To obtain the certificate of airworthiness,it is essential to conduct a full-scale aircraft static test.During such test,accurate and comprehensive wing deformation measurement is crucial for assessing its strength,st...To obtain the certificate of airworthiness,it is essential to conduct a full-scale aircraft static test.During such test,accurate and comprehensive wing deformation measurement is crucial for assessing its strength,stiffness,and bearing capability.This paper proposes a novel and cost-effective videogrammetric method using multi-camera system to achieve the non-contact,highprecision,and 3D measurement of overall static deformation for the large-scale wing structure.To overcome the difficulties of making,carrying,and employing the large 2D or 3D target for calibrating the cameras with large field of view,a flexible stereo cameras calibration method combining 1D target and epipolar geometry is proposed.The global calibration method,aided by a total station,is employed to unify the 3D data obtained from various binocular subsystems.A series of static load tests using a 10-meter-long large-scale wing have been conducted to validate the proposed system and methods.Furthermore,the proposed method was applied to the practical wing deformation measurement of both wings with a wingspan of 33.6 m in the full-size civil aircraft static test.The overall 3D profile and displacement data of the tested wing under various loads can be accurately obtained.The maximum error of distance and displacement measurement is less than 4.5 mm within the measurement range of 35 m in all load cases.These results demonstrate that the proposed method achieves effective,high-accuracy,on-site,and visualized wing deformation measurement,making it a promising approach for full-scale aircraft wing static test.展开更多
The study of rock failure mechanisms is fundamental to geotechnical engineering,as it enhances design quality and mitigates disaster risks.This research employed in situ compression tests on 3D-printed rocklike sample...The study of rock failure mechanisms is fundamental to geotechnical engineering,as it enhances design quality and mitigates disaster risks.This research employed in situ compression tests on 3D-printed rocklike samples with a single flaw,combining Micro-CT scans and a specialized loading device to analyze their behavior.Mechanical properties and failure modes of these printed samples were compared to those of natural flawed sandstones,demonstrating the capability of 3D printing to replicate natural rock characteristics.By reconstructing 3D crack evolution from 2D CT images and applying digital volume correlation(DVC),the study visualized internal strain fields and established a relationship between strain patterns and rock failure.The results reveal that crack initiation consistently occurs at the flaw,advancing into tensile and secondary shear or mixed cracks.For flaw angles(α)ranging from 0°to 45°,the 3D-printed samples exhibited a higher number of newly formed cracks and a faster increase in crack volume with strain.In contrast,for flaw angles of 45°≤α≤90°,the opposite trend was observed.The internal strain field exhibited significant strain localization,with this uneven distribution playing a critical role in sample failure.When the flaw angle was in the range of 0°≤α≤30°,failure was primarily driven by tensile cracks,forming distinct tensile bands.Conversely,for 30°<α≤90°,a combination of tensile and shear cracks dominated the failure,producing both shear and tensile bands in the sample.Additionally,the strain field component ε_(yy) showed a strong correlation with the evolution of internal damage,providing valuable insights into the underlying rock failure mechanisms.展开更多
In this paper,some basic theories and terms of language testing,like types of language tests and qualities of good tests were briefly discussed.Then CET3(College English Test Band3) in Beijing was analyzed from three ...In this paper,some basic theories and terms of language testing,like types of language tests and qualities of good tests were briefly discussed.Then CET3(College English Test Band3) in Beijing was analyzed from three perspectives:design principles,item formats and test content. In the end,some suggestions were given to improve this test.展开更多
Part One:Quick Responses Please make a quick response to the sentence you will hear.1.I’m really sorry,but I can’t come to your party tonight.2.I’m so upset,Jean,I lost my bag on my way to the Science Museum.
Aim： To investigate wether the corresponding protein of mono-ADP-ribosyltransferase 3 （ART3） mRNA is expressed in human testes and, if so, whether the expression is cell type-specific. Methods： ART3 mRNA was deter...Aim： To investigate wether the corresponding protein of mono-ADP-ribosyltransferase 3 （ART3） mRNA is expressed in human testes and, if so, whether the expression is cell type-specific. Methods： ART3 mRNA was determined in human testes and sperm by reverse transcription-polymerase chain reaction （RT-PCR）. The glycosylphosphatidylinositol linkage of ART3 was shown by treating ART3-transfected HEK-293-T cells with phospholipase C. Fluorescent activated cell sorter （FACS）-analyses were used to detect ART3 on mature spermatozoa and immunohistological studies to detect the protein in testes. Results： ART3 protein was shown to be present in testes. It was found on spermatocytes only. It was absent from spermatogonia, spermatids and spermatozoa. The absence of ART3 from spermatozoa was confirmed by FACS-analysis. ART3 protein was detected neither within a seminoma nor on Leydig cells. Conclusion： Here we show for the first time that ART3 protein is expressed in testes in particular on spermatocytes, indicating that ART3 exerts a specific function only required at a particular stage of spermatogenesis.展开更多
Soil test for availability of nutrients and heavy metals is extensively served as a means for the evaluations of soil fertility, and environmental effects and phytotoxicity of pollutants in soils, and for the fertiliz...Soil test for availability of nutrients and heavy metals is extensively served as a means for the evaluations of soil fertility, and environmental effects and phytotoxicity of pollutants in soils, and for the fertilizer recommendation in agricultural and environmental sciences. Therefore, great attention has been paid to the measurement of elemental availability in soil test.展开更多
The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at ...The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.展开更多
Chang'E-3 probe incorporates four landing gears to assure the soft-landing,which are stowed while launching and deployed after separated from rocket. Deployment reliability is quite crucial for this mission. The d...Chang'E-3 probe incorporates four landing gears to assure the soft-landing,which are stowed while launching and deployed after separated from rocket. Deployment reliability is quite crucial for this mission. The deployment reliability test( DRT) method and assessment method were developed in this paper. Then DRT was conducted and the deployment reliability estimate of Chang'E-3probe was used to verify the proposed methods.展开更多
Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the ra...Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.展开更多
In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is bu...In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors.An algorithm for testing cost and testing order optimization is proposed,and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints.To prove the influence of the optimal stacking order on testing costs,two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared.Based on the benchmarks from ITC 02,experimental results show that for a 5-layer 3D IC,under different constraints,the optimal stacking order can reduce the test costs on average by 13%and 62%,respectively,compared to the pyramid type and inverted pyramid type.Furthermore,with the increase of the stack size,the test costs of the optimized stack order can be decreased.展开更多
The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.T...The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.To address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization process.Smoothness metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D reconstruction.To ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision avoidance.By using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position path.Both orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and DVAO.The reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space trajectory.Simulation and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.展开更多
Aging induces decrease of locomotor capacity and its decrease is associated with an increased risk of falls. Several lines of evidence indicate that both change in muscle power and aerobic fitness are causative. Mobil...Aging induces decrease of locomotor capacity and its decrease is associated with an increased risk of falls. Several lines of evidence indicate that both change in muscle power and aerobic fitness are causative. Mobility tests are usually based on a maximal exercise stress test;however, this test is often difficult and sometimes frightening to older persons. Therefore, the objective of this study was to examine age and gender differences in 3-min walk distance test (3WDT), and time of chair-rising test (CRT) of functional mobility. 153 men and 159 women aged from 20 to 78 years were recruited as subjects of the present study. The body composition measured the height, body mass (BM), body mass index (BMI), lean tissue mass (LTM), and waist circumference (WC). The Functional mobility tests measured the peak oxygen uptake (VO2peak), 3WDT, leg extension strength (LES), and times of CRT. Both in men and women, height and BMI, WC decreased and increased, respectively, with age. Height, BM, LTM, WC in men are higher than in women. We found no correlation between ages and 3WDT in women and a significant, negative correlation in men. All parameters of fitness performance were negatively correlated with age. Both in men and women, all parameters of fitness performance were positively correlated with sex. Both in men and women, VO2peak, 3WDT, and LES decreased with age. All parameters of fitness performance in men are higher than in women. Both in men and women were observed for the correlation between 3WDT and VO2peak, LES and CRT respectively. Although as the correlation coefficient between 3WTD and VO2peak, LES and CRT were low (r = 0.28 - 0.38), an error may occur, this study shows that 3WDT and CRT test can be a feasible method of providing the information for muscle power and aerobic fitness, possibly avoiding the need for a maximal stress test.展开更多
A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yarns and the intertwining between braider yams and axial yams are analy...A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yarns and the intertwining between braider yams and axial yams are analyzed from experimentation. With the microstructure being defined, three levels of unit cell structure are identified, i.e. large unit cell, second unit cell and minimal unit cell. Secondly, based on the minimal unit cell in the interior and on the boundary of the entire cross-section, the deformations of axial yams squashed by braider yams contribute to the increase of the fiber packing factors of axial yams. Finally, the predicted fiber volume fraction of the composites decreases with the increase of linear density of the braider yam and the pitch length. Favorable correlations between the predicted and the experimental results arc found for six groups of the composites.展开更多
文摘To obtain the certificate of airworthiness,it is essential to conduct a full-scale aircraft static test.During such test,accurate and comprehensive wing deformation measurement is crucial for assessing its strength,stiffness,and bearing capability.This paper proposes a novel and cost-effective videogrammetric method using multi-camera system to achieve the non-contact,highprecision,and 3D measurement of overall static deformation for the large-scale wing structure.To overcome the difficulties of making,carrying,and employing the large 2D or 3D target for calibrating the cameras with large field of view,a flexible stereo cameras calibration method combining 1D target and epipolar geometry is proposed.The global calibration method,aided by a total station,is employed to unify the 3D data obtained from various binocular subsystems.A series of static load tests using a 10-meter-long large-scale wing have been conducted to validate the proposed system and methods.Furthermore,the proposed method was applied to the practical wing deformation measurement of both wings with a wingspan of 33.6 m in the full-size civil aircraft static test.The overall 3D profile and displacement data of the tested wing under various loads can be accurately obtained.The maximum error of distance and displacement measurement is less than 4.5 mm within the measurement range of 35 m in all load cases.These results demonstrate that the proposed method achieves effective,high-accuracy,on-site,and visualized wing deformation measurement,making it a promising approach for full-scale aircraft wing static test.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea Government(MOTIE)(Grant No.20214000000500,Training program of CCUS for the green growth)by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(Grant No.2022R1F1A1076409)the support from the Chinese Scholarship Council for awarding a scholarship(CSC No.202106820011).
文摘The study of rock failure mechanisms is fundamental to geotechnical engineering,as it enhances design quality and mitigates disaster risks.This research employed in situ compression tests on 3D-printed rocklike samples with a single flaw,combining Micro-CT scans and a specialized loading device to analyze their behavior.Mechanical properties and failure modes of these printed samples were compared to those of natural flawed sandstones,demonstrating the capability of 3D printing to replicate natural rock characteristics.By reconstructing 3D crack evolution from 2D CT images and applying digital volume correlation(DVC),the study visualized internal strain fields and established a relationship between strain patterns and rock failure.The results reveal that crack initiation consistently occurs at the flaw,advancing into tensile and secondary shear or mixed cracks.For flaw angles(α)ranging from 0°to 45°,the 3D-printed samples exhibited a higher number of newly formed cracks and a faster increase in crack volume with strain.In contrast,for flaw angles of 45°≤α≤90°,the opposite trend was observed.The internal strain field exhibited significant strain localization,with this uneven distribution playing a critical role in sample failure.When the flaw angle was in the range of 0°≤α≤30°,failure was primarily driven by tensile cracks,forming distinct tensile bands.Conversely,for 30°<α≤90°,a combination of tensile and shear cracks dominated the failure,producing both shear and tensile bands in the sample.Additionally,the strain field component ε_(yy) showed a strong correlation with the evolution of internal damage,providing valuable insights into the underlying rock failure mechanisms.
文摘In this paper,some basic theories and terms of language testing,like types of language tests and qualities of good tests were briefly discussed.Then CET3(College English Test Band3) in Beijing was analyzed from three perspectives:design principles,item formats and test content. In the end,some suggestions were given to improve this test.
文摘Part One:Quick Responses Please make a quick response to the sentence you will hear.1.I’m really sorry,but I can’t come to your party tonight.2.I’m so upset,Jean,I lost my bag on my way to the Science Museum.
文摘Aim： To investigate wether the corresponding protein of mono-ADP-ribosyltransferase 3 （ART3） mRNA is expressed in human testes and, if so, whether the expression is cell type-specific. Methods： ART3 mRNA was determined in human testes and sperm by reverse transcription-polymerase chain reaction （RT-PCR）. The glycosylphosphatidylinositol linkage of ART3 was shown by treating ART3-transfected HEK-293-T cells with phospholipase C. Fluorescent activated cell sorter （FACS）-analyses were used to detect ART3 on mature spermatozoa and immunohistological studies to detect the protein in testes. Results： ART3 protein was shown to be present in testes. It was found on spermatocytes only. It was absent from spermatogonia, spermatids and spermatozoa. The absence of ART3 from spermatozoa was confirmed by FACS-analysis. ART3 protein was detected neither within a seminoma nor on Leydig cells. Conclusion： Here we show for the first time that ART3 protein is expressed in testes in particular on spermatocytes, indicating that ART3 exerts a specific function only required at a particular stage of spermatogenesis.
文摘Soil test for availability of nutrients and heavy metals is extensively served as a means for the evaluations of soil fertility, and environmental effects and phytotoxicity of pollutants in soils, and for the fertilizer recommendation in agricultural and environmental sciences. Therefore, great attention has been paid to the measurement of elemental availability in soil test.
基金supported by National Outstanding Young Scientists Founds of China (Grant No. 50825902)National Key Technology R&D Program of China (Grant No. 2008BAF34B15)+2 种基金National Natural Science Foundation of China (Grant No. 51079062)Jiangsu Provincial 333 High-level Personal Training Project of ChinaJiangsu Provincial Six Talent Peak of China
文摘The double blade pump is widely used in sewage treatment industry,however,the research on the internal flow characteristics of the double blade pump with particle image velocimetry（PIV） technology is very little at present.To reveal inner flow characteristics in double blade pump impeller under off-design and design conditions,inner flows in a double blade pump impeller,whose specific speed is 111,are measured under the five off-design conditions and design condition by using 3D PIV test technology.In order to ensure the accuracy of the 3D PIV test,the external trigger synchronization system which makes use of fiber optic and equivalent calibration method are applied.The 3D PIV relative velocity synthesis procedure is compiled by using Visual C＋＋ 2005.Then absolute velocity distribution and relative velocity distribution in the double blade pump impeller are obtained.Test results show that vortex exists in each condition,but the location,size and velocity of vortex core are different.Average absolute velocity value of impeller outlet increases at first,then decreases,and then increases again with increase of flow rate.Again average relative velocity values under 0.4,0.8,and 1.2 design condition are higher than that under 1.0 design condition,while under 0.6 and 1.4 design condition it is lower.Under low flow rate conditions,radial vectors of absolute velocities at impeller outlet and blade inlet near the pump shaft decrease with increase of flow rate,while that of relative velocities at the suction side near the pump shaft decreases.Radial vectors of absolute velocities and relative velocities change slightly under the two large flow rate conditions.The research results can be applied to instruct the hydraulic optimization design of double blade pumps.
基金National Science and Technology Major Project,China
文摘Chang'E-3 probe incorporates four landing gears to assure the soft-landing,which are stowed while launching and deployed after separated from rocket. Deployment reliability is quite crucial for this mission. The deployment reliability test( DRT) method and assessment method were developed in this paper. Then DRT was conducted and the deployment reliability estimate of Chang'E-3probe was used to verify the proposed methods.
基金funded by the National Key R&D Program of China (Grant No. 2021YFB3901402)the Fundamental Research Funds for the Central Universities (Project No. 2022CDJKYJH037)。
文摘Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability.
基金The National Natural Science Foundation of China(No.61674048,61574052,61474036,61371025)the Project of Anhui Institute of Economics and Management(No.YJKT1417T01)
文摘In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high,an optimal stacking order scheme is proposed to reduce the mid-bond test cost.A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors.An algorithm for testing cost and testing order optimization is proposed,and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints.To prove the influence of the optimal stacking order on testing costs,two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared.Based on the benchmarks from ITC 02,experimental results show that for a 5-layer 3D IC,under different constraints,the optimal stacking order can reduce the test costs on average by 13%and 62%,respectively,compared to the pyramid type and inverted pyramid type.Furthermore,with the increase of the stack size,the test costs of the optimized stack order can be decreased.
基金supported by the National Key Research and Development Program of China(2019YFB1707505)the National Natural Science Foundation of China(Grant No.52005436)。
文摘The trend towards automation and intelligence in aircraft final assembly testing has led to a new demand for autonomous perception of unknown cockpit operation scenes in robotic collaborative airborne system testing.To address this demand,a robotic automated 3D reconstruction cell which enables to autonomously plan the robot end-camera’s trajectory is developed for image acquisition and 3D modeling of the cockpit operation scene.A continuous viewpoint path planning algorithm is proposed that incorporates both 3D reconstruction quality and robot path quality into optimization process.Smoothness metrics for viewpoint position paths and orientation paths are introduced together for the first time in 3D reconstruction.To ensure safe and effective movement,two spatial constraints,Domain of View Admissible Position(DVAP)and Domain of View Admissible Orientation(DVAO),are implemented to account for robot reachability and collision avoidance.By using diffeomorphism mapping,the orientation path is transformed into 3D,consistent with the position path.Both orientation and position paths can be optimized in a unified framework to maximize the gain of reconstruction quality and path smoothness within DVAP and DVAO.The reconstruction cell is capable of automatic data acquisition and fine scene modeling,using the generated robot C-space trajectory.Simulation and physical scene experiments have confirmed the effectiveness of the proposed method to achieve highprecision 3D reconstruction while optimizing robot motion quality.
文摘Aging induces decrease of locomotor capacity and its decrease is associated with an increased risk of falls. Several lines of evidence indicate that both change in muscle power and aerobic fitness are causative. Mobility tests are usually based on a maximal exercise stress test;however, this test is often difficult and sometimes frightening to older persons. Therefore, the objective of this study was to examine age and gender differences in 3-min walk distance test (3WDT), and time of chair-rising test (CRT) of functional mobility. 153 men and 159 women aged from 20 to 78 years were recruited as subjects of the present study. The body composition measured the height, body mass (BM), body mass index (BMI), lean tissue mass (LTM), and waist circumference (WC). The Functional mobility tests measured the peak oxygen uptake (VO2peak), 3WDT, leg extension strength (LES), and times of CRT. Both in men and women, height and BMI, WC decreased and increased, respectively, with age. Height, BM, LTM, WC in men are higher than in women. We found no correlation between ages and 3WDT in women and a significant, negative correlation in men. All parameters of fitness performance were negatively correlated with age. Both in men and women, all parameters of fitness performance were positively correlated with sex. Both in men and women, VO2peak, 3WDT, and LES decreased with age. All parameters of fitness performance in men are higher than in women. Both in men and women were observed for the correlation between 3WDT and VO2peak, LES and CRT respectively. Although as the correlation coefficient between 3WTD and VO2peak, LES and CRT were low (r = 0.28 - 0.38), an error may occur, this study shows that 3WDT and CRT test can be a feasible method of providing the information for muscle power and aerobic fitness, possibly avoiding the need for a maximal stress test.
基金This research was funded by Scientific Research Fund of National Ministry of Education (00135)
文摘A comprehensive study of yarn architecture of two-step rectangle 3D braided composites is presented. Firstly, the braided surface, the shapes of yarns and the intertwining between braider yams and axial yams are analyzed from experimentation. With the microstructure being defined, three levels of unit cell structure are identified, i.e. large unit cell, second unit cell and minimal unit cell. Secondly, based on the minimal unit cell in the interior and on the boundary of the entire cross-section, the deformations of axial yams squashed by braider yams contribute to the increase of the fiber packing factors of axial yams. Finally, the predicted fiber volume fraction of the composites decreases with the increase of linear density of the braider yam and the pitch length. Favorable correlations between the predicted and the experimental results arc found for six groups of the composites.
