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摘要:Due to the good balance between high efficiency and accuracy, meta-model based optimization algorithm is an important global optimization category and has been widely applied. To better solve the highly nonlinear and computation intensive en- gineering optimization problems, an enhanced hybrid and adaptive meta-model based global optimization (E-HAM) is first proposed in this work. Important region update method (IRU) and different sampling size strategies are proposed in the opti- mization method to enhance the performance. By applying self-moving and scaling strategy, the important region will be up- dated adaptively according to the search results to improve the resulting precision and convergence rate. Rough sampling strategy and intensive sampling strategy are applied at different stages of the optimization to improve the search efficiently and avoid results prematurely gathering in a small design space. The effectiveness of the new optimization algorithm is verified by comparing to six optimization methods with different variables bench mark optimization problems. The E-HAM optimization method is then applied to optimize the design parameters of the practical negative Poisson's ratio (NPR) crash box in this work. The results indicate that the proposed E-HAM has high accuracy and efficiency in optimizing the computation intensive prob- lems and can be widely used in engineering industry.
摘要:To improve aqueous solubility and anti-ischemic activity of 3-n-butylphthalide(NBP),we designed and synthesized the ring-opened derivative of NBP-ferulic acid-glucose trihybrids(S1-S8).These hybrids inhibited adenosine diphosphate(ADP)-or arachidonic acid(AA)-induced platelet aggregation,among them,S2 was 30-fold more water-soluble,and over 10-fold more potent in inhibition of platelet aggregation,as well as reduced ROS generation and protected primary neuronal cells from OGD/Rinduced damage,in comparison with NB ***,S2 was more active than its three moieties alone or in combination,suggesting that the activity of S2 may be attributed to the synergistic effects of these ***,in vivo studies indicated that S2 not only possessed good pharmacokinetic profile,but also improved NBP distribution in rodent brain,suggesting that the glucose moiety in S2 may be recognized by glucose transporter 1(GLUT1)on blood-brain barrier(BBB),promoting it to penetrate through *** findings suggest that S2 may be a promising candidate for the intervention of ischemic stroke,warranting further study.
摘要:Elbow draft-tubes are widely used in large- and medium-sized hydropower stations in many countries. During the application, handling the somatotype of elbow tubes has been found challenging: in order to maintain the designed shape of draft tube and to meet the requirement of construction lofting, the configuration of reinforcing bars and the fabrication of templates, the geometry of elbow tubes has to be accurately calculated to draw engineering graphics. Based on the derived equations in this paper, the motion of elbow tube curve envelope is simulated by using computers, which shows directly the smoothness of the curve and provides dynamic simulation for the study and optimization of the design and construction of elbow draft tubes, along with the front view and bottom view.
摘要:To search for potent anti-ischemic stroke agents,a series of tetramethylpyrazine(TMP)/resveratrol(RES)hybrids 6 a-t were designed and *** hybrids inhibited adenosine diphosphate(ADP)-or arachidonic acid(AA)-induced platelet aggregation,among them,6 d,6 g-i,6 o and 6 q were more active than *** most active compound 6 h exhibited more potent antiplatelet aggregation activity than TMP,RES,as well as positive control ticlopidine(Ticlid)and aspirin(ASP).Furthermore,6 h exerted strong antioxidative activity in a dose-dependent manner in rat pheochromocytoma PC12 cells which were treated with hydrogen peroxide(H2 O2)or hydroxyl radical(·OH).Importantly,6 h significantly protected primary neuronal cells suffered from oxygen-glucose deprivation/reoxygenation(OGD/R)injury,comparable to an anti-ischemic drug edaravone(Eda).Together,our findings suggest that 6 h may be a promising candidate warranting further investigation for the intervention of ischemic stroke.
摘要:To study the influence of roll casting process parameters on temperature and thermal-stress fields for the AZ31 magnesium alloy sheets,three-dimensional geometric and 3D finite element models for roll casting were established based on the symmetry of roll casting by ANSYS *** method and smart-sizing algorithm were used to divide finite element mesh in ANSYS software.A series of researches on the temperature and stress distributions during solidification process with different process parameters were done by 3D finite element *** temperatures of both the liquid-solid two-phase zone and liquid phase zone were elevated with increasing pouring *** the heat transfer coefficient increasing,the two-phase region for liquid-solid becomes *** the pouring temperature increasing and the increase of casting speed,the length of two-phase zone *** optimized of process parameters(casting speed 2 m/min,pouring temperature 640 ℃ and heat transfer coefficient 15 kW/(m2·℃) with the water pouring at roller exit was used to produce magnesium alloy AZ31 sheet,and equiaxed grains with the average grain size of 50 μm were achieved after roll *** simulation results give better understanding of the temperature variation in phase transformation zone and the formation mechanism of hot cracks in plates during roll casting and help to design the optimized process parameters of roll casting for Mg alloy.
摘要:认识剪切型岩爆的触发机理对地下工程科学设计与安全施工具有重要意义。为揭示隧道围岩(DTR)的剪切触发型岩爆机理,进行了砂岩的双矩形隧道和双圆形隧道物理模型剪切试验。在剪切试验过程中,利用高速摄像机和声发射监测仪对DTR的岩爆过程进行监测和记录,揭示了压剪下DTR的宏观和细观断裂特征;进而建立了5种隧道间距数值模型,分析了压剪下含隧洞试样连续-非连续剪切过程及其触发的岩爆机理;提出了一种新的能量冲击指数(S)来评价剪切型岩爆倾向性。试验结果表明,在剪切试验中,DTR的实时剪切特征、内外破裂特征和微裂纹数演化特征可划分为4个典型阶段:整体剪切压缩阶段(Ⅰ阶段)、以裂纹萌生为主的弹性阶段(Ⅱ阶段)、以裂纹扩展-贯通和剪切岩爆为主的剪切破裂阶段(Ⅲ阶段)和剪切摩擦阶段(Ⅳ阶段)。此外,试验结果还表明DTR在剪切型岩爆发生后可形成对称猫耳形缺口;微裂纹演化过程中DTR经历了裂纹预备阶段(Ⅰ阶段)、裂纹初始增长阶段(Ⅱ阶段)、裂纹快速增长阶段(Ⅲ阶段)和裂纹稳定阶段(Ⅳ阶段)。更重要的是,综合分析发现,双矩形隧道和双圆形隧道触发剪切型岩爆机制存在差别的本质是截面形状导致的结构效应,即双矩形隧道和双圆形隧道应力场分布差异导致断裂行为不同。研究结果有利于加深对剪切型岩爆机理的认识,为岩土工程防治提供理论依据。
摘要:The rechargeable aluminum-sulfur(Al-S)battery is a promising alternative-energy storage device with high energy density and made of cheap raw ***,Al-S batteries face several obstacles,especially the shuttle ***,a binder-free S@Ti_(3)C_(2)T_(x)sandwich structure film with uniform sulfur dispersion was *** two-dimensional(2D)layered material Ti_(3)C_(2)T_(x) not only has the function of binder and conductive agent but also is a promising host for sulfur *** a result,S@Ti_(3)C_(2)T_(x)film showed an initial capacity of 489 mA h g^(−1)at 300 mA g^(−1) and retained the value at 415 mA h g^(−1)after 280 stable cycles,with an average Coulombic efficiency of~95%.The film displayed higher capacity and stability than the S+Ti_(3)C_(2)T_(x)cathode prepared by the slurry-coating method(the initial capacity was 317 mA h g^(−1)and then decayed to 222 mA h g^(−1) after 160 cycles).The main capacity of S@Ti_(3)C_(2)T_(x) film in the Al-S battery came from the reversible redox reaction of S^(2−) and *** new 2D material combined with a controllable electrode structure design paves the way for the development of Al-S batteries.
摘要:To recycle vanadium and chromium from the V?Cr-bearing reducing slag,the thermodynamics of separating V(IV)and Cr(III)at 298 K was summarized in the form of potential-pH diagram and activity-pH *** potential-pH diagrams of V-Mn-H2O and Cr-Mn-H2O systems show that the electrode potential of MnO2/Mn2+is higher than that of VO2+/VO2+but lower than that of Cr2O7 2-/Cr3+,which proves that it is feasible to selectively oxidize low valent vanadium using *** activity-pH diagrams of V(V)-H2O and Cr(III)-H2O systems show that the precipitation pH of V(V)is far lower than that of Cr(III),and therefore V(V)and Cr(III)can be separated through precipitation *** on the thermodynamic analysis,the flowsheet of recovery of vanadium and chromium from the V-Cr-bearing reducing slag is designed.
摘要:近年来,煤矿井下为了提高生产效率,将盾构机应用到巷道掘进中。地质条件是决定盾构机工作效率的重要因素,盾构机施工围岩以石灰岩、砂岩等中硬岩最为有利,因此拟掘进巷道位置的岩性预测成为提高盾构机工作效率的核心问题。目前地震反演是岩性预测的重要手段,阳泉新景区块由于部分声波测井曲线缺失,对波阻抗反演产生了影响,因此,如何利用已有的测井曲线生成缺失的声波测井曲线以及如何利用盾构机工作行进中的岩性揭露数据不断更新前方岩性分布预测结果成为当前亟待解决的关键。首先对测井曲线进行标准化等预处理,针对声波测井曲线缺失问题,引入随机森林回归算法,利用密度(Density)、自然伽马(GR)、视电阻率(Res)和自然电位(SP)4种测井曲线作为特征变量,建立曲线回归预测模型,预测声波(P-wave)测井曲线。在分析声波曲线和伽马曲线原理的基础上,进行拟声波曲线构建并做拟声波反演,在反演数据体上解释K7砂岩的顶和底界面,将解释得到的地震解释层位信息从时间域数据转换到深度域,经验证实预测结果与揭露数据符合率较高。同时,结合盾构机工作行进中的岩性揭露数据对目标巷道剖面的K7砂体分布预测进行了多次更新迭代,精细刻画了巷道位置K7砂岩的分布情况,为盾构机掘进路线优选提供了有效指导。
摘要:Currently, there are a wide range of line types in the field of arch dam designing and construction, and each of them may have their own strength and weakness disparately. A trade-off between the size, stress, as well as the construction cost and complex- ity of the dam needs to be made in order to arrive at a new solution called the cycloid arch dam. Through redevelopment of VBA us- ing AutoCAD, the arch ring and the center of the arch line have been designed. Also, the stress analysis on parabola and cycloid have been done, which provides a theoretical principle that the cycloid could be regarded as a new line type of the arch dam.
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