We synthesized photo-responsive carboxymethyl chitosan(CMC-MA)via free radical polymerization and utilized nanoclay laponite(LAP)as an inorganic crosslinking agent to develop an injectable and 3D-printable CMC-MA/LAP ...We synthesized photo-responsive carboxymethyl chitosan(CMC-MA)via free radical polymerization and utilized nanoclay laponite(LAP)as an inorganic crosslinking agent to develop an injectable and 3D-printable CMC-MA/LAP hydrogel.We determined the optimal ratio of 2.5 w/v%CMC-MA/7.5 w/v%LAP based on injection molding,compression modulus,swelling properties,rheological properties,and 3D printing properties of the hydrogel system.In-vitro cytocompatibility experiments showed that both CMC-MA and CMC-MA/LAP hydrogel had no inhibitory effect on cell proliferation and can promote cell growth when cultured on the surface of the hydrogel matrix.Moreover,the hydrogel containing LAP particles significantly facilitated cell adhesion(>60%)compared with the hydrogel without LAP(20%).Our findings demonstrate that the CMC-MA/LAP hydrogel has great potential for tissue repair in neural tissue engineering.展开更多
During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties durin...During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties during friction stir lap welding(FSLW).This study focuses on investigating the effects of rotation rate,multipass welding,and cooling methods on lap defect formation,microstructural evolution,and mechanical properties.Hook defects were eliminated by decreasing welding speed,applying two-pass FLSW with a small welding tool,and introducing additional water cooling,thus leading to a remarkable increase in effective sheet thickness and lap width.This above strategy yielded defect-free joints with an ultrafine-grained microstructure and increased tensile shear force from 298 to 551 N/mm.The fracture behavior of FSLW joints was systematically studied,and a fracture factor of lap joints was proposed to predict their fracture mode.By reducing the rotation rate,using two-pass welding,and employing additional water cooling strategies,an enlarged,strengthened,and defect-free lap zone with refined ultrafine grains was achieved with a quality comparable to that of lap welds based on 7xxx Al alloys.Importantly,this study provides a valuable FSLW method for eliminating hook defects and improving joint performance.展开更多
Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost importance.However,the application of non-penetration welded aust...Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost importance.However,the application of non-penetration welded austenitic stainless steel parts is limited owing to the micro bulging distortion that occurs on the back surface of the partial penetration side.In this paper,non-penetration lap laser welding experiments,were conducted on galvanized and SUS304 austenitic stainless steel plates using a fiber laser,to investigate the mechanism of bulging distortion.A comparative experiment of DC01 galvanized steel-Q235 carbon steel lap laser welding was carried out,and the deflection and distortion profile of partially penetrated side of the sheets were measured using a noncontact laser interferometer.In addition,the cold-rolled SUS304 was subjected to heat holding at different temperatures and water quenching after bending to characterize its microstructure under tensile and compressive stress.The results show that,during the heating stage of the thermal cycle of laser lap welding,the partial penetration side of the SUS304 steel sheet generates compressive stress,which extrudes the material in the heat-affected zone to the outside of the back of the SUS304 steel sheet,thereby forming a bulge.The findings of these experiments can be of great value for controlling the distortion of the partial penetrated side of austenitic stainless steel sheet during laser non-penetration lap welding.展开更多
太阳能光伏发电已成为仅次于水电和风能的第三大可再生能源,光伏发电受云量时空变化的影响较大,因此准确模拟云天太阳辐射的时空变化对电网安全运行至关重要。围绕如何减小中尺度气象模式的云初始场误差,进而改进云天的太阳辐射模拟这...太阳能光伏发电已成为仅次于水电和风能的第三大可再生能源,光伏发电受云量时空变化的影响较大,因此准确模拟云天太阳辐射的时空变化对电网安全运行至关重要。围绕如何减小中尺度气象模式的云初始场误差,进而改进云天的太阳辐射模拟这一关键科学问题,本文通过研究基于卫星资料同化的LAPS(Local Analysis Prediction System)多时间层三维云分析同化方法,改进三维云结构,并将LAPS模式输出结果作为WRF(Weather Research and Forecasting)模式的初始场,模拟了2008年1月及夏季(6~8月)北京地区的总云量和总辐射的时空分布,重点分析了多云和有降水天气过程总辐射的模拟改进效果及其原因。结果表明,同化前后的总云量模拟值与观测值的时间变化趋势基本一致,但大部分时次总云量的模拟值低于观测值;大部分多云及降水时段同化后总云量模拟值较接近于实测值。1月晴天、多云天以及夏季晴天同化前后总辐射模拟值与实测值的时间变化趋势较一致,但同化前后两者的相关性差异不明显;晴天条件下同化前后总辐射模拟值均低于实测值,1月多云条件下多数时段同化后总辐射模拟误差减小不明显,与总云量的改进效果不显著有关。夏季多云、有降水及6月典型降水三种天气条件下同化前后总辐射模拟值与观测值的相关性稍差,同化后两者的相关性较同化前有所改进,尤其是6月典型降水过程改进效果较明显;同化前总辐射模拟误差较大,而同化后误差显著减小,尤其是6月典型降水过程同化后均方根误差和平均相对误差较同化前分别减小了102.6 W m^(-2)和355.9%,最大相对误差减小更显著;同化后总辐射模拟误差小于同化前的比例高达75%,即大部分时刻同化后模拟误差小于同化前。多云和有降水天气过程总辐射模拟效果的显著改进与总云量的改进密切相关,即同化后总云量模拟值增加,云的反射和散射作用增强,导致模拟总辐射减小,即更接近于实测总辐射值。研究结果对于多云和降水天气条件下太阳辐射的模拟效果改进、太阳能资源客观评估以及光伏电站的发电量预测具有一定的科学和实际应用价值。展开更多
利用LAPS(Local Analysis and Prediction System)系统同化GPS(Global Positioning System)/PWV(Precipitable Water Vapor)资料,分析GPS/PWV资料对LAPS输出场的影响,并结合WRF模式,将LAPS输出场作为其初始场进行降水预报,进一步考察GPS...利用LAPS(Local Analysis and Prediction System)系统同化GPS(Global Positioning System)/PWV(Precipitable Water Vapor)资料,分析GPS/PWV资料对LAPS输出场的影响,并结合WRF模式,将LAPS输出场作为其初始场进行降水预报,进一步考察GPS/PWV资料对降水预报的作用。选取2009年6月28日湖北地区的一次强降水过程,设计三种方案进行试验。结果表明:同化GPS/PWV资料后对LAPS湿度场有显著的改善,而对高度场及风场的作用则不明显;GPS/PWV资料对区域平均可降水量的影响比雷达资料大一个量级;与此同时,利用多种评分方法对6 h累计降水做了检验,分析结果表明同化GPS/PWV资料能够有效地改进WRF模式的初始场,增加丰富的中小尺度信息,并对随后的确定性预报产生正影响。展开更多
介绍了武汉暴雨研究所引进的LAPS系统(Local Analysis and Prediction System)在水汽分析中应用GPS水汽资料的方法。设计三种试验方案与实况进行对比分析,并结合WRF模式模拟,研究GPS水汽资料在LAPS系统中的作用以及对预报的影响。结果表...介绍了武汉暴雨研究所引进的LAPS系统(Local Analysis and Prediction System)在水汽分析中应用GPS水汽资料的方法。设计三种试验方案与实况进行对比分析,并结合WRF模式模拟,研究GPS水汽资料在LAPS系统中的作用以及对预报的影响。结果表明,LAPS同化GPS水汽资料后,对湿度场产生较大调整;对比各方案LAPS输出的可降水量后发现,GPS水汽资料的作用比雷达资料大一个量级;从模式模拟试验结果比较看出,LAPS对GPS水汽的同化能改善GPS测站分布区域降水预报,并对下游暴雨的预报也有正效果,能提高暴雨量级的Ts降水评分。展开更多
随着探测手段的发展,越来越多的探测资料可以提供给数值天气预报。为了更有效地将这些不同格式的探测资料融合同化为常规物理量,为预报员提供更加直观的中尺度分析场以及为数值模式提供包含丰富中尺度信息的初始场,引进美国的局地分析...随着探测手段的发展,越来越多的探测资料可以提供给数值天气预报。为了更有效地将这些不同格式的探测资料融合同化为常规物理量,为预报员提供更加直观的中尺度分析场以及为数值模式提供包含丰富中尺度信息的初始场,引进美国的局地分析预报系统LAPS(Local Analysis and Prediction System)。介绍了该系统处理资料的原理、方法。初步试验结果表明,对LAPS系统的局地化比较成功,可以融合T213或NCEP、多普勒雷达、云导风、探空及自动站等多种资料,为预报员提供更好的预报依据。展开更多
利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,...利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,地面有分散辐合形成并逐渐加强,成为触发中尺度垂直环流的主要机制,垂直结构上出现低层辐合高层辐散的有利配置,风暴中心附近出现明显的上升气流区,中高层相对湿度显著增加。成熟阶段,强对流云体中心附近的对流层底层开始出现下沉气流,上升气流在其拖曳作用下明显倾斜。衰减阶段,下沉气流加强使中尺度环流动力结构和水汽供应受到破坏,垂直结构上转为底层辐散高层辐合。因此,与天气尺度分析相比,基于LAPS的中尺度分析能更深刻地揭示中小尺度系统的三维结构和时空演变特征。展开更多
基金Funded by the Natural Science Foundation of Hubei Province(No.2022CFB386)。
文摘We synthesized photo-responsive carboxymethyl chitosan(CMC-MA)via free radical polymerization and utilized nanoclay laponite(LAP)as an inorganic crosslinking agent to develop an injectable and 3D-printable CMC-MA/LAP hydrogel.We determined the optimal ratio of 2.5 w/v%CMC-MA/7.5 w/v%LAP based on injection molding,compression modulus,swelling properties,rheological properties,and 3D printing properties of the hydrogel system.In-vitro cytocompatibility experiments showed that both CMC-MA and CMC-MA/LAP hydrogel had no inhibitory effect on cell proliferation and can promote cell growth when cultured on the surface of the hydrogel matrix.Moreover,the hydrogel containing LAP particles significantly facilitated cell adhesion(>60%)compared with the hydrogel without LAP(20%).Our findings demonstrate that the CMC-MA/LAP hydrogel has great potential for tissue repair in neural tissue engineering.
基金supported by the National Natural Science Foundation of China(Nos.52305436 and 51975553)the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A151511006)+4 种基金Guangxi Science and Technology Major Program,China(No.AA23023029)Liaoning Natural Science Foundation of China(No.2021-MS-007)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y2021061)the Bintech-IMR R&D Program(No.GYYJSBU-2022-002)the Institute of Metal Research Innovation Found,China(No.2022-PY11).
文摘During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties during friction stir lap welding(FSLW).This study focuses on investigating the effects of rotation rate,multipass welding,and cooling methods on lap defect formation,microstructural evolution,and mechanical properties.Hook defects were eliminated by decreasing welding speed,applying two-pass FLSW with a small welding tool,and introducing additional water cooling,thus leading to a remarkable increase in effective sheet thickness and lap width.This above strategy yielded defect-free joints with an ultrafine-grained microstructure and increased tensile shear force from 298 to 551 N/mm.The fracture behavior of FSLW joints was systematically studied,and a fracture factor of lap joints was proposed to predict their fracture mode.By reducing the rotation rate,using two-pass welding,and employing additional water cooling strategies,an enlarged,strengthened,and defect-free lap zone with refined ultrafine grains was achieved with a quality comparable to that of lap welds based on 7xxx Al alloys.Importantly,this study provides a valuable FSLW method for eliminating hook defects and improving joint performance.
文摘Non-penetration laser welding of lap joints in austenitic stainless steel sheets is commonly preferred in fields where the surface quality is of utmost importance.However,the application of non-penetration welded austenitic stainless steel parts is limited owing to the micro bulging distortion that occurs on the back surface of the partial penetration side.In this paper,non-penetration lap laser welding experiments,were conducted on galvanized and SUS304 austenitic stainless steel plates using a fiber laser,to investigate the mechanism of bulging distortion.A comparative experiment of DC01 galvanized steel-Q235 carbon steel lap laser welding was carried out,and the deflection and distortion profile of partially penetrated side of the sheets were measured using a noncontact laser interferometer.In addition,the cold-rolled SUS304 was subjected to heat holding at different temperatures and water quenching after bending to characterize its microstructure under tensile and compressive stress.The results show that,during the heating stage of the thermal cycle of laser lap welding,the partial penetration side of the SUS304 steel sheet generates compressive stress,which extrudes the material in the heat-affected zone to the outside of the back of the SUS304 steel sheet,thereby forming a bulge.The findings of these experiments can be of great value for controlling the distortion of the partial penetrated side of austenitic stainless steel sheet during laser non-penetration lap welding.
文摘太阳能光伏发电已成为仅次于水电和风能的第三大可再生能源,光伏发电受云量时空变化的影响较大,因此准确模拟云天太阳辐射的时空变化对电网安全运行至关重要。围绕如何减小中尺度气象模式的云初始场误差,进而改进云天的太阳辐射模拟这一关键科学问题,本文通过研究基于卫星资料同化的LAPS(Local Analysis Prediction System)多时间层三维云分析同化方法,改进三维云结构,并将LAPS模式输出结果作为WRF(Weather Research and Forecasting)模式的初始场,模拟了2008年1月及夏季(6~8月)北京地区的总云量和总辐射的时空分布,重点分析了多云和有降水天气过程总辐射的模拟改进效果及其原因。结果表明,同化前后的总云量模拟值与观测值的时间变化趋势基本一致,但大部分时次总云量的模拟值低于观测值;大部分多云及降水时段同化后总云量模拟值较接近于实测值。1月晴天、多云天以及夏季晴天同化前后总辐射模拟值与实测值的时间变化趋势较一致,但同化前后两者的相关性差异不明显;晴天条件下同化前后总辐射模拟值均低于实测值,1月多云条件下多数时段同化后总辐射模拟误差减小不明显,与总云量的改进效果不显著有关。夏季多云、有降水及6月典型降水三种天气条件下同化前后总辐射模拟值与观测值的相关性稍差,同化后两者的相关性较同化前有所改进,尤其是6月典型降水过程改进效果较明显;同化前总辐射模拟误差较大,而同化后误差显著减小,尤其是6月典型降水过程同化后均方根误差和平均相对误差较同化前分别减小了102.6 W m^(-2)和355.9%,最大相对误差减小更显著;同化后总辐射模拟误差小于同化前的比例高达75%,即大部分时刻同化后模拟误差小于同化前。多云和有降水天气过程总辐射模拟效果的显著改进与总云量的改进密切相关,即同化后总云量模拟值增加,云的反射和散射作用增强,导致模拟总辐射减小,即更接近于实测总辐射值。研究结果对于多云和降水天气条件下太阳辐射的模拟效果改进、太阳能资源客观评估以及光伏电站的发电量预测具有一定的科学和实际应用价值。
文摘利用LAPS(Local Analysis and Prediction System)系统同化GPS(Global Positioning System)/PWV(Precipitable Water Vapor)资料,分析GPS/PWV资料对LAPS输出场的影响,并结合WRF模式,将LAPS输出场作为其初始场进行降水预报,进一步考察GPS/PWV资料对降水预报的作用。选取2009年6月28日湖北地区的一次强降水过程,设计三种方案进行试验。结果表明:同化GPS/PWV资料后对LAPS湿度场有显著的改善,而对高度场及风场的作用则不明显;GPS/PWV资料对区域平均可降水量的影响比雷达资料大一个量级;与此同时,利用多种评分方法对6 h累计降水做了检验,分析结果表明同化GPS/PWV资料能够有效地改进WRF模式的初始场,增加丰富的中小尺度信息,并对随后的确定性预报产生正影响。
文摘介绍了武汉暴雨研究所引进的LAPS系统(Local Analysis and Prediction System)在水汽分析中应用GPS水汽资料的方法。设计三种试验方案与实况进行对比分析,并结合WRF模式模拟,研究GPS水汽资料在LAPS系统中的作用以及对预报的影响。结果表明,LAPS同化GPS水汽资料后,对湿度场产生较大调整;对比各方案LAPS输出的可降水量后发现,GPS水汽资料的作用比雷达资料大一个量级;从模式模拟试验结果比较看出,LAPS对GPS水汽的同化能改善GPS测站分布区域降水预报,并对下游暴雨的预报也有正效果,能提高暴雨量级的Ts降水评分。
文摘随着探测手段的发展,越来越多的探测资料可以提供给数值天气预报。为了更有效地将这些不同格式的探测资料融合同化为常规物理量,为预报员提供更加直观的中尺度分析场以及为数值模式提供包含丰富中尺度信息的初始场,引进美国的局地分析预报系统LAPS(Local Analysis and Prediction System)。介绍了该系统处理资料的原理、方法。初步试验结果表明,对LAPS系统的局地化比较成功,可以融合T213或NCEP、多普勒雷达、云导风、探空及自动站等多种资料,为预报员提供更好的预报依据。
文摘利用LAPS(local analysis and prediction system)同化系统融合多种观测资料,对2010年8月25日发生在上海的一次强对流天气过程进行中尺度分析。结果表明,这次强对流天气主要是由中、低空中尺度辐合系统直接触发形成的。强对流形成阶段,地面有分散辐合形成并逐渐加强,成为触发中尺度垂直环流的主要机制,垂直结构上出现低层辐合高层辐散的有利配置,风暴中心附近出现明显的上升气流区,中高层相对湿度显著增加。成熟阶段,强对流云体中心附近的对流层底层开始出现下沉气流,上升气流在其拖曳作用下明显倾斜。衰减阶段,下沉气流加强使中尺度环流动力结构和水汽供应受到破坏,垂直结构上转为底层辐散高层辐合。因此,与天气尺度分析相比,基于LAPS的中尺度分析能更深刻地揭示中小尺度系统的三维结构和时空演变特征。
