Romanian Journal of Acoustics and Vibration <p>The&nbsp;<strong>Romanian Journal of Acoustics and Vibration (Print ISSN 1584-7284;&nbsp; Online ISSN 2602-0351)</strong> is the referred journal of the Romanian Society of Acoustics (<strong>SRA</strong>).</p> Romanian Society of Acoustics en-US Romanian Journal of Acoustics and Vibration 1584-7284 <h2 id="Author-rights">Journal author rights</h2> <p>In order for Romanian Journal of Acoustics and Vibration to publish and disseminate research articles, we need publishing rights. This is determined by a publishing agreement between the author and Romanian Journal of Acoustics and Vibration. This agreement deals with the transfer or license of the copyright to Romanian Journal of Acoustics and Vibration and authors retain significant rights to use and share their own published articles. Romanian Journal of Acoustics and Vibration supports the need for authors to share, disseminate and maximize the impact of their research and these rights, in Romanian Journal of Acoustics and Vibration proprietary are defined below:</p> <p><strong>For subscription articles:</strong></p> <p>Authors transfer copyright to the publisher as part of a journal publishing agreement, but have the right to: Share their article for personal use (manuscript version); retain patent, trademark and other intellectual property rights (including research data); proper attribution and credit for the published work.</p> <p><strong>For open access articles</strong>:</p> <p>Authors sign an exclusive license agreement, where authors have copyright but license exclusive rights in their article to the publisher. In this case authors have the right to: share their article in the same ways permitted to third parties under the relevant user license; retain patent, trademark and other intellectual property rights (including research data); proper attribution and credit for the published work.</p> <h2 id="Elsevier-rights">Rights granted to Romanian Journal of Acoustics and Vibration</h2> <p>For both subscription and open access articles, published in proprietary titles, Romanian Journal of Acoustics and Vibration is granted the following rights:</p> <p>- The exclusive right to publish and distribute an article, and to grant rights to others, including for commercial purposes;</p> <p>- For open access articles, Romanian Journal of Acoustics and Vibration will apply the relevant third party user licence (Open access licencses) where Romanian Journal of Acoustics and Vibration publishes the article on its online platforms;</p> <p>- The right to provide the article in all forms and media so the article can be used on the latest technology even after publication;</p> <p>- The authority to enforce the rights in the article, on behalf of an author, against third parties, for example in the case of plagiarism or copyright infringement.</p> THE PERFORMANCES IN ACOUSTICS AND VIBRATION ENGINEERING <p>The evolution of the fields of industry, construction and energy has imposed performance requirements at a predictable and measurable level according to the normative reference documents<br>or the technical specifications of the manufacturer.</p> Polidor BRATU ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 2 2 A New Model for Milling Circular Work-pieces <p>In this paper we present a non-linear model for the investigation of the milling of circular work-pieces. Some hypotheses are used in this model including the non-variation of the direction of the cutting force in function of the engagement of the teeth. The model has four degrees of freedom. The non-linearity has as main causes the variation of the depth of cut and the expression of the components of the cutting forces in function of the depth of cut. Details of the integration of the non-linear system are also provided. A numerical example highlights the theory.</p> Elena-Larisa PREDEL Nicolae–Doru STANESCU Nicolae PANDREA ##submission.copyrightStatement## 2021-06-07 2021-06-07 18 1 3 8 Designing Quasi-harmonic Circular Membranes with Different Densities on Angular Sectors <p>We develop a mathematical method to design new circular drum membranes vibrating with maximal harmonicity. The membranes considered have different areal mass density, first over two sectors of complementary central angles, and second over <em>N</em> sectors of the same central angle. We exemplify the method with membranes having two or three different densities.</p> Freddy KASONGO NKOMBE WA KATEBA Ahcène BRAHMI Claude GAUTHIER ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 9 17 A Mathematical Method for Harmonizing the Vibrations of Compound Cymbals <p style="text-align: justify; margin: 0cm 1.0cm .0001pt 1.0cm;"><span style="font-size: 10.0pt;" lang="EN-US">Cymbal sounds are generally inharmonic. Using the property that their most energetic vibration modes are the same as those of thin circular plates, we develop a mathematical method to determine new configurations of compound cymbals made up of a centered disk and a ring around it that would vibrate with maximum harmonicity. We exemplify the method with plates made of aluminum and copper. </span></p> Yassine SABIR Ahcène BRAHMI Claude GAUTHIER ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 18 25 Analytical And Finite Element Studies on Free Vibration of Aluminum Alloy Plate and Control Passive with Damping Orthotropic Patches <p>This paper presents studies made on fundamental flexural frequencies of isotropic alloy aluminum rectangular thin plate with various boundary conditions. The first four vibration mode and corresponding frequencies and mode shapes of this plate were obtained by using analytical method, based on Rayleigh-Ritz energy approach and finite element method (FEM) by using ABAQUS code. The convergency and accuracy of the numerical solution was examined. A comparison was made between the analytical values and the finite element solution. The effect of geometrical parameters on natural vibrations of the isotropic rectangular plate was investigated. The values of frequency parameter of the plate having different (length/width) ratios in case of (a/b³1) were studied. The results obtained by the analytical approach are in good agreement with the FE solutions. Also, the paper presents simulations results of testing of the plate with passive vibration control realized through patches bonded to the plate.</p> Samir DEGHBOUDJ Wafia BOUKHEDENA ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 26 35 Generalized Differential Quadrature Method for Studying the Out off Plane Vibrations of Curved Pipes Conveying Fluid <p>A curved pipe bent in the arc of a circle conveying fluid is investigated. The flowing fluid is considered as a non-compressible and heavy. The considered pipe is assumed cantilevered at its both ends. The Generalized Differential Quadrature Method is employed to investigate the dynamic out off plane stability of the pipe. The obtained numerical results show the dependence of the critical fluid velocity on the maximal central angle of the pipe.</p> Dimitar LOLOV Svetlana LILKOVA-MARKOVA ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 36 39 Improving Speech Intelligibility in A High School Classroom Using Sound Absorbing Panels <p>Acoustic comfort has a huge impact on teachers’ health and students’ productivity. A good acoustic environment can change the child’s perception of the teacher. To obtain a good acoustic environment for a school classroom, the background noise and the reverberation time should be as low as possible. Thus, the aim of this investigation is to determine the reverberation time before and after applying sound absorbing materials in a classroom situated in a college from Bucharest. Further on, the measurements were compared with the results obtained from the reverberation time formulas. The speech transmission index was determined based on the reverberation time to highlight how the occupants perceive the classroom from the acoustical point of view. Important issues were discovered in obtaining the optimal reverberation time in schools.</p> Alexandra ENE Tiberiu CATALINA ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 40 45 A Cost Function to Assess Cracks in Simply Supported Beams with Artificial Intelligence <p>In this paper, we propose a model for detecting transverse cracks in simply supported beams, which can be part of more complex structural systems. The relative frequency shifts of the structure are considered a basis for damage identification. An original method developed by the authors is employed to evaluate the required modal parameters. A multi-stage optimization approach based on the rigidity loss suffered by the affected structure is employed to accurately recognize the locations of potential cracks. The outcome presented in this research shows the computational ability of the proposed model to indicate the presence and location of damages in beam-like structures.</p> Cristian TUFISI Nicoleta GILLICH Mario ARDELJAN Rusalin Lucian PAUN Gilbert-Rainer GILLICH ##submission.copyrightStatement## 2021-07-22 2021-07-22 18 1 46 52