To investigate the influence of different Talbot grading indices(n-values)on the fatigue damage deterioration and instability behavior of grouted reinforcement body,an increasing-amplitude fatigue loading test was con...To investigate the influence of different Talbot grading indices(n-values)on the fatigue damage deterioration and instability behavior of grouted reinforcement body,an increasing-amplitude fatigue loading test was conducted on grouted reinforcement specimens with different n-values using the multi-functional electro-hydraulic servo-controlled rigidity test system(MTS-815).Acoustic emission(AE)technology was employed to monitor the entire testing process.The fatigue mechanical response mechanism,AE characteristic parameters,and damage modes were analyzed.The results demonstrate that as n-value increases,the mechanical characteristics of the specimens initially increase and then decrease.AE parameters,including the cumulative AE ring counts and energy counts,follow the same trend,and spectral characteristics exhibit a strong correlation with crack evolution.The cumulative AE ring counts damage model reveals a three-phase behavior for the specimens under different n-values.The b-value,which characterizes the scale distribution of cracking events,correlates with the volumetric strain growth rate,showing a more sensitive response.Differences in n-values directly affect the distribution of RA/AF signals and damage modes.The findings provide valuable insights into predicting the destabilization of grouted reinforcement specimens under fatigue disturbance and offer necessary theoretical support for the design and stability control of excavation in fragmented surrounding rock.展开更多
背景痛风性关节炎(GA)是单钠尿酸盐沉积所致的晶体相关性关节病,近年来患病负担持续增加。四妙丸是临床治疗GA的常用中药方剂之一,已被多部相关指南收录或推荐,但其临床获益证据质量及从临床经验、实验研究到临床试验的证据链一致性尚...背景痛风性关节炎(GA)是单钠尿酸盐沉积所致的晶体相关性关节病,近年来患病负担持续增加。四妙丸是临床治疗GA的常用中药方剂之一,已被多部相关指南收录或推荐,但其临床获益证据质量及从临床经验、实验研究到临床试验的证据链一致性尚缺乏系统评价。因此,有必要基于整合证据链法和推荐分级的评估、制订和评价(GRADE)系统对四妙丸治疗GA的有效性证据进行再评价。目的应用GRADE系统与中药有效性评价整合证据链法(Eff-iEC),对四妙丸治疗痛风性关节炎的有效性证据进行全面、系统的再评价。方法计算机检索PubMed、Web of Science、中国知网、维普网、万方数据知识服务平台,检索时限为建库至2025年7月,纳入四妙丸治疗GA的随机对照试验(RCT)、实验研究及临床经验文献,采用Stata 18.0软件进行Meta分析,采用GRADE对结局指标进行证据质量评级,并通过Eff-iEC整合多维度证据。结果经筛选文献后,本研究临床经验证据共纳入1篇古籍文献、4篇指南文献;实验研究和临床试验证据分别纳入5篇实验研究、14篇临床试验文献。临床经验证据显示,四妙丸源自“二妙散”化裁,为清热利湿、通痹止痛的经典方剂,自2009年起被纳入《国家基本药物目录》,并被《国际中医临床实践指南痛风》《痛风及高尿酸血症中西医结合诊疗指南》《痛风和高尿酸血症病证结合诊疗指南》及《高尿酸血症和痛风病证结合诊疗指南》推荐用于治疗GA。Meta分析结果显示,与对照组相比,四妙丸联合常规西医治疗可进一步降低白介素6(IL-6)(6篇文献,n=462,SMD=-1.17,95%CI=-1.59~-0.74,P<0.001)、C反应蛋白(CRP)(5篇文献,n=338,SMD=-0.77,95%CI=-1.12~-0.41,P<0.001)、红细胞沉降率(ESR)(7篇文献,n=477,SMD=-0.96,95%CI=-1.59~-0.34,P=0.002)、肿瘤坏死因子α(TNF-α)(3篇文献,n=240,SMD=-1.84,95%CI=-2.14~-1.54,P<0.001)、视觉模拟评分(VAS)(5篇文献,n=315,SMD=-1.57,95%CI=-2.77~-0.38,P<0.05)及尿酸(UA)水平(10篇文献,n=651,SMD=-1.09,95%CI=-1.57~-0.60,P<0.001),并提高临床有效率(8篇文献,n=576,OR=4.46,95%CI=2.49~8.00,P<0.001)。亚组分析提示,联合用药方案可能是CRP和ESR异质性的重要来源。安全性方面,5篇RCT(400例)报告显示,均未见死亡或严重肝肾功能损害等严重不良事件;观察组不良反应以轻度、可逆事件为主,主要表现为胃肠道反应、头晕及一过性转氨酶升高,发生率为8.0%~23.5%,对照组为4.0%~20.0%。GRADE评价中,四妙丸联合常规西医治疗干预TNF-α、有效率为B级(中等质量证据),IL-6、CRP等指标证据为C级(低质量证据)、ESR、VAS、UA等指标证据为D级(极低质量证据)。Eff-iEC评价中,临床经验证据为A级,实验研究证据为A+级,临床试验证据为B级,综合评定为AA+B(高级证据)。结论现有证据表明,四妙丸联合常规西医治疗痛风性关节炎在缓解疼痛、改善炎症反应、降低UA水平及提高临床疗效方面具有一定优势,且短期应用安全性良好。尽管GRADE评价显示当前临床试验证据质量整体偏低,但Eff-iEC评价表明其已形成较完整证据链,综合证据等级为高级。未来仍需开展高质量随机对照试验,以进一步验证其临床获益。展开更多
In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’d...In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.展开更多
The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to ...The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.展开更多
The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have ...The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have been incorporated into the typical Al@AP composites through the spray drying technique.The thermal behavior,ignition and combustion characteristics were comprehensively evaluated and compared.The experimental results showed that with the varying inclusion of the graded Al,the heat of reaction exhibited a significant change,ranging from 9090 J·g^(-1) to 11036 J·g^(-1),which was strongly dependent on the particle size of Al.The combination of Al with diverse range of particle sizes in graded configuration serves to significantly enhance the decomposition of AP,resulting in the disappearance of the LTD stage and a conspicuous decrease of at least 11.7℃ in the peak temperature of the HTD.Furthermore,the maximum burning rate achieved by the Al-3@AP composite was 33.6 mm·s^(-1),which was exactly twice as high as that of the graded Al-1@AP composite with the lowest burning rate.Diffraction peaks corresponding to unburned Al were detected in the condensed combustion products of Al-1@AP,and the combustion images clearly indicated an incomplete combustion tendency for this sample.In contrast,a well-designed gradation of Al powders,such as a combination of fine Al powders with a particle size below 5μm,has proven to be the most conducive to enhancing the combustion efficiency of the composites.展开更多
Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis r...Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis remain significant challenges.This research aims to develop an effective computational method for analyzing the free vibration of functionally graded(FG)microplates under high temperatures while resting on a Pasternak foundation(PF).This formulation leverages a new thirdorder shear deformation theory(new TSDT)for improved accuracy without requiring shear correction factors.Additionally,the modified couple stress theory(MCST)is incorporated to account for sizedependent effects in microplates.The PF is characterized by two parameters including spring stiffness(k_(w))and shear layer stiffness(k_(s)).To validate the proposed method,the results obtained are compared with those of the existing literature.Furthermore,numerical examples explore the influence of various factors on the high-temperature free vibration of FG microplates.These factors include the length scale parameter(l),geometric dimensions,material properties,and the presence of the elastic foundation.The findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the results of this research will have great potential in military and defense applications such as components of submarines,fighter aircraft,and missiles.展开更多
In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-ele...In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.展开更多
目的对中药治疗特发性肺纤维化系统评价/Meta分析进行再评价研究,以期为临床医师及研究者提供更科学的决策支持。方法检索中药治疗特发性肺纤维化系统评价/Meta分析的文献,筛选文献后提取资料,采用AMSTAR2(A Measurement Tool To Assess...目的对中药治疗特发性肺纤维化系统评价/Meta分析进行再评价研究,以期为临床医师及研究者提供更科学的决策支持。方法检索中药治疗特发性肺纤维化系统评价/Meta分析的文献,筛选文献后提取资料,采用AMSTAR2(A Measurement Tool To Assess Systematic Reviews 2)量表和GRADE(Grade of Recommendation,Assessment,Development,and Evaluation)系统工具进行评估。结果共纳入14篇文献,106次结局指标;AMSTAR2量表结果示3篇属于低质量,11篇属于极低质量;GRADE分级显示,10次结局指标证据质量等级中等,83次等级低,13次等级极低。结论中药治疗特发性肺纤维化系统评价/Meta分析的方法学质量为低、极低,结局指标的证据质量等级多为低,高质量、证据强度高级别的系统评价亟需开展,从而作为高级别证据来指导临床。展开更多
基金Project(2022YFC2905600)supported by the National Key R&D Program of ChinaProjects(52474091,52204084)supported by the National Natural Science Foundation of ChinaProject(KLDCRMMOE24KF06)supported by the Foundation of Key Laboratory of Deep Coal Resource Mining(China University of Mining and Technology),Ministry of Education。
文摘To investigate the influence of different Talbot grading indices(n-values)on the fatigue damage deterioration and instability behavior of grouted reinforcement body,an increasing-amplitude fatigue loading test was conducted on grouted reinforcement specimens with different n-values using the multi-functional electro-hydraulic servo-controlled rigidity test system(MTS-815).Acoustic emission(AE)technology was employed to monitor the entire testing process.The fatigue mechanical response mechanism,AE characteristic parameters,and damage modes were analyzed.The results demonstrate that as n-value increases,the mechanical characteristics of the specimens initially increase and then decrease.AE parameters,including the cumulative AE ring counts and energy counts,follow the same trend,and spectral characteristics exhibit a strong correlation with crack evolution.The cumulative AE ring counts damage model reveals a three-phase behavior for the specimens under different n-values.The b-value,which characterizes the scale distribution of cracking events,correlates with the volumetric strain growth rate,showing a more sensitive response.Differences in n-values directly affect the distribution of RA/AF signals and damage modes.The findings provide valuable insights into predicting the destabilization of grouted reinforcement specimens under fatigue disturbance and offer necessary theoretical support for the design and stability control of excavation in fragmented surrounding rock.
文摘背景痛风性关节炎(GA)是单钠尿酸盐沉积所致的晶体相关性关节病,近年来患病负担持续增加。四妙丸是临床治疗GA的常用中药方剂之一,已被多部相关指南收录或推荐,但其临床获益证据质量及从临床经验、实验研究到临床试验的证据链一致性尚缺乏系统评价。因此,有必要基于整合证据链法和推荐分级的评估、制订和评价(GRADE)系统对四妙丸治疗GA的有效性证据进行再评价。目的应用GRADE系统与中药有效性评价整合证据链法(Eff-iEC),对四妙丸治疗痛风性关节炎的有效性证据进行全面、系统的再评价。方法计算机检索PubMed、Web of Science、中国知网、维普网、万方数据知识服务平台,检索时限为建库至2025年7月,纳入四妙丸治疗GA的随机对照试验(RCT)、实验研究及临床经验文献,采用Stata 18.0软件进行Meta分析,采用GRADE对结局指标进行证据质量评级,并通过Eff-iEC整合多维度证据。结果经筛选文献后,本研究临床经验证据共纳入1篇古籍文献、4篇指南文献;实验研究和临床试验证据分别纳入5篇实验研究、14篇临床试验文献。临床经验证据显示,四妙丸源自“二妙散”化裁,为清热利湿、通痹止痛的经典方剂,自2009年起被纳入《国家基本药物目录》,并被《国际中医临床实践指南痛风》《痛风及高尿酸血症中西医结合诊疗指南》《痛风和高尿酸血症病证结合诊疗指南》及《高尿酸血症和痛风病证结合诊疗指南》推荐用于治疗GA。Meta分析结果显示,与对照组相比,四妙丸联合常规西医治疗可进一步降低白介素6(IL-6)(6篇文献,n=462,SMD=-1.17,95%CI=-1.59~-0.74,P<0.001)、C反应蛋白(CRP)(5篇文献,n=338,SMD=-0.77,95%CI=-1.12~-0.41,P<0.001)、红细胞沉降率(ESR)(7篇文献,n=477,SMD=-0.96,95%CI=-1.59~-0.34,P=0.002)、肿瘤坏死因子α(TNF-α)(3篇文献,n=240,SMD=-1.84,95%CI=-2.14~-1.54,P<0.001)、视觉模拟评分(VAS)(5篇文献,n=315,SMD=-1.57,95%CI=-2.77~-0.38,P<0.05)及尿酸(UA)水平(10篇文献,n=651,SMD=-1.09,95%CI=-1.57~-0.60,P<0.001),并提高临床有效率(8篇文献,n=576,OR=4.46,95%CI=2.49~8.00,P<0.001)。亚组分析提示,联合用药方案可能是CRP和ESR异质性的重要来源。安全性方面,5篇RCT(400例)报告显示,均未见死亡或严重肝肾功能损害等严重不良事件;观察组不良反应以轻度、可逆事件为主,主要表现为胃肠道反应、头晕及一过性转氨酶升高,发生率为8.0%~23.5%,对照组为4.0%~20.0%。GRADE评价中,四妙丸联合常规西医治疗干预TNF-α、有效率为B级(中等质量证据),IL-6、CRP等指标证据为C级(低质量证据)、ESR、VAS、UA等指标证据为D级(极低质量证据)。Eff-iEC评价中,临床经验证据为A级,实验研究证据为A+级,临床试验证据为B级,综合评定为AA+B(高级证据)。结论现有证据表明,四妙丸联合常规西医治疗痛风性关节炎在缓解疼痛、改善炎症反应、降低UA水平及提高临床疗效方面具有一定优势,且短期应用安全性良好。尽管GRADE评价显示当前临床试验证据质量整体偏低,但Eff-iEC评价表明其已形成较完整证据链,综合证据等级为高级。未来仍需开展高质量随机对照试验,以进一步验证其临床获益。
文摘In this paper a fully parametrized finite element simulation model of the stator bar end is created using the COMSOL Multiphysics.The model allows conducting the comparison of different corona protection structures’design,various materials properties,and finally optimizing the corona protection system.Several samples of SiC based nonlinear conductivity materials for corona protection were fabricated in laboratory and then investigated.The conductivity dependencies on electric field(0.05 to 1 kV/mm)and temperature(20 to 155℃)were measured.By comparing the heat-resistant grades of the corona protection material and the insulating material,the maximum working temperature of the corona protection material corresponds to the heat-resistant grade F of the insulating material.As the temperature increases,the nonlinear characteristics of the corona protection material in the experiment decrease dramatically,reducing the heat-resistant grade of the corona protection material.The decrease in the nonlinear characteristics of the corona protection material at the maximum operating temperature causes the maximum electric field strength at the end of the HV rotating machines end corona protection(ECP)exceeding the corona discharge electric field strength,resulting in corona phenomenon.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(Grant No.2021B0301030001)the National Key Research and Development Program of China(Grant No.2021YFB3802300)the Foundation of National Key Laboratory of Shock Wave and Detonation Physics(Grant No.JCKYS2022212004)。
文摘The graded density impactor(GDI)dynamic loading technique is crucial for acquiring the dynamic physical property parameters of materials used in weapons.The accuracy and timeliness of GDI structural design are key to achieving controllable stress-strain rate loading.In this study,we have,for the first time,combined one-dimensional fluid computational software with machine learning methods.We first elucidated the mechanisms by which GDI structures control stress and strain rates.Subsequently,we constructed a machine learning model to create a structure-property response surface.The results show that altering the loading velocity and interlayer thickness has a pronounced regulatory effect on stress and strain rates.In contrast,the impedance distribution index and target thickness have less significant effects on stress regulation,although there is a matching relationship between target thickness and interlayer thickness.Compared with traditional design methods,the machine learning approach offers a10^(4)—10^(5)times increase in efficiency and the potential to achieve a global optimum,holding promise for guiding the design of GDI.
文摘The utilization of graded Al powders offers the possibility to adjust the combustion performance of Al powders,while simultaneously safeguarding their energy properties.In this paper,a series of graded Al powder have been incorporated into the typical Al@AP composites through the spray drying technique.The thermal behavior,ignition and combustion characteristics were comprehensively evaluated and compared.The experimental results showed that with the varying inclusion of the graded Al,the heat of reaction exhibited a significant change,ranging from 9090 J·g^(-1) to 11036 J·g^(-1),which was strongly dependent on the particle size of Al.The combination of Al with diverse range of particle sizes in graded configuration serves to significantly enhance the decomposition of AP,resulting in the disappearance of the LTD stage and a conspicuous decrease of at least 11.7℃ in the peak temperature of the HTD.Furthermore,the maximum burning rate achieved by the Al-3@AP composite was 33.6 mm·s^(-1),which was exactly twice as high as that of the graded Al-1@AP composite with the lowest burning rate.Diffraction peaks corresponding to unburned Al were detected in the condensed combustion products of Al-1@AP,and the combustion images clearly indicated an incomplete combustion tendency for this sample.In contrast,a well-designed gradation of Al powders,such as a combination of fine Al powders with a particle size below 5μm,has proven to be the most conducive to enhancing the combustion efficiency of the composites.
文摘Recent advancements in additive manufacturing(AM)have revolutionized the design and production of complex engineering microstructures.Despite these advancements,their mathematical modeling and computational analysis remain significant challenges.This research aims to develop an effective computational method for analyzing the free vibration of functionally graded(FG)microplates under high temperatures while resting on a Pasternak foundation(PF).This formulation leverages a new thirdorder shear deformation theory(new TSDT)for improved accuracy without requiring shear correction factors.Additionally,the modified couple stress theory(MCST)is incorporated to account for sizedependent effects in microplates.The PF is characterized by two parameters including spring stiffness(k_(w))and shear layer stiffness(k_(s)).To validate the proposed method,the results obtained are compared with those of the existing literature.Furthermore,numerical examples explore the influence of various factors on the high-temperature free vibration of FG microplates.These factors include the length scale parameter(l),geometric dimensions,material properties,and the presence of the elastic foundation.The findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the findings significantly enhance our comprehension of the free vibration of FG microplates in high thermal environments.In addition,the results of this research will have great potential in military and defense applications such as components of submarines,fighter aircraft,and missiles.
文摘In this paper,the isogeometric analysis(IGA)method is employed to analyze the oscillation characteristics of functionally graded triply periodic minimal surface(FG-TPMS)curved-doubly shells integrated with magneto-electric surface layers(referred to as"FG-TPMS-MEE curved-doubly shells")subjected to low-velocity impact loads.This study presents low-velocity impact load model based on a single springmass(S-M)approach.The FG-TPMS-MEE curved-doubly shells are covered with two magneto-electric surface layers,while the core layer consists of three types:I-graph and Wrapped Package-graph(IWP),Gyroid(G),and Primitive(P),with various graded functions.These types are notable for their exceptional stiffness-to-weight ratios,enabling a wide range of potential applications.The Maxwell equations and electromagnetic boundary conditions are applied to compute the change in electric potentials and magnetic potentials.The equilibrium equations of the shell are derived from a refined higher-order shear deformation theory(HSDT),and the transient responses of the FG-TPMS-MEE curveddoubly shells are subsequently determined using Newmark's direct integration method.These results have applications in structural vibration control and the analysis of structures subjected to impact or explosive loads.Furthermore,this study provides a theoretical prediction of the low-velocity impact load and magneto-electric-elastic effects on the free vibration and transient response of FG-TPMS-MEE curved-doubly shells.
