Detaylı Arama

Bulunan: 158 Adet 0.001 sn
- Eklemek veya çıkarmak istediğiniz kriterleriniz için 'Dahil' / 'Hariç' seçeneğini kullanabilirsiniz. Sorgu satırları birbirine 'VE' bağlacı ile bağlıdır.
- İptal tuşuna basarak normal aramaya dönebilirsiniz.
Bulunan: 158 Adet 0.001 sn
Koleksiyon [20]
Tam Metin [2]
Yayın Türü [6]
Yazar [20]
Yayın Yılı [20]
Konu Başlıkları [20]
Yayıncı [1]
Yayın Dili [1]
Dergi Adı [20]
Response dynamics of 2D plasmons coupled with optical phonons in bulk and near an interface

Horing N.J.M. | Ayaz Y.

Article | 1998 | Solid State Communications105 ( 8 ) , pp.507 - 511

We analyze both the local and nonlocal coupled mode dispersion relations for a degenerate 2D plasma interacting with both surface and bulk optical phonons. The coupled collective modes and their nonlocal shifts, are exhibited as functions of the distance z0 of the 2D plasma sheet from the bounding surface of the host material. We also explicitly determine the excitation amplitudes (oscillator strengths) of the modes. © 1998 Elsevier Science Ltd.

Synthesis and characterization of poly (linoleic acid)-g-poly(methyl methacrylate) graft copolymer with applying in Au/PLiMMA/n-Si diode

Çulcu H. | Alli A. | Alli S. | Gökçen M.

Article | 2015 | Materials Science in Semiconductor Processing31 , pp.639 - 643

Poly (linoleic acid)-g-poly(methyl methacrylate) (PLiMMA) graft copolymer was synthesized and characterized. PLiMMA graft copolymer was synthesized from polymeric linoleic acid peroxide (PLina) possessing peroxide groups in the main chain by free radical polymerization of methyl methacrylate. Later, PLiMMA was characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques. Furthermore, Au/PLiMMA/n-Si diode was fabricated for the purpose of investigating PLiMMAs conformity in diodes. The main electrical charact . . .eristics of this diode were investigated using experimental current-voltage (I-V) measurements in dark and at room temperature. Obtained results, such as sufficiently high rectifying ratio of 4.5×104, indicate that PLiMMA is a promising organic material for electronic device applications. © 2014 Elsevier Ltd. All rights reserved Daha fazlası Daha az

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

Yaşar M. | Korkmaz Z. | Gavas M.

Article | 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

Gender and politics: Patriarchal discourse on social media

Demirhan K. | Çakir-Demirhan D.

Article | 2015 | Public Relations Review41 ( 2 ) , pp.308 - 310

Comprehensive comparison of VHR 3D spatial data acquired from IKONOS and TerraSAR-X imagery

Sefercik U.G. | Ozendi M.

Article | 2013 | Advances in Space Research52 ( 9 ) , pp.1655 - 1667

With the launch of very high resolution (VHR) optical and synthetic aperture radar (SAR) remote sensing satellites such as IKONOS and TerraSAR-X, a new era has begun in 3D spatial data acquirement. IKONOS provided the first VHR data is still being preferred for many remote sensing applications. TerraSAR-X is considered as a revolution in SAR imaging as a result of 1 m resolution imaging capability. The imaging principles of these satellites are quite different and include advantages and disadvantages that have considerable effects on the quality of acquired 3D spatial data. In this research, we aim to compare qualities of high resol . . .ution digital elevation models (DEMs) generated from IKONOS and TSX imagery based on a reference model. Quality assessment was realized considering two main components as accuracy and visuality on different land classes. Results of comprehensive analyses indicate that the qualities of 3D data derived from IKONOS and TSX HS are almost identical and DEMs of both satellites can be used for various applications. © 2013 COSPAR. Published by Elsevier Ltd. All rights reserved Daha fazlası Daha az

Particle migration and surface modification on Ti6Al4V in SiC powder mixed electrical discharge machining

Öpöz T.T. | Yaşar H. | Ekmekci N. | Ekmekci B.

Article | 2018 | Journal of Manufacturing Processes31 , pp.744 - 758

The study examines the impact of SiC powder concentration on surface topography, particles deposition and subsurface structures in powder mixed electrical discharge machining (PMEDM) of Ti-6Al-4V-ELI work material. It was observed that low pulse currents and high suspended particle concentration in dielectric liquid enhance the material transfer mechanism in particulate form. The subsurface properties of such surfaces exhibited a distinctive and harder re-solidified layer structure that indicates a unique material transfer mechanism takes place during machining. The particles placed close to a discharge column directed towards the m . . .elted metal pool due to the sudden closure of the plasma channel. When the main discharge channel subdivided into several secondary discharges, the suspended particles in dielectric liquid stuck among the scattered sub discharges and increased the probability of penetrating into the melted metal pool at the end of a discharge. Therefore, the formation of secondary discharges favoured the improved SiC transfer in particulate form. However, increasing the pulse current deplete the material transfer mechanism in particulate form due to the inadequacy of secondary discharges. © 201 Daha fazlası Daha az

Design and application an integrated element selection model for press automation line

Cetinkaya K.

Article | 2007 | Materials and Design28 ( 1 ) , pp.217 - 229

There are many things that make useful automatic line systems for metalworking machinery. Press automation systems have been widely used in the industry for sheet metal processing. This paper presents a new approach towards elements selection of an automatic line for sheet metal forming. Automation line element selection is a complex, tedious task, and there are few tools other than checklists to assist engineers in the selection of appropriate, cost-effective elements. It has been described as an integrated press automation line elements selection system called press automation elements selection advisor (PAESA) model in this study . . .. The PAESA has incorporated 10 stages of integrated factors such as property profile of possible elements, defining of developed elements, firm research, company contact and costumer service, specification of requirements, driver mechanisms, environmental selection and cost, system accuracy, product strategy and fine selection. © 2005 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Debris and consequences in micro electric discharge machining of micro-holes

Ekmekci B. | Sayar A.

Article | 2013 | International Journal of Machine Tools and Manufacture65 , pp.58 - 67

The tip shape of a blind micro-hole produced using micro electrical discharge machining varies with respect to the process parameters used during machining. The usual tip shape is a blunt geometry within the common range of applications, however, under specific machining conditions and machining depths, the tip shape changes drastically to an inverted concaved shape. The origin of such tip deformation in micro electric discharge machining of blind micro-holes was investigated. It was observed that debris particles produced during machining accumulated at the tip, formed a hill and functioned as a tool electrode especially when using . . . fine machining conditions. The phenomena is elaborated experimentally with the affecting parameters to describe the wear mechanism. Open gap voltage, pulse energy and tool rotation speed are examined as varying parameters during the experiments. © 2012 Elsevier Ltd. All rights reserved Daha fazlası Daha az

A study of the microscopic deformation behavior of an phosphor bronze plate during arbitrary holes piercing process

Cetinkaya K.

Article | 2007 | Materials and Design28 ( 1 ) , pp.294 - 300

In order to obtain competitiveness in the field of industrial manufacturing, a reduction in the development period for the small batch manufacturing of products is required. However, metal forming tools cause multiple cracking on sheet metal strips during piercing process due to clearance between punch and die. Such a cracking eventually causes severe degradation of the critical current density. Therefore, it is very important to understand the microscopic deformation behavior of CuSn9 alloy under mechanical loading. A method of evaluating the strain over the deformed surface of stamping is described. Measurements of the deformation . . . width of the edges of arbitrary holes on the sheet metal were analyzed to determine the strain and the stress distributions which were displayed in the form of contours. For an arbitrary hole piercing process, FEM simulation with ANSYS/LS-DYNA Test of Edbound with Eroding Contact was used and as the first step, strip process layout was designed. After that, the process of die development was studied according to the sequence of die components, i.e., die structure, machining condition for die making, die materials, heat treatment of partially die components, and so on. In this study, modeling of strip layout and die components with the Mechanical Desktop commercial program, standard components selection and strip process layout drawing with the Auto-LISP, CAD/CAM application, ordinary machine tool operating, and measurement microscopic cracking deformation is done. © 2005 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.

Article | 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

Entropy generation analysis of a microchannel-condenser for use in a vapor compression refrigeration cycle [Analyse de la production d'entropie d'un condenseur à microcanaux pour une utilisation dans un cycle frigorifique à compression de vapeur]

Türkakar G. | Okutucu-Özyurt T. | Kandlikar S.G.

Article | 2016 | International Journal of Refrigeration70 , pp.71 - 83

Dimensionless entropy generation number in the microchannel condenser of a vapor compression refrigeration cycle is investigated. An air cooled, brazed aluminum parallel flow heat exchanger is considered as the condenser with R-134a as the refrigerant. While the effects of the fin pitch, fin height, louver angle and the air mass flow rate are investigated for the air side, the effect of the channel diameter is examined for the refrigerant side. The analysis is performed segment by segment for the superheated, two phase and subcooled regions using well-established empirical correlations. A mapping study is presented for the variation . . . of entropy generation number with the mentioned parameters. The optimum air mass flow rate interval is found to be between 0.055 and 0.1?kgs-1 for a given fin pitch interval of 1–1.6?mm. This range is within the operating limits of air fans in the market for this size. In his operating range, the optimal dimensions giving the minimum entropy generation numbers are presented. The entropy generation number distribution is given based on the pressure drop, heat transfer or the refrigerant state in the heat exchanger considering superheated, two phase, and subcooled regions. The entropy generation number due to pressure drop on the air side becomes dominant after a mass flow rate around 0.08?kgs-1. Hence, an optimum air mass flow rate generating the minimum entropy generation number is sought for different sizes of the condenser. The condenser length is variable in the range of 84.3–80.6?mm for the mentioned optimal air mass flow rate interval. The condenser height changes depending on desired operational conditions, and it is determined to be 112.5?mm for the fixed values given in the study. The study is unique in the literature in pursuing an entropy generation number mapping study for microchannel two-phase flow in air cooled heat exchangers. © 2016 Elsevier Ltd and II Daha fazlası Daha az

Synthesis of bis[N-(p-aryl)-carbamoyloxy]alkanes as new low-molecular weight organogelators

Demir-Ordu Ö. | Şimşir H. | Alper K.

Article | 2015 | Tetrahedron71 ( 10 ) , pp.1529 - 1539

A series of bis-carbamate-based low-molecular-weight organogelators were synthesized, and their structure-property relationships with respect to their gelation abilities in organic solvents were investigated. The self-aggregation behavior of the thermoreversible organogels was investigated by FTIR, temperature-dependent NMR, and SEM studies. The results revealed that the self-assembly into fibrous structures is driven by hydrogen bonding, ?-? stacking, and hydrophobic interactions. It was found that para-aryl substitution and the number of methylene units connecting two carbamate groups had a significant influence on gelation. The e . . .ffect of temperature on gel formation was also investigated for all compounds. The most interesting feature was observed for p-hexyl derivative, which gels at -18 °C but not room temperature. Furthermore, thermal properties of the gels were studied by dropping ball experiments and DSC. para-Alkoxyphenyl derivatives were also found to be good organogelators for olive oil, sunflower oil, corn oil, and ethyl laurate, isopropyl myristate, n-butyl palmitate. © 2015 Elsevier Ltd. All rights reserved Daha fazlası Daha az

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