This paper presents methods for computing a second-order sensitivity matrix and the Hessian matrix of eigenvalues and eigenvectors of multiple parameter structures. Second-order perturbations of eigenvalues and eigenv...This paper presents methods for computing a second-order sensitivity matrix and the Hessian matrix of eigenvalues and eigenvectors of multiple parameter structures. Second-order perturbations of eigenvalues and eigenvectors are transformed into multiple parameter forms,and the second-order perturbation sensitivity matrices of eigenvalues and eigenvectors are developed.With these formulations,the efficient methods based on the second-order Taylor expansion and second-order perturbation are obtained to estimate changes of eigenvalues and eigenvectors when the design parameters are changed. The presented method avoids direct differential operation,and thus reduces difficulty for computing the second-order sensitivity matrices of eigenpairs.A numerical example is given to demonstrate application and accuracy of the proposed method.展开更多
In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of ap...In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of apple tree and community, and some physiological indices in fields and by room measurements. The results showed that tree height of high-quality orchard was in the range of 260 to 290 cm, branch angle in 70°-75°, and orchard coverage rate in 75%-94%, and the connec-tion rates between rows and trees were lower. Furthermore, the total branches of mature orchard reached 1.04 ×106 per hm2, while the young orchard was 8.79 ×105 per hm2; the leaves were thick and chlorophyl content was high, with SPAD value at 58.22. Additional y, the photosynthesis of the orchard was strong, and net photo-synthetic rate was 17.48-21.8 μmolCO2/（m2·s）. The proportions of lateral shoot of bearing part were 81% and 75% respectively.展开更多
To design a power source system and mold for electromagnetic soft-contact continuous casting process and to theoretically estimate the heat losses from the charges and the system power, the effect of structure paramet...To design a power source system and mold for electromagnetic soft-contact continuous casting process and to theoretically estimate the heat losses from the charges and the system power, the effect of structure parameters on system power and magnetic flux density distribution was calculated using finite element method. The results show that as for electromagnetic soft-contact continuous casting system with partial-segment type mold, the power consumption is much more than that with a full-segment type mold; about 62% of electric power is dissipated in the mold, and the effective acting range of magnetic field is relatively narrow. Optimizing mold structure is a crucial measure of remarkably reducing mold power consumption and saving electric energy. Increasing slit number, width, and length can remarkably increase the magnetic flux density in the mold and can reduce the electric energy consumption. Among structure parameters, slit number and slit width are relatively more effective to reduce energy consumption. For a round billet electromagnetic continuous casting system with diameter of 178 ram, the reasonable slit number, width, and length are about 24--32, 0. 5--1.0 mm, and 160 mm, respectively.展开更多
Based on the numerical simulation analysis,structure parameters of the high pressure fuel pump and common rail as well as flow limiter are designed and the GD-1 high pressure common rail fuel injection system is self-...Based on the numerical simulation analysis,structure parameters of the high pressure fuel pump and common rail as well as flow limiter are designed and the GD-1 high pressure common rail fuel injection system is self-developed.Fuel injection characteristics experiment is performed on the GD-1 system.And double-factor variance analysis is applied to investigate the influence of the rail pressure and injection pulse width on the consistency of fuel injection quantity,thus to test whether the design of structure parameters is sound accordingly.The results of experiment and test show that rail pressure and injection pulse width as well as their mutual-effect have no influence on the injection quantity consistency,which proves that the structure parameters design is successful and performance of GD-1 system is sound.展开更多
Stope mining design is a very important and complicated task in daily production design and technical management of an underground mine.Based on workface technology and human-computer interaction technology,this study...Stope mining design is a very important and complicated task in daily production design and technical management of an underground mine.Based on workface technology and human-computer interaction technology,this study introduces a method of 3D parametric design for the irregular structure of stope bottoms,and focuses on solving technical problems in surface modeling of stope bottom structure.Optimization of the minimum span length algorithm(MSLA) and the shortest path search algorithm(SPSA) is conducted to solve the problem of contour-line based instant modeling of stope bottom structures,which makes possible the 3D parametric design for irregular structure of stope bottom.Implementation process and relevant methods of the proposed algorithms are also presented.Feasibility and reliability of the proposed modeling method are testified in a case study.In practice,the proposed 3 D parameterization design method for irregular structure stope bottom proves to be very helpful to precise 3D parametric design.This method is capable of contributing to improved efficiency and precision of stope design,and is worthy of promotion.展开更多
Vertical picking method is a predominate method used to harvest cotton crop.However,a vertical picking method may cause spindle bending of the cotton picker if spindles collide with stones on the cotton field.Thus,how...Vertical picking method is a predominate method used to harvest cotton crop.However,a vertical picking method may cause spindle bending of the cotton picker if spindles collide with stones on the cotton field.Thus,how to realize a precise height control of the cotton picker is a crucial issue to be solved.The objective of this study is to design a height control system to avoid the collision.To design it,the mathematical models are established first.Then a multi-objective optimization model represented by structure parameters and control parameters is proposed to take the pressure of chamber without piston,response time and displacement error of the height control system as the opti-mization objectives.An integrated optimization approach that combines optimization via simulation,particle swarm optimization and simulated annealing is proposed to solve the model.Simulation and experimental test results show that the proposed integrated optimization approach can not only reduce the pressure of chamber without piston,but also decrease the response time and displacement error of the height control system.展开更多
The bending section of tube between the bending die and the guider is in a less constrained state during the free bending process.The free bending dies have the important impact on the plastic deformation behavior and...The bending section of tube between the bending die and the guider is in a less constrained state during the free bending process.The free bending dies have the important impact on the plastic deformation behavior and the forming quality of tube.To study the evolution law of the deformation behavior of tube with the die structure parameters and optimize the free bending die parameters,the free bending experiments and the corresponding numerical simulations were carried out.The design principle of free bending die was illustrated.The free bending experiment was conducted to verify the reliability of the numerical simulation method.Based on the numerical simulation results,the influence of the distance between the center point of bending die and the front end of guider on the forming quality of bent tube is more obvious than that of the fillet of guider.However,the fillet of bending die hardly affects the stress and strain distribution and the evolution of the wall thickness.Finally,the free bending experiments with the newly determined free bending dies were conducted.The ultimate bending radius of bent tube is reduced and the forming quality is improved.展开更多
The initial efficiency is a very important criterion for carbon anode material of Li-ion battery.The relationship between initial efficiency and structure parameters of carbon anode material of Li-ion battery was inve...The initial efficiency is a very important criterion for carbon anode material of Li-ion battery.The relationship between initial efficiency and structure parameters of carbon anode material of Li-ion battery was investigated by an artificial intelligence approach called Random Forests using D10,D50,D90,BET specific surface area and TP density as inputs,initial efficiency as output.The results give good classification performance with 91%accuracy.The variable importance analysis results show the impact of 5 variables on the initial efficiency descends in the order of D90,TP density,BET specific surface area,D50 and D10;smaller D90 and larger TP density have positive impact on initial efficiency.The contribution of BET specific surface area on classification is only 18.74%,which indicates the shortcoming of BET specific surface area as a widely used parameter for initial efficiency evaluation.展开更多
It is regretted that the author corrections requested at the proof stage were not made accurately. There are some incorrect typings in two equations which will lead to inaccurate results if readers perform calculation...It is regretted that the author corrections requested at the proof stage were not made accurately. There are some incorrect typings in two equations which will lead to inaccurate results if readers perform calculations directly展开更多
In this paper, based on the second-order Taylor series expansion and the difference of convex functions algo- rithm for quadratic problems with box constraints （the DCA for QB）, a new method is proposed to solve the...In this paper, based on the second-order Taylor series expansion and the difference of convex functions algo- rithm for quadratic problems with box constraints （the DCA for QB）, a new method is proposed to solve the static response problem of structures with fairly large uncertainties in interval parameters. Although current methods are effective for solving the static response problem of structures with interval parameters with small uncertainties, these methods may fail to estimate the region of the static response of uncertain structures if the uncertainties in the parameters are fairly large. To resolve this problem, first, the general expression of the static response of structures in terms of structural parameters is derived based on the second-order Taylor series expansion. Then the problem of determining the bounds of the static response of uncertain structures is transformed into a series of quadratic problems with box constraints. These quadratic problems with box constraints can be solved using the DCA approach effectively. The numerical examples are given to illustrate the accuracy and the efficiency of the proposed method when comparing with other existing methods.展开更多
Textured surfaces are widely used in engineering components as they can improve tribological properties of sliding contacts, while the detailed behaviors of nanoscale reciprocating sliding contacts of textured surface...Textured surfaces are widely used in engineering components as they can improve tribological properties of sliding contacts, while the detailed behaviors of nanoscale reciprocating sliding contacts of textured surfaces are still lack of study. By using multiscale method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. The influence of indentation depth, texture shape, texture spacing, and tip radius on the average friction forces and the running-in stages is studied. The results show that the lowest indentation depth can make all the four textured surfaces reach steady state. Surfaces with right-angled trapezoid textures on the right side are better for reducing the running-in stage, and surfaces with right-angled trapezoid textures on the left side are better to reduce wear. Compared with other textured surfaces, the total average friction forces can be reduced by 82.94%–91.49% for the case of the contact between the tip with radius R = 60rand the isosceles trapezoid textured surface. Besides,the total average friction forces increase with the tip radii due to that bigger tip will induce higher contact areas. This research proposes a detailed study on nanoscale reciprocating sliding contacts of textured surfaces, to contribute to design textured surfaces, reduce friction and wear.展开更多
We determine structure parameters of the highest occupied molecular orbital(HOMO)of 27 dimers for the molecular tunneling ionization(so called MO-ADK)model of Tong et al.[Phys.Rev.A 66(2002)033402].The molecular wave ...We determine structure parameters of the highest occupied molecular orbital(HOMO)of 27 dimers for the molecular tunneling ionization(so called MO-ADK)model of Tong et al.[Phys.Rev.A 66(2002)033402].The molecular wave functions with correct asymptotic behavior are obtained by solving the time-independent Schr(o|¨)dinger equation with B-spline functions and molecular potentials which are numerically created using the density functional theory.We examine the alignment-dependent tunneling ionization probabilities from MO-ADK model for several molecules by comparing with the molecular strong-field approximation(MO-SFA)calculations.We show the molecular PerelomovPopov-Terent'ev(MO-PPT)can successfully give the laser wavelength dependence of ionization rates(or probabilities).Based on the MO-PPT model,two diatomic molecules having valence orbital with antibonding systems(i.e.,Cl_2,Ne_2)show strong ionization suppression when compared with their corresponding closest companion atoms.展开更多
The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor （AI）, such as the effective inductanc...The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor （AI）, such as the effective inductance Ls, quality factor Q, and self-resonant frequency too is analyzed based on 0.35%tm SiGe BiCMOS process. The simulation results show that for AI operated under fixed current density Jc, the HBT lateral structure parameters have significant effect on Ls but little influence on Q and 090, and the larger Ls can be realized by the narrow, short emitter stripe and few emitter stripes of SiGe HBTs. On the other hand, for AI with fixed HBT size, smaller Jc is beneficial for AI to obtain larger Ls, but with a cost of smaller Q and 090. In addition, under the fixed collector current Ic, the larger the size of HBT is, the larger Ls becomes, but the smaller Q and ab become. The obtained results provide a reference for selecting geometry of transistors and operational condition in the design of active inductors.展开更多
In the molecular Ammosov–Delone–Krainov(MO-ADK) model of Tong et al. [Phys. Rev. A 66(2002)033402], the ionization rate depends on the structure parameters of the molecular orbital from which the electron is removed...In the molecular Ammosov–Delone–Krainov(MO-ADK) model of Tong et al. [Phys. Rev. A 66(2002)033402], the ionization rate depends on the structure parameters of the molecular orbital from which the electron is removed. We determine systematically and tabulate accurate structure parameters of the highest occupied molecular orbital(HOMO) for 123 gas-phase linear molecules by solving time-independent Schr¨odinger equation with B-spline functions and molecular potentials which are constructed numerically using the modified Leeuwen–Baerends(LBα)model.展开更多
The Ammosov–Delone–Krainov(ADK) and Perelomov–Popov–Terent'ev(PPT) ionization models were widely used in strong-field physics and attosecond science due to their many attractive advantages such as simpler anal...The Ammosov–Delone–Krainov(ADK) and Perelomov–Popov–Terent'ev(PPT) ionization models were widely used in strong-field physics and attosecond science due to their many attractive advantages such as simpler analytical formula, less computational demands, and satisfied accuracy of ionization rate. Based on the density-functional theory, we systematically determine accurate structure parameters of 25 atoms, 24 positive ions and 13 negative ions and tabulate for future applications. The wave function with correct asymptotic behavior is obtained by solving the time-independent Schr?dinger equation with B-spline basis sets and the accurate structure parameters are extracted from this wave function in the asymptotic region. The accuracies of structure parameters are carefully examined by comparing the ionization probabilities(or yields) calculated by PPT and ADK models with those of solving the threedimensional time-dependent Schr?dinger equation and the experimental data.展开更多
X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystal...X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined.展开更多
Existing imaging techniques cannot simultaneously achieve high resolution and a wide field of view,and manual multi-mineral segmentation in shale lacks precision.To address these limitations,we propose a comprehensive...Existing imaging techniques cannot simultaneously achieve high resolution and a wide field of view,and manual multi-mineral segmentation in shale lacks precision.To address these limitations,we propose a comprehensive framework based on generative adversarial network(GAN)for characterizing pore structure properties of shale,which incorporates image augmentation,super-resolution reconstruction,and multi-mineral auto-segmentation.Using real 2D and 3D shale images,the framework was assessed through correlation function,entropy,porosity,pore size distribution,and permeability.The application results show that this framework enables the enhancement of 3D low-resolution digital cores by a scale factor of 8,without paired shale images,effectively reconstructing the unresolved fine-scale pores under a low resolution,rather than merely denoising,deblurring,and edge clarification.The trained GAN-based segmentation model effectively improves manual multi-mineral segmentation results,resulting in a strong resemblance to real samples in terms of pore size distribution and permeability.This framework significantly improves the characterization of complex shale microstructures and can be expanded to other heterogeneous porous media,such as carbonate,coal,and tight sandstone reservoirs.展开更多
The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface...The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface wettability on the boiling characteristics of copper surfaces is studied using molecular dynamics(MD)simulation.The argon is chosen as the coolant,and the wall temperature is 300 K.The main findings and innovations are as follows.(1)Compared to the smooth surface and fin surface,the cylindrical nano cavity obtains the superior boiling performance with earlier onset of nucleate boiling(ONB),larger heat flux because of the higher heat transport rate.(2)The nano cavity with hydrophilicity can improve the response speed and heat dissipation efficiency.Compared to the contact angleθ=121°,the formation times of nucleate bubble and film boiling for theθ=0°are reduced by 90.84%and 93.57%,respectively.(3)A deeper cavity of 3.3 nm is beneficial for triggering boiling and improving the heat dissipation rate.The highest heat flux can be achieved at 21.86 x 10°W/m2,which can meet the cooling requirements of the micro devices with ultra-high heat flux(107-108 W/m2).The coupling effect of nano configuration and surface wettability is illustrated,and the essential reasons for the enhanced heat transport are revealed.The findings can guide the optimization of cooling systems and promote the practical application of phase change liquid cooling in DCs.展开更多
High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional ...High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional mechanical or chemical cleaning techniques.Among the many parameters influencing its performance,the geometry of the nozzle plays a decisive role in governing jet coherence,impact pressure distribution,and overall cleaning efficiency.In this study,a comprehensive numerical and experimental investigation is conducted to elucidate the influence of nozzle geometry on the behavior of high-pressure water jets.Using Computational Fluid Dynamics(CFD)simulations based on the Volume of Fluid(VOF)approach,the jet dynamics and impingement characteristics of three representative nozzle configurations—flat,conical,and tapered—are systematically analyzed.Particular attention is devoted to the tapered nozzle,where variations in the outlet diameter are explored to determine their effect on flow structure,jet stability,and impact performance.The numerical predictions are rigorously validated against experimental measurements,demonstrating excellent quantitative agreement and confirming the robustness of the computational model.Results show that the tapered nozzle,characterized by its elongated conical transition section,promotes a more stable jet core and superior efflux performance compared to flat and conical geometries.Furthermore,the exit diameter is found to exert a profound influence on jet development.At an inlet pressure of 130 MPa,increasing the tapered nozzle's outlet diameter from 0.8 mm to 1.2 mm enlarges the coherent core region,enhances jet stability,and improves hydraulic energy utilization.Under these conditions,the total impact pressure on the target surface increases by 33.14%,while the overall cleaning efficiency improves by 40.44%.展开更多
We considered adding different amounts(1%,2%,3%,and 4%)of EMR to prepare manganese residue polymer magnesium phosphate cement composite(EMR-PMPC).The influence mechanism of EMR doping on the early macroscopic and micr...We considered adding different amounts(1%,2%,3%,and 4%)of EMR to prepare manganese residue polymer magnesium phosphate cement composite(EMR-PMPC).The influence mechanism of EMR doping on the early macroscopic and microscopic pore structure properties of composites was studied by combining macroscopic and microscopic testing methods.The experimental results show that the addition of EMR can improve the working performance of the slurry and enhance the strength in the later stage,the 28 d compressive strength value of the slurry doped with EMR can reach 49.5 MPa.The Mn element and NH4_(+)^(-)N in EMR react with MgO in the raw material to produce Struvite and Mn(OH)_(2)and Mn_(3)(PO_(4))·6H_(2)O gel,the hydration products coexist with each other and lap each other to form a dense microfine structure and effectively refine the pores.The hydration process consists of five stages,mainly concentrated in the first 10 h or less to exothermic mainly,infrared spectral absorption band is mainly composed of O-H bond,H-O-H bond,PO_(4)bond and metal oxygen bond 3 parts,EMR makes the wave number of the absorption band from the ground wave number to the high wave number.EMR doping T_(2)spectral relaxation time will lag behind,the pore size distribution changes.The total porosity and bound fluid saturation decrease with increasing,the free fluid saturation shows the opposite trend,the permeability decreases and then increases.展开更多
基金Project supported by the 985-Engineering Innovation of Graduate Students of Jilin Universitythe Science and Technology Development Foundation of Jilin Province(20070541)
文摘This paper presents methods for computing a second-order sensitivity matrix and the Hessian matrix of eigenvalues and eigenvectors of multiple parameter structures. Second-order perturbations of eigenvalues and eigenvectors are transformed into multiple parameter forms,and the second-order perturbation sensitivity matrices of eigenvalues and eigenvectors are developed.With these formulations,the efficient methods based on the second-order Taylor expansion and second-order perturbation are obtained to estimate changes of eigenvalues and eigenvectors when the design parameters are changed. The presented method avoids direct differential operation,and thus reduces difficulty for computing the second-order sensitivity matrices of eigenpairs.A numerical example is given to demonstrate application and accuracy of the proposed method.
基金Supported by Special Fund for Modern Agricultural Industry Technology System(CARS-28)~~
文摘In order to research environment parameters and physiological indices of high-quality and high-yield apple trees, two orchards with young and mature apples trees were investigated to explore structural parameter of apple tree and community, and some physiological indices in fields and by room measurements. The results showed that tree height of high-quality orchard was in the range of 260 to 290 cm, branch angle in 70°-75°, and orchard coverage rate in 75%-94%, and the connec-tion rates between rows and trees were lower. Furthermore, the total branches of mature orchard reached 1.04 ×106 per hm2, while the young orchard was 8.79 ×105 per hm2; the leaves were thick and chlorophyl content was high, with SPAD value at 58.22. Additional y, the photosynthesis of the orchard was strong, and net photo-synthetic rate was 17.48-21.8 μmolCO2/（m2·s）. The proportions of lateral shoot of bearing part were 81% and 75% respectively.
基金Item Sponsored by National Natural Science Foundation of China(50274203)National High Technology Research and Development Program of China(2001AA337040)
文摘To design a power source system and mold for electromagnetic soft-contact continuous casting process and to theoretically estimate the heat losses from the charges and the system power, the effect of structure parameters on system power and magnetic flux density distribution was calculated using finite element method. The results show that as for electromagnetic soft-contact continuous casting system with partial-segment type mold, the power consumption is much more than that with a full-segment type mold; about 62% of electric power is dissipated in the mold, and the effective acting range of magnetic field is relatively narrow. Optimizing mold structure is a crucial measure of remarkably reducing mold power consumption and saving electric energy. Increasing slit number, width, and length can remarkably increase the magnetic flux density in the mold and can reduce the electric energy consumption. Among structure parameters, slit number and slit width are relatively more effective to reduce energy consumption. For a round billet electromagnetic continuous casting system with diameter of 178 ram, the reasonable slit number, width, and length are about 24--32, 0. 5--1.0 mm, and 160 mm, respectively.
文摘Based on the numerical simulation analysis,structure parameters of the high pressure fuel pump and common rail as well as flow limiter are designed and the GD-1 high pressure common rail fuel injection system is self-developed.Fuel injection characteristics experiment is performed on the GD-1 system.And double-factor variance analysis is applied to investigate the influence of the rail pressure and injection pulse width on the consistency of fuel injection quantity,thus to test whether the design of structure parameters is sound accordingly.The results of experiment and test show that rail pressure and injection pulse width as well as their mutual-effect have no influence on the injection quantity consistency,which proves that the structure parameters design is successful and performance of GD-1 system is sound.
基金Supported by the National High Technology Research and Development Programme of China(No.2011AA060407)Yunnan Province Science and Technology Innovation Platform Construction Plans,China(No.2010DH005)
文摘Stope mining design is a very important and complicated task in daily production design and technical management of an underground mine.Based on workface technology and human-computer interaction technology,this study introduces a method of 3D parametric design for the irregular structure of stope bottoms,and focuses on solving technical problems in surface modeling of stope bottom structure.Optimization of the minimum span length algorithm(MSLA) and the shortest path search algorithm(SPSA) is conducted to solve the problem of contour-line based instant modeling of stope bottom structures,which makes possible the 3D parametric design for irregular structure of stope bottom.Implementation process and relevant methods of the proposed algorithms are also presented.Feasibility and reliability of the proposed modeling method are testified in a case study.In practice,the proposed 3 D parameterization design method for irregular structure stope bottom proves to be very helpful to precise 3D parametric design.This method is capable of contributing to improved efficiency and precision of stope design,and is worthy of promotion.
基金Supported by National Natural Science Foundation of China(Grant No.51905448)Chongqing Technology Innovation and Application Program of China(Grant No.cstc2018jszx-cyzdX0183)Fundamental Research Funds for the Central Universities of China(Grant No.SWU119060).
文摘Vertical picking method is a predominate method used to harvest cotton crop.However,a vertical picking method may cause spindle bending of the cotton picker if spindles collide with stones on the cotton field.Thus,how to realize a precise height control of the cotton picker is a crucial issue to be solved.The objective of this study is to design a height control system to avoid the collision.To design it,the mathematical models are established first.Then a multi-objective optimization model represented by structure parameters and control parameters is proposed to take the pressure of chamber without piston,response time and displacement error of the height control system as the opti-mization objectives.An integrated optimization approach that combines optimization via simulation,particle swarm optimization and simulated annealing is proposed to solve the model.Simulation and experimental test results show that the proposed integrated optimization approach can not only reduce the pressure of chamber without piston,but also decrease the response time and displacement error of the height control system.
基金The investigation was supported from the Opening Project of State Key Lab of Digital Manufacturing Equipment&Technology(No.DMETKF2021004)the National Natural Science Foundation of China(Nos.52105360,U1937206,and 52175328)+1 种基金2021 Jiangsu Shuangchuang Talent Program(JSSCBS20210157)Fundamental Research Funds for the Central Universities(No.NS2022061).
文摘The bending section of tube between the bending die and the guider is in a less constrained state during the free bending process.The free bending dies have the important impact on the plastic deformation behavior and the forming quality of tube.To study the evolution law of the deformation behavior of tube with the die structure parameters and optimize the free bending die parameters,the free bending experiments and the corresponding numerical simulations were carried out.The design principle of free bending die was illustrated.The free bending experiment was conducted to verify the reliability of the numerical simulation method.Based on the numerical simulation results,the influence of the distance between the center point of bending die and the front end of guider on the forming quality of bent tube is more obvious than that of the fillet of guider.However,the fillet of bending die hardly affects the stress and strain distribution and the evolution of the wall thickness.Finally,the free bending experiments with the newly determined free bending dies were conducted.The ultimate bending radius of bent tube is reduced and the forming quality is improved.
基金Project(2001AA501433)supported by the National High-Tech Research and Development Program of China
文摘The initial efficiency is a very important criterion for carbon anode material of Li-ion battery.The relationship between initial efficiency and structure parameters of carbon anode material of Li-ion battery was investigated by an artificial intelligence approach called Random Forests using D10,D50,D90,BET specific surface area and TP density as inputs,initial efficiency as output.The results give good classification performance with 91%accuracy.The variable importance analysis results show the impact of 5 variables on the initial efficiency descends in the order of D90,TP density,BET specific surface area,D50 and D10;smaller D90 and larger TP density have positive impact on initial efficiency.The contribution of BET specific surface area on classification is only 18.74%,which indicates the shortcoming of BET specific surface area as a widely used parameter for initial efficiency evaluation.
文摘It is regretted that the author corrections requested at the proof stage were not made accurately. There are some incorrect typings in two equations which will lead to inaccurate results if readers perform calculations directly
基金supported by the National Natural Science Foundation of China (Grants 11002013, 11372025)the Defense Industrial Technology Development Program (Grants A0820132001, JCKY2013601B)+1 种基金the Aeronautical Science Foundation of China (Grant 2012ZA51010)111 Project (Grant B07009) for support
文摘In this paper, based on the second-order Taylor series expansion and the difference of convex functions algo- rithm for quadratic problems with box constraints （the DCA for QB）, a new method is proposed to solve the static response problem of structures with fairly large uncertainties in interval parameters. Although current methods are effective for solving the static response problem of structures with interval parameters with small uncertainties, these methods may fail to estimate the region of the static response of uncertain structures if the uncertainties in the parameters are fairly large. To resolve this problem, first, the general expression of the static response of structures in terms of structural parameters is derived based on the second-order Taylor series expansion. Then the problem of determining the bounds of the static response of uncertain structures is transformed into a series of quadratic problems with box constraints. These quadratic problems with box constraints can be solved using the DCA approach effectively. The numerical examples are given to illustrate the accuracy and the efficiency of the proposed method when comparing with other existing methods.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675429,51205313)Fundamental Research Funds for the Central Universities,China(Grant No.3102014JCS05009)the 111 Project,China(Grant No.B13044)
文摘Textured surfaces are widely used in engineering components as they can improve tribological properties of sliding contacts, while the detailed behaviors of nanoscale reciprocating sliding contacts of textured surfaces are still lack of study. By using multiscale method, two dimensional nanoscale reciprocating sliding contacts of textured surfaces are investigated. The influence of indentation depth, texture shape, texture spacing, and tip radius on the average friction forces and the running-in stages is studied. The results show that the lowest indentation depth can make all the four textured surfaces reach steady state. Surfaces with right-angled trapezoid textures on the right side are better for reducing the running-in stage, and surfaces with right-angled trapezoid textures on the left side are better to reduce wear. Compared with other textured surfaces, the total average friction forces can be reduced by 82.94%–91.49% for the case of the contact between the tip with radius R = 60rand the isosceles trapezoid textured surface. Besides,the total average friction forces increase with the tip radii due to that bigger tip will induce higher contact areas. This research proposes a detailed study on nanoscale reciprocating sliding contacts of textured surfaces, to contribute to design textured surfaces, reduce friction and wear.
基金Supported by National Natural Science Foundation of China under Grant Nos.11164025,11264036,11465016,11364038the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20116203120001the Basic Scientific Research Foundation for Institution of Higher Learning of Gansu Province
文摘We determine structure parameters of the highest occupied molecular orbital(HOMO)of 27 dimers for the molecular tunneling ionization(so called MO-ADK)model of Tong et al.[Phys.Rev.A 66(2002)033402].The molecular wave functions with correct asymptotic behavior are obtained by solving the time-independent Schr(o|¨)dinger equation with B-spline functions and molecular potentials which are numerically created using the density functional theory.We examine the alignment-dependent tunneling ionization probabilities from MO-ADK model for several molecules by comparing with the molecular strong-field approximation(MO-SFA)calculations.We show the molecular PerelomovPopov-Terent'ev(MO-PPT)can successfully give the laser wavelength dependence of ionization rates(or probabilities).Based on the MO-PPT model,two diatomic molecules having valence orbital with antibonding systems(i.e.,Cl_2,Ne_2)show strong ionization suppression when compared with their corresponding closest companion atoms.
基金Project supported by the Natural Science Foundation of BeijingChina(Grant Nos.4142007 and 4122014)+1 种基金the National Natural Science Foundation of China(Grant No.61574010)the Higher Educational Science and Technology Program of Shandong Province,China(Grant No.J13LN09)
文摘The effect of lateral structure parameters of transistors including emitter width, emitter length, and emitter stripe number on the performance parameters of the active inductor （AI）, such as the effective inductance Ls, quality factor Q, and self-resonant frequency too is analyzed based on 0.35%tm SiGe BiCMOS process. The simulation results show that for AI operated under fixed current density Jc, the HBT lateral structure parameters have significant effect on Ls but little influence on Q and 090, and the larger Ls can be realized by the narrow, short emitter stripe and few emitter stripes of SiGe HBTs. On the other hand, for AI with fixed HBT size, smaller Jc is beneficial for AI to obtain larger Ls, but with a cost of smaller Q and 090. In addition, under the fixed collector current Ic, the larger the size of HBT is, the larger Ls becomes, but the smaller Q and ab become. The obtained results provide a reference for selecting geometry of transistors and operational condition in the design of active inductors.
基金Supported by National Natural Science Foundation of China under Grant Nos.11664035,11674268,11465016,11364038,11364039the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20116203120001the Basic Scientific Research Foundation for Institution of Higher Learning of Gansu Province
文摘In the molecular Ammosov–Delone–Krainov(MO-ADK) model of Tong et al. [Phys. Rev. A 66(2002)033402], the ionization rate depends on the structure parameters of the molecular orbital from which the electron is removed. We determine systematically and tabulate accurate structure parameters of the highest occupied molecular orbital(HOMO) for 123 gas-phase linear molecules by solving time-independent Schr¨odinger equation with B-spline functions and molecular potentials which are constructed numerically using the modified Leeuwen–Baerends(LBα)model.
基金Project supported by the National Natural Science Foundation of China under Grant Nos. 11664035, 11864037 and 11765018the Foundation of Northwest Normal University (No. NWNU-LKQN-17-1)。
文摘The Ammosov–Delone–Krainov(ADK) and Perelomov–Popov–Terent'ev(PPT) ionization models were widely used in strong-field physics and attosecond science due to their many attractive advantages such as simpler analytical formula, less computational demands, and satisfied accuracy of ionization rate. Based on the density-functional theory, we systematically determine accurate structure parameters of 25 atoms, 24 positive ions and 13 negative ions and tabulate for future applications. The wave function with correct asymptotic behavior is obtained by solving the time-independent Schr?dinger equation with B-spline basis sets and the accurate structure parameters are extracted from this wave function in the asymptotic region. The accuracies of structure parameters are carefully examined by comparing the ionization probabilities(or yields) calculated by PPT and ADK models with those of solving the threedimensional time-dependent Schr?dinger equation and the experimental data.
文摘X-ray diffraction line profiles of low density polyethylene(LDPE)/ (ethylene-propylene-octene-1)copolymer(EPO)blends have been analyzed with variance range function method.Theories for determining the microparacrystallite size and the distortion parameter from single reflection have been described,and the value of these two parameters at (110)and(200)directions have been determined.
基金Supported by the National Natural Science Foundation of China(U23A20595,52034010,52288101)National Key Research and Development Program of China(2022YFE0203400)+1 种基金Shandong Provincial Natural Science Foundation(ZR2024ZD17)Fundamental Research Funds for the Central Universities(23CX10004A).
文摘Existing imaging techniques cannot simultaneously achieve high resolution and a wide field of view,and manual multi-mineral segmentation in shale lacks precision.To address these limitations,we propose a comprehensive framework based on generative adversarial network(GAN)for characterizing pore structure properties of shale,which incorporates image augmentation,super-resolution reconstruction,and multi-mineral auto-segmentation.Using real 2D and 3D shale images,the framework was assessed through correlation function,entropy,porosity,pore size distribution,and permeability.The application results show that this framework enables the enhancement of 3D low-resolution digital cores by a scale factor of 8,without paired shale images,effectively reconstructing the unresolved fine-scale pores under a low resolution,rather than merely denoising,deblurring,and edge clarification.The trained GAN-based segmentation model effectively improves manual multi-mineral segmentation results,resulting in a strong resemblance to real samples in terms of pore size distribution and permeability.This framework significantly improves the characterization of complex shale microstructures and can be expanded to other heterogeneous porous media,such as carbonate,coal,and tight sandstone reservoirs.
基金the National Natural Science Foundation of China (No. 52406191, No. 52408123)the Science and Technology Project of Tianjin (No. 24YDTPJC00680).
文摘The local overheating issue is a serious threat to the safe operation of data centers(DCs).The chip level liquid cooling with pool boiling is expected to solve this problem.The effect of nano configuration and surface wettability on the boiling characteristics of copper surfaces is studied using molecular dynamics(MD)simulation.The argon is chosen as the coolant,and the wall temperature is 300 K.The main findings and innovations are as follows.(1)Compared to the smooth surface and fin surface,the cylindrical nano cavity obtains the superior boiling performance with earlier onset of nucleate boiling(ONB),larger heat flux because of the higher heat transport rate.(2)The nano cavity with hydrophilicity can improve the response speed and heat dissipation efficiency.Compared to the contact angleθ=121°,the formation times of nucleate bubble and film boiling for theθ=0°are reduced by 90.84%and 93.57%,respectively.(3)A deeper cavity of 3.3 nm is beneficial for triggering boiling and improving the heat dissipation rate.The highest heat flux can be achieved at 21.86 x 10°W/m2,which can meet the cooling requirements of the micro devices with ultra-high heat flux(107-108 W/m2).The coupling effect of nano configuration and surface wettability is illustrated,and the essential reasons for the enhanced heat transport are revealed.The findings can guide the optimization of cooling systems and promote the practical application of phase change liquid cooling in DCs.
基金the Natural Science Foundation of Shandong Province,China(No.ZR2021QE157).
文摘High-pressure water jet technology has emerged as a highly effective method for removing industrial-scale deposits from pipelines,offering a clean,efficient,and environmentally sustainable alternative to conventional mechanical or chemical cleaning techniques.Among the many parameters influencing its performance,the geometry of the nozzle plays a decisive role in governing jet coherence,impact pressure distribution,and overall cleaning efficiency.In this study,a comprehensive numerical and experimental investigation is conducted to elucidate the influence of nozzle geometry on the behavior of high-pressure water jets.Using Computational Fluid Dynamics(CFD)simulations based on the Volume of Fluid(VOF)approach,the jet dynamics and impingement characteristics of three representative nozzle configurations—flat,conical,and tapered—are systematically analyzed.Particular attention is devoted to the tapered nozzle,where variations in the outlet diameter are explored to determine their effect on flow structure,jet stability,and impact performance.The numerical predictions are rigorously validated against experimental measurements,demonstrating excellent quantitative agreement and confirming the robustness of the computational model.Results show that the tapered nozzle,characterized by its elongated conical transition section,promotes a more stable jet core and superior efflux performance compared to flat and conical geometries.Furthermore,the exit diameter is found to exert a profound influence on jet development.At an inlet pressure of 130 MPa,increasing the tapered nozzle's outlet diameter from 0.8 mm to 1.2 mm enlarges the coherent core region,enhances jet stability,and improves hydraulic energy utilization.Under these conditions,the total impact pressure on the target surface increases by 33.14%,while the overall cleaning efficiency improves by 40.44%.
基金Funden by the National Natural Science Foundation of China(Nos.51868044 and 52178216)the Basic Research Program of Qinghai Province(No.2022-ZJ-921)+2 种基金“the Innovation Star”Project for Excellent Postgraduates in Gansu Province(No.2022-CXZX-450)the Hongliu First-class Discipline Construction Program of Lanzhou University of TechnologyScience and Technology Project of Gansu Provincial Department of Transportation(No.2022-23)。
文摘We considered adding different amounts(1%,2%,3%,and 4%)of EMR to prepare manganese residue polymer magnesium phosphate cement composite(EMR-PMPC).The influence mechanism of EMR doping on the early macroscopic and microscopic pore structure properties of composites was studied by combining macroscopic and microscopic testing methods.The experimental results show that the addition of EMR can improve the working performance of the slurry and enhance the strength in the later stage,the 28 d compressive strength value of the slurry doped with EMR can reach 49.5 MPa.The Mn element and NH4_(+)^(-)N in EMR react with MgO in the raw material to produce Struvite and Mn(OH)_(2)and Mn_(3)(PO_(4))·6H_(2)O gel,the hydration products coexist with each other and lap each other to form a dense microfine structure and effectively refine the pores.The hydration process consists of five stages,mainly concentrated in the first 10 h or less to exothermic mainly,infrared spectral absorption band is mainly composed of O-H bond,H-O-H bond,PO_(4)bond and metal oxygen bond 3 parts,EMR makes the wave number of the absorption band from the ground wave number to the high wave number.EMR doping T_(2)spectral relaxation time will lag behind,the pore size distribution changes.The total porosity and bound fluid saturation decrease with increasing,the free fluid saturation shows the opposite trend,the permeability decreases and then increases.
