@article { author = {Beigzadeh, Borhan and Belali Koochesfahani, Mojtaba}, title = {Classification of Iranian traditional musical modes (DASTGÄH) with artificial neural network}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {107-118}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.20515}, abstract = {The concept of Iranian traditional musical modes, namely DASTGÄH, is the basis for the traditional music system. The concept introduces seven DASTGÄHs. It is not an easy process to distinguish these modes and such practice is commonly performed by an experienced person in this field. Apparently, applying artificial intelligence to do such classification requires a combination of the basic information in the field of traditional music with mathematical concepts and knowledge. In this paper, it has been shown that it is possible to classify the Iranian traditional musical modes (DASTGÄH) with acceptable errors. The seven Iranian musical modes including SHÖR, HOMÄYÖN, SEGÄH, CHEHÄRGÄH, MÄHÖR, NAVÄ and RÄST-PANJGÄH are studied for the two musical instruments NEY and Violin as well as for a vocal song. For the purpose of classification, a multilayer perceptron neural network with supervised learning method is used. Inputs to the neural network include the top twenty peaks from the frequency spectrum of each musical piece belonging to the three aforementioned categories. The results indicate that the trained neural networks could distinguish the DASTGÄH of test tracks with accuracy around 65% for NEY, 72% for violin and 56% for vocal song.}, keywords = {Iranian traditional musical modes (DASTGÄH),Classification,Artificial neural network,Feature Extraction}, url = {https://tava.isav.ir/article_20515.html}, eprint = {https://tava.isav.ir/article_20515_53d7e13e6294418199c045a736444f9b.pdf} } @article { author = {Mokhtari, Ali and Sarvestan, Vahid and Mirdamadi, Hamid Reza}, title = {Spectrally formulated finite element for vibration analysis of an Euler-Bernoulli beam on Pasternak foundation}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {119-132}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.20910}, abstract = {  In this article, vibration analysis of an Euler-Bernoulli beam resting on a Pasternak-type foundation is studied. The governing equation is solved by using a spectral finite element model (SFEM). The solution involves calculating wave and time responses of the beam. The Fast Fourier Transform function is used for temporal discretization of the governing partial differential equation into a set of ordinary differential equations. Then, the interpolating function for an element is derived from the exact solution of governing differential equation in the frequency domain. Inverse Fourier Transform is performed to rebuild the solution in the time domain. The foremost advantages of the SFEM are enormous high accuracy, smallness of the problem size and the degrees of freedom, low computational cost and high efficiency to deal with dynamic problems and digitized data. Moreover, it is very easy to execute the inverse problems by using this method. The influences of foundation stiffness, shear layer stiffness and axial tensile (or compressive) forces on the dynamic characteristic and divergence instability of the beam are investigated. The accuracy of the present SFEM is validated by comparing its results with those of classical finite element method (FEM). The results show the ascendency of SFEM with respect to FEM in reducing elements and computational effort, concurrently increasing the numerical accuracy.  }, keywords = {Foundation stiffness,Shear layer stiffness,Spectral finite element model,Divergence instability,Wave domain analysis}, url = {https://tava.isav.ir/article_20910.html}, eprint = {https://tava.isav.ir/article_20910_763d5c4dd7195f9afe7b29f1a2366b0e.pdf} } @article { author = {Malakooti, Mohammad Hossein and Ahmadian, Hamid and Jalali, Hassan}, title = {Adhesive joint modeling using compatible element formulation}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {133-144}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.21151}, abstract = {The use of structural adhesives in automotive structures has been increased recently for their role in noise, vibration and harshness (NVH). Therefore, the dynamic behavior of structures containing bonded joints has become an area with numerous investigations over the past decades. Development of accurate formulations capable of representing adhesively bonded joint dynamics is a step forward in constructing the numerical models for one of the most useful kinds of joints in industry. Analysis of the adhesive layer between the two parts requires special assumptions which leads to using nonlinear and three dimensional models. Obtaining shape functions for an adhesive element by using finite element (F.E.) theory is a complicated and difficult task to do. The complexity is increased when it is assumed that the adhesive element is compatible with the plate element. In this paper, a new finite element formulation is developed for the adhesive layer which does not rely on shape functions and is compatible with the plate element. The accuracy of the proposed element is evaluated by using numerical and experimental results.}, keywords = {finite element method,Adhesively bonded joints,Natural frequencies}, url = {https://tava.isav.ir/article_21151.html}, eprint = {https://tava.isav.ir/article_21151_525d566df4f58b6d73a30ba248518d90.pdf} } @article { author = {Yazdanian, Mohsen and Razavi, Vahid and Mashal, Mahmoud}, title = {Study on the dynamic behavior of cylindrical steel liquid storage tanks using finite element method}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {145-166}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.21833}, abstract = {Dynamic behavior of ground supported cylindrical storage tanks (CST) is of crucial importance because of its applications in industrial complexes. Seismic behavior of tanks is greatly affected by the height to diameter ratio, fluid height and fluid type. Five CSTs with different height to diameter ratios, three CSTs with the same height and diameters but various fluid heights and one CST with two different fluid types are selected to determine the effect of height to diameter ratio, fluid heights, and fluid type on the seismic behavior of the tanks respectively. Static, modal, response spectrum, and time history analyses are used in this study for the selected CSTs using ANSYS finite element software. In the time history analysis method, the Tabas, Kobe and Cape Mendocino earthquake records have been utilized on the first five CSTs to ascertain the effect of height to diameter ratio and the Tabas earthquake record is used for the rest of CSTs. Results show that an increase in fluid height lead to a corresponding increase in the base shear. Based on observations, 100 percent increase in the diameter showed 63 percent increase in sloshing under the response spectrum and 70 percent under time history analyses. Based on static and response spectrum analyses, the highest values of displacements are obtained at the lowest part of the tanks, while in time history analysis, the highest is obtained at the top of the tanks. All analyses showed that the maximum stress occurred at the height of 1 to 2 meter from the bottom of the tanks.}, keywords = {CSTs,Height,Diameter,Earthquake,Time history}, url = {https://tava.isav.ir/article_21833.html}, eprint = {https://tava.isav.ir/article_21833_8712f68346ba93893c6f9ec323778be9.pdf} } @article { author = {Eskandarzade, Mehdi and Masoumi, Abolfazl and Faraji, Ghader}, title = {Numerical and analytical investigation of an ultrasonic assisted ECAP process}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {167-184}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.22472}, abstract = {One of the great challenges in the processing of materials using Equal Channel Angular Pressing (ECAP) is the high forming forces required to produce large shear deformation in the material. Researchers show that the friction forces between the die and the sample constitute a great part of the total forming forces. Recently, ultrasonic vibrations are successfully implemented into the ECAP process with the aim of reducing the friction forces. However, there is still need to optimize the parameters of ultrasonic vibrations in the ECAP process using numerical methods. FE simulation of the ultrasonic assisted ECAP process is very time-consuming and during simulation, the constant ram speed has interaction with the vibration speed. A virtual increase in the ram speed for simulation of ultrasonic assisted ECAP process will affect the results. By using Coulomb and Dahl friction models, it is analytically shown how vibration speed and constant ram speed interact with each other during FE simulation. The results clearly suggest against using virtually higher speeds in numerical modelling of the vibrated ECAP process. The conclusion is reached through comparing several simulations, as well as an analytical formulation, with experimental data from literature. The required friction coefficient values to be used in FE simulation at high contact forces are measured experimentally. An alternative strategy is then offered to speed up FE simulation of the vibrated ECAP process without the need for a virtual increase in the ram speed. The proposed strategy can increase the simulation speed of the ultrasonic assisted ECAP process up to ten times  }, keywords = {ECAP process,Ultrasonic vibrations,Forming forces,Friction}, url = {https://tava.isav.ir/article_22472.html}, eprint = {https://tava.isav.ir/article_22472_7e49256143bfa1637069e819d0e35bd9.pdf} } @article { author = {Samadiyeh, Hossein and Khajavi, Reza}, title = {MPI- and CUDA- implementations of modal finite difference method for P-SV wave propagation modeling}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {2}, number = {2}, pages = {185-202}, year = {2016}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2016.45442.1052}, abstract = {Among different discretization approaches, Finite Difference Method (FDM) is widely used for acoustic and elastic full-wave form modeling. An inevitable deficit of the technique, however, is its sever requirement to computational resources. A promising solution is parallelization, where the problem is broken into several segments, and the calculations are distributed over different processors. For the present FD routines, however, such parallelization technique inevitably needs domain-decomposition and inter-core data exchange, due to the coupling of the governing equations. In this study, a new FD-based procedure for seismic wave modeling, named as ‘Modal Finite Difference Method (MFDM)” is introduced, which deals with the simulation in the decoupled modal space; thus, neither domain-decomposition nor inter-core data exchange is anymore required, which greatly simplifies parallelization for both MPI- and CUDA implementations over CPUs and GPUs. With MFDM, it is also possible to simply cut off less-significant modes and run the routine for just the important ones, which will effectively reduce computation and storage costs. The efficiency of the proposed MFDM is shown by some numerical examples.}, keywords = {Finite difference method,Graphics Processing Unit (GPU),Message Passing Interface (MPI),Modal,wave propagation}, url = {https://tava.isav.ir/article_23353.html}, eprint = {https://tava.isav.ir/article_23353_9b1576299b611007623e4697e6a2b320.pdf} }