摘要：Component sequence preservation is an intrinsic requirement in typical engineering applications, such as deployable chain-likestructures, 3D printing structures with contour-parallel toolpaths, additive manufacturing of continuous fibre-reinforcedpolymer structures, customized stents, and soft robotics parts. This study presents a feature-driven method that preservescomponent sequences accounting for engineering requirements. The chain-of-bars design variables setting scheme is developedto realize the sequential component’s layout, which sets the current bar’s end point as the next bar’s start point. The total lengthof the printing path is constrained to reduce the consumption of material accurately. Also, the angle between adjacent bars isconstrained to avoid sharp angles at the turning point of the 3D printing path. Next, the sensitivity analysis considering theinter-dependence of substructures is performed. Several numerical examples are given to demonstrate the validity and merits ofthe proposed method in designing structures preserving component sequences.

摘要：Urban air mobility(UAM)is an emerging concept proposed in recent years that uses electric vertical takeoff and landing vehicles(eVTOLs).UAM is expected to offer an alternative way of transporting passengers and goods in urban areas with significantly improved mobility by making use of low-altitude *** addition to other essential elements,ground infrastructure of vertiports is needed to transition UAM from concept to *** study examines the network design of UAM on-demand service,with a particular focus on the use of integer programming and a solution algorithm to determine the optimal locations of vertiports,user allocation to vertiports,and vertiport access-and egress-mode choices while considering the interactions between vertiport locations and potential UAM travel demand.A case study based on simulated disaggregate travel demand data of the Tampa Bay area in Florida,USA was conducted to demonstrate the effectiveness of the proposed *** vertiport locations were obtained by analyzing a three-dimensional(3D)geographic information system(GIS)map developed from lidar data of Florida and physical and regulation constraints of eVTOL operations at *** locations of vertiports were determined to achieve the minimal total generalized cost;however,the modeling structure allows each user to select a better mode between ground transportation and UAM in terms of generalized *** outcomes of the case study reveal that although the percentage of trips that switched from ground mode to multimodal UAM was small,users choosing the UAM service benefited from significant time *** addition,the impact of different parameter settings on the demand for UAM service was explored from the supply side,and different pricing strategies were tested that might influence potential demand and revenue generation for UAM *** combined effects of the number of vertiports and pricing strategies were also *** findings from this st

摘要：An empirical formula for composition demixing analysis in cathodic arc ion plating using alloy target is established based on the concepts of average charged state and relative demixing parameter. The level of composition demixing effect is presented by demixing degree of one element. For binary constituent alloy target, the composition change trend in coating is discussed and the limit of demixing degree for each element is determined. The content of one element with higher average charged state gets larger in coating than in alloy target, at meantime, the content of one element with lower average charged state gets less. For each one of the two constituents, the less the atom percent in alloy target, the larger the difference of its contents between the coating and the target. For triple constituent alloy target, the content change of one element with moderate average charged state is discussed in detail. Its content in coating getting larger or less is determined by the combination result of the contents of the other two elements in alloy target. For a given content of the element with moderate average charged state in triple alloy target, the content deviation level of that element from coating to alloy target will be not larger than that using binary alloy target containing only that element and one of the two others. According to the wanted coating composition, the composition design of alloy target is easily deduced from the formula.

摘要：Atomic blocks, a high-level language construct that allows programmers to explicitly specify the atomicity of operations without worrying about the implementations, are a promising approach that simplifies concurrent programming. On the other hand, temporal logic is a successful model in logic programming and concurrency verification, but none of existing temporal programming models supports concurrent programming with atomic blocks yet. In this paper, we propose a temporal programming model （αPTL） which extends the projection temporal logic （PTL） to support concurrent programming with atomic blocks. The novel construct that formulates atomic execution of code blocks, which we call atomic interval formulas, is always interpreted over two consecutive states, with the internal states of the block being abstracted away. We show that the framing mechanism in projection temporal logic also works in the new model, which consequently supports our development of an executive language. The language supports concurrency by introducing a loose interleaving semantics which tracks only the mutual exclusion between atomic blocks. We demonstrate the usage of αPTL by modeling and verifying both the fine-grained and coarse-grained concurrency.

摘要：AIM： To compare clinical results between toric and spherical periphery design orthokeratology（ortho-k） in myopic children with moderate-to-high corneal astigmatism. METHODS： This retrospective study enrolled 62 eyes of 62 subjects using toric ortho-k lenses. These subjects were assigned to the toric group. Based on the one-to-one match principle（same age, proximate spherical equivalence and corneal astigmatism）, 62 eyes of 62 subjects were enrolled and included in the spherical group. At one-year followup visit, visual acuity, corneal astigmatism, treatment zone decentration, axial elongation and adverse reaction were compared between these two groups. RESULTS： At the one-year visit, corneal astigmatism was significantly lower in the toric group（1.22±0.76 D） than in the spherical group（2.05±0.85 D）（P=0.012）. The mean magnitude of the treatment zone decentration was 0.62±0.42 mm in the toric group and 1.07±0.40 mm in the spherical group（P=0.004）. Axial elongation was significantly slower in the toric group（0.04±0.13 mm） than in the spherical group（0.09±0.13 mm）（P=0.001）. The oneyear axial elongation was significantly correlated with initial age（r=-0.487, P〈0.001） and periphery design of ortho-k lens（r=0.315, P〈0.001）. The incidence of corneal staining was lower in the toric group（8.1%） than in the spherical group（19.4%）（P〈0.001）. CONCLUSION： Toric periphery design ortho-k lenses may provide lower corneal astigmatism, better centration, slower axial elongation and lower incidence of corneal staining in myopic children with moderate-to-high corneal astigmatism.

摘要：Owing to the inherent central information processing and resource management ability,the cloud radio access network(C-RAN)is a promising network structure for an intelligent and simplified sixth-generation(6G)wireless ***,to further enhance the capacity and coverage,more radio remote heads(RRHs)as well as high-fidelity and low-latency fronthaul links are required,which may lead to high implementation *** address this issue,we propose to exploit the intelligent reflecting surface(IRS)as an alternative way to enhance the C-RAN,which is a low-cost and energy-efficient ***,we consider the uplink transmission where multi-antenna users communicate with the baseband unit(BBU)pool through multi-antenna RRHs and multiple IRSs are deployed between the users and *** can conduct either point-to-point(P2P)compression or Wyner-Ziv coding to compress the received signals,which are then forwarded to the BBU pool through fronthaul *** investigate the joint design and optimization of user transmit beamformers,IRS passive beamformers,and fronthaul compression noise covariance matrices to maximize the uplink sum rate subject to fronthaul capacity constraints under P2P compression and Wyner-Ziv *** exploiting the Arimoto-Blahut algorithm and semi-definite relaxation(SDR),we propose a successive convex approximation approach to solve non-convex problems,and two iterative algorithms corresponding to P2P compression and Wyner-Ziv coding are *** results verify the performance gain brought about by deploying IRS in C-RAN and the superiority of the proposed joint design.

摘要：High-temperature proton exchange membrane(HT-PEM)fuel cells offer more advantages than low-temperature PEM fuel *** ideal characteristics of HT-PEMs are high conductivities,low-humidity operation conditions,adequate mechanical properties,and competitive *** molecular moieties,such as benzimidazole,benzothiazole,imide,and ether ether ketone,have been introduced to polymer chain backbones to satisfy the application requirements for *** most common sulfonated polymers based on the main chain backbones have been employed to improve the *** group/chain engineering,including the introduction of SO_(3)^(-) on the side chain,grafting,branching,and crosslinking,has been widely applied to HTPEMs to further improve their proton conductivity,thermal stability,and mechanical ***,phosphoric acid-doped polybenzimidazole is the most successful polymer material for application in *** compositing/blending modification methods of polymers are effective in obtaining high PA-doping levels and superior mechanical *** this review,the current progress of various membrane materials used for HT-PEMs is *** synthesis and performance characteristics of polymers containing specific moieties in the chain backbones applied to HT-PEMs are discussed *** modification approaches and their deficiencies associated with HT-PEMs are analyzed and *** and future challenges are also presented.

摘要：A facile strategy was designed for the fabrication of Fe3O4-nanoparticle- decorated TiO2 nanofiber hierarchical heterostructures （FTHs） by combining the versatility of the electrospinning technique and the hydrothermal growth method. The hierarchical architecture of Fe3O4 nanoparticles decorated on TiO2 nanofibers enables the successful integration of the binary composite into batteries to address structural stability and low capacity. In the resulting unique architecture of FTHs, the 1D heterostructures relieve the strain caused by severe volume changes of Fe3O4 during numerous charge-discharge cycles, and thus suppress the degradation of the electrode material. As a result, FTHs show excellent performance including higher reversible capacity, excellent cycle life, and good rate performance over a wide temperature range owing to the synergistic effect of the binary composition of TiO2 and Fe304 and the unique features of the hierarchical nanofibers.

摘要：目的:研究高速动车组齿轮箱密封系统的密封性能的前提是分析内部油气分离性能。探讨密封系统中油气分离机理和密封间隙(轴向间隙宽度、轴向间隙高度差、径向密封齿形角和径向密封齿相对啮合深度)对油气分离效率的影响,为齿轮箱密封系统的优化设计提供理论基础。创新点:1.采用润滑油和空气混合介质作为工作介质,更贴合工程实践;2.采用液滴-壁面碰撞模型,分析油气分离过程中液滴的运动状态。方法:1.结合离散相模型和液滴-壁面碰撞模型,建立高速动车组齿轮箱的密封系统模型。2.通过试验和数值计算对比,验证仿真模拟的准确性和模型的适用性。3.通过仿真模拟,分析不同液滴直径下密封间隙对油气分离性能的影响;其中,密封间隙包含轴向间隙宽度、轴向间隙高度差、径向密封齿形角和径向密封齿相对插入深度比。结论:1.气流对油滴的拖曳力和油滴的惯性作用影响油滴运动轨迹和密封系统的油气分离效率;其中质量惯性力是主要因素,加速度惯性力与气流拖曳力是次要因素。2.随着轴向间隙宽度的增大,小直径油滴(1μm)分离效率降低,大直径油滴(5μm)分离效率基本不变,而过渡直径的油滴(2～4μm)分离效率先降低后增高。3.随着轴向间隙高度差和径向密封齿相对啮合深度的增大,油气分离效率增高。4.随着径向密封齿形角的增大,油气分离效率先降低后升高,齿形角为80°时,分离效率最低。5.油滴直径越大,密封间隙变化对油气分离效率的影响越小。

摘要：恰当的广告效果呈现会显著提升消费者感知,而达到广告效果的时间距离则是消费者对改变类产品的关注重点,直接影响其广告态度与购买决策。基于解释水平理论,本文通过4个实验验证了广告效果呈现方式(前后式vs.渐进式)与时间距离(远vs.近)的匹配效应:对于较长时间才能达到效果(时间距离远)的改变类产品,消费者对前后式广告具有更积极的态度;而对于较短时间即可达到效果(时间距离近)的改变类产品,消费者对渐进式广告的态度更积极,意象流畅性中介了该匹配效应。本研究结论拓展了广告效果呈现的相关研究,为企业提升改变类产品广告效果提供了新的启示。