The presence of residual stresses in materials or engineering structures can significantly influence their mechanical per-formance.Accurate measurement of residual stresses is of great importance to ensure their in-se...The presence of residual stresses in materials or engineering structures can significantly influence their mechanical per-formance.Accurate measurement of residual stresses is of great importance to ensure their in-service reliability.Although numerous instrumented indentation methods have been proposed to evaluate residual stresses,the majority of them require a stress-free reference sample as a comparison benchmark,thereby limiting their applicability in scenarios where obtaining stress-free reference samples is challenging.In this work,through a number of finite element simulations,it was found that the loading exponent of the loading load-depth curve and the recovered depth during unloading are insensitive to residual stresses.The loading curve of the stress-free specimen was virtually reconstructed using such stress-insensitive parameters extracted from the load-depth curves of the stressed state,thus eliminating the requirement for stress-free reference samples.The residual stress was then correlated with the fractional change in loading work between stressed and stress-free loading curves through dimensional analysis and finite element simulations.Based on this correlation,an instrumented sharp indentation method for measuring equibiaxial residual stress without requiring a stress-free specimen was established.Both numerical and experimental verifications were carried out to demonstrate the accuracy and reliability of the newly proposed method.The maximum relative error and absolute error in measured residual stresses are typically within±20%and±20 MPa,respectively.展开更多
The machining process remains relevant for manufacturing high-quality and high-precision parts,which can be found in industries such as aerospace and aeronautical,with many produced by turning,drilling,and milling pro...The machining process remains relevant for manufacturing high-quality and high-precision parts,which can be found in industries such as aerospace and aeronautical,with many produced by turning,drilling,and milling processes.Monitoring and analyzing tool wear during these processes is crucial to assess the tool’s life and optimize the tool’s performance under study;as such,standards detail procedures to measure and assess tool wear for various tools.Measuring wear in machining tools can be time-consuming,as the process is usually manual,requiring human interaction and judgment.In the present work,an automated offline flank wear measurement algorithm was developed in Python.The algorithm measures the flank wear of coated end-mills and slot drills from Scanning Electron Microscopy(SEM)images,according to the ISO 8688 standard,following the same wear measurement procedure.SEM images acquired with different magnifications and tools with varying machining parameters were analyzed using the developed algorithm.The flank wear measurements were then compared to the manually obtained,achieving relative errors for the most common magnifications of around 2.5%.Higher magnifications were also tested,yielding a maximum relative error of 13.4%.The algorithm can measure batches of images quickly on an ordinary personal computer,analyzing and measuring a 10-image batch in around 30 s,a process that would require around 30 min when performed manually by a skilled operator.Therefore,it can be a reliable alternative to measuring flank wear on many tools from SEM images,with the possibility of being adjusted for other wear measurements on different kinds of tools and different image types,for example,on images obtained by optical microscopy.展开更多
Traditional automated guided vehicle(AGV)primarily relies on scheduling systems to manage warehouse locations and execute picking or placing tasks on fixedheight pallets.However,these conventional systems are illsuite...Traditional automated guided vehicle(AGV)primarily relies on scheduling systems to manage warehouse locations and execute picking or placing tasks on fixedheight pallets.However,these conventional systems are illsuited for scenarios involving variable heights,such as vehicle loading and unloading or the complex stacking of soft packages.To address the challenges of AGV endeffector operations in nonfixed height scenarios,this paper proposes an innovative solution leveraging lowcost depth camera sensors.By capturing image and depth data,and integrating deep learning,image processing,and spatial attitude calculation techniques,the method accurately determines the position of the endeffector center point relative to the upper plane of the fork.The approach effectively resolves a key issue in AGV operations within intelligent logistics scenarios that lack fixed heights.The proposed algorithm is deployed on a domestic embedded,lowcost ARM chip controller,and extensive experiments are conducted on a real AGV equipped with multiple stacked vehicles and nonstandard vehicles.The experimental results demonstrate that for diverse vehicles with different heights,the measurement error can be maintained within±10 mm,satisfying the requirements for highprecision measurement.The height measurement method developed in the paper not only enhances the AGV’s adaptability in nonfixed height scenarios but also significantly broadens its application potential across various industries.展开更多
Introduction This study aimed to either identify or develop and validate a patient-reported outcome measure(PROM)to assess treatment burden related to general practice for patients with multimorbidity,which can be use...Introduction This study aimed to either identify or develop and validate a patient-reported outcome measure(PROM)to assess treatment burden related to general practice for patients with multimorbidity,which can be used alongside the MultiMorbidity Questionnaire part 1(MMQ1)without overwhelming the target population with redundant items.Methods We conducted a systematic literature review to identify all existing PROMs measuring treatment burden.If no suitable PROM was found,our plan was to:(1)develop a draft PROM using items from existing instruments,(2)carry out group and individual interviews with patients with multimorbidity to ensure the PROM’s understandability,clarity,completeness and relevance and(3)undertake psychometric validation with a diverse sample of primary care patients with chronic conditions.Results We did not identify an eligible PROM in the literature review.The draft PROM consisted of 30 items divided into six domains;Information about treatment,Challenges with medication,Medical appointments,Self-monitoring,Health behaviour and Challenges in the contact to the health system.In the psychometric validation,neither these domains nor any other theoretical constellation of items had adequate psychometric properties.Individual items had good criterion validity and sensitivity to change.Conclusions In this study,we developed a 30-item PROM with high content validity where various individual items showed adequate criterion validity and sensitivity to change,making these items useful as a supplemental measure to the MMQ1.Trial registration number NCT05676541 Registration Date:16 December 2022.展开更多
Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for th...Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for thermal imaging and transport research.Here,we introduce an approach to measure nanoscale thermal resistance using in situ inelastic scanning transmission electron microscopy.By constructing unidirectional heating flux with controlled temperature gradients and analyzing electron energy-loss/gain signals under optimized acquisition conditions,nanometer-resolution in mapping phonon apparent temperature is achieved.Thus,interfacial thermal resistance is determined by calculating the ratio of interfacial temperature difference to bulk temperature gradient.This methodology enables direct measurement of thermal transport properties for atomic-scale structural features(e.g.,defects and heterointerfaces),resolving critical structure-performance relationships,providing a useful tool for investigating thermal phenomena at the(sub-)nanoscale.展开更多
A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into correspon...A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into corresponding voltage signal by the thermo-couple first. Then after the V/F stage, the voltage signal is converted into the frequency signal to drive the infrared light-emitting diode to transmit infrared pulses. At the receiver end, a photosensitive audion receives the infrared pulses. After conversion, the voltage recorded by the receiver stands for the magnitude of temperature at the measuring point. Test results of the system indicate that the system is practical and the system can perform multipoint looping temperature measurements for the piston.展开更多
The analysis and calculating method of dynamic errors of CMMs during probing are discussed.To relate the dynamic displacement errors with the dynamic rotational errors a method for obtaining the displacement errors at...The analysis and calculating method of dynamic errors of CMMs during probing are discussed.To relate the dynamic displacement errors with the dynamic rotational errors a method for obtaining the displacement errors at the probing position from dynamic rotational errors is presented.It is pointed out that the finite element method might be used for modeling dynamic errors.However,dynamic errors are difficult to be modeled so a combined practical and theoretical approach is needed.In addition,the dynamic errors are measured with inductive position sensors.展开更多
基金support from the National Natural Science Foundation of China(Grant Nos.12172332,11727803 and 12072009)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ23A020007)the Fundamental Research Funds for the Provincial Universities of Zhejiang(Grant No.RF-C2022003).
文摘The presence of residual stresses in materials or engineering structures can significantly influence their mechanical per-formance.Accurate measurement of residual stresses is of great importance to ensure their in-service reliability.Although numerous instrumented indentation methods have been proposed to evaluate residual stresses,the majority of them require a stress-free reference sample as a comparison benchmark,thereby limiting their applicability in scenarios where obtaining stress-free reference samples is challenging.In this work,through a number of finite element simulations,it was found that the loading exponent of the loading load-depth curve and the recovered depth during unloading are insensitive to residual stresses.The loading curve of the stress-free specimen was virtually reconstructed using such stress-insensitive parameters extracted from the load-depth curves of the stressed state,thus eliminating the requirement for stress-free reference samples.The residual stress was then correlated with the fractional change in loading work between stressed and stress-free loading curves through dimensional analysis and finite element simulations.Based on this correlation,an instrumented sharp indentation method for measuring equibiaxial residual stress without requiring a stress-free specimen was established.Both numerical and experimental verifications were carried out to demonstrate the accuracy and reliability of the newly proposed method.The maximum relative error and absolute error in measured residual stresses are typically within±20%and±20 MPa,respectively.
文摘The machining process remains relevant for manufacturing high-quality and high-precision parts,which can be found in industries such as aerospace and aeronautical,with many produced by turning,drilling,and milling processes.Monitoring and analyzing tool wear during these processes is crucial to assess the tool’s life and optimize the tool’s performance under study;as such,standards detail procedures to measure and assess tool wear for various tools.Measuring wear in machining tools can be time-consuming,as the process is usually manual,requiring human interaction and judgment.In the present work,an automated offline flank wear measurement algorithm was developed in Python.The algorithm measures the flank wear of coated end-mills and slot drills from Scanning Electron Microscopy(SEM)images,according to the ISO 8688 standard,following the same wear measurement procedure.SEM images acquired with different magnifications and tools with varying machining parameters were analyzed using the developed algorithm.The flank wear measurements were then compared to the manually obtained,achieving relative errors for the most common magnifications of around 2.5%.Higher magnifications were also tested,yielding a maximum relative error of 13.4%.The algorithm can measure batches of images quickly on an ordinary personal computer,analyzing and measuring a 10-image batch in around 30 s,a process that would require around 30 min when performed manually by a skilled operator.Therefore,it can be a reliable alternative to measuring flank wear on many tools from SEM images,with the possibility of being adjusted for other wear measurements on different kinds of tools and different image types,for example,on images obtained by optical microscopy.
基金Supported by the Key Research and Development Program of Anhui Province(No.201904a05020035)the Postdoctoral Research Initiative of Anhui Province(No.2024B804)the Hefei City Key Technology Research and Development‘Ranking’(No.2023SGJ017).
文摘Traditional automated guided vehicle(AGV)primarily relies on scheduling systems to manage warehouse locations and execute picking or placing tasks on fixedheight pallets.However,these conventional systems are illsuited for scenarios involving variable heights,such as vehicle loading and unloading or the complex stacking of soft packages.To address the challenges of AGV endeffector operations in nonfixed height scenarios,this paper proposes an innovative solution leveraging lowcost depth camera sensors.By capturing image and depth data,and integrating deep learning,image processing,and spatial attitude calculation techniques,the method accurately determines the position of the endeffector center point relative to the upper plane of the fork.The approach effectively resolves a key issue in AGV operations within intelligent logistics scenarios that lack fixed heights.The proposed algorithm is deployed on a domestic embedded,lowcost ARM chip controller,and extensive experiments are conducted on a real AGV equipped with multiple stacked vehicles and nonstandard vehicles.The experimental results demonstrate that for diverse vehicles with different heights,the measurement error can be maintained within±10 mm,satisfying the requirements for highprecision measurement.The height measurement method developed in the paper not only enhances the AGV’s adaptability in nonfixed height scenarios but also significantly broadens its application potential across various industries.
基金supported by the public agreement between the Danish Regions and the General Practitioners’Organization 2022–2024.
文摘Introduction This study aimed to either identify or develop and validate a patient-reported outcome measure(PROM)to assess treatment burden related to general practice for patients with multimorbidity,which can be used alongside the MultiMorbidity Questionnaire part 1(MMQ1)without overwhelming the target population with redundant items.Methods We conducted a systematic literature review to identify all existing PROMs measuring treatment burden.If no suitable PROM was found,our plan was to:(1)develop a draft PROM using items from existing instruments,(2)carry out group and individual interviews with patients with multimorbidity to ensure the PROM’s understandability,clarity,completeness and relevance and(3)undertake psychometric validation with a diverse sample of primary care patients with chronic conditions.Results We did not identify an eligible PROM in the literature review.The draft PROM consisted of 30 items divided into six domains;Information about treatment,Challenges with medication,Medical appointments,Self-monitoring,Health behaviour and Challenges in the contact to the health system.In the psychometric validation,neither these domains nor any other theoretical constellation of items had adequate psychometric properties.Individual items had good criterion validity and sensitivity to change.Conclusions In this study,we developed a 30-item PROM with high content validity where various individual items showed adequate criterion validity and sensitivity to change,making these items useful as a supplemental measure to the MMQ1.Trial registration number NCT05676541 Registration Date:16 December 2022.
基金supported by the National Natural Science Foundation of China(Grant No.52125307)the National Key R&D Program of China(Grant No.2021YFB3501500)the support from the New Cornerstone Science Foundation through the XPLORER PRIZE。
文摘Rapid technological advancements drive miniaturization and high energy density in devices,thereby increasing nanoscale thermal management demands and urging development of higher spatial resolution technologies for thermal imaging and transport research.Here,we introduce an approach to measure nanoscale thermal resistance using in situ inelastic scanning transmission electron microscopy.By constructing unidirectional heating flux with controlled temperature gradients and analyzing electron energy-loss/gain signals under optimized acquisition conditions,nanometer-resolution in mapping phonon apparent temperature is achieved.Thus,interfacial thermal resistance is determined by calculating the ratio of interfacial temperature difference to bulk temperature gradient.This methodology enables direct measurement of thermal transport properties for atomic-scale structural features(e.g.,defects and heterointerfaces),resolving critical structure-performance relationships,providing a useful tool for investigating thermal phenomena at the(sub-)nanoscale.
文摘A high precision, high antijamming multipoint infrared telemetry system was developed to measure the piston temperature in internal combustion engine. The temperature at the measuring point is converted into corresponding voltage signal by the thermo-couple first. Then after the V/F stage, the voltage signal is converted into the frequency signal to drive the infrared light-emitting diode to transmit infrared pulses. At the receiver end, a photosensitive audion receives the infrared pulses. After conversion, the voltage recorded by the receiver stands for the magnitude of temperature at the measuring point. Test results of the system indicate that the system is practical and the system can perform multipoint looping temperature measurements for the piston.
文摘The analysis and calculating method of dynamic errors of CMMs during probing are discussed.To relate the dynamic displacement errors with the dynamic rotational errors a method for obtaining the displacement errors at the probing position from dynamic rotational errors is presented.It is pointed out that the finite element method might be used for modeling dynamic errors.However,dynamic errors are difficult to be modeled so a combined practical and theoretical approach is needed.In addition,the dynamic errors are measured with inductive position sensors.
