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Sample records for fast microchannel plate

  1. Time response of fast-gated microchannel plates used as x-ray detectors

    International Nuclear Information System (INIS)

    Turner, R.E.; Bell, P.; Hanks, R.; Kilkenny, J.D.; Landen, N.; Power, G.; Wiedwald, J.; Meier, M.

    1990-01-01

    We report measurements of the time response of fast-gated, micro- channel plate (MCP) detectors, using a <10 ps pulsewidth ultra-violet laser and an electronic sampling system to measure time resolutions to better than 25 ps. The results show that framing times of less than 100 ps are attainable with high gain. The data is compared to a Monte Carlo calculation, which shows good agreement. We also measured the relative sensitivity as a function of DC bias, and saturation effects for large signal inputs. In part B, we briefly describe an electrical ''time-of-flight'' technique, which we have used to measure the response time of a fast-gated microchannel plate (MCP). Thinner MCP's than previously used have been tested, and, as expected, show fast gating times and smaller electron multiplication. A preliminary design for an x-ray pinhole camera, using a thin MCP, is presented. 7 refs., 6 figs

  2. Fast microchannel plate detector for particles

    International Nuclear Information System (INIS)

    Wurz, P.; Gubler, L.

    1996-01-01

    In this article we report on the timing capabilities of a new microchannel plate detector we designed and built. The detector assembly has an impedance-matched transition line (50 Ω line resistance) from anode to cable connector which is considerably smaller than other, commercially available solutions and at the same time has about four times the active area. The detector was tested with an alpha particle source and excellent time response was achieved. Using 10 μm pore size channel plates, a rise time of 300 ps and a pulse width of 520 ps are obtained. The details of the signal analysis are also given in the article. copyright 1996 American Institute of Physics

  3. Gain stabilized microchannel plates and a treatment method for microchannel plates

    International Nuclear Information System (INIS)

    1979-01-01

    Microchannel plates having increased gain and significantly improved aging characteristics are provided by forming a thin film of a cesium compound on the channel walls. In an exemplary embodiment, a suface film of cesium hydroxide is applied to the interior wall surfaces of an MCP by saturating the plate with a solution of the compound, then allowing the solvent to evaporate. The cesium hydroxide residue on the walls subsequently is converted to cesium oxide by a high temperature bake. Microchannel plates are used in image amplifiers, radiation detectors and such like equipment. (Auth.)

  4. Monte Carlo simulations of microchannel plate detectors I: steady-state voltage bias results

    Energy Technology Data Exchange (ETDEWEB)

    Ming Wu, Craig Kruschwitz, Dane Morgan, Jiaming Morgan

    2008-07-01

    X-ray detectors based on straight-channel microchannel plates (MCPs) are a powerful diagnostic tool for two-dimensional, time-resolved imaging and timeresolved x-ray spectroscopy in the fields of laser-driven inertial confinement fusion and fast z-pinch experiments. Understanding the behavior of microchannel plates as used in such detectors is critical to understanding the data obtained. The subject of this paper is a Monte Carlo computer code we have developed to simulate the electron cascade in a microchannel plate under a static applied voltage. Also included in the simulation is elastic reflection of low-energy electrons from the channel wall, which is important at lower voltages. When model results were compared to measured microchannel plate sensitivities, good agreement was found. Spatial resolution simulations of MCP-based detectors were also presented and found to agree with experimental measurements.

  5. Micro-channel plates and vacuum detectors

    Energy Technology Data Exchange (ETDEWEB)

    Gys, T., E-mail: Thierry.Gys@cern.ch

    2015-07-01

    A micro-channel plate is an array of miniature electron multipliers that are each acting as a continuous dynode chain. The compact channel structure results in high spatial and time resolutions and robustness to magnetic fields. Micro-channel plates have been originally developed for night vision applications and integrated as an amplification element in image intensifiers. These devices show single-photon sensitivity with very low noise and have been used as such for scintillating fiber tracker readout in high-energy physics experiments. Given their very short transit time spread, micro-channel plate photomultiplier tubes are also being used in time-of-flight and particle identification detectors. The present paper will cover the history of the micro-channel plate development, basic features, and some of their applications. Emphasis will be put on various new manufacturing processes that have been developed over the last few years, and that result in a significant improvement in terms of efficiency, noise, and lifetime performance.

  6. Microchannel plate assembly parameters with micron gaps

    International Nuclear Information System (INIS)

    Demchenkova, A.A.

    1987-01-01

    Performance of chevron microchannel plate assembly with 5 and 15 μm gaps between them has been investigated. The assembly is placed into a vacuum chamber under pressure -6 Torr and irradiated by neutral He and Ar atom beams with 1.5 and 3 keV energies as well as by ultraviolet photons with 147 nm wave length. Dependence of the gain and amplitude resolution on power voltage in plates are measured. The results obtained have shown that microchannel plates permit to obtain the gain up to 3x10 7 and amplitude resolution up to 30% when detecting both atomic particles and ultraviolet photons. The assembly can be effectively used in those cases when it is necessary to use microchannel plates with curved channels

  7. Microchannel plate photodetectors

    International Nuclear Information System (INIS)

    Majka, R.

    1977-01-01

    A review is given the status of development work on photodetectors using microchannel plates (MCP) as the electron gain element. Projections are made and opinions are presented on what might be available in the next few years. Several uses for these devices at ISABELLE are mentioned

  8. Silicon-micromachined microchannel plates

    CERN Document Server

    Beetz, C P; Steinbeck, J; Lemieux, B; Winn, D R

    2000-01-01

    Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of approx 0.5 to approx 25 mu m, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposite...

  9. Silicon-micromachined microchannel plates

    International Nuclear Information System (INIS)

    Beetz, Charles P.; Boerstler, Robert; Steinbeck, John; Lemieux, Bryan; Winn, David R.

    2000-01-01

    Microchannel plates (MCP) fabricated from standard silicon wafer substrates using a novel silicon micromachining process, together with standard silicon photolithographic process steps, are described. The resulting SiMCP microchannels have dimensions of ∼0.5 to ∼25 μm, with aspect ratios up to 300, and have the dimensional precision and absence of interstitial defects characteristic of photolithographic processing, compatible with positional matching to silicon electronics readouts. The open channel areal fraction and detection efficiency may exceed 90% on plates up to 300 mm in diameter. The resulting silicon substrates can be converted entirely to amorphous quartz (qMCP). The strip resistance and secondary emission are developed by controlled depositions of thin films, at temperatures up to 1200 deg. C, also compatible with high-temperature brazing, and can be essentially hydrogen, water and radionuclide-free. Novel secondary emitters and cesiated photocathodes can be high-temperature deposited or nucleated in the channels or the first strike surface. Results on resistivity, secondary emission and gain are presented

  10. Study of a high gain microchannel plate photomultiplier having low statistical gain fluctuations

    International Nuclear Information System (INIS)

    Audier, M.

    1980-12-01

    A new photomultiplier configuration which synthesizes the performances of several models is proposed. The principles of microchannel plate photomultipliers are reviewed. The physical phenomena which limit the electron multiplication process in a microchannel and the detection efficiency of the microchannel plates are investigated. The operation of a herring-bone pattern device and of a system of two microchannel plate photomultipliers are described and characterized [fr

  11. Production of monodispersed Oil-in Water Emulsion Using Crossflow-Type Silicon Microchannel Plate

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, Takahiro.; Komori, Hideaki.; Yonemoto, Toshikuni. [Tohoku University, Miyagi (Japan). Chemical Engineering Department; Nakajima, Mitsutoshi.; Kikuchi, Yuji. [National Food Research Institute, Ibaraki (Japan)

    1999-04-01

    A novel method for continuous productin of monodispersed oil-in-water (O/W) emulsion is developed using acrossflow-type silicaon microchannel plate. On the single crystal silicon plate, a liquid flow path for continuous phase was made, and at each side of th wall of the path an array of regular-sized slits was precisely fabricated. A flat glass plate was tightly attached on the microchannel plate to cover the top of the slits to form the array of microchannels. Regular-sized oil (triolein) droplets were generated by squeezing the oil through the microchannels into the continuous-phase water (0.3 wt% sodium lauryl sulfate solutin) flowing in the liquid path. Oil droplet size is significantly dependent on the microchannel structure, which is identified with the microchannel width, height, and the length of the terrace (a flat area at the microchannel outlet). Three types of microchannel plates having different microchannel structures generate monodispersed emulsions of different average droplet sizes, 16,20, and 48 {mu}m at the watr flow rate of 1.4x10{sup -2}mL{center_dot}min{sup -1}. For the microchannel plate which generates large droplets of 48 {mu}m, increasing the flow rate causes decreasing droplet size. However, for the microchannel plate which generates small droplets of 16 or 20 {mu}m, the size is not affected by the flow rate within the range from 1.4x10{sup -2}to 2.4 mL{center_dot}min{sup -1}. In every case, the droplet size distribution is narrow, and the geometric standard deviation is 1.03 or less. (author)

  12. Study of the electric field inside microchannel plate multipliers

    International Nuclear Information System (INIS)

    Gatti, E.; Oba, K.; Rehak, P.

    1982-01-01

    Electric field inside high gain microchannel plate multipliers was studied. The calculations were based directly on the solution of the Maxwell equations applied to the microchannel plate (MCP) rather than on the conventional lumped RC model. The results are important to explain the performance of MCP's, (1) under a pulsed bias tension and, (2) at high rate conditions. The results were tested experimentally and a new method of MCP operation free from the positive ion feedback was demonstrated

  13. Imaging microchannel plate detectors for XUV sky survey experiments

    International Nuclear Information System (INIS)

    Barstow, M.A.; Fraser, G.W.; Milward, S.R.

    1986-01-01

    Attention is given to the development of microchannel plate detectors for the Wide Field Camera (WFC) XUV (50-300 A) sky survey experiment on Rosat. A novel feature of the detector design is that the microchannel plates and their resistive anode readout are curved to the same radius as the WFC telescope focal surface. It is shown that curving the channel plates is not detrimental to gain uniformity. The paper describes the design of a curved resistive anode readout element and contrasts the present measurements of spatial resolution, global and local uniformity and temperature coefficient of resistance with the poor performance recently ascribed to resistive anodes in the literature. 18 references

  14. Microchannel plates as detectors and amplifiers of x-ray images

    International Nuclear Information System (INIS)

    Wiedwald, J.D.

    1992-08-01

    Two decades of development driven largely by military night vision applications has led to the availability of a wide selection of microchannel plates for use by the scientific community. Microchannel plates (MCPs) are electron multipliers which retain a high degree of spatial resolution making it possible to amplify electron images by factors of 1,000 or more. Plates having 40 mm diameter and intrinsic spatial resolution of 8 μm are readily available. By coating the front surface of a microchannel plate with an x-ray sensitive photocathode material, x-ray images can be detected and amplified. While the detective quantum efficiency is relatively low, the low noise of the MCP (including the ability to construct images by single photon detection) and its high dynamic range make it suitable for some x-ray microscopy applications. The principles of MCP operation and typical performance are discussed. Examples of related applications and commercial capabilities are also presented

  15. Coordinate sensitive detectors based on microchannel plates

    International Nuclear Information System (INIS)

    Gruntman, M.A.

    1984-01-01

    Coordinate-sensitive detectors (CSD) on the basis of microchannel plates permit to determine in a digital form the coordinates of every recorded particle and they are used in different fields of physical experiment. The sensitive surface diameter of such detectors can reach 10 cm, and spatial resolution - 10 μm. In the review provided CSD with microchannel plates are classified according to the ways of coordinate determination, different types of the detectors, pecUliarities of their design and electron flowsheet are described. It is pointed out that there are reasons for introduction of CSD into practice of laboratory physical investigations in various fields, where the particle recorded is electron or is able to form a secondary electron. It is attributed to nuclear physics, physics of electron and atom collisions, optics, mass-spectrometry, electron microscopy, X-ray analysis, investigation of surfaces

  16. Micro-channel plate detector for ultra-fast relativistic electron diffraction

    International Nuclear Information System (INIS)

    Musumeci, P.; Moody, J.T.; Scoby, C.M.; Gutierrez, M.S.; Bender, H.A.; Hilko, B.; Kruschwitz, C.A.; Wilcox, N.S.

    2011-01-01

    Using relativistic ultra-short electron beams to obtain single-shot diffraction patterns holds the promise to yield real-time resolution of atomic motion in an easily accessible environment, such as a university laboratory, at a fraction of the cost of fourth-generation X-ray sources. One of the main issues in bringing this technique to full maturity is the development of efficient detector systems to record the diffraction pattern using a few MeV electron beams. Low noise, high spatial resolution, and single-electron detection capability are all characteristics of an ideal detector. In this paper, we compare the performances of a traditional fluorescent phosphor screen with a detection system based on the micro-channel plate (MCP). Since MCPs are typically used with lower energy electron beams, these tests constitute one of the few experimental data points available on the use of these devices with MeV energy beams.

  17. Micro-channel plate detector for ultra-fast relativistic electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Musumeci, P., E-mail: musumeci@physics.ucla.edu [UCLA Department of Physics and Astronomy, 475 Portola Plaza, Los Angeles, CA, 90095-1547 (United States); Moody, J.T.; Scoby, C.M.; Gutierrez, M.S. [UCLA Department of Physics and Astronomy, 475 Portola Plaza, Los Angeles, CA, 90095-1547 (United States); Bender, H.A.; Hilko, B.; Kruschwitz, C.A.; Wilcox, N.S. [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, NM (United States)

    2011-05-01

    Using relativistic ultra-short electron beams to obtain single-shot diffraction patterns holds the promise to yield real-time resolution of atomic motion in an easily accessible environment, such as a university laboratory, at a fraction of the cost of fourth-generation X-ray sources. One of the main issues in bringing this technique to full maturity is the development of efficient detector systems to record the diffraction pattern using a few MeV electron beams. Low noise, high spatial resolution, and single-electron detection capability are all characteristics of an ideal detector. In this paper, we compare the performances of a traditional fluorescent phosphor screen with a detection system based on the micro-channel plate (MCP). Since MCPs are typically used with lower energy electron beams, these tests constitute one of the few experimental data points available on the use of these devices with MeV energy beams.

  18. Fabrication of open-top microchannel plate using deep X-ray exposure mask made with silicon on insulator substrate

    CERN Document Server

    Fujimura, T; Etoh, S I; Hattori, R; Kuroki, Y; Chang, S S

    2003-01-01

    We propose a high-aspect-ratio open-top microchannel plate structure. This type of microchannel plate has many advantages in electrophoresis. The plate was fabricated by deep X-ray lithography using synchrotron radiation (SR) light and the chemical wet etching process. A deep X-ray exposure mask was fabricated with a silicon on insulator (SOI) substrate. The patterned Si microstructure was micromachined into a thin Si membrane and a thick Au X-ray absorber was embedded in it by electroplating. A plastic material, polymethylmethacrylate (PMMA) was used for the plate substrate. For reduction of the exposure time and high-aspect-ratio fast wet development, the fabrication condition was optimized with respect to not the exposure dose but to the PMMA mean molecular weight (M.W.) changing after deep X-ray exposure as measured by gel permeation chromatography (GPC). Decrement of the PMMA M.W. and increment of the wet developer temperature accelerated the etching rate. Under optimized fabrication conditions, a microc...

  19. Micro-channel plate photon detector studies for the TORCH detector

    Energy Technology Data Exchange (ETDEWEB)

    Castillo García, L., E-mail: lucia.castillo.garcia@cern.ch [CERN, PH Department, CH-1211, Geneva 23 (Switzerland); Laboratory for High Energy Physics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Brook, N.; Cowie, E.N.; Cussans, D. [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom); Forty, R.; Frei, C. [CERN, PH Department, CH-1211, Geneva 23 (Switzerland); Gao, R. [Department of Physics, University of Oxford, Oxford OXI 3RH (United Kingdom); Gys, T. [CERN, PH Department, CH-1211, Geneva 23 (Switzerland); Harnew, N. [Department of Physics, University of Oxford, Oxford OXI 3RH (United Kingdom); Piedigrossi, D. [CERN, PH Department, CH-1211, Geneva 23 (Switzerland); Van Dijk, M. [H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL (United Kingdom)

    2015-07-01

    The Time Of internally Reflected Cherenkov light (TORCH) detector is under development. Charged particle tracks passing through a 1 cm plate of quartz will generate the Cherenkov photons, and their arrival will be timed by an array of micro-channel plate photon detectors. As part of the TORCH R&D studies, commercial and custom-made micro-channel plate detectors are being characterized. The final photon detectors for this application are being produced in a three-phase program in collaboration with industry. Custom-made single-channel devices with extended lifetime have been manufactured and their performance is being systematically investigated in the laboratory. Optical studies for the preparation of beam and laboratory tests of a TORCH prototype are also underway.

  20. One-dimensional position readout from microchannel plates

    International Nuclear Information System (INIS)

    Connell, K.A.; Przybylski, M.M.

    1982-01-01

    The development of a one-dimensional position readout system with microchannel plates, is described, for heavy ion detectors for use in a particle time-of-flight telescope and as a position sensitive device in front of an ionisation counter at the Nuclear Structure Facility. (U.K.)

  1. Variation of microchannel plate resistance with temperature and applied voltage

    International Nuclear Information System (INIS)

    Pearson, J.F.; Fraser, G.W.; Whiteley, M.J.

    1987-01-01

    The resistance of microchannel plate electron multiplier is well known to be a function of both applied voltage and detector temperature. We show that the apparent variation of resistance with bias voltage is simply due to plate temperature increases resulting from resistive heating. (orig.)

  2. Development of a new fast shower maximum detector based on microchannel plates photomultipliers (MCP-PMT) as an active element

    Energy Technology Data Exchange (ETDEWEB)

    Ronzhin, A., E-mail: ronzhin@fnal.gov [Fermilab, Batavia, IL 60510 (United States); Los, S.; Ramberg, E. [Fermilab, Batavia, IL 60510 (United States); Spiropulu, M.; Apresyan, A.; Xie, S. [California Institute of Technology, Pasadena, CA (United States); Kim, H. [University of Chicago, Chicago, IL 60637 (United States); Zatserklyaniy, A. [University of California, Santa Cruz, CA (United States)

    2014-09-21

    One possibility to make a fast and radiation resistant shower maximum (SM) detector is to use a secondary emitter as an active element. We present below test beam results, obtained with different types of photodetectors based on microchannel plates (MCPs) as the secondary emitter. We performed the measurements at the Fermilab Test Beam Facility with 120 GeV proton beam and 12 GeV and 32 GeV secondary beams. The goal of the measurement with 120 GeV protons was to determine time resolution for minimum ionizing particles (MIPs). The SM time resolution we obtained for this new type of detector is at the level of 20–30 ps. We estimate that a significant contribution to the detector response originates from secondary emission of the MCP. This work can be considered as the first step in building a new type of calorimeter based on this principle.

  3. Photon counting with small pore microchannel plates

    International Nuclear Information System (INIS)

    Martindale, A.; Lapington, J.S.; Fraser, G.W.

    2007-01-01

    We describe the operation of microchannel plates (MCPs) with 3.2μm diameter channels as photon counting detectors of soft X-rays. Gain and temporal resolution measurements are compared with theoretical scaling laws for channel diameter. A minimum pulse width of 264ps is observed for a two stage multiplier at a total bias voltage of ∼1930V

  4. Effect of nano-scale morphology on micro-channel wall surface and electrical characterization in lead silicate glass micro-channel plate

    Science.gov (United States)

    Cai, Hua; Li, Fangjun; Xu, Yanglei; Bo, Tiezhu; Zhou, Dongzhan; Lian, Jiao; Li, Qing; Cao, Zhenbo; Xu, Tao; Wang, Caili; Liu, Hui; Li, Guoen; Jia, Jinsheng

    2017-10-01

    Micro-channel plate (MCP) is a two dimensional arrays of microscopic channel charge particle multiplier. Silicate composition and hydrogen reduction are keys to determine surface morphology of micro-channel wall in MCP. In this paper, lead silicate glass micro-channel plates in two different cesium contents (0at%, 0.5at%) and two different hydrogen reduction temperatures (400°C,450°C) were present. The nano-scale morphology, elements content and chemical states of microporous wall surface treated under different alkaline compositions and reduction conditions was investigated by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS), respectively. Meanwhile, the electrical characterizations of MCP, including the bulk resistance, electron gain and the density of dark current, were measured in a Vacuum Photoelectron Imaging Test Facility (VPIT).The results indicated that the granular phase occurred on the surface of microporous wall and diffuses in bulk glass is an aggregate of Pb atom derived from the reduction of Pb2+. In micro-channel plate, the electron gain and bulk resistance were mainly correlated to particle size and distribution, the density of dark current (DDC) went up with the increasing root-mean-square roughness (RMS) on the microporous wall surface. Adding cesiums improved the size of Pb atomic aggregation, lowered the relative concentration of [Pb] reduced from Pb2+ and decreased the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a less dark current. Increasing hydrogen reduction temperature also improved the size of Pb atomic aggregation, but enhanced the relative concentration of [Pb] and enlarged the total roughness of micro-channel wall surface, leading a higher bulk resistance, a lower electron gain and a larger dark current. The reasons for the difference of electrical characteristics were discussed.

  5. Batch production of microchannel plate photo-multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Frisch, Henry J.; Wetstein, Matthew; Elagin, Andrey

    2018-03-06

    In-situ methods for the batch fabrication of flat-panel micro-channel plate (MCP) photomultiplier tube (PMT) detectors (MCP-PMTs), without transporting either the window or the detector assembly inside a vacuum vessel are provided. The method allows for the synthesis of a reflection-mode photocathode on the entrance to the pores of a first MCP or the synthesis of a transmission-mode photocathode on the vacuum side of a photodetector entrance window.

  6. Avalanche transistor pulser for fast-gated operation of micro-channel plate image-intensifiers

    International Nuclear Information System (INIS)

    Lundy, A.; Parker, J.R.; Lunsford, J.S.; Martin, A.D.

    1977-01-01

    Transistors operated in the avalanche mode are employed to generate a 1000 volt 10 to 30 nsec wide pulse with less than 4 nsec rise and fall times. This pulse is resistively attenuated to approximately equal to 270 volts and drives the image intensifier tube which is a load of approximately equal to 200 pf. To reduce stray inductance and capacitance, transistor chips were assembled on a thick-film hybrid substrate. Circuit parameters, operating conditions, and coupling to the microchannel plate image-intensifier (MCPI 2 ) tube are described. To provide dc operating voltages and control of transient voltages on the MCPI 2 tube a resistance-capacitance network has been developed which (a) places the MCPI 2 output phosphor at ground, (b) provides programmable gains in ''f-stop'' steps, and (c) minimizes voltage transients on the MCPI 2 tube

  7. Preliminary studies of microchannel plate photomultiplier tube neutron detectors for flight test applications

    International Nuclear Information System (INIS)

    Dolan, K.W.

    1978-10-01

    Electrical, mechanical, thermal, and neutron response data indicate that microchannel plate photomultiplier tubes are viable candidates as miniature, ruggedized neutron detectors for flight test applications in future weapon systems

  8. A new miniature microchannel plate X-ray detector for synchrotron radiation

    International Nuclear Information System (INIS)

    Rosemeier, R.G.; Green, R.E. Jr.

    1982-01-01

    A state-of-the-art microchannel plate detector has been developed which allows real time X-ray imaging of X-ray diffraction as well as radiographic phenomenon. Advantages of the device include a 50 mm X-ray input, length less than 4'', and a weight of less than 1 lb. Since the use of synchrotron radiation is greatly facilitated by the capability of remote viewing of X-ray diffraction or radiographic images in real time, a prototype electro-optical system has been designed which couples the X-ray microchannel plate detector with a solid state television camera. Advantages of the miniature, lightweight, X-ray synchrotron camera include a large 50 mm X-ray input window, an output signal that is available in both analog format for display on a television monitor and in digital format for computer processing, and a completely modular design which allows all the components to be exchanged for other components optimally suited for the desired applications. (orig.)

  9. Developments in microchannel plate detectors for imaging x-ray astronomy

    International Nuclear Information System (INIS)

    Fraser, G.W.; Whiteley, M.J.; Pearson, J.F.

    1985-01-01

    The authors present new results in four areas of microchannel plate (MCP) X-ray detector operation. The performance in pulse counting mode of MCPs with 8 micron channel diameters is reported. The effects on MCP quantum detection efficiency and energy discrimination of multiple CsI coatings are described. A new mode of operation of two-stage multipliers is evaluated. Replacing the conventional electron-accelerating inter-plate potential difference by a retarding field is shown to result in definite advantages with regard to X-ray energy discrimination and detector lifetime. The source of the MCP internal background is discussed

  10. The parameterization of microchannel-plate-based detection systems

    Science.gov (United States)

    Gershman, Daniel J.; Gliese, Ulrik; Dorelli, John C.; Avanov, Levon A.; Barrie, Alexander C.; Chornay, Dennis J.; MacDonald, Elizabeth A.; Holland, Matthew P.; Giles, Barbara L.; Pollock, Craig J.

    2016-10-01

    The most common instrument for low-energy plasmas consists of a top-hat electrostatic analyzer (ESA) geometry coupled with a microchannel-plate-based (MCP-based) detection system. While the electrostatic optics for such sensors are readily simulated and parameterized during the laboratory calibration process, the detection system is often less well characterized. Here we develop a comprehensive mathematical description of particle detection systems. As a function of instrument azimuthal angle, we parameterize (1) particle scattering within the ESA and at the surface of the MCP, (2) the probability distribution of MCP gain for an incident particle, (3) electron charge cloud spreading between the MCP and anode board, and (4) capacitive coupling between adjacent discrete anodes. Using the Dual Electron Spectrometers on the Fast Plasma Investigation on NASA's Magnetospheric Multiscale mission as an example, we demonstrate a method for extracting these fundamental detection system parameters from laboratory calibration. We further show that parameters that will evolve in flight, namely, MCP gain, can be determined through application of this model to specifically tailored in-flight calibration activities. This methodology provides a robust characterization of sensor suite performance throughout mission lifetime. The model developed in this work is not only applicable to existing sensors but also can be used as an analytical design tool for future particle instrumentation.

  11. Amorphous silicon-based microchannel plates

    International Nuclear Information System (INIS)

    Franco, Andrea; Riesen, Yannick; Wyrsch, Nicolas; Dunand, Sylvain; Powolny, François; Jarron, Pierre; Ballif, Christophe

    2012-01-01

    Microchannel plates (MCP) based on hydrogenated amorphous silicon (a-Si:H) were recently introduced to overcome some of the limitations of crystalline silicon and glass MCP. The typical thickness of a-Si:H based MCPs (AMCP) ranges between 80 and 100 μm and the micromachining of the channels is realized by deep reactive ion etching (DRIE). Advantages and issues regarding the fabrication process are presented and discussed. Electron amplification is demonstrated and analyzed using Electron Beam Induced Current (EBIC) technique. The gain increases as a function of the bias voltage, limited to −340 V on account of high leakage currents across the structure. EBIC maps on 10° tilted samples confirm that the device active area extend to the entire channel opening. AMCP characterization with the electron beam shows gain saturation and signal quenching which depends on the effectiveness of the charge replenishment in the channel walls.

  12. Calculating and optimizing inter-electrode capacitances of charge division microchannel plate detectors

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yan [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Chen, Bo, E-mail: chenb@ciomp.ac.cn [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Zhang, Hong-Ji; Wang, Hai-Feng; He, Ling-Ping [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); Jin, Fang-Yuan [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-04-01

    Based on the principle of charge division microchannel plate detectors, the inter-electrode capacitances of charge division anodes which are related to electronic noise of the charge sensitive amplifier and crosstalk effect of the anode are presented. Under all the requirements of charge division microchannel plate detectors such as the imaging linearity and spatial resolution, decreasing the inter-electrode capacitances is one way to improve the imaging performance. In this paper, we illustrate the simulation process of calculating the inter-electrode capacitances. Moreover, a Wedge and Strip (WSZ) anode is fabricated with the picosecond laser micromachining process. Comparing the simulated capacitances and measured capacitances, the three-dimensional finite element method is proved to be valid. Furthermore, by adjusting the design parameters of the anode, the effects of the substrate permittivity, insulation width and the size of pitch on the inter-electrode capacitances have been analysed. The structure of the charge division anode has been optimized based on the simulation data.

  13. Oscillatory electroosmotic flow in a parallel-plate microchannel under asymmetric zeta potentials

    Science.gov (United States)

    Peralta, M.; Arcos, J.; Méndez, F.; Bautista, O.

    2017-06-01

    In this work, we conduct a theoretical analysis of the start-up of an oscillatory electroosmotic flow (EOF) in a parallel-plate microchannel under asymmetric zeta potentials. It is found that the transient evolution of the flow field is controlled by the parameters {R}ω , {R}\\zeta , and \\bar{κ }, which represent the dimensionless frequency, the ratio of the zeta potentials of the microchannel walls, and the electrokinetic parameter, which is defined as the ratio of the microchannel height to the Debye length. The analysis is performed for both low and high zeta potentials; in the former case, an analytical solution is derived, whereas in the latter, a numerical solution is obtained. These solutions provide the fundamental characteristics of the oscillatory EOFs for which, with suitable adjustment of the zeta potential and the dimensionless frequency, the velocity profiles of the fluid flow exhibit symmetric or asymmetric shapes.

  14. Synthesis of Rh/Macro-Porous Alumina Over Micro-Channel Plate and Its Catalytic Activity Tests for Diesel Reforming.

    Science.gov (United States)

    Seong, Yeon Baek; Kim, Yong Sul; Park, No-Kuk; Lee, Tae Jin

    2015-11-01

    Macro-porous Al2O3 as the catalytic support material was synthesized using colloidal polystyrene spheres over a micro-channel plate. The colloidal polystyrene spheres were used as a template for the production of an ordered macro porous material using an alumina nitrate solution as the precursor for Al2O3. The close-packed colloidal crystal array template method was applied to the formulation of ordered macro-porous Al2O3 used as a catalytic support material over a micro-channel plate. The solvent in the mixture solution, which also contained the colloidal polystyrene solution, aluminum nitrate solution and the precursor of the catalytic active materials (Rh), was evaporated in a vacuum oven at 50 degrees C. The ordered polystyrene spheres and aluminum salt of the solid state were deposited over a micro channel plate, and macro-porous Al2O3 was formed after calcination at 600 degrees C to remove the polystyrene spheres. The catalytic activity of the Rh/macro-porous alumina supported over the micro-channel plate was tested for diesel reforming.

  15. X-ray radiation channeling in micro-channel plates: Spectroscopy with a synchrotron radiation beam

    International Nuclear Information System (INIS)

    Mazuritskiy, M.I.; Dabagov, S.B.; Marcelli, A.; Dziedzic-Kocurek, K.; Lerer, A.M.

    2015-01-01

    We present here the angular distribution of the radiation propagated inside MultiChannel Plates with micro-channels of ∼3 μm diameter. The spectra collected at the exit of the channels present a complex distribution with contributions that can be assigned to the fluorescence radiation, originated from the excitation of the micro-channel walls. For radiation above the absorption edge, when the monochromatic energy in the region of the Si L-edge hits the micro-channel walls with a grazing angle θ ⩾ 5°, or at the O K-edge when θ ⩾ 2° a fluorescence radiation is detected. Additional information associated to the fine structures of the XANES spectra detected at the exit of MCPs are also presented and discussed

  16. A microchannel plate X-ray multiplier with rising-time less than 170 ps

    International Nuclear Information System (INIS)

    Zhao Shicheng; Ouyang Bin

    1987-01-01

    The time reponse of a microchannel plate X-ray multiplier has been improved considerably by using a coupling construction of coaxial tapers. The experimental calibration results with laser plasma X-ray source show that the rising-time of the multiplier is less than 170 ps

  17. Antiproton, positron, and electron imaging with a microchannel plate/phosphor detector

    CERN Document Server

    Andresen, G B; Bowe, P D; Bray, C; Butler, E; Cesar, C L; Chapman, S; Charlton, M; Fajans, J; Fujiwara, M C; Gill, D R; Hangst, J S; Hardy, W N; Hayano, R S; Hayden, M E; Humphries, A J; Hydomako, R; Jørgensen, L V; Kerrigan, S J; Kurchaninov, L; Lambo, R; Madsen, N; Nolan, P; Olchanski, K; Olin, A; Povilus, A; Pusa, P; Sarid, E; Seif El Nasr, S; Silveira, D M; Storey, J W; Thompson, R I; van der Werf, D P; Yamazaki, Y

    2009-01-01

    A microchannel plate (MCP)/phosphor screen assembly has been used to destructively measure the radial profile of cold, confined antiprotons, electrons, and positrons in the ALPHA experiment, with the goal of using these trapped particles for antihydrogen creation and confinement. The response of the MCP to low energy (10-200 eV, <1 eV spread) antiproton extractions is compared to that of electrons and positrons.

  18. Three-dimensional particle-in-cell simulation on gain saturation effect of microchannel plate

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiangqiang; Yuan, Zheng; Cao, Zhurong, E-mail: cao33jin@aliyun.com; Deng, Bo; Chen, Tao; Deng, Keli [Research Center of Laser Fusion, Chinese Academy of Engineering Physics, Mianyang, Sichuan 621900 (China)

    2016-07-15

    We present here the results of the simulation work, using the three-dimensional particle-in-cell method, on the performance of the lead glass microchannel plate under saturated state. We calculated the electron cascade process with different DC bias voltages under both self-consistent condition and non-self-consistent condition. The comparative results have demonstrated that the strong self-consistent field can suppress the cascade process and make the microchannel plate saturated. The simulation results were also compared to the experimental data and good agreement was obtained. The simulation results also show that the electron multiplication process in the channel is accompanied by the buildup process of positive charges in the channel wall. Though the interactions among the secondary electron cloud in the channel, the positive charges in the channel wall, and the external acceleration field can make the electron-surface collision more frequent, the collision energy will be inevitably reduced, thus the electron gain will also be reduced.

  19. X-ray focusing with Wolter microchannel plate optics

    CERN Document Server

    Price, G J; Beijersbergen, M W; Fraser, G W; Bavdaz, M; Boutot, J P; Fairbend, R; Flyckt, S O; Peacock, A; Tomaselli, E

    2002-01-01

    Square-pore microchannel plate (MCP) X-ray optics of the 'lobster-eye' geometry have frequently been described in the literature. We have now investigated the use of a radial channel packing geometry which, in the context of an MCP pair slumped to the correct radii of curvature, can form a conic approximation to the Wolter Type I grazing incidence X-ray optic. Such an optic can provide a large effective area with very low mass and may be ideally suited for use in applications such as planetary imaging X-ray fluorescence. We present here the results of X-ray illumination of the first such optic, fabricated by Photonis SAS, France.

  20. 'Zero-time' detectors using microchannel plates for charged particle detection

    International Nuclear Information System (INIS)

    Girard, J.

    1977-01-01

    The mass identification of the reaction products detected in heavy ion nuclear reactions is generally obtained by the time-of-flight method. This method requires a device giving first the 'start' signal (zero time at the passage of the particle) and then the stop 'signal'. The interest lying in 'zero-time' detectors using a secondary electron emission has been considerably increased with using microchannel electron multipliers. Nevertheless such a device was shown to induce either fluctuations in the distance of flight or the use of detectors of different type in the 'start' and 'stop' channels respectively. In both cases, it remains an ambiguity as the access to time resolution, in the channel including the electron multiplier, is not direct and the effect of the different parameters on this resolution are masked. To palliate this drawback and study the qualities of microchannel plate multipliers in time measurement field, some devices mechanically and electronically symmetric have been developed. The resolution measurement in time of flight is obtained for electrons generated by the same particle and emitted from either side of a thin film. The distances of flight of the electrons on each side of the film are same, and so are the accelerating potentials. The microchannel electron multipliers and the processing electronic units are the same in each channel [fr

  1. A novel ZVS high voltage power supply for micro-channel plate photomultiplier tubes

    International Nuclear Information System (INIS)

    Pei, Chengquan; Tian, Jinshou; Liu, Zhen; Qin, Hong; Wu, Shengli

    2017-01-01

    A novel resonant high voltage power supply (HVPS) with zero voltage switching (ZVS), to reduce the voltage stress on switching devices and improve conversion efficiency, is proposed. The proposed HVPS includes a drive circuit, a transformer, several voltage multiplying circuits, and a regulator circuit. The HVPS contains several secondary windings that can be precisely regulated. The proposed HVPS performed better than the traditional resistor voltage divider, which requires replacing matching resistors resulting in resistor dispersibility in the Micro-Channel Plate (MCP). The equivalent circuit of the proposed HVPS was established and the operational principle analyzed. The entire switching element can achieve ZVS, which was validated by a simulation and experiments. The properties of this HVPS were tested including minimum power loss (240 mW), maximum power loss (1 W) and conversion efficiency (85%). The results of this research are that the proposed HVPS was suitable for driving the micro-channel plate photomultiplier tube (MCP-PMT). It was therefore adopted to test the MCP-PMT, which will be used in Daya Bay reactor neutrino experiment II in China.

  2. A novel ZVS high voltage power supply for micro-channel plate photomultiplier tubes

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Chengquan [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi’an 710049 (China); Tian, Jinshou [Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Liu, Zhen [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi’an 710049 (China); Qin, Hong [School of Computer Science and Technology, Xi' an University of Science and Technology, Xi' an 710054 (China); Wu, Shengli, E-mail: slwu@mail.xjtu.edu.cn [Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Xi' an Jiaotong University, Xi’an 710049 (China)

    2017-04-11

    A novel resonant high voltage power supply (HVPS) with zero voltage switching (ZVS), to reduce the voltage stress on switching devices and improve conversion efficiency, is proposed. The proposed HVPS includes a drive circuit, a transformer, several voltage multiplying circuits, and a regulator circuit. The HVPS contains several secondary windings that can be precisely regulated. The proposed HVPS performed better than the traditional resistor voltage divider, which requires replacing matching resistors resulting in resistor dispersibility in the Micro-Channel Plate (MCP). The equivalent circuit of the proposed HVPS was established and the operational principle analyzed. The entire switching element can achieve ZVS, which was validated by a simulation and experiments. The properties of this HVPS were tested including minimum power loss (240 mW), maximum power loss (1 W) and conversion efficiency (85%). The results of this research are that the proposed HVPS was suitable for driving the micro-channel plate photomultiplier tube (MCP-PMT). It was therefore adopted to test the MCP-PMT, which will be used in Daya Bay reactor neutrino experiment II in China.

  3. Systematic studies of micro-channel plate PMTs

    International Nuclear Information System (INIS)

    Lehmann, A.; Britting, A.; Cowie, E.; Dodokhof, V.Kh.; Dueren, M.; Dutta, D.; Eyrich, W.; Foehl, K.; Glazier, D.I.; Hayrapetyan, A.; Hoek, M.; Hohler, R.; Kaiser, R.; Keri, T.; Koch, P.; Kroeck, B.; Lehmann, D.; Marton, J.; Merle, O.; Montgomery, R.

    2011-01-01

    DIRC Cherenkov detectors will be the main devices for π/K separation at the PANDA experiment at FAIR. Due to their advantageous properties in terms of time resolution and especially inside magnetic fields micro-channel plate photo multipliers (MCP-PMTs) are very attractive sensor candidates. In this paper we present the investigation of several types of multi-anode MCP-PMTs. The darkcount rate, the behavior inside a magnetic field of up to 2 T, the time resolution, the gain homogeneity and crosstalk of multi-pixel MCP-PMTs were found to be well suitable for the PANDA requirements. Even the rate capability of the latest models from Burle-Photonis and Hamamatsu is satisfactory. Although a big step forward was accomplished with these recently available MCP-PMTs, the lifetime is still not sufficient for the photon densities expected for the PANDA DIRCs.

  4. Detailed measurements and shaping of gate profiles for microchannel-plate-based X-ray framing cameras

    International Nuclear Information System (INIS)

    Landen, O.L.; Hammel, B.A.; Bell, P.M.; Abare, A.; Bradley, D.K.; Univ. of Rochester, NY

    1994-01-01

    Gated, microchannel-plate-based (MCP) framing cameras are increasingly used worldwide for x-ray imaging of subnanosecond laser-plasma phenomena. Large dynamic range (> 1,000) measurements of gain profiles for gated microchannel plates (MCP) are presented. Temporal profiles are reconstructed for any point on the microstrip transmission line from data acquired over many shots with variable delay. No evidence for significant pulse distortion by voltage reflections at the ends of the microstrip is observed. The measured profiles compare well to predictions by a time-dependent discrete dynode model down to the 1% level. The calculations do overestimate the contrast further into the temporal wings. The role of electron transit time dispersion in limiting the minimum achievable gate duration is then investigated by using variable duration flattop gating pulses. A minimum gate duration of 50 ps is achieved with flattop gating, consistent with a fractional transit time spread of ∼ 15%

  5. Microfabrication of Microchannels for Fuel Cell Plates

    Directory of Open Access Journals (Sweden)

    Ho Su Jang

    2009-12-01

    Full Text Available Portable electronic devices such as notebook computers, PDAs, cellular phones, etc., are being widely used, and they increasingly need cheap, efficient, and lightweight power sources. Fuel cells have been proposed as possible power sources to address issues that involve energy production and the environment. In particular, a small type of fuel-cell system is known to be suitable for portable electronic devices. The development of micro fuel cell systems can be achieved by the application of microchannel technology. In this study, the conventional method of chemical etching and the mechanical machining method of micro end milling were used for the microfabrication of microchannel for fuel cell separators. The two methods were compared in terms of their performance in the fabrication with regards to dimensional errors, flatness, straightness, and surface roughness. Following microchannel fabrication, the powder blasting technique is introduced to improve the coating performance of the catalyst on the surface of the microchannel. Experimental results show that end milling can remarkably increase the fabrication performance and that surface treatment by powder blasting can improve the performance of catalyst coating.

  6. Use of Large Surface MicroChannel Plates for the Tagging of Intermediate Energy Exotic Beams

    Energy Technology Data Exchange (ETDEWEB)

    Lombardo, I., E-mail: ilombardo@lns.infn.it [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Amorini, F. [INFN Laboratori Nazionali del Sud, Catania (Italy); Cardella, G. [INFN, Sezione di Catania, Catania (Italy); Cavallaro, S. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); De Filippo, E. [INFN, Sezione di Catania, Catania (Italy); Geraci, E.; Grassi, L. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); La Guidara, E. [INFN, Sezione di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lanzalone, G. [INFN Laboratori Nazionali del Sud, Catania (Italy); Libera Universita Kore, Enna (Italy); Pagano, A.; Papa, M.; Pirrone, S. [INFN, Sezione di Catania, Catania (Italy); Politi, G. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN, Sezione di Catania, Catania (Italy); Porto, F.; Rizzo, F.; Russotto, P. [Dipartimento di Fisica, Universita di Catania, Catania (Italy); INFN Laboratori Nazionali del Sud, Catania (Italy); Verde, G. [INFN, Sezione di Catania, Catania (Italy); Vigilante, M. [INFN, Sezione di Napoli and Dipartimento di Fisica, Universita Federico II di Napoli (Italy)

    2011-06-15

    We show the properties of the tagging system for exotic beams coupled to the CHIMERA detector. In particular, the characteristics of a newly developed large surface MicroChannel Plate will be discussed. Timing and efficiency of this instrument have been investigated. Preliminary results of tests performed with radioactive beams and alpha sources are presented.

  7. Recent developments with microchannel-plate PMTs

    Science.gov (United States)

    Lehmann, A.; Böhm, M.; Britting, A.; Eyrich, W.; Pfaffinger, M.; Uhlig, F.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M.; Düren, M.; Etzelmüller, E.; Föhl, K.; Hayrapetyan, A.; Kröck, B.; Merle, O.; Rieke, J.; Schmidt, M.; Wasem, T.; Cowie, E.; Keri, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2017-12-01

    Microchannel-plate (MCP) PMTs are the favored photon sensors for the DIRC detectors of the PANDA experiment at FAIR. Until recently the main drawback of MCP-PMTs were serious aging effects which led to a limited lifetime due to a rapidly decreasing quantum efficiency (QE) of the photo cathode (PC) as the integrated anode charge (IAC) increased. In the latest models of PHOTONIS and Hamamatsu an innovative atomic layer deposition (ALD) technique is applied to overcome these limitations. During the last five years comprehensive aging tests with ALD coated MCP-PMTs were performed and the results were compared to tubes treated with other techniques. The QE in dependence of the IAC was measured as a function of the wavelength and the position across the PC. For the best performing tubes the lifetime improvement in comparison to the older MCP-PMTs is a factor of > 50 based on an IAC of meanwhile > 10 C /cm2 . In addition, the performance results of a new 2-in. ALD coated MCP-PMT prototype from Hamamatsu with a very high position resolution (128×6 anode pixels) is presented and the first conclusions from investigations concerning the PC aging mechanism will be discussed.

  8. Observation of Ultra-Slow Antiprotons using Micro-channel Plate

    Science.gov (United States)

    Imao, H.; Torii, H. A.; Nagata, Y.; Toyoda, H.; Shimoyama, T.; Enomoto, Y.; Higaki, H.; Kanai, Y.; Mohri, A.; Yamazaki, Y.

    2008-08-01

    Our group ASACUSA-MUSASHI has succeeded in accumulating several million antiprotons and extracting them as monochromatic ultra-slow antiproton beams (10 eV-1 keV) at CERN AD. We have observed ultra-slow antiprotons using micro-channel plates (MCP). The integrated pulse area of the output signals generated when the MCP was irradiated by ultra-slow antiprotons was 6 times higher than that by electrons. As a long-term effect, we also observed an increase in the background rate presumably due to the radioactivation of the MCP surface. Irradiating the antiproton beams on the MCP induces antiproton-nuclear annihilations only on the first layer of the surface. Low-energy and short-range secondary particles like charged nuclear fragments caused by the "surface nuclear reactions" would be the origin of our observed phenomena.

  9. Implementation of 40-ps high-speed gated-microchannel-plate based x-ray framing cameras on reentrant SIM's for Nova

    International Nuclear Information System (INIS)

    Bell, P.M.; Kilkenny, J.D.; Landen, O.; Bradley, D.K.

    1994-01-01

    Gated framing cameras used in diagnosing laser produced plasmas have been used on the Nova laser system since 1987. There have been many variations of these systems implemented. All of these cameras have been ultimately limited in response time for two reasons. One being the electrical gating amplitude verses the gate width, this has always limited the detectable gain in the system. The second being the length to diameter (l/d) ratio of standard off the shelf microchannel plates (MCP). This sets the minimum electrical gate pulse that will give detectable gain from a given microchannel plate. The authors have implemented two different types of 40 ps framing camera configurations on the Nova laser system. They will describe the configurations of both systems as well as discuss the advantages of each

  10. Atomic layer deposition of alternative glass microchannel plates

    Energy Technology Data Exchange (ETDEWEB)

    O' Mahony, Aileen, E-mail: aom@incomusa.com; Craven, Christopher A.; Minot, Michael J.; Popecki, Mark A.; Renaud, Joseph M.; Bennis, Daniel C.; Bond, Justin L.; Stochaj, Michael E.; Foley, Michael R.; Adams, Bernhard W. [Incom, Inc., 294 Southbridge Road, Charlton, Massachusetts 01507 (United States); Mane, Anil U.; Elam, Jeffrey W. [Argonne National Laboratory, 9700 S. Cass Ave., Argonne, Illinois 60439 (United States); Ertley, Camden; Siegmund, Oswald H. W. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, California 94720 (United States)

    2016-01-15

    The technique of atomic layer deposition (ALD) has enabled the development of alternative glass microchannel plates (MCPs) with independently tunable resistive and emissive layers, resulting in excellent thickness uniformity across the large area (20 × 20 cm), high aspect ratio (60:1 L/d) glass substrates. Furthermore, the use of ALD to deposit functional layers allows the optimal substrate material to be selected, such as borosilicate glass, which has many benefits compared to the lead-oxide glass used in conventional MCPs, including increased stability and lifetime, low background noise, mechanical robustness, and larger area (at present up to 400 cm{sup 2}). Resistively stable, high gain MCPs are demonstrated due to the deposition of uniform ALD resistive and emissive layers on alternative glass microcapillary substrates. The MCP performance characteristics reported include increased stability and lifetime, low background noise (0.04 events cm{sup −2} s{sup −1}), and low gain variation (±5%)

  11. Development of time-of-flight RBS system using multi microchannel plates

    International Nuclear Information System (INIS)

    Nguyen, N.V.; Abo, S.; Lohner, T.; Sawaragi, H.; Wakaya, F.; Takai, M.

    2007-01-01

    A new time-of-flight Rutherford backscattering spectroscopy (TOF-RBS) system with two circular microchannel plates (MCPs) installed at a distance of 140 mm from a sample holder and a scattering angle of 125 o and a 100 kV focused ion beam column having a liquid metal ion source (LMIS) of AuSiBe alloy has been assembled to obtain high counting rate and enhanced mass resolution. The possible influence of the two MCPs by logical summation of the output signals on the time resolution was investigated by measuring dedicated thin deposited metallic samples. And, the time resolution was found in the range of 1.5-2 ns

  12. A Neutron Sensitive Microchannel Plate Detector with Cross Delay Line Readout

    International Nuclear Information System (INIS)

    Berry, Kevin D.; Bilheux, Hassina Z.; Crow, Lowell; Diawara, Yacouba; Feller, W. Bruce; Iverson, Erik B.; Martin, Adrian; Robertson, J. Lee

    2012-01-01

    Microchannel plates containing neutron absorbing elements such as boron and gadolinium in the bulk glass are used as the sensing element in high spatial resolution, high rate neutron imaging systems. In this paper we describe one such device, using both 10 B and natural Gd, which employs cross delay line signal readout, with time-of-flight capability. This detector has a measured spatial resolution under 40 m FWHM, thermal neutron efficiency of 19%, and has recorded rates in excess of 500 kHz. A physical and functional description is presented, followed by a discussion of measurements of detector performance and a brief survey of some practical applications.

  13. Functionalized Nano-Film Microchannel Plate: A Single High Aspect Ratio Device for High Resolution, Low Noise Astronomical Imaging, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is to apply proven nano-film technology to enable Microchannel plate (MCP) devices to be manufactured on a range of insulating substrates and...

  14. Design and fabrication of prototype 6×6 cm2 microchannel plate photodetector with bialkali photocathode for fast timing applications

    International Nuclear Information System (INIS)

    Xie, Junqi; Byrum, Karen; Demarteau, Marcel; Gregar, Joseph; May, Edward; Virgo, Mathew; Wagner, Robert; Walters, Dean; Wang, Jingbo; Xia, Lei; Zhao, Huyue

    2015-01-01

    Planar microchannel plate-based photodetectors with a bialkali photocathode are able to achieve photon detection with very good time and position resolution. A 6×6 cm 2 photodetector production facility was designed and built at Argonne National Laboratory. Small form-factor MCP-based photodetectors completely constructed out of glass were designed and prototypes were successfully fabricated. Knudsen effusion cells were incorporated in the photocathode growth chamber to achieve uniform and high quantum efficiency photocathodes. The thin film uniformity was simulated and measured for an antimony film deposition, showing uniformity of better than 10%. Several prototype devices with bialkali photocathodes have been fabricated with the described system and their characteristics were evaluated in the large signal (multi-PE) limit. A typical prototype device exhibits time-of-flight resolution of ~27 psec and differential time resolution of ~9 psec, corresponding to spatial resolution of ~0.65 mm

  15. The size and spatial distribution of microchannel plate output electron clouds

    International Nuclear Information System (INIS)

    Lapington, J.S.; Edgar, M.L.

    1989-01-01

    An experimental technique for measuring the spatial distribution of the output charge cloud from a microchannel plate (MCP), using a planar, charge-division-type anode is discussed. The anode simultaneously measures, for each charge cloud, both the position of the charge centroid and the fractional charge falling to one side of the split in the pattern. The measurements from several thousand events have been combined to calculate the average spatial distribution of the electron cloud and the dominant factors influencing the charge cloud distribution have been found to be the MCP gain and the MCP-anode accelerating field and geometry. Experimental research on the two dominant factors with respect to ranges of distribution is presented. 10 refs

  16. Multiple-photon disambiguation on stripline-anode Micro-Channel Plates

    Energy Technology Data Exchange (ETDEWEB)

    Jocher, Glenn R., E-mail: glenn.jocher@ultralytics.com [Ultralytics LLC, Arlington, VA 22203 (United States); Wetstein, Matthew J., E-mail: mwetstein@uchicago.edu [Iowa State University, Department of Physics and Astronomy, 12 Physics Hall, Ames, IA 50011 (United States); Adams, Bernhard, E-mail: badams@incomusa.com [Incom, Inc., 294 Southbridge Road, Charlton, MA 01507 (United States); Nishimura, Kurtis, E-mail: kurtis.nishimura@ultralytics.com [Ultralytics LLC, Arlington, VA 22203 (United States); Usman, Shawn M., E-mail: shawn.usman@nga.mil [Research Directorate, National Geospatial-Intelligence Agency, 7500 GEOINT Dr., Springfield, VA 22150 (United States); Department of Geography and Geoinformation Science, George Mason University, Fairfax, VA 22030 (United States)

    2016-06-21

    Large-Area Picosecond Photo-Detectors (LAPPDs) show great potential for expanding the performance envelope of Micro-Channel Plates (MCPs) to areas of up to 20×20 cm and larger. Such scaling introduces new challenges, including how to meet the electronics readout burden of ever larger area MCPs. One solution is to replace the traditional grid anode used for readout with a microwave stripline anode, thus allowing the channel count to scale with MCP width rather than area. However, stripline anodes introduce new issues not commonly dealt with in grid-anodes, especially as their length increases. One of these issues is the near simultaneous arrival of multiple photons on the detector, creating possible confusion about how to reconstruct their arrival times and positions. We propose a maximum a posteriori solution to the problem and verify its performance in simulated scintillator and water-Cherenkov detectors.

  17. Microchannel plate special nuclear materials sensor

    International Nuclear Information System (INIS)

    Feller, W.B.; White, P.L.; White, P.B.; Siegmund, O.H.W.; Martin, A.P.; Vallerga, J.V.

    2011-01-01

    Nova Scientific Inc., is developing for the Domestic Nuclear Detection Office (DNDO SBIR no. HSHQDC-08-C-00190), a solid-state, high-efficiency neutron detection alternative to 3 He gas tubes, using neutron-sensitive microchannel plates (MCPs) containing 10 B and/or Gd. This work directly supports DNDO development of technologies designed to detect and interdict nuclear weapons or illicit nuclear materials. Neutron-sensitized MCPs have been shown theoretically and more recently experimentally, to be capable of thermal neutron detection efficiencies equivalent to 3 He gas tubes. Although typical solid-state neutron detectors typically have an intrinsic gamma sensitivity orders of magnitude higher than that of 3 He gas detectors, we dramatically reduce gamma sensitivity by combining a novel electronic coincidence rejection scheme, employing a separate but enveloping gamma scintillator. This has already resulted in a measured gamma rejection ratio equal to a small 3 He tube, without in principle sacrificing neutron detection efficiency. Ongoing improvements to the MCP performance as well as the coincidence counting geometry will be described. Repeated testing and validation with a 252 Cf source has been underway throughout the Phase II SBIR program, with ongoing comparisons to a small commercial 3 He gas tube. Finally, further component improvements and efforts toward integration maturity are underway, with the goal of establishing functional prototypes for SNM field testing.

  18. Time resolution of Burle 85001 micro-channel plate photo-multipliers in comparison with Hamamatsu R2083

    Energy Technology Data Exchange (ETDEWEB)

    V. Baturin; V. Burkert; W. Kim; S. Majewsky; D. Nekrasov; K. Park; V. Popov; E. S. Smith; D. Son; S. S. Stepanyan; C. Zorn

    2005-06-01

    The CLAS detector will require improvements in its particle identification system to take advantage of the higher energies provided by the Jefferson Laboratory accelerator upgrade to 12 GeV. To this end, we have studied the timing characteristics of the micro-channel plate photo-multiplier 85001 from Burle, which can be operated in a high magnetic field environment. For reference and comparison, measurements were also made using the standard PMT R2083 from Hamamatsu using two timing methods. The cosmic ray method, which utilizes three identical scintillating counters 2cm x 3cm x 50cm with PMs at the ends, yields 59.1(0.7)ps. The location method of particles from radiative source with known coordinates has been used to compare timing resolutions of R2083 and Burle-85001. This ''coordinate method'' requires only one counter instrumented with two PMs and it yields 59.5(0.7)ps. For the micro-channel plate photomultiplier from Burle with an external amplification of 10 to the signals, the co ordinate method yields 130(4)ps. This method also makes it possible to estimate the number of primary photo-electrons.

  19. Performance test of miniature heat exchangers with microchannels

    International Nuclear Information System (INIS)

    Hong, Yong Ju; Koh, Deuk Yong

    2005-01-01

    Etched microchannel heat exchanger, a subfield within MEMS, has high heat flux capability. This capability makes microchannels well-suited for a wide variety of application of cooling and chemical reaction. In this study, counter flow type miniature heat exchangers, which have flat metal plates with chemically etched microchannels, were manufactured by brazing method. Four type of the heat exchangers, which have straight microchannels, wavy shape microchannels, pin-fin channels and serpentine shape microchannels, were investigated to compare their thermal and hydraulic performance. Gas to gas heat exchange experiments were performed to measure the pressure drop and effectiveness of the heat exchangers at given gas flow rates and temperature difference

  20. Microchannel plate detector technology potential for LUVOIR and HabEx

    Science.gov (United States)

    Siegmund, O. H. W.; Ertley, C.; Vallerga, J. V.; Schindhelm, E. R.; Harwit, A.; Fleming, B. T.; France, K. C.; Green, J. C.; McCandliss, S. R.; Harris, W. M.

    2017-08-01

    Microchannel plate (MCP) detectors have been the detector of choice for ultraviolet (UV) instruments onboard many NASA missions. These detectors have many advantages, including high spatial resolution (hardness, large formats (up to 20 cm), and ability for curved focal plane matching. Novel borosilicate glass MCPs with atomic layer deposition combine extremely low backgrounds, high strength, and tunable secondary electron yield. GaN and combinations of bialkali/alkali halide photocathodes show promise for broadband, higher quantum efficiency. Cross-strip anodes combined with compact ASIC readout electronics enable high spatial resolution over large formats with high dynamic range. The technology readiness levels of these technologies are each being advanced through research grants for laboratory testing and rocket flights. Combining these capabilities would be ideal for UV instruments onboard the Large UV/Optical/IR Surveyor (LUVOIR) and the Habitable Exoplanet Imaging Mission (HABEX) concepts currently under study for NASA's Astrophysics Decadal Survey.

  1. Significantly increased lifetime of recent microchannel-plate photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Britting, Alexander; Eyrich, Wolfgang; Lehmann, Albert; Uhlig, Fred [Physikalisches Institut, Universitaet Erlangen-Nuernberg (Germany)

    2013-07-01

    Micro-channel plate photo multipliers (MCP-PMT) are the favored sensors for the DIRC detectors (Detection of Internally Reflected Cherenkov Light) of the PANDA experiment. The main reasons for this are their usability in high magnetic fields of up to 2 T, a time resolution of better than σ = 50 ps and a rate capability high enough to withstand a detected photon rate of about 200 kHz cm{sup -2} at the MCP-PMTs surface, which is anticipated at the average luminosity of 2 . 10{sup 32} cm{sup -2}s{sup -1} in PANDA. Moreover, for the reconstruction of the Cherenkov angle using the planned optics for the barrel DIRC a spatial resolution of about 5 mm at the focal plane is needed. Until recently the major drawback of MCP-PMTs was their limited lifetime which was by far not sufficient to stand the integrated anode charge, which is ∼ 5 C/cm{sup 2} for the Barrel-DIRC and even more for the Disc-DIRC. However, the latest MCP prototype devices show a hugh step forward in this respect. The results of these lifetime measurements are presented. The achieved values are meanwhile close to the PANDA requirements for the Barrel-DIRC.

  2. An efficient and cost-effective microchannel plate detector for slow neutron radiography

    Science.gov (United States)

    Wiggins, B. B.; Vadas, J.; Bancroft, D.; deSouza, Z. O.; Huston, J.; Hudan, S.; Baxter, D. V.; deSouza, R. T.

    2018-05-01

    A novel approach for efficiently imaging objects with slow neutrons in two dimensions is realized. Neutron sensitivity is achieved by use of a boron doped microchannel plate (MCP). The resulting electron avalanche is further amplified with a Z-stack MCP before being sensed by two orthogonally oriented wire planes. Coupling of the wire planes to delay lines efficiently encodes the position information as a time difference. To determine the position resolution, slow neutrons were used to illuminate a Cd-mask placed directly in front of the detector. Peaks in the resulting spectrum exhibited an average peak width of 329 μm FWHM, corresponding to an average intrinsic resolution of 216 μm. The center region of the detector exhibits a significantly better spatial resolution with an intrinsic resolution of <100 μm observed.

  3. Testing micro-channel plate detectors for the particle identification upgrade of LHCb

    CERN Document Server

    Castillo Garcia, L

    2012-01-01

    The TORCH, Time of internally Reflected Cherenkov Light, is proposed for the high luminosity upgrade of the LHCb experiment. The detector combines Time-of-Flight and Cherenkov techniques to achieve positive pi/K/p separation on a >= 3 sigma level in the momentum range below 10 GeV/c. The required time resolution is <= 50 ps for single photon signal. In a preliminary R\\&D phase, we have shown that already commercially available micro-channel plate tubes with 8 x 8 channels fulfil the requirements. Timing properties of the tubes have been investigated with a pulsed laser diode in single photon regime. Key results from these laboratory tests are reported. An excellent timing resolution of <40 ps is achieved with an efficiency of similar to 90\\%. (C) 2011 Elsevier B.V. All rights reserved.

  4. Development of microchannel plates in advanced wind-tunnel instrumentation

    Science.gov (United States)

    Feller, W. Bruce

    1990-01-01

    Microchannel plate (MCP) electron multiplier dynamic range has been increased 3 to 4 orders of magnitude at ambient temperatures, through enhanced input count rate capability and reduced background or 'dark' noise. The previous upper limit of roughly 10(exp 7) - 10(exp 8) cm(exp -2)s(exp -1) at ambient has been extended to levels approach 10(exp 10) cm(exp -2)s(exp -1) under continuous dc operation. The lower limit, previously set by an irreducible background component (approximately 0.6 cm(exp -2)s(exp -1)), has been lowered to the cosmic ray limit of .01 cm(exp -2)s(exp -1). The high end improvement was achieved by conductively cooling a very low resistance MCP by bonding it to a heat sink, while maintaining pulse-counting operation with multianode readouts. The low-end improvement was achieved by removing all radioisotopes from the MCP matrix glass. The detectors will benefit optical and mass spectrometry, flow visualization, plasma diagnostics, magnetometry, and other high signal flux applications. Very low MCP background noise will benefit X-ray and UV astronomy, medical imaging, trace isotope mass spectrometry, and other applications where the signal flux is often extremely low.

  5. Measurements of recent microchannel-plate photomultipliers with significantly increased lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Uhlig, Fred; Eyrich, Wolfgang; Lehmann, Albert; Britting, Alexander [Universitaet Erlangen, Physikal. Institut IV (Germany); Collaboration: PANDA-Collaboration

    2015-07-01

    Microchannel-plate photomultipliers (MCP-PMTs) are the favored sensors for the DIRC detectors (Detection of Internally Reflected Cherenkov Light) of the PANDA experiment. They are usable in high magnetic fields of up to 2T and reach a time resolution of better than 50 ps (σ). The anticipated average luminosity of 2.10{sup 32} cm{sup -2} s{sup -1} in the detector requires a rate capability high enough to withstand a detected photon rate of about 200 kHz cm{sup -2} at the MCP-PMT surfaces. The major drawback until recently was the limited lifetime of MCP-PMTs, which appears to be solved for the latest generation of MCP-PMT prototype devices. The aging parameter is the quantum efficiency as a function of the integrated anode charge, which will be in the region of 5 C/cm{sup 2} for the Barrel- and the Disc-DIRC. We simultaneously measured the aging of several MCP-PMTs, which were treated with different methods to enhance the lifetime. Results of these measurements are presented.

  6. Temporal resolution technology of a soft X-ray picosecond framing camera based on Chevron micro-channel plates gated in cascade

    Energy Technology Data Exchange (ETDEWEB)

    Yang Wenzheng [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China)], E-mail: ywz@opt.ac.cn; Bai Yonglin; Liu Baiyu [State Key Laboratory of Transient Optics and Photonics, Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China); Bai Xiaohong; Zhao Junping; Qin Junjun [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi' an 710119 (China)

    2009-09-11

    We describe a soft X-ray picosecond framing camera (XFC) based on Chevron micro-channel plates (MCPs) gated in cascade for ultra-fast process diagnostics. The micro-strip lines are deposited on both the input and the output surfaces of the Chevron MCPs and can be gated by a negative (positive) electric pulse on the first (second) MCP. The gating is controlled by the time delay T{sub d} between two gating pulses. By increasing T{sub d}, the temporal resolution and the gain of the camera are greatly improved compared with a single-gated MCP-XFC. The optimal T{sub d}, which results in the best temporal resolution, is within the electron transit time and transit time spread of the MCP. Using 250 ps, {+-}2.5 kV gating pulses, the temporal resolution of the double-gated Chevron MCPs camera is improved from 60 ps for the single-gated MCP-XFC to 37 ps for T{sub d}=350 ps. The principle is presented in detail and accompanied with a theoretic simulation and experimental results.

  7. Laser beam micro-milling of micro-channels in aerospace alloys

    CERN Document Server

    Ahmed, Naveed; Al-Ahmari, Abdulrahman

    2017-01-01

    This volume is greatly helpful to micro-machining and laser engineers as it offers obliging guidelines about the micro-channel fabrications through Nd:YAG laser beam micro-milling. The book also demonstrates how the laser beam micro-milling behaves when operating under wet conditions (under water), and explores what are the pros and cons of this hybrid technique. From the predictive mathematical models, the readers can easily estimate the resulting micro-channel size against the desired laser parametric combinations. The book considers micro-channels in three highly important research materials commonly used in aerospace industry: titanium alloy Ti-6Al-4V, nickel alloy Inconel 718 and aluminum alloy AA 2024. Therefore, the book is highly practicable in the fields of micro-channel heat exchangers, micro-channel aerospace turbine blades, micro-channel heat pipes, micro-coolers and micro-channel pulsating heat plates. These are frequently used in various industries such as aerospace, automotive, biomedical and m...

  8. Understanding the dynamic performance of microchannel plates in pulsed mode

    International Nuclear Information System (INIS)

    Ray Thomas; Ming Wu; Nathan Joseph; Craig Kruschwitz; Gregroy A. Rochau

    2007-01-01

    The dynamic performance of a microchannel plate (MCP) is highly dependent on the high-voltage waveforms that are applied to it. Impedance mismatches in MCP detectors can significantly vary the waveforms on the MCP compared to the input pulses. High-voltage pulse waveforms launched onto surface coatings on the MCPs have historically been difficult and expensive to measure. Over the past few years, we have developed and tested techniques utilizing probes to measure the voltage propagation on the surface of MCPs. Square and Gaussian pulses with widths ranging from 200 ps to 2 ns have been applied. We have investigated the effects of coating thickness, microstrip width, and openended versus terminated strips. These data provide a wealth of knowledge that is enabling a better understanding of images recorded with these devices. This presentation discusses a method for measuring voltage profiles on the surface of the MCP and presents Monte Carlo simulations of the optical gate profiles based on the measured waveforms. Excellent agreement in the optical gate profiles have been achieved between the simulations and the experimental measurements using a short-pulse ultraviolet laser

  9. Compact Ceramic Microchannel Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  10. Mean secondary electron yield of avalanche electrons in the channels of a microchannel plate detector

    International Nuclear Information System (INIS)

    Funsten, H.O.; Suszcynsky, D.M.; Harper, R.W.

    1996-01-01

    By modeling the statistical evolution of an avalanche created by 20 keV protons impacting the input surface of a z-stack microchannel plate (MCP) detector, the mean secondary electron yield γ C of avalanche electrons propagating through a MCP channel is measured to equal 1.37 for 760 V per MCP in the z stack. This value agrees with other studies that used MCP gain measurements to infer γ C . The technique described here to measure γ C is independent of gain saturation effects and simplifying assumptions used in the segmented dynode model, both of which can introduce errors when inferring γ C through gain measurements. copyright 1996 American Institute of Physics

  11. On possibility to make a new type of calorimeter: radiation resistant and fast

    International Nuclear Information System (INIS)

    Derevshchikov, A.A.; Khodyrev, V.Yu.; Kryshkin, V.I.; Rakhmatov, V.E.; Ronzhin, A.I.

    1990-01-01

    It is proposed to use electron multipliers, which directly detect low energy shower particles as an active element in sandwich calorimeters. The approach pffers fast and radiation resistant calorimetry. Test of the method is presented with the use of a microchannel plate. 4 refs.; 4 figs

  12. Dynamic Characterizations of an 8-frame, Half-Strip, High-speed X-ray Microchannel Plate Imager

    International Nuclear Information System (INIS)

    Ken Moy; Ming Wu; Craig Kruschwitz; Aric Tibbits; Matt Griffin; Greg Rochau

    2008-01-01

    High-speed microchannel plate (MCP)-based imagers are critical detectors for x-ray diagnostics employed on Z-experiments at Sandia National Laboratories (SNL) to measure time-resolved x-ray spectra and to image dynamic hohlraums. A multiframe design using eight half strips in one imager permits recordings of radiation events in discrete temporal snapshots to yield a time-evolved movie. We present data using various facilities to characterize the performance of this design. These characterization studies include DC and pulsed-voltage biased measurements in both saturated and linear operational regimes using an intense, short-pulsed UV laser. Electrical probe measurements taken to characterize the shape of the HV pulse propagating across the strips help to corroborate the spatial gain dependence

  13. A new method to measure and increase the detection efficiency of a microchannel plate for 100 keV electrons

    International Nuclear Information System (INIS)

    Tornow, R.P.

    1990-01-01

    A new method is described which permits measurement of efficiency of a microchannel plate (MCP) simply by tracing the output current pulse in the saturated mode. The dependence of the detection efficiency on the gain of the input stages of a detector is calculated and the result is applied to a MCP. Furthermore, an enhancement of the detection efficiency of a MCP is presented for 100 keV electrons up to more than 90% by means of the field-enhanced secondary electron emission. (author)

  14. Investigation of a Multi-Anode Microchannel Plate PMT for Time-of-Flight PET

    Science.gov (United States)

    Choong, Woon-Seng

    2010-10-01

    We report on an investigation of a mulit-anode microchannel plate PMT for time-of-flight PET detector modules. The primary advantages of an MCP lie in its excellent timing properties (fast rise time and low transit time spread), compact size, and reasonably large active area, thus making it a good candidate for TOF applications. In addition, the anode can be segmented into an array of collection electrodes with fine pitch to attain good position sensitivity. In this paper, we investigate using the Photonis Planacon MCP-PMT with a pore size of 10 μm to construct a PET detector module, specifically for time-of-flight applications. We measure the single electron response by exciting the Planacon with pulsed laser diode. We also measure the performance of the Planacon as a PET detector by coupling a 4 mm×4 mm×10 mm LSO crystal to individual pixel to study its gain uniformity, energy resolution, and timing resolution. The rise time of the Planacon is 440 ps with pulse duration of about 1 ns. A transit time spread of 120 ps FWHM is achieved. The gain is fairly uniform across the central region of the Planacon, but drops off by as much as a factor of 2.5 around the edges. The energy resolution is fairly uniform across the Planacon with an average value of 18.6 ± 0.7% FWHM. While the average timing resolution of 252 ± 7 ps FWHM is achieved in the central region of the Planacon, it degrades to 280 ± 9 ps FWHM for edge pixels and 316 ± 15 ps FWHM for corner pixels. We compare the results with measurements performed with a fast timing conventional PMT (Hamamatsu R-9800). We find that the R9800, which has significantly higher PDE, has a better timing resolution than the Planacon. Furthermore, we perform detector simulations to calculate the improvement that can be achieved with a higher PDE Planacon. The calculation shows that the Planacon can achieve significantly better timing resolution if it can attain the same PDE as the R-9800, while only a 30% improvement is

  15. Time-of-flight resolution of scintillating counters with Burle 85001 microchannel plate photomultipliers in comparison with Hamamatsu R2083

    Energy Technology Data Exchange (ETDEWEB)

    Baturin, V. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Burkert, V. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Kim, W. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)]. E-mail: wooyoung@jlab.org; Majewsky, S. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Park, K. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Popov, V. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Smith, E.S. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Son, D. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Stepanyan, S.S. [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Zorn, C. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2006-06-15

    Improvements in the time resolution of the CEBAF Large Acceptance Spectrometer (CLAS) below {approx}50ps will be required for experiments using the planned upgraded accelerator facility at Jefferson Lab. The improved time resolution will allow particle identification using time-of-flight techniques to be used effectively up to the proposed operating energy of 12GeV. The challenge of achieving this time resolution over a relatively large area is compounded because the photomultipliers (PM) in the CLAS 'time-zero' scintillating counters must operate in very high magnetic fields. Therefore, we have studied the resolution of 'time-zero' prototypes with microchannel plate PMs 85001-501 from Burle. For reference and comparison, measurements were also made using the standard PMs R2083 from Hamamatsu using two timing methods. The cosmic ray method, which utilizes three identical scintillating counters (Bicron BC-408, 2x3x50cm{sup 3}) with PMs at the ends, yields {sigma}{sub R2083}=59.1+/-0.7ps. The location method of particles from a radiative source with known coordinates has been used to compare timing resolutions of R2083 and 85001-501. This method yields {sigma}{sub R2083}=59.5+/-0.7ps and it also provides an estimate of the number of primary photoelectrons. For the microchannel plate PM from Burle the method yields {sigma}{sub 85001}=130+/-4ps due to lower number of primary photoelectrons.

  16. Feasibility investigations on a novel micro-manufacturing process for fabrication of fuel cell bipolar plates: Internal pressure-assisted embossing of micro-channels with in-die mechanical bonding

    Energy Technology Data Exchange (ETDEWEB)

    Koc, Muammer [NSF I/UCR Center for Precision Forming (CPF), Department of Mechanical Engineering, Virginia Commonwealth University (VCU), Richmond, VA (United States); Mahabunphachai, Sasawat [NSF I/UCR Center for Precision Forming (CPF), Department of Mechanical Engineering, Virginia Commonwealth University (VCU), Richmond, VA (United States); Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI (United States)

    2007-10-25

    In this paper, we present the results of our studies on conceptual design and feasibility experiments towards development of a novel hybrid manufacturing process to fabricate fuel cell bipolar plates that consists of multi-array micro-channels on a large surface area. The premises of this hybrid micro-manufacturing process stem from the use of an internal pressure-assisted embossing process (cold or warm) combined with mechanical bonding of double bipolar plates in a single-die and single-step operation. Such combined use of hydraulic and mechanical forming forces and in-process bonding will (a) enable integrated forming of micro-channels on both surfaces (as anode and cathode flow fields) and at the middle (as cooling channels), (b) reduce the process steps, (c) reduce variation in dimensional tolerances and surface finish, (d) increase the product quality, (e) increase the performance of fuel cell by optimizing flow-field designs and ensuring consistent contact resistance, and (f) reduce the overall stack cost. This paper explains two experimental investigations that were performed to characterize and evaluate the feasibility of the conceptualized manufacturing process. The first investigation involved hydroforming of micro-channels using thin sheet metals of SS304 with a thickness of 51 {mu}m. The width of the channels ranged from 0.46 to 1.33 mm and the height range was between 0.15 and 0.98 mm. Our feasibility experiments resulted in that different aspect ratios of micro-channels could be fabricated using internal pressure in a controllable manner although there is a limit to very sharp channel shapes (i.e., high aspect ratios with narrow channels). The second investigation was on the feasibility of mechanical bonding of thin sheet metal blanks. The effects of different process and material variables on the bond quality were studied. Successful bonding of various metal blanks (Ni201, Al3003, and SS304) was obtained. The experimental results from both

  17. Static response of deformable microchannels: a comparative modelling study

    Science.gov (United States)

    Shidhore, Tanmay C.; Christov, Ivan C.

    2018-02-01

    We present a comparative modelling study of fluid-structure interactions in microchannels. Through a mathematical analysis based on plate theory and the lubrication approximation for low-Reynolds-number flow, we derive models for the flow rate-pressure drop relation for long shallow microchannels with both thin and thick deformable top walls. These relations are tested against full three-dimensional two-way-coupled fluid-structure interaction simulations. Three types of microchannels, representing different elasticity regimes and having been experimentally characterized previously, are chosen as benchmarks for our theory and simulations. Good agreement is found in most cases for the predicted, simulated and measured flow rate-pressure drop relationships. The numerical simulations performed allow us to also carefully examine the deformation profile of the top wall of the microchannel in any cross section, showing good agreement with the theory. Specifically, the prediction that span-wise displacement in a long shallow microchannel decouples from the flow-wise deformation is confirmed, and the predicted scaling of the maximum displacement with the hydrodynamic pressure and the various material and geometric parameters is validated.

  18. Scanning Microscopes Using X Rays and Microchannels

    Science.gov (United States)

    Wang, Yu

    2003-01-01

    Scanning microscopes that would be based on microchannel filters and advanced electronic image sensors and that utilize x-ray illumination have been proposed. Because the finest resolution attainable in a microscope is determined by the wavelength of the illumination, the xray illumination in the proposed microscopes would make it possible, in principle, to achieve resolutions of the order of nanometers about a thousand times as fine as the resolution of a visible-light microscope. Heretofore, it has been necessary to use scanning electron microscopes to obtain such fine resolution. In comparison with scanning electron microscopes, the proposed microscopes would likely be smaller, less massive, and less expensive. Moreover, unlike in scanning electron microscopes, it would not be necessary to place specimens under vacuum. The proposed microscopes are closely related to the ones described in several prior NASA Tech Briefs articles; namely, Miniature Microscope Without Lenses (NPO-20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43; and Reflective Variants of Miniature Microscope Without Lenses (NPO-20610), NASA Tech Briefs, Vol. 26, No. 9 (September 2002) page 6a. In all of these microscopes, the basic principle of design and operation is the same: The focusing optics of a conventional visible-light microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. A microchannel plate containing parallel, microscopic-cross-section holes much longer than they are wide is placed between a specimen and an image sensor, which is typically the CCD. The microchannel plate must be made of a material that absorbs the illuminating radiation reflected or scattered from the specimen. The microchannels must be positioned and dimensioned so that each one is registered with a pixel on the image sensor. Because most of the radiation incident on the microchannel walls becomes absorbed, the radiation that reaches the

  19. Charge coupled devices vs. microchannel plates in the extreme and far ultraviolet - A comparison based on the latest laboratory measurements

    Science.gov (United States)

    Vallerga, J.; Lampton, M.

    1988-01-01

    While microchannel plates (MCPs) have been established as imaging photon counters in the EUV and FUV for some years, CCDs are associated with low light level sensing at visible and near-IR wavelengths. Attention is presently given to recent proposals for CCDs' use as EUV and FUV detectors with quantum efficiencies sometimes exceeding those of MCPs; quantum resolution, format size, dynamic range, and long-term stability are also used as bases of comparison, for the cases of both space-based astronomical and spectroscopic applications.

  20. The sensitivity calibration of the ultra-fast quench plastic scintillation detector for D-T neutrons

    International Nuclear Information System (INIS)

    Tang Changhuan; Yan Meiqiong; Xie Chaomei

    1998-01-01

    The authors introduce some characteristics of ultra-fast quench plastic scintillation detectors. When the detectors are composed of different scintillators, light guides and microchannel plate photomultiplier tube (MCP-PMT), their sensitivities to D-T neutrons are calibrated by a pulse neutron tube with a neutron pulse width about 10 ns

  1. Readout for a large area neutron sensitive microchannel plate detector

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yiming [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); Yang, Yigang, E-mail: yangyigang@mail.tsinghua.edu.cn [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China); Wang, Xuewu; Li, Yuanjing [Department of Engineering Physics, Tsinghua University, Beijing (China); Key Laboratory of Particle & Radiation Imaging, Tsinghua University, Ministry of Education, Beijing (China)

    2015-06-01

    A neutron sensitive microchannel plate (MCP) detector was developed for neutron imaging on the beamline of a compact pulsed hadron source (CPHS). The detector was set up with a Wedge-and-Strip Anode (WSA) and a delay line anode readout to compare the spatial resolution and throughput with these two anodes. Tests show that the WSA readout is suitable for small area imaging with a spatial resolution of 200 μm with low energy X-rays in a 50 mm diameter MCP–WSA assembly. However, the spatial resolution deteriorated to ~2 mm in a 106 mm diameter MCP–WSA assembly because the noise caused by the parasitic capacitance is 10 times larger in the larger assembly than in the 50 mm diameter assembly. A 120 mm by 120 mm delay line anode was then used for the 106 mm MCP readout. The spatial resolution was evaluated for various voltages applied to the MCP V-stack, various readout voltages and various distances between the MCP V-stack rear face and the delay line. The delay line readout had resolutions of 65.6 μm in the x direction and 63.7 μm in the y direction and the throughput was greater than 600 kcps. The MCP was then used to acquire a neutron image of an USAF1951 Gd-mask.

  2. Improved lifetime of microchannel-plate PMTs

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, A., E-mail: lehmann@physik.uni-erlangen.de [Physikalisches Institut IV, Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); Britting, A.; Eyrich, W.; Uhlig, F. [Physikalisches Institut IV, Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Höhler, R.; Kalicy, G.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Zühlsdorf, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); and others

    2014-12-01

    The charged particle identification at the PANDA experiment will be mainly performed with DIRC detectors. Because of their advantageous properties the preferred photon sensors are MCP-PMTs. However, until recently these devices showed serious aging problems which resulted in a diminishing quantum efficiency (QE) of the photo cathode. By applying innovative countermeasures against the aging causes, the manufacturers recently succeeded in drastically improving the lifetime of MCP-PMTs. Especially the application of an ALD coating technique to seal the material of the micro-channels proves very powerful and results in a lifetime of ≈6C/cm{sup 2} integrated anode charge without a substantial QE degradation for the latest PHOTONIS XP85112. This paper will present a comparative measurement of the lifetime of several older and recent MCP-PMTs demonstrating this progress.

  3. The Parameterization of Top-Hat Particle Sensors with Microchannel-Plate-Based Detection Systems and its Application to the Fast Plasma Investigation on NASA's Magnetospheric MultiScale Mission

    Science.gov (United States)

    Gershman, Daniel J.; Gliese, Ulrik; Dorelli, John C.; Avanov, Levon A.; Barrie, Alexander C.; Chornay, Dennis J.; MacDonald, Elizabeth A.; Holland, Matthew P.; Pollock, Craig J.

    2015-01-01

    The most common instrument for low energy plasmas consists of a top-hat electrostatic analyzer geometry coupled with a microchannel-plate (MCP)-based detection system. While the electrostatic optics for such sensors are readily simulated and parameterized during the laboratory calibration process, the detection system is often less well characterized. Furthermore, due to finite resources, for large sensor suites such as the Fast Plasma Investigation (FPI) on NASA's Magnetospheric Multiscale (MMS) mission, calibration data are increasingly sparse. Measurements must be interpolated and extrapolated to understand instrument behavior for untestable operating modes and yet sensor inter-calibration is critical to mission success. To characterize instruments from a minimal set of parameters we have developed the first comprehensive mathematical description of both sensor electrostatic optics and particle detection systems. We include effects of MCP efficiency, gain, scattering, capacitive crosstalk, and charge cloud spreading at the detector output. Our parameterization enables the interpolation and extrapolation of instrument response to all relevant particle energies, detector high voltage settings, and polar angles from a small set of calibration data. We apply this model to the 32 sensor heads in the Dual Electron Sensor (DES) and 32 sensor heads in the Dual Ion Sensor (DIS) instruments on the 4 MMS observatories and use least squares fitting of calibration data to extract all key instrument parameters. Parameters that will evolve in flight, namely MCP gain, will be determined daily through application of this model to specifically tailored in-flight calibration activities, providing a robust characterization of sensor suite performance throughout mission lifetime. Beyond FPI, our model provides a valuable framework for the simulation and evaluation of future detection system designs and can be used to maximize instrument understanding with minimal calibration

  4. Analogue saturation limit of single and double 10 mm microchannel plate photomultiplier tubes

    Energy Technology Data Exchange (ETDEWEB)

    Milnes, J. S., E-mail: james.milnes@photek.co.uk; Conneely, T. M. [Photek Ltd., 26 Castleham Road, St Leonards on Sea, East Sussex TN38 9NS (United Kingdom); Horsfield, C. J. [AWE Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom)

    2016-11-15

    Photek are a well-established supplier of microchannel plate (MCP) photomultiplier tubes (PMTs) to the inertial confinement fusion community. The analogue signals produced at the major inertial confinement fusion facilities cover many orders of magnitude, therefore understanding the upper saturation limit of MCP-PMTs to large low rate signals takes on a high importance. Here we present a study of a single and a double MCP-PMT with 10 mm diameter active area. The saturation was studied for a range of optical pulse widths from 4 ns to 100 ns and at a range of electron gain values: 10{sup 3} to 10{sup 4} for the single and 10{sup 4} to 10{sup 6} for the double. We have shown that the saturation level of ∼1.2 nC depends only on the integrated charge of the pulse and is independent of pulse width and gain over this range, but that the level of charge available in deep saturation is proportional to the operating gain.

  5. Uses of microchannel plate intensified detectors for imaging applications in the X-ray, EUV and visible wavelength regions

    International Nuclear Information System (INIS)

    Read, P.D.; Carter, M.K.; Pike, C.D.; Harrison, R.A.; Kent, B.J.; Swinyard, B.M.; Patchett, B.E.; Redfern, R.M.; Shearer, A.; Colhoun, M.

    1997-01-01

    The Rutherford Appleton laboratory photon counting detector (RALPCD) has been refined to meet project requirements for a flexible imaging arrangement with applications at X-ray, EUV and visible wavelengths. The basic detector design comprises commercially available high gain microchannel plate intensifiers fibre optically coupled to CID or CCD cameras, to form a modular detector arrangement with the appropriate RAL detection and centroiding software. Frames of data from the cameras are detected and centroided in a transputer or C40 parallel processor array where correction algorithms use look up tables to produce pattern free images at high resolution. Data from completed applications are used to illustrate the performance and future advances are discussed. (orig.)

  6. Preliminary examination of the applicability of imaging plates to fast neutron radiography

    International Nuclear Information System (INIS)

    Matsubayashi, Masahito; Hibiki, Takashi; Mishima, Kaichiro; Yoshii, Koji; Okamoto, Koji

    2001-01-01

    Fast neutron radiography is an attractive non-destructive inspection technique because of the excellent penetration characteristics of fast neutrons in matter. However, the difficulty of detecting fast neutrons reduces this attractive feature. As an experiment to overcome the difficulty, imaging plates were applied to fast neutron radiography. A simple combination of two sheets of imaging plates and a sheet of polyethylene as a proton emitter was examined with the (fast neutron, thermal neutron and gamma ray) FTG discriminator proposed by Yoneda et al. . The experimental results showed that the method could be applicable to fast neutron radiography with effective discrimination of γ-rays

  7. Two and three dimensional imaging of compact toroid plasmas using fast photography

    International Nuclear Information System (INIS)

    Englert, S.E.; Bell, D.E.; Coffey, S.K.

    1992-01-01

    As is discussed in a companion paper, Degnan el al, fast photography is used as a visual diagnostic tool for high energy plasma research at the Phillips Laboratory. Both, two dimensional and three dimensional images, are gathered by using nanosecond and microsecond range fast photography techniques. A set of microchannel plate cameras and a fast framing camera are used to record images of a compact toroid plasma during formation and acceleration stages. These images are subsequently digitized and enhanced to bring out detailed information of interest. This spatial information is combined with other diagnostic results as well as theoretical models in order to build a more complete picture of the fundamental physics associated with high-energy plasmas

  8. Gain uniformity, linearity, saturation and depletion in gated microchannel-plate x-ray framing cameras

    International Nuclear Information System (INIS)

    Landen, O.L.; Bell, P.M.; Satariano, J.J.; Oertel, J.A.; Bradley, D.K.

    1994-01-01

    The pulsed characteristics of gated, stripline configuration microchannel-plate (MCP) detectors used in X-ray framing cameras deployed on laser plasma experiments worldwide are examined in greater detail. The detectors are calibrated using short (20 ps) and long (500 ps) pulse X-ray irradiation and 3--60 ps, deep UV (202 and 213 nm), spatially-smoothed laser irradiation. Two-dimensional unsaturated gain profiles show 5 in irradiation and fitted using a discrete dynode model. Finally, a pump-probe experiment quantifying for the first time long-suspected gain depletion by strong localized irradiation was performed. The mechanism for the extra voltage and hence gain degradation is shown to be associated with intense MCP irradiation in the presence of the voltage pulse, at a fluence at least an order of magnitude above that necessary for saturation. Results obtained for both constant pump area and constant pump fluence are presented. The data are well modeled by calculating the instantaneous electrical energy loss due to the intense charge extraction at the pump site and then recalculating the gain downstream at the probe site given the pump-dependent degradation in voltage amplitude

  9. Examination of the spatial-response uniformity of a microchannel-plate detector using a pulsed high-voltage electron gun

    International Nuclear Information System (INIS)

    Alumot, D; Kroupp, E; Fisher, A

    2014-01-01

    In this paper we describe an alternative method to examine the spatial-response uniformity of a microchannel-plate (MCP) detector to a ∼ 1 ns pulse of soft x-rays. The examination was performed by illuminating the MCP surface with energetic electrons rather than with x-rays. It is shown that the MCP features similar, yet not identical, response to pulses of soft x-ray photons or energetic electrons, making such examinations much simpler and less expensive. The building of the electron-gun system is relatively easy and inexpensive, and in addition to verifying the spatial uniformity of the response of the MCP to incoming particles and radiation, it can be used to detect damaged areas on the detector. A comparison between the results obtained using the electron-gun with those obtained using a laser-produced-plasma x-ray source, demonstrating the reliability of the method, is presented

  10. A new license plate extraction framework based on fast mean shift

    Science.gov (United States)

    Pan, Luning; Li, Shuguang

    2010-08-01

    License plate extraction is considered to be the most crucial step of Automatic license plate recognition (ALPR) system. In this paper, a region-based license plate hybrid detection method is proposed to solve practical problems under complex background in which existing large quantity of disturbing information. In this method, coarse license plate location is carried out firstly to get the head part of a vehicle. Then a new Fast Mean Shift method based on random sampling of Kernel Density Estimate (KDE) is adopted to segment the color vehicle images, in order to get candidate license plate regions. The remarkable speed-up it brings makes Mean Shift segmentation more suitable for this application. Feature extraction and classification is used to accurately separate license plate from other candidate regions. At last, tilted license plate regulation is used for future recognition steps.

  11. Micro-PIV/LIF measurements on electrokinetically-driven flow in surface modified microchannels

    International Nuclear Information System (INIS)

    Ichiyanagi, Mitsuhisa; Sasaki, Seiichi; Sato, Yohei; Hishida, Koichi

    2009-01-01

    Effects of surface modification patterning on flow characteristics were investigated experimentally by measuring electroosmotic flow velocities, which were obtained by micron-resolution particle image velocimetry using a confocal microscope. The depth-wise velocity was evaluated by using the continuity equation and the velocity data. The microchannel was composed of a poly(dimethylsiloxane) chip and a borosilicate cover-glass plate. Surface modification patterns were fabricated by modifying octadecyltrichlorosilane (OTS) on the glass surface. OTS can decrease the electroosmotic flow velocity compared to the velocity in the glass microchannel. For the surface charge varying parallel to the electric field, the depth-wise velocity was generated at the boundary area between OTS and the glass surfaces. For the surface charge varying perpendicular to the electric field, the depth-wise velocity did not form because the surface charge did not vary in the stream-wise direction. The surface charge pattern with the oblique stripes yielded a three-dimensional flow in a microchannel. Furthermore, the oblique patterning was applied to a mixing flow field in a T-shaped microchannel, and mixing efficiencies were evaluated from heterogeneity degree of fluorescent dye intensity, which was obtained by laser-induced fluorescence. It was found that the angle of the oblique stripes is an important factor to promote the span-wise and depth-wise momentum transport and contributes to the mixing flow in a microchannel

  12. Experimental investigation of thermoelectric power generation versus coolant pumping power in a microchannel heat sink

    DEFF Research Database (Denmark)

    Kolaei, Alireza Rezania; Rosendahl, Lasse; Andreasen, Søren Juhl

    2012-01-01

    The coolant heat sinks in thermoelectric generators (TEG) play an important role in order to power generation in the energy systems. This paper explores the effective pumping power required for the TEGs cooling at five temperature difference of the hot and cold sides of the TEG. In addition......, the temperature distribution and the pressure drop in sample microchannels are considered at four sample coolant flow rates. The heat sink contains twenty plate-fin microchannels with hydraulic diameter equal to 0.93 mm. The experimental results show that there is a unique flow rate that gives maximum net-power...

  13. Static response of deformable microchannels

    Science.gov (United States)

    Christov, Ivan C.; Sidhore, Tanmay C.

    2017-11-01

    Microfluidic channels manufactured from PDMS are a key component of lab-on-a-chip devices. Experimentally, rectangular microchannels are found to deform into a non-rectangular cross-section due to fluid-structure interactions. Deformation affects the flow profile, which results in a nonlinear relationship between the volumetric flow rate and the pressure drop. We develop a framework, within the lubrication approximation (l >> w >> h), to self-consistently derive flow rate-pressure drop relations. Emphasis is placed on handling different types of elastic response: from pure plate-bending, to half-space deformation, to membrane stretching. The ``simplest'' model (Stokes flow in a 3D rectangular channel capped with a linearly elastic Kirchhoff-Love plate) agrees well with recent experiments. We also simulate the static response of such microfluidic channels under laminar flow conditions using ANSYSWorkbench. Simulations are calibrated using experimental flow rate-pressure drop data from the literature. The simulations provide highly resolved deformation profiles, which are difficult to measure experimentally. By comparing simulations, experiments and our theoretical models, we show good agreement in many flow/deformation regimes, without any fitting parameters.

  14. Stress wave calculations in composite plates using the fast Fourier transform.

    Science.gov (United States)

    Moon, F. C.

    1973-01-01

    The protection of composite turbine fan blades against impact forces has prompted the study of dynamic stresses in composites due to transient loads. The mathematical model treats the laminated plate as an equivalent anisotropic material. The use of Mindlin's approximate theory of crystal plates results in five two-dimensional stress waves. Three of the waves are flexural and two involve in-plane extensional strains. The initial value problem due to a transient distributed transverse force on the plate is solved using Laplace and Fourier transforms. A fast computer program for inverting the two-dimensional Fourier transform is used. Stress contours for various stresses and times after application of load are obtained for a graphite fiber-epoxy matrix composite plate. Results indicate that the points of maximum stress travel along the fiber directions.

  15. Development of a single-photon-counting camera with use of a triple-stacked micro-channel plate.

    Science.gov (United States)

    Yasuda, Naruomi; Suzuki, Hitoshi; Katafuchi, Tetsuro

    2016-01-01

    At the quantum-mechanical level, all substances (not merely electromagnetic waves such as light and X-rays) exhibit wave–particle duality. Whereas students of radiation science can easily understand the wave nature of electromagnetic waves, the particle (photon) nature may elude them. Therefore, to assist students in understanding the wave–particle duality of electromagnetic waves, we have developed a photon-counting camera that captures single photons in two-dimensional images. As an image intensifier, this camera has a triple-stacked micro-channel plate (MCP) with an amplification factor of 10(6). The ultra-low light of a single photon entering the camera is first converted to an electron through the photoelectric effect on the photocathode. The electron is intensified by the triple-stacked MCP and then converted to a visible light distribution, which is measured by a high-sensitivity complementary metal oxide semiconductor image sensor. Because it detects individual photons, the photon-counting camera is expected to provide students with a complete understanding of the particle nature of electromagnetic waves. Moreover, it measures ultra-weak light that cannot be detected by ordinary low-sensitivity cameras. Therefore, it is suitable for experimental research on scintillator luminescence, biophoton detection, and similar topics.

  16. Photochemical immobilization of protein on the inner wall of a microchannel and Its application in a glucose sensor

    International Nuclear Information System (INIS)

    Nakajima, Hizuru; Ishino, Satomi; Masuda, Hironori; Nakagama, Tatsuro; Shimosaka, Takuya; Uchiyama, Katsumi

    2006-01-01

    A new protein immobilization technique has been developed for patterning enzymes in a specific position inside a microchannel. First, bovine serum albumin (BSA) was adsorbed onto the internal surface of a polydimethylsiloxane microchannel. The microchannel was then filled with the conjugate solution of a photoreactive cross-linker, 4-azido-2,3,5,6-tetrafluorobenzoic acid succinimidyl ester (ATFB-SE), and an enzyme, horseradish peroxidase (HRP). An irradiation by a He-Cd laser activated the azido group of the conjugates and these conjugates became covalently attached to the adsorbed BSA on the microchannel. The enzyme turnover was observed from only the HRP zone. This technique was successfully applied to the enzymatic glucose sensor. Glucose oxidase (GOD) and HRP were sequentially patterned in a single microchannel, i.e., the HRP zone was located downstream from the GOD zone. The calibration curve of a glucose standard solution was linear over the range of 0-128 μM with a correlation coefficient of 0.993. Compared to the traditional method using a 96-well microtiter plate, the present technique on the microchip shortened the reaction time from 30 min to 4.8 s, i.e., to 1/375

  17. Simulation of the effects of coated material SEY property on output electron energy distribution and gain of microchannel plates

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lin [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Xingchao [North Night Vision Technology (NNVT) Co., Ltd., Nanjing 210110 (China); Tian, Jinshou, E-mail: tianjs@opt.ac.cn [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006 (China); Liu, Chunliang [Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Hulin [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Chen, Ping [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Graduate School of Chinese Academy of Sciences (CAS), Beijing 100049 (China); Wei, Yonglin; Sai, Xiaofeng [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); Sun, Jianning; Si, Shuguang [North Night Vision Technology (NNVT) Co., Ltd., Nanjing 210110 (China); Wang, Xing; Lu, Yu [Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology, Xi' an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi' an 710119 (China); and others

    2016-12-21

    To obtain a high spatial resolution of a image intensifier based on microchannel plate (MCP), the long tail in the exit energy distribution of the output electrons (EDOE) is undesirable. The existing solution is increasing the penetration depth of the MCP output electrode, which will result in a serious gain reduction. Coating the MCP output electrode with efficient secondary electron yield (SEY) materials is supposed to be an effective approach to suppress the unfavorable tail component in the EDOE without negative effects on the gain. In our work, a three-dimensional MCP single channel model is developed in CST STUDIO SUITE to systematically investigate the dependences of the EDOE and the gain on the SEY property of the coated material, based on the Finite Integral Technique and Monte Carlo method. The results show that besides the high SEY of the coated material, the low incident energy corresponding to the peak SEY is another essential element affecting the electron yield in the final stage of multiplication and suppressing the output energy spread.

  18. Entropy generation minimization of a MHD (magnetohydrodynamic) flow in a microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Guillermo [Universidad de Ciencias y Artes de Chiapas, Tuxtla Gutierrez, Chiapas 29000 (Mexico); Cuevas, Sergio [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico A.P. 34, Temixco, Mor. 62580 (Mexico)

    2010-10-15

    The dissipative processes that arise in a microchannel flow subjected to electromagnetic interactions, as occurs in a MHD (magnetohydrodynamic) micropump, are analyzed. The entropy generation rate is used as a tool for the assessment of the intrinsic irreversibilities present in the microchannel owing to viscous friction, heat flow and electric conduction. The flow in a parallel plate microchannel produced by a Lorentz force created by a transverse magnetic field and an injected electric current is considered assuming a thermally fully developed flow and conducting walls of finite thickness. The conjugate heat transfer problem in the fluid and solid walls is solved analytically using thermal boundary conditions of the third kind at the outer surfaces of the walls and continuity of temperature and heat flux across the fluid-wall interfaces. Velocity, temperature and current density fields in the fluid and walls are used to calculate the global entropy generation rate. Conditions under which this quantity is minimized are determined for specific values of the geometrical and physical parameters of the system. The Nusselt number is also calculated and explored for different conditions. Results can be used to determine optimized conditions that lead to a minimum dissipation consistent with the physical constraints demanded by the microdevice. (author)

  19. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    International Nuclear Information System (INIS)

    Bizzeti, A.; Civinini, C.; D'alessandro, R.; Ferrando, A.

    1993-01-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LBC; based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (117 mn each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author)

  20. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    Energy Technology Data Exchange (ETDEWEB)

    Bizzeti, A.; Civinini, C.; D' Alessandro, R.; Ferrando, A.; Malinin, A.; Martinez-Laso, L.; Pojidaev, V.

    1993-07-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LHC, based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (17 mm each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author) 7 refs.

  1. Performance of a parallel plate volume cell prototype for a fast iron/gas calorimeter

    International Nuclear Information System (INIS)

    Bizzeti, A.; Civinini, C.; D'Alessandro, R.; Ferrando, A.; Malinin, A.; Martinez-Laso, L.; Pojidaev, V.

    1993-01-01

    We present the first test of the application of the parallel plate chamber principles for the design of a very fast and radiation-hard iron/gas sampling calorimeter, suitable for very forward regions in detectors for LHC, based on the use of thick iron plates as electrodes. We have built a one cell prototype consisting of three parallel thick iron plates (17 mm each). Results on efficiencies and mean collected charge for minimum ionizing particles with different gases are presented. (Author) 7 refs

  2. Hydrophilic Surface Modification of PDMS Microchannel for O/W and W/O/W Emulsions

    Directory of Open Access Journals (Sweden)

    Shazia Bashir

    2015-09-01

    Full Text Available A surface modification method for bonded polydimethylsiloxane (PDMS microchannels is presented herein. Polymerization of acrylic acid was performed on the surface of a microchannel using an inline atmospheric pressure dielectric barrier microplasma technique. The surface treatment changes the wettability of the microchannel from hydrophobic to hydrophilic. This is a challenging task due to the fast hydrophobic recovery of the PDMS surface after modification. This modification allows the formation of highly monodisperse oil-in-water (O/W droplets. The generation of water-in-oil-in-water (W/O/W double emulsions was successfully achieved by connecting in series a hydrophobic microchip with a modified hydrophilic microchip. An original channel blocking technique to pattern the surface wettability of a specific section of a microchip using a viscous liquid comprising a mixture of honey and glycerol, is also presented for generating W/O/W emulsions on a single chip.

  3. Fast neutron radiography using photoluminescent imaging plates

    International Nuclear Information System (INIS)

    Rant, J.; Kristof, E.; Balasko, M.; Stade, J.

    1999-01-01

    Fast neutron radiography (FNR) and resonance neutron radiography (RNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation used for the inspection of thick metal objects. In both non-destructive methods, the contrast sensitivity and the penetration power can be improved by using higher energy neutrons. At present direct techniques based either n Solid State Nuclear Track detectors (SSNTDs) or scintillating screens and transfer techniques using activation threshold detectors and radiographic films are applied for the detection of fast neutron images. Rather low detection sensitivity of film and SSNTD based fast neutron imaging methods and also rather poor inherent image contrast of SSNTD pose a problem for FNR in the fast neutron energy region 1-15 MeV interesting for NDT. For more efficient detection of fast neutron images the use of novel highly sensitive photoluminescent imaging plates (IP) in combination with threshold at the KFKI research reactor. The conventional IP produced by FUJI Photo Film Co. for the detection of beta and X-ray radiation were used. The threshold activation detectors were the reactions 115 In(n, n') 115m In, 64 Zn(n,p) 64 Cu, 56 Fe(n, p) 56 Mn, 24 Mg(n, p) 24 Na and 27 Al(n, α) 24 Na. These threshold reactions cover the fast neutron energy region between 0,7 MeV and 12 MeV. Pure, commercially available metals 0,1 mm to 0,25 mm thick made of In, Zn, Fe, Mg and Al were used as converter screens. The very high sensitivity of IP, the linearity of their response over 5 decades of exposure dose and the high dynamic digitalisation latitude enabled fast neutron radiography of image quality comparable to the quality of thermal NR. In our experimental conditions (φ n ∼ 10 8 n/cm 2 s, R Cd ∼ 2) the neutron exposure and IP exposure periods were still practical and comparable to the half life of the corresponding reaction products (half an hour to several hours). Even with the 27 Al(n.α) 24

  4. Evaporative CO$_2$ microchannel cooling for the LHCb VELO pixel upgrade

    CERN Document Server

    de Aguiar Francisco, Oscar A; Collins, Paula; Dumps, Raphael; John, Malcolm; Mapelli, Alessandro; Romagnoli, Giulia

    2015-01-01

    The LHCb Vertex Detector (VELO) will be upgraded in 2018 to a lightweight pixel detector capable of 40 MHz readout and operation in very close proximity to the LHC beams. The thermal management of the system will be provided by evaporative CO$_2$ circulating in microchannels embedded within thin silicon plates. This solution has been selected due to the excellent thermal efficiency, the absence of thermal expansion mismatch with silicon ASICs and sensors, the radiation hardness of CO$_2$, and very low contribution to the material budget. Although microchannel cooling is gaining considerable attention for applications related to microelectronics, it is still a novel technology for particle physics experiments, in particular when combined with evaporative CO$_2$ cooling. The R&D effort for LHCb is focused on the design and layout of the channels together with a fluidic connector and its attachment which must withstand pressures up to 170 bar. Even distribution of the coolant is ensured by means of the use o...

  5. Separation process using microchannel technology

    Science.gov (United States)

    Tonkovich, Anna Lee [Dublin, OH; Perry, Steven T [Galloway, OH; Arora, Ravi [Dublin, OH; Qiu, Dongming [Bothell, WA; Lamont, Michael Jay [Hilliard, OH; Burwell, Deanna [Cleveland Heights, OH; Dritz, Terence Andrew [Worthington, OH; McDaniel, Jeffrey S [Columbus, OH; Rogers, Jr; William, A [Marysville, OH; Silva, Laura J [Dublin, OH; Weidert, Daniel J [Lewis Center, OH; Simmons, Wayne W [Dublin, OH; Chadwell, G Bradley [Reynoldsburg, OH

    2009-03-24

    The disclosed invention relates to a process and apparatus for separating a first fluid from a fluid mixture comprising the first fluid. The process comprises: (A) flowing the fluid mixture into a microchannel separator in contact with a sorption medium, the fluid mixture being maintained in the microchannel separator until at least part of the first fluid is sorbed by the sorption medium, removing non-sorbed parts of the fluid mixture from the microchannel separator; and (B) desorbing first fluid from the sorption medium and removing desorbed first fluid from the microchannel separator. The process and apparatus are suitable for separating nitrogen or methane from a fluid mixture comprising nitrogen and methane. The process and apparatus may be used for rejecting nitrogen in the upgrading of sub-quality methane.

  6. License plate localization in complex scenes based on oriented FAST and rotated BRIEF feature

    Science.gov (United States)

    Wang, Ran; Xia, Yuanchun; Wang, Guoyou; Tian, Jiangmin

    2015-09-01

    Within intelligent transportation systems, fast and robust license plate localization (LPL) in complex scenes is still a challenging task. Real-world scenes introduce complexities such as variation in license plate size and orientation, uneven illumination, background clutter, and nonplate objects. These complexities lead to poor performance using traditional LPL features, such as color, edge, and texture. Recently, state-of-the-art performance in LPL has been achieved by applying the scale invariant feature transform (SIFT) descriptor to LPL for visual matching. However, for applications that require fast processing, such as mobile phones, SIFT does not meet the efficiency requirement due to its relatively slow computational speed. To address this problem, a new approach for LPL, which uses the oriented FAST and rotated BRIEF (ORB) feature detector, is proposed. The feature extraction in ORB is much more efficient than in SIFT and is invariant to scale and grayscale as well as rotation changes, and hence is able to provide superior performance for LPL. The potential regions of a license plate are detected by considering spatial and color information simultaneously, which is different from previous approaches. The experimental results on a challenging dataset demonstrate the effectiveness and efficiency of the proposed method.

  7. Improved Detection System Description and New Method for Accurate Calibration of Micro-Channel Plate Based Instruments and Its Use in the Fast Plasma Investigation on NASA's Magnetospheric MultiScale Mission

    Science.gov (United States)

    Gliese, U.; Avanov, L. A.; Barrie, A. C.; Kujawski, J. T.; Mariano, A. J.; Tucker, C. J.; Chornay, D. J.; Cao, N. T.; Gershman, D. J.; Dorelli, J. C.; hide

    2015-01-01

    The Fast Plasma Investigation (FPI) on NASAs Magnetospheric MultiScale (MMS) mission employs 16 Dual Electron Spectrometers (DESs) and 16 Dual Ion Spectrometers (DISs) with 4 of each type on each of 4 spacecraft to enable fast (30 ms for electrons; 150 ms for ions) and spatially differentiated measurements of the full 3D particle velocity distributions. This approach presents a new and challenging aspect to the calibration and operation of these instruments on ground and in flight. The response uniformity, the reliability of their calibration and the approach to handling any temporal evolution of these calibrated characteristics all assume enhanced importance in this application, where we attempt to understand the meaning of particle distributions within the ion and electron diffusion regions of magnetically reconnecting plasmas. Traditionally, the micro-channel plate (MCP) based detection systems for electrostatic particle spectrometers have been calibrated using the plateau curve technique. In this, a fixed detection threshold is set. The detection system count rate is then measured as a function of MCP voltage to determine the MCP voltage that ensures the count rate has reached a constant value independent of further variation in the MCP voltage. This is achieved when most of the MCP pulse height distribution (PHD) is located at higher values (larger pulses) than the detection system discrimination threshold. This method is adequate in single-channel detection systems and in multi-channel detection systems with very low crosstalk between channels. However, in dense multi-channel systems, it can be inadequate. Furthermore, it fails to fully describe the behavior of the detection system and individually characterize each of its fundamental parameters. To improve this situation, we have developed a detailed phenomenological description of the detection system, its behavior and its signal, crosstalk and noise sources. Based on this, we have devised a new detection

  8. Three-dimensional supercapacitors composed of Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} (BST)/NiSi{sub 2}/silicon microchannel plates

    Energy Technology Data Exchange (ETDEWEB)

    Liu Tao; Zhang Huayan; Wang Fei; Shi Jing; Ci Pengliang [Laboratory of Polar Materials and Devices, Ministry of Education, and Department of Electronic Engineering, East China Normal University, 500 Dongchuan Road, Minhang District, Shanghai 200241 (China); Wang Lianwei, E-mail: lwwang@ee.ecnu.edu.cn [Laboratory of Polar Materials and Devices, Ministry of Education, and Department of Electronic Engineering, East China Normal University, 500 Dongchuan Road, Minhang District, Shanghai 200241 (China); Ge Shuli; Wang Qingjiang [Department of Chemistry, East China Normal University, Shanghai 200241 (China); Chu, Paul K. [Department of Physics and Material Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

    2011-03-25

    Three-dimensional (3D) supercapacitors consisting of Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} (BST)/NiSi{sub 2}/silicon microchannel plate (MCP) stacked structure have been fabricated. The silicon MCP produced by electrochemical etching is utilized as a backbone of the 3D structure on which a nickel silicide current collector layer and Ba{sub 0.65}Sr{sub 0.35}TiO{sub 3} dielectric layer are deposited successively by electroless plating and the sol-gel method, respectively. The morphology and structure of the 3D BST/NiSi{sub 2}/Si-MCP structure are characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and the electrochemical properties are determined by cyclic voltammetry (CV) and chronopotentiometry. The structure exhibits excellent capacitive behavior with a maximum capacitance of 784 F g{sup -1}. After 700 charging/discharging cycles, the C{sub f} decreases slightly with only a 5.7% loss and is stable after more than 700 cycles. The BST/NiSi{sub 2}/Si-MCP 3D structure is a potential supercapacitor in industrial applications.

  9. Field-effect Flow Control in Polymer Microchannel Networks

    Science.gov (United States)

    Sniadecki, Nathan; Lee, Cheng S.; Beamesderfer, Mike; DeVoe, Don L.

    2003-01-01

    A new Bio-MEMS electroosmotic flow (EOF) modulator for plastic microchannel networks has been developed. The EOF modulator uses field-effect flow control (FEFC) to adjust the zeta potential at the Parylene C microchannel wall. By setting a differential EOF pumping rate in two of the three microchannels at a T-intersection with EOF modulators, the induced pressure at the intersection generated pumping in the third, field-free microchannel. The EOF modulators are able to change the magnitude and direction of the pressure pumping by inducing either a negative or positive pressure at the intersection. The flow velocity is tracked by neutralized fluorescent microbeads in the microchannels. The proof-of-concept of the EOF modulator described here may be applied to complex plastic ,microchannel networks where individual microchannel flow rates are addressable by localized induced-pressure pumping.

  10. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Neumark, D.M. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  11. Instability in flow boiling in microchannels

    CERN Document Server

    Saha, Sujoy Kumar

    2016-01-01

    This Brief addresses the phenomena of instability in flow boiling in microchannels occurring in high heat flux electronic cooling. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Critical Heat Flux in Flow Boiling in Microchannels,” and "Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,"by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.

  12. A review of entropy generation in microchannels

    Directory of Open Access Journals (Sweden)

    Mohamed M Awad

    2015-12-01

    Full Text Available In this study, a critical review of thermodynamic optimum of microchannels based on entropy generation analysis is presented. Using entropy generation analysis as evaluation parameter of microchannels has been reported by many studies in the literature. In these studies, different working fluids such as nanofluids, air, water, engine oil, aniline, ethylene glycol, and non-Newtonian fluids have been used. For the case of nanofluids, “nanoparticles” has been used in various kinds such as Al2O3 and Cu, and “base fluid” has been used in various kinds such as water and ethylene glycol. Furthermore, studies on thermodynamic optimum of microchannels based on entropy generation analysis are summarized in a table. At the end, recommendations of future work for thermodynamic optimum of microchannels based on entropy generation analysis are given. As a result, this article can not only be used as the starting point for the researcher interested in entropy generation in microchannels, but it also includes recommendations for future studies on entropy generation in microchannels.

  13. A highly stable microchannel heat sink for convective boiling

    International Nuclear Information System (INIS)

    Lu, Chun Ting; Pan Chin

    2009-01-01

    To develop a highly stable two-phase microchannel heat sink, we experimented with convective boiling in diverging, parallel microchannels with different distributions of laser-etched artificial nucleation sites. Each microchannel had a mean hydraulic diameter of 120 µm. The two-phase flow visualization and the magnitudes of pressure drop and inlet temperature oscillations under boiling conditions demonstrated clearly the merits of using artificial nucleation sites to further stabilize the flow boiling in diverging, parallel microchannels. The stability map showed the plane of subcooling number versus phase change number. It illustrated that diverging, parallel microchannels with artificial nucleation cavities have a much wider stable region than parallel microchannels with uniform cross-sections or diverging, parallel microchannels without artificial nucleation cavities. In addition, the results revealed that the design with cavities distributed uniformly along the downstream half of the channel presented the best stability performance among the three distributions of nucleation sites. This particular design can be regarded as a highly stable microchannel heat sink for convective boiling

  14. A High-Speed, Event-Driven, Active Pixel Sensor Readout for Photon-Counting Microchannel Plate Detectors

    Science.gov (United States)

    Kimble, Randy A.; Pain, Bedabrata; Norton, Timothy J.; Haas, J. Patrick; Oegerle, William R. (Technical Monitor)

    2002-01-01

    Silicon array readouts for microchannel plate intensifiers offer several attractive features. In this class of detector, the electron cloud output of the MCP intensifier is converted to visible light by a phosphor; that light is then fiber-optically coupled to the silicon array. In photon-counting mode, the resulting light splashes on the silicon array are recognized and centroided to fractional pixel accuracy by off-chip electronics. This process can result in very high (MCP-limited) spatial resolution while operating at a modest MCP gain (desirable for dynamic range and long term stability). The principal limitation of intensified CCD systems of this type is their severely limited local dynamic range, as accurate photon counting is achieved only if there are not overlapping event splashes within the frame time of the device. This problem can be ameliorated somewhat by processing events only in pre-selected windows of interest of by using an addressable charge injection device (CID) for the readout array. We are currently pursuing the development of an intriguing alternative readout concept based on using an event-driven CMOS Active Pixel Sensor. APS technology permits the incorporation of discriminator circuitry within each pixel. When coupled with suitable CMOS logic outside the array area, the discriminator circuitry can be used to trigger the readout of small sub-array windows only when and where an event splash has been detected, completely eliminating the local dynamic range problem, while achieving a high global count rate capability and maintaining high spatial resolution. We elaborate on this concept and present our progress toward implementing an event-driven APS readout.

  15. Next Generation Microchannel Heat Exchangers

    CERN Document Server

    Ohadi, Michael; Dessiatoun, Serguei; Cetegen, Edvin

    2013-01-01

    In Next Generation Microchannel Heat Exchangers, the authors’ focus on the new generation highly efficient heat exchangers and presentation of novel data and technical expertise not available in the open literature.  Next generation micro channels offer record high heat transfer coefficients with pressure drops much less than conventional micro channel heat exchangers. These inherent features promise fast penetration into many mew markets, including high heat flux cooling of electronics, waste heat recovery and energy efficiency enhancement applications, alternative energy systems, as well as applications in mass exchangers and chemical reactor systems. The combination of up to the minute research findings and technical know-how make this book very timely as the search for high performance heat and mass exchangers that can cut costs in materials consumption intensifies.

  16. Experimental evaluation of the response of micro-channel plate detector to ions with 10s of MeV energies

    Science.gov (United States)

    Jeong, Tae Won; Singh, P. K.; Scullion, C.; Ahmed, H.; Kakolee, K. F.; Hadjisolomou, P.; Alejo, A.; Kar, S.; Borghesi, M.; Ter-Avetisyan, S.

    2016-08-01

    The absolute calibration of a microchannel plate (MCP) assembly using a Thomson spectrometer for laser-driven ion beams is described. In order to obtain the response of the whole detection system to the particles' impact, a slotted solid state nuclear track detector (CR-39) was installed in front of the MCP to record the ions simultaneously on both detectors. The response of the MCP (counts/particles) was measured for 5-58 MeV carbon ions and for protons in the energy range 2-17.3 MeV. The response of the MCP detector is non-trivial when the stopping range of particles becomes larger than the thickness of the detector. Protons with energies E ≳ 10 MeV are energetic enough that they can pass through the MCP detector. Quantitative analysis of the pits formed in CR-39 and the signal generated in the MCP allowed to determine the MCP response to particles in this energy range. Moreover, a theoretical model allows to predict the response of MCP at even higher proton energies. This suggests that in this regime the MCP response is a slowly decreasing function of energy, consistently with the decrease of the deposited energy. These calibration data will enable particle spectra to be obtained in absolute terms over a broad energy range.

  17. Optimization of triangular microchannel heat sinks using constructible theory

    International Nuclear Information System (INIS)

    Mardani, Moloud; Salimpour, Mohammad Reza

    2016-01-01

    The present paper examines the optimization of triangular microchannel heat sinks. The impact of volume fraction of solid material and pressure drop on the maximum temperature of the microchannel heat sinks are investigated and their optimum operating conditions are compared. From the results, it is seen that increasing the side angle of the triangular microchannel, improves its performance. Furthermore, there is an appropriate agreement between the analytical and numerical results. Finally, the effect of degrees of freedom on the performance of microchannels is investigated. To accomplish this end, the triangular microchannels with the side angle of 60 degree have been chosen as it has the best performance compared to other microchannels. It is observed that the minimized maximum temperatures of optimized microchannel heat sinks with three degrees of freedom are 10% lower than the ones with two degrees of freedom

  18. Technology Development of an Advanced Small-scale Microchannel-type Process Heat Exchanger (PHE) for Hydrogen Production in Iodine-sulfur Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Sah, Injin; Kim, Chan Soo; Kim, Yong Wan; Park, Jae-Won; Kim, Eung-Seon; Kim, Min-Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    In this study, ongoing manufacturing processes of the components employed in an advanced small-scale microchannel-type PHE are presented. The components, such as mechanically machined microchannels and a diffusion-bonded stack are introduced. Also, preliminary studies on surface treatment techniques for improving corrosion resistance from the corrosive sulfuric environment will be covered. Ongoing manufacturing process for an advanced small-size microchannel-type PHE in KAERI is presented. Through the preliminary studies for optimizing diffusion bonding condition of Hastelloy-X, a diffusion-bonded stack, consisting of primary and secondary side layer by layer, is scheduled to be fabricated in a few months. Also, surface treatment for enhancing the corrosion resistance from the sulfuric acid environment is in progress for the plates with microchannels. A massive production of hydrogen with electricity generation is expected in a Process Heat Exchanger (PHE) in a Very High Temperature gas-cooled Reactor (VHTR) system. For the application of hydrogen production, a small-scale gas loop for feasibility testing of a laboratory-scale has constructed and operated in Korea Atomic Energy Research Institute (KAERI) as a precursor to an experimental- and a pilot-scale gas loops.

  19. Degradation of the performance of microchannel heat exchangers due to flow maldistribution

    DEFF Research Database (Denmark)

    Nielsen, Kaspar Kirstein; Engelbrecht, Kurt; Christensen, Dennis

    2012-01-01

    The effect of flow maldistribution on the performance of microchannel parallel plate heat exchangers is investigated using an established single blow numerical model and cyclic steady-state regenerator experiments. It is found that as the variation of the individual channel thickness...... in a particular stack (heat exchanger) increases the actual performance of the heat exchanger decreases significantly, deviating from the expected nominal performance. We show that this is due to both the varying fluid flow velocities in each individual channel and the thermal cross talk between the channels...

  20. Hydrodynamic dispersion in a combined magnetohydrodynamic- electroosmotic-driven flow through a microchannel with slowly varying wall zeta potentials

    Science.gov (United States)

    Vargas, C.; Arcos, J.; Bautista, O.; Méndez, F.

    2017-09-01

    The effective dispersion coefficient of a neutral solute in the combined electroosmotic (EO) and magnetohydrodynamic (MHD)-driven flow of a Newtonian fluid through a parallel flat plate microchannel is studied. The walls of the microchannel are assumed to have modulated and low zeta potentials that vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient is solved using the lubrication approximation theory. The solution of the electrical potential is based on the Debye-Hückel approximation for a symmetric (Z :Z ) electrolyte solution. The EO and MHD effects, together with the variations in the zeta potentials of the walls, are observed to notably modify the axial distribution of the effective dispersion coefficient. The problem is formulated for two cases of the zeta potential function. Note that the dispersion coefficient primarily depends on the Hartmann number, on the ratio of the half height of the microchannel to the Debye length, and on the assumed variation in the zeta potentials of the walls.

  1. Fast front-end L0 trigger electronics for ALICE FMD-MCP tests and performance

    CERN Document Server

    Efimov, L G; Kasatkan, V; Klempt, W; Kuts, V; Lenti, V; Platanov, V; Rudge, A; Stolyarov, O I; Tsimbal, F A; Valiev, F F; Villalobos Baillie, O; Vinogradov, L I; Zhigunov, O

    1997-01-01

    We present design details and new measurements of the performance of fast electronics for the Forward Multiplicity Detector for ALICE. These detectors based on sector type Microchannel Plates (MCP) forming several disks gave the very first trigger decision in the experiment (L0). Fast passive summators integrated with the detectors are used for linear summation of up to eight isochronous signal channels from MCP pads belonging to one sector. Two types of microelectronics design thin film summators were produced. We present test results for these summators, working in the frequency range up to 1 Ghz. New low noise preamplifiers have been built to work with these summators. The new design shows a good performance with the usable frequency range extended up to 1 Ghz. An upgrade of the functional scheme for the L0 ALICE pre-trigger design is also presented.Abstract:List of figures Figure 1: ALICE L0 Trigger Front-End Electronics Functional Scheme. Figure 2: UHF design for a fast passive summator based on direct...

  2. Integration of microplasma and microfluidic technologies for localised microchannel surface modification

    Science.gov (United States)

    Szili, Endre J.; Al-Bataineh, Sameer A.; Priest, Craig; Gruner, Philipp J.; Ruschitzka, Paul; Bradley, James W.; Ralston, John; Steele, David A.; Short, Robert D.

    2011-12-01

    In this paper we describe the spatial surface chemical modification of bonded microchannels through the integration of microplasmas into a microfluidic chip (MMC). The composite MMC comprises an array of precisely aligned electrodes surrounding the gas/fluid microchannel. Pairs of electrodes are used to locally ignite microplasmas inside the microchannel. Microplasmas, comprising geometrically confined microscopic electrically-driven gas discharges, are used to spatially functionalise the walls of the microchannels with proteins and enzymes down to scale lengths of 300 μm inside 50 μm-wide microchannels. Microchannels in poly(dimethylsiloxane) (PDMS) or glass were used in this study. Protein specifically adsorbed on to the regions inside the PDMS microchannel that were directly exposed to the microplasma. Glass microchannels required pre-functionalisation to enable the spatial patterning of protein. Firstly, the microchannel wall was functionalised with a protein adhesion layer, 3-aminopropyl-triethoxysilane (APTES), and secondly, a protein blocking agent (bovine serum albumin, BSA) was adsorbed onto APTES. The functionalised microchannel wall was then treated with an array of spatially localised microplasmas that reduced the blocking capability of the BSA in the region that had been exposed to the plasma. This enabled the functionalisation of the microchannel with an array of spatially separated protein. As an alternative we demonstrated the feasibility of depositing functional thin films inside the MMC by spatially plasma depositing acrylic acid and 1,7-octadiene within the microchannel. This new MMC technology enables the surface chemistry of microchannels to be engineered with precision, which is expected to broaden the scope of lab-on-a-chip type applications.

  3. Boiling in microchannels: a review of experiment and theory

    International Nuclear Information System (INIS)

    Thome, John R.

    2004-01-01

    A summary of recent research on boiling in microchannels is presented. The review addresses the topics of macroscale versus microscale heat transfer, two-phase flow regimes, flow boiling heat transfer results for microchannels, heat transfer mechanisms in microchannels and flow boiling models for microchannels. In microchannels, the most dominant flow regime appears to be the elongated bubble mode that can persist up to vapor qualities as high as 60-70% in microchannels, followed by annular flow. Flow boiling heat transfer coefficients have been shown experimentally to be dependent on heat flux and saturation pressure while only slightly dependent on mass velocity and vapor quality. Hence, these studies have concluded that nucleate boiling controls evaporation in microchannels. Instead, a recent analytical study has shown that transient evaporation of the thin liquid films surrounding elongated bubbles is the dominant heat transfer mechanism as opposed to nucleate boiling and is able to predict these trends in the experimental data. Newer experimental studies have further shown that there is in fact a significant effect of mass velocity and vapor quality on heat transfer when covering a broader range of conditions, including a sharp peak at low vapor qualities at high heat fluxes. Furthermore, it is concluded that macroscale models are not realistic for predicting flowing boiling coefficients in microchannels as the controlling mechanism is not nucleate boiling nor turbulent convection but is transient thin film evaporation (also, microchannel flows are typically laminar and not turbulent as assumed by macroscopic models). A more advanced three-zone flow boiling model for evaporation of elongated bubbles in microchannels is currently under development that so far qualitatively describes all these trends. Numerous fundamental aspects of two-phase flow and evaporation remain to be better understood and some of these aspects are also discussed

  4. Experimental evaluation of the response of micro-channel plate detector to ions with 10s of MeV energies

    International Nuclear Information System (INIS)

    Jeong, Tae Won; Ter-Avetisyan, S.; Singh, P. K.; Kakolee, K. F.; Scullion, C.; Ahmed, H.; Hadjisolomou, P.; Alejo, A.; Kar, S.; Borghesi, M.

    2016-01-01

    The absolute calibration of a microchannel plate (MCP) assembly using a Thomson spectrometer for laser-driven ion beams is described. In order to obtain the response of the whole detection system to the particles’ impact, a slotted solid state nuclear track detector (CR-39) was installed in front of the MCP to record the ions simultaneously on both detectors. The response of the MCP (counts/particles) was measured for 5–58 MeV carbon ions and for protons in the energy range 2–17.3 MeV. The response of the MCP detector is non-trivial when the stopping range of particles becomes larger than the thickness of the detector. Protons with energies E ≳ 10 MeV are energetic enough that they can pass through the MCP detector. Quantitative analysis of the pits formed in CR-39 and the signal generated in the MCP allowed to determine the MCP response to particles in this energy range. Moreover, a theoretical model allows to predict the response of MCP at even higher proton energies. This suggests that in this regime the MCP response is a slowly decreasing function of energy, consistently with the decrease of the deposited energy. These calibration data will enable particle spectra to be obtained in absolute terms over a broad energy range.

  5. Experimental evaluation of the response of micro-channel plate detector to ions with 10s of MeV energies

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Tae Won; Ter-Avetisyan, S. [Center for Relativistic Laser Science, Institute of Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Department of Physics and Photon Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005 (Korea, Republic of); Singh, P. K.; Kakolee, K. F. [Center for Relativistic Laser Science, Institute of Basic Science (IBS), Gwangju 61005 (Korea, Republic of); Scullion, C.; Ahmed, H.; Hadjisolomou, P.; Alejo, A.; Kar, S.; Borghesi, M. [School of Mathematics and Physics, The Queen’s University of Belfast, Belfast BT7 1NN (United Kingdom)

    2016-08-15

    The absolute calibration of a microchannel plate (MCP) assembly using a Thomson spectrometer for laser-driven ion beams is described. In order to obtain the response of the whole detection system to the particles’ impact, a slotted solid state nuclear track detector (CR-39) was installed in front of the MCP to record the ions simultaneously on both detectors. The response of the MCP (counts/particles) was measured for 5–58 MeV carbon ions and for protons in the energy range 2–17.3 MeV. The response of the MCP detector is non-trivial when the stopping range of particles becomes larger than the thickness of the detector. Protons with energies E ≳ 10 MeV are energetic enough that they can pass through the MCP detector. Quantitative analysis of the pits formed in CR-39 and the signal generated in the MCP allowed to determine the MCP response to particles in this energy range. Moreover, a theoretical model allows to predict the response of MCP at even higher proton energies. This suggests that in this regime the MCP response is a slowly decreasing function of energy, consistently with the decrease of the deposited energy. These calibration data will enable particle spectra to be obtained in absolute terms over a broad energy range.

  6. Process for separating nitrogen from methane using microchannel process technology

    Science.gov (United States)

    Tonkovich, Anna Lee [Marysville, OH; Qiu, Dongming [Dublin, OH; Dritz, Terence Andrew [Worthington, OH; Neagle, Paul [Westerville, OH; Litt, Robert Dwayne [Westerville, OH; Arora, Ravi [Dublin, OH; Lamont, Michael Jay [Hilliard, OH; Pagnotto, Kristina M [Cincinnati, OH

    2007-07-31

    The disclosed invention relates to a process for separating methane or nitrogen from a fluid mixture comprising methane and nitrogen, the process comprising: (A) flowing the fluid mixture into a microchannel separator, the microchannel separator comprising a plurality of process microchannels containing a sorption medium, the fluid mixture being maintained in the microchannel separator until at least part of the methane or nitrogen is sorbed by the sorption medium, and removing non-sorbed parts of the fluid mixture from the microchannel separator; and (B) desorbing the methane or nitrogen from the sorption medium and removing the desorbed methane or nitrogen from the microchannel separator. The process is suitable for upgrading methane from coal mines, landfills, and other sub-quality sources.

  7. Condensation in Microchannels

    National Research Council Canada - National Science Library

    Ameel, Timothy

    1999-01-01

    .... Evaporators and condensers for meso-scale energy systems will most likely be constructed of microchannels due to the microfabrication constraints that limit most structures to two-dimensional planar geometries...

  8. Heat transfer and fluid flow in minichannels and microchannels

    CERN Document Server

    Kandlikar, Satish; Li, Dongqing; Colin, Stephane; King, Michael R

    2014-01-01

    Heat exchangers with minichannel and microchannel flow passages are becoming increasingly popular due to their ability to remove large heat fluxes under single-phase and two-phase applications. Heat Transfer and Fluid Flow in Minichannels and Microchannels methodically covers gas, liquid, and electrokinetic flows, as well as flow boiling and condensation, in minichannel and microchannel applications. Examining biomedical applications as well, the book is an ideal reference for anyone involved in the design processes of microchannel flow passages in a heat exchanger. Each chapter is accompan

  9. Microchannel boiling mechanisms leading to burnout

    International Nuclear Information System (INIS)

    Landram, C.S.; Riddle, R.A.

    1994-01-01

    The authors are analyzing the thermal performance of microchannel heat sinks to extend their applied heat loads beyond coolant single-phase limits. This is the first investigation of boiling in the narrow (50-μm) microchannels having typically high-aspect-ratio (of order 10/1) flow cross-sections. The prescription of local, wall-coolant, interfacial, two-phase correlations first required development of a validated, approximate, thermal-model accounting for conjugate heat transfer. The strongest mechanism for heat transfer in two-phase microchannel flow was found to be saturated boiling in a channel region near the heated base. When this region dried out, burnout occurred, both in the computations and in the experiment

  10. Experimental study on flame pattern formation and combustion completeness in a radial microchannel

    Science.gov (United States)

    Fan, Aiwu; Minaev, Sergey; Kumar, Sudarshan; Liu, Wei; Maruta, Kaoru

    2007-12-01

    Combustion behavior in a radial microchannel with a gap of 2.0 mm and a diameter of 50 mm was experimentally investigated. In order to simulate the heat recirculation, which is an essential strategy in microscale combustion devices, positive temperature gradients along the radial flow direction were given to the microchannel by an external heat source. A methane-air mixture was supplied from the center of the top plate through a 4.0 mm diameter delivery tube. A variety of flame patterns, including a stable circular flame and several unstable flame patterns termed unstable circular flame, single and double pelton-like flames, traveling flame and triple flame, were observed in the experiments. The regime diagram of all these flame patterns is presented in this paper. Some characteristics of the various flame patterns, such as the radii of stable and unstable circular flames, major combustion products and combustion efficiencies of all these flame patterns, were also investigated. Furthermore, the effect of the heat recirculation on combustion stability was studied by changing the wall temperature levels.

  11. Effect of Induced Magnetic Field on MHD Mixed Convection Flow in Vertical Microchannel

    Science.gov (United States)

    Jha, B. K.; Aina, B.

    2017-08-01

    The present work presents a theoretical investigation of an MHD mixed convection flow in a vertical microchannel formed by two electrically non-conducting infinite vertical parallel plates. The influence of an induced magnetic field arising due to motion of an electrically conducting fluid is taken into consideration. The governing equations of the motion are a set of simultaneous ordinary differential equations and their exact solutions in dimensionless form have been obtained for the velocity field, the induced magnetic field and the temperature field. The expressions for the induced current density and skin friction have also been obtained. The effects of various non-dimensional parameters such as rarefaction, fluid wall interaction, the Hartmann number and the magnetic Prandtl number on the velocity, the induced magnetic field, the temperature, the induced current density, and skin friction have been presented in a graphical form. It is found that the effect of the Hartmann number and magnetic Prandtl number on the induced current density is found to have a decreasing nature at the central region of the microchannel.

  12. Microchannel neural interface manufacture by stacking silicone and metal foil laminae

    Science.gov (United States)

    Lancashire, Henry T.; Vanhoestenberghe, Anne; Pendegrass, Catherine J.; Ajam, Yazan Al; Magee, Elliot; Donaldson, Nick; Blunn, Gordon W.

    2016-06-01

    Objective. Microchannel neural interfaces (MNIs) overcome problems with recording from peripheral nerves by amplifying signals independent of node of Ranvier position. Selective recording and stimulation using an MNI requires good insulation between microchannels and a high electrode density. We propose that stacking microchannel laminae will improve selectivity over single layer MNI designs due to the increase in electrode number and an improvement in microchannel sealing. Approach. This paper describes a manufacturing method for creating MNIs which overcomes limitations on electrode connectivity and microchannel sealing. Laser cut silicone—metal foil laminae were stacked using plasma bonding to create an array of microchannels containing tripolar electrodes. Electrodes were DC etched and electrode impedance and cyclic voltammetry were tested. Main results. MNIs with 100 μm and 200 μm diameter microchannels were manufactured. High electrode density MNIs are achievable with electrodes present in every microchannel. Electrode impedances of 27.2 ± 19.8 kΩ at 1 kHz were achieved. Following two months of implantation in Lewis rat sciatic nerve, micro-fascicles were observed regenerating through the MNI microchannels. Significance. Selective MNIs with the peripheral nervous system may allow upper limb amputees to control prostheses intuitively.

  13. Study of condensation of refrigerants in a micro-channel for development of future compact micro-channel condensers

    Science.gov (United States)

    Chowdhury, Sourav

    2009-12-01

    Mini- and micro-channel technology has gained considerable ground in the recent years in industry and is favored due to its several advantages stemming from its high surface to volume ratio and high values of proof pressure it can withstand. Micro-channel technology has paved the way to development of highly compact heat exchangers with low cost and mass penalties. In the present work, the issues related to the sizing of compact micro-channel condensers have been explored. The considered designs encompass both the conventional and MEMS fabrication techniques. In case of MEMS-fabricated micro-channel condenser, wet etching of the micro-channel structures, followed by bonding of two such wafers with silicon nitride layers at the interface was attempted. It was concluded that the silicon nitride bonding requires great care in terms of high degree of surface flatness and absence of roughness and also high degree of surface purity and thus cannot be recommended for mass fabrication. Following this investigation, a carefully prepared experimental setup and test micro-channel with hydraulic diameter 700 mum and aspect ratio 7:1 was fabricated and overall heat transfer and pressure drop aspects of two condensing refrigerants, R134a and R245fa were studied at a variety of test conditions. To the best of author's knowledge, so far no data has been reported in the literature on condensation in such high aspect ratio micro-channels. Most of the published experimental works on condensation of refrigerants are concerning conventional hydraulic diameter channels (> 3mm) and only recently some experimental data has been reported in the sub-millimeter scale channels for which the surface tension and viscosity effects play a dominant role and the effect of gravity is diminished. It is found that both experimental data and empirically-derived correlations tend to under-predict the present data by an average of 25%. The reason for this deviation could be because a high aspect ratio

  14. A broad-application microchannel-plate detector system for advanced particle or photon detection tasks large area imaging, precise multi-hit timing information and high detection rate

    CERN Document Server

    Jagutzki, O; Mergel, V; Schmidt-Böcking, H; Spielberger, L; Spillmann, U; Ullmann-Pfleger, K

    2002-01-01

    New applications for single particle and photon detection in many fields require both large area imaging performance and precise time information on each detected particle. Moreover, a very high data acquisition rate is desirable for most applications and eventually the detection and imaging of more than one particle arriving within a microsecond is required. Commercial CCD systems lack the timing information whereas other electronic microchannel plate (MCP) read-out schemes usually suffer from a low acquisition rate and complicated and sometimes costly read-out electronics. We have designed and tested a complete imaging system consisting of an MCP position readout with helical wire delay-lines, single-unit amplifier box and PC-controlled time-to-digital converter (TDC) readout. The system is very flexible and can detect and analyse position and timing information at single particle rates beyond 1 MHz. Alternatively, multi-hit events can be collected and analysed at about 20 kHz rate. We discuss the advantage...

  15. Robust and fast license plate detection based on the fusion of color and edge feature

    Science.gov (United States)

    Cai, De; Shi, Zhonghan; Liu, Jin; Hu, Chuanping; Mei, Lin; Qi, Li

    2014-11-01

    Extracting a license plate is an important stage in automatic vehicle identification. The degradation of images and the computation intense make this task difficult. In this paper, a robust and fast license plate detection based on the fusion of color and edge feature is proposed. Based on the dichromatic reflection model, two new color ratios computed from the RGB color model are introduced and proved to be two color invariants. The global color feature extracted by the new color invariants improves the method's robustness. The local Sobel edge feature guarantees the method's accuracy. In the experiment, the detection performance is good. The detection results show that this paper's method is robust to the illumination, object geometry and the disturbance around the license plates. The method can also detect license plates when the color of the car body is the same as the color of the plates. The processing time for image size of 1000x1000 by pixels is nearly 0.2s. Based on the comparison, the performance of the new ratios is comparable to the common used HSI color model.

  16. Membrane-based microchannel device for continuous quantitative extraction of dissolved free sulfide from water and from oil.

    Science.gov (United States)

    Toda, Kei; Ebisu, Yuki; Hirota, Kazutoshi; Ohira, Shin-Ichi

    2012-09-05

    Underground fluids are important natural sources of drinking water, geothermal energy, and oil-based fuels. To facilitate the surveying of such underground fluids, a novel microchannel extraction device was investigated for in-line continuous analysis and flow injection analysis of sulfide levels in water and in oil. Of the four designs investigated, the honeycomb-patterned microchannel extraction (HMCE) device was found to offer the most effective liquid-liquid extraction. In the HMCE device, a thin silicone membrane was sandwiched between two polydimethylsiloxane plates in which honeycomb-patterned microchannels had been fabricated. The identical patterns on the two plates were accurately aligned. The extracted sulfide was detected by quenching monitoring of fluorescein mercuric acetate (FMA). The sulfide extraction efficiencies from water and oil samples of the HMCE device and of three other designs (two annular and one rectangular channel) were examined theoretically and experimentally. The best performance was obtained with the HMCE device because of its thin sample layer (small diffusion distance) and large interface area. Quantitative extraction from both water and oil could be obtained using the HMCE device. The estimated limit of detection for continuous monitoring was 0.05 μM, and sulfide concentrations in the range of 0.15-10 μM could be determined when the acceptor was 5 μM FMA alkaline solution. The method was applied to natural water analysis using flow injection mode, and the data agreed with those obtained using headspace gas chromatography-flame photometric detection. The analysis of hydrogen sulfide levels in prepared oil samples was also performed. The proposed device is expected to be used for real time survey of oil wells and groundwater wells. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Study of different cross-shaped microchannels affecting thermal-bubble-actuated microparticle manipulation

    Science.gov (United States)

    Li, Weichen; Tsou, Chingfu

    2015-10-01

    This paper presents a thermal-bubble-actuated microfluidic chip with cross-shaped microchannels for evaluating the effect of different microchannel designs on microparticle manipulation. Four cross-shaped microchannel designs, with orthogonal, misaligned, skewed, and antiskewed types, were proposed in this study. The thermal bubble micropump, which is based on a resistive bulk microheater, was used to drive fluid transportation, and it can be realized using a simple microfabrication process with a silicon-on-isolator wafer. Using commercial COMSOL software, the flow profiles of microfluidics in various cross-shaped microchannels were simulated qualitatively under different pumping pressures. Microbeads, with a diameter of 20 μm, manipulated in four cross-shaped microchannels, were also implemented in this experiment. The results showed that a skewed microchannel design has a higher sorting rate compared with orthogonal, misaligned, and antiskewed microchannels because its flow velocity in the main microchannel is significantly reduced by pumping pressure. Typically, the successful sorting rate for this type of skewed microchannel can reach 30% at a pumping frequency of 100 Hz.

  18. Formation of microchannels from low-temperature plasma-deposited silicon oxynitride

    Science.gov (United States)

    Matzke, Carolyn M.; Ashby, Carol I. H.; Bridges, Monica M.; Manginell, Ronald P.

    2000-01-01

    A process for forming one or more fluid microchannels on a substrate is disclosed that is compatible with the formation of integrated circuitry on the substrate. The microchannels can be formed below an upper surface of the substrate, above the upper surface, or both. The microchannels are formed by depositing a covering layer of silicon oxynitride over a mold formed of a sacrificial material such as photoresist which can later be removed. The silicon oxynitride is deposited at a low temperature (.ltoreq.100.degree. C.) and preferably near room temperature using a high-density plasma (e.g. an electron-cyclotron resonance plasma or an inductively-coupled plasma). In some embodiments of the present invention, the microchannels can be completely lined with silicon oxynitride to present a uniform material composition to a fluid therein. The present invention has applications for forming microchannels for use in chromatography and electrophoresis. Additionally, the microchannels can be used for electrokinetic pumping, or for localized or global substrate cooling.

  19. Effect of microchannel structure on the reaction performance of methanol steam reforming

    International Nuclear Information System (INIS)

    Pan, Minqiang; Wu, Qiuyu; Jiang, Lianbo; Zeng, Dehuai

    2015-01-01

    Highlights: • Effect of microchannel cross-section and distribution on MSR are investigated. • Microchannel distribution shows much more influence on reaction performance. • SLDR and ELR with rectangular cross-section present better reaction performance. • DLSR and EUU with tooth cross-section have better reaction performance. • Equal-distribution of microchannels present the best reaction performance. - Abstract: Methanol steam reforming inside microchannel reactors is regarded as one of effective methods for supplying hydrogen for fuel cells. Microchannel structure plays an important role on the reaction performance of methanol steam reforming. Parallel and uniform-distributed microchannels with rectangular cross-section are generally adopted. In this work, two kinds of microchannel cross-sections and four kinds of microchannel distributions are selected to investigate the effect of microchannel structure on the reaction performance of methanol steam reforming. The result indicates that microchannel distribution shows much more influences on the reaction performance of methanol steam reforming than the microchannel cross-section. Sparse-distribution in the Left direction and Dense-distribution in the Right direction (SLDR) as well as Equal-distribution in the Left–Right direction (ELR) with rectangular cross-section present relatively good reaction performances, whereas Dense-distribution in the Left direction and Sparse-distribution in the Right direction (DLSR) as well as Equal-distribution in the Upside–Underside direction (EUU) with tooth cross-section have relatively good performances. ELR presents the best reaction performances of methanol steam reforming among all the investigated microchannel structures, whether rectangular or tooth cross-section

  20. Interferometric measurement and numerical comparisons of supersonic heat transfer flows in microchannel

    International Nuclear Information System (INIS)

    Takahashi, Yuya; Chen, Lin; Okajima, Junnosuke; Iga, Yuka; Komiya, Atsuki; Maruyama, Shigenao

    2016-01-01

    Highlights: • Effective cooling design by super-/sub-sonic air flow in microchannels is proposed. • Microscale supersonic flows is successfully generated and examined. • Microchannel flow density field were visualized quantitatively by interferometer. • The bump design shows great potential of heat transfer enhancement in microscale. - Abstract: With the fast development of electronic systems and the ever-increasing demand of thermally “smart” design in space and aeronautic engineering, the heat transfer innovations and high heat flux challenges have become a hot topic for decades. This study is aimed at the effective cooling heat transfer design by super-/sub-sonic air flow in microscale channels for high heat flux devices. The design is based on the low temperature flows with supersonic expansion in microscale, which yields a compact and simple design. By careful microelectromechanical process, microscale straight and bumped channels (with simple arc curve) are fabricated and experimentally tested in this study. The microscale flow field and density distributions under new designs are visualized quantitatively by an advanced phase-shifting interferometer system, which results are then compared carefully with numerical simulations. In this study, large differences between the two designs in density distribution and temperature changes (around 50 K) are found. The high heat flux potential for supersonic microchannel flows is realized and discussion into detail. It is confirmed that the bump design contributes significantly to the heat transfer enhancement, which shows potential for future application in novel system designs.

  1. Numerical Investigation of Effect of Surface Roughness in a Microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Myung Seob; Byun, Sung Jun; Yoon, Joon Yong [Hanyang University, Seoul (Korea, Republic of)

    2010-05-15

    In this paper, lattice Boltzmann method(LBM) results for a laminar flow in a microchannel with rough surface are presented. The surface roughness is modeled as an array of rectangular modules placed on the top and bottom surface of a parallel-plate channel. The effects of relative surface roughness, roughness distribution, and roughness size are presented in terms of the Poiseuille number. The roughness distribution characterized by the ratio of the roughness height to the spacing between the modules has a negligible effect on the flow and friction factors. Finally, a significant increase in the Poiseuille number is observed when the surface roughness is considered, and the effects of roughness on the microflow field mainly depend on the surface roughness.

  2. Experimental study on fast neutron streaming through grid-plate shield of a LMFBR

    International Nuclear Information System (INIS)

    Oka, Yoshiaki; Wakabayashi, Hiroaki; An, Shigehiro; Suzuki, Ikunori.

    1976-01-01

    Neutron streaming through the holes penetrating the grid plate shield of a prototype LMFBR was experimentally examined. The mockups of the grid plate shield were made of iron and aluminum. Experiments were conducted at the vertical column of ''YAYOI'', the fast neutron source reactor of University of Tokyo. A He-3 spectrometer was employed in order to measure the transmitted neutron spectrum, while rhodium and indium threshold foils were for the integral flux above specific energies and their spatial distributions in the form of reaction rates. The streaming factor for usual small bended holes is 1.28+-0.04 as to the integral neutron flux above 0.1 MeV and 1.30+-0.12 as to the reaction rate of indium foil. Use were made of the one and two dimensional neutron transport code ANISN and TWOTRAN for evaluation by computation. The reaction rates calculated by infinite slab model with ANISN code agree well with the experiments when normalized at the source point where neutrons are incident on the grid plate shield. (auth.)

  3. High Frequency Design Considerations for the Large Detector Number and Small Form Factor Dual Electron Spectrometer of the Fast Plasma Investigation on NASA's Magnetospheric Multiscale Mission

    Science.gov (United States)

    Kujawski, Joseph T.; Gliese, Ulrik B.; Cao, N. T.; Zeuch, M. A.; White, D.; Chornay, D. J; Lobell, J. V.; Avanov, L. A.; Barrie, A. C.; Mariano, A. J.; hide

    2015-01-01

    Each half of the Dual Electron Spectrometer (DES) of the Fast Plasma Investigation (FPI) on NASA's Magnetospheric MultiScale (MMS) mission utilizes a microchannel plate Chevron stack feeding 16 separate detection channels each with a dedicated anode and amplifier/discriminator chip. The desire to detect events on a single channel with a temporal spacing of 100 ns and a fixed dead-time drove our decision to use an amplifier/discriminator with a very fast (GHz class) front end. Since the inherent frequency response of each pulse in the output of the DES microchannel plate system also has frequency components above a GHz, this produced a number of design constraints not normally expected in electronic systems operating at peak speeds of 10 MHz. Additional constraints are imposed by the geometry of the instrument requiring all 16 channels along with each anode and amplifier/discriminator to be packaged in a relatively small space. We developed an electrical model for board level interactions between the detector channels to allow us to design a board topology which gave us the best detection sensitivity and lowest channel to channel crosstalk. The amplifier/discriminator output was designed to prevent the outputs from one channel from producing triggers on the inputs of other channels. A number of Radio Frequency design techniques were then applied to prevent signals from other subsystems (e.g. the high voltage power supply, command and data handling board, and Ultraviolet stimulation for the MCP) from generating false events. These techniques enabled us to operate the board at its highest sensitivity when operated in isolation and at very high sensitivity when placed into the overall system.

  4. Material Selection for Microchannel Heatsink: Conjugate Heat Transfer Simulation

    Science.gov (United States)

    Uday Kumar, A.; Javed, Arshad; Dubey, Satish K.

    2018-04-01

    Heat dissipation during the operation of electronic devices causes rise in temperature, which demands an effective thermal management for their performance, life and reliability. Single phase liquid cooling in microchannels is an effective and proven technology for electronics cooling. However, due to the ongoing trends of miniaturization and developments in the microelectronics technology, the future needs of heat flux dissipation rate are expected to rise to 1 kW/cm2. Air cooled systems are unable to meet this demand. Hence, liquid cooled heatsinks are preferred. This paper presents conjugate heat transfer simulation of single phase flow in microchannels with application to electronic cooling. The numerical model is simulated for different materials: copper, aluminium and silicon as solid and water as liquid coolant. The performances of microchannel heatsink are analysed for mass flow rate range of 20-40 ml/min. The investigation has been carried out on same size of electronic chip and heat flux in order to have comparative study of different materials. This paper is divided into two sections: fabrication techniques and numerical simulation for different materials. In the first part, a brief discussion of fabrication techniques of microchannel heatsink have been presented. The second section presents conjugate heat transfer simulation and parametric investigation for different material microchannel heatsink. The presented study and findings are useful for selection of materials for microchannel heatsink.

  5. Some new possibilities in direct visible and x ray measurements

    International Nuclear Information System (INIS)

    Gex, J.P.; Sauneuf, R.; Boutot, J.P.; Delmotte, J.C.

    1979-01-01

    Subnanosecond photodetection measurements in visible and X ray range with vacuum cell and very thin microchannel plate phototube (coupled with a fast scintillator or not) in conjunction with fast oscilloscope (5 GHz) are presented. They are compared to those given by a visible or a gold photocathode X-ray streak camera (temporal resolution better than 20 ps). (author)

  6. CW-laser induced microchannels in dye-polymethacrylic acid films

    OpenAIRE

    M.A. Camacho-López

    2007-01-01

    In this work we report on the formation of microchannels on dye-polymethacrylic acid films using a cw-laser. A focalized beam of a He-Ne laser (632.8 nm emission line) was used to form microchannels on the films. It was found that there exists a laser power density threshold for a pit formation that depends on the dye concentration. The dimensions of the laser-induced channels are dependent on the laser power density. Microchannel formation in the transparent polymethacrylic acid films was no...

  7. Experimental investigation of heat transfer performance for a novel microchannel heat sink

    International Nuclear Information System (INIS)

    Wang, Y; Ding, G-F

    2008-01-01

    We demonstrated a novel microchannel heat sink with a high local heat transfer efficiency contributed by a complicated microchannel system, which comprises parallel longitudinal microchannels etched in a silicon substrate and transverse microchannels electroplated on a copper heat spreader. The thermal boundary layer develops in transverse microchannels. Meanwhile, the heat transfer area is increased compared with the conventional microchannel heat sink only having parallel longitudinal microchannels. Both benefits yield high local heat transfer efficiency and enhance the overall heat transfer, which is attractive for the cooling of high heat flux electronic devices. Infrared tests show the temperature distribution in the test objects. The effects of flow rate and heat flux levels on heat transfer characteristics are presented. A uniform temperature distribution is obtained through the heating area. The reference temperatures decrease with the increasing flow rate from 0.64 ml min −1 to 6.79 ml min −1 for a constant heat flux of 10.4 W cm −2 . A heat flux of 18.9 W cm −2 is attained at a flow rate of 6.79 ml min −1 for assuring the maximum temperature of the microchannel heat sink less than the maximum working temperature of electronic devices

  8. Study on Boiling Heat Transfer Phenomenon in Micro-channels

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Namgyun [Inha Technical College, Incheon (Korea, Republic of)

    2017-09-15

    Recently, efficient heat dissipation has become necessary because of the miniaturization of devices, and research on boiling on micro-channels has attracted attention. However, in the case of micro-channels, the friction coefficient and heat transfer characteristics are different from those in macro-channels. This leads to large errors in the micro scale results, when compared to correlations derived from the macro scale. In addition, due to the complexity of the mechanism, the boiling phenomenon in micro-channels cannot be approached only by experimental and theoretical methods. Therefore, numerical methods should be utilized as well, to supplement these methods. However, most numerical studies have been conducted on macro-channels. In this study, we applied the lattice Boltzmann method, proposed as an alternative numerical tool to simulate the boiling phenomenon in the micro-channel, and predicted the bubble growth process in the channel.

  9. A review on the analysis and experiment of fluid flow and mixing in micro-channels

    International Nuclear Information System (INIS)

    Kang, Sang Mo; Suh, Yong Kweon; Jayaraj, Simon

    2007-01-01

    The studies with respect to micro-channels and micro-mixers are expanding in many dimensions. Most significant area of micro-mixer study is the flow analysis in various micro-channel configurations. The flow phenomena in microchannel devices are quite different from that of the macro-scale devices. An attempt is made here to review the important recent literature available in the area of micro-channel flow analysis and mixing. The topics covered include the physics of flow in micro-channels and integrated simulation of the micro-channel flow. Also, the flow control models and electro-kinetically driven micro-channel flows are dealt in detail. A survey of important numerical methods, which are currently popular for micro-channel flow analysis, is carried out. Different options for mixing in microchannels are provided, in sufficient detail

  10. A Design of a PET Detector Using Micro-Channel Plate Photomultipliers with Transmission-Line Readout.

    Science.gov (United States)

    Kim, H; Frisch, H; Chen, C-T; Genat, J-F; Tang, F; Moses, W W; Choong, W S; Kao, C-M

    2010-01-01

    A computer simulation study has been conducted to investigate the feasibility of a positron emission tomography (PET) detector design by using micro-channel plate (MCP) photomultiplier tubes (PMT) with transmission-line (TL) read-out and waveform sampling. The detector unit consisted of a 24×24 array of pixelated LSO crystals, each of which was 4×4×25 mm(3) in size, and two 102×102 mm(2) MCP-PMTs coupled to both sides of the scintillator array. The crystal (and TL) pitch was 4.25 mm and reflective medium was inserted between the crystals. The transport of the optical photons inside the scintillator were simulated by using the Geant4 package. The output pulses of the MCP-PMT/TL unit were formed by applying the measured single photo-electron response of the MCP-PMT/TL unit to each individual photon that interacts with the photo-cathode of the MCP-PMT. The waveforms of the pulses at both ends of the TL strips were measured and analyzed to produce energy and timing information for the detected event. An experimental setup was developed by employing a Photonis Planacon MCP-PMT (XP85022) and a prototype TL board for measuring the single photo-electron response of the MCP-PMT/TL. The simulation was validated by comparing the predicted output pulses to measurements obtained with a single MCP-PMT/TL coupled to an LSO crystal exposed to 511 keV gamma rays. The validated simulation was then used to investigate the performance of the proposed new detector design. Our simulation result indicates an energy resolution of ~11% at 511 keV. When using a 400-600 keV energy window, we obtain a coincidence timing resolution of ~323 ps FWHM and a coincidence detection efficiency of ~40% for normally-incident 511keV photons. For the positioning accuracy, it is determined by the pitch of the TLs (and crystals) in the direction normal to the TLs and measured to be ~2.5 mm in the direction parallel to the TLs. The energy and timing obtained at the front- and back-end of the scintillator

  11. Enabling Microliquid Chromatography by Microbead Packing of Microchannels

    Science.gov (United States)

    Balvin, Manuel; Zheng, Yun

    2014-01-01

    The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid

  12. Transient response of nonideal ion-selective microchannel-nanochannel devices

    Science.gov (United States)

    Leibowitz, Neta; Schiffbauer, Jarrod; Park, Sinwook; Yossifon, Gilad

    2018-04-01

    We report evidence of variation in ion selectivity of a fabricated microchannel-nanochannel device resulting in the appearance of a distinct local maximum in the overlimiting chronopotentiometric response. In this system consisting of shallow microchannels joined by a nanochannel, viscous shear at the microchannel walls suppresses the electro-osmotic instability and prevents any associated contribution to the nonmonotonic response. Thus, this response is primarily electrodiffusive. Numerical simulations indicate that concentration polarization develops not only within the microchannel but also within the nanochannel itself, with a local voltage maximum in the chronopotentiometric response correlated with interfacial depletion and having the classic i-2 Sands time dependence. Furthermore, the occurrence of the local maxima is correlated with the change in selectivity due to internal concentration polarization. Understanding the transient nonideal permselective response is essential for obtaining fundamental insight and for optimizing efficient operation of practical fabricated nanofluidic and membrane devices.

  13. Periodic flow patterns of the magnetic fluid in microchannel

    International Nuclear Information System (INIS)

    Chang, C.-W.; Cheng, Y.-T.; Tsai, C.-Y.; Chien, J.-H.; Wang, P.-Y.; Chen, P.-H.

    2007-01-01

    In this study, of interests are the periodic flow patterns of the oil-based magnetic fluid in microchannels. A microfluidic chip is made of poly-dimethylsiloxane (PDMS) and contains cross-shape microchannels. The microchannels are 1000 μm in width and 200 μm in depth. A syringe pump was used to drive the fluids. Periodic flow patterns were seen and the slugs of magnetic fluid and DI water were generated. The operating factors discussed in the present work are the flow rates and the magnetic field. The frequency of generation of the slugs increases with increase in the flow rates. Besides, by settling the permanent magnet around the microchannel, the periods of the slug generation are changed. Different positions of the magnet lead to different periods for generating the slugs. By adjusting operating conditions, to control the frequency and the volume of the slugs is practical

  14. Surface roughness influences on the behaviour of flow inside microchannels

    Science.gov (United States)

    Farias, M. H.; Castro, C. S.; Garcia, D. A.; Henrique, J. S.

    2018-03-01

    This work discusses influence of the surface roughness on the behavior of liquids flowing inside microchannels. By measuring the flow profile using the micro-PIV technique, the flow of water inside two rectangular microchannels of different wall roughness and in a circular smooth microchannel was studied. Comparisons were made among the experimental results, showing that a metrological approach concerning surface characteristics of microdevices is required to ensure reliability of the measurements for flow analyses in microfluidic processes.

  15. Numerical Simulation and Analysis of Gas-Liquid Flow in a T-Junction Microchannel

    Directory of Open Access Journals (Sweden)

    Hongtruong Pham

    2012-01-01

    Full Text Available Gas-liquid flow in microchannels is widely used in biomedicine, nanotech, sewage treatment, and so forth. Particularly, owing to the high qualities of the microbubbles and spheres produced in microchannels, it has a great potential to be used in ultrasound imaging and controlled drug release areas; therefore, gas-liquid flow in microchannels has been the focus in recent years. In this paper, numerical simulation of gas-liquid flows in a T-junction microchannel was carried out with computational fluid dynamics (CFD software FLUENT and the Volume-of-Fluid (VOF model. The distribution of velocity, pressure, and phase of fluid in the microchannel was obtained, the pressure distribution along the channel walls was analyzed in order to give a better understanding on the formation of microbubbles in the T-junction microchannel.

  16. Critical heat flux in flow boiling in microchannels

    CERN Document Server

    Saha, Sujoy Kumar

    2015-01-01

    This Brief concerns the important problem of critical heat flux in flow boiling in microchannels. A companion edition in the SpringerBrief Subseries on Thermal Engineering and Applied Science to “Heat Transfer and Pressure Drop in Flow Boiling in Microchannels,” by the same author team, this volume is idea for professionals, researchers, and graduate students concerned with electronic cooling.

  17. Axisymmetric polydimethysiloxane microchannels for in vitro hemodynamic studies

    International Nuclear Information System (INIS)

    Lima, Rui; Oliveira, Monica S N; Ishikawa, Takuji; Kaji, Hirokazu; Nishizawa, Matsuhiko; Tanaka, Shuji; Yamaguchi, Takami

    2009-01-01

    The current microdevices used for biomedical research are often manufactured using microelectromechanical systems (MEMS) technology. Although it is possible to fabricate precise and reproducible rectangular microchannels using soft lithography techniques, this kind of geometry may not reflect the actual physiology of the microcirculation. Here, we present a simple method to fabricate circular polydimethysiloxane (PDMS) microchannels aiming to mimic an in vivo microvascular environment and suitable for state-of-the-art microscale flow visualization techniques, such as confocal μPIV/PTV. By using a confocal μPTV system individual red blood cells (RBCs) were successfully tracked trough a 75 μm circular PDMS microchannel. The results show that RBC lateral dispersion increases with the volume fraction of RBCs in the solution, i.e. with the hematocrit.

  18. Systems and methods of manufacturing microchannel arrays

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Brian K.; Brannon, Samuel T.

    2018-03-20

    The present application relates to apparatus and methods of reducing the cost of microchannel array production and operation. In a representative embodiment, a microchannel array can comprise a first lamina having one or more flanges and a plurality of elongated bosses. The one or more flanges can extend along a perimeter of the first lamina, the plurality of elongated bosses can at least partially define a plurality of first flow paths, and the first lamina can define at least one opening. The microchannel array can also comprise a second lamina having a plurality of second flow paths, and can define at least one opening. The second lamina can be disposed above the first lamina such that the second lamina encloses the first flow paths of the first lamina and the at least one opening of the first lamina is coaxial with the at least one opening of the second lamina.

  19. NASA's Platform for Cross-Disciplinary Microchannel Research

    Science.gov (United States)

    Son, Sang Young; Spearing, Scott; Allen, Jeffrey; Monaco, Lisa A.

    2003-01-01

    A team from the Structural Biology group located at the NASA Marshall Space Flight Center in Huntsville, Alabama is developing a platform suitable for cross-disciplinary microchannel research. The original objective of this engineering development effort was to deliver a multi-user flight-certified facility for iterative investigations of protein crystal growth; that is, Iterative Biological Crystallization (IBC). However, the unique capabilities of this facility are not limited to the low-gravity structural biology research community. Microchannel-based research in a number of other areas may be greatly accelerated through use of this facility. In particular, the potential for gas-liquid flow investigations and cellular biological research utilizing the exceptional pressure control and simplified coupling to macroscale diagnostics inherent in the IBC facility will be discussed. In conclusion, the opportunities for research-specific modifications to the microchannel configuration, control, and diagnostics will be discussed.

  20. Non-Newtonian fluid structure interaction in flexible biomimetic microchannels

    Science.gov (United States)

    Kiran, M.; Dasgupta, Sunando; Chakraborty, Suman

    2017-11-01

    To investigate the complex fluid structure interactions in a physiologically relevant microchannel with deformable wall and non-Newtonian fluid that flows within it, we fabricated cylindrical microchannels of various softness out of PDMS. Experiments to measure the transient pressure drop across the channel were carried out with high sampling frequencies to capture the intricate flow physics. In particular, we showed that the waveforms varies greatly for each of the non-Newtonian and Newtonian cases for both non-deformable and deformable microchannels in terms of the peak amplitude, r.m.s amplitude and the crest factor. In addition, we carried out frequency sweep experiments to evaluate the frequency response of the system. We believe that these results will aid in the design of polymer based microfluidic phantoms for arterial FSI studies, and in particular for studying blood analog fluids in cylindrical microchannels as well as developing frequency specific Lab-on-chip systems for medical diagnostics.

  1. Microchannel electron multiplier

    International Nuclear Information System (INIS)

    Beranek, I.; Janousek, L.; Vitovsky, O.

    1981-01-01

    A microchannel electron multiplier is described for detecting low levels of alpha, beta, soft X-ray and UV radiations. It consists of a glass tube or a system of tubes of various shapes made of common technological glass. The inner tube surface is provided with an active coat with photoemitter and secondary emitter properties. (B.S.)

  2. Convective heat transfer for a gaseous slip flow in micropipe and parallel-plate microchannel with uniform wall heat flux: effect of axial heat conduction

    Science.gov (United States)

    Haddout, Y.; Essaghir, E.; Oubarra, A.; Lahjomri, J.

    2018-06-01

    Thermally developing laminar slip flow through a micropipe and a parallel plate microchannel, with axial heat conduction and uniform wall heat flux, is studied analytically by using a powerful method of self-adjoint formalism. This method results from a decomposition of the elliptic energy equation into a system of two first-order partial differential equations. The advantage of this method over other methods, resides in the fact that the decomposition procedure leads to a selfadjoint problem although the initial problem is apparently not a self-adjoint one. The solution is an extension of prior studies and considers a first order slip model boundary conditions at the fluid-wall interface. The analytical expressions for the developing temperature and local Nusselt number in the thermal entrance region are obtained in the general case. Therefore, the solution obtained could be extended easily to any hydrodynamically developed flow and arbitrary heat flux distribution. The analytical results obtained are compared for select simplified cases with available numerical calculations and they both agree. The results show that the heat transfer characteristics of flow in the thermal entrance region are strongly influenced by the axial heat conduction and rarefaction effects which are respectively characterized by Péclet and Knudsen numbers.

  3. Integrated microchannel cooling in a three dimensional integrated circuit: A thermal management

    Directory of Open Access Journals (Sweden)

    Wang Kang-Jia

    2016-01-01

    Full Text Available Microchannel cooling is a promising technology for solving the three-dimensional integrated circuit thermal problems. However, the relationship between the microchannel cooling parameters and thermal behavior of the three dimensional integrated circuit is complex and difficult to understand. In this paper, we perform a detailed evaluation of the influence of the microchannel structure and the parameters of the cooling liquid on steady-state temperature profiles. The results presented in this paper are expected to aid in the development of thermal design guidelines for three dimensional integrated circuit with microchannel cooling.

  4. Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gruber, G.J.

    1996-05-01

    A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. At a sweeping rate of 10{sup 13} V/s, the electron pulses and resulting x-ray pulses are reduced to about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite new, fast, bright scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators (e.g., BaF{sub 2}). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths.

  5. Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

    International Nuclear Information System (INIS)

    Gruber, G.J.

    1996-05-01

    A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. At a sweeping rate of 10 13 V/s, the electron pulses and resulting x-ray pulses are reduced to about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite new, fast, bright scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators (e.g., BaF 2 ). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths

  6. Thermal performance of nanofluid flow in microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Li Jie [Department of Mechanical and Aerospace Engineering, University of North Carolina, Campus Box 7910, Broungton Hall 4160, Raleigh, NC 27695-7910 (United States); Kleinstreuer, Clement [Department of Mechanical and Aerospace Engineering, University of North Carolina, Campus Box 7910, Broungton Hall 4160, Raleigh, NC 27695-7910 (United States)], E-mail: ck@eos.ncsu.edu

    2008-08-15

    Two effective thermal conductivity models for nanofluids were compared in detail, where the new KKL (Koo-Kleinstreuer-Li) model, based on Brownian motion induced micro-mixing, achieved good agreements with the currently available experimental data sets. Employing the commercial Navier-Stokes solver CFX-10 (Ansys Inc., Canonsburg, PA) and user-supplied pre- and post-processing software, the thermal performance of nanofluid flow in a trapezoidal microchannel was analyzed using pure water as well as a nanofluid, i.e., CuO-water, with volume fractions of 1% and 4% CuO-particles with d{sub p} = 28.6 nm. The results show that nanofluids do measurably enhance the thermal performance of microchannel mixture flow with a small increase in pumping power. Specifically, the thermal performance increases with volume fraction; but, the extra pressure drop, or pumping power, will somewhat decrease the beneficial effects. Microchannel heat sinks with nanofluids are expected to be good candidates for the next generation of cooling devices.

  7. Dynamic Modelling of the DEP Controlled Boiling in a Microchannel

    Science.gov (United States)

    Lackowski, Marcin; Kwidzinski, Roman

    2018-04-01

    The paper presents theoretical analysis of flow dynamics in a heated microchannel in which flow rate may be controlled by dielectrophoretic (DEP) forces. Proposed model equations were derived in terms of lumped parameters characterising the system comprising of DEP controller and the microchannel. In result, an equation for liquid height of rise in the controller was obtained from momentum balances in the two elements of the considered system. In the model, the boiling process in the heated section of microchannel is taken into account through a pressure drop, which is a function of flow rate and uniform heat flux. Presented calculation results show that the DEP forces influence mainly the flow rate in the microchannel. In this way, by proper modulation of voltage applied to the DEP controller, it is possible to lower the frequency of Ledinegg instabilities.

  8. Slip flow through a converging microchannel: experiments and 3D simulations

    International Nuclear Information System (INIS)

    Varade, Vijay; Agrawal, Amit; Pradeep, A M

    2015-01-01

    An experimental and 3D numerical study of gaseous slip flow through a converging microchannel is presented in this paper. The measurements reported are with nitrogen gas flowing through the microchannel with convergence angles (4°, 8° and 12°), hydraulic diameters (118, 147 and 177 µm) and lengths (10, 20 and 30 mm). The measurements cover the entire slip flow regime and a part of the continuum and transition regimes (the Knudsen number is between 0.0004 and 0.14); the flow is laminar (the Reynolds number is between 0.5 and 1015). The static pressure drop is measured for various mass flow rates. The overall pressure drop increases with a decrease in the convergence angle and has a relatively large contribution of the viscous component. The numerical solutions of the Navier–Stokes equations with Maxwell’s slip boundary condition explore two different flow behaviors: uniform centerline velocity with linear pressure variation in the initial and the middle part of the microchannel and flow acceleration with nonlinear pressure variation in the last part of the microchannel. The centerline velocity and the wall shear stress increase with a decrease in the convergence angle. The concept of a characteristic length scale for a converging microchannel is also explored. The location of the characteristic length is a function of the Knudsen number and approaches the microchannel outlet with rarefaction. These results on gaseous slip flow through converging microchannels are observed to be considerably different than continuum flow. (paper)

  9. Acoustophoretic Synchronization of Mammalian Cells in Microchannels

    DEFF Research Database (Denmark)

    Thévoz, P.; Adams, J.D.; Shea, H.

    2010-01-01

    We report the first use of ultrasonic standing waves to achieve cell cycle phase synchronization in mammalian cells in a high-throughput and reagent-free manner. The acoustophoretic cell synchronization (ACS) device utilizes volume-dependent acoustic radiation force within a microchannel to selec......We report the first use of ultrasonic standing waves to achieve cell cycle phase synchronization in mammalian cells in a high-throughput and reagent-free manner. The acoustophoretic cell synchronization (ACS) device utilizes volume-dependent acoustic radiation force within a microchannel...

  10. Influence of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink

    International Nuclear Information System (INIS)

    Om, N I; Gunnasegaran, P; Rajasegaran, S

    2013-01-01

    In this paper, the effect of sinusoidal flow on the thermal and hydraulic performance of microchannel heat sink (MCHS) is numerically investigated. This investigation covers Reynolds number in the range of 100 ≤ Re ≤ 1000 and pure water is used as a working fluid. The three-dimensional steady, laminar flow and heat transfer governing equations are solved using finite volume method (FVM). The water flow field and heat transfer performance inside the sinusoidal microchannels is simulated and the results are compared with the straight microchannels. The effect of using sinusoidal microchannels on temperature distribution, Nusselt number, friction factor and thermal resistance is presented in this paper. It is found that with same rectangular cross-section, sinusoidal microchannels have a better heat transfer performance compared to the straight microchannels.

  11. Characterization of microchannel anechoic corners formed by surface acoustic waves

    Science.gov (United States)

    Destgeer, Ghulam; Alam, Ashar; Ahmed, Husnain; Park, Jinsoo; Jung, Jin Ho; Park, Kwangseok; Sung, Hyung Jin

    2018-02-01

    Surface acoustic waves (SAWs) generated in a piezoelectric substrate couple with a liquid according to Snell's law such that a compressional acoustic wave propagates obliquely at a Rayleigh angle ( θ t) inside the microchannel to form a region devoid of a direct acoustic field, which is termed a microchannel anechoic corner (MAC). In the present study, we used microchannels with various heights and widths to characterize the width of the MAC region formed by a single travelling SAW. The attenuation of high-frequency SAWs produced a strong acoustic streaming flow that moved the particles in and out of the MAC region, whereas reflections of the acoustic waves within the microchannel resulted in standing acoustic waves that trapped particles at acoustic pressure nodes located within or outside of the MAC region. A range of actuation frequencies and particle diameters were used to investigate the effects of the acoustic streaming flow and the direct acoustic radiation forces by the travelling as well as standing waves on the particle motion with respect to the MAC region. The width of the MAC ( w c), measured experimentally by tracing the particles, increased with the height of the microchannel ( h m) according to a simple trigonometric equation w c = h m × tan ( θ t ).

  12. Electrokinetic microchannel battery by means of electrokinetic and microfluidic phenomena

    Science.gov (United States)

    Yang, Jun; Lu, Fuzhi; Kostiuk, Larry W.; Kwok, Daniel Y.

    2003-11-01

    Pressure-driven flow in a microchannel induces a streaming current due to the presence of an electrical double layer in the interface between the electrolyte solution and channel wall. As the streaming current is of the order of a nano-amphere and is additive, we propose here a method to develop an electrokinetic battery consisting of an array of microchannels that converts the hydrostatic pressure of a liquid into electrical work. We have given oscillating analytical solutions by means of an electrical circuit analysis to model the multi-microchannel battery. Using superposition of the appropriate Fourier series, the derived analytical solutions are useful to predict the current when there is more general time-dependent flow through a microchannel array. To illustrate the idea, we have studied steady-state pressure-driven flow in micropore porous glass filter and compared the results with those predicted from our model. From a 30 cm hydrostatic pressure drop, an external current of 1-2 µA was obtained by means of water passing through the micropore porous glass filter. A larger current can be obtained by simply using a solution with higher salt concentration. This results in a new and potentially useful method of energy conversion by means of an array of microchannels.

  13. New technique for radiation detection by instruments based on microchannel plates

    International Nuclear Information System (INIS)

    Ammosov, V.V.; Bolozdynya, A.I.; Kubantsev, M.A.; Lebedenko, V.N.; Suvorov, A.L.

    1986-01-01

    Coordinate information can be obtained directly from microchanel plates (MCP) as storage matrix in MCP based radiation detectors, which is proved using as an example the registering of pulsed laser ultraviolet radiation. For read-out and representation of the information the TV channel was used: the vidicon electron-optical system - TV transmission camera - TV monitor

  14. Detection of Aeromonas hydrophila Using Fiber Optic Microchannel Sensor

    Directory of Open Access Journals (Sweden)

    Samla Gauri

    2017-01-01

    Full Text Available This research focuses on the detection of Aeromonas hydrophila using fiber optic microchannel biosensor. Microchannel was fabricated by photolithography method. The fiber optic was chosen as signal transmitting medium and light absorption characteristic of different microorganisms was investigated for possible detection. Experimental results showed that Aeromonas hydrophila can be detected at the region of UV-Vis spectra between 352 nm and 354 nm which was comparable to measurement provided by UV spectrophotometer and also theoretical calculation by Beer-Lambert Absorption Law. The entire detection can be done in less than 10 minutes using a total volume of 3 μL only. This result promises good potential of this fiber optic microchannel sensor as a reliable, portable, and disposable sensor.

  15. Two-phase flow instabilities in a silicon microchannels heat sink

    International Nuclear Information System (INIS)

    Bogojevic, D.; Sefiane, K.; Walton, A.J.; Lin, H.; Cummins, G.

    2009-01-01

    Two-phase flow instabilities are highly undesirable in microchannels-based heat sinks as they can lead to temperature oscillations with high amplitudes, premature critical heat flux and mechanical vibrations. This work is an experimental study of boiling instabilities in a microchannel silicon heat sink with 40 parallel rectangular microchannels, having a length of 15 mm and a hydraulic diameter of 194 μm. A series of experiments have been carried out to investigate pressure and temperature oscillations during the flow boiling instabilities under uniform heating, using water as a cooling liquid. Thin nickel film thermometers, integrated on the back side of a heat sink with microchannels, were used in order to obtain a better insight related to temperature fluctuations caused by two-phase flow instabilities. Flow regime maps are presented for two inlet water temperatures, showing stable and unstable flow regimes. It was observed that boiling leads to asymmetrical flow distribution within microchannels that result in high temperature non-uniformity and the simultaneously existence of different flow regimes along the transverse direction. Two types of two-phase flow instabilities with appreciable pressure and temperature fluctuations were observed, that depended on the heat to mass flux ratio and inlet water temperature. These were high amplitude/low frequency and low amplitude/high frequency instabilities. High speed camera imaging, performed simultaneously with pressure and temperature measurements, showed that inlet/outlet pressure and the temperature fluctuations existed due to alternation between liquid/two-phase/vapour flows. It was also determined that the inlet water subcooling condition affects the magnitudes of the temperature oscillations in two-phase flow instabilities and flow distribution within the microchannels.

  16. Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

    International Nuclear Information System (INIS)

    Gruber, G.J.; Derenzo, S.E.

    1996-01-01

    A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. Using solenoidal magnetic lenses with a cur-rent density of 150 A·turns/cm 2 to focus the electron beam, a deflection plate dV/dt of 10 13 V/s is needed to achieve electron pulse widths of about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators, (e.g., BaF 2 ). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths

  17. Stabilization of two-phase octanol/water flows inside poly(dimethylsiloxane) microchannels using polymer coatings

    NARCIS (Netherlands)

    van der Linden, H. J.; Jellema, L. C.; Holwerda, M.; Verpoorte, E.

    In this paper we present our first results on the realization of stable water/octanol, two-phase flows inside poly(dimethylsiloxane) (PDMS) microchannels. Native PDMS microchannels were coated with high molecular weight polymers to change the surface properties of the microchannels and thus

  18. Anti-stiction coating of PDMS moulds for rapid microchannel fabrication by double replica moulding

    DEFF Research Database (Denmark)

    Zhuang, Guisheng; Kutter, Jörg Peter

    2011-01-01

    ), which resulted in an anti-stiction layer for the improved release after PDMS casting. The deposition of FDTS on an O2 plasma-activated surface of PDMS produced a reproducible and well-performing anti-stiction monolayer of fluorocarbon, and we used the FDTS-coated moulds as micro-masters for rapid......In this paper, we report a simple and precise method to rapidly replicate master structures for fast microchannel fabrication by double replica moulding of polydimethylsiloxane (PDMS). A PDMS mould was surface-treated by vapour phase deposition of 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS...

  19. Influence of Heat Shock Temperatures and Fast Freezing on Viability of Probiotic Sporeformers and the Issue of Spore Plate Count Versus True Numbers

    Directory of Open Access Journals (Sweden)

    Mojtaba Jafari

    2016-02-01

    Full Text Available Background and Objectives: The purpose of the present study was to investigate effects of various heat shock conditions and fast freezing and subsequent thawing on the viability and recovery of Bacillus coagulans and Bacillus subtilis as probiotic sporeformers, and also to compare spore plate and microscopic counts. Materials and Methods: After preparing the final suspensions of B. coagulans and Bacillus subtilis subsp. Natto spores, they were spread-plated before and after fast freezing treatment (-70°C for about 1 min. Heat shock treatments of the spores were carried out at 68oC for 15, 20, and 30 min as well as at 80oC for 10 and 15 min. Concentrations of the examined probiotic sporeformers were determined simultaneously by plate enumerations and microscopically determined counts. Student’s t-test and one-way analysis of variance (ANOVA of SPSS were used for statistical analysis of the data. Analysis of DoE results was carried out using Minitab. Results: The results presented here show that the highest recovery rates for B. coagulans (14.75 log CFU/mL and B. subtilis spores (14.80 log CFU/mL were under a heat shock condition of 68°C for 20 min in nutrient agar (p<0.05. In addition, the survival rates of B. coagulans and B. subtilis spores under the fast freezing and subsequent thawing condition were about 90% and 88%, respectively. Plate counts differed significantly from counts determined microscopically, with differences of almost 0.5 and 0.8 log for B. coagulans and B. subtilis spores, respectively (p<0.05. In addition, DoE results of the study revealed that both factors of spore count method and only freezing factor in fast freezing treatment have a significant effect on concentrations of the spores examined (p<0.05. Conclusions: Heat shock conditions, freezing and subsequent thawing circumstances, and plate counts or enumerations determined microscopically have significant influences on the viability of probiotic sporeformers and

  20. Detection, Quantification, and Microlocalisation of Targets of Pesticides Using Microchannel Plate Autoradiographic Imagers

    Directory of Open Access Journals (Sweden)

    Mabruka H. Tarhoni

    2011-10-01

    Full Text Available Organophosphorus (OP compounds are a diverse chemical group that includes nerve agents and pesticides. They share a common chemical signature that facilitates their binding and adduction of acetylcholinesterase (AChE within nerve synapses to induce cholinergic toxicity. However, this group diversity results in non-uniform binding and inactivation of other secondary protein targets, some of which may be adducted and protein activity influenced, even when only a relatively minor portion of tissue AChE is inhibited. The determination of individual OP protein binding targets has been hampered by the sensitivity of methods of detection and quantification of protein-pesticide adducts. We have overcome this limitation by the employment of a microchannel plate (MCP autoradiographic detector to monitor a radiolabelled OP tracer compound. We preincubated rat thymus tissue in vitro with the OP pesticides, azamethiphos-oxon, chlorfenvinphos-oxon, chlorpyrifos-oxon, diazinon-oxon, and malaoxon, and then subsequently radiolabelled the free OP binding sites remaining with 3H-diisopropylfluorophosphate (3H-DFP. Proteins adducted by OP pesticides were detected as a reduction in 3H-DFP radiolabelling after protein separation by one dimensional polyacrylamide gel electrophoresis and quantitative digital autoradiography using the MCP imager. Thymus tissue proteins of molecular weights ~28 kDa, 59 kDa, 66 kDa, and 82 kDa displayed responsiveness to adduction by this panel of pesticides. The 59 kDa protein target (previously putatively identified as carboxylesterase I was only significantly adducted by chlorfenvinphos-oxon (p < 0.001, chlorpyrifos-oxon (p < 0.0001, and diazinon-oxon (p < 0.01, the 66 kDa protein target (previously identified as serum albumin similarly only adducted by the same three pesticides (p < 0.0001, (p < 0.001, and (p < 0.01, and the 82 kDa protein target (previously identified as acyl peptide hydrolase only adducted by chlorpyrifos-oxon (p

  1. Fabrication of polyester microchannel with functional surface for electro-chromatography - Incorporation of detection devices into the microchip -

    International Nuclear Information System (INIS)

    Uchiyama, Katsumi; Qiu, Jing Miao; Hobo, Toshiyuki

    2001-01-01

    In recent years, new analytical techniques using microchip devise have been extensively studied (micro-TAS). One of the most successful examples is capillary electrophoresis (CE) with glass plate fabricated by photolithography followed by the chemical or physical etching process. Micro CE one of the most excellent separation techniques, performs separations in microchannel formed in appreciate substrate material. We developed a fabrication method for polyester micro channels with aikene alcohol inside the wall of the channel and demonstrated the usefulness of the polymer microchip. Although many researchers have been studying microchannel or micro-devices for analytical use, miniaturization of the total system including sample introduction, separation, detection and data treatment is still under development. Especially, the miniaturization of the detection system will be a hard bar to be overcome. Our method, based upon the in situ polymerization of polyester resin on an appreciate template, can be exported to let some parts incorporated directly into the microchip during the polymerization process. In this paper, we will describe the incorporation of detection components (light emitting diode and optical fiber) into polyester microchip and the application of the microchip to the analysis of amino acids separated by electrophoresis.

  2. Enhanced MicroChannel Heat Transfer in Macro-Geometry using Conventional Fabrication Approach

    Science.gov (United States)

    Ooi, KT; Goh, AL

    2016-09-01

    This paper presents studies on passive, single-phase, enhanced microchannel heat transfer in conventionally sized geometry. The intention is to allow economical, simple and readily available conventional fabrication techniques to be used for fabricating macro-scale heat exchangers with microchannel heat transfer capability. A concentric annular gap between a 20 mm diameter channel and an 19.4 mm diameter insert forms a microchannel where heat transfer occurs. Results show that the heat transfer coefficient of more than 50 kW/m·K can be obtained for Re≈4,000, at hydraulic diameter of 0.6 mm. The pressure drop values of the system are kept below 3.3 bars. The present study re-confirms the feasibility of fabricating macro-heat exchangers with microchannel heat transfer capability.

  3. Developing a method of fabricating microchannels using plant root structure

    Science.gov (United States)

    Nakashima, Shota; Tokumaru, Kazuki; Tsumori, Fujio

    2018-06-01

    Complicated three-dimensional (3D) microchannels are expected to be applied to a lab-on-a-chip, especially an organ-on-a-chip. There are fine microchannel networks such as blood vessels in a living organ. However, it is difficult to recreate the complicated 3D microchannels of real living structures. Plant roots have a similar structure to blood vessels. They spread radially and three-dimensionally, and become thinner as they branch. In this research, we propose a method of fabricating microchannels using a live plant root as a template to mimic a blood vessel structure. We grew a plant in ceramic slurry instead of soil. The slurry consists of ceramic powder, binder and water, so it plays a similar role to soil consisting of fine particles in water. After growing the plant, the roots inside the slurry were burned and a sintered ceramic body with channel structures was obtained by heating. We used two types of slurry with different composition ratios, and compared the internal channel structures before and after sintering.

  4. Development of a micro-heat exchanger with stacked plates using LTCC technology

    Directory of Open Access Journals (Sweden)

    E. Vásquez-Alvarez

    2010-09-01

    Full Text Available A green ceramic tape micro-heat exchanger was developed using Low Temperature Co-fired Ceramics technology (LTCC. The device was designed by using Computational Aided Design software and simulations were made using a Computational Fluid Dynamics package (COMSOL Multiphysics to evaluate the homogeneity of fluid distribution in the microchannels. Four geometries were proposed and simulated in two and three dimensions to show that geometric details directly affect the distribution of velocity in the micro-heat exchanger channels. The simulation results were quite useful for the design of the microfluidic device. The micro-heat exchanger was then constructed using the LTCC technology and is composed of five thermal exchange plates in cross-flow arrangement and two connecting plates, with all plates stacked to form a device with external dimensions of 26 x 26 x 6 mm³.

  5. High Flux Microchannel Receiver Development with Adap-tive Flow Control

    Energy Technology Data Exchange (ETDEWEB)

    Drost, Kevin [Oregon State Univ., Corvallis, OR (United States)

    2015-08-15

    This project is focused on the demonstration of a microchannel-based solar receiver (MSR). The MSR concept consists of using a modular arrangement of arrayed microchannels to heat a working fluid in a concentrating solar receiver, allowing a much higher solar flux on the receiver and consequently a significant reduction in thermal losses, size, and cost.

  6. Thermal mixing of two miscible fluids in a T-shaped microchannel.

    Science.gov (United States)

    Xu, Bin; Wong, Teck Neng; Nguyen, Nam-Trung; Che, Zhizhao; Chai, John Chee Kiong

    2010-10-01

    In this paper, thermal mixing characteristics of two miscible fluids in a T-shaped microchannel are investigated theoretically, experimentally, and numerically. Thermal mixing processes in a T-shaped microchannel are divided into two zones, consisting of a T-junction and a mixing channel. An analytical two-dimensional model was first built to describe the heat transfer processes in the mixing channel. In the experiments, de-ionized water was employed as the working fluid. Laser induced fluorescence method was used to measure the fluid temperature field in the microchannel. Different combinations of flow rate ratios were studied to investigate the thermal mixing characteristics in the microchannel. At the T-junction, thermal diffusion is found to be dominant in this area due to the striation in the temperature contours. In the mixing channel, heat transfer processes are found to be controlled by thermal diffusion and convection. Measured temperature profiles at the T-junction and mixing channel are compared with analytical model and numerical simulation, respectively.

  7. Experimental and theoretical analysis of defocused CO2 laser microchanneling on PMMA for enhanced surface finish

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2017-02-01

    The poor surface finish of CO2 laser-micromachined microchannel walls is a major limitation of its utilization despite several key advantages, like low fabrication cost and low time consumption. Defocused CO2 laser beam machining is an effective solution for fabricating smooth microchannel walls on polymer and glass substrates. In this research work, the CO2 laser microchanneling process on PMMA has been analyzed at different beam defocus positions. Defocused processing has been investigated both theoretically and experimentally, and the depth of focus and beam diameter have been determined experimentally. The effect of beam defocusing on the microchannel width, depth, surface roughness, heat affected zone and microchannel profile were examined. A previously developed analytical model for microchannel depth prediction has been improved by incorporating the threshold energy density factor. A semi-analytical model for predicting the microchannel width at different defocus positions has been developed. A semi-empirical model has also been developed for predicting microchannel widths at different defocusing conditions for lower depth values. The developed models were compared and verified by performing actual experiments. Multi-objective optimization was performed to select the best optimum set of input parameters for achieving the desired surface roughness.

  8. A two-step sealing-and-reinforcement SU8 bonding paradigm for the fabrication of shallow microchannels

    Science.gov (United States)

    Mehboudi, Aryan; Yeom, Junghoon

    2018-03-01

    Adhesive bonding is a key technique to create microfluidic devices when two separate substrates are used to form microchannels. Among many adhesives explored in microchannel fabrication, SU8 has been widely used as an adhesive layer for sealing the microchannel sidewalls. The majority of the available SU8-based bonding methods, however, suffer from the difficulties associated with sealing of two important types of the microchannel architecture: (1) shallow microchannels with small patterns on a large area, and (2) microchannels with ultra-low aspect ratios (e.g. 6 mm in width and 2~μ m in height). In this paper, a new bonding paradigm based upon the low-temperature and low-pressure SU8 bonding, consisting of two steps of sealing using a thin-SU8-coated PET film and bonding reinforcement using a SU8-coated glass slide, is proposed to resolve the aforementioned difficulties. Since it does not need complicated instruments such as a wafer bonding machine and a lamination device, the developed bonding paradigm is convenient and economical. We successfully demonstrate the compatibility of the proposed bonding paradigm with the two microchannel fabrication approaches based on the glass wet etching and the SU8 photo-lithography, where small microchannels with the innermost surfaces fully made of SU8 are obtained. A theoretical model is employed to better investigate the flow characteristics and the structural behavior of the microchannel including the PET film deformation, strain and von Mises stress distributions, bonding strength, etc. Moreover, we demonstrate the fabrication of the multi-height deep-shallow microchannel sidewalls and their sealing using the SU8-coated PET film. Finally, as a proof-of-concept device, a microfluidic filter consisting of the double-height deep-shallow microchannel is fabricated for separation of 3 µm and 10 µm particles.

  9. Conceptual design for Japan Sodium-Cooled Fast Reactor. (4) Developmental study of steel plate reinforced concrete containment vessel for JSFR

    International Nuclear Information System (INIS)

    Hosoya, Takusaburo; Negishi, Kazuo; Satoh, Kenichiro; Somaki, Takahiro; Matsuo, Ippei; Shimizu, Katsusuke

    2009-01-01

    An innovative containment vessel, namely Steel plate reinforced Concrete Containment Vessel (SCCV) is developed for Japan Sodium-Cooled Fast Reactor (JSFR). Reducing plant construction cost is one of the most important issues for commercialization of fast reactors. This study investigated construction issues including the building structure and the construction method as well as design issues in terms of the applicability of SCCV to fast reactors. An experimental study including loading and/or heating tests has been carried out to investigate the fundamental structural features, which would be provided to develop methodology to evaluate the feasibility of SCCV under the severe conditions. In this paper, the test plan is described as well as the first test results. (author)

  10. Development of pulsed plate columns for fast reactor fuel reprocessing

    International Nuclear Information System (INIS)

    Jenkins, J.A.; Logsdail, D.H.; Lyall, E.; Myers, P.E.; Partridge, B.A.

    1987-01-01

    The UK Atomic Energy Authority has undertaken a development programme on solvent extraction equipment for reprocessing fast reactor fuels. As part of this programme a solvent extraction pilot plant has been built at Harwell in which a variety of flowsheet conditions can be simulated using the system uranyl nitrate/nitric acid (UN/HNO 3 ) - 20% tri-n-butyl phosphate in odourless kerosene (TBP/OK). The main purpose of present pilot plant operations is to study the performance of pulsed plate columns, with the following specific objectives: to measure the volumetric throughput capacity of the columns, - to study the effect of scale-up of column diameter on U mass transfer performance, - to provide hydraulic and mass transfer data for a dynamic simulation model of pulsed column operation, - to develop and test instruments and ancillary equipment. This poster describes the pilot plant and is illustrated by experimental data, with particular reference to an external settler for controlling the removal of aqueous phase from columns operated with the aqueous phase dispersed

  11. Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    McCann, Ronán [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland); Bagga, Komal; Groarke, Robert [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); Stalcup, Apryll [Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); Vázquez, Mercedes, E-mail: mercedes.vazquez@dcu.ie [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); School of Chemical Sciences, Dublin City University, Dublin 9 (Ireland); Brabazon, Dermot [Advanced Processing Technology Research Centre, Dublin City University, Glasnevin, Dublin 9 (Ireland); School of Mechanical and Manufacturing Engineering, Dublin City University, Dublin 9 (Ireland); Irish Separation Science Cluster, National Centre for Sensor Research, Dublin City University, Dublin 9 (Ireland); National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)

    2016-11-30

    Highlights: • Rapid single-step microchannel fabrication on optically transparent cyclic olefin polymer using IR Nd:YAG laser. • Ability to tailor channel depth between 12–47 μm demonstrated for single laser pass. • Use of multiple laser passes showed capability for finer depth control. • Potential applications in lab-on-chip and microfluidic devices. - Abstract: This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

  12. Microchannel fabrication on cyclic olefin polymer substrates via 1064 nm Nd:YAG laser ablation

    International Nuclear Information System (INIS)

    McCann, Ronán; Bagga, Komal; Groarke, Robert; Stalcup, Apryll; Vázquez, Mercedes; Brabazon, Dermot

    2016-01-01

    Highlights: • Rapid single-step microchannel fabrication on optically transparent cyclic olefin polymer using IR Nd:YAG laser. • Ability to tailor channel depth between 12–47 μm demonstrated for single laser pass. • Use of multiple laser passes showed capability for finer depth control. • Potential applications in lab-on-chip and microfluidic devices. - Abstract: This paper presents a method for fabrication of microchannels on cyclic olefin polymer films that have application in the field of microfluidics and chemical sensing. Continuous microchannels were fabricated on 188-μm-thick cyclic olefin polymer substrates using a picosecond pulsed 1064 nm Nd:YAG laser. The effect of laser fluence on the microchannel morphology and dimensions was analysed via scanning electron microscopy and optical profilometry. Single laser passes were found to produce v-shaped microchannels with depths ranging from 12 μm to 47 μm and widths from 44 μm to 154 μm. The ablation rate during processing was lower than predicted theoretically. Multiple laser passes were applied to examine the ability for finer control over microchannel morphology with channel depths ranging from 22 μm to 77 μm and channel widths from 59 μm to 155 μm. For up to five repeat passes, acceptable reproducibility was found in the produced microchannel morphology. Infrared spectroscopy revealed oxidation and dehydrogenation of the polymer surface following laser ablation. These results were compared to other work conducted on cyclic olefin polymers.

  13. Theoretical Study of Molecular Transport Through a Permeabilized Cell Membrane in a Microchannel.

    Science.gov (United States)

    Mahboubi, Masoumeh; Movahed, Saeid; Hosseini Abardeh, Reza; Hoshyargar, Vahid

    2017-06-01

    A two-dimensional model is developed to study the molecular transport into an immersed cell in a microchannel and to investigate the effects of finite boundary (a cell is suspended in a microchannel), amplitude of electric pulse, and geometrical parameter (microchannel height and size of electrodes) on cell uptake. Embedded electrodes on the walls of the microchannel generate the required electric pulse to permeabilize the cell membrane, pass the ions through the membrane, and transport them into the cell. The shape of electric pulses is square with the time span of 6 ms; their intensities are in the range of 2.2, 2.4, 2.6, 3 V. Numerical simulations have been performed to comprehensively investigate the molecular uptake into the cell. The obtained results of the current study demonstrate that calcium ions enter the cell from the anodic side (the side near positive electrode); after a while, the cell faces depletion of the calcium ions on a positive electrode-facing side within the microchannel; the duration of depletion depends on the amplitude of electric pulse and geometry that lasts from microseconds to milliseconds. By keeping geometrical parameters and time span constant, increment of a pulse intensity enhances molecular uptake and rate of propagation inside the cell. If a ratio of electrode size to cell diameter is larger than 1, the transported amount of Ca 2+ into the cell, as well as the rate of propagation, will be significantly increased. By increasing the height of the microchannel, the rate of uptake is decreased. In an infinite domain, the peak concentration becomes constant after reaching the maximum value; this value depends on the intra-extracellular conductivity and diffusion coefficient of interior and exterior domains of the cell. In comparison, the maximum concentration is changed by geometrical parameters in the microchannel. After reaching the maximum value, the peak concentration reduces due to the depletion of Ca 2+ ions within the

  14. Investigation of Size Effects to the Mixing Performance on the X-shaped Micro-Channels

    Directory of Open Access Journals (Sweden)

    S Tu

    2016-09-01

    Full Text Available Due to the developing of micro-electro-mechanical-system, MEMS, the fabrication of the microminiaturization devices becomes obviously important. The advances in the basic understanding of fluid physics have opened an era of application of fluid dynamics systems using microchannels. The purpose of this study is to research the flow transport phenomenon by employing different kinds of micro-channel sizing in X-shaped micro-channels. As the working fluid, water is injected to microchannel at different mass flow rate. Over a wide range of flow condition, 1.06 < Re < 514, in X-shaped micro-channels, the mixture performances of numerical simulation, flow visualization, and temperature distribution remain the same. At the same mass flow rate as the Reynolds number below 112.53, the biggest channel size had the slowest flow velocity and got the best mixing performance; as the Reynolds number above 112.53, the smaller the channel sizing, the lower the pressure drops and the faster velocity becomes. The transition form early from laminar flow, the unsteady flow is an advantage for mixing in the limited mixing area, therefore 0.7 mm got the best mixing performance. It is clear that the size of the channel plays an important role in the X-shaped micro-channels.

  15. Nanosecond framing photography for laser-produced interstreaming plasmas

    International Nuclear Information System (INIS)

    McLean, E.A.; Ripin, B.H.; Stamper, J.A.; Manka, C.K.; Peyser, T.A.

    1988-01-01

    Using a fast-gated (120 psec-5 nsec) microchannel-plate optical camera (gated optical imager), framing photographs have been taken of the rapidly streaming laser plasma (∼ 5 x 10 7 cm/sec) passing through a vacuum or a background gas, with and without a magnetic field. Observations of Large-Larmor-Radius Interchange Instabilities are presented

  16. Passive assay of plutonium metal plates using a fast-neutron multiplicity counter

    Energy Technology Data Exchange (ETDEWEB)

    Di Fulvio, A., E-mail: difulvio@umich.edu [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Shin, T.H.; Jordan, T.; Sosa, C.; Ruch, M.L.; Clarke, S.D. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Chichester, D.L. [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Pozzi, S.A. [Department of Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2017-05-21

    We developed a fast-neutron multiplicity counter based on organic scintillators (EJ-309 liquid and stilbene). The system detects correlated photon and neutron multiplets emitted by fission reactions, within a gate time of tens of nanoseconds. The system was used at Idaho National Laboratory to assay a variety of plutonium metal plates. A coincidence counting strategy was used to quantify the {sup 240}Pu effective mass of the samples. Coincident neutrons, detected within a 40-ns coincidence window, show a monotonic trend, increasing with the {sup 240}Pu-effective mass (in this work, we tested the 0.005–0.5 kg range). After calibration, the system estimated the {sup 240}Pu effective mass of an unknown sample ({sup 240}Pu{sub eff} >50 g) with an uncertainty lower than 1% in a 4-min assay time.

  17. Micro-channel convective boiling heat transfer with flow instabilities

    International Nuclear Information System (INIS)

    Consolini, L.; Thome, J.R.

    2009-01-01

    Flow boiling heat transfer in micro-channels has attracted much interest in the past decade, and is currently a strong candidate for high performance compact heat sinks, such as those required in electronics systems, automobile air conditioning units, micro-reactors, fuel cells, etc. Currently the literature presents numerous experimental studies on two-phase heat transfer in micro-channels, providing an extensive database that covers many different fluids and operating conditions. Among the noteworthy elements that have been reported in previous studies, is the sensitivity of micro-channel evaporators to oscillatory two-phase instabilities. These periodic fluctuations in flow and pressure drop either result from the presence of upstream compressibility, or are simply due to the interaction among parallel channels in multi-port systems. An oscillating flow presents singular characteristics that are expected to produce an effect on the local heat transfer mechanisms, and thus on the estimation of the two-phase heat transfer coefficients. The present investigation illustrates results for flow boiling of refrigerants R-134a, R-236fa, and R-245fa in a 510 μm circular micro-channel, exposed to various degrees of oscillatory compressible volume instabilities. The data describe the main features of the fluctuations in the temperatures of the heated wall and fluid, and draw attention to the differences in the measured unstable time-averaged heat transfer coefficients with respect to those for stable flow boiling. (author)

  18. Micro-channel convective boiling heat transfer with flow instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Consolini, L.; Thome, J.R. [Ecole Polytechnique Federale de Lausanne (Switzerland). Lab. de Transfert de Chaleur et de Masse], e-mail: lorenzo.consolini@epfl.ch, e-mail: john.thome@epfl.ch

    2009-07-01

    Flow boiling heat transfer in micro-channels has attracted much interest in the past decade, and is currently a strong candidate for high performance compact heat sinks, such as those required in electronics systems, automobile air conditioning units, micro-reactors, fuel cells, etc. Currently the literature presents numerous experimental studies on two-phase heat transfer in micro-channels, providing an extensive database that covers many different fluids and operating conditions. Among the noteworthy elements that have been reported in previous studies, is the sensitivity of micro-channel evaporators to oscillatory two-phase instabilities. These periodic fluctuations in flow and pressure drop either result from the presence of upstream compressibility, or are simply due to the interaction among parallel channels in multi-port systems. An oscillating flow presents singular characteristics that are expected to produce an effect on the local heat transfer mechanisms, and thus on the estimation of the two-phase heat transfer coefficients. The present investigation illustrates results for flow boiling of refrigerants R-134a, R-236fa, and R-245fa in a 510 {mu}m circular micro-channel, exposed to various degrees of oscillatory compressible volume instabilities. The data describe the main features of the fluctuations in the temperatures of the heated wall and fluid, and draw attention to the differences in the measured unstable time-averaged heat transfer coefficients with respect to those for stable flow boiling. (author)

  19. 3D printed microchannel networks to direct vascularisation during endochondral bone repair.

    Science.gov (United States)

    Daly, Andrew C; Pitacco, Pierluca; Nulty, Jessica; Cunniffe, Gráinne M; Kelly, Daniel J

    2018-04-01

    Bone tissue engineering strategies that recapitulate the developmental process of endochondral ossification offer a promising route to bone repair. Clinical translation of such endochondral tissue engineering strategies will require overcoming a number of challenges, including the engineering of large and often anatomically complex cartilage grafts, as well as the persistence of core regions of avascular cartilage following their implantation into large bone defects. Here 3D printing technology is utilized to develop a versatile and scalable approach to guide vascularisation during endochondral bone repair. First, a sacrificial pluronic ink was used to 3D print interconnected microchannel networks in a mesenchymal stem cell (MSC) laden gelatin-methacryloyl (GelMA) hydrogel. These constructs (with and without microchannels) were next chondrogenically primed in vitro and then implanted into critically sized femoral bone defects in rats. The solid and microchanneled cartilage templates enhanced bone repair compared to untreated controls, with the solid cartilage templates (without microchannels) supporting the highest levels of total bone formation. However, the inclusion of 3D printed microchannels was found to promote osteoclast/immune cell invasion, hydrogel degradation, and vascularisation following implantation. In addition, the endochondral bone tissue engineering strategy was found to support comparable levels of bone healing to BMP-2 delivery, whilst promoting lower levels of heterotopic bone formation, with the microchanneled templates supporting the lowest levels of heterotopic bone formation. Taken together, these results demonstrate that 3D printed hypertrophic cartilage grafts represent a promising approach for the repair of complex bone fractures, particularly for larger defects where vascularisation will be a key challenge. Copyright © 2018 Elsevier Ltd. All rights reserved.

  20. Experimental investigation of two-phase gas-liquid flow in microchannel with T-junction

    Science.gov (United States)

    Bartkus, German; Kozulin, Igor; Kuznetsov, Vladimir

    2017-10-01

    Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in rectangular microchannels with an aspect ratio of 2.35 and 1.26. Experiments were earned out for the vertical flow of ethanol-nitrogen mixture in a microchannel with a cross section of 553×235 µm and for the horizontal flow of water-nitrogen mixture in a microchannel with a cross section of 315×250 µm. The T-mixer was used at the channel's inlet for gas-liquid flow formation. It was observed that elongated bubble, transition, and annular flows are the main regimes for a microchannel with a hydraulic diameter substantially less than the capillary constant. Using laser scanning, the maps of flow regimes for ethanol-nitrogen and water-nitrogen mixtures were obtained and discussed.

  1. 3D simulation of Heat transfer in MEMS-based microchannel

    International Nuclear Information System (INIS)

    Choi, Chi Woong; Huh, Cheol; Kim, Dong Eok; Kim, Moo Hwan

    2007-01-01

    The microchannel heat sink is promising heat dissipation method for high heat flux source. Contrary to conventional circular channel, MEMS based microchannel had rectangular or trapezoidal cross-sectional shape. In our study, we conducted three dimensional conjugate heat transfer calculation for rectangular shape microchannel. First, we simulated that channel was completely drained with known heating power. As a result we obtained calibration line, which indicates heat loss was function of temperature. Second, we simulated single phase heat transfer with various mass flux, 100-400 kg/m 2 s. In conclusion, the single phase test verified that the present heat loss evaluation method is applicable to micro scale heat transfer devices. Heat fluxes from each side wall shows difference due to non-uniform heating. However those ratios were correlated with supplied total heat. Finally, we proposed effective area correction factor to evaluate appropriate heat flux

  2. Fast plasma shutdown by killer pellet injection in JT-60U with reduced heat flux on the divertor plate and avoiding runaway electron generation

    International Nuclear Information System (INIS)

    Yoshino, R.; Kondoh, T.; Neyatani, Y.; Itami, K.; Kawano, Y.; Isei, N.

    1997-01-01

    A killer pellet is an impurity pellet that is injected into a tokamak plasma in order to terminate a discharge without causing serious damage to the tokamak machine. In JT-60U neon ice pellets have been injected into OH and NB heated plasmas and fast plasma shutdowns have been demonstrated without large vertical displacement. The heat pulse on the divertor plate has been greatly reduced by killer pellet injections (KPI), but a low-power heat flux tail with a long time duration is observed. The total energy on the divertor plate increases with longer heat flux tail, so it has been reduced by shortening the tail. Runaway electron (RE) generation has been observed just after KPI and/or in the later phase of the plasma current quench. However, RE generation has been avoided when large magnetic perturbations are excited. These experimental results clearly show that KPI is a credible fast shutdown method avoiding large vertical displacement, reducing heat flux on the divertor plate, and avoiding (or minimizing) RE generation. (Author)

  3. Microchannel Reactor System for Catalytic Hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Adeniyi Lawal; Woo Lee; Ron Besser; Donald Kientzler; Luke Achenie

    2010-12-22

    We successfully demonstrated a novel process intensification concept enabled by the development of microchannel reactors, for energy efficient catalytic hydrogenation reactions at moderate temperature, and pressure, and low solvent levels. We designed, fabricated, evaluated, and optimized a laboratory-scale microchannel reactor system for hydrogenation of onitroanisole and a proprietary BMS molecule. In the second phase of the program, as a prelude to full-scale commercialization, we designed and developed a fully-automated skid-mounted multichannel microreactor pilot plant system for multiphase reactions. The system is capable of processing 1 – 10 kg/h of liquid substrate, and an industrially relevant immiscible liquid-liquid was successfully demonstrated on the system. Our microreactor-based pilot plant is one-of-akind. We anticipate that this process intensification concept, if successfully demonstrated, will provide a paradigm-changing basis for replacing existing energy inefficient, cost ineffective, environmentally detrimental slurry semi-batch reactor-based manufacturing practiced in the pharmaceutical and fine chemicals industries.

  4. Inertial effects on heat transfer in superhydrophobic microchannels

    Science.gov (United States)

    Cowley, Adam; Maynes, Daniel; Crockett, Julie; Iverson, Brian; BYU Fluids Team

    2015-11-01

    This work numerically studies the effects of inertia on thermal transport in superhydrophbic microchannels. An infinite parallel plate channel comprised of structured superhydrophbic walls is considered. The structure of the superhydrophobic surfaces consists of square pillars organized in a square array aligned with the flow direction. Laminar, fully developed flow is explored. The flow is assumed to be non-wetting and have an idealized flat meniscus. A shear-free, adiabatic boundary condition is used at the liquid/gas interface, while a no-slip, constant heat flux condition is used at the liquid/solid interface. A wide range of Peclet numbers, relative channel spacing distances, and relative pillar sizes are considered. Results are presented in terms of Poiseuille number, Nusselt number, hydrodynamic slip length, and temperature jump length. Interestingly, the thermal transport is varied only slightly by inertial effects for a wide range of parameters explored and compares well with other analytical and numerical work that assumed Stokes flow. It is only for very small relative channel spacing and large Peclet number that inertial effects exert significant influence. Overall, the heat transfer is reduced for the superhydrophbic channels in comparison to classic smooth walled channels. This research was supported by the National Science Foundation (NSF) - United States (Grant No. CBET-1235881).

  5. Effects of surface roughness and electrokinetic heterogeneity on electroosmotic flow in microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Masilamani, Kannan; Ganguly, Suvankar; Feichtinger, Christian; Bartuschat, Dominik; Rüde, Ulrich, E-mail: suva_112@yahoo.co.in [Department of Computer Science 10 University of Erlangen-Nuremberg, Cauerstr.11 91058 Erlangen (Germany)

    2015-06-15

    In this paper, a hybrid lattice-Boltzmann and finite-difference (LB-FD) model is applied to simulate the effects of three-dimensional surface roughness and electrokinetic heterogeneity on electroosmotic flow (EOF) in a microchannel. The lattice-Boltzmann (LB) method has been employed to obtain the flow field and a finite-difference (FD) method is used to solve the Poisson-Boltzmann (PB) equation for the electrostatic potential distribution. Numerical simulation of flow through a square cross-section microchannel with designed roughness is conducted and the results are critically analysed. The effects of surface heterogeneity on the electroosmotic transport are investigated for different roughness height, width, roughness interval spacing, and roughness surface potential. Numerical simulations reveal that the presence of surface roughness changes the nature of electroosmotic transport through the microchannel. It is found that the electroosmotic velocity decreases with the increase in roughness height and the velocity profile becomes asymmetric. For the same height of the roughness elements, the EOF velocity rises with the increase in roughness width. For the heterogeneously charged rough channel, the velocity profile shows a distinct deviation from the conventional plug-like flow pattern. The simulation results also indicate locally induced flow vortices which can be utilized to enhance the flow and mixing within the microchannel. The present study has important implications towards electrokinetic flow control in the microchannel, and can provide an efficient way to design a microfluidic system of practical interest. (paper)

  6. Microchannel Methanation Reactors Using Nanofabricated Catalysts, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and the Pennsylvania State University (Penn State) propose to develop and demonstrate a microchannel methanation reactor based on...

  7. Computational Fluid Dynamics Study of Channel Geometric Effect for Fischer-Tropsch Microchannel Reactor

    International Nuclear Information System (INIS)

    Na, Jonggeol; Jung, Ikhwan; Kshetrimayum, Krishnadash S.; Park, Seongho; Park, Chansaem; Han, Chonghun

    2014-01-01

    Driven by both environmental and economic reasons, the development of small to medium scale GTL(gas-to-liquid) process for offshore applications and for utilizing other stranded or associated gas has recently been studied increasingly. Microchannel GTL reactors have been preferred over the conventional GTL reactors for such applications, due to its compactness, and additional advantages of small heat and mass transfer distance desired for high heat transfer performance and reactor conversion. In this work, multi-microchannel reactor was simulated by using commercial CFD code, ANSYS FLUENT, to study the geometric effect of the microchannels on the heat transfer phenomena. A heat generation curve was first calculated by modeling a Fischer-Tropsch reaction in a single-microchannel reactor model using Matlab-ASPEN integration platform. The calculated heat generation curve was implemented to the CFD model. Four design variables based on the microchannel geometry namely coolant channel width, coolant channel height, coolant channel to process channel distance, and coolant channel to coolant channel distance, were selected for calculating three dependent variables namely, heat flux, maximum temperature of coolant channel, and maximum temperature of process channel. The simulation results were visualized to understand the effects of the design variables on the dependent variables. Heat flux and maximum temperature of cooling channel and process channel were found to be increasing when coolant channel width and height were decreased. Coolant channel to process channel distance was found to have no effect on the heat transfer phenomena. Finally, total heat flux was found to be increasing and maximum coolant channel temperature to be decreasing when coolant channel to coolant channel distance was decreased. Using the qualitative trend revealed from the present study, an appropriate process channel and coolant channel geometry along with the distance between the adjacent

  8. Corrosion resistance characteristics of stamped and hydroformed proton exchange membrane fuel cell metallic bipolar plates

    Energy Technology Data Exchange (ETDEWEB)

    Dundar, F. [NSF I/UCRC Center for Precision Forming (CPF), Virginia Commonwealth University, Richmond, VA (United States); Department of Materials Science and Engineering, Gebze Institute of Technology (Turkey); Dur, Ender; Koc, M. [NSF I/UCRC Center for Precision Forming (CPF), Virginia Commonwealth University, Richmond, VA (United States); Mahabunphachai, S. [NSF I/UCRC Center for Precision Forming (CPF), Virginia Commonwealth University, Richmond, VA (United States); National Metal and Materials Technology Center (MTEC), Pathumthani (Thailand)

    2010-06-01

    Metallic bipolar plates have several advantages over bipolar plates made from graphite and composites due to their high conductivity, low material and production costs. Moreover, thin bipolar plates are possible with metallic alloys, and hence low fuel cell stack volume and mass are. Among existing fabrication methods for metallic bipolar plates, stamping and hydroforming are seen as prominent approaches for mass production scales. In this study, the effects of important process parameters of these manufacturing processes on the corrosion resistance of metallic bipolar plates made of SS304 were investigated. Specifically, the effects of punch speed, pressure rate, stamping force and hydroforming pressure were studied as they were considered to inevitably affect the bipolar plate micro-channel dimensions, surface topography, and hence the corrosion resistance. Corrosion resistance under real fuel cell conditions was examined using both potentiodynamic and potentiostatic experiments. The majority of the results exhibited a reduction in the corrosion resistance for both stamped and hydroformed plates when compared with non-deformed blank plates of SS304. In addition, it was observed that there exist an optimal process window for punch speed in stamping and the pressure rate in hydroforming to achieve improved corrosion resistance at a faster production rate. (author)

  9. Silicon monolithic microchannel-cooled laser diode array

    International Nuclear Information System (INIS)

    Skidmore, J. A.; Freitas, B. L.; Crawford, J.; Satariano, J.; Utterback, E.; DiMercurio, L.; Cutter, K.; Sutton, S.

    2000-01-01

    A monolithic microchannel-cooled laser diode array is demonstrated that allows multiple diode-bar mounting with negligible thermal cross talk. The heat sink comprises two main components: a wet-etched Si layer that is anodically bonded to a machined glass block. The continuous wave (cw) thermal resistance of the 10 bar diode array is 0.032 degree sign C/W, which matches the performance of discrete microchannel-cooled arrays. Up to 1.5 kW/cm 2 is achieved cw at an emission wavelength of ∼808 nm. Collimation of a diode array using a monolithic lens frame produced a 7.5 mrad divergence angle by a single active alignment. This diode array offers high average power/brightness in a simple, rugged, scalable architecture that is suitable for large two-dimensional areas. (c) 2000 American Institute of Physics

  10. Micro-Channel Embedded Pulsating Heat Pipes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — As the need for thermal control technology becomes more demanding Micro-Channel Embedded Pulsating Heat Pipes (ME-PHPs) represents a sophisticated and enabling...

  11. Distillation process using microchannel technology

    Science.gov (United States)

    Tonkovich, Anna Lee [Dublin, OH; Simmons, Wayne W [Dublin, OH; Silva, Laura J [Dublin, OH; Qiu, Dongming [Carbondale, IL; Perry, Steven T [Galloway, OH; Yuschak, Thomas [Dublin, OH; Hickey, Thomas P [Dublin, OH; Arora, Ravi [Dublin, OH; Smith, Amanda [Galloway, OH; Litt, Robert Dwayne [Westerville, OH; Neagle, Paul [Westerville, OH

    2009-11-03

    The disclosed invention relates to a distillation process for separating two or more components having different volatilities from a liquid mixture containing the components. The process employs microchannel technology for effecting the distillation and is particularly suitable for conducting difficult separations, such as the separation of ethane from ethylene, wherein the individual components are characterized by having volatilities that are very close to one another.

  12. Numerical study on boiling heat transfer enhancement in a microchannel heat exchanger

    International Nuclear Information System (INIS)

    Jeon, Jin Ho; Suh, Young Ho; Son, Gi Hun

    2008-01-01

    Flow boiling in a microchannel heat exchanger has received attention as an effective heat removal mechanism for high power-density microelectronics. Despite extensive experimental studied, the bubble dynamics coupled with boiling heat transfer in a microchannel heat exchanger is still not well understood due to the technological difficulties in obtaining detailed measurements of microscale two-phase flows. In this study, complete numerical simulations are performed to further clarify the dynamics of flow boiling in a microchannel heat exchanger. The level set method for tracking the liquid-vapor interface is modified to include the effects of phase change and contact angle and to treat an immersed solid surface. Based on the numerical results, the effects of modified channel shape on the bubble growth and heat transfer are quantified

  13. An experimental study on flow friction and heat transfer of water in sinusoidal wavy silicon microchannels

    Science.gov (United States)

    Huang, Houxue; Wu, Huiying; Zhang, Chi

    2018-05-01

    Sinusoidal wavy microchannels have been known as a more heat transfer efficient heat sink for the cooling of electronics than normal straight microchannels. However, the existing experimental study on wavy silicon microchannels with different phase differences are few. As a result of this, in this paper an experimental study has been conducted to investigate the single phase flow friction and heat transfer of de-ionized water in eight different sinusoidal wavy silicon microchannels (SWSMCs) and one straight silicon microchannel (SMC). The SWSMCs feature different phase differences (α  =  0 to π) and different relative wavy amplitudes (β  =  A/l  =  0.05 to 0.4), but the same average hydraulic diameters (D h  =  160 µm). It is found that both flow friction constant fRe and the Nusselt number depend on the phase difference and relative wavy amplitude. For sinusoidal wavy microchannels with a relative wavy amplitude (β  =  0.05), the Nusselt number increased noticeably with the phase difference for Re  >  250, but the effect was insignificant for Re  reducing the wavy wave length induced higher pressure drop and apparent friction constant fRe, while the Nusselt number increased with relative wavy amplitude for Re  >  300. The results indicate that the thermal resistances of sinusoidal wavy silicon microchannels were generally lower than that of straight silicon microchannels, and the thermal resistance decreased with the increase in relative wavy amplitude. The enhancement of thermal performance is attributed to the flow re-circulation occurring in the corrugation troughs and the secondary flows or Dean vortices introduced by curved channels. It is concluded that silicon sinusoidal wavy microchannels provide higher heat transfer rate albeit with a higher flow friction, making it a better choice for the cooling of high heat flux electronics.

  14. Use of the μPIV technique for an indirect determination of the microchannel cross-section passage geometry

    International Nuclear Information System (INIS)

    Puccetti, G; Pulvirenti, B; Morini, G L

    2014-01-01

    In this work the possible use of the μPIV technique for the experimental determination of the microchannel cross-section geometry has been investigated by means of a blind test in which a series of experimental measurements obtained using glass microchannels having a declared rectangular cross-section with a depth of 100 μm and width of 300 μm and a square microchannel with a 300 μm side have been compared with the direct SEM visualisation of the real cross section of the microchannels. For the (oPIV measurements water is used as working fluid. The laminar fully developed 2D velocity profile has been reconstructed by moving the focal plane of the microscope objective from the bottom to the top of the microchannel. The results shown in this paper demonstrate that the real cross section geometry of the microchannel can be predicted by minimizing the difference between the theoretical and the experimental 2D velocity profiles. When the right passage geometry is determined, the average difference between the theoretical and the experimental velocity is within 4-6%.

  15. The Effect of the Rolling Direction, Temperature, and Etching Time on the Photochemical Machining of Monel 400 Microchannels

    Directory of Open Access Journals (Sweden)

    Deepakkumar H. Patil

    2016-01-01

    Full Text Available The present paper describes the effect of the rolling direction on the quality of microchannels manufactured using photochemical machining (PCM of Monel 400. Experiments were carried out to fabricate microchannels along and across the rolling direction to investigate the effect of the grain orientation on microchannel etching. The input parameters considered were channel width and rolling direction, whereas the depth of etch was the response parameters. Different channels of widths of 60, 100, 150, 200, and 250 μm were etched. The effects of the etching time and temperature of the etchant solution on the undercut and depth of the microchannels were studied. For good quality microchannels, the effects of spinning time, spinning speed, exposure time, and photoresist film strength were also taken into consideration. Optimized values of the above were used for the experimentation. The results show that the depth of etch of the microchannel increases more along the rolling direction than across the rolling direction. The channel width and depth are significantly affected by the etching time and temperature. The proposed study reports an improvement in the quality of microchannels produced using PCM.

  16. Thermal effect of a thermoelectric generator on parallel microchannel heat sink

    DEFF Research Database (Denmark)

    Kolaei, Alireza Rezania; Rosendahl, Lasse

    2012-01-01

    Thermoelectric generators (TEG) convert heat energy to electrical power by means of semiconductor charge carriers serving as working fluid. In this work, a TEG is applied to a parallel microchannel heat sink. The effect of the inlet plenum arrangement on the laminar flow distribution...... in the channels is considered at a wide range of the pressure drop along the heat sink. The particular focus of this study is geometrical effect of the TEG on the heat transfer characteristics in the micro-heat sink. The hydraulic diameter of the microchannels is 270 μm, and three heat fluxes are applied...... on the hot surface of the TEG. By considering the maximum temperature limitation for Bi_2 Te_3 material and using the microchannel heat sink for cooling down the TEG system, an optimum pumping power is achieved. The results are in a good agreement with the previous experimental and theoretical studies....

  17. Flow friction and heat transfer of ethanol–water solutions through silicon microchannels

    International Nuclear Information System (INIS)

    Wu Huiying; Wu Xinyu; Wei Zhen

    2009-01-01

    An experimental investigation was performed on the flow friction and convective heat transfer characteristics of the ethanol–water solutions flowing through five sets of trapezoidal silicon microchannels having hydraulic diameters ranging from 141.7 µm to 268.6 µm. Four kinds of ethanol–water solutions with the ethanol volume concentrations ranging from 0 to 0.8 were tested under different flow and heating conditions. It was found that the cross-sectional geometric parameters had great effect on the flow friction and heat transfer, and the microchannels with a larger W b /W t (bottom width-to-top width ratio) and a smaller H/W t (depth-to-top width ratio) usually had a larger friction constant and a higher Nusselt number. Entrance effects were significant for the flow friction and heat transfer in silicon microchannels, and decreased with the increase of dimensionless hydrodynamic length L and dimensionless thermal length L + h . When L > 1.0, the hydrodynamic entrance effect on the flow friction was ignorable. For the developed laminar flow in silicon microchannels, the Navier–Stokes equation was applicable. It was also found that the volume concentrations had different effects on the flow friction and heat transfer. Within the experimental range, the effect of volume concentrations on the flow friction was ignorable, and the friction constants of the ethanol–water solutions having different concentrations were the same as those of the pure water. However, volume concentrations had great effect on the convection heat transfer in silicon microchannels. With the increase of the volume concentrations, the Nusselt number of the ethanol–water solutions increased obviously, which was attributed to the combination effect of the increase in the Prantdtl number as well as the volatilization effect of the ethanol. Based on the experimental data, the dimensionless correlations for the flow friction and heat transfer of the ethanol–water solutions in the silicon

  18. Electro-osmotic flows inside triangular microchannels

    International Nuclear Information System (INIS)

    Vocale, P; Spiga, M; Geri, M; Morini, G L

    2014-01-01

    This work presents a numerical investigation of both pure electro-osmotic and combined electro-osmotic/pressure-driven flows inside triangular microchannels. A finite element analysis has been adopted to solve the governing equations for the electric potential and the velocity field, accounting for a finite thickness of the electric double layer. The influence of non-dimensional parameters such as the aspect ratio of the cross-section, the electrokinetic diameter and the ratio of the pressure force to the electric force on the flow behavior has been investigated. Numerical results point out that the velocity field is significantly influenced by the aspect ratio of the cross section and the electrokinetic diameter. More specifically, the aspect ratio plays an important role in determining the maximum volumetric flow rate, while the electrokinetic diameter is crucial to establishing the range of pressures that may be sustained by the electro-osmotic flow. Numerical results are also compared with two correlations available in the literature which enable to assess the volumetric flow rate and the pressure head for microchannels featuring a rectangular, a trapezoidal or an elliptical cross-section.

  19. Numerical investigation of fluid flow and heat transfer under high heat flux using rectangular micro-channels

    KAUST Repository

    Mansoor, Mohammad M.

    2012-02-01

    A 3D-conjugate numerical investigation was conducted to predict heat transfer characteristics in a rectangular cross-sectional micro-channel employing simultaneously developing single-phase flows. The numerical code was validated by comparison with previous experimental and numerical results for the same micro-channel dimensions and classical correlations based on conventional sized channels. High heat fluxes up to 130W/cm 2 were applied to investigate micro-channel thermal characteristics. The entire computational domain was discretized using a 120×160×100 grid for the micro-channel with an aspect ratio of (α=4.56) and examined for Reynolds numbers in the laminar range (Re 500-2000) using FLUENT. De-ionized water served as the cooling fluid while the micro-channel substrate used was made of copper. Validation results were found to be in good agreement with previous experimental and numerical data [1] with an average deviation of less than 4.2%. As the applied heat flux increased, an increase in heat transfer coefficient values was observed. Also, the Reynolds number required for transition from single-phase fluid to two-phase was found to increase. A correlation is proposed for the results of average Nusselt numbers for the heat transfer characteristics in micro-channels with simultaneously developing, single-phase flows. © 2011 Elsevier Ltd.

  20. Forced convection flow boiling and two-phase flow phenomena in a microchannel

    Science.gov (United States)

    Na, Yun Whan

    2008-07-01

    The present study was performed to numerically analyze the evaporation phenomena through the liquid-vapor interface and to investigate bubble dynamics and heat transfer behavior during forced convective flow boiling in a microchannel. Flow instabilities of two-phase flow boiling in a microchannel were studied as well. The main objective of this research is to investigate the fundamental mechanisms of two-phase flow boiling in a microchannel and provide predictive tools to design thermal management systems, for example, microchannel heat sinks. The numerical results obtained from this study were qualitatively and quantitatively compared with experimental results in the open literature. Physical and mathematical models, accounting for evaporating phenomena through the liquid-vapor interface in a microchannel at constant heat flux and constant wall temperature, have been developed, respectively. The heat transfer mechanism is affected by the dominant heat conduction through the thin liquid film and vaporization at the liquid-vapor interface. The thickness of the liquid film and the pressure of the liquid and vapor phases were simultaneously solved by the governing differential equations. The developed semi-analytical evaporation model that takes into account of the interfacial phenomena and surface tension effects was used to obtain solutions numerically using the fourth-order Runge-Kutta method. The effects of heat flux 19 and wall temperature on the liquid film were evaluated. The obtained pressure drops in a microchannel were qualitatively consistent with the experimental results of Qu and Mudawar (2004). Forced convective flow boiling in a single microchannel with different channel heights was studied through a numerical simulation to investigate bubble dynamics, flow patterns, and heat transfer. The momentum and energy equations were solved using the finite volume method while the liquid-vapor interface of a bubble is captured using the VOF (Volume of Fluid

  1. Cooling Performance of Additively Manufactured Microchannels and Film Cooling Holes

    Science.gov (United States)

    Stimpson, Curtis K.

    Additive manufacturing (AM) enables fabrication of components that cannot be made with any other manufacturing method. Significant advances in metal-based AM systems have made this technology feasible for building production parts to be used use in commercial products. In particular, the gas turbine industry benefits from AM as a manufacturing technique especially for development of components subjected to high heat flux. It has been shown that the use of microchannels in high heat flux components can lead to more efficient cooling designs than those that presently exist. The current manufacturing methods have prevented the use of microchannels in such parts, but AM now makes them manufacturable. However, before such designs can become a reality, much research must be done to characterize impacts on flow and heat transfer of AM parts. The current study considers the effect on flow and heat transfer through turbine cooling features made with AM. Specifically, the performance of microchannels and film cooling holes made with laser powder bed fusion (L-PBF) is assessed. A number of test coupons containing microchannels were built from high temperature alloy powders on a commercially available L-PBF machine. Pressure drop and heat transfer experiments characterized the flow losses and convective heat transfer of air passing through the channels at various Reynolds numbers and Mach numbers. The roughness of the channels' surfaces was characterized in terms of statistical roughness parameters; the morphology of the roughness was examined qualitatively. Magnitude and morphology of surface roughness found on AM parts is unlike any form of roughness seen in the literature. It was found that the high levels of roughness on AM surfaces result in markedly augmented pressure loss and heat transfer at all Reynolds numbers, and conventional flow and heat transfer correlations produce erroneous estimates. The physical roughness measurements made in this study were correlated to

  2. Numerical study of the bubbly flow regime in micro-channel flow boiling

    Science.gov (United States)

    Bhuvankar, Pramod; Dabiri, Sadegh

    2017-11-01

    Two-phase flow accompanied by boiling in micro-channel heat sinks is an effective means for heat removal from computer chips. We present a numerical study of flow boiling in micro-channels with conjugate heat transfer with a focus on the bubbly flow regime. The bubbles are assumed to nucleate at a pre-determined location and frequency. The Navier Stokes equations are solved using a single fluid formulation with the Front tracking method. Phase change is implemented using the deficit in heat flux across the bubble interface. The analytical solution for bubble growth in a superheated liquid is used as a benchmark to validate the mentioned numerical method. Water and FC-72 are studied as the operating fluids in a micro-channel made of Copper with a focus on hotspot mitigation. The micro-channel of cross-section 231 μm × 1000 μm , is used to study the effects of vertical up-flow, vertical down-flow and horizontal flow of the mentioned fluids on the heat transfer coefficients. A simple film model accounting for mass and energy conservation is applied wherever the bubble approaches closer than a cell width to the wall. The results of the simulation are compared with existing experimental data for bubble growth rates and heat transfer coefficients.

  3. Flow and heat transfer behaviour of nanofluids in microchannels

    Directory of Open Access Journals (Sweden)

    James Bowers

    2018-04-01

    Full Text Available Flow and heat transfer of aqueous based silica and alumina nanofluids in microchannels were experimentally investigated. The measured friction factors were higher than conventional model predictions at low Reynolds numbers particularly with high nanoparticle concentrations. A decrease in the friction factor was observed with increasing Reynolds number, possibly due to the augmentation of nanoparticle aggregate shape arising from fluid shear and alteration of local nanoparticle concentration and nanofluid viscosity. Augmentation of the silica nanoparticle morphology by fluid shear may also have affected the friction factor due to possible formation of a core/shell structure of the particles. Measured thermal conductivities of the silica nanofluids were in approximate agreement with the Maxwell-Crosser model, whereas the alumina nanofluids only showed slight enhancements. Enhanced convective heat transfer was observed for both nanofluids, relative to their base fluids (water, at low particle concentrations. Heat transfer enhancement increased with increasing Reynolds number and microchannel hydraulic diameter. However, the majority of experiments showed a larger increase in pumping power requirements relative to heat transfer enhancements, which may hinder the industrial uptake of the nanofluids, particularly in confined environments, such as Micro Electro-Mechanical Systems (MEMS. Keywords: Nanofluid, Microchannel, Heat transfer, Pressure drop, Friction factor, Thermal conductivity, Viscosity

  4. Effect of supersaturation on L-glutamic acid polymorphs under droplet-based microchannels

    Science.gov (United States)

    Jiang, Nan; Wang, Zhanzhong; Dang, Leping; Wei, Hongyuan

    2016-07-01

    Supersaturation is an important controlling factor for crystallization process and polymorphism. Droplet-based microchannels and conventional crystallization were used to investigate polymorphs of L-gluatamic acid in this work. The results illustrate that it is easy to realize the accurate and rapid control of the crystallization temperature in the droplets, which is especially beneficial to heat and mass transfer during crystallization. It is also noted that higher degree of supersaturation favors the nucleation of α crystal form, while lower degree of supersaturation favors the nucleation of β crystal form under droplet-based microchannels for L-gluatamic acid. In addition, there is a different nucleation behavior to be found under droplet-based microchannels both for the β form and α form of L-glutamic acid. This new finding can provide important insight into the development and design of investigation meanings for drug polymorph.

  5. Comparison of heat pump performance using fin-and-tube and microchannel heat exchangers under frost conditions

    International Nuclear Information System (INIS)

    Shao, Liang-Liang; Yang, Liang; Zhang, Chun-Lu

    2010-01-01

    Vapor compression heat pumps are drawing more attention in energy saving applications. Microchannel heat exchangers can provide higher performance via less core volume and reduce system refrigerant charge, but little is known about their performance in heat pump systems under frosting conditions. In this study, the system performance of a commercial heat pump using microchannel heat exchangers as evaporator is compared with that using conventional finned-tube heat exchangers numerically and experimentally. The microchannel and finned-tube heat pump system models used for comparison of the microchannel and finned-tube evaporator performance under frosting conditions were developed, considering the effect of maldistribution on both refrigerant and air sides. The quasi-steady-state modeling results are in reasonable agreement with the test data under frost conditions. The refrigerant-side maldistribution is found remarkable impact on the microchannel heat pump system performance under the frost conditions. Parametric study on the fan speed and the fin density under frost conditions are conducted as well to figure out the best trade-off in the design of frost tolerant evaporators. (author)

  6. Transition from annular flow to plug/slug flow in condensation of steam in microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Xiaojun; Cheng, Ping; Wu, Huiying [School of Mechanical and Power Engineering, Shanghai Jiaotong University, 800 Dong Chuan Road, Shanghai 200240 (China)

    2008-02-15

    A visualization study has been conducted to investigate the transition from annular flow to plug/slug flow in the condensation of steam in two different sets of parallel microchannels, having hydraulic diameters of 90 {mu}m and 136 {mu}m, respectively. The steam in the parallel microchannels was cooled on the bottom by forced convection of water and by natural convection of air from the top. It is found that the location, where the transition from annular flow to plug/slug flow takes place, depends on mass flux and cooling rate of steam. The effects of mass flux and cooling rate on the occurrence frequency of the injection flow in a single microchannel, having a hydraulic diameter of 120 {mu}m and 128 {mu}m, respectively, are investigated. It is found that two different shapes of injection flow occur in the smooth annular flow in microchannels: injection flow with unsteady vapor ligament occurring at low mass flux (or high cooling rate) and injection flow with steady vapor ligament occurring at high mass flux (or low cooling rate). It is also found that increase of steam mass flux, decrease of cooling rate, or decrease of the microchannel diameter tends to enhance instability of the condensate film on the wall, resulting in occurrence of the injection flow further toward the outlet with an increase in occurrence frequency. (author)

  7. In vitro blood flow in a rectangular PDMS microchannel: experimental observations using a confocal micro-PIV system.

    Science.gov (United States)

    Lima, Rui; Wada, Shigeo; Tanaka, Shuji; Takeda, Motohiro; Ishikawa, Takuji; Tsubota, Ken-ichi; Imai, Yohsuke; Yamaguchi, Takami

    2008-04-01

    Progress in microfabricated technologies has attracted the attention of researchers in several areas, including microcirculation. Microfluidic devices are expected to provide powerful tools not only to better understand the biophysical behavior of blood flow in microvessels, but also for disease diagnosis. Such microfluidic devices for biomedical applications must be compatible with state-of-the-art flow measuring techniques, such as confocal microparticle image velocimetry (PIV). This confocal system has the ability to not only quantify flow patterns inside microchannels with high spatial and temporal resolution, but can also be used to obtain velocity measurements for several optically sectioned images along the depth of the microchannel. In this study, we investigated the ability to obtain velocity measurements using physiological saline (PS) and in vitro blood in a rectangular polydimethysiloxane (PDMS) microchannel (300 microm wide, 45 microm deep) using a confocal micro-PIV system. Applying this combination, measurements of trace particles seeded in the flow were performed for both fluids at a constant flow rate (Re = 0.02). Velocity profiles were acquired by successive measurements at different depth positions to obtain three-dimensional (3-D) information on the behavior of both fluid flows. Generally, the velocity profiles were found to be markedly blunt in the central region, mainly due to the low aspect ratio (h/w = 0.15) of the rectangular microchannel. Predictions using a theoretical model for the rectangular microchannel corresponded quite well with the experimental micro-PIV results for the PS fluid. However, for the in vitro blood with 20% hematocrit, small fluctuations were found in the velocity profiles. The present study clearly shows that confocal micro-PIV can be effectively integrated with a PDMS microchannel and used to obtain blood velocity profiles along the full depth of the microchannel because of its unique 3-D optical sectioning ability

  8. The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

    International Nuclear Information System (INIS)

    Cornish, S.; Khachan, J.

    2016-01-01

    A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required. (paper)

  9. The Use of an Electron Microchannel as a Self-Extracting and Focusing Plasma Cathode Electron Gun

    Science.gov (United States)

    Cornish, S.; Khachan, J.

    2016-02-01

    A new and simple type of electron gun is presented. Unlike conventional electron guns, which require a heated filament or extractor, accelerator and focusing electrodes, this gun uses the collimated electron microchannels of an inertial electrostatic confinement (IEC) discharge to achieve the same outcome. A cylindrical cathode is placed coaxially within a cylindrical anode to create the discharge. Collimated beams of electrons and fast neutrals emerge along the axis of the cylindrical cathode. This geometry isolates one of the microchannels that emerge in a negatively biased IEC grid. The internal operating pressure range of the gun is 35-190 mTorr. A small aperture separates the gun from the main vacuum chamber in order to achieve a pressure differential. The chamber was operated at pressures of 4-12 mTorr. The measured current produced by the gun was 0.1-3 mA (0.2-14 mA corrected measurement) for discharge currents of 1-45 mA and discharge voltages of 0.5-12 kV. The collimated electron beam emerges from the aperture into the vacuum chamber. The performance of the gun is unaffected by the pressure differential between the vacuum chamber and the gun. This allows the aperture to be removed and the chamber pressure to be equal to the gun pressure if required.

  10. Development of Gas Electron Multiplier(GEM) for digital radiographic system

    International Nuclear Information System (INIS)

    Moon, B. S.; Chung, C. E.; Lee, J. W.

    2000-04-01

    Two computer programs SHOWFIELD and IMAGEQUAL have been developed. SHOWFIELD is used to draw electric field lines for GEM detectors and IMAGEQUAL is used to study the spatial resolution of x-ray images. Various simulation runs have been carried out using EGS4 to study the characteristics of electrons generated by micro-channel plates and Ar, Xe gases. A prototype GEM detector was developed through this project. The GEM detector is composed of a pair of GEM plates, a micro-channel plate, readout circuit in a gas filled chamber. GEM plate were made in CERN to meet KAERI's design specification and the micro-channel plates were purchased from Proxitronic company

  11. Optimization of porous microchannel heat exchanger

    Science.gov (United States)

    Kozhukhov, N. N.; Konovalov, D. A.

    2017-11-01

    The technical progress in information and communication sphere leads to a sharp increase in the use of radio electronic devices. Functioning of radio electronics is accompanied by release of thermal energy, which must be diverted from the heat-stressed element. Moreover, using of electronics at negative temperatures, on the contrary, requires supply of a certain amount of heat to start the system. There arises the task of creating a system that allows both to supply and to divert the necessary amount of thermal energy. The development of complex thermostabilization systems for radio electronic equipment is due to increasing the efficiency of each of its elements separately. For more efficient operation of a heat exchanger, which directly affects the temperature of the heat-stressed element, it is necessary to calculate the mode characteristics and to take into account the effect of its design parameters. The results of optimizing the microchannel heat exchanger are presented in the article. The target optimization functions are the mass, pressure drop and temperature. The parameters of optimization are the layout of porous fins, their geometric dimensions and coolant flow. For the given conditions, the optimum variant of porous microchannel heat exchanger is selected.

  12. Novel dense CO2 technique for beta-galactosidase immobilization in polystyrene microchannels.

    Science.gov (United States)

    Leclair Ellis, Jeffrey; Tomasko, David L; Dehghani, Fariba

    2008-03-01

    In this study we design new fabrication techniques and demonstrate the potential of using dense CO2 for facilitating crucial steps in the fabrication of polymeric lab-on-a-chip microdevices by embedding biomolecules at temperatures well below the polymer's glass transition temperature (T(g)). These new techniques are environmentally friendly and done without the use of a clean room. Carbon dioxide at 40 degrees C and between 4.48 and 6.89 MPa was used to immobilize the biologically active molecule, beta-galactosidase (beta-gal), on the surface of polystyrene microchannels. To our knowledge, this is the first time dense CO2 has been used to directly immobilize an enzyme in a microchannel. beta-gal activity was maintained and shown via a fluorescent reaction product, after enzyme immobilization and microchannel capping by the designed fabrication steps at 40 degrees C and pressures up to 6.89 MPa.

  13. Flow and Heat Transfer in Cooling Microchannels with Phase-Change

    Energy Technology Data Exchange (ETDEWEB)

    Peles, Y P; Yarin, L P; Hetsroni, G [Technion, Israel Institute of Technology, Haifa (Israel) Faculty of Engineering

    1998-05-19

    The subject of the present work is the parametrical investigation of hydrodynamic and thermal characteristics of laminar flow with phase-change in a heating microchannels. The study is based on the quasi-one-dimensional model of non-isothermal capillary flow. This model takes into account the evolution of flow, heating and evaporation of the liquid, as well as the influence of capillary, inertia, friction and gravity forces. The effect of various parameters (sizes of microchannel, initial temperature of cooling liquid, wall heat flux etc.) on hydrodynamic and thermal structures of the flow, the length of heating, evaporation and superheat regions is studied. Thc specific features of the phenomena is discussed.

  14. Flow and Heat Transfer in Cooling Microchannels with Phase-Change

    International Nuclear Information System (INIS)

    Peles, Y.P.; Yarin, L.P.; Hetsroni, G.

    1998-01-01

    The subject of the present work is the parametrical investigation of hydrodynamic and thermal characteristics of laminar flow with phase-change in a heating microchannels. The study is based on the quasi-one-dimensional model of non-isothermal capillary flow. This model takes into account the evolution of flow, heating and evaporation of the liquid, as well as the influence of capillary, inertia, friction and gravity forces. The effect of various parameters (sizes of microchannel, initial temperature of cooling liquid, wall heat flux etc.) on hydrodynamic and thermal structures of the flow, the length of heating, evaporation and superheat regions is studied. Thc specific features of the phenomena is discussed

  15. Optical image encryption using fresnel zone plate mask based on fast walsh hadamard transform

    Science.gov (United States)

    Khurana, Mehak; Singh, Hukum

    2018-05-01

    A new symmetric encryption technique using Fresnel Zone Plate (FZP) based on Fast Walsh Hadamard Transform (FWHT) is proposed for security enhancement. In this technique, bits of plain image is randomized by shuffling the bits randomly. The obtained scrambled image is then masked with FZP using symmetric encryption in FWHT domain to obtain final encrypted image. FWHT has been used in the cryptosystem so as to protect image data from the quantization error and for reconstructing the image perfectly. The FZP used in proposed scheme increases the key space and makes it robust to many traditional attacks. The effectiveness and robustness of the proposed cryptosystem has been analyzed on the basis of various parameters by simulating on MATLAB 8.1.0 (R2012b). The experimental results are provided to highlight suitability of the proposed cryptosystem and prove that the system is secure.

  16. Measuring the 3D motion of particles in microchannel acoustophoresis using astigmatism particle tracking velocimetry

    DEFF Research Database (Denmark)

    Augustsson, P.; Barnkob, Rune; Bruus, Henrik

    2012-01-01

    We introduce full three-dimensional tracking of particles in an acoustophoresis microchannel using Astigmatism Particle Tracking Velocimetry (APTV) [1]. For the first time the interaction between acoustic streaming and the primary acoustic radiation force in microchannel acoustophoresis are exami...... relative to the influence from the acoustic radiation force. The current study opens the route to optimized acoustophoretic system design and operation to enable manipulation of small biological components such as spores, bacteria and viruses.......We introduce full three-dimensional tracking of particles in an acoustophoresis microchannel using Astigmatism Particle Tracking Velocimetry (APTV) [1]. For the first time the interaction between acoustic streaming and the primary acoustic radiation force in microchannel acoustophoresis...... are examined in three dimensions. We have quantified the velocity of particles driven by the primary acoustic radiation force and acoustic streaming, respectively, using 0.5-μm and 5-μm particles. Increased ultrasound frequency and lowered viscosity of the medium reduced the influence of acoustic streaming...

  17. Continuous particle focusing in a waved microchannel using negative dc dielectrophoresis

    KAUST Repository

    Li, Ming

    2012-07-26

    We present a waved microchannel for continuous focusing of microparticles and cells using negative direct current (dc) dielectrophoresis. The waved channel is composed of consecutive s-shaped curved channels in series to generate an electric field gradient required for the dielectrophoretic effect. When particles move electrokinetically through the channel, the experienced negative dielectrophoretic forces alternate directions within two adjacent semicircular microchannels, leading to a focused continuous-flow stream along the channel centerline. Both the experimentally observed and numerically simulated results of the focusing performance are reported, which coincide acceptably in proportion to the specified dimensions (i.e. inlet and outlet of the waved channel). How the applied electric field, particle size and medium concentration affect the performance was studied by focusing polystyrene microparticles of varying sizes. As an application in the field of biology, the focusing of yeast cells in the waved mcirochannel was tested. This waved microchannel shows a great potential for microflow cytometry applications and is expected to be widely used before different processing steps in lab-on-A-chip devices with integrated functions. © 2012 IOP Publishing Ltd.

  18. Fabrication of rectangular cross-sectional microchannels on PMMA with a CO2 laser and underwater fabricated copper mask

    Science.gov (United States)

    Prakash, Shashi; Kumar, Subrata

    2017-09-01

    CO2 lasers are commonly used for fabricating polymer based microfluidic devices. Despite several key advantages like low cost, time effectiveness, easy to operate and no requirement of clean room facility, CO2 lasers suffer from few disadvantages like thermal bulging, improper dimensional control, difficulty to produce microchannels of other than Gaussian cross sectional shapes and inclined surface walls. Many microfluidic devices require square or rectangular cross-sections which are difficult to produce using normal CO2 laser procedures. In this work, a thin copper sheet of 40 μm was used as a mask above the PMMA (Polymethyl-methacrylate) substrate while fabricating the microchannels utilizing the raster scanning feature of the CO2 lasers. Microchannels with different width dimensions were fabricated utilizing a CO2 laser in with mask and without-mask conditions. A comparison of both the fabricating process has been made. It was found that microchannels with U shape cross section and rectangular cross-section can efficiently be produced using the with mask technique. In addition to this, this technique can provide perfect dimensional control and better surface quality of the microchannel walls. Such a microchannel fabrication process do not require any post-processing. The fabrication of mask using a nanosecond fiber laser has been discussed in details. An underwater laser fabrication method was adopted to overcome heat related defects in mask preparation. Overall, the technique was found to be easy to adopt and significant improvements were observed in microchannel fabrication.

  19. Non-Photolithographic Manufacturing Processes for Micro-Channels Functioned by Micro-Contact-Printed SAMs

    Science.gov (United States)

    Saigusa, Hiroki; Suga, Yasuo; Miki, Norihisa

    In this paper we propose non-photolithographic fabrication processes of micro-fluid channels with patterned SAMs (Self-Assembled-Monolayers). SAMs with a thiol group are micro-contact printed on a patterned Au/Ti layer, which is vapor-deposited through a shadow mask. Ti is an adhesion layer. Subsequently, the micro-channels are formed by bonding surface-activated PDMS onto the silicon substrate via a silanol group, producing a SAMs-functioned bottom wall of the micro-channel. No photolithographic processes are necessary and thus, the proposed processes are very simple, quick and low cost. The micro-reactors can have various functions associated with the micro-contact-printed SAMs. We demonstrate successful manufacturing of micro-reactors with two types of SAMs. The micro-reactor with patterned AUT (11-amino-1-undecanethiol) successfully trapped nano-particles with a carboxylic acid group, indicating that micro-contact-printed SAMs remain active after the manufacturing processes of the micro-reactor. AUT -functioned micro-channels are applicable to bioassay and to immobilize proteins for DNA arrays. ODT (1-octadecanethiol) makes surfaces hydrophobic with the methyl terminal group. When water was introduced into the micro-reactor with ODT-patterned surfaces, water droplets remained only in the hydrophilic areas where ODT was not patterned. ODT -functioned micro-channels are applicable to fluid handling.

  20. Application of two-phase flow for cooling of hybrid microchannel PV cells: A comparative study

    International Nuclear Information System (INIS)

    Valeh-e-Sheyda, Peyvand; Rahimi, Masoud; Karimi, Ebrahim; Asadi, Masomeh

    2013-01-01

    Highlights: ► Showing cooling potential of gas–liquid two-phase flow in microchannels for PV cell. ► Introducing the concept of using slug flow in microchannels for cooling of PV cells. ► In single-phase flow, increasing the liquid flow rate enhances the PV power. ► Showing that in two-phase flow the output power related the fluid flow regime. ► By coupling PV and microchannel an increase up to 38% in output power was observed. - Abstract: This paper reports the experimental data from performance of two-phase flows in a small hybrid microchannel solar cell. Using air and water as two-phase fluid, the experiments were conducted at indoor condition in an array of rectangular microchannels with a hydraulic diameter of 0.667 mm. The gas superficial velocity ranges were between 0 and 3.27 m s −1 while liquid flow rate was 0.04 m s −1 . The performance analysis of the PV cell at slug and transitional slug/annular flow regimes are the focus of this study. The influence of two-phase working fluid on PV cell cooling was compared with single-phase. In addition, the great potential of slug flow for heat removal enhancement in PV/T panel was investigated. The obtained data showed the proposed hybrid system could substantially increases the output power of PV solar cells

  1. Experimental investigation of Cu-based, double-layered, microchannel heat exchangers

    International Nuclear Information System (INIS)

    Lu, Bin; Meng, W J; Mei, Fanghua

    2013-01-01

    Cu-based, single- and double-layered, microchannel heat exchangers (MHEs) were fabricated and assembled. Comparative measurements on liquid flow characteristics and heat transfer performance were conducted on these devices. Results were compared at the individual microchannel level as well as at the device level. The present results demonstrate that double-layered MHEs exhibit similar heat transfer performance while suffering a much lower pressure drop penalty compared to single-layered MHEs. Another Cu-based, double-layered, liquid–liquid counter-flow MHE was fabricated, assembled and tested. Results show that a low-volume, multilayered, high-performance, liquid-to-liquid MHE is achievable following the manufacturing protocols of the present double-layered, liquid–liquid counter-flow MHE. (paper)

  2. Development of a Microchannel In Situ Propellant Production System

    Energy Technology Data Exchange (ETDEWEB)

    Brooks, Kriston P.; Rassat, Scot D.; TeGrotenhuis, Ward E.

    2005-09-01

    An in situ propellant production (ISPP) plant on future Mars robotic missions can produce oxygen (O2) and methane (CH4) that can be used for propellant for the return voyage. By producing propellants from Mars atmospheric carbon dioxide (CO2) and hydrogen (H2) brought from Earth, the initial mass launched in low Earth orbit can be reduced by 20% to 45%, as compared to carrying all of the propellant for a round-trip mission to the Mars surface from Earth. Pacific Northwest National Laboratory used microchannel architecture to develop a Mars-based In Situ Propellant Production (ISPP) system. This three year research and development effort focused on process intensification and system miniaturization of three primary subsystems: a thermochemical compressor, catalytic reactors, and components for separating gas phases from liquid phases. These systems were designed based on a robotic direct return mission scenario, but can be scaled up to human flight missions by simply numbering up the microchannel devices. The thermochemical compression was developed both using absorption and adsorption. A multichannel adsorption system was designed to meet the full-scale CO2 collection requirements using temperature swing adsorption. Each stage is designed to achieve a 10x compression of CO2. A compression ratio to collect Martian atmospheric CO2 at ~0.8 kPa and compress it to at least 100 kPa can be achieved with two adsorption stages in series. A compressor stage incorporates eight thermally coupled adsorption cells at various stages in the adsorption/desorption cycle to maximize the recuperation of thermal energy and provide a nearly continuous flow of CO2 to the downstream reactors. The thermochemically compressed CO2 is then mixed with hydrogen gas and fed to two reactors: a Sabatier Reaction unit and a Reverse Water/Gas Shift unit. The microchannel architecture allows better heat control than is possible in an adiabatic system, resulting in significantly higher conversion. The

  3. Applications of 'edge-on' illuminated porous plate detectors for diagnostic X-ray imaging

    CERN Document Server

    Shikhaliev, P M

    2002-01-01

    Scanning X-ray imaging systems for non-invasive diagnostics have several advantages over conventional imaging systems using area detectors. They significantly reduce the detected scatter radiation, cover large areas and potentially provide high spatial resolution. Applications of one-dimensional gaseous detectors and 'edge-on' illuminated silicon strip detectors for scanning imaging systems are currently under intensive investigation. The purpose of this work is to investigate 'edge-on' illuminated Porous Plate (PP) detectors for applications in diagnostic X-ray imaging. MicroChannel Plate (MCP), which is a common type of PP, has previously been investigated as a detector in surface-on illumination mode for medical X-ray imaging. However, its detection efficiency was too low for medical imaging applications. In the present study, the PP are used in the 'edge-on' illumination mode. Furthermore, the structural parameters of different PP types are optimized to improve the detection efficiency in the diagnostic X...

  4. Direct simulation Monte Carlo method for gas flows in micro-channels with bends with added curvature

    Directory of Open Access Journals (Sweden)

    Tisovský Tomáš

    2017-01-01

    Full Text Available Gas flows in micro-channels are simulated using an open source Direct Simulation Monte Carlo (DSMC code dsmcFOAM for general application to rarefied gas flow written within the framework of the open source C++ toolbox called OpenFOAM. Aim of this paper is to investigate the flow in micro-channel with bend with added curvature. Results are compared with flows in channel without added curvature and equivalent straight channel. Effects of micro-channel bend was already thoroughly investigated by White et al. Geometry proposed by White is also used here for refference.

  5. Microchannel Reactors for ISRU Applications Using Nanofabricated Catalysts, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Makel Engineering, Inc. (MEI) and USRA propose to develop microchannel reactors for In-Situ Resources Utilization (ISRU) using nanofabricated catalysts. The proposed...

  6. A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

    Science.gov (United States)

    Qiu, X.; Cherief, W.; Colombet, D.; Ayela, F.

    2017-04-01

    We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops.

  7. A simple process to achieve microchannels geometries able to produce hydrodynamic cavitation

    International Nuclear Information System (INIS)

    Qiu, X; Cherief, W; Colombet, D; Ayela, F

    2017-01-01

    We present a simple process to perform microchannels in which cavitating two phase flows are easily producible. Up to now, hydrodynamic cavitation ‘on a chip’ was reached with small flow rates inside microchannels whose micromachining had involved a deep reactive ion etching (D-RIE). The process we present here does not require a D-RIE reactor, as it is only funded on a wet etching of silicon. It leads to a so-called microstep profile, and large cavitating flow rates become possible together with moderate pressure drops. (technical note)

  8. CFD Analysis for Optimum Thermal Design of Carbon Nanotube Based Micro-Channel Heatsink

    Directory of Open Access Journals (Sweden)

    M. Mahbub

    2011-10-01

    Full Text Available Carbon nanotube (CNT is considered as an ideal material for thermal management in electronic packaging because of its extraordinary high thermal conductivity. Fabricated onto a silicon substrate to form micro-channels, the CNT based cooling fins show high heat dissipation efficiency. A series of 2D and 3D CFD simulations have been carried out for CNT based micro-channel cooling architectures based on one and two dimensional fin array in this paper using COMSOL 4.0a software. Micro-channels are generally regarded as an effective method for the heat transfer in electronic products. The influence of various fluids, micro-fin structures, fluid velocity and heating powers on cooling effects have been simulated and compared in this study. Steady-state thermal stress analyses for the forced convection heat transfer are also performed to determine maximum allowable stress and deflections for the different types of cooling assembly.

  9. Experimental and numerical investigations on spray structure under the effect of cavitation phenomenon in a microchannel

    International Nuclear Information System (INIS)

    Ghorbani, Morteza; Sadaghiani, Abdolali Khalili; Yidiz, Mehmet; Kosar, Ali

    2017-01-01

    In this study, the effect of upstream pressure on cavitation flows inside a microchannel with an inner diameter of 152 μm and resulting spray structure were experimentally and numerically investigated. The effects of bubble number density on two-phase flow hydrodynamics were studied using the numerical approach, where transient model was utilized to obtain the changes in vapor quality inside the microchannel and velocity field near the inlet and outlet of the nozzle. Spray visualization was carried out at a distance of 4.5 mm from the tip of the microchannel using the high speed visualization system. The experimental results showed that the spray cone angle increased with upstream pressure, and beyond the upstream pressure of 50 bar, the liquid jet flow changed to the cloudy spray flow. The bubble collapse was recorded at upstream pressures of 100 and 120 bar, where the cavitation bubbles extended to the outlet of the microchannel, and their collapse took place around the spray

  10. Flow boiling in expanding microchannels

    CERN Document Server

    Alam, Tamanna

    2017-01-01

    This Brief presents an up to date summary of details of the flow boiling heat transfer, pressure drop and instability characteristics; two phase flow patterns of expanding microchannels. Results obtained from the different expanding microscale geometries are presented for comparison and addition to that, comparison with literatures is also performed. Finally, parametric studies are performed and presented in the brief. The findings from this study could help in understanding the complex microscale flow boiling behavior and aid in the design and implementation of reliable compact heat sinks for practical applications.

  11. Scintillating plate calorimeter optical design

    International Nuclear Information System (INIS)

    McNeil, R.; Fazely, A.; Gunasingha, R.; Imlay, R.; Lim, J.

    1990-01-01

    A major technical challenge facing the builder of a general purpose detector for the SSC is to achieve an optimum design for the calorimeter. Because of its fast response and good energy resolution, scintillating plate sampling calorimeters should be considered as a possible technology option. The work of the Scintillating Plate Calorimeter Collaboration is focused on compensating plate calorimeters. Based on experimental and simulation studies, it is expected that a sampling calorimeter with alternating layers of high-Z absorber (Pb, W, DU, etc.) and plastic scintillator can be made compensating (e/h = 1.00) by suitable choice of the ratio of absorber/scintillator thickness. Two conceptual designs have been pursued by this subsystem collaboration. One is based on lead as the absorber, with read/out of the scintillator plates via wavelength shifter fibers. The other design is based on depleted uranium as the absorber with wavelength shifter (WLS) plate readout. Progress on designs for the optical readout of a compensating scintillator plate calorimeter are presented. These designs include readout of the scintillator plates via wavelength shifter plates or fiber readout. Results from radiation damage studies of the optical components are presented

  12. Extension - Upgrading Methane Using Ultra-Fast Thermal Swing Adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Anna Lee Tonkovich

    2008-08-11

    The need for cost effective technologies for upgrading coal mine methane to pipeline quality natural gas is becoming ever greater. The current work presents and investigates a new approach to reduce the impact of the most costly step in the conventional technology, nitrogen rejection. The proposed approach is based on the Velocys microchannel platform, which is being developed to commercialize compact and cost efficient chemical processing technology. For this separation, ultra fast thermal swing sorption is enabled by the very high rates of heat and mass transfer inherent in microchannel processing. In a first phase of the project solid adsorbents were explored. Feasibility of ultrafast thermal swing was demonstrated but the available adsorbents had insufficient differential methane capacity to achieve the required commercial economics. In a second phase, ionic liquids were adopted as absorbents of choice, and experimental work and economic analyses, performed to gauge their potential, showed promise for this novel alternative. Final conclusions suggest that a combination of a required cost target for ionic liquids or a methane capacity increase or a combination of both is required for commercialization.

  13. Electro-osmotically actuated oscillatory flow of a physiological fluid on a porous microchannel subject to an external AC electric field having dissimilar frequencies

    Science.gov (United States)

    Misra, Jagadis C.; Chandra, Sukumar

    2014-04-01

    Electro-osmotic flow of a physiological fluid with prominent micropolar characteristics, flowing over a microchannel has been analyzed for a situation, where the system is subject to the action of an external AC electric field. In order to account for the rotation of the micro-particles suspended in the physiological fluid, the fluid has been treated as a micropolar fluid. The microchannel is considered to be bounded by two porous plates executing oscillatory motion. Such motion of the plates will normally induce oscillatory flow of the fluid. The governing equations of the fluid include a second-order partial differential equation depicting Gauss's law of electrical charge distributions and two other partial differential equations of second order that arise out of the laws of conservation of linear and angular momenta. These equations have been solved under the sole influence of electrokinetic forces, by using appropriate boundary conditions. This enabled us to determine explicit analytical expressions for the electro-osmotic velocity of the fluid and the microrotation of the suspended micro-particles. These expressions have been used to obtain numerical estimates of important physical variables associated with the oscillatory electro-osmotic flow of a blood sample inside a micro-bio-fluidic device. The numerical results presented in graphical form clearly indicate that the formation of an electrical double layer near the vicinity of the wall causes linear momentum to reduce. In contrast, the angular momentum increases with the enhancement of microrotation of the suspended microparticles. The study will find important applications in the validation of results of further experimental and numerical models pertaining to flow in micro-bio-fluidic devices. It will also be useful in the improvement of the design and construction of various micro-bio-fluidic devices.

  14. EXPERIMENTAL PERFORMANCE OF R134a AND R152a USING MICROCHANNEL CONDENSER

    OpenAIRE

    Bhatkar, V. W.

    2018-01-01

    An experimental performance study on vapour compression refrigeration system with R134a and drop in substitute R152a with aluminium microchannel condenser was carried out for condensation temperature of 48°C while evaporation temperature varied from -10 to 15°C. Refrigerant charge of R152a was reduced by 40% over R134a with the microchannel condenser. Performance parameters like work input to the compressor, coefficient of performance, refrigerating capacity, condenser capacity and the produc...

  15. High speed gated x-ray imagers

    International Nuclear Information System (INIS)

    Kilkenny, J.D.; Bell, P.; Hanks, R.; Power, G.; Turner, R.E.; Wiedwald, J.

    1988-01-01

    Single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described. These systems are based on the gating of microchannel plates in a stripline configuration. The gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec. Results from single and four frame x-ray cameras used on Nova are described. 8 refs., 9 figs

  16. A fast and sensitive method for evaluating nuclides migration characteristics in rock medium by using micro-channel reactor concept

    Science.gov (United States)

    Okuyama, Keita; Sasahira, Akira; Noshita, Kenji; Yoshida, Takuma; Kato, Kazuyuki; Nagasaki, Shinya; Ohe, Toshiaki

    Experimental effort to evaluate the barrier performance of geologic disposal requires relatively long testing periods and chemically stable conditions. We have developed a new technique, the micro mock-up method, to present a fast and sensitive method to measure both nuclide diffusivity and sorption coefficient within a day to overcome such disadvantage of the conventional method. In this method, a Teflon plate having a micro channel (10-200 μm depth, 2, 4 mm width) is placed just beneath the rock sample plate, radionuclide solution is injected into the channel with constant rate. The breakthrough curve is being measured until a steady state. The outlet flux in the steady state however does not meet the inlet flux because of the matrix diffusion into the rock body. This inlet-outlet difference is simply related to the effective diffusion coefficient ( De) and the distribution coefficient ( Kd) of rock sample. Then, we adopt a fitting procedure to speculate Kd and De values by comparing the observation to the theoretical curve of the two-dimensional diffusion-advection equation. In the present study, we measured De of 3H by using both the micro mock-up method and the conventional through-diffusion method for comparison. The obtained values of De by two different ways for granite sample (Inada area of Japan) were identical: 1.0 × 10 -11 and 9.0 × 10 -12 m 2/s but the testing period was much different: 10 h and 3 days, respectively. We also measured the breakthrough curve of 85Sr and the resulting Kd and De agreed well to the previous study obtained by the batch sorption experiments with crushed samples. The experimental evidence and the above advantages reveal that the micro mock-up method based on the microreactor concept is powerful and much advantageous when compared to the conventional method.

  17. Asymmetrical Supercapacitor Composed of Thin Co(OH)2 Nanoflakes on Three-Dimensional Ni/Si Microchannel Plates with Superior Electrochemical Performance

    International Nuclear Information System (INIS)

    Li, Mai; Xu, Shaohui; Cherry, Christopher; Zhu, Yiping; Huang, Rong; Qi, Ruijuan; Yang, Pingxiong; Wang, Lianwei; Chu, Paul K.

    2014-01-01

    Graphical abstract: The paper studied the formation mechanism and growth process of nanostructured Co(OH) 2 . The first step of Co(OH) 2 growth involves nucleation of nanorods and tiny nanowires and the second is interconnection growth based on those nanostructures. By using the Co(OH) 2 /Ni/Si-MCPs electrode as the positive electrode and CNTs/nickel foam (CNTs/NF) as the negative electrode, the device assembled with CR2025 batteries exhibits high energy density (38.39 Wh kg −1 ), high power density (5400 W kg −1 at 9.67 Wh kg −1 ), and stable power characteristic (2000 times with 80.63% retention). After charging each supercapacitor for 10 s, the device can power a 5 mm diameter light-emitting diode (LED) with different colors efficiently, for example, a blue LED for 20 min. - Abstract: Nanoscale cobalt hydroxide (Co(OH) 2 ) particles are fabricated by electrodeposition on three-dimensional nickel/silicon microchannel plates (Ni/Si-MCPs) as the active electrode materials on the surface and sidewall of the Ni/Si-MCPs for miniature supercapacitors. The relationship among the electrodeposition time, morphology, formation mechanism of Co(OH) 2 nanostructure, and capacitor performance is studied. Using an optimal electrodeposition time of 6 min, the Co(OH) 2 supercapacitor has a capacitance of 697.56 F g −1 (5.72 F cm −2 ) at 2 mA cm −2 and the retention ratio is 91.20% after 2500 cycles. The large areal capacitance and excellent rate capability can be attributed to the unique 3D ordered porous architecture which facilitates electron and ion transport, enlarges the liquid-solid interfacial area, and enhances the utilization efficiency of the active materials. Meanwhile, the weight and size of the device are reduced. By using the Co(OH) 2 /Ni/Si-MCPs electrode as the positive electrode and CNTs/nickel foam (CNTs/NF) as the negative electrode, the device assembled with CR2025 batteries exhibits high energy density (38.39 Wh kg −1 ), high power density (5400

  18. Self-separation of blood plasma from whole blood during the capillary flow in microchannel

    Science.gov (United States)

    Nunna, Bharath Babu; Zhuang, Shiqiang; Lee, Eon Soo

    2017-11-01

    Self-separation of blood plasma from whole blood in microchannels is of great importance due to the enormous range of applications in healthcare and diagnostics. Blood is a multiphase complex fluid, composed of cells suspended in blood plasma. RBCs are the suspended particles whose shape changes during the flow of blood. The primary constituents of blood are erythrocytes or red blood cells (RBCs), leukocytes or white blood cells (WBCs), thrombocytes or platelets and blood plasma. The existence of RBCs in blood makes the blood a non-Newtonian fluid. The current study of separation of blood plasma from whole blood during self-driven flows in a single microchannel without bifurcation, by enhancing the capillary effects. The change in the capillary effect results in a change in contact angle which directly influences the capillary flow. The flow velocity directly influences the net force acting on the RBCs and influence the separation process. The experiments are performed on the PDMS microchannels with different contact angles by altering the surface characteristics using plasma treatment. The change in the separation length is studied during the capillary flow of blood in microchannel. Bharath Babu Nunna is a researcher in mechanical engineering and implementing the novel and innovative technologies in the biomedical devices to enhance the sensitivity of the disease diagnosis.

  19. Magnetic Control of Fe3O4 Nanomaterial for Fat Ablation in Microchannel

    Directory of Open Access Journals (Sweden)

    Ming Chang

    2015-11-01

    Full Text Available In this study, surface modification of iron (II, III oxide Fe3O4 nanoparticles by oleic acid (OA coating is investigated for the microablation of fat in a microchannel. The nanoparticles are synthesized by the co-precipitation method and then dispersed in organic solvent prior to mixing with the OA. The magnetization, agglomeration, and particle size distribution properties of the OA-coated Fe3O4 nanoparticles are characterized. The surface modification of the Fe3O4 nanoparticles reveals that upon injection into a microchannel, the lipophilicity of the OA coating influences the movement of the nanoparticles across an oil-phase barrier. The motion of the nanoparticles is controlled using an AC magnetic field to induce magnetic torque and a static gradient field to control linear translation. The fat microablation process in a microchannel is demonstrated using an oscillating driving field of less than 1200 Am−1.

  20. Data processing correction of the irising effect of a fast-gating intensified charge-coupled device on laser-pulse-excited luminescence spectra.

    Science.gov (United States)

    Ondic, L; Dohnalová, K; Pelant, I; Zídek, K; de Boer, W D A M

    2010-06-01

    Intensified charge-coupled devices (ICCDs) comprise the advantages of both fast gating detectors and spectrally broad CCDs into one device that enables temporally and spectrally resolved measurements with a few nanosecond resolution. Gating of the measured signal occurs in the image intensifier tube, where a high voltage is applied between the detector photocathode and a microchannel plate electron multiplier. An issue arises in time-resolved luminescence spectroscopy when signal onset characterization is required. In this case, the transient gate closing process that causes the detected signal always arises in the middle of the ICCD chip regardless of the spectral detection window--the so-called irising effect. We demonstrate that in case when the detection gate width is comparable to the opening/closing time and the gate is pretriggered with respect to the signal onset, the irising effect causes the obtained data to be strongly distorted. At the same time, we propose a software procedure that leads to the spectral correction of the irising effect and demonstrate its validity on the distorted data.

  1. New Configurations of Micro Plate-Fin Heat Sink to Reduce Coolant Pumping Power

    DEFF Research Database (Denmark)

    Kolaei, Alireza Rezania; Rosendahl, Lasse

    2012-01-01

    the optimum heat sink configuration. The particular focus of this study is to reduce the coolant mass flow rate by considering the thermal resistances of the heat sinks and, thereby, to reduce the coolant pumping power in the system. The threedimensional governing equations for the fluid flow and the heat......The thermal resistance of heat exchangers has a strong influence on the electric power produced by a thermoelectric generator (TEG). In this work, a real TEG device is applied to three configurations of micro plate-fin heat sink. The distance between certain microchannels is varied to find...... heat sink configurations reduces the coolant pumping power in the system....

  2. Measuring the local pressure amplitude in microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2010-01-01

    /glass microchannels. The system is actuated by a PZT piezo transducer attached beneath the chip and driven by an applied ac voltage near its eigenfrequency of 2 MHz. For a given frequency a number of particle tracks are recorded by a CCD camera and fitted to a theoretical expression for the acoustophoretic motion...

  3. Lattice Boltzmann Simulation of the Hydrodynamic Entrance Region of Rectangular Microchannels in the Slip Regime

    Directory of Open Access Journals (Sweden)

    Niya Ma

    2018-02-01

    Full Text Available Developing a three-dimensional laminar flow in the entrance region of rectangular microchannels has been investigated in this paper. When the hydrodynamic development length is the same magnitude as the microchannel length, entrance effects have to be taken into account, especially in relatively short ducts. Simultaneously, there are a variety of non-continuum or rarefaction effects, such as velocity slip and temperature jump. The available data in the literature appearing on this issue is quite limited, the available study is the semi-theoretical approximate model to predict pressure drop of developing slip flow in rectangular microchannels with different aspect ratios. In this paper, we apply the lattice Boltzmann equation method (LBE to investigate the developing slip flow through a rectangular microchannel. The effects of the Reynolds number (1 < Re < 1000, channel aspect ratio (0 < ε < 1, and Knudsen number (0.001 < Kn < 0.1 on the dimensionless hydrodynamic entrance length, and the apparent friction factor, and Reynolds number product, are examined in detail. The numerical solution of LBM can recover excellent agreement with the available data in the literature, which proves its accuracy in capturing fundamental fluid characteristics in the slip-flow regime.

  4. Numerical study on fabricating rectangle microchannel in microfluidic chips by glass molding process

    Science.gov (United States)

    Wang, Tao; Chen, Jing; Zhou, Tianfeng

    2017-09-01

    This paper studied the glass molding process (GMP) for fabricating a typical microstructure of glass microfluidic chips, i. e., rectangle microchannel, on soda-lime glass by finite element method. More than 100 models were established on the platform of Abaqus/Standard. The influence of parameters, i. e., temperature, aspect ratio, side wall angle and friction coefficient on deformation were studied, and the predicted morphology of the molded microchannel were presented as well. The research could provide fundamental experience for optimizing GMP process in the future.

  5. An adhesive bonding method with microfabricating micro pillars to prevent clogging in a microchannel

    International Nuclear Information System (INIS)

    Chen, Pin-Chuan; Liu, Yu-Min; Chou, Huang-Chieh

    2016-01-01

    Thermoplastics are widely used in the fabrication of microfluidic chips, due to their low cost, flexibility in manufacturing, and applicability in large-scale production. This paper presents a novel bonding method for the assembly of thermoplastic microfluidic chips, with the aim of preventing the flow of UV adhesive into microchannels during the bonding process. The proposed bonding methodology depends primarily on controlling the thickness of the UV adhesive, which is achieved by using spin-coating for the uniform UV adhesive in conjunction with the microfabrication of short pillars for keeping a uniform gap between the two bonded surfaces. In this study, two devices with serpentine microchannels (cross-sectional area of 500 μm  ×  500 μm and 200 μm  ×  200 μm) were fabricated on PMMA substrates using a micromilling machine, whereupon a hydrophobic coating was applied to the walls of 200 μm  ×  200 μm microchannels in order to prevent clogging, which might otherwise be caused by the seepage of UV adhesive into the channels. A variety of experiments were used to characterize the quality of bonding, the results of which reveal the following: (1) no leakage was observed in either of the microfluidic chips; (2) the hydrophobic coating proved highly effective in preventing the flow of UV adhesive into the smaller microchannels; (3) the average amount of clogging inside 500 μm  ×  500 μm microchannels was 1.13% with standard deviation of 0.55%, while the average amount of clogging inside 200 μm  ×  200 μm microchannels was 1.65% with standard deviation of 0.92%; (4) the average thickness of the UV adhesive in a 500 μm  ×  500 μm microfluidic chip was 32 μm with standard deviation of 2 μm, whereas the average thickness of the UV adhesive in a 200 μm  ×  200 μm microfluidic chip was 31 μm with standard deviation of 1.2 μm; (5) the two chips possess sufficient bonding strength to withstand

  6. High power vertical stacked and horizontal arrayed diode laser bar development based on insulation micro-channel cooling (IMCC) and hard solder bonding technology

    Science.gov (United States)

    Wang, Boxue; Jia, Yangtao; Zhang, Haoyu; Jia, Shiyin; Liu, Jindou; Wang, Weifeng; Liu, Xingsheng

    2018-02-01

    An insulation micro-channel cooling (IMCC) has been developed for packaging high power bar-based vertical stack and horizontal array diode lasers, which eliminates many issues caused in its congener packaged by commercial copper formed micro-channel cooler(MCC), such as coefficient of thermal expansion (CTE) mismatch between cooler and diode laser bar, high coolant quality requirement (DI water) and channel corrosion and electro-corrosion induced by DI water if the DI-water quality is not well maintained The IMCC cooler separates water flow route and electrical route, which allows tap-water as coolant without electro-corrosion and therefore prolongs cooler lifetime dramatically and escalated the reliability of these diode lasers. The thickness of ceramic and copper in an IMCC cooler is well designed to minimize the CTE mismatch between laser bar and cooler, consequently, a very low "SMILE" of the laser bar can be achieved for small fast axis divergence after collimation. In additional, gold-tin hard solder bonding technology was also developed to minimize the risk of solder electromigration at high current density and thermal fatigue under hard-pulse operation mode. Testing results of IMCC packaged diode lasers are presented in this report.

  7. Base-plate effects on pipe-support stiffness

    International Nuclear Information System (INIS)

    Winkel, B.V.; LaSalle, F.R.

    1981-01-01

    Present nuclear power plant design methods require that pipe support spring rates be considered in the seismic design of piping systems. Base plate flexibility can have a significant effect on the spring rates of these support structures. This paper describes the field inspection, test, and analytical techniques used to identify and correct excessively flexible base plates on the Fast Flux Test Facility pipe support structures

  8. Two-phase pressure drop and flow visualization of FC-72 in a silicon microchannel heat sink

    International Nuclear Information System (INIS)

    Megahed, Ayman; Hassan, Ibrahim

    2009-01-01

    The rapid development of two-phase microfluidic devices has triggered the demand for a detailed understanding of the flow characteristics inside microchannel heat sinks to advance the cooling process of micro-electronics. The present study focuses on the experimental investigation of pressure drop characteristics and flow visualization of a two-phase flow in a silicon microchannel heat sink. The microchannel heat sink consists of a rectangular silicon chip in which 45 rectangular microchannels were chemically etched with a depth of 276 μm, width of 225 μm, and a length of 16 mm. Experiments are carried out for mass fluxes ranging from 341 to 531 kg/m 2 s and heat fluxes from 60.4 to 130.6 kW/m 2 using FC-72 as the working fluid. Bubble growth and flow regimes are observed using high speed visualization. Three major flow regimes are identified: bubbly, slug, and annular. The frictional two-phase pressure drop increases with exit quality for a constant mass flux. An assessment of various pressure drop correlations reported in the literature is conducted for validation. A new general correlation is developed to predict the two-phase pressure drop in microchannel heat sinks for five different refrigerants. The experimental pressure drops for laminar-liquid laminar-vapor and laminar-liquid turbulent-vapor flow conditions are predicted by the new correlation with mean absolute errors of 10.4% and 14.5%, respectively.

  9. Effect of junction configurations on microdroplet formation in a T-junction microchannel

    Science.gov (United States)

    Lih, F. L.; Miao, J. M.

    2015-03-01

    This study investigates the dynamic formation process of water microdroplets in a silicon oil flow in a T-junction microchannel. Segmented water microdroplets are formed at the junction when the water flow is perpendicularly injected into the silicon oil flow in a straight rectangular microchannel. This study further presents the effects of the water flow inlet geometry on hydrodynamic characteristics of water microdroplet formation. A numerical multiphase volume of fluid (VOF) scheme is coupled to solve the unsteady three-dimensional laminar Navier-Stokes equations to depict the droplet formation phenomena at the junction. Predicted results on the length and generated frequency of the microdroplets agree well with experimental results in a T-junction microchannel with straight and flat inlets (the base model) for both fluid flows. Empirical correlations are reported between the volumetric flow ratio and the dimensionless microdroplet length or dimensionless frequency of droplet generation at a fixed capillary number of 4.7 · 10-3. The results of this study indicate a reduction in the droplet length of approximately 21% if the straight inlet for the water flow is modified to a downstream sudden contraction inlet for the water flow.

  10. The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

    Science.gov (United States)

    Wang, H. L.; Han, W.; Xu, M.

    2011-12-01

    Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

  11. Entropy generation of nanofluid flow in a microchannel heat sink

    Science.gov (United States)

    Manay, Eyuphan; Akyürek, Eda Feyza; Sahin, Bayram

    2018-06-01

    Present study aims to investigate the effects of the presence of nano sized TiO2 particles in the base fluid on entropy generation rate in a microchannel heat sink. Pure water was chosen as base fluid, and TiO2 particles were suspended into the pure water in five different particle volume fractions of 0.25%, 0.5%, 1.0%, 1.5% and 2.0%. Under laminar, steady state flow and constant heat flux boundary conditions, thermal, frictional, total entropy generation rates and entropy generation number ratios of nanofluids were experimentally analyzed in microchannel flow for different channel heights of 200 μm, 300 μm, 400 μm and 500 μm. It was observed that frictional and total entropy generation rates increased as thermal entropy generation rate were decreasing with an increase in particle volume fraction. In microchannel flows, thermal entropy generation could be neglected due to its too low rate smaller than 1.10e-07 in total entropy generation. Higher channel heights caused higher thermal entropy generation rates, and increasing channel height yielded an increase from 30% to 52% in thermal entropy generation. When channel height decreased, an increase of 66%-98% in frictional entropy generation was obtained. Adding TiO2 nanoparticles into the base fluid caused thermal entropy generation to decrease about 1.8%-32.4%, frictional entropy generation to increase about 3.3%-21.6%.

  12. Experimental study on frosting control of mobile air conditioning system with microchannel evaporator

    International Nuclear Information System (INIS)

    Qu Xiaohua; Shi Junye; Qi Zhaogang; Chen Jiangping

    2011-01-01

    In this paper, a newly developed frost control system is proposed. System bench tests and vehicle test in wind tunnel have been carried out to explore the anti-frosting performance of automotive air conditioning system with microchannel evaporator. The experimental results are compared with the baseline conventional laminated evaporator system. The test results show that the installation position of temperature sensor can dramatically affect the anti-frosting performance. The clutch switching on/off temperature range of the microchannel evaporator is also experimentally studied. The test results show that, with a proper installation position and on/off temperature range, the system COP can be improved, and meanwhile the panel vents' air off temperature can be reduced, and temperature swing can be reduced. - Highlights: → The frost control systems were tested with microchannel and laminated evaporators separately. → The installation position of temperature sensor affects the anti-frosting performance. → Temperature control range affects the anti-frosting performance. → The panel vents' air off temperature and swing can be reduced by proper control parameters. → The system COP can be improved by proper control parameters.

  13. Effect of patterned micro-magnets on superparamagnetic beads in microchannels

    International Nuclear Information System (INIS)

    Guo, S S; Deng, Y L; Zhao, L B; Zhao, X-Z; Chan, H L W

    2008-01-01

    The trapping response of patterned micro-magnets (PMMs) was studied based on the parameters affecting superparamagnetic beads in microfluidic channels. Using replica moulding and electroplating technologies, the PMMs were fabricated on the microchannel bottom, which generated sufficient magnetic forces to bias the moments of magnetic particles in a flowing stream. A simplified physical principle was used to analyse the relative velocity of the magnetic particle in the confined space of a microchannel. The results revealed that the magnetic force contributed to the fluidic flow rate as well as to the hydrodynamic drag force. The relative velocity of magnetic particles was dependent on the frequency under an external magnetic field driven by an alternate current (ac) source. It showed that the magnetic gradient induced hysteresis characteristics of the transmission spectrum, associated with the interaction of superparamagnetic beads and magnetic field

  14. The flow field around a micropillar confined in a microchannel

    International Nuclear Information System (INIS)

    Jung, Junkyu; Kuo, C.-J.; Peles, Yoav; Amitay, Michael

    2012-01-01

    The flow field over a low aspect ratio (AR) circular pillar (L/D = 1.5) in a microchannel was studied experimentally. Microparticle image velocimetry (μPIV) was employed to quantify flow parameters such as flow field, spanwise vorticity, and turbulent kinetic energy (TKE) in the microchannel. Flow regimes of cylinder-diameter-based Reynolds number at 100 ⩽ Re D ⩽ 700 (i.e., steady, transition from quasi-steady to unsteady, and unsteady flow) were elucidated at the microscale. In addition, active flow control (AFC), via a steady control jet (issued from the pillar itself in the downstream direction), was implemented to induce favorable disturbances to the flow in order to alter the flow field, promote turbulence, and increase mixing. Together with passive flow control (i.e., a circular pillar), turbulent kinetic energy was significantly increased in a controllable manner throughout the flow field.

  15. Explosive magnetic flux compression plate generators as fast high-energy power sources

    International Nuclear Information System (INIS)

    Caird, R.S.; Erickson, D.J.; Garn, W.B.; Fowler, C.M.

    1976-01-01

    A type of explosive driven generator, called a plate generator, is described. It is capable of delivering electrical energies in the MJ range at TW power levels. Plane wave detonated explosive systems accelerate two large-area metal plates to high opposing velocities. An initial magnetic field is compressed and the flux transferred to an external load. The characteristics of the plate generator are described and compared with those of other types of generators. Methods of load matching are discussed. The results of several high-power experiments are also given

  16. Experiences with the ASDEX neutralizer plates and construction of water-cooled plates for long-pulse heating

    International Nuclear Information System (INIS)

    Rapp, H.; Niedermeyer, H.; Kornherr, M.

    1987-01-01

    After dismantling of the titanium neutralizer plates inspection yielded satisfactory status of flat areas whereas edges and curved shapes were heavily melted. At the inner plates of the lower divertor strongly focused melting and cutting was found which is caused by fast electrons. These electrons are continuously produced. The production mechanism is not yet clear but runaway processes can be excluded. With long-pulse additional heating of 6 MW/10s as planned for ASDEX in 1987, the total energy delivered to the plasma will increase by a factor of 30. Therefore new water-cooled neutralizer plates have been constructed which consist of a copper-steel compound. The construction principle and the topology of the cooling circuits is presented

  17. Convective boiling in a parallel microchannel heat sink with a diverging cross-section design and artificial nucleation sites

    International Nuclear Information System (INIS)

    Lu, Chun Ting; Pan, Chin

    2009-01-01

    To develop a highly stable boiling heat transfer microchannel heat sink, the three types of diverging microchannels, namely Type-1, Type-2 and Type-3, were designed to explore experimentally the effect of different distribution of artificial nucleation sites on enhancing boiling heat transfer in 10 parallel diverging microchannels with a mean hydraulic diameter of 120 μm. The Type-1 system is with no cavities, Type-2 is with cavities distributed uniformly along the downstream half of the channel, while Type-3 is with cavities distributed uniformly along the whole channel. The artificial nucleation sites are laser-etched pits on the channel bottom wall with a mouth diameter of about 20-22 μm based on the heterogeneous nucleation theory. The results of the present study reveal the presence of the artificial nucleation sites for flow boiling in parallel diverging microchannel significantly reduces the wall superheat and enhances the boiling heat transfer performance. Additionally, the Type-3 design demonstrates the best boiling heat transfer performance. (author)

  18. Diamond Microchannel Heat Sink Designs For High Heat Flux Thermal Control

    National Research Council Canada - National Science Library

    Corbin, Michael

    2002-01-01

    .... Many investigators have suggested the use of diamond heat spreaders to reduce flux levels at or near to its source, and some have suggested that diamond microchannel heat sinks ultimately may play...

  19. Evaluation of Superficial and Dimensional Quality Features in Metallic Micro-Channels Manufactured by Micro-End-Milling

    Directory of Open Access Journals (Sweden)

    Claudio Giardini

    2013-04-01

    Full Text Available Miniaturization encourages the development of new manufacturing processes capable of fabricating features, like micro-channels, in order to use them for different applications, such as in fuel cells, heat exchangers, microfluidic devices and micro-electromechanical systems (MEMS. Many studies have been conducted on heat and fluid transfer in micro-channels, and they appeared significantly deviated from conventional theory, due to measurement errors and fabrication methods. The present research, in order to deal with this opportunity, is focused on a set of experiments in the micro-milling of channels made of aluminum, titanium alloys and stainless steel, varying parameters, such as spindle speed, depth of cut per pass (ap, channel depth (d, feed per tooth (fz and coolant application. The experimental results were analyzed in terms of dimensional error, channel profile shape deviation from rectangular and surface quality (burr and roughness. The micro-milling process was capable of offering quality features required on the micro-channeled devices. Critical phenomena, like run-out, ploughing, minimum chip thickness and tool wear, were encountered as an explanation for the deviations in shape and for the surface quality of the micro-channels. The application of coolant and a low depth of cut per pass were significant to obtain better superficial quality features and a smaller dimensional error. In conclusion, the integration of superficial and geometrical features on the study of the quality of micro-channeled devices made of different metallic materials contributes to the understanding of the impact of calibrated cutting conditions in MEMS applications.

  20. Cavitation in flow through a micro-orifice inside a silicon microchannel

    Science.gov (United States)

    Mishra, Chandan; Peles, Yoav

    2005-01-01

    Hydrodynamic cavitation in flows through a micro-orifice entrenched in a microchannel has been detected and experimentally investigated. Microfabrication techniques have been employed to design and develop a microfluidic device containing an 11.5μm wide micro-orifice inside a 100.2μm wide and 101.3μm deep microchannel. The flow of de-ionized water through the micro-orifice reveals the presence of multifarious cavitating flow regimes. This investigation divulges both similarities and differences between cavitation in micro-orifices and cavitation in their macroscale counterparts. The low incipient cavitation number obtained from the current experiments suggests a dominant size scale effect. Choking cavitation is observed to be independent of any pressure or velocity scale effects. However, choking is significantly influenced by the small stream nuclei residence time at such scales. Flow rate choking leads to the establishment of a stationary cavity. Large flow and cavitation hysteresis have been detected at the microscale leading to very high desinent cavitation numbers. The rapid transition from incipient bubbles to choking cavitation and subsequent supercavitation suggests the presence of radically different flow patterns at the microscale. Supercavitation results in a thick cavity, which extends throughout the microchannel, and is encompassed by the liquid. Cavitation at the microscale is expected to considerably influence the design of innovative high-speed microfluidic systems.

  1. Pressure and partial wetting effects on superhydrophobic friction reduction in microchannel flow

    Science.gov (United States)

    Kim, Tae Jin; Hidrovo, Carlos

    2012-11-01

    Friction reduction in microchannel flows can help alleviate the inherently taxing pumping power requirements associated with the dimensions involved. One possible way of achieving friction reduction is through the introduction of surface microtexturing that can lead to a superhydrophobic Cassie-Baxter state. The Cassie-Baxter state is characterized by the presence of air pockets within the surface microtexturing believed to act as an effective "shear free" (or at least shear reduced) layer, decreasing the overall friction characteristics of the surface. Most work in this area has concentrated on optimizing the surface microtexturing geometry to maximize the friction reduction effects and overall stability of the Cassie-Baxter state. However, less attention has been paid to the effects of partially wetted conditions induced by pressure and the correlation between the liquid-gas interface location within the surface microtexturing and the microchannel flow characteristics. This is mainly attributed to the difficulty in tracking the interface shape and location within the microtexturing in the typical top-down view arrangements used in most studies. In this paper, a rectangular microchannel with regular microtexturing on the sidewalls is used to visualize and track the location of the air-water interface within the roughness elements. While visually tracking the wetting conditions in the microtextures, pressure drops versus flow rates for each microchannel are measured and analyzed in terms of the non-dimensional friction coefficient. The frictional behavior of the Poiseuille flow suggests that (1) the air-water interface more closely resembles a no-slip boundary rather than a shear-free one, (2) the friction is rather insensitive to the degree of microtexturing wetting, and (3) the fully wetted (Wenzel state) microtexturing provides lower friction than the non-wetted one (Cassie state), in corroboration with observations (1) and (2).

  2. The application of μPIV technique in the study of magnetic flows in a micro-channel

    International Nuclear Information System (INIS)

    Nguyen, N.T.; Wu, Z.G.; Huang, X.Y.; Wen, C.-Y..

    2005-01-01

    In this preliminary experimental study, micro-scale particle image velocimetry (μPIV) was adopted for the first time to get the quantitative information of magnetic flows in a micro-channel. The μPIV consists of an inverted florescent microscope, a Q-switch Nd:YAG laser and a CCD camera. The florescent liquid with particles of 3 μm diameter was blended homogeneously with the prepared magnetic fluid. A permanent magnet approached and left one end of the micro-channel. The response of the magnetic fluid was recorded with the μPIV simultaneously. The flow features validate the feasibility of using μPIV technique in the study of magnetic flows in a micro-channel. μPIV provides a promising experimental tool for visualization and quantitative measurement of magnetic micro-flows

  3. Pattern analysis of aligned nanowires in a microchannel

    International Nuclear Information System (INIS)

    Jeon, Young Jin; Kang, Hyun Wook; Ko, Seung Hwan; Sung, Hyung Jin

    2013-01-01

    An image processing method for evaluating the quality of nanowire alignment in a microchannel is described. A solution containing nanowires flowing into a microchannel will tend to deposit the nanowires on the bottom surface of the channel via near-wall shear flows. The deposited nanowires generally form complex directional structures along the direction of flow, and the physical properties of these structures depend on the structural morphology, including the alignment quality. A quantitative analysis approach to characterizing the nanowire alignment is needed to estimate the useful features of the nanowire structures. This analysis consists of several image processing methods, including ridge detection, texton analysis and autocorrelation function (ACF) calculation. The ridge detection method improved the ACF by extracting nanowire frames 1–2 pixels in width. Dilation filters were introduced to permit a comparison of the ACF results calculated from different images, regardless of the nanowire orientation. An ACF based on the FFT was then calculated over a square interrogation window. The alignment angle probability distribution was obtained using texton analysis. Monte Carlo simulations of artificially generated images were carried out, and the new algorithm was applied to images collected using two types of microscopy. (paper)

  4. Osmotically driven flows in microchannels separated by a semipermeable membrane

    DEFF Research Database (Denmark)

    Jensen, Kåre Hartvig; Lee, J.; Bohr, Tomas

    2009-01-01

    We have fabricated lab-on-a-chip systems with microchannels separated by integrated membranes allowing for osmotically driven microflows. We have investigated these flows experimentally by studying the dynamics and structure of the front of a sugar solution travelling in 200 mu m wide and 50-200 mu...... m deep microchannels. We find that the sugar front travels at a constant speed, and that this speed is proportional to the concentration of the sugar solution and inversely proportional to the depth of the channel. We propose a theoretical model, which, in the limit of low axial flow resistance......, predicts that the sugar front should indeed travel with a constant velocity. The model also predicts an inverse relationship between the depth of the channel and the speed, and a linear relation between the sugar concentration and the speed. We thus find good qualitative agreement between the experimental...

  5. Effect of microculture on cell metabolism and biochemistry: do cells get stressed in microchannels?

    Science.gov (United States)

    Su, Xiaojing; Theberge, Ashleigh B; January, Craig T; Beebe, David J

    2013-02-05

    Microfluidics is emerging as a promising platform for cell culture, enabling increased microenvironment control and potential for integrated analysis compared to conventional macroculture systems such as well plates and Petri dishes. To advance the use of microfluidic devices for cell culture, it is necessary to better understand how miniaturization affects cell behavior. In particular, microfluidic devices have significantly higher surface-area-to-volume ratios than conventional platforms, resulting in lower volumes of media per cell, which can lead to cell stress. We investigated cell stress under a variety of culture conditions using three cell lines: parental HEK (human embryonic kidney) cells and transfected HEK cells that stably express wild-type (WT) and mutant (G601S) human ether-a-go-go related gene (hERG) potassium channel protein. These three cell lines provide a unique model system through which to study cell-type-specific responses in microculture because mutant hERG is known to be sensitive to environmental conditions, making its expression a particularly sensitive readout through which to compare macro- and microculture. While expression of WT-hERG was similar in microchannel and well culture, the expression of mutant G601S-hERG was reduced in microchannels. Expression of the endoplasmic reticulum (ER) stress marker immunoglobulin binding protein (BiP) was upregulated in all three cell lines in microculture. Using BiP expression, glucose consumption, and lactate accumulation as readouts we developed methods for reducing ER stress including properly increasing the frequency of media replacement, reducing cell seeding density, and adjusting the serum concentration and buffering capacity of culture medium. Indeed, increasing the buffering capacity of culture medium or frequency of media replacement partially restored the expression of the G601S-hERG in microculture. This work illuminates how biochemical properties of cells differ in macro- and

  6. Heat transfer and pressure drop in microchannels with random roughness

    NARCIS (Netherlands)

    Pelevic, N.; van der Meer, Theodorus H.

    2016-01-01

    The effect of surface roughness on heat transfer and fluid flow phenomena within a microchannel has been investigated by using the lattice Boltzmann method. The surface roughness has been generated by using Gaussian function. Gaussian function is an efficient and convenient method to create surface

  7. Continuous particle focusing in a waved microchannel using negative dc dielectrophoresis

    KAUST Repository

    Li, Ming; Li, Shunbo; Cao, Wenbin; Li, Weihua; Wen, Weijia; Alici, Gursel

    2012-01-01

    We present a waved microchannel for continuous focusing of microparticles and cells using negative direct current (dc) dielectrophoresis. The waved channel is composed of consecutive s-shaped curved channels in series to generate an electric field

  8. Air-side performance of a micro-channel heat exchanger in wet surface conditions

    Directory of Open Access Journals (Sweden)

    Srisomba Raviwat

    2017-01-01

    Full Text Available The effects of operating conditions on the air-side heat transfer, and pressure drop of a micro-channel heat exchanger under wet surface conditions were studied experimentally. The test section was an aluminum micro-channel heat exchanger, consisting of a multi-louvered fin and multi-port mini-channels. Experiments were conducted to study the effects of inlet relative humidity, air frontal velocity, air inlet temperature, and refrigerant temperature on air-side performance. The experimental data were analyzed using the mean enthalpy difference method. The test run was performed at relative air humidities ranging between 45% and 80%; air inlet temperature ranges of 27, 30, and 33°C; refrigerant-saturated temperatures ranging from 18 to 22°C; and Reynolds numbers between 128 and 166. The results show that the inlet relative humidity, air inlet temperature, and the refrigerant temperature had significant effects on heat transfer performance and air-side pressure drop. The heat transfer coefficient and pressure drop for the micro-channel heat exchanger under wet surface conditions are proposed in terms of the Colburn j factor and Fanning f factor.

  9. Development of New Correlation and Assessment of Correlations for Two-Phase Pressure Drop in Rectangular Microchannels

    International Nuclear Information System (INIS)

    Choi, Chi Woong; Yu, Dong In; Kim, Moo Hwan

    2010-01-01

    There are two kinds of models in two-phase pressured drop; homogeneous flow model and separated flow model. Many previous researchers have developed correlations for two-phase pressure drop in a microchannel. Most correlations were modified Lockhart and Martinelli's correlation, which was based on the separated flow model. In this study, experiments for adiabatic liquid water and nitrogen gas flow in rectangular microchannels were conducted to investigate two-phase pressure drop in the rectangular microchannels. Two-phase frictional pressure drop in the rectangular microchannels is highly related with flow regime. Homogeneous model with six two-phase viscosity models: Owen(21)'s, MacAdams(22)'s, Cicchitti et al.(23)'s, Dukler et al.(24)'s, Beattie and Whalley(25)'s, Lin et al.(26)'s models and six separated flow models: Lockhart and Martinelli(27)'s, Chisholm(31)'s, Zhang et al.(15)'s, Lee and Lee(5)'s, Moriyama and Inue(4)'s, Qu and Mudawar(8)'s models were assessed with our experimental data. The best two-phase viscosity model is Beattie and Whalley's model. The best separated flow model is Qu and Mudawar's correlation. Flow regime dependency in both homogeneous and separated flow models was observed. Therefore, new flow pattern based correlations for both homogeneous and separated flow models were individually proposed

  10. Theoretical modeling of electroosmotic flow in soft microchannels: A variational approach applied to the rectangular geometry

    Science.gov (United States)

    Sadeghi, Arman

    2018-03-01

    Modeling of fluid flow in polyelectrolyte layer (PEL)-grafted microchannels is challenging due to their two-layer nature. Hence, the pertinent studies are limited only to circular and slit geometries for which matching the solutions for inside and outside the PEL is simple. In this paper, a simple variational-based approach is presented for the modeling of fully developed electroosmotic flow in PEL-grafted microchannels by which the whole fluidic area is considered as a single porous medium of variable properties. The model is capable of being applied to microchannels of a complex cross-sectional area. As an application of the method, it is applied to a rectangular microchannel of uniform PEL properties. It is shown that modeling a rectangular channel as a slit may lead to considerable overestimation of the mean velocity especially when both the PEL and electric double layer (EDL) are thick. It is also demonstrated that the mean velocity is an increasing function of the fixed charge density and PEL thickness and a decreasing function of the EDL thickness and PEL friction coefficient. The influence of the PEL thickness on the mean velocity, however, vanishes when both the PEL thickness and friction coefficient are sufficiently high.

  11. An experimental analysis of process parameters to manufacture micro-channels in AISI H13 tempered steel by laser micro-milling

    Science.gov (United States)

    Teixidor, D.; Ferrer, I.; Ciurana, J.

    2012-04-01

    This paper reports the characterization of laser machining (milling) process to manufacture micro-channels in order to understand the incidence of process parameters on the final features. Selection of process operational parameters is highly critical for successful laser micromachining. A set of designed experiments is carried out in a pulsed Nd:YAG laser system using AISI H13 hardened tool steel as work material. Several micro-channels have been manufactured as micro-mold cavities varying parameters such as scanning speed (SS), pulse intensity (PI) and pulse frequency (PF). Results are obtained by evaluating the dimensions and the surface finish of the micro-channel. The dimensions and shape of the micro-channels produced with laser-micro-milling process exhibit variations. In general the use of low scanning speeds increases the quality of the feature in both surface finishing and dimensional.

  12. Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

    Science.gov (United States)

    Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

    2017-02-01

    Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.

  13. An analytical model for annular flow boiling heat transfer in microchannel heat sinks

    International Nuclear Information System (INIS)

    Megahed, A.; Hassan, I.

    2009-01-01

    An analytical model has been developed to predict flow boiling heat transfer coefficient in microchannel heat sinks. The new analytical model is proposed to predict the two-phase heat transfer coefficient during annular flow regime based on the separated model. Opposing to the majority of annular flow heat transfer models, the model is based on fundamental conservation principles. The model considers the characteristics of microchannel heat sink during annular flow and eliminates using any empirical closure relations. Comparison with limited experimental data was found to validate the usefulness of this analytical model. The model predicts the experimental data with a mean absolute error 8%. (author)

  14. Surface Modification of SiO2 Microchannels with Biocompatible Polymer Using Supercritical Carbon Dioxide

    Science.gov (United States)

    Saito, Tatsuro; Momose, Takeshi; Hoshi, Toru; Takai, Madoka; Ishihara, Kazuhiko; Shimogaki, Yukihiro

    2010-11-01

    The surface of 500-mm-long microchannels in SiO2 microchips was modified using supercritical CO2 (scCO2) and a biocompatible polymer was coated on it to confer biocompatibility to the SiO2 surface. In this method, the SiO2 surface of a microchannel was coated with poly(ethylene glycol monomethacrylate) (PEGMA) as the biocompatible polymer using allyltriethoxysilane (ATES) as the anchor material in scCO2 as the reactive medium. Results were compared with those using the conventional wet method. The surface of a microchannel could not be modified by the wet method owing to the surface tension and viscosity of the liquid, but it was modified uniformly by the scCO2 method probably owing to the near-zero surface tension, low viscosity, and high diffusivity of scCO2. The effect of the surface modification by the scCO2 method to prevent the adsorption of protein was as high as that of the modification by the wet method. Modified microchips can be used in biochemical and medical analyses.

  15. Pressure Drop and Catalytic Dehydrogenation of NaBH{sub 4} Solution Across Pin Fin Structures in a Microchannel Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Ki Moon [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of); Choi, Seok Hyun [Key Valve Technologies Ltd., Siheung (Korea, Republic of); Lee, Hee Joon [Kookmin Univ., Seoul (Korea, Republic of)

    2017-06-15

    Dehydrogenation from the hydrolysis of a sodium borohydride (NaBH{sub 4}) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.%) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a NaBH4 solution over both a single microchannel with a hydraulic diameter of 300 μm and a staggered array of micro pin fins in the microchannel with hydraulic diameter of 50 μm. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.%. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

  16. Induced- and alternating-current electro-osmotic control of the diffusion layer growth in a microchannel-membrane interface device

    Science.gov (United States)

    Park, Sinwook; Yossifon, Gilad

    2014-11-01

    The passage of an electric current through an ionic permselective medium under an applied electric field is characterized by the formation of ionic concentration gradients, which result in regions of depleted and enriched ionic concentration at opposite ends of the medium. Induced-current electro-osmosis (ICEO) and alternating-current-electro-osmosis (ACEO) are shown to control the growth of the diffusion layer (DL) which, in turn, controls the diffusion limited ion transport through the microchannel-membrane system. We fabricated and tested devices made of a Nafion membrane connecting two opposite PDMS microchannels. An interdigitated electrode array was embedded within the microchannel with various distances from the microchannel-membrane interface. The induced ICEO (floating electrodes) / ACEO (active electrodes) vortices formed at the electrode array stir the fluid and thereby suppress the growth of the DL. The intensity of the ACEO vortices is controlled by either varying the voltage amplitude or the frequency, each having its own unique effect. Enhancement of the limiting current by on-demand control of the diffusion length is of importance in on-chip electro-dialysis, desalination and preconcentration of analytes.

  17. Self-Sealed Bionic Long Microchannels with Thin Walls and Designable Nanoholes Prepared by Line-Contact Capillary-Force Assembly.

    Science.gov (United States)

    Lao, Zhao-Xin; Hu, Yan-Lei; Pan, Deng; Wang, Ren-Yan; Zhang, Chen-Chu; Ni, Jin-Cheng; Xu, Bing; Li, Jia-Wen; Wu, Dong; Chu, Jia-Ru

    2017-06-01

    Long microchannels with thin walls, small width, and nanoholes or irregular shaped microgaps, which are similar to capillaries or cancerous vessels, are urgently needed to simulate the physiological activities in human body. However, the fabrication of such channels remains challenging. Here, microchannels with designable holes are manufactured by combining laser printing with line-contact capillary-force assembly. Two microwalls are first printed by femtosecond laser direct-writing, and subsequently driven to collapse into a channel by the capillary force that arises in the evaporation of developer. The channel can remain stable in solvent due to the enhanced Van der Waals' force caused by the line-contact of microwalls. Microchannels with controllable nanoholes and almost arbitrary patterns can be fabricated without any bonding or multistep processes. As-prepared microchannels, with wall thicknesses less than 1 µm, widths less than 3 µm, lengths more than 1 mm, are comparable with human capillaries. In addition, the prepared channels also exhibit the ability to steer the flow of liquid without any external pump. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Crossflow type silicon microchannel substrate monodispersion oil-in-water emulsion manufacture; Kurosufuro gata shirikon maikuro chaneru kiban wo mochiita tanbunsan suchuyu emarushon no sakusei

    Energy Technology Data Exchange (ETDEWEB)

    Kawakatsu, Takahiro [Tohoku University, Miyagi (Japan). Graduate School; Komori, Hideai; Najima, Mitsutashi; Kikuchi, Yuji; Yonemoto, Toshikuni

    1999-05-05

    The new technique, which continuously produced the monodispersion oil-in-water (0/W) emulsion using the crossflow type silicon microchannel substrate, was developed. On the silicon monocrystal substrate, the watercourse as the liquid of the continuous phase flowed was produced, and the column of the equal slit of the size in both walls of the watercourse was precisely processed. By closing the upper part in the slit by the clamp of the flat glass board in the microchannel substrate, the microchannel column was formed. Through the microchannel, the oil droplet in which the size was even was formed by sending out the oil (triolein) in the water (0.3wt% sodium lauryl sulfate aqueous solution) of continuous phase which is flowing in respect of the watercourse. The size of the oil droplet is greatly dependent on the structure of the microchannel regulated by microchannel width, microchannel height and terrace length (the even part of which the microchannel exit was equipped). Monodispersion emulsion of 16,20 and 48 {mu}m at the average droplet diameter was formed by using microchannel substrate of the three types of which the structure differs. Droplet diameter decreased, when the substrate which formed large droplet of 48 {mu}m in which the water current quantity is 1.4x10{sup -2}mLmin{sup -1} was used, when the flow rate increased. However, there was no a flow rate at droplet diameter, even if it was made to change from 1.4x10{sup -2} to 2.4mLmin{sup -1}, 16 {mu}m 20 {mu}m small change. In all cases, the droplet size distribution was narrow, and the geometry standard deviation was under 1.03. (translated by NEDO)

  19. A dimensional comparison between embedded 3D-printed and silicon microchannels

    International Nuclear Information System (INIS)

    O'Connor, J; Punch, J; Jeffers, N; Stafford, J

    2014-01-01

    The subject of this paper is the dimensional characterization of embedded microchannel arrays created using contemporary 3D-printing fabrication techniques. Conventional microchannel arrays, fabricated using deep reactive ion etching techniques (DRIE) and wet-etching (KOH), are used as a benchmark for comparison. Rectangular and trapezoidal cross-sectional shapes were investigated. The channel arrays were 3D-printed in vertical and horizontal directions, to examine the influence of print orientation on channel characteristics. The 3D-printed channels were benchmarked against Silicon channels in terms of the following dimensional characteristics: cross-sectional area (CSA), perimeter, and surface profiles. The 3D-printed microchannel arrays demonstrated variances in CSA of 6.6-20% with the vertical printing approach yielding greater dimensional conformity than the horizontal approach. The measured CSA and perimeter of the vertical channels were smaller than the nominal dimensions, while the horizontal channels were larger in both CSA and perimeter due to additional side-wall roughness present throughout the channel length. This side-wall roughness caused significant shape distortion. Surface profile measurements revealed that the base wall roughness was approximately the resolution of current 3D-printers. A spatial periodicity was found along the channel length which appeared at different frequencies for each channel array. This paper concludes that vertical 3D-printing is superior to the horizontal printing approach, in terms of both dimensional fidelity and shape conformity and can be applied in microfluidic device applications.

  20. Flow analysis for efficient design of wavy structured microchannel mixing devices

    Science.gov (United States)

    Kanchan, Mithun; Maniyeri, Ranjith

    2018-04-01

    Microfluidics is a rapidly growing field of applied research which is strongly driven by demands of bio-technology and medical innovation. Lab-on-chip (LOC) is one such application which deals with integrating bio-laboratory on micro-channel based single fluidic chip. Since fluid flow in such devices is restricted to laminar regime, designing an efficient passive modulator to induce chaotic mixing for such diffusion based flow is a major challenge. In the present work two-dimensional numerical simulation of viscous incompressible flow is carried out using immersed boundary method (IBM) to obtain an efficient design for wavy structured micro-channel mixing devices. The continuity and Navier-Stokes equations governing the flow are solved by fractional step based finite volume method on a staggered Cartesian grid system. IBM uses Eulerian co-ordinates to describe fluid flow and Lagrangian co-ordinates to describe solid boundary. Dirac delta function is used to couple both these co-ordinate variables. A tether forcing term is used to impose the no-slip boundary condition on the wavy structure and fluid interface. Fluid flow analysis by varying Reynolds number is carried out for four wavy structure models and one straight line model. By analyzing fluid accumulation zones and flow velocities, it can be concluded that straight line structure performs better mixing for low Reynolds number and Model 2 for higher Reynolds number. Thus wavy structures can be incorporated in micro-channels to improve mixing efficiency.

  1. A dimensional comparison between embedded 3D-printed and silicon microchannels

    Science.gov (United States)

    O'Connor, J.; Punch, J.; Jeffers, N.; Stafford, J.

    2014-07-01

    The subject of this paper is the dimensional characterization of embedded microchannel arrays created using contemporary 3D-printing fabrication techniques. Conventional microchannel arrays, fabricated using deep reactive ion etching techniques (DRIE) and wet-etching (KOH), are used as a benchmark for comparison. Rectangular and trapezoidal cross-sectional shapes were investigated. The channel arrays were 3D-printed in vertical and horizontal directions, to examine the influence of print orientation on channel characteristics. The 3D-printed channels were benchmarked against Silicon channels in terms of the following dimensional characteristics: cross-sectional area (CSA), perimeter, and surface profiles. The 3D-printed microchannel arrays demonstrated variances in CSA of 6.6-20% with the vertical printing approach yielding greater dimensional conformity than the horizontal approach. The measured CSA and perimeter of the vertical channels were smaller than the nominal dimensions, while the horizontal channels were larger in both CSA and perimeter due to additional side-wall roughness present throughout the channel length. This side-wall roughness caused significant shape distortion. Surface profile measurements revealed that the base wall roughness was approximately the resolution of current 3D-printers. A spatial periodicity was found along the channel length which appeared at different frequencies for each channel array. This paper concludes that vertical 3D-printing is superior to the horizontal printing approach, in terms of both dimensional fidelity and shape conformity and can be applied in microfluidic device applications.

  2. Pool boiling visualization on open microchannel surfaces

    Directory of Open Access Journals (Sweden)

    Kaniowski Robert

    2017-01-01

    Full Text Available The paper presents visualization investigations into pool boiling heat transfer for open minichannel surfaces. The experiments were carried out wih saturated water at atmospheric pressure. Parallel microchannels fabricated by machining were about 0.3 mm wide and 0.2 to 0.4 mm deep. High-speed videos were used as an aid to understanding the heat transfer mechanism. The visualization study aimed at identifying nucleation sites of the departing bubbles and determining their diameters and frequency at various superheats.

  3. Thermal baffle for fast-breeder reactor

    International Nuclear Information System (INIS)

    Rylatt, J.A.

    1977-01-01

    A liquid-metal-cooled fast-breeder reactor includes a bridge structure for separating hot outlet coolant from relatively cool inlet coolant consisting of an annular stainless steel baffle plate extending between the core barrel surrounding the core and the thermal liner associated with the reactor vessel and resting on ledges thereon, there being inner and outer circumferential webs on the lower surface of the baffle plate and radial webs extending between the circumferential webs, a stainless steel insulating plate completely covering the upper surface of the baffle plate and flex seals between the baffle plate and the ledges on which the baffle plate rests to prevent coolant from washing through the gaps therebetween. The baffle plate is keyed to the core barrel for movement therewith and floating with respect to the thermal liner and reactor vessel. 3 claims, 2 figures

  4. Two-phase flow regimes in a horizontal microchannel with the height of 50 μm and width of 10 mm

    Science.gov (United States)

    Fina, V. P.; Ronshin, F. V.

    2017-11-01

    Two-phase flows of distilled deionized nanofiltered water and nitrogen gas in a microchannel with a height of 50 μm and a width of 10 mm have been investigated experimentally. The schlieren method has been used to determine main features of the two-phase flow in the microchannel. This method allows detecting the liquid film on the lower and upper walls of the microchannel as well as droplets of various shapes and sizes or vertical liquid bridges. Two-phase flow regimes have been observed, and their boundaries precisely determined using post-processing of the recordings. The following flow regimes have been distinguished: bubble, churn, jet, stratified and annular. Comparison of regime maps for channels of different widths has been carried out, and this parameter showed to have a significant impact on the boundaries between the regimes in microchannels of a height of less than 100 μm.

  5. Fabrication of Super-Hydrophobic Microchannels via Strain-Recovery Deformations of Polystyrene and Oxygen Reactive Ion Etch.

    Science.gov (United States)

    Chakraborty, Anirban; Xiang, Mingming; Luo, Cheng

    2013-08-19

    In this article, we report a simple approach to generate micropillars (whose top portions are covered by sub-micron wrinkles) on the inner surfaces of polystyrene (PS) microchannels, as well as on the top surface of the PS substrate, based on strain-recovery deformations of the PS and oxygen reactive ion etch (ORIE). Using this approach, two types of micropillar-covered microchannels are fabricated. Their widths range from 118 μm to 132 μm, depths vary from 40 μm to 44 μm, and the inclined angles of their sidewalls are from 53° to 64°. The micropillars enable these microchannels to have super-hydrophobic properties. The contact angles observed on the channel-structured surfaces are above 162°, and the tilt angles to make water drops roll off from these channel-structured substrates can be as small as 1°.

  6. Fabrication of Super-Hydrophobic Microchannels via Strain-Recovery Deformations of Polystyrene and Oxygen Reactive Ion Etch

    Directory of Open Access Journals (Sweden)

    Anirban Chakraborty

    2013-08-01

    Full Text Available In this article, we report a simple approach to generate micropillars (whose top portions are covered by sub-micron wrinkles on the inner surfaces of polystyrene (PS microchannels, as well as on the top surface of the PS substrate, based on strain-recovery deformations of the PS and oxygen reactive ion etch (ORIE. Using this approach, two types of micropillar-covered microchannels are fabricated. Their widths range from 118 μm to 132 μm, depths vary from 40 μm to 44 μm, and the inclined angles of their sidewalls are from 53° to 64°. The micropillars enable these microchannels to have super-hydrophobic properties. The contact angles observed on the channel-structured surfaces are above 162°, and the tilt angles to make water drops roll off from these channel-structured substrates can be as small as 1°.

  7. Thermal and hydrodynamic studies for micro-channel cooling for large area silicon sensors in high energy physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Flaschel, Nils; Ariza, Dario; Diez, Sergio; Gregor, Ingrid-Maria; Tackmann, Kerstin [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Gerboles, Marta; Jorda, Xavier; Mas, Roser; Quirion, David; Ullan, Miguel [Centro Nacional de Microelectronica, Barcelona (Spain)

    2017-01-15

    Micro-channel cooling initially aiming at small-sized high-power integrated circuits is being transferred to the field of high energy physics. Today's prospects of micro-fabricating silicon opens a door to a more direct cooling of detector modules. The challenge in high energy physics is to save material in the detector construction and to cool large areas. In this paper, we are investigating micro-channel cooling as a candidate for a future cooling system for silicon detectors in a generic research and development approach. The work presented in this paper includes the production and the hydrodynamic and thermal testing of a micro-channel equipped prototype optimized to achieve a homogeneous flow distribution. Furthermore, the device was simulated using finite element methods.

  8. Thermal and hydrodynamic studies for micro-channel cooling for large area silicon sensors in high energy physics experiments

    International Nuclear Information System (INIS)

    Flaschel, Nils; Ariza, Dario; Diez, Sergio; Gregor, Ingrid-Maria; Tackmann, Kerstin; Gerboles, Marta; Jorda, Xavier; Mas, Roser; Quirion, David; Ullan, Miguel

    2017-01-01

    Micro-channel cooling initially aiming at small-sized high-power integrated circuits is being transferred to the field of high energy physics. Today's prospects of micro-fabricating silicon opens a door to a more direct cooling of detector modules. The challenge in high energy physics is to save material in the detector construction and to cool large areas. In this paper, we are investigating micro-channel cooling as a candidate for a future cooling system for silicon detectors in a generic research and development approach. The work presented in this paper includes the production and the hydrodynamic and thermal testing of a micro-channel equipped prototype optimized to achieve a homogeneous flow distribution. Furthermore, the device was simulated using finite element methods.

  9. An improved plating assay for determination of phage titer | Yang ...

    African Journals Online (AJOL)

    In this study, an improved plating assay was developed for detection of the number of recombinant phage Cap-T7 present in a test solution at a certain dilution point by counting the plaque forming units. The data demonstrated that the improved plating assay is fast, useful, and convenient for the determination of the phage ...

  10. Development and characterisation of a visible light photon counting imaging detector system

    CERN Document Server

    Barnstedt, J

    2002-01-01

    We report on the development of a visible light photon counting imaging detector system. The detector concept is based on standard 25 mm diameter microchannel plate image intensifiers made by Proxitronic in Bensheim (Germany). Modifications applied to these image intensifiers are the use of three microchannel plates instead of two and a high resistance ceramics plate used instead of the standard phosphor output screen. A wedge and strip anode mounted directly behind the high resistance ceramics plate was used as a read out device. This wedge and strip anode picks up the image charge of electron clouds emerging from the microchannel plates. The charge pulses are fed into four charge amplifiers and subsequently into a digital position decoding electronics, achieving a position resolution of up to 1024x1024 pixels. Mounting the anode outside the detector tube is a new approach and has the great advantage of avoiding electrical feedthroughs from the anode so that the standard image intensifier fabrication process...

  11. Neural growth into a microchannel network: towards a regenerative neural interface

    NARCIS (Netherlands)

    Wieringa, P.A.; Wiertz, Remy; le Feber, Jakob; Rutten, Wim

    2009-01-01

    We propose and validated a design for a highly selective 'endcap' regenerative neural interface towards a neuroprosthesis. In vitro studies using rat cortical neurons determine if a branching microchannel structure can counter fasciculated growth and cause neurites to separte from one another,

  12. Numerical study on drag reduction and heat transfer enhancement in microchannels with superhydrophobic surfaces for electronic cooling

    International Nuclear Information System (INIS)

    Cheng, Yongpan; Xu, Jinliang; Sui, Yi

    2015-01-01

    Microchannels with superhydrophobic surfaces are a promising candidate for electric cooling with mild frictional penalty. Frictional and thermal performance of laminar liquid-water flow in such microchannels is numerically investigated for various shear-free fractions and Reynolds numbers. The structures on superhydrophobic surfaces include square posts and holes, transverse and longitudinal grooves. Combined frictional and thermal performance of microchannels is evaluated by a goodness factor, and is compared with that of smooth plain channels. It is found that with increasing shear-free fractions, both friction factor and average Nusselt number deteriorate for four surface patterns; however, goodness factor is improved significantly over smooth plain channels. In general, superhydrophobic surfaces containing longitudinal and transverse grooves exhibit the lowest and highest frictional and thermal performance, respectively; however, combined performance of these two are on opposite. Among four surface patterns, longitudinal grooves have the highest goodness factors, except at high shear-free fractions or high Reynolds numbers where overall performance is surpassed by square posts. At very low or high shear-free fractions, frictional and thermal performance of two-dimensional square posts and holes approaches that of one-dimensional longitudinal or transverse grooves. Our study suggests microchannels with superhydrophobic surfaces as promising candidates for efficient cooling devices.

  13. Behaviour and design considerations for continuous flow closed-open-closed liquid microchannels.

    Science.gov (United States)

    Melin, Jessica; van der Wijngaart, Wouter; Stemme, Göran

    2005-06-01

    This paper introduces a method of combining open and closed microchannels in a single component in a novel way which couples the benefits of both open and closed microfluidic systems and introduces interesting on-chip microfluidic behaviour. Fluid behaviour in such a component, based on continuous pressure driven flow and surface tension, is discussed in terms of cross sectional flow behaviour, robustness, flow-pressure performance, and its application to microfluidic interfacing. The closed-open-closed microchannel possesses the versatility of upstream and downstream closed microfluidics along with open fluidic direct access. The device has the advantage of eliminating gas bubbles present upstream when these enter the open channel section. The unique behaviour of this device opens the door to applications including direct liquid sample interfacing without the need for additional and bulky sample tubing.

  14. Inexpensive read-out for coincident electron spectroscopy with a transmission electron microscope at nanometer scale using micro channel plates and multistrip anodes

    International Nuclear Information System (INIS)

    Hollander, R.W.; Bom, V.R.; Van Eijk, C.W.E.; Faber, J.S.; Hoevers, H.; Kruit, P.

    1994-01-01

    The elemental composition of a sample at nanometer scale is determined by measurement of the characteristic energy of Auger electrons, emitted in coincidence with incoming primary electrons from a microbeam in a scanning transmission electron microscope (STEM). Single electrons are detected with position sensitive detectors, consisting of MicroChannel Plates (MCP) and MultiStrip Anodes (MSA), one for the energy of the Auger electrons (Auger-detector) and one for the energy loss of primary electrons (EELS-detector). The MSAs are sensed with LeCroy 2735DC preamplifiers. The fast readout is based on LeCroy's PCOS III system. On the detection of a coincidence (Event) energy data of Auger and EELS are combined with timing data to an Event word. Event words are stored in list mode in a VME memory module. Blocks of Event words are scanned by transputers in VME and two-dimensional energy histograms are filled using the timing information to obtain a maximal true/accidental ratio. The resulting histograms are stored on disk of a PC-386, which also controls data taking. The system is designed to handle 10 5 Events per second, 90% of which are accidental. In the histograms the ''true'' to ''accidental'' ratio will be 5. The dead time is 15%. ((orig.))

  15. Evaluation of a X-ray imaging method in micro-fluidics: the case of T-shaped micro-channels filling up

    International Nuclear Information System (INIS)

    Vabre, A.; Legoupil, S.; Manach, E.; Gal, O.; Colin, St.; Geoffroy, S.; Gue, A.M.

    2006-01-01

    X-rays methods assessment in micro-fluidics: case of 'T' shaped microchannels filling. Fluid flows within 'T' or 'Y' shaped microchannels are deeply studied in order to develop adapted modeling approaches and experimental techniques. Our technological choice lies on the attenuation measurement of X-ray in matter. The main advantage of this non-intrusive technique is to be implemented on media opaque to visible light. Moreover, X-rays methods may achieve better spatial resolutions as compared to optical methods because of their much lower wavelength. In order to validate this X-ray method, measurements obtained by this technique are compared with direct measurements carried out on similar microchannels. Finally, experimental results are compared with a theoretical model. (author)

  16. Motion of Passive Scalar by Elasticity-Induced Instability in Curved Microchannel

    Directory of Open Access Journals (Sweden)

    Xiao-Bin Li

    2014-08-01

    Full Text Available This paper presented a direct numerical simulation (DNS study on the elasticity-induced irregular flow, passive mixing, and scalar evolution in the curvilinear microchannel. The mixing enhancement was achieved at vanishingly low-Reynolds-number chaotic flow raised by elastic instabilities. Along with the mixing process, the passive scalar transportation carried by the flow was greatly affected by the flow structure and the underlying interaction between microstructures of viscoelastic fluid and flow structure itself. The simulations are conducted for a wide range of viscoelasticity. As the elastic effect exceeds the critical value, the flow tends to a chaotic state, while the evolution of scalar gets strong and fast, showing excellent agreement with experimental results. For the temporal changing of scalar gradients, they vary rapidly in the form of isosurfaces, with the shape of “rolls” in the bulk and evolving into “threads” near the wall. That indicates that the flow fields should be related to the deformation of viscoelastic micromolecules. The probability distribution function analysis between micromolecular deformation and flow field deformation shows that the main direction of molecular stretching is perpendicular to the main direction of flow field deformation. It implies they are weakly correlated, due to the confinement of channel wall.

  17. Surface cell immobilization within perfluoroalkoxy microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Stojkovič, Gorazd; Krivec, Matic [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Vesel, Alenka [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Marinšek, Marjan [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia); Žnidaršič-Plazl, Polona, E-mail: polona.znidarsic@fkkt.uni-lj.si [Faculty of Chemistry and Chemical Technology, University of Ljubljana, Aškerčeva 5, SI-1000 Ljubljana (Slovenia)

    2014-11-30

    Graphical abstract: - Highlights: • A very efficient approach for immobilization of cells into microreactors is presented. • It is applicable to various materials, including PFA and cyclic olefin (co)polymers. • It was used to immobilize different prokaryotic and eukaryotic microbes. • Cells were immobilized on the surface in high density and showed good stability. • Mechanisms of APTES interactions with target materials are proposed. - Abstract: Perfluoroalkoxy (PFA) is one of the most promising materials for the fabrication of cheap, solvent resistant and reusable microfluidic chips, which have been recently recognized as effective tools for biocatalytic process development. The application of biocatalysts significantly depends on efficient immobilization of enzymes or cells within the reactor enabling long-term biocatalyst use. Functionalization of PFA microchannels by 3-aminopropyltriethoxysilane (ATPES) and glutaraldehyde was used for rapid preparation of microbioreactors with surface-immobilized cells. X-ray photoelectron spectroscopy and scanning electron microscopy were used to accurately monitor individual treatment steps and to select conditions for cell immobilization. The optimized protocol for Saccharomyces cerevisiae immobilization on PFA microchannel walls comprised ethanol surface pretreatment, 4 h contacting with 10% APTES aqueous solution, 10 min treatment with 1% glutaraldehyde and 20 min contacting with cells in deionized water. The same protocol enabled also immobilization of Escherichia coli, Pseudomonas putida and Bacillus subtilis cells on PFA surface in high densities. Furthermore, the developed procedure has been proved to be very efficient also for surface immobilization of tested cells on other materials that are used for microreactor fabrication, including glass, polystyrene, poly (methyl methacrylate), polycarbonate, and two olefin-based polymers, namely Zeonor{sup ®} and Topas{sup ®}.

  18. Stability Analysis of Reactive Multiphase Slug Flows in Microchannels

    Directory of Open Access Journals (Sweden)

    Alejandro A. Munera Parra

    2014-05-01

    Full Text Available Conducting multiphase reactions in micro-reactors is a promising strategy for intensifying chemical and biochemical processes. A major unresolved challenge is to exploit the considerable benefits offered by micro-scale operation for industrial scale throughputs by numbering-up whilst retaining the underlying advantageous flow characteristics of the single channel system in multiple parallel channels. Fabrication and installation tolerances in the individual micro-channels result in different pressure losses and, thus, a fluid maldistribution. In this work, an additional source of maldistribution, namely the flow multiplicities, which can arise in a multiphase reactive or extractive flow in otherwise identical micro-channels, was investigated. A detailed experimental and theoretical analysis of the flow stability with and without reaction for both gas-liquid and liquid-liquid slug flow has been developed. The model has been validated using the extraction of acetic acid from n-heptane with the ionic liquid 1-Ethyl-3-methylimidazolium ethyl sulfate. The results clearly demonstrate that the coupling between flow structure, the extent of reaction/extraction and pressure drop can result in multiple operating states, thus, necessitating an active measurement and control concept to ensure uniform behavior and optimal performance.

  19. Theoretical study of time-dependent, ultrasound-induced acoustic streaming in microchannels

    DEFF Research Database (Denmark)

    Muller, Peter Barkholt; Bruus, Henrik

    2015-01-01

    Based on first- and second-order perturbation theory, we present a numerical study of the temporal buildup and decay of unsteady acoustic fields and acoustic streaming flows actuated by vibrating walls in the transverse cross-sectional plane of a long straight microchannel under adiabatic...

  20. Optical fibre cavity ring down measurement of refractive index with a microchannel drilled by femtosecond laser

    Science.gov (United States)

    Zhou, Kaiming; Webb, David; Mou, Chengbo; Farries, Mark; Hayes, Neil; Bennion, Ian

    2009-10-01

    μA microchannel was inscribed in the fibre of a ring cavity which was constructed from two 0.1%:99.9% couplers and a 10m fibre loop. Cavity ring down spectroscopy (CRDS) was used to measure the refractive index (RI) of gels infused into the microchannel with high resolution. The ring down time discloses a nonlinear increase with respect to the RI of the gel and sensitivity up to 300μs/RI unit (RIU) and resolution of 5×10-4 were obtained.

  1. Flow Investigation in a Microchannel with a Flow Disturbing Rib

    Czech Academy of Sciences Publication Activity Database

    Stogiannis, I.A.; Passos, A.D.; Mouza, A.A.; Paras, S.V.; Pěnkavová, Věra; Tihon, Jaroslav

    2014-01-01

    Roč. 119, NOV 8 (2014), s. 65-76 ISSN 0009-2509 R&D Projects: GA ČR(CZ) GAP101/12/0585; GA MŠk 7AMB12GR018 Institutional support: RVO:67985858 Keywords : microchannel * wall shear stress * micro-PIV Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.337, year: 2014

  2. Nanoscale coatings for erosion and corrosion protection of copper microchannel coolers for high powered laser diodes

    Science.gov (United States)

    Flannery, Matthew; Fan, Angie; Desai, Tapan G.

    2014-03-01

    High powered laser diodes are used in a wide variety of applications ranging from telecommunications to industrial applications. Copper microchannel coolers (MCCs) utilizing high velocity, de-ionized water coolant are used to maintain diode temperatures in the recommended range to produce stable optical power output and control output wavelength. However, aggressive erosion and corrosion attack from the coolant limits the lifetime of the cooler to only 6 months of operation. Currently, gold plating is the industry standard for corrosion and erosion protection in MCCs. However, this technique cannot perform a pin-hole free coating and furthermore cannot uniformly cover the complex geometries of current MCCs involving small diameter primary and secondary channels. Advanced Cooling Technologies, Inc., presents a corrosion and erosion resistant coating (ANCERTM) applied by a vapor phase deposition process for enhanced protection of MCCs. To optimize the coating formation and thickness, coated copper samples were tested in 0.125% NaCl solution and high purity de-ionized (DIW) flow loop. The effects of DIW flow rates and qualities on erosion and corrosion of the ANCERTM coated samples were evaluated in long-term erosion and corrosion testing. The robustness of the coating was also evaluated in thermal cycles between 30°C - 75°C. After 1000 hours flow testing and 30 thermal cycles, the ANCERTM coated copper MCCs showed a corrosion rate 100 times lower than the gold plated ones and furthermore were barely affected by flow rates or temperatures thus demonstrating superior corrosion and erosion protection and long term reliability.

  3. Determination of the Navier slip coefficient of microchannels exploiting the streaming potential.

    Science.gov (United States)

    Park, Hung Mok

    2012-03-01

    For most microchannels made of hydrophobic materials such as polymers, velocity slip occurs at the wall, affecting volumetric flow rate of electroosmotic flow Q(eof) and streaming potential (∂ϕ(str)/∂z). Since most techniques exploit Q(eof) or (∂ϕ(str)/∂z) to determine the zeta potential, ζ, it is very difficult to measure ζ of hydrophobic walls, if the slip coefficient b is not found a priori. Until now, Q(eof) and (∂ϕ(str)/∂z) are known to depend on ζ and b in a same functional form, which makes it impossible to estimate ζ or b separately using measurements of Q(eof) and (∂ϕ(str)/∂z). However, exploiting the analytic formula for Q(eof) and (∂ϕ(str)/∂z) derived in the present work, it is found that the effect of ζ and that of b on Q(eof) and (∂ϕ(str)/∂z) can be separated from each other by varying the bulk ionic concentration. Thus, the slip coefficient as well as the zeta potential of hydrophobic microchannels can be found with reasonable accuracy by means of a nonlinear curve fitting method using measured data of Q(eof) and (∂ϕ(str)/∂z) at various bulk ionic concentrations. The present method allows an accurate estimation of slip coefficient of hydrophobic microchannels, which is quite simple and cheap compared with methods employing microparticle velocimetry. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Tunable hydrodynamic characteristics in microchannels with biomimetic superhydrophobic (lotus leaf replica) walls.

    Science.gov (United States)

    Dey, Ranabir; Raj M, Kiran; Bhandaru, Nandini; Mukherjee, Rabibrata; Chakraborty, Suman

    2014-05-21

    The present work comprehensively addresses the hydrodynamic characteristics through microchannels with lotus leaf replica (exhibiting low adhesion and superhydrophobic properties) walls. The lotus leaf replica is fabricated following an efficient, two-step, soft-molding process and is then integrated with rectangular microchannels. The inherent biomimetic, superhydrophobic surface-liquid interfacial hydrodynamics, and the consequential bulk flow characteristics, are critically analyzed by the micro-particle image velocimetry technique. It is observed that the lotus leaf replica mediated microscale hydrodynamics comprise of two distinct flow regimes even within the low Reynolds number paradigm, unlike the commonly perceived solely apparent slip-stick dominated flows over superhydrophobic surfaces. While the first flow regime is characterized by an apparent slip-stick flow culminating in an enhanced bulk throughput rate, the second flow regime exhibits a complete breakdown of the aforementioned laminar and uni-axial flow model, leading to a predominantly no-slip flow. Interestingly, the critical flow condition dictating the transition between the two hydrodynamic regimes is intrinsically dependent on the micro-confinement effect. In this regard, an energetically consistent theoretical model is also proposed to predict the alterations in the critical flow condition with varying microchannel configurations, by addressing the underlying biomimetic surface-liquid interfacial conditions. Hence, the present research endeavour provides a new design-guiding paradigm for developing multi-functional microfluidic devices involving biomimetic, superhydrophobic surfaces, by judicious exploitation of the tunable hydrodynamic characteristics in the two regimes.

  5. Ferrofluid-in-oil two-phase flow patterns in a flow-focusing microchannel

    Science.gov (United States)

    Sheu, T. S.; Chen, Y. T.; Lih, F. L.; Miao, J. M.

    This study investigates the two-phase flow formation process of water-based Fe3O4 ferrofluid (dispersed phase) in a silicon oil (continuous phase) flow in the microfluidic flow-focusing microchannel under various operational conditions. With transparent PDMS chip and optical microscope, four main two-phase flow patterns as droplet flow, slug flow, ring flow and churn flow are observed. The droplet shape, size, and formation mechanism were also investigated under different Ca numbers and intended to find out the empirical relations. The paper marks an original flow pattern map of the ferrofluid-in-oil flows in the microfluidic flow-focusing microchannels. The flow pattern transiting from droplet flow to slug flow appears for an operational conditions of QR < 1 and Lf / W < 1. The power law index that related Lf / W to QR was 0.36 in present device.

  6. 3D tomography of cells in micro-channels

    Science.gov (United States)

    Quint, S.; Christ, A. F.; Guckenberger, A.; Himbert, S.; Kaestner, L.; Gekle, S.; Wagner, C.

    2017-09-01

    We combine confocal imaging, microfluidics, and image analysis to record 3D-images of cells in flow. This enables us to recover the full 3D representation of several hundred living cells per minute. Whereas 3D confocal imaging has thus far been limited to steady specimens, we overcome this restriction and present a method to access the 3D shape of moving objects. The key of our principle is a tilted arrangement of the micro-channel with respect to the focal plane of the microscope. This forces cells to traverse the focal plane in an inclined manner. As a consequence, individual layers of passing cells are recorded, which can then be assembled to obtain the volumetric representation. The full 3D information allows for a detailed comparison with theoretical and numerical predictions unfeasible with, e.g., 2D imaging. Our technique is exemplified by studying flowing red blood cells in a micro-channel reflecting the conditions prevailing in the microvasculature. We observe two very different types of shapes: "croissants" and "slippers." Additionally, we perform 3D numerical simulations of our experiment to confirm the observations. Since 3D confocal imaging of cells in flow has not yet been realized, we see high potential in the field of flow cytometry where cell classification thus far mostly relies on 1D scattering and fluorescence signals.

  7. Aluminum Nitride Micro-Channels Grown via Metal Organic Vapor Phase Epitaxy for MEMs Applications

    Energy Technology Data Exchange (ETDEWEB)

    Rodak, L.E.; Kuchibhatla, S.; Famouri, P.; Ting, L.; Korakakis, D.

    2008-01-01

    Aluminum nitride (AlN) is a promising material for a number of applications due to its temperature and chemical stability. Furthermore, AlN maintains its piezoelectric properties at higher temperatures than more commonly used materials, such as Lead Zirconate Titanate (PZT) [1, 2], making AlN attractive for high temperature micro and nanoelectromechanical (MEMs and NEMs) applications including, but not limited to, high temperature sensors and actuators, micro-channels for fuel cell applications, and micromechanical resonators. This work presents a novel AlN micro-channel fabrication technique using Metal Organic Vapor Phase Epitaxy (MOVPE). AlN easily nucleates on dielectric surfaces due to the large sticking coefficient and short diffusion length of the aluminum species resulting in a high quality polycrystalline growth on typical mask materials, such as silicon dioxide and silicon nitride [3,4]. The fabrication process introduced involves partially masking a substrate with a silicon dioxide striped pattern and then growing AlN via MOVPE simultaneously on the dielectric mask and exposed substrate. A buffered oxide etch is then used to remove the underlying silicon dioxide and leave a free standing AlN micro-channel. The width of the channel has been varied from 5 ìm to 110 ìm and the height of the air gap from 130 nm to 800 nm indicating the stability of the structure. Furthermore, this versatile process has been performed on (111) silicon, c-plane sapphire, and gallium nitride epilayers on sapphire substrates. Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and Raman measurements have been taken on channels grown on each substrate and indicate that the substrate is influencing the growth of the AlN micro-channels on the SiO2 sacrificial layer.

  8. High density gold nanoparticles immobilized on surface via plasma deposited APTES film for decomposing organic compounds in microchannels

    Science.gov (United States)

    Rao, Xi; Guyon, Cédric; Ognier, Stephanie; Da Silva, Bradley; Chu, Chenglin; Tatoulian, Michaël; Hassan, Ali Abou

    2018-05-01

    Immobilization of colloidal particles (e.g. gold nanoparticles (AuNps)) on the inner surface of micro-/nano- channels has received a great interest for catalysis. A novel catalytic ozonation setup using a gold-immobilized microchannel reactor was developed in this work. To anchor AuNps, (3-aminopropyl) triethoxysilane (APTES) with functional amine groups was deposited using plasma enhanced chemical vapor deposition (PECVD) process. The results clearly evidenced that PECVD processing exhibited relatively high efficiency for grafting amine groups and further immobilizing AuNPs. The catalytic activity of gold immobilized microchannel was evaluated by pyruvic acid ozonation. The decomposition rate calculated from High Performance Liquid Chromatography (HPLC) indicated a much better catalytic performance of gold in microchannel than that in batch. The results confirmed immobilizing gold nanoparticles on plasma deposited APTES for preparing catalytic microreactors is promising for the wastewater treatment in the future.

  9. Shock wave attenuation in a micro-channel

    Science.gov (United States)

    Giordano, J.; Perrier, P.; Meister, L.; Brouillette, M.

    2018-05-01

    This work presents optical measurements of shock wave attenuation in a glass micro-channel. This transparent facility, with a cross section ranging from 1 mm× 150 μm to 1 mm× 500 μm, allowed for the use of high-speed schlieren videography to visualize the propagation of a shock wave within the entire micro-channel and to quantify velocity attenuation of the wave due to wall effects. In this paper, we present the experimental technique and the relevant data treatment we have used to increase the sensitivity of shock wave detection. Then, we compared our experimental results for different channel widths, lengths, and shock wave velocities with the analytical model for shock attenuation proposed by Russell (J Fluid Mech 27(2):305-314, 1967), which assumes laminar flow, and by Mirels (Attenuation in a shock tube due to unsteady-boundary-layer action, NACA Report 1333, 1957) for turbulent flow. We found that these models are inadequate to predict the observed data, owing to the presence of fully developed flow which violates the basic assumption of these models. The data are also compared with the empirical shock attenuation models proposed by Zeitoun (Phys Fluids 27(1):011701, 2015) and Deshpande and Puranik (Shock Waves 26(4):465-475, 2016), where better agreement is observed. Finally, we presented experimental data for the flow field behind the shock wave from measurements of the Mach wave angle which shows globally decreasing flow Mach numbers due to viscous wall effects.

  10. Investigation of power battery thermal management by using mini-channel cold plate

    International Nuclear Information System (INIS)

    Huo, Yutao; Rao, Zhonghao; Liu, Xinjian; Zhao, Jiateng

    2015-01-01

    Highlights: • Micro-channel cold plate was used for battery thermal management. • Maximum temperature of battery decreased with the increase of channel number. • Effect of flow direction on cooling performance is smaller with the increase of flow rate. • Cooling performance increased with the increase of inlet flow rate. • The increasing trend become smaller when the flow rate is high enough. - Abstract: In order to guarantee the safety and extend the cycle life of Li-ion power batteries within electric vehicles, a mini-channel cold plate-based battery thermal management system is designed to cool a rectangular Li-ion battery. A three-dimensional thermal model of the cooling system was established and the effects of number of channels, flow direction, inlet mass flow rate and ambient temperature on temperature rise and distribution of the battery during the discharge process were investigated. The results suggest that the maximum temperature of the battery decreases with increases in the number of channels and inlet mass flow rate. The effect of flow direction on cooling performance was smaller after mass flow rate increased. The cooling performance improved with the increase of inlet mass flow rate but the increasing trend became smaller, and the mass flow rate as 5 × 10 −4 kg s −1 was optimal. The simulation results will be useful for the design of mini-channel cold plate-based battery thermal management system

  11. submitter The TORCH detector R&D: Status and perspectives

    CERN Document Server

    Gys, T; Castillo García, L; Cussans, D; Föhl, K; Forty, R; Frei, C; Gao, R; Harnew, N; Piedigrossi, D; Rademacker, J; Ros García, A; van Dijk, M

    2017-01-01

    TORCH (Timing Of internally Reflected CHerenkov photons) is a time-of-flight detector for particle identification at low momentum. It has been originally proposed for the LHCb experiment upgrade. TORCH is using plates of quartz radiator in a modular design. A fraction of the Cherenkov photons produced by charged particles passing through this radiator propagate by total internal reflection, they emerge at the edges and are subsequently focused onto fast, position-sensitive single-photon detectors. The recorded position and arrival time of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. The on-going R&D; programme aims at demonstrating the TORCH basic concept through the realization of a full detector module and has been organized on the following main development lines: micro-channel plate photon detectors featuring the required granularity and lifetime, dedicated fast front-end electronics preserving the picosecond timing information provided by single p...

  12. Developing the laminar MHD forced convection flow of water/FMWNT carbon nanotubes in a microchannel imposed the uniform heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Karimipour, Arash; Taghipour, Abdolmajid [Department of Mechanical Engineering, Najafabad Branch, Islamic Azad University, Najafabad (Iran, Islamic Republic of); Malvandi, Amir, E-mail: amirmalvandi@aut.ac.ir [Department of Mechanical Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of)

    2016-12-01

    This paper aims to investigate magnetic field and slip effects on developing laminar forced convection of nanofluids in the microchannels. A novel mixture of water and FMWNT carbon nanotubes is used as the working fluid. To do this, fluid flow and heat transfer through a microchannel is simulated by a computer code in FORTRAN language. The mixture of FMWNT carbon nanotubes suspended in water is considered as the nanofluid. Slip velocity is supposed as the hydrodynamic boundary condition while the microchannel's lower wall is insulated and the top wall is under the effect of a constant heat flux. Moreover, the flow field is subjected to a magnetic field with a constant strength. The results are presented as the velocity, temperature and Nusselt number profiles. It is observed that nanofluid composed of water and carbon nanotubes (FMWNT) can work well to increase the heat transfer rate along the microchannel walls. Furthermore, it is indicated that imposing the magnetic field is very effective at the thermally developing region. In contrast, the magnetic field effect at fully developed region is insignificant, especially at low values of Reynolds number. - Highlights: • Simulation of water/FMWNT carbon nanotubes flow in a microchannel. • The effects of magnetic field strength on nanofluid's slip velocity. • The effects of Ha, Re, ϕ and slip coefficient on averaged Nusselt number. • Magnetic field effect at developing flow region is significant.

  13. NINO An ultra-fast and low-power front-end amplifier/discriminator ASIC designed for the multigap resistive plate chamber

    CERN Document Server

    Anghinolfi, F; Martemyanov, A N; Usenko, E; Wenninger, Horst; Williams, M C S; Zichichi, A

    2004-01-01

    For the full exploitation of the excellent timing properties of the Multigap Resistive Plate Chamber (MRPC), front-end electronics with special characteristics are needed. These are (a) differential input, to profit from the differential signal from the MRPC (b) a fast amplifier with less than 1 ns peaking time and (c) input charge measurement by Time-Over-Threshold for slewing correction. An 8- channel amplifier and discriminator chip has been developed to match these requirements. This is the NINO ASIC, fabricated with 0.25 omegam CMOS technology. The power requirement at 40mW/channel is low. Results on the performance of the MRPCs using the NINO ASIC are presented. Typical time resolution a of the MRPC system is in the 50 ps range, with an efficiency of 99.9%.

  14. Investigating performance of microchannel evaporators for automobile air conditioning with different port structures

    Directory of Open Access Journals (Sweden)

    Guoliang Zhou

    2017-08-01

    Full Text Available Microchannel evaporator has been widely applied in automobile air conditioning, while it faces the problem of refrigerant maldistribution which deteriorates the thermal performance of evaporator. In this study, the performances of microchannel evaporators with different port structures are experimentally investigated for purpose of reducing evaporator pressure drop. Four evaporator samples with different port number and hydraulic diameter are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant R-134A at a real automobile air conditioning. The results on the variations of the evaporator pressure drop and evaporator surface temperature distribution are presented and analyzed. By studying the performance of an evaporator, seeking proper port structure is an approach to reduce refrigerant pressure drop as well as improve refrigerant distribution.

  15. Activity and lifetime of urease immobilized using layer-by-layer nano self-assembly on silicon microchannels.

    Science.gov (United States)

    Forrest, Scott R; Elmore, Bill B; Palmer, James D

    2005-01-01

    Urease has been immobilized and layered onto the walls of manufactured silicon microchannels. Enzyme immobilization was performed using layer-by-layer nano self-assembly. Alternating layers of oppositely charged polyelectrolytes, with enzyme layers "encased" between them, were deposited onto the walls of the silicon microchannels. The polycations used were polyethylenimine (PEI), polydiallyldimethylammonium (PDDA), and polyallylamine (PAH). The polyanions used were polystyrenesulfonate (PSS) and polyvinylsulfate (PVS). The activity of the immobilized enzyme was tested by pumping a 1 g/L urea solution through the microchannels at various flow rates. Effluent concentration was measured using an ultraviolet/visible spectrometer by monitoring the absorbance of a pH sensitive dye. The architecture of PEI/PSS/PEI/urease/PEI with single and multiple layers of enzyme demonstrated superior performance over the PDDA and PAH architectures. The precursor layer of PEI/PSS demonstrably improved the performance of the reactor. Conversion rates of 70% were achieved at a residence time of 26 s, on d 1 of operation, and >50% at 51 s, on d 15 with a six-layer PEI/urease architecture.

  16. Verification of homogenization in fast critical assembly analyses

    International Nuclear Information System (INIS)

    Chiba, Go

    2006-01-01

    In the present paper, homogenization procedures for fast critical assembly analyses are investigated. Errors caused by homogenizations are evaluated by the exact perturbation theory. In order to obtain reference solutions, three-dimensional plate-wise transport calculations are performed. It is found that the angular neutron flux along plate boundaries has a significant peak in the fission source energy range. To treat this angular dependence accurately, the double-Gaussian Chebyshev angular quadrature set with S 24 is applied. It is shown that the difference between the heterogeneous leakage theory and the homogeneous theory is negligible, and that transport cross sections homogenized with neutron flux significantly underestimate neutron leakage. The error in criticality caused by a homogenization is estimated at about 0.1%Δk/kk' in a small fast critical assembly. In addition, the neutron leakage is overestimated by both leakage theories when sodium plates in fuel lattices are voided. (author)

  17. Acoustically Generated Flows in Flexural Plate Wave Sensors: a Multifield Analysis

    Science.gov (United States)

    Sayar, Ersin; Farouk, Bakhtier

    2011-11-01

    Acoustically excited flows in a microchannel flexural plate wave device are explored numerically with a coupled solid-fluid mechanics model. The device can be exploited to integrate micropumps with microfluidic chips. A comprehensive understanding of the device requires the development of coupled two or three-dimensional fluid structure interactive (FSI) models. The channel walls are composed of layers of ZnO, Si3N4 and Al. An isothermal equation of state for the fluid (water) is employed. The flexural motions of the channel walls and the resulting flowfields are solved simultaneously. A parametric analysis is performed by varying the values of the driving frequency, voltage of the electrical signal and the channel height. The time averaged axial velocity is found to be proportional to the square of the wave amplitude. The present approach is superior to the method of successive approximations where the solid-liquid coupling is weak.

  18. Modeling of low-capillary number segmented flows in microchannels using OpenFOAM

    NARCIS (Netherlands)

    Hoang, D.A.; Van Steijn, V.; Portela, L.M.; Kreutzer, M.T.; Kleijn, C.R.

    2012-01-01

    Modeling of low-Capillary number segmented flows in microchannels is important for the design of microfluidic devices. We present numerical validations of microfluidic flow simulations using the volume-of-fluid (VOF) method as implemented in OpenFOAM. Two benchmark cases were investigated to ensure

  19. Hydrogen production through aqueous-phase reforming of ethylene glycol in a washcoated microchannel

    NARCIS (Netherlands)

    Neira d'Angelo, M.F.; Ordomskiy, V.; Paunovic, V.; Schaaf, van der J.; Schouten, J.C.; Nijhuis, T.A.

    2013-01-01

    Aqueous-phase reforming (APR) of biocarbohydrates is conducted in a catalytically stable washcoated microreactor where multiphase hydrogen removal enhances hydrogen efficiency. Single microchannel experiments are conducted following a simplified model based on the microreactor concept. A coating

  20. Modelling and Pareto optimization of heat transfer and flow coefficients in microchannels using GMDH type neural networks and genetic algorithms

    International Nuclear Information System (INIS)

    Amanifard, N.; Nariman-Zadeh, N.; Borji, M.; Khalkhali, A.; Habibdoust, A.

    2008-01-01

    Three-dimensional heat transfer characteristics and pressure drop of water flow in a set of rectangular microchannels are numerically investigated using Fluent and compared with those of experimental results. Two metamodels based on the evolved group method of data handling (GMDH) type neural networks are then obtained for modelling of both pressure drop (ΔP) and Nusselt number (Nu) with respect to design variables such as geometrical parameters of microchannels, the amount of heat flux and the Reynolds number. Using such obtained polynomial neural networks, multi-objective genetic algorithms (GAs) (non-dominated sorting genetic algorithm, NSGA-II) with a new diversity preserving mechanism is then used for Pareto based optimization of microchannels considering two conflicting objectives such as (ΔP) and (Nu). It is shown that some interesting and important relationships as useful optimal design principles involved in the performance of microchannels can be discovered by Pareto based multi-objective optimization of the obtained polynomial metamodels representing their heat transfer and flow characteristics. Such important optimal principles would not have been obtained without the use of both GMDH type neural network modelling and the Pareto optimization approach

  1. Effects of microchannel confinement on acoustic vaporisation of ultrasound phase change contrast agents

    Science.gov (United States)

    Lin, Shengtao; Zhang, Ge; Hau Leow, Chee; Tang, Meng-Xing

    2017-09-01

    The sub-micron phase change contrast agent (PCCA) composed of a perfluorocarbon liquid core can be activated into gaseous state and form stable echogenic microbubbles for contrast-enhanced ultrasound imaging. It has shown great promise in imaging microvasculature, tumour microenvironment, and cancer cells. Although PCCAs have been extensively studied for different diagnostic and therapeutic applications, the effect of biologically geometrical confinement on the acoustic vaporisation of PCCAs is still not clear. We have investigated the difference in PCCA-produced ultrasound contrast enhancement after acoustic activation with and without a microvessel confinement on a microchannel phantom. The experimental results indicated more than one-order of magnitude less acoustic vaporisation in a microchannel than that in a free environment taking into account the attenuation effect of the vessel on the microbubble scattering. This may provide an improved understanding in the applications of PCCAs in vivo.

  2. Experimental and numerical investigations of ionic liquid-aqueous flow in microchannel

    Science.gov (United States)

    Li, Qi; Tsaoulidis, Dimitrios; Angeli, Panagiota

    2015-11-01

    The hydrodynamic characteristics of plug flow of an ionic liquid-aqueous two-phase system in a microchannel were studied experimentally and numerically. A mixture of 0.2M N-octyl(plenyl)-N,N-diisobutylcarbamoylmethyphosphine oxide (CMOP)- 1.2 M Tri-n-butylphosphate (TBP) in room temperature ionic liquid 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]amide ([C4min][NTf2]), and a nitric acid solution of 1M were chosen. These fluids are relevant Eu(III) separation by extraction from nitric acid solutions. The two liquid phases were introduced into microchannels of 0.2 and 0.5mm internal diameter through a T-junction inlet. The flow pattern was visualized during plug formation at the inlet section and further downstream by means by bright field planar micro-Particle Image Velocimetry. Key features of plug flow, such as plug velocity, film thickness, plug length and recirculation intensity were measured under various experimental conditions. To gain further understanding of the 3-D flow field, Computation Fluid Dynamics (CFD) simulations approach were also conducted.

  3. Numerical simulation of electroosmotic flow in rough microchannels using the lattice Poisson-Nernst-Planck methods

    Science.gov (United States)

    Kamali, Reza; Soloklou, Mohsen Nasiri; Hadidi, Hooman

    2018-05-01

    In this study, coupled Lattice Boltzmann method is applied to solve the dynamic model for an electroosmotic flow and investigate the effects of roughness in a 2-D flat microchannel. In the present model, the Poisson equation is solved for the electrical potential, the Nernst- Planck equation is solved for the ion concentration. In the analysis of electroosmotic flows, when the electric double layers fully overlap or the convective effects are not negligible, the Nernst-Planck equation must be used to find the ionic distribution throughout the microchannel. The effects of surface roughness height, roughness interval spacing and roughness surface potential on flow conditions are investigated for two different configurations of the roughness, when the EDL layers fully overlap through the microchannel. The results show that in both arrangements of roughness in homogeneously charged rough channels, the flow rate decreases by increasing the roughness height. A discrepancy in the mass flow rate is observed when the roughness height is about 0.15 of the channel width, which its average is higher for the asymmetric configuration and this difference grows by increasing the roughness height. In the symmetric roughness arrangement, the mass flow rate increases until the roughness interval space is almost 1.5 times the roughness width and it decreases for higher values of the roughness interval space. For the heterogeneously charged rough channel, when the roughness surface potential ψr is less than channel surface potential ψs , the net charge density increases by getting far from the roughness surface, while in the opposite situation, when ψs is more than ψr , the net charge density decreases from roughness surface to the microchannel middle center. Increasing the roughness surface potential induces stronger electric driving force on the fluid which results in larger velocities in the flow.

  4. A one-step strategy for ultra-fast and low-cost mass production of plastic membrane microfluidic chips.

    Science.gov (United States)

    Hu, Chong; Lin, Sheng; Li, Wanbo; Sun, Han; Chen, Yangfan; Chan, Chiu-Wing; Leung, Chung-Hang; Ma, Dik-Lung; Wu, Hongkai; Ren, Kangning

    2016-10-05

    An ultra-fast, extremely cost-effective, and environmentally friendly method was developed for fabricating flexible microfluidic chips with plastic membranes. With this method, we could fabricate plastic microfluidic chips rapidly (within 12 seconds per piece) at an extremely low cost (less than $0.02 per piece). We used a heated perfluoropolymer perfluoroalkoxy (often called Teflon PFA) solid stamp to press a pile of two pieces of plastic membranes, low density polyethylene (LDPE) and polyethylene terephthalate (PET) coated with an ethylene-vinyl acetate copolymer (EVA). During the short period of contact with the heated PFA stamp, the pressed area of the membranes permanently bonded, while the LDPE membrane spontaneously rose up at the area not pressed, forming microchannels automatically. These two regions were clearly distinguishable even at the micrometer scale so we were able to fabricate microchannels with widths down to 50 microns. This method combines the two steps in the conventional strategy for microchannel fabrication, generating microchannels and sealing channels, into a single step. The production is a green process without using any solvent or generating any waste. Also, the chips showed good resistance against the absorption of Rhodamine 6G, oligonucleotides, and green fluorescent protein (GFP). We demonstrated some typical microfluidic manipulations with the flexible plastic membrane chips, including droplet formation, on-chip capillary electrophoresis, and peristaltic pumping for quantitative injection of samples and reagents. In addition, we demonstrated convenient on-chip detection of lead ions in water samples by a peristaltic-pumping design, as an example of the application of the plastic membrane chips in a resource-limited environment. Due to the high speed and low cost of the fabrication process, this single-step method will facilitate the mass production of microfluidic chips and commercialization of microfluidic technologies.

  5. The selective flow of volatile organic compounds in conductive polymer-coated microchannels

    Science.gov (United States)

    Hossein-Babaei, Faramarz; Hooshyar Zare, Ali

    2017-02-01

    Many gaseous markers of critical biological, physicochemical, or industrial occurrences are masked by the cross-sensitivity of the sensors to the other active components present at higher concentrations. Here, we report the strongly selective diffusion and drift of contaminant molecules in air-filled conductive polymer-coated microfluidic channels for the first time. Monitoring the passage of different target molecules through microchannels coated with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) revealed that contaminants such as hexane, benzene, and CO pass through the channel unaffected by the coating while methanol, ethanol, and partly acetone are blocked. The observations are explained with reference to the selective interactions between the conductive polymer surface and target gas molecules amplified by the large wall/volume ratio in microchannels. The accumulated quantitative data point at the hydrogen bonding as the mechanism of wall adsorption; dipole-dipole interactions are relatively insignificant. The presented model facilitates a better understanding of how the conductive polymer-based chemical sensors operate.

  6. Glucose Fuel Cells with a MicroChannel Fabricated on Flexible Polyimide Film

    Science.gov (United States)

    Sano, Ryohei; Fukushi, Yudai; Sasaki, Tsubasa; Mogi, Hiroshi; Koide, Syohei; Ikoma, Ryuta; Akatsuka, Wataru; Tsujimura, Seiya; Nishioka, Yasushiro

    2013-12-01

    In this work, a glucose fuel cell was fabricated using microfabrication processes assigned for microelectromechanical systems. The fuel cell was equipped with a microchannel to flow an aqueous solution of glucose. The cell was fabricated on a flexible polyimide substrate, and its porous carbon-coated aluminum (Al) electrodes of 2.8 mm in width and 11 mm in length were formed using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Al electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. The microchannel with a depth of 200 μm was fabricated using a hot embossing technique. A maximum power of 0.45 μW at 0.5 V that corresponds to a power density of 1.45 μW/cm2 was realized by introducing a 200 mM concentrated glucose solution at room temperature.

  7. Glucose Fuel Cells with a MicroChannel Fabricated on Flexible Polyimide Film

    International Nuclear Information System (INIS)

    Sano, Ryohei; Fukushi, Yudai; Sasaki, Tsubasa; Mogi, Hiroshi; Koide, Syohei; Ikoma, Ryuta; Nishioka, Yasushiro; Akatsuka, Wataru; Tsujimura, Seiya

    2013-01-01

    In this work, a glucose fuel cell was fabricated using microfabrication processes assigned for microelectromechanical systems. The fuel cell was equipped with a microchannel to flow an aqueous solution of glucose. The cell was fabricated on a flexible polyimide substrate, and its porous carbon-coated aluminum (Al) electrodes of 2.8 mm in width and 11 mm in length were formed using photolithography and screen printing techniques. Porous carbon was deposited by screen printing of carbon black ink on the Al electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the electrode surfaces. The microchannel with a depth of 200 μm was fabricated using a hot embossing technique. A maximum power of 0.45 μW at 0.5 V that corresponds to a power density of 1.45 μW/cm 2 was realized by introducing a 200 mM concentrated glucose solution at room temperature

  8. Distribution of Evaporating CO2 in Parallel Microchannels

    DEFF Research Database (Denmark)

    Brix, Wiebke; Elmegaard, Brian

    2008-01-01

    The impact on the heat exchanger performance due to maldistribution of evaporating CO2 in parallel channels is investigated numerically. A 1D steady state simulation model of a microchannel evaporator is built using correlations from the literature to calculate frictional pressure drop and heat...... transfer coefficients. For two channels in parallel two different cases of maldistribution are studied. Firstly, the impact of a non-uniform air flow is considered, and secondly the impact of maldistribution of the two phases in the inlet manifold is investigated. The results for both cases are compared...

  9. Power of the uranium plate of Naiade; Puissance de la plaque d'uranium de Naiade

    Energy Technology Data Exchange (ETDEWEB)

    Lafore, P; Millot, J P; Rastoin, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    1. Calculation. Knowing the incident current of thermal neutrons, the sources of fast neutrons inside the plate are deduced. The fast flux leaving the plate is then determined. Isotropically, 0.57 fast neutrons come out for each incident thermal neutron. 2. Experiments. The incident thermal flux is measured by means of manganese detectors on reaching the plate, and estimated from the flux leaving the graphite. The fast flux coming out is measured with dose-rate films. The absorption of the fast flux in the swimming-pool water is measured. 3. Results. The uranium plate is equivalent to a disc placed at its surface emitting isotropically 3.8 x 10{sup 7} fast neutrons per cm{sup 2}/s, when Zoe operates at 100 kW. This result is valid to about 10 per cent. (author) [French] 1.Calcul. Connaissant le courant de neutrons thermiques incident, on deduit les sources de rapides a l'interieur de la plaque. Puis on determine le flux de rapides sortants de la plaque. Il sort, de facon isotrope, 0,57 neutrons rapides par neutron thermique incident. 2. Experiences. Le flux thermique incident est mesure par des detecteurs au manganese a l'arrivee sur la plaque et estime a partir du flux a la sortie du graphite. Le flux rapide sortant est mesure avec des films de dose. On mesure l'absorption du flux rapide dans l'eau de la piscine. 3. Resultats. La plaque d'uranium est equivalente a un disque place a sa surface emettant isotropiquement, 3,8 x 10{sup 7} neutrons rapides par cm{sup 2}/s, lorsque ZOE marche a 100 kW. Ce resultat est valable a 10 pour cent pres. (auteur)

  10. Fast damage imaging using the time-reversal technique in the frequency–wavenumber domain

    International Nuclear Information System (INIS)

    Zhu, R; Huang, G L; Yuan, F G

    2013-01-01

    The time-reversal technique has been successfully used in structural health monitoring (SHM) for quantitative imaging of damage. However, the technique is very time-consuming when it is implemented in the time domain. In this paper, we study the technique in the frequency–wavenumber (f–k) domain for fast real-time imaging of multiple damage sites in plates using scattered flexural plate waves. Based on Mindlin plate theory, the time reversibility of dispersive flexural waves in an isotropic plate is theoretically investigated in the f–k domain. A fast damage imaging technique is developed by using the cross-correlation between the back-propagated scattered wavefield and the incident wavefield in the frequency domain. Numerical simulations demonstrate that the proposed technique cannot only localize multiple damage sites but also potentially identify their sizes. Moreover, the time-reversal technique in the f–k domain is about two orders of magnitude faster than the method in the time domain. Finally, experimental testing of an on-line SHM system with a sparse piezoelectric sensor array is conducted for fast multiple damage identification using the proposed technique. (paper)

  11. Single-phase liquid flow forced convection under a nearly uniform heat flux boundary condition in microchannels

    KAUST Repository

    Lee, Man

    2012-02-22

    A microchannel heat sink, integrated with pressure and temperature microsensors, is utilized to study single-phase liquid flow forced convection under a uniform heat flux boundary condition. Utilizing a waferbond-and-etch- back technology, the heat source, temperature and pressure sensors are encapsulated in a thin composite membrane capping the microchannels, thus allowing experimentally good control of the thermal boundary conditions. A three-dimensional physical model has been constructed to facilitate numerical simulations of the heat flux distribution. The results indicate that upstream the cold working fluid absorbs heat, while, within the current operating conditions, downstream the warmer working fluid releases heat. The Nusselt number is computed numerically and compared with experimental and analytical results. The wall Nusselt number in a microchannel can be estimated using classical analytical solutions only over a limited range of the Reynolds number, Re: both the top and bottom Nusselt numbers approach 4 for Re < 1, while the top and bottom Nusselt numbers approach 0 and 5.3, respectively, for Re > 100. The experimentally estimated Nusselt number for forced convection is highly sensitive to the location of the temperature measurements used in calculating the Nusselt number. © 2012 IOP Publishing Ltd.

  12. Single-phase liquid flow forced convection under a nearly uniform heat flux boundary condition in microchannels

    KAUST Repository

    Lee, Man; Lee, Yi-Kuen; Zohar, Yitshak

    2012-01-01

    A microchannel heat sink, integrated with pressure and temperature microsensors, is utilized to study single-phase liquid flow forced convection under a uniform heat flux boundary condition. Utilizing a waferbond-and-etch- back technology, the heat source, temperature and pressure sensors are encapsulated in a thin composite membrane capping the microchannels, thus allowing experimentally good control of the thermal boundary conditions. A three-dimensional physical model has been constructed to facilitate numerical simulations of the heat flux distribution. The results indicate that upstream the cold working fluid absorbs heat, while, within the current operating conditions, downstream the warmer working fluid releases heat. The Nusselt number is computed numerically and compared with experimental and analytical results. The wall Nusselt number in a microchannel can be estimated using classical analytical solutions only over a limited range of the Reynolds number, Re: both the top and bottom Nusselt numbers approach 4 for Re < 1, while the top and bottom Nusselt numbers approach 0 and 5.3, respectively, for Re > 100. The experimentally estimated Nusselt number for forced convection is highly sensitive to the location of the temperature measurements used in calculating the Nusselt number. © 2012 IOP Publishing Ltd.

  13. Asymmetry of blood flow and cancer cell adhesion in a microchannel with symmetric bifurcation and confluence.

    Science.gov (United States)

    Ishikawa, Takuji; Fujiwara, Hiroki; Matsuki, Noriaki; Yoshimoto, Takefumi; Imai, Yohsuke; Ueno, Hironori; Yamaguchi, Takami

    2011-02-01

    Bifurcations and confluences are very common geometries in biomedical microdevices. Blood flow at microchannel bifurcations has different characteristics from that at confluences because of the multiphase properties of blood. Using a confocal micro-PIV system, we investigated the behaviour of red blood cells (RBCs) and cancer cells in microchannels with geometrically symmetric bifurcations and confluences. The behaviour of RBCs and cancer cells was strongly asymmetric at bifurcations and confluences whilst the trajectories of tracer particles in pure water were almost symmetric. The cell-free layer disappeared on the inner wall of the bifurcation but increased in size on the inner wall of the confluence. Cancer cells frequently adhered to the inner wall of the bifurcation but rarely to other locations. Because the wall surface coating and the wall shear stress were almost symmetric for the bifurcation and the confluence, the result indicates that not only chemical mediation and wall shear stress but also microscale haemodynamics play important roles in the adhesion of cancer cells to the microchannel walls. These results provide the fundamental basis for a better understanding of blood flow and cell adhesion in biomedical microdevices.

  14. Experimental investigation of the unsteady one-phase flow through perforated plates

    International Nuclear Information System (INIS)

    Casadei, F.

    1982-07-01

    The flow of the coolant through the perforated dip-plate during a hypothetical core-disruptive accident in a sodium-cooled fast breeder reactor was simulated in a one-dimensional model. Several experiments with water as fluid and with various perforation ratios of the dip-plate and different initial heights of the fluid head over the dip plate were run. The pressure drop through the dip-plate and the forces acting on the dip-plate and on the upper plug of the reactor vessel in a wide range of the Reynolds and Strouhal numbers were measured. The flow pattern downstreams the perforated plate was filmed with high-speed cameras. The resistance coefficients for the unsteady flow of the coolant through the perforated plate were obtained as a function of the acceleration. The forces acting on the upper plug and their time integral were compared with those acting on the dip-plate. Finally, using the high-speed film pictures the formation of fluid jets downstream the dip-plate was investigated. (orig.) [de

  15. A Capillary Electrochromatographic Microchip Packed with Self-Assembly Colloidal Carboxylic Silica Beads

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, In Sun; Kim, Shin Seon; Park, Jong Man [Konkuk University, Seoul (Korea, Republic of)

    2012-04-15

    An electrochromatographic microchip with carboxyl-group-derivatized mono-disperse silica packing was prepared from the corresponding colloidal silica solution by utilizing capillary action and self-assembly behavior. The silica beads in water were primed by the capillary action toward the ends of cross-patterned microchannel on a cyclic olefinic copolymer (COC) substrate. Slow evaporation of water at the front of packing promoted the self-assembled packing of the beads. After thermally binding a cover plate on the chip substrate, reservoirs for sample solutions were fabricated at the ends of the microchannel. The packing at the entrances of the microchannel was silver coated to fix utilizing an electroless silver-plating technique to prevent the erosion of the packed structure caused by the sudden switching of a high voltage DC power source. The electrochromatographic behavior of the microchip was explored and compared to that of the microchip with bare silica packing in basic borate buffer. Electrophoretic migration of Rhodamine B was dominant in the microchip with the carboxyl-derivatized silica packing that resulted in a migration approximated twice as fast, while the reversible adsorption was dominant in the bare silica-packed microchip. Not only the faster migration rates of the negatively charged FITC-derivatives of amino acids but also the different migration due to the charge interaction at the packing surface were observed. The electrochromatographic characteristics were studied in detail and compared with those of the bare silica packed microchip in terms of the packing material, the separation potential, pH of the running buffer, and also the separation channel length

  16. Mathematical modelling of liquid meniscus shape in cylindrical micro-channel for normal and micro gravity conditions

    Science.gov (United States)

    Marchuk, Igor; Lyulin, Yuriy

    2017-10-01

    Mathematical model of liquid meniscus shape in cylindrical micro-channel of the separator unit of condensing/separating system is presented. Moving liquid meniscus in the 10 μm cylindrical microchannel is used as a liquid lock to recover the liquid obtained by condensation from the separators. The main goal of the liquid locks to prevent penetration of a gas phase in the liquid line at the small flow rate of the condensate and because of pressure fluctuations in the vapor-gas-liquid loop. Calculation of the meniscus shape has been performed for liquid FC-72 at different values of pressure difference gas - liquid and under normal and micro gravity conditions.

  17. Fluid flow and heat transfer of nanofluids in microchannel heat sink with V-type inlet/outlet arrangement

    Directory of Open Access Journals (Sweden)

    Ayoub Abdollahi

    2017-03-01

    Full Text Available The fluid flow and heat transfer characteristics of laminar nanofluid flow in microchannel heat sink (MCHS with V-Type inlet/outlet arrangement are numerically studied. A constant heat flux boundary condition is applied on the base plate of MCHS and all the other surfaces of MCHS are insulated. Four different kinds of nanofluids are utilized as working fluids which are SiO2, Al2O3, ZnO and CuO dispersed in pure water as a base fluid. Three different volume fractions of 1%, 1.5% and 2% and three distinctive nanoparticle diameters of 30 nm, 40 nm and 60 nm were employed. The results specify that the SiO2 nanofluid has the uppermost heat transfer rate compared to other tested nanofluids. Increasing the nanoparticles volume fraction together with decreasing the nanoparticles diameter enhances the Nusselt number value. The pressure drop coefficient did not change significantly by using nanofluid with various volume fractions and varied nanoparticle diameters. Moreover, the results indicate that nanofluid can enhance the performance of MCHS with V-shaped inlet/outlet arrangement.

  18. Diagnostics for Pioneer I imploding plasma experiments

    International Nuclear Information System (INIS)

    Lee, P.H.Y.; Benjamin, R.F.; Brownell, J.H.

    1985-01-01

    The Pioneer I series of imploding plasma experiments are aimed at collapsing a thin aluminum foil with a multimegampere, submicrosecond electrical pulse produced by an explosive flux compression generator and fast plasma compression opening switch. Anticipated experimental conditions are bounded by implosion velocities of 2 x 10 7 cm/s and maximum plasma temperatures of 100 eV. A comprehensive array of diagnostics have been deployed to measure implosion symmetry (gated microchannel plate array and other time-resolved imaging), temperature of the imploding plasma (visible/uv spectroscopy), stagnation geometry (x-ray pinhole imaging), radiation emission characteristics at pinch (XRD's, fast bolometry), and electrical drive history (Rogowski loops, Faraday rotation current detectors, and capacitive voltage probes). Diagnostic performance is discussed and preliminary results are presented

  19. Prototyping the PANDA Barrel DIRC

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, C., E-mail: C.Schwarz@gsi.de [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Kalicy, G.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Hohler, R.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwiening, J.; Traxler, M.; Zühlsdorf, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Dodokhov, V.Kh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Britting, A.; Eyrich, W.; Lehmann, A. [Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); and others

    2014-12-01

    The design of the Barrel DIRC detector for the future PANDA experiment at FAIR contains several important improvements compared to the successful BABAR DIRC, such as focusing and fast timing. To test those improvements as well as other design options a prototype was build and successfully tested in 2012 with particle beams at CERN. The prototype comprises a radiator bar, focusing lens, mirror, and a prism shaped expansion volume made of synthetic fused silica. An array of micro-channel plate photomultiplier tubes measures the location and arrival time of the Cherenkov photons with sub-nanosecond resolution. The development of a fast reconstruction algorithm allowed to tune construction details of the detector setup with test beam data and Monte-Carlo simulations.

  20. Light emission by an oscillator moving through a refracting plate

    International Nuclear Information System (INIS)

    Baryshevskij, V.G.

    1982-01-01

    Optical-frequency light emitted by a fast electron passing through a crystalline plate of a finite thickness is treated. Formulas are presented for the spectral distribution and intensity of the emission at a given frequency and amplitude of the electron oscillations. The formulas correspond to both normal and abnormal Doppler effects. The calculations are carried out for the light observed in the vacuum, with the reflection and refraction at the edges of the plate taken into account

  1. Positron emission zone plate holography for particle tracking

    Energy Technology Data Exchange (ETDEWEB)

    Gundogdu, O. [University of Birmingham, School of Physics and Astronomy, Birmingham B15 2TT (United Kingdom)]. E-mail: o.gundogdu@surrey.ac.uk

    2006-01-15

    Positron Emission Particle Tracking (PEPT) is a powerful non-invasive technique that has been used extensively for tracking a single particle. In this paper, we present a study of zone plate holography method in order to track multiple particles, mainly two particles. The main aim is to use as small number of events as possible in the order to make it possible to track particles in fast moving industrial systems. A zone plate with 100% focal efficiency is simulated and applied to the Positron Emission Tomography (PET) data for multiple particle tracking. A simple trajectory code was employed to explore the effects of the nature of the experimental trajectories. A computer holographic reconstruction code that simulates optical reconstruction was developed. The different aspects of the particle location, particle activity ratios for enabling tagging of particles and zone plate and hologram locations are investigated. The effect of the shot noise is investigated and the limitations of the zone plate holography are reported.

  2. Positron emission zone plate holography for particle tracking

    International Nuclear Information System (INIS)

    Gundogdu, O.

    2006-01-01

    Positron Emission Particle Tracking (PEPT) is a powerful non-invasive technique that has been used extensively for tracking a single particle. In this paper, we present a study of zone plate holography method in order to track multiple particles, mainly two particles. The main aim is to use as small number of events as possible in the order to make it possible to track particles in fast moving industrial systems. A zone plate with 100% focal efficiency is simulated and applied to the Positron Emission Tomography (PET) data for multiple particle tracking. A simple trajectory code was employed to explore the effects of the nature of the experimental trajectories. A computer holographic reconstruction code that simulates optical reconstruction was developed. The different aspects of the particle location, particle activity ratios for enabling tagging of particles and zone plate and hologram locations are investigated. The effect of the shot noise is investigated and the limitations of the zone plate holography are reported

  3. Parametric Study on the Characteristics of Multiphase Laminar Flow with Density Difference in Various Microchannels

    International Nuclear Information System (INIS)

    Paek, Seung Ho; Kim, Dong Sung; Choi, Young Ki

    2009-01-01

    In this paper, we have performed a parametric study on the characteristics of multiphase laminar flow with density difference in various microchannels. The interface between multiphase fluids is rotated by the gravitational forces induced by density difference. The numerical simulations were carried out via commercial CFD package to study the characteristics of multiphase laminar flow. The results of the numerical simulations in this study were verified by comparing with the previously reported experimental results in the literature. We have also proposed a new dimensionless relationship between dimensionless rotation angle of interface and dimensionless parameters are proposed for square microchannels with various aspect ratios. The dimensionless relationship could be widely applied to the reliable design of various microfluidic devices dealing with multiphase laminar flow

  4. Radiographic control of mineral fibre-reinforced cement plates

    International Nuclear Information System (INIS)

    Domanus, J.C.; Moeller Jensen, L.

    1980-03-01

    The usefulnes of the radiographic technique in the examination of Spinrock fibres reinforced cement plates was investigated with soft X-rays. A preliminary investigation has shown that soft X-rays are most suitable for radiography of cement plates, and therefore a 50 kV X-ray machine with a 0.5 mm focus and beryllium window X-ray tube was used througout the investigation. X-ray films of different speed and graininess were used, and it was proved that a relatively fast Kodak Industrex D film can produce radiographs of adequate quality. An Agfa-Gevaert Structurix IC paper can also be used. (author)

  5. Localized electric field induced transition and miniaturization of two-phase flow patterns inside microchannels.

    Science.gov (United States)

    Sharma, Abhinav; Tiwari, Vijeet; Kumar, Vineet; Mandal, Tapas Kumar; Bandyopadhyay, Dipankar

    2014-10-01

    Strategic application of external electrostatic field on a pressure-driven two-phase flow inside a microchannel can transform the stratified or slug flow patterns into droplets. The localized electrohydrodynamic stress at the interface of the immiscible liquids can engender a liquid-dielectrophoretic deformation, which disrupts the balance of the viscous, capillary, and inertial forces of a pressure-driven flow to engender such flow morphologies. Interestingly, the size, shape, and frequency of the droplets can be tuned by varying the field intensity, location of the electric field, surface properties of the channel or fluids, viscosity ratio of the fluids, and the flow ratio of the phases. Higher field intensity with lower interfacial tension is found to facilitate the oil droplet formation with a higher throughput inside the hydrophilic microchannels. The method is successful in breaking down the regular pressure-driven flow patterns even when the fluid inlets are exchanged in the microchannel. The simulations identify the conditions to develop interesting flow morphologies, such as (i) an array of miniaturized spherical or hemispherical or elongated oil drops in continuous water phase, (ii) "oil-in-water" microemulsion with varying size and shape of oil droplets. The results reported can be of significance in improving the efficiency of multiphase microreactors where the flow patterns composed of droplets are preferred because of the availability of higher interfacial area for reactions or heat and mass exchange. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Treatment of Industrial Liquid Waste of Steel Plating by Coagulation-Flocculation Using Sodium Biphosphate

    International Nuclear Information System (INIS)

    Subiarto; Herlan Martono

    2007-01-01

    Research about treatment of industrial liquid waste of steel plating by coagulation-flocculation using sodium biphosphate have been conducted. The purpose of the treatment was the content reduction of Cr, Ni, and Cu in the liquid waste, so that produced effluent with Cr, Ni, and Cu content until they laid under mutual standard. The variables studied in this process were the solution pH, the coagulant/waste volume comparison, the speed of the fast stirring, and the time of the fast stirring. Optimum separation efficiency on coagulation-flocculation process of liquid waste of steel plating using sodium biphosphate at the condition of solution ph 9, coagulant/waste volume comparation 1.50, the speed of the fast stirring 400 rpm, and the time of fast stirring is 5 minute. Low stirring was conducted at 60 rpm for 60 minute. The yields of optimum separation efficiency in this condition were 99.48 % for Cr, 99.51 % for Ni, and 99.03 % for Cu. (author)

  7. Flow Boiling in a Micro-Channel Coated With Carbon Nanotubes

    OpenAIRE

    Khanikar, Vikash; Mudawar, Issam; Fisher, Timothy

    2009-01-01

    This study examines the heat transfer enhancement attributes of carbon nanotubes (CNTs) applied to the bottom wall of a shallow rectangular micro-channel. Using deionized water as working fluid, experiments were performed with both a bare copper bottom wall and a CNT-coated copper wall. Boiling curves were generated for both walls, aided by high-speed video analysis of interfacial features. CNT arrays promoted earlier, abundant and intense bubble nucleation at low mass velocities, consistent ...

  8. Optimal Design of Silicon-based Chips for Piezo-induced Ultrasound Resonances in Embedded Microchannels

    DEFF Research Database (Denmark)

    Garofalo, F.; Laurell, T.; Bruus, Henrik

    2015-01-01

    constituting the device (the piezo transducer, the silicon walls, the fluid-filled microchannel, and the glass lid) allows for the introduction of the weak formulation used in the finite element discretization of the equations describing the system in its oscillatory regime. Additionally, the knowledge...... of the Lagrangian density leads to the derivation of the correct structure of the Hamiltonian density, i.e. the energy density, which is important for the quantification of the energy content of the whole system and its individual parts. Specifically, the energy content of the embedded microchannel is quantified...... by means of the acoustofluidic yield η defined as the ratio between the energy in the channel and the total energy. From the standpoint of acoustophoretic application, the introduction of the acoustophoretic mean orientation allows us to identify the frequencies for which an acoustophoretic effect, i...

  9. VOF Modeling and Analysis of the Segmented Flow in Y-Shaped Microchannels for Microreactor Systems

    Directory of Open Access Journals (Sweden)

    Xian Wang

    2013-01-01

    Full Text Available Microscaled devices receive great attention in microreactor systems for producing high renewable energy due to higher surface-to-volume, higher transport rates (heat or/and mass transfer rates, and other advantages over conventional-size reactors. In this paper, the two-phase liquid-liquid flow in a microchannel with various Y-shaped junctions has been studied numerically. Two kinds of immiscible liquids were injected into a microchannel from the Y-shaped junctions to generate the segment flow mode. The segment length was studied. The volume of fluid (VOF method was used to track the liquid-liquid interface and the piecewise-liner interface construction (PLIC technique was adopted to get a sharp interface. The interfacial tension was simulated with continuum surface force (CSF model and the wall adhesion boundary condition was taken into consideration. The simulated flow pattern presents consistence with our experimental one. The numerical results show that a segmented flow mode appears in the main channel. Under the same inlet velocities of two liquids, the segment lengths of the two liquids are the same and depend on the inclined angles of two lateral channels. The effect of inlet velocity is studied in a typical T-shaped microchannel. It is found that the ratio between the lengths of two liquids is almost equal to the ratio between their inlet velocities.

  10. A Flexible Ascorbic Acid Fuel Cell with a Microchannel Fabricated using MEMS Techniques

    Science.gov (United States)

    Mogi, Hiroshi; Fukushi, Yudai; Koide, Syohei; Sano, Ryohei; Sasaki, Tsubasa; Nishioka, Yasushiro

    2013-12-01

    We fabricated a miniature ascorbic acid fuel cells equipped with a microchannel for the circulation of ascorbic acid (AA) solution using micro electronic mechanical system techniques. The fuel cell was fabricated on a flexible polyimide substrate, and its porous carbon-coated aluminium (Al) electrodes of 2.8 mm in width and 11 mm in length were formed using photolithography and screen-printing techniques. The porous carbon was deposited by screen-printing of carbon-black ink on the Al electrode surfaces in order to increase the effective electrode surface area and to absorb more enzymes on the cathode surface. The microchannel with a depth of 200 μm was fabricated using a hot-embossing technique. A maximum power of 0.60 μW at 0.58 V that corresponds to a power density of 1.83 μW/cm2 was realized by introducing a 200 mM concentrated AA solution at room temperature.

  11. Continuous particle separation in a serpentine microchannel via negative and positive dielectrophoretic focusing

    International Nuclear Information System (INIS)

    Church, Christopher; Zhu, Junjie; Nieto, Juan; Keten, Gyunay; Ibarra, Erl; Xuan, Xiangchun

    2010-01-01

    Dielectrophoresis (DEP) has been widely used to focus and separate cells and particles in microfluidic devices. This work first demonstrates negative and positive dielectrophoretic focusing of particles in a serpentine microchannel by changing only the electric conductivity of the suspending fluid. Due to the channel turn-induced dielectrophoretic force, particles are focused to either the centerline or the sidewalls of the channel when their electric conductivity is lower (i.e. negative DEP) or higher (i.e. positive DEP) than that of the fluid. These distinctive dielectrophoretic focusing phenomena in a serpentine microchannel are then combined to implement a continuous separation between particles of different sizes and electric conductivities. Such separation eliminates the fabrication of in-channel microelectrodes or micro-insulators that are typically required in DEP-based separation techniques. A numerical model is also developed to predict the particle motion, and the simulation results agree reasonably with the observed particle focusing and separation behaviors.

  12. Numerical Study of Surfactant Dynamics during Emulsification in a T-Junction Microchannel.

    Science.gov (United States)

    Riaud, Antoine; Zhang, Hao; Wang, Xueying; Wang, Kai; Luo, Guangsheng

    2018-04-18

    Microchannel emulsification requires large amounts of surfactant to prevent coalescence and improve emulsions lifetime. However, most numerical studies have considered surfactant-free mixtures as models for droplet formation in microchannels, without taking into account the distribution of surfactant on the droplet surface. In this paper, we investigate the effects of nonuniform surfactant coverage on the microfluidic flow pattern using an extended lattice-Boltzmann model. This numerical study, supported by micro-particle image velocimetry experiments, reveals the likelihood of uneven distribution of surfactant during the droplet formation and the appearance of a stagnant cap. The Marangoni effect affects the droplet breakup by increasing the shear rate. According to our results, surfactant-free and surfactant-rich droplet formation processes are qualitatively different, such that both the capillary number and the Damköhler number should be considered when modeling the droplet generation in microfluidic devices. The limitations of traditional volume and pressure estimation methods for determining the dynamic interfacial tension are also discussed on the basis of the simulation results.

  13. Coupling between electroosmotically driven flow and bipolar faradaic depolarization processes in electron-conducting microchannels

    NARCIS (Netherlands)

    Qian, S.Z.; Duval, J.F.L.

    2006-01-01

    A quantitative theory is proposed for the analysis of steady electroosmotically driven flows within conducting cylindrical microchannels. Beyond a threshold value of the electric field applied in the electrolyte Solution and parallel to the conducting surface, electrochemical oxidation and reduction

  14. Assessment of residual life of fast breeder test reactor

    International Nuclear Information System (INIS)

    Srinivasan, G.

    2016-01-01

    The Fast Breeder Test Reactor (FBTR) is a loop type sodium cooled fast reactor and has been in operation since 1985. As a part of regulatory requirement for relicensing, residual life assessment had to be carried out. The systems are made of SS 316, and designed for creep and fatigue. The design life for creep is 100,000 h at 550°C. The design fatigue cycle for operation from shutdown to full power varies from component to component. In general, most of the components are designed for 2000 cycles. The reactor has operated mostly below the design temperatures. It is seen that enough creep-fatigue life is available for the non-replaceable, permanent components. The residual life was found to be governed by the residual ductility of the Grid Plate supporting the core after neutron irradiation. Fast flux measurements were carried out at the grid plate location. Samples were irradiated and tensile tested. Results indicate the allowable dpa for a 10% residual ductility criterion as 4.37. This gave a residual life of ~ 6 Effective Full Power Years for the reactor as of Feb 2012. Measures to reduce the neutron dose on the grid plate are being taken. (author)

  15. Ultrafast Laser Engraving Method to Fabricate Gravure Plate for Printed Metal-Mesh Touch Panel

    Directory of Open Access Journals (Sweden)

    Weiyuan Chen

    2015-10-01

    Full Text Available In order to engrave gravure plate with fine lines structures, conventional art used lithography with dry/wet etching. Lithography with dry/wet etching method allows to engrave lines with smooth concave shape, but its disadvantages include difficulty in controlling aspect ratio, high and uniform in large size process, substrate material limitation due to etching solution availability, and process complexity. We developed ultra-fast laser technology to directly engrave a stainless plate, a gravure plate, to be used for fabricating 23 in. metal-mesh touch panel by gravure offset printing process. The technology employs high energy pulse to ablate materials from a substrate. Because the ultra-fast laser pulse duration is shorter than the energy dissipation time between material lattices, there is no heating issue during the ablation process. Therefore, no volcano-type protrusion on the engraved line edges occurs, leading to good printing quality. After laser engraving, we then reduce surface roughness of the gravure plate using electro-polishing process. Diamond like carbon (DLC coating layer is then added onto the surface to increase scratch resistance. We show that this procedure can fabricate gravure plate for gravure offset printing process with minimum printing linewidth 10.7 μm. A 23 in. metal-mesh pattern was printed using such gravure plate and fully functional touch panel was demonstrated in this work.

  16. Fast neutron scintillation spectrometer in a heavy ion accelerator

    International Nuclear Information System (INIS)

    Blinov, M.V.; Gavrilov, B.P.; Ivannikova, L.L.; Kozulin, Eh.M.; Mozhaev, A.N.; Tyurin, G.P.

    1984-01-01

    Scintillation fast neutron spectrometer in a heavy ion accelerator is described in short. The spectrometer is used to measure characteristics of neutrons emitted in heavy ion interaction with different nuclei. Experiment was performed on the base of particle flight from 0.7 up to 2 m. Within the angle range of 0-150 deg. The technique is based on recording of two-dimensional neutron spectra obtained due to combination of the time-of-flight method and the method of recoil proton energy detection. Two measuring channels were used in the spectrometer. Each channel comprise both amplitude and time tracks. Detector on the base microchannel plates (MCP) generated a signal in passing the next ion bunch was used in order to obtain the time mark. Data from the scintillation block are recorded with respect to three parameters: recoil proton amplitude, time of neutron or γ-quantum arrival in respect of MCP-sensor pulse. Apparatus is carried out within the CAMAC standard. The spectrometer calibration within the 1-20 MeV neutron range was conducted in the Van-de-Graaf accelerator, and for higher energies - with the use of lightguides. Spectrometer time resolution for neutron energies of 0.5-50 MeV constituted 1.5-1.8 ns. The above measuring of neutron spectra from 1 /H2C+ 181 Ta and sup(20, 22)Ne+sup(181)Ta reaction have revealed a possibility of the experiment organization in heavy ion accelerators in the presence of strong neutron and γ-fields. Organization of multi-dimensional analysis combining two methods allows one to separate accelerator cycle, a region of the most reliable information, free of a low-energy gamma background and limited both by a dynamic threshold and a region of permissible energy values

  17. Modelling refrigerant distribution in microchannel evaporators

    DEFF Research Database (Denmark)

    Brix, Wiebke; Kærn, Martin Ryhl; Elmegaard, Brian

    2009-01-01

    of the refrigerant distribution is carried out for two channels in parallel and for two different cases. In the first case maldistribution of the inlet quality into the channels is considered, and in the second case a non-uniform airflow on the secondary side is considered. In both cases the total mixed superheat...... out of the evaporator is kept constant. It is shown that the cooling capacity of the evaporator is reduced significantly, both in the case of unevenly distributed inlet quality and for the case of non-uniform airflow on the outside of the channels.......The effects of refrigerant maldistribution in parallel evaporator channels on the heat exchanger performance are investigated numerically. For this purpose a 1D steady state model of refrigerant R134a evaporating in a microchannel tube is built and validated against other evaporator models. A study...

  18. Eulerian-Eulerian two-phase numerical simulation of nanofluid laminar forced convection in a microchannel

    International Nuclear Information System (INIS)

    Kalteh, Mohammad; Abbassi, Abbas; Saffar-Avval, Majid; Harting, Jens

    2011-01-01

    In this paper, laminar forced convection heat transfer of a copper-water nanofluid inside an isothermally heated microchannel is studied numerically. An Eulerian two-fluid model is considered to simulate the nanofluid flow inside the microchannel and the governing mass, momentum and energy equations for both phases are solved using the finite volume method. For the first time, the detailed study of the relative velocity and temperature of the phases are presented and it has been observed that the relative velocity and temperature between the phases is very small and negligible and the nanoparticle concentration distribution is uniform. However, the two-phase modeling results show higher heat transfer enhancement in comparison to the homogeneous single-phase model. Also, the heat transfer enhancement increases with increase in Reynolds number and nanoparticle volume concentration as well as with decrease in the nanoparticle diameter, while the pressure drop increases only slightly.

  19. Large-scale performance studies of the Resistive Plate Chamber fast tracker for the ATLAS 1st-level muon trigger

    CERN Document Server

    Cattani, G; The ATLAS collaboration

    2009-01-01

    In the ATLAS experiment, Resistive Plate Chambers provide the first-level muon trigger and bunch crossing identification over large area of the barrel region, as well as being used as a very fast 2D tracker. To achieve these goals a system of about ~4000 gas gaps operating in avalanche mode was built (resulting in a total readout surface of about 16000 m2 segmented into 350000 strips) and is now fully operational in the ATLAS pit, where its functionality has been widely tested up to now using cosmic rays. Such a large scale system allows to study the performance of RPCs (both from the point of view of gas gaps and readout electronics) with unprecedented sensitivity to rare effects, as well as providing the means to correlate (in a statistically significant way) characteristics at production sites with performance during operation. Calibrating such a system means fine tuning thousands of parameters (involving both front-end electronics and gap voltage), as well as constantly monitoring performance and environm...

  20. Method for producing components with internal architectures, such as micro-channel reactors, via diffusion bonding sheets

    Science.gov (United States)

    Alman, David E [Corvallis, OR; Wilson, Rick D [Corvallis, OR; Davis, Daniel L [Albany, OR

    2011-03-08

    This invention relates to a method for producing components with internal architectures, and more particularly, this invention relates to a method for producing structures with microchannels via the use of diffusion bonding of stacked laminates. Specifically, the method involves weakly bonding a stack of laminates forming internal voids and channels with a first generally low uniaxial pressure and first temperature such that bonding at least between the asperites of opposing laminates occurs and pores are isolated in interfacial contact areas, followed by a second generally higher isostatic pressure and second temperature for final bonding. The method thereby allows fabrication of micro-channel devices such as heat exchangers, recuperators, heat-pumps, chemical separators, chemical reactors, fuel processing units, and combustors without limitation on the fin aspect ratio.

  1. A model of breakdown in parallel-plate detectors

    International Nuclear Information System (INIS)

    Fonte, P.

    1996-01-01

    Parallel-plate avalanche chambers (PPAC's) have many desirable properties, such as a fast, large area particle detector. However, the maximum gain is limited by a form of violent breakdown that limits the usefulness of this detector, despite its other evident qualities. The exact nature of this phenomenon is not yet sufficiently clear to sustain possible improvements. A previous experimental study is complemented in the present work by a quantitative model of the breakdown phenomenon in PPAC's, based on the streamer theory. The model reproduces well the peculiar behavior of the external current observed in PPAC's and resistive-plate chambers. Other breakdown properties measured in PPAC's are also well reproduced

  2. Heater Chip with Different Microchannels Geometries for a Low Pressure Free Molecular Micro-Resistojet

    NARCIS (Netherlands)

    Cordeiro Guerrieri, D.; de Athayde Costa e Silva, M.; Zandbergen, B.T.C.; Cervone, A.

    2016-01-01

    This paper presents a dynamic system approach for the modeling of fluid flow in microchannels to be used in thrust control applications. A micro-resistojet fabricated using MEMS (Microelectromechanical Systems) technology has been selected for the analysis. The device operates by vaporizing a liquid

  3. Simulation and prototyping of 2 m long resistive plate chambers for detection of fast neutrons and multi-neutron event identification

    Energy Technology Data Exchange (ETDEWEB)

    Elekes, Z., E-mail: z.elekes@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Bemmerer, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Caesar, C. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Technische Universität Darmstadt, Darmstadt (Germany); Cowan, T.C. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Hehner, J.; Heil, M. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Kempe, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Rossi, D. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Röder, M. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Simon, H. [GSI Helmholtzzentrumfür Schwerionenforschung, Darmstadt (Germany); Sobiella, M.; Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Reinhardt, T. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universität Dresden, Dresden (Germany); Wagner, A.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Zilges, A. [Universität zu Köln, Köln (Germany); Zuber, K. [Technische Universität Dresden, Dresden (Germany)

    2013-02-11

    Resistive plate chamber (RPC) prototypes of 2 m length were simulated and built. The experimental tests using a 31 MeV electron beam, discussed in details, showed an efficiency higher than 90% and an excellent time resolution of around σ=100ps. Furthermore, comprehensive simulations were performed by GEANT4 toolkit in order to study the possible use of these RPCs for fast neutron (200 MeV–1 GeV) detection and multi-neutron event identification. The validation of simulation parameters was carried out via a comparison to experimental data. A possible setup for invariant mass spectroscopy of multi-neutron emission is presented and the characteristics are discussed. The results show that the setup has a high detection efficiency. Its capability of determining the momentum of the outgoing neutrons and reconstructing the relative energy between the fragments from nuclear reactions is demonstrated for different scenarios.

  4. Optical timing receiver for the NASA laser ranging system. Part I. Constant-fraction discriminator

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1975-01-01

    Position-resolution capabilities of the NASA laser ranging system are essentially determined by time-resolution capabilities of its optical timing receiver. The optical timing receiver consists of a fast photoelectric device, primarily a standard of microchannel-plate-type photomultiplier or an avalanche photodiode detector, a timing discriminator, a high-precision time-interval digitizer, and a signal-processing system. The time-resolution capabilities of the receiver are determined by the photoelectron time spread of the photoelectric device, the time walk and resolution characteristics of the timing discriminator, and the time-interval digitizer. It is thus necessary to evaluate available fast photoelectronic devices with respect to their time-resolution capabilities, and to design a very low time walk timing discriminator and a high-precision time digitizer which will be used in the laser ranging system receiver. (auth)

  5. Fine 3D neutronic characterization of a gas-cooled fast reactor based on plate-type sub-assemblies

    International Nuclear Information System (INIS)

    Bosq, J. C.; Peneliau, Y.; Rimpault, G.; Vanier, M.

    2006-01-01

    CEA neutronic studies have allowed the definition of a first 2400 MWth reference gas-cooled fast reactor core using plate-type sub-assemblies, for which the main neutronic characteristics were calculated by the so-called ERANOS 'design calculation scheme' relying on several method approximations. The last stage has consisted in a new refine characterization, using the reference calculation scheme, in order to confirm the impact of the approximations of the design route. A first core lay-out taking into account control rods was proposed and the reactivity penalty due to the control rod introduction in this hexagonal core lay-out was quantified. A new adjusted core was defined with an increase of the plutonium content. This leads to a significant decrease of the breeding gain which needs to be recovered in future design evolutions in order to achieve the self breeding goal. Finally, the safety criteria associated to the control rods were calculated with a first estimation of the uncertainties. All these criteria are respected, even if the safety analysis of GFR concepts and the determination of these uncertainties should be further studied and improved. (authors)

  6. Enhancing heat transfer in microchannel heat sinks using converging flow passages

    International Nuclear Information System (INIS)

    Dehghan, Maziar; Daneshipour, Mahdi; Valipour, Mohammad Sadegh; Rafee, Roohollah; Saedodin, Seyfolah

    2015-01-01

    Highlights: • The fluid flow and conjugate heat transfer in microchannel heat sinks are studied. • The Poiseuille and Nusselt numbers are presented for width-tapered MCHS. • Converging walls are found to enhance the thermal performance of MCHS. • The optimum performance of MCHS for fixed inlet and outlet pressures is discussed. • For the optimum configuration, the pumping power is reduced up to 75%. - Abstract: Constrained fluid flow and conjugate heat transfer in microchannel heat sinks (MCHS) with converging channels are investigated using the finite volume method (FVM) in the laminar regime. The maximum pressure of the MCHS loop is assumed to be limited due to constructional or operational conditions. Results show that the Poiseuille number increases with increased tapering, while the required pumping power decreases. Meanwhile, the Nusselt number increases with tapering as well as the convection heat transfer coefficient. The MCHS having the optimum heat transfer performance is found to have a width-tapered ratio equal to 0.5. For this tapering configuration and at the maximum pressure constraint of 3000 Pa, the pumping power reduces by a factor of 4 while the overall heat removal rate is kept fixed in comparison with a straight channel

  7. Slow waves in microchannel metal waveguides and application to particle acceleration

    Directory of Open Access Journals (Sweden)

    L. C. Steinhauer

    2003-06-01

    Full Text Available Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong exchange of energy can occur between a beam of charged particles and this slow-waveguide mode. Moreover, the energy exchange can be sustained over a distance limited only by the natural damping of the wave. This makes the microchannel metal waveguide an attractive possibility for high-gradient electron laser acceleration because the wave can be directly energized by a long-wavelength laser. Indeed the frequency of CO_{2} lasers lies at a fortuitous wavelength that produces a strong laser-particle interaction in a channel of reasonable macroscopic size (e.g., ∼0.6  mm. The dispersion properties including phase velocity and damping for the slow wave are developed. The performance and other issues related to laser accelerator applications are discussed.

  8. Slow waves in microchannel metal waveguides and application to particle acceleration

    Science.gov (United States)

    Steinhauer, L. C.; Kimura, W. D.

    2003-06-01

    Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong exchange of energy can occur between a beam of charged particles and this slow-waveguide mode. Moreover, the energy exchange can be sustained over a distance limited only by the natural damping of the wave. This makes the microchannel metal waveguide an attractive possibility for high-gradient electron laser acceleration because the wave can be directly energized by a long-wavelength laser. Indeed the frequency of CO2 lasers lies at a fortuitous wavelength that produces a strong laser-particle interaction in a channel of reasonable macroscopic size (e.g., ˜0.6 mm). The dispersion properties including phase velocity and damping for the slow wave are developed. The performance and other issues related to laser accelerator applications are discussed.

  9. Optimum thermal design of microchannel heat sink with triangular reentrant cavities

    International Nuclear Information System (INIS)

    Xia Guodong; Chai Lei; Wang Haiyan; Zhou Mingzheng; Cui Zhenzhen

    2011-01-01

    The effect of geometric parameters on water flow and heat transfer characteristics in microchannel heat sink with triangular reentrant cavities is numerically investigated. A three-dimensional laminar flow model, consisting of Navier-Stokes equations and energy conservation equation, with the conjugate heat transfer between the silicon base and water taken into consideration is solved numerically. In order to find the optimum geometric parameters, four variables, representing the distance and geometry of the triangular reentrant cavity, are designed. It is found that the vortices in the triangular reentrant cavities lead to chaotic advection and can greatly enhance the convective fluid mixing. The thermal and hydraulic boundary layers are interrupted and the repeated developing flow enhances heat transfer in the constant cross-section segment. Furthermore, the effects of the four design variables on heat transfer augmentation and pressure drop penalty are investigated depending on different Reynolds numbers by using the simulated annealing method. Based on the thermal enhancement factor performance maps, the optimal geometric parameters are obtained in principle. - Research highlights: → The microchannels with different triangular reentrant cavities are numerically investigated. → The heat transfer enhancement attributes to fluid mixing and redeveloped thermal boundary layers. → The optimal distance and geometry of the triangular reentrant cavity are obtained in principle.

  10. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1978-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single phtoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems. 16 refs

  11. Investigation of high frequency external perturbation effects on flow in a T-shape microchannel by μLIF technique

    Science.gov (United States)

    Kravtsova, A. Yu; Meshalkin, Yu E.; Bilsky, A. V.

    2017-11-01

    Investigation of high frequency external perturbation effect on flow inside T-shape microchannel was examined. In-phase pulsations of different frequencies were added to both inlets of the T-shaped microchannel to study mixing by means of Micro Laser Induced Fluorescence (μLIF) technique. For all flow regimes studied, mixing enhancement was obtained. Significant enhancement can be achieved at the beginning of the outlet channel operating in steady asymmetric regime (Re=186) by forcing at certain frequency ranges (f = 500Hz, f = 800Hz). Mixing suppression was also observed for two flow regimes (Re = 400, f = 1000Hz) and (Re = 120, f = 700Hz).

  12. Coatings for fast breeder reactor components

    International Nuclear Information System (INIS)

    Johnson, R.N.

    1984-04-01

    Several types of metallurgical coatings are used in the unique environments of the fast breeder reactor. Most of the coatings have been developed for tribological applications, but some also serve as corrosion barriers, diffusion barriers, or radionuclide traps. The materials that have consistently given the best performance as tribological coatings in the breeder reactor environments have been coatings based on chromium carbide, nickel aluminide, or Tribaloy 700 (a nickel-base hard-facing alloy). Other coatings that have been qualified for limited applications include chromium plating for low temperature galling protection and nickel plating for radionuclide trapping

  13. Coaxial nozzle-assisted 3D bioprinting with built-in microchannels for nutrients delivery.

    Science.gov (United States)

    Gao, Qing; He, Yong; Fu, Jian-zhong; Liu, An; Ma, Liang

    2015-08-01

    This study offers a novel 3D bioprinting method based on hollow calcium alginate filaments by using a coaxial nozzle, in which high strength cell-laden hydrogel 3D structures with built-in microchannels can be fabricated by controlling the crosslinking time to realize fusion of adjacent hollow filaments. A 3D bioprinting system with a Z-shape platform was used to realize layer-by-layer fabrication of cell-laden hydrogel structures. Curving, straight, stretched or fractured filaments can be formed by changes to the filament extrusion speed or the platform movement speed. To print a 3D structure, we first adjusted the concentration and flow rate of the sodium alginate and calcium chloride solution in the crosslinking process to get partially crosslinked filaments. Next, a motorized XY stages with the coaxial nozzle attached was used to control adjacent hollow filament deposition in the precise location for fusion. Then the Z stage attached with a Z-shape platform moved down sequentially to print layers of structure. And the printing process always kept the top two layers fusing and the below layers solidifying. Finally, the Z stage moved down to keep the printed structure immersed in the CaCl2 solution for complete crosslinking. The mechanical properties of the resulting fused structures were investigated. High-strength structures can be formed using higher concentrations of sodium alginate solution with smaller distance between adjacent hollow filaments. In addition, cell viability of this method was investigated, and the findings show that the viability of L929 mouse fibroblasts in the hollow constructs was higher than that in alginate structures without built-in microchannels. Compared with other bioprinting methods, this study is an important technique to allow easy fabrication of lager-scale organs with built-in microchannels. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Heat Transfer and Pressure Drop Characteristics in Straight Microchannel of Printed Circuit Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Jang-Won Seo

    2015-05-01

    Full Text Available Performance tests were carried out for a microchannel printed circuit heat exchanger (PCHE, which was fabricated with micro photo-etching and diffusion bonding technologies. The microchannel PCHE was tested for Reynolds numbers in the range of 100‒850 varying the hot-side inlet temperature between 40 °C–50 °C while keeping the cold-side temperature fixed at 20 °C. It was found that the average heat transfer rate and heat transfer performance of the countercurrrent configuration were 6.8% and 10%‒15% higher, respectively, than those of the parallel flow. The average heat transfer rate, heat transfer performance and pressure drop increased with increasing Reynolds number in all experiments. Increasing inlet temperature did not affect the heat transfer performance while it slightly decreased the pressure drop in the experimental range considered. Empirical correlations have been developed for the heat transfer coefficient and pressure drop factor as functions of the Reynolds number.

  15. Performance enhancement of PV cells through micro-channel cooling

    Directory of Open Access Journals (Sweden)

    Muzaffar Ali

    2015-11-01

    Full Text Available Efficiency of a PV cell is strongly dependent on its surface temperature. The current study is focused to achieve maximum efficiency of PV cells even in scorching temperatures in hot climates like Pakistan where the cell surface temperatures can even rise up to around 80 ℃. The study includes both the CFD and real time experimental investigations of a solar panel using micro channel cooling. Initially, CFD analysis is performed by developing a 3D model of a Mono-Crystalline cell with micro-channels to analyze cell surface temperature distribution at different irradiance and water flow rates. Afterwards, an experimental setup is developed for performance investigations under the real conditions of an open climate of a Pakistan's city, Taxila. Two 35W panels are manufactured for the experiments; one is based on the standard manufacturing procedure while other cell is developed with 4mm thick aluminum sheet having micro-channels of cross-section of 1mm by 1mm. The whole setup also includes different sensors for the measurement of solar irradiance, cell power, surface temperature and water flow rates. The experimental results show that PV cell surface temperature drop of around 15 ℃ is achieved with power increment of around 14% at maximum applied water flow rate of 3 LPM. Additionally, a good agreement is also found between CFD and experimental results. Therefore, that study clearly shows that a significant performance improvement of PV cells can be achieved through the proposed cell cooling technique.

  16. Ionizing device comprising a microchannel electron multiplier with secondary electron emission

    International Nuclear Information System (INIS)

    Chalmeton, Vincent.

    1974-01-01

    The present invention relates to a ionizing device comprising a microchannel electron multiplier involving secondary electron emission as a means of ionization. A system of electrodes is used to accelerate said electrons, ionize the gas and extract the ions from thus created plasma. Said ionizer is suitable for bombarding the target in neutron sources (target of the type of nickel molybdenum coated with tritiated titanium or with a tritium deuterium mixture) [fr

  17. In-channel electrochemical detection in the middle of microchannel under high electric field.

    Science.gov (United States)

    Kang, Chung Mu; Joo, Segyeong; Bae, Je Hyun; Kim, Yang-Rae; Kim, Yongseong; Chung, Taek Dong

    2012-01-17

    We propose a new method for performing in-channel electrochemical detection under a high electric field using a polyelectrolytic gel salt bridge (PGSB) integrated in the middle of the electrophoretic separation channel. The finely tuned placement of a gold working electrode and the PGSB on an equipotential surface in the microchannel provided highly sensitive electrochemical detection without any deterioration in the separation efficiency or interference of the applied electric field. To assess the working principle, the open circuit potentials between gold working electrodes and the reference electrode at varying distances were measured in the microchannel under electrophoretic fields using an electrically isolated potentiostat. In addition, "in-channel" cyclic voltammetry confirmed the feasibility of electrochemical detection under various strengths of electric fields (∼400 V/cm). Effective separation on a microchip equipped with a PGSB under high electric fields was demonstrated for the electrochemical detection of biological compounds such as dopamine and catechol. The proposed "in-channel" electrochemical detection under a high electric field enables wider electrochemical detection applications in microchip electrophoresis.

  18. Simulation of Micro-Channel and Micro-Orifice Flow Using Lattice Boltzmann Method with Langmuir Slip Model

    Directory of Open Access Journals (Sweden)

    A. R. Rahmati

    2016-12-01

    Full Text Available Because of its kinetic nature and computational advantages, the Lattice Boltzmann method (LBM has been well accepted as a useful tool to simulate micro-scale flows. The slip boundary model plays a crucial role in the accuracy of solutions for micro-channel flow simulations. The most used slip boundary condition is the Maxwell slip model. The results of Maxwell slip model are affected by the accommodation coefficient significantly, but there is not an explicitly relationship between properties at wall and accommodation coefficient. In the present wok, Langmuir slip model is used beside LBM to simulate micro-channel and micro-orifice flows. Slip velocity and nonlinear pressure drop profiles are presented as two major effects in such flows. The results are in good agreement with existing results in the literature.

  19. Process for making unsaturated hydrocarbons using microchannel process technology

    Science.gov (United States)

    Tonkovich, Anna Lee [Dublin, OH; Yuschak, Thomas [Lewis Center, OH; LaPlante, Timothy J [Columbus, OH; Rankin, Scott [Columbus, OH; Perry, Steven T [Galloway, OH; Fitzgerald, Sean Patrick [Columbus, OH; Simmons, Wayne W [Dublin, OH; Mazanec, Terry Daymo, Eric

    2011-04-12

    The disclosed invention relates to a process for converting a feed composition comprising one or more hydrocarbons to a product comprising one or more unsaturated hydrocarbons, the process comprising: flowing the feed composition and steam in contact with each other in a microchannel reactor at a temperature in the range from about 200.degree. C. to about 1200.degree. C. to convert the feed composition to the product, the process being characterized by the absence of catalyst for converting the one or more hydrocarbons to one or more unsaturated hydrocarbons. Hydrogen and/or oxygen may be combined with the feed composition and steam.

  20. Hermitian Mindlin Plate Wavelet Finite Element Method for Load Identification

    Directory of Open Access Journals (Sweden)

    Xiaofeng Xue

    2016-01-01

    Full Text Available A new Hermitian Mindlin plate wavelet element is proposed. The two-dimensional Hermitian cubic spline interpolation wavelet is substituted into finite element functions to construct frequency response function (FRF. It uses a system’s FRF and response spectrums to calculate load spectrums and then derives loads in the time domain via the inverse fast Fourier transform. By simulating different excitation cases, Hermitian cubic spline wavelets on the interval (HCSWI finite elements are used to reverse load identification in the Mindlin plate. The singular value decomposition (SVD method is adopted to solve the ill-posed inverse problem. Compared with ANSYS results, HCSWI Mindlin plate element can accurately identify the applied load. Numerical results show that the algorithm of HCSWI Mindlin plate element is effective. The accuracy of HCSWI can be verified by comparing the FRF of HCSWI and ANSYS elements with the experiment data. The experiment proves that the load identification of HCSWI Mindlin plate is effective and precise by using the FRF and response spectrums to calculate the loads.

  1. Regulating the Emission Spectrum of CsPbBr₃ from Green to Blue via Controlling the Temperature and Velocity of Microchannel Reactor.

    Science.gov (United States)

    Tang, Yong; Lu, Hanguang; Rao, Longshi; Li, Zongtao; Ding, Xinrui; Yan, Caiman; Yu, Binhai

    2018-03-02

    The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs) is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr₃ QDs with tunable spectrum. By adjusting the temperature and velocity of the microchannel reactor, the emission peaks of CsPbBr₃ QDs ranging from 520 nm to 430 nm were obtained, which is wider than that of QDs obtained in a traditional flask without changing halide component. The mechanism of photoluminescence (PL) spectral shift of CsPbBr₃ QDs was investigated, the result shows that the supersaturation control enabled by the superior mass and heat transfer performance in the microchannel is the key to achieve the wide range of PL spectrum, with only a change in the setting of the temperature controller required. The wide spectrum of CsPbBr₃ QDs can be applied to light-emitting diodes (LEDs), photoelectric sensors, lasers, etc.

  2. New Configurations of Micro Plate-Fin Heat Sink to Reduce Coolant Pumping Power

    Science.gov (United States)

    Rezania, A.; Rosendahl, L. A.

    2012-06-01

    The thermal resistance of heat exchangers has a strong influence on the electric power produced by a thermoelectric generator (TEG). In this work, a real TEG device is applied to three configurations of micro plate-fin heat sink. The distance between certain microchannels is varied to find the optimum heat sink configuration. The particular focus of this study is to reduce the coolant mass flow rate by considering the thermal resistances of the heat sinks and, thereby, to reduce the coolant pumping power in the system. The three-dimensional governing equations for the fluid flow and the heat transfer are solved using the finite-volume method for a wide range of pressure drop laminar flows along the heat sink. The temperature and the mass flow rate distribution in the heat sink are discussed. The results, which are in good agreement with previous computational studies, show that using suggested heat sink configurations reduces the coolant pumping power in the system.

  3. Automated and temperature-controlled micro-PIV measurements enabling long-term-stable microchannel acoustophoresis characterization

    DEFF Research Database (Denmark)

    Augustsson, Per; Barnkob, Rune; Wereley, Steven T.

    2011-01-01

    We present a platform for micro particle image velocimetry (μPIV), capable of carrying out full-channel, temperature-controlled, long-term-stable, and automated μPIV-measurement of microchannel acoustophoresis with uncertainties below 5% and a spatial resolution in the order of 20 μm. A method to...

  4. Hydrodynamic shrinkage of liquid CO2 Taylor drops in a straight microchannel

    Science.gov (United States)

    Qin, Ning; Wen, John Z.; Ren, Carolyn L.

    2018-03-01

    Hydrodynamic shrinkage of liquid CO2 drops in water under a Taylor flow regime is studied using a straight microchannel (length/width ~100). A general form of a mathematical model of the solvent-side mass transfer coefficient (k s) is developed first. Based on formulations of the surface area (A) and the volume (V) of a general Taylor drop in a rectangular microchannel, a specific form of k s is derived. Drop length and speed are experimentally measured at three specified positions of the straight channel, namely, immediately after drop generation (position 1), the midpoint of the channel (position 2) and the end of the channel (position 3). The reductions of drop length (L x , x  =  1, 2, 3) from position 1 to 2 and down to 3 are used to quantify the drop shrinkage. Using the specific model, k s is calculated mainly based on L x and drop flowing time (t). Results show that smaller CO2 drops produced by lower flow rate ratios ({{Q}LC{{O2}}}/{{Q}{{H2}O}} ) are generally characterized by higher (nearly three times) k s and Sherwood numbers than those produced by higher {{Q}LC{{O2}}}/{{Q}{{H2}O}} , which is essentially attributed to the larger effective portion of the smaller drop contributing in the mass transfer under same levels of the flowing time and the surface-to-volume ratio (~104 m-1) of all drops. Based on calculated pressure drops of the segmented flow in microchannel, the Peng-Robinson equation of state and initial pressures of drops at the T-junction in experiments, overall pressure drop (ΔP t) in the straight channel as well as the resulted drop volume change are quantified. ΔP t from position 1-3 is by average 3.175 kPa with a ~1.6% standard error, which only leads to relative drop volume changes of 0.3‰ to 0.52‰.

  5. Hydrodynamic shrinkage of liquid CO2 Taylor drops in a straight microchannel.

    Science.gov (United States)

    Qin, Ning; Wen, John; Ren, Carolyn L

    2018-01-16

    Hydrodynamic shrinkage of liquid CO2 drops in water under a Taylor flow regime is studied using a straight microchannel (length/width ~ 100). A general form of a mathematical model of the solvent-side mass transfer coefficient (ks) is developed first. Based on formulations of the surface area (A) and the volume (V) of a general Taylor drop in a rectangular microchannel, a specific form of ks is derived. Drop length and speed are experimentally measured at three specified positions of the straight channel, namely, immediately after drop generation (position 1), the midpoint of the channel (position 2) and the end of the channel (position 3). The reductions of drop length (Lx, x = 1, 2, 3) from position 1 to 2 and down to 3 are used to quantify the drop shrinkage. Using the specific model, ks is calculated mainly based on Lx and drop flowing time (t). Results show that smaller CO2 drops produced by lower flow rate ratios (QLCO2/QH2O) are generally characterized by higher (nearly three times) ks and Sherwood numbers than those produced by higher QLCO2/QH2O, which is essentially attributed to the larger effective portion of the smaller drop contributing in the mass transfer under same levels of the flowing time and the surface-to-volume ratio (~ 104 m-1) of all drops. Based on calculated pressure drops of the segmented flow in microchannel, the Peng-Robinson equation of state (EOS) and initial pressures of drops at the T-junction in experiments, overall pressure drop (ΔPt) in the straight channel as well as the resulted drop volume change are quantified. ΔPt from position 1 to 3 is by average 3.175 kPa with a ~1.6% standard error, which only leads to relative drop volume changes of 0.3‰ to 0.52‰. © 2018 IOP Publishing Ltd.

  6. Detector for imaging and dosimetry of laser-driven epithermal neutrons by alpha conversion

    Science.gov (United States)

    Mirfayzi, S. R.; Alejo, A.; Ahmed, H.; Wilson, L. A.; Ansell, S.; Armstrong, C.; Butler, N. M. H.; Clarke, R. J.; Higginson, A.; Notley, M.; Raspino, D.; Rusby, D. R.; Borghesi, M.; Rhodes, N. J.; McKenna, P.; Neely, D.; Brenner, C. M.; Kar, S.

    2016-10-01

    An epithermal neutron imager based on detecting alpha particles created via boron neutron capture mechanism is discussed. The diagnostic mainly consists of a mm thick Boron Nitride (BN) sheet (as an alpha converter) in contact with a non-borated cellulose nitride film (LR115 type-II) detector. While the BN absorbs the neutrons in the thermal and epithermal ranges, the fast neutrons register insignificantly on the detector due to their low neutron capture and recoil cross-sections. The use of solid-state nuclear track detectors (SSNTD), unlike image plates, micro-channel plates and scintillators, provide safeguard from the x-rays, gamma-rays and electrons. The diagnostic was tested on a proof-of-principle basis, in front of a laser driven source of moderated neutrons, which suggests the potential of using this diagnostic (BN+SSNTD) for dosimetry and imaging applications.

  7. Measuring density and compressibility of white blood cells and prostate cancer cells by microchannel acoustophoresis

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Magnusson, Cecilia

    2011-01-01

    We present a novel method for the determination of density and compressibility of individual particles and cells undergoing microchannel acoustophoresis in an arbitrary 2D acoustic field. Our method is a critical advancement within acoustophoretic separation of biological cells, as the ability to...

  8. Microchannel laminated mass exchanger and method of making

    Science.gov (United States)

    Martin, Peter M.; Bennett, Wendy D.; Matson, Dean W.; Stewart, Donald C.; Drost, Monte K.; Wegeng, Robert S.; Perez, Joseph M.; Feng, Xiangdong; Liu, Jun

    2000-01-01

    The present invention is a microchannel mass exchanger having a first plurality of inner thin sheets and a second plurality of outer thin sheets. The inner thin sheets each have a solid margin around a circumference, the solid margin defining a slot through the inner thin sheet thickness. The outer thin sheets each have at least two header holes on opposite ends and when sandwiching an inner thin sheet. The outer thin sheets further have a mass exchange medium. The assembly forms a closed flow channel assembly wherein fluid enters through one of the header holes into the slot and exits through another of the header holes after contacting the mass exchange medium.

  9. Experimental investigation of the unsteady two-phase flow through perforated plates

    International Nuclear Information System (INIS)

    Tartaglia, G.P.

    1985-07-01

    The coolant flow across the perforated dip-plate during a hypothetical core disruptive accident (HCDA) in a liquid metal fast breeder reactor was simulated in a one-dimensional model. Experiments with a water-air mixture as fluid were run by varying the following parameters: geometry of the dip-plate (perforation ratio, number of the holes), height of the fluid head over the dip-plate, air volumetric fraction, size of the air bubbles, acceleration of the fluid. The pressure drop across the dip-plate, the forces acting on the dip-plate and on the upper plate, acceleration and displacement of the piston, the air volumetric fraction and the size of the air bubbles were measured in a wide range of Strouhal and acceleration numbers. The flow pattern downstream the dip-plate was filmed with a high-speed camera. The following correlations were investigated: resistance coefficients as a function of the acceleration and Strouhal number, time delay of the force on the upper plate as a function of the cavitation number, and forces and impulses acting on the upper plate compared with those acting on the dip-plate. Finally, using high-speed film pictures, the formation of fluid jets downstream the dip-plate was investigated. The following relations were obtained: displacement of the mixture surface and of the jets as a function of the perforation ratio and of the air volumetric fraction, and cavitation volume as a function of the cavitation number. (orig.) [de

  10. Time resolution performance studies of contemporary high speed photomultipliers

    International Nuclear Information System (INIS)

    Leskovar, B.; Lo, C.C.

    1977-01-01

    The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850 and C31024 high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems

  11. Efficiency enhancements for MCP-based beta autoradiography imaging

    CERN Document Server

    Lees, J E

    2002-01-01

    We describe three approaches to increase the beta detection efficiency of microchannel plate detectors for biological beta autoradiography:(a)reversing the microchannel plate (MCP) bias polarity, changing the conventional high negative voltage on the input MCP to a grounded input, (b) a reduction in MCP pore size from 12.5 to 6 mu m, (c) using a CsI coating as an efficient secondary electron emitter. We also present our first measurements of double-tracer ( sup 3 H and sup 1 sup 4 C) imaging using pulse height analysis to distinguish between isotopes.

  12. Modification of parabolic dish antenna pattern using two symmetrically placed circular flat plates

    Science.gov (United States)

    Thorpe, Glen C.

    1987-12-01

    This study aims to formulate a method of predicting the far field pattern of a parabolic dish antenna with two moveable flat plates mounted symmetrically on either side of the feed horn. The approach taken has been to first analyze the radiation pattern of the antenna with the disks at certain heights out from the surface of the dish. To do this the near-field radiation in amplitude and phase was measured over a plane surface in the near-field and the values were then transformed into the far field using a Fast Fourier Transform. Far field pattern values of the antenna were directly measured for each setting of the plates. The results obtained from the Fast Fourier Transform of the near field data were in good agreement with the values obtained by measurement. Finally, an approximate model of the antenna was developed and implemented as a computer program. This model, while relatively unsophisticated, provided some insights into the changes in the near field phase distribution caused by the moveable circular flat plates.

  13. Analysis of three idealized reactor configurations: plate, pin, and homogeneous

    International Nuclear Information System (INIS)

    McKnight, R.D.

    1983-01-01

    Detailed Monte Carlo calculations have been performed for three distinct configurations of an idealized fast critical assembly. This idealized assembly was based on the LMFBR benchmark critical assembly ZPR-6/7. In the first configuration, the entire core was loaded with the plate unit cell of ZPR-6/7. In the second configuration, the entire core was loaded with the ZPR sodium-filled pin calandria. The actual ZPR pin calandria are loaded with mixed (U,Pu) oxide pins which closely match the composition of the ZPR-6/7 plate unit cell. For the present study, slight adjustments were made in the atom concentrations and the length of the pin calandria in order to make the core boundaries and average composition for the pin-cell configuration identical to those of the plate-cell configuration. In the third configuration, the core was homogeneous, again with identical core boundaries and average composition as the plate and pin configurations

  14. COMPUTER PROGRAM FOR CALCULATION MICROCHANNEL HEAT EXCHANGERS FOR AIR CONDITIONING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Olga V. Olshevska

    2016-08-01

    Full Text Available Creating a computer program to calculate microchannel air condensers to reduce design time and carrying out variant calculations. Software packages for thermophysical properties of the working substance and the coolant, the correlation equation for calculating heat transfer, aerodynamics and hydrodynamics, the thermodynamic equations for the irreversible losses and their minimization in the heat exchanger were used in the process of creating. Borland Delphi 7 is used for creating software package.

  15. Development of an innovative plate-type SG for fast breeder reactor. Proposal of the concept and the evaluation of the fabricating method by the test fabrication of the partial model

    International Nuclear Information System (INIS)

    Nishi, Yoshihisa; Kinoshita, Izumi

    2006-01-01

    The concept of an innovative plate type SG for the fast reactor fabricated by using the HIP (Hot Isostatic Pressing) method was proposed. The heat transfer plate, which is assembled with rectangular tubes and is fabricated by HIP method, is surrounded by leakage detection spaces. It is possible to apply it to both the pool-type and the loop-type LMFR. In this report, the fabrication technique was studied about the concept for the loop-type LMFR, and the following results were obtained. Hip tests, tensile tests, and structure observation were performed to clarify the suitable HIP condition for the modified 9Cr-1Mo steel. As a result, the optimum condition of 1150 deg C x 1200 kgf/cm 2 x 3 hr was found. Nickel-type solder (BNi-5) and gold-type solder (BAu-4) were selected as a joining material to laminate the heat transfer tube plates. Through the comparison of tensile tests, BAu-4 that showed a more excellent joining performance was selected on the assumption of the margin of 5 mm from the welding line. After buckling load had been clarified, the BAu-4 brazing of the heat transfer tube plates was performed using a hot pressing method. Problems were not observed in the welding of simulated header, and in the fabricating of the partial model of SG. (author)

  16. Innovation-Prototype. Making hydraulic and/or pneumatic plates using 3D printing technology

    Science.gov (United States)

    Alexa, V.; Rațiu, S. A.; Kiss, I.; Cioată, V. G.; Rackov, M.

    2018-01-01

    Start 3D printing allows hydraulic and/or pneumatic plates to be obtained from a single technological process without requiring further post-production operations. 3D printing with innovative materials in a rich colour range has several advantages such as: time-saving, cost is the same for any type of plate and its reported just to volume, fast and impossible realization of hydraulic and/or pneumatic links compared to traditional and high accuracy technologies.

  17. Experimental investigation of the liquid volumetric mass transfer coefficient for upward gas-liquid two-phase flow in rectangular microchannels

    Directory of Open Access Journals (Sweden)

    X. Y. Ji

    2010-12-01

    Full Text Available The gas-liquid two-phase mass transfer process in microchannels is complicated due to the special dynamical characteristics. In this work, a novel method was explored to measure the liquid side volumetric mass transfer coefficient kLa. Pressure transducers were utilized to measure the pressure variation of upward gas-liquid two-phase flow in three vertical rectangular microchannels and the liquid side volumetric mass transfer coefficient kLa was calculated through the Pressure-Volume-Temperature correlation of the gas phase. Carbon dioxide-water, carbon dioxide-ethanol and carbon dioxide-n-propanol were used as working fluids, respectively. The dimensions of the microchannels were 40 µm×240 µm (depth×width, 100 µm×800 µm and 100 µm×2000 µm, respectively. Results showed that the channel diameter and the capillary number influence kLa remarkably and that the maximum value of kLa occurs in the annular flow regime. A new correlation of kLa was proposed based on the Sherwood number, Schmidt number and the capillary number. The predicted values of kLa agreed well with the experimental data.

  18. Low temperature catalytic combustion of propane over Pt-based catalyst with inverse opal microstructure in microchannel reactor

    NARCIS (Netherlands)

    Guan, G.; Zapf, R.; Kolb, G.A.; Men, Y.; Hessel, V.; Löwe, H.; Ye, J.; Zentel, R.

    2007-01-01

    novel Pt-based catalyst with highly regular, periodic inverse opal microstructure was fabricated in a microchannel reactor, and catalytic testing revealed excellent conversion and stable activity for propane combustion at low temperatures

  19. Two-fluid mixing in a microchannel

    International Nuclear Information System (INIS)

    Liu Yingzheng; Kim, Byoung Jae; Sung, Hyung Jin

    2004-01-01

    A numerical study of the mixing of two fluids (pure water and a solution of glycerol in water) in a microchannel was carried out. By varying the glycerol content of the glycerol/water solution, the variation in mixing behavior with changes in the difference in the properties of the two fluids (e.g., viscosity, density and diffusivity) was investigated. The mixing phenomena were tested for three micromixers: a squarewave mixer, a three-dimensional serpentine mixer and a staggered herringbone mixer. The governing equations of continuity, momentum and solute mass fraction were solved numerically. To evaluate mixing performance, a criterion index of mixing uniformity was proposed. In the systems considered, the Reynolds number based on averaged properties was Re=1 and 10. For low Reynolds number (Re=1), the mixing performance varied inversely with mass fraction of glycerol due to the dominance of molecular diffusion. The mixing performance deteriorated due to a significant reduction in the residence time of the fluid inside the mixers

  20. Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC for Implant of Varicose Veins

    Directory of Open Access Journals (Sweden)

    Muhammad Javaid Afzal

    2017-09-01

    Full Text Available Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT, vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs.

  1. Systematic test on fast time resolution parallel plate avalanche counter

    International Nuclear Information System (INIS)

    Chen Yu; Li Guangwu; Gu Xianbao; Chen Yanchao; Zhang Gang; Zhang Wenhui; Yan Guohong

    2011-01-01

    Systematic test on each detect unit of parallel plate avalanche counter (PPAC) used in the fission multi-parameter measurement was performed with a 241 Am α source to get the time resolution and position resolution. The detectors work at 600 Pa flowing isobutane and with-600 V on cathode. The time resolution was got by TOF method and the position resolution was got by delay line method. The time resolution of detect units is better than 400 ps, and the position resolution is 6 mm. The results show that the demand of measurement is fully covered. (authors)

  2. Signal-to-noise characterization of time-gated intensifiers used for wide-field time-domain FLIM

    Energy Technology Data Exchange (ETDEWEB)

    McGinty, J; Requejo-Isidro, J; Munro, I; Talbot, C B; Dunsby, C; Neil, M A A; French, P M W [Photonics Group, Blackett Laboratory, Imperial College London, Prince Consort Road, London, SW7 2BW (United Kingdom); Kellett, P A; Hares, J D, E-mail: james.mcginty@imperial.ac.u [Kentech Instruments Ltd, Isis Building, Howbery Park, Wallingford, OX10 8BA (United Kingdom)

    2009-07-07

    Time-gated imaging using gated optical intensifiers provides a means to realize high speed fluorescence lifetime imaging (FLIM) for the study of fast events and for high throughput imaging. We present a signal-to-noise characterization of CCD-coupled micro-channel plate gated intensifiers used with this technique and determine the optimal acquisition parameters (intensifier gain voltage, CCD integration time and frame averaging) for measuring mono-exponential fluorescence lifetimes in the shortest image acquisition time for a given signal flux. We explore the use of unequal CCD integration times for different gate delays and show that this can improve the lifetime accuracy for a given total acquisition time.

  3. Modeling particulate removal in plate-plate and wire-plate electrostatic precipitators

    Directory of Open Access Journals (Sweden)

    S Ramechecandane

    2016-09-01

    Full Text Available The present study is concerned with the modeling of electrically charged particles in a model plate-plate and a single wire-plate electrostatic precipitator (ESP. The particle concentration distributions for both a plate-plate and a wire-plate ESP are calculated using a modified drift flux model. Numerical investigations are performed using the modified drift flux model for particle number concentration, in addition to the RNG k - ε model for the mean turbulent flow field and the Poisson equation for the electric field. The proposed model and the outlined methodology for coupling the flow field, electric field, charging kinetics and particle concentration is applied to two model precipitators that are truly representative of a wide class of commercialized ESPs. The present investigation is quite different from the earlier studies as it does not make assumptions like a homogeneous electric field or an infinite turbulent diffusivity. The electric field calculated is a strong function of position and controls the migration velocity of particles. Hence, the proposed model can be implemented in a flow solver to obtain a full-fledged solution for any kind of ESP with no limitations on the particle number concentration, as encountered in a Lagrangian approach. The effect of turbulent diffusivity on particle number concentration in a plate-plate ESP is investigated in detail and the results obtained are compared with available experimental data. Similarly, the effect of particle size/diameter and applied electric potential on the accumulative collection performance in the case of a wire-plate ESP is studied and the results obtained are compared with available numerical data. The numerical results obtained using the modified drift flux model for both the plate-plate and wire-plate ESP are in close agreement with available experimental and numerical data.

  4. Pressure loss in two-phase flow through a microchannel rod bundle

    International Nuclear Information System (INIS)

    Smith, A.C.; Hamm, L.L.; Qureshi, Z.; Steeper, T.J.

    1998-01-01

    The purpose of the microchannel rod bundle two-phase flow test described here was to provide data for benchmarking safety analyses for the accelerator production of tritium (APT). The objective was to obtain pressure loss data for a typical accelerator target rod bundle over a wide range of two-phase flow conditions. The test rod bundle assembly was fabricated for single-phase pressure drop tests conducted at Los Alamos National Laboratory (LANL) and subsequently used for the two-phase flow testing described here. The results for a typical case are given. These results fall generally in the slug flow regime for the horizontal flow results of Fukano and Kariyasaki for a 1.0-mm circular channel. Fukano and Kariyasaki found that surface tension effects were dominant in the 1-mm channel and report no churn regime. The results were also compared with the flow regime maps given by Triplett et al. for flow in discrete microchannels. Triplett employed both circular and trapezoidal channels, the latter to approximate the rod bundle interstitial flow channel shape. It was found that the rod bundle flow fell across the slug-to-churn flow regime transition reported by Triplett. This is consistent with the expectation that cross flow among channels would result in turbulent mixing and would suppress the formation of large discrete bubbles

  5. Continuous Size-Dependent Sorting of Ferromagnetic Nanoparticles in Laser-Ablated Microchannel

    Directory of Open Access Journals (Sweden)

    Yiqiang Fan

    2016-01-01

    Full Text Available This paper reports a low-cost method of continuous size-dependent sorting of magnetic nanoparticles in polymer-based microfluidic devices by magnetic force. A neodymium permanent magnet was used to generate a magnetic field perpendicular to the fluid flow direction. Firstly, FeNi3 magnetic nanoparticles were chemically synthesized with diameter ranges from 80 nm to 200 nm; then, the solution of magnetic nanoparticles and a buffer were passed through the microchannel in laminar flow; the magnetic nanoparticles were deflected from the flow direction under the applied magnetic field. Nanoparticles in the microchannel will move towards the direction of high-gradient magnetic fields, and the degree of deflection depends on their sizes; therefore, magnetic nanoparticles of different sizes can be separated and finally collected from different output ports. The proposed method offers a rapid and continuous approach of preparing magnetic nanoparticles with a narrow size distribution from an arbitrary particle size distribution. The proposed new method has many potential applications in bioanalysis field since magnetic nanoparticles are commonly used as solid support for biological entities such as DNA, RNA, virus, and protein. Other than the size sorting application of magnetic nanoparticles, this approach could also be used for the size sorting and separation of naturally magnetic cells, including blood cells and magnetotactic bacteria.

  6. Custom ceramic microchannel-cooled array for high-power fiber-coupled application

    Science.gov (United States)

    Junghans, Jeremy; Feeler, Ryan; Stephens, Ed

    2018-03-01

    A low-SWaP (Size, Weight and Power) diode array has been developed for a high-power fiber-coupled application. High efficiency ( 65%) diodes enable high optical powers while minimizing thermal losses. A large amount of waste heat is still generated and must be extracted. Custom ceramic microchannel-coolers (MCCs) are used to dissipate the waste heat. The custom ceramic MCC was designed to accommodate long cavity length diodes and micro-lenses. The coolers provide similar thermal performance as copper MCCs however they are not susceptible to erosion and can be cooled with standard filtered water. The custom ceramic micro-channel cooled array was designed to be a form/fit replacement for an existing copperbased solution. Each array consisted of three-vertically stacked MCCs with 4 mm CL, 976 nm diodes and beamshaping micro-optics. The erosion and corrosion resistance of ceramic array is intended to mitigate the risk of copperbased MCC corrosion failures. Elimination of the water delivery requirements (pH, resistivity and dissolved oxygen control) further reduces the system SWaP while maintaining reliability. The arrays were fabricated and fully characterized. This work discusses the advantages of the ceramic MCC technology and describes the design parameters that were tailored for the fiber-coupled application. Additional configuration options (form/fit, micro-lensing, alternate coolants, etc.) and on-going design improvements are also discussed.

  7. Coupling intensity and isostatic competition between subducting slab and overriding plate control trench motions and tectonics of the overriding plate

    Science.gov (United States)

    Wu, G.; Moresi, L. N.

    2017-12-01

    Trench motions not only reflect tectonic regimes on the overriding plate but also shed light on the competition between subducting slab and overriding plate, however, major controls over trench advance or retreat and their consequences are still illusive. We use 2D thermo-mechanical experiments to study the problem. We find that the coupling intensity particularly in the uppermost 200 km and the isostatic competition between subducting slab and overriding plate largely determine trench motion and tectonics of in the overriding plate. Coupling intensity is the result of many contributing factors, including frictional coefficient of brittle part of the subducting interface and the viscosity of the ductile part, thermal regime and rheology of the overriding plate, and water contents and magmatic activity in the subducting slab and overriding plate. In this study, we are not concerned with the dynamic evolution of individual controlling parameter but simply use effective media. For instance, we impose simple model parameters such as frictional coefficient and vary the temperature and strain-rate dependent viscosity of the weak layer between the subducting slab and overriding plate. In the coupled end-member case, strong coupling leads to strong corner flow, depth-dependent compression/extension, and mantle return flow on the overriding plate side. It results in fast trench retreat, broad overriding plate extension, and even slab breakoff. In the decoupled end-member case, weak coupling causes much weaker response on the overriding plate side compared with the coupled end-member case, and the subducting slab can be largely viewed as a conveyer belt. We find that the isostatic competition between the subducting slab and overriding plate also has a major control over trench motion, and may better be viewed in 3D models. This is consistent with the findings in previous 3D studies that trench motion is most pronounced close to the slab edge. Here we propose that the

  8. Fast pulse beam generation systems for electron accelerators

    International Nuclear Information System (INIS)

    Koontz, R.F.

    1977-01-01

    The fast pulse beam generation system to supply the SLAC storage ring, SPEAR, by the two one nanosecond bunch electron beam pulses is described. Generation of these pulses is accomplished with a combination of a fast pulsed grided gun and a synchronized transverse beam chopper. Fast gun based on spherical cathode-grid assembly has output current up to 2As. Fast pulse amplifier system can handle trains of short pulses with repetition rates up to 40 MHz during the 1.6 μs normal accelerating time. Chopping deflector system consists of a resonant coaxial line with the deflecting plates. The resonator frequency is 39.667 MHz. A schematic diagram of the resonant system is shown. The fast beam pickup system has a one hundred picosecond rise time overrall. Fast beam generation and chopper systems permit to generate almost any short or single bunch beam profile needed for experiments

  9. Regulating the Emission Spectrum of CsPbBr3 from Green to Blue via Controlling the Temperature and Velocity of Microchannel Reactor

    Science.gov (United States)

    Tang, Yong; Lu, Hanguang; Rao, Longshi; Ding, Xinrui; Yan, Caiman; Yu, Binhai

    2018-01-01

    The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs) is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr3 QDs with tunable spectrum. By adjusting the temperature and velocity of the microchannel reactor, the emission peaks of CsPbBr3 QDs ranging from 520 nm to 430 nm were obtained, which is wider than that of QDs obtained in a traditional flask without changing halide component. The mechanism of photoluminescence (PL) spectral shift of CsPbBr3 QDs was investigated, the result shows that the supersaturation control enabled by the superior mass and heat transfer performance in the microchannel is the key to achieve the wide range of PL spectrum, with only a change in the setting of the temperature controller required. The wide spectrum of CsPbBr3 QDs can be applied to light-emitting diodes (LEDs), photoelectric sensors, lasers, etc. PMID:29498710

  10. Advancements in the Interferometric Measurements of Real Time Finishing Birefringent Filter's Crystal Plates

    International Nuclear Information System (INIS)

    Gan, Ma; Kushtal, Gi; Skomorovsky, Vi; Domyshev, Gn; Sadokhin, Vp

    2006-01-01

    The finishing of birefringent plates consists of two processes: polishing and evaluation of a surface, which have been performed separately till now. The purpose of this work is achieving of high accuracy of the evaluation and machining of the plane-parallel plates from birefringent crystals, in particular of crystal plates of birefringent filters during their finishing. The developed process combines evaluation and polishing in an interactive way. We have found modes of treatment, shape of polisher, have designed interferometer, with a mirror arranged in polisher. Visual checking of optical thickness comparatively with reference plate was carried out using the interference fringes of equal birefringence, and checking of an optical wedge - by interference rings of an equal inclination. The automated processing of TV camera interference fringes was impossible, because of gaps of interference fringes on polishing cells above the mirror. Therefore a special software was developed for processing of a complex fringe pattern interferogram. Software FastInterf uses furrier analysis technique which allows to process an interferogram with multiply gaps. Interferograms are registered by a high resolution TV camera (1280 x1024). Automatic processing of a fringe interferogram using FastInterf software takes less then one second. The influence of gaps is excluded, and the flat field is taken into account. Software provides full 3D surface and wavefront maps. Aberration analysis of a wavefront gives information on thickness of a plate comparatively with a reference one, optical wedge of plate and azimuth of an inclination of wave front. Moreover, software provides a control of surface quality. The measuring device, features of the software are described and process of interferometric evaluation during polishing is illustrated

  11. Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells

    Science.gov (United States)

    Siyabi, Idris Al; Shanks, Katie; Mallick, Tapas; Sundaram, Senthilarasu

    2017-09-01

    Concentrator Photovoltaic (CPV) technology is increasingly being considered as an alternative option for solar electricity generation. However, increasing the light concentration ratio could decrease the system output power due to the increase in the temperature of the cells. The performance of a multi-layer microchannel heat sink configuration was evaluated using numerical analysis. In this analysis, three dimensional incompressible laminar steady flow model was solved numerically. An electrical and thermal solar cell model was coupled for solar cell temperature and efficiency calculations. Thermal resistance, solar cell temperature and pumping power were used for the system efficiency evaluation. An increase in the number of microchannel layers exhibited the best overall performance in terms of the thermal resistance, solar cell temperature uniformity and pressure drop. The channel height and width has no effect on the solar cell maximum temperature. However, increasing channel height leads to a reduction in the pressure drop and hence less fluid pumping power.

  12. Slow waves in microchannel metal waveguides and application to particle acceleration

    OpenAIRE

    L. C. Steinhauer; W. D. Kimura

    2003-01-01

    Conventional metal-wall waveguides support waveguide modes with phase velocities exceeding the speed of light. However, for infrared frequencies and guide dimensions of a fraction of a millimeter, one of the waveguide modes can have a phase velocity equal to or less than the speed of light. Such a metal microchannel then acts as a slow-wave structure. Furthermore, if it is a transverse magnetic mode, the electric field has a component along the direction of propagation. Therefore, a strong ex...

  13. A fast neutron detector with IP by track measurement

    International Nuclear Information System (INIS)

    Miao Zhengqiang; Yang Jun; Zhang Qiang; Zhao Xiangfeng; Wang Daohua

    2004-01-01

    Imaging Plate(IP) is very sensitive to electric particles, especially to heavy ions. As we know, the recoiling protons are produced while fast neutrons scattered in light material containing hydrogen. When the recoiling proton enters in the sensitive layer of IP, a track will be recorded by IP. In this paper, a fast neutron detector based on IP and (n, p) reaction is described in detail, the detector's efficiency is studied also. (authors)

  14. Efficiency determination of resistive plate chambers for fast quasi-monoenergetic neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Roeder, M.; Cowan, T.E.; Kempe, M.; Yakorev, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Universitaet Dresden, Dresden (Germany); Elekes, Z. [MTA ATOMKI, Debrecen (Hungary); Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Aumann, T.; Caesar, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Technische Universitaet Darmstadt, Darmstadt (Germany); Bemmerer, D.; Sobiella, M.; Stach, D.; Wagner, A. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Boretzky, K.; Hehner, J.; Heil, M. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Maroussov, V. [Universitaet zu Koeln, Koeln (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Nusair, O. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Al-Balqa Applied University, Salt (Jordan); Prokofiev, A.V. [Uppsala University, The Svedberg Laboratory, Uppsala (Sweden); Reifarth, R. [Johann Wolfgang Goethe - Universitaet, Frankfurt am Main (Germany); Zilges, A. [Universitaet zu Koeln, Koeln (Germany); Zuber, K. [Technische Universitaet Dresden, Dresden (Germany); Collaboration: R3B Collaboration

    2014-07-15

    Composite detectors made of stainless-steel converters and multigap resistive plate chambers have been irradiated with quasi-monoenergetic neutrons with a peak energy of 175 MeV. The neutron detection efficiency has been determined using two different methods. The data are in agreement with the output of Monte Carlo simulations. The simulations are then extended to study the response of a hypothetical array made of these detectors to energetic neutrons from a radioactive ion beam experiment. (orig.)

  15. Regulating the Emission Spectrum of CsPbBr3 from Green to Blue via Controlling the Temperature and Velocity of Microchannel Reactor

    OpenAIRE

    Yong Tang; Hanguang Lu; Longshi Rao; Zongtao Li; Xinrui Ding; Caiman Yan; Binhai Yu

    2018-01-01

    The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs) is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr3 QDs with tunable spectrum. By adjusting the temperature and velocity of the microchannel reactor, the emission peaks of CsPbBr3 QDs ranging from 520 nm to 430 nm were obtained, which is wider than that of QDs obtained in a traditional flask without changing hal...

  16. Optimization of Dimples in Microchannel Heat Sink with Impinging Jets — Part A: Mathematical Model and the Influence of Dimple Radius

    Science.gov (United States)

    Ming, Tingzhen; Cai, Cunjin; Yang, Wei; Shen, Wenqing; Gan, Ting

    2018-06-01

    With increasing heat fluxes caused by electronic components, dimples have attracted wide attention by researchers and have been applied to microchannel heat sink in modern advanced cooling technologies. In this work, the combination of dimples, impinging jets and microchannel heat sink was proposed to improve the heat transfer performance on a cooling surface with a constant heat flux 500 W/cm2. A mathematical model was advanced for numerically analyzing the fluid flow and heat transfer characteristics of a microchannel heat sink with impinging jets and dimples (MHSIJD), and the velocity distribution, pressure drop, and thermal performance of MHSIJD were analyzed by varying the radii of dimples. The results showed that the combination of dimples and MHSIJ can achieve excellent heat transfer performance; for the MHSIJD model in this work, the maximum and average temperatures can be as low as 320 K and 305 K, respectively when mass flow rate is 30 g/s; when dimple radius is larger than 0.195 mm, both the heat transfer coefficient and the overall performance h/ΔP of MHSIJD are higher than those of MHSIJ.

  17. Single-phase flow and flow boiling of water in horizontal rectangular microchannels

    OpenAIRE

    Mirmanto

    2013-01-01

    This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University The current study is part of a long term experimental project devoted to investigating single-phase flow pressure drop and heat transfer, flow boiling pressure drop and heat transfer, flow boiling instability and flow visualization of de-ionized water flow in microchannels. The experimental facility was first designed and constructed by S. Gedupudi (2009) and in the present study; ...

  18. Anomalous scattering, transport, and spatial distribution of X-ray fluorescence at the exit of polycapillary structures

    Energy Technology Data Exchange (ETDEWEB)

    Mazuritskiy, M. I., E-mail: mazurmik@gmail.com; Lerer, A. M.; Makhno, P. V. [Southern Federal University (Russian Federation)

    2016-12-15

    The angular distribution of the X-ray intensity at the exit of microchannel plates at grazing incidence of monochromatic radiation on the walls of microcapillaries has been investigated. The angles and energies of the primary radiation quanta at which the synchrotron beam excites X-ray fluorescence propagating inside polycapillary structures have been determined. The angular dependences of the intensity distribution of X-rays transmitted through the microcapillaries have been studied theoretically and experimentally for energies corresponding to the region of anomalous dispersion near the L{sub 2,3} absorption edges of silicon. The propagation of waves in hollow polycapillary waveguides, the excitation of X-ray fluorescence, and the X-ray diffraction at the exit of microchannel plates have been modeled mathematically. The mathematical model takes into account the presence of a transition layer on the microchannel surface.

  19. Features of two-phase flow in a microchannel of 0.05×20 mm

    Science.gov (United States)

    Ronshin, Fedor

    2017-10-01

    We have studied the two-phase flow in a microchannel with cross-section of 0.05×20 mm2. The following two-phase flow regimes have been registered: jet, bubble, stratified, annular, and churn ones. The main features of flow regimes in this channel such as formation of liquid droplets in all two-phase flows have been distinguished.

  20. Development of fast neutron radiography system based on portable neutron generator

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Chia Jia, E-mail: gei-i-kani@hotmail.com; Nilsuwankosit, Sunchai, E-mail: sunchai.n@chula.ac.th [Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Phayathai Rd., Patumwan, Bangkok, THAILAND 10330 (Thailand)

    2016-01-22

    Due to the high installation cost, the safety concern and the immobility of the research reactors, the neutron radiography system based on portable neutron generator is proposed. Since the neutrons generated from a portable neutron generator are mostly the fast neutrons, the system is emphasized on using the fast neutrons for the purpose of conducting the radiography. In order to suppress the influence of X-ray produced by the neutron generator, a combination of a shielding material sandwiched between two identical imaging plates is used. A binary XOR operation is then applied for combining the information from the imaging plates. The raw images obtained confirm that the X-ray really has a large effect and that XOR operation can help enhance the effect of the neutrons.

  1. High rate resistive plate chambers: An inexpensive, fast, large area detector of energetic charged particles for accelerator and non-accelerator applications

    International Nuclear Information System (INIS)

    Wuest, C.R.; Ables, E.; Bionta, R.M.; Clamp, O.; Haro, M.; Mauger, G.J.; Miller, K.; Olson, H.; Ramsey, P.

    1993-05-01

    Resistive Plate Chambers, or RPCs, have been used until recently as large detectors of cosmic ray muons. They are now finding use as fast large-area trigger and muon detection systems for different high energy physics detectors such the L3 Detector at LEP and future detectors to be built at the Superconducting Super Collider (SSC) and at the Large Hadron Collider (LHC) at CERN. RPC systems at these accelerators must operate with high efficiency, providing nanosecond timing resolution in particle fluences up to a few tens of kHz/cm 2 -- with thousands of square meters of active area. RPCs are simple and cheap to construct. The authors report here recent work on RPCs using new materials that exhibit a combination of desirable RPC features such as low bulk resistivity, high dielectric strength, low mass, and low cost. These new materials were originally developed for use in electronics assembly areas and other applications, where static electric charge buildup can damage sensitive electrical systems

  2. Bubble splitting under gas–liquid–liquid three-phase flow in a double T-junction microchannel

    NARCIS (Netherlands)

    Liu, Yanyan; Yue, Jun; Zhao, Shuainan; Yao, Chaoqun; Chen, Guangwen

    Gas–aqueous liquid–oil three-phase flow was generated in a microchannel with a double T-junction. Under the squeezing of the dispersed aqueous phase at the second T-junction (T2), the splitting of bubbles generated from the first T-junction (T1) was investigated. During the bubble splitting process,

  3. Laser-Induced Motion of a Nanofluid in a Micro-Channel

    OpenAIRE

    Tran X. Phuoc; Mehrdad Massoudi; Ping Wang

    2016-01-01

    Since a photon carries both energy and momentum, when it interacts with a particle, photon-particle energy and momentum transfer occur, resulting in mechanical forces acting on the particle. In this paper we report our theoretical study on the use of a laser beam to manipulate and control the flow of nanofluids in a micro-channel. We calculate the velocity induced by a laser beam for TiO2, Fe2O3, Al2O3 MgO, and SiO2 nanoparticles with water as the base fluid. The particle diameter is 50 nm an...

  4. Use of 3D Printed Bone Plate in Novel Technique to Surgically Correct Hallux Valgus Deformities

    Science.gov (United States)

    Smith, Kathryn E.; Dupont, Kenneth M.; Safranski, David L.; Blair, Jeremy; Buratti, Dawn; Zeetser, Vladimir; Callahan, Ryan; Lin, Jason; Gall, Ken

    2016-01-01

    Three-dimensional (3-D) printing offers many potential advantages in designing and manufacturing plating systems for foot and ankle procedures that involve small, geometrically complex bony anatomy. Here, we describe the design and clinical use of a Ti-6Al-4V ELI bone plate (FastForward™ Bone Tether Plate, MedShape, Inc., Atlanta, GA) manufactured through 3-D printing processes. The plate protects the second metatarsal when tethering suture tape between the first and second metatarsals and is a part of a new procedure that corrects hallux valgus (bunion) deformities without relying on doing an osteotomy or fusion procedure. The surgical technique and two clinical cases describing the use of this procedure with the 3-D printed bone plate are presented within. PMID:28337049

  5. Influence of rheology on realignment of mantle convective structure with plate motion after a plate reorganization

    Science.gov (United States)

    van Hunen, J.; Zhong, S.

    2006-08-01

    Small-scale convection (SSC) rolls below the oceanic lithosphere have the tendency to align with the large-scale shearing direction and thus with the plate motion direction relative to the deep mantle. Understanding the timescales of and processes responsible for realignment would contribute significantly to our understanding of the unresolved phenomena in the Pacific such as gravity lineations, small-scale seismic velocity variations, and intraplate volcanism that cannot be explained by hot spots. In this study we examine the evolution of those convection rolls when this relative plate motion direction is suddenly changed, as suggested by the kink in the Hawaii-Emperor seamount chain. Using three-dimensional numerical flow models, we investigate the realignment of SSC rolls after a change in plate motion direction. From the nature of the SSC, it is expected that rheological parameters dominate the characteristics of this realignment. Our results show that this is indeed the case. We find that (1) using constraints from onset timing of SSC, realignment of rolls can occur as fast as within 20 Ma, but might also take much longer, dependent on the rheology; (2) the realignment period is strongly correlated to the sum of large-scale shear stress induced by plate motion and small-scale shear stress from the SSC itself; (3) in a mantle deforming by dislocation creep, realignment occurs faster than by diffusion creep, because dislocation creep SSC is more vigorous; and (4) activation energy has little influence on the realignment time. Possible evidence for the realignment period might come from precise age determination of intraplate volcanism or azimuthal seismic anisotropy.

  6. A heat exchanger provided with plates

    International Nuclear Information System (INIS)

    Chaix, J.E.; Fajeau, Maurice; Chlique, Bernard.

    1976-01-01

    The invention relates to a heat exchanger of the plate type, in which two fluids exchange calories through parallel metal plates, delimiting spaces separated from each other in which two fluids respectively flow without direct contact between them. The invention particularly applies in the case where one of the two fluids is water under pressure or else a circulating liquid metal, specially sodium, used in the system of a pressurised water or fast neutron reactor, the second fluid being water to be vaporised in the exchanger by the calories supplied by the first fluid. The arrangement is designed to give minimum bulk, particularly enabling the exchanger to be housed in the area between the core of a nuclear reactor and a casing or outer vessel, or else in an external sealed containment, with a view to recovering with the best efficiency the heat acquired by a coolant flowing through the core [fr

  7. Effects of carbon nanotube coating on flow boiling in a micro-channel

    OpenAIRE

    Khanikar, Vikash; Mudawar, Issam; Fisher, Timothy

    2009-01-01

    Experiments were performed to assess the heat transfer enhancement benefits of coating the bottom wall of a shallow rectangular micro-channel with carbon nanotubes (CNTs). Using water as working fluid, tests were performed with a bare copper surface and three separate, yet identical CNT-coated surfaces. Each of the CNT-coated surfaces was tested repeatedly at the same mass velocity to explore any time dependence of heat transfer performance parameters, especially critical heat flux (CHIF). Ap...

  8. Measurements of tangential momentum accommodation coefficient for various gases in plane microchannel

    OpenAIRE

    Graur , I; Perrier , Pierre; Ghozlani , W ,; Méolans , J.Gilbert

    2009-01-01

    International audience; Mass flow rate measurements in a single silicon microchannel were carried out for various gases in isothermal steady flows. The results obtained from hydrodynamic to near free molecular regime by using a powerful experimental platform allowed us to deduce interesting information, notably about the reflection/accommodation process at the wall. In the 0–0.3 Knudsen range, a continuum analytic approach was derived from the NS equations, associated with first or second ord...

  9. Mixing in wicking structures and the use of enhanced mixing within wicks in microchannel devices

    Science.gov (United States)

    Stenkamp, Victoria S [Richland, WA; TeGrotenhuis, Ward E [Kennewick, WA; Wegeng, Robert S [Alexandria, VA

    2009-06-02

    Advanced wicking structures and methods utilizing these structures are described. The use of advanced wicking structures can promote rapid mass transfer while maintaining high capillary pressure through the use of small pores. Particularly improved results in fluid contacting processes can be achieved by enhanced mixing within a wicking layer within a microchannel.

  10. Hydrodynamics of a flexible plate between pitching rigid plates

    Science.gov (United States)

    Kim, Junyoung; Kim, Daegyoum

    2017-11-01

    The dynamics of a flexible plate have been studied as a model problem in swimming and flying of animals and fluid-structure interaction of plants and flags. Motivated by fish schooling and an array of sea grasses, we investigate the dynamics of a flexible plate closely placed between two pitching rigid plates. In most studies on passive deformation of the flexible plate, the plate is immersed in a uniform flow or a wavy flow. However, in this study, the flexible plate experiences periodic deformation by the oscillatory flow generated by the prescribed pitching motion of the rigid plates. In our model, the pitching axes of the rigid plates and the clamping position of the flexible plate are aligned on the same line. The flexible plate shows various responses depending on length and pitching frequency of rigid plates, thickness of a flexible plate, and free-stream velocity. To find the effect of each variable on the response of the flexible plate, amplitude of a trailing edge and modal contribution of a flapping motion are compared, and flow structure around the flexible plate is examined.

  11. Regulating the Emission Spectrum of CsPbBr3 from Green to Blue via Controlling the Temperature and Velocity of Microchannel Reactor

    Directory of Open Access Journals (Sweden)

    Yong Tang

    2018-03-01

    Full Text Available The ability to precisely obtain tunable spectrum of lead halide perovskite quantum dots (QDs is very important for applications, such as in lighting and display. Herein, we report a microchannel reactor method for synthesis of CsPbBr3 QDs with tunable spectrum. By adjusting the temperature and velocity of the microchannel reactor, the emission peaks of CsPbBr3 QDs ranging from 520 nm to 430 nm were obtained, which is wider than that of QDs obtained in a traditional flask without changing halide component. The mechanism of photoluminescence (PL spectral shift of CsPbBr3 QDs was investigated, the result shows that the supersaturation control enabled by the superior mass and heat transfer performance in the microchannel is the key to achieve the wide range of PL spectrum, with only a change in the setting of the temperature controller required. The wide spectrum of CsPbBr3 QDs can be applied to light-emitting diodes (LEDs, photoelectric sensors, lasers, etc.

  12. Features of two-phase flow in a microchannel of 0.05×20 mm

    Directory of Open Access Journals (Sweden)

    Ronshin Fedor

    2017-01-01

    Full Text Available We have studied the two-phase flow in a microchannel with cross-section of 0.05×20 mm2. The following two-phase flow regimes have been registered: jet, bubble, stratified, annular, and churn ones. The main features of flow regimes in this channel such as formation of liquid droplets in all two-phase flows have been distinguished.

  13. A bio-inspired, microchanneled hydrogel with controlled spacing of cell adhesion ligands regulates 3D spatial organization of cells and tissue.

    Science.gov (United States)

    Lee, Min Kyung; Rich, Max H; Lee, Jonghwi; Kong, Hyunjoon

    2015-07-01

    Bioactive hydrogels have been extensively studied as a platform for 3D cell culture and tissue regeneration. One of the key desired design parameters is the ability to control spatial organization of biomolecules and cells and subsequent tissue in a 3D matrix. To this end, this study presents a simple but advanced method to spatially organize microchanneled, cell adherent gel blocks and non-adherent ones in a single construct. This hydrogel system was prepared by first fabricating a bimodal hydrogel in which the microscale, alginate gel blocks modified with cell adhesion peptides containing Arg-Gly-Asp sequence (RGD peptides), and those free of RGD peptides, were alternatingly presented. Then, anisotropically aligned microchannels were introduced by uniaxial freeze-drying of the bimodal hydrogel. The resulting gel system could drive bone marrow stromal cells to adhere to and differentiate into neuron and glial cells exclusively in microchannels of the alginate gel blocks modified with RGD peptides. Separately, the bimodal gel loaded with microparticles releasing vascular endothelial growth factor stimulated vascular growth solely into microchannels of the RGD-alginate gel blocks in vivo. These results were not attained by the bimodal hydrogel fabricated to present randomly oriented micropores. Overall, the bimodal gel system could regulate spatial organization of nerve-like tissue or blood vessels at sub-micrometer length scale. We believe that the hydrogel assembly demonstrated in this study will be highly useful in developing a better understanding of diverse cellular behaviors in 3D tissue and further improve quality of a wide array of engineered tissues. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. An automated microfluidic multiplexer for fast delivery of C. elegans populations from multiwells.

    Directory of Open Access Journals (Sweden)

    Navid Ghorashian

    Full Text Available Automated biosorter platforms, including recently developed microfluidic devices, enable and accelerate high-throughput and/or high-resolution bioassays on small animal models. However, time-consuming delivery of different organism populations to these systems introduces a major bottleneck to executing large-scale screens. Current population delivery strategies rely on suction from conventional well plates through tubing periodically exposed to air, leading to certain disadvantages: 1 bubble introduction to the sample, interfering with analysis in the downstream system, 2 substantial time drain from added bubble-cleaning steps, and 3 the need for complex mechanical systems to manipulate well plate position. To address these concerns, we developed a multiwell-format microfluidic platform that can deliver multiple distinct animal populations from on-chip wells using multiplexed valve control. This Population Delivery Chip could operate autonomously as part of a relatively simple setup that did not require any of the major mechanical moving parts typical of plate-handling systems to address a given well. We demonstrated automatic serial delivery of 16 distinct C. elegans worm populations to a single outlet without introducing any bubbles to the samples, causing cross-contamination, or damaging the animals. The device achieved delivery of more than 90% of the population preloaded into a given well in 4.7 seconds; an order of magnitude faster than delivery modalities in current use. This platform could potentially handle other similarly sized model organisms, such as zebrafish and drosophila larvae or cellular micro-colonies. The device's architecture and microchannel dimensions allow simple expansion for processing larger numbers of populations.

  15. Numerical investigation of fluid flow and heat transfer under high heat flux using rectangular micro-channels

    KAUST Repository

    Mansoor, Mohammad M.; Wong, Kokcheong; Siddique, Mansoor M.

    2012-01-01

    computational domain was discretized using a 120×160×100 grid for the micro-channel with an aspect ratio of (α=4.56) and examined for Reynolds numbers in the laminar range (Re 500-2000) using FLUENT. De-ionized water served as the cooling fluid while the micro

  16. Experimental demonstration of a tailored-width microchannel heat exchanger configuration for uniform wall temperature

    International Nuclear Information System (INIS)

    Riera, S; Barrau, J; Rosell, J I; Omri, M; Fréchette, L G

    2013-01-01

    In this work, an experimental study of a novel microfabricated heat sink configuration that tends to uniform the wall temperature, even with increasing flow temperature, is presented. The design consists of a series of microchannel sections with stepwise varying width. This scheme counteracts the flow temperature increase by reducing the local thermal resistance along the flow path. A test apparatus with uniform heat flux and distributed wall temperature measurements was developed for microchannel heat exchanger characterisation. The energy balance is checked and the temperature distribution is analysed for each test. The results show that the wall temperature decreases slightly along the flow path while the fluid temperature increases, highlighting the strong impact of this approach. For a flow rate of 16 ml/s, the mean thermal resistance of the heat sink is 2,35·10 −5 m 2 ·K/W which enhances the results compared to the millimeter scale channels nearly three-fold. For the same flow rate and a heat flux of 50 W/cm 2 , the temperature uniformity, expressed as the standard deviation of the wall temperature, is around 6 °C

  17. Mixing enhancement of low-Reynolds electro-osmotic flows in microchannels with temperature-patterned walls.

    Science.gov (United States)

    Alizadeh, A; Zhang, L; Wang, M

    2014-10-01

    Mixing becomes challenging in microchannels because of the low Reynolds number. This study aims to present a mixing enhancement method for electro-osmotic flows in microchannels using vortices caused by temperature-patterned walls. Since the fluid is non-isothermal, the conventional form of Nernst-Planck equation is modified by adding a new migration term which is dependent on both temperature and internal electric potential gradient. This term results in the so-called thermo-electrochemical migration phenomenon. The coupled Navier-Stokes, Poisson, modified Nernst-Planck, energy and advection-diffusion equations are iteratively solved by multiple lattice Boltzmann methods to obtain the velocity, internal electric potential, ion distribution, temperature and species concentration fields, respectively. To enhance the mixing, three schemes of temperature-patterned walls have been considered with symmetrical or asymmetrical arrangements of blocks with surface charge and temperature. Modeling results show that the asymmetric arrangement scheme is the most efficient scheme and enhances the mixing of species by 39% when the Reynolds number is on the order of 10(-3). Current results may help improve the design of micro-mixers at low Reynolds number. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Direct measurement of erythrocyte deformability in diabetes mellitus with a transparent microchannel capillary model and high-speed video camera system.

    Science.gov (United States)

    Tsukada, K; Sekizuka, E; Oshio, C; Minamitani, H

    2001-05-01

    To measure erythrocyte deformability in vitro, we made transparent microchannels on a crystal substrate as a capillary model. We observed axisymmetrically deformed erythrocytes and defined a deformation index directly from individual flowing erythrocytes. By appropriate choice of channel width and erythrocyte velocity, we could observe erythrocytes deforming to a parachute-like shape similar to that occurring in capillaries. The flowing erythrocytes magnified 200-fold through microscopy were recorded with an image-intensified high-speed video camera system. The sensitivity of deformability measurement was confirmed by comparing the deformation index in healthy controls with erythrocytes whose membranes were hardened by glutaraldehyde. We confirmed that the crystal microchannel system is a valuable tool for erythrocyte deformability measurement. Microangiopathy is a characteristic complication of diabetes mellitus. A decrease in erythrocyte deformability may be part of the cause of this complication. In order to identify the difference in erythrocyte deformability between control and diabetic erythrocytes, we measured erythrocyte deformability using transparent crystal microchannels and a high-speed video camera system. The deformability of diabetic erythrocytes was indeed measurably lower than that of erythrocytes in healthy controls. This result suggests that impaired deformability in diabetic erythrocytes can cause altered viscosity and increase the shear stress on the microvessel wall. Copyright 2001 Academic Press.

  19. Streaming potential of superhydrophobic microchannels.

    Science.gov (United States)

    Park, Hung Mok; Kim, Damoa; Kim, Se Young

    2017-03-01

    For the purpose of gaining larger streaming potential, it has been suggested to employ superhydrophobic microchannels with a large velocity slip. There are two kinds of superhydrophobic surfaces, one having a smooth wall with a large Navier slip coefficient caused by the hydrophobicity of the wall material, and the other having a periodic array of no- shear slots of air pockets embedded in a nonslip wall. The electrokinetic flows over these two superhydrophobic surfaces are modelled using the Navier-Stokes equation and convection-diffusion equations of the ionic species. The Navier slip coefficient of the first kind surfaces and the no-shear slot ratio of the second kind surfaces are similar in the sense that the volumetric flow rate increases as these parameter values increase. However, although the streaming potential increases monotonically with respect to the Navier slip coefficient, it reaches a maximum and afterward decreases as the no-shear ratio increases. The results of the present investigation imply that the characterization of superhydrophobic surfaces employing only the measurement of volumetric flow rate against pressure drop is not appropriate and the fine structure of the superhydrophobic surfaces must be verified before predicting the streaming potential and electrokinetic flows accurately. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Spinning and tumbling of micron-sized triangles in a micro-channel shear flow

    Science.gov (United States)

    Fries, J.; Kumar, M. Vijay; Mihiretie, B. Mekonnen; Hanstorp, D.; Mehlig, B.

    2018-03-01

    We report on measurements of the angular dynamics of micron-sized equilaterally triangular platelets suspended in a micro-channel shear flow. Our measurements confirm that such particles spin and tumble like a spheroid in a simple shear. Since the triangle has corners, we can observe the spinning directly. In general, the spinning frequency is different from the tumbling frequency and the spinning is affected by tumbling. This gives rise to doubly periodic angular dynamics.

  1. Varying the agglomeration position of particles in a micro-channel using Acoustic Radiation Force beyond the resonance condition.

    Science.gov (United States)

    Dron, Olivier; Aider, Jean-Luc

    2013-09-01

    It is well-known that particles can be focused at mid-height of a micro-channel using Acoustic Radiation Force (ARF) tuned at the resonance frequency (h=λ/2). The resonance condition is a strong limitation to the use of acoustophoresis (particles manipulation using acoustic force) in many applications. In this study we show that it is possible to focus the particles anywhere along the height of a micro-channel just by varying the acoustic frequency, in contradiction with the resonance condition. This result has been thoroughly checked experimentally. The different physical properties as well as wall materials have been changed. The wall materials is finally the only critical parameters. One of the specificity of the micro-channel is the thickness of the carrier and reflector layer. A preliminary analysis of the experimental results suggests that the acoustic focusing beyond the classic resonance condition can be explained in the framework of the multilayered resonator proposed by Hill [1]. Nevertheless, further numerical studies are needed in order to confirm and fully understand how the acoustic pressure node can be moved over the entire height of the micro channel by varying the acoustic frequency. Despite some uncertainties about the origin of the phenomenon, it is robust and can be used for improved acoustic sorting or manipulation of particles or biological cells in confined set-ups. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Microchannel-connected SU-8 honeycombs by single-step projection photolithography for positioning cells on silicon oxide nanopillar arrays

    International Nuclear Information System (INIS)

    Larramendy, Florian; Paul, Oliver; Blatche, Marie Charline; Mazenq, Laurent; Laborde, Adrian; Temple-Boyer, Pierre

    2015-01-01

    We report on the fabrication, functionalization and testing of SU-8 microstructures for cell culture and positioning over large areas. The microstructure consists of a honeycomb arrangement of cell containers interconnected by microchannels and centered on nanopillar arrays designed for promoting cell positioning. The containers have been dimensioned to trap single cells and, with a height of 50 µm, prevent cells from escaping. The structures are fabricated using a single ultraviolet photolithography exposure with focus depth in the lower part of the SU-8 resist. With optimized process parameters, microchannels of various aspect ratios are thus produced. The cell containers and microchannels serve for the organization of axonal growth between neurons. The roughly 2 µm-high and 500 nm-wide nanopillars are made of silicon oxide structured by deep reactive ion etching. In future work, beyond their cell positioning purpose, the nanopillars could be functionalized as sensors. The proof of concept of the novel microstructure for organized cell culture is given by the successful growth of interconnected PC12 cells. Promoted by the honeycomb geometry, a dense network of interconnections between the cells has formed and the intended intimate contact of cells with the nanopillar arrays was observed by scanning electron microscopy. This proves the potential of these new devices as tools for the controlled cell growth in an interconnected container system with well-defined 3D geometry. (paper)

  3. Research of Spectrometric and Exploitation Characteristics of BGO-PMP-165 Scintiblock in Temperature Interval from +25 to -140$^{o}$C

    CERN Document Server

    Ainbund, M R; Gundorin, N A; Matveev, D V; Serov, D G

    2001-01-01

    Photomultipliers based on microchannel plates are used for fast systems which form time marks of physical setups as well as in special technical areas. It is not uncommon when they substitute traditional dynode system photomultipliers. The possibility of compatible work of the PMP-165 photomultiplier with BGO crystal which were cooled down to temperature necessary for appropriate functioning of a semiconductor Ge detector with taking into account of temperature dependencies of own PMP characteristics is investigated during experiment. Cooling down of the system from room temperature down to v140^{o}C during 8 hours is done. Lower limit of temperature which allows PMP to function properly is registered. Changes of spectrometric characteristics caused by temperature are studied.

  4. Picosecond wide-field time-correlated single photon counting fluorescence microscopy with a delay line anode detector

    Energy Technology Data Exchange (ETDEWEB)

    Hirvonen, Liisa M.; Le Marois, Alix; Suhling, Klaus, E-mail: klaus.suhling@kcl.ac.uk [Department of Physics, King' s College London, Strand, London WC2R 2LS (United Kingdom); Becker, Wolfgang; Smietana, Stefan [Becker & Hickl GmbH, Nahmitzer Damm 30, 12277 Berlin (Germany); Milnes, James; Conneely, Thomas [Photek Ltd., 26 Castleham Rd, Saint Leonards-on-Sea TN38 9NS (United Kingdom); Jagutzki, Ottmar [Institut für Kernphysik, Max-von-Laue-Str. 1, 60438 Frankfurt (Germany)

    2016-08-15

    We perform wide-field time-correlated single photon counting-based fluorescence lifetime imaging (FLIM) with a crossed delay line anode image intensifier, where the pulse propagation time yields the photon position. This microchannel plate-based detector was read out with conventional fast timing electronics and mounted on a fluorescence microscope with total internal reflection (TIR) illumination. The picosecond time resolution of this detection system combines low illumination intensity of microwatts with wide-field data collection. This is ideal for fluorescence lifetime imaging of cell membranes using TIR. We show that fluorescence lifetime images of living HeLa cells stained with membrane dye di-4-ANEPPDHQ exhibit a reduced lifetime near the coverslip in TIR compared to epifluorescence FLIM.

  5. Advancements in the Interferometric Measurements of Real Time Finishing Birefringent Filter's Crystal Plates

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Ma [State Optical Institute, Birzhevaya linia, 12 St. Petersburg (Russian Federation); Kushtal, Gi; Skomorovsky, Vi; Domyshev, Gn; Sadokhin, Vp [Institute of Solar-Terrestrial Physics Siberian Branch of Russian Academy of Sciences, 126 Lermontova Str., PO 4026, 664033, Irkutsk (Russian Federation)

    2006-10-15

    The finishing of birefringent plates consists of two processes: polishing and evaluation of a surface, which have been performed separately till now. The purpose of this work is achieving of high accuracy of the evaluation and machining of the plane-parallel plates from birefringent crystals, in particular of crystal plates of birefringent filters during their finishing. The developed process combines evaluation and polishing in an interactive way. We have found modes of treatment, shape of polisher, have designed interferometer, with a mirror arranged in polisher. Visual checking of optical thickness comparatively with reference plate was carried out using the interference fringes of equal birefringence, and checking of an optical wedge - by interference rings of an equal inclination. The automated processing of TV camera interference fringes was impossible, because of gaps of interference fringes on polishing cells above the mirror. Therefore a special software was developed for processing of a complex fringe pattern interferogram. Software FastInterf uses furrier analysis technique which allows to process an interferogram with multiply gaps. Interferograms are registered by a high resolution TV camera (1280 x1024). Automatic processing of a fringe interferogram using FastInterf software takes less then one second. The influence of gaps is excluded, and the flat field is taken into account. Software provides full 3D surface and wavefront maps. Aberration analysis of a wavefront gives information on thickness of a plate comparatively with a reference one, optical wedge of plate and azimuth of an inclination of wave front. Moreover, software provides a control of surface quality. The measuring device, features of the software are described and process of interferometric evaluation during polishing is illustrated.

  6. Axisymmetric buckling analysis of laterally restrained thick annular plates using a hybrid numerical method

    Energy Technology Data Exchange (ETDEWEB)

    Malekzadeh, P. [Department of Mechanical Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Center of Excellence for Computational Mechanics, Shiraz University, Shiraz (Iran, Islamic Republic of)], E-mail: malekzadeh@pgu.ac.ir; Ouji, A. [Department of Civil Engineering, Persian Gulf University, Bushehr 75168 (Iran, Islamic Republic of); Islamic Azad University, Larestan Branch, Larestan (Iran, Islamic Republic of)

    2008-11-15

    The buckling analysis of annular thick plates with lateral supports such as two-parameter elastic foundations or ring supports is investigated using an elasticity based hybrid numerical method. For this purpose, firstly, the displacement components are perturbed around the pre-buckling state, which is located using the elasticity theory. Then, by decomposing the plate into a set of sub-domain in the form of co-axial annular plates, the buckling equations are discretized through the radial direction using global interpolation functions in conjunction with the principle of virtual work. The resulting differential equations are solved using the differential quadrature method. The method has the capability of modeling the arbitrary boundary conditions either at the inner and outer edges of thin-to-thick plates and with different types of lateral restraints. The fast rate of convergence of the method is demonstrated and comparison studies are carried out to establish its accuracy and versatility for thin-to-thick plates.

  7. Two-Phase Flow in High-Heat-Flux Micro-Channel Heat Sink for Refrigeration Cooling Applications. Part 1: Micro-Channel Heat Sink for Direct Refrigeration Cooling

    Science.gov (United States)

    2008-09-01

    the two-phase mixture exiting the condenser. Throttling from high to low pressure was achieved by a manual metering valve situated upstream of the micro...channel et al. htp N4hsP) correlation (2002) kh sp = Nu kf dh’ Nuta, = const (Refer to Eqs. (1.4.6) and (1.4.7)), = 0.023Re" Prf4 f f E=1.0+6Bol6 +f(Bo)x...12.26% (318 data points) 0Id" +30%OND A ~’AAK - -30%",A- / A’ A* 10 " , , , htp ,&xp [W/M 2 K] Figure 1.4.8 Comparison of heat transfer coefficient

  8. Critical experiment and analysis for nitride fuel fast reactor using FCA

    International Nuclear Information System (INIS)

    Andoh, Masaki; Iijima, Susumu; Okajima, Shigeaki; Sakurai, Takeshi; Oigawa, Hiroyuki

    2000-03-01

    As a research on FBR with new types of fuel, a series of experiments on a nitride fuel fast reactor was carried out at Fast Critical Assembly (FCA) to evaluate the calculation accuracy on the neutronic characteristics of the reactor. In this study, criticality, sample reactivity worth and sodium void reactivity worth were measured in the FCA XIX-2 core simulating a nitride fuel fast reactor and were analyzed using the standard analysis method for FCA fast reactor cores. The accuracy of the analysis on the effective multiplication factor was the same as those of the other FCA cores. For the plate sample reactivity worth, the calculation on the radial distribution of plutonium plate reactivity worth overestimated the measurement depending on the distance from the center of the core. For the sodium void reactivity worth, the calculation overestimated the experimental value 10 to 20% at the core center, while the overestimation was improved as the voided position was located at the core boundary. It was found that the transport effect was considerable even at the center of the core. It was considered that the calculation accuracy on the non-leakage term of the void reactivity worth and transport correction should be improved. (author)

  9. Tentative investigation on neutron mirror fabrication with electroless nickel plating

    International Nuclear Information System (INIS)

    Guo, Jiang; Morita, Shin-ya; Yamagata, Yutaka; Takeda, Shin; Kato, Jun-ichi; Hino, Masahiro; Furusaka, Michihiro

    2013-01-01

    Neutron optics becomes highly required due to the rapid development of neutron technology. In this paper, we attempt to fabricate the neutron mirror by using a metal substrate made of electroless nickel plating to take place of glass concerning about mirror's optical performance and manufacturing method. A new manufacture process chain of neutron mirror is proposed by following the steps of fast milling and precision cutting of aluminium/stainless, electroless nickel plating, ultra-precision cutting by diamond tools, super-smooth polishing and super mirror coating to obtain high form accuracy and good surface roughness time-efficiently. Some tentative investigations are carried out. A workpiece (□ 50 x 50 mm 2 ) with flat surface made of electroless nickel plating is machined by ultra-precision cutting and polishing. The surface roughness with 0.728 nm rms (0.588 nm Ra) is acquired. According to results of reflectometry, the neutron beam can be reflected effectively with high intensity and little scattering. (author)

  10. Investigation of the reflection of fast neutrons

    International Nuclear Information System (INIS)

    Devillers, Christian; Hasselin, Gilbert

    1964-10-01

    The authors report the study of the reflection of fast neutrons on a plane plate having a finite and varying thickness and an infinite width. Calculations are performed by using a Monte-Carlo method which allows the number, the energy, the direction, the emergence point of neutrons reflected on a plate, to be computed with respect to the energy and direction of incident neutrons. The author present how paths, elastic and inelastic shocks, direction after shock are calculated. Different information are calculated: the numbers of elastic shocks, inelastic shocks and transmitted neutrons, the number, energy and dose albedo, the spectrum and angular distribution, the distribution of neutron in terms of energy and direction

  11. MStern Blotting–High Throughput Polyvinylidene Fluoride (PVDF) Membrane-Based Proteomic Sample Preparation for 96-Well Plates*

    OpenAIRE

    Berger, Sebastian T.; Ahmed, Saima; Muntel, Jan; Cuevas Polo, Nerea; Bachur, Richard; Kentsis, Alex; Steen, Judith; Steen, Hanno

    2015-01-01

    We describe a 96-well plate compatible membrane-based proteomic sample processing method, which enables the complete processing of 96 samples (or multiples thereof) within a single workday. This method uses a large-pore hydrophobic PVDF membrane that efficiently adsorbs proteins, resulting in fast liquid transfer through the membrane and significantly reduced sample processing times. Low liquid transfer speeds have prevented the useful 96-well plate implementation of FASP as a widely used mem...

  12. Material and welding development of anchor plates to build nuclear power plant by blue arc process

    International Nuclear Information System (INIS)

    Gibelli, C.E.

    1986-01-01

    To build nuclear power plants, anchor plates are plenty used. These anchor plates serve as a system with the purpose to fix many heavy components or a simple stair. Considering the necessity of element fabrication fastly, with reasonable economy and quality, the arc study welding process (blue arc) was used. A special development of the material concept as well as a welding procedure and a subsuppliers qualification of the raw material was necessary. (Author) [pt

  13. Fast and epithermal neutron radiography using neutron irradiator

    International Nuclear Information System (INIS)

    Oliveira, Karol A.M. de; Crispim, Verginia R.; Ferreira, Francisco J.O.

    2013-01-01

    The neutron radiography technique (NR) with neutrons in the energy range fast to epithermal is a powerful tool used in no-destructive inspection of bulky objects of diverse materials, including those rich in hydrogen, oxygen, nitrogen ad carbon. Thus, it can be used to identify, inclusions, voids and thickness differences in materials such as explosive artifacts and narcotics. Aiming at using NR with fast and epithermal neutrons, an Irradiator was constructed by: a 241 Am-Be source, with 5 Ci activity, a collimator with adjustable collimation rate, L/D; and a shield device composed by plates of borated paraffin and iron. The test specimens chosen were a Beam Purity Indicator (BPI) and an Indicator of Visual Resolution (IVR). The neutron radiography images obtained had a resolution of 444.4 μm and 363.6 μm respectively when registered in: 1) the sheet of the nuclear track solid detector, CR-39 type, through X (n,p) Y nuclear reaction; and 2) Kodak Industrex M radiographic film plate in close contact with a boron converter screen, both stored in a Kodak radiographic cassette. (author)

  14. Flame dynamics in a micro-channeled combustor

    International Nuclear Information System (INIS)

    Hussain, Taaha; Balachandran, Ramanarayanan; Markides, Christos N.

    2015-01-01

    The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of

  15. Flame dynamics in a micro-channeled combustor

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Taaha; Balachandran, Ramanarayanan, E-mail: r.balachandran@ucl.ac.uk [Department of Mechanical Engineering, University College London, London (United Kingdom); Markides, Christos N. [Clean Energy Processes Laboratory, Department of Chemical Engineering, Imperial College London, London (United Kingdom)

    2015-01-22

    The increasing use of Micro-Electro-Mechanical Systems (MEMS) has generated a significant interest in combustion-based power generation technologies, as a replacement of traditional electrochemical batteries which are plagued by low energy densities, short operational lives and low power-to-size and power-to-weight ratios. Moreover, the versatility of integrated combustion-based systems provides added scope for combined heat and power generation. This paper describes a study into the dynamics of premixed flames in a micro-channeled combustor. The details of the design and the geometry of the combustor are presented in the work by Kariuki and Balachandran [1]. This work showed that there were different modes of operation (periodic, a-periodic and stable), and that in the periodic mode the flame accelerated towards the injection manifold after entering the channels. The current study investigates these flames further. We will show that the flame enters the channel and propagates towards the injection manifold as a planar flame for a short distance, after which the flame shape and propagation is found to be chaotic in the middle section of the channel. Finally, the flame quenches when it reaches the injector slots. The glow plug position in the exhaust side ignites another flame, and the process repeats. It is found that an increase in air flow rate results in a considerable increase in the length (and associated time) over which the planar flame travels once it has entered a micro-channel, and a significant decrease in the time between its conversion into a chaotic flame and its extinction. It is well known from the literature that inside small channels the flame propagation is strongly influenced by the flow conditions and thermal management. An increase of the combustor block temperature at high flow rates has little effect on the flame lengths and times, whereas at low flow rates the time over which the planar flame front can be observed decreases and the time of

  16. The effects of different nano particles of Al2O3 and Ag on the MHD nano fluid flow and heat transfer in a microchannel including slip velocity and temperature jump

    Science.gov (United States)

    Karimipour, Arash; D'Orazio, Annunziata; Shadloo, Mostafa Safdari

    2017-02-01

    The forced convection of nanofluid flow in a long microchannel is studied numerically according to the finite volume approach and by using a developed computer code. Microchannel domain is under the influence of a magnetic field with uniform strength. The hot inlet nanofluid is cooled by the heat exchange with the cold microchannel walls. Different types of nanoparticles such as Al2O3 and Ag are examined while the base fluid is considered as water. Reynolds number are chosen as Re=10 and Re=100. Slip velocity and temperature jump boundary conditions are simulated along the microchannel walls at different values of slip coefficient for different amounts of Hartmann number. The investigation of magnetic field effect on slip velocity and temperature jump of nanofluid is presented for the first time. The results are shown as streamlines and isotherms; moreover the profiles of slip velocity and temperature jump are drawn. It is observed that more slip coefficient corresponds to less Nusselt number and more slip velocity especially at larger Hartmann number. It is recommended to use Al2O3-water nanofluid instead of Ag-water to increase the heat transfer rate from the microchannel walls at low values of Re. However at larger amounts of Re, the nanofluid composed of nanoparticles with higher thermal conductivity works better.

  17. Enabling fast charging – A battery technology gap assessment

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Shabbir; Bloom, Ira; Jansen, Andrew N.; Tanim, Tanvir; Dufek, Eric J.; Pesaran, Ahmad; Burnham, Andrew; Carlson, Richard B.; Dias, Fernando; Hardy, Keith; Keyser, Matthew; Kreuzer, Cory; Markel, Anthony; Meintz, Andrew; Michelbacher, Christopher; Mohanpurkar, Manish; Nelson, Paul A.; Robertson, David C.; Scoffield, Don; Shirk, Matthew; Stephens, Thomas; Vijayagopal, Ram; Zhang, Jiucai

    2017-11-01

    The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; measure temperature distributions during fast charge to enable / validate models; and develop thermal management and pack designs to accommodate the higher operating voltage.

  18. Electron cloud observations at the ISIS Proton Synchrotron

    CERN Document Server

    Pertica, A.

    2013-04-22

    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.

  19. The effects of viscosity, surface tension, and flow rate on gasoil-water flow pattern in microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Boogar, Rahman Sadeghi; Gheshlaghi, Reza; Mahdavi, Mahmood Akhavan [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2013-01-15

    A microchannel was fabricated with glass tubes to investigate the effect of viscosity, surface tension, and flow rate on the liquid-liquid two-phase flow regime. Water and gasoil were selected as aqueous and organic working fluids, respectively. The two fluids were injected into the microchannel and created either slug or parallel profile depending on the applied conditions. The range of Reynolds and capillary numbers was chosen in such a way that neither inertia nor interfacial tension forces were negligible. Xanthan gum was used to increase viscosity and Triton X-100 (TX-100) and Sodium Dodecyl Sulfate (SDS) were used to reduce the interfacial tension. The results demonstrated that higher value of viscosity and flow rate increased interfacial area, but slug flow regime remained unchanged. The two surfactants showed different effects on the flow regime and interfacial area. Addition of TX-100 did not change the slug flow but decreased the interfacial area. In contrast, addition of SDS increased interfacial area by decreasing the slug’s length in the low concentrations and by switching from slug to parallel regime at high concentrations.

  20. Numerical simulation of the droplet formation in a cross-junction microchannel using the Lattice Boltzmann Method

    International Nuclear Information System (INIS)

    Li, Zilu; Kang, Jinfen; Park, Jae Hyun; Suh, Yong Kweon

    2007-01-01

    This study describes the numerical simulation of two-dimensional droplet formation and the following motion by using the Lattice Boltzmann Method (LBM) with the phase field equation. The free energy model is used to treat the interfacial force and the deformation of a binary fluid system, drawn into a cross-junction microchannel. While one fluid is introduced through the central inlet channel, the other fluid is drawn into the main channel through the two vertical inlet channels. Due to the effect of surface tension on the interface between the two fluids, the droplets of the first fluid are formed near the cross-junction. The aim in this investigation is to examine the applicability of LBM to the numerical analysis of the droplet formation and its motion in the microchannel. It was found from comparison with the experimentally visualized patterns that LBM with the free energy model can reproduce the droplet formation successfully. However because of the stability problem which is intrinsic for high surface-tension cases, it requires a very long computational time. This issue is to be resolved in the future.

  1. Numerical simulation of the droplet formation in a cross-junction microchannel using the Lattice Boltzmann Method

    International Nuclear Information System (INIS)

    Li, Zi Lu; Kang, Jin Fen; Park, Jae Hyun; Suh, Yong Kweon

    2007-01-01

    This study describes the numerical simulation of two-dimensional droplet formation and the following motion by using the Lattice Boltzmann Method (LBM) with the phase field equation. The free energy model is used to treat the interfacial force and the deformation of a binary fluid system, drawn into a cross-junction microchannel. While one fluid is introduced through the central inlet channel, the other fluid is drawn into the main channel through the two vertical inlet channels. Due to the effect of surface tension on the interface between the two fluids, the droplets of the first fluid are formed near the cross-junction. The aim in this investigation is to examine the applicability of LBM to the numerical analysis of the droplet formation and its motion in the microchannel. It was found from comparison with the experimentally visualized patterns that LBM with the free energy model can reproduce the droplet formation successfully. However because of the stability problem which is intrinsic for high surface-tension cases, it requires a very long computational time. This issue is to be resolved in the future

  2. New technology of lead-tin plating of superconducting RF resonators for the ANU LINAC

    International Nuclear Information System (INIS)

    Lobanov, N.R.; Weisser, D.C.

    2003-01-01

    The RF accelerating resonators for the ANU superconducting LINAC have been re-plated with lead-tin and their performance substantially improved. The re-plating was at first derailed by the appearance of dendrites on the surface. This problem was overcome by a new combination of two techniques. Rather than the standard process of chemically stripping the old Pb and hand polishing the Cu substrate the unsatisfactory Pb surface was mechanically polished and then re-plated. This is enormously easier, faster and doesn't put at risk the thin cosmetic electron beam welds or the repaired ones. Reverse pulse plating was then used to re-establish an excellent superconducting surface. Average acceleration fields of 3.5 to 3.9 MV/m have been achieved. The re-plated resonators will double the energy gain of the accelerator significantly extending capability of the facility research. Lead-tin plating provides fast adequate results with modest equipment and at relatively low cost. SUNY re-plated six high-beta SLRs with 2 microns of Pb-Sn using a modern, commercial, methane-sulfonate process (Lea Ronal Solderon MHS-L) and a simple open-air procedure. This proven success motivated ANU to adopt MSA chemistry and to re-plate the first SLR in November 1998 followed by re-plating all twelve SLRs by November 2002. This increased the booster energy gain by almost 100%

  3. Increasing heat transfer of non-Newtonian nanofluid in rectangular microchannel with triangular ribs

    Science.gov (United States)

    Shamsi, Mohammad Reza; Akbari, Omid Ali; Marzban, Ali; Toghraie, Davood; Mashayekhi, Ramin

    2017-09-01

    In this study, computational fluid dynamics and the laminar flow of the non-Newtonian fluid have been numerically studied. The cooling fluid includes water and 0.5 wt% Carboxy methyl cellulose (CMC) making the non-Newtonian fluid. In order to make the best of non-Newtonian nanofluid in this simulation, solid nanoparticles of Aluminum Oxide have been added to the non-Newtonian fluid in volume fractions of 0-2% with diameters of 25, 45 and 100 nm. The supposed microchannel is rectangular and two-dimensional in Cartesian coordination. The power law has been used to speculate the dynamic viscosity of the cooling nanofluid. The field of numerical solution is simulated in the Reynolds number range of 5 nanoparticles as well as the use for nanoparticles with smaller diameters lead to greater heat transfer. Among all the studied forms, the triangular rib from with an angle of attack 30° has the biggest Nusselt number and the smallest pressure drop along the microchannel. Also, an increase in the angle of attack and as a result of a sudden contact between the fluid and the ribs and also a reduction in the coflowing length (length of the rib) cause a cut in heat transfer by the fluid in farther parts from the solid wall (tip of the rib).

  4. A highly efficient autothermal microchannel reactor for ammonia decomposition: Analysis of hydrogen production in transient and steady-state regimes

    Science.gov (United States)

    Engelbrecht, Nicolaas; Chiuta, Steven; Bessarabov, Dmitri G.

    2018-05-01

    The experimental evaluation of an autothermal microchannel reactor for H2 production from NH3 decomposition is described. The reactor design incorporates an autothermal approach, with added NH3 oxidation, for coupled heat supply to the endothermic decomposition reaction. An alternating catalytic plate arrangement is used to accomplish this thermal coupling in a cocurrent flow strategy. Detailed analysis of the transient operating regime associated with reactor start-up and steady-state results is presented. The effects of operating parameters on reactor performance are investigated, specifically, the NH3 decomposition flow rate, NH3 oxidation flow rate, and fuel-oxygen equivalence ratio. Overall, the reactor exhibits rapid response time during start-up; within 60 min, H2 production is approximately 95% of steady-state values. The recommended operating point for steady-state H2 production corresponds to an NH3 decomposition flow rate of 6 NL min-1, NH3 oxidation flow rate of 4 NL min-1, and fuel-oxygen equivalence ratio of 1.4. Under these flows, NH3 conversion of 99.8% and H2 equivalent fuel cell power output of 0.71 kWe is achieved. The reactor shows good heat utilization with a thermal efficiency of 75.9%. An efficient autothermal reactor design is therefore demonstrated, which may be upscaled to a multi-kW H2 production system for commercial implementation.

  5. High-Throughput Particle Manipulation Based on Hydrodynamic Effects in Microchannels

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2017-03-01

    Full Text Available Microfluidic techniques are effective tools for precise manipulation of particles and cells, whose enrichment and separation is crucial for a wide range of applications in biology, medicine, and chemistry. Recently, lateral particle migration induced by the intrinsic hydrodynamic effects in microchannels, such as inertia and elasticity, has shown its promise for high-throughput and label-free particle manipulation. The particle migration can be engineered to realize the controllable focusing and separation of particles based on a difference in size. The widespread use of inertial and viscoelastic microfluidics depends on the understanding of hydrodynamic effects on particle motion. This review will summarize the progress in the fundamental mechanisms and key applications of inertial and viscoelastic particle manipulation.

  6. Proton beam micromachined buried microchannels in negative tone resist materials

    International Nuclear Information System (INIS)

    Rajta, I.; Chatzichristidi, M.; Baradacs, E.; Cserhati, C.; Raptis, I.; Manoli, K.; Valamontes, E.S.

    2007-01-01

    In the present work the Atomki, Debrecen microprobe facility has been used to write long tilted structures by 2 MeV protons. For the formation of the structures, two exposures have been carried out at +20 o and -20 o using a goniometer stage sample holder. The tilted structures were resolved in the negative tone resist materials SU-8 and ADEPR (an aqueous base developable chemically amplified resist). The length of the microchannels was varied between 100 μm and 1000 μm, the wall thickness was less than 10 μm. By applying the developed methodology it was possible to resolve the desired layout through the whole length of the channel

  7. Cold plate

    Energy Technology Data Exchange (ETDEWEB)

    Marroquin, Christopher M.; O' Connell, Kevin M.; Schultz, Mark D.; Tian, Shurong

    2018-02-13

    A cold plate, an electronic assembly including a cold plate, and a method for forming a cold plate are provided. The cold plate includes an interface plate and an opposing plate that form a plenum. The cold plate includes a plurality of active areas arranged for alignment over respective heat generating portions of an electronic assembly, and non-active areas between the active areas. A cooling fluid flows through the plenum. The plenum, at the non-active areas, has a reduced width and/or reduced height relative to the plenum at the active areas. The reduced width and/or height of the plenum, and exterior dimensions of cold plate, at the non-active areas allow the non-active areas to flex to accommodate surface variations of the electronics assembly. The reduced width and/or height non-active areas can be specifically shaped to fit between physical features of the electronics assembly.

  8. Scaling Law for Cross-stream Diffusion in Microchannels under Combined Electroosmotic and Pressure Driven Flow.

    Science.gov (United States)

    Song, Hongjun; Wang, Yi; Pant, Kapil

    2013-01-01

    This paper presents an analytical study of the cross-stream diffusion of an analyte in a rectangular microchannel under combined electroosmotic flow (EOF) and pressure driven flow to investigate the heterogeneous transport behavior and spatially-dependent diffusion scaling law. An analytical model capable of accurately describing 3D steady-state convection-diffusion in microchannels with arbitrary aspect ratios is developed based on the assumption of the thin Electric Double Layer (EDL). The model is verified against high-fidelity numerical simulation in terms of flow velocity and analyte concentration profiles with excellent agreement (parametric analysis is then undertaken to interrogate the effect of the combined flow velocity field on the transport behavior in both the positive pressure gradient (PPG) and negative pressure gradient (NPG) cases. For the first time, the evolution from the spindle-shaped concentration profile in the PPG case, via the stripe-shaped profile (pure EOF), and finally to the butterfly-shaped profile in the PPG case is obtained using the analytical model along with a quantitative depiction of the spatially-dependent diffusion layer thickness and scaling law across a wide range of the parameter space.

  9. Investigation of Different Droplet Formation Regimes in a T-junction Microchannel Using the VOF Technique in OpenFOAM

    Science.gov (United States)

    Malekzadeh, Shima; Roohi, Ehsan

    2015-06-01

    Here we aimed to investigate various droplet formation regimes in a two-dimensional T-junction microchannel geometry using the open source software OpenFOAM. Two incompressible fluids, continuous phase in the main channel and dispersed phase in the lateral channel, have been considered. The interFoam solver was used to simulate laminar flow with two incompressible and isothermal phases. We evaluated the capability of "Compressive Interface Capturing Scheme for Arbitrary Meshes (CICSAM)" volume of fluid (VOF) technique of the OpenFOAM for modeling of the droplet formation and movement in different regimes. The flow behavior in the T-junction microchannel over a wide range of capillary numbers (0.006 to 0.12), volume flow rate ratio (0.125, 0.25, 0.5), and contact angle (130° to 180°) in the squeezing, dripping and jetting regimes were examined.The importance of parameters such as contact angle, capillary number, flow rate ratio, and Reynolds number at the time of separation, as well as the formation of droplets, was investigated in different regimes. We found that droplet detachment time increases by increasing the contact angle in the squeezing regime while increasing the contact angle in the dripping regime results in a decrease in the droplet detachment time. We compare the role of pressure gradient and shear stress forces in the droplet formation process in both dripping and squeezing regimes in details. We also provide a classification of two-phase flow regimes in the investigated T-junction microchannel in terms of three main parameters of, e.g., flow rate ratio, contact angle, and capillary number.

  10. Effect of laser beam conditioning on fabrication of clean micro-channel on stainless steel 316L using second harmonic of Q-switched Nd:YAG laser

    Science.gov (United States)

    Singh, Sanasam Sunderlal; Baruah, Prahlad Kr; Khare, Alika; Joshi, Shrikrishna N.

    2018-02-01

    Laser micromachining of metals for fabrication of micro-channels generate ridge formation along the edges accompanied by ripples along the channel bed. The ridge formation is due to the formation of interference pattern formed by back reflections from the beam splitter and other optical components involved before focusing on the work piece. This problem can be curtailed by using a suitable aperture or Iris diaphragm so as to cut the unwanted portion of the laser beam before illuminating the sample. This paper reports an experimental investigation on minimizing this problem by conditioning the laser beam using an Iris diaphragm and using optimum process parameters. In this work, systematic experiments have been carried out using the second harmonic of a Q-switched Nd:YAG laser to fabricate micro-channels. Initial experiments revealed that formation of ridges along the sides of micro-channel can easily be minimized with the help of Iris diaphragm. Further it is noted that a clean micro-channel of depth 43.39 μm, width up to 64.49 μm and of good surface quality with average surface roughness (Ra) value of 370 nm can be machined on stainless steel (SS) 316L by employing optimum process condition: laser beam energy of 30 mJ/pulse, 11 number of laser scans and scan speed of 169.54 μm/s with an opening of 4 mm diameter of Iris diaphragm in the path of the laser beam.

  11. Global Dynamic Numerical Simulations of Plate Tectonic Reorganizations

    Science.gov (United States)

    Morra, G.; Quevedo, L.; Butterworth, N.; Matthews, K. J.; Müller, D.

    2010-12-01

    We use a new numerical approach for global geodynamics to investigate the origin of present global plate motion and to identify the causes of the last two global tectonic reorganizations occurred about 50 and 100 million years ago (Ma) [1]. While the 50 Ma event is the most well-known global plate-mantle event, expressed by the bend in the Hawaiian-Emperor volcanic chain, a prominent plate reorganization at about 100 Ma, although presently little studied, is clearly indicated by a major bend in the fracture zones in the Indian Ocean and by a change in Pacific plate motion [2]. Our workflow involves turning plate reconstructions into surface meshes that are subsequently employed as initial conditions for global Boundary Element numerical models. The tectonic setting that anticipates the reorganizations is processed with the software GPlates, combining the 3D mesh of the paleo-plate morphology and the reconstruction of paleo-subducted slabs, elaborated from tectonic history [3]. All our models involve the entire planetary system, are fully dynamic, have free surface, are characterized by a spectacular computational speed due to the simultaneous use of the multi-pole algorithm and the Boundary Element formulation and are limited only by the use of sharp material property variations [4]. We employ this new tool to unravel the causes of plate tectonic reorganizations, producing and comparing global plate motion with the reconstructed ones. References: [1] Torsvik, T., Müller, R.D., Van der Voo, R., Steinberger, B., and Gaina, C., 2008, Global Plate Motion Frames: Toward a unified model: Reviews in Geophysics, VOL. 46, RG3004, 44 PP., 2008 [2] Wessel, P. and Kroenke, L.W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research, Vol 113, B06101, 2008 [3] L. Quevedo, G. Morra, R. D. Mueller. Parallel Fast Multipole Boundary Element Method for Crustal Dynamics, Proceeding 9th World Congress and 4th Asian

  12. Radiation hardness tests and characterization of the CLARO-CMOS, a low power and fast single-photon counting ASIC in 0.35 micron CMOS technology

    International Nuclear Information System (INIS)

    Fiorini, M.; Andreotti, M.; Baldini, W.; Calabrese, R.; Carniti, P.; Cassina, L.; Cotta Ramusino, A.; Giachero, A.; Gotti, C.; Luppi, E.; Maino, M.; Malaguti, R.; Pessina, G.; Tomassetti, L.

    2014-01-01

    The CLARO-CMOS is a prototype ASIC that allows fast photon counting with 5 ns peaking time, a recovery time to baseline smaller than 25 ns, and a power consumption of less than 1 mW per channel. This chip is capable of single-photon counting with multi-anode photomultipliers and finds applications also in the read-out of silicon photomultipliers and microchannel plates. The prototype is realized in AMS 0.35 micron CMOS technology. In the LHCb RICH environment, assuming 10 years of operation at the nominal luminosity expected after the upgrade in Long Shutdown 2 (LS2), the ASIC must withstand a total fluence of about 6×10 12 1 MeV n eq /cm 2 and a total ionizing dose of 400 krad. A systematic evaluation of the radiation effects on the CLARO-CMOS performance is therefore crucial to ensure long term stability of the electronics front-end. The results of multi-step irradiation tests with neutrons and X-rays up to the fluence of 10 14 cm −2 and a dose of 4 Mrad, respectively, are presented, including measurement of single event effects during irradiation and chip performance evaluation before and after each irradiation step. - Highlights: • CLARO chip capable of single-photon counting with 5 ns peaking time. • Chip irradiated up to very high neutron, proton and X-rays fluences, as expected for upgraded LHCb RICH detectors. • No significant performance degradation is observed after irradiation

  13. Investigating performance of microchannel evaporators with different manifold structures

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Junye; Qu, Xiaohua; Qi, Zhaogang; Chen, Jiangping [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, No. 800, Dongchuan Rd, Shanghai 200240 (China)

    2011-01-15

    In this paper, the performances of microchannel evaporators with different manifold structures are experimentally investigated. Eight evaporator samples with 7 different designs of the I/O manifold and 5 different designs of the return manifold are made for this study. The performances of the evaporator samples are tested on a psychometric calorimeter test bench with the refrigerant 134A at a real automotive AC condition. The results on the variations of the cooling capacity and air temperature distribution of the evaporator due to the deflector designs in the I/O manifold and flow hole arrangements in the return manifold are presented and analyzed. By studying the KPI's for the performance of an evaporator, the design trade-off for an evaporator designer is summarized and discussed. (author)

  14. A performance evaluation of a microchannel reactor for the production of hydrogen from formic acid for electrochemical energy applications

    CSIR Research Space (South Africa)

    Ndlovu, IM

    2017-12-01

    Full Text Available An experimental evaluation of a microchannel reactor was completed to assess the reactor performance for the catalytic decomposition of vaporised formic acid (FA) for H2 production. Initially, X-ray powder diffraction (XRD), elemental mapping using...

  15. Cooling high heat flux micro-electronic systems using refrigerants in high aspect ratio multi-microchannel evaporators

    International Nuclear Information System (INIS)

    Costa-Patry, E.

    2011-11-01

    Improving the energy efficiency of cooling systems can contribute to reduce the emission of greenhouse gases. Currently, most microelectronic applications are air-cooled. Switching to two-phase cooling systems would decrease power consumption and allow for the reuse of the extracted heat. For this type of application, multi-microchannel evaporators are thought to be well adapted. However, such devices have not been tested for a wide range of operating conditions, such that their thermal response to the high non-uniform power map typically generated by microelectronics has not been studied. This research project aims at clarifying these gray areas by investigating the behavior of the two-phase flow of different refrigerants in silicon and copper multi-microchannel evaporators under uniform, non-uniform and transient heat fluxes operating conditions. The test elements use as a heat source a pseudo-chip able to mimic the behavior of a CPU. It is formed by 35 independent sub-heaters, each having its own temperature sensor, such that 35 temperature and 35 heat flux measurements can be made simultaneously. Careful measurements of each pressure drop component (inlet, microchannels and outlet) found in the micro-evaporators showed the importance of the inlet and outlet restriction pressure losses. The overall pressure drop levels found in the copper test section were low enough to possibly be driven by a thermosyphon system. The heat transfer coefficients measured for uniform heat flux conditions were very high and typically followed a V-shape curve. The first branch was associated to the slug flow regime and the second to the annular flow regime. By tracking the minimum level of heat transfer, a transition criteria between the regimes was established, which included the effect of heat flux on the transition. Then for each branch, a different prediction method was used to form the first flow pattern-based prediction method for two-phase heat transfer in microchannels. A

  16. Experimental study of gas-liquid flow local characteristics in rectangular microchannel

    Directory of Open Access Journals (Sweden)

    Bartkus German

    2017-01-01

    Full Text Available Using high-speed video recording and the method of dual laser scanning the gas-liquid flow was investigated in a rectangular microchannel with an aspect ratio of 0.74 (cross section 269×362 μm. The T-mixer was used at the channel’s inlet for the two-phase flow formation. The peculiarity of this work is using a number of liquids (ethanol, distilled water, 40% aqueous ethanol with different physical properties, including surface tension, viscosity, and density, with nitrogen. Experiments were carried out for the vertically upward and horizontal flow. Using laser scanning method the maps of flow patterns were obtained for all mixtures.

  17. Numerical investigation of non-Newtonian nanofluid flow in a converging microchannel

    Energy Technology Data Exchange (ETDEWEB)

    Mohsenian, S.; Ramiar, A.; Ranjbar, A. A. [Faculty of Mechanical Engineering, Babol Noshirvani University of Technology, Babol (Iran, Islamic Republic of)

    2017-01-15

    In the present study the flow of non-Newtonian nanofluid through a converging microchannel is investigated numerically. TiO{sub 2} nanoparticles with 10 nm diameter are dispersed in an aqueous solution of 0.5 %.wt Carboxymethyl cellulose (CMC) to produce the nanofluid. Both nanofluid and the base fluid show pseudoplastic behavior. The equations have been solved with finite volume approach using collocated grid. It has been found that by increasing the volume fraction and Reynolds number and the convergence angle, the Nusselt number increases. Also, it has been observed that by increasing convergence angle and decreasing aspect ratio of the channel, the velocity of the channel increases.

  18. Steam conversion of liquefied petroleum gas and methane in microchannel reactor

    Science.gov (United States)

    Dimov, S. V.; Gasenko, O. A.; Fokin, M. I.; Kuznetsov, V. V.

    2018-03-01

    This study presents experimental results of steam conversion of liquefied petroleum gas and methane in annular catalytic reactor - heat exchanger. The steam reforming was done on the Rh/Al2O3 nanocatalyst with the heat applied through the microchannel gap from the outer wall. Concentrations of the products of chemical reactions in the outlet gas mixture are measured at different temperatures of reactor. The range of channel wall temperatures at which the ratio of hydrogen and carbon oxide in the outlet mixture grows substantially is determined. Data on the composition of liquefied petroleum gas conversion products for the ratio S/C = 5 was received for different GHVS.

  19. A fast chopper for the Fermilab High Intensity Neutrino Source (HINS)

    Energy Technology Data Exchange (ETDEWEB)

    Madrak, R.; Wildman, D.; /Fermilab; Dymokde-Bradshaw, A.; Hares, J.; Kellett, P.

    2008-10-01

    A fast chopper capable of kicking single 2.5 MeV H-bunches spaced at 325 MHz, at rates greater than 50 MHz is needed for the Fermilab High Intensity Neutrino Source (HINS) [1]. Four 1.2 kV fast pulsers, designed and manufactured by Kentech Instruments Ltd., will drive a 0.5 m long meander made from a copper plated ceramic composite. Test results showing pulses from the first 1.2 kV pulser and meander results will be presented.

  20. High counting rate resistive-plate chamber

    International Nuclear Information System (INIS)

    Peskov, V.; Anderson, D.F.; Kwan, S.

    1993-05-01

    Parallel-plate avalanche chambers (PPAC) are widely used in physics experiments because they are fast ( 5 counts/mm 2 . A resistive-plate chamber (RPC) is similar to the PPAC in construction except that one or both of the electrodes are made from high resistivity (≥10 10 Ω·cm) materials. In practice RPCs are usually used in the spark mode. Resistive electrodes are charged by sparks, locally reducing the actual electric field in the gap. The size of the charged surface is about 10 mm 2 , leaving the rest of the detector unaffected. Therefore, the rate capability of such detectors in the spark mode is considerably higher than conventional spark counters. Among the different glasses tested the best results were obtained with electron type conductive glasses, which obey Ohm's law. Most of the work with such glasses was done with high pressure parallel-plate chambers (10 atm) for time-of-flight measurements. Resistive glasses have been expensive and produced only in small quantities. Now resistive glasses are commercially available, although they are still expensive in small scale production. From the positive experience of different groups working with the resistive glasses, it was decided to review the old idea to use this glass for the RPC. This work has investigated the possibility of using the RPC at 1 atm and in the avalanche mode. This has several advantages: simplicity of construction, high rate capability, low voltage operation, and the ability to work with non-flammable gases