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91.
Yunus Yıldız Sultan Kuzu Betül Sen Aysun Savk Süleyman Akocak Fatih Şen 《International Journal of Hydrogen Energy》2017,42(18):13061-13069
Addressed herein, a highly effective and monodisperse Pt/L@rGO nanocatalysts were successfully synthesized by using different types of ligands (pentylamine, Pt/PA@rGO and tripentylamine, Pt/TPA@rGO) and the impact of ligand on catalytic activity of the prepared nanomaterials have been examined for methanol oxidation. An easy and facile ultrasonication method was applied to produce highly efficient, monodispersed and durable (Pt) NPs dispersed on reduced graphene oxides (rGO). The structure morphology, composition and properties of Pt/L@rGO NPs were characterized by using different techniques such as ICP-OES, XPS, TEM, HRTEM, and XRD methods. A different ligand based monodisperse Pt (0) nanocatalysts have been compared with each other and commercial catalysts in terms of catalytic performance, life-time and reusability of catalyst for methanol oxidation reaction in THF at room temperature. All experimental results demonstrate the highly stable and reusable rGO furnished Pt (0) nanomaterials and their excellent catalytic performance in the methanol oxidation reactions at room temperature. 相似文献
92.
Erol Kurt Francesco Cottone Yunus Uzun Francesco Orfei Maurizio Mattarelli Davut Özhan 《International Journal of Hydrogen Energy》2017,42(28):17813-17822
The features of the new designed and constructed harvester are examined. The harvested power of three piezoelectric layers having different masses (i.e. different natural frequencies) has been explored. These layers have the same length around the harvester body, whereas a permanent magnet (PM) attached to the shaft rotates by low speed wind and this PM repels these three piezoelectric layers with a 120° phase shift. Since PM and the PMs located to the tip of the layers do not contact, this system improves the lifetime of the harvester. The measured harvested power in the low wind speeds (i.e. 1.75 m/s) is of the order of 0.2 μW. The waveform includes many subharmonic and superharmonic components, hence the total harmonic distortion (THD) is found around 130%, which is fairly high due to nonlinear effects. Although the system shows an high THD, the 20% of the signal can be rectified and stored in the capacitor for the use of harvested energy. A scenario has also been created for a resistive load of RL = 1 MΩ and 100 kΩ for various wind speeds and it has been proven that the harvester can feed the load at even lower wind speeds. In addition, extra power beyond the usage of the load can be stored into the capacitor. The proposed harvester and its rectifying unit can be a good solution for the energy conversion procedures of low-power required machines. 相似文献
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通过有限元方法(FEA)分析强化复合板的非线性屈曲行为。该模型中硼-铝复合材料由硼基体和嵌入其中的不同形态的Al纤维组成。对片层结构的B-Al矩形板施加横向压缩应力,发现强化纤维对具有不同几何形状板材的屈曲行为有明显影响。建模中采用单向、具有矩形截面的强化纤维。结果表明:加载过程中存在一重要的载荷范围,临界屈曲模式在稳态和非稳态之间反复转变。确定由不同的纤维形态和板材高宽比组成的分叉失稳区域。通过ANSYS有限元计算,研究简支边界条件下强化板材的失稳模式,分别得到压应力(σx)与平面收缩(u)以及压应力(σx)与面外挠度(δ)的关系曲线。通过非线性分析,在C1、C2、C3和C4四种形态的纤维中,嵌入C2纤维的板材获得最安全的临界屈服应力。结果表明,FEA非线性屈曲分析可以得到精确的结果。 相似文献
96.
Kinetics of adsorption of dyes from aqueous solution using activated carbon prepared from waste apricot 总被引:1,自引:0,他引:1
Onal Y 《Journal of hazardous materials》2006,137(3):1719-1728
Adsorbent (WA11Zn5) has been prepared from waste apricot by chemical activation with ZnCl(2). Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N(2) adsorption and DFT plus software. Adsorption of three dyes, namely, Methylene Blue (MB), Malachite Green (MG), Crystal Violet (CV), onto activated carbon in aqueous solution was studied in a batch system with respect to contact time, temperature. The kinetics of adsorption of MB, MG and CV have been discussed using six kinetic models, i.e., the pseudo-first-order model, the pseudo-second-order model, the Elovich equation, the intraparticle diffusion model, the Bangham equation, the modified Freundlich equation. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation could describe the adsorption kinetics for three dyes. The dyes uptake process was found to be controlled by external mass transfer at earlier stages (before 5 min) and by intraparticle diffusion at later stages (after 5 min). Thermodynamic parameters, such as DeltaG, DeltaH and DeltaS, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures and concentrations. The thermodynamics of dyes-WA11Zn5 system indicates endothermic process. 相似文献
97.
Yunus E.M. Spearing S.M. McBride J.W. 《Components and Packaging Technologies, IEEE Transactions on》2009,32(3):650-657
Carbon nanotube (CNT)-coated surfaces are investigated to determine the electrical contact performance under low force conditions. The surfaces under investigation are vertically aligned multiwalled CNTs formed on a silicon substrate and coated with an Au film. These planar surfaces are mated with a hemispherical Au plated probe mounted in a nanoindentation apparatus. The maximum contact force used is 1 mN. The contact resistance of these surfaces is investigated as a function of the applied force and is also studied under repeated loading cycles. The surfaces are compared with a reference Au-Au contact under the same experimental conditions and the results compared to established contact theory. The results show that the vertically aligned multiwalled CNT surface provides a stable contact resistance. This paper shows the potential for the application of CNT surfaces as an interface in low force electrical contact applications. 相似文献
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99.
Berksoy-Yavuz Ayse Kaya Mustafa Yunus Avcı Tubanur Cakırbas Gizem Menşur Ebru 《Journal of Materials Science: Materials in Electronics》2022,33(5):2336-2349
Journal of Materials Science: Materials in Electronics - The effect of crystallographic texture on the properties of 0.94(Na0.5Bi0.5TiO3)–0.06BaTiO3 (0.94NBT–0.06BT) ceramics were... 相似文献
100.
Yunus Emre Yuksel Murat Ozturk Ibrahim Dincer 《International Journal of Hydrogen Energy》2021,46(30):16344-16359
Increasing environmental concerns and decreasing fossil fuel sources compel engineers and scientists to find resilient, clean, and inexpensive alternative energy options Recently, the usage of renewable power resources has risen, while the efficiency improvement studies have continued. To improve the efficiency of the plants, it is of great significance to recover and use the waste heat to generate other useful products. In this paper, a novel integrated energy plant utilizing a geothermal resource to produce hydrogen, ammonia, power, fresh water, hot water, heated air for drying, heating, and cooling is designed. Hydrogen, as an energy carrier, has become an attractive choice for energy systems in recent years due to its features like high energy content, clean, bountiful supply, non-toxic and high efficiency. Furthermore in this study, hydrogen beside electricity is selected to produce and stored in a hydrogen storage tank, and some amount of hydrogen is mixed with nitrogen to compound ammonia. In order to determine the irreversibilities occurring within the system and plant performance, energy and exergy analyses are then performed accordingly. In the design of the plant, each sub-system is integrated in a sensible manner, and the streams connecting sub-systems are enumerated. Then thermodynamic balance equations, in terms of mass, energy, entropy and exergy, are introduced for each unit of the plant. Based on the system inputs and outputs, the energy and exergy efficiencies of the entire integrated plant is found to be 58.68% and 54.73% with the base parameters. The second part of the analysis contains some parametric studies to reveal how some system parameters, which are the reference temperature, geothermal resource temperature and mass flow rate, and separator inlet pressure in the geothermal cycle, affect both energy and exergy efficiencies and hence the useful outputs. 相似文献