检索结果-南通市图书馆

Theoretical study on bubble dynamics under hybrid-boundary and multi-bubble conditions using the unified equation

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2023年第12期66卷 142-157页

作者： A-Man Zhang shi-min li Pu Cui Shuai li Yun-Long liu College of shipbuilding Engineering Harbin Engineering UniversityHarbin 150001China Nanhai Institute of Harbin Engineering University Sanya 572024China

This paper aims to use the unified bubble dynamics equation to investigate bubble behavior in complex scenarios involving hybrid free surface/wall boundaries and interactions between multiple *** effect of singularity movement on the unified equation’s form is analyzed after deriving the bubble pulsation equation using a moving point source and a dipole,followed by discussions on the effect of migration compressibility-related terms on the bubble *** addition,the present study accounts for the impact of hybrid boundaries,including crossed and parallel boundaries,by introducing a finite number of mirror bubbles for the former and an infinite number of mirror bubbles for the *** bubble experiments and numerical simulation are conducted to validate the present *** application of the unified equation in multi-bubble interactions is exemplified by computing a spherical bubble array containing more than 100 uniformly distributed cavitation bubbles under different boundary *** bubble cluster-induced pressure peak can reach nearly two times or even higher than that of an individual bubble,highlighting the damage potential caused by cavitation bubble clusters.

关键词： bubble dynamics multiphase flows cavitation

Theoretical analysis of the surface temperature regulation of an infrared false target subjected to periodical ambient conditions

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2016年第5期12卷 360-366页

作者： shi-min li Hong YE Qi-zhao liN Department of Thermal Science and Energy Engineering University of Science and Technology of China

Infrared false target is an important mean to induce the infrared-guided weapons,and the key issue is how to keep the surface temperature of the infrared false target to be the same as that of the object to be ***-dimensional heat transfer models of a metal plate and imitative material were established to explore the influences of the thermophysical properties of imitative material on the surface temperature difference（STD） between the metal plate and imitative material which were subjected to periodical ambient *** is elucidated that the STD is determined by the imitative material’s dimensionless thickness（dim*,） and the thermal inertia(Pim).When dim* is above 1.0,the STD is invariable as long as Pim is a *** if the dimensionless thickness of metal plate（d,m*） is also larger than 1.0,the STD approaches to zero as long as Pimis the same as the thermal inertia of metal plate（Pm）.When dim* is between 0.08 and 1,the STD varies irregularly with Pim and dim*.However,if dm* is also in the range of 0.08-1,the STD approaches to zero on condition that Pim=Pm and dim*= dm*.If dim*,is below 0.08,the STD is unchanged when Pimdim* is a *** if dm* is also less than 0.08,the STD approaches to zero as long as Pimdim* = Pmdm*.Furthermore,an applicationoriented discussion indicates that the imitative material can be both light and thin via the application of the phase change material with a preset STD because of its high specific heat capacity during the phase transition process.

关键词： Infrared false target Surface temperature Periodical ambient conditions Thermal inertia Dimensionless thickness

A linear complementarity model for multibody systems with frictional unilateral and bilateral constraints

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2011年第4期27卷 587-592页

作者： Hai-Ping Gao Qi Wang shi-min Wang li Fu Department of dynamics and control Beihang University 100191 Beijing China

The Lagrange-I equations and measure differential equations for multibody systems with unilateral and bilateral constraints are constructed. For bilateral constraints, frictional forces and their impulses contain the products of the filled-in relay function induced by Coulomb friction and the absolute values of normal constraint reactions. With the time-stepping impulse-velocity scheme, the measure differential equations are discretized. The equations of horizontal linear complementarity problems （HLCPs）, which are used to compute the impulses, are constructed by decomposing the absolute function and the filled-in relay function. These HLCP equations degenerate into equations of LCPs for frictional unilateral constraints, or HLCPs for frictional bilateral constraints. Finally, a numerical simulation for multibody systems with both unilateral and bilateral constraints is presented.

关键词： Coulomb friction Bilateral constraint Unilat-eral constraint - Horizontal linear complementarity problem(HLCP) Time-stepping impulse-velocity algorithm

Effect of a rigid structure on the dynamics of a bubble beneath the free surface

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2021年第6期11卷 355-361页

作者： shi-min li A-Man Zhang Nian-Nian liu College of shipbuilding Engineering Harbin Engineering UniversityHarbin 150001China

The coupling effect between a pulsating bubble and a free surface near a rigid structure is a complicated physical *** this study,the evolution of an underwater explosion bubble and the free surface near a rigid structure is modeled by the boundary integral *** approach of“double-node method”is used to maintain the stability of fluid-structure junction in the simulations,and meshes on the free surface and the structure are transformed to an open domain to ensure the calculation accuracy and *** are conducted against an underwater explosion experiment near a rigid *** a result,the simulations trace the jetting behavior of the bubble and the rise of the free ***,the bubble migration and the height of the free surface for different structure draughts are analyzed.

关键词： Underwater explosion Bubble dynamics Boundary integral method

Physiological and pathological functions of circular RNAs in the nervous system

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2024年第2期19卷 342-349页

作者： min Zhou shi li Chuan Huang School of life Sciences Chongqing UniversityChongqingChina

Circular RNAs(circRNAs)are a class of covalently closed single-stranded RNAs that are expressed during the development of specific cells and *** play crucial roles in physiological and pathological processes by sponging microRNAs,modulating gene transcription,controlling the activity of certain RNA-binding proteins,and producing functional peptides.A key focus of research at present is the functionality of circRNAs in the nervous system and several advances have emerged over the last 2 ***,the precise role of circRNAs in the nervous system has yet to be comprehensively *** this review,we first summarize the recently described roles of circRNAs in brain development,maturity,and ***,we focus on the involvement of circRNAs in various diseases of the central nervous system,such as brain cancer,chronic neurodegenerative diseases,acute injuries of the nervous system,and neuropathic pain.A better understanding of the functionality of circRNAs will help us to develop potential diagnostic,prognostic,and therapeutic strategies to treat diseases of the nervous system.

关键词： Alzheimer’s disease amyotrophic lateral sclerosis brain development circRNAs neuropathic pain Parkinson’s disease

Synthesis and Characterization of Layered Co_2(OH)_3(CH_3COO)·H_2O

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2011年第6期27卷 910-914页

作者： ZHENG De-shan WANG Yan-zhong shi li-min SUN Si-xiu School of Materials and Chemical Engineering Xi＇an Technological University Xi＇an 710032 P. R. China School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China

Layered hydroxide metal acetate Co2（OH）3（CH3COO）·H2O with an interlayer spacing of 1.282 nm has been synthesized by a novel method which is employed in ethanol-aqueous mixed solvents media. Experiment results show that the purity of the product by the modified method is higher compared with that by the previous methods. A complete characterization of the as-prepared samples was performed by means of X-ray powder diffraction, IR spectroscopy, scanning electron microscope, as well as magnetic measurement. The facile and effective approach for the preparation of this compound in this study is very interesting and important because it has wide application in the field of anionic exchange reaction for the synthesis of hybrid organic-inorganic compounds.

关键词： Anionic exchange reaction Hybrid organic-inorganic compound Layered hydroxide cobalt acetate Magnetic property

血清miR-497、miR-5787水平变化对重症脑卒中并发不同严重程度肺部感染的预测及与炎症反应的相关性

在线全文

学校读者我要写书评

暂无评论

河北医科大学学报 2024年第9期45卷 1018-1024页

作者：韩雪娇陈月静师丽敏刘洁河北省邢台市第三医院呼吸与危重症医学科河北邢台054000 河北省邢台市第三医院重症医学科河北邢台054000

目的探讨血清miR-497、miR-5787水平变化对重症脑卒中并发不同严重程度肺部感染的预测及与炎症反应的相关性。方法回顾性研究河北省邢台市第三医院收治的重症脑卒中患者202例,根据是否发生肺部感染和病情严重程度,将患者分成非感染组、... 详细信息

目的探讨血清miR-497、miR-5787水平变化对重症脑卒中并发不同严重程度肺部感染的预测及与炎症反应的相关性。方法回顾性研究河北省邢台市第三医院收治的重症脑卒中患者202例,根据是否发生肺部感染和病情严重程度,将患者分成非感染组、轻中度感染组和重症感染组,检测不同组别患者血清miR-497和miR-5787,并收集炎性因子,Pearson法分析血清miR-497和miR-5787与炎性因子的相关性,单因素和多因素Logistic回归分析确定肺部感染不同严重程度的危险因素,ROC曲线评估血清miR-497和miR-5787对肺部感染不同严重程度预测价值。结果非感染组患者血清C反应蛋白(C-reactive protein,CRP)、白细胞介素6(interleukin 6,IL-6)和肿瘤坏死因子α(tumor necrosis factor-alpha,TNF-α)低于轻中度感染组和重症感染组,轻中度感染组CRP、IL-6和TNF-α低于重症感染组(P<0.05)。非感染组血清miR-497和miR-5787低于轻中度感染组和重症感染组,轻中度感染组血清miR-497和miR-5787低于重症感染组。血清miR-497与血清CRP、IL-6和TNF-α呈正相关(r=0.756、0.595、0.718,P<0.001);血清miR-5787与血清CRP、IL-6和TNF-α呈正相关(r=0.929、0.827、0.878,P<0.001)。Logistic回归分析,miR-497(OR=1.824,95%CI:1.473~2.258)和miR-5787(OR=2.034,95%CI:1.234~3.353)是重症脑卒中发生肺部感染的影响因素(P<0.05)。ROC结果显示,miR-497诊断的临界值为3.55,其对应的敏感度为69.77%,特异度为71.07%,AUC为0.801(95%CI:0.750~0.852);miR-5787诊断的临界值为10.27,其对应的敏感度为74.42%,特异度为69.81%,AUC为0.760(95%CI:0.707~0.812);回归分析敏感度为86.05%,特异度为83.02%,AUC为0.869(95%CI:0.831~0.907)。结论血清miR-497和miR-5787在重症脑卒中患者中异常高表达,且与肺部感染严重程度呈现正相关,并可应用于预测重症脑卒中肺部感染,值得临床进一步研究并推广。

关键词：脑卒中呼吸道感染信使核糖核酸-497 信使核糖核酸-5787

维普期刊数据库博看期刊

Interactions between a central bubble and a surrounding bubble cluster

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2023年第3期13卷 216-221页

The interaction of multiple bubbles is a complex physical problem.A simplified case of multiple bubbles is studied theoretically with a bubble located at the center of a circular bubble *** bubbles in the cluster are equally spaced and own the same initial conditions as the central *** unified theory for bubble dynamics[35]is applied to model the interaction between the central bubble and the circular bubble *** account for the effect of the propagation time of pressure waves,the emission source of the wave is obtained by interpolating the physical information on the time *** underwater explosion experiment with two bubbles of different scales is used to validate the theoretical *** effect of the bubble cluster with a variation in scale on the pulsation characteristics of the central bubble is studied.

关键词： Bubble dynamics Bubble cluster

高分辨率超声联合血清HCY、GDF-15、GFAP对缺血性脑梗死的诊断价值研究

在线全文

学校读者我要写书评

暂无评论

现代生物医学进展 2024年第6期24卷 1072-1076页

作者：孙楠王肖曲沙施理敏张雯琼首都医科大学附属北京潞河医院超声介入疼痛科北京101100 上海市公共卫生临床中心检验科上海200000

目的:探讨高分辨率超声联合血清同型半胱氨酸(HCY)、生长分化因子15(GDF-15)、神经胶质纤维酸性蛋白(GFAP)对缺血性脑梗死的诊断价值。方法:选择2021年3月-2023年3月本院收治的162例缺血性脑梗死患者作为梗死组,另选取同期138名健康体... 详细信息

目的:探讨高分辨率超声联合血清同型半胱氨酸(HCY)、生长分化因子15(GDF-15)、神经胶质纤维酸性蛋白(GFAP)对缺血性脑梗死的诊断价值。方法:选择2021年3月-2023年3月本院收治的162例缺血性脑梗死患者作为梗死组,另选取同期138名健康体检者作为对照组,所有受试者均行高分辨率超声技术测量颈动脉内膜/中膜厚度(cIT/cMT)和桡动脉内膜/中膜厚度(rIT/rMT),所有受试者均行酶联免疫吸附试验法(EliSA)测定其血清HCY、GDF-15、GFAP水平,比较两组之间各测量参数的差异。通过绘制受试者工作特征曲线(ROC)分析高分辨率超声参数、血清HCY、GDF-15、GFAP水平对缺血性脑梗死的诊断效能。结果:梗死组cIT、rIT、血清HCY、GDF-15、GFAP水平显著高于对照组(P0.05)。与单独诊断相比较,高分辨率超声参数cIT、rIT联合血清HCY、GDF-15、GFAP水平对缺血性脑梗死评估的曲线下面积(AUC)、约登指数、敏感度、特异度最高。结论:高分辨率超声参数cIT、rIT联合血清HCY、GDF-15、GFAP水平对缺血性脑梗死具有更高的诊断价值,有助于指导临床对缺血性脑梗死患者的诊断。

关键词：高分辨率超声 HCY GDF-15 GFAP 缺血性脑梗死诊断价值