bearing capacity， the mid-span deformation under the yield load and the specimen’s average price per meter was studied by orthogonal test， and the parameters of STS specimen were optimized by fuzzy mathematics. The results indicate that the pipe diameter has the greatest influence on the mid-span deformation under the yield load， and the pipe thickness has the greatest influence on the longitudinal flexural bearing capacity and the specimen’s average price per meter. To meet the safety and economy， the ratio of parameters is suggested to be， the pipe diameter∶the pipe thickness∶the bolt diameter∶the spacing between pipes∶the flange thickness=1∶0.03∶0.05∶1.15∶0.02.

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Impact Compression Properties of Recycled Tyre Steel Fiber Reinforced Concrete Based on Fractal Theory

CHEN Meng， WANG Yu-ting， TAO Yun-xiao， WANG Hao

2022, 43 (2): 266-273. DOI: 10.12068/j.issn.1005-3026.2022.02.016

Abstract ( 482 )

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In order to study the impact compression properties of recycled tire steel fiber(RTSF) reinforced concrete， the impact compression tests of general concrete(F 0)， industrial steel fiber(ISF)reinforced concrete and RTSF reinforced concrete were carried out by using split Hopkinson pressure bar. The crushed specimens were sieved and fractal dimensions were calculated. The results indicate that the impact failure modes of RTSF reinforced concrete can be divided into three types: peripheral tensile strain failure， core retaining failure and overall failure. The fractal dimension of RTSF reinforced concrete ranges between 1.33 and 2.25 under strain rates of 55 to 125s^-1. The fractal dimension decreases and then increases with the increase of RTSF content. The fractal dimension of RTSF 0.75 reinforced concrete is minimal. The fractal dimension of concrete reinforced with various fiber contents increases with the increase of strain rates. Under different strain rates， the dynamic compressive strength and fracture energy of RTSF reinforced concrete enhance with the increase of fractal dimension. The fractal dimension， dynamic compressive strength and fracture energy of concrete reinforced with ISF 1.00 are between those of concrete reinforced with RTSF 0.75 and RTSF 1.00.In terms of impact compression， RTSF 0.75 outperforms ISF 1.00 (the fiber length is 35mm and the aspect ratio is 65).

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Bond-Slip Behavior Between Reinforcement Bars and High-Strength Lightweight Aggregate Concrete

ZHANG Yu， LIU Bo-quan， WU Tao， CHEN Xu

2022, 43 (2): 274-282. DOI: 10.12068/j.issn.1005-3026.2022.02.017

Abstract ( 517 )

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Nine groups of pull-out tests on the bond-slip behavior between reinforcement bars and lightweight aggregate concrete were completed.The effect of lightweight aggregate concrete strength， anchorage length， coarse aggregate type and bar diameter on bond strength was analyzed. Combined with the test results， the analytical solution of bond strength of lightweight aggregate concrete was given by using thick wall model， and a constitutive model between reinforcement and lightweight aggregate concrete was established.Test results indicate that the bond-slip behavior of the lightweight aggregate concrete is mainly affected by the mortar strength， making the bond stress between the concrete and reinforcement bars better than that between normal weight concrete and reinforcement bars. The bond strength increases with the increase of strength of lightweight aggregate concrete and with the decrease of anchorage length. The proposed bond stress-slip constitutive model shows good precision to predict test curves.

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Appointment Capacity Allocation Model of Medical Examination Considering Adding the Temporary Service Capacity

YANG Fei-fei， JIANG Yan-ping， TANG Zhen-peng

2022, 43 (2): 283-289. DOI: 10.12068/j.issn.1005-3026.2022.02.018

Abstract ( 487 )

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In view of the allocation of medical examination appointment capacity， it is considered that emergency examinations that are in an idle state are added to routine examinations as temporary services， and the two together serve regular patients with appointments and walk-in patiets. With the goal of maximizing the expected return of the hospital， a medical examination appointment capacity allocation model is established， and the structure property of this model is analyzed to prove that there is an optimal appointment limit that maximizes the expected return on the day of service， and the conditions for solving the optimal appointment limit are given. Through a large number of numerical experiments， the influence of different parameters on the allocation scheme of medical examination capacity is analyzed. The results show that the number of arriving walk-in patients and temporary service ability have a greater influence on the allocation scheme.

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Measurement of China’s Provincial Ecological Welfare Performance and Its Influencing Factors

ZHANG Yan-bo， LI Xiang， LIU Wei， KOU Po

2022, 43 (2): 289-296. DOI: 10.12068/j.issn.1005-3026.2022.02.019

Abstract ( 669 )

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An ecological welfare performance model is constructed based on its definition. On this basis， the panel data of 30 provinces， cities and autonomous regions in China from 2007 to 2017 are used to measure the ecological welfare performance level， and the influencing factors that determine its differences are empirically analyzed. It is found that China’s ecological welfare performance has experienced three stages of “rising-falling-rising” in the time trend， and the overall increase is 19.3%. In terms of regional characteristics， ecological welfare performance presents a pattern of “the highest in the east， the second in the west， and the lowest in the middle”. Economic scale has improved China’s ecological welfare performance， while government supervision， urbanization and industrial structure are the negative factors that inhibit the improvement of China’s ecological welfare performance. Formalism and information asymmetry make it impossible for public participation to have an impact on the ecological welfare performance.

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Time Strategies of Innovative Technology Adoption Considering Technical Uncertainty

GUO Li， JIANG Nan

2022, 43 (2): 297-304. DOI: 10.12068/j.issn.1005-3026.2022.02.020

Abstract ( 343 )

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Whether an innovative technology should be adopted early or with delay involves the construction of sustainable competitiveness. Based on Farzin’s optimal technology adoption model， the uncertainty of innovative technologies is redefined from two aspects of expected income and occurrence time of innovative technologies， a dynamic programming model for manufacturing enterprises is constructed to adopt innovative technologies， and a numerical example analysis is given. The research shows that for the technologies that appear or grow rapidly， the time strategy of enterprises is to wait and carefully evaluate， so as to avoid falling into the technology trap(the more introduced， the more backward); for technologies with large variable costs(equipment upgrading cost， manpower allocation and other management costs)， enterprises’ time strategy is to adopt them as soon as possible.

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