The purpose of this study was to examine the prevalence of body shape dissatisfaction, weight and physical activity status among university students and predictors for body shape dissatisfaction. A cross sectional stu...The purpose of this study was to examine the prevalence of body shape dissatisfaction, weight and physical activity status among university students and predictors for body shape dissatisfaction. A cross sectional study was carried out in a sample comprising of 368 female and male university students aged 18 years or more at King Faisal University, Saudi Arabia. Body weight, height, Body Shape Questionnaire (BSQ) and physical activity level were used as assessment tools. Chi-square and independent sample T-test were used to assess gender difference. Linear regression analysis was conducted to examine predictors of the body shape dissatisfaction. Overall, 65% of students had normal BMI, more males then females overweight (23%), while more females underweight (16.8%). Females have higher body shape dissatisfaction (33.5%) then males (21.4%), half of males inactive and this percentage increased in females to (73.8%). Overweight males were more dissatisfied with their body shape (10.7%) than females (6.3%). Almost one fifth of inactive males dissatisfied comparable to quarter inactive females dissatisfied with their body shape. Younger age is predictor for body shape dissatisfaction in both genders, also weight in males. BMI and being married female was predictor for body shape dissatisfaction. Collectively results indicate that body shape dissatisfaction and inactive lifestyle were prevalent among females than male’s age, weight;BMI and marital status was the most predictor for body shape dissatisfaction. However developing educational program to promote body shape satisfaction and active lifestyle will be very useful especially among females.展开更多
Scattering and diffraction of elastic in-plane P- and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and...Scattering and diffraction of elastic in-plane P- and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong motion seismologists for over forty years. The case of out-of- plane SH-waves on the same elastic canyon that is semicircular in shape on the half-space surface is the first such problem that was solved by analytic closed-form solutions over forty years ago by Trifunac. The corresponding case of in-plane P- and SV- waves on the same circular canyon is a much more complicated problem because the in-plane P- and SV- scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by Lee and Liu. This paper uses their technique of defining these stress-free scattered waves, which Brandow and Lee previously used to solve the problem of the scattering and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape, to the study of the scattering and diffraction of these in-plane waves on an almost circular arbitrary-shaped alluvial valley.展开更多
针对道路交通环境中车辆和行人目标较小或被遮挡导致的检测精度低以及误检、漏检问题,提出道路目标检测算法RO-YOLOv9。增加小目标检测层,增强算法对小目标的特征学习能力。设计双向与自适应尺度融合特征金字塔网络(bidirectional and a...针对道路交通环境中车辆和行人目标较小或被遮挡导致的检测精度低以及误检、漏检问题,提出道路目标检测算法RO-YOLOv9。增加小目标检测层,增强算法对小目标的特征学习能力。设计双向与自适应尺度融合特征金字塔网络(bidirectional and adaptive scale fusion feature pyramid network,BiASF-FPN)结构,优化多尺度特征融合,保证算法有效捕捉从小尺度到大尺度目标的详细信息。提出OR-RepN4模块,通过重参数化策略,复杂算法结构简单化,提高推理速度。引用Shape-NWD(shape neighborhood weighted decomposition)损失函数,专注边界框形状与尺寸,采用归一化高斯Wasserstein距离平滑回归,实现跨尺度不变性,降低小尺度与遮挡目标的检测误差。实验结果表明,在优化后的SODA10M和BDD100K数据集下,RO-YOLOv9算法的mAP@0.5(mean average precision)分别达到68.1%和56.8%,比YLOLOv9算法提高5.6个百分点和4.4个百分点,并且检测帧率分别达到了55.3帧/s和54.2帧/s,达到检测精度和检测速度的平衡。展开更多
The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The excep...The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The exceptionally high surface-to-volume ratio of nanoparticles imparts remarkable reinforcing potentials,yet it simultaneously gives rise to a prevalent tendency for nanoparticles to agglomerate into clusters within nanocomposites.The agglomeration behavior of the nanoparticles is predominantly influenced by their distinct microstructures and varied weight concentrations.This study investigated the synergistic effects of nanoparticle geometric shape and weight concentration on the dispersion characteristics of nanoparticles and the physical-mechanical performances of nano-reinforced epoxy coatings.Three carbon-based nanoparticles,nanodiamonds(NDs),carbon nanotubes(CNTs),and graphenes(GNPs),were incorporated into epoxy coatings at three weight concentrations(0.5%,1.0%,and 2.0%).The experimental findings reveal that epoxy coatings reinforced with NDs demonstrated the most homogenous dispersion characteristics,lowest viscosity,and reduced porosity among all the nanoparticles,which could be attributed to the spherical geometry shape.Due to the superior physical properties,ND-reinforced nanocomposites displayed the highest abrasion resistance and tensile properties.Specifically,the 1.0wt%ND-reinforced nanocomposites exhibited 60%,52%,and 97%improvements in mass lost,tensile strength,and failure strain,respectively,compared to pure epoxy.Furthermore,the representative volume element(RVE)modeling was employed to validate the experimental results,while highlighting the critical role of nanoparticle agglomeration,orientation,and the presence of voids on the mechanical properties of the nanocomposites.Nano-reinforced epoxy coatings with enhanced mechanical properties are well-suited for application in protective coatings for pipelines,industrial equipment,and automotive parts,where high wear resistance is essential.展开更多
文摘The purpose of this study was to examine the prevalence of body shape dissatisfaction, weight and physical activity status among university students and predictors for body shape dissatisfaction. A cross sectional study was carried out in a sample comprising of 368 female and male university students aged 18 years or more at King Faisal University, Saudi Arabia. Body weight, height, Body Shape Questionnaire (BSQ) and physical activity level were used as assessment tools. Chi-square and independent sample T-test were used to assess gender difference. Linear regression analysis was conducted to examine predictors of the body shape dissatisfaction. Overall, 65% of students had normal BMI, more males then females overweight (23%), while more females underweight (16.8%). Females have higher body shape dissatisfaction (33.5%) then males (21.4%), half of males inactive and this percentage increased in females to (73.8%). Overweight males were more dissatisfied with their body shape (10.7%) than females (6.3%). Almost one fifth of inactive males dissatisfied comparable to quarter inactive females dissatisfied with their body shape. Younger age is predictor for body shape dissatisfaction in both genders, also weight in males. BMI and being married female was predictor for body shape dissatisfaction. Collectively results indicate that body shape dissatisfaction and inactive lifestyle were prevalent among females than male’s age, weight;BMI and marital status was the most predictor for body shape dissatisfaction. However developing educational program to promote body shape satisfaction and active lifestyle will be very useful especially among females.
文摘Scattering and diffraction of elastic in-plane P- and SV-waves by a surface topography such as an elastic canyon at the surface of a half-space is a classical problem which has been studied by earthquake engineers and strong motion seismologists for over forty years. The case of out-of- plane SH-waves on the same elastic canyon that is semicircular in shape on the half-space surface is the first such problem that was solved by analytic closed-form solutions over forty years ago by Trifunac. The corresponding case of in-plane P- and SV- waves on the same circular canyon is a much more complicated problem because the in-plane P- and SV- scattered waves have different wave speeds and together they must have zero normal and shear stresses at the half-space surface. It is not until recently in 2014 that analytic solution for such problem is found by Lee and Liu. This paper uses their technique of defining these stress-free scattered waves, which Brandow and Lee previously used to solve the problem of the scattering and diffraction of these in-plane waves on an almost-circular surface canyon that is arbitrary in shape, to the study of the scattering and diffraction of these in-plane waves on an almost circular arbitrary-shaped alluvial valley.
基金supported by the National Science Foundation(NSF)(No.CMMI-1750316)Pipeline and Hazardous Materials Safety Administration(PHMSA)of U.S.Department of Transportation(No.693JK31950008CAAP).
文摘The addition of nanoparticles serves as an effective reinforcement strategy for polymeric coatings,utilizing their unique characteristics as well as extraordinary mechanical,thermal,and electrical properties.The exceptionally high surface-to-volume ratio of nanoparticles imparts remarkable reinforcing potentials,yet it simultaneously gives rise to a prevalent tendency for nanoparticles to agglomerate into clusters within nanocomposites.The agglomeration behavior of the nanoparticles is predominantly influenced by their distinct microstructures and varied weight concentrations.This study investigated the synergistic effects of nanoparticle geometric shape and weight concentration on the dispersion characteristics of nanoparticles and the physical-mechanical performances of nano-reinforced epoxy coatings.Three carbon-based nanoparticles,nanodiamonds(NDs),carbon nanotubes(CNTs),and graphenes(GNPs),were incorporated into epoxy coatings at three weight concentrations(0.5%,1.0%,and 2.0%).The experimental findings reveal that epoxy coatings reinforced with NDs demonstrated the most homogenous dispersion characteristics,lowest viscosity,and reduced porosity among all the nanoparticles,which could be attributed to the spherical geometry shape.Due to the superior physical properties,ND-reinforced nanocomposites displayed the highest abrasion resistance and tensile properties.Specifically,the 1.0wt%ND-reinforced nanocomposites exhibited 60%,52%,and 97%improvements in mass lost,tensile strength,and failure strain,respectively,compared to pure epoxy.Furthermore,the representative volume element(RVE)modeling was employed to validate the experimental results,while highlighting the critical role of nanoparticle agglomeration,orientation,and the presence of voids on the mechanical properties of the nanocomposites.Nano-reinforced epoxy coatings with enhanced mechanical properties are well-suited for application in protective coatings for pipelines,industrial equipment,and automotive parts,where high wear resistance is essential.
