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27th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2016

作者： Lane, B. Mekhontsev, S. Grantham, S. Vlasea, M.L. Whiting, J. Yeung, H. Fox, J. Zarobila, C. Neira, J. McGlauflin, M. Hanssen, L. Moylan, S. Donmez, A. Rice, J. Engineering Laboratory National Institute of Standards and Technology GaithersburgMD20899 United States Physical Measurement Laboratory National Institute of Standards and Technology GaithersburgMD20899 United States Mechanical and Mechatronics Engineering University of Waterloo WaterlooONN2L 3GI Canada

The National Institute of Standards and Technology (NIST) is developing a facility titled the Additive Manufacturing Metrology Testbed that will enable advanced research into monitoring, controls, process development, and temperature measurement for laser powder bed fusion additive manufacturing and similar processes. This system provides an open control architecture as well as a plethora of sensor systems and calibration sources that are primarily radiance-based and aligned co-axially with the laser beam and focused on the laser interaction zone. This paper briefly reviews the system requirements, and details the current progress of the facility design and construction. Mechanical, optical, and control systems designs are detailed with select highlights that may be relevant to additive manufacturing researchers and system developers. Recent experimental results from the prototype laser control and in-situ monitoring system are also highlighted. © 2016 The Department of Energy’s Kansas City National Security Campus is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839.

关键词： 3D printers

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Biphysical undetectable concentrators manipulating both heat flux and direct current via topology optimization

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Physical Review E 2022年第6期106卷 065304-065304页

作者： Garuda Fujii Institute of Engineering Shinshu University Nagano 380-8553 Japan and Energy Landscape Architectonics Brain Bank (ELab2) and Interdisciplinary Cluster for Cutting Edge Research Shinshu University Nagano 380-8553 Japan

Recent remarkable developments in metamaterials and metadevices manipulating diffusive processes, such as thermal and electrical conduction, have enabled the control of multiple phenomena and the development of multifunctional devices. However, only either multiphysics operations or multiple functionalities are usually implemented on single metadevices. In this paper, we describe a method for the optimal design of metadevices that achieves both cloaking and focusing in the control of both heat flux and direct current by a single device, i.e., biphysical-bifunctional metadevices having four capabilities. Our design scheme performs well in terms of providing cloaking and focusing bifunctionality. Additionally, it assumes bulk natural materials without the use of metamaterials, which improves the manufacturability of the designed metadevices. Moreover, multidirectional metad evices are optimally designed for thermal-electrical conductions transmitted from multiple directions or from heat and voltage sources at various locations.

关键词： Cloaking optical cloaking

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design And Fabrication Of In-plane Ridge Waveguide Surface Emitting Lasers With Two Dry Etched 45/spl deg/ Total Reflection Mirrors

Design And Fabrication Of In-plane Ridge Waveguide Surface E...

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LEOS Summer Topical Meetings

作者： C.P. Chao K.-K. Law J.L. Merz Department of Electrical and Computer Engineering University of California슠Santa Barbara Santa Barbara CA USA

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Advanced optical sensor performance in transmission and distribution applications

Proceedings of the IEEE Power Engineering Society Transmissi...

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Proceedings of the IEEE Power engineering Society Transmission and Distribution Conference 1999年 1卷 259-265页

作者： Cruden, A. Michie, W.C. Niewczas, P. Madden, W.I. McDonald, J.R. Andonovic, I. Univ of Strathclyde Glasgow United Kingdom

This paper reports on recent developments within research into optical fibre based voltage and current measurement equipment for metering and protection applications. Several parameters (thermal variations, intensity fluctuations due to mechanical disturbance, electronic noise) are known to influence the performance of these sensors and this paper summarises an analysis of the effect of such disturbances providing design criteria for the realisation of protection and metering class OCTs. Laboratory trials have shown that the compensation schemes devised reduce vibration errors by 20 to 30 dB and compensate for temperature induced drift to better than 0.1%. Extended engineering evaluation field trials of both OCT and OVT devices within a three phase 132 kV installation have been undertaken over the past two years. Details of these trials are presented to provide an appreciation of the potential difficulties which may be encountered and the benefits which may be derived.

关键词： optical sensors

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Third harmonic generation in optical microcavities [recurso eletrônico] : Geração de terceiro harmônico em microcavidades ópticas / Jorge Henrique Soares.

Third harmonic generation in optical microcavities [recurso ...

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作者： Soares, Jorge Henrique, 1991- Universidade Estadual de Campinas

The interaction between light and matter occurs due to electric polarization which can be described as a power series of the electric field. A light source sufficiently intense can access high order terms leading to nonlinear phenomena, such as third harmonic generation which recombine three photons in a new one with higher energy. To reach the necessary condition of intensity, we will use the resonant intensification obtained with optical microcavities which can confine thousands of Watts of circulating power in a micrometric volume. Besides the power intensification, the design of the microcavities that we studied has the potential to integration and mass production and enable a mode engineering in order to optimize the couple both between the modes and the source. In this dissertation, we studied silicon dioxide microcavities which present as first nonlinear term the third order term. We start describing the mode theory for couplesd mode due to third order nonlinearity, identifying the parameters that optimize the photon conversion from the infrared mode to the visible mode. The proposed model takes into account the phase-mismatch induced by dispersion, phase-modulation effects and bistability. We propose a technique to compensate the phase-shift and describe the system in phase-matching condition. In the following, we present the experiments done in order to compare the theoretical and experimental results. Although we couldnt reach the maximum photon conversion efficiency regime due to limitation in maximum input power, is possible to identify the effectiveness of the phase-matching method. Meanwhile, we studied the fabrication process to characterize the current method employed by the research group and it was possible to identify deficit and limitation that may be compromising the fabrication result

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Low profile antenna study using the physical optics hybrid method (POHM)

Low profile antenna study using the physical optics hybrid m...

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Antennas and Propagation Society International Symposium

作者： C.S. Kim Y. Rahmat-Samii Department of Electrical Engineering University of California Los Angeles CA USA

POHM is applied to the design of the low-profile IFF (identification of friend or foe) airborne antenna whose height is less than 1 in. The basic idea of the POHM is that the physical optics technique is used to extend the application of the method of moments to a larger class of problems. The POHM program is tested with geometrical optics, geometrical theory of diffraction, and measured data. It is seen that the accuracy of the POHM is quite satisfactory for large ground plates. In the angular region, z>or=0, the accuracy of the POHM is very high because the physical optics currents on the body are included. However, the accuracy decreases because the POHM assumes that no currents exist on the shadow area (z<0) of the surface on the body.< >

关键词： Physical optics optical surface waves Boundary conditions Moment methods Electric potential current density optical design optical computing Physics computing Surface impedance

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Multidisciplinary modeling and design of a space system

Multidisciplinary modeling and design of a space system

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IEEE International Conference on Systems engineering

作者： Tester Robinson Department of Aeronautical Engineering OH USA

The application of concurrent engineering approach to the design of a large flexible space structure is discussed. A full system model using bond graphs incorporating orbital and ballistic dynamics, controls, optics, and vibrational analyses is developed. design of experiment techniques is used to analyze the entire system and determine the optimum set of design parameters. The objective of the design effort involved the simultaneous design of the control algorithm, structural characteristics, and optical geometry. The system size and mass were limited by current space shuttle capabilities. The satellite was required to track the missile plume of an ICBM with minimum line-of-site error, and transmit the position data to earth.< >

关键词： Aerospace control Aerospace simulation Dynamics Large-scale systems

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design and pre-development of an airborne multi-species differential absorption Lidar system for water vapor and HDO isotope, carbon dioxide, and methane observation

Design and pre-development of an airborne multi-species diff...

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2020 International Conference on Space Optics, ICSO 2020

作者： Dherbecourt, J.B. Raybaut, M. Melkonian, J.M. Hamperl, J. Santagata, R. Dalin, M. Lebat, V. Godard, A. Flamant, C. Totems, J. Chazette, P. Pasiskevicius, V. Heinecke, D. Schäfer, H. Strotkamp, M. Geus, J.F. Rapp, S. Sodemann, H. Steen-Larsen, H.C. DPHY ONERA Université ParisSaclay PalaiseauF-91123 France UMR 8190 CNRS-SU-UVSQ Paris France UMR 1572 CEA-CNRSUVSQ Gif-sur-Yvette France Roslagstullsbacken 21 Stockholm10691 Sweden SpaceTech GmbH Seelbachstr. 13 Immenstaad88090 Germany Fraunhofer Institute for Laser Technology Steinbachstr. 15 Aachen52074 Germany InnoLas Laser GmbH Justus-von-Liebig- Ring 8 Krailling82152 Germany Geophysical Institute University of Bergen Bjerknes Centre for Climate Research Bergen Norway

We report on the current design and preliminary developments of the airborne Lidar Emitter and Multi-species greenhouse gases Observation iNstrument (LEMON), which is aiming at probing H2O and its isotope HDO at 1982 nm, CO2 at 2051 nm, and potentially CH4 at 2290 nm, with the Differential Absorption Lidar method (DIAL). The infrared emitter is based on the combination of two Nested Cavity OPOs (NesCOPOs) with a single optical parametric amplifier (OPA) line for high-energy pulse generation. This configuration is enabled by the use of high-aperture periodically poled KTP crystals (PPKTP), which provide efficient amplification in the spectral range of interest around 2 μm with slight temperature adjustments. The parametric stages are pumped with a Nd:YAG laser providing 200 mJ nanosecond double pulses at 75 Hz. According to parametric conversion simulations supported by current laboratory experiments, output energies in the 40 - 50 mJ range are expected in the extracted signal beam whilst maintaining a good beam quality (M2 © 2021 ESA and CNES

关键词： Carbon dioxide

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current status of closed-form Green's functions in layered media composed of natural and artificial materials

Current status of closed-form Green's functions in layered m...

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International Conference on Electromagnetics in Advanced Applications (ICEAA)

作者： M. I. Aksun Aytac Alparslan K. A. Michalski Department of Electrical and Electronics Engineering Koc University Istanbul Turkey Department of Information Technology and Electrical Engineering Swiss Federal Institute of Technology Zurich Switzerland Department of Electrical and Computer Engineering Texas A and M University College Station TX USA

This paper provides an overview of the development of closed-form Green's functions in planar multilayered structures, with an emphasis given to the discrete complex image method (DCIM). In addition to the review of the materials in the literature, the latest developments on DCIM and its applications to artificial materials are also discussed.

关键词： Green's function methods Nonhomogeneous media Algorithm design and analysis Sampling methods Closed-form solution Surface fitting optical design Radio frequency High speed optical techniques Microwave circuits

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Scanning the Issue

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IETE JOURNAL OF RESEARCH 2016年第2期62卷 127-128页

作者： Koul, Shiban K.

The Volume 62, May-June 2016 issue of IETE Journal of Research contains articles on research and developments taking place in the broad areas of Electrical engineering. The paper 'On feasibility conditions for linear interference alignment over cognitive interference channel: A DoF analysis with diversity tradeoff' presents analytical studies related to multiuser opportunistic interference alignment (OIA) scheme in a multiple-antenna cognitive radio network. The paper 'Cost-effective optimal allocation and sizing of active power filters using a new fuzzy-MABICA method', deals with the active power filters in distribution systems. The next paper titled 'Reversible comparator design using quantum dot-cellular automata', presents the design of a reversible building block for a 1-bit comparator and gives its implementation in quantum dot cellular automata (QCA). The next paper on 'Gate Tunneling current Model for NanoscaleMOSFETS with Varying Surface Potential' deals with development of a simple first-order analytical model for evaluating gate tunnelling current through thin dielectrics in Nanoscale MOSFETs. In the paper on 'A physics-based model of double-gate tunnel FET for circuit simulation', an accurate device physics-based model for double-gate tunnel FET (TFET) is developed and integrated with Cadence circuit simulator.

关键词： Comparators (optical)

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