Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh...Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh form and excellent rigidity. In order to further understand the buckling behaviors of single layer two-way grid cylindrical shell roof with tension members,the buckling experiments have been undertaken to investigate the effect of tension members,in either out-of-plane or in-plane placement. A single layer two-way grid cylindrical shell roof with out-of-plane tension members has been tested under symmetric and asymmetric loading. The tension member placement,the introducing initial axial force to tension members and the load patterns are considered to investigate the buckling behavior. Experimental results indicate that four long out-ofplane tension members work well under symmetrical loading,but only two long out-of-plane tension members work under asymmetrical loading. It can be concluded that the PC bar members used as tension members for this study are useful in the construction of a single layer two-way grid cylindrical shell roof with structural members intersecting at small angles.展开更多
Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduc...Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduction in a semi-infinite boundary condition is studied and the theoretical formula of single-side TPS method is deduced. During the measurement, the influence of the probe heat capacity on the results is analyzed and the corresponding mathematical compensation model is established, and a series of experiments on different materials are conducted by hot disk probe at normal temperature and pressure. The results show that the relative error with the single-side TPS method is less than 5% and the relative standard deviation is no greater than 3%. This method has high accuracy and good reproducibility, which provides a feasible measuring method for single material that does not meet the requirements of the standard TPS theory.展开更多
目的:探讨腹横肌平面阻滞(TAPB)与切口局部浸润麻醉(LIA)对单孔腹腔镜胆囊切除术(SILC)患者切口疼痛及炎症应激反应的影响。方法:选择2022年6月—2024年6月中山市东凤人民医院普外科收治的94例接受SILC的患者,并随机分为两组,每组47例...目的:探讨腹横肌平面阻滞(TAPB)与切口局部浸润麻醉(LIA)对单孔腹腔镜胆囊切除术(SILC)患者切口疼痛及炎症应激反应的影响。方法:选择2022年6月—2024年6月中山市东凤人民医院普外科收治的94例接受SILC的患者,并随机分为两组,每组47例。两组均接受SILC,观察组进行TAPB,对照组进行切口LIA。比较两组数字分级评分法(NRS)、炎症因子[肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-8(IL-8)]水平及住院时间。结果:观察组术后30 min、2 h、6 h NRS评分均显著低于对照组,差异均有统计学意义(P<0.05)。术后1周,观察组TNF-α、IL-6、IL-8水平均低于对照组,差异均有统计学意义(P<0.05)。观察组住院时间短于对照组(P<0.05)。结论:TAPB应用于SILC患者,不仅可显著减轻患者疼痛程度,还可减轻炎症应激反应,促进患者快速康复。展开更多
The plane metrology using a single uncalibrated image is studied in the paper, and three novel approaches are proposed. The first approach, namely key-line-based method, is an improvement over the widely used key-poin...The plane metrology using a single uncalibrated image is studied in the paper, and three novel approaches are proposed. The first approach, namely key-line-based method, is an improvement over the widely used key-point-based method, which uses line correspondences directly to compute homography between the world plane and its image so as to increase the computational accuracy. The second and third approaches are both based on a pair of vanishing points from two orthogonal sets of parallel lines in the space plane together with two unparallel referential distances, but the two methods deal with the problem in different ways. One is from the algebraic viewpoint which first maps the image points to an affine space via a transformation constructed from the vanishing points, and then computes the metric distance according to the relationship between the affine space and the Euclidean space, while the other is from the geometrical viewpoint based on the invariance of cross ratios. The second and third methods avoid the selection of control points and are widely applicable. In addition, a brief description on how to retrieve other geometrical entities on the space plane, such as distance from a point to a line, angle formed by two lines, etc., is also presented in the paper. Extensive experiments on simulated data as well as on real images show that the first and the second approaches are of better precision and stronger robustness than the key-point-based one and the third one, since these two approaches are fundamentally based on line information.展开更多
为研究飞秒激光打孔和电火花打孔工艺对镍基单晶涡轮叶片高周疲劳寿命的影响,分别建立两种打孔方式的有限元模型。在有限元计算过程中,结合镍基单晶本构特点和晶体塑性滑移理论,编写单晶本构模型的用户材料子程序(User Defined Material...为研究飞秒激光打孔和电火花打孔工艺对镍基单晶涡轮叶片高周疲劳寿命的影响,分别建立两种打孔方式的有限元模型。在有限元计算过程中,结合镍基单晶本构特点和晶体塑性滑移理论,编写单晶本构模型的用户材料子程序(User Defined Material Mechanical Behavior,UMAT),计算得到高周疲劳边界条件下镍基单晶各个滑移面上的分切应力分布。针对特定应力状态下开动的滑移系和滑移面,基于临界平面法建立不同的损伤判据。选取适用于飞秒激光打孔和电火花打孔工艺镍基单晶涡轮叶片的损伤判据,分别建立高周疲劳寿命预测模型,预测两种打孔方式单晶试件和单晶涡轮叶片的高周疲劳寿命,并与实际高周疲劳试验结果进行对比,计算得到的试件和涡轮叶片的寿命预测结果与试验寿命对比误差在10%左右。研究成果为优化航空发动机涡轮叶片加工工艺提供了借鉴。展开更多
基金Sponsored by the Postdoctoral Science Foundation of China(Grant No.2015M571422)Heilongjiang Province Postdoctoral Science Foundation(Grant No.LBH-Z14095)"Young Talents"Project of Northeast Agricultural University(Grant No.14QC50)
文摘Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roofs. Compared with traditional single-layer latticed shells,this new type has a unique mesh form and excellent rigidity. In order to further understand the buckling behaviors of single layer two-way grid cylindrical shell roof with tension members,the buckling experiments have been undertaken to investigate the effect of tension members,in either out-of-plane or in-plane placement. A single layer two-way grid cylindrical shell roof with out-of-plane tension members has been tested under symmetric and asymmetric loading. The tension member placement,the introducing initial axial force to tension members and the load patterns are considered to investigate the buckling behavior. Experimental results indicate that four long out-ofplane tension members work well under symmetrical loading,but only two long out-of-plane tension members work under asymmetrical loading. It can be concluded that the PC bar members used as tension members for this study are useful in the construction of a single layer two-way grid cylindrical shell roof with structural members intersecting at small angles.
文摘Based on the traditional measurement theory of transient plane source (TPS) technique, single-side TPS method is proposed for measuring the thermal conductivity of single specimen. The problem of transient heat conduction in a semi-infinite boundary condition is studied and the theoretical formula of single-side TPS method is deduced. During the measurement, the influence of the probe heat capacity on the results is analyzed and the corresponding mathematical compensation model is established, and a series of experiments on different materials are conducted by hot disk probe at normal temperature and pressure. The results show that the relative error with the single-side TPS method is less than 5% and the relative standard deviation is no greater than 3%. This method has high accuracy and good reproducibility, which provides a feasible measuring method for single material that does not meet the requirements of the standard TPS theory.
文摘目的:探讨腹横肌平面阻滞(TAPB)与切口局部浸润麻醉(LIA)对单孔腹腔镜胆囊切除术(SILC)患者切口疼痛及炎症应激反应的影响。方法:选择2022年6月—2024年6月中山市东凤人民医院普外科收治的94例接受SILC的患者,并随机分为两组,每组47例。两组均接受SILC,观察组进行TAPB,对照组进行切口LIA。比较两组数字分级评分法(NRS)、炎症因子[肿瘤坏死因子-α(TNF-α)、白细胞介素-6(IL-6)、白细胞介素-8(IL-8)]水平及住院时间。结果:观察组术后30 min、2 h、6 h NRS评分均显著低于对照组,差异均有统计学意义(P<0.05)。术后1周,观察组TNF-α、IL-6、IL-8水平均低于对照组,差异均有统计学意义(P<0.05)。观察组住院时间短于对照组(P<0.05)。结论:TAPB应用于SILC患者,不仅可显著减轻患者疼痛程度,还可减轻炎症应激反应,促进患者快速康复。
文摘The plane metrology using a single uncalibrated image is studied in the paper, and three novel approaches are proposed. The first approach, namely key-line-based method, is an improvement over the widely used key-point-based method, which uses line correspondences directly to compute homography between the world plane and its image so as to increase the computational accuracy. The second and third approaches are both based on a pair of vanishing points from two orthogonal sets of parallel lines in the space plane together with two unparallel referential distances, but the two methods deal with the problem in different ways. One is from the algebraic viewpoint which first maps the image points to an affine space via a transformation constructed from the vanishing points, and then computes the metric distance according to the relationship between the affine space and the Euclidean space, while the other is from the geometrical viewpoint based on the invariance of cross ratios. The second and third methods avoid the selection of control points and are widely applicable. In addition, a brief description on how to retrieve other geometrical entities on the space plane, such as distance from a point to a line, angle formed by two lines, etc., is also presented in the paper. Extensive experiments on simulated data as well as on real images show that the first and the second approaches are of better precision and stronger robustness than the key-point-based one and the third one, since these two approaches are fundamentally based on line information.
文摘为研究飞秒激光打孔和电火花打孔工艺对镍基单晶涡轮叶片高周疲劳寿命的影响,分别建立两种打孔方式的有限元模型。在有限元计算过程中,结合镍基单晶本构特点和晶体塑性滑移理论,编写单晶本构模型的用户材料子程序(User Defined Material Mechanical Behavior,UMAT),计算得到高周疲劳边界条件下镍基单晶各个滑移面上的分切应力分布。针对特定应力状态下开动的滑移系和滑移面,基于临界平面法建立不同的损伤判据。选取适用于飞秒激光打孔和电火花打孔工艺镍基单晶涡轮叶片的损伤判据,分别建立高周疲劳寿命预测模型,预测两种打孔方式单晶试件和单晶涡轮叶片的高周疲劳寿命,并与实际高周疲劳试验结果进行对比,计算得到的试件和涡轮叶片的寿命预测结果与试验寿命对比误差在10%左右。研究成果为优化航空发动机涡轮叶片加工工艺提供了借鉴。
