The Experts below are selected from a list of 49998 Experts worldwide ranked by ideXlab platform
Yoon Young Kim - One of the best experts on this subject based on the ideXlab platform.
-
Waveguide tapering for Beam-Width control in a waveguide transducer.
Ultrasonics, 2013Co-Authors: Young Eui Kwon, Hyun Joong Jeon, Hoe Woong Kim, Yoon Young KimAbstract:In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow Beam Width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-Beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the Beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow Beam Width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.
Young Eui Kwon - One of the best experts on this subject based on the ideXlab platform.
-
Waveguide tapering for Beam-Width control in a waveguide transducer.
Ultrasonics, 2013Co-Authors: Young Eui Kwon, Hyun Joong Jeon, Hoe Woong Kim, Yoon Young KimAbstract:In a waveguide transducer that transmits an ultrasonic wave through a waveguide unit to a test structure, it is most preferred to send a non-dispersive ultrasonic wave of a narrow Beam Width. However, there is an unresolved conflict between the generation of the non- or less-dispersive wave and the transmission of a narrow-Beam wave into a test structure. Among others, the thickness of the waveguide unit in a waveguide transducer is the key variable determining these two conflicting criteria, but the use of a uniformly-thick waveguide of any thickness cannot fulfill the two conflicting criteria simultaneously. In this study, we propose a specially-engineered tapered waveguide unit for the simultaneous satisfaction. An excitation unit is installed at the end of the thin region of the tapered waveguide and generates only the lowest non-dispersive shear-horizontal wave. Then the generated wave propagates through the tapered region of the waveguide unit and reaches the thick region of the waveguide with insignificant mode conversion to higher modes. If the tapered waveguide is used, the surviving lowest mode in the thick region of the waveguide is shown to carry most of the transmitted power and is finally propagated into a test structure. Because the Beam size of the propagated wave and the thickness of the contacting waveguide region are inversely related, the thick contacting region of the tapered waveguide ensures narrow Beam Width. Numerical and experimental investigations were performed to check the effectiveness of the proposed waveguide-tapering approach.
Claude Fabre - One of the best experts on this subject based on the ideXlab platform.
-
Quantum uncertainty in the Beam Width of spatial optical modes.
Optics express, 2015Co-Authors: Vanessa Chille, Peter Banzer, Andrea Aiello, Gerd Leuchs, Christoph Marquardt, Nicolas Treps, Claude FabreAbstract:We theoretically investigate the quantum uncertainty in the Beam Width of transverse optical modes and, for this purpose, define a corresponding quantum operator. Single mode states are studied as well as multimode states with small quantum noise. General relations are derived, and specific examples of different modes and quantum states are examined. For the multimode case, we show that the quantum uncertainty in the Beam Width can be completely attributed to the amplitude quadrature uncertainty of one specific mode, which is uniquely determined by the field under investigation. This discovery provides us with a strategy for the reduction of the Beam Width noise by an appropriate choice of the quantum state.
S. Crewell - One of the best experts on this subject based on the ideXlab platform.
-
biases caused by the instrument bandWidth and Beam Width on simulated brightness temperature measurements from scanning microwave radiometers
Atmospheric Measurement Techniques, 2013Co-Authors: V. Meunier, U. Löhnert, P. Kollias, S. CrewellAbstract:Abstract. More so than the traditional fixed radiometers, the scanning radiometer requires a careful design to ensure high quality measurements. Here the impact of the radiometer characteristics (e.g., antenna Beam Width and receiver bandWidth) and atmospheric propagation (e.g. curvature of the Earth and vertical gradient of refractive index) on scanning radiometer measurements are presented. A forward radiative transfer model that includes all these effects to represent the instrument measurements is used to estimate the biases. These biases are estimated using differences between the measurement with and without these characteristics for three commonly used frequency bands: K, V and W-band. The receiver channel bandWidth errors are less important in K-band and W-band. Thus, the use of a wider bandWidth to improve detection at low signal-to-noise conditions is acceptable at these frequencies. The biases caused by omitting the antenna Beam Width in measurement simulations are larger than those caused by omitting the receiver bandWidth, except for V-band where the bandWidth may be more important in the vicinity of absorption peaks. Using simple regression algorithms, the effects of the bandWidth and Beam Width biases in liquid water path, integrated water vapour, and temperature are also examined. The largest errors in liquid water path and integrated water vapour are associated with the Beam Width errors.
-
Biases caused by the instrument bandWidth and Beam Width on simulated brightness temperature measurements from scanning microwave radiometers
Atmospheric Measurement Techniques Discussions, 2012Co-Authors: V. Meunier, U. Löhnert, P. Kollias, S. CrewellAbstract:Abstract. More so than the traditional fixed radiometers, the scanning radiometer requires a careful design to ensure high quality measurements. Here the impact of the radiometer characteristics (e.g. antenna Beam Width, receiver bandWidth) and atmospheric propagation (e.g. curvature of the earth and refractivity) on the scanning radiometer measurements are presented. A forward radiative transfer model that includes all these effects to represent the instrument measurements is used to estimate the biases as differences between the measurement with and without these characteristics for three commonly used frequency bands: K, V and W-band. The receiver channel bandWidth errors are not so important in K-band and W-band. Thus, the use of a wider bandWidth to improve detection at low signal-to-noise conditions is acceptable. The impact of the antenna Beam Width is higher than the receiver bandWidth, but, for V-band where they are of similar importance. Using simple regression algorithms, the effects of the bandWidth and Beam Width biases in liquid water path, integrated water vapor, and temperature are also examined. The largest errors in liquid water path and integrated water vapor are associated with the Beam Width errors.
Jun Shang Kuang - One of the best experts on this subject based on the ideXlab platform.
-
exterior rc wide Beam column connections effect of Beam Width ratio on seismic behaviour
Engineering Structures, 2017Co-Authors: Hamdolah Behnam, Jun Shang Kuang, Roy Y C HuangAbstract:Abstract Design recommendations stipulated in international standards for seismic design of reinforced concrete (RC) wide Beam-column connections are based on limited experimental studies. To supplement the existing information, an experimental study was conducted that focused on the effect of Beam Width to column Width ratio (or Beam Width ratio) on the seismic behaviour of exterior Beam-column connections. Four specimens were designed, constructed and tested under reversed cyclic loading conditions. The primary test variables were the Beam Width ratio and the joint shear stress ratio ( γ d ). The specimens were designed in conformance with ACI 318-14 and ACI 352R-02. They had Beam Width ratios of 1, 1.5, 2 and 2.5 and γ d , of 0.74, 1.12, 1.63, and 2.03. According to ACI 352R-02, the γ d value should be lower than γ n = 1.25 for joints confined on three faces. The results indicated that specimens with Beam Width ratios of 1 and 1.5 and γ d of 0.74 and 1.12 were capable of supporting the complete formation of Beam plastic hinges with no major cracks in the joint region. In contrast, specimens with Beam Width ratios of 2 and 2.5 and γ d of 1.63 and 2.03 exhibited significant damage at the joint core. Torsional failure of the spandrel Beam was also observed in specimen with Beam Width ratio of 2.5.
-
Effective Beam Width of reinforced-concrete wide Beam-column connections
Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2017Co-Authors: Jun Shang Kuang, Hamdolah Behnam, Qunxian HuangAbstract:The reinforced-concrete wide-Beam floor system is recognised as one of the most efficient Beam-and-slab floor systems in buildings. However, potential advantages of the system as a lateral load-resisting structure are often ignored due to a lack of understanding of the seismic behaviour of wide Beam–column connections. Design codes prescribe Beam Width limitations to minimise the shear lag effect on the formation of full-Width plastic hinges and achieving the expected capacity. However, owing to insufficient experimental and analytical studies, empirical design formulas for the Beam Width limitation, with remarkably different results, have been implemented in different design codes. In this paper, parametric studies of the influence of key parameters on the behaviour of wide Beam–column connections are conducted based on available test results. An effective Beam-Width model is analytically developed using the equivalent-frame representation, where the effects of torsion of transverse Beams and flexure aro...