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1.
Sinem Palantken Emre Tekay Sinan en Turgut Nugay Nihan Nugay 《Polymer Composites》2016,37(9):2770-2781
A novel method based on cryoscopic expansion of halloysite nanotubes via frozen water molecules entrapped in their lumens and subsequent lyophilization was described. Detailed analyses confirmed that the inner and outer diameters as well as the surface area of the nanotubes could be efficiently increased without disturbing the inherent tubular structure. The benefits of cryo‐expanded nanotubes for the enhancement of chitosan hydrogel performances were discussed. The composite hydrogels, depending on their compositions and morphologies, exhibited significantly enhanced swelling and mechanical properties compared with neat chitosan hydrogel. This effect was even more pronounced in the hydrogels containing cryo‐expanded halloysite nanotubes. Although neat chitosan is a selectively good adsorbent for anionic dyes, in the presence of a small amount of cryo‐expanded halloysite, the resultant composite hydrogel can establish a relatively high adsorption capacity for anionic and cationic dyes as a broad‐spectrum dye adsorbent. POLYM. COMPOS., 37:2770–2781, 2016. © 2015 Society of Plastics Engineers 相似文献
2.
Rohat MelikEmre Unal Nihan Kosku PerkgozChristian Puttlitz Hilmi Volkan Demir 《Microelectronic Engineering》2011,88(3):247-253
In this paper, we present and demonstrate RF-MEMS load sensors designed and fabricated in a suspended architecture that increases their quality-factor (Q-factor), accompanied with an increased resonance frequency shift under load. The suspended architecture is obtained by removing silicon under the sensor. We compare two sensors that consist of 195 μm × 195 μm resonators, where all of the resonator features are of equal dimensions, but one’s substrate is partially removed (suspended architecture) and the other’s is not (planar architecture). The single suspended device has a resonance of 15.18 GHz with 102.06 Q-factor whereas the single planar device has the resonance at 15.01 GHz and an associated Q-factor of 93.81. For the single planar device, we measured a resonance frequency shift of 430 MHz with 3920 N of applied load, while we achieved a 780 MHz frequency shift in the single suspended device. In the planar triplet configuration (with three devices placed side by side on the same chip, with the two outmost ones serving as the receiver and the transmitter), we observed a 220 MHz frequency shift with 3920 N of applied load while we obtained a 340 MHz frequency shift in the suspended triplet device with 3920 N load applied. Thus, the single planar device exhibited a sensitivity level of 0.1097 MHz/N while the single suspended device led to an improved sensitivity of 0.1990 MHz/N. Similarly, with the planar triplet device having a sensitivity of 0.0561 MHz/N, the suspended triplet device yielded an enhanced sensitivity of 0.0867 MHz/N. 相似文献
3.
Jianyang Zheng Yinhai Wang Nancy L. Nihan & Mark E. Hallenbeck 《Computer-Aided Civil and Infrastructure Engineering》2006,21(6):425-435
Abstract: Signal cycle failure (or overflow) is an interrupted traffic condition in which a number of queued vehicles are unable to depart due to insufficient capacity during a signal cycle. Cycle failure detection is essential for identifying signal control problems at intersections. However, typical traffic sensors do not have the capability of capturing cycle failures. In this article, we introduce an algorithm for traffic signal cycle failure detection using video image processing. A cycle failure for a particular movement occurs when at least one vehicle must wait through more than one red light to complete the intended movement. The proposed cycle failure algorithm was implemented using Microsoft Visual C#. The system was tested with field data at different locations and time periods. The test results show that the algorithm works favorably: the system captured all the cycle failures and generated only three false alarms, which is approximately 0.9% of the total cycles tested. 相似文献
4.
Sasan?Amini Kristian?Beckers Markus?B?hm Fritz?Busch Nihan?Celikkaya Vittorio?Cozzolino Anne?Faber Michael?Haus Dominik?Huth Alfons?Kemper Andreas?Kipf Helmut?Krcmar Florian?MatthesEmail author J?rg?Ott Christian?Prehofer Alexander?Pretschner ?mer?Uluda? Wolfgang?W?rndl 《Informatik-Spektrum》2017,40(2):180-191
5.
Summary
Polymerisation of methyl methacrylate was conducted by using alkyl lithium/dimethylsulfoxide (DMSO) system as initiator in
toluene. A special attention was focused on using some lithium polyetheralkoxides as polymerisation promoters at ambient temperatures.
Poly(methyl methacrylate) samples were characterized with Gel Permeation Chromatography (GPC), Nuclear Magnetic Resonance
Spectroscopy (1H NMR) and Differential Scanning Calorimetry (DSC). The positive effect of the μ/σ type ligands such as lithium 2-(2-methoxyethoxy)ethoxide
(LiOEEM), 2-(methoxy)ethoxide (LiOEM) on controlling the living character, molecular weight, stereo regularity and the yield
of the produced polymers was demonstrated. It has been found that this approach provided high polymerisation yields and low
polydispersity but low initiator efficiency.
Received: 9 April 2002 / Revised version: 10 May 2002 / Accepted: 15 June 2002 相似文献
6.
There is a worldwide interest in renewable electricity technologies (RETs) due to growing concerns about global warming and climate change. As an EU candidate country whose energy demand increases exponentially, Turkey inevitably shares this common interest on RET. This study, using an aggregate economic equilibrium model, explores the economic costs of different policy measures to mitigate CO2 emissions in Turkey. The model combines energy demands, capital requirements and labor inputs at a constant elasticity of substitution under an economy-wide nested production function. Growing energy demand, triggered by economic growth, is met by increased supply and initiates new capacity additions. Investment into RET is encouraged via the incorporation of (a) endogenous technological learning through which the RET cost declines as a function of cumulative capacity, and (b) a willingness to pay (WTP) function which imposes the WTP of consumers as a lower bound on RET installation. The WTP equation is obtained as a function of consumer income categories, based on data gathered from a pilot survey in which the contingent valuation methodology was employed. The impacts of various emission reduction scenarios on GDP growth and RET diffusion are explored. As expected, RET penetration is accelerated under faster technological learning and higher WTP conditions. It is found that stabilizing CO2 emissions to year 2005 levels causes economic losses amounting to 17% and 23% of GDP in the years 2020 and 2030, respectively. 相似文献
7.
Nihan Kaya Ferhat Arslan Zeynep Yildiz Uzun 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(10):769-780
AbstractIn this study, hazelnut shell and walnut shell which are the agricultural wastes existent abundantly in many countries were pyrolyzed at different temperatures in the temperature range of 400–700?°C in order to optimize the physicochemical properties of biochars. The biochars with large surface area were used to removal of lead (Pb2+) ions, one of the most important heavy metal pollutant, from aqueous solutions. The characterization of raw biomass and also biochars produced by pyrolysis were performed using FT-IR, BET, SEM, partial and elemental analysis techniques. In order to determine the adsorption characteristics of both biochars, batch adsorption experiments were carried out under different experimental conditions. The optimum conditions were determined by investigating the effect of adsorption parameters (initial heavy metal concentration, temperature, adsorbent amount, pH, contact time and mixing speed) for efficient removal of Pb2+ ions from aqueous solution. The experimental results were investigated in terms of Langmuir, Freundlich and Temkin isotherm models. Together with the calculated thermodynamic parameters, the adsorption mechanism was tried to be explained. In order to determine the kinetic model of the adsorption process, the experimental data were applied to pseudo first-order, pseudo second-order and intra-particle diffusion model, and the model constants were investigated. 相似文献
8.
4‐vinylpyridine monomer was mixed with organophilic montmorillonite (MMT) clay and polymerized in the presence of free‐radical initiator. MMT clay was rendered organophilic by means of ion‐exchanging sodium cations for low‐molecular‐weight quaternized poly(4‐vinylpyridine) (P4VP) homopolymer and diblock copolymers of styrene and quaternized 4‐vinylpyridine (SVP) with different sequence lengths. The swelling behaviour of the MMT clay was studied by X‐ray diffraction (XRD). After the cation exchange, the resulting organophilic clays showed an expansion of interlayer distance indicating the nanoscale ordering of intercalant polymer and MMT layers. The nanocomposite materials, when moulded, exhibited improved thermal stability and dynamic mechanical properties compared with neat P4VP. The composite, having longer ionic segments in its organophilic MMT, showed exfoliated nanocomposite structure as well as higher stiffness and damping properties at higher temperatures even for MMT loading as low as 2 wt%. Copyright © 2006 Society of Chemical Industry 相似文献
9.
M. Güneş M. E. D. Yavas J. Klomfass F. Finger 《Journal of Materials Science: Materials in Electronics》2010,21(2):153-159
Effects of native and light induced defects states in hydrogenated amorphous silicon–germanium alloy thin films with different
Ge concentrations have been investigated by using steady-state photoconductivity, dual beam photoconductivity (DBP), transmission
spectroscopy and photothermal deflection spectroscopy (PDS) techniques. In the annealed state, sub-bandgap absorption spectra
obtained from both PDS and DBP overlap very well at energies above 1.4 eV. However, differences in α (hν) spectrum exist in
the lower energy part of absorption spectrum. The α (hν) value measured at 1.0 eV is the lowest for 10% Ge sample and increases
gradually as Ge content of the sample increases. In the light soaked state, time dependence of photoconductivity decay obeys
to t
−x
power law, where x changes from 0.30 to 0.60 for samples with low Ge content and 0.05–0.1 for samples with high Ge content. Correspondingly,
the increase of the sub-bandgap absorption coefficient at lower energies obeys to t
y
power law, where y values are lower than the x value of the same sample. It can be inferred that sub-bandgap absorption and photoconductivity measurements are not controlled
by the same set of defects created in the bandgap of alloys. 相似文献
10.
Phenacyl benzoylpyridinium (PBP) salts are effective photoinitiatiors for cationic polymerization. In this study, it is shown that PBP salts are stable in their keto forms, and undergo a reversible keto–enol tautomerization reaction when a capillary action is applied. Spectroscopic and theoretical methods are used to explain the existence of the enol forms in the capillary tube. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry 相似文献