Quarterly Journal of Mechanics and Applied Mathematics最新文献_第3页

Equilibrium of Two Rods in Contact Under Pressure 压力作用下两杆接触的平衡

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-11-01 DOI: 10.1093/QJMAM/HBAA016

S. Turzi, M. Zoppello, Davide Carlo Ambrosi

{"title":"Equilibrium of Two Rods in Contact Under Pressure","authors":"S. Turzi, M. Zoppello, Davide Carlo Ambrosi","doi":"10.1093/QJMAM/HBAA016","DOIUrl":"https://doi.org/10.1093/QJMAM/HBAA016","url":null,"abstract":"\u0000 We study the equilibrium of a mechanical system composed by two rods that bend under the action of a pressure difference; they have one fixed endpoint and are partially in contact. This system can be viewed as a bi-valve made by two smooth leaflets that lean on each other. We obtain the balance equations of the mechanical system exploiting the principle of virtual work and the contact point is identified by a jump condition. The problem can be simplified exploiting a first integral. In the case of quadratic energy, another first integral exists: its peculiarity is discussed and a further reduction of the equations is carried out. Numerical integration of the differential system shows how the shape of the beams and the position of the contact point depend on the applied pressure. For small pressure, an asymptotic expansion in a small parameter allows us to find an approximate solutions of polynomial form which is in surprisingly good agreement with the solution of the original system of equations, even beyond the expected range of validity. Finally, the asymptotics predicts a value of the pressure that separates the contact from the no-contact regime of the beams that compares very well with the one numerically evaluated.","PeriodicalId":56087,"journal":{"name":"Quarterly Journal of Mechanics and Applied Mathematics","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/QJMAM/HBAA016","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61233605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Calculation of a key function in the asymptotic description of moving contact lines 移动接触线渐近描述中一个关键函数的计算

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-10-10 DOI: 10.1093/qjmam/hbaa012

J. Scott

{"title":"Calculation of a key function in the asymptotic description of moving contact lines","authors":"J. Scott","doi":"10.1093/qjmam/hbaa012","DOIUrl":"https://doi.org/10.1093/qjmam/hbaa012","url":null,"abstract":"\u0000 An important element of the asymptotic description of flows having a moving liquid/gas interface which intersects a solid boundary is a function denoted $Q_i left( alpha right)$ by Hocking and Rivers (The spreading of a drop by capillary action, J. Fluid Mech. 121 (1982) 425–442), where $0 < alpha < pi$ is the contact angle of the interface with the wall. $Q_i left( alpha right)$ arises from matching of the inner and intermediate asymptotic regions introduced by those authors and is required in applications of the asymptotic theory. This article describes a new numerical method for the calculation of $Q_i left( alpha right)$, which, because it explicitly allows for the logarithmic singularity in the kernel of the governing integral equation and uses quadratic interpolation of the non-singular factor in the integrand, is more accurate than that employed by Hocking and Rivers. Nonetheless, our results show good agreement with theirs, with, however, noticeable departures near $alpha = pi $. We also discuss the limiting cases $alpha to 0$ and $alpha to pi $. The leading-order terms of $Q_i left( alpha right)$ in both limits are in accord with the analysis of Hocking (A moving fluid interface. Part 2. The removal of the force singularity by a slip flow, J. Fluid Mech. 79 (1977) 209–229). The next-order terms are also considered. Hocking did not go beyond leading order for $alpha to 0$, and we believe his results for the next order as $alpha to pi $ to be incorrect. Numerically, we find that the next-order terms are $Oleft( {alpha ^2} right)$ for $alpha to 0$ and $Oleft( 1 right)$ as $alpha to pi $. The latter result agrees with Hocking, but the value of the $Oleft( 1 right)$ constant does not. It is hoped that giving details of the numerical method and more precise information, both numerical and in terms of its limiting behaviour, concerning $Q_i left( alpha right)$ will help those wanting to use the asymptotic theory of contact-line dynamics in future theoretical and numerical work.","PeriodicalId":56087,"journal":{"name":"Quarterly Journal of Mechanics and Applied Mathematics","volume":" ","pages":""},"PeriodicalIF":0.9,"publicationDate":"2020-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/qjmam/hbaa012","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44172402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Capillary-gravity waves on the interface of two dielectric fluid layers under normal electric fields 法向电场作用下两层介质流体界面上的毛细管重力波

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-08-01 DOI: 10.1093/qjmam/hbaa009

A. Doak, T. Gao, J. Vanden-Broeck, Josh Kandola

引用次数: 6

A Singular Nonlinear History-Dependent Cohesive Zone Model: Is it Possible? 一个奇异的非线性历史相关粘性区模型：它可能吗？

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-08-01 DOI: 10.1093/qjmam/hbaa007

I. Argatov

引用次数: 0

Four solutions of a two-cylinder electrostatic problem, and identities resulting from their equivalence 两圆柱静电问题的四个解，以及由它们的等价性所产生的恒等式

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-08-01 DOI: 10.1093/qjmam/hbaa010

J. Lekner

引用次数: 1

The Legendre–Hadamard condition in Cosserat elasticity theory Cosserat弹性理论中的Legendre–Hadamard条件

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2020-06-02 DOI: 10.1093/QJMAM/HBAA013

M. Shirani, D. Steigmann, P. Neff

引用次数: 8

The use of e-cigarettes among university students in Malaysia. 马来西亚大学生使用电子烟的情况。

IF 2.2 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2018-12-10 eCollection Date: 2018-01-01 DOI: 10.18332/tid/99539

Sharifa Ezat Wan Puteh, Roslina Abdul Manap, Tidi Maharani Hassan, Izzah Syazwani Ahmad, Idayu Badilla Idris, Fariza Md Sham, Andrea Ban Yu Lin, Chun Ian Soo, Rashidi Mohamed Pakri Mohamed, Ahmad Irdha Mokhtar, Hazli Zakaria, Jing Lee, Amer Siddiq Amer Nordin, Suthahar Ariaratnam, Mohd Zaliman Mohd Yusoff

{"title":"The use of e-cigarettes among university students in Malaysia.","authors":"Sharifa Ezat Wan Puteh, Roslina Abdul Manap, Tidi Maharani Hassan, Izzah Syazwani Ahmad, Idayu Badilla Idris, Fariza Md Sham, Andrea Ban Yu Lin, Chun Ian Soo, Rashidi Mohamed Pakri Mohamed, Ahmad Irdha Mokhtar, Hazli Zakaria, Jing Lee, Amer Siddiq Amer Nordin, Suthahar Ariaratnam, Mohd Zaliman Mohd Yusoff","doi":"10.18332/tid/99539","DOIUrl":"10.18332/tid/99539","url":null,"abstract":"Introduction: E-cigarette use is an emerging phenomenon with increasing recognition and acceptance globally. This study aims to create a profile of e-cigarette users among university students in Malaysia.Methods: The study was conducted using a cross-sectional research involving six universities in Malaysia. A semi-structured questionnaire was distributed to 1302 randomly selected students, who either smoked cigarettes and/or e-cigarettes. The 2011 version of Global Adult Tobacco Surveys (GATS) tool was used to record the respondents' sociodemographic data.Results: The study revealed that 74.9% of the respondents smoked e-cigarettes; 40.3% used both cigarettes and e-cigarettes (dual users), and 34.5% were exclusive e-cigarette users. The exclusive use of e-cigarettes was related to gender (OR=0.18, 95% CI: 0.09-0.39). Also, male respondents were the majority users (95%). Of the respondents, 75.2 % were Malays, 98.0% single and most believed they have no health problems (92.1%). Further findings revealed the occurrence of adverse effects, dizziness 14.4%, cough 14.1%, and headaches 12.4%. Overall, 57.8% of the respondents used e-cigarettes as a smoking cessation tool, while others consider e-cigarettes a self-image enhancing tool or as part of social activities.Conclusions: Further research on the use of e-cigarettes should be conducted on a large number of respondents in other settings to augment the findings of this study, and also guide policy making on and prevention practice of e-cigarette use, among the general student population in Malaysia.","PeriodicalId":56087,"journal":{"name":"Quarterly Journal of Mechanics and Applied Mathematics","volume":"11 1","pages":"57"},"PeriodicalIF":2.2,"publicationDate":"2018-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6659562/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83244506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Image conditions for polar and cylindrical coordinate separation-of-variables acoustic multiple scattering models with perfectly reflecting flat boundaries 完美反射平面边界的极坐标和柱坐标变量分离声学多重散射模型的成像条件

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2018-08-01 DOI: 10.1093/QJMAM/HBY005

Ho-Chul Shin

{"title":"Image conditions for polar and cylindrical coordinate separation-of-variables acoustic multiple scattering models with perfectly reflecting flat boundaries","authors":"Ho-Chul Shin","doi":"10.1093/QJMAM/HBY005","DOIUrl":"https://doi.org/10.1093/QJMAM/HBY005","url":null,"abstract":"This article addresses efficient implementation of the method of images for acoustic multiple scattering models (MSM) with perfectly reflecting flat boundaries. Time-harmonic problems are first solved in the polar coordinate system for circular scatterers; then the models are extended to the cylindrical coordinate system with (semi-)infinitely long circular cylinders. The MSM in this article is based on the method of separation of variables and Graf’s addition theorem. Derivations are provided for ‘image conditions’ which relate the unknown coefficients of outgoing waves from image scatterers with those of real counterparts. The method of images is applied to wedge-shaped domains with apex angles of \u0000π/n rad for a positive integer n. Image conditions make the MSM numerically more efficient: the system of linear equations for unknown coefficients is formulated 2n times faster; its memory requirements are reduced by 4n2 times for direct solvers. The proposed model is applied to a benchmark wedge in ocean environment with n=64. Good agreement is observed between the MSM with image conditions and the boundary element method. Furthermore, half- and quarter-space measurements in an anechoic chamber are in accordance with the correct use of image conditions. Incorrect image conditions reported elsewhere for polar coordinates are also discussed.","PeriodicalId":56087,"journal":{"name":"Quarterly Journal of Mechanics and Applied Mathematics","volume":"71 1","pages":"273-296"},"PeriodicalIF":0.9,"publicationDate":"2018-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/QJMAM/HBY005","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44707800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Scattering of In-plane Elastic Waves by an Anisotropic Circle 各向异性圆对平面内弹性波的散射

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2018-05-01 DOI: 10.1093/QJMAM/HBX029

A. Boström

引用次数: 10

Subsonic Frictional Cavitating Penetration of a Thin Rigid Body Into an Elastic Medium 弹性介质中薄刚体的亚音速摩擦空化穿透

IF 0.9 4区工程技术

Quarterly Journal of Mechanics and Applied Mathematics Pub Date : 2018-05-01 DOI: 10.1093/QJMAM/HBY003

Y. Antipov

{"title":"Subsonic Frictional Cavitating Penetration of a Thin Rigid Body Into an Elastic Medium","authors":"Y. Antipov","doi":"10.1093/QJMAM/HBY003","DOIUrl":"https://doi.org/10.1093/QJMAM/HBY003","url":null,"abstract":"Two model problems of plane elasticity on subsonic steady-state motion of a thin rigid body in an elastic medium are analyzed. Both models concern a finite body symmetric with respect to the plane of motion and assume that the body contacts with the surrounding medium according to the Coulomb friction law. The body, while moves, leaves a trailing semi-infinite cracklike cavity moving at the body speed. The first model also assumes that ahead of the body a finite crack-like cavity is formed, and it is moving at the same speed. The second model does not admit the existence of this finite cavity. Both problems reduce to two sequently solved Riemann–Hilbert problems with piece-wise constant coefficients. Analysis of the solution to these problems obtained by quadratures reveals that the normal and tangential traction components and the normal velocity are continuous for any point of separation of the medium from the body. A criterion for the separation point based on the analysis of the sign of the normal traction component is proposed. Numerical results for the length of the fore crack (the first model), the normal traction and the resistance force for some ogive-nose penetrators are reported.","PeriodicalId":56087,"journal":{"name":"Quarterly Journal of Mechanics and Applied Mathematics","volume":"71 1","pages":"221-243"},"PeriodicalIF":0.9,"publicationDate":"2018-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1093/QJMAM/HBY003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47065754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3