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Bulunan: 423 Adet 0.001 sn
Koleksiyon [20]
Tam Metin [2]
Yayın Türü [10]
Yazar [20]
Yayın Yılı [1]
Konu Başlıkları [20]
Yayıncı [20]
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Editör/Editörler [8]
Air Pollution And The Risk Of Venous Thromboembolism

Tor, M. | Cevik, C. | Kurcer, M. | Akbulut, S. | Altuntas, M. | Atalay, F.

Conference Object | 2010 | AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE181

WOS: 000208771000726

Vibration analysis of euler-bernoulli beam based on the variational iteration method

Ozer H.

Conference Object | 2010 | 17th International Congress on Sound and Vibration 2010, ICSV 20104 , pp.2740 - 2745

The variational iteration method has been attracted much attention of researchers as a promising method for solving linear and nonlinear differential equations. This study presents a way of using the variational iteration method (VIM) to solve free vibration problems of uniform Euler-Bernoulli beams. The method depends on constructing a correction functional by a general Lagrange multiplier. An example is given to illustrate the accuracy and efficiency of the present method. Each iteration step gives a direct approximate solution to the problem. It is verified that the method is a powerful mathematical tool to get the solutions easi . . .ly by reducing the volume of calculations Daha fazlası Daha az

A new phase measurement technique for RF power amplifier only measuring magnitudes

Yuzer A.H. | Demir S.

Conference Object | 2010 | PIERS 2010 Cambridge - Progress in Electromagnetics Research Symposium, Proceedings , pp.170 - 173

In this study, a new phase measurement setup to measure magnitudes and phases of the fundamental components and intermodulation created by an amplifier under two tone excitation is reported. There are three signal generators, one digital attenuator and one spectrum analyzer in the measurement setup. There is no need to any other special electronic circuits (e.g., mixer, filter, etc.). Phase is found/measured mathematically based on magnitude measurements. Also absolute phase difference between the frequency components can be measured. Measured phase error is better than 1° for repetitive measurements.

DRBEM solution of exterior nonlinear wave problem using FDM and LSM time integrations

Meral G. | Tezer-Sezgin M.

Article | 2010 | Engineering Analysis with Boundary Elements34 ( 6 ) , pp.574 - 580

The nonlinear wave equation is solved numerically in an exterior region. For the discretization of the space derivatives dual reciprocity boundary element method (DRBEM) is applied using the fundamental solution of Laplace equation. The time derivative and the nonlinearity are treated as the nonhomogenity. The boundary integrals coming from the far boundary are eliminated using rational and exponential interpolation functions which have decay properties far away from the region of interest. The resulting system of ordinary differential equations in time are solved using finite difference method (FDM) with a relaxation parameter and . . .least squares method (LSM). The proposed methods are examined with numerical test problems in which the behaviours of solutions are known. Although it gives almost the same accuracy with the DRBEM+FDM procedure, DRBEM+LSM solution procedure is preferred, since it is a direct method without the need of a parameter. © 2010 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Investigation of breakage behavior of coal in a laboratory-scale stirred media mill

Samanli S. | Cuhadaroglu D. | Ucbas Y. | Ipek H.

Article | 2010 | International Journal of Coal Preparation and Utilization30 ( 1 ) , pp.20 - 31

Coal obtained from the Catalagzi thermal power station was prepared into a -2360 +1700µm mono size fraction and ground for different times in a laboratory-scale stirred media mill. The breakage behavior was investigated and an attempt was made to determine optimum grinding conditions. Three stirring rates (1440, 720, and 360rpm) and three ball sizes (6, 4, 2.36mm) were utilized in the grinding studies. It was determined that for effective grinding not only the mill's mechanical properties but also the material properties have to be taken into consideration in order to determine breakage functions more accurately. At longer grind tim . . .es, oversize material mainly composed of shale, which is comparatively difficult to grind. As a result of this, breakage rate slows down and a deviation from first-order breakage behavior occurs in the grinding stage. Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

Nox formation in combustion of natural gases used in Turkey under different conditions

Öztürk S. | Eyriboyun M.

Article | 2010 | Isi Bilimi Ve Teknigi Dergisi/ Journal of Thermal Science and Technology30 ( 2 ) , pp.95 - 102

The amount of NO x produced during combustion is computationally investigated for methane, Russian- Shebelinka, Iran-South Pars, and Turkey-Tekirdag natural gases in different operating conditions. The flames are laminar and stoichiometric premixed. The chemical kinetic mechanism used in the study consists of 59 reactions and 25 chemical species. A computer program (CREK) is used to compute mole and mass fractions of products. The highest and the lowest NO x amounts are obtained during methane-air and Turkey-Tekirdag natural gas-air combustions. Amounts of methane and nitrogen in the compositions of natural gases affect the amount o . . .f NO x produced during combustion. The amount of NO x increases with increasing reactant inlet temperature. Increased reactant total mass amount raises the amount of NO x, but it causes mass fraction of NO x to decrease in the products. Increasing humidity ratio of the burning air reduces the amount of NO x. ©2008 TIBTD Printed in Turkey Daha fazlası Daha az

A nonlinear model for amplifiers with memory

Yuzer A.H. | Demir S.

Conference Object | 2010 | 2010 10th Mediterranean Microwave Symposium, MMS 2010 , pp.277 - 280

In this study an improved behavioral modeling including even order terms is proposed to model asymmetric IMD components observed in the multi-tone excitation of nonlinear amplifiers. Only odd order model (OOM) and even order introduced model (EOM), proposed model, are constructed and compared for a sample amplifier. It is showed that introducing even order term is improved the model validity range and accuracy in addition to the decrease model polinomial order. © 2010 IEEE.

Behavioral modeling of asymmetric intermodulation distortion of nonlinear amplifier

Yuzer A.H. | Demir S.

Conference Object | 2010 | PIERS 2010 Cambridge - Progress in Electromagnetics Research Symposium, Proceedings , pp.1115 - 1119

In this study, a behavioural modelling is proposed to model asymmetric IMD components produced in the two tone excitation of nonlinear amplifiers. Model parameters are extracted based on single tone and two-tone measurement results. Then measurement results and model predictions are compared for a four-tone signal.

Assessment of the dynamic stability of the portals of the Dorukhan tunnel using numerical analysis

Geniş M.

Article | 2010 | International Journal of Rock Mechanics and Mining Sciences47 ( 8 ) , pp.1231 - 1241

Instability problems may arise during the construction and operation of tunnels depending on the quality of the rock mass. In particular, determining instability problems at the portals of a tunnel is of utmost importance during excavation and operation of the tunnel. Slope instability and rockfalls are the most frequent instability problems that may be encountered at tunnel portals. Such instability problems can be triggered by dynamic effects such as earthquakes, blasting, etc. This study investigates the stability of the portals of the Dorukhan Tunnel connecting the provinces of Zonguldak and Bolu in the close vicinity of the Nor . . .th Anatolian Fault Zone (NAFZ), which is a well-known strike-slip 1500. km long fault. The effect of an earthquake that may occur in the NAFZ on the extent of failure has also been studied by numerical analyses. In the analyses, a three-dimensional dynamic analysis computer code, based on the finite difference method, has been used. According to results of the dynamic numerical analyses, the Devrek portal was found to be more stable than the Mengen portal. Moreover, it was found that, for acceleration values of dynamic wave higher than 0.5. g, tunnel portal slopes and the areas as far as 20-50. m from the tunnel entrance may suffer serious damage. Wave propagation perpendicular to the tunnel axis was established to cause more damage around the openings and in the portal slopes as wave compared to propagation parallel to the tunnel axis. © 2010 Elsevier Ltd Daha fazlası Daha az

Oral involvement in a case of AA amyloidosis: A case report

Cengiz M.I. | Wang H.-L. | Yldz L.

Article | 2010 | Journal of Medical Case Reports4 , pp.1231 - 1241

Introduction. Deposition of amyloid fibrils derived from circulating acute-phase reactant serum amyloid A protein causes systemic amyloidosis, a serious inflammatory disorder. We document a male patient who developed reactive amyloidosis (AA type), most likely secondary to his long standing periodontitis. Case presentation. A 67-year-old Turkish man complained of pain in his oral cavity (burning mouth) especially on the tongue, and had difficulty chewing and swallowing foods. A careful dental/periodontal examination was performed, including assessment of plaque, gingival condition and periodontal probing depths on all his remaining . . .teeth. Prosthetic rehabilitation was provided three months after the completion of his periodontal and surgical therapy. The concentration of serum inflammatory markers including erythrocyte sedimentation rate, white blood cell count, fibrinogen and high sensitive C-reactive protein were measured at baseline, at the second and sixth weeks, and at three and six months after the periodontal and surgical therapy. Conclusions. Oral examination revealed a few papules on the dorsum of the tongue with two slightly painful, small ulcers, localized on the vestibule of the mouth. The mean probing depth was 9.10 0.84 mm. Biopsies of the tongue, buccal mucosa and retromolar trigone were performed and amyloid deposits were found. The serum inflammatory markers improved more dramatically at the second week of periodontal therapy than any other time intervals. Amyloidosis may manifest as periodontal destruction that leads to severe chronic periodontitis. Proper periodontal treatment may alleviate systemic inflammatory mediators caused by the amyloidosis. © 2010 Cengiz et al; licensee BioMed Central Ltd Daha fazlası Daha az

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