[目的/意义]苹果“冰糖心”又称水心病,是一种常见的果实病害,严重的水心病果会随着储藏时间的增加发生霉变,造成食品安全隐患。为实现不同等级水心病苹果快速无损检测,本研究旨在构建有效的分级与可溶性固形物(Soluble Solids Content,...[目的/意义]苹果“冰糖心”又称水心病,是一种常见的果实病害,严重的水心病果会随着储藏时间的增加发生霉变,造成食品安全隐患。为实现不同等级水心病苹果快速无损检测,本研究旨在构建有效的分级与可溶性固形物(Soluble Solids Content,SSC)预测模型。[方法]本研究选取了230个富士苹果,其中正常、轻度、中度、重度水心苹果数量分别为113、61、47和9个,分别采集了400~1000 nm范围的反射光谱和X射线计算机断层成像(X-ray Computed Tomography,X-ray CT)数据,并测定了SSC含量。[结果和讨论]SSC随水心程度加剧呈上升趋势,重度水心苹果呈现更高的光谱反射率,X-ray CT扫描成像观察到水心区域的组织体积平均密度高于健康组织,基于三维重建算法实现不同等级水心苹果内部水心组织可视化分布。基于偏最小二乘判别分析(Partial Least Squares Discriminant Analysis,PLSDA)构建的不同水心程度苹果果实分级模型建模集和测试集准确率分别为98.7%和95.9%;构建不同水心程度苹果果实SSC回归模型,校正集决定系数(Correlation Coefficient of Calibration,R_(C)^(2))为0.962,均方根误差(Root Mean Squares Error of Calibration,RMSEC)为0.264,测试集决定系数(Correlation Coefficient of Prediction,R_(P)^(2))为0.879,均方根误差(Root Mean Squares Error of Prediction,RMSEP)为0.435。[结论]该研究构建的不同水心程度苹果果实分级模型能够实现苹果不同等级水心病的预测,构建的不同水心程度苹果果实SSC回归模型能够较好地预测苹果果实的SSC,为苹果水心病无损检测和品质评估提供了有效方法。展开更多
Indirect X-ray modulation imaging has been adopted in a number of solar missions and provided reconstructed X-ray images of solar flares that are of great scientific importance.However,the assessment of the image qual...Indirect X-ray modulation imaging has been adopted in a number of solar missions and provided reconstructed X-ray images of solar flares that are of great scientific importance.However,the assessment of the image quality of the reconstruction is still difficult,which is particularly useful for scheme design of X-ray imaging systems,testing and improvement of imaging algorithms,and scientific research of X-ray sources.Currently,there is no specified method to quantitatively evaluate the quality of X-ray image reconstruction and the point-spread function(PSF)of an X-ray imager.In this paper,we propose percentage proximity degree(PPD)by considering the imaging characteristics of X-ray image reconstruction and in particular,sidelobes and their effects on imaging quality.After testing a variety of imaging quality assessments in six aspects,we utilized the technique for order preference by similarity to ideal solution to the indices that meet the requirements.Then we develop the final quality index for X-ray image reconstruction,QuIX,which consists of the selected indices and the new PPD.QuIX performs well in a series of tests,including assessment of instrument PSF and simulation tests under different grid configurations,as well as imaging tests with RHESSI data.It is also a useful tool for testing of imaging algorithms,and determination of imaging parameters for both RHESSI and ASO-S/Hard X-ray Imager,such as field of view,beam width factor,and detector selection.展开更多
Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method...Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indirect imaging technique that requires algorithms to reconstruct and optimize images.During the last decade,a variety of algorithms have been developed and improved.However,it is difficult to quantitatively evaluate the image quality of different solutions without a true,reference image of observation.How to choose the values of imaging parameters for these algorithms to get the best performance is also an open question.In this study,we present a detailed test of the characteristics of these algorithms,imaging dynamic range and a crucial parameter for the CLEAN method,clean beam width factor(CBWF).We first used SDO/AIA EUV images to compute DEM maps and calculate thermal X-ray maps.Then these realistic sources and several types of simulated sources are used as the ground truth in the imaging simulations for both RHESSI and ASO-S/HXI.The different solutions are evaluated quantitatively by a number of means.The overall results suggest that EM,PIXON,and CLEAN are exceptional methods for sidelobe elimination,producing images with clear source details.Although MEM_GE,MEM_NJIT,VIS_WV and VIS_CS possess fast imaging processes and generate good images,they too possess associated imperfections unique to each method.The two forward fit algorithms,VF and FF,perform differently,and VF appears to be more robust and useful.We also demonstrated the imaging capability of HXI and available HXI algorithms.Furthermore,the effect of CBWF on image quality was investigated,and the optimal settings for both RHESSI and HXI were proposed.展开更多
BACKGROUND In pediatric age group patients(<18 years old)treated operatively for distal radius/both bone fractures extending imaging beyond the initial postoperative period-particularly in uncomplicated cases-appea...BACKGROUND In pediatric age group patients(<18 years old)treated operatively for distal radius/both bone fractures extending imaging beyond the initial postoperative period-particularly in uncomplicated cases-appears to provide limited additional benefit.AIM To determine the necessary number of follow-up X-rays to use resources efficiently.METHODS Participants included in this study are pediatric age group patients who were treated operatively for distal radius/both bone fractures and were identified from a prospected collected data from the operating room database between the years 2009 and 2017.The data in the study included patients who had distal radius fractures and underwent fixation surgery(n=88).RESULTS When assessing the difference in the odds of conducting 1 or less X-ray compared to 2 or more X-rays in regard to the type of fixation,the only significant difference is the closed reduction fixation method.Patients who underwent closed reduction method procedure have significantly lower odds of having 2 more X-rays compared to those who didn’t have closed reduction method.Open reduction,internal fixation,and other fixation methods(close reduction and internal fixation,debridement,or epiphysiodesis)have higher odds of having two or more X-rays compared to patients who did not receive these methods;however,these odds are not statistically significant.CONCLUSION The findings of this study reveal notable absence of a statistically significant association between the frequency of postoperative X-rays and the outcome of children with distal radius fractures.展开更多
Using the new soft X-ray data from the Macao Science Satellite-1,we studied a solar flare that occurred on 22 June 2023.We found that the centroids of the Ca(around 3.9 keV)and Fe(around 6.7 keV)line features exhibit ...Using the new soft X-ray data from the Macao Science Satellite-1,we studied a solar flare that occurred on 22 June 2023.We found that the centroids of the Ca(around 3.9 keV)and Fe(around 6.7 keV)line features exhibit a rapid shift toward higher energy channels during the flare's rising phase,followed by a gradual decrease during the decay phase.Through precise energy calibration,the centroids are determined with high accuracy.Temperature and velocity are then self-consistently derived by comparing the centroids with those calculated from the synthesized line features using the latest CHIANTI atomic database(ver.10.1).The calculated maximum velocity reaches up to 710±60 km s-1,which significantly exceeds the previously reported values.Our results suggest that the entire shift of soft X-ray lines may occur during the process of chromospheric evaporation.展开更多
During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a rest...During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid slag.In contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive information.Therefore,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding times.The results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles increases.In addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases.In one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the large.These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.展开更多
X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorpho...X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorphous selenium,cadmium telluride zinc,and perovskites,have been utilized in direct conversion X-ray detectors.However,these semiconductor materials are susceptible to temperature-induced performance degradation,crystallization,delamination,uneven lattice growth,radiation damage,and high dark current.This study explores a new approach by coupling an FC40 electronic fluorinated liquid with a specialized high-resolution and high-readout-speed complementary metal-oxide-semiconductor(CMOS)pixel array,specifically the Topmetal II−chip,to fabricate a direct conversion X-ray detector.The fluorinated liquid FC40(molecular formula:C_(21)F_(48)N_(2))is an electronic medium that is minimally affected by temperature and displays no issues with uniform conductivity.It exhibits a low dark current and minimal radiation damage and enables customizable thickness in X-ray absorption.This addresses the limitations inherent in conventional semiconductor-based detectors.In this study,simple X-ray detector imaging tests were conducted,demonstrating the excellent coupling capability between FC40 electronic fluorinated liquid and CMOS chips by the X-ray detector.A spatial resolution of 4.0 lp/mm was measured using a striped line par card,and a relatively clear image of a cockroach was displayed in the digital radiography imaging results.Preliminary test results indicated the feasibility of fabricating an X-ray detector by combining FC40 electronic fluorinated liquid and CMOS chips.Owing to the absence of issues related to chip-material coupling,a high spatial resolution could be achieved by reducing the chip pixel size.This method presents a new avenue for studies on novel liquid-based direct conversion X-ray detectors.展开更多
The paper presents experimental investigation results of crack pattern change in cement pastes caused by external sulfate attack(ESA).To visualize the formation and development of cracks in cement pastes under ESA,an ...The paper presents experimental investigation results of crack pattern change in cement pastes caused by external sulfate attack(ESA).To visualize the formation and development of cracks in cement pastes under ESA,an X-ray computed tomography(X-ray CT)was used,i e,the tomography system of Zeiss Xradia 510 versa.The results indicate that X-CT can monitor the development process and distribution characteristics of the internal cracks of cement pastes under ESA with attack time.In addition,the C3A content in the cement significantly affects the damage mode of cement paste specimens during sulfate erosion.The damage of ordinary Portland cement(OPC)pastes subjected to sulfate attack with high C3A content are severe,while the damage of sulfate resistant Portland cement(SRPC)pastes is much smaller than that of OPC pastes.Furthermore,a quadratic function describes the correlation between the crack volume fraction and development depth for two cement pastes immermed in sulfate solution.展开更多
This study describes the design and performance of a laboratory-based tender X-ray spectrometer for X-ray absorption spectroscopy.The system enables effective absorption spectra to be measured within the 2.0-9.0 keV r...This study describes the design and performance of a laboratory-based tender X-ray spectrometer for X-ray absorption spectroscopy.The system enables effective absorption spectra to be measured within the 2.0-9.0 keV range using Rowland circle geometry;it covers the K edge of 3d transition metals,the L edge of lanthanides,and the M edge of actinides.The spectrometer is configured with a Rowland circle with a diameter of 500 mm and integrates a 250 W liquid metal jet X-ray source,spherical bent crystal analyzer,and energy-resolving silicon drift detector.The X-ray source is installed outside the vacuum chamber and remains fixed,while the analyzer crystals and detector are adjusted to change the Bragg angle,maintaining the Rowland condition.The energy resolution is 0.36-1.30 eV at 2.0-9.0 keV,and the monochromatic flux is approximately 5×10^(5) counts/s at 7040 eV.This study highlights the primary characteristics of the spectrometer and demon-strates its capabilities using selected experimental examples.The successful development of this spectrometer can facilitate research on actinide elements,which are often constrained in synchrotron radiation experiments owing to their radioactivity,thus fostering advancements in related nuclear energy fields.展开更多
In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources i...In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.展开更多
The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more...The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more precise lattice parameters using the interaction points for the pseudo-Kossel pattern obtained from laser-induced X-ray diffraction(XRD).This method has been validated by the analysis of an XRD experiment conducted on iron single crystals.Furthermore,the method was used to calculate the compression ratio and rotated angle of an LiF sample under high pressure loading.This technique provides a robust tool for in-situ characterization of structural changes in single crystals under extreme conditions.It has significant implications for studying the equation of state and phase transitions.展开更多
Operando X-ray diffraction(XRD)is an important characterization tool for real-time monitoring of structural changes in materials under different reaction conditions.In this study,we developed a laboratory-based diffra...Operando X-ray diffraction(XRD)is an important characterization tool for real-time monitoring of structural changes in materials under different reaction conditions.In this study,we developed a laboratory-based diffractometer that could capture a full XRD spectrum within 10 s.The instrument has several advanced features.First,it uses a Ga–In alloy metal-jet X-ray source,thereby achieving high X-ray flux with a brightness of up to 3.0×10^(10) photons/(s·mm^(2)·mrad2).Second,it employs an ellipsoidal mirror with a multilayer coating to produce quasi-parallel monochromatic light characterized by a divergence of 0.6 mrad and an energy resolution of 5.9×10^(−3).Third,it is equipped with a high-efficiency,high-signal-to-noise-ratio Pilatus 3R 1M detector for collecting diffraction signals.These features make the developed instrument applicable in studying rapid phase transitions in lithium-ion batteries,especially under extremely fast charge–discharge conditions.The data quality was comparable to that of synchrotron radiation XRD.展开更多
Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ra...Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.展开更多
Background Schizophrenia is characterised by pervasive cognitive deficits that significantly impair daily functioning and quality of life.Pharmacological treatments have limited efficacy in addressing these deficits,h...Background Schizophrenia is characterised by pervasive cognitive deficits that significantly impair daily functioning and quality of life.Pharmacological treatments have limited efficacy in addressing these deficits,highlighting the need for adjunctive interventions like computerised cognitive training(CCT).Aims This study aimed to evaluate the effects of a 30-session CCT programme on mental well-being and cognitive performance in individuals with schizophrenia.Additionally,it assessed the usability and acceptability of CCT in this population.Methods A double-blind,randomised clinical trial was conducted with 54 participants assigned to intervention and control groups.Cognitive and mental health outcomes were assessed using validated tools such as the Depression Anxiety Stress Scale 21,the Warwick-Edinburgh Mental Wellbeing Scale and the Cambridge Neuropsychological Test Automated Battery.Usability was measured with the System Usability Scale(SUS).Assessments were conducted at baseline,post-intervention and 3 months post-follow-up.Results The CCT intervention significantly improved mental well-being,reduced stress and enhanced working memory(paired associate learning,spatial working memory and spatial span)compared with controls.However,no significant effects were observed for anxiety,depression or executive function.Usability scores were high(SUS=83.51),and compliance rates were strong(92.7%),indicating favourable participant engagement.Conclusion CCT demonstrated potential as an adjunctive treatment for schizophrenia,with significant improvements in targeted cognitive and mental health domains.The high usability and compliance rates support its feasibility for broader implementation.Further research is needed to optimise protocols and explore long-term benefits.CCT offers a promising approach to addressing mental health and cognitive challenges in schizophrenia,particularly for stress and working memory.Its usability and acceptability suggest it could be seamlessly integrated into clinical practice.展开更多
BACKGROUND Schizophrenia is commonly associated with comorbid depression,which exacerbates cognitive impairments and negatively impacts quality of life.Despite the high prevalence and burden of these comorbidities,eff...BACKGROUND Schizophrenia is commonly associated with comorbid depression,which exacerbates cognitive impairments and negatively impacts quality of life.Despite the high prevalence and burden of these comorbidities,effective treatment options,particularly for cognitive dysfunction,remain limited.AIM To evaluate the efficacy of computerized cognitive behavioral therapy(CCBT)with sertraline vs sertraline monotherapy in improving depressive symptoms,cognitive function,and quality of life in schizophrenia and depressive episodes.METHODS In this single-center,randomized controlled trial,68 adults[mean age(SD)=36.5(10.0),57.4%male]with schizophrenia and depressive symptoms were randomly assigned to receive either CCBT with sertraline or sertraline monotherapy during a 4-week hospitalization.The CCBT intervention involved 45-60-minute sessions twice weekly for four weeks.Outcomes included comparisons of depressive symptoms(Calgary depression scale for schizophrenia),cognitive function[MATRICS consensus cognitive battery(MCCB)],and quality of life(36-item short form survey)between the groups.RESULTS The experimental group showed greater improvements in depressive symptoms at 4,8,and 12 weeks compared to the controls,with the most notable difference at 12 weeks[mean difference(MD)=-1.7;P<0.001;Cohen’s d=0.9].Cognitive function improved across all MCCB domains in the experimental group,with higher processing speed scores(MD=4.1;P=0.043;Cohen’s d=0.5)and social cognition scores(MD=4.9;P=0.006;Cohen’s d=0.7)than in the control group.Quality of life,particularly in mental health,was significantly better in the experimental group.CONCLUSION CCBT with sertraline was more effective than sertraline monotherapy for patients with schizophrenia and depressive episodes,supporting its use as an adjunctive therapy.展开更多
A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a...A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a double-foil technique to determine T_(e) by comparing the soft X-ray(SXR)emissivities from the same plasma location through two beryllium(Be)foils of differing thickness.The DSXAI system comprises five photocameras mounted at two different poloidal cross-sections,separated toroidally by 15°,allowing for three distinct poloidal viewing angles.Each photocamera features 20 channels,offering a temporal resolution of approximately 4μs and a spatial resolution of about 8 cm,with no channel overlap.Each photocamera contains two identical optical systems,each defined by an aperture slit and a photodiode array.The double-foil configuration is realized by placing these two optical systems,each with a different Be foil,in close proximity.Initial experimental results demonstrate that the DSXAI diagnostic system performs well,successfully reconstructing 2-dimensional(2D)tomographic SXR emissivity and T_(e) on the HL-2A tokamak.This study provides valuable insights for the future implementation of similar diagnostic systems on fusion reactors like ITER.展开更多
In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing...In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing was performed during X-ray microtomography experiments.Compared with investigations of surface voids by traditional two-dimensional(2D)methods involving post-mortem characterization,three-dimensional(3D)information on void evolution inside optically opaque samples obtained through X-ray microtomography is essential.The Rice and Tracey model and Huang model were applied to predict void growth and show good agreement with experimental data using calibration of the damage parameterα.The void growth kinetics of Ti5321 with bimodal microstructure was analyzed by comparing theαvalue with that of Ti64 for different microstructure morphologies.The damage mechanism of ductile fracture of Ti5321 with bimodal microstructure is discussed.It was found that the size of the voids apparently increases with the triaxiality of stress.Post-mortem scanning electron microscopy(SEM)was also used to demonstrate this damage mechanism of ductile fracture of Ti5321.展开更多
In the evaluation of cementing quality,quantitatively assessing cement density is crucial along with identifying the cementation degree at the interface using acoustic logging.While the 137Cs-based formation density l...In the evaluation of cementing quality,quantitatively assessing cement density is crucial along with identifying the cementation degree at the interface using acoustic logging.While the 137Cs-based formation density logging method is well-suited for density calculation,its reliance on open-hole environmental measurements poses challenges when inspecting cement density.This work focuses on the quantitative calculation of cement density while considering the radioactive hazards to the environment caused by 137Cs source.The proposed approach utilizes a measurement system consisting of an X-Ray source and four gamma detectors.The gamma spectrum characteristics of each detector are analyzed,and the energy spectrum recorded by each detector is distinguished by different energy windows.A forward model is established to relate the gamma counts of each energy window to the formation and cement parameters.By employing a regularized Newton's method based on optimization technique,cement density can be calculated with a controllable error margin of within 0.015 g/cm^(3).Furthermore,even though X-Ray detection has lower sensitivity to formation parameters compared to 137Cs,this method is capable of estimating formation density.Overall,the proposed approach enables the quantitative calculation of cement density and semi-quantitative calculation of formation density,therefore is of significance to the comprehensive evaluation of cementing quality.展开更多
The main scientific payload of Macao Science Satellite-1B is a solar soft X-ray detection unit.To obtain an accurate solar X-ray spectrum,we have designed low-noise,high-throughput electronics.Solar radiation is detec...The main scientific payload of Macao Science Satellite-1B is a solar soft X-ray detection unit.To obtain an accurate solar X-ray spectrum,we have designed low-noise,high-throughput electronics.Solar radiation is detected using a low-leakage silicon drift detector(SDD),which is cooled to-30℃.The SDD output is processed using two parallel shaping amplifiers with peaking times of 315 ns and 65 ns.The amplifiers are designed using two-pole multiple-feedback active low-pass filters optimized to achieve a Bessel response.The differential output of the shaping amplifier generates a bipolar signal.The phase of the differential stage is tuned to ensure zero crossing corresponding to the peak of the shaping amplifier.A high-speed switch is inserted between the shaping amplifier and the peak-hold capacitor,and the peak value is maintained by turning off the switch.Fast and slow peak-hold circuits share a common ADC via time-division multiplexing.Both peak values are sampled for space-background rejection.Traditional pile-up detection methods cannot distinguish pulses that overlap in a fast channel.In this study,the differential of the“fast shaping”is selected,enabling the distinction of events separated by as little as 65ns,which is crucial for solar flare detection.The energy resolution is measured to be 138 eV at 5.90 keV.The centroid drift is less than 3.6 eV between-5℃ and 20℃.Compared with other solar X-ray instruments,this study demonstrates improved energy resolution with a lower peaking time,indicating a higher solar flare detection capability.展开更多
文摘[目的/意义]苹果“冰糖心”又称水心病,是一种常见的果实病害,严重的水心病果会随着储藏时间的增加发生霉变,造成食品安全隐患。为实现不同等级水心病苹果快速无损检测,本研究旨在构建有效的分级与可溶性固形物(Soluble Solids Content,SSC)预测模型。[方法]本研究选取了230个富士苹果,其中正常、轻度、中度、重度水心苹果数量分别为113、61、47和9个,分别采集了400~1000 nm范围的反射光谱和X射线计算机断层成像(X-ray Computed Tomography,X-ray CT)数据,并测定了SSC含量。[结果和讨论]SSC随水心程度加剧呈上升趋势,重度水心苹果呈现更高的光谱反射率,X-ray CT扫描成像观察到水心区域的组织体积平均密度高于健康组织,基于三维重建算法实现不同等级水心苹果内部水心组织可视化分布。基于偏最小二乘判别分析(Partial Least Squares Discriminant Analysis,PLSDA)构建的不同水心程度苹果果实分级模型建模集和测试集准确率分别为98.7%和95.9%;构建不同水心程度苹果果实SSC回归模型,校正集决定系数(Correlation Coefficient of Calibration,R_(C)^(2))为0.962,均方根误差(Root Mean Squares Error of Calibration,RMSEC)为0.264,测试集决定系数(Correlation Coefficient of Prediction,R_(P)^(2))为0.879,均方根误差(Root Mean Squares Error of Prediction,RMSEP)为0.435。[结论]该研究构建的不同水心程度苹果果实分级模型能够实现苹果不同等级水心病的预测,构建的不同水心程度苹果果实SSC回归模型能够较好地预测苹果果实的SSC,为苹果水心病无损检测和品质评估提供了有效方法。
基金supported by the National Natural Science Foundation of China(NSFC)12333010the National Key R&D Program of China 2022YFF0503002+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0560000)the NSFC 11921003supported by the Prominent Postdoctoral Project of Jiangsu Province(2023ZB304)supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,grant No.XDA15320000.
文摘Indirect X-ray modulation imaging has been adopted in a number of solar missions and provided reconstructed X-ray images of solar flares that are of great scientific importance.However,the assessment of the image quality of the reconstruction is still difficult,which is particularly useful for scheme design of X-ray imaging systems,testing and improvement of imaging algorithms,and scientific research of X-ray sources.Currently,there is no specified method to quantitatively evaluate the quality of X-ray image reconstruction and the point-spread function(PSF)of an X-ray imager.In this paper,we propose percentage proximity degree(PPD)by considering the imaging characteristics of X-ray image reconstruction and in particular,sidelobes and their effects on imaging quality.After testing a variety of imaging quality assessments in six aspects,we utilized the technique for order preference by similarity to ideal solution to the indices that meet the requirements.Then we develop the final quality index for X-ray image reconstruction,QuIX,which consists of the selected indices and the new PPD.QuIX performs well in a series of tests,including assessment of instrument PSF and simulation tests under different grid configurations,as well as imaging tests with RHESSI data.It is also a useful tool for testing of imaging algorithms,and determination of imaging parameters for both RHESSI and ASO-S/Hard X-ray Imager,such as field of view,beam width factor,and detector selection.
基金supported by the National Key R&D Program of China 2022YFF0503002the National Natural Science Foundation of China(NSFC,Grant Nos.12333010 and 12233012)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(grant No.XDB0560000)supported by the Prominent Postdoctoral Project of Jiangsu Province(2023ZB304)supported by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,grant No.XDA15320000.
文摘Imaging observations of solar X-ray bursts can reveal details of the energy release process and particle acceleration in flares.Most hard X-ray imagers make use of the modulation-based Fourier transform imaging method,an indirect imaging technique that requires algorithms to reconstruct and optimize images.During the last decade,a variety of algorithms have been developed and improved.However,it is difficult to quantitatively evaluate the image quality of different solutions without a true,reference image of observation.How to choose the values of imaging parameters for these algorithms to get the best performance is also an open question.In this study,we present a detailed test of the characteristics of these algorithms,imaging dynamic range and a crucial parameter for the CLEAN method,clean beam width factor(CBWF).We first used SDO/AIA EUV images to compute DEM maps and calculate thermal X-ray maps.Then these realistic sources and several types of simulated sources are used as the ground truth in the imaging simulations for both RHESSI and ASO-S/HXI.The different solutions are evaluated quantitatively by a number of means.The overall results suggest that EM,PIXON,and CLEAN are exceptional methods for sidelobe elimination,producing images with clear source details.Although MEM_GE,MEM_NJIT,VIS_WV and VIS_CS possess fast imaging processes and generate good images,they too possess associated imperfections unique to each method.The two forward fit algorithms,VF and FF,perform differently,and VF appears to be more robust and useful.We also demonstrated the imaging capability of HXI and available HXI algorithms.Furthermore,the effect of CBWF on image quality was investigated,and the optimal settings for both RHESSI and HXI were proposed.
文摘BACKGROUND In pediatric age group patients(<18 years old)treated operatively for distal radius/both bone fractures extending imaging beyond the initial postoperative period-particularly in uncomplicated cases-appears to provide limited additional benefit.AIM To determine the necessary number of follow-up X-rays to use resources efficiently.METHODS Participants included in this study are pediatric age group patients who were treated operatively for distal radius/both bone fractures and were identified from a prospected collected data from the operating room database between the years 2009 and 2017.The data in the study included patients who had distal radius fractures and underwent fixation surgery(n=88).RESULTS When assessing the difference in the odds of conducting 1 or less X-ray compared to 2 or more X-rays in regard to the type of fixation,the only significant difference is the closed reduction fixation method.Patients who underwent closed reduction method procedure have significantly lower odds of having 2 more X-rays compared to those who didn’t have closed reduction method.Open reduction,internal fixation,and other fixation methods(close reduction and internal fixation,debridement,or epiphysiodesis)have higher odds of having two or more X-rays compared to patients who did not receive these methods;however,these odds are not statistically significant.CONCLUSION The findings of this study reveal notable absence of a statistically significant association between the frequency of postoperative X-rays and the outcome of children with distal radius fractures.
文摘Using the new soft X-ray data from the Macao Science Satellite-1,we studied a solar flare that occurred on 22 June 2023.We found that the centroids of the Ca(around 3.9 keV)and Fe(around 6.7 keV)line features exhibit a rapid shift toward higher energy channels during the flare's rising phase,followed by a gradual decrease during the decay phase.Through precise energy calibration,the centroids are determined with high accuracy.Temperature and velocity are then self-consistently derived by comparing the centroids with those calculated from the synthesized line features using the latest CHIANTI atomic database(ver.10.1).The calculated maximum velocity reaches up to 710±60 km s-1,which significantly exceeds the previously reported values.Our results suggest that the entire shift of soft X-ray lines may occur during the process of chromospheric evaporation.
基金financially supported by the National Natural Science Foundation of China(Nos.52274315 and 52374320)the Fundamental Research Funds for the Central Universities(Nos.FRF-TP-22-011A1 and FRF-DF22-16)。
文摘During the continuous casting process of high-Mn high-Al steels,various types of gases such as Ar need to escape through the top of the mold.In which,the behavior of bubbles traversing the liquid slag serves as a restrictive link,closely associated with viscosity and the thickness of liquid slag.In contrast to two-dimensional surface observation,three-dimensional(3D)analysis method can offer a more intuitive,accurate,and comprehensive information.Therefore,this study employs a 3D X-ray microscope(3D-XRM)to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag,different temperatures,and different holding times.The results indicate that as basicity of slag increases from 0.52 to 1.03,temperature increases from 1423 to 1573 K,the viscosity of slag decreases,the floating rate of bubbles increases.In addition,when holding time increases from 10 to 30 s,the bubbles floating distance increases,and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases.In one word,increasing the basicity,temperature,and holding time leading to an increase in the removal rate of bubbles especially for the large.These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.
基金supported by the National Natural Science Foundation of China(No.12235006)the National Key Research and Development Program of China(No.2020YFE0202002.
文摘X-ray detectors show potential applications in medical imaging,materials science,and nuclear energy.To achieve high detection efficiency and spatial resolution,many conventional semiconductor materials,such as amorphous selenium,cadmium telluride zinc,and perovskites,have been utilized in direct conversion X-ray detectors.However,these semiconductor materials are susceptible to temperature-induced performance degradation,crystallization,delamination,uneven lattice growth,radiation damage,and high dark current.This study explores a new approach by coupling an FC40 electronic fluorinated liquid with a specialized high-resolution and high-readout-speed complementary metal-oxide-semiconductor(CMOS)pixel array,specifically the Topmetal II−chip,to fabricate a direct conversion X-ray detector.The fluorinated liquid FC40(molecular formula:C_(21)F_(48)N_(2))is an electronic medium that is minimally affected by temperature and displays no issues with uniform conductivity.It exhibits a low dark current and minimal radiation damage and enables customizable thickness in X-ray absorption.This addresses the limitations inherent in conventional semiconductor-based detectors.In this study,simple X-ray detector imaging tests were conducted,demonstrating the excellent coupling capability between FC40 electronic fluorinated liquid and CMOS chips by the X-ray detector.A spatial resolution of 4.0 lp/mm was measured using a striped line par card,and a relatively clear image of a cockroach was displayed in the digital radiography imaging results.Preliminary test results indicated the feasibility of fabricating an X-ray detector by combining FC40 electronic fluorinated liquid and CMOS chips.Owing to the absence of issues related to chip-material coupling,a high spatial resolution could be achieved by reducing the chip pixel size.This method presents a new avenue for studies on novel liquid-based direct conversion X-ray detectors.
基金Funded by Chinese National Natural Science Foundation of China(No.U2006224)。
文摘The paper presents experimental investigation results of crack pattern change in cement pastes caused by external sulfate attack(ESA).To visualize the formation and development of cracks in cement pastes under ESA,an X-ray computed tomography(X-ray CT)was used,i e,the tomography system of Zeiss Xradia 510 versa.The results indicate that X-CT can monitor the development process and distribution characteristics of the internal cracks of cement pastes under ESA with attack time.In addition,the C3A content in the cement significantly affects the damage mode of cement paste specimens during sulfate erosion.The damage of ordinary Portland cement(OPC)pastes subjected to sulfate attack with high C3A content are severe,while the damage of sulfate resistant Portland cement(SRPC)pastes is much smaller than that of OPC pastes.Furthermore,a quadratic function describes the correlation between the crack volume fraction and development depth for two cement pastes immermed in sulfate solution.
基金supported by the Instrument and Equipment Development Program of the Chinese Academy of Science(Grant No.YJKYYQ20180066)the National Natural Science Foundation of China(No.22227809)+2 种基金the Shanghai Science and Technology Innovation Action Plan(No.22142200300)the Science and Technology Talents Program of the Shanghai Institute of Applied Physics(No.SINAP-KJZX-202204)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA 0400000).
文摘This study describes the design and performance of a laboratory-based tender X-ray spectrometer for X-ray absorption spectroscopy.The system enables effective absorption spectra to be measured within the 2.0-9.0 keV range using Rowland circle geometry;it covers the K edge of 3d transition metals,the L edge of lanthanides,and the M edge of actinides.The spectrometer is configured with a Rowland circle with a diameter of 500 mm and integrates a 250 W liquid metal jet X-ray source,spherical bent crystal analyzer,and energy-resolving silicon drift detector.The X-ray source is installed outside the vacuum chamber and remains fixed,while the analyzer crystals and detector are adjusted to change the Bragg angle,maintaining the Rowland condition.The energy resolution is 0.36-1.30 eV at 2.0-9.0 keV,and the monochromatic flux is approximately 5×10^(5) counts/s at 7040 eV.This study highlights the primary characteristics of the spectrometer and demon-strates its capabilities using selected experimental examples.The successful development of this spectrometer can facilitate research on actinide elements,which are often constrained in synchrotron radiation experiments owing to their radioactivity,thus fostering advancements in related nuclear energy fields.
基金supported by the National Key R&D Program of China(No.2022YFF0608303)the National Major Scientific Research Instrument Development Project(No.11927805)+4 种基金the NSFC Young Scientists Fund(No.12005134)the Shanghai-XFEL Beamline Project(SBP)(No.31011505505885920161A2101001)the Shanghai Municipal Science and Technology Major Project(No.2017SHZDZX02)the Open Fund of the Key Laboratory for Particle Astrophysics and CosmologyMinistry of Education of China。
文摘In the exploration of celestial bodies,such as Mars,the Moon,and asteroids,X-ray fluorescence analysis has emerged as a critical tool for elemental analysis.However,the varying selection rules and excitation sources introduce complexity.Specifically,these discrepancies can cause variations in the intensities of the characteristic spectral lines emitted by identical elements.These variations,compounded by the minimal energy spacing between these spectral lines,pose substantial challenges for conventional silicon drift detectors(SDD),hindering their ability to accurately differentiate these lines and provide detailed insights into the material structure.To overcome this challenge,a cryogenic X-ray spectrometer based on transition-edge sensor(TES)detector arrays is required to achieve precise measurements.This study measured and analyzed the K-edge characteristic lines of copper and the diverse L-edge characteristic lines of tungsten using a comparative analysis of the electron and X-ray excitation processes.For the electron excitation experiments,copper and tungsten targets were employed as X-ray sources,as they emit distinctive X-ray spectra upon electron-beam bombardment.In the photon excitation experiments,a molybdenum target was used to produce a continuous spectrum with the prominent Mo Kαlines to emit pure copper and tungsten samples.TES detectors were used for the comparative spectroscopic analysis.The initial comparison revealed no substantial differences in the Kαand Kβlines of copper across different excitation sources.Similarly,the Lαlines of tungsten exhibited uniformity under different excitation sources.However,this investigation revealed pronounced differences within the Lβline series.The study found that XRF spectra preferentially excite outer-shell electrons,in contrast to intrinsic spectra,owing to different photon and electron interaction mechanisms.Photon interactions are selection-ruledependent and involve a single electron,whereas electron interactions can involve multiple electrons without such limitations.This leads to varied excitation transitions,as evidenced in the observed Lβline series.
基金National Natural Science Foundation of China(12102410)Fund of National Key Laboratory of Shock Wave and Detonation Physics(JCKYS2022212005)。
文摘The lattice parameter,measured with sufficient accuracy,can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials.We propose an iterative method for obtaining more precise lattice parameters using the interaction points for the pseudo-Kossel pattern obtained from laser-induced X-ray diffraction(XRD).This method has been validated by the analysis of an XRD experiment conducted on iron single crystals.Furthermore,the method was used to calculate the compression ratio and rotated angle of an LiF sample under high pressure loading.This technique provides a robust tool for in-situ characterization of structural changes in single crystals under extreme conditions.It has significant implications for studying the equation of state and phase transitions.
基金supported by“2020 Special Fund for Key Technology and Equipment Development of Major Science and Technology Infrastructure”from the Development and Reform Commission of Shenzhensupport from National Natural Science Foundation of China(Grant No.52103365)Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2021ZT09L227).
文摘Operando X-ray diffraction(XRD)is an important characterization tool for real-time monitoring of structural changes in materials under different reaction conditions.In this study,we developed a laboratory-based diffractometer that could capture a full XRD spectrum within 10 s.The instrument has several advanced features.First,it uses a Ga–In alloy metal-jet X-ray source,thereby achieving high X-ray flux with a brightness of up to 3.0×10^(10) photons/(s·mm^(2)·mrad2).Second,it employs an ellipsoidal mirror with a multilayer coating to produce quasi-parallel monochromatic light characterized by a divergence of 0.6 mrad and an energy resolution of 5.9×10^(−3).Third,it is equipped with a high-efficiency,high-signal-to-noise-ratio Pilatus 3R 1M detector for collecting diffraction signals.These features make the developed instrument applicable in studying rapid phase transitions in lithium-ion batteries,especially under extremely fast charge–discharge conditions.The data quality was comparable to that of synchrotron radiation XRD.
基金supported by the Vinnova(project number 2020-03778)supported by the Swedish Research Council(Vetenskapsradet,project number 2021-04157).
文摘Nano-scale chemical inhomogeneity in surface oxide films formed on a V-and N-containing martensite stainless steel and tempering heating induced changes are investigated by a combination of synchrotron-based hard X-ray Photoelectron emission spectroscopy(HAXPES)and microscopy(HAXPEEM)as well as microscopic X-ray absorption spectroscopy(μ-XAS)techniques.The results reveal the inhomogeneity in the oxide films on the micron-sized Cr_(2)N-and VN-type particles,while the inhomogeneity on the martensite matrix phase exists due to localised formation of nano-sized tempering nitride particles at 600℃.The oxide film formed on Cr_(2)N-type particles is rich in Cr_(2)O_(3) compared with that on the martensite matrix and VN-type particles.With the increase of tempering temperature,Cr_(2)O_(3) formation is faster for the oxidation of Cr in the martensite matrix than the oxidation of Cr nitride-rich particles.
基金supported by a grant from University of Social Welfare and Rehabilitation Sciences for the research expenses.
文摘Background Schizophrenia is characterised by pervasive cognitive deficits that significantly impair daily functioning and quality of life.Pharmacological treatments have limited efficacy in addressing these deficits,highlighting the need for adjunctive interventions like computerised cognitive training(CCT).Aims This study aimed to evaluate the effects of a 30-session CCT programme on mental well-being and cognitive performance in individuals with schizophrenia.Additionally,it assessed the usability and acceptability of CCT in this population.Methods A double-blind,randomised clinical trial was conducted with 54 participants assigned to intervention and control groups.Cognitive and mental health outcomes were assessed using validated tools such as the Depression Anxiety Stress Scale 21,the Warwick-Edinburgh Mental Wellbeing Scale and the Cambridge Neuropsychological Test Automated Battery.Usability was measured with the System Usability Scale(SUS).Assessments were conducted at baseline,post-intervention and 3 months post-follow-up.Results The CCT intervention significantly improved mental well-being,reduced stress and enhanced working memory(paired associate learning,spatial working memory and spatial span)compared with controls.However,no significant effects were observed for anxiety,depression or executive function.Usability scores were high(SUS=83.51),and compliance rates were strong(92.7%),indicating favourable participant engagement.Conclusion CCT demonstrated potential as an adjunctive treatment for schizophrenia,with significant improvements in targeted cognitive and mental health domains.The high usability and compliance rates support its feasibility for broader implementation.Further research is needed to optimise protocols and explore long-term benefits.CCT offers a promising approach to addressing mental health and cognitive challenges in schizophrenia,particularly for stress and working memory.Its usability and acceptability suggest it could be seamlessly integrated into clinical practice.
基金Supported by Fuzhou Science and Technology Plan Project,No.2023-S-028.
文摘BACKGROUND Schizophrenia is commonly associated with comorbid depression,which exacerbates cognitive impairments and negatively impacts quality of life.Despite the high prevalence and burden of these comorbidities,effective treatment options,particularly for cognitive dysfunction,remain limited.AIM To evaluate the efficacy of computerized cognitive behavioral therapy(CCBT)with sertraline vs sertraline monotherapy in improving depressive symptoms,cognitive function,and quality of life in schizophrenia and depressive episodes.METHODS In this single-center,randomized controlled trial,68 adults[mean age(SD)=36.5(10.0),57.4%male]with schizophrenia and depressive symptoms were randomly assigned to receive either CCBT with sertraline or sertraline monotherapy during a 4-week hospitalization.The CCBT intervention involved 45-60-minute sessions twice weekly for four weeks.Outcomes included comparisons of depressive symptoms(Calgary depression scale for schizophrenia),cognitive function[MATRICS consensus cognitive battery(MCCB)],and quality of life(36-item short form survey)between the groups.RESULTS The experimental group showed greater improvements in depressive symptoms at 4,8,and 12 weeks compared to the controls,with the most notable difference at 12 weeks[mean difference(MD)=-1.7;P<0.001;Cohen’s d=0.9].Cognitive function improved across all MCCB domains in the experimental group,with higher processing speed scores(MD=4.1;P=0.043;Cohen’s d=0.5)and social cognition scores(MD=4.9;P=0.006;Cohen’s d=0.7)than in the control group.Quality of life,particularly in mental health,was significantly better in the experimental group.CONCLUSION CCBT with sertraline was more effective than sertraline monotherapy for patients with schizophrenia and depressive episodes,supporting its use as an adjunctive therapy.
基金supported by the National Magnetic Confinement Fusion Science Program of China (Nos.2022YFE03100004,2017YFE0301700,2017YFE0301701 and 2022YFE03060003)National Natural Science Foundation of China (Nos.12375226,12175227,11875255 and 11975231)+2 种基金the China Postdoctoral Science Foundation (No.2022M723066)the Fundamental Research Funds for the Central Universitiesthe Collaborative Innovation Program of Hefei Science Center,CAS (No.2022HSCCIP022)。
文摘A 100-channel double-foil soft X-ray array imaging(DSXAI)diagnostic system has been developed for the HL-2A tokamak to obtain tomographic bremsstrahlung emissivity and electron temperature(T_(e)).This system employs a double-foil technique to determine T_(e) by comparing the soft X-ray(SXR)emissivities from the same plasma location through two beryllium(Be)foils of differing thickness.The DSXAI system comprises five photocameras mounted at two different poloidal cross-sections,separated toroidally by 15°,allowing for three distinct poloidal viewing angles.Each photocamera features 20 channels,offering a temporal resolution of approximately 4μs and a spatial resolution of about 8 cm,with no channel overlap.Each photocamera contains two identical optical systems,each defined by an aperture slit and a photodiode array.The double-foil configuration is realized by placing these two optical systems,each with a different Be foil,in close proximity.Initial experimental results demonstrate that the DSXAI diagnostic system performs well,successfully reconstructing 2-dimensional(2D)tomographic SXR emissivity and T_(e) on the HL-2A tokamak.This study provides valuable insights for the future implementation of similar diagnostic systems on fusion reactors like ITER.
基金supported by the China Postdoctoral Science Foundation(No.2022M720399).
文摘In order to investigate the damage tolerance of a metastable Ti-5Al-3V-3Mo-2Cr-2Zr-1Nb-1Fe(Ti5321)alloy with bimodal microstructure using void growth quantification and micromechanical modeling,in situ tensile testing was performed during X-ray microtomography experiments.Compared with investigations of surface voids by traditional two-dimensional(2D)methods involving post-mortem characterization,three-dimensional(3D)information on void evolution inside optically opaque samples obtained through X-ray microtomography is essential.The Rice and Tracey model and Huang model were applied to predict void growth and show good agreement with experimental data using calibration of the damage parameterα.The void growth kinetics of Ti5321 with bimodal microstructure was analyzed by comparing theαvalue with that of Ti64 for different microstructure morphologies.The damage mechanism of ductile fracture of Ti5321 with bimodal microstructure is discussed.It was found that the size of the voids apparently increases with the triaxiality of stress.Post-mortem scanning electron microscopy(SEM)was also used to demonstrate this damage mechanism of ductile fracture of Ti5321.
基金support of the National Natural Science Foundation of China(U23B20151 and 52171253)National Science Foundation for Young Scientists of Sichuan(2025ZNSFSC1168).
文摘In the evaluation of cementing quality,quantitatively assessing cement density is crucial along with identifying the cementation degree at the interface using acoustic logging.While the 137Cs-based formation density logging method is well-suited for density calculation,its reliance on open-hole environmental measurements poses challenges when inspecting cement density.This work focuses on the quantitative calculation of cement density while considering the radioactive hazards to the environment caused by 137Cs source.The proposed approach utilizes a measurement system consisting of an X-Ray source and four gamma detectors.The gamma spectrum characteristics of each detector are analyzed,and the energy spectrum recorded by each detector is distinguished by different energy windows.A forward model is established to relate the gamma counts of each energy window to the formation and cement parameters.By employing a regularized Newton's method based on optimization technique,cement density can be calculated with a controllable error margin of within 0.015 g/cm^(3).Furthermore,even though X-Ray detection has lower sensitivity to formation parameters compared to 137Cs,this method is capable of estimating formation density.Overall,the proposed approach enables the quantitative calculation of cement density and semi-quantitative calculation of formation density,therefore is of significance to the comprehensive evaluation of cementing quality.
基金supported by the National Natural Science Foundation of China(No.12035020)National Key Scientific Instrument and Equipment Development Projects of China(No.42327802).
文摘The main scientific payload of Macao Science Satellite-1B is a solar soft X-ray detection unit.To obtain an accurate solar X-ray spectrum,we have designed low-noise,high-throughput electronics.Solar radiation is detected using a low-leakage silicon drift detector(SDD),which is cooled to-30℃.The SDD output is processed using two parallel shaping amplifiers with peaking times of 315 ns and 65 ns.The amplifiers are designed using two-pole multiple-feedback active low-pass filters optimized to achieve a Bessel response.The differential output of the shaping amplifier generates a bipolar signal.The phase of the differential stage is tuned to ensure zero crossing corresponding to the peak of the shaping amplifier.A high-speed switch is inserted between the shaping amplifier and the peak-hold capacitor,and the peak value is maintained by turning off the switch.Fast and slow peak-hold circuits share a common ADC via time-division multiplexing.Both peak values are sampled for space-background rejection.Traditional pile-up detection methods cannot distinguish pulses that overlap in a fast channel.In this study,the differential of the“fast shaping”is selected,enabling the distinction of events separated by as little as 65ns,which is crucial for solar flare detection.The energy resolution is measured to be 138 eV at 5.90 keV.The centroid drift is less than 3.6 eV between-5℃ and 20℃.Compared with other solar X-ray instruments,this study demonstrates improved energy resolution with a lower peaking time,indicating a higher solar flare detection capability.
