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排序方式: 共有866条查询结果,搜索用时 62 毫秒
731.
732.
733.
Ian McAuley J. Anthony Murphy Darragh McCarthy Marcin Gradziel Ronan Mahon Creidhe O’Sullivan Neil Trappe 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(4):340-355
In this paper, we discuss how a holographic interference technique can be applied in the experimental determination of the phase centers of non-standard horn antennas in the millimeter-waveband. The phase center is the point inside the horn from which the radiation appears to emanate when viewed from the far-field, and knowing its location is necessary for optimizing coupling efficiencies to quasi-optical systems. For non-standard horn designs, and other feed structures, the phase center may be difficult to reliably predict by simulation, in which case, before committing to antenna manufacture, there is a requirement for it to be determined experimentally. Although the phase center can be recovered by direct phase measurement of the far-field beam pattern, this usually involves expensive instrumentation such as a vector network analyzer for millimeter wave horn antennas. In this paper, we describe one inexpensive alternative, which is based on measuring the interference pattern in intensity between the radiation from the horn of interest and a reference beam derived from the same coherent source in an off-axis holography setup. The accuracy of the approach is improved by comparison with the interference pattern of a well-understood standard horn (such as a corrugated conical horn) in the same experimental setup. We present an example of the technique applied to a profiled smooth-walled horn antenna, which has been especially designed for cosmic microwave background (CMB) polarization experiments. 相似文献
734.
Justyna Zygmuntowicz Justyna Tomaszewska Radosław Żurowski Marcin Wachowski Ireneusz Szachogłuchowicz Paulina Piotrkiewicz Waldemar Kaszuwara Katarzyna Konopka 《Ceramics International》2021,47(13):18053-18064
The main goal of this study was to optimize the technological process of forming and sintering Zirconia Toughened Alumina (ZTA) composites in terms of reducing energy demand. Based on the results of Life Cycle Assessment carried out according to ISO 14044 and EN 15805 standards, the elimination of preliminary homogenization of ceramic suspension in the planetary mill, allowed to reduce energy consumption by over 25%. The method of forming ZTA materials by CSC method, allowed to obtain finished tube-shaped products, which did not require any mechanical treatment after sintering. Such an approach may be an alternative solution for production of ZTA pipes that can be used in transport of aggressive substances, even in extreme corrosive or temperatures conditions. 相似文献
735.
Marcin Stec Andrzej Czaplicki Grzegorz Tomaszewicz Krzysztof Słowik 《Korean Journal of Chemical Engineering》2018,35(1):129-136
The addition of carbon dioxide to the gasification media during lignite gasification is introduced. The paper presents thermodynamic grounds of CO2 enhanced gasification using a simplified equilibrium model. Experimental tests conducted using a pilot-scale circulating fluidized bed gasifier are discussed. Detailed analysis of the CO2/C ratio on process conditions, namely on the process gas composition, lower heating value and H2/CO ratio, is provided. Process gas composition implies that the gas is suitable for heat and power generation. Alternatively, CO2 enhanced gasification could be considered as a carbon capture and utilization technology when external, renewable heat supply to the process is used. The results thus obtained are the initial step toward development of the CO2 enhanced gasification process. 相似文献
736.
Paweł Wajer Edyta Woźniak Wlodek Kofman Marcin Rybicki Stanisław Lewiński 《International journal of remote sensing》2018,39(9):2671-2689
This study uses the ray tracing method to simulate synthetic aperture radar (SAR) images of urban areas. The images are constructed for polarisations: horizontal-horizontal (HH) and vertical-vertical (VV), and different types of buildings, vegetation, and streets. Simulated images of a given area are compared with real SAR images of the same area acquired by the TerraSAR-X satellite. The simulations use the measured backscatter coefficient for HH and VV polarisations and for five different classes of terrain: houses, trees, shrubs, grass, and ground. For multiple reflections, we apply the generalized bistatic Lambertian model. The results show that, despite the limits of the ray tracing method and the approximations involved in modelling three-dimensional objects in the simulated scene, the simulated SAR images correspond well with the actual scene. All features present in the real image are reproduced in the simulated image; in particular, the double reflections of buildings and the surrounding ground appear clearly. However, discrepancies exist, and these are also discussed. 相似文献
737.
Sabine Payr Marcin Skowron Anna Dobrosovestnova Martin Trapp Robert Trappl 《控制论与系统》2017,48(8):576-596
Conversational robots and agents are being designed for educational and/or persuasive tasks, e.g., health or fitness coaching. To pursue such tasks over a long time, they will need a complex model of the strategic goal, a variety of strategies to implement it in interaction, and the capability of strategic talk. Strategic talk is incipient ongoing conversation in which at least one participant has the objective of changing the other participant’s attitudes or goals. The paper is based on the observation that strategic talk can stretch over considerable periods of time and a number of conversational segments. Film dialogues are taken as a source to develop a model of the strategic talk of mentor characters. A corpus of film mentor utterances is annotated on the basis of the model, and the data are interpreted to arrive at insights into mentor behavior, especially into the realization and sequencing of strategies. 相似文献
738.
739.
van der Linden PJ Mathon O Strohm C Sikora M 《The Review of scientific instruments》2008,79(7):075104
We have developed a versatile experimental apparatus for synchrotron x-ray measurements in pulsed high magnetic fields. The apparatus consists of a double cryostat incorporating a liquid nitrogen bath to cool the miniature pulsed coil and an independent helium flow cryostat allowing sample temperatures from 4 up to 250 K. The high duty cycle miniature pulsed coils can generate up to 38 T. During experiments at 30 T a repetition rate of 6 pulsesmin was routinely reached. Using a 4 kJ power supply, the pulse duration was between 500 mus and 1 ms. The setup was used for nuclear forward scattering measurements on 57Fe up to 25 T on the ESRF beamline ID18. In another experiment, x-ray magnetic circular dichroism was measured up to 30 T on the ESRF energy dispersive beamline ID24. 相似文献
740.
Jolanta Gilewicz-Wolter Joanna Dudała Zbigniew Żurek Marta Homa Jerzy Lis Marcin Wolter 《Journal of Phase Equilibria and Diffusion》2005,26(5):561-564
As a result of the oxidation of chromium (Cr)-manganese (Mn) steels, a multilayer scale is formed. The intermediate layer of this scale is composed of MnCr2O4 spinel, and the outer layer is composed of MnO. The aim of the current study is to examine self-diffusion processes in MnCr2O4 spinel by a tracer method. In experiments, the radioisotopes 54Mn, 51Cr, and 59Fe were used. The serial sectioning method was applied for the simultaneous evaluation of diffusion rates of Cr, Mn, and iron (Fe) in MnCr2O4 spinel at 1173 K under a pressure of 105 Pa in SO2 containing 10 Pa O2. This spinel was obtained by a modified sol-gel method from metal nitrates (R. Gajerski and Z. Zurek, personal communication, 14.04.2004). It was found that the dominant mechanism of Mn transport in the studied samples is a volume diffusion, while Cr and Fe are transported mainly through the high-diffusivity paths. 相似文献