Papers by Keyword: Reflector

Abstract: This work investigates the radiation pattern of a 5 GHz antenna composed of a metal dipole antenna and surrounded by fluorescent tubes which act as reflectors (plasma medium). The study emphasizes the role of plasma reflectors in improving the antenna’s efficiency by controlling the radiation pattern. The electrical parameters of the plasma medium are modeled by Drude model in Comsol Multyphysics for different voltage discharges. Also, a CST software is used to simulate metallic dipole antenna reconfigurability. The results show that the plasma can be used as a good reflector when its permittivity is negative () and . Moreover, it is shown that with increasing the discharge voltage, the plasma reflectivity increases, this is because the gain increases and the directivity of the antenna considerably changes. Keywords: Reflector, Plasma, COMSOL, CST, Gain, Directivity.

Abstract: KENS-II is the second generation of the spallation neutron source at KEK which was operated from December 1, 2000 to March 22, 2006 supplying neutron beam to the neutron spectrometers of material science. The present paper reviews history of the KENS-II from its design to removal together with its performance for the neutron scattering experiments.

Abstract: The neutron transmutation doping (NTD) of silicon is usually used for producing different electronic devices like thyristors, VLSI, detectors, etc. This article focuses on the formation of the radiation field to create the technology for silicon NTD implementing a pool-type nuclear reactor. The works includes the analytical consideration of the conditions for achieving the high radial irradiation uniformity of silicon ingots.

Abstract: Over the past decade, the studies have been growing rapidly on application of Synthetic Aperture Radar Interferometry (InSAR) technology to landslide deformation monitoring. On the basis of InSAR ground reflector, the paper has improved the design, produced a new InSAR reflector and successfully applied to Three Gorges Reservoir Shuping Landslide deformation monitoring.

Abstract: Rapid determination of soil moisture in the arid area has important ecological significance and practical value. This study carried out a series of measurements in the alpine meadow of Urumqi Southern Mountain on April 28^th, 2011 right after the snow melt. Ground-penetrating radar (GPR), time domain reflectometry (TDR) were used simultaneously for measuring the soil moisture of a 50 × 50 m² plot, and a vertical soil profile was dug for validation analysis. The results show that: (1) a clear and continuous reflective layer in the experimental plot can be found from the GPR radar data and have a depth range from 0.362 to 0.656 m, while the GPR calculated average soil moisture above this layer is approximate 0.191 ~ 0.341; (2) TDR derived soil moistures of surface 10 cm and 20 cm depth show a consistent distribution with GPR measurements, and the former is slightly higher than the latter is likely to be due to the snow melt water accumulated more in the surface layer and not transferred immediately to the deep; (3) the vertical soil profile displays a actual compacted layer which is just at same position with the corresponding GRP measured reflective layer, and the TDR measured average soil moisture above this layer is only 0.001 less than the GPR derived data. The results give fully demonstrates to the accuracy of GPR reflected wave model to measure soil reflector and average moisture, which provides a scientific and effective technique for field-scale soil moisture and structure studies.

Abstract: The paper aims to study the deformation and compensation of the reflector for RF-excited diffusion-cooled CO₂ laser. Based on ANSYS, the thermal deformation and compensation of the reflector have been calculated, It has been proved that the effect of temperature compensation is obvious, and can correct the thermal deformation of the reflector to the tolerance of the parameter of optical cavity.

Abstract: LED gradually replaces light source in many fields, it becomes more and more important. For the purpose of letting LED more effective, people usually use secondary optical lens to improve the optical quality. In this research, reflector and lens are used to compose a LED light module. In this study, a LED module is designed to meet the specific requirement of the illumination. It was found that changing lens thickness and lens position can improve the uniformity and the size of light patch. As a result, we found parameters about lens for best results. In the design process, we realized that uniformity can be increased by decreasing D10 value of the light. The best result of simulation was found (which are in the form of point data). We used polynomials to fit the contour of LED module of point data and used it to extend the reflector contour of calculated results. The size of light patch of LED contour with reflector-masked and point data is much smaller than with polynomials.

Abstract: This research focuses on the effect manufacture factors about the brightness and uniformity of multi-stage reflector. Trace-pro and 3D CAD model were used for optical simulations. The optical simulation results of grating lens and reflector were done as well as successfully developed the LED fog lamp. The results meet the regulations, R19 CLASS F3, of Economic Commission for Europe (ECE) at the test distance of 25 meters, and central zone under line6 achieves average over 3200cd. The optimal design of reflector is of third-order paraboloidal one to improve the brightness and uniformity. The acuter the microstructure’s tip is(R below 0.1mm), the better the apparent improving of eliminating stray light. In accordance with microstructure of grating lens, Moldex-3D is used to help the mold flow filling simulation and mold design. The mold cavity with microstructure was manufactured by the wire cutting and polishing processing. And the molding plastic was optics level PC (Polycarbonate). Both Taguchi’s method applied in Moldex-3D and real injection molding experiments showed that high melt temperature, low injection speed and suitable holding time can reduce warpage; in addition, using higher melt temperature, mold temperature and injection pressure can achieve higher degree of replication of micro features.

Abstract: In this paper, we review the basic properties of resonant leaky mode elements implemented with periodic waveguide layers and consider their applicability in photonic devices and systems. Leaky waveguide modes can be exited when an incident light beam is coupled into the waveguide structure through an inscribed periodicity under phase-matching conditions. This results in generation of a guided-mode resonance field response in the spectrum. Device operation can be explained in terms of the photonic band structure and associated leaky-wave effects near the second stop band. Resonant devices such as bandpass/bandstop filters, polarizers, wideband reflectors, biosensors, tunable filters, and display pixels can be designed using this operational principle.

Abstract: NURBS surface representation, combined with Differential Evolution (DE), enables us to perform automated non-imaging reflector design. The overall result is a simple automated nonimaging reflector design technique and only a little data such as desired illuminance distribution and searching limits are needed. Merit functions specific to non-imaging reflector design are presented. Using different merit functions, the generated illuminance distribution can be uniform as well as concentrated. DE is performed to obtain the reflector that generates the desired illuminance distribution. The photometric distributions are calculated through Monte-Carlo ray tracing and the illuminance value is used to calculate the merit function value. The validity of the proposed approach is demonstrated by optimization examples. Almost the same uniform illuminance distribution can be obtained using the algorithm proposed in this paper as that obtained by edge-raymethod. A concentrated illuminance distribution can also be generated using the algorithm proposed.