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71.
It is of great interest to replace the K2TiF6 salt so as to reduce the volume of fluoride-bearing particulate material to be added to the aluminium melt in the popular “halide salt” process. Ti sponge was used in the present work as the source of Ti in the production of an Al–5Ti–1B grain refiner. Addition of Ti granules into molten aluminium, either premixed with or before KBF4 salt, has produced Al–5Ti–1B alloys where the boride particles were relatively few and predominantly of the AlB2 type. The grain refining efficiency of these alloys were far from satisfactory. TiB2 was the dominant boride phase with sufficient number of blocky aluminide particles when Ti, in excess of the TiB2 stoichiometry was supplied before hand and the balance was reserved for co-addition with KBF4. Al3Ti particles were generated soon after the Ti solubility limit was exceeded in the first step while the boride particles were subsequently produced by the reaction between molten aluminium, KBF4 and K2TiF6. The Al–5Ti–1B master alloy thus produced provided an adequate grain refining performance while the amount of particulate material to be added to the aluminium melt was reduced by nearly 30%. 相似文献
72.
73.
A new analytical approach for obtaining the time samples of the retarded-time scalar and vector potentials due to an impulsively excited Rao-Wilton-Glisson (RWG) basis function is presented. The approach is formulated directly in the time-domain without any assumptions regarding the temporal behavior of the currents represented by the RWG bases. To the best knowledge of the authors, analytical evaluation of the potential integrals due to the RWG bases have not been formulated prior to the present work either in the time domain or the frequency domain. It is shown that the aforementioned potentials are related to the arc segments formed by the intersection of the triangular supports of the RWG basis and the sphere that is centered at the observation point and that has a radius R=ct, where c is the speed of light. In particular, the scalar potential is directly proportional to the total arc length and the vector potential is a function of the bisectors of these arc segments. A simple algorithm to evaluate these quantities is also presented. The validity of the obtained time-domain formulae is demonstrated through comparison of results to those obtained in the frequency domain by using numerical quadrature and transformed into time domain. 相似文献
74.
The noniterative method of adaptive channel equalization proposed by Butler and Cantoni [1] is investigated. Its start-up time is improved remarkably by choosing the period of the training sequence judiciously and performing the estimation of channel parameters exactly over one period. The resulting version of the algorithm is as fast as the fastest known iterative algorithms, such as Godard's Kaiman algorithm [2]. 相似文献
75.
Seda Aksoy Atila Yucel Yalcin Elerman Thorsten Krenke Mehmet Acet Xavier Moya Lluís Maosa 《Journal of Alloys and Compounds》2008,460(1-2):94-98
Gd5Si2Ge2 was alloyed with varying amounts of Ga to study its influence on the giant magnetocaloric effect. Investigations on Gd5(Si2−xGe2−x)Ga2x with 2x = 0.03, 0.05 and 0.13 were carried out using X-ray powder diffraction, temperature and magnetic field dependent magnetization measurements, and differential scanning calorimetry. We observe that as the Ga content increases, the temperature stability range of the monoclinic phase narrows, and the orthorhombic structure gains stability. This is expected to be related to the decrease in the (Si/Ge)(Si/Ge) bond distance in the monoclinic phase. The maximum entropy change for the parent compound at 270 K was found to be 9.8 J kg−1 K−1 in an applied field of 5 T. For 2x = 0.03, this value reduces to 8.5 J kg−1 K−1, and the temperature corresponding to the maximum entropy change shifts marginally to 278 K. For other 2x values, the maximum entropy change further decreases. 相似文献
76.
Danckert James; Maruff Paul; Ymer Carley; Kinsella Glynda; Yucel Murat; de Graaff Steven; Currie Jon 《Canadian Metallurgical Quarterly》2000,14(1):16
Competing visual stimuli lead to slower responses to targets. This response competition must be resolved before correct responses are executed. Neuroimaging suggests that response competition monitoring may be subserved by an integrated neural network including the anterior cingulate cortex (ACC). In this study, 1 patient with a parietal lesion (Patient J.S.) and 1 with an ACC lesion (Patient G.M.) were presented with 2 flanker tasks; 1 required verbal identification of color targets, and the other required an opposite response to targets (e.g., see red and say "green"); a control group was also tested. For controls, perceptually incongruent flankers interfered with the ability to inhibit prepotent responses to targets. Patient J.S. performed in a similar manner, even when flankers appeared in the neglected field. Patient G.M. demonstrated reduced interference effects for contralesional flankers. Results are discussed in terms of goal-directed selective attention and response competition monitoring. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
Emrah Sagir Siamak Alipour Kamal Elkahlout Harun Koku Ufuk Gunduz Inci Eroglu Meral Yucel 《International Journal of Hydrogen Energy》2017,42(36):22743-22755
Photofermentative hydrogen production by immobilized Rhodobacter capsulatus YO3 was carried out in a novel photobioreactor in sequential batch mode under indoor and outdoor conditions. Long-term H2 production was realized in a 1.4 L photobioreactor for 64 days using Rhodobacter capsulatus YO3 immobilized with 4% (w/v) agar on 5 mM sucrose and 4 mM glutamate. The highest hydrogen yield (19 mol H2/mol sucrose) and hydrogen productivity (0.73 mmol H2 L?1 h?1) were achieved indoors on 5 mM sucrose. The effect of initial sucrose concentration (5 mM, 10 mM, and 20 mM) on hydrogen production was also investigated. Sustained hydrogen production was carried out under natural, outdoor conditions as well. For the outdoor experiments, the highest hydrogen productivity and yield were obtained as 0.87 ± 0.06 mmol H2 L?1 h?1 and 6.1 ± 0.2 mol H2/mol sucrose, respectively on 10 mM sucrose. Furthermore, this system prevented sudden pH drops and fluctuations caused by the utilization of sucrose throughout the process. These results demonstrate that a proper immobilization setup can lead to long-term efficient and robust hydrogen production even under naturally varying conditions. 相似文献
78.
Metin Gencten Hurmus Gursu Yucel Sahin 《International Journal of Hydrogen Energy》2017,42(40):25598-25607
In this study, the effect of α-alumina (α-Al2O3) and γ-alumina (γ-Al2O3) on the precipitation of the positive electrolyte, which is one of the most important problems in vanadium redox battery (VRB) systems, was investigated. α-Al2O3 and γ-Al2O3 were used as additive materials to improve the thermal stability of V(V) ion and the performance of VRB at high temperatures. Cyclic voltammetry and electrochemical impedance spectroscopy were used to determine the properties of positive electrolyte systems. The optimum amount of additives was identified as wt% 0.004 and 0.010 for α-Al2O3 and γ-Al2O3, respectively. The surface morphology and composition of electrodes were investigated by scanning electron microscopy and energy-dispersive X-ray analysis. A plausible reaction mechanism was also proposed for redox reaction occurring on the positive electrode of a VRB. The adsorption of V(V) ions to the electrode surface from the solution increased by the time additives were added into the system. γ-Al2O3 showed the best anti-precipitation effects for the V(V) ion at 40 °C and 60 °C in the precipitation tests. In the battery test, the discharge capacity of γ-Al2O3 with a positive electrolyte, was the highest at 87.2 mAh. According to thermal and electrochemical studies, γ-Al2O3 can be a useful additive for the positive electrolyte of a VRB. 相似文献
79.
Yucel Can Severcan 《International Planning Studies》2015,20(3):251-269
This paper discusses barriers to civic engagement of disadvantaged young people that we observed in the course of a child-friendly city project in Turkey. It also emphasizes the importance of being prepared to overcome such barriers, some of which were quite unexpected. Results show that many of the unexpected issues are the outcome of poverty, illiteracy, lack of ethics, inexperience of project managers, conflicting political interests and sense of insecurity. The paper concludes with suggestions for researchers and policy-makers on how to overcome such unforeseen barriers to child and youth participation in disadvantaged communities. 相似文献
80.
G. Yildirim S. Bal E. Yucel M. Dogruer M. Akdogan A. Varilci C. Terzioglu 《Journal of Superconductivity and Novel Magnetism》2012,25(2):381-390
This study deals with the effect of Mn addition on the structural and superconducting properties of Bi1.8Pb0.4Sr2Mn
x
Ca2.2Cu3.0O
y
ceramics with x=0,0.03,0.06,0.15,0.3 and 0.6 by means of X-ray analysis (XRD), scanning electron microscopy (SEM), electron dispersive X-ray
(EDX), resistivity, and transport critical current density (J
c) measurements. Zero-resistivity transition temperatures (T
c) of the samples produced via the standard solid-state reaction method are estimated from the dc resistivity measurements.
Moreover, the phase fraction and lattice parameters are determined from XRD measurements while the microstructure, surface
morphology and element composition analyses of the samples are investigated by SEM and EDX measurements, respectively. It
is found that T
c values are obtained to decrease from 109 K to 85 K; likewise, J
c values are observed to reduce from 3200 A/cm2 to 125 A/cm2 with increasing Mn addition. According to the refinement of cell parameters done by considering the structural modulation,
the Mn addition is confirmed by both an increase of the lattice parameter a and a decrease of the cell parameter c of the samples in comparison with that of the pure sample (Mn0). SEM measurements show that not only the surface morphology
and grain connectivity are seen to degrade but the grain sizes of the samples are found to decrease with the increase of the
Mn addition as well. The EDX results reveal that the elements used for the preparation of samples distribute homogeneously
and the Mn atoms enter into the crystal structure by replacing Sr and Cu atoms. The possible reasons for the obtained degradation
in microstructural and superconducting properties are also interpreted. 相似文献