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Investigation on the vortical structures by the Liutex method in turbulent channels at Re_(τ)=180 with scalloped and triangular riblet control

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Journal of Hydrodynamics 2024年第1期36卷 35-52页

作者： Zhang-dan Yu shang jiang Hai-dong Yu Bi-yu Pang Xin Dong Yi-qian Wang School of Mathematical Sciences Soochow UniversitySuzhou215006China Beijing Institute of Astronautical System Engineering Beijing100076China

Riblets are a series of small protrusions formed along the flow direction,which have been extensively studied as a passive turbulent drag reduction *** and numerical simulations have shown that well-designed riblets can significantly reduce drag in turbulent flows,making them highly promising and valuable for various *** this study,we focus on a scalloped riblet,which is designed by smoothly connecting two third-order polynomials,and thus the sharpness of the tip and the curvature of the valley can be well *** conduct direct numerical simulations of turbulent channel with smooth plate,scalloped riblet-mounted and triangular riblet-mounted *** in wall units of W^(+)=20 and height-width ratio ofγ=0.5 are selected for both riblet *** with the smooth plate case,the scalloped riblet case achieves an 8.68%drag reduction,while the triangular riblet case achieves a 4.79%drag *** obtained drag reduction rate of the triangular riblet is consistent with previous experiments and simulations,and the results indicate that the scalloped riblet is more effective in reducing drag and deserves further *** compare turbulent statistics of the scalloped riblet case with those of the triangular riblet *** mean velocity profiles of riblets are similar,but both the Reynolds shear stress and second-order statistics of velocity fluctuations and Liutex are significantly reduced in the scalloped riblets controlled turbulent channel,indicating that the scalloped riblet can more effectively suppress the spanwise and wall-normal turbulent intensity near the *** also compare the pre-multiplied spectra of streamwise velocity and streamwise Liutex component for the three cases to investigate the energy distribution and characteristics of Liutex *** Liutex vortex identification method is also utilized to analyze the instantaneous flow field,which provides insights into the flow field and could be bene

关键词： Liutex vector riblet drag reduction tip sharpness turbulent channel scalloped

Heterostructured Co_(3)Se_(4)/CoSe_(2)@C nanoparticles attached on three-dimensional reduced graphene oxide as a promising anode towards Li-ion batteries

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Frontiers of Materials Science 2024年第2期18卷 101-115页

作者： Mingjun Pang Zhaoyang Song Miaomiao Mao shang jiang Ruxia Zhang Runwei Wang jianguo Zhao Engineering Research Center of Coal-based Ecological Carbon Sequestration Technology of the Ministry of Education Shanxi Datong UniversityDatong 037009China State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of ChemistryJilin UniversityChangchun 130012China

In situ carbon-coated Co_(3)Se_(4)/CoSe_(2)(Co_(x)Se_(y))nanoparticles(NPs)attached on three-dimensional(3D)reduced graphene oxide(rGO)sheets were skillfully developed in this work,which involved the environment-friendly hydrothermal method,freeze drying,and selenide *** the structure,the glucose-derived carbon layer exhibited significantly homogeneous dispersion under an argon *** structure not only has enhanced stability,but also can effectively mitigate the volume swell of Co_(x)Se_(y) *** resulted Co_(3)Sea/CoSe_(2)@C/rGO(CSe@C/rGO)exhibited a specific surface area(SSA)of 240.9 m^(2)·g^(-1),offering more electrochemically active sites for the storage of energy related to lithium *** rGO matrix held exceptional flexibility and functional structural rigidity,facilitating the swift ion intercalation and ensuring the high conductivity and recyclability of the *** applied to anodes designed for lithium-ion batteries(LiBs),this material demonstrated distinguished rate and ultra-high reversible capacity(872.98 mA·h·g^(-1) at 0.5 A·g^(-1)).Meanwhile,its capacity retention reached 119.5%after 500 cycles at 2 A·g^(-1),with a coulombic efficiency of 100%.This work potentially paves the way for generating fast and powerful metal selenide anodes and initiating LiBs with good performance.

关键词： CSe@C/rGO lithium-ion battery reduced graphene oxide electrochemicalperformance heterostructure

Π型叠合梁斜拉桥涡激振动性能及气动措施研究

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振动工程学报 2024年第5期37卷 830-837页

作者：蒋尚君朱金鲁胜龙李永乐康锐西南交通大学土木工程学院桥梁工程系四川成都610031

型叠合梁为气动钝体结构,容易发生气动失稳。本文以一座Π型截面叠合梁斜拉桥作为工程背景,采用风洞节段模型试验与计算流体动力学(CFD)方法,对主梁的涡激振动性能及相应的气动抑振措施展开了研究。在风洞节段模型试验中获得涡激振动风... 详细信息

型叠合梁为气动钝体结构,容易发生气动失稳。本文以一座Π型截面叠合梁斜拉桥作为工程背景,采用风洞节段模型试验与计算流体动力学(CFD)方法,对主梁的涡激振动性能及相应的气动抑振措施展开了研究。在风洞节段模型试验中获得涡激振动风速区间,讨论了不同气动措施的抑振效果,运用计算流体动力学(CFD)方法对主梁涡振发生机理及气动措施抑振机理进行了初步研究。结果表明:在原始断面下,由于尾迹区旋涡的周期性脱落以及主梁上、下表面旋涡演变的相互作用,导致了涡激振动发生。在采取三种不同抑振措施后,除采用上L型导流板断面在+3°风攻角下发生扭转涡振外,其余优化断面均能使得来流平稳地通过,从而抑制涡振发生。本研究可对Π型叠合梁断面的斜拉桥抗风设计提供一定参考。

关键词：涡激振动抑振措施叠合梁风洞试验计算流体动力学(CFD)

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罗源湾潮致余流特征及其对物质分布的影响

热带海洋学报 2024年第1期43卷 28-39页

作者：丁一王翠姜尚陈秋明自然资源部第三海洋研究所福建厦门361005

基于MIKE 3开展了罗源湾的三维数值模拟,以流场和断面垂向流速阐释了罗源湾的潮流分布特征,计算了罗源湾的潮致余流场,采用拉格朗日粒子追踪法模拟了具有粒子特性的物质在湾内的运移并分析了粒子的运动规律,结合潮流和潮致余流特征讨论... 详细信息

基于MIKE 3开展了罗源湾的三维数值模拟,以流场和断面垂向流速阐释了罗源湾的潮流分布特征,计算了罗源湾的潮致余流场,采用拉格朗日粒子追踪法模拟了具有粒子特性的物质在湾内的运移并分析了粒子的运动规律,结合潮流和潮致余流特征讨论了罗源湾不同区域的物理自净能力。研究结果表明,罗源湾西北部、东北岸内凹处和内湾口处形成了余环流结构,湾内不同区域的物质分布与潮致余流结构有明显相关性,粒子在罗源湾西北部海域运移缓慢,而湾口及可门水道附近具有较好的自净能力。本研究为进一步探讨罗源湾污染物质分布机制提供了科学依据,为罗源湾的污染控制和环境保护提供了技术支撑,研究方法也为其他海湾的相关研究提供借鉴参考。

关键词：罗源湾 MIKE 3 潮流特征潮致余流拉格朗日粒子追踪

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考虑转矩脉动的电动汽车传动系统扭转振动抑制

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微特电机 2024年第5期52卷 52-57,64页

作者：陈磊江尚刘帅索恩格汽车电动系统有限公司长沙410119 合肥工业大学汽车与交通工程学院合肥230009

车用电机低频转矩脉动极易引发电驱动传动系统的扭转振动,降低电动汽车的驾乘体验。采用集中参数法建立典型电驱动传动系统动力学模型,获取传动系统在转矩脉动作用下的扭转振动频率分布规律;利用电机有限元仿真获取电机转矩脉动在齿槽... 详细信息

车用电机低频转矩脉动极易引发电驱动传动系统的扭转振动,降低电动汽车的驾乘体验。采用集中参数法建立典型电驱动传动系统动力学模型,获取传动系统在转矩脉动作用下的扭转振动频率分布规律;利用电机有限元仿真获取电机转矩脉动在齿槽、铁心磁饱和、磁场非正弦等因素作用下的数值解,并建立以定子电流为变量的转矩脉动精确解析模型;提出削弱低频转矩脉动的参考电流谐波设计与电流谐波闭环控制方法,实现电驱动传动系统扭转振动的主动抑制;在MATLAB/Simulink中完成电机转矩脉动模型与传动系统动力学模型的联合仿真,验证所述传动系统扭转振动特性分析与主动抑制的有效性。

关键词：电动汽车转矩脉动传动系统扭转振动

On pricing of corporate securities in the case of jump-diffusion

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Applied Mathematics(A Journal of Chinese Universities) 2014年第2期29卷 205-216页

作者： REN Xue-min jiang Li-shang Department of Mathematics Tongji University

Structural models of credit risk are known to present vanishing spreads at very short maturities. This shortcoming, which is due to the diffusive behavior assumed for asset values, can be circumvented by considering discontinuities of the jump type in their evolution over time. In this paper, we extend the pricing model for corporate bond and determine the default probability in jump-diffusion model to address this issue. To make the problem clearly, we first investigate the case that the firm value follows a geometric Brownian motion under similar assumptions to those in Black and Scholes（1973）, Briys and de Varenne（1997）, i.e, the default barrier is KD （t, T） and the recovery rate is （1 -w）, where D （t, T） is the price of zero coupon default free bond and w is a constant （0 〈 w 〈 1）. By changing the numeraire, we obtain the closed-form solution for both the price of bond and default probability. Further, we consider the case of jump-diffusion and suppose that a firm will go bankruptcy if its value Vt 〈 KD （t, T） and at the same time, the bondholder will receive （1 - w） vt/k By introducing the Green function of PDE with absorbing boundary and converting the problem to an II-type Volterra integral equation, we get the closed-form expressions in series form for bond price and corresponding default probability. Numerical results are presented to show the impact of different parameters to credit spread of bond.

关键词： default risk corporate bond stochastic interest rate jump diffusion process.

Pattern Formation and Continuation in a Trineuron Ring with Delays

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Acta Mathematica Sinica,English Series 2007年第5期23卷 799-818页

作者： shang jiang GUO Li Hong HUANG College of Mathematics and Econometrics Hu'nan University Changsha 410082 P. R. China

In this paper, we consider a single-directional ring of three neurons with delays. First, linear stability of the model is investigated by analyzing the associated characteristic transcendental equation. Next, we studied the local Hopf bifurcations and the spatio-temporal patterns of Hopf bifurcating periodic orbits. Basing on the normal form approach and the center manifold theory, we derive the formula for determining the properties of Hopf bifurcating periodic orbit, such as the direction of Hopf bifurcation. Finally, global existence conditions for Hopf bifurcating periodic orbits are derived by using degree theory methods.

关键词： ring networks periodic solution Hopf bifurcation stability

一例多钒酸盐杂化材料的制备及高效催化烯烃环氧化

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无机化学学报 2024年第4期40卷 799-808页

作者：李宁杜思宇王雪怡杨辉周涛关致敏费鹏马宏芳蒋尚山西大同大学化学与化工学院大同037009

以2-(2-吡啶基)咪唑(pIM)、Co^(2+)和NaVO_(3)为原料,在水热条件下,制备了新的钒氧簇化合物[Co(pIM)V_(2)O_(6)](1)。采用X射线单晶衍射、粉末X射线衍射、傅里叶变换红外光谱和元素分析等方法对化合物进行了表征。单晶解析表明,该化合物... 详细信息

以2-(2-吡啶基)咪唑(pIM)、Co^(2+)和NaVO_(3)为原料,在水热条件下,制备了新的钒氧簇化合物[Co(pIM)V_(2)O_(6)](1)。采用X射线单晶衍射、粉末X射线衍射、傅里叶变换红外光谱和元素分析等方法对化合物进行了表征。单晶解析表明,该化合物由VO_(4)四面体和CoO_(3)N_(2)四方锥通过氧原子共边、共角连接成二维结构。基于钒氧簇在催化氧化体系中的高效活性,1作为非均相反应的催化剂,在以H_(2)O_(2)为氧化剂的催化烯烃环氧化反应中表现出优秀的催化性能,催化剂能够多次重复使用且活性基本保持不变。此外,磁化率研究表明1中存在反铁磁相互作用。

关键词：多钒酸盐非均相催化剂烯烃环氧化磁性

精氨酸对热应激诱导奶牛中性粒细胞凋亡的影响

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中国兽医学报 2024年第5期44卷 1008-1013,1018页

作者：王超姜尚李心慰宋玉祥冯海华吉林大学动物医学学院吉林长春130062

旨在研究热应激对奶牛中性粒细胞(polymorphonuclear granulocyte, PMN)凋亡的影响,并探究精氨酸(L-arginine,L-Arg)是否对热应激诱导下的奶牛PMN具有保护作用。利用从健康奶牛分离培养的PMN构建体外试验模型,分为对照组(Con组,37℃)和... 详细信息

旨在研究热应激对奶牛中性粒细胞(polymorphonuclear granulocyte, PMN)凋亡的影响,并探究精氨酸(L-arginine,L-Arg)是否对热应激诱导下的奶牛PMN具有保护作用。利用从健康奶牛分离培养的PMN构建体外试验模型,分为对照组(Con组,37℃)和热应激组(HS组,42℃培养0.0、0.5、1.0、1.5、2.0、2.5、3.0 h),通过CCK-8法检测细胞活性,确定最适热处理时间为2.5 h;将从健康奶牛分离得到的PMN与不同浓度(2、4、6、8、10 mmol/L)L-Arg预孵育30 min后,再置于42℃下培养2.5 h,利用CCK-8法检测细胞活性,最终筛选出L-Arg的最佳使用浓度为4 mmol/L。通过Western blot检测热休克蛋白70(HSP70)和凋亡关键蛋白c-CASP 3的蛋白丰度,流式细胞术检测PMN凋亡率。结果显示,相对于Con组,HS组PMN HSP70蛋白的丰度显著升高(P<0.01),c-CASP 3与CASP 3的蛋白丰度比显著升高(P<0.01),同时PMN凋亡率显著升高(P<0.01);而4 mmol/L的L-Arg预孵育可显著缓解热应激对奶牛PMN的c-CASP 3与CASP 3的蛋白丰度(P<0.01)和凋亡(P<0.05)的影响。这些结果表明,热应激能引起奶牛PMN凋亡,而L-Arg能缓解热应激对奶牛PMN的促凋亡作用。

关键词：精氨酸奶牛热应激中性粒细胞凋亡