摘要：At present,the clinical reconstruction of the auricle usually adopts the strategy of taking autologous costal *** method has great trauma to patients,poor plasticity and inaccurate ***-dimensional(3D)printing technology has made a great breakthrough in the clinical application of orthopedic *** study explored the combination of 3D printing and tissue engineering to precisely reconstruct the ***,a polylactic acid(PLA)polymer scaffold with a precisely customized patient appearance was fabricated,and then auricle cartilage fragments were loaded into the 3D-printed porous PLA scaffold to promote auricle *** vitro,gelatin methacrylamide(GelMA)hydrogels loaded with different sizes of rabbit ear cartilage fragments were studied to assess the regenerative activity of various autologous cartilage *** vivo,rat ear cartilage fragments were placed in an accurately designed porous PLA polymer ear scaffold to promote auricle *** results indicated that the chondrocytes in the cartilage fragments could maintain the morphological phenotype in *** three months of implantation observation,it was conducive to promoting the subsequent regeneration of cartilage in *** autologous cartilage fragments combined with 3D printing technology show promising potential in auricle reconstruction.

摘要：基于H桥级联的STATCOM具备易拓展、体积小、可模块化实现等突出优点,现已成为国内外电力领域的热点。本文首先研究并分析了它的拓扑结构、补偿原理及开关状态,并在此基础上分别建立了STATCOM和H桥模块的数学模型。然后,分析STATCOM数学模型,引入线性PI控制器对其解耦,并建立了功率解耦控制策略。另外,根据虚拟磁链理论和功率估算方法,建立了基于虚拟磁链的直接功率控制。最后,利用MATLAB进行仿真,论证了方法的可行性,并得出了基于虚拟磁链的直接功率控制方法具有响应速度快,能够快速跟踪电压矢量角,但电流谐波含量高,PI参数难设计;功率解耦控制策略实现简单,电流谐波含量低等结论。

摘要：气动热风洞实验是地面研究和预测飞行器气动热环境的重要手段之一,但由于风洞实验模拟能力的限制,风洞实验的流场参数和模型的几何尺度都会与实际飞行情况存在一定的差别,导致地面风洞实验中得到的模型表面气动加热率数据无法直接用于飞行条件下的热环境预测和热防护设计.以往通过针对具体飞行器的试验结果进行数据拟合后外插的气动热关联换算方法指向性较强,没有考虑到气动热的具体影响参数,存在一定局限性,难以外推应用于其他外形的飞行器.为解决通过气动热风洞实验数据外推预测飞行条件下气动热的技术难题,基于无量纲NS方程和边界层理论分析研究了影响气动热的主要参数,并通过推导化简边界层近似解热流公式,针对层流流态建立了气动热关联换算方法,可以考虑当地边界层外缘参数的影响,具有一定通用性.在此基础上,利用建立的方法将Reentry-F飞行器缩比模型的风洞实验数据换算到该飞行器飞行条件下的典型工况,并与飞行测量结果进行了比较,外推预测结果与飞行测量结果符合较好,表明建立的关联方法可以用于气动热风洞实验数据的外推换算.

摘要：近年来,高铁发展是否经济的问题受到广泛关注,仅采用费用效益分析的高铁运营效益评价无法全面衡量其产生的广泛影响及效益。基于对中国国家铁路集团有限公司、中国铁路设计集团有限公司等单位的调研,结合文献研究与德尔菲法,界定了高铁广义效益的内涵和机理,从经济、环境、社会三个维度构建了更加符合当前社会经济发展目标的高铁运营效益评价框架。同时,以京沪高铁为例,结合专家赋权法和熵权法进行综合赋权和评价,验证了该框架的有效性和实用性。评价结果表明,京沪高铁具有良好的广义运营效益,并呈逐年上升趋势,但其经济效益、环境效益和社会效益的变化趋势并不相同。

摘要：Given the carbon peak and carbon neutrality era,there is an urgent need to develop high-strength steel with remarkable hydrogen embrittlement *** is crucial in enhancing toughness and ensuring the utilization of hydrogen in emerging iron and steel ***,the pursuit of enhanced metallic materials presents a cross-disciplinary scientific and engineering *** high-strength,toughened steel with both enhanced strength and hydrogen embrittlement(HE)resistance holds significant theoretical and practical *** ensures secure hydrogen utilization and further carbon neutrality objectives within the iron and steel *** on the design principles of high-strength steel HE resistance,this review provides a comprehensive overview of research on designing surface HE resistance and employing nanosized precipitates as intragranular hydrogen *** also proposes feasible recommendations and prospects for designing high-strength steel with enhanced HE resistance.

摘要：半监督多标记学习利用有标记数据和无标记数据进行模型的训练,降低了多标记数据的标记成本并取得了不错的结果,吸引了很多研究者不断进行研究.然而,在半监督标注过程中,由于标记的数量较多,往往会出现某些标记缺失标注样本的情况,这些标记被称为开放词汇.开放词汇会导致模型无法学习到该类别的标记信息,使得模型性能下降. 针对上述问题,提出了基于图提示的半监督开放词汇多标记 学习方法. 具体地,该方法利用基于提示的图神经网络对预训练大模型进行微调,挖掘和探索开放词汇与 监督样本之间的关系. 通过使用包含图像与文本的多模态数据构造图神经网络作为预训练大模型的文本 输入进行学习. 其次利用预训练大模型在开放词汇上的泛化能力,对无监督样本生成伪标记,实现对输出 分类层的微调,使模型在对开放词汇进行分类时能获得更加理想的效果. 多个基准数据集上的实验结果 均显示,基于图提示的半监督开放词汇多标记学习方法优于目前的主流方法,在 VOC,COCO,CUB,NUS 等基准数据集上均取得了最优的效果.

摘要：时变系统受迫振动的响应计算理论仍不完善,数值解法不能准确反映振动响应的解析性。利用Legendre多项式逼近法(Legendre polynomial approximation method, LPAM)可以得到时变系统响应的连续近似函数解,但该方法的计算效率较低。将时不变系统的时域响应求解理论移植到时变系统,基于线性系统的叠加原理提出基于Duhamel积分的改进Legendre级数算法,利用Dirac函数的Legendre多项式近似和Duhamel积分求解时变系统的响应。通过一个一阶非齐次变系数常微分方程组说明改进算法的有效性。设计刚度阻尼均线性变化和非线性变化的单自由度系统仿真算例,对比利用该方法得到的瞬态激励和简谐激励下系统位移响应和四阶Runge-Kutta数值法计算结果,说明了改进算法敛散性问题和计算速度的提升。

摘要：采用计算流体力学软件对进气道喷射汽油机冷起动时前3个循环可燃混合气的形成进行了三维数值计算,采用多组分燃油模型研究了喷油量、喷油时刻、喷油位置、燃油温度以及2次喷射对混合气形成的影响规律。结果表明:随着喷油量的增加,缸内当量比线性上升,但过高油量将抑制燃油蒸发;在闭阀喷射时,过早喷油使得燃油蒸发率下降,进气阀背面喷油位置的燃油蒸发率大于进气道底面;在开阀喷射时,混合气形成不均匀,气阀内侧缸内附壁油膜最少,当量比最大;燃油温度过高可抑制油膜蒸发;2次喷射有益于缸内当量比提高,附壁油膜减少。

摘要：随着我国基础建设的发展,大量混凝土桥梁在恶劣环境影响下发生腐蚀和老化,腐蚀桥梁结构的灾害破坏机理研究对桥梁结构的运营安全具有重要意义。为研究已经锈蚀受损的桥梁在局部受热状态下的高温力学性能,设计10根预应力混凝土梁试件。其中对照组的2根试件在常温下加载,试验变量为预应力筋初始应力,试验组的8根试件在高温下加载,试验变量分别为钢筋锈蚀、预应力筋初始应力、初始荷载。首先,基于电化学原理对4根预应力混凝土梁进行钢筋加速锈蚀处理,然后利用复合高温试验炉对8根预应力混凝土梁(4根锈蚀、4根未锈蚀)在跨中进行三面受火试验。最后,采用数值方法对局部受热预应力混凝土梁进行了仿真分析。研究结果表明:局部受热条件下,预应力混凝土梁的承载能力会发生明显降低,下降幅度约为11.3%~14.9%;钢筋锈蚀导致的混凝土开裂会对预应力混凝土梁的抗火性能产生不利影响,主要表现为2个方面,1)相同试验条件下,锈蚀后的试件预应力增量更大;2)锈蚀试件在局部受热条件下承载能力下降幅度更大,约为19.4%~21.9%;增大预应力筋的初始应力可以减小预应力混凝土梁在局部受热时的高温蠕变变形;局部高温作用下预应力混凝土梁对初始荷载较为敏感,当试件初始荷载值提升20%时,三分点位移量约增大60%。研究成果可以为实际锈蚀桥梁的防火设计和灾后应急提供理论依据。

摘要：Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze CO2 reduction reaction(CO2RR)still cannot meet the requirements of commercial-scale *** developing Snbased catalyst is of vital ***,the sheet-like heterophase Sn O2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process,with Sn3O4 as the dominant *** evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO*formation,accelerate the charge transfer between the catalysts and reactants,and ultimately greatly elevate the intrinsic activity of the heterophase Sn O2/Sn3O4 towards CO2 ***,the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of Sn O2/*** heterophase Sn O2/Sn3O4 displays high activity and selectivity for CO2 RR,achieving an improvement in CO2 reduction current density,88.3%Faradaic efficiency of HCOOH conversion at-0.9 VRHE,along with a long-term tolerance in CO2 *** study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.