To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains i...To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.展开更多
Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for ...Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.展开更多
A hybrid fiber-reinforced polymer(HFRP)continuous sucker rod,comprising a carbon fiber-reinforced polymer(CFRP)core layer,a glass fiber-reinforced polymer(GFRP)winding layer,and a GFRP coating layer(CFRP:GFRP=2:3),has...A hybrid fiber-reinforced polymer(HFRP)continuous sucker rod,comprising a carbon fiber-reinforced polymer(CFRP)core layer,a glass fiber-reinforced polymer(GFRP)winding layer,and a GFRP coating layer(CFRP:GFRP=2:3),has been developed and widely used in oilfield extraction due to its lower specific gravity,enhanced corrosion resistance,and superior strength.However,HFRP rod joints and their adjacent sections are prone to multi-mode failures,including fracture,debonding,and cracking.Due to the complexity of joint structure and the coupling of tension,bending,and torsion,the failure mechanism is unclear.To address this issue,a dual-scale failure assessment methodology for HFRP rods was proposed,utilizing both macro and meso finite element models(FEM).This methodology was validated through tensile and bending experiments,which yielded critical loads for theφ22 mm HFRP rod:a tensile load of 340.2 kN,a torque of 132.3 N m,and a bending moment of 1192.4 N m.Additionally,a comprehensive FEM of the joint was established,which identified potential failure points at the necking of the rotary joint,resin adhesive and the HFRP rod cross-section at the first groove tip.These failure modes closely matched the experimental observations.Furthermore,the simulation results show that stress concentration at the joint reduced the tensile,bending,and torsional strengths of the HFRP rod to 61%,12%,and 82%of their original values,respectively.The effects of bending moments and torque on the tensile strength of HFRP rods were subsequently explored,leading to the development of an equivalent fatigue assessment method for HFRP rod joints.This method,based on the fatigue characteristics of HFRP rods and joint components,reveals that the primary cause of joint failure is the susceptibility of both the joint and the HFRP rod to bending moments and torque induced by dynamic buckling of the sucker rod string(SRS).Using this method,the fatigue ultimate axial force of theφ22 mm HFRP joint was determined to be 91.5 kN,with corresponding fatigue ultimate torque and bending moment under an axial force of 62.4 kN being 89.3 N m and 71.5 N m,respectively.Finally,a design method incorporating a concentrated weighting strategy for HFRP-steel mixed rods was proposed to enhance their service life,and its effectiveness was demonstrated through on-site testing.展开更多
The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods w...The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.展开更多
Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-...Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-ing deformation.Similar to traditional gravity-driven systems,it is constrained by the direction of gravity and cannot be applied in microgravity environments.This study introduces a lateral constraint to a liquid crystal elastomer rod system,enabling self-rotation under lighting from any direction,including horizontal and vertical illumination.Through theoretical modeling,the results indicate that the system can steadily rotate under the combined impacts of lateral forces and vertical illumination.Factors like thermal energy flux,thermal conduc-tivity coefficient,the LCE rod length,contraction coefficient,and friction coefficient affect the angular velocity of the self-rotation.The numerical computations align closely with the experimental data.Our proposed steadily self-rotating system features a simple structure with constant self-rotation.It operates independently of gravity direction,making it an excellent choice for special environments,such as the microgravity conditions on the Moon.The lateral constraint strategy presented in this study offers a general approach to expanding the applica-tions of gravity-driven self-sustained motion,with promising potential,especially in microgravity settings,where its versatility under varying lighting conditions could yield valuable insights.展开更多
In engineering practice,there are many factors causing the vibration to which rods are usually subjected.Generally,the vibration of elastic rods motivated by determined vibration excitations can be controlled effectiv...In engineering practice,there are many factors causing the vibration to which rods are usually subjected.Generally,the vibration of elastic rods motivated by determined vibration excitations can be controlled effectively.However,the working frequency of vibration excitation may vary due to environmental changes,the working conditions of equipment,and other factors.Consequently,it remains a challenge to restrict the longitudinal vibration of elastic rods within a wide frequency band.In order to meet the relevant engineering requirements and address the existing limitations,the longitudinal vibration control of an elastic rod within a wide frequency band is explored in this study through an adjustable stiffness internal support.To achieve this purpose,the variable stiffness longitudinal vibration control theory of the elastic rod is validated.The model of an adjustable stiffness internal support is designed,constructed,and tested,demonstrating that the stiffness coefficients of the adjustable stiffness internal support can be effectively controlled.Through the adjustable stiffness internal support,the experiment on longitudinal vibration control of the elastic rod is designed and performed.It leads to the conclusion that the adjustable stiffness internal support within the adjustable working region is effective in restricting the longitudinal vibration within a wide frequency band of the elastic rod.Furthermore,the existence of the adjustable working region in the experiment demonstrates the effectiveness of the adjustable stiffness internal support intended for the variable stiffness longitudinal vibration control of an elastic rod.To sum up,this study provides insights into an adjustable stiffness mechanism for applying the theory of variable stiffness longitudinal vibration control on an elastic rod in engineering practice.展开更多
Accurate measurement of anchor rod length is crucial for ensuring structural safety in tunnel engineering,yet conventional destructive techniques face limitations in efficiency and adaptability to complex underground ...Accurate measurement of anchor rod length is crucial for ensuring structural safety in tunnel engineering,yet conventional destructive techniques face limitations in efficiency and adaptability to complex underground environments.This study presents a novel wireless instrument based on the standing wave principle to enable remote,non-destructive length assessment.The system employs a master-slave architecture,where a handheld transmitter unit initiates measurements through robust 433 MHz wireless communication,optimized for signal penetration in obstructed spaces.The embedded measurement unit,integrated with anchor rods during installation,utilizes frequency-scanning technology to excite structural resonances.By analyzing standing wave characteristics,anchor length is derived from a calibrated frequency-length relationship.Power management adopts a standby-activation strategy to minimize energy consumption while maintaining operational readiness.Experimental validation confirms the system effectively measures anchor lengths with high precision and maintains reliable signal transmission through thick concrete barriers,demonstrating suitability for tunnel deployment.The non-destructive approach eliminates structural damage risks associated with traditional pull-out tests,while wireless operation enhances inspection efficiency in confined spaces.Thiswork establishes a paradigmfor embedded structural healthmonitoring in tunneling,offering significant improvements over existing methods in safety,cost-effectiveness,and scalability.The technology holds promise for broad applications in mining,underground infrastructure,and geotechnical engineering.展开更多
In this paper,we present a high peak power passively Q-switched intracavity frequency-doubled green laser based on an efficient LED-pumped Nd:YAG dual-rod laser module.In quasi-continuous wave(QCW)running operation,th...In this paper,we present a high peak power passively Q-switched intracavity frequency-doubled green laser based on an efficient LED-pumped Nd:YAG dual-rod laser module.In quasi-continuous wave(QCW)running operation,the average output power of the fundamental laser at 1064 nm reaches as high as 20.98 W at a repetition rate of 50 Hz with a maximum single pulse energy of 419.6 mJ,corresponding to a maximum optical conversion efficiency of 38.8%and a slope efficiency of 41%.展开更多
h-BN rods modified low-carbon alumina-carbon(Al_(2)O_(3)-C)refractories were prepared,and the effect of h-BN rod addition on the high-temperature properties was investigated and compared with commercial h-BN flake,car...h-BN rods modified low-carbon alumina-carbon(Al_(2)O_(3)-C)refractories were prepared,and the effect of h-BN rod addition on the high-temperature properties was investigated and compared with commercial h-BN flake,carbon black,and carbon nanotubes additives.The results demonstrated that Al_(2)O_(3)-C refractories containing h-BN rods exhibited optimal high-temperature service performances,including 25%higher hot modulus of rupture,21.3%higher thermal shock strength residual ratio,20.9%lower in oxidation and 44.3%less in slag corrosion,compared to the counterpart specimens without additives.Moreover,benefiting from the synergistic enhancement of the rod-like h-BN and in-situ generated SiC whiskers,the high-temperature service performances of h-BN rods containing specimens outperformed counterpart specimens containing commercial h-BN flake,carbon black,and carbon nanotubes,respectively.展开更多
The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computatio...The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.展开更多
The bimetallic composite rods prepared by co-extrusion have good mechanical properties,but their compressive deformation behaviors have rarely been studied.This paper primarily investigates the compressive deformation...The bimetallic composite rods prepared by co-extrusion have good mechanical properties,but their compressive deformation behaviors have rarely been studied.This paper primarily investigates the compressive deformation behavior of the AZ31/Mg-Gd-Y composite rod,analyzes the differences between its compressive deformation behavior and that of AZ31,and systematically studies the compressive deformation mechanisms of various regions in the composite rod,as well as the texture evolution and{10-12}twin evolution during the compression process.The results reveal that the AZ31/Mg-Gd-Y composite rods exhibit excellent metallurgical bonding,with the interface remaining intact even under a 9%compressive strain.In the compression process,AZ31 initiates yielding earlier than the AZ31/Mg-Gd-Y composite rods,exhibiting a relatively lower yield strength,whereas both show comparable plasticity.The deformation behavior of the AZ31/Mg-Gd-Y composite rod is governed by a combination of basal a slip and{10-12}-1011 tension twinning during compression along the ED(extrusion direction).With increasing compressive strain,the number of{10-12}twins in the AZ31 region(A/G-AZ31)of the AZ31/Mg-Gd-Y composite rod increases significantly,leading to changes in grain orientation,whereas the Mg-Gd-Y region(A/G-Mg-Gd-Y)of the composite rod shows no significant change.In addition,the A/G-Mg-Gd-Y significantly inhibits the nucleation and growth of{10-12}twins in A/G-AZ31 during compression,and thus the texture hardening generated by{10-12}twins make the work hardening behavior of the AZ31/Mg-Gd-Y composite rods different from that of AZ31.展开更多
An exact forecast of the failures of a sucker rod-pumped well in a production area means much for an oilfield’s operation budget, operational arrangement and production plan. In this paper, according to the characte...An exact forecast of the failures of a sucker rod-pumped well in a production area means much for an oilfield’s operation budget, operational arrangement and production plan. In this paper, according to the characteristics of failed sucker rod-pumped well randomness and strong outburst, with the gray GM (1,1) forecast model and the Markov forecast model combined, gray GM (1,1) forecast model is utilized to handle the primary data of an oilfield, and Markov forecast model is utilized to calculate the state transfer probability of forecast value. Then, the gray Markov forecast model considering the influence of randomness factors is formed. Field results prove that the calculation precision of this method is higher and the practicability is greater.展开更多
目的 :探讨应用Smiley face rod固定系统治疗L5椎弓峡部裂的临床疗效。方法:2016年1月~2017年6月,我科采用Smiley face rod固定系统节段内固定植骨融合治疗腰椎峡部裂患者18例,男13例,女5例,年龄28.2±3.2岁(25~32岁),术前平均病程...目的 :探讨应用Smiley face rod固定系统治疗L5椎弓峡部裂的临床疗效。方法:2016年1月~2017年6月,我科采用Smiley face rod固定系统节段内固定植骨融合治疗腰椎峡部裂患者18例,男13例,女5例,年龄28.2±3.2岁(25~32岁),术前平均病程为16.3±5.7个月(7~24个月)。峡部裂节段均位于L5。术后3个月、1年时进行随访,对患者进行疼痛视觉模拟评分(visual analogue scale,VAS)及Oswestry功能障碍指数(Oswestry disability index,ODI)评定,评价其临床治疗效果。行X线、CT等检查,分析术前和术后L5/S1椎间活动度变化及椎间不稳发生率变化情况,并评价患者术后植骨融合情况。结果:手术时间平均90.0±24.1min,术中出血量平均140±15ml。平均随访18.5±5.0个月(12~24个月)。术前VAS评分为7.3±2.5分,ODI为(67.0±15.1)%;术后3个月时分别为3.0±1.2分和(17.2±4.5)%,较术前明显改善(P<0.05);术后1年时分别为1.0±0.6分和(9.1±5.3)%,较术后3个月时进一步改善(P<0.05)。术前L5/S1间隙活动度为13.1°±2.1°,存在腰椎不稳或小于Ⅰ度滑脱者共15例(83.3%,15/18);术后1年时分别为9.3°±1.6°和2例(11.1%,2/18),两者之间存在统计学差异(P<0.05)。术后1年时随访患者峡部裂均获得骨性愈合。结论 :应用Smiley face rod固定系统治疗L5椎弓峡部裂具有创伤小、对神经干扰少、恢复正常的解剖结构、提高椎间稳定性的优点。展开更多
Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properti...Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.展开更多
文摘To ensure the safe transportation of radioactive materials,numerous countries have established specific standards.For the transfer of fissile materials,it is imperative that the material within the packaging remains in a subcritical state during routine,normal,and accidental transport conditions.In the event of an accident,the rods within the storage tank may become rearranged,introducing uncertainty that must be accounted for to ensure that criticality analysis results are conservative.Historically,this uncertainty was addressed overly conservatively due to limited research on non-uniform arrangement scenarios,which proved unsuitable for criticality safety analysis of spent fuel packages.This paper introduced three distinct methods to non-uniformly rearrange fuel rods—Uniform Arrangement by Blocks,Layer-by-Layer Determination,and Birdcage Deformation—and meticulously evaluates the influences of rod rearrangement on the effective multiplication factor of neutrons,k eff,utilizing the Monte Carlo method.Ultimately,this study presents a holistic method capable of encompassing the entire spectrum of potential effects stemming from the rearrangement of fuel rods during rods mispositioning accident.By augmenting the safety margin,this approach proves to be adeptly suited for the criticality safety analysis of nuclear fuel transport containers.
基金supported by Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2020261)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA02010000)the Young Potential Program of Shanghai Institute of Applied Physics,Chinese Academy of Sciences(No.SINAP-YXJH-202412).
文摘Molten salt reactors,being the only reactor type among Generation Ⅳ advanced nuclear reactors that utilize liquid fuels,offer inherent safety,high-temperature,and low-pressure operation,as well as the capability for online fuel reprocessing.However,the fuel-salt flow results in the decay of delayed neutron precursors(DNPs)outside the core,causing fluctuations in the effective delayed neutron fraction and consequently impacting the reactor reactivity.Particularly in accident scenarios—such as a combined pump shutdown and the inability to rapidly scram the reactor—the sole reliance on negative temperature feedback may cause a significant increase in core temperature,posing a threat to reactor safety.To address these problems,this paper introduces an innovative design for a passive fluid-driven suspended control rod(SCR)to dynamically compensate for reactivity fluctuations caused by DNPs flowing with the fuel.The control rod operates passively by leveraging the combined effects of gravity,buoyancy,and fluid dynamic forces,thereby eliminating the need for an external drive mechanism and enabling direct integration within the active region of the core.Using a 150 MWt thorium-based molten salt reactor as the reference design,we develop a mathematical model to systematically analyze the effects of key parameters—including the geometric dimensions and density of the SCR—on its performance.We examine its motion characteristics under different core flow conditions and assess its feasibility for the dynamic compensation of reactivity changes caused by fuel flow.The results of this study demonstrate that the SCR can effectively counteract reactivity fluctuations induced by fuel flow within molten salt reactors.A sensitivity analysis reveals that the SCR’s average density exerts a profound impact on its start-up flow threshold,channel flow rate,resistance to fuel density fluctuations,and response characteristics.This underscores the critical need to optimize this parameter.Moreover,by judiciously selecting the SCR’s length,number of deployed units,and the placement we can achieve the necessary reactivity control while maintaining a favorable balance between neutron economy and heat transfer performance.Ultimately,this paper provides an innovative solution for the passive reactivity control in molten salt reactors,offering significant potential for practical engineering applications.
基金the Fundamental Research Funds for the Central Universities under Grant no.24CX02019Athe Opening Fund of National Engineering Research Center of Marine Geophysical Prospecting and Exploration and Development Equipment under Grant no.24CX02019A。
文摘A hybrid fiber-reinforced polymer(HFRP)continuous sucker rod,comprising a carbon fiber-reinforced polymer(CFRP)core layer,a glass fiber-reinforced polymer(GFRP)winding layer,and a GFRP coating layer(CFRP:GFRP=2:3),has been developed and widely used in oilfield extraction due to its lower specific gravity,enhanced corrosion resistance,and superior strength.However,HFRP rod joints and their adjacent sections are prone to multi-mode failures,including fracture,debonding,and cracking.Due to the complexity of joint structure and the coupling of tension,bending,and torsion,the failure mechanism is unclear.To address this issue,a dual-scale failure assessment methodology for HFRP rods was proposed,utilizing both macro and meso finite element models(FEM).This methodology was validated through tensile and bending experiments,which yielded critical loads for theφ22 mm HFRP rod:a tensile load of 340.2 kN,a torque of 132.3 N m,and a bending moment of 1192.4 N m.Additionally,a comprehensive FEM of the joint was established,which identified potential failure points at the necking of the rotary joint,resin adhesive and the HFRP rod cross-section at the first groove tip.These failure modes closely matched the experimental observations.Furthermore,the simulation results show that stress concentration at the joint reduced the tensile,bending,and torsional strengths of the HFRP rod to 61%,12%,and 82%of their original values,respectively.The effects of bending moments and torque on the tensile strength of HFRP rods were subsequently explored,leading to the development of an equivalent fatigue assessment method for HFRP rod joints.This method,based on the fatigue characteristics of HFRP rods and joint components,reveals that the primary cause of joint failure is the susceptibility of both the joint and the HFRP rod to bending moments and torque induced by dynamic buckling of the sucker rod string(SRS).Using this method,the fatigue ultimate axial force of theφ22 mm HFRP joint was determined to be 91.5 kN,with corresponding fatigue ultimate torque and bending moment under an axial force of 62.4 kN being 89.3 N m and 71.5 N m,respectively.Finally,a design method incorporating a concentrated weighting strategy for HFRP-steel mixed rods was proposed to enhance their service life,and its effectiveness was demonstrated through on-site testing.
基金supported by the general project of the National Natural Science Foundation of China(No.52071042)Chongqing Natural Science Foundation Project,China(Nos.CSTB2023NSCQ-MSX0079,cstc2021ycjh-bgzxm0148)Graduate Student Innovation Program of Chongqing University of Technology,China(No.gzlcx20232008).
文摘The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.
基金supported by the University Natural Science Research Project of Anhui Province(Grant Nos.2022AH040042 and 2022AH020029)the National Natural Science Foundation of China(Grant No.12172001)+1 种基金Anhui Provincial Natural Science Foundation(Grant No.2208085Y01)the Housing and Urban-Rural Development Science and Technology Project of Anhui Province(Grant No.2022-YF069).
文摘Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-ing deformation.Similar to traditional gravity-driven systems,it is constrained by the direction of gravity and cannot be applied in microgravity environments.This study introduces a lateral constraint to a liquid crystal elastomer rod system,enabling self-rotation under lighting from any direction,including horizontal and vertical illumination.Through theoretical modeling,the results indicate that the system can steadily rotate under the combined impacts of lateral forces and vertical illumination.Factors like thermal energy flux,thermal conduc-tivity coefficient,the LCE rod length,contraction coefficient,and friction coefficient affect the angular velocity of the self-rotation.The numerical computations align closely with the experimental data.Our proposed steadily self-rotating system features a simple structure with constant self-rotation.It operates independently of gravity direction,making it an excellent choice for special environments,such as the microgravity conditions on the Moon.The lateral constraint strategy presented in this study offers a general approach to expanding the applica-tions of gravity-driven self-sustained motion,with promising potential,especially in microgravity settings,where its versatility under varying lighting conditions could yield valuable insights.
基金Supported by the Fundamental Research Project of SIA(Grant No.2022JC1G04)National Natural Science Foundation of China(Grant Nos.52401364 and 52205091)。
文摘In engineering practice,there are many factors causing the vibration to which rods are usually subjected.Generally,the vibration of elastic rods motivated by determined vibration excitations can be controlled effectively.However,the working frequency of vibration excitation may vary due to environmental changes,the working conditions of equipment,and other factors.Consequently,it remains a challenge to restrict the longitudinal vibration of elastic rods within a wide frequency band.In order to meet the relevant engineering requirements and address the existing limitations,the longitudinal vibration control of an elastic rod within a wide frequency band is explored in this study through an adjustable stiffness internal support.To achieve this purpose,the variable stiffness longitudinal vibration control theory of the elastic rod is validated.The model of an adjustable stiffness internal support is designed,constructed,and tested,demonstrating that the stiffness coefficients of the adjustable stiffness internal support can be effectively controlled.Through the adjustable stiffness internal support,the experiment on longitudinal vibration control of the elastic rod is designed and performed.It leads to the conclusion that the adjustable stiffness internal support within the adjustable working region is effective in restricting the longitudinal vibration within a wide frequency band of the elastic rod.Furthermore,the existence of the adjustable working region in the experiment demonstrates the effectiveness of the adjustable stiffness internal support intended for the variable stiffness longitudinal vibration control of an elastic rod.To sum up,this study provides insights into an adjustable stiffness mechanism for applying the theory of variable stiffness longitudinal vibration control on an elastic rod in engineering practice.
基金supported in part by the Natural Science Foundation of Gansu Province(Nos.20JR10RA614,22YF7GA182,22JR11RA042,22JR5RA1006,24CXGA024)the National Natural Science Foundation of China under Grant 61804071.
文摘Accurate measurement of anchor rod length is crucial for ensuring structural safety in tunnel engineering,yet conventional destructive techniques face limitations in efficiency and adaptability to complex underground environments.This study presents a novel wireless instrument based on the standing wave principle to enable remote,non-destructive length assessment.The system employs a master-slave architecture,where a handheld transmitter unit initiates measurements through robust 433 MHz wireless communication,optimized for signal penetration in obstructed spaces.The embedded measurement unit,integrated with anchor rods during installation,utilizes frequency-scanning technology to excite structural resonances.By analyzing standing wave characteristics,anchor length is derived from a calibrated frequency-length relationship.Power management adopts a standby-activation strategy to minimize energy consumption while maintaining operational readiness.Experimental validation confirms the system effectively measures anchor lengths with high precision and maintains reliable signal transmission through thick concrete barriers,demonstrating suitability for tunnel deployment.The non-destructive approach eliminates structural damage risks associated with traditional pull-out tests,while wireless operation enhances inspection efficiency in confined spaces.Thiswork establishes a paradigmfor embedded structural healthmonitoring in tunneling,offering significant improvements over existing methods in safety,cost-effectiveness,and scalability.The technology holds promise for broad applications in mining,underground infrastructure,and geotechnical engineering.
基金supported by the Nanjing University of Posts and Telecommunications Foundation,China(Grant Nos.JUH219002 and JUH219007)the Key R&D Program of Shandong Province,China(Grant No.2021CXGC010202)。
文摘In this paper,we present a high peak power passively Q-switched intracavity frequency-doubled green laser based on an efficient LED-pumped Nd:YAG dual-rod laser module.In quasi-continuous wave(QCW)running operation,the average output power of the fundamental laser at 1064 nm reaches as high as 20.98 W at a repetition rate of 50 Hz with a maximum single pulse energy of 419.6 mJ,corresponding to a maximum optical conversion efficiency of 38.8%and a slope efficiency of 41%.
基金support from the National Natural Science Foundation of China(Grant Nos.52072274,52272021,U23A20559 and 52232002)the Open Foundation of State Key Laboratory of Advanced Refractories(No.SKLAR202207)+1 种基金the Key Laboratory of Hubei Province for Coal Conversion and New Carbon Materials(Wuhan University of Science and Technology,WKDM202201)the Open/Innovation Foundation of Hubei Three Gorges Laboratory(SK232006).
文摘h-BN rods modified low-carbon alumina-carbon(Al_(2)O_(3)-C)refractories were prepared,and the effect of h-BN rod addition on the high-temperature properties was investigated and compared with commercial h-BN flake,carbon black,and carbon nanotubes additives.The results demonstrated that Al_(2)O_(3)-C refractories containing h-BN rods exhibited optimal high-temperature service performances,including 25%higher hot modulus of rupture,21.3%higher thermal shock strength residual ratio,20.9%lower in oxidation and 44.3%less in slag corrosion,compared to the counterpart specimens without additives.Moreover,benefiting from the synergistic enhancement of the rod-like h-BN and in-situ generated SiC whiskers,the high-temperature service performances of h-BN rods containing specimens outperformed counterpart specimens containing commercial h-BN flake,carbon black,and carbon nanotubes,respectively.
基金supported by Shanghai 2021“Science and Technology Innovation Action Plan”:Social Development Science and Technology Research Project(Grant No.21DZ1202703).
文摘The numerical simulation of the fluid flow and the flexible rod(s)interaction is more complicated and has lower efficiency due to the high computational cost.In this paper,a semi-resolved model coupling the computational fluid dynamics and the flexible rod dynamics is proposed using a two-way domain expansion method.The gov-erning equations of the flexible rod dynamics are discretized and solved by the finite element method,and the fluid flow is simulated by the finite volume method.The interaction between fluids and solid rods is modeled by introducing body force terms into the momentum equations.Referred to the traditional semi-resolved numerical model,an anisotropic Gaussian kernel function method is proposed to specify the interactive forces between flu-ids and solid bodies for non-circle rod cross-sections.A benchmark of the flow passing around a single flexible plate with a rectangular cross-section is used to validate the algorithm.Focused on the engineering applications,a test case of a finite patch of cylinders is implemented to validate the accuracy and efficiency of the coupled model.
基金supported by National Natural Science Foundation of China(52274397 and 52374395)Shandong Provincial Natural Science Foundation of China(ZR2024JQ020).
文摘The bimetallic composite rods prepared by co-extrusion have good mechanical properties,but their compressive deformation behaviors have rarely been studied.This paper primarily investigates the compressive deformation behavior of the AZ31/Mg-Gd-Y composite rod,analyzes the differences between its compressive deformation behavior and that of AZ31,and systematically studies the compressive deformation mechanisms of various regions in the composite rod,as well as the texture evolution and{10-12}twin evolution during the compression process.The results reveal that the AZ31/Mg-Gd-Y composite rods exhibit excellent metallurgical bonding,with the interface remaining intact even under a 9%compressive strain.In the compression process,AZ31 initiates yielding earlier than the AZ31/Mg-Gd-Y composite rods,exhibiting a relatively lower yield strength,whereas both show comparable plasticity.The deformation behavior of the AZ31/Mg-Gd-Y composite rod is governed by a combination of basal a slip and{10-12}-1011 tension twinning during compression along the ED(extrusion direction).With increasing compressive strain,the number of{10-12}twins in the AZ31 region(A/G-AZ31)of the AZ31/Mg-Gd-Y composite rod increases significantly,leading to changes in grain orientation,whereas the Mg-Gd-Y region(A/G-Mg-Gd-Y)of the composite rod shows no significant change.In addition,the A/G-Mg-Gd-Y significantly inhibits the nucleation and growth of{10-12}twins in A/G-AZ31 during compression,and thus the texture hardening generated by{10-12}twins make the work hardening behavior of the AZ31/Mg-Gd-Y composite rods different from that of AZ31.
文摘An exact forecast of the failures of a sucker rod-pumped well in a production area means much for an oilfield’s operation budget, operational arrangement and production plan. In this paper, according to the characteristics of failed sucker rod-pumped well randomness and strong outburst, with the gray GM (1,1) forecast model and the Markov forecast model combined, gray GM (1,1) forecast model is utilized to handle the primary data of an oilfield, and Markov forecast model is utilized to calculate the state transfer probability of forecast value. Then, the gray Markov forecast model considering the influence of randomness factors is formed. Field results prove that the calculation precision of this method is higher and the practicability is greater.
文摘目的 :探讨应用Smiley face rod固定系统治疗L5椎弓峡部裂的临床疗效。方法:2016年1月~2017年6月,我科采用Smiley face rod固定系统节段内固定植骨融合治疗腰椎峡部裂患者18例,男13例,女5例,年龄28.2±3.2岁(25~32岁),术前平均病程为16.3±5.7个月(7~24个月)。峡部裂节段均位于L5。术后3个月、1年时进行随访,对患者进行疼痛视觉模拟评分(visual analogue scale,VAS)及Oswestry功能障碍指数(Oswestry disability index,ODI)评定,评价其临床治疗效果。行X线、CT等检查,分析术前和术后L5/S1椎间活动度变化及椎间不稳发生率变化情况,并评价患者术后植骨融合情况。结果:手术时间平均90.0±24.1min,术中出血量平均140±15ml。平均随访18.5±5.0个月(12~24个月)。术前VAS评分为7.3±2.5分,ODI为(67.0±15.1)%;术后3个月时分别为3.0±1.2分和(17.2±4.5)%,较术前明显改善(P<0.05);术后1年时分别为1.0±0.6分和(9.1±5.3)%,较术后3个月时进一步改善(P<0.05)。术前L5/S1间隙活动度为13.1°±2.1°,存在腰椎不稳或小于Ⅰ度滑脱者共15例(83.3%,15/18);术后1年时分别为9.3°±1.6°和2例(11.1%,2/18),两者之间存在统计学差异(P<0.05)。术后1年时随访患者峡部裂均获得骨性愈合。结论 :应用Smiley face rod固定系统治疗L5椎弓峡部裂具有创伤小、对神经干扰少、恢复正常的解剖结构、提高椎间稳定性的优点。
基金Project(51335009)supported by the National Natural Science Foundation of ChinaProject(2014JQ7273)supported by the Natural Science Foundation of Shaanxi Province of ChinaProject(CXY1514(1))supported by the Xi’an Science and Technology Plan Projects,China
文摘Semi-solid squeeze casting（SSSC） and liquid squeeze casting（LSC） processes were used to fabricate a ZL104 connecting rod, and the influences of the process parameters on the microstructures and mechanical properties were investigated. Results showed that the tensile strength and elongation of the SSSC-fabricated rod were improved by 22% and 17%, respectively, compared with those of the LSC-fabricated rod. For SSSC, the average particle size（APS） and the shape factor（SF） increased with the increase of re-melting temperature（Tr）, whereas the tensile strength and elongation increased first and then decreased. The APS increased with increasing the mold temperature（Tm）, whereas the SF increased initially and then decreased, which caused the tensile strength and elongation to increase initially and then decrease. The APS decreased and the SF increased as squeezing pressure（ps） increased, and the mechanical properties were enhanced. Moreover, the optimal Tr, ps and Tm are 848 K, 100 MPa and 523 K, respectively.
