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International Conference on Space Optics 2008, ICSO 2008

作者： Cheng, L. Ahlers, B. Toet, P. Casarosa, G. Appolloni, M. TNO Science and Industry Optics Stieltjesweg 1 Delft2600 AD Netherlands TNO Science and Industry Space and Science Stieltjesweg 1 Delft2600 AD Netherlands AOES Netherlands B.V. Huygensstraat 34 Noordwijk2201 DK Netherlands

ISBN: (纸本)9781510616219

Fibre Bragg Grating (FBG) sensor systems based on optical fibres are gaining interest in space applications. Studies on Structural Health Monitoring (SHM) of the reusable launchers using FBG sensors have been carried out in the Future European Space Transportation Investigations Programme (FESTIP). Increasing investment in the development on FBG sensor applications is foreseen for the Future Launchers Preparatory Programme (FLPP). TNO has performed different SHM measurements with FBGs including on the vEGA interstage [1, 2] in 2006. Within the current project, a multi-parameter FBG sensor array demonstrator system for temperature and strain measurements is designed, fabricated and tested under ambient as well as Thermal vacuum (Tv) conditions in a Tv chamber of the European Space Agency (ESA), ESTEC site. The aim is the development of a multi-parameters measuring system based on FBG technology for space applications. During the Tv tests of a Space Craft (S/C) or its subsystems, thermal measurements, as well as strain measurements are needed by the engineers in order to verify their prediction and to validate their models. Because of the dimensions of the test specimen and the accuracy requested to the measurement, a large number of observation/measuring points are needed. Conventional sensor systems require a complex routing of the cables connecting the sensors to their acquisition unit. This will add extra weight to the construction under test. FBG sensors are potentially light-weight and can easily be multiplexed in an array configuration. The different tasks comply of a demonstrator system design;its component selection, procurement, manufacturing and finally its assembly. The temperature FBG sensor is calibrated in a dedicated laboratory setup down to liquid nitrogen (LN2) temperature at TNO. A temperature-wavelength calibration curve is generated. After a test programme definition a setup in thermal vacuum is realised at ESA premises including a mechanical stra

关键词： Fiber Bragg gratings

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Asymmetric Waveguide design of Laser Diodes for Pico-and Nanosecond Pulse Generation in the Eye Safe Spectral Range: Linear and Nonlinear Electromagnetic Effects

Asymmetric Waveguide Design of Laser Diodes for Pico-and Nan...

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Progress in Electromagnetic Research Symposium

作者： E. A. Avrutin B. S. Ryvkin J. T. Kostamovaara Department of Electronics University of York York UK A. F. Ioffe Physico-Technical Institute St. Petersburg Russia Department of Electrical and Information Engineering University of Oulu Oulu Finland

High energy optical pulse generation using semiconductor lasers has attracted significant attention recently, for applications such as high-precision laser radars, three-dimensional time imaging, spectroscopy, and lifetime studies. Depending on the resolution required, pulses of either several to several tens of nanoseconds or ~ 100 picoseconds in duration can be required. In the former case, from the laser dynamics point of view, the laser is operating in a steady state with a transient at the start of the pulse;in the latter case, the main techniques used are gain switching (pumping the laser with a current pulse of a nanosecond duration or somewhat shorter, but still significant ly longer than the desired optical pulse), active or passive Q-switching (using a laser incorporating an active voltage-controlled modulator or a saturable absorber respectively), or a combination of these techniques. In our recent work (see [1,2] and references therein), we have used gain-switched Fabry-Perot asymmetric-waveguide semiconductor lasers with a large equivalent spot size d/τ_a ≥ 1μm (d being the active layer thickness and τ_a, the active layer confinement factor). A saturable absorber can be monolithically integrated within the laser cavity to facilitate high-energy afterpulse-free optical pulse emission in a broad range of injection current pulse amplitudes by combined gain- and Q-switching. optical pulses with a peak power of about 35 W and a duration of about 80 ps at half maximum, without a substantial afterpulse structure, were achieved with a current pulse with an amplitude of just 8 A and a duration of 1.5 ns. Good quality, afterpulsing-free optical pulses were observed in a broad range of elevated temperatures. It has also been shown [3] that a similarly asymmetric laser structure, with a Quantum Well active layer, is advantageous for quasi-CW operation (that is, pumped by current pulses long enough for the output power transients to die out, but short enough to

关键词： optical waveguides Laser radar optical pulses optical pumping optical pulse generation

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A temperature compensated fibre Bragg grating (FBG)-based sensor system for condition monitoring of electrified railway pantograph 25

A temperature compensated fibre Bragg grating (FBG)-based se...

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25th International Conference on optical Fibre Sensors (OFS)

作者： Chen, Ye vidakovic, Miodrag Fabian, Matthias Swift, Martin Brun, Lee Sun, Tong Grattan, Kenneth T. v. City Univ London Sch Math Comp Sci & Engn London England Brecknell Willis Millfield TA20 2DA Chard England

ISBN: (纸本)9781509048502

This paper presents the results obtained from fibre Bragg grating (FBG) sensors integrated into a railway current-collecting pantograph for accurate measurement of contact force and contact location when it is subjected to various temperature conditions. The temperature change of the pantograph is simulated, at the industrial laboratory of Brecknell Willis in the UK, by changing the DC current applied to pantograph from 0 to 1500 A. This test is primarily designed to verify the effectiveness of the temperature compensation mechanism built in the FBG sensor design. For this verification, 3 thermocouples co-located with the FBG sensor packages are used to measure the temperature change seen from 25 degrees C to 55 degrees C. The tests were repeated several times and the sensor system has shown its temperature-independence, confirming that the intrinsic cross-sensitivity of FBGs to temperature variation for strain measurement has been fully compensated through the use of this innovative sensor design and data processing.

关键词： Fibre Bragg Grating (FBG) Sensors railway pantograph condition monitoring electrified pantograph

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Microbial fuel cells: recent developments in design and materials

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IOP Conference Series: Materials Science and engineering 2018年第1期330卷

作者： G Bhargavi v venu S. Renganathan Department of Biotechnology Anna University Chennai Tamilnadu – 600025 India. Department of Mechanical Engineering Marri Laxman Reddy Institute of Technology and Management Duindigal Hyderabad Telangana – 500043 India.

Microbial Fuel Cells (MFCs) are the promising devices which can produce electricity by anaerobic fermentation of organic / inorganic matter from easily metabolized biomass to complex wastewater using microbes as biocatalysts. MFC technology has been found as a potential technology for electricity generation and concomitant wastewater treatment. However, the high cost of the components and low efficiency are barricading the commercialization of MFC when compared with other energy generating systems. The performance of an MFC is largely relying on the reactor design and electrode materials. On the way to improve the efficiency of an MFC, tremendous exercises have been carried out to explore new electrode materials and reactor designs in recent decades. The current review is excogitated to amass the progress in design and electrode materials, which could bolster further investigations on MFCs to improve their performance, mitigate the cost and successful implementation of technology in field applications as well.

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Laser-written polarizing directional coupler with reduced interaction length

arXiv

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arXiv 2017年

作者： Dyakonov, I.v. Saygin, M.Yu. Kondratyev, I.v. Kalinkin, A.A. Straupe, S.S. Kulik, S.P. Faculty of Physics M.V. Lomonosov Moscow State University Leninskije Gory 1 Moscow119991 Russia

Integrated optical devices are becoming a common tool in modern optical science and engineering. This devices should be designed to allow for precise control and manipulation of light. The femtosecond laser written (FSLW) photonic chips have proven to cope with the most current demands of integrated photonics. However, up to date the polarization degree of freedom has rarely been exploited in experiments performed on the FSLW integrated platform. The main obstacle is an intrinsically low anisotropy of laser written waveguides, preventing the design of polarizing integrated devices with small footprint. In this Letter we demonstrate the approach based on stress-induced anisotropy allowing us to decrease the size of polarizing directional couplers fabricated with the FSLW technology by almost an order of magnitude. We provide an accurate account for the effects emerging in waveguides written in a close proximity to each over. Copyright © 2017, The Authors. All rights reserved.

关键词： Directional couplers

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Towards Self-testing Quantum Random Number Generators in Integrated design

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IOP Conference Series: Materials Science and engineering 2018年第1期454卷

作者： P S Chernov v S volkov D A Surovtsev Penza State University Krasnaya 40 Penza Russian Federation

Truly random numbers are in great demand in various applications. Self-testing quantum random number generators provide a way to verify that random numbers indeed come from quantum effects. optical quantum random number generators of this type are the most promising but due to their relative complexity have been realized only as a macroscopic prototype. Miniaturization of such devices opens the way to commercial use. Quantum photonics provides the means to achieve this goal. We discuss general design of self-testing optical quantum random number generator and the ways to implement it as a compact integrated photonic circuit within current technological reach.

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Proceedings of SPIE - The International Society for optical engineering

Proceedings of SPIE - The International Society for Optical ...

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current developments in Lens design and optical engineering XvII

ISBN: (纸本)9781510602861

The proceedings contain 35 papers. The topics discussed include: some methods for determining the limit of potential image quality of optical systems of various complexities using the database;optical design of an ultrashort throw ratio projector with two freeform mirrors;reduce volume of head-up display by image stitching;optical performance of a PDMS tunable lens with automatically controlled applied stress;fabrication of focus-tunable liquid crystal microlens array with spherical electrode;characterization of a tunable liquid-filled lens with minimum spherical aberration;design of a radiance meter with predicted size of source and distance effects;formation of the color image based on the vidicon Tv camera;AND efficient 3M PBS enhancing miniature projection optics.

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design, Fabrication, and Application of GaN-Based Micro-LED Arrays With Individual Addressing by N-Electrodes

IEEE PHOTONICS JOURNAL

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IEEE PHOTONICS JOURNAL 2017年第6期9卷

作者： Xie, Enyuan Stonehouse, Mark Ferreira, Ricardo McKendry, Jonathan J. D. Herrnsdorf, Johannes He, Xiangyu Rajbhandari, Sujan Chun, Hyunchae Jalajakumari, Aravind v. N. Almer, Oscar Faulkner, Grahame Watson, Ian M. Gu, Erdan Henderson, Robert O'Brien, Dominic Dawson, Martin D. Univ Strathclyde Dept Phys Inst Photon Glasgow G1 1RD Lanark Scotland Univ Oxford Dept Engn Sci Oxford OX1 3PJ England Univ Edinburgh CMOS Sensors & Syst Grp Edinburgh EH9 3JL Midlothian Scotland Coventry Univ Sch Comp Elect & Math Ctr Mobil & Transport Coventry CV1 2JH W Midlands England

We demonstrate the development, performance, and application of a GaN-based micro-light emitting diode (mu LED) array sharing a common p-electrode (anode), and with individually addressable n-electrodes (cathodes). Compared to conventional GaN-based LED arrays, this array design employs a reversed structure of common and individual electrodes, which makes it innovative and compatible with n-type metal-oxide-semiconductor (NMOS) transistor-based drivers for faster modulation. Excellent performance characteristics are illustrated by an example array emitting at 450 nm. At a current density of 17.7 kA/cm(2) in direct-current operation, the optical power and small signal electrical-to-optical modulation bandwidth of a single mu LED element with 24 mu m diameter are over 2.0 mW and 440 MHz, respectively. The optimized fabrication process also ensures a high yield of working mu LED elements per array and excellent element-to-element uniformity of electrical/optical characteristics. Results on visible light communication are presented as an application of an array integrated with an NMOS driver. Data transmission at several hundred Mb/s without bit error is achieved for single-and multiple-mu LED-element operations, under an ON-OFF-keying modulation scheme. Transmission of stepped sawtooth waveforms is also demonstrated to confirm that the mu LED elements can transmit discrete multilevel signals.

关键词： GaN micro-light emitting diode array Individual addressing by n-electrodes visible light communication

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Setting up new chemical engineering degree programmes: Exercises in design and retrofit within constraints

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EDUCATION FOR CHEMICAL ENGINEERS 2016年 17卷 1-13页

作者： Campbell, Grant M. Belton, Daniel J. Univ Huddersfield Sch Appl Sci Huddersfield HD1 3DH W Yorkshire England

The rise in popularity of chemical engineering among students entering university has prompted expansion of the UK provision, through increased intake into current degree programmes and with the rise of new providers. The former entails logistical challenges of processing larger numbers through existing infrastructures whilst maintaining the student experience. The latter entails challenges of designing and introducing programmes that build harmoniously on existing non-chemical engineering provision, within the constraints of university validation procedures and physical resources, and in the face of uncertainty around student and staff recruitment, while aspiring to implement best practice in chemical engineering content and pedagogy. Following a review of the UK chemical engineering landscape and a critique of literature guidance on the appropriate content of chemical engineering curricula, this paper illustrates the issues of new programme development through the approaches and experiences of a new provider, the University of Huddersfield, which introduced new chemical engineering programmes from academic year 2013-2014. The paper addresses specifying the content of chemical engineering programmes to align with accreditation requirements and literature advice while maintaining distinctiveness. The constraints imposed by the need to specify and validate courses internally and to minimise substantive programme changes subsequently, whilst responding to the opportunities that arise as staff are recruited and to external developments and unplanned incidents, are highlighted and illustrated, in order to draw lessons that might help to guide other new entrants. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.v. All rights reserved.

关键词： Programme design Curriculum Accreditation validation design project Laboratory infrastructure

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Electromagnetic actuators for medium voltage vacuum switching devices: Classification, design, controlling 18

Electromagnetic actuators for medium voltage vacuum switchin...

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18th International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic engineering, ISEF 2017

作者： Klymenko, Borys v. Pantelyat, Michael G. Department for Electrical Apparatus National Technical University Kharkiv Polytechnic Institute Kharkiv Ukraine

ISBN: (纸本)9781538616611

vacuum switching devices (circuit breakers and contactors) dominate the current market of medium voltage devices. In the paper a classification of electromagnets and actuators which are used in Mv vacuum switching devices is presented. Peculiarities, advantages and disadvantages of bistable and monostable electromagnets and actuators are analyzed. Information on the developments of the authors as well as the results of theoretical and experimental investigations of new designs of polarized monostable electromagnet actuators are presented and analyzed. Relevant microprocessor controlling devices and methods of switching windings allowing to create effective designs of Mv vacuum switching devices are described. The results of investigations have been tested on several prototypes of circuit breakers and contactors which were presented at various exhibitions. The proposed solutions on the design of bistable actuators with monostable polarized electromagnets, ways to control windings of such electromagnets as well as varistor degaussing of windings at their disconnection by transistor switches are tested experimentally on single prototypes and worth discussing the possibility of their industrial application after the full-scale tests on a sufficient number of vacuum contactors and circuit breakers. © 2017 IEEE.

关键词： Electromagnets

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