To improve heat-transfer performance, a novel integral three-dimensional fin-structure on the plat surface was presented to increase the evaporation efficiency. The three-dimensional fin-structure is composed of a spi...To improve heat-transfer performance, a novel integral three-dimensional fin-structure on the plat surface was presented to increase the evaporation efficiency. The three-dimensional fin-structure is composed of a spiral micro-groove and multi radial micro-grooves. Both ploughing-extrusion(P-E) and stamping were used to form the integral-fins with a connection between radial and circumferential directions. Based on the SEM results, the relationships among P-E speed v P-E, rotational speed np and feed fp, and among interference length Li, stamping feed angle θc and stamping depth ac were analyzed. The effects of processing parameters on the groove morphology and the matching relationship between parameters were also discussed. The integral finned surface with micro-grooves and cracks can be obtained under such processing conditions: P-E depth ap=0.3 mm, ac=0.3 mm, the interval of helical groove dp=1.24 mm, θc=2° and np=50 r/min.展开更多
为解决耕整播一体机作业过程中面临的土壤回填和碎土效果不佳,以及耕作阻力较大等问题,该研究基于鲨鱼背鳍的轮廓曲线设计了一种仿生直刃旋耕刀。通过高斯方程对背鳍轮廓进行拟合,结果显示拟合决定系数R2接近1且残差平方和SSE(sum of sq...为解决耕整播一体机作业过程中面临的土壤回填和碎土效果不佳,以及耕作阻力较大等问题,该研究基于鲨鱼背鳍的轮廓曲线设计了一种仿生直刃旋耕刀。通过高斯方程对背鳍轮廓进行拟合,结果显示拟合决定系数R2接近1且残差平方和SSE(sum of squares of the residuals)值接近0,验证了所用函数方程的优越性及数据预测的准确性。借助离散元仿真软件,以刀辊回转速度n、机具前进速度v和耕作深度h为因素,以回填率Pr、碎土率I和耕作阻力F为指标,进行二次正交旋转组合仿真试验。结果显示,当刀辊回转速度为241 r/min,机具前进速度为0.65 m/s,耕作深度为120 mm时,仿生旋耕刀-土壤颗粒接触模型具有最优解。室内土槽试验进一步验证,仿生旋耕刀回填率为84.34%,碎土率为79.7%,平均耕作阻力为87.25N,在同等运动参数条件下相较于直刃刀、弯形刀和凿形刀,回填率分别提升了11.98%、36.62%、23.2%;碎土率分别提升了15.07%、6.89%、10.32%;耕作阻力分别降低了15.59%、28.83%、24.38%,并且各指标与仿真结果的相对误差分别为3.7%、3.2%和4.5%,仿真试验和室内土槽试验结果表明仿生旋耕刀在减少耕作阻力的同时,可提高带状旋耕作业的回填率和碎土率,验证了设计的正确性。研究结果可为带状旋耕装置的研发与优化提供支撑。展开更多
目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man...目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man 5.2软件进行Meta分析。结果:共纳入5个随机对照试验,包括294例患者。结果显示,丹蛭降糖胶囊能降低2型糖尿病患者FINS[MD=1.24,95%CI(0.90,1.59),P<0.01],降低IRI[MD=0.20,95%CI(0.14,0.27),P<0.01]。结论:丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用是有效的。展开更多
基金Projects(51205072,51275099)supported by the National Natural Science Foundation of ChinaProjects(S2013010013469,S2011040004110)supported by the Natural Science Foundation of Guangdong Province,China+1 种基金Projects(Yq2013127,2013KJCX0143)supported by Research Program of Guangdong Province UniversityProject(2012A083)supported by Guangzhou Prefecture University Research Program,China
文摘To improve heat-transfer performance, a novel integral three-dimensional fin-structure on the plat surface was presented to increase the evaporation efficiency. The three-dimensional fin-structure is composed of a spiral micro-groove and multi radial micro-grooves. Both ploughing-extrusion(P-E) and stamping were used to form the integral-fins with a connection between radial and circumferential directions. Based on the SEM results, the relationships among P-E speed v P-E, rotational speed np and feed fp, and among interference length Li, stamping feed angle θc and stamping depth ac were analyzed. The effects of processing parameters on the groove morphology and the matching relationship between parameters were also discussed. The integral finned surface with micro-grooves and cracks can be obtained under such processing conditions: P-E depth ap=0.3 mm, ac=0.3 mm, the interval of helical groove dp=1.24 mm, θc=2° and np=50 r/min.
文摘为解决耕整播一体机作业过程中面临的土壤回填和碎土效果不佳,以及耕作阻力较大等问题,该研究基于鲨鱼背鳍的轮廓曲线设计了一种仿生直刃旋耕刀。通过高斯方程对背鳍轮廓进行拟合,结果显示拟合决定系数R2接近1且残差平方和SSE(sum of squares of the residuals)值接近0,验证了所用函数方程的优越性及数据预测的准确性。借助离散元仿真软件,以刀辊回转速度n、机具前进速度v和耕作深度h为因素,以回填率Pr、碎土率I和耕作阻力F为指标,进行二次正交旋转组合仿真试验。结果显示,当刀辊回转速度为241 r/min,机具前进速度为0.65 m/s,耕作深度为120 mm时,仿生旋耕刀-土壤颗粒接触模型具有最优解。室内土槽试验进一步验证,仿生旋耕刀回填率为84.34%,碎土率为79.7%,平均耕作阻力为87.25N,在同等运动参数条件下相较于直刃刀、弯形刀和凿形刀,回填率分别提升了11.98%、36.62%、23.2%;碎土率分别提升了15.07%、6.89%、10.32%;耕作阻力分别降低了15.59%、28.83%、24.38%,并且各指标与仿真结果的相对误差分别为3.7%、3.2%和4.5%,仿真试验和室内土槽试验结果表明仿生旋耕刀在减少耕作阻力的同时,可提高带状旋耕作业的回填率和碎土率,验证了设计的正确性。研究结果可为带状旋耕装置的研发与优化提供支撑。
文摘目的:评价丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用的有效性。方法:计算机检索中国生物医学文献数据库、中国期刊全文数据库、万方期刊数据库等相关资料,按照Cochrane系统评价的方法,客观评价纳入研究的质量,提取有效数据,采用Rev Man 5.2软件进行Meta分析。结果:共纳入5个随机对照试验,包括294例患者。结果显示,丹蛭降糖胶囊能降低2型糖尿病患者FINS[MD=1.24,95%CI(0.90,1.59),P<0.01],降低IRI[MD=0.20,95%CI(0.14,0.27),P<0.01]。结论:丹蛭降糖胶囊对2型糖尿病患者FINS和IRI作用是有效的。
