By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and...By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.展开更多
目的分析超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞在肥胖孕妇剖宫产中的应用效果。方法将2022年6月至2025年2月期间在保定市妇幼保健院行剖宫产的82例肥胖孕妇使用双盲法设计分组,按随机数字表法分为常规组、联合组,每组各41例。...目的分析超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞在肥胖孕妇剖宫产中的应用效果。方法将2022年6月至2025年2月期间在保定市妇幼保健院行剖宫产的82例肥胖孕妇使用双盲法设计分组,按随机数字表法分为常规组、联合组,每组各41例。常规组接受椎管内麻醉(常规髂嵴最高点连线定位法),联合组采用超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞(剖宫产术后)。比较两组穿刺情况、术后疼痛[视觉模拟评分法(VAS)]评分、术后活动情况、术后恢复质量[40项恢复质量量表(QoR-40)]、术后并发症发生情况。结果联合组的穿刺次数为(1.29±0.57)次,少于常规组[(1.75±0.47)次],穿刺时间为(76.55±9.19)s,短于常规组[(111.04±13.35)s],差异均有统计学意义(P<0.05)。联合组术后2、6、12、24 h VAS评分均显著低于常规组,差异均有统计学意义(P<0.05)。联合组术后泌乳时间、住院时间均显著短于常规组,下床活动持续时间显著长于常规组,差异均有统计学意义(P<0.05)。联合组术后QoR-40评分中情绪状态等各方面评分及总分均显著高于常规组,差异均有统计学意义(P<0.05)。联合组术后并发症发生率为2.44%,显著低于常规组(19.51%),差异有统计学意义(P<0.05)。结论相比常规定位法,超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞在肥胖孕妇剖宫产中的应用效果较好,可有效减少穿刺次数、优化镇痛效果、缩短泌乳时间、增加下床活动时间、加速术后康复并减少术后并发症。展开更多
Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under trans...Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.展开更多
We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pio...We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pion within the frame work of hadronic operator. To achieve this, we consider a slightly deformed curve deviating from a straight line and construct a set of differential equations by comparing them to the equation determining charged pion wave function in a straight line case. By solving these equations, we employ the Fourier transform of these wave functions.展开更多
文摘By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in transverse section, and by appling topology theory, the topological structures and vortex structure in the transverse section of a blade cascade were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex, and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex.
文摘目的分析超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞在肥胖孕妇剖宫产中的应用效果。方法将2022年6月至2025年2月期间在保定市妇幼保健院行剖宫产的82例肥胖孕妇使用双盲法设计分组,按随机数字表法分为常规组、联合组,每组各41例。常规组接受椎管内麻醉(常规髂嵴最高点连线定位法),联合组采用超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞(剖宫产术后)。比较两组穿刺情况、术后疼痛[视觉模拟评分法(VAS)]评分、术后活动情况、术后恢复质量[40项恢复质量量表(QoR-40)]、术后并发症发生情况。结果联合组的穿刺次数为(1.29±0.57)次,少于常规组[(1.75±0.47)次],穿刺时间为(76.55±9.19)s,短于常规组[(111.04±13.35)s],差异均有统计学意义(P<0.05)。联合组术后2、6、12、24 h VAS评分均显著低于常规组,差异均有统计学意义(P<0.05)。联合组术后泌乳时间、住院时间均显著短于常规组,下床活动持续时间显著长于常规组,差异均有统计学意义(P<0.05)。联合组术后QoR-40评分中情绪状态等各方面评分及总分均显著高于常规组,差异均有统计学意义(P<0.05)。联合组术后并发症发生率为2.44%,显著低于常规组(19.51%),差异有统计学意义(P<0.05)。结论相比常规定位法,超声引导定位下椎管内麻醉联合腹横筋膜平面阻滞在肥胖孕妇剖宫产中的应用效果较好,可有效减少穿刺次数、优化镇痛效果、缩短泌乳时间、增加下床活动时间、加速术后康复并减少术后并发症。
文摘Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress due to bending and axial stress arising from constrained warping displacements at the fixing. The net shear stress distribution overlays the distributions from axial torsion and that from flexural shear under transverse loading. Both arise when transverse forces are displaced from the shear centre.
文摘We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pion within the frame work of hadronic operator. To achieve this, we consider a slightly deformed curve deviating from a straight line and construct a set of differential equations by comparing them to the equation determining charged pion wave function in a straight line case. By solving these equations, we employ the Fourier transform of these wave functions.
