摘要：Electrocatalytic ammonia synthesis under mild conditions is an attractive and challenging process in the earth’s nitrogen cycle,which requires efficient and stable catalysts to reduce the *** N2 activation and reduction overpotential of different Ti3C2O2-supported transition metal(TM)(Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn,Mo,Ru,Rh,Pd,Ag,Cd,and Au)single-atom catalysts have been analyzed in terms of the Gibbs free energies calculated using the density functional theory(DFT).The end-on N2 adsorption was more energetically favorable,and the negative free energies represented good N2 activation performance,especially in the presence Fe/Ti3C2O2(﹣0.75 eV).The overpotentials of Fe/Ti3C2O2,Co/Ti3C2O2,Ru/Ti3C2O2,and Rh/Ti3C2O2 were 0.92,0.89,1.16,and 0.84 eV,*** potential required for ammonia synthesis was different for different TMs and ranged from 0.68 to 2.33 *** possible potential-limiting steps may be involved in the process:(i)hydrogenation of N2 to*NNH and(ii)hydrogenation of*NH2 to *** catalysts can change the reaction pathway and avoid the traditional N–N bond-breaking *** also simplifies the understanding of the relationship between the Gibbs free energy and overpotential,which is a significant factor in the rational designing and large-scale screening of catalysts for the electrocatalytic ammonia synthesis.

摘要：布线是芯片设计自动化流程中至关重要且特别耗时的一环,直接影响最终产品的面积、成本、功耗、速度和可靠性,研究智能布线算法对提高芯片布线效率和优化芯片布线效果具有重要意义.芯片布线问题是一个多目标、多约束的NP困难问题.即使已有几十年的研究历史,目前仍存在大量未突破的问题和空间.随着制造工艺的不断发展,布线规则、约束和目标也持续调整和增加,使得布线选择极其困难.因此,对芯片设计自动化中自动布线的前沿研究进行了全面归纳与分析,以帮助科研人员全面了解该领域的研究进展和方向,助力智能布线算法的研究和发展.具体而言,首先阐述芯片布线的问题背景,然后分别介绍全局布线(Global routing,GR)和详细布线(Detailed routing,DR)的任务定义和目标、过程特点、难点和挑战、评估方法;接着详述和分析各布线方法,重点论述基于规划搜索的布线方法和基于机器学习的布线方法的最新研究成果、优缺点及其应用环节;然后介绍公开数据集和开源布线工具;最后总结现有方法在实际应用中存在的局限性,并对自动布线未来的发展趋势和潜在研究方向进行展望.

摘要：针对游梁式抽油机检修时因系统机械故障或工人未锁死刹车系统而导致生产事故意外发生的隐患,结合现场需求,设计一种啮合式刹车驻车装置,对其实现方案、结构等进行分析,并结合有限元软件对齿块、齿盘、转臂等关键部件进行强度校核;根据其工作原理,对齿块与齿盘的啮入啮出条件进行校核,为后续推广应用提供理论依据。该刹车驻车装置作为抽油机正常刹车装置有益补充,为抽油机检维修等作业提供双保险,为抽油机检维修时溜车隐患的解决提供一种可行的解决方案。

摘要：The nitrogen reduction reaction(NRR)using new and efficient electrocatalysts is a promising al‐ternative to the traditional Haber‐Bosch ***,it remains a challenge to design efficient catalysts with improved catalytic ***,various O‐functional MXenes were investigated as NRR catalysts by a combination of density functional theory calculations and least absolute shrinkage and selection operator(LASSO)***_(3)C_(2)O_(X) has been regarded as a promising catalyst for the NRR because of its stability,activity,and *** poten‐tial‐determining step is*NH_(2) hydrogenation to*NH3 with a limiting potential of-0.45 ***‐more,via LASSO regression,the descriptors and equations fitting the relationship between the properties of O‐functional MXenes and NRR activity have been *** work not only pro‐vides a rational design strategy for catalysts but also provides machine learning data for further investigation.

摘要：采用自行设计的绝缘夹具对TC4钛合金板材进行了电致塑性单向拉伸试验。基于对照试验的方法,以无脉冲电流且不同温度条件作为参照,与同等温度条件下脉冲电流加热情况进行对比,以探索电流参数对TC4钛合金电致塑性效应和力学性能的影响规律。结果表明:在试验研究范围内,脉冲电流的占空比主要影响材料的温度变化,脉冲电流密度对TC4钛合金的电致塑性起主导地位,脉冲电流作用下的TC4钛合金材料抗拉强度大幅下降,塑性提高。基于Johnson-Cook模型和Arrhenius方程建立了耦合温度和脉冲电流密度的TC4钛合金电致塑性本构方程,并进行了验证。

摘要：为了适应长江、黄河流域棉区的棉花机械化采收需求,设计了一款采棉机三角履带行走装置。分析棉田工况、整车接地比压和车速等参数,确定了三角履带行走装置的主要技术参数;通过有限元分析,对基架、驱动轮和摆动销轴等关键部件进行了强度校核计算。结果表明:所设计结构与材料选用均能满足使用要求,单轮承载最高可达8 t。该装置可与原车轮胎快速互换,对于推进长江、黄河流域棉花收获机械化具有一定意义。

摘要：目的制备唑来膦酸(ZOL)修饰的聚多巴胺(PDA)包覆介孔二氧化硅(MSN)纳米颗粒,对其进行表征及释药性能研究。方法将ZOL与氨基-聚乙二醇-巯基连接作为骨靶向配体,通过加成反应修饰在PDA包覆的MSN表面,得到药物载体MSN@PDA-PEG-ZOL,通过1H-NMR、FT-IR、TEM、粒径及Zeta电位等方法对其进行表征。以自噬抑制剂3-甲基腺嘌呤(3-MA)为药物模型,设计不同药物浓度计算载药量及包封率,筛选最佳处方,并考察药物在不同环境下的释放量。结果制备得到的纳米颗粒为分散均匀的球形结构;粒径及Zeta电位分别为(229.1±8.8)nm、-(30.3±0.6)mV;载药浓度在1000μg·mL^(-1)时,其包封率为(90.87±0.05)%,载药量为(37.55±0.02)%。纳米颗粒在pH 7.4的PBS溶液中48 h内的药物释放率为(16.99±0.15)%,在pH 5.0的PBS溶液中的释放率为(65.11±1.64)%,有利于药物在肿瘤微环境中的释放。结论本文成功制备了负载3-MA且具有靶向性和pH响应性的纳米制剂,其分散性好,具有高载药量、高包封率等特点,可为后续研究奠定基础。

摘要：A mesoporous silica/gold （MSN/Au） nanocomposite was designed for photo- controlled drug delivery targeted specifically at tumor cells. The MSN/Au nanocomposite was composed of MSN-based drug carriers and gold nanoparticle （AuNP）-based indicators. While the MSN-based drug carrier was a mesoporous silica nanoparticle immobilized with photo-switchable azobenzene （Azo） moieties, the AuNP-based indicator was a fluorescence-quenched AuNP modified with a matrix metalloproteinase （MMP） substrate and poly（ethylene glycol）. The two kinds of nanoparticles were connected by an α,β cyclodextrin （α,β CD） dimer ＂bridge.＂ In vitro studies demonstrated that the nanocomposite specifically interacted with tumor sites overexpressing MMP-2, which enabled guidance of the subsequent UV light irradiation for releasing entrapped drugs. Through integration of the AuNP-based indicator and the MSN-based drug carrier, the MSN/Au nanocomposite could precisely localize the released drug to tumor sites, thereby significantly improving therapeutic efficacy.

摘要：总结了被动步行的特点和研究现状,介绍了几款国外主要的被动步行机器人的机构设计和驱动系统设计,对被动步行研究中的稳定性问题、能量优化问题以及控制和学习方法进行了综述,并指出了被动步行领域的研究难点和未来研究方向.

摘要：为进一步降低飞机螺旋桨气动噪声,针对飞机螺旋桨开展综合考虑气动、噪声和结构强度的低噪声多学科优化设计与试验验证。采用基于涡格法的升力面理论进行螺旋桨气动性能计算,基于hanson频域远场噪声计算方法进行螺旋桨远场噪声评估,2种计算方法都通过与试验对比验证精度,由此组成螺旋桨气动-噪声联合算法;以桨叶沿叶高分布的弦长、安装角和侧掠为设计变量,充分考虑桨叶结构强度对设计变量的约束,以螺旋桨推力、效率不降低和远场噪声降噪最大为优化目标;优化桨叶通过了离心载荷试验、气动载荷试验、动态特性试验等强度试验;在气动声学风洞内完成了气动与声学性能验证,优化螺旋桨相比原始桨气动性能基本保持不变,优化螺旋桨在设计工况的1阶离散分量处的远场气动噪声峰值降低2.7dB,较小推力下降噪量最高可达4dB,2阶离散分量处也有明显的降噪效果。提出的方法同时满足气动、噪声和结构强度要求。