Browsing by Publisher "Association for Scientific Research"
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Item Vibrations of a stretched beam with non-ideal boundary conditions(Association for Scientific Research, 2001) Pakdemirli M.; Boyaci H.A simply supported Euler-Bernoulli beam with immovable end conditions is considered. The concept of non-ideal boundary conditions is applied to the beam problem. In accordance, the boundaries are assumed to allow small deflections. Approximate analytical solution of the problem is found using the method of multiple scales, a perturbation technique.Item Linear transverse vibrations of a simply supported beam carrying concentrated masses(Association for Scientific Research, 2001) Özkaya E.Linear transverse vibrations of an Euler-Bernoulli beam are considered. The beam carries masses and is simply supported at both ends. The equations of motion are obtained and solved. Linear frequency equations are obtained. Natural frequencies are calculated for different number of masses, mass ratios, and mass locations.Item Group classification and some similarity solutions for a nonlinear filtration equation(Association for Scientific Research, 2002) Pakdemirli M.A nonlinear filtration equation in which the filter coefficient is an arbitrary function of the specific deposit is considered. Lie Group theory is applied to the coupled system of partial differential equations. Group classification is performed with respect to the arbitrary filter coefficient. Some similarity solutions are constructed using the symmetries.Item Vibrations of a simply supported beam with a non-ideal support at an intermediate point(Association for Scientific Research, 2003) Pakdemirli M.; Boyaci H.A simply supported Euler-Bernoulli beam with an intermediate support is considered. The concept of non-ideal boundary conditions is applied to the beam problem. In accordance, the intermediate support is assumed to allow small deflections. Approximate analytical solution of the problem is found using the Method of Multiple Scales, a perturbation technique. Ideal and non-ideal frequency response curves are contrasted.Item Prediction of ratio of mineral substitution in the production of low-clinker factored cement by artificial neural network(Association for Scientific Research, 2003) Canpolat F.; Yilmaz K.; Ata R.; Köse M.M.Artificial Neural Networks (ANN) has been widely used to solve some of the problems in science and engineering, which requires experimental analysis. Use of ANN in civil engineering applications started in late eighties. One of the important features of the ANN is its ability to learn from experience and examples and then to adapt with changing situations. Engineers often deal with incomplete and noisy data, which is one of the areas where ANN can easily be applied. Dealing with incomplete and noisy data is the conceptual stage of the design process. This paper shows practical guidelines for designing ANN for civil engineering applications. ANN is in cement industry: in the production of low-clinker factored cement, and in the derivation of composition of natural and artificial puzzolans in the production of high performance cement and concrete. By using ANN, a study to find out the optimum ratio of substitution and compression strengths was carried out.Item Cutting tool condition monitoring using surface texture via neural network(Association for Scientific Research, 2003) Saģlam H.; Kaçar H.For defining surface finish and monitoring tool wear is essential for optimisation of machining parameters and performing automated manufacturing systems. There is very close relationship between tool wear and surface finish parameters as surface roughness (Ra) and maximum depth of profile (Rt). The machined surface reflects the rate of tool wear and the plot of surface provides reliable information about tool condition. In this paper an approach for estimating Ra and Rt in milling process using the artificial neural networks is proposed. Feed-forward multi-layered neural networks, trained by the back-propagation algorithm are used. In training phase seven input parameters (v, f, d, Fx, Fy, Fz and Vb) and two output parameters are used and the network architecture is as 7×6×6×6×2. It was found that the ANN results are very close to the experimental results. The developed model can be used to define the quality of surface finish in tool condition monitoring systems.Item The investigation of the log(ft) values for the allowed Gamow-Teller transitions of some deformed nuclei(Association for Scientific Research, 2004) Selam C.; Babacan T.; Aygör H.A.; Bircan H.; Küçükbursa A.; Maraş I.The log(ft) values of allowed β± decay between odd-A nuclei for 125≤A≤180 mass region are investigated. Single particle energies and wave functions are calculated by making use of a deformed Woods-Saxon potential. The calculations are performed in the framework of proton-neutron quasi particle random phase approximation (QRPA) including the schematic residual spin-isospin interaction among the nucleons in the particle hole channel. The calculations indicated that the results obtained through using the ΧGT=5.2/A0.7 are more in agreement with experimental observations.Item Presentations for regular unbranched Cp -coverings of a Klein Bottle(Association for Scientific Research, 2004) Kazaz M.[No abstract available]Item Freeness conditions of tensors and coproducts of groups(Association for Scientific Research, 2004) Mutlu A.Using a free simplicial group with given a CW-basis, we give an alternative description of the top group of the free square complex and 2-crossed complex of groups on 2-construction data in terms of tensors and coproducts of crossed module of groups. Therefore the functors are given between these categorical constructions.Item Determination of hardness of pre-aged AA 6063 aluminum alloy by means of artificial neural networks method(Association for Scientific Research, 2004) Durmuş H.; Ünlü B.S.; Meriç C.A lot of experiments must be conducted in order to find an appropriate technology for the calculation of strength of the materials, which wastes both man power and money. For this reason artificial neural networks (ANNs) have been used to search the optimum technology proper for pre-aged AA 6063 aluminum alloy. In this study, ANNs were used to compare experimental results and test data were used for teaching of the ANNs. This paper examines the changes in the hardness of AA 6063 alloys when heat treated at different pre-aging treatments. The alloy was solution treated for 1 hour at 525±3 °C and quenched in water. After quenching, samples were subjected to five different pre-aging times, 2 hours, 1 day, 3 days, 7 days. On the other hand, some specimens were not pre-aged. Artificial age temperatures were selected as 160 °C and 180 °C. The hardness values of these under-aged alloys were measured. When the pre-aging time was 7 days, the hardness values of the specimens increased. An excellent correlation was found between experimental hardness results and ANNs hardness results.Item A simple method for calculating the number of atoms in ion implanted samples from the RBS yield(Association for Scientific Research, 2004) Can N.; Belik H.G.A simple method that computes the number of atoms in implanted samples from the integral of the elastic backscattering yield, using a pocket calculator, is represented. The energy dependence E2, of the Rutherford law and the screening of the nuclear charge by the electron cloud is considered. The method is based on the assumption that the stopping power is a linearly decreasing function of the energy in the range from 1.4 MeV to 2MeV. The total yield can be integrated analytically, and the number of atoms in the sample can then be ascertained by an iteration procedure that can be accomplished with a scientific pocket calculator. The results obtained are compared with the values obtained using the computer simulation code for RBS spectra RUMP.Item Determination of friction coefficient at journal bearings by experimental and by means of artificial neural networks method(Association for Scientific Research, 2004) Ünlü B.S.; Durmuş H.; Meriç C.; Atik E.Knowing friction coefficient is important for determination of wear loss conditions at journal bearings. Tribological events that influence wear and its variations affect experimental results. In this study, friction coefficient at CuSn10 Bronze radial bearings has been determined by a new approach as experimental and artificial neural networks method. In experiments, effects of bearings have been examined at dry and lubricated conditions and at different loads and velocities.Item Natural frequencies of beam-mass systems in transverse motion for different end conditions(Association for Scientific Research, 2005) Öz H.R.; Özkaya E.In this study, an Euler-Bernoulli type beam carrying masses at different locations is considered. Natural frequencies for transverse vibrations are investigated for different end conditions. Frequency equations are obtained for two and three mass cases. Analytical and numerical results are compared with each other. © Association for Scientific Research.Item An investigation of the Gamow-Teller 1+ states in 90Nb isotopes(Association for Scientific Research, 2005) Babacan T.; Salamov D.I.; Küçükbursa A.In this study, based on Pyatov-Salamov method, the properties of the Gamow-Teller(GT) 1+ states in 90Nb have been investigated and the agreement of our results calculated by this method for the energy of Gamow-Teller Resonance (GTR) and the corresponding strengths of the 1 + excitations in 90Nb with the experimental values has been tested. As a result of the calculations, it was seen that the calculated values for the energy and strength of the GTR are sufficiently in agreement with the experimental ones. © Association for Scientific Research.Item Free energies and specific heats of the nematics within nonextensive thermostatistics(Association for Scientific Research, 2005) Afsar O.; Kayacan O.In this study, the free energies and specific heats of the nematic liquid crystals are studied within Tsallis thermostatistics. In equilibrium, free energy of PAA (para-azoxyanisole) vs the order parameter is plotted, as well as its the specific heat vs temperature. The effect of the nonextensivity is illustrated for some values of the entropic index q. © Association for Scientific Research.Item Hyperbolic sine and cosine rules for geodesic triangles on the hyperbolic unit sphere H02(Association for Scientific Research, 2005) Özdemir A.; Kazaz M.In this work, we proved the sine and cosine rules for a geodesic triangle on the hyperbolic unit sphere H02 by means of timelike unit vectors. We also obtained some useful results.Item Assessment of optimum tip speed ratio of wind turbines(Association for Scientific Research, 2005) Çetin N.S.; Yurdusev M.A.; Ata R.; Özdemir A.The first thing to do in wind turbine blade design is to select tip speed ratio. Generally speaking, the speed ratio depends on the profile type used and the number of blades. Various speed ratios could be chosen for different types of profiles with different number of blades. Therefore, an optimization procedure should be applied to find the best ratio since this directly affects the energy generated from the turbine and in turn the investment made. This study presents a procedure to assess the optimum speed ratios for various profile types used in practice with various numbers of blades.Item IBM-1 calculations on the even-even 122-128Te isotopes(Association for Scientific Research, 2005) Küçükbursa A.; Manisa K.; Çiftçi M.; Babacan T.; Maraş I.The 122-128Te isotopes in O(6)- SU(5) transition region were investigated. For these nuclei, the energy levels, B(E2) transition probabilities, and δ(E2/M1) mixing ratios were calculated within framework of the Interacting Boson Model (IBM-1). The results are compared with the experimental data and the previous calculations. It is shown that there is a good agreement between the results found and especially with the experimental ones.Item Determination of the steady state response of EFEF /VFVF supported rectangular specially orthotropic plates(Association for Scientific Research, 2006) Altintaş G.; Baǧci M.Determination Of The Steady State Response Of EFEF / VFVF Supported Rectangular Specially Orthotropic Plates is presented. EFEF and VFVF plates, these are rectangular plates with two opposite edges elastically or viscoelastically supported and remaining others free. Using the energy based finite difference method, the problem is modelled by a kind of finite difference element. Due to the significiance of the fundamental frequency of the plate, its variation was investigated with respect to mechanical properties of plate material and translational spring coefficient of supports. The steady state response of viscoelastically supported plates was also investigated numerically for various damping coefficients. In the numerical examples, the natural frequency parameters and steady state responses to a sinusoidally varying force are assessed for the fundamental mode. Convergence studies are made. Many new results have been presented. Considered problems are solved within the frame work of Kirchhoff-Love hypothesis. © Association for Scientific Research.Item A similarity solution of fin equation with variable thermal conductivity and heat transfer coefficient(Association for Scientific Research, 2006) Pakdemirli M.; Şahin A.Z.A nonlinear fin equation in which thermal conductivity is an arbitrary function of temperature and, heat transfer coefficient is an arbitrary function of spatial variable is considered. Scaling transformation is applied to the equations to determine the specific forms of these functions for which the equation admits such type of transformation. It is found that for arbitrary heat conduction function, scaling transformation exists for an inverse square heat transfer coefficient. Selecting also the conductivity as an exponential function, the partial differential equation is transferred to an ordinary differential equation via similarity transformations. The resulting equation is solved numerically and temperature distribution is determined for various heat conductivity parameters. © Association for Scientific Research.