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In this study, phononic crystals reducing the earthquake effects will be determined and prototypes will be constructed which can give the opportunity to reduce the effects of seismic waves. Furthermore, test results will be discussed numerically and experimentally. A reasonable structure has been investigated for seismic waves in a low-frequency band by extracting band diagram based on finite element method. The wave propagation is numerically carried out depending on the experimentally obtained mechanical properties of the field. The optimum dimensions and arrangement of the periodic structure have been evaluated by numerical analysis. It is demonstrated that the shielding effect can be realized due to the impedance matching between the ground and seismic metamaterials. Impedance matching is the necessary condition for the maximum interaction of the seismic waves propagating in the field with the structure.

In this study, we investigate acoustic wave propagation in 3 D phononic crystal (PnC) slabs wherein scatterers have different cross sections by using the finite-element method. The PnC consists of scatterers embedded in the host material arranged in a square lattice and honeycomb lattice in different patterns (bathroom and ladybug tiling in Archimedean-like tiling). By determining the eigenmodes and band gaps, complete and accurate band structures and transmission spectra are obtained. Compared to traditional square lattice PnCs, it has been observed that the bands obtained in pattern structures may have some advantages in terms of width and position. It was also shown that the low-frequency response of two Archimedean-like structures was similar with respect to the traditional square lattice.

In this numerical and experimental study, we designed sinusoidal located concrete-based boreholes which are candidate for seismic shielding applications. To attenuate seismic wave transmission in an area, proposed design is created in most dangerous part of seismic frequencies which corresponds 1-15 Hz band. Firstly, transmission loss characteristics of proposed design is obtained numerically, and it is clearly shown that proposed design has multiband blocking capability. Afterwards, total surface displacements were plotted, analysed and explained. Thus, proposed design attenuates seismic wave transmission according to numerical results. Moreover, to support proposed design, various experimental measurements were carried out by using a harmonic vibration source and 14 accelerometers as sensors. Experiments conducted in time domain and obtained results were converted to the frequency domain by fast Fourier transform, and mapping processes were done by interpolation technique. The obtained measured map of the seismic radiation between 5 and 15 Hz bands is given, and a good matching between simulations and experiments has been seen. As obtained numerical and experimental results, the proposed metamaterial structure could be used in seismic shielding applications because of its highly blocking capability of seismic wave transmission.

The goal of the work presented in this investigation is to achieve the efficient parametric interaction of narrow beams (in particular second harmonic generation) using a nonlinear (ferroelectric-LiTaO3) photonic crystal tuned to self-collimation (nondiffractive) regimes. A numerical study of second harmonic generation (SHG) in one-dimensional nonlinear photonic crystals based on a full nonlinear system of equations, implemented by a combination of the method of finite elements and fixed-point iterations, is reported. This model is derived from a nonlinear system of Maxwell’s equations that partly overcomes the known shortcoming of some existing models that rely on the undepleted pump approximation. We derive a general solution of SHG in one-dimensional nonlinear photonic crystals structures. Numerical simulations also show that the conversion efficiency of SHG can be significantly enhanced when the frequencies of the fundamental wave are located at the photonic band edges or are assigned to the designed defect states.

In this report, we present an investigation of the dispersion properties of the phononic crystal in different lattice, geometries for various piezoelectric materials. We study dispersion pr...

In this paper, we investigated the bandgaps of two-dimensional phononic crystals with quasiSierpinski carpet unit cells in a metacomposite based solid–solid phononic crystal. Finite element method was used to analyze the properties of two-dimensional phononic bandgaps (2D PBGs) in a quasi-fractal structure. Two new types of quasi-Sierpinski fractal unit cells whose constituents are homogeneous and isotropic were proposed to obtain larger full bandgaps. The results show that the PBGs of the proposed quasi-Sierpinski fractals are suitable to tune the PBG’s without changing the size of the phonic crystal. The new quasi-Sierpinski fractals also retain the selfsimilarity as in the third-order Sierpinski fractal unit cell. The investigated quasi-fractals can be easily modified to increase the filling fraction of the constituents, which can be effectively used to enlarge existing PBG by preserving degree of self-similarity structure.

In this study, a triangular array of cylindrical holes was shown to function as a local resonator to seismic metamaterials against the vibration generator loading in the geophysics concept. The field test showed that the seismic waves applied to one side of the proposed array interacted with the triangularly arranged holes, resulting in a strong attenuation in two narrow frequency bands. The numerical analysis was carried out using simulations based on the finite element method, which provides optimal dimensions and arrangement at a sub-wavelength scale to achieve maximum attenuation against incoming seismic wave at a very low frequency range. Different band gaps were observed due to interaction of the longitudinal resonance between the cylindrical holes and vertical components of soil response under the applied wave. Experimental analysis was carried out using optimum dimensions and hole arrangements, and a strong attenuation due to impedance matching between soil and seismic metamaterials was shown. It was also observed that, at very low frequencies, the soil response was due to the inverse proportionality between the resonator length and the seismic energy wavelength applied for longitudinal resonance. Two band gaps have been observed around 25–36 Hz as shown in band diagram. The proposed structure exactly prevents the seismic wave propagation at 25 Hz and 36 Hz in accordance with band diagram. Therefore, the proposed system can prevent the seismic waves from attaining the backside of the seismic array. The attenuation was obtained at a level of 0.00125, observed at a 0.0001 source point, measured by a speed sensor located at the back of the seismic metamaterials, with an attenuation rate of 12.5 at 8 Hz.

In this study, the band structure and transmission spectra in multiferroic based Sierpinski-carpet phononic crystal are investigated based on finite element simulation. In order to obtain the band structure of the phononic crystal (PnC), the Floquet periodicity conditions were applied to the sides of unit cell. The square lattice PnC consists of various piezoelectric inclusion in a rubber matrix with circular and triangular cross section.

Temporally periodic photonic crystals develop an ω-k dispersion relation with momentum band gaps. While conventional photonic crystals induce forbidden bands in the frequency spectrum of photons, photonic time crystals create forbidden regions in the momentum spectrum of photons. This effect allows for enhanced control over many optical processes that require both photonic energy and momentum conservations such as nonlinear harmonic generation. The simulation results show that more intensive scatter fields can obtained in photonic space time crystal. Also, we investigate topological phase transitions of photonic time crystals systems.

In the present work the acoustic band structure of a two-dimensional phononic crystal containing an organic ferroelectric (PVDF- polyvinylidene fluoride) and muliferroic material (LiVCuO4) were investigated by the plane-wave-expansion method. A two-dimensional PC with square lattices composed of LiVCuO4 cylindrical rods embedded in the PVDF matrix are studied to find the existence of stop bands for the waves of certain energy. This phononic bandgap - forbidden frequency range - allows sound to be controlled in many useful ways in structures that can act as sonic filters, waveguides or resonant cavities. Phononic band diagram omega = omega(k) for a 2D PC, in which non-dimensional frequencies omega a/2 pi c (c-velocity of wave) were plotted versus the wavevector k along the Gamma-X-M-Gamma path in the square Brillouin zone show four stop bands in the frequency range 0.01-8.0 kHz. The ferroelectric properties of PVDF and unusual properties of multiferroic LiVCuO4 give us the ability to control the wave propagation through the PC in over a wide frequency range.

In the present work, the acoustic band structure of a two-dimensional (2D) phononic crystal containing a multiferroic and liquid were investigated by the plane-wave-expansion method. 2D PnC with triangular and honeycomb lattices composed of LiCu2O4 cylindrical rods embedded in the seawater matrix are studied to find the existence of stop bands for the waves of certain energy. Phononic band diagram ω=ω(k) for a 2D PC, in which nondimensional frequencies ωa/2πc (c-velocity of wave) were plotted versus the wavevector k along the г-X-M-г path in the Brillouin zone show few stop bands in the frequency range between 10 and 110 kHz.

In this study, we investigated band structure of a 2D Phononic Crystal (PnC) which was consist of hollow aluminum cylinders in different media. To validate the finite element predictions, we made a square lattice PnC which has lattice constant a = 14mm, outer radius r1 = 5mm and inner radius r2 = 4mm of cylinders. In our experimental measurement, by using a signal generator software, we sent 100 Hz-20kHz sine signal for 5 seconds duration from speaker to the PnC where placed 1m away from. With the help of a microphone, we recorded the sound in front of the PnC (Pin ) and backside the PnC (Pout ). Then we were converted our recording into frequency domain by standard FFT algorithm, we calculated the Transmission Loss value according to the formula TL = 20* log10 (Pout / Pin ) and obtained the experimental Transmission Loss. After experimental validation, we conducted band structure analysis of different combination of the 2D PnC by finite element method.

Osteosynthesis of femoral neck fractures (FNF) is accompanied by a large percentage of various complications. The aim of this research was to study biomechanical implications arising from the stress and strain distributions by use of new device -perforated H-beam implant. A reference 3D femur model has been developed using digital femur geometry. The stress and deformity characteristics after the application of force were determined by ANSYS, which entails the finite element analysis (FEA) method. This method was used for both the perforated and non-perforated implant models and compared the application of constant strength. Three types of FNF were realized according to the Pauwell classification system. We concluded that, the perforations in the implants make the distribution of strength and pressure homogenous along the whole implant functioning as wave breaker to reduce the pressure on the bone. This contributes to implant stability and the minimization of bone destruction.

3rd Internatiomal Conference on Rheology and Modeling of Materials, IC-RMM 2017 -- 2 October 2017 through 6 October 2017 -- -- 138334, In the present work, the acoustic band structure of a two-dimensional (2D) phononic crystal (PnC) containing composite material were investigated by the finite element method. Two-dimensional PC with triangular and honeycomb lattices composed of composite cylindrical rods are in the air and liquid matrix. The existence of stop bands are investigated for the waves of certain frequency ranges. This phononic band gap - forbidden frequency range - allows sound to be controlled in many useful ways in structures. These structures can be used as sonic filters, waveguides or resonant cavities. Phononic band diagrams ?-?(k) for a 2D PnC were plotted versus the wavevector k along the ?-X-M- ? path in the first Brillouin zone. The calculated phonon dispersion results indicate the existence of full acoustic modes in the proposed structure along the high symmetry points. © 2018 Published under licence by IOP Publishing Ltd.

In wind energy conversion systems, one of the operational problems is the changeability and discontinuity of wind. In most cases, wind speed can fluctuate rapidly. Hence, quality of produced energy becomes an important problem in wind energy conversion plants. Several control techniques have been applied to improve the quality of power generated from wind turbines. Pitch control is the most efficient and popular power control method, especially for variable-speed wind turbines. It is a useful method for power regulation above the rated wind speed. This paper proposes an artificial neural network-based pitch angle controller for wind turbines. In the simulations, a variable-speed wind turbine is modeled, and its operation is observed by using two types of artificial neural network controllers. These are multi-layer perceptrons with back propagation learning algorithm and radial basis function network. It is shown that the power output was successfully regulated during high wind speed, and as a result overloading or outage of the wind turbine was prevented.

In this study the residue levels of the heavy metals, which located in the main substance of the pesticides, in waters were investigated in Mersin Province. For this aim, samples were collected from total 32 unit water sources (river and water canal) near the fields and green houses in four different agricultural regions (Kazanli, Adanalioglu, Homurlu, Kocahasanli) in Mersin Province at three periods: after the sowing period, growing period and harvesting period. Heavy metal (Cu, Mn, Cr, Ni, Mo) level of these samples, which may be caused by pesticides, and some other chemical and physical parameters like pH, salinity and conductivity were analysed. At the end of the study, although pH, salinity and conductivity parameters weren't changed with agricultural chemicals, it was determined that the heavy metal levels were changed up to regions and sampling periods.

This paper presents the design, modeling and finite element model simulation of a micro-electromechanical system based on the ternary ferroelectric compounds and paratellurite. The dynamic behavior of the sensor structure is described by the super position of its dominant vibration mode shapes. The resulting model still considers all the physical domains and is even able to capture nonlinear phenomena, such as the stress stiffening of constraint structures or frequency and stiffening caused by squeezed gas in the sensor cell. Process induced and thermally induced residual stresses and the resulting deformation of the transducer elements are considered. © 2016, © Taylor & Francis Group, LLC.

Purpose: To investigate the influence of crown margin design on the stress distribution and to localize critical sites in maxillary canine under functional loading by using three dimensional finite element analysis. Materials and Methods: The bite force of 100 N, 150 N, and 200 N was applied with an angulation of 45° to the longitudinal axis of tooth. Six models were restored with IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) with a different margin design. With lingual ledge and various thicknesses, three different core ceramics were designed in each model. Result: In the core ceramic, the maximum tensile stresses were found at the labiocervical region. In the veneering ceramic the maximum tensile stresses were found at the area where the force was applied in all models. Conclusion: Shoulder and chamfer margin types are acceptable for all-ceramic rehabilitations. A ledge on the core ceramic at cervical region may affect the strength of all-ceramic crowns.

Chiral metamaterials have been a research area for many researchers due to their polarization rotation properties on electromagnetic waves. However, most of the proposed chiral metamaterials are designed depending on experience or time-consuming inefficient simulations. A method is investigated for designing a chiral metamaterial with a strong and natural chirality admittance by optimizing a grid of metallic pixels through both sides of a dielectric sheet placed perpendicular to the incident wave by using a genetic algorithm (GA) technique based on finite element method solver. The effective medium parameters are obtained by using constitutive equations and S parameters. The proposed methodology is very efficient for designing a chiral metamaterial with the desired effective medium parameters. By using GA-based topology, it is proven that a chiral metamaterial can be designed and manufactured more easily and with a low cost. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

This paper presents the design and modeling of micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT) based by using finite element model (FEM) simulation. The conceptual framework establishes five steps to perform the critical analysis: design a novel structure, define the failure mechanisms under the given conditions, analyze different vibrations, analyze the operation principle, and detect resonance modes. In addition, MEMS failure modes were analyzed under different scenarios and the obtained results discussed. Copyright © Taylor & Francis Group, LLC.

Date of Conference: 9-13 July 2012 This paper present the design and modeling of the micro-electromechanical systems (MEMS) on the ternary ferroelectric compounds (PZT and Ba xSr 1-xTiO 3) based by using finite element model (FEM) simulation. © 2012 IEEE.

Goksu Delta is an important wetland where the Goksu River reaches to sea in the eastern of the town Tasucu-Ice1. The delta is classified as a Wetland of International Importance according to the Ramsar Convention on Wetlands of International Importance. The amount of fertilizers used in this area was 7200 tons in 2006. These pollutants affect the surface and groundwater quality negatively. The intensively used fertilizers and pesticides contain not only N- and P compounds but also some heavy metals. The contents of all pollutants in surface waters were determined for four different seasons between 2006 and 2008 and with these data a Geographic Information System (GIS) has been constructed by using Map Info. From the photometric heavy metal analysis, it is inferred that the excess concentration of Fe, Ni, Mn, Mo and Cu at some locations is the cause of undesirable quality for drinking purposes. The source of excess concentration of various heavy metals is the agricultural activities and fertilizers. It is determined that in all periods between 2006 and 2008 the heavy metals and other pollutants in the fertilizers and pesticides transported easily to river water with irrigation return flow. The organic pollutants, including COD, BOD, NH(3) and NO(3) followed the sharply increasing trends from Silifke city to Mediterranean Sea. The water quality of Goksu River is modeled and determined that the waste water discharge of 10,700 m(3)/day from Silifke city does not create a serious problem because of the high amount of flow rate of Goksu River.

In a lossy media, anisotropic chiral metamaterial (MTM) structures with normal incidence asymmetric transmission of linearly polarized electromagnetic (EM) waves are investigated and analyzed in both microwave and terahertz frequency regimes. The proposed lossy structures are used to perform dynamic polarization rota- tion and consist of square-shaped resonators with gaps on both sides of dielectric substrates with a certain degree of rotation. Asymmetric transmission of a linearly polarized EM wave through the chiral MTMs is realized by experimental and numerical studies. The dynamic structures are adjustable via various parameters to be tuned for any desired frequency regimes. From the obtained results, the suggested structure can be used to design new polarization control devices for desired frequency regimes. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.53.7.075109)

Adsorption of copper (II) ions to untreated peanut hulls and untreated Pinus brutia sawdust was investigated as a function of the contact time, amount of adsorbents, initial pH, temperature and initial metal ion concentration. Adsorption efficiency was increased by increasing contact time, amount of adsorbents and decreasing initial metal ion concentration. The optimum adsorption conditions were obtained at pH 5.0. Experimental results indicate that peanut hulls are a more effective adsorbent than Pinus brutia sawdust for the removal of Cu (II) from aqueous solutions. The isothermal data of peanut hulls could be well described by the Langmuir and Freundlich equations.