On the efficacy of a novel optimized tuned mass damper for minimizing dynamic responses of cantilever beams

This study examines the optimal design of a tuned mass damper (TMD) in the frequency domain so that the dynamic response of cantilever beams can be decreased. Random vibration theory is applied to identify the mean square acceleration of the endpoint of a cantilever beam as the objective function to be reduced. In addition, to determine the optimal TMD coefficient of mass, stiffness, and damping, a differential evolution (DE) optimization algorithm is employed. The upper and lower limit values of these parameters are taken into account. A majority of the previous studies have concentrated on determining just the stiffness and damping parameters of TMD. Nonetheless, in this study there is also the optimization of TMD mass parameters to determine the mass quantity. In addition, there has been inefficient use of the stochastic DE optimization algorithm method for the optimization of TMD parameters in previous studies. Hence, to obtain optimal TMD parameters, this algorithm is precisely used on the objective function. Tests are carried out on the cantilever beam with the TMD system following this optimization method with harmonic base excitations that resonate the foremost modes of the beam and white noise excitation. The method proposed here is reasonably practical and successful regarding the optimal TMD design. When a TMD is designed appropriately, the response of the cantilever beam under dynamic interactions undergoes a considerable reduction

Evaluation of low tidal volume with positive end-expiratory pressure application effects on arterial blood gases during laparoscopic surgery

Abstract Background: Pneumoperitoneum (PNP) and patient positions required for laparoscopy can induce pathophysiological changes that complicate anesthetic management during laparoscopic procedures. This study investigated whether low tidal volume and positive end-expiratory pressure (PEEP) application can improve ventilatory and oxygenation parameters during laparoscopic surgery. Methods: A total of 60 patients undergoing laparoscopic surgery were randomized to either the conventional group (n ¼ 30, tidal volume ¼ 10 mL/kg, rate ¼ 12/minute, PEEP ¼ 0 cm H 2 O) or the low tidal group with PEEP group (n ¼ 30, tidal volume ¼ 6 mL/kg, rate ¼ 18/minute, PEEP ¼ 5 cm H 2 O) at maintenance of anesthesia. Hemodynamic parameters, peak plateau pressure (Pplat) and arterial blood gases results were recorded before and after PNP. Results: There was a significant increase in the partial pressure of arterial carbon dioxide (PaCO 2 ) values after PNP in the conventional group in the reverse Trendelenburg (41.28 mmHg) and Trendelenburg positions (44.80 mmHg; p ¼ 0.001), but there was no difference in the low tidal group at any of the positions (36.46 and 38.56, respectively). We saw that PaO 2 values recorded before PNP were significantly higher than the values recorded 1 hour after PNP in the two groups at all positions. No significant difference was seen in peak inspiratory pressure (Ppeak) at the reverse Trendelenburg position before and after PNP between the groups, but there was a significant increase at the Trendelenburg position in both groups (conventional; 21.67 cm H 2 O, p ¼ 0.041, low tidal; 23.67 cm H 2 O, p ¼ 0.004). However, Pplat values did not change before and after PNP in the two groups at all positions. Conclusion: The application of low tidal volume þ PEEP þ high respiratory rate during laparoscopic surgeries may be considered to improve good results of arterial blood gases

Free Vibration Analysis of Beam on Elastic Foundation by the Variational Iteration Method

WOS: 000273652600001This paper applies the variational iteration method (VIM) to analysis of free vibration of a beam on an elastic foundation. Three different axially loaded cases are considered: 1) one end fixed, the other end simply supported; 2) both ends fixed; and 3) both ends simply supported. Analytical solutions and the frequency factors are obtained for different ratios of axial load acting on the beam to Euler buckling load. The VIM results are in excellent agreement with both analytical solutions for all the cases considered in this paper and the differential transform method (DTM) results available in the literature for the fixed-pinned case

Seismic drift response of building structures in seismically active and near -fault regions

The main goal of this study is the development of a simple procedure for the assessment of seismic drift response of building structures located in seismically active and near-fault regions. The displacement-based design approach which correlates observed damage of a structure according to its drift ratio will be the reference point. The concept of ground velocity change, ΔV and its effects on the nonlinear displacement response of building structures are investigated. Ten ground motion data obtained from recording stations located in one of the most seismically active regions in the world, Turkey where two consecutive earthquakes occurred within three months in 1999 are used. The results of the nonlinear displacement response of the building structures revealed that for ΔV \u3e 0.75 m/s and [special characters omitted] \u3c 1.0 the displacement demand exceeds the displacement spectrum defined by Lepage (1997). In general, it is observed that the increase in ΔV increases the nonlinear displacement demand and the observed damage accordingly. To avoid excessive displacement demand an increase in base shear strength is beneficial to the performance of the building. Nonlinear displacement spectra are defined for single-degree-of-freedom systems and a three-dimensional displacement response spectrum for Earthquake-Resistant Design in Turkey is developed. Eight five-story reinforced concrete buildings are proposed which are proportioned to reflect the common construction practice in Turkey. Their behavior is investigated assuming that these buildings act as multi-degree-of-freedom systems. A relationship between the nonlinear displacement spectra of MDOF systems and SDOF systems is defined. A set of four buildings located close to a recording station were previously investigated (Engvall 2002) to determine the correlation between the calculated nonlinear behavior of the building structures and their observed damage. It revealed that a nonlinear SDOF system represented best the behavior of a building during an earthquake excitation. This station recorded the ground motions at the town of Duzce which was destructed during both earthquakes. In the light of the described findings it is concluded that the proposed methodology regarding the effect of ground velocity change on the maximum drift of the building structures represents the observed behavior of the building structures located in seismically active regions well

Vibration analysis of plates with curvilinear quadrilateral domains by discrete singular convolution method

WOS: 000282139300002A methodology on application of the discrete singular convolution (DSC) technique to the free vibration analysis of thin plates with curvilinear quadrilateral platforms is developed. In the proposed approach, irregular physical domain is transformed into a rectangular domain by using geometric coordinate transformation. The DSC procedures are then applied to discretization of the transformed set of governing equations and boundary conditions. For demonstration of the accuracy and convergence of the method, some numerical examples are provided on plates with different geometry such as elliptic, trapezoidal having straight and parabolic sides, sectorial, annular sectorial, and plates with lour curved edges. The results obtained by the DSC method are compared with those obtained by other numerical and analytical methods. The method is suitable for the problem considered due to its generality, simplicity, and potential for further development.Akdeniz UniversityThe financial support of the Scientific Research Projects Unit of Akdeniz University is gratefully acknowledged

Free vibration analysis of tapered beam-column with pinned ends embedded in Winkler-Pasternak elastic foundation

WOS: 000208451100004The current study presents a mathematical model and numerical method for free vibration of tapered piles embedded in two-parameter elastic foundations. The method of Discrete Singular Convolution (DSC) is used for numerical simulation. Bernoulli-Euler beam theory is considered. Various numerical applications demonstrate the validity and applicability of the proposed method for free vibration analysis. The results prove that the proposed method is quite easy to implement, accurate and highly efficient for free vibration analysis of tapered beam-columns embedded in Winkler- Pasternak elastic foundations.Scientific Research Projects Unit of Akdeniz UniversityThe financial support of the Scientific Research Projects Unit of Akdeniz University is gratefully acknowledged

The Homotopy Perturbation Method for free vibration analysis of beam on elastic foundation

WOS: 000286688300005In this study, the homotopy perturbation method (HPM) is applied to free vibration analysis of beam on elastic foundation. This numerical method is applied on three different axially loaded cases, namely: 1) one end fixed, the other end simply supported; 2) both ends fixed and 3) both ends simply supported cases. Analytical solutions and frequency factors are evaluated for different ratios of axial load N acting on the beam to Euler buckling load, N(r). The application of HPM for the particular problem in this study gives results which are in excellent agreement with both analytical solutions and the variational iteration method (VIM) solutions for all the cases considered in this study and the differential transform method (DTM) results available in the literature for the fixed-pinned case

Evaluation of Manure Management in Dairy Cattle Farms: The Case of Izmir-Tire (Turkey) Region

WOS: 000295359100010The objective of this research is to evaluate the current manure management systems in dairy cattle farms, which are the members of Tire Dairy Cooperative, in Tire-Izmir Region. In this context; characteristics of farms, manure management systems and their statistical interactions were determined. Also, methane emissions through manure management were estimated for two different approaches of Intergovernmental Panel on Climate Change (IPCC) and SWOT analyze for manure management in region was done. According to results of the research, it is noticed that farmers do not care about technical standards and legal regulations on planning the barn placement and storing the manure. It is determined that 74% of the examined farms use mechanization possibilities to collect the manure from paddocks. In 78% of the farms manure is stored as a bulk inside or outside of the farm, in 16% of the farms it is stored on paddocks and in 6% of the farms it is stored in a pit. In 99% of the farms, manure is used as fertilizer on fields without taking precautions for fermentation and also it is burned directly in 1% of the farms. Statistical analyses show that, manure collection and storage practices have significant interactions with farm characteristics while manure usage practices have no significant interactions with farm characteristics. Methane emissions for the region were calculated 0.2 Gg year-1 for the first approach and 0.03 Gg year-1 for the second approach. SWOT analyze shows that, manure management practices and infrastructure are better in big farms and the cooperative may make a significant contribution to usage of modern systems in the region.Ege University Scientific Research Projects CommissionEge University [2008-ZRF-022]This study was prepared from MSc thesis and supported by Ege University Scientific Research Projects Commission (Project No: 2008-ZRF-022

Modeling of plasma assisted formation of precipitates in zirconium containing liquid precursor droplets

This paper focuses on the modeling of heat and mass transfer in precursor containing droplets injected into a plasma jet and the estimation of precipitate formation in these droplets from the solute. A hybrid model is employed where the plasma temperature and velocity fields are obtained from previous experimental results and the heat and mass transfer around droplets are modeled. The precipitate formation zones from the zirconium acetate solution in these droplets are estimated based on the solute concentration field within the droplet. A simple homogeneous nucleation hypothesis is employed in predicting the regions of droplets where zirconia might precipitate. The effects of droplet size, injection velocity and angle, plasma conditions as well as the solute mass diffusivity are considered. Micrographs from single pass coating experiments give credible evidence of the presence of similar types of particle morphologies in agreement with this modeling study