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
By using an instrumented impact pendulum, the force versus time curves of 7075-T651 aluminum welds were obtained from standard Charpy-V samples. Considering the force-time curves and constant impact velocity, the frac...By using an instrumented impact pendulum, the force versus time curves of 7075-T651 aluminum welds were obtained from standard Charpy-V samples. Considering the force-time curves and constant impact velocity, the fracture energies for different zones were quantified. A fracture energy improvement for the HAZ(33.6 J) was observed in comparison with the weld metal(7.88 J), and base metal(5.37 J and 7.37 J for longitudinal and transverse directions, respectively). This toughness increment was attributed to the microstructural transformation caused by the thermodynamic instability of η′ precipitates during the welding. Fracture energy for weld metal was higher than that for base metal, probably due to pores created during solidification. Regarding the dynamic yielding force obtained from the force-time curves, an approximation to the dynamic yield strength for weld, HAZ and base metal was determined. Fracture surfaces revealed an intergranular failure for base metal in longitudinal direction, whereas a predominately brittle failure(cleavage) with some insights of ductile characteristics was observed for the transverse direction. In contrast, a ductile failure was observed for weld metal and HAZ.展开更多
A nondestructive continuous instrumented wheelset design is proposed based on strain gauges placing inside of the wheel web and wireless telemetry system. The signal feature analysis including frequency contents and h...A nondestructive continuous instrumented wheelset design is proposed based on strain gauges placing inside of the wheel web and wireless telemetry system. The signal feature analysis including frequency contents and high order harmonic ripples is also carried out. The strain gradient decoupling method for vertical and lateral force identification is proposed based on the strain distributions under respective loads. The method implements minimum crosstalk effects and insensitive to the varying contact points. The KMT telemetry system is adopted for wireless inductive powering and signal transferring. The drilling holes on the wheel and axles are avoidable to ensure the integrity and long-term using of the wheelset. Bridging and demodulating schemes for lateral and vertical force are designed respectively as they have dramatic differences at the dynamic signal features. High order harmonic ripple analysis and error estimation are gotten by independent waveforms. Based on the data form calibration test rig, it is indicated that the high order ripple amplitudes are below 10% of the demodulation amplitudes and fulfill designed requirements.展开更多
BACKGROUND Acute spinal subdural haematoma(ASSH)is a rare and potentially devastating condition with a variable prognosis.Previously described subdural haematomas were thought to have occurred spontaneously or be rela...BACKGROUND Acute spinal subdural haematoma(ASSH)is a rare and potentially devastating condition with a variable prognosis.Previously described subdural haematomas were thought to have occurred spontaneously or be related to major or minor iatrogenic or traumatic injuries caused by surgery,spinal puncture or epidural anaesthesia.Other contributing pathologies have been described,such as intradural tumours or spinal arteriovenous malformations.ASSH has also been associated with anticoagulation therapy,haemostatic abnormalities and risk factors such as pregnancy.To the best of our knowledge,this case study described the first reported occurrence of an ASSH during spinal surgery in a paediatric patient.The patient was not known to have any coagulopathies,and no obvious vascular lesions were documented.The surgical procedure did not directly involve the dura mater,and no evident intraoperative dural tears were found.CASE SUMMARY We reported and discussed a case of ASSH complicating a posterior spinal instrumented fusion during surgery for paediatric congenital scoliosis.This condition has not been previously described.We made recommendations for facing such an occurrence,explored its aetiology in the context of malformation and discussed the benefits of neuromonitoring during scoliosis correction and the management protocol.We conducted a PubMed literature review for cases of paediatric ASSH and other closely related disorders.We reviewed recommendations regarding neuromonitoring and treatment management in such cases.CONCLUSION ASSH is a rare complication of posterior spinal instrumented fusion.Published cases are more often associated with anticoagulation therapy or coagulopathy.Neuromonitoring is strongly recommended to detect and assess neurological status,thus enabling rapid diagnosis and treatment and facilitating early spinal decompression and a return to a normal neurological status.展开更多
A more accurate determination for the Probability of Failure on Demand(PFD)of the Safety Instrumented System(SIS)contributes to more SIS realiability,thereby ensuring more safety and lower cost.IEC 61508 and ISA TR.84...A more accurate determination for the Probability of Failure on Demand(PFD)of the Safety Instrumented System(SIS)contributes to more SIS realiability,thereby ensuring more safety and lower cost.IEC 61508 and ISA TR.84.02 provide the PFD detemination formulas.However,these formulas suffer from an uncertaity issue due to the inclusion of uncertainty sources,which,including high redundant systems architectures,cannot be assessed,have perfect proof test assumption,and are neglegted in partial stroke testing(PST)of impact on the system PFD.On the other hand,determining the values of PFD variables to achieve the target risk reduction involves daunting efforts and consumes time.This paper proposes a new approach for system PFD determination and PFD variables optimization that contributes to reduce the uncertainty problem.A higher redundant system can be assessed by generalizing the PFD formula into KooN architecture without neglecting the diagnostic coverage factor(DC)and common cause failures(CCF).In order to simulate the proof test effectiveness,the Proof Test Coverage(PTC)factor has been incorporated into the formula.Additionally,the system PFD value has been improved by incorporating PST for the final control element into the formula.The new developed formula is modelled using the Genetic Algorithm(GA)artificial technique.The GA model saves time and effort to examine system PFD and estimate near optimal values for PFD variables.The proposed model has been applicated on SIS design for crude oil test separator using MATLAB.The comparison between the proposed model and PFD formulas provided by IEC 61508 and ISA TR.84.02 showed that the proposed GA model can assess any system structure and simulate industrial reality.Furthermore,the cost and associated implementation testing activities are reduced.展开更多
Our paper presents a project that involves two research questions: does the choice of a related problem by the tutorial system allow the problem solving process which is blocked for the student to be restarted? What i...Our paper presents a project that involves two research questions: does the choice of a related problem by the tutorial system allow the problem solving process which is blocked for the student to be restarted? What information about learning do related problems returned by the system provide us? We answer the first question according to the didactic engineering, whose mode of validation is internal and based on the confrontation between an a priori analysis and an a posteriori analysis that relies on data from experiments in schools. We consider the student as a subject whose adaptation processes are conditioned by the problem and the possible interactions with the computer environment, and also by his knowledge, usually implicit, of the institutional norms that condition his relationship with geometry. Choosing a set of good problems within the system is therefore an essential element of the learning model. Since the source of a problem depends on the student’s actions with the computer tool, it is necessary to wait and see what are the related to problems that are returned to him before being able to identify patterns and assess the learning. With the simultaneity of collecting and analysing interactions in each class, we answer the second question according to a grounded theory analysis. By approaching the problems posed by the system and the designs in play at learning blockages, our analysis links the characteristics of problems to the design components in order to theorize on the decisional, epistemological, representational, didactic and instrumental aspects of the subject-milieu system in interaction.展开更多
Background The purpose of this retrospective study was to compare the surgical outcomes of simple discectomy and instrumented posterior lumbar interbody fusion （iPLIF） in patients with lumbar disc herniation and Mod...Background The purpose of this retrospective study was to compare the surgical outcomes of simple discectomy and instrumented posterior lumbar interbody fusion （iPLIF） in patients with lumbar disc herniation and Modic endplate changes.Our hypothesis was that iPLIF could provide better outcome for patients with refractory lumbar disc herniation and Modic changes （LDH-MC）.Methods Ninety-one patients with single-segment LDH-MC were recruited.All patients experienced low back pain as well as radicular leg pain,and low back pain was more severe than leg pain.Forty-seven patients were treated with discectomy and 44 were treated with iPLIE The outcomes of both low back pain and radicular leg pain using visual analogue scale （VAS） as well as the clinical outcome related to low back pain using Japanese Orthopaedic Association （JOA） score were assessed before and 18 months after surgery,respectively.Results Both low back and leg pain were significantly improved 18 months after simple discectomy and iPLIE Compared to patients undergoing simple discectomy,low back pain was significantly reduced in patients undergoing iPLIE but there was no significant difference in leg pain between two groups.Solid fusion was achieved in all patients who underwent iPLIF.Conclusions In patients with LDH-MC,iPLIF can yield significantly superior outcome on the relief of low back pain compared to simple discectomy.Simple discectomy can relieve radicular leg pain as efficient as iPLIE Accordingly,iPLIF seems to be a reliable treatment for patients with LDH-MC and predominant low back pain.展开更多
The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been ...The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.展开更多
The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the re...The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the readout system is implemented using a frequency division multiplexing circuit system,coupled with an FFT design to enable the readout of MKID arrays.The system is characterized by its compact size,low cost,portability,and ease of further development.Together,these features have significant implications for the design and readout of terahertz MKID arrays,while simultaneously advancing both the theoretical and practical aspects of MKID technology.展开更多
The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a ...The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a wide field of view of approximately 3×3 square degrees.Calibration parameters are essential to ensure the precision of astrometric observations with the WFST.These parameters are derived from geometric distortion(GD)and gaps through astrometric modeling and are subsequently validated via the Yao’An High Precision Telescope(YAHPT).The GD solutions show maximum distortions between 1.18 and 10.29 pixels for the WFST chips,with central chips exhibiting lower distortion.After applying the GD correction,the precision of the WFST reaches 4 mas.The interchip gaps of the WFST range from 1.922 mm to 7.765 mm,corresponding to 10μm/pixel,aligning with the design and measurements.The calibrated parameters guarantee that the WFST can perform highly accurate astrometric measurements.Furthermore,as the WFST undergoes updates,the parameter model remains consistently applicable.展开更多
https://www.sciencedirect.com/journal/energy-and-buildings/vol/336/suppl/C Volume 336,1 June 2025[OA](1)Advancing energy renovations through digitalisation:A critical review of EU policies and instruments by Sun-Ah Hw...https://www.sciencedirect.com/journal/energy-and-buildings/vol/336/suppl/C Volume 336,1 June 2025[OA](1)Advancing energy renovations through digitalisation:A critical review of EU policies and instruments by Sun-Ah Hwang,Sultan etin,Henk Visscher,et al,Article 115627.展开更多
Objective:To evaluate the effectiveness of quality nursing in the management of reusable instruments in the Central Sterile Supply Department(CSSD).Methods:Eleven nurses from the CSSD department were selected from Jan...Objective:To evaluate the effectiveness of quality nursing in the management of reusable instruments in the Central Sterile Supply Department(CSSD).Methods:Eleven nurses from the CSSD department were selected from January to October 2024,and quality nursing activities were implemented in the management of reusable instruments.The completion of quality indicators was analyzed.The instrument quality management scores,department satisfaction,and nurses’professional ability scores before and after nursing management were compared.Results:After nursing intervention,the qualified rates of initial cleaning and final cleaning of sterilization instruments were 99.66%and 100%,respectively.The qualified rate of packaging was 99.97%,the wet package rate was 0.1‰,the loading qualified rate was 99.88%,and the qualified rate of distribution was 99.99%.After nursing intervention,the nurses’instrument quality management scores,department satisfaction,and nurses’professional ability scores were all higher than those before nursing intervention(P<0.05).Conclusion:Quality nursing activities can improve the cleaning,packaging,and sterilization qualified rates of reusable instruments in the CSSD,enhance the effect of instrument quality management,obtain higher department satisfaction from nurses,cultivate their professional abilities,and possess significant nursing management advantages.展开更多
Searching for primordial gravitational waves in the cosmic microwave background(CMB)polarization signal is one of the key topics in modern cosmology.Cutting-edge CMB telescopes require thousands of pixels to maximize ...Searching for primordial gravitational waves in the cosmic microwave background(CMB)polarization signal is one of the key topics in modern cosmology.Cutting-edge CMB telescopes require thousands of pixels to maximize mapping speed.Using a modular design,the telescope focal plane is simplified to several detector modules.Each module has hundreds of pixels including antenna arrays,detector arrays,and readout arrays.The antenna arrays,as the beam defining component,determine the overall optical response of the detector module.In this article,we present the developments of 6 inch broadband antenna arrays from 80 to 170 GHz for the future IHEP focal plane module.The arrays are fabricated from 426 inch silicon wafers including 456 antennas,7%more pixels than the usual design.The overall in-band cross polarization is smaller than-20 dB and the in-band beam asymmetry is smaller than 10%,fulfilling the requirements for primordial gravitational wave search.展开更多
A leading position in the areas of testing,instrumentation and machine control has been established by members of the British Textile Machinery Association(BTMA)and a number of new developments in these fields will be...A leading position in the areas of testing,instrumentation and machine control has been established by members of the British Textile Machinery Association(BTMA)and a number of new developments in these fields will be showcased at this year’s ITMA Asia+CITME exhibition,which takes place in Singapore from October 28-31.“Many of our members are currently developing new technologies,either in-house or increasingly through joint projects,and there will be much to reveal by the time of ITMA Asia in Singapore,”says BTMA CEO Jason Kent.“Some of the most recent developments are really going beyond what has previously been possible.”展开更多
The infrared Fourier transform spectrometer needs a cold view field diaphragm to reduce stray radiation.For an infrared spectrometer with linear array detectors,the part of the view field diaphragm where the light pas...The infrared Fourier transform spectrometer needs a cold view field diaphragm to reduce stray radiation.For an infrared spectrometer with linear array detectors,the part of the view field diaphragm where the light passes can be regarded as a slit.If the infrared detectors are small in size,the width of the slit is also small,which will cause serious diffraction phenomena.If the widths of the view field diaphragm and the optical system are designed by geometric optics theory,the diffraction light cannot be fully received by the detectors,which will cause energy loss.Expanding the width of the view field diaphragm will introduce stray radiation.Meanwhile,spectrometer follow-up optics should be set in cold environments to reduce the infrared background of the instrument.Optical materials have different thermal characteristics,the optical and mechanical structures will deform at lowtemperature,and the cold view field diaphragm is installed at room temperature,so it is impossible to guarantee that the cold view field diaphragm remains in its design position when working at low-temperature.This paper solves the above problems by designing an adjustable cold view field diaphragm installed in its cryogenic vacuum chamber.The width and position of the view field diaphragm can be adjusted when working in cold temperatures,without opening the cryogenic vacuum chamber.Contrasting the interference signal obtained by the detectors in the adjustment process,the system can get the most suitable width and position of the cold view field diaphragm.The above works are based on the spectrometer used in the study named Accurate Infrared Magnetic Field Measurements of the Sun.展开更多
For some space radio telescopes,the orbit determination accuracy is not high enough,the time synchronization accuracy provided by the satellite platforms is low,and GNSS devices are not available.As a result,a traditi...For some space radio telescopes,the orbit determination accuracy is not high enough,the time synchronization accuracy provided by the satellite platforms is low,and GNSS devices are not available.As a result,a traditional method that relies on GNSS devices to obtain an initial clock offset followed by performing correlation with the calibration source may fail to obtain fringes.Moreover,a brutal force search across the 2D clock offset and fringe rate search plane is computationally expensive.In light of these challenges,we propose a novel time synchronization method that utilizes the spacecraft’s telemetry tone signal.This method employs frequency polynomials derived from Doppler tracking for fringe rotation during the correlation process.By aligning the frequency of the target station precisely with that of the reference station,it is only necessary to split the clock offset search range into multiple time windows,perform correlation for each window,and identify the window with the highest signal-to-noise ratio(SNR).The precise clock offset is determined by combining the residual delay with the initial offset.To validate the method,we observe the Tianwen-1 telemetry signal with the 4.5 m small telescope in the Tianma campus of Shanghai Astronomical Observatory and 40 m telescope in Kunming.The results demonstrate that our method can accurately determine clock offset for a time range as wide as±10 ms,with an SNR slightly higher than that achieved with the delay model.This method is suitable for wide-range time synchronization for space Very Long Baseline Interferometry observations,especially in scenarios involving small antennas with low sensitivity and poor orbit determination accuracy.展开更多
The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spect...The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spectroscopy.The precision of fiber positioning is crucial,as it directly impacts the observational efficiency of LAMOST.A critical component of the fiber positioning system is the closed-loop control system,which traditionally utilizes the light spot generated at fiber end.However,this study introduces a novel approach based on front-illuminated LAMOST focal plane image measurements.Unlike back-illumination,front-illumination does not necessitate internal lighting in the spectrograph,thus reducing light pollution and eliminating the need for additional photography.This method employs an artificial intelligence model to analyze images captured at the focal plane unit(FPU),using the image of the white ceramic head on the FPU as the data set for training,the model is capable of accurately measuring the fiber positions solely through front-illumination.Preliminary trials indicate that the measurement accuracy achieved using the frontillumination method is approximately 0."13.This level of precision meets the stringent fiber positioning accuracy requirement of LAMOST,set at 0."2.Furthermore,this novel approach demonstrates compatibility with LAMOST’s existing closed-loop fiber control system,offering potential for seamless integration and enhanced operational efficiency.展开更多
This paper presents a comprehensive analysis of the photometric system of the University of Chinese Academy of Sciences 70 cm Telescope located at the Yan-qi Lake campus of the University of Chinese Academy of Science...This paper presents a comprehensive analysis of the photometric system of the University of Chinese Academy of Sciences 70 cm Telescope located at the Yan-qi Lake campus of the University of Chinese Academy of Sciences.We evaluated the linearity,bias stability,and dark current of the camera.Utilizing the Johnson-Cousins Blue-Visible-Red-Infrared filter system and an Andor DZ936 charge-coupled device camera,we conducted extensive observations of Landolt standard stars to determine the color terms,atmospheric extinction coefficients,photometric zero-points,and the sky background brightness.The results indicate that this telescope demonstrates excellent performance in photometric calibration and good system performance overall,meeting the requirements for limited scientific research and teaching purposes.展开更多
Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for...Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for identifying bridge damping ratios using a two-axle,three-mass test vehicle,relying on wheel responses captured by only two mounted sensors.Damping ratio estimation formulas are derived using both the Hilbert Transform(HT)and Wavelet Transform(WT),with a consistent formulation that confirms accurate estimation is achievable with minimal instrumentation,particularly when addressing the support effect.A comparative analysis of the two signal processing techniques reveals the superior performance of WT in identifying bridge damping ratios.The effectiveness of the proposed procedure and formulas is validated through a detailed parametric study,demonstrating robustness across bridges with varying modal damping ratios and different spans using minimal sensors.Moreover,the present study shows that responses from only the first two spans of a multi-span bridge are sufficient for reliable damping estimation,underscoring the practicality and scalability of the procedure for structural health monitoring applications.展开更多
The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to ...The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to lack of low-cost methods capable of rapid As analysis.Therefore,the development of high through-put and reliable on-site determination methods for inorganic As is essential.Herein,a portable automated analyzer was developed for the determination of arsenite(As(Ⅲ)),arsenate(As(Ⅴ))and phosphate in As contaminated groundwater based on a previously adapted method for molybdenum blue spectrophotometry.After the optimization of the chemical reactions and flow manifold,the system demonstrated a high sample through-put(4.8/h for As(Ⅲ),As(Ⅴ)and phosphate analysis),allowing this system to screen 125 samples in 24 h.Other advantages include low operational costs(0.3 CNY per sample),appropriate sensitivity for contaminated groundwater(detection limits of 4.7μg/L,8.3μg/L and 5.4μg/L for As(Ⅲ),As(Ⅴ)and phosphate,respectively),good linearity(R^(2)>0.9996 at As concentrations up to 1600μg/L)and high precision(relative standard deviations of 3.5% and 2.8% for As(Ⅲ)and As(Ⅴ),respectively).The portable system was successfully used for As speciation analysis in 5 groundwater samples collected from multi-level wells at Yinchuan Plain,northwestern China,with total As concentrations ranging from 75.7 to 295.0μg/L,independently assessing As speciation,providing a promising novel method for the rapid on-site screening of As in tens of millions of domestic wells worldwide.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.
基金CONACy T (project CB 177834)SIP-IPN for the funds given to conduct this research
文摘By using an instrumented impact pendulum, the force versus time curves of 7075-T651 aluminum welds were obtained from standard Charpy-V samples. Considering the force-time curves and constant impact velocity, the fracture energies for different zones were quantified. A fracture energy improvement for the HAZ(33.6 J) was observed in comparison with the weld metal(7.88 J), and base metal(5.37 J and 7.37 J for longitudinal and transverse directions, respectively). This toughness increment was attributed to the microstructural transformation caused by the thermodynamic instability of η′ precipitates during the welding. Fracture energy for weld metal was higher than that for base metal, probably due to pores created during solidification. Regarding the dynamic yielding force obtained from the force-time curves, an approximation to the dynamic yield strength for weld, HAZ and base metal was determined. Fracture surfaces revealed an intergranular failure for base metal in longitudinal direction, whereas a predominately brittle failure(cleavage) with some insights of ductile characteristics was observed for the transverse direction. In contrast, a ductile failure was observed for weld metal and HAZ.
文摘A nondestructive continuous instrumented wheelset design is proposed based on strain gauges placing inside of the wheel web and wireless telemetry system. The signal feature analysis including frequency contents and high order harmonic ripples is also carried out. The strain gradient decoupling method for vertical and lateral force identification is proposed based on the strain distributions under respective loads. The method implements minimum crosstalk effects and insensitive to the varying contact points. The KMT telemetry system is adopted for wireless inductive powering and signal transferring. The drilling holes on the wheel and axles are avoidable to ensure the integrity and long-term using of the wheelset. Bridging and demodulating schemes for lateral and vertical force are designed respectively as they have dramatic differences at the dynamic signal features. High order harmonic ripple analysis and error estimation are gotten by independent waveforms. Based on the data form calibration test rig, it is indicated that the high order ripple amplitudes are below 10% of the demodulation amplitudes and fulfill designed requirements.
文摘BACKGROUND Acute spinal subdural haematoma(ASSH)is a rare and potentially devastating condition with a variable prognosis.Previously described subdural haematomas were thought to have occurred spontaneously or be related to major or minor iatrogenic or traumatic injuries caused by surgery,spinal puncture or epidural anaesthesia.Other contributing pathologies have been described,such as intradural tumours or spinal arteriovenous malformations.ASSH has also been associated with anticoagulation therapy,haemostatic abnormalities and risk factors such as pregnancy.To the best of our knowledge,this case study described the first reported occurrence of an ASSH during spinal surgery in a paediatric patient.The patient was not known to have any coagulopathies,and no obvious vascular lesions were documented.The surgical procedure did not directly involve the dura mater,and no evident intraoperative dural tears were found.CASE SUMMARY We reported and discussed a case of ASSH complicating a posterior spinal instrumented fusion during surgery for paediatric congenital scoliosis.This condition has not been previously described.We made recommendations for facing such an occurrence,explored its aetiology in the context of malformation and discussed the benefits of neuromonitoring during scoliosis correction and the management protocol.We conducted a PubMed literature review for cases of paediatric ASSH and other closely related disorders.We reviewed recommendations regarding neuromonitoring and treatment management in such cases.CONCLUSION ASSH is a rare complication of posterior spinal instrumented fusion.Published cases are more often associated with anticoagulation therapy or coagulopathy.Neuromonitoring is strongly recommended to detect and assess neurological status,thus enabling rapid diagnosis and treatment and facilitating early spinal decompression and a return to a normal neurological status.
文摘A more accurate determination for the Probability of Failure on Demand(PFD)of the Safety Instrumented System(SIS)contributes to more SIS realiability,thereby ensuring more safety and lower cost.IEC 61508 and ISA TR.84.02 provide the PFD detemination formulas.However,these formulas suffer from an uncertaity issue due to the inclusion of uncertainty sources,which,including high redundant systems architectures,cannot be assessed,have perfect proof test assumption,and are neglegted in partial stroke testing(PST)of impact on the system PFD.On the other hand,determining the values of PFD variables to achieve the target risk reduction involves daunting efforts and consumes time.This paper proposes a new approach for system PFD determination and PFD variables optimization that contributes to reduce the uncertainty problem.A higher redundant system can be assessed by generalizing the PFD formula into KooN architecture without neglecting the diagnostic coverage factor(DC)and common cause failures(CCF).In order to simulate the proof test effectiveness,the Proof Test Coverage(PTC)factor has been incorporated into the formula.Additionally,the system PFD value has been improved by incorporating PST for the final control element into the formula.The new developed formula is modelled using the Genetic Algorithm(GA)artificial technique.The GA model saves time and effort to examine system PFD and estimate near optimal values for PFD variables.The proposed model has been applicated on SIS design for crude oil test separator using MATLAB.The comparison between the proposed model and PFD formulas provided by IEC 61508 and ISA TR.84.02 showed that the proposed GA model can assess any system structure and simulate industrial reality.Furthermore,the cost and associated implementation testing activities are reduced.
文摘Our paper presents a project that involves two research questions: does the choice of a related problem by the tutorial system allow the problem solving process which is blocked for the student to be restarted? What information about learning do related problems returned by the system provide us? We answer the first question according to the didactic engineering, whose mode of validation is internal and based on the confrontation between an a priori analysis and an a posteriori analysis that relies on data from experiments in schools. We consider the student as a subject whose adaptation processes are conditioned by the problem and the possible interactions with the computer environment, and also by his knowledge, usually implicit, of the institutional norms that condition his relationship with geometry. Choosing a set of good problems within the system is therefore an essential element of the learning model. Since the source of a problem depends on the student’s actions with the computer tool, it is necessary to wait and see what are the related to problems that are returned to him before being able to identify patterns and assess the learning. With the simultaneity of collecting and analysing interactions in each class, we answer the second question according to a grounded theory analysis. By approaching the problems posed by the system and the designs in play at learning blockages, our analysis links the characteristics of problems to the design components in order to theorize on the decisional, epistemological, representational, didactic and instrumental aspects of the subject-milieu system in interaction.
文摘Background The purpose of this retrospective study was to compare the surgical outcomes of simple discectomy and instrumented posterior lumbar interbody fusion （iPLIF） in patients with lumbar disc herniation and Modic endplate changes.Our hypothesis was that iPLIF could provide better outcome for patients with refractory lumbar disc herniation and Modic changes （LDH-MC）.Methods Ninety-one patients with single-segment LDH-MC were recruited.All patients experienced low back pain as well as radicular leg pain,and low back pain was more severe than leg pain.Forty-seven patients were treated with discectomy and 44 were treated with iPLIE The outcomes of both low back pain and radicular leg pain using visual analogue scale （VAS） as well as the clinical outcome related to low back pain using Japanese Orthopaedic Association （JOA） score were assessed before and 18 months after surgery,respectively.Results Both low back and leg pain were significantly improved 18 months after simple discectomy and iPLIE Compared to patients undergoing simple discectomy,low back pain was significantly reduced in patients undergoing iPLIE but there was no significant difference in leg pain between two groups.Solid fusion was achieved in all patients who underwent iPLIF.Conclusions In patients with LDH-MC,iPLIF can yield significantly superior outcome on the relief of low back pain compared to simple discectomy.Simple discectomy can relieve radicular leg pain as efficient as iPLIE Accordingly,iPLIF seems to be a reliable treatment for patients with LDH-MC and predominant low back pain.
基金supported by the National Key R&D Program of China(grant No.2023YFA1608304 and No.2023YFA1608300)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0550100 and XDB0550000)the National Natural Science Foundation of China(NSFC,grant Nos.12090041,12090040,11903054,12422303,and 12261141690)。
文摘The Si Tian project,designed to utilize 60 telescopes distributed across multiple sites in China,is a next-generation timedomain survey initiative.As a pathfinder for the Si Tian project,the Mini-Si Tian(MST)has been proposed and implemented to test the Si Tian’s brain and data pipeline,and to evaluate the feasibility of its technology and science cases.Mounted at the Xinglong Observatory,the MST project comprises three 30 cm telescopes and has been operated since 2022 November.Each telescope of the MST possesses a large field of view,covering 2°.29×1°.53 FOV,and is equipped withg',r'andi'filters,respectively.Acting as the pioneer of the forthcoming Si Tian project,the MST is dedicated to the discovery of variable stars,transients,and outburst events,and has already obtained some interesting scientific results.In this paper,we will summarize the first-two-year operation of the MST project.
基金funded by the National Key Research and Development Program of China under Nos.2023YFA1608200&2020YFC2201703the National Natural Science Foundation of China(NSFC,Grant No.12020101002)the Natural Science Foundation of China for the youth under No.12103093。
文摘The proposed design of a microwave superconducting kinetic inductance detector(MKID)array readout system characterizes the performance of MKIDs through a digital homodyne frequency mixing architecture.Meanwhile,the readout system is implemented using a frequency division multiplexing circuit system,coupled with an FFT design to enable the readout of MKID arrays.The system is characterized by its compact size,low cost,portability,and ease of further development.Together,these features have significant implications for the design and readout of terahertz MKID arrays,while simultaneously advancing both the theoretical and practical aspects of MKID technology.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0350300)the National Natural Science Foundation of China(12203105,12103091,62394351,12073008)the China Manned Space Project(CMS-CSST-2021-A12,CMS-CSST-2021-B10).
文摘The Wide Field Survey Telescope(WFST)is located at 4200 m on Saishiteng Mountain in Lenghu,Qinghai Province,China.It features a primary mirror with a diameter of 2.5 m and a camera equipped with nine CCDs,providing a wide field of view of approximately 3×3 square degrees.Calibration parameters are essential to ensure the precision of astrometric observations with the WFST.These parameters are derived from geometric distortion(GD)and gaps through astrometric modeling and are subsequently validated via the Yao’An High Precision Telescope(YAHPT).The GD solutions show maximum distortions between 1.18 and 10.29 pixels for the WFST chips,with central chips exhibiting lower distortion.After applying the GD correction,the precision of the WFST reaches 4 mas.The interchip gaps of the WFST range from 1.922 mm to 7.765 mm,corresponding to 10μm/pixel,aligning with the design and measurements.The calibrated parameters guarantee that the WFST can perform highly accurate astrometric measurements.Furthermore,as the WFST undergoes updates,the parameter model remains consistently applicable.
文摘https://www.sciencedirect.com/journal/energy-and-buildings/vol/336/suppl/C Volume 336,1 June 2025[OA](1)Advancing energy renovations through digitalisation:A critical review of EU policies and instruments by Sun-Ah Hwang,Sultan etin,Henk Visscher,et al,Article 115627.
文摘Objective:To evaluate the effectiveness of quality nursing in the management of reusable instruments in the Central Sterile Supply Department(CSSD).Methods:Eleven nurses from the CSSD department were selected from January to October 2024,and quality nursing activities were implemented in the management of reusable instruments.The completion of quality indicators was analyzed.The instrument quality management scores,department satisfaction,and nurses’professional ability scores before and after nursing management were compared.Results:After nursing intervention,the qualified rates of initial cleaning and final cleaning of sterilization instruments were 99.66%and 100%,respectively.The qualified rate of packaging was 99.97%,the wet package rate was 0.1‰,the loading qualified rate was 99.88%,and the qualified rate of distribution was 99.99%.After nursing intervention,the nurses’instrument quality management scores,department satisfaction,and nurses’professional ability scores were all higher than those before nursing intervention(P<0.05).Conclusion:Quality nursing activities can improve the cleaning,packaging,and sterilization qualified rates of reusable instruments in the CSSD,enhance the effect of instrument quality management,obtain higher department satisfaction from nurses,cultivate their professional abilities,and possess significant nursing management advantages.
基金supported by the National Key Research and Development Program of China(grants Nos.2022YFC2205000 and 2021YFC2203400)。
文摘Searching for primordial gravitational waves in the cosmic microwave background(CMB)polarization signal is one of the key topics in modern cosmology.Cutting-edge CMB telescopes require thousands of pixels to maximize mapping speed.Using a modular design,the telescope focal plane is simplified to several detector modules.Each module has hundreds of pixels including antenna arrays,detector arrays,and readout arrays.The antenna arrays,as the beam defining component,determine the overall optical response of the detector module.In this article,we present the developments of 6 inch broadband antenna arrays from 80 to 170 GHz for the future IHEP focal plane module.The arrays are fabricated from 426 inch silicon wafers including 456 antennas,7%more pixels than the usual design.The overall in-band cross polarization is smaller than-20 dB and the in-band beam asymmetry is smaller than 10%,fulfilling the requirements for primordial gravitational wave search.
文摘A leading position in the areas of testing,instrumentation and machine control has been established by members of the British Textile Machinery Association(BTMA)and a number of new developments in these fields will be showcased at this year’s ITMA Asia+CITME exhibition,which takes place in Singapore from October 28-31.“Many of our members are currently developing new technologies,either in-house or increasingly through joint projects,and there will be much to reveal by the time of ITMA Asia in Singapore,”says BTMA CEO Jason Kent.“Some of the most recent developments are really going beyond what has previously been possible.”
基金supported by the National Natural Science Foundation of China(NSFC,Grant No.11427901)。
文摘The infrared Fourier transform spectrometer needs a cold view field diaphragm to reduce stray radiation.For an infrared spectrometer with linear array detectors,the part of the view field diaphragm where the light passes can be regarded as a slit.If the infrared detectors are small in size,the width of the slit is also small,which will cause serious diffraction phenomena.If the widths of the view field diaphragm and the optical system are designed by geometric optics theory,the diffraction light cannot be fully received by the detectors,which will cause energy loss.Expanding the width of the view field diaphragm will introduce stray radiation.Meanwhile,spectrometer follow-up optics should be set in cold environments to reduce the infrared background of the instrument.Optical materials have different thermal characteristics,the optical and mechanical structures will deform at lowtemperature,and the cold view field diaphragm is installed at room temperature,so it is impossible to guarantee that the cold view field diaphragm remains in its design position when working at low-temperature.This paper solves the above problems by designing an adjustable cold view field diaphragm installed in its cryogenic vacuum chamber.The width and position of the view field diaphragm can be adjusted when working in cold temperatures,without opening the cryogenic vacuum chamber.Contrasting the interference signal obtained by the detectors in the adjustment process,the system can get the most suitable width and position of the cold view field diaphragm.The above works are based on the spectrometer used in the study named Accurate Infrared Magnetic Field Measurements of the Sun.
基金supported by the National Key Research and Development Program of China(grant No.2022YFC2205203)the National Natural Science Foundation of China(grant No.42241118)+1 种基金the Strategic Pilot Study Program of the Chinese Academy of Sciences(grant No.XDB0800103)the Key Incubation Project of Shanghai Astronomical Observatory,CAS.
文摘For some space radio telescopes,the orbit determination accuracy is not high enough,the time synchronization accuracy provided by the satellite platforms is low,and GNSS devices are not available.As a result,a traditional method that relies on GNSS devices to obtain an initial clock offset followed by performing correlation with the calibration source may fail to obtain fringes.Moreover,a brutal force search across the 2D clock offset and fringe rate search plane is computationally expensive.In light of these challenges,we propose a novel time synchronization method that utilizes the spacecraft’s telemetry tone signal.This method employs frequency polynomials derived from Doppler tracking for fringe rotation during the correlation process.By aligning the frequency of the target station precisely with that of the reference station,it is only necessary to split the clock offset search range into multiple time windows,perform correlation for each window,and identify the window with the highest signal-to-noise ratio(SNR).The precise clock offset is determined by combining the residual delay with the initial offset.To validate the method,we observe the Tianwen-1 telemetry signal with the 4.5 m small telescope in the Tianma campus of Shanghai Astronomical Observatory and 40 m telescope in Kunming.The results demonstrate that our method can accurately determine clock offset for a time range as wide as±10 ms,with an SNR slightly higher than that achieved with the delay model.This method is suitable for wide-range time synchronization for space Very Long Baseline Interferometry observations,especially in scenarios involving small antennas with low sensitivity and poor orbit determination accuracy.
基金supported by NSFC under grant Nos.12073046 and 12261141689the project has been provided by the National Development and Reform Commission.
文摘The double revolving fiber positioning technology employed in the Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)represents one of the most successful advancements in large-scale multiobjective spectroscopy.The precision of fiber positioning is crucial,as it directly impacts the observational efficiency of LAMOST.A critical component of the fiber positioning system is the closed-loop control system,which traditionally utilizes the light spot generated at fiber end.However,this study introduces a novel approach based on front-illuminated LAMOST focal plane image measurements.Unlike back-illumination,front-illumination does not necessitate internal lighting in the spectrograph,thus reducing light pollution and eliminating the need for additional photography.This method employs an artificial intelligence model to analyze images captured at the focal plane unit(FPU),using the image of the white ceramic head on the FPU as the data set for training,the model is capable of accurately measuring the fiber positions solely through front-illumination.Preliminary trials indicate that the measurement accuracy achieved using the frontillumination method is approximately 0."13.This level of precision meets the stringent fiber positioning accuracy requirement of LAMOST,set at 0."2.Furthermore,this novel approach demonstrates compatibility with LAMOST’s existing closed-loop fiber control system,offering potential for seamless integration and enhanced operational efficiency.
基金supported by National Key R&D Program of China(2023YFA1609700)Research and Education Integration Funding。
文摘This paper presents a comprehensive analysis of the photometric system of the University of Chinese Academy of Sciences 70 cm Telescope located at the Yan-qi Lake campus of the University of Chinese Academy of Sciences.We evaluated the linearity,bias stability,and dark current of the camera.Utilizing the Johnson-Cousins Blue-Visible-Red-Infrared filter system and an Andor DZ936 charge-coupled device camera,we conducted extensive observations of Landolt standard stars to determine the color terms,atmospheric extinction coefficients,photometric zero-points,and the sky background brightness.The results indicate that this telescope demonstrates excellent performance in photometric calibration and good system performance overall,meeting the requirements for limited scientific research and teaching purposes.
文摘Much of the research has focused on identifying bridge frequencies for health monitoring,while the bridge damping ratio also serves as an important factor in damage detection.This study presents an enhanced method for identifying bridge damping ratios using a two-axle,three-mass test vehicle,relying on wheel responses captured by only two mounted sensors.Damping ratio estimation formulas are derived using both the Hilbert Transform(HT)and Wavelet Transform(WT),with a consistent formulation that confirms accurate estimation is achievable with minimal instrumentation,particularly when addressing the support effect.A comparative analysis of the two signal processing techniques reveals the superior performance of WT in identifying bridge damping ratios.The effectiveness of the proposed procedure and formulas is validated through a detailed parametric study,demonstrating robustness across bridges with varying modal damping ratios and different spans using minimal sensors.Moreover,the present study shows that responses from only the first two spans of a multi-span bridge are sufficient for reliable damping estimation,underscoring the practicality and scalability of the procedure for structural health monitoring applications.
基金supported by the Natural Science Foundation of Fujian Province(No.2020J06008)for Distinguished Young Scholarsthe Fujian Provincial Central Guided Local Science and Technology Development Special Project(No.2022L3078).
文摘The occurrence of geogenic arsenic(As)in groundwater is a global public health concern.However,there remain large gaps in groundwater As data,making it difficult to identify non-compliant domestic wells,partly due to lack of low-cost methods capable of rapid As analysis.Therefore,the development of high through-put and reliable on-site determination methods for inorganic As is essential.Herein,a portable automated analyzer was developed for the determination of arsenite(As(Ⅲ)),arsenate(As(Ⅴ))and phosphate in As contaminated groundwater based on a previously adapted method for molybdenum blue spectrophotometry.After the optimization of the chemical reactions and flow manifold,the system demonstrated a high sample through-put(4.8/h for As(Ⅲ),As(Ⅴ)and phosphate analysis),allowing this system to screen 125 samples in 24 h.Other advantages include low operational costs(0.3 CNY per sample),appropriate sensitivity for contaminated groundwater(detection limits of 4.7μg/L,8.3μg/L and 5.4μg/L for As(Ⅲ),As(Ⅴ)and phosphate,respectively),good linearity(R^(2)>0.9996 at As concentrations up to 1600μg/L)and high precision(relative standard deviations of 3.5% and 2.8% for As(Ⅲ)and As(Ⅴ),respectively).The portable system was successfully used for As speciation analysis in 5 groundwater samples collected from multi-level wells at Yinchuan Plain,northwestern China,with total As concentrations ranging from 75.7 to 295.0μg/L,independently assessing As speciation,providing a promising novel method for the rapid on-site screening of As in tens of millions of domestic wells worldwide.
