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Fatigue in jointless bridge H-piles under axial load and thermal movements

Karalar M. | Dicleli M.

Makale | 2018 | Journal of Constructional Steel Research147 , pp.504 - 522

The seasonal and short-term temperature variations produce cyclic horizontal displacements in the continuous superstructure of jointless bridges and hence in the abutment piles. Thorough study of the available field measurement data for jointless bridges showed that the thermal-induced cyclic flexural strains in steel H-piles (SHPs) at the abutments are composed of large, primary small and secondary small flexural strain cycles. While the SHPs at the abutments of jointless bridges laterally deform and experience these cyclic flexural strains due to thermal effects, they also carry axial loads transferred from the superstructure thro . . .ugh the abutments. Review of the literature revealed that there is no specific study on the combined effects of axial load and thermal-induced/flexural strain cycles with various amplitudes on the low cycle fatigue (LCF) performance of jointless bridge SHPs. For this purpose, parametric experimental studies on full scale SHP specimens are conducted to simulate the cyclic behavior of SHPs under thermal effects in jointless bridges by considering the effect of axial load combined with large and small flexural strain cycles with various amplitudes. It is observed that at large flexural strain amplitudes, local buckling of the pile due to the effect of axial load adversely affects the LCF life of SHPs at the abutments of jointless bridges. Furthermore, it is observed that the effect of small flexural strain cycles on the LCF life of uncompact SHPs depends on the amplitude of large flexural strains and the amplitude ratio of the small and large flexural strains. © 2017 Elsevier Lt Daha fazlası Daha az

Forming sheet metals by means of multi-point deep drawing method

Yaşar M. | Korkmaz Z. | Gavas M.

Makale | 2007 | Materials and Design28 ( 10 ) , pp.2647 - 2653

Multi-point deep drawing (MPDD) is an advanced manufacturing technology for 3D sheet metal parts and it can form a variety of part shapes without the need for solid dies. In this study, a test set has been prepared for multi-point deep drawing process utilizing the multi-point forming technology. Drawability attributes of gradually rectangular shaped container have been observed using a sheet, which has the quality of Erdemir 7114 and is suitable for deep drawing process, and also using multi-pointed punch with a given tool geometry and a draw velocity. The blank shape to be drawn without wrinkling and tearing has been determined. W . . .rinkles and dimples are the major forming defects in the MPDD process. In conventional deep drawing, the method to form sheet metal with a blank holder is an effective way to suppress wrinkling; and the same is true in MPDD. The process of multi-point forming technology decreases production cost of die, provides flexible usage, and it is convenient to achieve the most even deformation distribution. © 2006 Elsevier Ltd. All rights reserved Daha fazlası Daha az

The first regio- and diastereoselective synthesis of homochiral perhydroimidazoisoxazoles via the 1,3-dipolar cycloaddition of imidazoline 3-oxides with (1S)-(-)-ß-pinene

Coşkun N. | Tat F.T. | Güven Ö.Ö.

Makale | 2001 | Tetrahedron Asymmetry12 ( 10 ) , pp.1463 - 1467

The 1,3-dipolar cycloaddition of imidazoline 3-oxides 1 with (1S)-(-)-ß-pinene proceeds regio- and diastereoselectively to give homochiral perhydroimidazoisoxazole derivatives 3 in high yields in the cases of imidazoline 3-oxides 1a-e but in low yields in the reactions of 1f-g. The preferred attack of (1S)-(-)-ß-pinene to the cyclic nitrone was shown to be anti-endo. The reaction of racemic nitrones (±)-1f-g with the homochiral ß-pinene gave the adduct from the (S)-nitrone and the corresponding imidazole. The adducts 3 undergo retro-1,3-dipolar cycloaddition when heated in the condensed phase or in diphenyl ether to give the corresp . . .onding imidazole and ß-pinene. © 2001 Elsevier Science Ltd. All rights reserved Daha fazlası Daha az

Comparative formation constants for metal ions with macrocycles based on 1,4,8,11-tetraazacyclotetradecane and carrying diamine, dicarboxylate or amine-carboxylate pendants

Baran Y. | Lawrance G.A. | Wilkes E.N.

Makale | 1997 | Polyhedron16 ( 4 ) , pp.599 - 602

Acid dissociation constants for the newly isolated dihydrogen anti-1,4,8,11-tetraazacyclotetradecane-6,13-dicarboxylate (diacmac), as well as for hydrogen anti-6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine-13-carboxylate (acammac) and anti-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine (diammac) are reported. The ligands differ somewhat in their selection of metal ions, which is reflected in the formation constants for complexation (log KML, 25°C) which have been determined for the d10 metal ions Zn2+ (diammac, 14.9; acammac, 14.7; diacmac, 26.3), Cd2+ (diammac, 10.6; acammac, 16.7; diacmac, 15.9), Hg2+ (diammac, . . .10.5; acammac, 17.3; diacmac, 21.8) and Pb2+ (diammac, 10.8; acammac, 10.7; diacmac, 19.0) and the d5 Mn2+ ion (diammac, 6.2; acammac, 12.0; diacmac, 18.3). Differences arise in part from the increasing availability of potential O donors versus N donors in stepping from diammac to diacmac, and imply a clear role for the pendants in binding metal ions. Copyright ©1996 Elsevier Science Ltd Daha fazlası Daha az

Erratum: Corrigendum to “The 3-D strain patterns in Turkey using geodetic velocity fields from the RTK-CORS (TR) network” (Journal of African Earth Sciences (2016) 115 (246–270)(S1464343X15301242)(10.1016/j.jafrearsci.2015.12.002))

Kutoglu H.S. | Toker M. | Mekik C.

Erratum | 2016 | Journal of African Earth Sciences124 , pp.517 - 518

In the article titled “The 3-D Strain patterns in Turkey using Geodetic velocity fields from the RTK-CORS (TR) Network” published in Journal of African Earth Sciences Vol. 11, pp.246–270, the black arrows on the Figs. 10 and 12 are shifted due to printing error to undesired places. The correct form of Figs. 10 and 12 are given below: Fig. 10. Normal strain in the y-axis (max rms = ± 2 × 10-5 ppb). The westerly black arrow refers to the Tekirdag basin and the easterly arrow refers to the Çınarcik basin. Note the compressional strain in the ruptured zone of the 2011 Van earthquake (LV) consistent with its aftershock distribution (6000 . . . events) (see Fig. 2). Fig. 12. Shear strain in the xy-plane (max rms = ± 7.7 × 10-6 ppb). Note the anomalous circular closure of extensional shear strains in the center of EAAP, LV and the compressional shear strains in the W-part of MS and KTJ (see Fig. 2). © 201 Daha fazlası Daha az

Combination and comparison of two models in prognosis of pulmonary embolism: Results from TUrkey Pulmonary Embolism Group (TUPEG) study

Ozsu S. | Ozlu T. | Şentürk A. | Uçar E.Y. | Kirkil G. | Kadioglu E.E. | Altinsoy B.

Makale | 2014 | Thrombosis Research133 ( 6 ) , pp.1006 - 1010

Background Clinical parameters, biomarkers and imaging-based risk stratification are widely accepted in pulmonary embolism(PE). The present study has investigated the prognostic role of simplified Pulmonary Embolism Severity Index (sPESI) score and the European Society of Cardiology (ESC) model. Methods This prospective cohort study included a total of 1078 patients from a multi-center registry, with objectively confirmed acute symptomatic PE. The primary endpoint was all-cause mortality during the first 30 days, and the secondary endpoint included all-cause mortality, nonfatal symptomatic recurrent PE, or nonfatal major bleeding. R . . .esults Of the 1078 study patients, 95 (8.8%) died within 30 days of diagnosis. There was no significant difference between non-low-risk patients ESC [12.2% (103 of 754;)] and high-risk patients as per the sPESI [11.6% (103 of 796)] for 30-day mortality. The nonfatal secondary endpoint occurred in 2.8% of patients in the the sPESI low-risk and 1.9% in the ESC low-risk group. Thirty-day mortality occurred in 2.2% of patients the sPESI low-risk and in 2.2% the ESC low-risk group (P = NS). In the present study, in the combination of the sPESI low-risk and ESC model low-risk mortality rate was 0%. Conclusions The sPESI and the ESC model showed a similar performance regarding 30-day mortality and secondary outcomes in the present study. However, the combination of these two models appears to be particularly valuable in PE. © 2014 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Effect of gravity waves on the tropopause temperature, height and water vapor in Tibet from COSMIC GPS Radio Occultation observations

Khan A. | Jin S.

Makale | 2016 | Journal of Atmospheric and Solar-Terrestrial Physics138-139 , pp.23 - 31

The tropopause plays an important role in climate change, particularly in Tibet with complex topography and climate change system. In this paper, the temperature and height of the Cold Point Tropopause (CPT) in Tibet are obtained and investigated from COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) GPS Radio Occultation (RO) during June 2006-Feb 2014, which are compared with Lapse Rate Tropopause (LRT) from Atmospheric Infrared Sounder (AIRS/NASA). Furthermore, the impact of Gravity waves (GW) potential energy (Ep) on the CPT-Temperature, CPT-Height, and the variation of stratospheric water vapor with . . . GW Ep variations are presented. Generally the coldest CPT temperature is in June-July-August (JJA) with -76.5°C, resulting less water vapor into the stratosphere above the cold points. The temperature of the cold point increases up to -69°C during the winter over the Tibetan Plateau (25-40°N, 70-100°E) that leads to increase in water vapor above the cold points (10hPa). Mean vertical fluctuations of temperature are calculated as well as the mean gravity wave potential energy Ep for each month from June 2006 to Feb 2014. Monthly Ep is calculated at 5°×5° grids between 17km and 24km in altitude for the Tibetan Plateau. The Ep raises from 1.83 J/Kg to 3.4 J/Kg from summer to winter with mean Ep of 2.5 J/Kg for the year. The results show that the gravity waves affect the CPT temperature and water vapor concentration in the stratosphere. Water vapor, CPT temperature and gravity wave (Ep) have good correlation with each other above the cold points, and water vapor increases with increasing Ep. © 2015 Elsevier Ltd Daha fazlası Daha az

Estimation of the production of medical Ac-225 on thorium material via proton accelerator

Artun O.

Makale | 2017 | Applied Radiation and Isotopes127 , pp.166 - 172

In the present study, we aimed at estimating the production of medical Ac-225 radionuclide via proton accelerator in the energy range Eproton=1000 ›1 MeV under certain conditions, on thorium target material instead of uranium due to the low abundant of uranium in nature. Hence, to produce the medical Ac-225, cross-section, separation energy was calculated by taking into account the proton induced reaction processes that were simulated to estimate activity and, yield of the product up to 1000 MeV. Moreover, the calculated integral yields of reactions were presented. For achieving the aim, we have put forward the X-PMSP program to der . . .ive mass stopping power from a new perspective. © 2017 Elsevier Lt Daha fazlası Daha az

Wear behaviour of organic asbestos based and bronze based powder metal brake linings

Kurt A. | Boz M.

Makale | 2005 | Materials and Design26 ( 8 ) , pp.717 - 721

Bronze based brake linings, were produced by powder metallurgy technique and their wear behaviour was investigated and compared to that of asbestos ones. Bronze powders were compacted under 350, 500 and 600 MPa pressures and sintered at 810 °C in ammonia atmosphere for 75 min. For the same friction distance, it was determined that temperature increase in the bronze based brake linings was lower than that of asbestos based ones. However, higher wear rate was observed in the bronze based brake linings. Moreover, thermal conductivity was decreased with high porosity level with low densities. Although, friction coefficient remained the . . .same during breaking, an increase in wear resistance was observed. © 2004 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Calculation of productions of medical 201Pb, 198Au, 186Re, 111Ag, 103Pd, 90Y, 89Sr, 77Kr, 77As, 67Cu, 64Cu, 47Sc and 32P nuclei used in cancer therapy via phenomenological and microscopic level density models

Artun O.

Makale | 2019 | Applied Radiation and Isotopes144 , pp.64 - 79

In the present study, we have widely investigated the production of nuclei used in cancer therapy for both phenomenological and microscopic level density models via TALYS and EMPIRE codes. To estimate the production of the radioisotope, we calculated the cross-section curves of the reaction and the integral yield curves for nine level density models using the cross-sections and the mass-stopping powers acquired from X-PMSP program in the particle beam current of 1 µA and irradiation time 1 h. To discuss the obtained results on the basis of the cross-sections and the integral yields curves, the results were compared with the experime . . .ntal data and the recommended data in the literature. © 2018 Elsevier Lt Daha fazlası Daha az

Turkish dermatologists' approach for chronic spontaneous urticaria: A questionnaire based study

Kocatürk E. | Piril E. | Oktay T. | Nilgun A. | Teoman E. | Serap U. | Ekin S.

Makale | 2018 | Dermatologica Sinica36 ( 2 ) , pp.70 - 74

Background/Objectives: Chronic spontaneous urticaria (CSU) is a common skin disorder which represents a challenge both for the patients and physicians. Guidelines and treatment algorithms have been created to help physicians to ease management. Our aim was to determine Turkish dermatologists' approach to CSU with regard to treatment, search for causative factors and use of instruments to assess the quality of life and severity of the disease. Methods: This was a cross-sectional methodological study which was performed by delivery of a questionnaire including ten questions about the management of CSU. Results: Analyses of 314 questio . . .nnaires revealed that the most common first-line treatments were non-sedating antihistamines in standard doses (65.6%), while second-line treatment was updosing antihistamines (59.9%) followed by addition of sedative-antihistamines (26.4%) and systemic steroids (19.1%). Third-line treatment option was omalizumab in 35% followed by systemic steroids. Twenty-two percent of the dermatologists referred the patients to a center experienced in urticaria. Most of them were performing laboratory testing for underlying causes including thyroid function tests, C-reactive protein, thyroid auto-antibodies, stool analyses, infection markers. Urticaria activity score and chronic urticaria quality of life questionnaire were used by 30 and 13%, respectively, while 56% were using none of the instruments. Conclusion: Our study showed that the therapeutic management of Turkish dermatologists was parallel to the European Urticaria Guidelines. The high utility of omalizumab as a third line regimen improved patient care. Nevertheless there is a need for centers experienced in urticaria to refer antihistamine-resistant patients where third-line treatment options can not be implemented. © 201 Daha fazlası Daha az

The size effect on the magnetic levitation force of MgB2 bulk superconductors

Savaskan B. | Koparan E.T. | Güner S.B. | Celik S. | Yanmaz E.

Makale | 2016 | Cryogenics80 , pp.108 - 114

In this study, the size effect on the magnetic levitation performance of disk-shaped MgB2 bulk superconductors and permanent magnets was investigated. MgB2 samples with varying diameters of 13 mm, 15 mm and 18 mm, each of which were 2 g in mass, were prepared by two-step solid state reaction method. Vertical levitation force measurements under both zero-field-cooled (ZFC) and field-cooled (FC) regimes were carried out at different temperatures of 20, 24 and 28 K. It was determined that the levitation force of the MgB2 strongly depends on both the diameters of the sample and the permanent magnet. In ZFC regime, the maximum levitation . . . force value for the permanent magnet and the sample 18 mm in diameters reached to the 8.41 N at 20 K. In addition, in FC regime, attractive and repulsive force increased with increasing diameters of the sample and the permanent magnet. In that, the sample with 18 mm in diameter showed the highest attractive force value -3.46 N at 20 K and FC regime. The results obtained in this study are very useful in magnetic levitation devices as there is no detailed study on the size of superconductors and permanent magnets. © 2016 Elsevier Lt Daha fazlası Daha az

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