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
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
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
随着超声和钼靶技术的应用,越来越多的乳腺病灶被检出,如何正确判断其检查结果已成为研究的热点[1]。乳腺影像报告和数据系统（breast imaging reporting and data system,BI-RADS）对规范乳腺影像报告、减少描述混淆以及对临床诊治均...随着超声和钼靶技术的应用,越来越多的乳腺病灶被检出,如何正确判断其检查结果已成为研究的热点[1]。乳腺影像报告和数据系统（breast imaging reporting and data system,BI-RADS）对规范乳腺影像报告、减少描述混淆以及对临床诊治均起着很大的作用[2]。本研究回顾性分析甘肃省肿瘤医院超声和钼靶报告均完整的200例乳腺恶性肿瘤及63例良性病变临床资料，评价BI-RADS分级在乳腺癌诊断中的价值。展开更多
目的:探讨新版(2013年更新版)超声(ultrasound,US)乳腺影像报告数据系统(breast imaging report and data system,BI-RADS)中罗列的指标结合相关临床资料在诊断乳腺癌中的应用情况,评估新版超声BI-RADS(BI-RADS-US)在乳腺癌诊断中的临...目的:探讨新版(2013年更新版)超声(ultrasound,US)乳腺影像报告数据系统(breast imaging report and data system,BI-RADS)中罗列的指标结合相关临床资料在诊断乳腺癌中的应用情况,评估新版超声BI-RADS(BI-RADS-US)在乳腺癌诊断中的临床应用价值。方法:3名超声医师结合收集的临床资料共同对2 860个肿块的声像图进行回顾性分析,按照新版BIRADS超声影像学词典记录、分类。以病理结果为金标准,运用ROC曲线计算新版BI-RADS-US分类的诊断效能。并对记录的超声指标及收集的临床资料先行单因素分析,具有统计学意义的指标再运用多因素logistic回归分析进行分析。结果:新版BIRADS-US诊断乳腺癌BI-RADS 2类的恶性率为0.66%,3类的恶性率0.99%,4a类的恶性率为9.57%,4b类的恶性率为32.31%,4c类的恶性率为88.36%,5类的恶性率为94.19%。以4a类为截断点,新版BI-RADS-US诊断乳腺癌的敏感性为88.55%,特异性为92.17%,准确性为91.75%,AUC为0.948,Youden指数为0.81。结论:新版BI-RADS-US诊断乳腺癌风险分层的准确率高。以4a类作为截断点,新版BI-RADS-US诊断乳腺癌具有较高的诊断效能。肿块形态、边缘、钙化、血流是重要的超声变量,结合患者年龄和腋窝淋巴结转移情况可指导临床进行明确的诊断和精确的治疗。展开更多
目的·探讨2013版超声乳腺影像报告和数据系统(breast imaging reporting and data system,BI-RADS)分类诊断标准结合剪切波弹性成像技术(shear wave elastography,SWE)鉴别乳腺良恶性病灶的价值。方法·对155例患者共175个乳...目的·探讨2013版超声乳腺影像报告和数据系统(breast imaging reporting and data system,BI-RADS)分类诊断标准结合剪切波弹性成像技术(shear wave elastography,SWE)鉴别乳腺良恶性病灶的价值。方法·对155例患者共175个乳腺病灶行常规超声检查,并用BI-RADS分类诊断标准判断其良恶性;再行剪切波弹性成像检测,获得乳腺良恶性病灶的剪切波定量参数。以病理结果为金标准,构建受试者操作特征(ROC)曲线,比较2种方法单独应用及联合应用的诊断价值。结果·BI-RADS分类诊断标准、SWE技术及两者联合鉴别诊断乳腺良恶性结节的曲线下面积(AUC)分别为0.913、0.884和0.957,三者两两比较,2种方法单独使用与两者联合应用的AUC差异皆有统计学意义(BI-RADS分类vs两者联合:Z=2.883,P=0.002;SWE技术vs两者联合:Z=4.081,P=0.000)。结论·BI-RADS分类与SWE技术联合可以提高乳腺病灶的诊断准确性。展开更多
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.
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.
文摘随着超声和钼靶技术的应用,越来越多的乳腺病灶被检出,如何正确判断其检查结果已成为研究的热点[1]。乳腺影像报告和数据系统（breast imaging reporting and data system,BI-RADS）对规范乳腺影像报告、减少描述混淆以及对临床诊治均起着很大的作用[2]。本研究回顾性分析甘肃省肿瘤医院超声和钼靶报告均完整的200例乳腺恶性肿瘤及63例良性病变临床资料，评价BI-RADS分级在乳腺癌诊断中的价值。
文摘目的:探讨新版(2013年更新版)超声(ultrasound,US)乳腺影像报告数据系统(breast imaging report and data system,BI-RADS)中罗列的指标结合相关临床资料在诊断乳腺癌中的应用情况,评估新版超声BI-RADS(BI-RADS-US)在乳腺癌诊断中的临床应用价值。方法:3名超声医师结合收集的临床资料共同对2 860个肿块的声像图进行回顾性分析,按照新版BIRADS超声影像学词典记录、分类。以病理结果为金标准,运用ROC曲线计算新版BI-RADS-US分类的诊断效能。并对记录的超声指标及收集的临床资料先行单因素分析,具有统计学意义的指标再运用多因素logistic回归分析进行分析。结果:新版BIRADS-US诊断乳腺癌BI-RADS 2类的恶性率为0.66%,3类的恶性率0.99%,4a类的恶性率为9.57%,4b类的恶性率为32.31%,4c类的恶性率为88.36%,5类的恶性率为94.19%。以4a类为截断点,新版BI-RADS-US诊断乳腺癌的敏感性为88.55%,特异性为92.17%,准确性为91.75%,AUC为0.948,Youden指数为0.81。结论:新版BI-RADS-US诊断乳腺癌风险分层的准确率高。以4a类作为截断点,新版BI-RADS-US诊断乳腺癌具有较高的诊断效能。肿块形态、边缘、钙化、血流是重要的超声变量,结合患者年龄和腋窝淋巴结转移情况可指导临床进行明确的诊断和精确的治疗。
文摘目的·探讨2013版超声乳腺影像报告和数据系统(breast imaging reporting and data system,BI-RADS)分类诊断标准结合剪切波弹性成像技术(shear wave elastography,SWE)鉴别乳腺良恶性病灶的价值。方法·对155例患者共175个乳腺病灶行常规超声检查,并用BI-RADS分类诊断标准判断其良恶性;再行剪切波弹性成像检测,获得乳腺良恶性病灶的剪切波定量参数。以病理结果为金标准,构建受试者操作特征(ROC)曲线,比较2种方法单独应用及联合应用的诊断价值。结果·BI-RADS分类诊断标准、SWE技术及两者联合鉴别诊断乳腺良恶性结节的曲线下面积(AUC)分别为0.913、0.884和0.957,三者两两比较,2种方法单独使用与两者联合应用的AUC差异皆有统计学意义(BI-RADS分类vs两者联合:Z=2.883,P=0.002;SWE技术vs两者联合:Z=4.081,P=0.000)。结论·BI-RADS分类与SWE技术联合可以提高乳腺病灶的诊断准确性。
