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过渡料特性对沥青混凝土心墙开裂的影响

人民珠江 2024年第8期45卷 104-113页

作者：刘波王俊杰孙众刘良军重庆交通大学河海学院重庆400074 重庆交通大学材料科学与工程学院重庆400074 重庆巫山水利发展有限公司重庆404700 重庆腾云工程咨询有限公司重庆409000

沥青混凝土心墙的应力水平变化不仅受自身材料特性影响,也受相邻过渡料特性的制约,改变过渡料特性会对心墙水力劈裂产生较大影响。为探明过渡料特性变化与心墙开裂之间的关系,采用邓肯张E-b模型对庙堂心墙堆石坝进行有限元计算,提出了... 详细信息

沥青混凝土心墙的应力水平变化不仅受自身材料特性影响,也受相邻过渡料特性的制约,改变过渡料特性会对心墙水力劈裂产生较大影响。为探明过渡料特性变化与心墙开裂之间的关系,采用邓肯张E-b模型对庙堂心墙堆石坝进行有限元计算,提出了抗裂安全系数Kn来表征心墙发生水力劈裂的危险程度,并在此基础上采用正交实验的方法比较了过渡料E-b模型各个参数与心墙开裂的相关性,得出结论:过渡料刚度越大,心墙发生水力劈裂可能性越大;在过渡料选择上,应当优先考虑高敏感性因素破坏比(R_(f))、卸荷再填筑时的弹性模量指数(n)、土体内摩擦角(φ_(0))、初始弹性模量(K),在满足沥青混凝土心墙坝设计和施工规范的前提下,选取R_(f)较大,K、φ_(0)较小的过渡料,能够有效提升沥青混凝土心墙坝抗裂性能。

关键词：沥青混凝土心墙坝水力劈裂总应力法心墙抗裂安全比例指标

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具有可变真空结构的物镜优化设计及性能分析

光学学报 2024年第5期44卷 193-202页

作者：史丽娜王鹏飞刘俊标王岩殷伯华韩立中国科学院电工研究所北京100190 中国科学院大学北京100049

环境扫描电子显微镜(ESEM)能够在低真空环境模式下对含水、含油以及生物等样品进行高分辨率观测。由于电子束通道与样品室间存在着极大的真空压差,采用真空差分结构会导致出现物镜的工作距离增加、偏转范围缩小、电子束和气体碰撞概率... 详细信息

环境扫描电子显微镜(ESEM)能够在低真空环境模式下对含水、含油以及生物等样品进行高分辨率观测。由于电子束通道与样品室间存在着极大的真空压差,采用真空差分结构会导致出现物镜的工作距离增加、偏转范围缩小、电子束和气体碰撞概率增加等问题,最终影响成像分辨率和效率。针对这些问题,本文从电子光学理论出发,综合考虑了ESEM中物镜结构和真空差分结构,将两者结合在一起进行优化设计,提出了一种具有可变真空结构的物镜设计方法,并搭建了实验平台,开展了物镜磁场测试、真空压差测试和分辨率测试。测试结果表明,在目前实验条件和133 Pa的低真空环境模式下,工作距离为15 mm时,20μm×20μm的扫描场对应的成像分辨率优于50 nm。

关键词：电子光学物镜可变真空结构压差光阑节流管

Adaptive Leader-Follower Consensus Control of Multiple Flexible Manipulators with Actuator Failures and Parameter Uncertainties

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IEEE/CAA Journal of Automatica Sinica 2023年第4期10卷 1020-1031页

作者： Yu liu Lin Li School of Automation Science and Engineering South China University of TechnologyGuangzhou 510640 Research and Development Center of Precision Electronic Manufacturing Technology Guangzhou Institute of Modern Industrial TechnologyGuangzhou 511458China

In this paper,the leader-follower consensus problem for a multiple flexible manipulator network with actuator failures,parameter uncertainties,and unknown time-varying boundary disturbances is *** purpose of this study is to develop distributed controllers utilizing local interactive protocols that not only suppress the vibration of each flexible manipulator but also achieve consensus on joint angle position between actual followers and the virtual *** the accomplishment of the reconstruction of the fault terms and parameter uncertainties,the adaptive neural network method and parameter estimation technique are employed to compensate for unknown items and bounded ***,the Lyapunov stability theory is used to demonstrate that followers’angle consensus errors and vibration deflections in closed-loop systems are uniformly ultimately ***,the numerical simulation results confirm the efficacy of the proposed controllers.

关键词： Actuator failures leader-follower consensus multiple flexible manipulators neural network parameter uncertainties

考虑装配工艺的螺栓连接转子系统振动特性研究

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机械工程学报 2024年第8期60卷 396-406页

作者：罗忠石宝龙吴法勇李玉奇刘凯宁张小霞东北大学机械工程与自动化学院沈阳110819 东北大学航空动力装备振动及控制教育部重点实验室沈阳110819 中国航发沈阳发动机研究所沈阳110015 广西科技大学机械与交通工程学院柳州545006

针对由装配工艺引起的航空发动机螺栓连接转子系统振动问题,基于ANSYS仿真分析了螺栓装配顺序对连接结构时变弯曲刚度的影响,以及螺栓预紧力不平衡产生的转子转轴初始变形。基于有限元法建立螺栓连接转子系统动力学模型,螺栓连接结构由... 详细信息

针对由装配工艺引起的航空发动机螺栓连接转子系统振动问题,基于ANSYS仿真分析了螺栓装配顺序对连接结构时变弯曲刚度的影响,以及螺栓预紧力不平衡产生的转子转轴初始变形。基于有限元法建立螺栓连接转子系统动力学模型,螺栓连接结构由两节点连接单元模拟。采用Newmark-β法求解运动方程,研究装配顺序对转子系统临界转速及其对应振幅的影响,并基于螺栓连接转子试验台开展试验验证了理论分析结果的正确性。研究发现,螺栓在顺序拧紧和交叉拧紧时连接结构弯曲刚度均呈现分段线性特性,而交叉拧紧比顺序拧紧拥有更大且更加对称的的残余预紧力,因此交叉拧紧的转轴初始变形较小,对应连接结构的第一阶段弯曲刚度较大,使得转子系统一阶临界转速高于顺序拧紧;转轴初始变形会影响转子系统时域振幅。螺栓装配工艺的考虑有助于进一步掌握螺栓连接结构对转子系统响应特性的影响。

关键词：螺栓连接转子系统装配顺序预紧力不平衡振动特性

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压缩载荷下新型折纸结构的吸能特性研究

Acta Mechanica Sinica 2024年第5期40卷 116-140页

作者：唐勇李奇奇苗秀娟陈博浩尹来容刘鑫顾成波 College of Automotive and Mechanical Engineering Changsha University of Science & Technology Changsha China AISN Innovative Design and Manufacturing Co. Ltd. Liuzhou China

受折纸形状的启发,通过单折纸单元结构(SOSs)的排列获得了两种折纸管。在准静态压缩载荷下,同向折纸管(SOT)的比吸能(SEA)值比反向折纸管(ROT)高13.46%.ROT显示了压缩旋转的变形模式,而SOT则是逐层破碎.通过折纸管和连接板的组合,提出... 详细信息

受折纸形状的启发,通过单折纸单元结构(SOSs)的排列获得了两种折纸管。在准静态压缩载荷下,同向折纸管(SOT)的比吸能(SEA)值比反向折纸管(ROT)高13.46%.ROT显示了压缩旋转的变形模式,而SOT则是逐层破碎.通过折纸管和连接板的组合,提出了两层、三层和四层的折纸结构,它们的能量吸收效率明显高于折纸管。这些折纸结构表现出稳定的变形模式,主要是轴向压缩、扭转和混合变形模式.具有四个ROT的折纸结构(4R)的变形模式与麻花的形状相似.关于两层结构,由反向SOT(RSOT)和SOT组成的折纸结构的SEA值明显高于由ROT和SOT以及ROT和RSOT组成的折纸结构.此外,两层折纸结构的压缩性能明显优于三层和四层折纸结构.具有两个RSOT和两个SOT的两层折纸结构(2RS2S)的SEA值分别高于具有四个A细胞的三层折纸结构(4A)和具有一个C细胞和三个D细胞的四层折纸结构(1C3D)68.05%和64.48%.总之,这些折纸结构表现出卓越的机械性能,在吸能结构中具有广泛的应用潜力.

关键词：能量吸收效率变形模式折纸单元结构压缩载荷连接板吸能结构轴向压缩

一种基于安全多方计算的快速Transformer安全推理方案

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计算机研究与发展 2024年第5期61卷 1218-1229页

作者：刘伟欣管晔玮霍嘉荣丁元朝郭华李博北京航空航天大学网络空间安全学院北京100191 复杂关键软件环境全国重点实验室(北京航空航天大学) 北京100878

Transformer模型在自然语言处理、计算机视觉等众多领域得到了广泛应用,并且有着突出的表现.在Transformer的推理应用中用户的数据会被泄露给模型提供方.随着数据隐私问题愈发得到公众的关注,上述数据泄露问题引发了学者们对Transforme... 详细信息

Transformer模型在自然语言处理、计算机视觉等众多领域得到了广泛应用,并且有着突出的表现.在Transformer的推理应用中用户的数据会被泄露给模型提供方.随着数据隐私问题愈发得到公众的关注,上述数据泄露问题引发了学者们对Transformer安全推理的研究,使用安全多方计算(secure multi-party computation,MPC)实现Transformer模型的安全推理是当前的一个研究热点.由于Transformer模型中存在大量非线性函数,因此使用MPC技术实现Transformer安全推理会造成巨大的计算和通信开销.针对Transformer安全推理过程中开销较大的Softmax注意力机制,提出了2种MPC友好的注意力机制Softmax freeDiv Attention和2Quad freeDiv Attention.通过将Transformer模型中的Softmax注意力机制替换为新的MPC友好的注意力机制,同时结合激活函数GeLU的替换以及知识蒸馏技术,提出了一个MPC友好的Transformer转换框架,通过将Transformer模型转化为MPC友好的Transformer模型,提高Transformer安全推理的效率.在局域网环境下使用安全处理器(secure processing unit,SPU)提供的隐私计算协议,基于所提出的MPC友好的Transformer转换框架,在SST-2上使用bert-base进行安全推理.测试结果表明,在保持推理准确率与无近似模型一致的情况下,安全推理计算效率提高2.26倍.

关键词：安全推理 Transformer 安全多方计算安全处理器知识蒸馏

Prediction of spatial soil loss impacted by long-term land-use/land-cover change in a tropical watershed

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Geoscience Frontiers 2019年第2期10卷 389-403页

作者： J.H.Abdulkareem b.Pradhan w.N.A.Sulaiman N.R.Jamil Department of Environmental Science Faculty of Environmental StudiesUniversiti Putra Malaysia (UPM) Department of Soil Science Institute for Agricultural Research/Faculty of AgricultureAhmadu Bello University Department of Civil Engineering Faculty of EngineeringGeospatial Information Science Research Center (GISRC)Universiti Putra Malaysia (UPM) Centre for Advanced Modeling and Geospatial Information Systems (CAMGIS) Faculty of Engineering and Information TechnologyUniversity of Technology Sydney Department of Energy and Mineral Resources Engineering Choongmu-gwanSejong University

The devastating effect of soil erosion is one of the major sources of land degradation that affects human lives in many ways which occur mainly due to deforestation, poor agricultural practices, overgrazing,wildfire and urbanization. Soil erosion often leads to soil truncation, loss of fertility, slope instability, *** causes irreversible effects on the poorly renewable soil resource. In view of this, a study was conducted in Kelantan River basin to predict soil loss as influenced by long-term land use/land-cover(LULC) changes in the area. The study was conducted with the aim of predicting and assessing soil erosion as it is influenced by long-term LULC changes. The 13,100 km^2 watershed was delineated into four sub-catchments Galas, Pergau, Lebir and Nenggiri for precise result estimation and ease of execution. GIS-based Universal Soil Loss Equation(USLE) model was used to predict soil loss in this study. The model inputs used for the temporal and spatial calculation of soil erosion include rainfall erosivity factor,topographic factor, land cover and management factor as well as erodibility factor. The results showed that 67.54% of soil loss is located under low erosion potential(reversible soil loss) or 0-1 t ha^(-1) yr^(-1) soil loss in Galas, 59.17% in Pergau, 53.32% in Lebir and 56.76% in Nenggiri all under the 2013 LULC *** from the correlation of soil erosion rates with LULC changes indicated that cleared land in all the four catchments and under all LULC conditions(1984-2013) appears to be the dominant with the highest erosion losses. Similarly, grassland and forest were also observed to regulate erosion rates in the area. This is because the vegetation cover provided by these LULC types protects the soil from direct impact of rain drops which invariably reduce soil loss to the barest minimum. Overall, it was concluded that the results have shown the significance of LULC in the control of erosion. Maps generated from the study may be usef

关键词： Soil erosion USLE Landuse/cover changes GIS Malaysia

ELECTROPOLYMERIZATION OF ANILINE ON ZINC-ELECTROPLATED STEEL FROM NEUTRAL AQUEOUS MEDIUM bY SINGLE-STEP PROCESS

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 849-855页

作者： Y.P.Zhao R.H.Yin w.M.Cao A.b.Yuan Dept.ofChem. CollegeofScienceShanghaiUniv.Shanghai200436China

Polyaniline films were successfully synthesized on zinc-electroplated steel sheets in sodium salicylate (1mol·dm-3) aqueous medium. This one-step aniline electropolymerization process has been studied in this paper using different electrochemical techniques. And scanning electron microscopy (SEM) showed that the polymer coatings rapidly formed by either galvanostatic or potentiostatic mode performed compact and uniform in morphology. Potentiodynamic polarization was used to test the anticorrosion properties of this polymer.

关键词： anticorrosion electropolymerization polyaniline salicylate zinc

Discovery of synergistic anti-inflammatory compound combination from herbal formula GuGe FengTong Tablet

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Chinese Journal of Natural Medicines 2018年第9期16卷 683-692页

作者： liu Le-Le liu Qun LI Ping liu E-Hu State Key Laboratory of Natural Medicines School of Traditional Chinese PharmacyChina Pharmaceutical University

Multi-components in herbal formulae exert holistic effects in synergistic or additive manners. However, appropriate strategies and supportive evidences are still lacking to uncover the synergistic or additive combinations. The present investigation aimed at seeking a screening strategy to identify the targeted combinations in GuG e FengT ong Tablet(GGFTT), an herbal formula. Two compounds, belonging to different chemical classes, were combined with different concentration ratios and their anti-inflammation effects were investigated. The most significant anti-inflammatory combinations were evaluated by combination index(CI) method(additive effect, CI = 1; synergism, CI 1). The modulating effects of candidate combinations on pro-inflammatory cytokines and MAPKs signaling pathway were also detected. Two combinations, "biochanin A + 6-gingerol"(bio-6 G) and "genistein + 6-gingerol"(Gen-6 G), showed synergistic effects(CI bio-6 G was selected for further study. Compared with single compound, bio-6 G could synergistically inhibit the production of pro-inflammatory cytokines(TNF-α, IL-1β, and IL-6) and the activation of MAPKs signaling pathway in LPS-stimulated RAw264.7 cells. The combined results showed that bio-6 G was a synergistic anti-inflammatory combination in GGFTT. Our results could provide a useful strategy to screen the synergistic combinations in herbal formulae.

关键词： GuGe FengTong Tablet Synergistic combinations Anti-inflammation Cytokines MAPKs