摘要：The design and preparation of non-noble metal catalysts with high catalytic activity and robust stability are important in the research of metal-air batteries and fuel ***,a three-dimensional(3D)hierarchically ordered porous carbon nanomaterial was conveniently synthesized with zeolite-imidazole framework(ZIF-8)carbonization using the silica-template method and carbon nanotube(CNT)*** addition of an iron source endows the porous mFeNCCNT with Fe-based nanoparticles and abundant atomically dispersive Fe-Nx sites from its nitrogen-incorporated graphitic carbon *** a result,the 3D porous structure reduces the charge transport resistance,and the iron and nitrogen codoped carbon exhibits excellent catalytic activity for oxygen reduction reaction(ORR)similar to that of commercial Pt/***,the interwoven CNTs obtained under urea catalysis further shorten the ion and electron diffusion *** and theoretical analyses revealed that the optimized mFeNC-CNT has a high ORR activity with a half-wave potential of 0.908 V and a large open-circuit voltage(1.556 V)when applied on zinc-air *** work provides a promising strategy for the rational design and facile synthesis of high-performing non-noble metal-based electrocatalysts for energy storage,conversion,and transport applications.

摘要：Multi-wall carbon nanotube filled shape memory polymer composite(MWCNT/SMC)possessed enhanced modulus,strength,and electric conductivity,as well as excellent electrothermal shape memory properties,showing wide design scenarios and engineering application *** thermoelectrically triggered shape memory process contains complex multi-physical mechanisms,especially when coupled with finite deformation rooted on micro-mechanisms.A multi-physical finite deformation model is necessary to get a deep understanding on the coupled electro-thermomechanical properties of electrothermal shape memory composites(ESMCs),beneficial to its design and wide *** into consideration of micro-physical mechanisms of the MWCNTs interacting with double-chain networks,a finite deformation theoretical model is developed in this work based on two superimposed network chains of physically crosslinked network formed among MWCNTs and the chemically crosslinked *** intact crosslinked chemical network is considered featuring with entropic-hyperelastic properties,superimposed with a physically crosslinked network where percolation theory is based on electric conductivity and electric-heating *** model is calibrated by experiments and used for shape recoveries triggered by heating and electric *** captures the coupled electro-thermomechanical behavior of ESMCs and provides design guidelines for MWCNTs filled shape memory polymers.

摘要：Anterior cruciate ligament(ACL)injuries of the knee are one of the most common and serious athletic *** widely used cortical suspension fixation buttons for ligament reconstruction are permanent implants,particularly those made from conventional steel or titanium *** this study,a biodegradable Zn-0.45Mn-0.2Mg(ZMM42)alloy with the yield strength of 300.4 MPa and tensile strength of 329.8 MPa was prepared through hot *** use of zinc alloys in the preparation of cortical suspension fixation buttons was proposed for the first *** 35 d of immersion in simulated body fluids,the ZMM42 alloy fixation buttons were degraded at a rate of 44μm/a,and the fixation strength was retained(379.55 N)in the traction ***,the ZMM42 alloy fixation buttons exhibited an increase in MC3T3-E1 cell viability and high antibacterial activity against Escherichia coli and Staphylococcus *** results reveal the potential of biodegradable zinc alloys for use as ligament reconstruction materials and for developing diverse zinc alloy cortical suspension fixation devices.

摘要：Two major challenges,high cost and short lifespan,have been hindering the commercialization process of lowtemperature fuel *** Wei's group has been focusing on decreasing cathode Pt loadings without losses of activity and durability,and their research advances in this area over the past three decades are briefly reviewed *** the Pt-based catalysts and the low Pt usage,they have firstly tried to clarify the degradation mechanism of Pt/C catalysts,and then demonstrated that the activity and stability could be improved by three strategies:regulating the nanostructures of the active sites,enhancing the effects of support materials,and optimizing structures of the three-phase *** Pt-free catalysts,especialiy carbon-based ones,several strategies that they proposed to enhance the activity of nitrogen-/heteroatom-doped carbon catalysts are firstly ***,an indepth understanding of the degradation mechanism for carbon-based catalysts is discussed,and followed by the corresponding stability enhancement ***,the carbon-based electrode at the micrometer-scale,faces the challenges such as low active-site density,thick catalytic layer,and the effect of hydrogen peroxide,which require rational structure design for the integral cathodic *** review finally gives a brief conclusion and outlook about the low cost and long lifespan of cathodic oxygen reduction catalysts.

摘要：用于光学、微波通信调谐等器件的向列相液晶材料需要具备高响应速度来实现应用需求.液晶器件响应速度与液晶的旋转黏度、液晶的双折射率等因素相关.微波器件用向列相液晶,常采用大π-电子共轭体系、大极性基团来提高液晶分子的双折射率和介电各向异性,实现宽相位调制量,也因此增大了液晶材料黏度,影响了微波器件的响应速度.本文以液晶黏度因素为主线,对本课题组设计合成的42种向列相液晶在25℃时的黏度用旋转流变仪进行测试,从液晶化合物的结构角度分析影响液晶黏度的因素.首次建立向列相液晶分子结构与黏度的BPNN-QSAR定量构效模型,模型测试组预测值跟真实值之间的相关系数q^(2)=0.607>0.5,说明模型可用于液晶化合物的黏度性能预测,并对影响黏度性能的分子结构描述符进行了探讨.从实际应用出发结合本课题研究,设计了两个系列7个大双折射率液晶分子,BPNN模型测试黏度量度小于同类型分子,实验测试值与模型测试值相近.

摘要：传统状态观测器仅基于当前观测误差重构系统状态,未充分利用系统历史观测数据.针对存在匹配扰动的二阶不确定线性系统,设计一种比例-积分-时滞滑模观测器,实现不确定线性系统状态的鲁棒确切估计.首先,设计带记忆滑模函数,形式为历史观测误差和当前观测误差的线性组合,设计参数包括滑模面增益和人工时滞两部分,将滑模面中的时滞项基于泰勒级数展开,将截断误差表示为积分形式;然后,设计带记忆输出反馈等效控制律,采用时滞依赖型Lyapunov泛函,进行滑模动态指数稳定性分析和观测补偿;接着,将观测器参数设计转化为多目标优化问题,优化目标包括:系统状态衰减率、控制代价、高频噪声不灵敏度,基于粒子群算法,在上述3个优化目标间实现设计参数优化整定,在“快、准、稳”方面进行合理折衷选择;最后,在无源网络系统中,验证所提出滑模观测器的可行性和有效性.

摘要：中国海岸线绵长,海洋资源丰富。厦门作为沿海城市,近年来,港口建设、临海工业、滨海旅游开发等活动的增加导致海岸线出现较大变化。高效、精确地测量海岸线的时空动态变化极具研究价值和实际意义。该文基于2005年、2010年、2015年、2020年4期Landsat遥感影像数据,利用面向对象的方法对海岸线进行提取,然后从海岸线长度、形态和陆地面积变化等方面研究海岸线的时空演变。研究结果表明,15 a间,厦门市海岸线时空变化特征显著。海岸线长度整体持续增长,先加速后减速,2010—2015年间变化最快,平均速率高达4.1 km/a,变化主要集中在大嶝岛和海翔码头附近。海岸线形态逐年趋于平整,湖里区变化最为明显。2005—2020年间,厦门陆地面积增长约24.5 km 2,翔安区陆地面积增长最大。海岸线的变化受到多种因素的影响,其中人口增长、经济发展、政策的出台和改变等都对海岸线的变化产生巨大影响。

摘要：近年来,以ChatGPT为代表的能够适应复杂场景、并能满足人类的各种应用需求为目标的文本生成算法模型成为学术界与产业界共同关注的焦点.然而,ChatGPT等大规模语言模型(Large Language Model,LLM)高度忠实于用户意图的优势隐含了部分的事实性错误,而且也需要依靠提示内容来控制细致的生成质量和领域适应性,因此,研究以内在质量约束为核心的文本生成方法仍具有重要意义.本文在近年来关键的内容生成模型和技术对比研究的基础上,定义了基于内在质量约束的文本生成的基本形式,以及基于“信、达、雅”的6种质量特征;针对这6种质量特征,分析并总结了生成器模型的设计和相关算法;同时,围绕不同的内在质量特征总结了多种自动评价和人工评价指标与方法.最后,本文对文本内在质量约束技术的未来研究方向进行了展望.

摘要：为了提高四轮独立驱动电动汽车(FWID EV)轨迹跟踪控制性能,针对车辆横向运动系统的不确定性与非线性问题,考虑转向执行机构的动态特性,提出了基于线性变参数(LPV)的鲁棒加权增益调度轨迹跟踪控制策略。首先利用凸分解技术将LPV系统转化为有限多胞顶点凸组合的多胞体系统,然后基于离线设计的每个多胞顶点控制器和线性组合在线计算任意时变参数对应的系统控制器参数,并利用MATLAB和CarSim进行联合仿真。结果表明:在加速变道场景下,所设计的控制器可以保证横向偏移误差不超过2 cm,横向偏移平均绝对误差不超过0.9 cm的较高跟踪精度及行驶稳定性和鲁棒性。

摘要：吸附强化水气变换反应(SEWGS)是实现高纯氢制备及二氧化碳(CO_(2))减排的关键反应之一。SEWGS借助复合催化剂将水气变换反应(制氢)和原位移除CO_(2)反应(脱碳)耦合,打破热力学限制使反应平衡向制氢侧移动。SEWGS具有一步制取高纯氢气的特点,但复合催化剂在连续操作过程中由于烧结和CO_(2)扩散受阻存在循环稳定性下降的问题,进而影响制氢效率。本文阐述了高温Ni/CaO基复合催化剂吸附强化制氢的研究现状,简述了Fe/CaO基复合催化剂SEWGS制氢面临的主要问题,回顾了中温Cu/MgO基和Cu/类水滑石基复合催化剂的SEWGS制氢现状及现阶段的核心问题。从复合催化剂的催化组分和吸附组分角度,分析了SEWGS制氢过程中复合催化剂循环稳定性降低的原因,简述了现阶段最有效的改性手段。进一步从增强CO_(2)扩散和改善烧结角度入手,围绕复合催化剂设计、操作条件和床层装填方式等方面探讨提高复合催化剂循环稳定性的策略。指出设计开发组成简单、易制备、兼具高活性和高稳定性的复合催化剂实现制氢和脱碳耦合是今后SEWGS制氢的研究方向。