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Sample records for high-aspect ratio holes

  1. Measurement and simulation of jet mass caused by a high-aspect ratio hole perturbation

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Paul A [Los Alamos National Laboratory; Cooley, James H [Los Alamos National Laboratory; Wilson, D C [Los Alamos National Laboratory; Kyrala, George A [Los Alamos National Laboratory; Blue, Brent E [LLNL; Edwards, J [LLNL; Elliott, James B [LLNL; Robey, H F [LLNL; Spears, B [Los Alamos National Laboratory

    2009-01-01

    Inertial confinement fusion (ICF) capsule performance can be negatively impacted by the presence of hydrodynamic instabilities. To perform a gas fill on an ICF capsule, current plans involve drilling a small hole and inserting a fill tube to inject the gas mixture into the capsule. This introduces a perturbation on the capsule, which can seed hydrodynamic instabilities. The small hole can cause jetting of the shell material into the gas, which might adversely affect the capsule performance. We have performed simulations and experiments to study the hydrodynamic evolution of jets from high-aspect ratio holes, such as the fill tube hole. Although simulations using cold materials overpredict the amount of mass in the jet, when a reasonable amount of preheat (<1 eV) is introduced, the simulations are in better agreement with the experiment.

  2. The Capabilities of Electrodischarge Microdrilling of High Aspect Ratio Holes in Ceramic Materials

    Directory of Open Access Journals (Sweden)

    Skoczypiec Sebastian

    2015-09-01

    Full Text Available In the first part of the article the review of ceramic materials drilling possibilities was presented. Among the described methods special attention is paid to electrodischarge drilling. This process have especially been predicted for machining difficult-to-cut electrically conductive materials. The second part consist of the results analysis of electrodischarge microdrilling of siliconized silicon carbide. The experiment involves the impact of current amplitude, discharge voltage and pulse time on the hole depth, side gap, linear tool wear and mean drilling speed. The results shows that electrodischarge drilling is a good alternative when machining inhomogeneous ceramic materials and gives possibility to drill high aspect ratio holes with relatively high efficiency (the drilling speed >2 mm/min.

  3. Measuring ion velocity distribution functions through high-aspect ratio holes in inductively coupled plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Cunge, G., E-mail: gilles.cunge@cea.fr; Darnon, M.; Dubois, J.; Bezard, P.; Mourey, O.; Petit-Etienne, C.; Vallier, L.; Despiau-Pujo, E.; Sadeghi, N. [Laboratoire des Technologies de la Microélectronique, CNRS, 17 rue des Martyrs, 38054 Grenoble (France)

    2016-02-29

    Several issues associated with plasma etching of high aspect ratio structures originate from the ions' bombardment of the sidewalls of the feature. The off normal angle incident ions are primarily due to their temperature at the sheath edge and possibly to charging effects. We have measured the ion velocity distribution function (IVDF) at the wafer surface in an industrial inductively coupled plasma reactor by using multigrid retarding field analyzers (RFA) in front of which we place 400 μm thick capillary plates with holes of 25, 50, and 100 μm diameters. The RFA then probes IVDF at the exit of the holes with Aspect Ratios (AR) of 16, 8, and 4, respectively. The results show that the ion flux dramatically drops with the increase in AR. By comparing the measured IVDF with an analytical model, we concluded that the ion temperature is 0.27 eV in our plasma conditions. The charging effects are also observed and are shown to significantly reduce the ion energy at the bottom of the feature but only with a “minor” effect on the ion flux and the shape of the IVDF.

  4. Real time ablation rate measurement during high aspect-ratio hole drilling with a 120-ps fiber laser.

    Science.gov (United States)

    Mezzapesa, Francesco P; Sibillano, Teresa; Di Niso, Francesca; Ancona, Antonio; Lugarà, Pietro M; Dabbicco, Maurizio; Scamarcio, Gaetano

    2012-01-02

    We report on the instantaneous detection of the ablation rate as a function of depth during ultrafast microdrilling of metal targets. The displacement of the ablation front has been measured with a sub-wavelength resolution using an all-optical sensor based on the laser diode self-mixing interferometry. The time dependence of the laser ablation process within the depth of aluminum and stainless steel targets has been investigated to study the evolution of the material removal rate in high aspect-ratio micromachined holes.

  5. Interaction between photoresist pretreatment and high-aspect-ratio contact and via hole definition

    Science.gov (United States)

    Brown, Kevin C.; Insalaco, Linda J.; Szeto, Elina C.

    1993-09-01

    The relationship between photoresist treatment prior to etch and subsequent oxide sidewall hole profile is investigated. Etched features were examined immediately after resist pattern definition with post-expose bake, then after oven hard bake or deep UV photostabilization. It was observed that taper of the etched oxide profile depends on pre-treatment temperature. Etch chemistry influences the relative change in taper across a range of pre-treatment temperatures. `Bowing,' as well as reticulated or `burnt' resist is eliminated. Profile variation across the wafer is reduced with deep UV photostabilization. Microscopic etch uniformity (RIE lag) also depends on the interaction between resist pre-treatment and oxide etch chemistry.

  6. Direct investigation of the ablation rate evolution during laser drilling of high-aspect-ratio micro-holes

    Science.gov (United States)

    Mezzapesa, Francesco P.; Sibillano, Teresa; Columbo, Lorenzo L.; Di Niso, Francesca; Ancona, Antonio; Dabbicco, Maurizio; De Lucia, Francesco; Lugarà, Pietro M.; Scamarcio, Gaetano

    2012-03-01

    The recent development of ultrafast laser ablation technology in precision micromachining has dramatically increased the demand for reliable and real-time detection systems to characterize the material removal process. In particular, the laser percussion drilling of metals is lacking of non-invasive techniques able to monitor into the depth the spatial- and time-dependent evolution all through the ablation process. To understand the physical interaction between bulk material and high-energy light beam, accurate in-situ measurements of process parameters such as the penetration depth and the removal rate are crucial. We report on direct real time measurements of the ablation front displacement and the removal rate during ultrafast laser percussion drilling of metals by implementing a contactless sensing technique based on optical feedback interferometry. High aspect ratio micro-holes were drilled onto steel plates with different thermal properties (AISI 1095 and AISI 301) and Aluminum samples using 120-ps/110-kHz pulses delivered by a microchip laser fiber amplifier. Percussion drilling experiments have been performed by coaxially aligning the diode laser probe beam with the ablating laser. The displacement of the penetration front was instantaneously measured during the process with a resolution of 0.41 μm by analyzing the sawtooth-like induced modulation of the interferometric signal out of the detector system.

  7. Real time ablation rate measurement during high aspect-ratio hole drilling with a 120-ps fiber laser

    National Research Council Canada - National Science Library

    Mezzapesa, Francesco P; Sibillano, Teresa; Di Niso, Francesca; Ancona, Antonio; Lugarà, Pietro M; Dabbicco, Maurizio; Scamarcio, Gaetano

    2012-01-01

    .... The time dependence of the laser ablation process within the depth of aluminum and stainless steel targets has been investigated to study the evolution of the material removal rate in high aspect...

  8. Noise of Embedded High Aspect Ratio Nozzles

    Science.gov (United States)

    Bridges, James E.

    2011-01-01

    A family of high aspect ratio nozzles were designed to provide a parametric database of canonical embedded propulsion concepts. Nozzle throat geometries with aspect ratios of 2:1, 4:1, and 8:1 were chosen, all with convergent nozzle areas. The transition from the typical round duct to the rectangular nozzle was designed very carefully to produce a flow at the nozzle exit that was uniform and free from swirl. Once the basic rectangular nozzles were designed, external features common to embedded propulsion systems were added: extended lower lip (a.k.a. bevel, aft deck), differing sidewalls, and chevrons. For the latter detailed Reynolds-averaged Navier-Stokes (RANS) computational fluid dynamics (CFD) simulations were made to predict the thrust performance and to optimize parameters such as bevel length, and chevron penetration and azimuthal curvature. Seventeen of these nozzles were fabricated at a scale providing a 2.13 inch diameter equivalent area throat." ! The seventeen nozzles were tested for far-field noise and a few data were presented here on the effect of aspect ratio, bevel length, and chevron count and penetration. The sound field of the 2:1 aspect ratio rectangular jet was very nearly axisymmetric, but the 4:1 and 8:1 were not, the noise on their minor axes being louder than the major axes. Adding bevel length increased the noise of these nozzles, especially on their minor axes, both toward the long and short sides of the beveled nozzle. Chevrons were only added to the 2:1 rectangular jet. Adding 4 chevrons per wide side produced some decrease at aft angles, but increased the high frequency noise at right angles to the jet flow. This trend increased with increasing chevron penetration. Doubling the number of chevrons while maintaining their penetration decreased these effects. Empirical models of the parametric effect of these nozzles were constructed and quantify the trends stated above." Because it is the objective of the Supersonics Project that

  9. High Aspect Ratio Semiconductor Heterojunction Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Redwing, Joan [Pennsylvania State Univ., University Park, PA (United States). Dept. of Material Science and Engineering; Mallouk, Tom [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemistry; Mayer, Theresa [Pennsylvania State Univ., University Park, PA (United States). Dept. of Electrical Engineering; Dickey, Elizabeth [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Wronski, Chris [Pennsylvania State Univ., University Park, PA (United States). Dept. of Electrical Engineering

    2013-05-17

    The project focused on the development of high aspect ratio silicon heterojunction (HARSH) solar cells. The solar cells developed in this study consisted of high density vertical arrays of radial junction silicon microwires/pillars formed on Si substrates. Prior studies have demonstrated that vertical Si wire/pillar arrays enable reduced reflectivity and improved light trapping characteristics compared to planar solar cells. In addition, the radial junction structure offers the possibility of increased carrier collection in solar cells fabricated using material with short carrier diffusion lengths. However, the high junction and surface area of radial junction Si wire/pillar array devices can be problematic and lead to increased diode leakage and enhanced surface recombination. This study investigated the use of amorphous hydrogenated Si in the form of a heterojunction-intrinsic-thin layer (HIT) structure as a junction formation method for these devices. The HIT layer structure has widely been employed to reduce surface recombination in planar crystalline Si solar cells. Consequently, it was anticipated that it would also provide significant benefits to the performance of radial junction Si wire/pillar array devices. The overall goals of the project were to demonstrate a HARSH cell with a HIT-type structure in the radial junction Si wire/pillar array configuration and to develop potentially low cost pathways to fabricate these devices. Our studies demonstrated that the HIT structure lead to significant improvements in the open circuit voltage (Voc>0.5) of radial junction Si pillar array devices compared to devices fabricated using junctions formed by thermal diffusion or low pressure chemical vapor deposition (LPCVD). In addition, our work experimentally demonstrated that the radial junction structure lead to improvements in efficiency compared to comparable planar devices for devices fabricated using heavily doped Si that had reduced carrier diffusion

  10. High aspect ratio channels in glass and porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liang, H.D. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Nanoscience and Nanotechnology Initiative (NNI), National University of Singapore, Singapore 117411 (Singapore); Dang, Z.Y. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Wu, J.F. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Kan, J.A. van; Qureshi, S. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Ynsa, M.D.; Torres-Costa, V. [Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Centro de Micro-Análisis de Materiales (CMAM), Universidad Autónoma de Madrid, Campus de Cantoblanco Edif. 22, Faraday 3, E-28049 Madrid (Spain); Maira, A. [Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Venkatesan, T.V. [Nanoscience and Nanotechnology Initiative (NNI), National University of Singapore, Singapore 117411 (Singapore); Breese, M.B.H., E-mail: phymbhb@nus.edu.sg [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore)

    2017-03-01

    We have developed a micromachining process to produce high-aspect-ratio channels and holes in glass and porous silicon. Our process utilizes MeV proton beam irradiation of silicon using direct writing with a focused beam, followed by electrochemical etching. To increase throughput we have also developed another process for large area ion irradiation based on a radiation-resistant gold surface mask, allowing many square inches to be patterned. We present a study of the achievable channel width, depth and period and sidewall verticality for a range of channels which can be over 100 μm deep or 100 nm wide with aspect ratios up to 80. This process overcomes the difficulty of machining glass on a micro- and nanometer scale which has limited many areas of applications in different fields such as microelectronics and microfluidics.

  11. High aspect ratio channels in glass and porous silicon

    Science.gov (United States)

    Liang, H. D.; Dang, Z. Y.; Wu, J. F.; van Kan, J. A.; Qureshi, S.; Ynsa, M. D.; Torres-Costa, V.; Maira, A.; Venkatesan, T. V.; Breese, M. B. H.

    2017-03-01

    We have developed a micromachining process to produce high-aspect-ratio channels and holes in glass and porous silicon. Our process utilizes MeV proton beam irradiation of silicon using direct writing with a focused beam, followed by electrochemical etching. To increase throughput we have also developed another process for large area ion irradiation based on a radiation-resistant gold surface mask, allowing many square inches to be patterned. We present a study of the achievable channel width, depth and period and sidewall verticality for a range of channels which can be over 100 μm deep or 100 nm wide with aspect ratios up to 80. This process overcomes the difficulty of machining glass on a micro- and nanometer scale which has limited many areas of applications in different fields such as microelectronics and microfluidics.

  12. Fabrication of high-aspect ratio SU-8 micropillar arrays

    DEFF Research Database (Denmark)

    Amato, Letizia; Keller, Stephan S.; Heiskanen, Arto

    2012-01-01

    SU-8 is the preferred photoresist for development and fabrication of high aspect ratio (HAR) three dimensional patterns. However, processing of SU-8 is a challenging task, especially when the film thickness as well as the aspect ratio is increasing and the size of the features is close to the res...

  13. Scattering and extinction from high-aspect-ratio trenches

    DEFF Research Database (Denmark)

    Roberts, Alexander Sylvester; Søndergaard, Thomas; Chirumamilla, Manohar;

    2015-01-01

    We construct a semi-analytical model describing the scattering, extinction and absorption properties of a high aspect-ratio trench in a metallic film. We find that these trenches act as highly efficient scatterers of free waves. In the perfect conductor limit, which for many metals is approached...

  14. Injection molding of high aspect ratio sub-100 nm nanostructures

    DEFF Research Database (Denmark)

    Matschuk, Maria; Larsen, Niels B

    2013-01-01

    with FDTS. Reduced adhesion forces are consistent with lowered friction that reduces the risk of fracturing the nanoscopic pillars during demolding. Optimized mold surface chemistry and associated injection molding conditions permitted the fabrication of square arrays of 40 nm wide and 107 nm high (aspect......We have explored the use of mold coatings and optimized processing conditions to injection mold high aspect ratio nanostructures (height-to-width >1) in cyclic olefin copolymer (COC). Optimizing the molding parameters on uncoated nickel molds resulted in slight improvements in replication quality...

  15. Fabrication of high aspect ratio nanocell lattices by ion beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Osamu [School of Environmental Science and Technology, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 (Japan); Nitta, Noriko, E-mail: nitta.noriko@kochi-tech.ac.jp [School of Environmental Science and Technology, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 (Japan); Center for Nanotechnology, Research Institute, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 (Japan); Taniwaki, Masafumi [School of Environmental Science and Technology, Kochi University of Technology, Tosayamada, Kami, Kochi 782-8502 (Japan)

    2016-11-01

    Highlights: • Nanocell lattice with a high aspect ratio on InSb semiconductor surface was fabricated by ion beam irradiation. • The fabrication technique consisting of top-down and bottom-up processes was performed in FIB. • High aspect ratio of 2 was achieved in nanocell lattice with a 100 nm interval. • The intermediate-flux irradiation is favorable for fabrication of nanocell with a high aspect ratio. - Abstract: A high aspect ratio nanocell lattice was fabricated on the InSb semiconductor surface using the migration of point defects induced by ion beam irradiation. The fabrication technique consisting of the top-down (formation of voids and holes) and bottom-up (growth of voids and holes into nanocells) processes was performed using a focused ion beam (FIB) system. A cell aspect ratio of 2 (cell height/cell diameter) was achieved for the nanocell lattice with a 100 nm dot interval The intermediate-flux ion irradiation during the bottom-up process was found to be optimal for the fabrication of a high aspect ratio nanocell.

  16. Aeroelastic stability analysis of high aspect ratio aircraft wings

    OpenAIRE

    Banerjee, J. R.; Liu, X.; Kassem, H. I.

    2014-01-01

    Free vibration and flutter analyses of two types of high aspect ratio aircraft wings are presented. The wing is idealised as an assembly of bending-torsion coupled beams using the dynamic stiffness method leading to a nonlinear eigenvalue problem. This problem is solved using the Wattrick-Williams algorithm yielding natural frequencies and mode shapes. The flutter analysis is carried out using the normal mode method in conjunction with generalised coordinates and two-dimensional unsteady aero...

  17. High aspect ratio 3D nanopatterning using Proton Beam Writing

    Science.gov (United States)

    van Kan, Jeroen A.

    2009-03-01

    Proton beam writing (PBW) is a new direct write lithography using MeV protons, and is unique because of its ability to fabricate 3D structures of high aspect ratio structures directly in resist material like PMMA, SU-8 and HSQ. The introduction by CIBA, Singapore of a dedicated PBW facility, capable of writing at the micro- and nano- scale has facilitated high aspect ratio nanostructuring. PBW has demontrated high aspect ratio walls in HSQ down to the 20nm level. In recent experiments details down to sub 20 nm have been achieved in PMMA. Monte-Carlo calculations have shown that structuring down to the nanometer level is feasible. All this is possible because of the virtual absence of proximity effects (unwanted resist exposure by stray secondary electrons). The design and performance of this unique nanoprobe facility will be discussed. Two potential fields of application (eg nanofluidics and nanowire integration) of PBW will be discussed. Currently nanofluidics devices have typically only one critical dimension below 100 nm. Here we will introduce PBW as a powerful technique to fabricate molds for replication of PDMS nanofluidic circuits down to the sub 100 nm level in two dimensions. Initial chips with dimension down to 150 nm have successfully been used to study DNA folding in quasi-1d nanochannels in tandem with fluorescence imaging. Since the size of these PDMS nanochannels is not limited by the PDMS or PBW further miniaturization down to the sub 100 nm level is a realistic goal and initial results will be discussed. Nanowires are a potential building block for nano-electronic devices, and one critical problem is the integration of nanowires to form contacts. Porous alumina templates and high energy ion-tracks have been used for the production of nanowire templates in a random orientation. Since PBW is the only true 3D direct write nanolithographic technique it can be used to fabricate nanowire templates in a controlled manner.

  18. High aspect ratio transmission line circuits micromachined in silicon

    Science.gov (United States)

    Todd, Shane Truman

    The performance of complimentary metal-oxide-semiconductor (CMOS) monolithic microwave integrated circuits (MMICs) fabricated on silicon has improved dramatically. The scaling down of silicon transistors has increased the maximum frequency of transistors to the point where silicon MMICs have become a viable alternative to compound semiconductor MMICs in certain applications. A fundamental problem still exists in silicon MMICs however in that transmission lines fabricated on silicon can suffer from high loss due to the finite conductivity of the silicon substrate. A novel approach for creating low-loss transmission lines on silicon is presented in this work. Low-loss transmission lines are created on low resistivity silicon by using a micromachining method that combines silicon deep reactive ion etching (DRIE), thermal oxidation, electroplating, and planarization. Two types of high aspect ratio transmission lines are created with this method including high aspect ratio coplanar waveguide (hicoplanar) and semi-rectangular coaxial (semicoaxial). Transmission lines with impedances ranging from 20--80 O have been fabricated with minimum measured loss lower than 1 dB/cm at 67 GHz. Low-loss dielectrics are created for the high aspect ratio transmission lines using the mesa merging method. The mesa merging method works by creating silicon mesa arrays using DRIE and then converting and merging the mesa arrays into a solid oxide dielectric using thermal oxidation. The transmission lines are designed so that the fields penetrate the low-loss oxide dielectric and are isolated from the lossy silicon substrate. The mesa merging method has successfully created large volume oxide with depth up to 65 microm and width up to 240 microm in short oxidation times. Other advantages of the high aspect ratio transmission lines are demonstrated including low-loss over a wide impedance range, high isolation, and high coupling for coupled-line circuits. Transmission line models have been

  19. Anomalous dynamic behaviour of optically trapped high aspect ratio nanowires

    CERN Document Server

    Toe, Wen Jun; Angstmann, Christopher; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati; Henry, Bruce; Reece, Peter J

    2015-01-01

    We investigate the dynamics of high aspect ratio nanowires trapped axially in a single gradient force optical tweezers. A power spectrum analysis of the Brownian dynamics reveals a broad spectral resonance of the order of a kHz with peak properties that are strongly dependent on the input trapping power. Modelling of the dynamical equations of motion of the trapped nanowire that incorporate non-conservative effects through asymmetric coupling between translational and rotational degrees of freedom provides excellent agreement with the experimental observations. An associated observation of persistent cyclical motion around the equilibrium trapping position using winding analysis provides further evidence for the influence of non-conservative forces.

  20. High Aspect-Ratio Neural Probes using Conventional Blade Dicing

    Science.gov (United States)

    Goncalves, S. B.; Ribeiro, J. F.; Silva, A. F.; Correia, J. H.

    2016-10-01

    Exploring deep neural circuits has triggered the development of long penetrating neural probes. Moreover, driven by brain displacement, the long neural probes require also a high aspect-ratio shafts design. In this paper, a simple and reproducible method of manufacturing long-shafts neural probes using blade dicing technology is presented. Results shows shafts up to 8 mm long and 200 µm wide, features competitive to the current state-of-art, being its outline simply accomplished by a single blade dicing program. Therefore, conventional blade dicing presents itself as a viable option to manufacture long neural probes.

  1. High-aspect ratio magnetic nanocomposite polymer cilium

    Science.gov (United States)

    Rahbar, M.; Tseng, H. Y.; Gray, B. L.

    2014-03-01

    This paper presents a new fabrication technique to achieve ultra high-aspect ratio artificial cilia micro-patterned from flexible highly magnetic rare earth nanoparticle-doped polymers. We have developed a simple, inexpensive and scalable fabrication method to create cilia structures that can be actuated by miniature electromagnets, that are suitable to be used for lab-on-a chip (LOC) and micro-total-analysis-system (μ-TAS) applications such as mixers and flow-control elements. The magnetic cilia are fabricated and magnetically polarized directly in microfluidic channels or reaction chambers, allowing for easy integration with complex microfluidic systems. These cilia structures can be combined on a single chip with other microfluidic components employing the same permanently magnetic nano-composite polymer (MNCP), such as valves or pumps. Rare earth permanent magnetic powder, (Nd0.7Ce0.3)10.5Fe83.9B5.6, is used to dope polydimethylsiloxane (PDMS), resulting in a highly flexible M-NCP of much higher magnetization and remanence [1] than ferromagnetic polymers typically employed in magnetic microfluidics. Sacrificial poly(ethylene-glycol) (PEG) is used to mold the highly magnetic polymer into ultra high-aspect ratio artificial cilia. Cilia structures with aspect ratio exceeding 8:0.13 can be easily fabricated using this technique and are actuated using miniature electromagnets to achieve a high range of motion/vibration.

  2. Formation of High Aspect Ratio Microcoil Using Dipping Method

    Science.gov (United States)

    Noda, Daiji; Yamashita, Shuhei; Matsumoto, Yoshifumi; Setomoto, Masaru; Hattori, Tadashi

    Coils are used in many electronic devices as inductors in mobile units such as mobile phone, digital cameras, etc. Inductance and quality factor of coils are very important value of the performance. Therefore, the requests for coils are small size, high inductance, low power consumption, etc. However, coils are unsuitable for miniaturization because of its structure. Therefore, we have proposed and developed the microcoils of high aspect ratio with the dipping method and an X-ray lithography technique. In dipping method, centrifugal force and highly viscous photoresist solution were key points to evenly apply resist in the form of thick film on metal bar. The film thickness of resist on bar was achieved about 50 μm after single coating. Using these techniques, we succeeded in creating threaded groove structure with 10 μm lines and spaces on 1 mm brass bar. In this case, the aspect ratio was achieved five. It is very expected the high performance microcoil with high aspect ratio lines could be manufactured in spite of the miniature size.

  3. Improving acousto-optical interaction by high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    In recent years experiments have shown that optical waves in waveguides can be modulated by mechanical stresses from surface acoustic waves (SAW), which have most of their energy density concentrated at the surface. In these experiments the SAWs are generated in piezoelectric materials...... by conventional interdigital transducers consisting of thin electrodes deposited at the surface. In this work the finite element method is employed to investigate if the acousto-optical interaction can be enhanced by generating the SAWs by interdigital transducers consisting of high aspect ratio electrodes....... With a periodic model it is first shown that these tall electrodes introduce several new confined SAW modes with slow phase velocities because of mechanical energy storage in the electrodes. The periodic model is then extended to a finite model by using perfectly matched layers at the substrate borders...

  4. Dielectric spectroscopy of high aspect ratio graphene-polyurethane nanocomposites

    Science.gov (United States)

    Jan, Rahim; Habib, Amir; Abbassi, Hina; Amir, Shahid

    2015-03-01

    High aspect ratio graphene nanosheets (GNS), prepared via liquid exfoliation, are homogeneously dispersed in thermoplastic polyurethane (TPU). Dielectric spectroscopy results are reported for these nanocomposites (up to 0.55 vol. % GNS) in the frequency range of 100 Hz to 5 MHz. The as-prepared GNS increased the AC conductivity 10-1000 times across the given frequency range. The dielectric constant is increased 5-6 times at 100 Hz for the maximum loading of GNS when compared with the pristine TPU, with subsequently high dielectric loss making them a suitable candidate for high energy dissipation applications such as EMI shielding. The temperature effects on the dielectric characteristics of 0.55 vol. % GNS/TPU nanocomposites beyond 400 K are more pronounced due to the interfacial and orientation polarization. Mechanical characteristics evaluation of GNS/TPU composites shows a marked increase in the ultimate tensile strength without compromising their ductility and stiffness. [Figure not available: see fulltext.

  5. Large eddy simulation of a high aspect ratio combustor

    Science.gov (United States)

    Kirtas, Mehmet

    The present research investigates the details of mixture preparation and combustion in a two-stroke, small-scale research engine with a numerical methodology based on large eddy simulation (LES) technique. A major motivation to study such small-scale engines is their potential use in applications requiring portable power sources with high power density. The investigated research engine has a rectangular planform with a thickness very close to quenching limits of typical hydrocarbon fuels. As such, the combustor has a high aspect ratio (defined as the ratio of surface area to volume) that makes it different than the conventional engines which typically have small aspect ratios to avoid intense heat losses from the combustor in the bulk flame propagation period. In most other aspects, this engine involves all the main characteristics of traditional reciprocating engines. A previous experimental work has identified some major design problems and demonstrated the feasibility of cyclic combustion in the high aspect ratio combustor. Because of the difficulty of carrying out experimental studies in such small devices, resolving all flow structures and completely characterizing the flame propagation have been an enormously challenging task. The numerical methodology developed in this work attempts to complement these previous studies by providing a complete evolution of flow variables. Results of the present study demonstrated strengths of the proposed methodology in revealing physical processes occuring in a typical operation of the high aspect ratio combustor. For example, in the scavenging phase, the dominant flow structure is a tumble vortex that forms due to the high velocity reactant jet (premixed) interacting with the walls of the combustor. Since the scavenging phase is a long process (about three quarters of the whole cycle), the impact of the vortex is substantial on mixture preparation for the next combustion phase. LES gives the complete evolution of this flow

  6. Measurement and simulation of jet mass caused by a high-aspect ratio pertubation

    Energy Technology Data Exchange (ETDEWEB)

    Keiter, Paul A [Los Alamos National Laboratory; Cooley, James [Los Alamos National Laboratory; Kyrala, George [Los Alamos National Laboratory; Wilson, Doug [Los Alamos National Laboratory; Blue, Brent [LLNL/GA; Elliott, Jim [LLNL; Edwards, John [LLNL; Robey, Harry [LLNL; Spears, Brian [LLNL

    2009-01-01

    Inertial confinement fusion (ICF) capsule performance can be negatively impacted by the presence of hydrodynamic instabilities. To perform a gas fill on an ICF capsule current plans involve drilling a small hole and inserting a fill tube to inject the gas mixture into the capsule. This introduces a perturbation on the capsule, which can seed hydrodynamic instabilities. The small hole can cause jetting of the shell material into the gas, which might adversely affect the capsule performance. We have performed simulations and experiments to study the hydrodynamic evolution of jets from high-aspect ratio holes, such as the fill tube hole. Although simulations using cold materials over predict the amount of mass in the jet, when a reasonable amount of preheat (< 1 eV) is introduced, the simulations are in better agreement with the experiment.

  7. Wet Etched High Aspect Ratio Microstructures on Quartz for MEMS Applications

    Science.gov (United States)

    Liang, Jinxing; Kohsaka, Fusao; Matsuo, Takahiro; Ueda, Toshitsugu

    Z cut α-quartz wafers were etched in saturated ammonium bifluoride solution at 87 degrees C. The side wall profiles were observed using the scanning electron microscopy (SEM) and plotted dependent on the polar direction. This research focused on investigating high aspect ratio trench and through-hole, which were dependent on the polar direction to the crystal axis. Aspect ratio in dependence on polar direction was also plotted and microchannels with aspect ratio > 3 could be achieved at the polar angle between 30° to 60°. The possibility of application for microcapillary was discussed, and the trench at 45° was considered best. Double-sided etching technique was used for manufacturing through-hole structures. Through-hole at 0° was demonstrated effective for fabrication of capacitive MEMS tilt sensor. Through-holes at 15° and 105° were proposed for fabrication of 90°-arranged two axis capactive tilt sensor, taking advantage of the twofold symmetry property around X axis and threefold symmetry property around Z axis.

  8. Rapid homogeneous endothelialization of high aspect ratio microvascular networks.

    Science.gov (United States)

    Naik, Nisarga; Hanjaya-Putra, Donny; Haller, Carolyn A; Allen, Mark G; Chaikof, Elliot L

    2015-08-01

    Microvascularization of an engineered tissue construct is necessary to ensure the nourishment and viability of the hosted cells. Microvascular constructs can be created by seeding the luminal surfaces of microfluidic channel arrays with endothelial cells. However, in a conventional flow-based system, the uniformity of endothelialization of such an engineered microvascular network is constrained by mass transfer of the cells through high length-to-diameter (L/D) aspect ratio microchannels. Moreover, given the inherent limitations of the initial seeding process to generate a uniform cell coating, the large surface-area-to-volume ratio of microfluidic systems demands long culture periods for the formation of confluent cellular microconduits. In this report, we describe the design of polydimethylsiloxane (PDMS) and poly(glycerol sebacate) (PGS) microvascular constructs with reentrant microchannels that facilitates rapid, spatially homogeneous endothelial cell seeding of a high L/D (2 cm/35 μm; > 550:1) aspect ratio microchannels. MEMS technology was employed for the fabrication of a monolithic, elastomeric, reentrant microvascular construct. Isotropic etching and PDMS micromolding yielded a near-cylindrical microvascular channel array. A 'stretch - seed - seal' operation was implemented for uniform incorporation of endothelial cells along the entire microvascular area of the construct yielding endothelialized microvascular networks in less than 24 h. The feasibility of this endothelialization strategy and the uniformity of cellularization were established using confocal microscope imaging.

  9. Shape matters: synthesis and biomedical applications of high aspect ratio magnetic nanomaterials

    OpenAIRE

    Raluca M Fratila; Rivera-Fernández, Sara; Fuente, Jesús M. de la

    2015-01-01

    High aspect ratio magnetic nanomaterials possess anisotropic properties that make them attractive for biological applications. Their elongated shape enables multivalent interactions with receptors through the introduction of multiple targeting units on their surface, thus enhancing cell internalization. Moreover, due to their magnetic anisotropy, high aspect ratio nanomaterials can outperform their spherical analogues as contrast agents for magnetic resonance imaging (MRI) applications. In th...

  10. Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions

    NARCIS (Netherlands)

    Ende, D.A. van den; Kempen, S.E. van; Wu, X.; Groen, W.A.; Randall, C.A.; Zwaag, S. van der

    2012-01-01

    Piezoelectric composites were prepared by dielectrophoretic alignment of high aspect ratio piezoelectric particles in a thermosetting polymer matrix. A high level of alignment was achieved in the cured composite from a resin containing randomly oriented high aspect ratio particles. Upon application

  11. Hot punching of high-aspect-ratio 3D polymeric microstructures for drug delivery

    DEFF Research Database (Denmark)

    Petersen, Ritika Singh; Keller, Stephan Sylvest; Boisen, Anja

    2015-01-01

    Hot punching: a highly versatile method of fabricating high-aspect-ratio 3D microstructures for drug delivery with good replication fidelity and yield.......Hot punching: a highly versatile method of fabricating high-aspect-ratio 3D microstructures for drug delivery with good replication fidelity and yield....

  12. Photoimageable Polyimide: A Dielectric Material For High Aspect Ratio Structures

    Science.gov (United States)

    Cech, Jay M.; Oprysko, Modest M.; Young, Peter L.; Li, Kin

    1986-07-01

    Polyimide has been identified as a useful material for microelectronic packaging because of its low dielectric constant and high temperature stability. Difficulties involved with reactive ion etching (RIE), a conventional technique for patterning thick polyimide films (thickness greater than 5 microns) with vertical walls, can be overcome by using photimageable polyimide precursors. The processing steps are similar to those used with negative photoresists. EM Chemical's HTR-3 photosensitive polyimide has been spun on up to a thickness of 12 microns. Exposure with a dose of 780 mJcm-2 of ultraviolet light, followed by spin development produces clean patterns as small as 5 microns corresponding to an aspect ratio of 2.4. When the patterned precursor is heated, an imidization reaction occurs converting the patterned film to polyimide. Baking to ca. 400 degrees C results in substantial loss in the thickness and in line width. However, shrinkage occurs reproducibly so useful rules for mask design can be formulated. Near vertical wall structures can be fabricated by taking advantage of the optical and shrinkage properties of the polyimide precursor. After development, an undercut wall profile can be produced since the bottom of the film receives less exposure and is hence more soluble in the developer. During heating, lateral shrinkage pulls the top of the film inward producing a vertical wall since the bottom is fixed to the substrate by adhesion. As a result, fully cured polyimide structures with straight walls and aspect ratios greater than one can be obtained. Dielectric properties of the fully imidized films were investigated with capacitor test structures. A relative dielectric constant of 3.3 and a loss tangent of .002 were measured at 20 kHz. It was also found that the dielectric constant increases as a linear function of relative humidity.

  13. Noise Measurements of High Aspect Ratio Distributed Exhaust Systems

    Science.gov (United States)

    Bridges, James E.

    2015-01-01

    This paper covers far-field acoustic measurements of a family of rectangular nozzles with aspect ratio 8, in the high subsonic flow regime. Several variations of nozzle geometry, commonly found in embedded exhaust systems, are explored, including bevels, slants, single broad chevrons and notches, and internal septae. Far-field acoustic results, presented previously for the simple rectangular nozzle, showed that increasing aspect ratio increases the high frequency noise, especially directed in the plane containing the minor axis of the nozzle. Detailed changes to the nozzle geometry generally made little difference in the noise, and the differences were greatest at low speed. Having an extended lip on one broad side (bevel) did produce up to 3 decibels more noise in all directions, while extending the lip on the narrow side (slant) produced up to 2 decibels more noise, primarily on the side with the extension. Adding a single, non-intrusive chevron, made no significant change to the noise, while inverting the chevron (notch) produced up to 2decibels increase in the noise. Having internal walls (septae) within the nozzle, such as would be required for structural support or when multiple fan ducts are aggregated, reduced the noise of the rectangular jet, but could produce a highly directional shedding tone from the septae trailing edges. Finally, a nozzle with both septae and a beveled nozzle, representative of the exhaust system envisioned for a distributed electric propulsion aircraft with a common rectangular duct, produced almost as much noise as the beveled nozzle, with the septae not contributing much reduction in noise.

  14. Ultra-high aspect ratio replaceable AFM tips using deformation-suppressed focused ion beam milling

    DEFF Research Database (Denmark)

    Savenko, Alexey; Yildiz, Izzet; Petersen, Dirch Hjorth;

    2013-01-01

    Fabrication of ultra-high aspect ratio exchangeable and customizable tips for atomic force microscopy (AFM) using lateral focused ion beam (FIB) milling is presented. While on-axis FIB milling does allow high aspect ratio (HAR) AFM tips to be defined, lateral milling gives far better flexibility...... FIB milling strategies for obtaining sharper tips are discussed. Finally, assembly of the HAR tips on a custom-designed probe as well as the first AFM scanning is shown....

  15. Synthesis of high aspect ratio ZnO nanowires with an inexpensive handcrafted electrochemical setup

    Science.gov (United States)

    Taheri, Ali; Saramad, Shahyar; Setayeshi, Saeed

    2016-12-01

    In this work, high aspect ratio zinc oxide nanowires are synthesized using templated one-step electrodeposition technique. Electrodeposition of the nanowires is done using a handcrafted electronic system. Nuclear track-etched polycarbonate membrane is used as a template to form the high aspect ratio nanowires. The result of X-ray diffraction and scanning electron microscopy shows that nanowires with a good crystallinity and an aspect ratio of more than 30 can be achieved in a suitable condition. The height of electrodeposited nanowires reaches to about 11 μm. Based on the obtained results, high aspect ratio ZnO nanowires can be formed using inexpensive electrodeposition setup with an acceptable quality.

  16. Etching high aspect ratio structures in silicon using sulfur hexafluoride/oxygen plasma

    Science.gov (United States)

    Belen, Rodolfo Jun

    Plasma etching of high aspect ratio structures in Si is an important step in manufacturing capacitors for memory devices and integrated components of microelectromechanical systems. In these applications, the goal is to etch deep features anisotropically with high etch rates and selectivities to the mask while maintaining good uniformity and reproducibility. This study investigates the etching of deep sub-half-micron diameter holes in Si using SF6/O 2 plasma. Etching experiments and plasma diagnostics are combined with modeling to gain a fundamental understanding of the etching and passivation kinetics and mechanism necessary in developing and scaling-up processes. Etching experiments are conducted in an inductively coupled plasma reactor with a planar coil. The substrate electrode is biased with a separate rf power supply to achieve independent control of the ion flux and energy. The effects of pressure, rf-bias and SF6-to-O2 ratio in the feed gas on the etch rate, selectivity and feature profile shape are studied using Si wafers patterned with 0.35 mum-diameter holes in a SiO2 mask. Visualization of profiles using scanning electron microscopy is complemented by plasma diagnostics such as mass spectrometry and actinometry. Simultaneous with experiments, reactor-scale and feature-scale models are developed to quantify the etching and passivation kinetics and identify the important kinetic parameters that affect feature profile evolution. Information from plasma diagnostics and previously published data are used to reduce the degrees of freedom in the model. Experiments are designed to directly measure kinetic parameters such as the chemical etch rate constant and the incidence angle dependence of the etching yield. Experimentally inaccessible parameters such as the sticking coefficients, etching yield and ion scattering parameters are determined through feature profile simulation. The key internal plasma parameters that affect profile evolution are the F-to-O and F

  17. Shape matters: synthesis and biomedical applications of high aspect ratio magnetic nanomaterials.

    Science.gov (United States)

    Fratila, Raluca M; Rivera-Fernández, Sara; de la Fuente, Jesús M

    2015-05-14

    High aspect ratio magnetic nanomaterials possess anisotropic properties that make them attractive for biological applications. Their elongated shape enables multivalent interactions with receptors through the introduction of multiple targeting units on their surface, thus enhancing cell internalization. Moreover, due to their magnetic anisotropy, high aspect ratio nanomaterials can outperform their spherical analogues as contrast agents for magnetic resonance imaging (MRI) applications. In this review, we first describe the two main synthetic routes for the preparation of anisotropic magnetic nanomaterials: (i) direct synthesis (in which the anisotropic growth is directed by tuning the reaction conditions or by using templates) and (ii) assembly methods (in which the high aspect ratio is achieved by assembly from individual building blocks). We then provide an overview of the biomedical applications of anisotropic magnetic nanomaterials: magnetic separation and detection, targeted delivery and magnetic resonance imaging.

  18. Development of high-aspect-ratio microchannel heat exchanger based on multi-tool milling process

    Institute of Scientific and Technical Information of China (English)

    潘敏强; 李金恒; 汤勇

    2008-01-01

    A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.

  19. Shape matters: synthesis and biomedical applications of high aspect ratio magnetic nanomaterials

    Science.gov (United States)

    Fratila, Raluca M.; Rivera-Fernández, Sara; de La Fuente, Jesús M.

    2015-04-01

    High aspect ratio magnetic nanomaterials possess anisotropic properties that make them attractive for biological applications. Their elongated shape enables multivalent interactions with receptors through the introduction of multiple targeting units on their surface, thus enhancing cell internalization. Moreover, due to their magnetic anisotropy, high aspect ratio nanomaterials can outperform their spherical analogues as contrast agents for magnetic resonance imaging (MRI) applications. In this review, we first describe the two main synthetic routes for the preparation of anisotropic magnetic nanomaterials: (i) direct synthesis (in which the anisotropic growth is directed by tuning the reaction conditions or by using templates) and (ii) assembly methods (in which the high aspect ratio is achieved by assembly from individual building blocks). We then provide an overview of the biomedical applications of anisotropic magnetic nanomaterials: magnetic separation and detection, targeted delivery and magnetic resonance imaging.

  20. Fabrication of high aspect ratio nanogrid transparent electrodes via capillary assembly of Ag nanoparticles

    Science.gov (United States)

    Kang, Juhoon; Park, Chang-Goo; Lee, Su-Han; Cho, Changsoon; Choi, Dae-Geun; Lee, Jung-Yong

    2016-05-01

    In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%.In this report, we describe the fabrication of periodic Ag nanogrid electrodes by capillary assembly of silver nanoparticles (AgNPs) along patterned nanogrid templates. By assembling the AgNPs into these high-aspect-ratio nanogrid patterns, we can obtain high-aspect-ratio nanogratings, which can overcome the inherent trade-off between the optical transmittance and the sheet resistance of transparent electrodes. The junction resistance between the AgNPs is effectively reduced by photochemical welding and post-annealing. The fabricated high-aspect-ratio nanogrid structure with a line width of 150 nm and a height of 450 nm has a sheet resistance of 15.2 Ω sq-1 and an optical transmittance of 85.4%. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01896c

  1. Physical Delivery of Macromolecules using High-Aspect Ratio Nanostructured Materials.

    Science.gov (United States)

    Lee, Kunwoo; Lingampalli, Nithya; Pisano, Albert P; Murthy, Niren; So, Hongyun

    2015-10-28

    There is great need for the development of an efficient delivery method of macromolecules, including nucleic acids, proteins, and peptides, to cell cytoplasm without eliciting toxicity or changing cell behavior. High-aspect ratio nanomaterials have addressed many challenges present in conventional methods, such as cell membrane passage and endosomal degradation, and have shown the feasibility of efficient high-throughput macromolecule delivery with minimal perturbation of cells. This review describes the recent advances of in vitro and in vivo physical macromolecule delivery with high-aspect ratio nanostructured materials and summarizes the synthesis methods, material properties, relevant applications, and various potential directions.

  2. Framework to model neutral particle flux in convex high aspect ratio structures using one-dimensional radiosity

    Science.gov (United States)

    Manstetten, Paul; Filipovic, Lado; Hössinger, Andreas; Weinbub, Josef; Selberherr, Siegfried

    2017-02-01

    We present a computationally efficient framework to compute the neutral flux in high aspect ratio structures during three-dimensional plasma etching simulations. The framework is based on a one-dimensional radiosity approach and is applicable to simulations of convex rotationally symmetric holes and convex symmetric trenches with a constant cross-section. The framework is intended to replace the full three-dimensional simulation step required to calculate the neutral flux during plasma etching simulations. Especially for high aspect ratio structures, the computational effort, required to perform the full three-dimensional simulation of the neutral flux at the desired spatial resolution, conflicts with practical simulation time constraints. Our results are in agreement with those obtained by three-dimensional Monte Carlo based ray tracing simulations for various aspect ratios and convex geometries. With this framework we present a comprehensive analysis of the influence of the geometrical properties of high aspect ratio structures as well as of the particle sticking probability on the neutral particle flux.

  3. Thermo-mechanical properties of high aspect ratio silica nanofiber filled epoxy composites

    Science.gov (United States)

    Ren, Liyun

    The optimization of thermo-mechanical properties of polymer composites at low filler loadings is of great interest in both engineering and scientific fields. There have been several studies on high aspect ratio fillers as novel reinforcement phase for polymeric materials. However, facile synthesis method of high aspect ratio nanofillers is limited. In this study, a scalable synthesis method of high aspect ratio silica nanofibers is going to be presented. I will also demonstrate that the inclusion of high aspect ratio silica nanofibers in epoxy results in a significant improvement of epoxy thermo-mechanical properties at low filler loadings. With silica nanofiber concentration of 2.8% by volume, the Young's modulus, ultimate tensile strength and fracture toughness of epoxy increased ~23, ~28 and ~50%, respectively, compared to unfilled epoxy. At silica nanofiber volume concentration of 8.77%, the thermal expansion coefficient decreased by ˜40% and the thermal conductivity was improved by ˜95% at room temperature. In the current study, the influence of nano-sized silica filler aspect ratio on mechanical and thermal behavior of epoxy nanocomposites were studied by comparing silica nanofibers to spherical silica nanoparticles (with aspect ratio of one) at various filler loadings. The significant reinforcement of composite stiffness is attributed to the variation of the local stress state in epoxy due to the high aspect ratio of the silica nanofiber and the introduction of a tremendous amount of interfacial area between the nanofillers and the epoxy matrix. The fracture mechanisms of silica nanofiber filled epoxy were also investigated. The existence of high aspect ratio silica nanofiber promotes fracture energy dissipation by crack deflection, crack pinning as well as debonding with fiber pull-out leading to enhanced fracture toughness. High aspect ratio fillers also provide significant reduction of photon scattering due to formation of a continuous fiber network

  4. Modeling and characterization of dielectrophoretically structured piezoelectric composites using piezoceramic particle inclusions with high aspect ratios

    NARCIS (Netherlands)

    Ende, D.A. van den; Maier, R.A.; Neer, P.L.M.J. van; Zwaag, S. van der; Randall, C.A.; Groen, W.A.

    2013-01-01

    In this work, the piezoelectric properties at high electric fields of dielectrophoretically aligned PZT - polymer composites containing high aspect ratio particles (such as short fibers) are presented. Polarization and strain as a function of electric field are evaluated. The properties of the compo

  5. Improving surface acousto-optical interaction by high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes that are stro...

  6. Dense high-aspect ratio 3D carbon pillars on interdigitated microelectrode arrays

    DEFF Research Database (Denmark)

    Amato, Letizia; Heiskanen, Arto; Hansen, Rasmus

    2015-01-01

    In this work we present high-aspect ratio carbon pillars (1.4 μm in diameter and ∼11 μm in height) on top of interdigitated electrode arrays to be used for electrochemical applications. For this purpose, different types of 2D and 3D pyrolysed carbon structures were fabricated and characterised...

  7. A 3-dimensional in vitro model of epithelioid granulomas induced by high aspect ratio nanomaterials

    Directory of Open Access Journals (Sweden)

    Hurt Robert H

    2011-05-01

    Full Text Available Abstract Background The most common causes of granulomatous inflammation are persistent pathogens and poorly-degradable irritating materials. A characteristic pathological reaction to intratracheal instillation, pharyngeal aspiration, or inhalation of carbon nanotubes is formation of epithelioid granulomas accompanied by interstitial fibrosis in the lungs. In the mesothelium, a similar response is induced by high aspect ratio nanomaterials, including asbestos fibers, following intraperitoneal injection. This asbestos-like behaviour of some engineered nanomaterials is a concern for their potential adverse health effects in the lungs and mesothelium. We hypothesize that high aspect ratio nanomaterials will induce epithelioid granulomas in nonadherent macrophages in 3D cultures. Results Carbon black particles (Printex 90 and crocidolite asbestos fibers were used as well-characterized reference materials and compared with three commercial samples of multiwalled carbon nanotubes (MWCNTs. Doses were identified in 2D and 3D cultures in order to minimize acute toxicity and to reflect realistic occupational exposures in humans and in previous inhalation studies in rodents. Under serum-free conditions, exposure of nonadherent primary murine bone marrow-derived macrophages to 0.5 μg/ml (0.38 μg/cm2 of crocidolite asbestos fibers or MWCNTs, but not carbon black, induced macrophage differentiation into epithelioid cells and formation of stable aggregates with the characteristic morphology of granulomas. Formation of multinucleated giant cells was also induced by asbestos fibers or MWCNTs in this 3D in vitro model. After 7-14 days, macrophages exposed to high aspect ratio nanomaterials co-expressed proinflammatory (M1 as well as profibrotic (M2 phenotypic markers. Conclusions Induction of epithelioid granulomas appears to correlate with high aspect ratio and complex 3D structure of carbon nanotubes, not with their iron content or surface area. This model

  8. Flow visualization study in high aspect ratio cooling channels for rocket engines

    Science.gov (United States)

    Meyer, Michael L.; Giuliani, James E.

    1993-11-01

    The structural integrity of high pressure liquid propellant rocket engine thrust chambers is typically maintained through regenerative cooling. The coolant flows through passages formed either by constructing the chamber liner from tubes or by milling channels in a solid liner. Recently, Carlile and Quentmeyer showed life extending advantages (by lowering hot gas wall temperatures) of milling channels with larger height to width aspect ratios (AR is greater than 4) than the traditional, approximately square cross section, passages. Further, the total coolant pressure drop in the thrust chamber could also be reduced, resulting in lower turbomachinery power requirements. High aspect ratio cooling channels could offer many benefits to designers developing new high performance engines, such as the European Vulcain engine (which uses an aspect ratio up to 9). With platelet manufacturing technology, channel aspect ratios up to 15 could be formed offering potentially greater benefits. Some issues still exist with the high aspect ratio coolant channels. In a coolant passage of circular or square cross section, strong secondary vortices develop as the fluid passes through the curved throat region. These vortices mix the fluid and bring lower temperature coolant to the hot wall. Typically, the circulation enhances the heat transfer at the hot gas wall by about 40 percent over a straight channel. The effect that increasing channel aspect ratio has on the curvature heat transfer enhancement has not been sufficiently studied. If the increase in aspect ratio degrades the secondary flow, the fluid mixing will be reduced. Analysis has shown that reduced coolant mixing will result in significantly higher wall temperatures, due to thermal stratification in the coolant, thus decreasing the benefits of the high aspect ratio geometry. A better understanding of the fundamental flow phenomena in high aspect ratio channels with curvature is needed to fully evaluate the benefits of this

  9. Growth of high aspect ratio ZnO nanorods by solution process: Effect of polyethyleneimine

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Han-Seok; Vaseem, Mohammad; Kim, Sang Gon; Im, Yeon-Ho [School of Semiconductor and Chemical Engineering, Dept. of BIN Fusion Technology, BK 21 Centre for Future Energy Materials and Devices, and Nanomaterials Processing Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Hahn, Yoon-Bong, E-mail: ybhahn@chonbuk.ac.kr [School of Semiconductor and Chemical Engineering, Dept. of BIN Fusion Technology, BK 21 Centre for Future Energy Materials and Devices, and Nanomaterials Processing Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

    2012-05-15

    High aspect ratio ZnO nanorods were grown vertically on ZnO seed layer deposited silicon, glass and polyimide substrates by a solution process at low-temperature using zinc nitrate hexahydrate and hexamethylenetetramine. We studied the effect of polyethlyeneimine (PEI) on the growth of ZnO nanorods. It was found that PEI has a prominent effect on controlling the aspect ratio of ZnO nanorods in solution. The morphological and photoluminescence properties of the ZnO nanorods were also examined with varying the growth temperature (60-90 Degree-Sign C). - Graphical abstract: With addition of polyehyleneimine (PEI) high aspect-ratio ZnO nanorods were grown. It is believed that during ZnO nanorods growth, protonized form of linear PEI molecules inhibits the lateral growth by being adsorbed on non-polar lateral planes. Thus the vertical growth is favored. Highlights: Black-Right-Pointing-Pointer A controlled growth of high aspect ratio ZnO nanorods on different substrates. Black-Right-Pointing-Pointer A prominent effect of polyethlyeneimine (PEI) on controlling the aspect ratio of ZnO nanorods in solution. Black-Right-Pointing-Pointer Precursor concentration and growth temperature effect for various aspect ratio ZnO nanorods.

  10. Different methods to alter surface morphology of high aspect ratio structures

    Energy Technology Data Exchange (ETDEWEB)

    Leber, M., E-mail: moritz.leber@utah.edu [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Shandhi, M.M.H. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Hogan, A. [Blackrock Microsystems, Salt Lake City, UT (United States); Solzbacher, F. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Bhandari, R.; Negi, S. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT (United States); Blackrock Microsystems, Salt Lake City, UT (United States)

    2016-03-01

    Graphical abstract: Surface engineering of high aspect ratio silicon structures. - Highlights: • Multiple roughening techniques for high aspect ratio devices were investigated. • Modification of surface morphology of high aspect ratio silicon devices (1:15). • Decrease of 76% in impedance proves significant increase in surface area. - Abstract: In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode's coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several

  11. Single-pulse femtosecond laser Bessel beams drilling of high-aspect-ratio microholes based on electron dynamics control

    Science.gov (United States)

    Zhao, Weiwei; Li, Xiaowei; Xia, Bo; Yan, Xueliang; Han, Weina; Lu, Yongfeng; Jiang, Lan

    2014-11-01

    Microholes drilling has attracted extensive research efforts for its broad applications in photonics, microfluidics, optical fibers and many other fields. A femtosecond (fs) laser is a promising tool for high-precision materials processing with reduced recast/microcracks and minimized heat affected zones. But there remain many challenges in hole drilling using conventional fs laser with Gaussian beams, such as low aspect ratio and taper effects. We report small-diameter and high-aspect-ratio microholes with taper free drilling in PMMA (polymethyl methacrylate) using single-pulse fs laser Bessel beams. Axicon is used to transform Gaussian beams into Bessel beams, which then irradiate in the sample by a telescope consisting of plano-convex lens and microscope objective. Using this technique, we enhance the aspect ratio of microholes by 55 times as compared with Gaussian beams. We attribute this high aspect ratio and high quality microholes formation to the unique spatial intensity distribution and propagation stability of Bessel beams, which can effectively adjust the transient localized electron density distribution leading to a long and uniform localized-interacted zone. By using the optimized pulse energy and focal depth position, the microholes diameter ranges between 1.4-2.1 μm and the aspect ratio can exceed 460. This efficient technique is of great potentials for fabrication of microphotonics devices and microfluidics.

  12. A review on non-linear aeroelasticity of high aspect-ratio wings

    Science.gov (United States)

    Afonso, Frederico; Vale, José; Oliveira, Éder; Lau, Fernando; Suleman, Afzal

    2017-02-01

    Current economic constraints and environmental regulations call for design of more efficient aircraft configurations. An observed trend in aircraft design to reduce the lift induced drag and improve fuel consumption and emissions is to increase the wing aspect-ratio. However, a slender wing is more flexible and subject to higher deflections under the same operating conditions. This effect may lead to changes in dynamic behaviour and in aeroelastic response, potentially resulting in instabilities. Therefore, it is important to take into account geometric non-linearities in the design of high aspect-ratio wings, as well as having accurate computational codes that couple the aerodynamic and structural models in the presence of non-linearities. Here, a review on the state-of-the-art on non-linear aeroelasticity of high aspect-ratio wings is presented. The methodologies employed to analyse high aspect-ratio wings are presented and their applications discussed. Important observations from the state-of-the-art studies are drawn and the current challenges in the field are identified.

  13. An implicit wetting and drying approach for non-hydrostatic flows in high aspect ratio domains

    CERN Document Server

    Candy, Adam S

    2013-01-01

    A wetting and drying approach for free surface flows governed by the three-dimensional, non-hydrostatic Navier-Stokes equations in high aspect ratio domains is developed. This has application in the modelling of inundation processes in geophysical domains, where dynamics takes place over a large horizontal extent relative to vertical resolution, such as in the evolution of a tsunami, or an urban fluvial flooding scenario. The approach is novel in that it solves for three dimensional dynamics in these very high aspect ratio domains, to include non-hydrostatic effects and accurately model dispersive processes. These become important in shallow regions with steep gradients, a particularly acute problem where man-made structures exist such as buildings or flood defences in an urban environment. It is implicit in time to allow efficient time integration over a range of mesh element sizes. Specific regularisation methods are introduced to improve conditioning of the full three-dimensional pressure Poisson problem i...

  14. Light emitting diode with high aspect ratio submicron roughness for light extraction and methods of forming

    Science.gov (United States)

    Li, Ting

    2013-08-13

    The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

  15. Fabrication of nanopore and nanoparticle arrays with high aspect ratio AAO masks

    Science.gov (United States)

    Li, Z. P.; Xu, Z. M.; Qu, X. P.; Wang, S. B.; Peng, J.; Mei, L. H.

    2017-03-01

    How to use high aspect ratio anodic aluminum oxide (AAO) membranes as an etching and evaporation mask is one of the unsolved problems in the application of nanostructured arrays. Here we describe the versatile utilizations of the highly ordered AAO membranes with a high aspect ratio of more than 20 used as universal masks for the formation of various nanostructure arrays on various substrates. The result shows that the fabricated nanopore and nanoparticle arrays of substrates inherit the regularity of the AAO membranes completely. The flat AAO substrates and uneven AAO frontages were attached to the Si substrates respectively as an etching mask, which demonstrates that the two kinds of replication, positive and negative, represent the replication of the mirroring of Si substrates relative to the flat AAO substrates and uneven AAO frontages. Our work is a breakthrough for the broad research field of surface nano-masking.

  16. Wafer-scale fabrication of high-aspect ratio nanochannels based on edge-lithography technique.

    Science.gov (United States)

    Xie, Quan; Zhou, Qing; Xie, Fei; Sang, Jianming; Wang, Wei; Zhang, Haixia Alice; Wu, Wengang; Li, Zhihong

    2012-03-01

    This paper introduced a wafer-scale fabrication approach for the preparation of nanochannels with high-aspect ratio (the ratio of the channel depth to its width). Edge lithography was used to pattern nanogaps in an aluminum film, which was functioned as deep reactive ion etching mask thereafter to form the nanochannel. Nanochannels with aspect ratio up to 172 and width down to 44 nm were successfully fabricated on a 4-inch Si wafer with width nonuniformity less than 13.6%. A microfluidic chip integrated with nanometer-sized filters was successfully fabricated by utilizing the present method for geometric-controllable nanoparticle packing.

  17. Patterned growth of high aspect ratio silicon wire arrays at moderate temperature

    Science.gov (United States)

    Morin, Christine; Kohen, David; Tileli, Vasiliki; Faucherand, Pascal; Levis, Michel; Brioude, Arnaud; Salem, Bassem; Baron, Thierry; Perraud, Simon

    2011-04-01

    High aspect ratio silicon wire arrays with excellent pattern fidelity over wafer-scale area were grown by chemical vapor deposition at moderate temperature, using a gas mixture of silane and hydrogen chloride. An innovative two-step process was developed for in situ doping of silicon wires by diborane. This process led to high p-type doping levels, up to 10 18-10 19 cm -3, without degradation of the silicon wire array pattern fidelity.

  18. Flight Loads Prediction of High Aspect Ratio Wing Aircraft Using Multibody Dynamics

    Directory of Open Access Journals (Sweden)

    Michele Castellani

    2016-01-01

    Full Text Available A framework based on multibody dynamics has been developed for the static and dynamic aeroelastic analyses of flexible high aspect ratio wing aircraft subject to structural geometric nonlinearities. Multibody dynamics allows kinematic nonlinearities and nonlinear relationships in the forces definition and is an efficient and promising methodology to model high aspect ratio wings, which are known to be prone to structural nonlinear effects because of the high deflections in flight. The multibody dynamics framework developed employs quasi-steady aerodynamics strip theory and discretizes the wing as a series of rigid bodies interconnected by beam elements, representative of the stiffness distribution, which can undergo arbitrarily large displacements and rotations. The method is applied to a flexible high aspect ratio wing commercial aircraft and both trim and gust response analyses are performed in order to calculate flight loads. These results are then compared to those obtained with the standard linear aeroelastic approach provided by the Finite Element Solver Nastran. Nonlinear effects come into play mainly because of the need of taking into account the large deflections of the wing for flight loads computation and of considering the aerodynamic forces as follower forces.

  19. Fabrication of Aspheric Micro-Lens Mold with High Aspect Ratio

    Science.gov (United States)

    Naniwa, Irizo; Kanamaru, Masatoshi; Nakamura, Shigeo; Shimano, Takeshi; Horino, Masaya

    The optical pickup of our Small-Form-Factor Optical Disc Drives (SFFODDs) requires a micro-objective whose profile is composed of two aspheric surfaces. However, it is difficult to fabricate a micro-objective with an arbitrary aspheric surface and high aspect ratio using conventional techniques. We propose here a new method to fabricate an aspheric micro-lens mold with high aspect ratio. This method uses the micro-loading effect in Deep Reactive Ion Etching (DRIE) and isotropic Reactive Ion Etching (RIE). The micro-loading effect is a phenomenon that leads to different etching depths depending on the aperture size of the mask layer used in etching. We fabricated an aspheric micro-lens mold for the prototype by using the proposed method after experimental evaluations of the micro-loading effect for a feasibility study. The profile of the first prototype was slightly different from the designed one according as the distance from the lens center increase. The profile error of the second prototype was reduced by using a mask that had multiple apertures with the smallest aperture located outside the area where the crater was formed. Our proposed method was found to be effective for fabricating a micro-lens mold with an arbitrary aspheric surface and high aspect ratio.

  20. Design and Analyses of High Aspect Ratio Nozzles for Distributed Propulsion Acoustic Measurements

    Science.gov (United States)

    Dippold, Vance F., III

    2016-01-01

    A series of three convergent round-to-rectangular high-aspect ratio nozzles were designed for acoustics measurements. The nozzles have exit area aspect ratios of 8:1, 12:1, and 16:1. With septa inserts, these nozzles will mimic an array of distributed propulsion system nozzles, as found on hybrid wing-body aircraft concepts. Analyses were performed for the three nozzle designs and showed that the flow through the nozzles was free of separated flow and shocks. The exit flow was mostly uniform with the exception of a pair of vortices at each span-wise end of the nozzle.

  1. Proton beam writing and electroplating for the fabrication of high aspect ratio Au microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Yue Weisheng [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Ren Yaping [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Kan, Jeroen Anton van; Chiam, S.-Y. [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Jian, Linke; Moser, Herbert O. [Singapore Synchrotron Light Source, National University of Singapore, 5 Research Link, Singapore 117603 (Singapore); Osipowicz, Thomas [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore)], E-mail: phyto@nus.edu.sg; Watt, Frank [Centre for Ion Beam Applications, Department of Physics, National University of Singapore, Singapore 117542 (Singapore)

    2009-07-01

    We present an approach to fabricate tall high aspect ratio Au microstructures by means of proton beam direct writing. Combining proton beam direct writing and electroplating, we successfully produced gold structures with sub-micrometer lateral dimensions, structure heights in excess of 11 {mu}m, and aspect ratios over 28. Sidewall quality of the Au structures was improved by lowering the process temperature to 20 deg. C when developing PMMA patterns with GG developer. The application of such structures as X-ray masks for deep X-ray lithography with synchrotron radiation was demonstrated.

  2. Fabrication of High Aspect Ratio SU-8 Structures for Integrated Spectrometers

    DEFF Research Database (Denmark)

    Anhøj, Thomas Aarøe

    2007-01-01

    of photolithography. Successful fabrication of re ection gratings requires a high degree of precision in the photolithographic process. The fabrication process has thus been optimized by optimizing the photolithographic process for fabrication of high aspect ratio structures, i.e. structures with details...... that are small compared to the height of the structure. A decisive factor is the ability of the process to separate closely- spaced structures. The primary measure of quality is thus the aspect ratio of the narrowest trench which it is possible to resolve in the lithographic process. The optimization...

  3. Holes at High Blowing Ratios

    Directory of Open Access Journals (Sweden)

    Phillip M. Ligrani

    1996-01-01

    Full Text Available Experimental results are presented which describe the development and structure of flow downstream of a single row of holes with compound angle orientations producing film cooling at high blowing ratios. This film cooling configuration is important because similar arrangements are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 6d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 1.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes.

  4. A sub-atmospheric chemical vapor deposition process for deposition of oxide liner in high aspect ratio through silicon vias.

    Science.gov (United States)

    Lisker, Marco; Marschmeyer, Steffen; Kaynak, Mehmet; Tekin, Ibrahim

    2011-09-01

    The formation of a Through Silicon Via (TSV) includes a deep Si trench etching and the formation of an insulating layer along the high-aspect-ratio trench and the filling of a conductive material into the via hole. The isolation of the filling conductor from the silicon substrate becomes more important for higher frequencies due to the high coupling of the signal to the silicon. The importance of the oxide thickness on the via wall isolation can be verified using electromagnetic field simulators. To satisfy the needs on the Silicon dioxide deposition, a sub-atmospheric chemical vapor deposition (SA-CVD) process has been developed to deposit an isolation oxide to the walls of deep silicon trenches. The technique provides excellent step coverage of the 100 microm depth silicon trenches with the high aspect ratio of 20 and more. The developed technique allows covering the deep silicon trenches by oxide and makes the high isolation of TSVs from silicon substrate feasible which is the key factor for the performance of TSVs for mm-wave 3D packaging.

  5. Nanometer scale high-aspect-ratio trench etching at controllable angles using ballistic reactive ion etching

    Energy Technology Data Exchange (ETDEWEB)

    Cybart, Shane; Roediger, Peter; Ulin-Avila, Erick; Wu, Stephen; Wong, Travis; Dynes, Robert

    2012-11-30

    We demonstrate a low pressure reactive ion etching process capable of patterning nanometer scale angled sidewalls and three dimensional structures in photoresist. At low pressure the plasma has a large dark space region where the etchant ions have very large highly-directional mean free paths. Mounting the sample entirely within this dark space allows for etching at angles relative to the cathode with minimal undercutting, resulting in high-aspect ratio nanometer scale angled features. By reversing the initial angle and performing a second etch we create three-dimensional mask profiles.

  6. Simulation and Measurement of Neuroelectrodes' Characteristics with Integrated High Aspect Ratio Nano Structures

    Directory of Open Access Journals (Sweden)

    Christoph Nick

    2015-07-01

    Full Text Available Improving the interface between electrodes and neurons has been the focus of research for the last decade. Neuroelectrodes should show small geometrical surface area and low impedance for measuring and high charge injection capacities for stimulation. Increasing the electrochemically active surface area by using nanoporous electrode material or by integrating nanostructures onto planar electrodes is a common approach to improve this interface. In this paper a simulation approach for neuro electrodes' characteristics with integrated high aspect ratio nano structures based on a point-contact-model is presented. The results are compared with experimental findings conducted with real nanostructured microelectrodes. In particular, effects of carbon nanotubes and gold nanowires integrated onto microelectrodes are described. Simulated and measured impedance properties are presented and its effects onto the transfer function between the neural membrane potential and the amplifier output signal are studied based on the point-contact-model. Simulations show, in good agreement with experimental results, that electrode impedances can be dramatically reduced by the integration of high aspect ratio nanostructures such as gold nanowires and carbon nanotubes. This lowers thermal noise and improves the signal-to-noise ratio for measuring electrodes. It also may increase the adhesion of cells to the substrate and thus increase measurable signal amplitudes.

  7. Cryogenic Etching of High Aspect Ratio 400 nm Pitch Silicon Gratings.

    Science.gov (United States)

    Miao, Houxun; Chen, Lei; Mirzaeimoghri, Mona; Kasica, Richard; Wen, Han

    2016-10-01

    The cryogenic process and Bosch process are two widely used processes for reactive ion etching of high aspect ratio silicon structures. This paper focuses on the cryogenic deep etching of 400 nm pitch silicon gratings with various etching mask materials including polymer, Cr, SiO2 and Cr-on-polymer. The undercut is found to be the key factor limiting the achievable aspect ratio for the direct hard masks of Cr and SiO2, while the etch selectivity responds to the limitation of the polymer mask. The Cr-on-polymer mask provides the same high selectivity as Cr and reduces the excessive undercut introduced by direct hard masks. By optimizing the etching parameters, we etched a 400 nm pitch grating to ≈ 10.6 μm depth, corresponding to an aspect ratio of ≈ 53.

  8. Micro precision casting based on investment casting for micro structures with high aspect ratio

    Institute of Scientific and Technical Information of China (English)

    YANG Chuang; LI Bang-sheng; REN Ming-xing; FU Heng-zhi

    2009-01-01

    Microcasting is one of the significant technologies for the production of metallic micro parts with high aspect ratio (ratio of flow length to diameter). A micro precision casting technology based on investment casting using centrifugal method was investigated. The micro parts of Zn-4%Al alloy with an aspect ratio up to 200 was produced at the centrifugal speed of 1 500 r/min and the mold temperature of 270 ℃. The investigations on the relationship between flow length and rotational speed were carried out. For microcasting, the flow length is not only dependent on the centrifugal speed under the constant centrifugal radius, but also on the preheating temperature of mold. The flow length increases as the rotational speed and the mold temperature increase, and is much higher at a mold temperature of 270 ℃ than at other mold temperatures.

  9. A simple method for fabrication of high-aspect-ratio all-silicon grooves

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yuncan; Pan, An; Si, Jinhai, E-mail: jinhaisi@mail.xjtu.edu.cn; Chen, Tao; Chen, Feng; Hou, Xun

    2013-11-01

    A simple method using 800-nm femtosecond laser irradiation and chemical selective etching has been proposed for fabrication of high-aspect-ratio all-silicon grooves. Grooves with the maximum aspect ratio of 44 were produced. A scanning electronic microscopy equipped with an energy dispersive X-ray spectroscopy was employed to characterize the morphology and chemical composition of the grooves respectively. The formation mechanism of the grooves was attributed to the chemical reaction of the laser induced refractive index change microstructures and hydrofluoric acid solution. The dependences of the aspect ratio of the grooves on the laser irradiation parameters, such as: the numerical aperture of the microscope objective lens, the laser average power and the laser scanning velocity, are discussed.

  10. Aqueous solution route to high-aspect-ratio zinc oxide nanostructures on indium tin oxide substrates.

    Science.gov (United States)

    Ku, Chen-Hao; Wu, Jih-Jen

    2006-07-06

    High-aspect-ratio ZnO nanowires and nanotubes are formed on indium tin oxide (ITO) substrates using a three-step route at low temperatures. The three steps, including successive ionic layer absorption and reaction (SILAR) deposition of the ZnO seed layer, hydrothermal annealing of the seed layer, and chemical bath deposition (CBD) of the one-dimensional (1D) ZnO nanostructures, are all conducted in aqueous solutions at temperatures below 120 degrees C. Both the hydrothermal annealing of the SILAR seed layer and the low-concentration precursor solution employed in the CBD process are crucial in order to synthesize the uniform and high-aspect-ratio ZnO nanostructures on the ITO substrate. TEM analyses reveal that both the nanowire and the nanotube possess the single-crystal structure and are grown along [001] direction. Room-temperature cathodoluminescence spectrum of the 1D ZnO nanostructures shows a sharp ultraviolet emission at 375 nm and a broad green-band emission.

  11. High aspect ratio MEMS capacitor for high frequency impedance matching applications

    DEFF Research Database (Denmark)

    Yalcinkaya, Arda Deniz; Jensen, Søren; Hansen, Ole

    2003-01-01

    We present a microelectromechanical tunable capacitor with a low control voltage, a wide tuning range and adequate electrical quality factor. The device is fabricated in a single-crystalline silicon layer using deep reactive ion etching (DRIE) for obtaining high-aspect ratio (> 20) parallel comb-...... response and it was found that the device is a suitable passive component to be used in impedance matching applications, band-pass filtering or voltage controlled oscillators in the Very High Frequency (VHF) and Ultra High Frequency (UHF) bands.......We present a microelectromechanical tunable capacitor with a low control voltage, a wide tuning range and adequate electrical quality factor. The device is fabricated in a single-crystalline silicon layer using deep reactive ion etching (DRIE) for obtaining high-aspect ratio (> 20) parallel comb......-drive structures with vertical sidewalls. The process sequence for fabrication of the devices uses only one lithographic masking step and can be completed in a short time. The fabricated device was characterized with respect to electrical quality factor, tuning range, self-resonance frequency and transient...

  12. Combined AFM nano-machining and reactive ion etching to fabricate high aspect ratio structures.

    Science.gov (United States)

    Peng, Ping; Shi, Tielin; Liao, Guanglan; Tang, Zirong

    2010-11-01

    In this paper, a new combined method of sub-micron high aspect ratio structure fabrication is developed which can be used for production of nano imprint template. The process includes atomic force microscope (AFM) scratch nano-machining and reactive ion etching (RIE) fabrication. First, 40 nm aluminum film was deposited on the silicon substrate by magnetron sputtering, and then sub-micron grooves were fabricated on the aluminum film by nano scratch using AFM diamond tip. As aluminum film is a good mask for etching silicon, high aspect ratio structures were finally fabricated by RIE process. The fabricated structures were studied by SEM, which shows that the grooves are about 400 nm in width and 5 microm in depth. To obtain sub-micron scale groove structures on the aluminum film, experiments of nanomachining on aluminum films under various machining conditions were conducted. The depths of the grooves fabricated using different scratch loads were also studied by the AFM. The result shows that the material properties of the film/substrate are elastic-plastic following nearly a bilinear law with isotropic strain hardening. Combined AFM nanomachining and RIE process provides a relative lower cost nano fabrication technique than traditional e-beam lithography, and it has a good prospect in nano imprint template fabrication.

  13. Planarization of High Aspect Ratio P-I-N Diode Pillar Arrays for Blanket Electrical Contacts

    Energy Technology Data Exchange (ETDEWEB)

    Voss, L F; Shao, Q; Reinhardt, C E; Graff, R T; Conway, A M; Nikolic, R J; Deo, N; Cheung, C L

    2009-03-05

    Two planarization techniques for high aspect ratio three dimensional pillar structured P-I-N diodes have been developed in order to enable a continuous coating of metal on the top of the structures. The first technique allows for coating of structures with topography through the use of a planarizing photoresist followed by RIE etch back to expose the tops of the pillar structure. The second technique also utilizes photoresist, but instead allows for planarization of a structure in which the pillars are filled and coated with a conformal coating by matching the etch rate of the photoresist to the underlying layers. These techniques enable deposition using either sputtering or electron beam evaporation of metal films to allow for electrical contact to the tops of the underlying pillar structure. These processes have potential applications for many devices comprised of 3-D high aspect ratio structures. Two separate processes have been developed in order to ensure a uniform surface for deposition of an electrode on the {sup 10}Boron filled P-I-N pillar structured diodes. Each uses S1518 photoresist in order to achieve a relatively uniform surface despite the non-uniformity of the underlying detector. Both processes allow for metallization of the final structure and provide good electrical continuity over a 3D pillar structure.

  14. Diffusion of dilute gas in arrays of randomly distributed, vertically aligned, high-aspect-ratio cylinders

    Science.gov (United States)

    Guerra, Carlos

    2017-01-01

    In this work we modelled the diffusive transport of a dilute gas along arrays of randomly distributed, vertically aligned nanocylinders (nanotubes or nanowires) as opposed to gas diffusion in long pores, which is described by the well-known Knudsen theory. Analytical expressions for (i) the gas diffusion coefficient inside such arrays, (ii) the time between collisions of molecules with the nanocylinder walls (mean time of flight), (iii) the surface impingement rate, and (iv) the Knudsen number of such a system were rigidly derived based on a random-walk model of a molecule that undergoes memoryless, diffusive reflections from nanocylinder walls assuming the molecular regime of gas transport. It can be specifically shown that the gas diffusion coefficient inside such arrays is inversely proportional to the areal density of cylinders and their mean diameter. An example calculation of a diffusion coefficient is delivered for a system of titanium isopropoxide molecules diffusing between vertically aligned carbon nanotubes. Our findings are important for the correct modelling and optimisation of gas-based deposition techniques, such as atomic layer deposition or chemical vapour deposition, frequently used for surface functionalisation of high-aspect-ratio nanocylinder arrays in solar cells and energy storage applications. Furthermore, gas sensing devices with high-aspect-ratio nanocylinder arrays and the growth of vertically aligned carbon nanotubes need the fundamental understanding and precise modelling of gas transport to optimise such processes. PMID:28144565

  15. Characterization of the optical parameters of high aspect ratio polymer micro-optical components

    Science.gov (United States)

    Krajewski, Rafal; Van Erps, Jurgen; Wissmann, Markus; Kujawinska, Malgorzata; Parriaux, Olivier; Tonchev, S.; Mohr, Jurgen; Thienpont, Hugo

    2008-04-01

    Over the last decades the significant grow of interest of photonics devices is observed in various fields of applications. Due to the market demands, the current research studies are focused on the technologies providing miniaturized, reliable low-cost micro-optical systems, particularly the ones featuring the fabrication of high aspect ratio structures. A high potential of these technologies comes from the fact that fabrication process is not limited to single optical components, but entire systems integrating sets of elements could be fabricated. This could in turn result in a significant saving on the assembly and packaging costs. We present a brief overview of the most common high aspect ratio fabrication technologies for micro-optical components followed by some characterization studies of these techniques. The sidewall quality and internal homogeneity will be considered as the most crucial parameters, having an impact on the wavefront propagation in the fabricated components. We show the characterization procedure and measurement results for components prototyped with Deep Proton Writing and glass micromachining technology replicated with Hot Embossing and Elastomeric Mould Vacuum Casting technology. We discuss the pros and cons for using these technologies for the production of miniaturized interferometers blocks. In this paper we present the status of our research on the new technology chain and we show the concept of microinterferometers to be fabricated within presented technology chain.

  16. Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips

    KAUST Repository

    Li, Huawei

    2013-04-01

    This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.

  17. Hybrid UV Lithography for 3D High-Aspect-Ratio Microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sungmin; Nam, Gyungmok; Kim, Jonghun; Yoon, Sang-Hee [Inha Univ, Incheon (Korea, Republic of)

    2016-08-15

    Three-dimensional (3D) high-aspect-ratio (HAR) microstructures for biomedical applications (e.g., microneedle, microadhesive, etc.) are microfabricated using the hybrid ultraviolet (UV) lithography in which inclined, rotational, and reverse-side UV exposure processes are combined together. The inclined and rotational UV exposure processes are intended to fabricate tapered axisymmetric HAR microstructures; the reverse-side UV exposure process is designed to sharpen the end tip of the microstructures by suppressing the UV reflection on a bottom substrate which is inevitable in conventional UV lithography. Hybrid UV lithography involves fabricating 3D HAR microstructures with an epoxy-based negative photoresist, SU-8, using our customized UV exposure system. The effects of hybrid UV lithography parameters on the geometry of the 3D HAR microstructures (aspect ratio, radius of curvature of the end tip, etc.) are measured. The dependence of the end-tip shape on SU-8 soft-baking condition is also discussed.

  18. Maintaining high-Q in an optical microresonator coated with high-aspect-ratio gold nanorods

    Science.gov (United States)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2013-10-01

    We report methods to coat fused-silica microresonators with solution-grown high-aspect-ratio (AR) gold nanorods (NRs). Microresonators coated using our method maintain an optical quality factor (Q) greater than 107 after coating. The more successful method involves silanization of the surface of the microresonator with 3-mercaptopropylmethyldimethoxysilane (MPMDMS), to enable the adhesion of gold NRs. The high-AR NR-coated microresonator combines the field enhancement of localized surface plasmon resonances with the cavity-enhanced evanescent components of high-Q whispering-gallery modes, making it useful for plasmonic sensing applications in the infrared. By coating with NRs having a different aspect ratio, the enhancement regime can be selected within a wide range of wavelengths.

  19. Pilot Study of Inhaled Aerosols Targeted via Magnetic Alignment of High Aspect Ratio Particles in Rabbits

    Directory of Open Access Journals (Sweden)

    Gillian E. S. Redman

    2011-01-01

    Full Text Available Recently, inhaled pharmaceutical aerosols have seen increased investigation in the treatment of lung cancer, where the inability to deliver adequate therapeutic drug concentrations to tumour sites may be overcome with improved targeted delivery to the site of the tumour. In this study, the feasibility of magnetically targeted delivery of high aspect ratio particles loaded with iron oxide nanoparticles was studied in 19 New Zealand White rabbits. Half of the exposed rabbits had a magnetic field placed externally over their right lung. Iron sensitive magnetic resonance images of the lungs were acquired to determine the iron concentrations in the right and left lung of each animal. The right/left ratio increased in the middle and basal regions of the lung where, due to the morphology of the rabbit lung, this method of targeting is most effective. With further optimization, this technique could be an effective method for increasing the dose of drug delivered to a specific site within the lung.

  20. Multiscale Domain Decomposition Methods for Elliptic Problems with High Aspect Ratios

    Institute of Scientific and Technical Information of China (English)

    Jфrg Aarnes; Thomas Y. Hou

    2002-01-01

    In this paper we study some nonoverlapping domain decomposition methods for solving a class of elliptic problems arising from composite materials and flows in porous media which contain many spatial scales. Our preconditioner differs from traditional domain decomposition preconditioners by using a coarse solver which is adaptive to small scale heterogeneous features. While the convergence rate of traditional domain decomposition algorithms using coarse solvers based on linear or polynomial interpolations may deteriorate in the presence of rapid small scale oscillations or high aspect ratios, our preconditioner is applicable to multiplescale problems without restrictive assumptions and seems to have a convergence rate nearly independent of the aspect ratio within the substructures. A rigorous convergence analysis based on the Schwarz framework is carried out, and we demonstrate the efficiency and robustness of the proposed preconditioner through numerical experiments which include problems with multiple-scale coefficients, as well problems with continuous scales.

  1. Different methods to alter surface morphology of high aspect ratio structures

    Science.gov (United States)

    Leber, M.; Shandhi, M. M. H.; Hogan, A.; Solzbacher, F.; Bhandari, R.; Negi, S.

    2016-03-01

    In various applications such as neural prostheses or solar cells, there is a need to alter the surface morphology of high aspect ratio structures so that the real surface area is greater than geometrical area. The change in surface morphology enhances the devices functionality. One of the applications of altering the surface morphology is of neural implants such as the Utah electrode array (UEA) that communicate with single neurons by charge injection induced stimulation or by recording electrical neural signals. For high selectivity between single cells of the nervous system, the electrode surface area is required to be as small as possible, while the impedance is required to be as low as possible for good signal to noise ratios (SNR) during neural recording. For stimulation, high charge injection and charge transfer capacities of the electrodes are required, which increase with the electrode surface. Traditionally, researchers have worked with either increasing the roughness of the existing metallization (platinum grey, black) or other materials such as Iridium Oxide and PEDOT. All of these previously investigated methods lead to more complicated metal deposition processes that are difficult to control and often have a critical impact on the mechanical properties of the metal films. Therefore, a modification of the surface underneath the electrode's coating will increase its surface area while maintaining the standard and well controlled metal deposition process. In this work, the surfaces of the silicon micro-needles were engineered by creating a defined microstructure on the electrodes surface using several methods such as laser ablation, focused ion beam, sputter etching, reactive ion etching (RIE) and deep reactive ion etching (DRIE). The surface modification processes were optimized for the high aspect ratio silicon structures of the UEA. The increase in real surface area while maintaining the geometrical surface area was verified using scanning electron

  2. High yield polyol synthesis of round- and sharp-end silver nanowires with high aspect ratio

    Energy Technology Data Exchange (ETDEWEB)

    Nekahi, A.; Marashi, S.P.H., E-mail: pmarashi@aut.ac.ir; Fatmesari, D. Haghshenas

    2016-12-01

    Long silver nanowires (average length of 28 μm, average aspect ratio of 130) with uniform diameter along their length were produced by polyol synthesis of AgNO{sub 3} in ethylene glycol in the presence of PVP as preferential growth agent. Nanowires were produced with no addition of chloride salts such as NaCl or CuCl{sub 2} (or other additives such as Na{sub 2}S) which are usually used for lowering reduction rate of Ag ions by additional etchant of O{sub 2}/Cl{sup −}. Lower reduction rate was obtained by increasing the injection time of PVP and AgNO{sub 3} solutions, which was the significant factor in the formation of nanowires. Therefore, there was enough time for reduced Ag atoms to be deposited preferentially in the direction of PVP chains, resulting in high yield (the fraction of nanowires in the products) of nanowires (more than 95%) with high aspect ratio. The produced nanowires had both round- and sharp-ends with pentagonal cross section. Higher energy level of Ag atoms in borders of MTPs, which increases the dissolution rate of precipitated atoms, in addition to partial melting of MTPs at high synthesis temperatures, leads to the curving of the surfaces of exposed (111) crystalline planes in some MTPs and the formation of round-end silver nanowires. - Highlights: • Long silver nanowires with high aspect ratio of 130 were produced. • More than 95% nanowires were produced in products. • The produced nanowires had round- and sharp-ends with pentagonal cross section. • Additives were needed neither for high yield synthesis nor for round-end nanowires. • Melting and etching of MTPs in high energy borders resulted to round-end nanowires.

  3. Gust response analysis and wind tunnel test for a high-aspect ratio wing

    Directory of Open Access Journals (Sweden)

    Liu Yi

    2016-02-01

    Full Text Available A theoretical nonlinear aeroelastic response analysis for a flexible high-aspect ratio wing excited by harmonic gust load is presented along with a companion wind tunnel test. A multidisciplinary coupled numerical calculation is developed to simulate the flexible model wing undergoing gust load in the time domain via discrete nonlinear finite element structural dynamic analysis and nonplanar unsteady vortex lattice aerodynamic computation. A dynamic perturbation analysis about a nonlinear static equilibrium is also used to determine the small perturbation flutter boundary. A novel noncontact 3-D camera measurement analysis system is firstly used in the wind tunnel test to obtain the spatial large deformation and responses. The responses of the flexible wing under different static equilibrium states and frequency gust loads are discussed. The fair to good quantitative agreements between the theoretical and experimental results demonstrate that the presented analysis method is an acceptable way to predict the geometrically nonlinear gust response for flexible wings.

  4. A new multifunctional platform based on high aspect ratio interdigitated NEMS structures

    Energy Technology Data Exchange (ETDEWEB)

    Ghatnekar-Nilsson, S; Karlsson, I; Kvennefors, A; Luo, G; Zela, V; Parker, T; Litwin, A [NEMS AB, Solvegatan 16, S-223 62 Lund (Sweden); Arlelid, M [Electrical and Information Technology, Lund University, PO Box 118, S-221 00 Lund (Sweden); Montelius, L [Solid State Physics/The Nanometer Structure Consortium, Lund University, PO Box 118, S-221 00 Lund (Sweden)], E-mail: andrej.litwin@nems.se

    2009-04-29

    A multifunctional NEMS platform based on a mass-producible, surface relief grating has been developed and fabricated directly in polymer materials. The pattern consists of high aspect ratio interdigitated nanometer-sized pairs of walls and can be produced in a low-complexity one-step patterning process with nanoimprint lithography. In this paper, we demonstrate the usefulness of the platform primarily by showing an application as a high-sensitivity mass sensor in air. The sensors, which are based on the high frequency resonant response of around 200 MHz, show a mass responsivity of the order of 0.1 Hz/zg per wall at room temperature and in ambient air. Their ability to selectively adsorb airborne target molecules, such as thiols, is also demonstrated. We also show that the same device can function as a varactor for electronic circuits based on its large tunable capacitive range.

  5. A new multifunctional platform based on high aspect ratio interdigitated NEMS structures.

    Science.gov (United States)

    Ghatnekar-Nilsson, S; Karlsson, I; Kvennefors, A; Luo, G; Zela, V; Arlelid, M; Parker, T; Montelius, L; Litwin, A

    2009-04-29

    A multifunctional NEMS platform based on a mass-producible, surface relief grating has been developed and fabricated directly in polymer materials. The pattern consists of high aspect ratio interdigitated nanometer-sized pairs of walls and can be produced in a low-complexity one-step patterning process with nanoimprint lithography. In this paper, we demonstrate the usefulness of the platform primarily by showing an application as a high-sensitivity mass sensor in air. The sensors, which are based on the high frequency resonant response of around 200 MHz, show a mass responsivity of the order of 0.1 Hz/zg per wall at room temperature and in ambient air. Their ability to selectively adsorb airborne target molecules, such as thiols, is also demonstrated. We also show that the same device can function as a varactor for electronic circuits based on its large tunable capacitive range.

  6. Dynamics of polymer nanoparticles through a single artificial nanopore with a high-aspect-ratio.

    Science.gov (United States)

    Cabello-Aguilar, Simon; Chaaya, Adib Abou; Bechelany, Mikhael; Pochat-Bohatier, Céline; Balanzat, Emmanuel; Janot, Jean-Marc; Miele, Philippe; Balme, Sébastien

    2014-11-14

    The development of nanometric Coulter counters for nanoparticle detection is an attractive and promising field of research. In this work, we have studied the influence of the nanopore surface state on charged polymer nanoparticle translocations. To make this, the translocation of carboxylate modified polystyrene microspheres (diameter 40, 70 and 100 nm) has been investigated through two kinds of high aspect ratio nanopores (negative and uncharged). The latter were tailored by a single track-etched and atomic layer deposition technique. It was shown that the mobility and the energy barrier are strongly dependent on nanopore surface charge. Typically if the latter exhibits negative surface charge, the microsphere mobility increases and the global energy barrier of entrance inside the nanopore decreases with its diameter, converse to the uncharged nanopore.

  7. Surface-diffusion-driven decay of high-aspect-ratio gratings: existence of morphologically related classes.

    Science.gov (United States)

    Madrid, Marcos A; Salvarezza, Roberto C; Castez, Marcos F

    2013-06-01

    We present numerical and theoretical results concerning the technologically important process of evolution of high-aspect-ratio profiles due to surface diffusion under thermal treatment. We show how a broad class of initial gratings adopt, after a short transient stage, a typical shape that can be accurately described as a curve whose curvature has only two single Fourier modes as a function of the arc-length parameter. Moreover, we introduce a set of evolution equations for the relevant parameters that accounts very accurately for both morphological and kinetic aspects of the transformation processes for these curves in a wide region in parameter space. Regarding the decay of rectangular gratings, our numerical results show the existence of geometrically related classes that asymptotically approach to the same trajectory in parameter space. Gratings belonging to the same class pass through the same sequence of morphologies before reaching the final equilibrium state.

  8. A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

    Science.gov (United States)

    Alaferdov, A. V.; Savu, R.; Rackauskas, T. A.; Rackauskas, S.; Canesqui, M. A.; de Lara, D. S.; Setti, G. O.; Joanni, E.; de Trindade, G. M.; Lima, U. B.; de Souza, A. S.; Moshkalev, S. A.

    2016-09-01

    A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ˜103) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

  9. Design and Simulation of BTT Missile with High-Aspect-Ratio Wing Robust H∞ Autopilot

    Institute of Scientific and Technical Information of China (English)

    CUI Sheng-wang; LIU Li; MA Chun-yan

    2007-01-01

    For the strong coupling among the channels of bank-to-turn (BTT) missile with high-aspect-ratio wing,an autopilot is designed with a two loop control structure robust autopilot design methods.By the inner loop design,the question of pole-zero cancellation is solved,and the stabilization of structured uncertainty is achieved.Through the outer loop of H∞ controller design,the flying performance and robustness can be guaranteed.The nonlinear simulation results show that the autopilot designed has perfect time domain response,and can suppress bad influence of the inertial and kinematics couplings.It can make the missile fly stably in the large flying areas.The control is very effective.

  10. Large-area thermoelectric high-aspect-ratio nanostructures by atomic layer deposition

    Science.gov (United States)

    Ruoho, Mikko; Juntunen, Taneli; Tittonen, Ilkka

    2016-09-01

    We report on the thermoelectric properties of large-area high-aspect-ratio nanostructures. We fabricate the structures by atomic layer deposition of conformal ZnO thin films on track-etched polycarbonate substrate. The resulting structure consists of ZnO tubules which continue through the full thickness of the substrate. The electrical and thermal properties of the structures are studied both in-plane and out-of-plane. They exhibit very low out-of-plane thermal conductivity down to 0.15 W m-1 K-1 while the in-plane sheet resistance of the films was found to be half that of the same film on glass substrate, allowing material-independent doubling of output power of any planar thin-film thermoelectric generator. The wall thickness of the fabricated nanotubes was varied within a range of up to 100 nm. The samples show polycrystalline nature with (002) preferred crystal orientation.

  11. Plasma-assisted atomic layer deposition of conformal Pt films in high aspect ratio trenches

    Science.gov (United States)

    Erkens, I. J. M.; Verheijen, M. A.; Knoops, H. C. M.; Keuning, W.; Roozeboom, F.; Kessels, W. M. M.

    2017-02-01

    To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe3 vapor and O2 gas at 300 °C. Plasma-assisted ALD of Pt using O2 plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

  12. Nanofabrication of high aspect ratio structures using an evaporated resist containing metal

    Science.gov (United States)

    Con, Celal; Zhang, Jian; Cui, Bo

    2014-05-01

    Organic electron beam resists are typically not resistant to the plasma etching employed to transfer the pattern into the underlying layer. Here, the authors present the incorporation of a metal hard mask material into negative resist polystyrene by co-evaporation of the polystyrene and the metal onto a substrate. With a volume ratio of 1:15 between Cr and polystyrene, this nanocomposite resist showed an etching selectivity to silicon one order higher than pure polystyrene resist. Silicon structures of 100 nm width and 3.5 μm height (aspect ratio 1:35) were obtained using a non-switching deep silicon etching recipe with SF6 and C4F8 gas. Moreover, unlike the common spin coating method, evaporated nanocomposite resist can be coated onto irregular and non-flat surfaces such as optical fibers and AFM cantilevers. As a proof of concept, we fabricated high aspect ratio structures on top of an AFM cantilever. Nanofabrication on non-flat surfaces may find applications in the fields of (AFM) tip enhanced Raman spectroscopy for chemical analysis and lab-on-fiber technology.

  13. Etching of Silicon in HBr Plasmas for High Aspect Ratio Features

    Science.gov (United States)

    Hwang, Helen H.; Meyyappan, M.; Mathad, G. S.; Ranade, R.

    2002-01-01

    Etching in semiconductor processing typically involves using halides because of the relatively fast rates. Bromine containing plasmas can generate high aspect ratio trenches, desirable for DRAM and MEMS applications, with relatively straight sidewalk We present scanning electron microscope images for silicon-etched trenches in a HBr plasma. Using a feature profile simulation, we show that the removal yield parameter, or number of neutrals removed per incident ion due to all processes (sputtering, spontaneous desorption, etc.), dictates the profile shape. We find that the profile becomes pinched off when the removal yield is a constant, with a maximum aspect ratio (AR) of about 5 to 1 (depth to height). When the removal yield decreases with increasing ion angle, the etch rate increases at the comers and the trench bottom broadens. The profiles have ARs of over 9:1 for yields that vary with ion angle. To match the experimentally observed etched time of 250 s for an AR of 9:1 with a trench width of 0.135 microns, we find that the neutral flux must be 3.336 x 10(exp 17)sq cm/s.

  14. Large-Area High Aspect Ratio Plasmonic Interference Lithography Utilizing a Single High-k Mode.

    Science.gov (United States)

    Chen, Xi; Yang, Fan; Zhang, Cheng; Zhou, Jing; Guo, L Jay

    2016-04-26

    Plasmonic lithography, which utilizes subwavelength confinement of surface plasmon polartion (SPP) waves, has the capability of breaking the diffraction limit and delivering high resolution. However, all previously reported results suffer from critical issues, such as shallow pattern depth and pattern nonuniformity even over small exposure areas, which limit the application of the technology. In this work, periodic patterns with high aspect ratios and a half-pitch of about 1/6 of the wavelength were achieved with pattern uniformity in square centimeter areas. This was accomplished by designing a special mask and photoresist (PR) system to select a single high spatial frequency mode and incorporating the PR into a waveguide configuration to ensure uniform light exposure over the entire depth of the photoresist layer. In addition to the experimental progress toward large-scale applications of plasmonic interference lithography, the general criteria of designing such an exposure system is also discussed, which can be used for nanoscale fabrication in this fashion for various applications with different requirements for wavelength, pitch, aspect ratio, and structure.

  15. Aerodynamic Properties of Rough Surfaces with High Aspect-Ratio Roughness Elements: Effect of Aspect Ratio and Arrangements

    Science.gov (United States)

    Sadique, Jasim; Yang, Xiang I. A.; Meneveau, Charles; Mittal, Rajat

    2017-05-01

    We examine the effect of varying roughness-element aspect ratio on the mean velocity distributions of turbulent flow over arrays of rectangular-prism-shaped elements. Large-eddy simulations (LES) in conjunction with a sharp-interface immersed boundary method are used to simulate spatially-growing turbulent boundary layers over these rough surfaces. Arrays of aligned and staggered rectangular roughness elements with aspect ratio >1 are considered. First the temporally- and spatially-averaged velocity profiles are used to illustrate the aspect-ratio effects. For aligned prisms, the roughness length (z_o) and the friction velocity (u_*) increase initially with an increase in the roughness-element aspect ratio, until the values reach a plateau at a particular aspect ratio. The exact value of this aspect ratio depends on the coverage density. Further increase in the aspect ratio changes neither z_o, u_* nor the bulk flow above the roughness elements. For the staggered cases, z_o and u_* continue to increase for the surface coverage density and the aspect ratios investigated. To model the flow response to variations in roughness aspect ratio, we turn to a previously developed phenomenological volumetric sheltering model (Yang et al., in J Fluid Mech 789:127-165, 2016), which was intended for low to moderate aspect-ratio roughness elements. Here, we extend this model to account for high aspect-ratio roughness elements. We find that for aligned cases, the model predicts strong mutual sheltering among the roughness elements, while the effect is much weaker for staggered cases. The model-predicted z_o and u_* agree well with the LES results. Results show that the model, which takes explicit account of the mutual sheltering effects, provides a rapid and reliable prediction method of roughness effects in turbulent boundary-layer flows over arrays of rectangular-prism roughness elements.

  16. A small perturbation based optimization approach for the frequency placement of high aspect ratio wings

    Science.gov (United States)

    Goltsch, Mandy

    Design denotes the transformation of an identified need to its physical embodiment in a traditionally iterative approach of trial and error. Conceptual design plays a prominent role but an almost infinite number of possible solutions at the outset of design necessitates fast evaluations. The corresponding practice of empirical equations and low fidelity analyses becomes obsolete in the light of novel concepts. Ever increasing system complexity and resource scarcity mandate new approaches to adequately capture system characteristics. Contemporary concerns in atmospheric science and homeland security created an operational need for unconventional configurations. Unmanned long endurance flight at high altitudes offers a unique showcase for the exploration of new design spaces and the incidental deficit of conceptual modeling and simulation capabilities. Structural and aerodynamic performance requirements necessitate light weight materials and high aspect ratio wings resulting in distinct structural and aeroelastic response characteristics that stand in close correlation with natural vibration modes. The present research effort evolves around the development of an efficient and accurate optimization algorithm for high aspect ratio wings subject to natural frequency constraints. Foundational corner stones are beam dimensional reduction and modal perturbation redesign. Local and global analyses inherent to the former suggest corresponding levels of local and global optimization. The present approach departs from this suggestion. It introduces local level surrogate models to capacitate a methodology that consists of multi level analyses feeding into a single level optimization. The innovative heart of the new algorithm originates in small perturbation theory. A sequence of small perturbation solutions allows the optimizer to make incremental movements within the design space. It enables a directed search that is free of costly gradients. System matrices are decomposed

  17. High aspect ratio AFM Probe processing by helium-ion-beam induced deposition.

    Science.gov (United States)

    Onishi, Keiko; Guo, Hongxuan; Nagano, Syoko; Fujita, Daisuke

    2014-11-01

    A Scanning Helium Ion Microscope (SHIM) is a high resolution surface observation instrument similar to a Scanning Electron Microscope (SEM) since both instruments employ finely focused particle beams of ions or electrons [1]. The apparent difference is that SHIMs can be used not only for a sub-nanometer scale resolution microscopic research, but also for the applications of very fine fabrication and direct lithography of surfaces at the nanoscale dimensions. On the other hand, atomic force microscope (AFM) is another type of high resolution microscopy which can measure a three-dimensional surface morphology by tracing a fine probe with a sharp tip apex on a specimen's surface.In order to measure highly uneven and concavo-convex surfaces by AFM, the probe of a high aspect ratio with a sharp tip is much more necessary than the probe of a general quadrangular pyramid shape. In this paper we report the manufacture of the probe tip of the high aspect ratio by ion-beam induced gas deposition using a nanoscale helium ion beam of SHIM.Gas of platinum organic compound was injected into the sample surface neighborhood in the vacuum chamber of SHIM. The decomposition of the gas and the precipitation of the involved metal brought up a platinum nano-object in a pillar shape on the normal commercial AFM probe tip. A SHIM system (Carl Zeiss, Orion Plus) equipped with the gas injection system (OmniProbe, OmniGIS) was used for the research. While the vacuum being kept to work, we injected platinum organic compound ((CH3)3(CH3C5H4)Pt) into the sample neighborhood and irradiated the helium ion beam with the shape of a point on the apex of the AFM probe tip. It is found that we can control the length of the Pt nano-pillar by irradiation time of the helium ion beam. The AFM probe which brought up a Pt nano-pillar is shown in Figure 1. It is revealed that a high-aspect-ratio Pt nano-pillar of ∼40nm diameter and up to ∼2000 nm length can be grown. In addition, for possible heating

  18. Gust response analysis and wind tunnel test for a high-aspect ratio wing

    Institute of Scientific and Technical Information of China (English)

    Liu Yi; Xie Changchuan; Yang Chao; Cheng Jialin

    2016-01-01

    A theoretical nonlinear aeroelastic response analysis for a flexible high-aspect ratio wing excited by harmonic gust load is presented along with a companion wind tunnel test. A multidisci-plinary coupled numerical calculation is developed to simulate the flexible model wing undergoing gust load in the time domain via discrete nonlinear finite element structural dynamic analysis and nonplanar unsteady vortex lattice aerodynamic computation. A dynamic perturbation analysis about a nonlinear static equilibrium is also used to determine the small perturbation flutter bound-ary. A novel noncontact 3-D camera measurement analysis system is firstly used in the wind tunnel test to obtain the spatial large deformation and responses. The responses of the flexible wing under different static equilibrium states and frequency gust loads are discussed. The fair to good quanti-tative agreements between the theoretical and experimental results demonstrate that the presented analysis method is an acceptable way to predict the geometrically nonlinear gust response for flex-ible wings.

  19. Dimensional measurement of micro parts with high aspect ratio in HIT-UOI

    Science.gov (United States)

    Dang, Hong; Cui, Jiwen; Feng, Kunpeng; Li, Junying; Zhao, Shiyuan; Zhang, Haoran; Tan, Jiubin

    2016-11-01

    Micro parts with high aspect ratios have been widely used in different fields including aerospace and defense industries, while the dimensional measurement of these micro parts becomes a challenge in the field of precision measurement and instrument. To deal with this contradiction, several probes for the micro parts precision measurement have been proposed by researchers in Center of Ultra-precision Optoelectronic Instrument (UOI), Harbin Institute of Technology (HIT). In this paper, optical fiber probes with structures of spherical coupling(SC) with double optical fibers, micro focal-length collimation (MFL-collimation) and fiber Bragg grating (FBG) are described in detail. After introducing the sensing principles, both advantages and disadvantages of these probes are analyzed respectively. In order to improve the performances of these probes, several approaches are proposed. A two-dimensional orthogonal path arrangement is propounded to enhance the dimensional measurement ability of MFL-collimation probes, while a high resolution and response speed interrogation method based on differential method is used to improve the accuracy and dynamic characteristics of the FBG probes. The experiments for these special structural fiber probes are given with a focus on the characteristics of these probes, and engineering applications will also be presented to prove the availability of them. In order to improve the accuracy and the instantaneity of the engineering applications, several techniques are used in probe integration. The effectiveness of these fiber probes were therefore verified through both the analysis and experiments.

  20. Tunable Ultra-high Aspect Ratio Nanorod Architectures grown on Porous Substrate via Electromigration.

    Science.gov (United States)

    Mansourian, Ali; Paknejad, Seyed Amir; Wen, Qiannan; Vizcay-Barrena, Gema; Fleck, Roland A; Zayats, Anatoly V; Mannan, Samjid H

    2016-02-29

    The interplay between porosity and electromigration can be used to manipulate atoms resulting in mass fabrication of nanoscale structures. Electromigration usually results in the accumulation of atoms accompanied by protrusions at the anode and atomic depletion causing voids at the cathode. Here we show that in porous media the pattern of atomic deposition and depletion is altered such that atomic accumulation occurs over the whole surface and not just at the anode. The effect is explained by the interaction between atomic drift due to electric current and local temperature gradients resulting from intense Joule heating at constrictions between grains. Utilizing this effect, a porous silver substrate is used to mass produce free-standing silver nanorods with very high aspect ratios of more than 200 using current densities of the order of 10(8) A/m(2). This simple method results in reproducible formation of shaped nanorods, with independent control over their density and length. Consequently, complex patterns of high quality single crystal nanorods can be formed in-situ with significant advantages over competing methods of nanorod formation for plasmonics, energy storage and sensing applications.

  1. Analysis of Interrupted Rectangular Microchannel Heat Sink with High Aspect Ratio

    Directory of Open Access Journals (Sweden)

    Harshin Kamal

    2017-01-01

    Full Text Available A computational modelling of microchannel heat sinks with high aspect ratio has been performed to compare the geometrical features in the plane parallel to the heating surface and to determine the optimum configuration for the best heat transfer characteristics. A periodic thermal development of flow can cause significant heat transfer enhancement. A consensus on a particular geometrical configuration that provides the best heat transfer characteristics has not been reached in the literature, although many novel ideas have been proposed recently. Firstly the validity and applicability of microchannel sink modelling is presented followed by an optimization of parameters of interrupted microchannel heat sink. Consequences of the multichannel effect due to the introduction of transverse microchamber are also presented. It has been shown that the average Nusselt number of the microchannel heat sink increases by the introduction of a transverse microchamber with the additional advantage of a lower pressure drop. There exists an optimum width for the transverse microchamber for which the interrupted microchannel heat sink shows optimum characteristics.

  2. High-speed microprobe for roughness measurements in high-aspect-ratio microstructures

    Science.gov (United States)

    Doering, Lutz; Brand, Uwe; Bütefisch, Sebastian; Ahbe, Thomas; Weimann, Thomas; Peiner, Erwin; Frank, Thomas

    2017-03-01

    Cantilever-type silicon microprobes with an integrated tip and a piezoresistive signal read out have successfully proven to bridge the gap between scanning force microscopy and stylus profilometry. Roughness measurements in high-aspect-ratio microstructures (HARMS) with depths down to 5 mm and widths down to 50 µm have been demonstrated. To improve the scanning speed up to 15 mm s‑1, the wear of the tip has to be reduced. The atomic layer deposition (ALD) technique with alumina (Al2O3) has been tested for this purpose. Repeated wear measurements with coated and uncoated microprobe cantilevers have been carried out on a roughness standard at a speed of 15 mm s‑1. The tip shape and the wear have been measured using a new probing tip reference standard containing rectangular silicon grooves with widths from 0.3 µm to 3 µm. The penetration depth of the microprobe allows one to measure the wear of the tip as well as the tip width and the opening angle of the tip. The roughness parameters obtained on the roughness standard during wear experiments agree well with the reference values measured with a calibrated stylus instrument, nevertheless a small amount of wear still is observable. Further research is necessary in order to obtain wear resistant microprobe tips for non-destructive inspection of microstructures in industry and microform measurements, for example in injection nozzles.

  3. Gas-Assisted Heating Technology for High Aspect Ratio Microstructure Injection Molding

    Directory of Open Access Journals (Sweden)

    Shia-Chung Chen

    2013-01-01

    Full Text Available A hot gas is used for heating the cavity surface of a mold. Different mold gap sizes were designed. The mold surface temperature was heated to above the glass transition temperature of the plastic material, and the mold then closed for melt filling. The cavity surface can be heated to 130°C to assist the melt filling of the microfeatures. Results show that hot gas heating can improve the filling process and achieve 91% of the high aspect ratio microgrooves (about 640.38 μm of the maximum of 700 μm. The mold gap size strongly affects the heating speed and heating uniformity. Without surface preheating, the center rib is the highest. When the heating target temperature is 90°C or 100°C, the three microribs have a good uniformity of height. However, when the target temperature exceeds 100°C, the left side rib is higher than the other ribs.

  4. Bosch-like method for creating high aspect ratio poly(methyl methacrylate) (PMMA) structures

    KAUST Repository

    Haiducu, Marius

    2012-02-02

    This paper presents a method for etching millimetre-deep trenches in commercial grade PMMA using deep-UV at 254 nm. The method is based on consecutive cycles of irradiation and development of the exposed areas, respectively. The exposure segment is performed using an inexpensive, in-house built irradiation box while the development part is accomplished using an isopropyl alcohol (IPA):H2O developer. The method was tested and characterized by etching various dimension square test structures in commercial grade, mirrored acrylic. The undercut of the sidewalls due to the uncollimated nature of the irradiation light was dramatically alleviated by using a honeycomb metallic grid in between the irradiation source and the acrylic substrate and by rotating the latter using a direct current (DC) motor-driven stage. By using an extremely affordable set-up and non-toxic, environmentally friendly materials and substances, this process represents an excellent alternative to microfabricating microfluidic devices in particular and high aspect ratio structures in general using PMMA as substrate. © 2012 SPIE.

  5. Ultra-high aspect ratio copper nanowires as transparent conductive electrodes for dye sensitized solar cells

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2016-09-01

    We report the synthesis of ultra-high aspect ratio copper nanowires (CuNW) and fabrication of CuNW-based transparent conductive electrodes (TCE) with high optical transmittance (>80%) and excellent sheet resistance (Rs zinc oxide (AZO) thin-film coatings, or platinum thin film coatings, or nickel thin-film coatings. Our hybrid transparent electrodes can replace indium tin oxide (ITO) films in dye-sensitized solar cells (DSSCs) as either anodes or cathodes. We highlight the challenges of integrating bare CuNWs into DSSCs, and demonstrate that hybridization renders the solar cell integrations feasible. The CuNW/AZO-based DSSCs have reasonably good open-circuit voltage (Voc = 720 mV) and short-circuit current-density (Jsc = 0.96 mA/cm2), which are comparable to what is obtained with an ITO-based DSSC fabricated with a similar process. Our CuNW-Ni based DSSCs exhibit a good open-circuit voltage (Voc = 782 mV) and a decent short-circuit current (Jsc = 3.96 mA/cm2), with roughly 1.5% optical-to-electrical conversion efficiency.

  6. Atomic Layer Deposition for Coating of High Aspect Ratio TiO2 Nanotube Layers

    Science.gov (United States)

    2016-01-01

    We present an optimized approach for the deposition of Al2O3 (as a model secondary material) coating into high aspect ratio (≈180) anodic TiO2 nanotube layers using the atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al2O3 precursors on the resulting coating thickness, ALD processes with different exposure times (i.e., 0.5, 2, 5, and 10 s) of the trimethylaluminum (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 s), as verified by detailed scanning electron microscopy analysis. Quartz crystal microbalance measurements were used to monitor the deposition process and its particular features due to the tube diameter gradient. Finally, theoretical calculations were performed to calculate the minimum precursor exposure time to attain uniform coating. Theoretical values on the diffusion regime matched with the experimental results and helped to obtain valuable information for further optimization of ALD coating processes. The presented approach provides a straightforward solution toward the development of many novel devices, based on a high surface area interface between TiO2 nanotubes and a secondary material (such as Al2O3). PMID:27643411

  7. High-Aspect Ratio Bio-Metallic Nanocomposites for Cellular Interactions

    Science.gov (United States)

    Deodhar, Sneha; Huckaby, Justin; Delahoussaye, Miles; DeCoster, Mark A.

    2014-08-01

    We synthesized high aspect ratio composites with biological and metal components. Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM) revealed linear morphology and smooth surface texture. SEM, TEM and light microscopy showed that composites have scalable dimensions from nano- to micro-, with diameters as low as 60 nm, lengths exceeding 150 pm, and average aspect ratio of 100. The structures are stable, remaining intact for over one year in dried form and in liquid, and did not aggregate, in contrast to metal nanoparticles such as iron and copper. Many metal nanoparticles are toxic to cells, limiting their use for biological applications. The bio-metallic composites characterized here showed lower toxicity compared to their precursor metal nanoparticles in brain tumor cell cultures. Due to these more biocompatible properties, we tested the ability of the composites to interact with cells. Zeta potential analysis indicated that composites carry a net negative charge (-24.3 ± 2.2 mV), while the starting metal nanoparticles measured (43.3 ± 2.4 mV). We labeled the composites with poly-l-lysine fluorescein isothiocyanate (PLL-FITC), which shifted the potential to 3.5 ± 2.9 mV. It was observed by fluorescence microscopy that composites smaller than cells were internalized by some cells and larger composites remained outside. Cells became fluorescent over time due to leakage of PLL-FITC from the composites which lost fluorescence over time. Higher biocompatibility, low aggregation, and ability to control size distribution of the linear composites may make them ideal vehicles to deliver drugs or other materials to cells, and may be used as a scaffolding material for cells.

  8. Geometrical Nonlinear Aeroelastic Stability Analysis of a Composite High-Aspect-Ratio Wing

    Directory of Open Access Journals (Sweden)

    Chang Chuan Xie

    2008-01-01

    Full Text Available A composite high-aspect-ratio wing of a high-altitude long-endurance (HALE aircraft was modeled with FEM by MSC/NASTRAN, and the nonlinear static equilibrium state is calculated under design load with follower force effect, but without load redistribution. Assuming the little vibration amplitude of the wing around the static equilibrium state, the system is linearized and the natural frequencies and mode shapes of the deformed structure are obtained. Planar doublet lattice method is used to calculate unsteady aerodynamics in frequency domain ignoring the bending effect of the deflected wing. And then, the aeroelastic stability analysis of the system under a given load condition is successively carried out. Comparing with the linear results, the nonlinear displacement of the wing tip is higher. The results indicate that the critical nonlinear flutter is of the flap/chordwise bending type because of the chordwise bending having quite a large torsion component, with low critical speed and slowly growing damping, which dose not appear in the linear analysis. Furthermore, it is shown that the variation of the nonlinear flutter speed depends on the scale of the load and on the chordwise bending frequency. The research work indicates that, for the very flexible HALE aircraft, the nonlinear aeroelastic stability is very important, and should be considered in the design progress. Using present FEM software as the structure solver (e.g. MSC/NASTRAN, and the unsteady aerodynamic code, the nonlinear aeroelastic stability margin of a complex system other than a simple beam model can be determined.

  9. GaN nanowire tip for high aspect ratio nano-scale AFM metrology (Conference Presentation)

    Science.gov (United States)

    Behzadirad, Mahmoud; Dawson, Noel; Nami, Mohsen; Rishinaramangalam, Ashwin K.; Feezell, Daniel F.; Busani, Tito L.

    2016-09-01

    In this study we introduce Gallium Nitride (GaN) nanowire (NW) as high aspect ratio tip with excellent durability for nano-scale metrology. GaN NWs have superior mechanical property and young modulus compare to commercial Si and Carbon tips which results in having less bending issue during measurement. The GaN NWs are prepared via two different methods: i) Catalyst-free selected area growth, using Metal Organic Chemical Vapor Deposition (MOCVD), ii) top-down approach by employing Au nanoparticles as the mask material in dry-etch process. To achieve small diameter tips, the semipolar planes of the NWs grown by MOCVD are etched using AZ400k. The diameter of the NWs fabricated using the top down process is controlled by using different size of nanoparticles and by Inductively Coupled Plasma etching. NWs with various diameters were manipulated on Si cantilevers using Focus Ion Beam (FIB) to make tips for AFM measurement. A Si (110) substrate containing nano-scale grooves with vertical 900 walls were used as a sample for inspection. AFM measurements were carried out in tapping modes for both types of nanowires (top-down and bottom-up grown nanowires) and results are compared with conventional Si and carbon nanotube tips. It is shown our fabricated tips are robust and have improved edge resolution over conventional Si tips. GaN tips made with NW's fabricated using our top down method are also shown to retain the gold nanoparticle at tip, which showed enhanced field effects in Raman spectroscopy.

  10. High aspect ratio silicon nanowires control fibroblast adhesion and cytoskeleton organization.

    Science.gov (United States)

    Andolfi, Laura; Murello, Anna; Cassese, Damiano; Ban, Jelena; Dal Zilio, Simone; Lazzarino, Marco

    2017-04-18

    Cell-cell and cell-matrix interactions are essential to the survival and proliferation of most cells, and are responsible for triggering a wide range of biochemical pathways. More recently, the biomechanical role of those interactions was highlighted, showing, for instance, that adhesion forces are essential for cytoskeleton organization. Silicon nanowires (Si NWs) with their small size, high aspect ratio and anisotropic mechanical response represent a useful model to investigate the forces involved in the adhesion processes and their role in cellular development. In this work we explored and quantified, by single cell force spectroscopy (SCFS), the interaction of mouse embryonic fibroblasts with a flexible forest of Si NWs. We observed that the cell adhesion forces are comparable to those found on collagen and bare glass coverslip, analogously the membrane tether extraction forces are similar to that on collagen but stronger than that on bare flat glass. Cell survival did not depend significantly on the substrate, although a reduced proliferation after 36 h was observed. On the contrary both cell morphology and cytoskeleton organization revealed striking differences. The cell morphology on Si-NW was characterized by a large number of filopodia and a significant decrease of the cell mobility. The cytoskeleton organization was characterized by the absence of actin fibers, which were instead dominant on collagen and flat glass support. Such findings suggest that the mechanical properties of disordered Si NWs, and in particular their strong asymmetry, play a major role in the adhesion, morphology and cytoskeleton organization processes. Indeed, while adhesion measurements by SCFS provide out-of-plane forces values consistent with those measured on conventional substrates, weaker in-plane forces hinder proper cytoskeleton organization and migration processes.

  11. Jet noise of high aspect-ratio rectangular nozzles with application to pneumatic high-lift devices

    Science.gov (United States)

    Munro, Scott Edward

    Circulation control wings are a type of pneumatic high-lift device that have been extensively researched as to their aerodynamic benefits. However, there has been little research into the possible airframe noise reduction benefits. The key element of noise is the jet noise associated with the jet sheet emitted from the blowing slot. This jet sheet is essentially a high aspect-ratio rectangular jet. This study directly compared far-field noise emissions from a state-of-the-art circulation control wing high lift configuration, and a conventional wing also configured for high lift. Results indicated that a circulation control wing had a significant acoustic advantage over a conventional wing for identical lift performance. A high aspect-ratio nozzle was fabricated to study the general characteristics of high aspect-ratio jets with aspect ratios from 100 to 3000. The results of this study provided the basic elements in understanding how to reduce the noise from a circulation control wing. High aspect-ratio nozzle results showed that the jet noise of this type of jet was proportional to the 8th power of the jet velocity. It was also found that the jet noise was proportional to the slot height to the 3/2 power and slot width to the 1/2 power. Fluid dynamic experiments were also performed on the high aspect-ratio nozzle. Single hot-wire experiments indicated that the jet exhaust from the high aspect-ratio nozzle was similar to a 2-d turbulent jet. Two-wire space-correlation experiments were performed to attempt to find a relationship between the slot height of the jet and the length-scale of the flow noise generating turbulence structure. The turbulent eddy convection velocity was also calculated, and was found to vary with the local centerline velocity, and also as a function of the frequency of the eddy.

  12. BisGMA/TEGDMA dental composite containing high aspect-ratio hydroxyapatite nanofibers

    Science.gov (United States)

    Chen, Liang; Yu, Qingsong; Wang, Yong; Li, Hao

    2011-01-01

    Objectives The objectives of this study are to investigate the properties of high aspect-ratio hydroxyapatite (HAP) nanofibers and the reinforcing effect of such fibers on bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental resins (without silica microparticle filler) and dental composites (with silica microparticle filler) with various mass fractions (loading rates). Methods HAP nanofibers were synthesized using a wet-chemical method and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). Biaxial flexural strength (BFS) of the HAP nanofibers reinforced dental resins without any microsized filler and dental composites with silica microparticle filler was tested and analysis of variance (ANOVA) was used for the statistically analysis of acquired data. The morphology of fracture surface of tested dental composite samples was examined by SEM. Results The HAP nanofibers with aspect-ratios of 600 to 800 can be successfully fabricated with a simple wet-chemical method in aqueous solution. Impregnation of small mass fractions of the HAP nanofibers (5 wt% or 10 wt%) into the BisGMA/TEGDMA dental resins or impregnation of small mass fractions of the HAP nanofibers (2 wt% or 3 wt%) into the dental composites can substantially improve the biaxial flexural strength of the resulting dental resins and composites. A percolation threshold of HAP nanofibers, beyond which more nanofibers will no longer further increase the mechanical properties of dental composites containing HAP nanofibers, was observed for the dental composites with or without silica microparticle filler. Our mechanical testing and fractographic analysis indicated that the relatively good dispersion of HAP nanofibers at low mass fraction is the key reason for the significantly improved biaxial flexural strength, while higher mass fraction of HAP nanofibers tends to lead to bundles that cannot effectively

  13. Fabrication of micro-pin array with high aspect ratio on stainless steel using nanosecond laser beam machining

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Se Won [School of Mechanical and Aerospace Engineering, Seoul National University, Gwanak 599 Gwanak-ro, Gwanak-Gu, Seoul, 151-744 (Korea, Republic of); Shin, Hong Shik, E-mail: shinhs05@ut.ac.kr [Department of Energy System Engineering, Korea National University of Transportation, Chungju, Chungbuk, 380-702 (Korea, Republic of); Chu, Chong Nam [School of Mechanical and Aerospace Engineering, Seoul National University, Gwanak 599 Gwanak-ro, Gwanak-Gu, Seoul, 151-744 (Korea, Republic of)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer A high aspect ratio micro-pin array was fabricated by laser beam machining using the piling of a recast layer. Black-Right-Pointing-Pointer The recast layer could be piled due to the chromium oxide with high surface tension and viscosity of chromium oxide. Black-Right-Pointing-Pointer The machining characteristics for a high aspect ratio micro-pin array were investigated according to laser beam parameters. Black-Right-Pointing-Pointer Experiments for attaching force relative to the surface roughness of the subject plane were carried out. Black-Right-Pointing-Pointer The developed micro-pin array was successfully attached to vertical wall. - Abstract: In this paper, a micro-pin array with a high aspect ratio was fabricated on AISI 304 using laser beam ablation for attachment to a vertical wall. In recent times, there has been research in various fields, including robotics and bio-MEMS, regarding attachment to vertical walls, and micro-pin arrays may offer the best solution. For vertical wall attachment, the micro-pin should have a high aspect ratio, long length, and sharp tip. The recast layer could be piled due to the chromium oxide with high surface tension and viscosity of chromium oxide, and it composed the micro-pins with high aspect ratio. X-ray photoelectron spectroscopy (XPS) was used to identify the characteristics of the piled recast layer. The machining characteristics for a high aspect ratio micro-pin array were investigated according to laser beam machining parameters. In addition, experiments for attaching force relative to the surface roughness of the subject plane were carried out.

  14. Fabrication of Ni stamp with high aspect ratio, two-leveled, cylindrical microstructures using dry etching and electroplating

    DEFF Research Database (Denmark)

    Petersen, Ritika Singh; Keller, Stephan Sylvest; Hansen, Ole;

    2015-01-01

    We describe a process for the fabrication of a Ni stamp that is applied to the microstructuring of polymers by hot embossing. The target devices are microcontainers that have a potential application in oral drug delivery. Each container is a 3D, cylindrical, high aspect ratio microstructure...

  15. Highly Manufacturable Deep (Sub-Millimeter) Etching Enabled High Aspect Ratio Complex Geometry Lego-Like Silicon Electronics

    KAUST Repository

    Ghoneim, Mohamed T.

    2017-02-01

    A highly manufacturable deep reactive ion etching based process involving a hybrid soft/hard mask process technology shows high aspect ratio complex geometry Lego-like silicon electronics formation enabling free-form (physically flexible, stretchable, and reconfigurable) electronic systems.

  16. Fabrication of novel AFM probe with high-aspect-ratio ultra-sharp three-face silicon nitride tips

    NARCIS (Netherlands)

    Vermeer, Rolf; Berenschot, Erwin; Sarajlic, Edin; Tas, Niels; Jansen, Henri

    2014-01-01

    In this paper we present the wafer-scale fabrication of molded AFM probes with high aspect ratio ultra-sharp three-plane silicon nitride tips. Using (111) silicon wafers a dedicated process is developed to fabricate molds in the silicon wafer that have a flat triangular bottom surface enclosed by th

  17. High aspect ratio micro tool manufacturing for polymer replication using mu EDM of silicon, selective etching and electroforming

    DEFF Research Database (Denmark)

    Tosello, Guido; Bissacco, Giuliano; Tang, Peter Torben

    2008-01-01

    Mass fabrication of polymer micro components with high aspect ratio micro-structures requires high performance micro tools allowing the use of low cost replication processes such as micro injection moulding. In this regard an innovative process chain, based on a combination of micro electrical di...

  18. High precision and high aspect ratio laser drilling: challenges and solutions

    Science.gov (United States)

    Uchtmann, Hermann; He, Chao; Gillner, Arnold

    2016-03-01

    Laser drilling is a very versatile tool to produce high accuracy bores in small and large geometries using different technologies. In large and deep hole drilling laser drilling can be found in drilling cooling holes into turbomachinery components such as turbine blades. In micro drilling, the technology is used for the generation of nozzles and filters. However, especially in macro drilling, the process often causes microstructure changes and induces defects such as recast layers and cracks. The defects are caused by the melt dominated drilling process by using pulse durations in the range of some 100 μm up to a few ms. A solution of this problem is the use of ultrashort pulsed laser radiation with pulse durations in the range of some 100 fs up to a few ps, however with the disadvantage of long drilling times. Thus, the aim of this work is to combine the productive process by using ms pulsed fiber laser radiation with subsequent ablation of existing recast layers at the hole wall by using ultrashort pulsed laser radiation. By using fast scanning techniques the recast layer can be avoided almost completely. With a similar technology also very small hole can be produced. Using a rotating dove prism a circular oscillation of the laser spots is performed and holes are drilled at intervals in 1 mm thick stainless steel (1.4301) by ultra-short laser pulses of 7 ps at 515 nm. The formation of hole and the behavior of energy deposition differ from other drilling strategies due to the helical revolution. The temporal evolution of the hole shape is analyzed by means of SEM techniques from which three drilling phases can be distinguished.

  19. The field emission properties of high aspect ratio diamond nanocone arrays fabricated by focused ion beam milling

    Directory of Open Access Journals (Sweden)

    Z.L. Wang, Q. Wang, H.J. Li, J.J. Li, P. Xu, Q. Luo, A.Z. Jin, H.F. Yang and C.Z. Gu

    2005-01-01

    Full Text Available High aspect ratio diamond nanocone arrays are formed on freestanding diamond film by means of focused ion beam (FIB milling technology and hot-filament chemical vapor deposition (HFCVD method. The structure and phase purity of an individual diamond nanocone are characterized by scanning electron microscopy (SEM and micro-Raman spectroscopy. The result indicates that the diamond cones with high aspect ratio and small tip apex radius can be obtained by optimizing the parameters of FIB milling and diamond growth. The diamond nanocone arrays were also used to study the electron field emission properties and electric field shielding effect, finding high emission current density, low threshold and weak shielding effect, all attributable to the high field enhancement factor and suitable cone density of the diamond nanocone emitter

  20. High aspect ratio microstructuring of transparent dielectrics using femtosecond laser pulses: method for optimization of the machining throughput

    Science.gov (United States)

    Hendricks, F.; der Au, J. Aus; Matylitsky, V. V.

    2014-10-01

    High average power, high repetition rate femtosecond lasers with μJ pulse energies are increasingly used for material processing applications. The unique advantage of material processing with sub-picosecond lasers is efficient, fast and localized energy deposition, which leads to high ablation efficiency and accuracy in nearly all kinds of solid materials. This work focuses on the machining of high aspect ratio structures in transparent dielectrics, in particular chemically strengthened Xensation™ glass from Schott using multi-pass ablative material removal. For machining of high aspect ratio structures, among others needed for cutting applications, a novel method to determine the best relation between kerf width and number of overscans is presented. The importance of this relation for optimization of the machining throughput will be demonstrated.

  1. Numerical studies of the reversed-field pinch at high aspect ratio

    Science.gov (United States)

    Sätherblom, H.-E.; Drake, J. R.

    1998-10-01

    The reversed field pinch (RFP) configuration at an aspect ratio of 8.8 is studied numerically by means of the three-dimensional magnetohydrodynamic code DEBS [D. D. Schnack et al., J. Comput. Phys. 70, 330 (1987)]. This aspect ratio is equal to that of the Extrap T1 experiment [S. Mazur et al., Nucl. Fusion 34, 427 (1994)]. A numerical study of a RFP with this level of aspect ratio requires extensive computer achievements and has hitherto not been performed. The results are compared with previous studies [Y. L. Ho et al., Phys. Plasmas 2, 3407 (1995)] of lower aspect ratio RFP configurations. In particular, an evaluation of the extrapolation to the aspect ratio of 8.8 made in this previous study shows that the extrapolation of the spectral spread, as well as most of the other findings, are confirmed. An important exception, however, is the magnetic diffusion coefficient, which is found to decrease with aspect ratio. Furthermore, an aspect ratio dependence of the magnetic energy and of the helicity of the RFP is found.

  2. Patterning of periodic high-aspect-ratio nanopores in anatase titanium dioxide from titanium fluoride hydrolysis.

    Science.gov (United States)

    Tevis, Ian D; Stupp, Samuel I

    2011-05-01

    We report straight pores in titanium dioxide produced by a pattern transfer method with titanium fluoride hydrolysis. The resulting films on fluorine-doped tin oxide had pores with diameters of 30 nm and depths of 500 nm, corresponding to aspect ratios of 1:17.

  3. Key Techniques on Preparing High Aspect Ratio Micro and Nano Structures

    DEFF Research Database (Denmark)

    Jian, Zhao; Lianhe, Dong; Xiaoli, Zhu

    2016-01-01

    effectively. The mechanism of action between NaCl and HSQ was analyzed. The collapse and adhesion of resist structure due to the effect of gas-liquid interfacial capillary surface tension were suppressed by the CO2 supercritical drying method. Large-area dense nano-structures with the aspect ratio of 12...

  4. Nanoimprinting ultrasmall and high-aspect-ratio structures by using rubber-toughened UV cured epoxy resist

    Science.gov (United States)

    Shin, Young Jae; Wu, Yi-Kuei; Guo, L. Jay

    2013-06-01

    A simple and robust scheme is proposed for the fabrication of nanoscale (20 nm line width) and high-aspect-ratio (9:1) structures by using modulus-tunable UV curable epoxy resists. Additionally, the ability to control the Young’s modulus of the imprinted material from hard to rigiflex using these epoxy resists is demonstrated. The physical properties of the new epoxy resists were controlled by adjusting the ratio of bisphenol F-type epoxy resin and acrylonitrile-butadiene rubber-based epoxy resin in the formulation of the resist. The mechanical properties of the resist were tuned to obtain various aspect ratios as well as mold flexibility for conformal contact over non-planar surfaces and large areas. In order to reduce the line width of the imprinted patterns, a process to conformally coat the mold structure by atomic layer deposition of alumina was also developed. Narrow lines with high-aspect-ratio features and with very low defect density were achieved via the new approach and the high mechanical strength of the new resist formulation.

  5. Nanofabrication of low extinction coefficient and high-aspect-ratio Si structures for metaphotonic applications

    Science.gov (United States)

    Lee, JeongYub; Song, Byonggwon; Kim, Jaekwan; Lee, Chang-Won; Han, Seunghoon; Baik, Chan-Wook; Jeong, Heejeong; Kim, Yongsung; Lee, Chang Seung

    2016-09-01

    We investigated forming of high refractive index (n), low extinction coefficient (k) of Si dielectrics in visible wavelength ranges. To decrease k, pulsed green laser annealing (GLA) with line beam of a 532-nm wavelength was applied in this study for homogeneous melting. By AFM, XRD and TEM analysis, we examined the defect reduction in various conditions during poly-crystallization. We achieved dielectric nanostructures having optical properties of n>4.2, k<0.06 at 550 nm wavelength and fine pitches down to 40 nm (aspect ratio 3:1) and 130 nm (aspect ratio 7:1) with +/-5% size accuracy. Finally, we realized optical metasurfaces for optical band filters, flat lens and beam deflectors.

  6. High aspect ratio tungsten grating on ultrathin Si membranes for extreme UV lithography

    Science.gov (United States)

    Peng, Xinsheng; Ying, Yulong

    2016-09-01

    Extreme ultraviolet lithography is one of the modern lithography tools for high-volume manufacturing with 22 nm resolution and beyond. But critical challenges exist to the design and fabrication of large-scale and highly efficient diffraction transmission gratings, significantly reducing the feature sizes down to 22 nm and beyond. To achieve such a grating, the surface flatness, the line edge roughness, the transmission efficiency and aspect ratio should be improved significantly. Delachat et al (2015 Nanotechnology 26 108262) develop a full process to fabricate a tungsten diffraction grating on an ultrathin silicon membrane with higher aspect ratio up to 8.75 that met all the aforementioned requirements for extreme ultraviolet lithography. This process is fully compatible with standard industrial extreme ultraviolet lithography.

  7. High aspect ratio tungsten grating on ultrathin Si membranes for extreme UV lithography.

    Science.gov (United States)

    Peng, Xinsheng; Ying, Yulong

    2016-09-02

    Extreme ultraviolet lithography is one of the modern lithography tools for high-volume manufacturing with 22 nm resolution and beyond. But critical challenges exist to the design and fabrication of large-scale and highly efficient diffraction transmission gratings, significantly reducing the feature sizes down to 22 nm and beyond. To achieve such a grating, the surface flatness, the line edge roughness, the transmission efficiency and aspect ratio should be improved significantly. Delachat et al (2015 Nanotechnology 26 108262) develop a full process to fabricate a tungsten diffraction grating on an ultrathin silicon membrane with higher aspect ratio up to 8.75 that met all the aforementioned requirements for extreme ultraviolet lithography. This process is fully compatible with standard industrial extreme ultraviolet lithography.

  8. Deposition of a-C:H films on inner surface of high-aspect-ratio microchannel

    Science.gov (United States)

    Hirata, Yuki; Choi, Junho

    2016-08-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared on inner surface of 100-μm-width microchannel by using a bipolar-type plasma based ion implantation and deposition. The microchannel was fabricated using a silicon plate, and two kinds of microchannels were prepared, namely, with a bottom layer (open at one end) and without a bottom layer (open at both ends). The distribution of thickness and hardness of films was evaluated by SEM and nanoindentation measurements, respectively, and the microstructures of films were evaluated by Raman spectroscopy. Furthermore, the behavior of ions and radicals was analyzed simultaneously by combining the calculation methods of Particle-In-Cell/Monte Carlo Collision and Direct Simulation Monte Carlo to investigate the coating mechanism for the microchannel. It was found that the film thickness decreased as the depth of the coating position increased in the microchannels where it is open at one end. The uniformity of the film thickness improved by increasing the negative pulse voltage because ions can arrive at the deeper part of the microchannel. In addition, the hardness increased as the depth of the coating position increased. This is because the radicals do not arrive at the deeper part of the microchannel, and the incident proportion of ions relative to that of radicals increases, resulting in a high hardness due to the amorphization of the film. The opening area of the microchannel where the aspect ratio is very small, radicals dominate the incident flux, whereas ions prevail over radicals above an aspect ratio of about 7.5. On the other hand, in the microchannels that are open at both ends, there were great improvements in uniformity of the film thickness, hardness, and the film structure. The a-C:H films were successfully deposited on the entire inner surface of a microchannel with an aspect ratio of 20.

  9. Dispersion and Polarization of Surface Waves Trapped in High Aspect Ratio Electrode Arrays

    DEFF Research Database (Denmark)

    Laude, Vincent; Dühring, Maria Bayard; Moubchir, Hanane

    2007-01-01

    .Phys., 90(5):2492, 2001; Appl. Phys. Lett., 89:083515, 2006.) an experimental and theoretical analysis of the transduction of SAW under a metallic array of electrodes with a large aspect ratio on a piezoelectric substrate, whereby allowing the electrode height to become larger than one wavelength....... The multimode character of SAW propagation was observed and the explicit dependence of the SAW velocities as a function of the electrode height was obtained experimentally. Up to a 10-fold slowing of surface waves was observed, with the phase velocity dropping from 4000 m/s down to 450 m/s. We present...

  10. Hot embossing of photonic crystal polymer structures with a high aspect ratio

    DEFF Research Database (Denmark)

    Schelb, Mauno; Vannahme, Christoph; Kolew, Alexander;

    2011-01-01

    Hot embossing is a promising approach for mass production of photonic crystal structures. This paper describes the fabrication of a replication tool for two-dimensional photonic crystal patterns and its replication in substrates of poly(methylmethacrylate) (PMMA) and cyclic olefin copolymer (COC......). A nickel tool for the replication of structures with lateral dimensions of 110 nm and heights of approximately 370 nm is fabricated via electroplating of a nanostructured sample resulting in an aspect ratio of approximately 3.5. The structures are subsequently hot embossed into PMMA and COC substrates....

  11. Highly sensitive glucose biosensor based on Au-Ni coaxial nanorod array having high aspect ratio.

    Science.gov (United States)

    Hsu, Che-Wei; Wang, Gou-Jen

    2014-06-15

    An effective glucose biosensor requires a sufficient amount of GOx immobilizing on the electrode surface. An electrode of a 3D nanorod array, having a larger surface-to-volume ratio than a 2D nanostructure, can accommodate more GOx molecules to immobilize onto the surface of the nanorods. In this study, a highly sensitive Au-Ni coaxial nanorod array electrode fabricated through the integration of nano electroforming and immersion gold (IG) method for glucose detection was developed. The average diameter of the as-synthesized Ni nanorods and that of the Au-Ni nanorods were estimated to be 150 and 250 nm, respectively; both had a height of 30 μm. The aspect ratio was 120. Compared to that of a flat Au electrode, the effective sensing area was enhanced by 79.8 folds. Actual glucose detections demonstrated that the proposed Au-Ni coaxial nanorod array electrode could operate in a linear range of 27.5 μM-27.5mM with a detection limit of 5.5μM and a very high sensitivity of 769.6 μA mM(-1)cm(-2). Good selectivity of the proposed sensing device was verified by sequential injections of uric acid (UA) and ascorbic acid (AA). Long-term stability was examined through successive detections over a period of 30 days.

  12. Subsonic and transonic pressure measurements on a high-aspect-ratio supercritical-wing model with oscillating control surfaces

    Science.gov (United States)

    Sandford, M. C.; Ricketts, R. H.; Watson, J. J.

    1981-01-01

    A high aspect ratio supercritical wing with oscillating control surfaces is described. The semispan wing model was instrumented with 252 static orifices and 164 in situ dynamic pressure gases for studying the effects of control surface position and sinusoidal motion on steady and unsteady pressures. Data from the present test (this is the second in a series of tests on this model) were obtained in the Langley Transonic Dynamics Tunnel at Mach numbers of 0.60 and 0.78 and are presented in tabular form.

  13. Designs and processes toward high-aspect-ratio nanostructures at the deep nanoscale: unconventional nanolithography and its applications

    Science.gov (United States)

    Lee, Sori; Park, Byeonghak; Kim, Jun Sik; Kim, Tae-il

    2016-11-01

    The patterning of high-resolution-featured deep-nanoscale structures with a high aspect ratio (AR) has received increasing attention in recent years as a promising technique for a wide range of applications, including electrical, optical, mechanical and biological systems. Despite extensive efforts to develop viable nanostructure fabrication processes, a superior technique enabling defect-free, high-resolution control over a large area is still required. In this review, we focus on recent important advances in the designs and processes of high-resolution nanostructures possessing a high AR, including hierarchical and 3D patterns. The unique applications of these materials are also discussed.

  14. Large-scale high aspect ratio Al-doped ZnO nanopillars arrays as anisotropic metamaterials

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Panah, Mohammad Esmail Aryaee

    2017-01-01

    High aspect ratio free-standing Al-doped ZnO (AZO) nanopillars and nanotubes were fabricated using a combination of advanced reactive ion etching and atomic layer deposition (ALD) techniques. Prior to the pillar and tube fabrication, AZO layers were grown on flat silicon and glass substrates...... plasma frequency. During pillar fabrication, AZO conformally passivates the silicon template, which is characteristic of typical ALD growth conditions. The last step of fabrication is heavily dependent on the selective chemistry of the SF6 plasma. It was shown that silicon between AZO structures can...

  15. Shrink film patterning by craft cutter: complete plastic chips with high resolution/high-aspect ratio channel.

    Science.gov (United States)

    Taylor, Douglas; Dyer, David; Lew, Valerie; Khine, Michelle

    2010-09-21

    This paper presents a rapid, ultra-low-cost approach to fabricate microfluidic devices using a polyolefin shrink film and a digital craft cutter. The shrinking process (with a 95% reduction in area) results in relatively uniform and consistent microfluidic channels with smooth surfaces, vertical sidewalls, and high aspect ratio channels with lateral resolutions well beyond the tool used to cut them. The thermal bonding of the layers results in strongly bonded devices. Complex microfluidic designs are easily designed on the fly and protein assays are also readily integrated into the device. Full device characterization including channel consistency, optical properties, and bonding strength are assessed in this technical note.

  16. Fabrication of high-aspect-ratio polymer microstructures and hierarchical textures using carbon nanotube composite master molds.

    Science.gov (United States)

    Copic, Davor; Park, Sei Jin; Tawfick, Sameh; De Volder, Michael F L; Hart, A John

    2011-05-21

    Scalable and cost effective patterning of polymer structures and their surface textures is essential to engineer material properties such as liquid wetting and dry adhesion, and to design artificial biological interfaces. Further, fabrication of high-aspect-ratio microstructures often requires controlled deep-etching methods or high-intensity exposure. We demonstrate that carbon nanotube (CNT) composites can be used as master molds for fabrication of high-aspect-ratio polymer microstructures having anisotropic nanoscale textures. The master molds are made by growth of vertically aligned CNT patterns, capillary densification of the CNTs using organic solvents, and capillary-driven infiltration of the CNT structures with SU-8. The composite master structures are then replicated in SU-8 using standard PDMS transfer molding methods. By this process, we fabricated a library of replicas including vertical micro-pillars, honeycomb lattices with sub-micron wall thickness and aspect ratios exceeding 50:1, and microwells with sloped sidewalls. This process enables batch manufacturing of polymer features that capture complex nanoscale shapes and textures, while requiring only optical lithography and conventional thermal processing.

  17. Millijoule femtosecond micro-Bessel beams for ultra-high aspect ratio machining.

    Science.gov (United States)

    Mitra, Sambit; Chanal, Margaux; Clady, Raphaël; Mouskeftaras, Alexandros; Grojo, David

    2015-08-20

    We report on a functional experimental design for Bessel beam generation capable of handling high-energy ultrashort pulses (up to 1.2 mJ per pulse of 50 fs duration). This allows us to deliver intensities exceeding the breakdown threshold for air or any dielectric along controlled micro-filaments with lengths exceeding 4 mm. It represents an unprecedented upscaling in comparison to recent femtosecond Bessel beam micromachining experiments. We produce void microchannels through glass substrates to demonstrate that aspect ratios exceeding 1200∶1 can be achieved by using single high-intensity pulses. This demonstration must lead to new methodologies for deep-drilling and high-speed cutting applications.

  18. Fabrication of High Aspect Ratio Micro-Penning-Malmberg Gold Plated Silicon Trap Arrays

    CERN Document Server

    Narimannezhad, Alireza; Weber, Marc H; Lynn, Kelvin G

    2013-01-01

    Acquiring a portable high density charged particles trap might consist of an array of micro-Penning-Malmberg traps (microtraps) with substantially lower end barriers potential than conventional Penning-Malmberg traps [1]. We report on the progress of the fabrication of these microtraps designed for antimatter storage such as positrons. The fabrication of large length to radius aspect ratio (1000:1) microtrap arrays involved advanced techniques including photolithography, deep reactive ion etching (DRIE) of silicon wafers to achieve through-vias, gold sputtering of the wafers on the surfaces and inside the vias, and thermal compression bonding of the wafers. This paper describes the encountered issues during fabrication and addresses geometry errors and asymmetries. In order to minimize the patch effects on the lifetime of the trapped positrons, the bonded stacks were gold electroplated to achieve a uniform gold surface. We show by simulation and analytical calculation that how positrons confinement time depen...

  19. High aspect ratio iridescent three-dimensional metal–insulator–metal capacitors using atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Burke, Micheal, E-mail: micheal.burke@tyndall.ie; Blake, Alan; Djara, Vladimir; O' Connell, Dan; Povey, Ian M.; Cherkaoui, Karim; Monaghan, Scott; Scully, Jim; Murphy, Richard; Hurley, Paul K.; Pemble, Martyn E.; Quinn, Aidan J., E-mail: aidan.quinn@tyndall.ie [Tyndall National Institute, University College Cork, Cork (Ireland)

    2015-01-01

    The authors report on the structural and electrical properties of TiN/Al{sub 2}O{sub 3}/TiN metal–insulator–metal (MIM) capacitor structures in submicron three-dimensional (3D) trench geometries with an aspect ratio of ∼30. A simplified process route was employed where the three layers for the MIM stack were deposited using atomic layer deposition (ALD) in a single run at a process temperature of 250 °C. The TiN top and bottom electrodes were deposited via plasma-enhanced ALD using a tetrakis(dimethylamino)titanium precursor. 3D trench devices yielded capacitance densities of 36 fF/μm{sup 2} and quality factors >65 at low frequency (200 Hz), with low leakage current densities (<3 nA/cm{sup 2} at 1 V). These devices also show strong optical iridescence which, when combined with the covert embedded capacitance, show potential for system in package (SiP) anticounterfeiting applications.

  20. Photoablation characteristics of novel polyimides synthesized for high-aspect-ratio excimer laser LIGA process

    Science.gov (United States)

    Yang, Chii-Rong; Hsieh, Yu-Sheng; Hwang, Guang-Yeu; Lee, Yu-Der

    2004-04-01

    The photoablation properties of two soluble polyimides DMDB/6FDA and OT/6FDA with thicknesses of over 300 µm, synthesized by the polycondensation of a hexafluoropropyl group contained in a dianhydride with two kinds of diamines, are investigated using a 248 nm krypton fluoride (KrF) laser. The incorporation of the hexafluoropropyl group into the chemical structure gives these two polyimides higher etching rates than Kapton (a commercial polyimide film which is difficult to dissolve). The etching rates of synthesized polyimides are about 0.1-0.5 µm/pulse over a fluence range of 0.25-2.25 J cm-2. The photothermal mechanism for DMDB/6FDA contributes about 19% of etching depth at a laser fluence of 0.82 J cm-2. Moreover, the number of laser pulses seriously affects the taper angle of microstructures, especially at low fluence. Near-vertical side-wall structures can be built at high fluence (~2 J cm-2). Fresnel patterns with a thickness of 300 µm and a linewidth of 10 µm were fabricated, with an attainable aspect ratio of around 30. After photoablation, the complementary metallic microstructures were also fabricated by a sequential electroplating procedure. Then, those two new polyimides could be dissolved easily in most common solvents (such as THF, DMSO, NMP and DMF). These results indicate that these two soluble polyimides are highly suitable for use in the KrF laser LIGA process.

  1. High-aspect-ratio photoresist processing for fabrication of high resolution and thick micro-windings

    Science.gov (United States)

    Anthony, Ricky; Laforge, Elias; Casey, Declan P.; Rohan, James F.; O'Mathuna, Cian

    2016-10-01

    DC winding losses remain a major roadblock in realizing high efficiency micro-magnetic components (inductors/transformers). This paper reports an optimized photoresist process using negative tone and acrylic based THB-151N (from JSR Micro), to achieve one of the highest aspect ratio (17:1) and resolution (~5 µm) resist patterns for fabrication of thick (~80 µm) micro-winding using UV lithography. The process was optimized to achieve photoresist widths from 5 µm to 20 µm with resist thickness of ~85 µm in a single spin step. Unlike SU-8, this resist can be readily removed and shows a near-vertical (~91°) electroplated Cu side-wall profile. Moreover, the high resolution compared to available resist processes enables a further reduction in the footprint area and can potentially increase the number of winding thereby increasing the inductance density for micro-magnetic components. Resistance measurements of electroplated copper winding of air-core micro-inductors within the standard 0402 size (0.45 mm2 footprint area) suggested a 42% decrease in resistance (273 mΩ-159 mΩ) with the increase in electroplated Cu thickness (from 50 µm to 80 µm). Reduction of the spacings (from 10 µm to 5 µm) enabled further miniaturisation of the device footprint area (from 0.60 mm2 to 0.45 mm2) without significant increase in resistance.

  2. Jet-Surface Interaction Noise from High-Aspect Ratio Nozzles: Test Summary

    Science.gov (United States)

    Brown, Clifford; Podboy, Gary

    2017-01-01

    Noise and flow data have been acquired for a 16:1 aspect ratio rectangular nozzle exhausting near a simple surface at the NASA Glenn Research Center as part of an ongoing effort to understand, model, and predict the noise produced by current and future concept aircraft employing a tightly integrated engine airframe designs. The particular concept under consideration in this experiment is a blended-wing-body airframe powered by a series of electric fans exhausting through slot nozzle over an aft deck. The exhaust Mach number and surface length were parametrically varied during the test. Far-field noise data were acquired for all nozzle surface geometries and exhaust flow conditions. Phased-array noise source localization data and in-flow pressure data were also acquired for a subset of the isolated (no surface) and surface configurations; these measurements provide data that have proven useful for modeling the jet-surface interaction noise source and the surface effect on the jet-mixing noise in round jets. A summary of the nozzle surface geometry, flow conditions tested, and data collected are presented.

  3. HIGH ASPECT RATIO ION EXCHANGE RESIN BED - HYDRAULIC RESULTS FOR SPERICAL RESIN BEADS

    Energy Technology Data Exchange (ETDEWEB)

    Duignan, M; Charles Nash, C; Timothy Punch, T

    2007-09-27

    A principal role of the DOE Savannah River Site is to safely dispose of a large volume of liquid nuclear waste held in many storage tanks. An in-tank ion exchange unit is being considered for cesium removal to accelerate waste processing. This unit is planned to have a relatively high bed height to diameter ratio (10:1). Complicating the design is the need to cool the ion exchange media; therefore, the ion exchange column will have a central cooling core making the flow path annular. To separate cesium from waste the media being considered is made of resorcinol formaldehyde resin deposited on spherical plastic beads and is a substitute for a previously tested resin made of crystalline silicotitanate. This spherical media not only has an advantage of being mechanically robust, but, unlike its predecessor, it is also reusable, that is, loaded cesium can be removed through elution and regeneration. Resin regeneration leads to more efficient operation and less spent resin waste, but its hydraulic performance in the planned ion exchange column was unknown. Moreover, the recycling process of this spherical resorcinol formaldehyde causes its volume to significantly shrink and swell. To determine the spherical media's hydraulic demand a linearly scaled column was designed and tested. The waste simulant used was prototypic of the wastes' viscosity and density. This paper discusses the hydraulic performance of the media that will be used to assist in the design of a full-scale unit.

  4. Filling high aspect ratio trenches by superconformal chemical vapor deposition: Predictive modeling and experiment

    Science.gov (United States)

    Wang, Wenjiao B.; Abelson, John R.

    2014-11-01

    Complete filling of a deep recessed structure with a second material is a challenge in many areas of nanotechnology fabrication. A newly discovered superconformal coating method, applicable in chemical vapor deposition systems that utilize a precursor in combination with a co-reactant, can solve this problem. However, filling is a dynamic process in which the trench progressively narrows and the aspect ratio (AR) increases. This reduces species diffusion within the trench and may drive the component partial pressures out of the regime for superconformal coating. We therefore derive two theoretical models that can predict the possibility for filling. First, we recast the diffusion-reaction equation for the case of a sidewall with variable taper angle. This affords a definition of effective AR, which is larger than the nominal AR due to the reduced species transport. We then derive the coating profile, both for superconformal and for conformal coating. The critical (most difficult) step in the filling process occurs when the sidewalls merge at the bottom of the trench to form the V shape. Experimentally, for the Mg(DMADB)2/H2O system and a starting AR = 9, this model predicts that complete filling will not be possible, whereas experimentally we do obtain complete filling. We then hypothesize that glancing-angle, long-range transport of species may be responsible for the better than predicted filling. To account for the variable range of species transport, we construct a ballistic transport model. This incorporates the incident flux from outside the structure, cosine law re-emission from surfaces, and line-of-sight transport between internal surfaces. We cast the transport probability between all positions within the trench into a matrix that represents the redistribution of flux after one cycle of collisions. Matrix manipulation then affords a computationally efficient means to determine the steady-state flux distribution and growth rate for a given taper angle. The

  5. The Space-Time CESE Method Applied to Viscous Flow Computations with High-Aspect Ratio Triangular or Tetrahedral Meshes

    Science.gov (United States)

    Chang, Chau-Lyan; Venkatachari, Balaji

    2016-11-01

    Flow physics near the viscous wall is intrinsically anisotropic in nature, namely, the gradient along the wall normal direction is much larger than that along the other two orthogonal directions parallel to the surface. Accordingly, high aspect ratio meshes are employed near the viscous wall to capture the physics and maintain low grid count. While such arrangement works fine for structured-grid based methods with dimensional splitting that handles derivatives in each direction separately, similar treatments often lead to numerical instability for unstructured-mesh based methods when triangular or tetrahedral meshes are used. The non-splitting treatment of near-wall gradients for high-aspect ratio triangular or tetrahedral elements results in an ill-conditioned linear system of equations that is closely related to the numerical instability. Altering the side lengths of the near wall tetrahedrons in the gradient calculations would make the system less unstable but more dissipative. This research presents recent progress in applying numerical dissipation control in the space-time conservation element solution element (CESE) method to reduce or alleviate the above-mentioned instability while maintaining reasonable solution accuracy.

  6. Single phase flow characteristics of FC-72 and ethanol in high aspect ratio rectangular mini- and micro-channels

    Science.gov (United States)

    Wang, Yuan; Wang, Zhen-guo

    2016-11-01

    Single phase flow friction factor of FC-72 and ethanol in mini-and micro-channels are experimentally investigated in the present study. High aspect ratio3 rectangular channels are selected, the hydraulic diameters of which are 571 µm, 762 µm and 1454 µm, and the aspect ratios are 20, 20 and 10 respectively. Degassed ethanol and FC-72 are used as working fluids. All the friction factors acquired in the 571 µm and 762 µm channels agree with the conventional friction theory within  ±20%-±25%. In the 1454 µm channel, however, deviations from the conventional theory occur and a modified empirical correlation of friction factor as a function of Reynolds number is proposed. Early transition from laminar to transitional flow is captured. Besides, effects of liquid physical properties are discussed. Lower viscosity and higher liquid density are responsible for the higher friction factor of FC-72. The influence of liquid properties weakens as the Reynolds number increases.

  7. The fluid mechanics of a high aspect ratio slot with an impressed pressure gradient and secondary injection

    Science.gov (United States)

    Sobanik, John Bertram

    1993-01-01

    A high aspect ratio slot flow (which emulates the gas leakage path in a gas turbine engine outer turbine air seal) is studied by use of a high aspect ratio slot using water as the working fluid. The cross section of the geometry is similar to a 'T', the slot being the vertical stroke and the main flow being the cross bar. A pressure gradient in the axial direction is created by blocking the main flow at a discreet location with an orifice plate (or blade tip simulator), located above the slot. Seven individually metered secondary flow injectors are located periodically along the bottom of the wall of the slot. Two slot widths, 1/8 and 1/4 inch, were investigated for length to width aspect ratios of 384 and 192 and height to width aspect ratios 33.2 and 16.6 respectively. Orifice plate pressure drops sufficient to give Reynolds numbers based upon half width of the slot, without secondary injection turned on, of 2350 and 4700 in the 1/8 inch slot and 4700 and 9400 in the 1/4 inch slot were run. Various secondary injection scenarios were added to the flow, the cases most studied being the no-injection and the all injectors flowing equal mass rates. Total injection rates for all seven injectors of 3.78 and 7.56 slot volumes per second were run. Laser velocimetry data and flow visualization pictures using fluorescein dye in the secondary flow are compared with computational results form the TEACH 3-D computer code. Major features and trends of the flow are captured by the computational model. Recommendations for further improvement of the numerical accuracy involves modification of the TEACH 3-D code to allow the 'slip condition' on all confining boundaries of the flow, or using a code which permits the 'slip condition' on all boundaries as a built-in option.

  8. High fidelity replication of surface texture and geometric form of a high aspect ratio aerodynamic test component

    Science.gov (United States)

    Walton, Karl; Fleming, Leigh; Goodhand, Martin; Racasan, Radu; Zeng, Wenhan

    2016-06-01

    This paper details, assesses and validates a technique for the replication of a titanium wind tunnel test aerofoil in polyurethane resin. Existing resin replication techniques are adapted to overcome the technical difficulties associated with casting a high aspect ratio component. The technique is shown to have high replication fidelity over all important length-scales. The blade chord was accurate to 0.02%, and the maximum blade thickness was accurate to 2.5%. Important spatial and amplitude areal surface texture parameter were accurate to within 2%. Compared to an existing similar system using correlation areal parameters the current technique is shown to have lower fidelity and this difference is discussed. The current technique was developed for the measurement of boundary layer flow ‘laminar to turbulent’ transition for gas turbine compressor blade profiles and this application is illustrated.

  9. Hydrothermal Synthesis of ZnO Structures Formed by High-Aspect-Ratio Nanowires for Acetone Detection.

    Science.gov (United States)

    Cao, Zhen; Wang, Yong; Li, Zhanguo; Yu, Naisen

    2016-12-01

    Snowflake-like ZnO structures originating from self-assembled nanowires were prepared by a low-temperature aqueous solution method. The as-grown hierarchical ZnO structures were investigated by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The results showed that the snowflake-like ZnO structures were composed of high-aspect-ratio nanowires. Furthermore, gas-sensing properties to various testing gases of 10 and 50 ppm were measured, which confirms that the ZnO structures were of good selectivity and response to acetone and could serve for acetone sensor to detect low-concentration acetone.

  10. Electrolytic Manganese Dioxide Coatings on High Aspect Ratio Micro-Pillar Arrays for 3D Thin Film Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Yafa Zargouni

    2017-05-01

    Full Text Available In this work, we present the electrochemical deposition of manganese dioxide (MnO2 thin films on carbon-coated TiN/Si micro-pillars. The carbon buffer layer, grown by plasma enhanced chemical vapor deposition (PECVD, is used as a protective coating for the underlying TiN current collector from oxidation, during the film deposition, while improving the electrical conductivity of the stack. A conformal electrolytic MnO2 (EMD coating is successfully achieved on high aspect ratio C/TiN/Si pillar arrays by tailoring the deposition process. Lithiation/Delithiation cycling tests have been performed. Reversible insertion and extraction of Li+ through EMD structure are observed. The fabricated stack is thus considered as a good candidate not only for 3D micorbatteries but also for other energy storage applications.

  11. Fabrication of high aspect ratio tungsten nanostructures on ultrathin c-Si membranes for extreme UV applications.

    Science.gov (United States)

    Delachat, F; Le Drogoff, B; Constancias, C; Delprat, S; Gautier, E; Chaker, M; Margot, J

    2016-01-15

    In this work, we demonstrate a full process for fabricating high aspect ratio diffraction optics for extreme ultraviolet lithography. The transmissive optics consists in nanometer scale tungsten patterns standing on flat, ultrathin (100 nm) and highly transparent (>85% at 13.5 nm) silicon membranes (diameter of 1 mm). These tungsten patterns were achieved using an innovative pseudo-Bosch etching process based on an inductively coupled plasma ignited in a mixture of SF6 and C4F8. Circular ultra-thin Si membranes were fabricated through a state-of-the-art method using direct-bonding with thermal difference. The silicon membranes were sputter-coated with a few hundred nanometers (100-300 nm) of stress-controlled tungsten and a very thin layer of chromium. Nanoscale features were written in a thin resist layer by electron beam lithography and transferred onto tungsten by plasma etching of both the chromium hard mask and the tungsten layer. This etching process results in highly anisotropic tungsten features at room temperature. The homogeneity and the aspect ratio of the advanced pattern transfer on the membranes were characterized with scanning electron microscopy after focus ion beam milling. An aspect ratio of about 6 for 35 nm size pattern is successfully obtained on a 1 mm diameter 100 nm thick Si membrane. The whole fabrication process is fully compatible with standard industrial semiconductor technology.

  12. Ultra-high aspect ratio poly-Si FinFET using an improved spacer formation technique

    Science.gov (United States)

    Liu, Libin; Liang, Renrong; Wang, Jing; Xu, Jun

    2017-04-01

    An improved spacer formation technique was proposed and developed to fabricate poly-Si fin field-effect transistors (FinFETs) with an ultra-high aspect ratio. The as-demonstrated FinFETs have a fin channel with a width and height of 22 nm and 230 nm, respectively, corresponding to an aspect ratio of 10.5. The electrical and temperature properties of the FinFETs are described in detail in this paper. The poly-Si FinFETs exhibit a steep subthreshold swing (196 mV/dec), a low leakage current (∼10-14 A), a high on/off current ratio (2.2 × 107 at VDS = 0.1 V), and a low drain-induced barrier lowering effect (0.28 V). The excellent switching characteristics are attributed to the ultrathin channel body and the multi-gate structure combined with high-k Al2O3 dielectric. Furthermore, the electron field-effective mobility increases as the temperature increases. An analytical fitting model was derived and was utilized to account for this phenomenon. The fitting results indicate that the positive temperature coefficient originates from the grain boundary-controlled mechanism in the low gate voltage regime.

  13. pH-Dependent Toxicity of High Aspect Ratio ZnO Nanowires in Macrophages Due to Intracellular Dissolution

    KAUST Repository

    H. Müller, Karin

    2010-11-23

    High-aspect ratio ZnO nanowires have become one of the most promising products in the nanosciences within the past few years with a multitude of applications at the interface of optics and electronics. The interaction of zinc with cells and organisms is complex, with both deficiency and excess causing severe effects. The emerging significance of zinc for many cellular processes makes it imperative to investigate the biological safety of ZnO nanowires in order to guarantee their safe economic exploitation. In this study, ZnO nanowires were found to be toxic to human monocyte macrophages (HMMs) at similar concentrations as ZnCl2. Confocal microscopy on live cells confirmed a rise in intracellular Zn2+ concentrations prior to cell death. In vitro, ZnO nanowires dissolved very rapidly in a simulated body fluid of lysosomal pH, whereas they were comparatively stable at extracellular pH. Bright-field transmission electron microscopy (TEM) showed a rapid macrophage uptake of ZnO nanowire aggregates by phagocytosis. Nanowire dissolution occurred within membrane-bound compartments, triggered by the acidic pH of the lysosomes. ZnO nanowire dissolution was confirmed by scanning electron microscopy/energy-dispersive X-ray spectrometry. Deposition of electron-dense material throughout the ZnO nanowire structures observed by TEM could indicate adsorption of cellular components onto the wires or localized zinc-induced protein precipitation. Our study demonstrates that ZnO nanowire toxicity in HMMs is due to pH-triggered, intracellular release of ionic Zn2+ rather than the high-aspect nature of the wires. Cell death had features of necrosis as well as apoptosis, with mitochondria displaying severe structural changes. The implications of these findings for the application of ZnO nanowires are discussed. © 2010 American Chemical Society.

  14. Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation

    Science.gov (United States)

    Balme, Sébastien; Picaud, Fabien; Manghi, Manoel; Palmeri, John; Bechelany, Mikhael; Cabello-Aguilar, Simon; Abou-Chaaya, Adib; Miele, Philippe; Balanzat, Emmanuel; Janot, Jean Marc

    2015-01-01

    Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10−2 C m−2 needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed. PMID:26036687

  15. Optimization of laser energy deposition for single-shot high aspect-ratio microstructuring of thick BK7 glass

    Energy Technology Data Exchange (ETDEWEB)

    Garzillo, Valerio; Grigutis, Robertas [Dipartimento di Scienza e Alta Tecnologia, University of Insubria, Via Valleggio 11, I-22100 Como (Italy); Jukna, Vytautas [Centre de Physique Theorique, CNRS, Ecole Polytechnique, Université Paris-Saclay, F-91128 Palaiseau (France); LOA, ENSTA-ParisTech, CNRS, Ecole Polytechnique, Université Paris Saclay, F-91762 Palaiseau (France); Couairon, Arnaud [Centre de Physique Theorique, CNRS, Ecole Polytechnique, Université Paris-Saclay, F-91128 Palaiseau (France); Di Trapani, Paolo [Dipartimento di Scienza e Alta Tecnologia, University of Insubria and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy); Jedrkiewicz, Ottavia, E-mail: ottavia.jedrkiewicz@ifn.cnr.it [Istituto di Fotonica e Nanotecnologie, CNR and CNISM UdR Como, Via Valleggio 11, I-22100 Como (Italy)

    2016-07-07

    We investigate the generation of high aspect ratio microstructures across 0.7 mm thick glass by means of single shot Bessel beam laser direct writing. We study the effect on the photoinscription of the cone angle, as well as of the energy and duration of the ultrashort laser pulse. The aim of the study is to optimize the parameters for the writing of a regular microstructure due to index modification along the whole sample thickness. By using a spectrally resolved single pulse transmission diagnostics at the output surface of the glass, we correlate the single shot material modification with observations of the absorption in different portions of the retrieved spectra, and with the absence or presence of spectral modulation. Numerical simulations of the evolution of the Bessel pulse intensity and of the energy deposition inside the sample help us interpret the experimental results that suggest to use picosecond pulses for an efficient and more regular energy deposition. Picosecond pulses take advantage of nonlinear plasma absorption and avoid temporal dynamics effects which can compromise the stationarity of the Bessel beam propagation.

  16. Tailoring femtosecond 1.5-μm Bessel beams for manufacturing high-aspect-ratio through-silicon vias.

    Science.gov (United States)

    He, Fei; Yu, Junjie; Tan, Yuanxin; Chu, Wei; Zhou, Changhe; Cheng, Ya; Sugioka, Koji

    2017-01-18

    Three-dimensional integrated circuits (3D ICs) are an attractive replacement for conventional 2D ICs as high-performance, low-power-consumption, and small-footprint microelectronic devices. However, one of the major remaining challenges is the manufacture of high-aspect-ratio through-silicon vias (TSVs), which is a crucial technology for the assembly of 3D Si ICs. Here, we present the fabrication of high-quality TSVs using a femtosecond (fs) 1.5-μm Bessel beam. To eliminate the severe ablation caused by the sidelobes of a conventional Bessel beam, a fs Bessel beam is tailored using a specially designed binary phase plate. We demonstrate that the tailored fs Bessel beam can be used to fabricate a 2D array of approximately ∅10-μm TSVs on a 100-μm-thick Si substrate without any sidelobe damage, suggesting potential application in the 3D assembly of 3D Si ICs.

  17. Tailoring femtosecond 1.5-μm Bessel beams for manufacturing high-aspect-ratio through-silicon vias

    Science.gov (United States)

    He, Fei; Yu, Junjie; Tan, Yuanxin; Chu, Wei; Zhou, Changhe; Cheng, Ya; Sugioka, Koji

    2017-01-01

    Three-dimensional integrated circuits (3D ICs) are an attractive replacement for conventional 2D ICs as high-performance, low-power-consumption, and small-footprint microelectronic devices. However, one of the major remaining challenges is the manufacture of high-aspect-ratio through-silicon vias (TSVs), which is a crucial technology for the assembly of 3D Si ICs. Here, we present the fabrication of high-quality TSVs using a femtosecond (fs) 1.5-μm Bessel beam. To eliminate the severe ablation caused by the sidelobes of a conventional Bessel beam, a fs Bessel beam is tailored using a specially designed binary phase plate. We demonstrate that the tailored fs Bessel beam can be used to fabricate a 2D array of approximately ∅10-μm TSVs on a 100-μm-thick Si substrate without any sidelobe damage, suggesting potential application in the 3D assembly of 3D Si ICs. PMID:28098250

  18. Optimization of laser energy deposition for single-shot high aspect-ratio microstructuring of thick BK7 glass

    Science.gov (United States)

    Garzillo, Valerio; Jukna, Vytautas; Couairon, Arnaud; Grigutis, Robertas; Di Trapani, Paolo; Jedrkiewicz, Ottavia

    2016-07-01

    We investigate the generation of high aspect ratio microstructures across 0.7 mm thick glass by means of single shot Bessel beam laser direct writing. We study the effect on the photoinscription of the cone angle, as well as of the energy and duration of the ultrashort laser pulse. The aim of the study is to optimize the parameters for the writing of a regular microstructure due to index modification along the whole sample thickness. By using a spectrally resolved single pulse transmission diagnostics at the output surface of the glass, we correlate the single shot material modification with observations of the absorption in different portions of the retrieved spectra, and with the absence or presence of spectral modulation. Numerical simulations of the evolution of the Bessel pulse intensity and of the energy deposition inside the sample help us interpret the experimental results that suggest to use picosecond pulses for an efficient and more regular energy deposition. Picosecond pulses take advantage of nonlinear plasma absorption and avoid temporal dynamics effects which can compromise the stationarity of the Bessel beam propagation.

  19. Ionic transport through sub-10 nm diameter hydrophobic high-aspect ratio nanopores: experiment, theory and simulation.

    Science.gov (United States)

    Balme, Sébastien; Picaud, Fabien; Manghi, Manoel; Palmeri, John; Bechelany, Mikhael; Cabello-Aguilar, Simon; Abou-Chaaya, Adib; Miele, Philippe; Balanzat, Emmanuel; Janot, Jean Marc

    2015-06-03

    Fundamental understanding of ionic transport at the nanoscale is essential for developing biosensors based on nanopore technology and new generation high-performance nanofiltration membranes for separation and purification applications. We study here ionic transport through single putatively neutral hydrophobic nanopores with high aspect ratio (of length L = 6 μm with diameters ranging from 1 to 10 nm) and with a well controlled cylindrical geometry. We develop a detailed hybrid mesoscopic theoretical approach for the electrolyte conductivity inside nanopores, which considers explicitly ion advection by electro-osmotic flow and possible flow slip at the pore surface. By fitting the experimental conductance data we show that for nanopore diameters greater than 4 nm a constant weak surface charge density of about 10(-2) C m(-2) needs to be incorporated in the model to account for conductance plateaus of a few pico-siemens at low salt concentrations. For tighter nanopores, our analysis leads to a higher surface charge density, which can be attributed to a modification of ion solvation structure close to the pore surface, as observed in the molecular dynamics simulations we performed.

  20. Mechanisms involved in the hydrothermal growth of ultra-thin and high aspect ratio ZnO nanowires

    Science.gov (United States)

    Demes, Thomas; Ternon, Céline; Morisot, Fanny; Riassetto, David; Legallais, Maxime; Roussel, Hervé; Langlet, Michel

    2017-07-01

    Hydrothermal synthesis of ZnO nanowires (NWs) with tailored dimensions, notably high aspect ratios (AR) and small diameters, is a major concern for a wide range of applications and still represents a challenging and recurring issue. In this work, an additive-free and reproducible hydrothermal procedure has been developed to grow ultra-thin and high AR ZnO NWs on sol-gel deposited ZnO seed layers. Controlling the substrate temperature and using a low reagent concentration (1 mM) has been found to be essential for obtaining such NWs. We show that the NW diameter remains constant at about 20-25 nm with growth time contrary to the NW length that can be selectively increased leading to NWs with ARs up to 400. On the basis of investigated experimental conditions along with thermodynamic and kinetic considerations, a ZnO NW growth mechanism has been developed which involves the formation and growth of nuclei followed by NW growth when the nuclei reach a critical size of about 20-25 nm. The low reagent concentration inhibits NW lateral growth leading to ultra-thin and high AR NWs. These NWs have been assembled into electrically conductive ZnO nanowire networks, which opens attractive perspectives toward the development of highly sensitive low-cost gas- or bio-sensors.

  1. Nanoscale tomographic reconstruction of the subsurface mechanical properties of low-k high-aspect ratio patterns

    Science.gov (United States)

    Stan, Gheorghe; Mays, Ebony; Yoo, Hui Jae; King, Sean W.

    2016-12-01

    In this work, intermittent contact resonance atomic force microscopy (ICR-AFM) was performed on high-aspect ratio a-SiOC:H patterned fins (100 nm in height and width from 20 to 90 nm) to map the depth and width dependencies of the material stiffness. The spatial resolution and depth sensitivity of the measurements were assessed from tomographic cross-sections over various regions of interest within the 3D space of the measurements. Furthermore, the depth-dependence of the measured contact stiffness over the scanned area was used to determine the sub-surface variation of the elastic modulus at each point in the scan. This was achieved by iteratively adjusting the local elastic profile until the depth dependence of the resulted contact stiffness matched the depth dependence of the contact stiffness measured by ICR-AFM at that location. The results of this analysis were assembled into nanoscale sub-surface tomographic images of the elastic modulus of the investigated SiOC:H patterns. A new 3D structure-property representation emerged from these tomographic images with direct evidence for the alterations sustained by the structures during processing.

  2. Sharp-Tip Silver Nanowires Mounted on Cantilevers for High-Aspect-Ratio High-Resolution Imaging.

    Science.gov (United States)

    Ma, Xuezhi; Zhu, Yangzhi; Kim, Sanggon; Liu, Qiushi; Byrley, Peter; Wei, Yang; Zhang, Jin; Jiang, Kaili; Fan, Shoushan; Yan, Ruoxue; Liu, Ming

    2016-11-09

    Despite many efforts to fabricate high-aspect-ratio atomic force microscopy (HAR-AFM) probes for high-fidelity, high-resolution topographical imaging of three-dimensional (3D) nanostructured surfaces, current HAR probes still suffer from unsatisfactory performance, low wear-resistivity, and extravagant prices. The primary objective of this work is to demonstrate a novel design of a high-resolution (HR) HAR AFM probe, which is fabricated through a reliable, cost-efficient benchtop process to precisely implant a single ultrasharp metallic nanowire on a standard AFM cantilever probe. The force-displacement curve indicated that the HAR-HR probe is robust against buckling and bending up to 150 nN. The probes were tested on polymer trenches, showing a much better image fidelity when compared with standard silicon tips. The lateral resolution, when scanning a rough metal thin film and single-walled carbon nanotubes (SW-CNTs), was found to be better than 8 nm. Finally, stable imaging quality in tapping mode was demonstrated for at least 15 continuous scans indicating high resistance to wear. These results demonstrate a reliable benchtop fabrication technique toward metallic HAR-HR AFM probes with performance parallel or exceeding that of commercial HAR probes, yet at a fraction of their cost.

  3. 高厚径比HDI板电镀能力研究%Plating ability Of HDI with high aspect ratio item

    Institute of Scientific and Technical Information of China (English)

    班向东

    2013-01-01

    With the development of information technology, more layers, thickness, aperture smaller, thicker wiring denser PCB needs PCB manufacturers put forward higher requirements. High aspect ratio and BMV plating are two different processing direction of PCB plating, and the two requirements of both the product processing is the dififculty of electroplating. So to ifnd a balance between the two is very important. Through the experiment, we found the electroplating parameters, achieved the balance of the blind holes.%随着信息技术的不断发展,层数更多、板厚更厚、孔径更小、布线更密的PCB需求给PCB生产厂家提出的更高的要求。高纵横比与盲孔电镀是PCB电镀的两个不同的加工方向,而这两种要求并存的产品加工是电镀的难点,因此找到两者之间的平衡点至关重要。本文通过实验,找到两者兼顾的电镀参数,达到通盲孔兼顾的效果。

  4. Fabrication of high-aspect-ratio double-slot photonic crystal waveguide in InP heterostructure by inductively coupled plasma etching using ultra-low pressure

    Directory of Open Access Journals (Sweden)

    Kaiyu Cui

    2013-02-01

    Full Text Available Double-slot photonic crystal waveguide (PCW in InP heterostructure is fabricated by inductively coupled plasma (ICP etching. Due to using an ultra-low pressure of 0.05 Pa, etch depths up to 3.5 μm for holes with diameter of 200 nm and 1.8 μm for slots of ∼40 nm are achieved, which indicate a record-high aspect-ratio, i.e. 45, for such narrow slots in InP heterostructure. Moreover, etching quality is evaluated based on both the transmission performance and the linewidth of micro-photoluminescence (μ-PL. In our measurement, a structure-dependent transmission-dip about 17 dB is obtained from a 17-μm-long W3 PCW, and a PL widening as small as 19 nm compared to the corresponding wafer is observed. These promising experimental results evidence the high etching quality realized in this work and confirm the feasibility of etching small-feature-size patterns by ICP technology for InP based devices in future mono-/hetero-integrated photonic circuits.

  5. FFT-impedance spectroscopy analysis of the growth of magnetic metal nanowires in ultra-high aspect ratio InP membranes

    Science.gov (United States)

    Gerngross, M.-D.; Carstensen, J.; Föll, H.; Adelung, R.

    2016-01-01

    This paper reports on the characterization of the electrochemical growth process of magnetic nanowires in ultra-high-aspect ratio InP membranes via in situ fast Fourier transform impedance spectroscopy in a typical frequency range from 75 Hz to 18.5 kHz. The measured impedance data from the Ni, Co, and FeCo can be very well fitted using the same electric equivalent circuit consisting of a series resistance in serial connection to an RC-element and a Maxwell element. The impedance data clearly indicate the similarities in the growth behavior of Ni, Co and FeCo nanowires in ultra-high aspect ratio InP membranes—the beneficial impact of boric acid on the metal deposition in ultra-high aspect ratio membranes and the diffusion limitation of boric acid, as well as differences such as passivation or side reactions.

  6. Fabrication of High Aspect Ratio Through-Wafer Vias in CMOS Wafers for 3-D Packaging Applications

    DEFF Research Database (Denmark)

    Rasmussen, Frank Engel; Frech, J.; Heschel, M.

    2003-01-01

    A process for fabrication of through-wafer vias in CMOS wafers is presented. The process presented offers simple and well controlled fabrication of through-wafer vias using DRIE formation of wafer through-holes, low temperature deposition of through-hole insulation, doubled sided sputtering of Cr....../Au, and electroless deposition of Cu. A novel characteristic of the process is the use of a metal etch stop layer providing perfect control of the etch profile of the wafer through-holes in combination with a remarkably improved etch uniformity across the wafer. Excellent through-hole insulation is provided through...

  7. Electrodeposition of Gold to Conformally Fill High Aspect Ratio Nanometric Silicon Grating Trenches: A Comparison of Pulsed and Direct Current Protocols

    OpenAIRE

    Znati, Sami A.; Chedid, Nicholas; Miao, Houxun; Chen,Lei; Bennett, Eric E.; Wen, Han

    2015-01-01

    Filling high-aspect-ratio trenches with gold is a frequent requirement in the fabrication of x-ray optics as well as micro-electronic components and other fabrication processes. Conformal electrodeposition of gold in sub-micron-width silicon trenches with an aspect ratio greater than 35 over a grating area of several square centimeters is challenging and has not been described in the literature previously. A comparison of pulsed plating and constant current plating led to a gold electroplatin...

  8. Sharp high-aspect-ratio AFM tips fabricated by a combination of deep reactive ion etching and focused ion beam techniques.

    Science.gov (United States)

    Caballero, David; Villanueva, Guillermo; Plaza, Jose Antonio; Mills, Christopher A; Samitier, Josep; Errachid, Abdelhamid

    2010-01-01

    The shape and dimensions of an atomic force microscope tip are crucial factors to obtain high resolution images at the nanoscale. When measuring samples with narrow trenches, inclined sidewalls near 90 degrees or nanoscaled structures, standard silicon atomic force microscopy (AFM) tips do not provide satisfactory results. We have combined deep reactive ion etching (DRIE) and focused ion beam (FIB) lithography techniques in order to produce probes with sharp rocket-shaped silicon AFM tips for high resolution imaging. The cantilevers were shaped and the bulk micromachining was performed using the same DRIE equipment. To improve the tip aspect ratio we used FIB nanolithography technique. The tips were tested on narrow silicon trenches and over biological samples showing a better resolution when compared with standard AFM tips, which enables nanocharacterization and nanometrology of high-aspect-ratio structures and nanoscaled biological elements to be completed, and provides an alternative to commercial high aspect ratio AFM tips.

  9. Numerical design of X-ray tabletop Talbot interferometer using polycapillary optics as two-dimensional gratings with high aspect ratio

    Science.gov (United States)

    Sun, Weiyuan; Liu, Zhiguo; Sun, Tianxi; Sun, Xuepeng; Li, Fangzuo; Jiang, Bowen; Ding, Xunliang

    2015-12-01

    The polycapillary optics was proposed to be used as two-dimensional X-ray gratings with high aspect ratios for high energy X-rays. The X-ray Talbot interferometer was designed numerically using the polycapillary X-ray gratings and a conventional X-ray source. The simulation showed that it was available to get a high-aspect-ratio pattern of the polycapillary X-ray gratings for higher energies than 60 keV. Moreover, this design of polycapillary gratings decreased the requirement for high power of the X-ray source. The polycapillary X-ray gratings had potential applications in X-ray imaging technology for medical fields, industrial nondestructive tests, public security, physical science, chemical analysis, life science, nanoscience biology and energy science.

  10. A Link Between Black Holes and the Golden Ratio

    CERN Document Server

    Nieto, J A

    2011-01-01

    We consider a variational formalism to describe black holes solution in higher dimensions. Our procedure clarifies the arbitrariness of the radius parameter and, in particular, the meaning of the event horizon of a black hole. Moreover, our formalism enables us to find a surprising link between black holes and the golden ratio.

  11. Electrically conducting, ultra-sharp, high aspect-ratio probes for AFM fabricated by electron-beam-induced deposition of platinum

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Jason, E-mail: jason.brown@physics.ox.ac.uk [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Kocher, Paul; Ramanujan, Chandra S; Sharp, David N [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom); Torimitsu, Keiichi [NTT Basic Research Laboratories, NTT Corporation, Atsugi, 243-0198 (Japan); Ryan, John F [Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU (United Kingdom)

    2013-10-15

    We report on the fabrication of electrically conducting, ultra-sharp, high-aspect ratio probes for atomic force microscopy by electron-beam-induced deposition of platinum. Probes of 4.0 ±1.0 nm radius-of-curvature are routinely produced with high repeatability and near-100% yield. Contact-mode topographical imaging of the granular nature of a sputtered gold surface is used to assess the imaging performance of the probes, and the derived power spectral density plots are used to quantify the enhanced sensitivity as a function of spatial frequency. The ability of the probes to reproduce high aspect-ratio features is illustrated by imaging a close-packed array of nanospheres. The electrical resistance of the probes is measured to be of order 100 kΩ. - Highlights: • Electrically conducting, ultra-sharp, high aspect-ratio probes for AFM with radius-of-curvature 4.0±±1.0 nm. • AFM probe fabrication by electron-beam-induced deposition of platinum. • Enhanced spatial resolution demonstrated through AFM of sputtered gold grains. • AFM imaging of deep clefts and recesses on a close-packed array of nanospheres.

  12. Engineered high aspect ratio vertical nanotubes as a model system for the investigation of catalytic methanol synthesis over Cu/ZnO.

    Science.gov (United States)

    Güder, Firat; Frei, Elias; Kücükbayrak, Umut M; Menzel, Andreas; Thomann, Ralf; Luptak, Roman; Hollaender, Bernd; Krossing, Ingo; Zacharias, Margit

    2014-02-12

    Catalytically synthesized methanol from H2 and CO2 using porous Cu/ZnO aggregates is a promising, carbon neutral, and renewable alternative to replace fossil fuel based transport fuels. However, the absence of surface-engineered model systems to understand and improve the industrial Cu/ZnO catalyst poses a big technological gap in efforts to increase industrial methanol conversion efficiency. In this work, we report a novel process for the fabrication of patterned, vertically aligned high aspect ratio 1D nanostructures on Si that can be used as an engineered model catalyst. The proposed strategy employs near-field phase shift lithography (NF-PSL), deep reactive ion etching (DRIE), and atomic layer deposition (ALD) to pattern, etch, and coat Si wafers to produce high aspect ratio 1D nanostructures. Using this method, we produced a model system consisting of high aspect ratio Cu-decorated ZnO nanotubes (NTs) to investigate the morphological effects of ZnO catalyst support in comparison to the planar Cu/ZnO catalyst in terms of the catalytic reactions. The engineered catalysts performed 70 times better in activating CO2 than the industrial catalyst. In light of the obtained results, several important points are highlighted, and recommendations are made to achieve higher catalytic performance.

  13. Electrochemical growth of Co nanowires in ultra-high aspect ratio InP membranes: FFT-impedance spectroscopy of the growth process and magnetic properties

    Science.gov (United States)

    2014-01-01

    The electrochemical growth of Co nanowires in ultra-high aspect ratio InP membranes has been investigated by fast Fourier transform-impedance spectroscopy (FFT-IS) in the frequency range from 75 Hz to 18.5 kHz. The impedance data could be fitted very well using an electric circuit equivalent model with a series resistance connected in series to a simple resistor-capacitor (RC) element and a Maxwell element. Based on the impedance data, the Co deposition in ultra-high aspect ratio InP membranes can be divided into two different Co deposition processes. The corresponding share of each process on the overall Co deposition can be determined directly from the transfer resistances of the two processes. The impedance data clearly show the beneficial impact of boric acid on the Co deposition and also indicate a diffusion limitation of boric acid in ultra-high aspect ratio InP membranes. The grown Co nanowires are polycrystalline with a very small grain size. They show a narrow hysteresis loop with a preferential orientation of the easy magnetization direction along the long nanowire axis due to the arising shape anisotropy of the Co nanowires. PMID:25050088

  14. Electrochemical growth of Co nanowires in ultra-high aspect ratio InP membranes: FFT-impedance spectroscopy of the growth process and magnetic properties

    Science.gov (United States)

    Gerngross, Mark-Daniel; Carstensen, Jürgen; Föll, Helmut

    2014-06-01

    The electrochemical growth of Co nanowires in ultra-high aspect ratio InP membranes has been investigated by fast Fourier transform-impedance spectroscopy (FFT-IS) in the frequency range from 75 Hz to 18.5 kHz. The impedance data could be fitted very well using an electric circuit equivalent model with a series resistance connected in series to a simple resistor-capacitor ( RC) element and a Maxwell element. Based on the impedance data, the Co deposition in ultra-high aspect ratio InP membranes can be divided into two different Co deposition processes. The corresponding share of each process on the overall Co deposition can be determined directly from the transfer resistances of the two processes. The impedance data clearly show the beneficial impact of boric acid on the Co deposition and also indicate a diffusion limitation of boric acid in ultra-high aspect ratio InP membranes. The grown Co nanowires are polycrystalline with a very small grain size. They show a narrow hysteresis loop with a preferential orientation of the easy magnetization direction along the long nanowire axis due to the arising shape anisotropy of the Co nanowires.

  15. A study of high-altitude manned research aircraft employing strut-braced wings of high-aspect-ratio

    Science.gov (United States)

    Smith, P. M.; Deyoung, J.; Lovell, W. A.; Price, J. E.; Washburn, G. F.

    1981-01-01

    The effect of increased wing aspect ratio of subsonic aircraft on configurations with and without strut bracing. Results indicate that an optimum cantilever configuration, with a wing aspect ratio of approximately 26, has a 19% improvement in cruise range when compared to a baseline concept with a wing aspect ratio of approximately 10. An optimum strut braced configuration, with a wing aspect ratio of approximately 28, has a 31% improvment in cruise range when compared to the same baseline concept. This improvement is mainly due to the estimated reduction in wing weight resulting from use of lifting struts. All configurations assume the same mission payload and fuel. The drag characteristics of the wings are enhanced with the use of laminar flow airfoils. A method for determining the extent of attainable natural laminar flow, and methods for preliminary structural design and for aerodynamic analysis of wings lifting struts are presented.

  16. Narrow conductive structures with high aspect ratios through single-pass inkjet printing and evaporation-induced dewetting

    NARCIS (Netherlands)

    Abbel, R.; Teunissen, P.; Michels, J.; Groen, W.A.

    2015-01-01

    Inkjet printed silver lines contract to widths below 20-μm during drying on an organic planarization coating. Aspect ratios previously unprecedented with single pass inkjet printing on isotropic homogeneous substrates are obtained. This effect is caused by the subsequent evaporation of solvents from

  17. Fabrication of high-aspect-ratio microstructures in polymer microfluid chips for in vitro single-cell analysis

    Science.gov (United States)

    Bukatin, A. S.; Mukhin, I. S.; Malyshev, E. I.; Kukhtevich, I. V.; Evstrapov, A. A.; Dubina, M. V.

    2016-10-01

    Technologies and methods of prototyping microfluidic devices are widely used in solving many biological problems and testing of operability of new microanalytic systems. This study is devoted to analyzing the features of the formation of microstructures in SU-8 photoresist and the preparation of replicas in polydimethyl siloxane by the soft lithography method. It has been shown that the aspect ratio of the resultant microstructures is determined by their shape, size, and the force of resist adhesion to the silicon substrate and the efficiency of the circulation of the developer around microstructures. In the replication of complex microstructures, an aspect ratio of 25 is attained. The technology considered here is used to prepare microfluidic chips with mechanical traps for fixation and the in vitro analysis of living cells.

  18. Conductivity and methanol permeability of Nafion-zirconium phosphate composite membranes containing high aspect ratio filler particles

    Energy Technology Data Exchange (ETDEWEB)

    Bagnasco, G.; Micoli, L.; Turco, M. [Dipartimento di Ingegneria Chimica, Universita di Napoli Federico II, P.le V. Tecchio 80, 80125 - Napoli (Italy); Donnadio, A.; Pica, M.; Sganappa, M. [Dipartimento di Chimica, Universita di Perugia, via Elce di Sotto 8, 06123 - Perugia (Italy); Casciola, M.

    2009-08-15

    Gels of exfoliated {alpha}-zirconium phosphate (ZrP{sub exf}) in dimethylformamide (DMF) were used to prepare Nafion/ZrP{sub exf} composite membranes with filler loadings up to 7 wt.-% by casting mixtures of Nafion 1100 solutions in DMF and suitable amounts of 2 wt.-% ZrP gels in DMF. TEM pictures showed that the ZrP{sub exf} particles had aspect ratio of at least 20. All samples were characterised by methanol permeability (P) and through-plane ({sigma}{sub thp}) and in-plane ({sigma}{sub inp}) conductivity measurements at 40 C and 100% RH. The methanol permeability of Nafion membranes containing in situ grown ZrP particles with low aspect ratio (Nafion/ZrP{sub isg}) was also determined. The methanol permeability and the swelling behaviour of the composite membranes turned out to be strongly dependent on the filler morphology. As a general trend, both permeability and swelling decreased according to the sequence: Nafion/ZrP{sub isg} > Nafion > Nafion/ZrP{sub exf}. The maximum selectivity ({sigma}{sub thp}/P = 1.4 x 10{sup 5} S cm{sup -3} s) was found for the membrane filled with 1 wt.-% ZrP{sub exf}: this value is seven times higher than that of Nafion. For the Nafion/ZrP{sub exf} membranes, the ratio {sigma}{sub inp}/{sigma}{sub thp} increases with the filler loading, thus indicating that the preferred orientation of the ZrP sheets is parallel to the membrane surface. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  19. High aspect ratio, nanostructured, platinum based electrodes for proton exchange membrane fuel cells: Design, development and ionic conduction of the proposed structures

    Science.gov (United States)

    Paschos, Odysseas

    High aspect ratio nanostructures can provide substantial benefits when used as fuel cell electrodes since they can alleviate problems associated with conventional carbon supports. In this work the potential of incorporating high aspect ratio nanostructures as electrodes for fuel cells was studied. Moreover, a model was created that demonstrated the potential for the nanostructures to yield high performance. The creation of Pt nanorods using anodic aluminum oxide templates was investigated and experiments showed complete utilization of the electrodes surface area. However, the Pt nanorod structure was found to not be effective in terms of Pt mass utilization, since only the outer surface of the rod is utilized for catalytic activity. An alternate method was developed to coat (with Pt) high aspect ratio structures made from a cost-effective support material. Thus far, methods used to conformally coat Pt either cannot be used directly on several materials or tend not to be cost-effective. A non-vacuum method based on an Aerosol Assisted Deposition (AAD) technique was developed and optimized. Initial experiments showed feasibility of the technique to coat a large variety of substrates. Dimensions of the particles were controlled by the deposition parameters and ranged from 4 nm up to several hundreds of nm in diameter. Experiments where Pt nanoparticles were deposited on gas diffusion layer substrates, showed higher electrochemical performance compared to commercial catalyst. The need for electrolyte coating on the high aspect ratio structures was also investigated. Initial experiments were performed by splitting an MEA in half and using an intermediate Pt film. These experiments showed that ionic conduction on Pt surface is possible. Moreover these studies indicated that ionic conduction on Pt could result from hydrophilic groups that can exist on its surface. Since these groups can either be physisorbed due to presence of water or chemisorbed on the oxidized Pt

  20. Internal Laser Writing of High-Aspect-Ratio Microfluidic Structures in Silicate Glasses for Lab-on-a-Chip Applications

    Directory of Open Access Journals (Sweden)

    Ya Cheng

    2017-02-01

    Full Text Available Femtosecond laser direct writing is unique in allowing for fabrication of 3D micro- and nanofluidic structures, thereby enabling rapid and efficient manipulation of fluidic dynamics in 3D space to realize innovative functionalities. Here, I discuss the challenges in producing fully functional and highly integrated 3D micro- and nanofluidic systems with potential applications ranging from chemical and biological analyses to investigations of nanofluidic behaviors. In particular, I review the achievements we have made in the past decade, which have led to 3D microchannels with controllable cross-sectional profiles and large aspect ratios, 3D nanofluidic channels with widths of several tens of nanometers, and smooth inner walls with roughness on the order of ~1 nm. Integration of the microfluidics with other functional microcomponents including microoptics and microelectrodes will also be discussed, followed by conclusions and the future perspective.

  1. Application of Self-Assembled Monolayers to the Electroless Metallization of High Aspect Ratio Vias for Microelectronics

    Science.gov (United States)

    Bernasconi, R.; Molazemhosseini, A.; Cervati, M.; Armini, S.; Magagnin, L.

    2016-10-01

    All-wet electroless metallization of through-silicon vias (TSVs) with a width of 5 μm and a 1:10 aspect ratio was carried out. Immersion in a n-(2-aminoethyl) 3-aminopropyl-trimethoxysilane (AEAPTMS) self-assembled monolayer (SAM) was used to enhance the adhesion between the metal film and substrate. Contact angle variation and atomic force microscopy were used to verify the formation of a SAM layer. A PdCl2 solution was later used to activate the silanized substrates, exploiting the affinity of the -NH3 functional group of AEAPTMS to palladium. A nickel-phosphorus-boron electroless bath was employed to deposit the first barrier layer onto silicon. The NiPB growth rate was evaluated on flat silicon wafers, while the structure of the coating obtained was investigated via glow discharge optical emission spectroscopy. Cross-sectional scanning electron microscope observations were carried out on metallized TSVs to characterize the NiPB seed, the Cu seed layer deposited with a second electroless step, and the Cu superfilling obtained with a commercial solution. Complete filling of TSV was achieved.

  2. An implicit wetting and drying approach for non-hydrostatic baroclinic flows in high aspect ratio domains

    Science.gov (United States)

    Candy, A. S.

    2017-04-01

    A new approach to modelling free surface flows is developed that enables, for the first time, 3D consistent non-hydrostatic baroclinic physics that wets and drys in the large aspect ratio spatial domains that characterise geophysical systems. This is key in the integration of physical models to permit seamless simulation in a single consistent arbitrarily unstructured multiscale and multi-physics dynamical model. A high order continuum representation is achieved through a general Galerkin finite element formulation that guarantees local and global mass conservation, and consistent tracer advection. A flexible spatial discretisation permits conforming domain bounds and a variable spatial resolution, whilst atypical use of fully implicit time integration ensures computational efficiency. Notably this brings the natural inclusion of non-hydrostatic baroclinic physics and a consideration of vertical inertia to flood modelling in the full 3D domain. This has application in improving modelling of inundation processes in geophysical domains, where dynamics proceeds over a large range of horizontal extents relative to vertical resolution, such as in the evolution of a tsunami, or in urban environments containing complex geometric structures at a range of scales.

  3. A high aspect ratio SU-8 fabrication technique for hollow microneedles for transdermal drug delivery and blood extraction

    Science.gov (United States)

    Chaudhri, Buddhadev Paul; Ceyssens, Frederik; De Moor, Piet; Van Hoof, Chris; Puers, Robert

    2010-06-01

    Protein drugs, e.g. hormonal drugs, cannot be delivered orally to a patient as they get digested in the gastro-intestinal (GI) tract. Thus, it is imperative that these kinds of drugs are delivered transdermally through the skin. To provide for real-time feedback as well as to test independently for various substances in the blood, we also need a blood sampling system. Microneedles can perform both these functions. Further, microneedles made of silicon or metal have the risk of breaking inside the skin thereby leading to complications. SU-8, being approved of as being biocompatible by the Food and Drug Agency (FDA) of the United States, is an attractive alternative because firstly it is a polymer material, thereby reducing the chances of breakages inside the skin, and secondly it is a negative photoresist, thereby leading to ease of fabrication. Thus, here we present very tall (around 1600 µm) SU-8 polymer-based hollow microneedles fabricated by a simple and repeatable process, which are a very good candidate for transdermal drug delivery as well as blood extraction. The paper elaborates on the details that allow the fabrication of such extreme aspect ratios (>100).

  4. Solution Process Synthesis of High Aspect Ratio ZnO Nanorods on Electrode Surface for Sensitive Electrochemical Detection of Uric Acid

    Science.gov (United States)

    Ahmad, Rafiq; Tripathy, Nirmalya; Ahn, Min-Sang; Hahn, Yoon-Bong

    2017-04-01

    This study demonstrates a highly stable, selective and sensitive uric acid (UA) biosensor based on high aspect ratio zinc oxide nanorods (ZNRs) vertical grown on electrode surface via a simple one-step low temperature solution route. Uricase enzyme was immobilized on the ZNRs followed by Nafion covering to fabricate UA sensing electrodes (Nafion/Uricase-ZNRs/Ag). The fabricated electrodes showed enhanced performance with attractive analytical response, such as a high sensitivity of 239.67 μA cm-2 mM-1 in wide-linear range (0.01-4.56 mM), rapid response time (~3 s), low detection limit (5 nM), and low value of apparent Michaelis-Menten constant (Kmapp, 0.025 mM). In addition, selectivity, reproducibility and long-term storage stability of biosensor was also demonstrated. These results can be attributed to the high aspect ratio of vertically grown ZNRs which provides high surface area leading to enhanced enzyme immobilization, high electrocatalytic activity, and direct electron transfer during electrochemical detection of UA. We expect that this biosensor platform will be advantageous to fabricate ultrasensitive, robust, low-cost sensing device for numerous analyte detection.

  5. Protein-enabled layer-by-layer syntheses of aligned, porous-wall, high-aspect-ratio TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Berrigan, John D.; Cai, Ye; Sandhage, Kenneth H. [School of Materials Science and Engineering, Air Force Center of Excellence on Bio-Nano-Enabled Inorganic/Organic Nanocomposites and Improved Cognition (BIONIC), Georgia Institute of Technology, 771 Ferst Drive, Atlanta, Georgia 30332-0400 (United States); Kang, Tae-Sik; Deneault, James R.; Durstock, Michael F. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, 45433-7702 (United States)

    2011-05-10

    An aqueous, protein-enabled (biomimetic), layer-by-layer titania deposition process is developed, for the first time, to convert aligned-nanochannel templates into high-aspect-ratio, aligned nanotube arrays with thin (34 nm) walls composed of co-continuous networks of pores and titania nanocrystals (15 nm ave. size). Alumina templates with aligned open nanochannels are exposed in an alternating fashion to aqueous protamine-bearing and titania precursor-bearing (Ti(IV) bis-ammonium-lactato-dihydroxide, TiBALDH) solutions. The ability of protamine to bind to alumina and titania, and to induce the formation of a Ti-O-bearing coating upon exposure to the TiBALDH precursor, enables the layer-by-layer deposition of a conformal protamine/Ti-O-bearing coating on the nanochannel surfaces within the porous alumina template. Subsequent protamine pyrolysis yields coatings composed of co-continuous networks of pores and titania nanoparticles. Selective dissolution of the underlying alumina template through the porous coating then yields freestanding, aligned, porous-wall titania nanotube arrays. The interconnected pores within the nanotube walls allow enhanced loading of functional molecules (such as a Ru-based N719 dye), whereas the interconnected titania nanoparticles enable the high-aspect-ratio, aligned nanotube arrays to be used as electrodes (as demonstrated for dye-sensitized solar cells with power conversion efficiencies of 5.2 {+-} 0.4%). (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. High-Yield Synthesis of Uniform Ag Nanowires with High Aspect Ratios by Introducing the Long-Chain PVP in an Improved Polyol Process

    Directory of Open Access Journals (Sweden)

    Jie-Jun Zhu

    2011-01-01

    Full Text Available Polyvinyl pyrrolidone (PVP with different molecular weights was used as capping agent to synthesize silver nanowires through a polyol process. The results indicated that the yields and aspect ratios of silver nanowires were controlled by the chain length of PVP and increased with increasing the molecular weight (MW of PVP. When the long-chain PVP-K90 (MW = 800,000 was used, the product was uniform in size and was dominated by nanowires with high aspect ratios. The growth mechanism of the nanowires was studied. It is proposed that the chemical adsorption of Ag+ on the PVP chains at the initial stage promotes the growth of Ag nanowires.

  7. Low-temperature plasma etching of high aspect-ratio densely packed 15 to sub-10 nm silicon features derived from PS-PDMS block copolymer patterns.

    Science.gov (United States)

    Liu, Zuwei; Gu, Xiaodan; Hwu, Justin; Sassolini, Simone; Olynick, Deirdre L

    2014-07-18

    The combination of block copolymer (BCP) lithography and plasma etching offers a gateway to densely packed sub-10 nm features for advanced nanotechnology. Despite the advances in BCP lithography, plasma pattern transfer remains a major challenge. We use controlled and low substrate temperatures during plasma etching of a chromium hard mask and then the underlying substrate as a route to high aspect ratio sub-10 nm silicon features derived from BCP lithography. Siloxane masks were fabricated using poly(styrene-b-siloxane) (PS-PDMS) BCP to create either line-type masks or, with the addition of low molecular weight PS-OH homopolymer, dot-type masks. Temperature control was essential for preventing mask migration and controlling the etched feature's shape. Vertical silicon wire features (15 nm with feature-to-feature spacing of 26 nm) were etched with aspect ratios up to 17 : 1; higher aspect ratios were limited by the collapse of nanoscale silicon structures. Sub-10 nm fin structures were etched with aspect ratios greater than 10 : 1. Transmission electron microscopy images of the wires reveal a crystalline silicon core with an amorphous surface layer, just slightly thicker than a native oxide.

  8. High Aspect Ratio Silver Conductive Tracks in Inkjet Printing%喷墨打印制备高“高宽比”银导线工艺

    Institute of Scientific and Technical Information of China (English)

    张磊; 朱云龙; 程晓鼎; 王驰远

    2016-01-01

    传统丝网印刷技术因其接触式印刷工艺难以提高金属导线的精度和“高宽比”,为实现高“高宽比”的金属导线制造,以低黏度纳米银墨水为喷墨材料,采用自主研发的喷墨打印设备在多种基材表面打印银导线.通过喷墨打印实验方法研究了喷墨打印过程的“咖啡环”及“马鞍型”缺陷产生原理及影响因素,通过在Teslin、Kapton、多晶硅硅片及高光相纸4种基材上多层打印及改变基板温度制备银导线,研究了银导线“高宽比”及三维形貌的变化关系.实验结果表明:基板温度在60℃时,打印的银导线呈“拱型”;基板温度在80℃时,打印的银导线“高宽比”最佳且受基材影响减弱.打印层数为20层时,导线边缘出现波浪纹;打印层数为80层时,波浪纹消失,导线形貌均匀.烧结温度为200℃时,银导线导电能力得到极大提升,Teslin基材形成的银导线电阻率最低至2.13μΩ·cm.%It' s difficult to improve the accuracy and aspect ratio of conductive tracks for the traditional screen printing technology. In order to achieve high aspect ratio of conductive tracks, an ink jet printing method for fabrication of high aspect ratio silver tracks was described. The mechanisms and influence factors of coffee-ring and M-type effect were revealed by experiments. The experiments of multi-pass inkjet printing on Teslin, Kapton, Polycrystalline silicon, glossy photo paper and altering substrates temperature procedure were carried out. The results show that when the substrate temperature is 60℃, the arch-type silver tracks are formed. When the substrate temperature is 80 ℃, the optimized aspect ratio of silver tracks is formed and the influence by different substrates is weak. As inkjet printing runs 20 pass, wave form on the edge of silver tracks comes out. When inkjet printing runs 80 pass, wave form fades away and high aspect ratio silver tracks are fabricated instead. When

  9. Fabrication of high aspect ratio TiO2 and Al2O3 nanogratings by atomic layer deposition

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Michael-Lindhard, Jonas

    2016-01-01

    followed by ALD of TiO2 or Al2O3. Then, the template was etched away using SF6 in an inductively coupled plasma tool, which resulted in the formation of isolated ALD coatings, thereby achieving high aspect ratio grating structures. SF6 plasma removes silicon selectively without any observable influence......The authors report on the fabrication of TiO2 and Al2O3 nanostructured gratings with an aspect ratio of up to 50. The gratings were made by a combination of atomic layer deposition (ALD) and dry etch techniques. The workflow included fabrication of a Si template using deep reactive ion etching...... in a gradual change in the pitch value of the structures. The pitch on top of the gratings is 400 nm, and it gradually reduces to 200 nm at the bottom. The form of the bending can be reshaped by Arþ ion beam etching. The chemical purity of the ALD grown materials was analyzed by x-ray photoelectron...

  10. Design, fabrication and characterization of high-stroke high-aspect ratio micro electro mechanical systems deformable mirrors for adaptive optics

    Science.gov (United States)

    Fernandez Rocha, Bautista

    Adaptive optic (AO) systems for next generation of extremely large telescopes (30--50 meter diameter primary mirrors) require high-stroke (10 microns), high-order (100x100) deformable mirrors at lower-cost than current technology. The required specifications are achievable with Micro Electro Mechanical Systems (MEMS) devices fabricated with high-aspect ratio processing techniques. This dissertation will review simulation results compared with displacement measurements of actuators utilizing a white-light interferometer. It will also review different actuator designs, materials and post-processing procedures fabricated in three different high-aspect ratio processes, Microfabrica's Electrochemical Fabrication (EFAB(TM)), HT-Micro's Precision Fabrication Technology (HTPF(TM)), and Innovative Micro Technologies (IMT) fabrication process. These manufacturing processes allow high-precision multilayer fabrication and their sacrificial layer thicknesses can be specified by the designer, rather than by constraints of the fabrication process. Various types of high-stroke gold actuators for AO consisting of folded springs with rectangular and circular membranes as well as X-beam actuators supported diagonally by beams were designed, simulated, fabricated, and tested individually and as part of a continuous facesheet DM system. The design, modeling and simulation of these actuators are compared to experimental measurements of their pull-in voltages, which characterizes their stiffness and maximum stroke. Vertical parallel plate ganged actuators fabricated with the EFAB(TM) process have a calculated pull-in voltage of 95V for a 600mum size device. In contrast, the pull-in voltages for the comb-drive actuators ranged from 55V for the large actuator, to 203V for the smallest actuator. Simulations and interferometer scans of actuator designs fabricated with HT-Micro's Precision Fabrication (HTPF(TM)) two wafer bonded process with different spring supports have shown the ability of

  11. The acoustics of short circular holes with finite expansion ratio

    Science.gov (United States)

    Yang, Dong; Morgans, Aimee

    2016-11-01

    The acoustic response of a circular hole with mean flow passing through it is highly relevant to Helmholtz resonators, fuel injectors, perforated liners, perforated plates and many other engineering applications. Analytical models for the acoustic response of these holes often ignore the impact of a finite expansion ratio either side, or account for it simply by adding an end mass inertial correction derived from the no mean flow assumption. The vortex-sound interaction within a short hole has been recently shown to strongly affect the acoustic response in the low frequency region. The present study uses an analytical model based on the Green's function method to investigate how the expansion ratios either side of a short hole affect the vortex-sound interaction within it - something neglected by previous models. This model is then incorporated into a Helmholtz resonator model, allowing us to consider the effect of a finite neck-to-cavity expansion ratio and the vortex-sound interaction within the finite length neck. Large resistance and acoustic energy absorption performance variations are seen even for small changes in the resonator neck length. Reducing the neck-to-cavity expansion ratio is found to decrease the resonator's sound absorption when the expansion ratio is low. CSC-Imperial PhD Scholarship; ERC Starting Grant, ACOULOMODE (2013-18).

  12. Catalytic Synthesis of Substrate-Free, Aligned and Tailored High Aspect Ratio Multiwall Carbon Nanotubes in an Ultrasonic Atomization Head CVD Reactor

    Directory of Open Access Journals (Sweden)

    Fahad Ali Rabbani

    2016-01-01

    Full Text Available Chemical vapor deposition (CVD method has proven its benchmark, over other methods, for the production of different types of carbon nanotubes (CNT on commercial and lab scale. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head was used in a pilot-plant scale (height 274 cm, radius 25 cm for semicontinuous production of multiwall carbon nanotubes (MWCNTs. p-Xylene was used as a hydrocarbon precursor in which ferrocene was dissolved and provided the cracking catalyst. Atomization of the feed solution resulted in full and even dispersion of the catalytic solution. This dispersion led to the production of high aspect ratio MWCNTs (ranging from 8,000 to 12,000 at 850°C. Different experimental parameters affecting the quality and quantity of the produced CNTs were investigated. These included temperature, reaction time, and flow rate of the reaction and carrier gases. Different properties of the produced CNTs were characterized using SEM and TEM, while TGA was used to evaluate their purity. Specific surface area of selected samples was calculated by BET.

  13. Ultra-high aspect ratio Si nanowires fabricated with plasma etching: plasma processing, mechanical stability analysis against adhesion and capillary forces and oleophobicity.

    Science.gov (United States)

    Zeniou, A; Ellinas, K; Olziersky, A; Gogolides, E

    2014-01-24

    Room-temperature deep Si etching using time-multiplexed deep reactive ion etching (DRIE) processes is investigated to fabricate ultra-high aspect ratio Si nanowires (SiNWs) perpendicular to the silicon substrate. Nanopatterning is achieved using either top-down techniques (e.g. electron beam lithography) or colloidal polystyrene (PS) sphere self-assembly. The latter is a faster and more economical method if imperfections in diameter and position can be tolerated. We demonstrate wire radii from below 100 nm to several micrometers, and aspect ratios (ARs) above 100:1 with etching rates above 1 μm min(-1) using classical mass flow controllers with pulsing rise times of seconds. The mechanical stability of these nanowires is studied theoretically and experimentally against adhesion and capillary forces. It is shown that above ARs of the order of 50:1 for spacing 1 μm, SiNWs tend to bend due to adhesion forces between them. Such large adhesion forces are due to the high surface energy of silicon. Wetting the SiNWs with water and drying also gives rise to capillary forces. We find that capillary forces may be less important for SiNW collapse/bending compared to adhesion forces of dry SiNWs, contrary to what is observed for polymeric nanowires/nanopillars which have a much lower surface energy compared to silicon. Finally we show that SiNW arrays have oleophobic and superoleophobic properties, i.e. they exhibit excellent anti-wetting properties for a wide range of liquids and oils due to the re-entrant profile produced by the DRIE process and the well-designed spacing.

  14. Fabrication of high aspect ratio TiO{sub 2} and Al{sub 2}O{sub 3} nanogratings by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Shkondin, Evgeniy, E-mail: eves@fotonik.dtu.dk [Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark and Danish National Center for Micro- and Nanofabrication (DANCHIP), DK-2800 Kongens Lyngby (Denmark); Takayama, Osamu; Lavrinenko, Andrei V. [Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Lindhard, Jonas Michael; Larsen, Pernille Voss; Mar, Mikkel Dysseholm; Jensen, Flemming [Danish National Center for Micro- and Nanofabrication (DANCHIP), DK-2800 Kongens Lyngby (Denmark)

    2016-05-15

    The authors report on the fabrication of TiO{sub 2} and Al{sub 2}O{sub 3} nanostructured gratings with an aspect ratio of up to 50. The gratings were made by a combination of atomic layer deposition (ALD) and dry etch techniques. The workflow included fabrication of a Si template using deep reactive ion etching followed by ALD of TiO{sub 2} or Al{sub 2}O{sub 3}. Then, the template was etched away using SF{sub 6} in an inductively coupled plasma tool, which resulted in the formation of isolated ALD coatings, thereby achieving high aspect ratio grating structures. SF{sub 6} plasma removes silicon selectively without any observable influence on TiO{sub 2} or Al{sub 2}O{sub 3}, thus revealing high selectivity throughout the fabrication. Scanning electron microscopy was used to analyze every fabrication step. Due to nonreleased stress in the ALD coatings, the top parts of the gratings were observed to bend inward as the Si template was removed, thus resulting in a gradual change in the pitch value of the structures. The pitch on top of the gratings is 400 nm, and it gradually reduces to 200 nm at the bottom. The form of the bending can be reshaped by Ar{sup +} ion beam etching. The chemical purity of the ALD grown materials was analyzed by x-ray photoelectron spectroscopy. The approach presented opens the possibility to fabricate high quality optical metamaterials and functional nanostructures.

  15. Ultra-high aspect ratio Si nanowires fabricated with plasma etching: plasma processing, mechanical stability analysis against adhesion and capillary forces and oleophobicity

    Science.gov (United States)

    Zeniou, A.; Ellinas, K.; Olziersky, A.; Gogolides, E.

    2014-01-01

    Room-temperature deep Si etching using time-multiplexed deep reactive ion etching (DRIE) processes is investigated to fabricate ultra-high aspect ratio Si nanowires (SiNWs) perpendicular to the silicon substrate. Nanopatterning is achieved using either top-down techniques (e.g. electron beam lithography) or colloidal polystyrene (PS) sphere self-assembly. The latter is a faster and more economical method if imperfections in diameter and position can be tolerated. We demonstrate wire radii from below 100 nm to several micrometers, and aspect ratios (ARs) above 100:1 with etching rates above 1 μm min-1 using classical mass flow controllers with pulsing rise times of seconds. The mechanical stability of these nanowires is studied theoretically and experimentally against adhesion and capillary forces. It is shown that above ARs of the order of 50:1 for spacing 1 μm, SiNWs tend to bend due to adhesion forces between them. Such large adhesion forces are due to the high surface energy of silicon. Wetting the SiNWs with water and drying also gives rise to capillary forces. We find that capillary forces may be less important for SiNW collapse/bending compared to adhesion forces of dry SiNWs, contrary to what is observed for polymeric nanowires/nanopillars which have a much lower surface energy compared to silicon. Finally we show that SiNW arrays have oleophobic and superoleophobic properties, i.e. they exhibit excellent anti-wetting properties for a wide range of liquids and oils due to the re-entrant profile produced by the DRIE process and the well-designed spacing.

  16. Enhancing the Wettability of High Aspect-Ratio Through-Silicon Vias Lined with LPCVD Silicon Nitride or PE-ALD Titanium Nitride for Void-Free Bottom-Up Copper Electroplating

    NARCIS (Netherlands)

    Saadaoui, M.; van Zeijl, H.; Wien, W. H. A.; Pham, H. T. M.; Kwakernaak, C.; Knoops, H. C. M.; Kessels, W. M. M.; R. van de Sanden,; Voogt, F. C.; Roozeboom, F.; Sarro, P. M.

    2011-01-01

    One of the critical steps toward producing void-free and uniform bottom-up copper electroplating in high aspect-ratio (AR) through-silicon vias (TSVs) is the ability of the copper electrolyte to spontaneously flow through the entire depth of the via. This can be accomplished by reducing the concentr

  17. Preliminary Study of Polymer Removal in 0.25, 0.3, and 0.5 μm Ruthenium Storage Nodes and 0.11 μm, 10.9:1 High-Aspect-Ratio Trenches by Laser-Induced Etching

    Science.gov (United States)

    Kim, Yong-Gi; Cha, Byung Heon

    2005-07-01

    The demands for new etching technology are increasing because of new materials, such as, ruthenium (Ru), platinum (Pt), and iridium (Ir), that are now being used, and the strict critical dimension (C/D) controls required in today’s ultra large scale integrated (ULSI) circuit technology and dynamic random-access memory (DRAM) fabrication lines. Laser etching technology successfully etched organometallic polymers generated after reactive ion etching and ash processing in 0.25, 0.3, and 0.5 μm Ru storage nodes. In this study, the effects of the incident beam profile on the laser-induced etching of the polymers are investigated. Unevenness of the peak energy in the Gaussian beam profile creates unequal etching and heating effects on the polymer removal depending on the irradiating position of the line beam profile on the sample surface. This article discusses for the first time the preliminary results of laser-induced etching with a KrF laser to remove photoresist (PR) and polymer in 0.11 μm deep contact holes with a high-aspect-ratio 10.9:1 trench hole. How deep can the laser etching technology penetrate and strip the PR at a high aspect ratio (A/R) of 10.9:1 and a 0.11 μm hole size? The penetration depth for the PR removal was approximately 1 μm, which is about a 9.1:1 A/R in a 0.11 μm hole with a 1.2-μm-deep trench. Several promising points are discussed on the basis of laser etching in such a high A/R and small 0.11 μm contact hole. Laser-induced etching technology enabled a very uniform penetration depth without any fluctuations, and it also did not show any attack on the edge of the barrier material TiN.

  18. Fabrication of high aspect ratio TiOsub>2sub> and Alsub>2sub>O>3sub> nanogratings by atomic layer deposition

    DEFF Research Database (Denmark)

    Shkondin, Evgeniy; Takayama, Osamu; Michael-Lindhard, Jonas

    2016-01-01

    The authors report on the fabrication of TiO2 and Al2O3 nanostructured gratings with an aspect ratio of up to 50. The gratings were made by a combination of atomic layer deposition (ALD) and dry etch techniques. The workflow included fabrication of a Si template using deep reactive ion etching...

  19. Transonic steady- and unsteady-pressure measurements on a high-aspect-ratio supercritical-wing model with oscillating control surfaces

    Science.gov (United States)

    Sandford, M. C.; Ricketts, R. H.; Cazier, F. W., Jr.

    1980-01-01

    A supercritical wing with an aspect ratio of 10.76 and with two trailing-edge oscillating control surfaces is described. The semispan wing is instrumented with 252 static orifices and 164 in situ dynamic-pressure gages for studying the effects of control-surface position and motion on steady- and unsteady-pressures at transonic speeds. Results from initial tests conducted in the Langley Transonic Dynamics Tunnel at two Reynolds numbers are presented in tabular form.

  20. 大展弦比飞翼布局飞机的三轴稳定特性%Three-axis stability characteristics of flying wing with high aspect ratio

    Institute of Scientific and Technical Information of China (English)

    张子军; 王磊; 王立新; 王晋军

    2012-01-01

    飞翼布局飞机取消了平尾和垂尾,构型的改变和阻力方向舵的使用使其呈现出与常规布局飞机不同的三轴稳定特性.以大展弦比飞翼布局飞机为研究对象,开展了其三轴静、动稳定特性的研究;通过与常规大展弦比飞机进行对比,揭示了飞翼构型参数、典型飞行状态对其稳定性的影响规律;分析了阻力方向舵的偏转对此类飞机稳定性的影响.研究结果表明,大展弦比飞翼布局飞机的本体稳定性存在诸多的不足.%A flying wing cancels horizontal and vertical tails, but the changes of configuration and the use of drag rudder make it differ much from the conventional configuration aircraft in three-axis stability characteristics. The aircraft chosen for the study is a flying wing with high aspect ratio. Its three-axis static and dynamic stability characteristics are studied. Comparing with the conventional configuration aircraft with high aspect ratio, the effects of configuration parameters and typical flight condition on the stabilities of the flying wing are discussed. The impact of the drag rudder on the stabilities of such aircraft types is also analyzed. Results show that there are many deficiencies in the inherent three-axis stabilities of the high aspect ratio flying wing.

  1. 3-D Numerical Simulation and Analysis of Complex Fiber Geometry RaFC Materials with High Volume Fraction and High Aspect Ratio based on ABAQUS PYTHON

    Science.gov (United States)

    Jin, BoCheng

    2011-12-01

    Organic and inorganic fiber reinforced composites with innumerable fiber orientation distributions and fiber geometries are abundantly available in several natural and synthetic structures. Inorganic glass fiber composites have been introduced to numerous applications due to their economical fabrication and tailored structural properties. Numerical characterization of such composite material systems is necessitated due to their intrinsic statistical nature, which renders extensive experimentation prohibitively time consuming and costly. To predict various mechanical behavior and characterizations of Uni-Directional Fiber Composites (UDFC) and Random Fiber Composites (RaFC), we numerically developed Representative Volume Elements (RVE) with high accuracy and efficiency and with complex fiber geometric representations encountered in uni-directional and random fiber networks. In this thesis, the numerical simulations of unidirectional RaFC fiber strand RVE models (VF>70%) are first presented by programming in ABAQUS PYTHON. Secondly, when the cross sectional aspect ratios (AR) of the second phase fiber inclusions are not necessarily one, various types of RVE models with different cross sectional shape fibers are simulated and discussed. A modified random sequential absorption algorithm is applied to enhance the volume fraction number (VF) of the RVE, which the mechanical properties represents the composite material. Thirdly, based on a Spatial Segment Shortest Distance (SSSD) algorithm, a 3-Dimentional RaFC material RVE model is simulated in ABAQUS PYTHON with randomly oriented and distributed straight fibers of high fiber aspect ratio (AR=100:1) and volume fraction (VF=31.8%). Fourthly, the piecewise multi-segments fiber geometry is obtained in MATLAB environment by a modified SSSD algorithm. Finally, numerical methods including the polynomial curve fitting and piecewise quadratic and cubic B-spline interpolation are applied to optimize the RaFC fiber geometries

  2. Study on Locally Confined Deposition of Si Nanocrystals in High-Aspect-Ratio Si Nano-Pillar Array for Nano-Electronic and Nano-Photonic Applications

    Science.gov (United States)

    2010-02-23

    the applied electric field on the SiOx, mox is the effective electron mass in the SiOx, m is the free electron mass, B is the barrier height at the...compared to other mechanisms. For example, a simulated direct tunneling current with mox /m ratio of 0.26, the barrier height of 3.8, the oxide thickness...transport path,[24] which is give by * 2 exp exp 1Bthermionic q qVJ A T kT kT               , (5) where A* = 4 pqk2m*/h3 = 120 ( mox

  3. Influence of Alkyl Trimethyl Ammonium Bromides on Hydrothermal Formation of α-CaSO4·0.5H2O Whiskers with High Aspect Ratios

    Directory of Open Access Journals (Sweden)

    Ruosong Chen

    2017-01-01

    Full Text Available In this paper, the influence of alkyl trimethyl ammonium bromides (CnH2n+1(CH33NBr, n = 10, 12, 14, 16, 18, abbreviated as ATAB on the formation of alpha calcium sulfate hemihydrate (α-CaSO4·0.5H2O whiskers under a hydrothermal condition (135 °C, 3.0 h was analyzed. Specifically, it focuses on cetyl trimethyl ammonium bromide (C16H33(CH33NBr, abbreviated as CTAB. The rising CTAB concentration from 0 to 9.2 × 10−4 mol·L−1 led to the increase of the average aspect ratio of α-CaSO4·0.5H2O whiskers from 80 to 430, since the selective adsorption of CTAB on the negatively-charged side facets of the whiskers inhibited the growth of the whiskers along the direction normal to the lateral facets. The further increase of CTAB concentration above the critical micelle concentration (abbreviated as CMC showed little effect on the morphology of α-CaSO4·0.5H2O whiskers, considering that CTAB tended to form micelles instead of being adsorbed on the whisker surfaces. Similar phenomena were observed in other ATABs (n = 10, 12, 14, 18.

  4. Fractionation and Characterization of High Aspect Ratio Gold Nanorods Using Asymmetric-Flow Field Flow Fractionation and Single Particle Inductively Coupled Plasma Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Thao M. Nguyen

    2015-07-01

    Full Text Available Gold nanorods (GNRs are of particular interest for biomedical applications due to their unique size-dependent longitudinal surface plasmon resonance band in the visible to near-infrared. Purified GNRs are essential for the advancement of technologies based on these materials. Used in concert, asymmetric-flow field flow fractionation (A4F and single particle inductively coupled mass spectrometry (spICP-MS provide unique advantages for fractionating and analyzing the typically complex mixtures produced by common synthetic procedures. A4F fractions collected at specific elution times were analyzed off-line by spICP-MS. The individual particle masses were obtained by conversion of the ICP-MS pulse intensity for each detected particle event, using a defined calibration procedure. Size distributions were then derived by transforming particle mass to length assuming a fixed diameter. The resulting particle lengths correlated closely with ex situ transmission electron microscopy. In contrast to our previously reported observations on the fractionation of low-aspect ratio (AR GNRs (AR < 4, under optimal A4F separation conditions the results for high-AR GNRs of fixed diameter (≈20 nm suggest normal, rather than steric, mode elution (i.e., shorter rods with lower AR generally elute first. The relatively narrow populations in late eluting fractions suggest the method can be used to collect and analyze specific length fractions; it is feasible that A4F could be appropriately modified for industrial scale purification of GNRs.

  5. Injection Molding of High Aspect Ratio Nanostructures

    DEFF Research Database (Denmark)

    Matschuk, Maria; Larsen, Niels Bent

    We present a process for injection molding of 40 nm wide and >100 nm high pillars (pitch: 200 nm). We explored the effects of mold coatings and injection molding conditions on the replication quality of nanostructures in cyclic olefin copolymer. We found that optimization of molding parameters...

  6. Wind-tunnel investigation of longitudinal and lateral-directional stability and control characteristics of a 0.237-scale model of a remotely piloted research vehicle with a thick, high-aspect-ratio supercritical wing

    Science.gov (United States)

    Byrdsong, T. A.; Brooks, C. W., Jr.

    1980-01-01

    A 0.237-scale model of a remotely piloted research vehicle equipped with a thick, high-aspect-ratio supercritical wing was tested in the Langley 8-foot transonic tunnel to provide experimental data for a prediction of the static stability and control characteristics of the research vehicle as well as to provide an estimate of vehicle flight characteristics for a computer simulation program used in the planning and execution of specific flight-research mission. Data were obtained at a Reynolds number of 16.5 x 10 to the 6th power per meter for Mach numbers up to 0.92. The results indicate regions of longitudinal instability; however, an adequate margin of longitudinal stability exists at a selected cruise condition. Satisfactory effectiveness of pitch, roll, and yaw control was also demonstrated.

  7. Do floating orbits in extreme mass ratio binary black holes exist?

    CERN Document Server

    Kapadia, Shasvath J; Glampedakis, Kostas

    2013-01-01

    This paper examines the possibility of floating or non-decaying orbits for extreme mass ratio binary black holes. In the adiabatic approximation, valid in the extreme mass ratio case, if the orbital flux lost due to gravitational radiation reaction is compensated for by the orbital flux gained from the spins of the black holes via superradiant scattering (or, equivalently, tidal acceleration) the orbital decay would be stalled, causing the binary to "float". We show that this flux balance is not, in practice, possible for extreme mass ratio binary black holes with circular equatorial orbits; furthermore, adding eccentricity and inclination to the orbits will not significantly change this null result, thus ruling out the possibility of floating orbits for extreme mass ratio binary black holes. We also argue that binaries consisting of material bodies dense and massive enough to generate gravitational waves detectable by any kind of gravitational wave detector are also unlikely to float. Using a multipolar anal...

  8. The golden ratio in Schwarzschild-Kottler black holes

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, Norman [Universidad de Santiago de Chile, Departamento de Fisica, Facultad de Ciencia, Santiago 2 (Chile); Olivares, Marco [Universidad Diego Portales, Facultad de Ingenieria, Santiago (Chile); Villanueva, J.R. [Universidad de Valparaiso, Instituto de Fisica y Astronomia, Valparaiso (Chile)

    2017-02-15

    In this paper we show that the golden ratio is present in the Schwarzschild-Kottler metric. For null geodesics with maximal radial acceleration, the turning points of the orbits are in the golden ratio Φ = (√(5)-1)/2. This is a general result which is independent of the value and sign of the cosmological constant Λ. (orig.)

  9. Low-speed aerodynamic performance of a high-aspect-ratio supercritical-wing transport model equipped with full-span slat and part-span double-slotted flaps

    Science.gov (United States)

    Morgan, H. L., Jr.; Paulson, J. W., Jr.

    1979-01-01

    An investigation was conducted in the Langley V/STOL tunnel to determine the static longitudinal and lateral-directional aerodynamic characteristics of an advanced high-aspect-ratio supercritical-wing transport model equipped with a full-span leading-edge slat and part-span double-slotted trailing-edge flaps. This wide-body transport model was also equipped with spoiler and aileron control surfaces, flow-through nacelles, landing gear, movable horizontal tails, and interchangeable wing tips with aspect ratios of 10 and 12. The model was tested with leading-edge slat and trailing-edge flap combinations representative of cruise, climb, takeoff, and landing wing configurations. The tests were conducted at free-stream conditions corresponding to Reynolds numbers (based on mean geometric chord) of 0.97 to 1.63 x 10 to the 6th power and corresponding Mach numbers of 0.12 to 0.20, through an angle-of-attack range of -2 deg to 24 deg and a sideslip-angle range of -10 deg to 5 deg.

  10. On the Black Hole - Bulge Mass Ratios in Narrow-Line Seyfert 1 Galaxies

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    We present estimated ratios of the central black hole mass to the bulgemass (Mbh/Mbulge) for 15 Narrow Line Seyfert 1 galaxies (NLS1s). It is found thatNLS1s apparently have lower mass ratios: the average mass ratio is about 1 × 10-4with a spread of 2, which is one order of magnitude lower than for Broad Line AGNsand quiescent galaxies. This lower value, as compared to that established essentiallyfor all other types of galaxies, can be accounted for by an underestimation of theblack hole masses and an overestimation of the bulge masses in the NLS1s.

  11. Perturbative effects of spinning black holes in the extreme mass-ratio limit

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Hiroyuki; Campanelli, Manuela; Lousto, Carlos O; Zlochower, Yosef, E-mail: nakano@astro.rit.edu, E-mail: manuela@astro.rit.edu, E-mail: lousto@astro.rit.edu, E-mail: yosef@astro.rit.edu [Center for Computational Relativity and Gravitation, School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY 14623 (United States)

    2011-07-07

    Recently, we proposed an enhancement of the Regge-Wheeler-Zerilli formalism for first-order perturbations about a Schwarzschild background that includes first-order corrections due to the background black-hole spin in the black-hole perturbation approach. Using this formalism, we analytically investigate gravitational wave emission and linear momentum flux from a head-on collision of two spinning black holes in the extreme mass-ratio limit. The result derived in the lowest slow-motion and weak-field approximations here is consistent with the post-Newtonian calculation.

  12. Study on Static Test Technology for High-Aspect Ratio Wing of Full Scale Aircraft%全尺寸飞机大展弦比机翼静力试验技术研究

    Institute of Scientific and Technical Information of China (English)

    刘兴科; 刘冰; 张建锋

    2014-01-01

    In the bearing capability static test of wing structure,because of the high-aspect ratio, the large deformation will arouse load direction changed.Taking the full scale aircraft structure as research obj ect,a test loading technology is proposed,which can realize the extractive wing loading.The static test of a certain type aircraft structure solves the problems of large deforma-tion loading,which has great realistic significance and application value.%在大展弦比飞机的机翼承载能力试验中,试验加载方向会因其大变形发生变化。本文以全尺寸结构机翼为研究对象,提出一种试验加载技术,最大程度实现机翼载荷的准确施加。通过此静强度试验,很好地解决了机翼试验大变形加载问题,具有较大的现实意义和应用价值。

  13. Aeroelastic response for straight wing with high aspect ratio due to sharp edge gust%锐边突风对大展弦比机翼的气动弹性响应影响

    Institute of Scientific and Technical Information of China (English)

    刘伏虎; 马晓平

    2012-01-01

    基于Theodorsen非定常气动力理论,以大展弦比均匀直机翼为研究对象,建立了系统的气动弹性响应方程.选取二阶弯曲和二阶扭转模态,采用V-g法求解了系统的颤振速度.基于Kussner函数,建立了锐边突风系统模型,并推导了在弯曲和扭转模态阶数为Nw和Na下的系统状态方程,仿真研究了加入突风后系统的气动弹性响应.结果表明,加入突风后翼尖响应振幅增大.%Based on Theodorsen unsteady aerodynamics theory, the equation of aeroelastic response for straight wing with high aspect ratio is established. Flutter speed is determined for two bending modes and two torsional modes using V-g methods. The sharp edge gust system model is established and the system state equations are derived with Nw bending modes and Na torsional modes wing systems based on the function Kussner. The aeroelastic response of system shows that the amplitude oscillation becomes higher. The modeling method may offer reference for research of gust response.

  14. Self-organization and FORC-based magnetic characterization of ultra-high aspect ratio epitaxial Co nanostrips produced by oblique deposition on an ordered step-bunched silicon surface

    Science.gov (United States)

    Ognev, A. V.; Ermakov, K. S.; Samardak, A. Yu; Kozlov, A. G.; Sukovatitsina, E. V.; Davydenko, A. V.; Chebotkevich, L. A.; Stancu, A.; Samardak, A. S.

    2017-03-01

    Further development of microelectronics requires novel or improved technological approaches for device nanofabrication and functional properties characterization. In this paper, we studied the crystal structure and magnetic properties of epitaxial Co nanostrips with the average width of 32.6, 45.3, and 62.6 nm grown on a step-bunched Si(111)5.55 × 5.55-Cu/Cu surface. Technological conditions, under which the ultra-high aspect ratio (˜104) structurally solid, straight nanostrips of hcp-Co with crystallographic axis [0001] oriented along their long side can be grown, were determined. The dependence of the coercive force on the width of the nanostrips was demonstrated. Magnetization reversal through the transverse domain-wall nucleation and propagation in a Co nanostrip was defined with an analytical approach based on the Stoner-Wohlfarth model. Using the first-order reversal curve method, we analyzed the effect of nanostrip uniformity degree on magnetic behavior and the influence of the magnetostatic interactions on the coercive force of individual nanostrips.

  15. Film Cooling from Two Staggered Rows of Compound Angle Holes at High Blowing Ratios

    Directory of Open Access Journals (Sweden)

    Phillip M. Ligrani

    1996-01-01

    Full Text Available Experimental results are presented which describe the development and structure of flow downstream of two staggered rows of film-cooling holes with compound angle orientations at high blowing ratios. These film cooling configurations are important because they are frequently employed on the first stage of rotating blades of operating gas turbine engines. With this configuration, holes are spaced 3d apart in the spanwise direction, with inclination angles of 24 degrees, and angles of orientation of 50.5 degrees. Blowing ratios range from 0.5 to 4.0 and the ratio of injectant to freestream density is near 1.0. Results show that spanwise averaged adiabatic effectiveness, spanwise-averaged iso-energetic Stanton number ratios, surveys of streamwise mean velocity, and surveys of injectant distributions change by important amounts as the blowing ratio increases. This is due to injectant lift-off from the test surface just downstream of the holes which becomes more pronounced as blowing ratio increases.

  16. Mid-Infrared Selected Quasars I: Virial Black Hole Mass and Eddington Ratios

    CERN Document Server

    Dai, Y Sophia; Bergeron, Jacqueline; Fazio, Giovanni G; Huang, Jia-Sheng; Wilkes, Belinda J; Willmer, Christopher N A; Omont, Alain; Papovich, Casey

    2014-01-01

    We provide a catalog of 391 mid-infrared-selected (MIR, 24$\\mu$m) broad-emission-line (BEL, type 1) quasars in the 22 deg$^2$ SWIRE Lockman Hole field. This quasar sample is selected in the MIR from Spitzer MIPS with $S_{\\rm 24} > 400\\mu$Jy, jointly with an optical magnitude limit of r (AB) $ 19.1$. We then investigate the continuum luminosity and line profiles of these MIR quasars, and estimate their virial black hole masses and the Eddington ratios. The SMBH mass shows evidence of downsizing, though the Eddington ratios remain constant at $1 < z < 4$. Compared to point sources in the same redshift range, extended sources at $z < 1$ show systematically lower Eddington ratios. The catalog and spectra are publicly available online.

  17. LISA extreme-mass-ratio inspiral events as probes of the black hole mass function

    CERN Document Server

    Gair, Jonathan R; Volonteri, Marta

    2010-01-01

    One of the sources of gravitational waves for the proposed space-based gravitational wave detector, the Laser Interferometer Space Antenna (LISA), are the inspirals of compact objects into supermassive black holes in the centres of galaxies - extreme-mass-ratio inspirals (EMRIs). Using LISA observations, we will be able to measure the parameters of each EMRI system detected to very high precision. However, the statistics of the set of EMRI events observed by LISA will be more important in constraining astrophysical models than extremely precise measurements for individual systems. The black holes to which LISA is most sensitive are in a mass range that is difficult to probe using other techniques, so LISA provides an almost unique window onto these objects. In this paper we explore, using Bayesian techniques, the constraints that LISA EMRI observations can place on the mass function of black holes at low redshift. We describe a general framework for approaching inference of this type --- using multiple observ...

  18. Preparation and Cytotoxicity of High-aspect-ratio Gold Nanorods at Single Cell Level%大长径比金纳米棒的合成及其单细胞毒性研究

    Institute of Scientific and Technical Information of China (English)

    周海英; 周瑞; 熊斌; 何彦

    2012-01-01

    利用三步晶种生长法合成长径比约为14的大长径比金纳米棒(GNR),利用巯基十一酸(MUDA)对金纳米棒表面进行了生物适应性修饰,并在宏观水平上研究了修饰前后的金纳米棒在对细胞活性的影响.利用单细胞方法分别考察了修饰后的纳米金棒对细胞贴壁过程、增殖速率、细胞内ROS以及骨架排布的影响.虽然MTT细胞活性结果显示内吞后的金纳米棒对细胞无毒,但单细胞毒性分析方法发现,不同浓度纳米金棒对早期贴壁过程有较小的影响,且内吞的纳米金棒在一定程度上促进了细胞的增殖,而高浓度下纳米金棒引起了细胞内ROS含量的升高,并破坏了细胞内骨架纤维排布.本研究建立了用单细胞行为分析纳米颗粒对细胞毒性的方法,证明了以往仅仅利用MTT等宏观手段分析纳米材料生物适应性是不足的.纳米材料在生物医学领域的进一步应用还应考虑单细胞及分子水平上的毒性效应.%We have synthesized high-aspect-ratio gold nanorods (GNR) by using a three-step seed-mediated growth method. The aspect ratio of the GNRs is approximately 14. The modification of the GNRs was achieved by replacing the CTAB molecules on the surface of gold nanorods with the 11-mercaptoundecanoic (MUDA) molecules. The cytotoxicity of the as-prepared GNRs and their effects on endocytosis, adhesion, proliferation, intracellular reactive oxygen species (ROS) level and cytoskeleton of the cells were studied. Interestingly, by using the 3-(4, 5-dimethylthiazol-2-yl) 2,5-diphenyl-tetrazolium bromide (MTT) assay, the GNRs did not show a significant toxicity to HeLa cells. However, single cell viability assays showed that GNR uptake could influence the cell adhesion at the early stage, though the effect was not much, and the cell proliferation was promoted to some degree. Moreover, large amounts of GNR uptake will lead to increased intracellular ROS level and impaired the cell skeleton.

  19. Novel Rotating Hairy Black Hole in (2+1)-Dimensions and Shear Viscosity to Entropy Ratio

    Science.gov (United States)

    Naji, J.; Heshmatian, S.

    2014-08-01

    The novel rotating hairy black hole metric in (2 + 1) dimensions, which is an exact solution to the field equations of the Einstein-scalar AdS theory with a non-minimal coupling, considered in this paper and some hydrodynamics quantities such as diffusion constant and shear viscosity investigated. By using thermodynamics quantities such as temperature and entropy we can use diffusion constant to obtain shear viscosity and then calculate shear viscosity to entropy ratio.

  20. 高深宽比金属光栅制备及中红外波段传感特性%Fabrication and application of high aspect ratio metallic gratings for sensing in the mid-infrared region

    Institute of Scientific and Technical Information of China (English)

    郑改革; 陈云云; 徐林华; 赖敏

    2013-01-01

    A method for fabricating high aspect ratio (HAR) metallic gratings using nanoimprint together with sputtering and reactive-ion etching (RIE) was introduced. The reflection spectrum is measured by Fourier transform infrared (FT-IR) spectrometer in the mid-infrared (Mid-IR) region. The reflection peaks will appear just when the p-polarized light incident normally to the grating vector direction, which is very similar to the phenomenon of surface plasmon resonance. This is the so-called spoof surface plasmon resonance (SSPR). Theoretical analysis based on rigorous coupled wave showed that spoof surface plasmon resonance is very sensitive to the change of refractive index in the surface of the metal. Thus this phenomenon has its potential use as a refractive index sensor. In addition, the shift of resonance wavelength with the refractive index of the metal surface is completely linear. The refractive index sensitivity of the Mid-IR SPR sensor are predicted to be 1600 nm per refractive index unit (1600 nm/RIU) and 5000 nm/RIU for the positive and negative order diffractive waves, respectively. The corresponding figure of merits of the whole system is predicted to be 20 RIU -1 and 60 RIU-1, respectively. The list of applicable target materials will certainly expand greatly if mid-IR SPR-based sensors are developed.%利用纳米压印结合溅射和反应离子刻蚀工艺制备了具有高深宽比的金光栅,使用傅里叶变换红外光谱仪测得了反射谱线.测量结果显示,只在p偏振光垂直于光栅矢量方向入射条件下才存在共振反射峰,证明了“伪表面等离子体激元波”的存在.基于严格耦合波分析理论计算了金属光栅的反射率,研究了其作为中红外波段波长调制型表面等离子体共振传感器的可行性.数值计算表明负级次衍射光波对应的共振反射峰的移动能获得较高的波长灵敏度.对于深宽比为10的金光栅结构,+1级次和-3级次衍射光波对应

  1. Extreme mass ratio inspiral rates: dependence on the massive black hole mass

    CERN Document Server

    Hopman, Clovis

    2009-01-01

    We study the rate at which stars spiral into a massive black hole (MBH) due to the emission of gravitational waves (GWs), as a function of the mass M of the MBH. In the context of our model, it is shown analytically that the rate approximately depends on the MBH mass as M^{-1/4}. Numerical simulations confirm this result, and show that for all MBH masses, the event rate is highest for stellar black holes, followed by white dwarfs, and lowest for neutron stars. The Laser Interferometer Space Antenna (LISA) is expected to see hundreds of these extreme mass ratio inspirals per year. Since the event rate derived here formally diverges as M->0, the model presented here cannot hold for MBHs of masses that are too low, and we discuss what the limitations of the model are.

  2. Intermediate-mass-ratio black-hole binaries: numerical relativity meets perturbation theory.

    Science.gov (United States)

    Lousto, Carlos O; Nakano, Hiroyuki; Zlochower, Yosef; Campanelli, Manuela

    2010-05-28

    We study black-hole binaries in the intermediate-mass-ratio regime 0.01≲q≲0.1 with a new technique that makes use of nonlinear numerical trajectories and efficient perturbative evolutions to compute waveforms at large radii for the leading and nonleading (ℓ, m) modes. As a proof-of-concept, we compute waveforms for q=1/10. We discuss applications of these techniques for LIGO and VIRGO data analysis and the possibility that our technique can be extended to produce accurate waveform templates from a modest number of fully nonlinear numerical simulations.

  3. Uncertainties of the masses of black holes and Eddington ratios in AGN

    CERN Document Server

    Collin, S

    2006-01-01

    Black hole masses in Active Galactic Nuclei have been determined in 35 objects through reverberation mapping of the emission line region. I mention some uncertainties of the method, such as the ``scale factor'' relating the Virial Product to the mass, which depends on the unknown structure and dynamics of the Broad Line Region. When the black hole masses are estimated indirectly using the empirical size-luminosity relation deduced from this method, the uncertainties can be larger, especially when the relation is extrapolated to high and low masses and/or luminosities. In particular they lead to Eddington ratios of the order of unity in samples of Narrow Line Seyfert 1. As the optical-UV luminosity is provided by the accretion disk, the accretion rates can be determined and are found to be much larger than the Eddington rates. So, accretion must be performed at a super-critical rate through a slim disk, resulting in rapid growth of the black holes. The alternative is that the mass determination is wrong at thi...

  4. Dusty Gas Accretion onto Massive Black Holes and Infrared Diagnosis of the Eddington Ratio

    Science.gov (United States)

    Yajima, Hidenobu; Ricotti, Massimo; Park, KwangHo; Sugimura, Kazuyuki

    2017-09-01

    Evidence for dust around supermassive black holes (SMBHs) in the early universe is strongly suggested by recent observations. However, the accretion mechanism of SMBHs in dusty gas is not well understood yet. We investigate the growth of intermediate-mass black holes (IMBHs) of ˜ {10}4{--}{10}6 {M}⊙ in dusty clouds by using one-dimensional radiative-hydrodynamics simulations. We find that the accretion of dusty gas onto IMBHs proceeds gently with small fluctuations of the accretion rate, whereas that of pristine gas causes more violent periodic bursts. At dust-to-gas mass ratios similar to the solar neighborhood, the time-averaged luminosity becomes smaller than that for primordial gas by one order of magnitude and the time-averaged Eddington ratio ranges from ˜ {10}-4 to ˜ {10}-2 in clouds with initial gas densities of {n}{{H}}=10{--}1000 {{cm}}-3. Our calculations show that the effect of dust opacity alone is secondary compared to the radiation pressure on dust in regulating the BH growth. We also derive spectral energy distributions at IR bands by calculating dust thermal emission and show that the flux ratio between λ ≲ 20 μ {{m}} and ≳ 100 μ {{m}} is closely related to the Eddington ratio. Thermal emission from hot dust near the BH dominates only during the phase of high accretion, producing higher flux density at ≲ 20 μ {{m}}. Therefore, we suggest that a combination of mid-IR observations by the James Webb Space Telescope and far-IR observations by ALMA or Spitzer can be used to estimate the Eddington ratio of massive BHs. We also extend our simple modeling to SMBHs of {10}8{--}{10}9 {M}⊙ and show that ALMA can detect SMBHs of ˜ {10}9 {M}⊙ at z≳ 5.

  5. Synchrotron peak luminosity,black hole mass and Eddington ratio for SDSS flat-spectrum radio quasars

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    For a sample of 185 flat-spectrum radio quasars(FSRQs) constructed from the SDSS DR3 quasar catalog,we found a significant correlation between the synchrotron peak luminosity and both the black hole mass and Eddington ratio.This implies that the physics of its jet formation is not only tightly related with the black hole mass,but also with the accretion rate.We verify that the synchrotron peak luminosity can be a better indicator of jet emission than 5 GHz luminosity,through comparing the relationships between each of these two parameters and both black hole mass and Eddington ratio.The fundamental plane of black hole activity for our FSRQs is established as Lr ∝ L0x.80 ± 0.06 Mbh -0.04 ± 0.09 with a weak dependence on black hole mass,however,the scatter is significant.

  6. The typical mass ratio and typical final spin in supermassive black hole mergers

    CERN Document Server

    Gergely, László Á

    2012-01-01

    We prove that merging supermassive black holes (SMBHs) typically have neither equal masses, nor is their mass ratio too extreme. The majority of such mergers fall into the mass ratio range of 1:30 to 1:3, implying a spin flip during the inspiral. We also present a simple expression for the final spin $\\chi_{f}$ of the emerging SMBH, as function of the mass ratio, initial spin magnitudes, and orientation of the spins with respect to the orbital plane and each other. This formula approximates well more cumbersome expressions obtained from the fit with numerical simulations. By integrating over all equally likely orientations for precessing mergers we determine a lower approximant to the final spin distribution as function of the mass ratio alone. By folding this with the derived mass ratio dependent merger rate we derive a lower bound to the typical final spin value after mergers. We repeat the procedure deriving an upper bound for the typical spin in the case when the spins are aligned to the orbital angular m...

  7. 大展弦比机翼非线性颤振剪裁设计新方法%A NEW METHOD ON FLUTTER TAILORING TECHNIQUES OF HIGH-ASPECT-RATIO WINGS

    Institute of Scientific and Technical Information of China (English)

    任智毅; 金海波; 丁运亮

    2014-01-01

    A method was presented to analyze the nonlinear flutter.Based on this method,the flutter character-istics of the high aspect wing were illustrated.The numerical results show that the flutter speed is decreased when the first horizontal bending mode involved.Secondly,this study discussed how the main direction of the compos-ite influenced the character of the nonlinear vibration and flutter,and established the method of the flutter clip-ping to the high aspect wing.And the result shows that the stiffness of structure can be changed by changing the main direction of the composite.It mainly changes the horizontal bending mode,makes the main direction tend to the trailing edge,and then makes the section line move to the leading edge.Further analyzing the nonlinear flut-ter reveals that it is the changing of the horizontal bending mode that causes the flutter speed change obviously. And by the section line of this mode moves ahead,the flutter speed will become larger.In the study,two exam-ples were illustrated to validate its truthiness.%针对大展弦比机翼水平弯曲模态参与耦合颤振问题,首先用考虑几何非线性的颤振分析方法研究了某大展弦比机翼的颤振特性,结果表明水平一弯模态参与耦合降低了机翼传统模式的线性颤振速度;然后研究了复合材料的铺层主刚度方向角对机翼非线性振动特性和颤振特性的影响规律,提出了大展弦比机翼非线性颤振剪裁设计的新方法。结果表明主刚度方向角的变化主要引起了水平一弯模态振型的改变,一般表现为主刚度方向角从机翼后梁向后缘偏转,该阶模态的相对扭转振型节线位置向前缘移动;反之,该节线位置后移。进一步非线性颤振分析,发现水平一弯模态振型的变化引起了该阶模态参与耦合颤振速度的明显改变,主要表现为该颤振型的颤振速度随该阶模态的相对扭转振型节线位置前移量的增加而增

  8. Mass ratio determination from Halpha lines in Black-Hole X-ray transients

    CERN Document Server

    Casares, Jorge

    2016-01-01

    We find that the mass ratio q in quiescent black hole (BH) X-ray transients is tightly correlated with the ratio of the double peak separation (DP) to the full-width-half maximum (FWHM) of the Halpha emission line, log q = -6.88 -23.2 log (DP/FWHM). The correlation is explained through the efficient truncation of the outer disc radius by the 3:1 resonance with the companion star. This is the dominant tidal interaction for extreme mass ratios q=M2/M1<~0.25, the realm of BH (and some neutron star) X-ray transients. Mass ratios can thus be estimated with a typical uncertainty of ~32%, provided that the Halpha profile used to measure DP/FWHM is an orbital phase average. We apply the DP/FWHM-q relation to the three faint BH transients XTE J1650-500, XTE J1859+226 and Swift J1357-0933 and predict q=0.026 (+0.038-0.007), 0.049 (+0.023-0.012) and 0.040 (+0.003-0.005), respectively. This new relation, together with the FWHM-K2 correlation presented in Paper I (casares 2015) allows the extraction of fundamental para...

  9. Kicking massive black holes off clusters: Intermediate-mass ratio inspirals

    CERN Document Server

    Konstantinidis, Symeon; Kokkotas, Kostas D

    2011-01-01

    Contrary to supermassive and stellar-mass black holes (SBHs), the existence of intermediate-mass black holes (IMBHs) with masses ranging between 100 and 10,000 Msun has not yet been confirmed. The main problem in the detection is that the innermost stellar kinematics of globular clusters (GCs), the natural loci to IMBHs, are very difficult to resolve. However, if IMBHs reside in the center of GCs, a possibility is that they interact dynamically with their enviroment. A binary formed with the IMBH and a compact object of the GC would naturally lead to a prominent source of gravitational radiation, detectable with future observatories. We run for the first time direct-summation integrations of GCs with an IMBH including the dynamical evolution of the IMBH with the stellar system and relativistic effects, such as energy loss in gravitational waves (GWs) and periapsis shift, and gravitational recoil. We find in one of our models an intermediate-mass ratio inspiral (IMRI), which leads to a merger with a recoiling ...

  10. Exploring the unusually high black hole-to-bulge mass ratios in NGC4342 and NGC4291: the asynchronous growth of bulges and black holes

    CERN Document Server

    Bogdan, Akos; Zhuravleva, Irina; Mihos, J Christopher; Kraft, Ralph P; Harding, Paul; Guo, Qi; Li, Zhiyuan; Churazov, Eugene; Vikhlinin, Alexey; Nulsen, Paul E J; Schindler, Sabine; Jones, Christine

    2012-01-01

    We study two nearby, early-type galaxies, NGC4342 and NGC4291, that host unusually massive black holes relative to their low stellar mass. The observed black hole-to-bulge mass ratios of NGC4342 and NGC4291 are ~6.9% and ~1.9%, respectively, which significantly exceed the typical observed ratio of ~0.2%. As a consequence of the exceedingly large black hole-to-bulge mass ratios, NGC4342 and NGC4291 are ~5.1 sigma and ~3.4 sigma outliers from the M_BH - M_bulge scaling relation, respectively. In this paper we explore the origin of the unusually high black hole-to-bulge mass ratio. Based on Chandra X-ray observations of the hot gas content of NGC4342 and NGC4291, we compute gravitating mass profiles, and conclude that both galaxies reside in massive dark matter halos, which extend well beyond the stellar light. The presence of dark matter halos around NGC4342 and NGC4291 and a deep optical image of the environment of NGC4342 indicate that tidal stripping, in which >90% of the stellar mass was lost, cannot explai...

  11. Spin–orbit precession for eccentric black hole binaries at first order in the mass ratio

    Science.gov (United States)

    Akcay, Sarp; Dempsey, David; Dolan, Sam R.

    2017-04-01

    We consider spin–orbit (‘geodetic’) precession for a compact binary in strong-field gravity. Specifically, we compute ψ, the ratio of the accumulated spin-precession and orbital angles over one radial period, for a spinning compact body of mass m 1 and spin s 1, with {{s}1}\\ll Gm12/c , orbiting a non-rotating black hole. We show that ψ can be computed for eccentric orbits in both the gravitational self-force and post-Newtonian frameworks, and that the results appear to be consistent. We present a post-Newtonian expansion for ψ at next-to-next-to-leading order, and a Lorenz-gauge gravitational self-force calculation for ψ at first order in the mass ratio. The latter provides new numerical data in the strong-field regime to inform the effective one-body model of the gravitational two-body problem. We conclude that ψ complements the Detweiler redshift z as a key invariant quantity characterizing eccentric orbits in the gravitational two-body problem.

  12. Spin-orbit precession for eccentric black hole binaries at first order in the mass ratio

    CERN Document Server

    Akcay, Sarp; Dolan, Sam

    2016-01-01

    We consider spin-orbit ("geodetic") precession for a compact binary in strong-field gravity. Specifically, we compute $\\psi$, the ratio of the accumulated spin-precession and orbital angles over one radial period, for a spinning compact body orbiting a non-rotating black hole. We show that $\\psi$ can be computed for eccentric orbits in both the gravitational self-force and post-Newtonian frameworks, and that the results appear to be consistent. We present a post-Newtonian expansion for $\\psi$ at next-to-next-to-leading order, and a Lorenz-gauge gravitational self-force calculation for $\\psi$ at first order in the mass ratio. The latter provides new numerical data in the strong-field regime to inform the Effective One-Body model of the gravitational two-body problem. We conclude that $\\psi$ complements the Detweiler redshift $z$ as a key invariant quantity characterizing eccentric orbits in the gravitational two-body problem.

  13. 11-orbit inspiral of a mass ratio 4:1 black-hole binary

    Energy Technology Data Exchange (ETDEWEB)

    Sperhake, U; Sopuerta, C F [Institute of Space Sciences (CSIC-IEEC), Campus UAB, Torre C5 Parells, 08193 Bellaterra (Spain); Bruegmann, B; Mueller, D, E-mail: sperhake@ieec.uab.es [Theoretisch Physikalisches Institut, Friedrich Schiller Universitaet, Max-Wien Platz 1, 07743 Jena (Germany)

    2011-07-07

    We analyse an 11-orbit inspiral of a non-spinning black-hole binary with mass ratio q {identical_to} M{sub 1}/M{sub 2} = 4. The numerically obtained gravitational waveforms are compared with post-Newtonian (PN) predictions including several subdominant multipoles up to multipolar indices (l = 5, m = 5). We find that (i) numerical and post-Newtonian predictions of the phase of the (2, 2) mode accumulate a phase difference of about 0.35 rad at the PN cut-off frequency M{omega} = 0.1 for the Taylor T1 approximant when numerical and PN waveforms are matched over a window in the early inspiral phase; (ii) in contrast to previous studies of equal mass and specific spinning binaries, we find the Taylor T4 approximant to agree less well with numerical results, provided the latter are extrapolated to infinite extraction radius; (iii) extrapolation of gravitational waveforms to infinite extraction radius is particularly important for subdominant multipoles with l {ne} m; (iv) 3PN terms in post-Newtonian multipole expansions significantly improve the agreement with numerical predictions for subdominant multipoles.

  14. Laser Micro-Hole Drilling of Soda-Lime Glass with Femtosecond Pulses

    Institute of Scientific and Technical Information of China (English)

    AN Ran; LI Yan; DOU Yan-Ping; FANG Ying; YANG Hong; GONG Qi-Huang

    2004-01-01

    @@ Using tightly focused femtosecond laser pulses, we have drilled micro-holes from the front and rear surface of soda-lime glass in ambient air. The machined holes have small aspect ratio or irregular inner walls. When the drilling is conducted from the rear surface in contact with distilled water, a good quality micro-hole with a high aspect ratio can be obtained. The corresponding formation mechanisms are investigated.

  15. MEMS acoustic emission transducers designed with high aspect ratio geometry

    Science.gov (United States)

    Saboonchi, H.; Ozevin, D.

    2013-09-01

    In this paper, micro-electro-mechanic systems (MEMS) acoustic emission (AE) transducers are manufactured using an electroplating technique. The transducers use a capacitance change as their transduction principle, and are tuned to the range 50-200 kHz. Through the electroplating technique, a thick metal layer (20 μm nickel + 0.5 μm gold) is used to form a freely moving microstructure layer. The presence of the gold layer reduces the potential corrosion of the nickel layer. A dielectric layer is deposited between the two electrodes, thus preventing the stiction phenomenon. The transducers have a measured quality factor in the range 15-30 at atmospheric pressure and are functional without vacuum packaging. The transducers are characterized using electrical and mechanical tests to identify the capacitance, resonance frequency and damping. Ultrasonic wave generation using a Q-switched laser shows the directivity of the transducer sensitivity. The comparison of the MEMS transducers with similar frequency piezoelectric transducers shows that the MEMS AE transducers have better response characteristics and sensitivity at the resonance frequency and well-defined waveform signatures (rise time and decay time) due to pure resonance behavior in the out-of-plane direction. The transducers are sensitive to a unique wave direction, which can be utilized to increase the accuracy of source localization by selecting the correct wave velocity at the structures.

  16. Downsizing of single crystalline high aspect ratio tungsten nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Milenkovic, Srdjan [IMDEA Materials Institute, Eric Kandel 2, 28906, Getafe (Spain); Drensler, Stefanie [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Hassel, Achim Walter [Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University, Altenberger Str. 69, 4040, Linz (Austria); Christian Doppler Laboratory for Combinatorial Oxide Chemistry, Institute for Chemical Technology of Inorganic Materials, Johannes Kepler University Linz, Altenberger Str. 69, 4040, Linz (Austria)

    2015-06-15

    Directional solidification of eutectic NiAl-W alloys offers an intuitive method to produce tungsten nanowires. Through the use of two different methods, the well-established Bridgman method and a newer type floating zone method, the direct influence of process parameters, like the withdrawal rate and the temperature gradient, onto the sample microstructure were studied. The sharp temperature gradient, built up using a four mirror system focusing the light emitted by halogen lamps inside the optical floating zone furnace allows producing nanowires with a diameter as small as 75 nm. Differences in the solid/liquid interface morphology depending on the solidification method used are discussed. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Active Aeroelastic Tailoring of High-Aspect-Ratio Composite Wings

    Science.gov (United States)

    2005-09-01

    34 - 26000 , ......... . . . ...... . . .... .. .......................... ... - - ----------- 21000 ... ........... ~0 50 LOAD... ISO 5: B s mission....f Figure 5: Basic mission profile 7 Figure 6: Baseline single-wing and joined-wing vehicles 3.1 Baseline vehicles Three sets

  18. High aspect ratio template and method for producing same

    Science.gov (United States)

    Sakamoto, Jeff S. (Inventor); Weiss, James R. (Inventor); Fleurial, Jean-Pierre (Inventor); Kisor, Adam (Inventor); Tuszynski, Mark (Inventor); Stokols, Shula (Inventor); Holt, Todd Edward (Inventor); Welker, David James (Inventor); Breckon, Christopher David (Inventor)

    2010-01-01

    Millimeter to nano-scale structures manufactured using a multi-component polymer fiber matrix are disclosed. The use of dissimilar polymers allows the selective dissolution of the polymers at various stages of the manufacturing process. In one application, biocompatible matrixes may be formed with long pore length and small pore size. The manufacturing process begins with a first polymer fiber arranged in a matrix formed by a second polymer fiber. End caps may be attached to provide structural support and the polymer fiber matrix selectively dissolved away leaving only the long polymer fibers. These may be exposed to another product, such as a biocompatible gel to form a biocompatible matrix. The polymer fibers may then be selectively dissolved leaving only a biocompatible gel scaffold with the pores formed by the dissolved polymer fibers.

  19. Metallization of high aspect ratio, out of plane structures

    DEFF Research Database (Denmark)

    Vazquez, Patricia; Dimaki, Maria; Svendsen, Winnie Edith

    2009-01-01

    This work is dedicated to developing a novel three dimensional structure for electrochemical measurements in neuronal studies. The final prototype will allow not only for the study and culture on chip of neuronal cells, but also of brain tissue. The use of out-of-plane electrodes instead of planar......, since the coverage of the side walls of almost vertical pillars is not trivial by standard processes in a clean room facility. This paper will discuss the different steps taken towards this goal and present the results that we have obtained so far....

  20. Observational Constraints on Quasar Black Hole Mass Distributions, Eddington Ratio Distributions, and Lifetimes

    DEFF Research Database (Denmark)

    Kelly, Brandon C.; Vestergaard, Marianne; Fan, X.

    2010-01-01

    I will present the black hole mass function (BHMF) of broad line quasars in the SDSS DR3. We employ a powerful Bayesian statistical technique that corrects for incompleteness and the statistical uncertainty in the mass estimates. We find evidence that the most massive black hole appeared as quasars...... earlier in the universe, and that most quasars are not radiating at or near the Eddington limit. I will also present constraints on the quasar lifetime and maximum black hole mass, derived from the mass functions....

  1. Observational Constraints on Quasar Black Hole Mass Distributions, Eddington Ratio Distributions, and Lifetimes

    DEFF Research Database (Denmark)

    Kelly, Brandon C.; Vestergaard, Marianne; Fan, X.

    2010-01-01

    I will present the black hole mass function (BHMF) of broad line quasars in the SDSS DR3. We employ a powerful Bayesian statistical technique that corrects for incompleteness and the statistical uncertainty in the mass estimates. We find evidence that the most massive black hole appeared as quasars...... earlier in the universe, and that most quasars are not radiating at or near the Eddington limit. I will also present constraints on the quasar lifetime and maximum black hole mass, derived from the mass functions....

  2. Correlation of microstructure, tensile properties and hole expansion ratio in cold rolled advanced high strength steels

    Science.gov (United States)

    Terrazas, Oscar R.

    The demand for advanced high strength steels (AHSS) with higher strengths is increasing in the automotive industry. While there have been major improvements recently in the trade-off between ductility and strength, sheared-edge formability of AHSS remains a critical issue. AHSS sheets exhibit cracking during stamping and forming operations below the predictions of forming limits. It has become important to understand the correlation between microstructure and sheared edge formability. The present work investigates the effects of shearing conditions, microstructure, and tensile properties on sheared edge formability. Seven commercially produced steels with tensile strengths of 1000 +/- 100 MPa were evaluated: five dual-phase (DP) steels with different compositions and varying microstructural features, one trip aided bainitic ferrite (TBF) steel, and one press-hardened steel tempered to a tensile strength within the desired range. It was found that sheared edge formability is influenced by the martensite in DP steels. Quantitative stereology measurements provided results that showed martensite size and distribution affect hole expansion ratio (HER). The overall trend is that HER increases with more evenly dispersed martensite throughout the microstructure. This microstructure involves a combination of martensite size, contiguity, mean free distance, and number of colonies per unit area. Additionally, shear face characterization showed that the fracture and burr region affect HER. The HER decreases with increasing size of fracture and burr region. With a larger fracture and burr region more defects and/or micro-cracks will be present on the shear surface. This larger fracture region on the shear face facilitates cracking in sheared edge formability. Finally, the sheared edge formability is directly correlated to true fracture strain (TFS). The true fracture strain from tensile samples correlates to the HER values. HER increases with increasing true fracture strain.

  3. N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes

    Science.gov (United States)

    Baumgardt, H.

    2016-10-01

    We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well observed clusters we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of =1.98 ± 0.03, which agrees very well with the expected M/L ratio if the initial mass function (IMF) of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease of the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globular clusters are incompatible with the presence of intermediate-mass black holes (IMBHs) with more than a few thousand M⊙ in them. The only clear exception is ω Cen, where the velocity dispersion profile provides strong evidence for the presence of a ˜40,000 M⊙ IMBH in the centre of the cluster.

  4. N -body modelling of globular clusters: masses, mass-to-light ratios and intermediate-mass black holes

    Science.gov (United States)

    Baumgardt, H.

    2017-01-01

    We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well-observed clusters, we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of =1.98 ± 0.03, which agrees very well with the expected M/L ratio if the initial mass function (IMF) of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease in the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globular clusters are incompatible with the presence of intermediate-mass black holes (IMBHs) with more than a few thousand M⊙ in them. The only clear exception is ω Cen, where the velocity dispersion profile provides strong evidence for the presence of a ˜40 000 M⊙ IMBH in the centre of the cluster.

  5. Black hole-neutron star mergers at realistic mass ratios: Equation of state and spin orientation effects

    CERN Document Server

    Foucart, Francois; Duez, Matthew D; Kidder, Lawrence E; MacDonald, Ilana; Ott, Christian D; Pfeiffer, Harald P; Scheel, Mark A; Szilagyi, Bela; Teukolsky, Saul A

    2012-01-01

    Black hole-neutron star mergers resulting in the disruption of the neutron star and the formation of an accretion disk and/or the ejection of unbound material are prime candidates for the joint detection of gravitational-wave and electromagnetic signals when the next generation of gravitational-wave detectors comes online. However, the disruption of the neutron star and the properties of the post-merger remnant are very sensitive to the parameters of the binary. In this paper, we study the impact of the radius of the neutron star and the alignment of the black hole spin for systems within the range of mass ratio currently deemed most likely for field binaries (M_BH ~ 7 M_NS) and for black hole spins large enough for the neutron star to disrupt (J/M^2=0.9). We find that: (i) In this regime, the merger is particularly sensitive to the radius of the neutron star, with remnant masses varying from 0.3M_NS to 0.1M_NS for changes of only 2 km in the NS radius; (ii) 0.01-0.05M_sun of unbound material can be ejected w...

  6. Binary black hole coalescence in the extreme-mass-ratio limit: testing and improving the effective-one-body multipolar waveform

    CERN Document Server

    Bernuzzi, Sebastiano; Zenginoglu, Anil

    2010-01-01

    We discuss the properties of the effective-one-body (EOB) multipolar gravitational waveform emitted by nonspinning black-hole binaries of masses $\\mu$ and $M$ in the extreme-mass-ratio limit, $\\mu/M=\

  7. Secular evolution and a non-evolving black hole to galaxy mass ratio in the last 7 Gyr

    CERN Document Server

    Cisternas, Mauricio; Bongiorno, Angela; Inskip, Katherine J; Impey, Chris D; Koekemoer, Anton M; Merloni, Andrea; Salvato, Mara; Trump, Jonathan R

    2011-01-01

    We present new constraints on the ratio of black hole (BH) mass to total galaxy stellar mass at 0.3ratio to estimate the stellar masses (M_*). The M_BH-M_* ratio shows a zero offset with respect to the local relation for galactic bulge masses, and we also find no evolution in the mass ratio M_BH/M_*=(1+z)^{0.02+-0.34} up to z~0.9. Interestingly, at the high-M_BH end there is a positive offset from the z=0 relation, which can be fully explained by a mass function bias with a cosmic scatter of 0.3, reaffirming that the intrinsic distribution is consistent with zero evolution. From our results we conclude that since z~0.9 no ...

  8. N-body modeling of globular clusters: Masses, mass-to-light ratios and intermediate-mass black holes

    CERN Document Server

    Baumgardt, Holger

    2016-01-01

    We have determined the masses and mass-to-light ratios of 50 Galactic globular clusters by comparing their velocity dispersion and surface brightness profiles against a large grid of 900 N-body simulations of star clusters of varying initial concentration, size and central black hole mass fraction. Our models follow the evolution of the clusters under the combined effects of stellar evolution and two-body relaxation allowing us to take the effects of mass segregation and energy equipartition between stars self-consistently into account. For a subset of 16 well observed clusters we also derive their kinematic distances. We find an average mass-to-light ratio of Galactic globular clusters of $=1.98 \\pm 0.03$, which agrees very well with the expected M/L ratio if the initial mass function of the clusters was a standard Kroupa or Chabrier mass function. We do not find evidence for a decrease of the average mass-to-light ratio with metallicity. The surface brightness and velocity dispersion profiles of most globul...

  9. Radio Luminosity,Black Hole Mass and Eddington Ratio for Quasars from the Sloan Digital Sky Survey

    Institute of Scientific and Technical Information of China (English)

    Wei-Hao Bian; Yan-Mei Chen; Chen Hu; Kai Huang; Yan Xu

    2008-01-01

    We investigate the MBH-O'.relation for radio-loud quasars with redshift z<0.83 in Data Release 3 of the Sloan Digital Sky Survey (SDSS).The sample consists of 3772 quasars with better models of the H/~ and [O III] lines and available radio luminosity,including 306 radio-loud quasars,3466 radio-quiet quasars with measured radio luminosity or upper-limit of radio luminosity (181 radio-quiet quasars with measured radio luminosity).The virial supermassive black hole mass (MBH) is calculated from the broad H/line,and the host stellar velocity dispersion (σ*) is traced by the core [O III] gaseous velocity dispersion.The radio luminosity and radio loudness are derived from the FIRST catalog.Our results are as follows:(1) For radio-quiet quasars,we confirm that there is no obvious deviation from the MBH-O".relation defined for inactive galaxies when the uncertainties in MBH and the luminosity bias are concerned.(2) We find that the radio-loud quasars deviate more from the MBH-σ.relation than do the radio-quiet quasars.This deviation is only partly due to a possible cosmological evolution of the MBH-σ* relation and the luminosity bias.(3) The radioluminosity is proportional to M128+0.23-0.16 BH(LBol/LEdd)1.29+0.31-0.24 for radio-quiet quasars and to M3.10+0.6.-0.70(LBol.LEdd)4.18+1.40-1.10 for radio-loud quasars.The weaker dependence of the radio luminosity on the mass and the Eddington ratio for radio-loud quasars shows that other physical effects would account for their radio luminosities,such as the spin of the black hole.

  10. Mergers of neutron star black hole binaries with small mass ratios: nucleosynthesis, gamma-ray bursts and electromagnetic transients

    CERN Document Server

    Rosswog, S

    2005-01-01

    I discuss simulations of the coalescence of black hole neutron star binary systems with black hole masses between 14 and 20 \\msun. The calculations use a three-dimensional smoothed particle hydrodynamics code, a temperature-dependent, nuclear equation of state and a multi-flavor neutrino scheme. General relativistic effects are mimicked using the \\Pacz-Wiita pseudo-potential and gravitational radiation reaction forces. Opposite to previous, purely Newtonian calculations, in none of the explored cases episodic mass transfer occurs. The neutron star is always completely disrupted after most of its mass has been transferred directly into the hole. For black hole masses between 14 and 16 \\Msun an accretion disk forms, large parts of it, however, are inside the last stable orbit and therefore falling with large radial velocities into the hole. These disks are (opposite to the neutron star merger case) thin and -apart from a spiral shock- essentially cold. For higher mass black holes ($M_{\\rm BH} \\ge 18$ \\msun) alm...

  11. VLT/ISAAC Spectra of the H-beta Region in Intermediate-Redshift Quasars II. Black Hole Mass and Eddington Ratio

    CERN Document Server

    Sulentic, J W; Stirpe, G M; Marziani, P; Dultzin-Hacyan, D; Calvani, M

    2006-01-01

    We derive black hole masses for a sample of about 300 AGNs in the redshift range 0 9.5 and suggest that extremely large M values (log M >~ 10) may not be realistic. Derived Eddington ratio values values show no evidence for a significant population of super-Eddington radiators especially after correction is made for sources with extreme orientation to our line of sight. Sources with FWHM(Hbeta broad component) <~ 4000 km/s show systematically higher Eddington ratio and lower M values than broader lined AGNs (including almost all radio-loud sources).

  12. Temperature dependence of band gap ratio and Q-factor defect mode in a semiconductor quaternary alloy hexagonal photonic-crystal hole slab

    Science.gov (United States)

    Sánchez-Cano, R.; Porras-Montenegro, N.

    2016-04-01

    We present numerical predictions for the photonic TE-like band gap ratio and the quality factors of symmetric localized defect as a function of the thickness slab and temperature by the use of plane wave expansion and the finite-difference time-domain methods. The photonic-crystal hole slab is composed of a 2D hexagonal array with identical air holes and a circular cross section, embedded in a non-dispersive III-V semiconductor quaternary alloy slab, which has a high value of dielectric function in the near-infrared region, and the symmetric defect is formed by increasing the radius of a single hole in the 2D hexagonal lattice. We show that the band gap ratio depends linearly on the temperature in the range 150-400 K. Our results show a strong temperature dependence of the quality factor Q, the maximum (Q = 7000) is reached at T = 350 hbox {K}, but if the temperature continues to increase, the efficiency drops sharply. Furthermore, we present numerical predictions for the electromagnetic field distribution at T = 350 hbox {K}.

  13. Accuracy of the Post-Newtonian Approximation for Extreme-Mass Ratio Inspirals from Black-hole Perturbation Approach

    CERN Document Server

    Sago, Norichika; Nakano, Hiroyuki

    2016-01-01

    We revisit the accuracy of the post-Newtonian (PN) approximation and its region of validity for quasi-circular orbits of a point particle in the Kerr spacetime, by using an analytically known highest post-Newtonian order gravitational energy flux and accurate numerical results in the black hole perturbation approach. It is found that regions of validity become larger for higher PN order results although there are several local maximums in regions of validity for relatively low-PN order results. This might imply that higher PN order calculations are also encouraged for comparable-mass binaries.

  14. Eddington ratios of faint AGN at intermediate redshift: Evidence for a population of half-starved black holes

    CERN Document Server

    Gavignaud, I; Bongiorno, A; Paltani, S; Zamorani, G; Møller, P; Le Brun, V; Husemann, B; Lamareille, F; Schramm, M; Le Fèvre, O; Bottini, D; Garilli, B; MacCagni, D; Scaramella, R; Scodeggio, M; Tresse, L; Vettolani, G; Zanichelli, A; Adami, C; Arnaboldi, M; Arnouts, S; Bardelli, S; Bolzonella, M; Cappi, A; Charlot, S; Ciliegi, P; Contini, T; Foucaud, S; Franzetti, P; Guzzo, L; Ilbert, O; Iovino, A; McCracken, H J; Marano, B; Marinoni, C; Mazure, A; Meneux, B; Merighi, R; Pellò, R; Pollo, A; Pozzetti, L; Radovich, M; Zucca, E; Bondi, M; Busarello, G; Cucciati, O; De la Torre, S; Gregorini, L; Mellier, Y; Merluzzi, P; Ripepi, V; Rizzo, D; Vergani, D

    2008-01-01

    We use one of the deepest spectroscopic samples of broad line active galactic nuclei (AGN) currently available, extracted from the VIMOS VLT Deep Survey (VVDS), to compute MgII and CIV virial masses estimate of 120 super-massive black holes in the redshift range 1.0holes accreting far below their Eddington limit (L_bol/L_Edd < 0.1), in marked contrast to what is generally found for AGN of higher luminosities. We speculate that these may be AGN on the decaying branch of their light-curves, well past their peak activity. This would agree with recent theoretical predictions of AGN evolution. In the electronic Appendix of this paper we publish an update of the VVDS type-1 AGN sample, including the first and most of the second epoch observations. This sample contains 298 objects of which 1...

  15. An Optically Faint Quasar Survey at z ∼ 5 in the CFHTLS Wide Field: Estimates of the Black Hole Masses and Eddington Ratios

    Science.gov (United States)

    Ikeda, H.; Nagao, T.; Matsuoka, K.; Kawakatu, N.; Kajisawa, M.; Akiyama, M.; Miyaji, T.; Morokuma, T.

    2017-09-01

    We present the result of our spectroscopic follow-up observation for faint quasar candidates at z ∼ 5 in part of the Canada–France–Hawaii Telescope Legacy Survey wide field. We select nine photometric candidates and identify three z ∼ 5 faint quasars, one z ∼ 4 faint quasar, and a late-type star. Since two faint quasar spectra show the C iv emission line without suffering from a heavy atmospheric absorption, we estimate their black hole masses ({M}{BH}) and Eddington ratios (L/{L}{Edd}). The inferred {log}{M}{BH} are 9.04 ± 0.14 and 8.53 ± 0.20, respectively. In addition, the inferred {log}(L/{L}{Edd}) are ‑1.00 ± 0.15 and ‑0.42 ± 0.22, respectively. If we adopt that L/{L}{Edd}={constant} {or}\\propto {(1+z)}2, the seed black hole masses ({M}{seed}) of our z ∼ 5 faint quasars are expected to be > {10}5 {M}ȯ in most cases. We also compare the observational results with a mass accretion model, where angular momentum is lost due to supernova explosions. Accordingly, {M}{BH} of the z ∼ 5 faint quasars in our sample can be explained even if {M}{seed} is ∼ {10}3 {M}ȯ . Since z ∼ 6 luminous qusars and our z ∼ 5 faint quasars are not on the same evolutionary track, z ∼ 6 luminous quasars and our z ∼ 5 quasars are not the same populations but different populations, due to the difference of a period of the mass supply from host galaxies. Furthermore, we confirm that one can explain {M}{BH} of z ∼ 6 luminous quasars and our z ∼ 5 faint quasars even if their seed black holes are formed at z ∼ 7.

  16. Corrosion Fatigue Crack Growth Behavior at Notched Hole in 7075 T6 Under Different Biaxial Stress Ratios

    Science.gov (United States)

    2016-08-18

    strain energy release rate I mode one (opening) K stress intensity factor (MPa*m^0.5) M molar mass R stress ratio for cyclic loading (unit less) r...Finally, 7 the third phase of the fatigue failure occurs when the resistance is exceeded, and a structure occurs, Figure 2.1 [30]. Figure 2.1...Alloy 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT UU 18. NUMBER OF PAGES 92 19a. NAME OF RESPONSIBLE PERSON Shankar

  17. Accuracy of the post-Newtonian approximation. II. Optimal asymptotic expansion of the energy flux for quasicircular, extreme mass-ratio inspirals into a Kerr black hole

    CERN Document Server

    Zhang, Zhongyang; Berti, Emanuele

    2011-01-01

    We study the effect of black hole spin on the accuracy of the post-Newtonian approximation. We focus on the gravitational energy flux for the quasicircular, equatorial, extreme mass-ratio inspiral of a compact object into a Kerr black hole of mass M and spin J. For a given dimensionless spin a=J/M^2 (in geometrical units), the energy flux depends only on the orbital velocity v or (equivalently) on the Boyer-Lindquist orbital radius r. We investigate the formal region of validity of the Taylor post-Newtonian expansion of the energy flux (which is known up to order v^8 beyond the quadrupole formula), generalizing previous work by two of us. The "error function" used to determine the region of validity of the post-Newtonian expansion can have two qualitatively different kinds of behavior, and we deal with these two cases separately. We find that, at any fixed post-Newtonian order, the edge of the region of validity (as measured by v/v_{ISCO}, where v_{ISCO} is the orbital velocity at the innermost stable circula...

  18. The Biases of Optical Line-Ratio Selection for Active Galactic Nuclei, and the Intrinsic Relationship between Black Hole Accretion and Galaxy Star Formation

    CERN Document Server

    Trump, Jonathan R; Zeimann, Gregory R; Luck, Cuyler; Bridge, Joanna S; Grier, Catherine J; Hagen, Alex; Juneau, Stephanie; Montero-Dorta, Antonio; Rosario, David J; Brandt, W Niel; Ciardullo, Robin; Schneider, Donald P

    2015-01-01

    We use 317,000 emission-line galaxies from the Sloan Digital Sky Survey to investigate line-ratio selection of active galactic nuclei (AGNs). In particular, we demonstrate that "star formation dilution" by HII regions causes a significant bias against AGN selection in low-mass, blue, star-forming, disk-dominated galaxies. This bias is responsible for the observed preference of AGNs among high-mass, green, moderately star-forming, bulge-dominated hosts. We account for the bias and simulate the intrinsic population of emission-line AGNs using a physically-motivated Eddington ratio distribution, intrinsic AGN narrow line region line ratios, a luminosity-dependent Lbol/L[OIII] bolometric correction, and the observed Mbh-sigma relation. These simulations indicate that, in massive (log(M*/Msun) > 10) galaxies, AGN accretion is correlated with specific star formation rate but is otherwise uniform with stellar mass. There is some hint of lower black hole occupation in low-mass (log(M*/Msun) < 10) hosts, although o...

  19. Characterization of Organic Thin Film Solar Cells of PCDTBT : PC71BM Prepared by Different Mixing Ratio and Effect of Hole Transport Layer

    Directory of Open Access Journals (Sweden)

    Vijay Srinivasan Murugesan

    2015-01-01

    Full Text Available The organic thin film solar cells (OTFSCs have been successfully fabricated using PCDTBT : PC71BM with different mixing ratios (1 : 1 to 1 : 8 and the influence of hole transport layer thickness (PEDOT : PSS. The active layers with different mixing ratios of PCDTBT : PC71BM have been fabricated using o-dichlorobenzene (o-DCB. The surface morphology of the active layers and PEDOT : PSS layer with different thicknesses were characterized by AFM analysis. Here, we report that the OTFSCs with high performance have been optimized with 1 : 4 ratios of PCDTBT : PC71BM. The power conversion efficiency (PCE = 5.17% of the solar cells was significantly improved by changing thickness of PEDOT : PSS layer. The thickness of the PEDOT : PSS layer was found to be of significant importance; the thickness of the PEDOT : PSS layer at 45 nm (higher spin speed 5000 rpm shows higher short circuit current density (Jsc and lower series resistance (Rs and higher PCE.

  20. Evidence for High-Frequency QPOs with a 3:2 Frequency Ratio from a 5000 Solar Mass Black Hole

    CERN Document Server

    Pasham, Dheeraj R; Zoghbi, Abderahmen; Mushotzky, Richard F; Miller, Jon; Tombesi, Francesco

    2016-01-01

    Following the discovery of 3:2 resonance quasi-periodic oscillations (QPOs) in M82X-1 (Pasham et al. 2014), we have constructed power density spectra (PDS) of all 15 (sufficiently long) {\\it XMM-Newton} observations of the ultraluminous X-ray source NGC1313X-1 ($L_{X}$ $\\approx$ 2$\\times$10$^{40}$ erg/sec). We detect a strong QPO at a frequency of 0.29$\\pm$0.01 Hz in data obtained on 2012 December 16. Subsequent searching of all the remaining observations for a 3:2/2:3 frequency pair revealed a feature at 0.46$\\pm$0.02 Hz on 2003 Dec 13 (frequency ratio of 1.59$\\pm$0.09). The global significance of the 0.29 Hz feature considering all frequencies between 0.1 and 4 Hz is $>$ 3.5 $\\sigma$. The significance of the 0.46$\\pm$0.02 Hz QPO is $>$ 3.5$\\sigma$ for a search at 2/3 and 3/2 of 0.29 Hz. We also detect lower frequency QPOs (32.9$\\pm$2.6 and 79.7$\\pm$1.2 mHz). All the QPOs are super-imposed on a continuum consisting of flat-topped, band-limited noise, breaking into a power-law at a frequency of 16$\\pm$3 mHz a...

  1. An Automated High Aspect Ratio Mesher for Computational Fluid Dynamics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The work will focus on the 3D implementation of the Phase 1 CHARM mesher, with solution-adaptive iteration for CFD and non-CFD applications. The proposed 3D method...

  2. The flow over a 'high' aspect ratio gothic wing at supersonic speeds

    Science.gov (United States)

    Narayan, K. Y.

    1975-01-01

    Results are presented of an experimental investigation on a nonconical wing which supports an attached shock wave over a region of the leading edge near the vertex and a detached shock elsewhere. The shock detachment point is determined from planform schlieren photographs of the flow field and discrepancies are shown to exist between this and the one calculated by applying the oblique shock equations normal to the leading edge. On a physical basis, it is argued that the shock detachment has to obey the two-dimensional law normal to the leading edges. From this, and from other measurements on conical wings, it is thought that the planform schlieren technique may not be particularly satisfactory for detecting shock detachment. Surface pressure distributions are presented and are explained in terms of the flow over related delta wings which are identified as a vertex delta wing and a local delta wing.

  3. Visualization of cavitating and flashing flows within a high aspect ratio injector

    Science.gov (United States)

    Thompson, Andrew S.

    Thermal management issues necessitate the use of fuel as a heat sink for gas turbine and liquid rocket engines. There are certain benefits to using heated fuels, namely, increased sensible enthalpy, increased combustion efficiency, a decrease in certain emissions, and enhanced vaporization characteristics. However, the thermal and pressure enviornment inside an injector can result in the fuel flashing to vapor. Depending on the injector design, this can have deleterious effects on engine performance. As interest in heated fuels inreases, it is important to understand what occurs in the flow path of an injector under flashing conditions. At the High Pressure Laboratory at Purdue University's Maurice J. Zucrow Laboritories, a test rig was designed and built to give visual access into the flow path of a 2-D slot injector. The rig is capable of pressurizing and heating a liquid to superheated conditions and utilizes a pneumatically actuated piston to pusth the liquid through the slot injector. Methanol was chosen as a surrogate fuel to allow for high levels of superheat at relatively low temperatures. Testing was completed with acrylic and quartz injectors of varying L/DH. Flashing conditions inside the injector flow path were induced via a combination of heating and back pressure adjustments. Volume flow rate, pressure measurements, and temperature measurements were made which allowed the discharge characteristics, the level of superheat, and other parameters to be calculated and compared. To give a basis for comparison the flashing results are compared to the flow through the injector under cavitating conditions. Cavitation and flashing appear to be related phenomena and this relationship is shown. Bubble formation under cavitating or flashing conditions is observed to attenuate the injector's discharge characteristics. High speed videos of the flow field were also collected. Several flow regimes and flow structures, unique to these regimes, were observed. A frequency analysis was also performed on the video files. Bubble formation in the flow field dominates the frequency spectrum, which is confined below 1 kHz. The test campaign was successful. The result is a possible way to predict an injector's performance under flashing conditions without running heated fuel through the injector. These results may be applicable to real world injector design and testing.

  4. High-aspect-ratio silicon-cell metallization technical status report. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1982-01-01

    Two features of the silicon concentrator solar cell are addressed which affect output at high concentration levels. The first is the development of narrow but high electroplated grid lines with improved conductivity. The object is a reduction in cell series resistance without increase in shadowing. This goal is accomplished by electroplating through a thick photo resist mask to produce lines .7 mil wide by .7 mil high. Advance pulse plating techniques are combined with pure silver plating baths to produce a deposit conductivity equal to the bulk silver conductivity (a 1.5 to 2 X improvement over conventional silver plating). The second feature is a double diffused selectively textured front surface. This development employs a deep diffusion in the silicon under the grid lines. Only the non grid line open area is selectively texture etched removing the deep junction. This open textured area is then given a second shallow diffusion for optimum cell efficiency. This selective procedure maintains the original highly polished wafer surface under the grid lines so that high resolution narrow grid lines are possible. The double diffusion protects the junction from metal diffusion while enabling the optimum shallow junction in the illuminated regions. Combining these two features has produced a large area concentrator cells (8 cm/sup 2/) with peak efficiency above 16% and exhibiting a broad peak efficiency extending from 50 to 175 suns above 15%.

  5. Light extinction and scattering from individual and arrayed high-aspect-ratio trenches in metal

    DEFF Research Database (Denmark)

    Roberts, Alexander; Søndergaard, Thomas; Chirumamilla, Manohar

    2016-01-01

    for a two-dimensional scatterer. We construct a simple resonator model which predicts the wavelength-dependent extinction, scattering, and absorption cross section of the trench and compare the model findings with full numerical simulations. Both extinction and scattering cross sections are mainly...... determined by the wavelength and can reach highly supergeometric values. At wavelengths where the metal exhibits near perfect electrical conductor behavior, such trenches lend themselves to be used as self-normalizing scatterers, as their scattering cross section is independent of their geometry and depend...... and two-photon luminescence that the resonant behavior of the vertical trenches is preserved....

  6. Nucleation of melting and solidification in confined high aspect ratio thin films

    Science.gov (United States)

    Mastandrea, J. P.; Ager, J. W.; Chrzan, D. C.

    2017-09-01

    Classical nucleation theory is used to consider the solidification of a melt confined between two planar surfaces. The critical nucleus shapes and the associated nucleation energy barriers are computed as a function of the thickness of the film and the film's relevant bulk and interface energies. The analysis is then repeated for the melting transition, and expressions for the depression and elevation of the melting temperature, relative to the thermodynamic bulk melting temperature of the film material, are found. A nucleus morphology diagram is constructed. This diagram presents the lowest energy morphology of the nuclei, as well as melting points, as a function of the system parameters. Using the nucleus morphology diagram, experimental and system parameters that allow for the desired nucleation behavior can be identified. Furthermore, the nucleus morphology diagram illustrates a region of parameter space where the film is predicted to solidify above its thermodynamic bulk melting temperature, a behavior termed presolidification. The theory is used to predict the temperature at which the nucleation of the solid phase and liquid phase is expected for Ge between two glass substrates. Furthermore, a possible route for controlling the orientation of the film is identified. By controlling the growth temperature, certain orientations may not be able to nucleate, thereby reducing the possible number of orientations within a film.

  7. Lecithin blended polyamide-6 high aspect ratio nanofiber scaffolds via electrospinning for human osteoblast cell culture

    Energy Technology Data Exchange (ETDEWEB)

    Nirmala, R. [Bio-nano System Engineering, College of Engineering, Chonbuk National University, Jeonju, 561 756 (Korea, Republic of); Park, Hye-Min [Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); Navamathavan, R. [School of Advanced Materials Engineering, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); Kang, Hyung-Sub [Department of Pharmacology and Toxicology, College of Veterinary Medicine, Chonbuk National University, Jeonju 561 756 (Korea, Republic of); El-Newehy, Mohamed H. [Petrochemical Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Kim, Hak Yong, E-mail: khy@jbnu.ac.kr [Petrochemical Research Chair, Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Center for Healthcare Technology and Development, Chonbuk National University, Jeonju, 561 756 (Korea, Republic of)

    2011-03-12

    In this study, we focused on the preparation and characterization of lecithin blended polyamide-6 nanofibers via an electrospinning process for human osteoblastic (HOB) cell culture applications. The morphological, structural characterizations and thermal properties of polyamide-6/lecithin nanofibers were determined by using scanning electron microscopy (SEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetry (TGA). SEM images revealed that the nanofibers were well-oriented with good incorporation of lecithin. FT-IR results indicated the presence of amino groups of lecithin in the blended nanofibers. TGA analysis revealed that the onset degradation temperature decreased with increasing lecithin content in the blended nanofibers. The morphological features of cells attached on polyamide-6/lecithin nanofibers were confirmed by SEM. The adhesion, viability and proliferation properties of osteoblast cells on the polyamide-6/lecithin blended nanofibers were analyzed by in vitro cell compatibility test. This study demonstrated the non-cytotoxic behavior of electrospun polyamide-6/lecithin nanofibers for the osteoblast cell culture.

  8. High aspect-ratio MEMS devices for the next generation of THz/MHz passive components

    NARCIS (Netherlands)

    Fiorentino, G.

    2015-01-01

    The realization of efficient passive devices directly on chip represents one of the most intriguing challenges in IC fabrication processes. The performance of such devices are intrinsically determined by physical parameters that cannot be easily scaled, making the on-chip integration of such compone

  9. Ordered and Ultra-High Aspect Ratio Nanocapillary Arrays as a Model System

    Science.gov (United States)

    2015-10-13

    nanocapillaries can be used to synthesize molecularly confined or form quantum confined nanostructures. We have shown these effects benefit to improve...10 3 10-2 10 1 100 101 102 103 104 Page 5 Copyright © 2015 Mainstream Engineering Corporation Thermodynamic • Joule Heating • Uneven...Complex thermal/electrochemical dependence  Rate-inhibiting concentration gradient established  Small environmental gradients effect long-term

  10. Low-energy electron transmission through high aspect ratio Al O nanocapillaries

    DEFF Research Database (Denmark)

    Milosavljević, A.R.; Jureta, J.; Víkor, G.;

    2009-01-01

    Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined with resp......Electron transmission through insulating AlO nanocapillaries of different diameters (40 and 270 nm) and 15 μm length has been investigated for low-energy electrons (2-120 V). The total intensity of transmitted current weakly depends on the incident electron energy and tilt angle defined...

  11. Injection molding micro patterns with high aspect ratio using a polymeric flexible stamper

    Directory of Open Access Journals (Sweden)

    2011-11-01

    Full Text Available Poor filling occurs during the injection molding process of micro- or nano- scale patterns mainly because the hot polymer melt rapidly cools and its skin quickly solidifies upon contact with the mold surface. In this study, it is proposed to use Polyethylene terephthalate (PET film coated with patterned polyurethane acrylate (PUA as an effective thermal barrier. It can significantly hinder heat transfer into the mold during the molding process and thus may keep the melt viscosity low for longer duration. As a result, the replication would be improved not only during the filling phase but also during the packing phase. In order to verify the validity of the use of polymeric stamper, the melt-film interface temperature was evaluated by numerical simulation. Experimental results indicated that patterns possessing widths within the range of one to tens of micrometers and a height of approximately 10 µm were successfully filled and demolded.

  12. Deep proton writing of high aspect ratio SU-8 micro-pillars on glass

    Science.gov (United States)

    Ebraert, Evert; Rwamucyo, Ben; Thienpont, Hugo; Van Erps, Jürgen

    2016-12-01

    Deep proton writing (DPW) is a fabrication technology developed for the rapid prototyping of polymer micro-structures. We use SU-8, a negative resist, spincoated in a layer up to 720 μm-thick in a single step on borosilicate glass, for irradiation with a collimated 12 MeV energy proton beam. Micro-pillars with a slightly conical profile are irradiated in the SU-8 layer. We determine the optimal proton fluence to be 1.02 × 104 μm-2, with which we are able to repeatably achieve micro-pillars with a top-diameter of 138 ± 1 μm and a bottom-diameter of 151 ± 3 μm. The smallest fabricated pillars have a top-diameter of 57 ± 5 μm. We achieved a root-mean-square sidewall surface roughness between 19 nm and 35 nm for the fabricated micro-pillars, measured over an area of 5 × 63.7 μm. We briefly discuss initial testing of two potential applications of the fabricated micro-pillars. Using ∼100 μm-diameter pillars as waveguides for gigascale integration optical interconnect applications, has shown a 4.7 dB improvement in optical multimode fiber-to-fiber coupling as compared to the case where an air-gap is present between the fibers at the telecom wavelength of 1550 nm. The ∼140 μm-diameter pillars were used for mold fabrication with silicone casting. The resulting mold can be used for hydrogel casting, to obtain hydrogel replicas mimicking human tissue for in vitro bio-chemical applications.

  13. An atmospheric-pressure, high-aspect-ratio, cold micro-plasma.

    Science.gov (United States)

    Lu, X; Wu, S; Gou, J; Pan, Y

    2014-01-01

    An atmospheric pressure nonequilibrium Ar micro-plasma generated inside a micro-tube with plasma radius of 3 μm and length of 2.7 cm is reported. The electron density of the plasma plume estimated from the broadening of the Ar emission line reaches as high as 3 × 10(16) cm(-3). The electron temperature obtained from CR model is 1.5 ev while the gas temperature of the plasma estimated from the N2 rotational spectrum is close to room temperature. The sheath thickness of the plasma could be close to the radius of the plasma. The ignition voltages of the plasma increase one order when the radius of the dielectric tube is decreased from 1 mm to 3 μm.

  14. High Aspect Ratio Microstructures in Flexible Printed Circuit Boards : Process and Applications

    OpenAIRE

    Yousef, Hanna

    2008-01-01

    Flexible printed circuit boards (flex PCBs) are used in a wide range of electronic devices today due to their light weight, bendability, extensive wiring possibilities, and low-cost manufacturing techniques. The general trend in the flex PCB industry is further miniaturization alongside increasing functionality per device and reduced costs. To meet these demands, a new generation of low cost manufacturing technologies is being developed to enable structures with smaller lateral dimensions and...

  15. High-Aspect-Ratio CMOS add-on modules for RF passive components

    NARCIS (Netherlands)

    Sagkol, H.

    2011-01-01

    Commercial wireless communication technologies stemmed mostly from the research done through and after the Second World War as outlined in Chapter 1. Earlier systems were intended for military applications, hence had very high performance and were very expensive and bulky. Later, with the dawn of co

  16. Deep proton writing of high aspect ratio SU-8 micro-pillars on glass

    Energy Technology Data Exchange (ETDEWEB)

    Ebraert, Evert, E-mail: eebraert@b-phot.org; Rwamucyo, Ben; Thienpont, Hugo; Van Erps, Jürgen

    2016-12-15

    Deep proton writing (DPW) is a fabrication technology developed for the rapid prototyping of polymer micro-structures. We use SU-8, a negative resist, spincoated in a layer up to 720 μm-thick in a single step on borosilicate glass, for irradiation with a collimated 12 MeV energy proton beam. Micro-pillars with a slightly conical profile are irradiated in the SU-8 layer. We determine the optimal proton fluence to be 1.02 × 10{sup 4} μm{sup −2}, with which we are able to repeatably achieve micro-pillars with a top-diameter of 138 ± 1 μm and a bottom-diameter of 151 ± 3 μm. The smallest fabricated pillars have a top-diameter of 57 ± 5 μm. We achieved a root-mean-square sidewall surface roughness between 19 nm and 35 nm for the fabricated micro-pillars, measured over an area of 5 × 63.7 μm. We briefly discuss initial testing of two potential applications of the fabricated micro-pillars. Using ∼100 μm-diameter pillars as waveguides for gigascale integration optical interconnect applications, has shown a 4.7 dB improvement in optical multimode fiber-to-fiber coupling as compared to the case where an air–gap is present between the fibers at the telecom wavelength of 1550 nm. The ∼140 μm-diameter pillars were used for mold fabrication with silicone casting. The resulting mold can be used for hydrogel casting, to obtain hydrogel replicas mimicking human tissue for in vitro bio-chemical applications.

  17. Magnetic field alignment of randomly oriented, high aspect ratio silicon microwires into vertically oriented arrays.

    Science.gov (United States)

    Beardslee, Joseph A; Sadtler, Bryce; Lewis, Nathan S

    2012-11-27

    External magnetic fields have been used to vertically align ensembles of silicon microwires coated with ferromagnetic nickel films. X-ray diffraction and image analysis techniques were used to quantify the degree of vertical orientation of the microwires. The degree of vertical alignment and the minimum field strength required for alignment were evaluated as a function of the wire length, coating thickness, magnetic history, and substrate surface properties. Nearly 100% of 100 μm long, 2 μm diameter, Si microwires that had been coated with 300 nm of Ni could be vertically aligned by a 300 G magnetic field. For wires ranging from 40 to 60 μm in length, as the length of the wire increased, a higher degree of alignment was observed at lower field strengths, consistent with an increase in the available magnetic torque. Microwires that had been exposed to a magnetic sweep up to 300 G remained magnetized and, therefore, aligned more readily during subsequent magnetic field alignment sweeps. Alignment of the Ni-coated Si microwires occurred at lower field strengths on hydrophilic Si substrates than on hydrophobic Si substrates. The magnetic field alignment approach provides a pathway for the directed assembly of solution-grown semiconductor wires into vertical arrays, with potential applications in solar cells as well as in other electronic devices that utilize nano- and microscale components as active elements.

  18. Ablative implosion of high-aspect-ratio gas-filled targets

    Energy Technology Data Exchange (ETDEWEB)

    Tomasel, F.G.; Cortazar, O.D. (Universidad Nacional de Mar del Plata (Argentina). Dept. de Fisica); Piriz, A.R. (Buenos Aires Univ. (Argentina). Dept. de Fisica)

    1991-11-01

    A simple analytical mode for the implosion of very thin spherical shell targets filled with fuel gas is developed. The shock trajectory in the fuel is described consistently with the shell acceleration, and two dimensionless parameters which govern the complete dynamics are found. The model applies to recent experiments focused on high neutron yield and provides a simple description of the main physical phenomena, which is in agreement with simulation and experiments. (author).

  19. Mechanical Design of High Lift Systems for High Aspect Ratio Swept Wings

    Science.gov (United States)

    Rudolph, Peter K. C.

    1998-01-01

    The NASA Ames Research Center is working to develop a methodology for the optimization and design of the high lift system for future subsonic airliners with the involvement of two partners. Aerodynamic analysis methods for two dimensional and three dimensional wing performance with flaps and slats deployed are being developed through a grant with the aeronautical department of the University of California Davis, and a flap and slat mechanism design procedure is being developed through a contract with PKCR, Inc., of Seattle, WA. This report documents the work that has been completed in the contract with PKCR on mechanism design. Flap mechanism designs have been completed for seven (7) different mechanisms with a total of twelve (12) different layouts all for a common single slotted flap configuration. The seven mechanisms are as follows: Simple Hinge, Upside Down/Upright Four Bar Linkage (two layouts), Upside Down Four Bar Linkages (three versions), Airbus A330/340 Link/Track Mechanism, Airbus A320 Link/Track Mechanism (two layouts), Boeing Link/Track Mechanism (two layouts), and Boeing 767 Hinged Beam Four Bar Linkage. In addition, a single layout has been made to investigate the growth potential from a single slotted flap to a vane/main double slotted flap using the Boeing Link/Track Mechanism. All layouts show Fowler motion and gap progression of the flap from stowed to a fully deployed position, and evaluations based on spanwise continuity, fairing size and number, complexity, reliability and maintainability and weight as well as Fowler motion and gap progression are presented. For slat design, the options have been limited to mechanisms for a shallow leading edge slat. Three (3) different layouts are presented for maximum slat angles of 20 deg, 15 deg and 1O deg all mechanized with a rack and pinion drive similar to that on the Boeing 757 airplane. Based on the work of Ljungstroem in Sweden, this type of slat design appears to shift the lift curve so that higher lift is achieved with the deployed slat with no increase in angle of attack. The layouts demonstrate that these slat systems can be designed with no need for slave links, and an experimental test program is outlined to experimentally validate the lift characteristics of the shallow slat.

  20. Finite element analysis of surface acoustic waves in high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2008-01-01

    down the SAWvelocity because of mechanical energy storage. A finite model is furthermore employed to study the acousto-optical interaction and shows that it is possible to get a bigger change in effective refractive index with these surface acoustic waves compared to using conventional interdigital...

  1. High aspect-ratio MEMS devices for the next generation of THz/MHz passive components

    NARCIS (Netherlands)

    Fiorentino, G.

    2015-01-01

    The realization of efficient passive devices directly on chip represents one of the most intriguing challenges in IC fabrication processes. The performance of such devices are intrinsically determined by physical parameters that cannot be easily scaled, making the on-chip integration of such

  2. An Automated High Aspect Ratio Mesher for Computational Fluid Dynamics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Computational fluid dynamics (CFD) simulations are routinely used while designing, analyzing, and optimizing air- and spacecraft. An important component of CFD...

  3. The AKARI 2.5-5.0 Micron Spectral Atlas of Type-1 Active Galactic Nuclei: Black Hole Mass Estimator, Line Ratio, and Hot Dust Temperature

    CERN Document Server

    Kim, Dohyeong; Kim, Ji Hoon; Jun, Hyunsung David; Woo, Jong-Hak; Lee, Hyung Mok; Lee, Myung Gyoon; Nakagawa, Takao; Matsuhara, Hideo; Wada, Takehiko; Oyabu, Shinki; Takagi, Toshinobu; Ohyama, Youichi; Lee, Seong-Kook

    2015-01-01

    We present 2.5-5.0 $\\mu$m spectra of 83 nearby ($0.002\\,<\\,z\\,<\\,0.48$) and bright ($K<14$mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera (IRC) on board $\\it{AKARI}$. The 2.5-5.0 $\\mu$m spectral region contains emission lines such as Br$\\beta$ (2.63 $\\mu$m), Br$\\alpha$ (4.05 $\\mu$m), and polycyclic aromatic hydrocarbons (PAH; 3.3 $\\mu$m), which can be used for studying the black hole (BH) masses and star formation activities in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green (PG) and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. (2004). Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physica...

  4. The charged black-hole bomb: A lower bound on the charge-to-mass ratio of the explosive scalar field

    Directory of Open Access Journals (Sweden)

    Shahar Hod

    2016-04-01

    Full Text Available The well-known superradiant amplification mechanism allows a charged scalar field of proper mass μ and electric charge q to extract the Coulomb energy of a charged Reissner–Nordström black hole. The rate of energy extraction can grow exponentially in time if the system is placed inside a reflecting cavity which prevents the charged scalar field from escaping to infinity. This composed black-hole-charged-scalar-field-mirror system is known as the charged black-hole bomb. Previous numerical studies of this composed physical system have shown that, in the linearized regime, the inequality q/μ>1 provides a necessary condition for the development of the superradiant instability. In the present paper we use analytical techniques to study the instability properties of the charged black-hole bomb in the regime of linearized scalar fields. In particular, we prove that the lower bound qμ>rm/r−−1rm/r+−1 provides a necessary condition for the development of the superradiant instability in this composed physical system (here r± are the horizon radii of the charged Reissner–Nordström black hole and rm is the radius of the confining mirror. This analytically derived lower bound on the superradiant instability regime of the composed black-hole-charged-scalar-field-mirror system is shown to agree with direct numerical computations of the instability spectrum.

  5. Efficient Si photovoltaic devices with integrated micro/nano holes

    Science.gov (United States)

    Cansizoglu, Hilal; Gao, Yang; Kaya, Ahmet; Ghandiparsi, Soroush; Polat, Kazim G.; Wang, Yichuan; Zhang, Runzhou; Reggad, Hind; Mayet, Ahmed; Ponizovskaya Devine, Ekaterina; Islam, M. Saif

    2016-09-01

    Efficient light harvesting in a thin layer of crystalline Si can be realized by implementing nanoscale pillars and holes to the device structure. The major drawback of the pillars and holes based photovoltaic devices is high surface to volume ratio, contributing to an increase in surface recombination rate of the photo-generated carriers. The common techniques used in pillars/holes fabrication such as dry etching make the surface even worse by bombarding it with high energy ions. Therefore, such damaged surfaces of high aspect ratio structures need to be effectively passivated. In this study, we demonstrate a hole based thin crystalline Si photovoltaic device with enhanced open circuit voltage and short circuit current after a successful surface passivation process through a wet oxidation. In addition, the effect of passivation layer fabricated by rapid thermal oxide growth on photo response is investigated. A successful fabrication of thin crystalline Si solar cells can lead to the applications of ultra-thin, highly efficient, flexible and wearable energy sources.

  6. Microfabrication of through holes in polydimethylsiloxane (PDMS) sheets using a laser plasma EUV source (Conference Presentation)

    Science.gov (United States)

    Makimura, Tetsuya; Urai, Hikari; Niino, Hiroyuki

    2017-03-01

    Polydimethylsiloxane (PDMS) is a material used for cell culture substrates / bio-chips and micro total analysis systems / lab-on-chips due to its flexibility, chemical / thermo-dynamic stability, bio-compatibility, transparency and moldability. For further development, it is inevitable to develop a technique to fabricate precise three dimensional structures on micrometer-scale at high aspect ratio. In the previous works, we reported a technique for high-quality micromachining of PDMS without chemical modification, by means of photo direct machining using laser plasma EUV sources. In the present work, we have investigated fabrication of through holes. The EUV radiations around 10 nm were generated by irradiation of Ta targets with Nd:YAG laser light (10 ns, 500 mJ/pulse). The generated EUV radiations were focused using an ellipsoidal mirror. It has a narrower incident angle than those in the previous works in order to form a EUV beam with higher directivity, so that higher aspect structures can be fabricated. The focused EUV beam was incident on PDMS sheets with a thickness of 15 micrometers, through holes in a contact mask placed on top of them. Using a contact mask with holes with a diameter of three micrometers, complete through holes with a diameter of two micrometers are fabricated in the PDMS sheet. Using a contact mask with two micrometer holes, however, ablation holes almost reaches to the back side of the PDMS sheet. The fabricated structures can be explained in terms of geometrical optics. Thus, we have developed a technique for micromachining of PDMS sheets at high aspect ratios.

  7. The charged black-hole bomb: A lower bound on the charge-to-mass ratio of the explosive scalar field

    CERN Document Server

    Hod, Shahar

    2016-01-01

    The well-known superradiant amplification mechanism allows a charged scalar field of proper mass $\\mu$ and electric charge $q$ to extract the Coulomb energy of a charged Reissner-Nordstr\\"om black hole. The rate of energy extraction can grow exponentially in time if the system is placed inside a reflecting cavity which prevents the charged scalar field from escaping to infinity. This composed black-hole-charged-scalar-field-mirror system is known as the {\\it charged black-hole bomb}. Previous numerical studies of this composed physical system have shown that, in the linearized regime, the inequality $q/\\mu>1$ provides a necessary condition for the development of the superradiant instability. In the present paper we use analytical techniques to study the instability properties of the charged black-hole bomb in the regime of linearized scalar fields. In particular, we prove that the lower bound ${{q}\\over{\\mu}}>\\sqrt{{{r_{\\text{m}}/r_--1}\\over{r_{\\text{m}}/r_+-1}}}$ provides a necessary condition for the develo...

  8. Ion microprobe analyses of oxygen three-isotope ratios of chondrules from the Sayh al Uhaymir 290 CH chondrite using a multiple-hole disk

    Digital Repository Service at National Institute of Oceanography (India)

    Nakashima, D.; Ushikubo, T.; Gowda, R.N.; Kita, N.T.; Valley, J.W.; Naga, K.

    (i.e., small dimples vs. small bumps). The deformation of the electrostatic field above the sample surface in the multiple-hole disks would thus be in the opposite direction compared to that of zircon grains with polishing relief. Thus, the X...

  9. Laser hole drilling in thick polypropylene sheets for alignment sensors

    Science.gov (United States)

    Bergen, D. E.; Chapman, Glenn H.; Samra, Taranjit S.; Weeks, T. S.

    1996-04-01

    Laser micromachining of polypropylene for transducer applications has the advantage of creating small ( 400 micron). Normally translucent polypropylene formed using carbon as a dye is an excellent laser machining material having a high optical absorption, and a low thermal conductivity. For an optical alignment system a matrix of high aspect ratio holes of 400 micron) sheets. This alignment sensor is to be used on the end of a robot arm and will aid in the manipulation of the arm. Using an argon ion laser focused through a 50 mm lens (5.2 micron R1/e2 spot, 55.2 micron focal depth), holes as small as 30 microns on 150 micron spacing were achieved in 400 - 500 micron thick black polypropylene sheets with consistent results. Best results currently are achieved with a laser power of only 0.3 W, using 10 - 100 pulse stream of 10 - 100 microsec pulses, and duty cycles of polypropylene required 17 times the power, and achieved holes of only 127 microns, with 500 microns spacing in 500 micron thick material. Thicker (1 mm) black polypropylene produces 144 micron holes on 500 micron spacings due to the lip material, and required a 100 mm lens.

  10. Two-dimensional photonic crystals based on anodic porous TiO2 with ideally ordered hole arrangement

    Science.gov (United States)

    Kondo, Toshiaki; Hirano, Shota; Yanagishita, Takashi; Truong Nguyen, Nhat; Schmuki, Patrick; Masuda, Hideki

    2016-10-01

    Ideally ordered TiO2 hole arrays with high aspect ratios were prepared by the anodization of pretextured Ti. The obtained TiO2 acted as two-dimensional photonic crystals in which a photonic band gap is formed in all directions of light propagation in the lattice. The process allows the easy and low-cost fabrication of TiO2 photonic crystals and can be used for the preparation of functional optical devices, which require the precise control of light propagation.

  11. δ13C and δ18O isotopic composition of CaCO3 measured by continuous flow isotope ratio mass spectrometry: statistical evaluation and verification by application to Devils Hole core DH-11 calcite

    Science.gov (United States)

    Revesz, Kinga M.; Landwehr, Jurate M.

    2002-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400 ± 20 µg) of calcium carbonate. This new method streamlines the classical phosphoric acid/calcium carbonate (H3PO4/CaCO3) reaction method by making use of a recently available Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. Conditions for which the H3PO4/CaCO3 reaction produced reproducible and accurate results with minimal error had to be determined. When the acid/carbonate reaction temperature was kept at 26 °C and the reaction time was between 24 and 54 h, the precision of the carbon and oxygen isotope ratios for pooled samples from three reference standard materials was ≤0.1 and ≤0.2 per mill or ‰, respectively, although later analysis showed that materials from one specific standard required reaction time between 34 and 54 h for δ18O to achieve this level of precision. Aliquot screening methods were shown to further minimize the total error. The accuracy and precision of the new method were analyzed and confirmed by statistical analysis. The utility of the method was verified by analyzing calcite from Devils Hole, Nevada, for which isotope-ratio values had previously been obtained by the classical method. Devils Hole core DH-11 recently had been re-cut and re-sampled, and isotope-ratio values were obtained using the new method. The results were comparable with those obtained by the classical method with correlation = +0.96 for both isotope ratios. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, and two cutting errors that occurred during re-sampling then were confirmed independently. This result indicates that the new method is a viable alternative to the classical reaction method. In particular, the new method requires less sample material permitting finer resolution and allows

  12. Black Holes

    Science.gov (United States)

    Luminet, Jean-Pierre

    1992-09-01

    Foreword to the French edition; Foreword to the English edition; Acknowledgements; Part I. Gravitation and Light: 1. First fruits; 2. Relativity; 3. Curved space-time; Part II. Exquisite Corpses: 4. Chronicle of the twilight years; 5. Ashes and diamonds; 6. Supernovae; 7. Pulsars; 8. Gravitation triumphant; Part III. Light Assassinated: 9. The far horizon; 10. Illuminations; 11. A descent into the maelstrom; 12. Map games; 13. The black hole machine; 14. The quantum black hole; Part IV. Light Regained: 15. Primordial black holes; 16. The zoo of X-ray stars; 17. Giant black holes; 18. Gravitational light; 19. The black hole Universe; Appendices; Bibliography; Name index; Subject index.

  13. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  14. Spinning a charged dilaton black hole

    CERN Document Server

    Shiraishi, Kiyoshi

    2015-01-01

    A charged dilaton black hole which possesses infinitesimal angular momentum is studied. We find that the gyromagnetic ratio of the dilaton black hole depends not only on the parameter which appears in the interaction between the dilaton and the electric field but also nonlinearly on the ratio of the charge to the mass of the black hole. The moment of inertia for the charged dilaton hole in the limit of infinitesimal angular momentum is also calculated.

  15. Tailoring the Mechanical Properties of High-Aspect-Ratio Carbon Nanotube Arrays using Amorphous Silicon Carbide Coatings

    NARCIS (Netherlands)

    Poelma, R.H.; Morana, B.; Vollebregt, S.; Schlangen, H.E.J.G.; Van Zeijl, H.W.; Fan, X.; Zhang, G.Q.

    2014-01-01

    The porous nature of carbon nanotube (CNT) arrays allows for the unique opportunity to tailor their mechanical response by the infiltration and deposition of nanoscale conformal coatings. Here, we fabricate novel photo-lithographically defined CNT pillars that are conformally coated with amorphous s

  16. Multi-Objective Flight Control for Drag Minimization and Load Alleviation of High-Aspect Ratio Flexible Wing Aircraft

    Science.gov (United States)

    Nguyen, Nhan; Ting, Eric; Chaparro, Daniel; Drew, Michael; Swei, Sean

    2017-01-01

    As aircraft wings become much more flexible due to the use of light-weight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence increased fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of light-weight material could be offset by less optimal aerodynamic performance at off-design flight conditions. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multi-disciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the optimal aerodynamic performance from being realized. These operational constraints include reduced flutter margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the optimal aerodynamic performance present themselves as a multi-objective flight control problem. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control has already been developed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag minimization demonstrates the effectiveness of the proposed solution. In-flight structural loads are also an important consideration. As wing flexibility increases, maneuver load and gust load responses can be significant and therefore can pose safety and flight control concerns. In this paper, we will extend the multi-objective flight control framework to include load alleviation control. The study will focus initially on maneuver load minimization control, and then subsequently will address gust load alleviation control in future work.

  17. Oxidative Unzipping and Transformation of High Aspect Ratio Boron Nitride Nanotubes into “White Graphene Oxide” Platelets

    Science.gov (United States)

    Nautiyal, Pranjal; Loganathan, Archana; Agrawal, Richa; Boesl, Benjamin; Wang, Chunlei; Agarwal, Arvind

    2016-07-01

    Morphological and chemical transformations in boron nitride nanotubes under high temperature atmospheric conditions is probed in this study. We report atmospheric oxygen induced cleavage of boron nitride nanotubes at temperatures exceeding 750 °C for the first time. Unzipping is then followed by coalescence of these densely clustered multiple uncurled ribbons to form stacks of 2D sheets. FTIR and EDS analysis suggest these 2D platelets to be Boron Nitride Oxide platelets, with analogous structure to Graphene Oxide, and therefore we term them as “White Graphene Oxide” (WGO). However, not all BNNTs deteriorate even at temperatures as high as 1000 °C. This leads to the formation of a hybrid nanomaterial system comprising of 1D BN nanotubes and 2D BN oxide platelets, potentially having advanced high temperature sensing, radiation shielding, mechanical strengthening, electron emission and thermal management applications due to synergistic improvement of multi-plane transport and mechanical properties. This is the first report on transformation of BNNT bundles to a continuous array of White Graphene Oxide nanoplatelet stacks.

  18. Direct Observation of Two Phase Flow Generated by an Alumina Seeded Grain in High Aspect Ratio Channels

    Science.gov (United States)

    2010-06-01

    and the characteristic length is 44.45 mm. Finally, the convection coefficient is calculated to be 298 W/m2*K. Incropera and Dewitt note that...Advanced Strength and Applied Elasticity (4th ed.). Upper Saddle, NJ: Prentice Hall PTR, 2003. [11] F. P. Incropera and D. P. DeWitt

  19. Fabricating and Tailoring Polyaniline (PANI) Nanofibers with High Aspect Ratio in a Low-Acid Environment in a Magnetic Field.

    Science.gov (United States)

    Ma, Yong; Chen, Yanhui; Mei, Ang; Qiao, Mingtao; Hou, Chunping; Zhang, Hepeng; Zhang, Qiuyu

    2016-01-01

    In a 0.010 m HCl solution, we successfully transformed irregular polyaniline (PANI) agglomerates into uniform PANI nanofibers with a diameter of 46-145 nm and a characteristic length on the order of several microns by the addition of superparamagnetic Fe3 O4 microspheres in a magnetic field. The PANI morphological evolution showed that the PANI nanofibers stemmed from the PANI coating shell synthesized on the surface of the Fe3 O4 microsphere chains. It was found that the magnetic field could optimize the PANI nanofibers with a narrow diameter size distribution, and effectively suppressed secondary growth. When compared with other microspheres (like silica and polystyrene), only the use of superparamagnetic Fe3 O4 microspheres resulted in the appearance of PANI nanofibers. Attempts to form these high-quality PANI nanofibers in other concentrations of HCl solution were unsuccessful. This deficiency was largely attributed to the inappropriate quantity of aniline cations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. BisGMA/TEGDMA dental nanocomposites containing glyoxylic acid modified high-aspect ratio hydroxyapatite nanofibers with enhanced dispersion

    Science.gov (United States)

    Chen, Liang; Xu, Changqi; Wang, Yong; Shi, Jian; Yu, Qingsong

    2012-01-01

    The purpose of this research was to investigate the influence of the glyoxylic acid (GA) modification of hydroxyapatite (HAP) nanofibers on their dispersion in bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental composites and also investigate the mechanical properties, water absorption, and water solubility of the resulting dental resins and composites. Scanning/Transmission electron microscopy (STEM) images showed that microsized HAP nanofiber bundles could be effectively broken down to individual HAP nanofibers with an average length of ~15 μm after the surface modification process. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA) characterization confirmed glyoxylic acid was chemically grafted on the HAP nanofiber surface, hypothetically by reacting with the amine group on HAP nanofiber surface. The enhanced dispersion of HAP nanofibers in dental matrix led to increased biaxial flexural strength (BFS) compared with the corresponding dental resins and composites filled with untreated HAP nanofibers. In addition, impregnation of small mass fractions of the glyoxylic acid modified HAP nanofibers into the BisGMA/TEGDMA dental resins (5wt%, 10wt%) or composites (2wt%, 3wt%) could also substantially improve the BFS in comparison with the controls(pure resins or dental composites filled with silica particles alone). Larger mass fractions could not further increase the mechanical property or even degrade the BFS values. Water behavior testing results indicated that the addition of glyoxylic acid modified HAP nanofibers resulted in higher water absorption and water solubility values which is not preferred for clinical application. In summary, well dispersed HAP nanofibers and their dental composites with enhanced mechanical property have been successfully fabricated but the water absorption and water solubility of such dental composites need to be further improved. PMID:22689264

  1. BisGMA/TEGDMA dental nanocomposites containing glyoxylic acid modified high-aspect ratio hydroxyapatite nanofibers with enhanced dispersion

    OpenAIRE

    Chen, Liang; Xu, Changqi; Wang,Yong; Shi, Jian; Yu, Qingsong; Li, Hao

    2012-01-01

    The purpose of this research was to investigate the influence of the glyoxylic acid (GA) modification of hydroxyapatite (HAP) nanofibers on their dispersion in bisphenol A glycidyl methacrylate (BisGMA)/triethylene glycol dimethacrylate (TEGDMA) dental composites and also investigate the mechanical properties, water absorption, and water solubility of the resulting dental resins and composites. Scanning/Transmission electron microscopy (STEM) images showed that microsized HAP nanofiber bundle...

  2. Design and microfabrication of a high-aspect-ratio PDMS microbeam array for parallel nanonewton force measurement and protein printing

    Science.gov (United States)

    Sasoglu, F. M.; Bohl, A. J.; Layton, B. E.

    2007-03-01

    Cell and protein mechanics has applications ranging from cellular development to tissue engineering. Techniques such as magnetic tweezers, optic tweezers and atomic force microscopy have been used to measure cell deformation forces of the order of piconewtons to nanonewtons. In this study, an array of polymeric polydimethylsiloxane (PDMS) microbeams with diameters of 10-40 µm and lengths of 118 µm was fabricated from Sylgard® with curing agent concentrations ranging from 5% to 20%. The resulting spring constants were 100-300 nN µm-1. The elastic modulus of PDMS was determined experimentally at different curing agent concentrations and found to be 346 kPa to 704 kPa in a millimeter-scale array and ~1 MPa in a microbeam array. Additionally, the microbeam array was used to print laminin for the purpose of cell adhesion. Linear and nonlinear finite element analyses are presented and compared to the closed-from solution. The highly compliant, transparent, biocompatible PDMS may offer a method for more rapid throughput in cell and protein mechanics force measurement experiments with sensitivities necessary for highly compliant structures such as axons.

  3. Acoustic Scattering from Sand Dollars (Dendraster excentricus): Modeling as High Aspect Ratio Oblate Objects and Comparison to Experiment

    Science.gov (United States)

    2008-09-01

    naturally occurring dense collections. These benthic echinoderms can form concentrations of up to several hundred per square meter in the sandy, shallow...L. (1972). “A new approach to the shaded picture problem”, Proc ACM National Conf. Nichols, D. (1969). Echinoderms , 4th edition (Hutchinson & Co

  4. Sacrificial structures for deep reactive ion etching of high-aspect ratio kinoform silicon x-ray lenses

    DEFF Research Database (Denmark)

    Stöhr, Frederik; Michael-Lindhard, Jonas; Hübner, Jörg

    2015-01-01

    investigated how sacrificial structures in the form of guarding walls and pillars may be utilized to facilitate accurate control of the etch profile. Unlike other sacrificial structuring approaches, no silicon-on-insulator substrates or multiple lithography steps are required. In addition, the safe removal...

  5. Fundamentals of figure control and fracture-'free' finishing for high aspect ratio laser optics

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, Tayyab [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-01

    The high level objectives of the this work were to: 1) scientifically understand critical phenomena affecting the surface figure during full aperture finishing; 2) utilize these fundamentals to more deterministically control the surface figure during finishing; 3) successfully polish under rogue particle-‘free’ environments during polishing by understanding/preventing key sources of rogue particles.

  6. Effect of ac electrodeposition conditions on the growth of high aspect ratio copper nanowires in porous aluminum oxide templates.

    Science.gov (United States)

    Gerein, Nathan J; Haber, Joel A

    2005-09-22

    The effect of several deposition parameters on the uniformity of copper electrodeposition through the alumina barrier layer into porous aluminum oxide templates grown in sulfuric or oxalic acid was systematically investigated. A fractional factorial design of experiment was conducted to find suitable deposition conditions among the variables: frequency, voltage, pulsed or continuous deposition, electrolyte concentration, and barrier layer thinning voltage. Continuous ac sine wave deposition conditions yielded excellent uniformity of pore-filling but damaged the porous aluminum oxide templates when deposition was continued to grow bulk copper on the surface. Pulsed electrodeposition yielded comparable uniformity of pore-filling and no damage to the porous aluminum oxide templates, even when bulk copper was deposited on them. Further optimization of pulsed deposition conditions was accomplished by comparing square and sine waveforms and pulse polarity. Pulsed square waveforms produced better pore-filling than pulsed sine waveforms. For sine wave depositions, the oxidative/reductive pulse polarity was more efficient than the commonly used reductive/oxidative pulse polarity. For square wave depositions into sulfuric acid grown pores, the reductive/oxidative pulse polarity produces more uniform pore-filling, likely as a result of enhanced resonant tunneling through the barrier layer and reoxidation of copper in faster filling pores.

  7. Opportunities for high aspect ratio micro-electro-magnetic-mechanical systems (HAR-MEMMS) at Lawrence Berkeley Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, S. [ed.

    1993-10-01

    This report contains viewgraphs on the following topics: Opportunities for HAR-MEMMS at LBL; Industrial Needs and Opportunities; Deep Etch X-ray Lithography; MEMS Activities at BSAC; DNA Amplification with Microfabricated Reaction Chamber; Electrochemistry Research at LBL; MEMS Activities at LLNL; Space Microsensors and Microinstruments; The Advanced Light Source; Institute for Micromaching; IBM MEMS Interests; and Technology Transfer Opportunities at LBL.

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

    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...

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

    Data.gov (United States)

    National Aeronautics and Space Administration — Atomic layer deposited functional nano-film technology is used to manufacture Microchannel plate (MCP) devices capable of high gain / low ion feedback operation, on...

  10. Tailoring the Mechanical Properties of High-Aspect-Ratio Carbon Nanotube Arrays using Amorphous Silicon Carbide Coatings

    NARCIS (Netherlands)

    Poelma, R.H.; Morana, B.; Vollebregt, S.; Schlangen, H.E.J.G.; Van Zeijl, H.W.; Fan, X.; Zhang, G.Q.

    2014-01-01

    The porous nature of carbon nanotube (CNT) arrays allows for the unique opportunity to tailor their mechanical response by the infiltration and deposition of nanoscale conformal coatings. Here, we fabricate novel photo-lithographically defined CNT pillars that are conformally coated with amorphous

  11. Numerical simulation of parallel hole cut blasting with uncharged holes

    Institute of Scientific and Technical Information of China (English)

    Shijie Qu; Xiangbin Zheng; Lihua Fan; Ying Wang

    2008-01-01

    The cavity formation and propagation process of stress wave from parallel hole cut blasting was simulated with AN-SYS/LS-DYNA 3D nonlinear dynamic finite element software. The distribution of element plastic strain, node velocity, node time-acceleration history and the blasting cartridge volume ratio during the process were analyzed. It was found that the detonation of charged holes would cause the interaction of stress wave with the wall of uncharged holes. Initial rock cracking and displacement to neighboring uncharged holes become the main mechanism of cavity formation in early stage.

  12. Measurement of delta13C and delta18O Isotopic Ratios of CaCO3 by a Thermoquest Finnigan GasBench II Delta Plus XL Continous Flow Isotope Ratio Mass Spectrometer with Application to Devils Hole Core DH-11 Calcite

    Science.gov (United States)

    Revesz, Kinga M.; Landwehr, Jurate Maciunas; Keybl, Jaroslav Edward

    2001-01-01

    A new method was developed to analyze the stable carbon and oxygen isotope ratios of small samples (400?20 ?g) of calcium carbonate. This new method streamlines the classical phosphoric acid - calcium carbonate (H3PO4 - CaCO3) reaction method by making use of a Thermoquest-Finnigan GasBench II preparation device and a Delta Plus XL continuous flow isotope ratio mass spectrometer. To obtain reproducible and accurate results, optimal conditions for the H3PO4 - CaCO3 reaction had to be determined. At the acid-carbonate reaction temperature suggested by the equipment manufacturer, the oxygen isotope ratio results were unsatisfactory (standard deviation () greater than 1.5 per mill), probably because of a secondary reaction. When the acid-carbonate reaction temperature was lowered to 26?C and the reaction time was increased to 24 hours, the precision of the carbon and oxygen isotope ratios for duplicate analyses improved to 0.1 and 0.2 per mill, respectively. The method was tested by analyzing calcite from Devils Hole, Nevada, which was formed by precipitation from ground water onto the walls of a sub-aqueous cavern during the last 500,000 years. Isotope-ratio values previously had been obtained by the classical method for Devils Hole core DH-11. The DH-11 core had been recently re-sampled, and isotope-ratio values were obtained using this new method. The results were comparable to those obtained by the classical method. The consistency of the isotopic results is such that an alignment offset could be identified in the re-sampled core material, a cutting error that was then independently confirmed. The reproducibility of the isotopic values is demonstrated by a correlation of approximately 0.96 for both isotopes, after correcting for an alignment offset. This result indicates that the new method is a viable alternative to the classical method. In particular, the new method requires less sample material permitting finer resolution and allows automation of some processes

  13. Arrays of holes fabricated by electron-beam lithography combined with image reversal process using nickel pulse reversal plating

    Science.gov (United States)

    Awad, Yousef; Lavallée, Eric; Lau, Kien Mun; Beauvais, Jacques; Drouin, Dominique; Cloutier, Melanie; Turcotte, David; Yang, Pan; Kelkar, Prasad

    2004-05-01

    A critical issue in fabricating arrays of holes is to achieve high-aspect-ratio structures. Formation of ordered arrays of nanoholes in silicon nitride was investigated by the use of ultrathin hard etch mask formed by nickel pulse reversal plating to invert the tonality of a dry e-beam resist patterned by e-beam lithography. Ni plating was carried out using a commercial plating solution based on nickel sulfamate salt without organic additives. Reactive ion etching using SF6/CH4 was found to be very effective for pattern transfer to silicon nitride. Holes array of 100 nm diam, 270 nm period, and 400 nm depth was fabricated on a 5×5 mm2 area. .

  14. The closest black holes

    CERN Document Server

    Fender, Rob; Heywood, Ian

    2013-01-01

    Starting from the assumption that there is a large population (> 10^8) of isolated, stellar-mass black holes (IBH) distributed throughout our galaxy, we consider the detectable signatures of accretion from the interstellar medium (ISM) that may be associated with such a population. We simulate the nearby (radius 250 pc) part of this population, corresponding to the closest ~35 000 black holes, using current best estimates of the mass distribution of stellar mass black holes combined with two models for the velocity distribution of stellar-mass IBH which bracket likely possibilities. We distribute this population of objects appropriately within the different phases of the ISM and calculate the Bondi-Hoyle accretion rate, modified by a further dimensionless efficiency parameter \\lambda. Assuming a simple prescription for radiatively inefficient accretion at low Eddington ratios, we calculate the X-ray luminosity of these objects, and similarly estimate the radio luminosity from relations found empirically for b...

  15. Discharge Coefficient of 3-in-1 Hole with Various Inclination Angle and Hole Pitch

    Institute of Scientific and Technical Information of China (English)

    Li Guangchao; Zhu Huiren; Fan Huiming

    2008-01-01

    Discharge coefficients of 3-in- 1 hole of three inclination angles and three spacing between holes are presented which described the discharge behavior of a row of holes. The inlet and outlet of the 3-in-1 hole both have a 15° lateral expansion. The flow conditions considered are mainstream turbulence intensities and density ratios of secondary flow to mainstream. The momentum flux ratios varied in the range froom 1 to 4. The comparison is made of the discharge coefficients of three shaped holes to find an optimal hole with low flow loss. The results show that the discharge coefficients of 3-in-1 hole are highest in three shaped holes and therefore this article is focused on the measurements of discharge coefficients of 3-in-1 hole for various geometries and aerodynamic parameters. The measured results of 3-in-1 hole indicate that turbulence intensities, density ratios and momentum flux ratios have weak influence on discharge coefficients for inclination angle of 20°. The high turbulence intensity yields the small discharge coefficients for inclination angle of 45° and 90°.The increased both momentum flux ratios and density ratios lead to the increased discharge coefficients for inclination angle of 45° and 90°. The increased inclination angle causes the rapidly increased discharge coefficients. There is a weak dependence of discharge coefficients on hole pitches.

  16. Black holes

    CERN Document Server

    Chrúsciel, P T

    2002-01-01

    This paper is concerned with several not-quantum aspects of black holes, with emphasis on theoretical and mathematical issues related to numerical modeling of black hole space-times. Part of the material has a review character, but some new results or proposals are also presented. We review the experimental evidence for existence of black holes. We propose a definition of black hole region for any theory governed by a symmetric hyperbolic system of equations. Our definition reproduces the usual one for gravity, and leads to the one associated with the Unruh metric in the case of Euler equations. We review the global conditions which have been used in the Scri-based definition of a black hole and point out the deficiencies of the Scri approach. Various results on the structure of horizons and apparent horizons are presented, and a new proof of semi-convexity of horizons based on a variational principle is given. Recent results on the classification of stationary singularity-free vacuum solutions are reviewed. ...

  17. Instability of charged anti-de Sitter black holes

    Science.gov (United States)

    Gwak, Bogeun; Lee, Bum-Hoon; Ro, Daeho

    2016-10-01

    We have studied the instability of charged anti-de Sitter black holes in four- or higher-dimensions under fragmentation. The unstable black holes under fragmentation can be broken into two black holes. Instability depends not only on the mass and charge of the black hole but also on the ratio between the fragmented black hole and its predecessor. We have found that the near extremal black holes are unstable, and Schwarzschild-AdS black holes are stable. These are qualitatively similar to black holes in four dimensions and higher. The detailed instabilities are numerically investigated.

  18. Dyonic Non-Abelian Black Holes

    CERN Document Server

    Brihaye, Y; Kunz, J; Tell, N

    1999-01-01

    We study static spherically symmetric dyonic black holes in Einstein-Yang-Mills-Higgs theory. As for the magnetic non-abelian black holes, the domain of existence of the dyonic non-abelian black holes is limited with respect to the horizon radius and the dimensionless coupling constant $\\alpha$, which is proportional to the ratio of vector meson mass and Planck mass. At a certain critical value of this coupling constant, $\\hat \\alpha$, the maximal horizon radius is attained. We derive analytically a relation between $\\hat numerically. Besides the fundamental dyonic non-abelian black holes, we study radially excited dyonic non-abelian black holes and globally regular gravitating dyons.

  19. Coronal Holes

    Directory of Open Access Journals (Sweden)

    Steven R. Cranmer

    2009-09-01

    Full Text Available Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations, and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are established in the extended corona. For example, the importance of kinetic plasma physics and turbulence in coronal holes has been affirmed by surprising measurements from the UVCS instrument on SOHO that heavy ions are heated to hundreds of times the temperatures of protons and electrons. These observations point to specific kinds of collisionless Alfvén wave damping (i.e., ion cyclotron resonance, but complete theoretical models do not yet exist. Despite our incomplete knowledge of the complex multi-scale plasma physics, however, much progress has been made toward the goal of understanding the mechanisms ultimately responsible for producing the observed properties of coronal holes.

  20. Coronal Holes

    CERN Document Server

    Cranmer, Steven R

    2009-01-01

    Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations), and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are establish...

  1. Dumb holes: analogues for black holes.

    Science.gov (United States)

    Unruh, W G

    2008-08-28

    The use of sonic analogues to black and white holes, called dumb or deaf holes, to understand the particle production by black holes is reviewed. The results suggest that the black hole particle production is a low-frequency and low-wavenumber process.

  2. Are LIGO's Black Holes Made From Smaller Black Holes?

    Science.gov (United States)

    Kohler, Susanna

    2017-05-01

    all the hierarchical mergers are so-called major mergers i.e., the smaller black hole of the pair is at least 70% of the mass of the larger one.Distribution of spins for 4th-generation mergers, with two different mass ratios (q= 0.7 and q= 1) and initial first-generation spins (non-spinning and maximally spinning). [Fishbach et al. 2017]The authors find that hierarchical major mergers result in a distribution of spins with a distinctive shape, peaking at a spin of a 0.7 with relatively low contribution from spins below a 0.5. Intriguingly, this distribution is universal if you include several generations of mergers, the resulting spin distribution converges to the same shape every time. This is true regardless of the details of the hierarchical merger scenario, like the exact black hole mass ratio (as long as only major mergers occur) or the initial spin distributions.Testing the ModelWhat does this tell us? Since the hierarchical merger model predicts a very specific distribution of spins for the black holes detected by LIGO, we can compare future LIGO detections to see if theyre consistent with this model.The authors calculate the statistics to show that after order 100 LIGO detections, we should be able to tell whether these black holes are consistent with a hierarchical merger formation model or not. With luck, this could mean that we will have solved this mystery within a few years of advanced LIGO operations!CitationMaya Fishbach et al 2017 ApJL 840 L24. doi:10.3847/2041-8213/aa7045

  3. Black hole accretion disc impacts

    CERN Document Server

    Pihajoki, Pauli

    2015-01-01

    We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength {\\lambda} = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.

  4. Dyonic Non-Abelian Black Holes

    OpenAIRE

    Brihaye, Y.; Hartmann, B.; Kunz, J; Tell, N.

    1999-01-01

    We study static spherically symmetric dyonic black holes in Einstein-Yang-Mills-Higgs theory. As for the magnetic non-abelian black holes, the domain of existence of the dyonic non-abelian black holes is limited with respect to the horizon radius and the dimensionless coupling constant $\\alpha$, which is proportional to the ratio of vector meson mass and Planck mass. At a certain critical value of this coupling constant, $\\hat \\alpha$, the maximal horizon radius is attained. We derive analyti...

  5. High Aspect Pattern Formation by Integration of Micro Inkjetting and Electroless Plating

    CERN Document Server

    Gian, P W; Liang, Y N; Lok, B K; Lu, C W; Ooi, B L

    2008-01-01

    This paper reports on formation of high aspect micro patterns on low temperature co-fired ceramic (LTCC) substrates by integrating micro inkjetting with electroless plating. Micro inkjetting was realized by using an inkjetting printer that ejects ink droplets from a printhead. This printhead consists of a glass nozzle with a diameter of 50 micrometers and a piezoelectric transducer that is coated on the nozzle. The silver colloidal solution was inkjetted on a sintered CT800 ceramic substrate, followed by curing at 200 degrees C for 60 minutes. As a result, the silver trace with a thickness of 200 nm was obtained. The substrate, with the ejected silver thin film as the seed layer, was then immersed into a preinitiator solution to coat a layer of palladium for enhancing the deposition of nickel. Electroless nickel plating was successfully conducted at a rate of 0.39 micrometers /min, and the thickness of traces was plated up to 84 micrometers. This study demonstrates that the integration of inkjetting with plat...

  6. Dimensional verification of high aspect micro structures using FIB-SEM

    DEFF Research Database (Denmark)

    Zhang, Yang; Hansen, Hans Nørgaard

    2013-01-01

    Micro-structured surfaces are increasingly used for advanced functionality. In particular, micro-structured polymer parts are interesting due to the manufacturing via injection moulding. A micro-structured nickel surface was characterized by focussed ion beam-scanning electron microscope (FIB-SEM....... A cross sectioned sample was prepared for conventional SEM in order to inspect the geometry of the holes, but the cutting angle used when making the cross section had a significant influence on the obtained results. Via FIB-SEM, the process was recorded by images when slicing the sample layer by layer...

  7. Study on the performance of pressure drop ratio about a new type of down-hole axial oil-water separation cyclone%轴流式井下旋流油水分离器压降比性能研究

    Institute of Scientific and Technical Information of China (English)

    徐晓峰; 史仕荧

    2015-01-01

    在室内试验装置上对轴流式井下旋流油水分离器的压降比性能开展了相关试验研究。试验结果表明,压降比仅与分流比相关,与入口流量、入口含油率(<20%)、导流片结构无关;压降比与分流比的关系呈指数关系而非线性的。研究结果对新型油水分离器的工程设计和实际井下应用的自动控制具有重要意义。%An experimental investigation about the pressure drop ratio of down‐hole axial oil‐water separation cyclone was made .The result shows that the pressure drop ratio relied only on the split ratio instead of the inlet flow ,oil content or the guide vane’ structure .Besides ,the relation between the pressure drop ratio and split ratio is exponential relationship rather than linear .The research results have an important significance to the design and automatic control when using in down‐hole .

  8. Charged black holes in phantom cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, Mubasher; Qadir, Asghar; Rashid, Muneer Ahmad [National University of Sciences and Technology, Center for Advanced Mathematics and Physics, Rawalpindi (Pakistan)

    2008-11-15

    In the classical relativistic regime, the accretion of phantom-like dark energy onto a stationary black hole reduces the mass of the black hole. We have investigated the accretion of phantom energy onto a stationary charged black hole and have determined the condition under which this accretion is possible. This condition restricts the mass-to-charge ratio in a narrow range. This condition also challenges the validity of the cosmic-censorship conjecture since a naked singularity is eventually produced due to accretion of phantom energy onto black hole. (orig.)

  9. Micro-Hole Drilling on Glass Substrates—A Review

    Directory of Open Access Journals (Sweden)

    Lucas A. Hof

    2017-02-01

    Full Text Available Glass micromachining is currently becoming essential for the fabrication of micro-devices, including micro- optical-electro-mechanical-systems (MOEMS, miniaturized total analysis systems (μTAS and microfluidic devices for biosensing. Moreover, glass is radio frequency (RF transparent, making it an excellent material for sensor and energy transmission devices. Advancements are constantly being made in this field, yet machining smooth through-glass vias (TGVs with high aspect ratio remains challenging due to poor glass machinability. As TGVs are required for several micro-devices, intensive research is being carried out on numerous glass micromachining technologies. This paper reviews established and emerging technologies for glass micro-hole drilling, describing their principles of operation and characteristics, and their advantages and disadvantages. These technologies are sorted into four machining categories: mechanical, thermal, chemical, and hybrid machining (which combines several machining methods. Achieved features by these methods are summarized in a table and presented in two graphs. We believe that this paper will be a valuable resource for researchers working in the field of glass micromachining as it provides a comprehensive review of the different glass micromachining technologies. It will be a useful guide for advancing these techniques and establishing new hybrid ones, especially since this is the first broad review in this field.

  10. Wavelength-sized cavities in high aspect InP/InGaAsP/InP photonic crystals

    NARCIS (Netherlands)

    Kicken, H.H.J.E.; Barbu, I.; Van der Heijden, R.W.; Karouta, F.; Nötzel, R.; Van der Drift, E.; Salemink, H.W.M.

    2009-01-01

    The photonic properties of two classes of wavelength-sized cavities are reported for deeply etched InP/InGaAsP/InP planar photonic crystals. The high aspect, deeply etched structures are studied as potential building blocks for nonmembrane type photonic devices in standard InP photonic integrated ci

  11. PENURUNAN TINGKAT INTRUSI AIR LAUT BERDASARKAN "CHLORIDE BICARBONATE RATIO" MENGGUNAKAN LUBANG RESAPAN BIOPORI : STUDI KASUS DI KOTA SEMARANG (Decreased of Sea Water Intrusion Based On “Chloride-Bicarbonater Ratio”Using the Biopore Absorption Hole

    Directory of Open Access Journals (Sweden)

    Siti Sundari Miswadi

    2010-11-01

    Full Text Available ABSTRAK Banjir menjadi agenda tahunan bagi warga yang tinggal di daerah pinggiran pantai di Kota Semarang. Namun sekarang, wilayah yang jauh dari pantaipun kini sudah tidak luput dari banjir dan intrusi air laut. Hal ini terjadi karena airtanah sudah melebihi besarnya pengisian kembali (recharge, dan tanah sudah kehilangan fungsinya dalam menyerap air akibat maraknya pembangunan gedung dan perumahan yang tidak ramah lingkungan. Penelitian ini bertujuan untuk memetakan tingkat intrusi air laut di sumur-sumur gali berdasarkan "Chloride-Bicarbonate Ratio", dan daya hantar listrik (DHL serta salinitas di Kota Semarang. Penelitian dilakukan terhadap 30 sumur gali milik penduduk dengan jarak dari pantai antara 0,5-5 (lima kilometer. Tingkat intrusi air laut dihitung berdasarkan rasio klorida terhadap karbonat dan bikarbonat, dan hasilnya diplotkan pada peta dasar. Hasil penelitian menunjukkan, tingkat intrusi air laut dan nilai DHL di Kota Semarang bagian timur jauh lebih jelek dibandingkan dengan wilayah pantai sebelah barat Kota Semarang, sedangkan kadar salinitas di sebagian besar daerah penelitian rata-rata kadarnya sedang. Hasil penelitian menggunakan lubang resapan biopori (LRB sebagai adsorben menunjukkan, pada minggu ketiga setelah pembuatan LRB didapatkan tingkat intrusi air laut naik sebesar 66,64 % sumur, dan sebanyak 33,33% sumur turun tingkat intrusinya, sedangkan pada mingggu keenam terjadi penurunan tingkat intrusi sebesar 66,64% sumur, dan 33,33% sumur naik. Kadar salinitas pada minggu ketiga turun sebanyak 83,30 %sumur, dan 16,66% tetap, sedangkan pada minggu keenam 49,90 % sumur salinitasnya naik, 33,33% turun, dan 16,66% tetap. Nilai daya hantar tistrik (DHL pada minggu ketiga terdeteksi 16,66% sumur naik, dan 83,30% sumur turun, sedangkan pada minggu keenam 49,98 % sumur DHL-nya naik, dan 49,98% turun. Nilai pH pada minggu ketiga terdeteksi 100% sumur turun, sedangkan minggu kelima 66,64 % turun dan 33,33 % sumur p

  12. Deburring small intersecting holes

    Energy Technology Data Exchange (ETDEWEB)

    Gillespie, L.K.

    1980-08-01

    Deburring intersecting holes is one of the most difficult deburring tasks faced by many industries. Only 14 of the 37 major deburring processes are applicable to most intersecting hole applications. Only five of these are normally applicable to small or miniature holes. Basic process capabilities and techniques used as a function of hole sizes and intersection depths are summarized.

  13. Life inside black holes

    CERN Document Server

    Dokuchaev, V I

    2012-01-01

    We consider test planet and photon orbits of the third kind inside a black hole, which are stable, periodic and neither come out of the black hole nor terminate at the singularity. Interiors of supermassive black holes may be inhabited by advanced civilizations living on planets with the third-kind orbits. In principle, one can get information from the interiors of black holes by observing their white hole counterparts.

  14. Influences of Hole Shape on Film Cooling Characteristics with CO2 Injection

    Institute of Scientific and Technical Information of China (English)

    Li Guangchao; Zhu Huiren; Fan Huiming

    2008-01-01

    This article presents the data about heat transfer coefficient ratios, film cooling effectiveness and heat loads for the injection through cylindrical holes, 3-in-1 holes and fanned holes in order to characterize the film cooling performance downstream of a row of holes with 45° inclination and 3 hole spacing apart. The trip wire is placed upstream at a distance of 10 times diameter of the cooling hole from the hole center to keep mainstream fully turbulent. Both inlet and outlet of 3-in-1 holes have a 15° lateral expansion. The outlet of faaned holes has a lateral expansion. CO2 is applied for secondary injection to obtain a density ratio of 1.5. Momentum flux ratio varies from 1 to 4. The results indicate that the increased momentum flux ratio significantly inoreases heat transfer coefficient and slightly improve film cooling effectiveness for the injection through cylindrical holes. A weak dependence of heat transfer coefficient and film cooling effectiveness, respectively, on momentum flux ratio has been identified for the injection through 3-in-1 holes. The increase of the momentum flux ratio decreases heat transfer coefficient and significantly increases film cooling effectiveness for the injection through fanned holes. In terms of the film cooling performance, the fanned holes are the best while the cylindrical holes are the worst among the three hole shapes under study.

  15. Thermodynamic Properties of Higher-Dimensional RN Black Holes

    Institute of Scientific and Technical Information of China (English)

    WEI Yi-Huan

    2009-01-01

    A general calculation formula of the heat capacity for the HRN black holes is derived.The heat capacities for Q,Φ_+ and τ_- fixed are obtained. Assuming that the charge-mass ratio of fluctuation modes does not exceed the extremal value, the minimum charge-mass ratio of the black holes for which the heat capacity is positive is determined.

  16. Electrodynamics of Black Holes in STU Supergravity

    CERN Document Server

    Cvetic, M; Pope, C N; Saleem, Z H

    2013-01-01

    External magnetic fields can probe the composite structure of black holes in string theory. With this motivation we study magnetised four-charge black holes in the STU model, a consistent truncation of maximally supersymmetric supergravity with four types of electromagnetic fields. We employ solution generating techniques to obtain Melvin backgrounds, and black holes in these backgrounds. For an initially electrically charged static black hole immersed in magnetic fields, we calculate the resultant angular momenta and analyse their global structure. Examples are given for which the ergoregion does not extend to infinity. We calculate magnetic moments and gyromagnetic ratios via Larmor's formula. Our results are consistent with earlier special cases. A scaling limit and associated subtracted geometry in a single surviving magnetic field is shown to lift to $AdS_3\\times S^2$. Magnetizing magnetically charged black holes give static solutions with conical singularities representing strings or struts holding the ...

  17. Development of new hole expansion testing method

    Science.gov (United States)

    Kim, Hyunok; Shang, Jianhui; Beam, Kevin; Samant, Anoop; Hoschouer, Cliff; Dykeman, Jim

    2016-08-01

    This paper introduces a new hole expansion (HE) testing method that could be more relevant to the edge cracking problem observed in stamping advanced high strength steel (AHSS). The new testing method adopted a large hole diameter of 75 mm compared to the standard hole diameter of 10 mm. An inline monitoring system was developed to visually monitor the hole edge cracking during the test and synchronize the load-displacement data with the recorded video for capturing the initial crack. A new hole expansion testing method was found to be effective in evaluating the edge cracking by considering the effects of material properties and trimming methods. It showed a much larger difference, up to 11%, of the HE ratio between DP980 and TRIP780 compared to the standard HE testing method giving less than a 2% difference.

  18. Phantom Energy Accretion by a Stringy Charged Black Hole

    Institute of Scientific and Technical Information of China (English)

    M.Sharif; G.Abbas

    2012-01-01

    We investigate the dynamical behavior of phantom energy near a stringy magnetically charged black hole. For this purpose, we derive equations of motion for steady-state spherically symmetric Row of phantom energy onto the stringy magnetically charged black hole. It is found that phantom energy accreting onto a black hole decreases its mass. Further, the location of the critical points of accretion is explored, which yields a mass to charge ratio. This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity, hence cosmic censorship hypothesis remains valid here.%We investigate the dynamical behavior of phantom energy near a stringy magnetically charged black hole.For this purpose,we derive equations of motion for steady-state spherically symmetric flow of phantom energy onto the stringy magnetically charged black hole.It is found that phantom energy accreting onto a black hole decreases its mass.Further,the location of the critical points of accretion is explored,which yields a mass to charge ratio.This ratio implies that accretion process cannot transform a black hole into an extremal black hole or a naked singularity,hence cosmic censorship hypothesis remains valid here.

  19. Variable Deflection Response of Sensitive CNT-on-Fiber Artificial Hair Sensors from CNT Synthesis in High Aspect Ratio Microcavities (Postprint)

    Science.gov (United States)

    2015-04-01

    microstructures such as tailored hair shapes, micro-antennae, brushes, or filters . The CNT arrays are synthesized in a 1” diameter quartz tube furnace...Microstructure Growth,” ACS Nano, 8(6), 5799-5812 (2014). [17] P. B. Amama, C. L. Pint, L. McJilton et al., “Role of Water in Super Growth of Single...Garcia et al., “High-yield growth and morphology control of aligned carbon nanotubes on ceramic fibers for multifunctional enhancement of structural

  20. Technological and material related challenges for large area, high aspect-ratio, near teradot/inch2 areal density and three-dimensional structuring of polyaniline.

    Science.gov (United States)

    Jedrasik, Piotr; Vlad, Alexandru; Södervall, Ulf

    2011-10-01

    In this manuscript we report on a newly developed technology for the nanoscale processing of the conducting polyaniline (PANI) with an unprecedented areal patterning order and density control exceeding 0.25 teradot/inch2. High resolution electron beam lithography was used to generate ordered 2D and 3D templates. A novel type of resist and dose-modulated 3D-electron beam lithography (RDM-3D-EBL), extensively exploiting the intrinsic properties of resist-electron beam interaction is detailed. Surface initiated and template confined aniline polymerization, through catalytic activity of metallic platinum, was then exploited to provide a genuine method for controlled nanoscale processing of polyaniline, a prototypical conjugated polymer that definitively settled the concept of synthetic metals. Using nanoscale polymerization reactors, ultimate resolution patterning and processing control of single polyaniline nanostructures was feasible. Aspects of the nanoscale polyaniline growth mechanism are discussed and the highly controllable, sub-picogram scale fabrication is emphasized. Near teradot/inch2 pattern transfer technology, complex 3D structuring and physico-chemical functionalization of polyaniline can be subsequently harnessed to build a large variety of architectures with potential for emerging optoelectronic technologies. The method is scalable, can be applied on virtually any type of flexible or rigid substrates and provides a generic approach for nanopatterning surfaces with functional polymers. Technological and material related fabrication challenges are detailed and discussed.

  1. Catalytic Synthesis of Substrate-Free, Aligned and Tailored High Aspect Ratio Multiwall Carbon Nanotubes in an Ultrasonic Atomization Head CVD Reactor

    OpenAIRE

    Fahad Ali Rabbani; Zuhair Omar Malaibari; Muataz Ali Atieh; Ammar Jamie

    2016-01-01

    Chemical vapor deposition (CVD) method has proven its benchmark, over other methods, for the production of different types of carbon nanotubes (CNT) on commercial and lab scale. In this study, an injection vertical CVD reactor fitted with an ultrasonic atomization head was used in a pilot-plant scale (height 274 cm, radius 25 cm) for semicontinuous production of multiwall carbon nanotubes (MWCNTs). p-Xylene was used as a hydrocarbon precursor in which ferrocene was dissolved and provided the ...

  2. Fractionation and Characterization of High Aspect Ratio Gold Nanorods Using Asymmetric-Flow Field Flow Fractionation and Single Particle Inductively Coupled Plasma Mass Spectrometry

    OpenAIRE

    Nguyen, Thao M; Jingyu Liu; Vincent A. Hackley

    2015-01-01

    Gold nanorods (GNRs) are of particular interest for biomedical applications due to their unique size-dependent longitudinal surface plasmon resonance band in the visible to near-infrared. Purified GNRs are essential for the advancement of technologies based on these materials. Used in concert, asymmetric-flow field flow fractionation (A4F) and single particle inductively coupled mass spectrometry (spICP-MS) provide unique advantages for fractionating and analyzing the typically complex mixtur...

  3. Porous, one-dimensional and high aspect ratio nanofibric network of cobalt manganese oxide as a high performance material for aqueous and solid-state supercapacitor (2 V)

    Science.gov (United States)

    Bhagwan, Jai; Sivasankaran, V.; Yadav, K. L.; Sharma, Yogesh

    2016-09-01

    Porous nanofibric network of spinel CoMn2O4 (CMO) are fabricated by facile electrospinning process and characterized by XRD, BET, TGA, FTIR, FESEM, TEM, XPS techniques. CMO nanofibers are employed as supercapacitor electrode for first time which exhibits high specific capacitance (Cs) of 320(±5) F g-1 and 270(±5) F g-1 at 1 A g-1 and 5 A g-1, respectively in 1 M H2SO4. CMO nanofibers exhibit excellent cyclability (till 10,000 cycles @ 5 A g-1). To examine practical performance, solid-state symmetric supercapacitor (SSSC) is also fabricated using PVA-H2SO4 as gel electrolyte. The SSSC evinces high energy density of 75 W h kg-1 (comparable to Pb-acid and Ni-MH battery) along with high power density of 2 kW kg-1. Furthermore, a red colored LED (1.8 V @ current 20 mA) was lit for 5 min using single SSSC device supporting its output voltage of 2 V. This high performance of CMO in both aqueous and SSSC is attributed to one dimensional nanofibers consisting of voids/gaps with minimum inter-particle resistance that facilitates smoother transportation of electrons/ions. These voids/gaps in CMO (structural as well as morphological) act as intercalation/de-intercalation sites for extra storage performance, and also works as buffering space to accommodate stress/strain produced while long term cyclings.

  4. Fast plunges into Kerr black holes

    Energy Technology Data Exchange (ETDEWEB)

    Hadar, Shahar [Racah Institute of Physics, Hebrew University,Jerusalem 91904 (Israel); Porfyriadis, Achilleas P.; Strominger, Andrew [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States)

    2015-07-15

    Most extreme-mass-ratio-inspirals of small compact objects into supermassive black holes end with a fast plunge from an eccentric last stable orbit. For rapidly rotating black holes such fast plunges may be studied in the context of the Kerr/CFT correspondence because they occur in the near-horizon region where dynamics are governed by the infinite dimensional conformal symmetry. In this paper we use conformal transformations to analytically solve for the radiation emitted from fast plunges into near-extreme Kerr black holes. We find perfect agreement between the gravity and CFT computations.

  5. Higher spin black holes

    National Research Council Canada - National Science Library

    Gutperle, Michael; Kraus, Per

    2011-01-01

    .... We find solutions that generalize the BTZ black hole and carry spin-3 charge. The black hole entropy formula yields a result for the asymptotic growth of the partition function at finite spin-3 chemical potential...

  6. Black hole hair removal

    Science.gov (United States)

    Banerjee, Nabamita; Mandal, Ipsita; Sen, Ashoke

    2009-07-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair — degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  7. Black Hole Hair Removal

    CERN Document Server

    Banerjee, Nabamita; Sen, Ashoke

    2009-01-01

    Macroscopic entropy of an extremal black hole is expected to be determined completely by its near horizon geometry. Thus two black holes with identical near horizon geometries should have identical macroscopic entropy, and the expected equality between macroscopic and microscopic entropies will then imply that they have identical degeneracies of microstates. An apparent counterexample is provided by the 4D-5D lift relating BMPV black hole to a four dimensional black hole. The two black holes have identical near horizon geometries but different microscopic spectrum. We suggest that this discrepancy can be accounted for by black hole hair, -- degrees of freedom living outside the horizon and contributing to the degeneracies. We identify these degrees of freedom for both the four and the five dimensional black holes and show that after their contributions are removed from the microscopic degeneracies of the respective systems, the result for the four and five dimensional black holes match exactly.

  8. Fast plunges into Kerr black holes

    OpenAIRE

    Hadar, Shahar; Porfyriadis, Achilleas; Strominger, Andrew E.

    2015-01-01

    Most extreme-mass-ratio-inspirals of small compact objects into supermassive black holes end with a fast plunge from an eccentric last stable orbit. For rapidly rotating black holes such fast plunges may be studied in the context of the Kerr/CFT correspondence because they occur in the near-horizon region where dynamics are governed by the infinite dimensional conformal symmetry. In this paper we use conformal transformations to analytically solve for the radiation emitted from fast plunges i...

  9. Deep coronal hole associated with quiescent filament

    Science.gov (United States)

    Kesumaningrum, Rasdewita; Herdiwidjaya, Dhani

    2014-03-01

    We present a study of the morphology of quiescent filament observed by H-alpha Solar Telescope at Bosscha Observatory in association with coronal hole observed by Atmospheric Imaging Assembly (AIA) instrument in 193 Å from Solar Dynamics Observatory. H-alpha images were processed by imaging softwares, namely Iris 5.59 and ImageJ, to enhance the signal to noise ratio and to identify the filament features associated with coronal hole. For images observed on October 12, 2011, November 14, 2011 and January 2, 2012, we identified distinct features of coronal holes above the quiescent filaments. This associated coronal holes have filament-like morphology with a thick long thread as it's `spine', defined as Deep Coronal Hole. Because of strong magnetic field of sunspot, these filaments and coronal holes emerged far from active region and lasted for several days. It is interesting as for segmented filament, deep coronal holes above the filaments lasted for a quite long period of time and merged. This association between filament and deep coronal hole can be explained by filament magnetic loop.

  10. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-DomInguez, J C [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); Obregon, O [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico); RamIrez, C [Facultad de Ciencias FIsico Matematicas, Universidad Autonoma de Puebla, PO Box 1364, 72000 Puebla (Mexico); Sabido, M [Instituto de Fisica de la Universidad de Guanajuato PO Box E-143, 37150 Leoen Gto. (Mexico)

    2007-11-15

    We study noncommutative black holes, by using a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate Hawking's temperature and entropy for the 'noncommutative' Schwarzschild black hole.

  11. Black Hole Thermodynamics

    Science.gov (United States)

    Israel, Werner

    This chapter reviews the conceptual developments on black hole thermodynamics and the attempts to determine the origin of black hole entropy in terms of their horizon area. The brick wall model and an operational approach are discussed. An attempt to understand at the microlevel how the quantum black hole acquires its thermal properties is included. The chapter concludes with some remarks on the extension of these techniques to describing the dynamical process of black hole evaporation.

  12. Monopole black hole skyrmions

    OpenAIRE

    Moss, I. G.; Shiiki, N.; Winstanley, E.

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  13. Monopole Black Hole Skyrmions

    OpenAIRE

    Moss, I. G.; Shiiki, N.; Winstanley, E.

    2000-01-01

    Charged black hole solutions with pion hair are discussed. These can be\\ud used to study monopole black hole catalysis of proton decay.\\ud There also exist\\ud multi-black hole skyrmion solutions with BPS monopole behaviour.

  14. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs. Spin-dependen

  15. Ballistic hole magnetic microscopy

    NARCIS (Netherlands)

    Haq, E.; Banerjee, T.; Siekman, M.H.; Lodder, J.C.; Jansen, R.

    2005-01-01

    A technique to study nanoscale spin transport of holes is presented: ballistic hole magnetic microscopy. The tip of a scanning tunneling microscope is used to inject hot electrons into a ferromagnetic heterostructure, where inelastic decay creates a distribution of electron-hole pairs.

  16. Sound Hole Sound

    CERN Document Server

    Politzer, David

    2015-01-01

    The volume of air that goes in and out of a musical instrument's sound hole is related to the sound hole's contribution to the volume of the sound. Helmholtz's result for the simplest case of steady flow through an elliptical hole is reviewed. Measurements on multiple holes in sound box geometries and scales relevant to real musical instruments demonstrate the importance of a variety of effects. Electric capacitance of single flat plates is a mathematically identical problem, offering an alternate way to understand the most important of those effects. The measurements also confirm and illuminate aspects of Helmholtz's "bottle" resonator model as applied to musical instrument sound boxes and sound holes.

  17. Black holes in binary stars

    NARCIS (Netherlands)

    Wijers, R.A.M.J.

    1996-01-01

    Introduction Distinguishing neutron stars and black holes Optical companions and dynamical masses X-ray signatures of the nature of a compact object Structure and evolution of black-hole binaries High-mass black-hole binaries Low-mass black-hole binaries Low-mass black holes Formation of black holes

  18. Rotating black holes with scalar hair in three dimensions

    CERN Document Server

    Zou, De-Cheng; Wang, Bin; Xu, Wei

    2014-01-01

    We examine the first law of thermodynamics in (2+1)-dimensional rotating hairy black holes and find that the first law of black hole thermodynamics can be protected when the scalar field parameter $B$ is constrained to relate to the black hole size. We disclose the Hawking-Page phase transition between the hairy black holes and the pure thermal radiation. Moreover, we find that the free energies of the rotating hairy black holes depend on the ratio between the horizon size to the scalar field parameter $B$. We also compare the free energies for the hairy black hole and the BTZ black hole when they have the same temperature and angular momentum, and find that when this ratio is large, the BTZ black hole has smaller free energy which is a thermodynamically more preferred phase; but when the ratio is small, the hairy black hole has smaller free energy and there exists the possibility for the BTZ black hole to dress up scalar field and become hairy.

  19. On Accelerated Black Holes

    CERN Document Server

    Letelier, P S; Letelier, Patricio S.; Oliveira, Samuel R.

    1998-01-01

    The C-metric is revisited and global interpretation of some associated spacetimes are studied in some detail. Specially those with two event horizons, one for the black hole and another for the acceleration. We found that the spacetime fo an accelerated Schwarzschild black hole is plagued by either conical singularities or lack of smoothness and compactness of the black hole horizon. By using standard black hole thermodynamics we show that accelerated black holes have higher Hawking temperature than Unruh temperature. We also show that the usual upper bound on the product of the mass and acceleration parameters (<1/sqrt(27)) is just a coordinate artifact. The main results are extended to accelerated Kerr black holes. We found that they are not changed by the black hole rotation.

  20. Greybody factors for d-dimensional black holes

    DEFF Research Database (Denmark)

    Harmark, Troels; Natário, José; Schiappa, Ricardo

    2010-01-01

    Gravitational greybody factors are analytically computed for static, spherically symmetric black holes in d-dimensions, including black holes with charge and in the presence of a cosmological constant (where a proper definition of greybody factors for both asymptotically de Sitter and anti...... of the details of the black hole. For asymptotically de Sitter black holes the greybody factor is different for even or odd spacetime dimension, and proportional to the ratio of the areas of the event and cosmological horizons. For asymptotically Ads black holes the greybody factor has a rich structure in which...... universality is hidden in the transmission and reflection coefficients. For either charged or asymptotically de Sitter black holes the greybody factors are given by non-trivial functions, while for asymptotically Ads black holes the greybody factor precisely equals one (corresponding to pure blackbody emission...

  1. Greybody factors for d-dimensional black holes

    DEFF Research Database (Denmark)

    Harmark, Troels; Natário, José; Schiappa, Ricardo

    2010-01-01

    Gravitational greybody factors are analytically computed for static, spherically symmetric black holes in d-dimensions, including black holes with charge and in the presence of a cosmological constant (where a proper definition of greybody factors for both asymptotically de Sitter and anti...... of the details of the black hole. For asymptotically de Sitter black holes the greybody factor is different for even or odd spacetime dimension, and proportional to the ratio of the areas of the event and cosmological horizons. For asymptotically Ads black holes the greybody factor has a rich structure in which...... universality is hidden in the transmission and reflection coefficients. For either charged or asymptotically de Sitter black holes the greybody factors are given by non-trivial functions, while for asymptotically Ads black holes the greybody factor precisely equals one (corresponding to pure blackbody emission)....

  2. Primordial Universe Inside the Black Hole and Inflation

    CERN Document Server

    Firouzjahi, Hassan

    2016-01-01

    We speculate that the early Universe was inside a primordial black hole. The interior of the the black hole is a dS background and the two spacetimes are separated on the surface of black hole's event horizon. We argue that this picture provides a natural realization of inflation without invoking the inflaton field. The black hole evaporation by Hawking radiation provides a natural mechanism for terminating inflation so reheating and the hot big bang cosmology starts from the evaporation of black hole to relativistic particles. The quantum gravitational fluctuations at the boundary of black hole generate the nearly scale invariant scalar and tensor perturbations with the ratio of tensor to scalar power spectra at the order of $10^{-3}$. As the black hole evaporates, the radius of its event horizon shrinks and the Hubble expansion rate during inflation increases slowly so the quantum Hawking radiation provides a novel mechanism for the violation of null energy condition in cosmology.

  3. Black Hole Spectroscopy: Testing General Relativity through Gravitational Wave Observations

    CERN Document Server

    Dreyer, O; Krishnan, B; Finn, L S; Garrison, D; López-Aleman, R; Dreyer, Olaf; Kelly, Bernard; Krishnan, Badri; Finn, Lee Samuel; Garrison, David; Lopez-Aleman, Ramon

    2004-01-01

    Assuming that general relativity is the correct theory of gravity in the strong field limit, can gravitational wave observations distinguish between black hole and other compact object sources? Alternatively, can gravitational wave observations provide a test of one of the fundamental predictions of general relativity? Here we describe a definitive test of the hypothesis that observations of damped, sinusoidal gravitational waves originated from a black hole or, alternatively, that nature respects the general relativistic no-hair theorem. For astrophysical black holes, which have a negligible charge-to-mass ratio, the black hole quasi-normal mode spectrum is characterized entirely by the black hole mass and angular momentum and is unique to black holes. In a different theory of gravity, or if the observed radiation arises from a different source (e.g., a neutron star, strange matter or boson star), the spectrum will be inconsistent with that predicted for general relativistic black holes. We give a statistica...

  4. Mass of a black hole firewall.

    Science.gov (United States)

    Abramowicz, M A; Kluźniak, W; Lasota, J-P

    2014-03-07

    Quantum entanglement of Hawking radiation has been supposed to give rise to a Planck density "firewall" near the event horizon of old black holes. We show that Planck density firewalls are excluded by Einstein's equations for black holes of mass exceeding the Planck mass. We find an upper limit of 1/(8πM) to the surface density of a firewall in a Schwarzschild black hole of mass M, translating for astrophysical black holes into a firewall density smaller than the Planck density by more than 30 orders of magnitude. A strict upper limit on the firewall density is given by the Planck density times the ratio M(Pl)/(8πM).

  5. Braneworld Black Holes

    CERN Document Server

    Whisker, Richard

    2008-01-01

    In this thesis we investigate black holes in the Randall-Sundrum braneworld scenario. We begin with an overview of extra-dimensional physics, from the original proposal of Kaluza and Klein up to the modern braneworld picture of extra dimensions. A detailed description of braneworld gravity is given, with particular emphasis on its compatibility with experimental tests of gravity. We then move on to a discussion of static, spherically symmetric braneworld black hole solutions. Assuming an equation of state for the ``Weyl term'', which encodes the effects of the extra dimension, we are able to classify the general behaviour of these solutions. We then use the strong field limit approach to investigate the gravitational lensing properties of some candidate braneworld black hole solutions. It is found that braneworld black holes could have significantly different observational signatures to the Schwarzschild black hole of standard general relativity. Rotating braneworld black hole solutions are also discussed, an...

  6. Astrophysical black holes

    CERN Document Server

    Gorini, Vittorio; Moschella, Ugo; Treves, Aldo; Colpi, Monica

    2016-01-01

    Based on graduate school lectures in contemporary relativity and gravitational physics, this book gives a complete and unified picture of the present status of theoretical and observational properties of astrophysical black holes. The chapters are written by internationally recognized specialists. They cover general theoretical aspects of black hole astrophysics, the theory of accretion and ejection of gas and jets, stellar-sized black holes observed in the Milky Way, the formation and evolution of supermassive black holes in galactic centers and quasars as well as their influence on the dynamics in galactic nuclei. The final chapter addresses analytical relativity of black holes supporting theoretical understanding of the coalescence of black holes as well as being of great relevance in identifying gravitational wave signals. With its introductory chapters the book is aimed at advanced graduate and post-graduate students, but it will also be useful for specialists.

  7. Extremal Hairy Black Holes

    CERN Document Server

    Gonzalez, P A; Saavedra, Joel; Vasquez, Yerko

    2014-01-01

    We consider a gravitating system consisting of a scalar field minimally coupled to gravity with a self-interacting potential and an U(1) electromagnetic field. Solving the coupled Einstein-Maxwell-scalar system we find exact hairy charged black hole solutions with the scalar field regular everywhere. We go to the zero temperature limit and we study the effect of the scalar field on the near horizon geometry of an extremal black hole. We find that except a critical value of the charge of the black hole there is also a critical value of the charge of the scalar field beyond of which the extremal black hole is destabilized. We study the thermodynamics of these solutions and we find that if the space is flat then at low temperature the Reissner-Nordstr\\"om black hole is thermodynamically preferred, while if the space is AdS the hairy charged black hole is thermodynamically preferred at low temperature.

  8. Charged Lifshitz Black Holes

    OpenAIRE

    Dehghani, M. H.; Pourhasan, R.; Mann, R. B.

    2011-01-01

    We investigate modifications of the Lifshitz black hole solutions due to the presence of Maxwell charge in higher dimensions for arbitrary $z$ and any topology. We find that the behaviour of large black holes is insensitive to the topology of the solutions, whereas for small black holes significant differences emerge. We generalize a relation previously obtained for neutral Lifshitz black branes, and study more generally the thermodynamic relationship between energy, entropy, and chemical pot...

  9. Perturbations around black holes

    CERN Document Server

    Wang, B

    2005-01-01

    Perturbations around black holes have been an intriguing topic in the last few decades. They are particularly important today, since they relate to the gravitational wave observations which may provide the unique fingerprint of black holes' existence. Besides the astrophysical interest, theoretically perturbations around black holes can be used as testing grounds to examine the proposed AdS/CFT and dS/CFT correspondence.

  10. Physics of black holes

    OpenAIRE

    Thorne, Kip S.

    1982-01-01

    The activity at the galactic center might be fuelled by energy release near a large black hole. In this talk I describe some relativistic effects which may be relevant to this process. I use Newtonian language so far as possible and illustrate the effects with simple  analogies. Specifically, I describe the gravitational field near a black hole, Lens‐Thirring and geodetic precession, electro‐magnetic energy extraction of the spin energy of a black hole and the structure of accretion tori arou...

  11. Asymptotic black holes

    Science.gov (United States)

    Ho, Pei-Ming

    2017-04-01

    Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.

  12. Asymptotic Black Holes

    CERN Document Server

    Ho, Pei-Ming

    2016-01-01

    Following earlier works on the KMY model of black-hole formation and evaporation, we construct the metric for a matter sphere in gravitational collapse, with the back-reaction of pre-Hawking radiation taken into consideration. The mass distribution and collapsing velocity of the matter sphere are allowed to have an arbitrary radial dependence. We find that a generic gravitational collapse asymptote to a universal configuration which resembles a black hole but without horizon. This approach clarifies several misunderstandings about black-hole formation and evaporation, and provides a new model for black-hole-like objects in the universe.

  13. Black Hole Dynamic Potentials

    Indian Academy of Sciences (India)

    Koustubh Ajit Kabe

    2012-09-01

    In the following paper, certain black hole dynamic potentials have been developed definitively on the lines of classical thermodynamics. These potentials have been refined in view of the small differences in the equations of the laws of black hole dynamics as given by Bekenstein and those of thermodynamics. Nine fundamental black hole dynamical relations have been developed akin to the four fundamental thermodynamic relations of Maxwell. The specific heats , and , have been defined. For a black hole, these quantities are negative. The d equation has been obtained as an application of these fundamental relations. Time reversible processes observing constancy of surface gravity are considered and an equation connecting the internal energy of the black hole , the additional available energy defined as the first free energy function , and the surface gravity , has been obtained. Finally as a further application of the fundamental relations, it has been proved for a homogeneous gravitational field in black hole space times or a de Sitter black hole that $C_{\\Omega,\\Phi}-C_{J,Q}=\\kappa \\left[\\left(\\dfrac{\\partial J}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial \\Omega}{\\partial \\kappa}\\right)_{J,Q}+\\left(\\dfrac{\\partial Q}{\\partial \\kappa}\\right)_{\\Omega,\\Phi}\\left(\\dfrac{\\partial\\Phi}{\\partial \\kappa}\\right)_{J,Q}\\right]$. This is dubbed as the homogeneous fluid approximation in context of the black holes.

  14. Black holes matter

    DEFF Research Database (Denmark)

    Kragh, Helge Stjernholm

    2016-01-01

    Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015).......Review essay, Marcia Bartusiak, Black Hole: How an Idea Abandoned by Newtonians, Hated by Einstein, and Gambled On by Hawking Became Loved (New Haven: Yale University Press, 2015)....

  15. Perturbing supersymmetric black hole

    CERN Document Server

    Onozawa, H; Mishima, T; Ishihara, H; Onozawa, Hisashi; Okamura, Takashi; Mishima, Takashi; Ishihara, Hideki

    1996-01-01

    An investigation of the perturbations of the Reissner-Nordstr\\"{o}m black hole in the N=2 supergravity is presented. In the extreme case, the black hole responds to the perturbation of each field in the same manner. This is possibly because we can match the modes of the graviton, gravitino, and photon using supersymmetry transformations.

  16. Black hole levitron

    NARCIS (Netherlands)

    Arsiwalla, X.D.; Verlinde, E.P.

    2010-01-01

    We study the problem of spatially stabilizing four dimensional extremal black holes in background electric/magnetic fields. Whilst looking for stationary stable solutions describing black holes placed in external fields we find that taking a continuum limit of Denef et al.’s multicenter

  17. Newborn Black Holes

    Science.gov (United States)

    Science Teacher, 2005

    2005-01-01

    Scientists using NASA's Swift satellite say they have found newborn black holes, just seconds old, in a confused state of existence. The holes are consuming material falling into them while somehow propelling other material away at great speeds. "First comes a blast of gamma rays followed by intense pulses of x-rays. The energies involved are much…

  18. Scattering by Black Holes

    CERN Document Server

    Andersson, N

    2000-01-01

    This is a chapter on Black-hole Scattering that was commissioned for an Encyclopaedia on Scattering edited by Pike and Sabatier, to be published by Academic Press. The chapter surveys wave propagation in black-hole spacetimes, diffraction effects in wave scattering, resonances, quasinormal modes and related topics.

  19. Disregarding the 'Hole Argument'

    CERN Document Server

    Roberts, Bryan W

    2014-01-01

    Jim Weatherall has suggested that Einstein's hole argument, as presented by Earman and Norton (1987), is based on a misleading use of mathematics. I argue on the contrary that Weatherall demands an implausible restriction on how mathematics is used. The hole argument, on the other hand, is in no new danger at all.

  20. Lifshitz Topological Black Holes

    CERN Document Server

    Mann, R B

    2009-01-01

    I find a class of black hole solutions to a (3+1) dimensional theory gravity coupled to abelian gauge fields with negative cosmological constant that has been proposed as the dual theory to a Lifshitz theory describing critical phenomena in (2+1) dimensions. These black holes are all asymptotic to a Lifshitz fixed point geometry and depend on a single parameter that determines both their area (or size) and their charge. Most of the solutions are obtained numerically, but an exact solution is also obtained for a particular value of this parameter. The thermodynamic behaviour of large black holes is almost the same regardless of genus, but differs considerably for small black holes. Screening behaviour is exhibited in the dual theory for any genus, but the critical length at which it sets in is genus-dependent for small black holes.

  1. Cosmological Black Holes

    CERN Document Server

    Stornaiolo, C

    2002-01-01

    In this letter we propose the existence of low density black holes and discuss its compatibility with the cosmological observations. The origin of these black holes can be traced back to the collapse of long wavelength cosmological perturbations during the matter dominated era, when the densities are low enough to neglect any internal and thermal pressure. By introducing a threshold density $\\hat{\\rho}$ above which pressure and non-gravitational interactions become effective, we find the highest wavelength for the perturbations that can reach an equilibrium state instead of collapsing to a black hole. The low density black holes introduced here, if they exist, can be observed through weak and strong gravitational lensing effects. Finally we observe that we obtained here a cosmological model which is capable to explain in a qualitative way the void formation together with the value $\\Omega=1$. But we remark that it needs to be improved by considering non spherical symmetric black holes.

  2. Primordial Black Hole Baryogenesis

    CERN Document Server

    Baumann, D; Turok, N G; Baumann, Daniel; Steinhardt, Paul J.; Turok, Neil

    2007-01-01

    We reconsider the possibility that the observed baryon asymmetry was generated by the evaporation of primordial black holes that dominated the early universe. We present a simple derivation showing that the baryon asymmetry is insensitive to the initial black hole density and the cosmological model but is sensitive to the temperature-dependence of the CP and baryon-violating (or lepton-violating) interactions. We also consider the possibility that black holes stop evaporating and form Planck-mass remnants that act as dark matter. We show that primordial black holes cannot simultaneously account for both the observed baryon asymmetry and the (remnant) dark matter density unless the magnitude of CP violation is much greater than expected from most particle physics models. Finally, we apply these results to ekpyrotic/cyclic models, in which primordial black holes may form when branes collide. We find that obtaining the observed baryon asymmetry is compatible with the other known constraints on parameters.

  3. Probing Black Holes With Gravitational Radiation

    Science.gov (United States)

    Cornish, Neil J.

    2006-09-01

    Gravitational radiation can provide unique insights into the dynamics and evolution of black holes. Gravitational waveforms encode detailed information about the spacetime geometry, much as the sounds made by a musical instrument reflect the geometry of the instrument. The LISA gravitational wave observatory will be able to record black holes colliding out to the edge of the visible Universe, with an expected event rate of tens to thousands per year. LISA has unmatched capabilities for studying the role of black holes in galactic evolution, in particular, by studying the mergers of seed black holes at very high redshift, z > 5. Merger events at lower redshift will be detected at extremely high signal-to-noise, allowing for precision tests of the black hole paradigm. Below z=1 LISA will be able to record stellar remnants falling into supermassive black holes. These extreme mass ratio inspiral events will yield insights into the dynamics of galactic cusps, and the brighter events will provide incredibly precise tests of strong field, dynamical gravity.

  4. The catalog of nearby black hole candidates

    CERN Document Server

    Caramete, Laurentiu I

    2011-01-01

    Context. In order to study the association of the origin of ultra high energy cosmic rays (UHECR) with active galactic nuclei (AGN) at all levels of their activity we require an unbiased sample of black holes. Aims. Here we describe such a sample, of about 6 000 black holes, within the local Universe, inside the GZK (Greisen Zatsepin Kuzmin) limit, around 100 Mpc. Methods. The starting point is the 2 micron all sky survey, with the next steps as: test its com- pleteness down to low flux densities, confine it to redshifts z < 0.025, limit it to early Hubble type galaxies, test with B-V colors and with the FIR/Radio ratio the possible separation in classes of sources for the ultra high energy cosmic rays, use the spheroidal stellar component - black hole mass relationship to derive black hole masses, and test them with known black hole masses. Results. The statistics are consistent with the mass function of black hole masses, with a rel- atively flat distribution to about 10^8 Msol, and thereafter a very ste...

  5. Black Hole Critical Phenomena Without Black Holes

    CERN Document Server

    Liebling, S L

    2000-01-01

    Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.

  6. Binary pairs of supermassive black holes - Formation in merging galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Valtaoja, L.; Valtonen, M.J.; Byrd, G.G. (Turku Univ. (Finland); Alabama Univ., Tuscaloosa (USA))

    1989-08-01

    A process in which supermassive binary blackholes are formed in nuclei of supergiant galaxies due to galaxy mergers is examined. There is growing evidence that mergers of galaxies are common and that supermassive black holes in center of galaxies are also common. Consequently, it is expected that binary black holes should arise in connection with galaxy mergers. The merger process in a galaxy modeled after M87 is considered. The capture probability of a companion is derived as a function of its mass. Assuming a correlation between the galaxy mass and the blackholes mass, the expected mass ratio in binary black holes is calculated. The binary black holes formed in this process are long lived, surviving longer than the Hubble time unless they are perturbed by black holes from successive mergers. The properties of these binaries agree with Gaskell's (1988) observational work on quasars and its interpretation in terms of binary black holes. 39 refs.

  7. Bearing Behavior of Drilled and Molded-in Holes

    Science.gov (United States)

    Durante, Massimo; Langella, Antonio

    2009-10-01

    Glass/epoxy composites were manufactured using RIFT (Resin Infusion under Flexible Tool), a closed mould process capable of obtaining large and complex forms, by impregnating, under a vacuum, a dry preform placed on a flat rigid mould. At certain points of these composite laminates, molded-in holes were made in the dry perform before the resin infusion phase, using two different methods: displacing or cutting the yarn of the fibers. After the resin treatment, other holes were made in the same laminates by drilling. Single-point pin-loaded specimens, cut from laminates, were tested for different values of specimen width-to-hole diameter ratio (W/D) and edge distance-to-hole diameter ratio. In the results of the experiment, the specimens with molded in holes made by displacing the fiber yarn showed higher bearing strength values.

  8. Scalarized Hairy Black Holes

    CERN Document Server

    Kleihaus, Burkhard; Yazadjiev, Stoytcho

    2015-01-01

    In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  9. Primordial Black Holes

    CERN Document Server

    MacGibbon, Jane H; Linnemann, J T; Marinelli, S S; Stump, D; Tollefson, K

    2015-01-01

    Primordial Black Holes (PBHs) are of interest in many cosmological contexts. PBHs lighter than about 1012 kg are predicted to be directly detectable by their Hawking radiation. This radiation should produce both a diffuse extragalactic gamma-ray background from the cosmologically-averaged distribution of PBHs and gamma-ray burst signals from individual light black holes. The Fermi, Milagro, Veritas, HESS and HAWC observatories, in combination with new burst recognition methodologies, offer the greatest sensitivity for the detection of such black holes or placing limits on their existence.

  10. Black Hole Entropy

    OpenAIRE

    P. Mitra

    1994-01-01

    In the talk different definitions of the black hole entropy are discussed and compared. It is shown that the Bekenstein-Hawking entropy $S^{BH}$ (defined by the response of the free energy of a system containing a black hole on the change of the temperature) differs from the statistical- mechanical entropy $S^{SM}=-\\mbox{Tr}(\\hat{\\rho}\\ln \\hat{\\rho})$ (defined by counting internal degrees of freedom of a black hole). A simple explanation of the universality of the Bekenstein-Hawking entropy (...

  11. Black hole entropy

    CERN Document Server

    Frolov, V

    1994-01-01

    In the talk different definitions of the black hole entropy are discussed and compared. It is shown that the Bekenstein-Hawking entropy S^{BH} (defined by the response of the free energy of a system containing a black hole on the change of the temperature) differs from the statistical- mechanical entropy S^{SM}=-\\mbox{Tr}(\\hat{\\rho}\\ln \\hat{\\rho}) (defined by counting internal degrees of freedom of a black hole). A simple explanation of the universality of the Bekenstein-Hawking entropy (i.e. its independence of the number and properties of the fields which might contribute to S^{SM}) is given.

  12. Scalarized hairy black holes

    Energy Technology Data Exchange (ETDEWEB)

    Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kunz, Jutta [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Yazadjiev, Stoytcho [Department of Theoretical Physics, Faculty of Physics, Sofia University, Sofia 1164 (Bulgaria)

    2015-05-11

    In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  13. Scalarized hairy black holes

    Directory of Open Access Journals (Sweden)

    Burkhard Kleihaus

    2015-05-01

    Full Text Available In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.

  14. Black holes new horizons

    CERN Document Server

    Hayward, Sean Alan

    2013-01-01

    Black holes, once just fascinating theoretical predictions of how gravity warps space-time according to Einstein's theory, are now generally accepted as astrophysical realities, formed by post-supernova collapse, or as supermassive black holes mysteriously found at the cores of most galaxies, powering active galactic nuclei, the most powerful objects in the universe. Theoretical understanding has progressed in recent decades with a wider realization that local concepts should characterize black holes, rather than the global concepts found in textbooks. In particular, notions such as trapping h

  15. Black Hole Thermodynamics

    CERN Document Server

    Carlip, S

    2014-01-01

    The discovery in the early 1970s that black holes radiate as black bodies has radically affected our understanding of general relativity, and offered us some early hints about the nature of quantum gravity. In this chapter I will review the discovery of black hole thermodynamics and summarize the many independent ways of obtaining the thermodynamic and (perhaps) statistical mechanical properties of black holes. I will then describe some of the remaining puzzles, including the nature of the quantum microstates, the problem of universality, and the information loss paradox.

  16. Influence of delay interval on blasting efficiency of parallel hole cuts with an empty hole

    Institute of Scientific and Technical Information of China (English)

    Qi Zhang; Dachao Lin

    2003-01-01

    Time interval of short delay ignition is an important factor to affect the efficiency of blasting cuts. The motion process of rock pieces in the cut cavity is analyzed, a mechanical model to calculate the delay time of parallel hole cuts is presented for tunnel blasting, and a theoretical method to determine the volume ratio (the clearage rate) of the rock pieces within the cut cavity at different moments is proposed for the blasting cut with an empty hole. Numerical analysis results show that the optimal delay interval is proportional to the borehole depth. The suggested results are of practical value to the optimal design of the delay interval in millisecond blasting related to the parallel hole cuts with an empty hole.

  17. Numerical analysis of drilling hole work-hardening effects in hole-drilling residual stress measurement

    Science.gov (United States)

    Li, H.; Liu, Y. H.

    2008-11-01

    The hole-drilling strain gage method is an effective semi-destructive technique for determining residual stresses in the component. As a mechanical technique, a work-hardening layer will be formed on the surface of the hole after drilling, and affect the strain relaxation. By increasing Young's modulus of the material near the hole, the work-hardening layer is simplified as a heterogeneous annulus. As an example, two finite rectangular plates submitted to different initial stresses are treated, and the relieved strains are measured by finite element simulation. The accuracy of the measurement is estimated by comparing the simulated residual stresses with the given initial ones. The results are shown for various hardness of work-hardening layer. The influence of the relative position of the gages compared with the thickness of the work-hardening layer, and the effect of the ratio of hole diameter to work-hardening layer thickness are analyzed as well.

  18. Black hole critical phenomena without black holes

    Indian Academy of Sciences (India)

    Steven L Liebling

    2000-10-01

    Studying the threshold of black hole formation via numerical evolution has led to the discovery of fascinating nonlinear phenomena. Power-law mass scaling, aspects of universality, and self-similarity have now been found for a large variety of models. However, questions remain. Here I briefly review critical phenomena, discuss some recent results, and describe a model which demonstrates similar phenomena without gravity.

  19. Black hole quantum spectrum

    National Research Council Canada - National Science Library

    Corda, Christian

    2013-01-01

    Introducing a black hole (BH) effective temperature, which takes into account both the non-strictly thermal character of Hawking radiation and the countable behavior of emissions of subsequent Hawking quanta, we recently re...

  20. Holographic black hole chemistry

    National Research Council Canada - National Science Library

    Karch, Andreas; Robinson, Brandon

    2015-01-01

    Thermodynamic quantities associated with black holes in Anti-de Sitter space obey an interesting identity when the cosmological constant is included as one of the dynamical variables, the generalized Smarr relation...

  1. Braneworld black holes

    CERN Document Server

    Gregory, Ruth

    2008-01-01

    In these lectures, I give an introduction to and overview of braneworlds and black holes in the context of warped compactifications. I first describe the general paradigm of braneworlds, and introduce the Randall-Sundrum model. I discuss braneworld gravity, both using perturbation theory, and also non perturbative results. I then discuss black holes on the brane, the obstructions to finding exact solutions, and ways of tackling these difficulties. I describe some known solutions, and conclude with some open questions and controversies.

  2. Holes in Heisenberg antiferromagnets

    Science.gov (United States)

    Chen, Yang

    1990-05-01

    In this Brief Report we show that a recent model proposed by Shankar [Phys. Rev. Lett. 63, 203 (1989)], describing the motion of holes in quantum antiferromagnets is equivalent to the Schwinger model [Phys. Rev. 128, 2425 (1962)] in 1+1 dimensions. Some exact results are deduced. In addition to the superconducting long-range order found by Shankar, it is shown that there is a 2pF hole density wave existing with the superconducting pairing instability.

  3. Life Inside Black Holes

    Science.gov (United States)

    Dokuchaev, Vyacheslav

    2013-11-01

    It is considered the test planet and photon orbits of the third kind inside the black hole (BH), which are stable, periodic and neither come out the BH nor terminate at the central singularity. Interiors of the supermassive BHs may be inhabited by advanced civilizations living on the planets with the third kind orbits. In principle, one can get information from the interiors of BHs by observing their white hole counterparts.

  4. Modelling quantum black hole

    CERN Document Server

    Govindarajan, T R

    2016-01-01

    Novel bound states are obtained for manifolds with singular potentials. These singular potentials require proper boundary conditions across boundaries. The number of bound states match nicely with what we would expect for black holes. Also they serve to model membrane mechanism for the black hole horizons in simpler contexts. The singular potentials can also mimic expanding boundaries elegantly, there by obtaining appropriately tuned radiation rates.

  5. Hydrodynamics and black holes

    CERN Document Server

    Oz, Yaron

    2015-01-01

    This chapter describes how the AdS/CFT correspondence (the Holographic Principle) relates field theory hydrodynamics to perturbations of black hole (brane) gravitational backgrounds. The hydrodynamics framework is first presented from the field theory point of view, after which the dual gravitational description is outlined, first for relativistic fluids and then for the nonrelativistic case. Further details of the fluid/gravity correspondence are then discussed, including the bulk geometry and the dynamics of the black hole horizon.

  6. Black hole geometrothermodynamics

    Science.gov (United States)

    Quevedo, Hernando

    2017-03-01

    We review the main aspects of geometrothermodynamics which is a geometric formalism to describe thermodynamic systems, taking into account the invariance of classical thermodynamics with respect to Legendre transformations. We focus on the particular case of black holes, and present a Riemannian metric which describes the corresponding space of equilibrium states. We show that this metric can be used to describe the stability properties and phase transition structure of black holes in different gravity theories.

  7. Helical superconducting black holes.

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P

    2012-05-25

    We construct novel static, asymptotically five-dimensional anti-de Sitter black hole solutions with Bianchi type-VII(0) symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have a vanishing entropy and approach domain wall solutions that reveal homogenous, nonisotropic dual ground states with an emergent scaling symmetry.

  8. Black Hole Induced Ejections

    OpenAIRE

    Pelletier, G.

    2004-01-01

    Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and consequently high energy phenomena take place. Therefore Black Holes, which are very likely at the origin of powerfull astrophysical phenomena such as AGNs, micro- quasars and GRBs where relativistic ejections are observed, are at the heart of high energy a...

  9. Charged Galileon black holes

    Science.gov (United States)

    Babichev, Eugeny; Charmousis, Christos; Hassaine, Mokhtar

    2015-05-01

    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematically compatible with the field equations. This opens up the possibility for novel searches of hairy black holes in a far more general setting of Horndeski theory.

  10. Ultramassive Black Hole Coalescence

    CERN Document Server

    Khan, Fazeel; Berczik, Peter

    2015-01-01

    Although supermassive black holes (SMBHs) correlate well with their host galaxies, there is an emerging view that outliers exist. Henize 2-10, NGC 4889, and NGC1277 are examples of SMBHs at least an order of magnitude more massive than their host galaxy suggests. The dynamical effects of such ultramassive central black holes is unclear. Here, we perform direct N-body simulations of mergers of galactic nuclei where one black hole is ultramassive to study the evolution of the remnant and the black hole dynamics in this extreme regime. We find that the merger remnant is axisymmetric near the center, while near the large SMBH influence radius, the galaxy is triaxial. The SMBH separation shrinks rapidly due to dynamical friction, and quickly forms a binary black hole; if we scale our model to the most massive estimate for the NGC1277 black hole, for example, the timescale for the SMBH separation to shrink from nearly a kiloparsec to less than a parsec is roughly 10 Myr. By the time the SMBHs form a hard binary, gr...

  11. Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

    Science.gov (United States)

    Tsuji, Hidenobu; Imaki, Masaharu; Kotake, Nobuki; Hirai, Akihito; Nakaji, Masaharu; Kameyama, Shumpei

    2017-03-01

    We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5 μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120 pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.

  12. Cosmic censorship inside black holes

    CERN Document Server

    Thorlacius, L

    2006-01-01

    A simple argument is given that a traversable Cauchy horizon inside a black hole is incompatible with unitary black hole evolution. The argument assumes the validity of black hole complementarity and applies to a generic black hole carrying angular momentum and/or charge. In the second part of the paper we review recent work on the semiclassical geometry of two-dimensional charged black holes.

  13. Black holes and beyond

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    Belief in the existence of black holes is the ultimate act of faith for a physicist. First suggested by the English clergyman John Michell in the year 1784, the gravitational pull of a black hole is so strong that nothing - not even light - can escape. Gravity might be the weakest of the fundamental forces but black-hole physics is not for the faint-hearted. Black holes present obvious problems for would-be observers because they cannot, by definition, be seen with conventional telescopes - although before the end of the decade gravitational-wave detectors should be able to study collisions between black holes. Until then astronomers can only infer the existence of a black hole from its gravitational influence on other matter, or from the X-rays emitted by gas and dust as they are dragged into the black hole. However, once this material passes through the 'event horizon' that surrounds the black hole, we will never see it again - not even with X-ray specs. Despite these observational problems, most physicists and astronomers believe that black holes do exist. Small black holes a few kilometres across are thought to form when stars weighing more than about two solar masses collapse under the weight of their own gravity, while supermassive black holes weighing millions of solar masses appear to be present at the centre of most galaxies. Moreover, some brave physicists have proposed ways to make black holes - or at least event horizons - in the laboratory. The basic idea behind these 'artificial black holes' is not to compress a large amount of mass into a small volume, but to reduce the speed of light in a moving medium to less than the speed of the medium and so create an event horizon. The parallels with real black holes are not exact but the experiments could shed new light on a variety of phenomena. The first challenge, however, is to get money for the research. One year on from a high-profile meeting on artificial black holes in London, for

  14. Investigating stellar-mass black hole kicks

    CERN Document Server

    Repetto, Serena; Sigurdsson, Steinn

    2012-01-01

    We investigate whether stellar-mass black holes have to receive natal kicks in order to explain the observed distribution of low-mass X-ray binaries containing black holes within our Galaxy. Such binaries are the product of binary evolution, where the massive primary has exploded forming a stellar-mass black hole, probably after a common envelope phase where the system contracted down to separations of order 10-30 Rsun. We perform population synthesis calculations of these binaries, applying both kicks due to supernova mass-loss and natal kicks to the newly-formed black hole. We then integrate the trajectories of the binary systems within the Galactic potential. We find that natal kicks are in fact necessary to reach the large distances above the Galactic plane achieved by some binaries. Further, we find that the distribution of natal kicks would seem to be similar to that of neutron stars, rather than one where the kick velocities are reduced by the ratio of black hole to neutron-star mass (i.e. where the ki...

  15. Hamiltonian formalism for Perturbed Black Hole Spacetimes

    Science.gov (United States)

    Mihaylov, Deyan; Gair, Jonathan

    2017-01-01

    Present and future gravitational wave observations provide a new mechanism to probe the predictions of general relativity. Observations of extreme mass ratio inspirals with millihertz gravitational wave detectors such as LISA will provide exquisite constraints on the spacetime structure outside astrophysical black holes, enabling tests of the no-hair property that all general relativistic black holes are described by the Kerr metric. Previous work to understand what constraints LISA observations will be able to place has focussed on specific alternative theories of gravity, or generic deviations that preserve geodesic separability. We describe an alternative approach to this problem--a technique that employs canonical perturbations of the Hamiltonian function describing motion in the Kerr metric. We derive this new approach and demonstrate its application to the cases of a slowly rotating Kerr black hole which is viewed as a perturbation of a Schwarzschild black hole, of coupled perturbations of black holes in the second-order Chern-Simons modified gravity theory, and several more indicative scenarios. Deyan Mihaylov is funded by STFC.

  16. Formation of the Black Holes in the Highest Redshift Quasars

    CERN Document Server

    Yoo, J

    2004-01-01

    The recent discovery of luminous quasars up to a redshift z=6.43 has renewed interest into the formation of black holes massive enough to power the quasars. If black holes grow by Eddington-limited gas accretion with a radiative efficiency of at least 10%, the time required to grow from a stellar black hole to ~10^9 Msun is ~10^9 years, close to the age of the universe at z=6. Black hole mergers may accelerate the rate of mass growth, but can also completely eject black holes from halo centers owing to the gravitational wave recoil effect. Recently, Haiman concluded that black hole ejections likely do not allow black holes to grow to ~10^9 Msun by z=6.43. We reexamine this problem and show that, by using a different relation between halo velocity dispersion and escape velocity, and taking into account the dependence of the gravitational wave recoil velocity on the mass ratio of the merging black holes and spins, black hole masses could reach ~10^9 Msun as early as z=9 starting from stellar seeds without super...

  17. Standard methods for filled hole tension testing of textile composites

    Science.gov (United States)

    Portanova, M. A.; Masters, J. E.

    1995-01-01

    The effects of two test specimen geometry parameters, the specimen width and W/D ratio, on filled-hole tensile strength were determined for textile composite materials. Test data generated by Boeing and Lockheed on 2-D and 3-D braids, and 3-D weaves were used to make these evaluations. The investigation indicated that filled-hole tensile-strength showed little sensitivity to either parameter. Test specimen configurations used in open-hole tension tests, such as those suggested by ASTM D5766 - Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates or those proposed by MIL-HDBK-17-lD should provide adequate results for material comparisons studies. Comparisons of the materials' open-hole and filled-hole tensile strengths indicated that the latter were generally lower than the former. The 3-D braids were the exception; their filled-hole strengths were unexpected larger than their open-hole strengths. However, these increases were small compared to the scatter in the data. Thus, filled hole tension may be a critical design consideration for textile composite materials.

  18. Charged Galileon black holes

    CERN Document Server

    Babichev, Eugeny; Hassaine, Mokhtar

    2015-01-01

    We consider an Abelian gauge field coupled to a particular truncation of Horndeski theory. The Galileon field has translation symmetry and couples non minimally both to the metric and the gauge field. When the gauge-scalar coupling is zero the gauge field reduces to a standard Maxwell field. By taking into account the symmetries of the action, we construct charged black hole solutions. Allowing the scalar field to softly break symmetries of spacetime we construct black holes where the scalar field is regular on the black hole event horizon. Some of these solutions can be interpreted as the equivalent of Reissner-Nordstrom black holes of scalar tensor theories with a non trivial scalar field. A self tuning black hole solution found previously is extended to the presence of dyonic charge without affecting whatsoever the self tuning of a large positive cosmological constant. Finally, for a general shift invariant scalar tensor theory we demonstrate that the scalar field Ansatz and method we employ are mathematic...

  19. Merging Black Holes

    Science.gov (United States)

    Centrella, Joan

    2009-05-01

    The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. And, when the black holes merge in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics.

  20. Black Holes and Beyond

    CERN Document Server

    Mathur, Samir D

    2012-01-01

    The black hole information paradox forces us into a strange situation: we must find a way to break the semiclassical approximation in a domain where no quantum gravity effects would normally be expected. Traditional quantizations of gravity do not exhibit any such breakdown, and this forces us into a difficult corner: either we must give up quantum mechanics or we must accept the existence of troublesome `remnants'. In string theory, however, the fundamental quanta are extended objects, and it turns out that the bound states of such objects acquire a size that grows with the number of quanta in the bound state. The interior of the black hole gets completely altered to a `fuzzball' structure, and information is able to escape in radiation from the hole. The semiclassical approximation can break at macroscopic scales due to the large entropy of the hole: the measure in the path integral competes with the classical action, instead of giving a subleading correction. Putting this picture of black hole microstates ...

  1. Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

    NARCIS (Netherlands)

    Kruyt, J.W.; Heijst, Van G.F.; Altshuler, D.L.; Lentink, David

    2015-01-01

    Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle o

  2. Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

    NARCIS (Netherlands)

    Kruyt, J.W.; Heijst, Van G.F.; Altshuler, D.L.; Lentink, David

    2015-01-01

    Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle o

  3. Black hole entropy quantization

    CERN Document Server

    Corichi, A; Fernandez-Borja, E; Corichi, Alejandro; Diaz-Polo, Jacobo; Fernandez-Borja, Enrique

    2006-01-01

    Ever since the pioneer works of Bekenstein and Hawking, black hole entropy has been known to have a quantum origin. Furthermore, it has long been argued by Bekenstein that entropy should be quantized in discrete (equidistant) steps given its identification with horizon area in (semi-)classical general relativity and the properties of area as an adiabatic invariant. This lead to the suggestion that black hole area should also be quantized in equidistant steps to account for the discrete black hole entropy. Here we shall show that loop quantum gravity, in which area is not quantized in equidistant steps can nevertheless be consistent with Bekenstein's equidistant entropy proposal in a subtle way. For that we perform a detailed analysis of the number of microstates compatible with a given area and show that an observed oscillatory behavior in the entropy-area relation, when properly interpreted yields an entropy that has discrete, equidistant values that are consistent with the Bekenstein framework.

  4. Black hole gravitohydromagnetics

    CERN Document Server

    Punsly, Brian

    2008-01-01

    Black hole gravitohydromagnetics (GHM) is developed from the rudiments to the frontiers of research in this book. GHM describes plasma interactions that combine the effects of gravity and a strong magnetic field, in the vicinity (ergosphere) of a rapidly rotating black hole. This topic was created in response to the astrophysical quest to understand the central engines of radio loud extragalactic radio sources. The theory describes a "torsional tug of war" between rotating ergospheric plasma and the distant asymptotic plasma that extracts the rotational inertia of the black hole. The recoil from the struggle between electromagnetic and gravitational forces near the event horizon is manifested as a powerful pair of magnetized particle beams (jets) that are ejected at nearly the speed of light. These bipolar jets feed large-scale magnetized plasmoids on scales as large as millions of light years (the radio lobes of extragalactic radio sources). This interaction can initiate jets that transport energy fluxes exc...

  5. Turbulent black holes.

    Science.gov (United States)

    Yang, Huan; Zimmerman, Aaron; Lehner, Luis

    2015-02-27

    We demonstrate that rapidly spinning black holes can display a new type of nonlinear parametric instability-which is triggered above a certain perturbation amplitude threshold-akin to the onset of turbulence, with possibly observable consequences. This instability transfers from higher temporal and azimuthal spatial frequencies to lower frequencies-a phenomenon reminiscent of the inverse cascade displayed by (2+1)-dimensional fluids. Our finding provides evidence for the onset of transitory turbulence in astrophysical black holes and predicts observable signatures in black hole binaries with high spins. Furthermore, it gives a gravitational description of this behavior which, through the fluid-gravity duality, can potentially shed new light on the remarkable phenomena of turbulence in fluids.

  6. Merging Black Holes

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    The final merger of two black holes is expected to be the strongest source of gravitational waves for both ground-based detectors such as LIGO and VIRGO, as well as future. space-based detectors. Since the merger takes place in the regime of strong dynamical gravity, computing the resulting gravitational waveforms requires solving the full Einstein equations of general relativity on a computer. For many years, numerical codes designed to simulate black hole mergers were plagued by a host of instabilities. However, recent breakthroughs have conquered these instabilities and opened up this field dramatically. This talk will focus on.the resulting 'gold rush' of new results that is revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, testing general relativity, and astrophysics

  7. Janus black holes

    Science.gov (United States)

    Bak, Dongsu; Gutperle, Michael; Janik, Romuald A.

    2011-10-01

    In this paper Janus black holes in A dS 3 are considered. These are static solutions of an Einstein-scalar system with broken translation symmetry along the horizon. These solutions are dual to interface conformal field theories at finite temperature. An approximate solution is first constructed using perturbation theory around a planar BTZ blackhole. Numerical and exact solutions valid for all sets of parameters are then found and compared. Using the exact solution the thermodynamics of the system is analyzed. The entropy associated with the Janus black hole is calculated and it is found that the entropy of the black Janus is the sum of the undeformed black hole entropy and the entanglement entropy associated with the defect.

  8. Black Hole Induced Ejections

    CERN Document Server

    Pelletier, G

    2004-01-01

    Black Holes generate a particular kind of environments dominated by an accretion flow which concentrates a magnetic field. The interplay of gravity and magnetism creates this paradoxical situation where relativistic ejection is allowed and consequently high energy phenomena take place. Therefore Black Holes, which are very likely at the origin of powerfull astrophysical phenomena such as AGNs, micro- quasars and GRBs where relativistic ejections are observed, are at the heart of high energy astrophysics. The combination of General Relativity and Magneto-HydroDynamics (MHD) makes theory difficult; however great pionneers opened beautiful tracks in the seventies and left important problems to be solved for the next decades. These lectures will present the status of these issues. They have a tutorial aspect together with critical review aspect and contain also some new issues. Most of these lectures has been presented at the "School on Black Hole in the Universe" at Cargese, in May 2003.

  9. Black hole accretion discs

    CERN Document Server

    Lasota, Jean-Pierre

    2015-01-01

    This is an introduction to models of accretion discs around black holes. After a presentation of the non-relativistic equations describing the structure and evolution of geometrically thin accretion discs we discuss their steady-state solutions and compare them to observation. Next we describe in detail the thermal-viscous disc instability model and its application to dwarf novae for which it was designed and its X-ray irradiated-disc version which explains the soft X--ray transients, i.e. outbursting black-hole low-mass X-ray binaries. We then turn to the role of advection in accretion flow onto black holes illustrating its action and importance with a toy model describing both ADAFs and slim discs. We conclude with a presentation of the general-relativistic formalism describing accretion discs in the Kerr space-time.

  10. State-space Manifold and Rotating Black Holes

    CERN Document Server

    Bellucci, Stefano

    2010-01-01

    We study a class of fluctuating higher dimensional black hole configurations obtained in string theory/ $M$-theory compactifications. We explore the intrinsic Riemannian geometric nature of Gaussian fluctuations arising from the Hessian of the coarse graining entropy, defined over an ensemble of brane microstates. It has been shown that the state-space geometry spanned by the set of invariant parameters is non-degenerate, regular and has a negative scalar curvature for the rotating Myers-Perry black holes, Kaluza-Klein black holes, supersymmetric $AdS_5$ black holes, $D_1$-$D_5$ configurations and the associated BMPV black holes. Interestingly, these solutions demonstrate that the principal components of the state-space metric tensor admit a positive definite form, while the off diagonal components do not. Furthermore, the ratio of diagonal components weakens relatively faster than the off diagonal components, and thus they swiftly come into an equilibrium statistical configuration. Novel aspects of the scali...

  11. Growth of Primordial Black Holes

    Science.gov (United States)

    Harada, Tomohiro

    Primordial black holes have important observational implications through Hawking evaporation and gravitational radiation as well as being a candidate for cold dark matter. Those black holes are assumed to have formed in the early universe typically with the mass scale contained within the Hubble horizon at the formation epoch and subsequently accreted mass surrounding them. Numerical relativity simulation shows that primordial black holes of different masses do not accrete much, which contrasts with a simplistic Newtonian argument. We see that primordial black holes larger than the 'super-horizon' primordial black holes have decreasing energy and worm-hole like struture, suggesting the formation through quamtum processes.

  12. Over spinning a black hole?

    Energy Technology Data Exchange (ETDEWEB)

    Bouhmadi-Lopez, Mariam; Cardoso, Vitor; Nerozzi, Andrea; Rocha, Jorge V, E-mail: mariam.bouhmadi@ist.utl.pt, E-mail: vitor.cardoso@ist.utl.pt, E-mail: andrea.nerozzi@ist.utl.pt, E-mail: jorge.v.rocha@ist.utl.pt [CENTRA, Department de Fisica, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049 Lisboa (Portugal)

    2011-09-22

    A possible process to destroy a black hole consists on throwing point particles with sufficiently large angular momentum into the black hole. In the case of Kerr black holes, it was shown by Wald that particles with dangerously large angular momentum are simply not captured by the hole, and thus the event horizon is not destroyed. Here we reconsider this gedanken experiment for black holes in higher dimensions. We show that this particular way of destroying a black hole does not succeed and that Cosmic Censorship is preserved.

  13. Superfluid Black Holes

    CERN Document Server

    Hennigar, Robie A; Tjoa, Erickson

    2016-01-01

    We present what we believe is the first example of a "$\\lambda$-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid $^4$He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically AdS hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.

  14. Correlated Multiphoton Holes

    CERN Document Server

    Afek, Itai; Silberberg, Yaron

    2010-01-01

    We generate bipartite states of light which exhibit an absence of multiphoton coincidence events between two modes amid a constant background flux. These `correlated photon holes' are produced by mixing a coherent state and relatively weak spontaneous parametric down-conversion using a balanced beamsplitter. Correlated holes with arbitrarily high photon numbers may be obtained by adjusting the relative phase and amplitude of the inputs. We measure states of up to five photons and verify their nonclassicality. The scheme provides a route for observation of high-photon-number nonclassical correlations without requiring intense quantum resources.

  15. Are Black Holes Springy?

    OpenAIRE

    Good, Michael R. R.; Ong, Yen Chin

    2014-01-01

    A $(3+1)$-dimensional asymptotically flat Kerr black hole angular speed $\\Omega_+$ can be used to define an effective spring constant, $k=m\\Omega_+^2$. Its maximum value is the Schwarzschild surface gravity, $k = \\kappa $, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\\pi T = \\kappa - k$. Hooke's law, in the extremal limit, provides the force $F = 1/4$, which is consistent with the conj...

  16. Are Black Holes Springy?

    CERN Document Server

    Good, Michael R R

    2014-01-01

    A $(3+1)$-dimensional asymptotically flat Kerr black hole angular speed $\\Omega_+$ can be used to define an effective spring constant, $k=m\\Omega_+^2$. Its maximum value is the Schwarzschild surface gravity, $k = \\kappa $, which rapidly weakens as the black hole spins down and the temperature increases. The Hawking temperature is expressed in terms of the spring constant: $2\\pi T = \\kappa - k$. Hooke's law, in the extremal limit, provides the force $F = 1/4$, which is consistent with the conjecture of maximum force in general relativity.

  17. Characterizing Black Hole Mergers

    Science.gov (United States)

    Baker, John; Boggs, William Darian; Kelly, Bernard

    2010-01-01

    Binary black hole mergers are a promising source of gravitational waves for interferometric gravitational wave detectors. Recent advances in numerical relativity have revealed the predictions of General Relativity for the strong burst of radiation generated in the final moments of binary coalescence. We explore features in the merger radiation which characterize the final moments of merger and ringdown. Interpreting the waveforms in terms of an rotating implicit radiation source allows a unified phenomenological description of the system from inspiral through ringdown. Common features in the waveforms allow quantitative description of the merger signal which may provide insights for observations large-mass black hole binaries.

  18. Magnonic Black Holes.

    Science.gov (United States)

    Roldán-Molina, A; Nunez, Alvaro S; Duine, R A

    2017-02-10

    We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons-the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

  19. Superfluid Black Holes.

    Science.gov (United States)

    Hennigar, Robie A; Mann, Robert B; Tjoa, Erickson

    2017-01-13

    We present what we believe is the first example of a "λ-line" phase transition in black hole thermodynamics. This is a line of (continuous) second order phase transitions which in the case of liquid ^{4}He marks the onset of superfluidity. The phase transition occurs for a class of asymptotically anti-de Sitter hairy black holes in Lovelock gravity where a real scalar field is conformally coupled to gravity. We discuss the origin of this phase transition and outline the circumstances under which it (or generalizations of it) could occur.

  20. Horndeski black hole geodesics

    CERN Document Server

    Tretyakova, D A

    2016-01-01

    We examine geodesics for the scalar-tensor black holes in the Horndeski-Galileon framework. Our analysis shows that first kind relativistic orbits may not be present within some model parameters range. This is a highly pathological behavior contradicting to the black hole accretion and Solar System observations. We also present a new (although very similar to those previously known) solution, which contains the orbits we expect from a compact object, admits regular scalar field at the horizon and and can fit into the known stability criteria.

  1. Magnonic Black Holes

    Science.gov (United States)

    Roldán-Molina, A.; Nunez, Alvaro S.; Duine, R. A.

    2017-02-01

    We show that the interaction between the spin-polarized current and the magnetization dynamics can be used to implement black-hole and white-hole horizons for magnons—the quanta of oscillations in the magnetization direction in magnets. We consider three different systems: easy-plane ferromagnetic metals, isotropic antiferromagnetic metals, and easy-plane magnetic insulators. Based on available experimental data, we estimate that the Hawking temperature can be as large as 1 K. We comment on the implications of magnonic horizons for spin-wave scattering and transport experiments, and for magnon entanglement.

  2. Modeling black hole evaporation

    CERN Document Server

    Fabbri, Alessandro

    2005-01-01

    The scope of this book is two-fold: the first part gives a fully detailed and pedagogical presentation of the Hawking effect and its physical implications, and the second discusses the backreaction problem, especially in connection with exactly solvable semiclassical models that describe analytically the black hole evaporation process. The book aims to establish a link between the general relativistic viewpoint on black hole evaporation and the new CFT-type approaches to the subject. The detailed discussion on backreaction effects is also extremely valuable.

  3. Acoustic black holes

    CERN Document Server

    Visser, M

    1999-01-01

    Acoustic propagation in a moving fluid provides a conceptually clean and powerful analogy for understanding black hole physics. As a teaching tool, the analogy is useful for introducing students to both General Relativity and fluid mechanics. As a research tool, the analogy helps clarify what aspects of the physics are kinematics and what aspects are dynamics. In particular, Hawking radiation is a purely kinematical effect, whereas black hole entropy is intrinsically dynamical. Finally, I discuss the fact that with present technology acoustic Hawking radiation is almost experimentally testable.

  4. Woodwind Tone Hole Acoustics and the Spectrum Transformation Function.

    Science.gov (United States)

    Keefe, Douglas Howard

    negative inertances whose values depend on the tone hole proportions. An open hole at a pressure node can radiate as a dipole when (b/a) is large and (t/2b) is small. Dissipative losses vary significantly with the frequency of oscillation and the tone hole geometry. Lowering the pad height above a tone hole increases the dissipation. Acoustical streaming through holes is very important for t << 2b, and the associated nonlinear dissipation can destroy the oscillation on poorly designed woodwinds. This unexpected phenomenon is critical in the playing behavior of some flutes, clarinets, and other woodwinds. The onset of streaming occurs at all dynamical levels and more easily for instruments whose spectra are in a 1:3:5 frequency ratio, rather than a 1:2:3 ratio. The streaming is most important for low register tones for which the usual dissipation is also the largest relative to the radiative dissipation, due to losses at the sharp edges inside the bore near the tone holes. Mutual interactions between holes separated by a distance 2s are most pronounced for large diameter holes (2b/2s not small). Holes interact externally via radiation, and internally via higher-order evanescent modes excited at the intersection of the main bore with each tone hole. The non-radiative dissipation increases, and the air column resonances are slightly shifted due to the presence of these interactions. Applications are discussed and numerous additional experiments are proposed which are relevant to woodwinds and their design, and the perception of listeners in rooms.

  5. Electron hole tracking PIC simulation

    Science.gov (United States)

    Zhou, Chuteng; Hutchinson, Ian

    2016-10-01

    An electron hole is a coherent BGK mode solitary wave. Electron holes are observed to travel at high velocities relative to bulk plasmas. The kinematics of a 1-D electron hole is studied using a novel Particle-In-Cell simulation code with fully kinetic ions. A hole tracking technique enables us to follow the trajectory of a fast-moving solitary hole and study quantitatively hole acceleration and coupling to ions. The electron hole signal is detected and the simulation domain moves by a carefully designed feedback control law to follow its propagation. This approach has the advantage that the length of the simulation domain can be significantly reduced to several times the hole width, which makes high resolution simulations tractable. We observe a transient at the initial stage of hole formation when the hole accelerates to several times the cold-ion sound speed. Artificially imposing slow ion speed changes on a fully formed hole causes its velocity to change even when the ion stream speed in the hole frame greatly exceeds the ion thermal speed, so there are no reflected ions. The behavior that we observe in numerical simulations agrees very well with our analytic theory of hole momentum conservation and energization effects we call ``jetting''. The work was partially supported by the NSF/DOE Basic Plasma Science Partnership under Grant DE-SC0010491. Computer simulations were carried out on the MIT PSFC parallel AMD Opteron/Infiniband cluster Loki.

  6. Is black-hole ringdown a memory of its progenitor?

    Science.gov (United States)

    Kamaretsos, Ioannis; Hannam, Mark; Sathyaprakash, B S

    2012-10-05

    We perform an extensive numerical study of coalescing black-hole binaries to understand the gravitational-wave spectrum of quasinormal modes excited in the merged black hole. Remarkably, we find that the masses and spins of the progenitor are clearly encoded in the mode spectrum of the ringdown signal. Some of the mode amplitudes carry the signature of the binary's mass ratio, while others depend critically on the spins. Simulations of precessing binaries suggest that our results carry over to generic systems. Using Bayesian inference, we demonstrate that it is possible to accurately measure the mass ratio and a proper combination of spins even when the binary is itself invisible to a detector. Using a mapping of the binary masses and spins to the final black-hole spin allows us to further extract the spin components of the progenitor. Our results could have tremendous implications for gravitational astronomy by facilitating novel tests of general relativity using merging black holes.

  7. Rotating regular black holes

    CERN Document Server

    Bambi, Cosimo

    2013-01-01

    The formation of spacetime singularities is a quite common phenomenon in General Relativity and it is regulated by specific theorems. It is widely believed that spacetime singularities do not exist in Nature, but that they represent a limitation of the classical theory. While we do not yet have any solid theory of quantum gravity, toy models of black hole solutions without singularities have been proposed. So far, there are only non-rotating regular black holes in the literature. These metrics can be hardly tested by astrophysical observations, as the black hole spin plays a fundamental role in any astrophysical process. In this letter, we apply the Newman-Janis algorithm to the Hayward and to the Bardeen black hole metrics. In both cases, we obtain a family of rotating solutions. Every solution corresponds to a different matter configuration. Each family has one solution with special properties, which can be written in Kerr-like form in Boyer-Lindquist coordinates. These special solutions are of Petrov type ...

  8. Rotating black hole hair

    CERN Document Server

    Gregory, Ruth; Wills, Danielle

    2013-01-01

    A Kerr black hole sporting cosmic string hair is studied in the context of the abelian Higgs model vortex. It is shown that a such a system displays much richer phenomenology than its static Schwarzschild or Reissner--Nordstrom cousins, for example, the rotation generates a near horizon `electric' field. In the case of an extremal rotating black hole, two phases of the Higgs hair are possible: Large black holes exhibit standard hair, with the vortex piercing the event horizon. Small black holes on the other hand, exhibit a flux-expelled solution, with the gauge and scalar field remaining identically in their false vacuum state on the event horizon. This solution however is extremely sensitive to confirm numerically, and we conjecture that it is unstable due to a supperradiant mechanism similar to the Kerr-adS instability. Finally, we compute the gravitational back reaction of the vortex, which turns out to be far more nuanced than a simple conical deficit. While the string produces a conical effect, it is con...

  9. Moulting Black Holes

    Science.gov (United States)

    Bena, Iosif; Chowdhury, Borun D.; de Boer, Jan; El-Showk, Sheer; Shigemori, Masaki

    2012-03-01

    We find a family of novel supersymmetric phases of the D1-D5 CFT, which in certain ranges of charges have more entropy than all known ensembles. We also find bulk BPS configurations that exist in the same range of parameters as these phases, and have more entropy than a BMPV black hole; they can be thought of as coming from a BMPV black hole shedding a "hair" condensate outside of the horizon. The entropy of the bulk configurations is smaller than that of the CFT phases, which indicates that some of the CFT states are lifted at strong coupling. Neither the bulk nor the boundary phases are captured by the elliptic genus, which makes the coincidence of the phase boundaries particularly remarkable. Our configurations are supersymmetric, have non-Cardy-like entropy, and are the first instance of a black hole entropy enigma with a controlled CFT dual. Furthermore, contrary to common lore, these objects exist in a region of parameter space (between the "cosmic censorship bound" and the "unitarity bound") where no black holes were thought to exist.

  10. Twistors and Black Holes

    NARCIS (Netherlands)

    Neitzke, A.; Pioline, B.; Vandoren, S.

    2007-01-01

    Motivated by black hole physics in N = 2,D = 4 supergravity, we study the geometry of quaternionic-K¨ahler manifolds Mobtained by the c-map construction from projective special Kähler manifolds Ms. Improving on earlier treatments, we compute the Käahler potentials on the twistor space Z and Swann sp

  11. Rotating regular black holes

    Energy Technology Data Exchange (ETDEWEB)

    Bambi, Cosimo, E-mail: bambi@fudan.edu.cn; Modesto, Leonardo, E-mail: lmodesto@fudan.edu.cn

    2013-04-25

    The formation of spacetime singularities is a quite common phenomenon in General Relativity and it is regulated by specific theorems. It is widely believed that spacetime singularities do not exist in Nature, but that they represent a limitation of the classical theory. While we do not yet have any solid theory of quantum gravity, toy models of black hole solutions without singularities have been proposed. So far, there are only non-rotating regular black holes in the literature. These metrics can be hardly tested by astrophysical observations, as the black hole spin plays a fundamental role in any astrophysical process. In this Letter, we apply the Newman–Janis algorithm to the Hayward and to the Bardeen black hole metrics. In both cases, we obtain a family of rotating solutions. Every solution corresponds to a different matter configuration. Each family has one solution with special properties, which can be written in Kerr-like form in Boyer–Lindquist coordinates. These special solutions are of Petrov type D, they are singularity free, but they violate the weak energy condition for a non-vanishing spin and their curvature invariants have different values at r=0 depending on the way one approaches the origin. We propose a natural prescription to have rotating solutions with a minimal violation of the weak energy condition and without the questionable property of the curvature invariants at the origin.

  12. When Black Holes Collide

    Science.gov (United States)

    Baker, John

    2010-01-01

    Among the fascinating phenomena predicted by General Relativity, Einstein's theory of gravity, black holes and gravitational waves, are particularly important in astronomy. Though once viewed as a mathematical oddity, black holes are now recognized as the central engines of many of astronomy's most energetic cataclysms. Gravitational waves, though weakly interacting with ordinary matter, may be observed with new gravitational wave telescopes, opening a new window to the universe. These observations promise a direct view of the strong gravitational dynamics involving dense, often dark objects, such as black holes. The most powerful of these events may be merger of two colliding black holes. Though dark, these mergers may briefly release more energy that all the stars in the visible universe, in gravitational waves. General relativity makes precise predictions for the gravitational-wave signatures of these events, predictions which we can now calculate with the aid of supercomputer simulations. These results provide a foundation for interpreting expect observations in the emerging field of gravitational wave astronomy.

  13. Nonsingular black hole

    Energy Technology Data Exchange (ETDEWEB)

    Chamseddine, Ali H. [American University of Beirut, Physics Department, Beirut (Lebanon); I.H.E.S., Bures-sur-Yvette (France); Mukhanov, Viatcheslav [Niels Bohr Institute, Niels Bohr International Academy, Copenhagen (Denmark); Ludwig-Maximilians University, Theoretical Physics, Munich (Germany); MPI for Physics, Munich (Germany)

    2017-03-15

    We consider the Schwarzschild black hole and show how, in a theory with limiting curvature, the physical singularity ''inside it'' is removed. The resulting spacetime is geodesically complete. The internal structure of this nonsingular black hole is analogous to Russian nesting dolls. Namely, after falling into the black hole of radius r{sub g}, an observer, instead of being destroyed at the singularity, gets for a short time into the region with limiting curvature. After that he re-emerges in the near horizon region of a spacetime described by the Schwarzschild metric of a gravitational radius proportional to r{sub g}{sup 1/3}. In the next cycle, after passing the limiting curvature, the observer finds himself within a black hole of even smaller radius proportional to r{sub g}{sup 1/9}, and so on. Finally after a few cycles he will end up in the spacetime where he remains forever at limiting curvature. (orig.)

  14. "Holes": Folklore Redux.

    Science.gov (United States)

    Mascia, Elizabeth G.

    2001-01-01

    Demonstrates that a careful reading of the book for young adults, "Holes" by Louis Sachar, reveals how this contemporary story is grounded in folklore, and that it is this debt to folk literature that allows readers to accept an improbable plot. Shows how the story weaves together elements from traditional folk literature and stretches them across…

  15. Laser bottom hole assembly

    Science.gov (United States)

    Underwood, Lance D; Norton, Ryan J; McKay, Ryan P; Mesnard, David R; Fraze, Jason D; Zediker, Mark S; Faircloth, Brian O

    2014-01-14

    There is provided for laser bottom hole assembly for providing a high power laser beam having greater than 5 kW of power for a laser mechanical drilling process to advance a borehole. This assembly utilizes a reverse Moineau motor type power section and provides a self-regulating system that addresses fluid flows relating to motive force, cooling and removal of cuttings.

  16. Convenient contrast enhancement by a hole-free phase plate

    DEFF Research Database (Denmark)

    Malac, Marek; Beleggia, Marco; Kawasaki, Masahiro

    2012-01-01

    Decrease of the irradiation dose needed to obtain a desired signal-to-noise ratio can be achieved by Zernike phase-plate imaging. Here we present results on a hole-free phase plate (HFPP) design that uses the incident electron beam to define the center of the plate, thereby eliminating the need...... for high precision alignment and with advantages in terms of ease of fabrication. The Zernike-like phase shift is provided by a charge distribution induced by the primary beam, rather than by a hole in the film. Compared to bright-field Fresnel-mode imaging, the hole-free phase plate (HFPP) results in two...

  17. Quantum aspects of black holes

    CERN Document Server

    2015-01-01

    Beginning with an overview of the theory of black holes by the editor, this book presents a collection of ten chapters by leading physicists dealing with the variety of quantum mechanical and quantum gravitational effects pertinent to black holes. The contributions address topics such as Hawking radiation, the thermodynamics of black holes, the information paradox and firewalls, Monsters, primordial black holes, self-gravitating Bose-Einstein condensates, the formation of small black holes in high energetic collisions of particles, minimal length effects in black holes and small black holes at the Large Hadron Collider. Viewed as a whole the collection provides stimulating reading for researchers and graduate students seeking a summary of the quantum features of black holes.

  18. Towards Noncommutative Quantum Black Holes

    CERN Document Server

    Lopez-Dominguez, J C; Ramírez, C; Sabido, M

    2006-01-01

    In this paper we study noncommutative black holes. We use a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Trough the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular we calculate the Hawking's temperature and entropy for the Noncommutative Schwarzschild black hole.

  19. Black Hole: The Interior Spacetime

    CERN Document Server

    Ong, Yen Chin

    2016-01-01

    The information loss paradox is often discussed from the perspective of the observers who stay outside of a black hole. However, the interior spacetime of a black hole can be rather nontrivial. We discuss the open problems regarding the volume of a black hole, and whether it plays any role in information storage. We also emphasize the importance of resolving the black hole singularity, if one were to resolve the information loss paradox.

  20. Simulations of coalescing black holes

    CERN Document Server

    Janiuk, Agnieszka

    2016-01-01

    We describe the methods and results of numerical simulations of coalescing black holes. The simulation in dynamical spacetime covers the inspiral, merger, and ringdown phases. We analyze the emission of gravitational waves and properties of a black hole being the merger product. We discuss the results in the context of astrophysical environment of black holes that exist in the Universe.

  1. "Exotic" black holes with torsion

    OpenAIRE

    2013-01-01

    In the context of three-dimensional gravity with torsion, the concepts of standard and "exotic" Banados-Teitelboim-Zanelli black holes are generalized by going over to black holes with torsion. This approach provides a unified insight into thermodynamics of black holes, with or without torsion.

  2. Experimental investigation of key parameters pertinent to multi-hole orifice throttling characteristic

    Institute of Scientific and Technical Information of China (English)

    ZHAO Tian-yi; ZHANG Ji-li

    2008-01-01

    This study firstly defines a set of arrangement rule for perforated holes of multi-hole orifice (MO), and then presents three critical geometrical parameters including total number of performated hole, equivalent diameter ratio and distribution density of perforated holes, which are to quantify MO structure. This paper built the throttling test apparatus for nice test MO plates, which were designed according to orthogonal theory. The experiments were conducted to investigate the effect of three critical geometerical parameters on the pressure loss coefficient of test MOs. Results show that equivalent diameter ratio is the dominant prameter affecting MO throttling characterstic.

  3. Optical black hole lasers

    CERN Document Server

    Faccio, Daniele; Lamperti, Marco; Leonhardt, Ulf

    2012-01-01

    Using numerical simulations we show how to realise an optical black hole laser, i.e. an amplifier formed by travelling refractive index perturbations arranged so as to trap light between a white and a black hole horizon. The simulations highlight the main features of these lasers: the growth inside the cavity of positive and negative frequency modes accompanied by a weaker emission of modes that occurs in periodic bursts corresponding to the cavity round trips of the trapped modes. We then highlight a new regime in which the trapped mode spectra broaden until the zero-frequency points on the dispersion curve are reached. Amplification at the horizon is highest for zero-frequencies, therefore leading to a strong modification of the structure of the trapped light. For sufficiently long propagation times, lasing ensues only at the zero-frequency modes.

  4. Presentism meets black holes

    CERN Document Server

    Romero, Gustavo E

    2014-01-01

    Presentism is, roughly, the metaphysical doctrine that maintains that whatever exists, exists in the present. The compatibility of presentism with the theories of special and general relativity was much debated in recent years. It has been argued that at least some versions of presentism are consistent with time-orientable models of general relativity. In this paper we confront the thesis of presentism with relativistic physics, in the strong gravitational limit where black holes are formed. We conclude that the presentist position is at odds with the existence of black holes and other compact objects in the universe. A revision of the thesis is necessary, if it is intended to be consistent with the current scientific view of the universe.

  5. Photon Black Holes

    CERN Document Server

    Hernández, X; Mendoza, S; Sussman, R A

    2005-01-01

    We study the relationship between the energy and entropy of a black body photon gas, within an idealised spherical adiabatic enclosure of radius R, as this is compressed into a self-gravitating regime. We show that this regime approximately coincides with the black hole regime for the system, i.e., R ~ R_{s}, where R_{s} denotes the Schwarzschild radius of the system. The entropy of this system is always below the suggested Holographic bound, even as R \\to R_{s}. A plausible quantum configuration for the photon gas at R \\to R_{s} is suggested, which satisfies all energy, entropy and temperature black hole conditions. Finally we examine our results from the point of view of recent Loop Quantum Gravity ideas.

  6. Philosophical Issues of Black Holes

    CERN Document Server

    Romero, Gustavo E

    2014-01-01

    Black holes are extremely relativistic objects. Physical processes around them occur in a regime where the gravitational field is extremely intense. Under such conditions, our representations of space, time, gravity, and thermodynamics are pushed to their limits. In such a situation philosophical issues naturally arise. In this chapter I review some philosophical questions related to black holes. In particular, the relevance of black holes for the metaphysical dispute between presentists and eternalists, the origin of the second law of thermodynamics and its relation to black holes, the problem of information, black holes and hypercomputing, the nature of determinisim, and the breakdown of predictability in black hole space-times. I maintain that black hole physics can be used to illuminate some important problems in the border between science and philosophy, either epistemology and ontology.

  7. Noncommutative Black Holes

    CERN Document Server

    Bastos, C; Dias, N C; Prata, J N

    2010-01-01

    One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity regime and it is shown that the wave function vanishes in this limit.

  8. Artificial ozone holes

    OpenAIRE

    Dolya, S. N.

    2014-01-01

    This article considers an opportunity of disinfecting a part of the Earth surface, occupying a large area of ten thousand square kilometers. The sunlight will cause dissociation of molecular bromine into atoms; each bromine atom kills thirty thousand molecules of ozone. Each bromine plate has a mass of forty milligrams grams and destroys ozone in the area of hundred square meters. Thus, to form the ozone hole over the area of ten thousand square kilometers, it is required to have the total ma...

  9. Linear dilaton black holes

    CERN Document Server

    Clément, G; Leygnac, C; Clement, Gerard; Gal'tsov, Dmitri; Leygnac, Cedric

    2003-01-01

    We present new solutions to Einstein-Maxwell-dilaton-axion (EMDA) gravity in four dimensions describing black holes which asymptote to the linear dilaton background. In the non-rotating case they can be obtained as the limiting geometry of dilaton black holes. The rotating solutions (possibly endowed with a NUT parameter) are constructed using a generating technique based on the Sp(4,R) duality of the EMDA system. In a certain limit (with no event horizon present) our rotating solutions coincide with supersymmetric Israel-Wilson-Perjes type dilaton-axion solutions. In presence of an event horizon supersymmetry is broken. The temperature of the static black holes is constant, and their mass does not depend on it, so the heat capacity is zero. We investigate geodesics and wave propagation in these spacetimes and find superradiance in the rotating case. Because of the non-asymptotically flat nature of the geometry, certain modes are reflected from infinity, in particular, all superradiant modes are confined. Thi...

  10. Moulting Black Holes

    CERN Document Server

    Bena, Iosif; de Boer, Jan; El-Showk, Sheer; Shigemori, Masaki

    2011-01-01

    We find a family of novel supersymmetric phases of the D1-D5 CFT, which in certain ranges of charges have more entropy than all known ensembles. We also find bulk BPS configurations that exist in the same range of parameters as these phases, and have more entropy than a BMPV black hole; they can be thought of as coming from a BMPV black hole shedding a "hair" condensate outside of the horizon. The entropy of the bulk configurations is smaller than that of the CFT phases, which indicates that some of the CFT states are lifted at strong coupling. Neither the bulk nor the boundary phases are captured by the elliptic genus, which makes the coincidence of the phase boundaries particularly remarkable. Our configurations are supersymmetric, have non-Cardy-like entropy, and are the first instance of a black hole entropy enigma with a controlled CFT dual. Furthermore, contrary to common lore, these objects exist in a region of parameter space (between the "cosmic censorship bound" and the "unitarity bound") where no b...

  11. Slowly balding black holes

    CERN Document Server

    Lyutikov, Maxim

    2011-01-01

    The "no hair" theorem, a key result in General Relativity, states that an isolated black hole is defined by only three parameters: mass, angular momentum, and electric charge; this asymptotic state is reached on a light-crossing time scale. We find that the "no hair" theorem is not formally applicable for black holes formed from collapse of a rotating neutron star. Rotating neutron stars can self-produce particles via vacuum breakdown forming a highly conducting plasma magnetosphere such that magnetic field lines are effectively "frozen-in" the star both before and during collapse. In the limit of no resistivity, this introduces a topological constraint which prohibits the magnetic field from sliding off the newly-formed event horizon. As a result, during collapse of a neutron star into a black hole, the latter conserves the number of magnetic flux tubes $N_B = e \\Phi_\\infty /(\\pi c \\hbar)$, where $\\Phi_\\infty \\approx 2 \\pi^2 B_{NS} R_{NS}^3 /(P_{\\rm NS} c)$ is the initial magnetic flux through the hemisphere...

  12. Black hole's quantum levels

    CERN Document Server

    Corda, Christian

    2012-01-01

    By introducing a black hole's effective temperature, which takes into account both of the non-strictly thermal and non-strictly continuous characters of Hawking radiation, we recently re-analyzed black hole's quasi-normal modes and interpreted them naturally in terms of quantum levels for emissions of particles. After a careful review of previous results, in this work we improve such an analysis by removing an approximation that we implicitly used in our previous work and by obtaining the corrected expressions for the formulas of the horizon's area quantization and the number of quanta of area and hence also for Bekenstein-Hawking entropy, its sub-leading corrections and the number of micro-states, i.e. quantities which are fundamental to realize unitary quantum gravity theory, like functions of the quantum overtone number e (emission) and, in turn,of the black hole's quantum excited level. Another approximation concerning the maximum value of e is also corrected. We also consider quasi-normal modes in terms ...

  13. Observational Signatures of Binary Supermassive Black Holes

    CERN Document Server

    Roedig, Constanze; Miller, M Coleman

    2014-01-01

    Observations indicate that most massive galaxies contain a supermassive black hole, and theoretical studies suggest that when such galaxies have a major merger, the central black holes will form a binary and eventually coalesce. Here we discuss two spectral signatures of such binaries that may help distinguish them from ordinary AGN. These signatures are expected when the mass ratio between the holes is not extreme and the system is fed by a circumbinary disk. One such signature is a notch in the thermal continuum that has been predicted by other authors; we point out that it should be accompanied by a spectral revival at shorter wavelengths and also discuss its dependence on binary properties such as mass, mass ratio, and separation. In particular, we note that the wavelength $\\lambda_n$ at which the notch occurs depends on these three parameters in such a way as to make the number of systems displaying these notches $\\propto \\lambda_n^{16/3}$; longer wavelength searches are therefore strongly favored. A sec...

  14. Two stellar-mass black holes in the globular cluster M22.

    Science.gov (United States)

    Strader, Jay; Chomiuk, Laura; Maccarone, Thomas J; Miller-Jones, James C A; Seth, Anil C

    2012-10-04

    Hundreds of stellar-mass black holes probably form in a typical globular star cluster, with all but one predicted to be ejected through dynamical interactions. Some observational support for this idea is provided by the lack of X-ray-emitting binary stars comprising one black hole and one other star ('black-hole/X-ray binaries') in Milky Way globular clusters, even though many neutron-star/X-ray binaries are known. Although a few black holes have been seen in globular clusters around other galaxies, the masses of these cannot be determined, and some may be intermediate-mass black holes that form through exotic mechanisms. Here we report the presence of two flat-spectrum radio sources in the Milky Way globular cluster M22, and we argue that these objects are black holes of stellar mass (each ∼10-20 times more massive than the Sun) that are accreting matter. We find a high ratio of radio-to-X-ray flux for these black holes, consistent with the larger predicted masses of black holes in globular clusters compared to those outside. The identification of two black holes in one cluster shows that ejection of black holes is not as efficient as predicted by most models, and we argue that M22 may contain a total population of ∼5-100 black holes. The large core radius of M22 could arise from heating produced by the black holes.

  15. Black hole evaporation with separated fermions.

    Science.gov (United States)

    Han, Tao; Kribs, Graham D; McElrath, Bob

    2003-01-24

    In models with a low quantum gravity scale, fast proton decay can be avoided by localizing quarks and leptons to separated positions in an extra 1/TeV sized dimension with gauge and Higgs fields living throughout. Black holes with masses of the order of the quantum gravity scale are therefore expected to evaporate nonuniversally, preferentially radiating directly into quarks or leptons but not both. Should black holes be copiously produced at a future hadron collider, we find the ratio of final state jets to charged leptons to photons is 113:8:1, which differs from previous analyses that assumed all standard model fields live at the same point in the extra dimensional space.

  16. Hydrodynamics of R-charged black holes

    CERN Document Server

    Son, D T; Son, Dam T.; Starinets, Andrei O.

    2006-01-01

    We consider hydrodynamics of N=4 supersymmetric SU(N_c) Yang-Mills plasma at a nonzero density of R-charge. In the regime of large N_c and large 't Hooft coupling the gravity dual description involves an asymptotically Anti- de Sitter five-dimensional charged black hole solution of Behrnd, Cvetic and Sabra. We compute the shear viscosity as a function of chemical potentials conjugated to the three U(1) \\subset SO(6)_R charges. The ratio of the shear viscosity to entropy density is independent of the chemical potentials and is equal to 1/4\\pi. For a single charge black hole we also compute the thermal conductivity, and investigate the critical behavior of the transport coefficients near the boundary of thermodynamic stability.

  17. Highly eccentric inspirals into a black hole

    Science.gov (United States)

    Osburn, Thomas; Warburton, Niels; Evans, Charles R.

    2016-03-01

    We model the inspiral of a compact stellar-mass object into a massive nonrotating black hole including all dissipative and conservative first-order-in-the-mass-ratio effects on the orbital motion. The techniques we develop allow inspirals with initial eccentricities as high as e ˜0.8 and initial separations as large as p ˜50 to be evolved through many thousands of orbits up to the onset of the plunge into the black hole. The inspiral is computed using an osculating elements scheme driven by a hybridized self-force model, which combines Lorenz-gauge self-force results with highly accurate flux data from a Regge-Wheeler-Zerilli code. The high accuracy of our hybrid self-force model allows the orbital phase of the inspirals to be tracked to within ˜0.1 radians or better. The difference between self-force models and inspirals computed in the radiative approximation is quantified.

  18. Black Holes with Skyrme Hair

    CERN Document Server

    Shiiki, N; Shiiki, Noriko; Sawado, Nobuyuki

    2005-01-01

    This paper is intended to give a review of the recent developments on black holes with Skyrme hair. The Einstein-Skyrme system is known to possess black hole solutions with Skyrme hair. The spherically symmetric black hole skyrmion with B=1 was the first discovered counter example of the no-hair conjecture for black holes. Recently we found the B=2 axially symmetric black hole skyrmion. In this system, the black hole at the center of the skyrmion absorbs the baryon number partially, leaving fractional charge outside the horizon. Therefore the baryon number is no longer conserved. We examine the B=1, 2 black hole solutions in detail in this paper. The model has a natural extension to the gauged version which can describe monopole black hole skyrmions. Callan and Witten discussed the monopole catalysis of proton decay within the Skyrme model. We apply the idea to the Einstein-Maxwell-Skyrme system and obtain monopole black hole skyrmions. Remarkably there exist multi-black hole skyrmion solutions in which the g...

  19. Prospects for Measuring Supermassive Black Hole Masses with TMT

    Science.gov (United States)

    Do, Tuan; Wright, Shelley A.; Barth, Aaron J.; Barton, Elizabeth J.; Simard, Luc; Larkin, James E.; Moore, Anna M.; Wang, Lianqi; Ellerbroek, Brent

    2014-07-01

    The next generation of giant-segmented mirror telescopes will enable us to observe galactic nuclei at much higher angular resolution and sensitivity than ever before. These capabilities will introduce a revolutionary shift in our understanding of the origin and evolution of supermassive black holes by enabling more precise black hole mass measurements in a mass range that is unreachable today. We present simulations and predictions of the observations of nuclei that will be made with the Thirty Meter Telescope and the adaptive optics assisted integral- field spectrograph IRIS, which is capable of diffraction-limited spectroscopy from Z band (0.9 μm) to K band (2.2 μm). These simulations, for the first time, use realistic values for the sky, telescope, adaptive optics system, and instrument to determine the expected signal-to-noise ratio of a range of possible targets spanning intermediate mass black holes of ˜10^4 M⊙ to the most massive black holes known today of >10^10 M⊙. I will present simulations across a spectrum of black hole masses and galaxy types to show the ability of IRIS and TMT to quantitatively explore the demographics of black holes in the universe. I will discuss how these observations will enable our study of the origin of the MBH - galaxy velocity dispersion and MBH - galaxy luminosity relationships, and the evolution of black holes through cosmic time.

  20. Are Nuclear Star Clusters the Precursors of Massive Black Holes?

    Directory of Open Access Journals (Sweden)

    Nadine Neumayer

    2012-01-01

    Full Text Available We present new upper limits for black hole masses in extremely late type spiral galaxies. We confirm that this class of galaxies has black holes with masses less than 106M⊙, if any. We also derive new upper limits for nuclear star cluster masses in massive galaxies with previously determined black hole masses. We use the newly derived upper limits and a literature compilation to study the low mass end of the global-to-nucleus relations. We find the following. (1 The MBH-σ relation cannot flatten at low masses, but may steepen. (2 The MBH-Mbulge relation may well flatten in contrast. (3 The MBH-Sersic n relation is able to account for the large scatter in black hole masses in low-mass disk galaxies. Outliers in the MBH-Sersic n relation seem to be dwarf elliptical galaxies. When plotting MBH versus MNC we find three different regimes: (a nuclear cluster dominated nuclei, (b a transition region, and (c black hole-dominated nuclei. This is consistent with the picture, in which black holes form inside nuclear clusters with a very low-mass fraction. They subsequently grow much faster than the nuclear cluster, destroying it when the ratio MBH/MNC grows above 100. Nuclear star clusters may thus be the precursors of massive black holes in galaxy nuclei.

  1. Rotating "Black Holes" with Holes in the Horizon

    OpenAIRE

    Burinskii, Alexander; Elizalde, Emilio; Hildebrandt, Sergi R.; Magli, Giulio

    2005-01-01

    Kerr-Schild solutions of the Einstein-Maxwell field equations, containing semi-infinite axial singular lines, are investigated. It is shown that axial singularities break up the black hole, forming holes in the horizon. As a result, a tube-like region appears which allows matter to escape from the interior without crossing the horizon. It is argued that axial singularities of this kind, leading to very narrow beams, can be created in black holes by external electromagnetic or gravitational ex...

  2. The Eddington Ratio of H2O Maser Host AGN

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2011-03-01

    The Eddington ratio was derived for the entire maser host AGN sample, based on the intrinsic X-ray luminosity, the X-ray bolometric correction X and the mass of central black hole. Further the [O III] bolometric correction [O III] was estimated for our sample. Possible relations were also investigated between the maser luminosity and the bolometric luminosity – the Eddington ratio.

  3. Black Holes, Worm Holes, and Future Space Propulsion

    Science.gov (United States)

    Barret, Chris

    2000-01-01

    NASA has begun examining the technologies needed for an Interstellar Mission. In 1998, a NASA Interstellar Mission Workshop was held at the California Institute of Technology to examine the technologies required. Since then, a spectrum of research efforts to support such a mission has been underway, including many advanced and futuristic space propulsion concepts which are being explored. The study of black holes and wormholes may provide some of the breakthrough physics needed to travel to the stars. The first black hole, CYGXI, was discovered in 1972 in the constellation Cygnus X-1. In 1993, a black hole was found in the center of our Milky Way Galaxy. In 1994, the black hole GRO J1655-40 was discovered by the NASA Marshall Space Flight center using the Gamma Ray Observatory. Today, we believe we have found evidence to support the existence of 19 black holes, but our universe may contain several thousands. This paper discusses the dead star states - - both stable and unstable, white dwarfs, neutron stars, pulsars, quasars, the basic features and types of black holes: nonspinning, nonspinning with charge, spinning, and Hawking's mini black holes. The search for black holes, gravitational waves, and Laser Interferometer Gravitational Wave Observatory (LIGO) are reviewed. Finally, concepts of black hole powered space vehicles and wormhole concepts for rapid interstellar travel are discussed in relation to the NASA Interstellar Mission.

  4. Black Holes, Worm Holes, and Future Space Propulsion

    Science.gov (United States)

    Barret, Chris

    2000-01-01

    NASA has begun examining the technologies needed for an Interstellar Mission. In 1998, a NASA Interstellar Mission Workshop was held at the California Institute of Technology to examine the technologies required. Since then, a spectrum of research efforts to support such a mission has been underway, including many advanced and futuristic space propulsion concepts which are being explored. The study of black holes and wormholes may provide some of the breakthrough physics needed to travel to the stars. The first black hole, CYGXI, was discovered in 1972 in the constellation Cygnus X-1. In 1993, a black hole was found in the center of our Milky Way Galaxy. In 1994, the black hole GRO J1655-40 was discovered by the NASA Marshall Space Flight center using the Gamma Ray Observatory. Today, we believe we have found evidence to support the existence of 19 black holes, but our universe may contain several thousands. This paper discusses the dead star states - - both stable and unstable, white dwarfs, neutron stars, pulsars, quasars, the basic features and types of black holes: nonspinning, nonspinning with charge, spinning, and Hawking's mini black holes. The search for black holes, gravitational waves, and Laser Interferometer Gravitational Wave Observatory (LIGO) are reviewed. Finally, concepts of black hole powered space vehicles and wormhole concepts for rapid interstellar travel are discussed in relation to the NASA Interstellar Mission.

  5. Tensile strength and the mining of black holes.

    Science.gov (United States)

    Brown, Adam R

    2013-11-22

    There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.

  6. Accretion onto a noncommutative geometry inspired black hole

    Science.gov (United States)

    Kumar, Rahul; Ghosh, Sushant G.

    2017-09-01

    The spherically symmetric accretion onto a noncommutative (NC) inspired Schwarzschild black hole is treated for a polytropic fluid. The critical accretion rate \\dot{M}, sonic speed a_s and other flow parameters are generalized for the NC inspired static black hole and compared with the results obtained for the standard Schwarzschild black holes. Also explicit expressions for gas compression ratios and temperature profiles below the accretion radius and at the event horizon are derived. This analysis is a generalization of Michel's solution to the NC geometry. Owing to the NC corrected black hole, the accretion flow parameters also have been modified. It turns out that \\dot{M} ≈ {M^2} is still achievable but r_s seems to be substantially decreased due to the NC effects. They in turn do affect the accretion process.

  7. Fatigue Behavior for Composite Laminates with Circular Hole

    Institute of Scientific and Technical Information of China (English)

    Qi Hongyu; Wen Weidong; Sun Lianwen

    2004-01-01

    Based on the fatigue model of exponential function and WN criterion of static strength for the composite material laminates with a circular hole, the stress correct factorβ is presented. In order to gain the factorβ, the fatigue experiments of laminates with holes in different diameters and the same ratio of width and diameter. The fatigue behavior is usually accompanied with extensive damages. Those damages can affect composite materials in their strength and stiffness. The new model based on damage theory and strain equivalent hypothesis meets engineering requirement.T300/KH304, which is recently studied, is a high capability composite material. The fatigue analysis and tests of laminates with a hole in diameter of 5 mm are carried under difference stress levels. The simple, prompt and practical method was provided for the predication of fatigue life of composite material plate with a circular hole.

  8. Structural Holes in Directed Fuzzy Social Networks

    OpenAIRE

    Renjie Hu; Guangyu Zhang

    2014-01-01

    The structural holes have been a key issue in fuzzy social network analysis. For undirected fuzzy social networks where edges are just present or absent undirected fuzzy relation and have no more information attached, many structural holes measures have been presented, such as key fuzzy structural holes, general fuzzy structural holes, strong fuzzy structural holes, and weak fuzzy structural holes. There has been a growing need to design structural holes measures for directed fuzzy social net...

  9. Geometry of black hole spacetimes

    CERN Document Server

    Andersson, Lars; Blue, Pieter

    2016-01-01

    These notes, based on lectures given at the summer school on Asymptotic Analysis in General Relativity, collect material on the Einstein equations, the geometry of black hole spacetimes, and the analysis of fields on black hole backgrounds. The Kerr model of a rotating black hole in vacuum is expected to be unique and stable. The problem of proving these fundamental facts provides the background for the material presented in these notes. Among the many topics which are relevant for the uniqueness and stability problems are the theory of fields on black hole spacetimes, in particular for gravitational perturbations of the Kerr black hole, and more generally, the study of nonlinear field equations in the presence of trapping. The study of these questions requires tools from several different fields, including Lorentzian geometry, hyperbolic differential equations and spin geometry, which are all relevant to the black hole stability problem.

  10. Deep Hole in 'Clovis'

    Science.gov (United States)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1 At a rock called 'Clovis,' the rock abrasion tool on NASA's Mars Exploration Rover Spirit cut a 9-millimeter (0.35-inch) hole during the rover's 216th martian day, or sol (Aug. 11, 2004). The hole is the deepest drilled in a rock on Mars so far. This approximately true-color view was made from images taken by Spirit's panoramic camera on sol 226 (Aug. 21, 2004) at around 12:50 p.m. local true solar time -- early afternoon in Gusev Crater on Mars. To the right is a 'brush flower' of circles produced by scrubbing the surface of the rock with the abrasion tool's wire brush. Scientists used rover's Moessbauer spectrometer and alpha particle X-ray spectrometer to look for iron-bearing minerals and determine the elemental chemical composition of the rock. This composite combines images taken with the camera's 750-, 530-, and 430-nanometer filters. The grayish-blue hue in this image suggests that the interior of the rock contains iron minerals that are less oxidized than minerals on the surface. The diameter of the hole cut into the rock is 4.5 centimeters (1.8 inches). Data on the graph (Figure 1) from the alpha particle X-ray spectrometer instrument on the robotic arm of NASA's Mars Exploration Rover Spirit reveal the elemental chemistry of two rocks, 'Ebenezer' and 'Clovis,' (see PIA06914) in the 'Columbia Hills.' Scientists found, through comparison of the rocks' chemistry, that Ebenezer and Clovis have very different compositions from the rocks on the Gusev plains.

  11. Collisions Around a Black Hole Mean Mealtime

    Science.gov (United States)

    Kohler, Susanna

    2017-08-01

    When a normally dormant supermassive black hole burps out a brief flare, its assumed that a star was torn apart and fell into the black hole. But a new study suggests that some of these flares might have a slightly different cause.Not a Disruption?Artists impression of a tidal disruption event, in which a star has been pulled apart and its gas feeds the supermassive black hole. [NASA/JPL-Caltech]When a star swings a little too close by a supermassive black hole, the black holes gravity can pull the star apart, completely disrupting it. The resulting gas can then accrete onto the black hole, feeding it and causing it to flare. The predicted frequency of these tidal disruption events and their expected light curves dont perfectly match all our observations of flaring black holes, however.This discrepancy has led two scientists from the Columbia Astrophysics Laboratory, Brian Metzger and Nicholas Stone, to wonder if we can explain flares from supermassive black holes in another way. Could a differentevent masquerade as a tidal disruption?Evolution of a stars semimajor axis (top panel) and radius (bottom panel) as a function of time since Roche-lobe overflow began onto a million-solar-mass black hole. Curves show stars of different masses. [Metzger Stone 2017]Inspirals and OutspiralsIn the dense nuclear star cluster surrounding a supermassive black hole, various interactions can send stars on new paths that take them close to the black hole. In many of these interactions, the stars will end up on plunging orbits, often resulting in tidal disruption. But sometimes stars can approach the black hole on tightly bound orbits with lower eccentricities.A main-sequence star on such a path, in what is known as an extreme mass ratio inspiral (EMRI), slowly approaches the black hole over a period of millions of years, eventually overflowing its Roche lobe and losing mass. Theradius of the star inflates, driving more mass loss and halting the stars inward progress. The star then

  12. Artificial ozone holes

    CERN Document Server

    Dolya, S N

    2014-01-01

    This article considers an opportunity of disinfecting a part of the Earth surface, occupying a large area of ten thousand square kilometers. The sunlight will cause dissociation of molecular bromine into atoms; each bromine atom kills thirty thousand molecules of ozone. Each bromine plate has a mass of forty milligrams grams and destroys ozone in the area of hundred square meters. Thus, to form the ozone hole over the area of ten thousand square kilometers, it is required to have the total mass of bromine equal to the following four tons.

  13. Observing braneworld black holes

    CERN Document Server

    Gregory, R; Beckwith, K; Done, C; Gregory, Ruth; Whisker, Richard; Beckwith, Kris; Done, Chris

    2004-01-01

    Spacetime in the vicinity of an event horizon can be probed using observations which explore the dynamics of the accretion disc. Many high energy theories of gravity lead to modifications of the near horizon regime, potentially providing a testing ground for these theories. In this paper, we explore the impact of braneworld gravity on this region by formulating a method of deriving the general behaviour of the as yet unknown braneworld black hole solution. We use simple bounds to constrain the solution close to the horizon.

  14. Thermal BEC Black Holes

    Directory of Open Access Journals (Sweden)

    Roberto Casadio

    2015-10-01

    Full Text Available We review some features of Bose–Einstein condensate (BEC models of black holes obtained by means of the horizon wave function formalism. We consider the Klein–Gordon equation for a toy graviton field coupled to a static matter current in a spherically-symmetric setup. The classical field reproduces the Newtonian potential generated by the matter source, while the corresponding quantum state is given by a coherent superposition of scalar modes with a continuous occupation number. An attractive self-interaction is needed for bound states to form, the case in which one finds that (approximately one mode is allowed, and the system of N bosons can be self-confined in a volume of the size of the Schwarzschild radius. The horizon wave function formalism is then used to show that the radius of such a system corresponds to a proper horizon. The uncertainty in the size of the horizon is related to the typical energy of Hawking modes: it decreases with the increasing of the black hole mass (larger number of gravitons, resulting in agreement with the semiclassical calculations and which does not hold for a single very massive particle. The spectrum of these systems has two components: a discrete ground state of energy m (the bosons forming the black hole and a continuous spectrum with energy ω > m (representing the Hawking radiation and modeled with a Planckian distribution at the expected Hawking temperature. Assuming the main effect of the internal scatterings is the Hawking radiation, the N-particle state can be collectively described by a single-particle wave-function given by a superposition of a total ground state with energy M = Nm and Entropy 2015, 17 6894 a Planckian distribution for E > M at the same Hawking temperature. This can be used to compute the partition function and to find the usual area law for the entropy, with a logarithmic correction related to the Hawking component. The backreaction of modes with ω > m is also shown to reduce

  15. A bottom hole motor

    Energy Technology Data Exchange (ETDEWEB)

    Kibishcher, G.B.; Karpenko, V.K.; Pogorelov, V.P.

    1982-01-01

    A bottom hole motor is proposed which includes a body, a push rod with a piston, a spindle, a mechanism for converting the reciprocal movement of the piston into rotation of the shaft and pump and drain cavities. In order to simplify the design the push rod is made with radial openings above and below the piston, while the shaft is made with two longitudinal channels at the level of the radial openings of the push rod on the diametrically opposite sides. The cavity of one channel is constantly connected with the pump cavity, while the other is permanently connected with the drain cavity.

  16. Noncommutative black holes

    Energy Technology Data Exchange (ETDEWEB)

    Bastos, C; Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Dias, N C; Prata, J N, E-mail: cbastos@fisica.ist.utl.p, E-mail: orfeu@cosmos.ist.utl.p, E-mail: ncdias@mail.telepac.p, E-mail: joao.prata@mail.telepac.p [Departamento de Matematica, Universidade Lusofona de Humanidades e Tecnologias, Avenida Campo Grande, 376, 1749-024 Lisboa (Portugal)

    2010-04-01

    One considers phase-space noncommutativity in the context of a Kantowski-Sachs cosmological model to study the interior of a Schwarzschild black hole. It is shown that the potential function of the corresponding quantum cosmology problem has a local minimum. One deduces the thermodynamics and show that the Hawking temperature and entropy exhibit an explicit dependence on the momentum noncommutativity parameter, {eta}. Furthermore, the t = r = 0 singularity is analysed in the noncommutative regime and it is shown that the wave function vanishes in this limit.

  17. Black hole accretion discs

    OpenAIRE

    Lasota, Jean-Pierre

    2015-01-01

    This is an introduction to models of accretion discs around black holes. After a presentation of the non-relativistic equations describing the structure and evolution of geometrically thin accretion discs we discuss their steady-state solutions and compare them to observation. Next we describe in detail the thermal-viscous disc instability model and its application to dwarf novae for which it was designed and its X-ray irradiated-disc version which explains the soft X--ray transients, i.e. ou...

  18. Surfing a Black Hole

    Science.gov (United States)

    2002-10-01

    Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours [1] Summary An international team of astronomers [2], lead by researchers at the Max-Planck Institute for Extraterrestrial Physics (MPE) , has directly observed an otherwise normal star orbiting the supermassive black hole at the center of the Milky Way Galaxy. Ten years of painstaking measurements have been crowned by a series of unique images obtained by the Adaptive Optics (AO) NAOS-CONICA (NACO) instrument [3] on the 8.2-m VLT YEPUN telescope at the ESO Paranal Observatory. It turns out that earlier this year the star approached the central Black Hole to within 17 light-hours - only three times the distance between the Sun and planet Pluto - while travelling at no less than 5000 km/sec . Previous measurements of the velocities of stars near the center of the Milky Way and variable X-ray emission from this area have provided the strongest evidence so far of the existence of a central Black Hole in our home galaxy and, implicitly, that the dark mass concentrations seen in many nuclei of other galaxies probably are also supermassive black holes. However, it has not yet been possible to exclude several alternative configurations. In a break-through paper appearing in the research journal Nature on October 17th, 2002, the present team reports their exciting results, including high-resolution images that allow tracing two-thirds of the orbit of a star designated "S2" . It is currently the closest observable star to the compact radio source and massive black hole candidate "SgrA*" ("Sagittarius A") at the very center of the Milky Way. The orbital period is just over 15 years. The new measurements exclude with high confidence that the central dark mass consists of a cluster of unusual stars or elementary particles, and leave little doubt of the presence of a supermassive black hole at the centre of the galaxy in which we live . PR Photo 23a/02 : NACO image of the central region of the Milky Way

  19. Artificial black holes

    CERN Document Server

    Visser, Matt; Volovik, Grigory E

    2009-01-01

    Physicists are pondering on the possibility of simulating black holes in the laboratory by means of various "analog models". These analog models, typically based on condensed matter physics, can be used to help us understand general relativity (Einstein's gravity); conversely, abstract techniques developed in general relativity can sometimes be used to help us understand certain aspects of condensed matter physics. This book contains 13 chapters - written by experts in general relativity, particle physics, and condensed matter physics - that explore various aspects of this two-way traffic.

  20. Assessment of pot-hole subsidence risk for Indian coal mines

    Institute of Scientific and Technical Information of China (English)

    Lokhande D. Ritesh; Murthy Vemavarapu M.S.R.; Vellanky Venkateswarlu; Singh B. Kalendra

    2015-01-01

    Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence. Pot-hole subsidence is extremely hazardous and does not give any prior indication before its occurrence. In India, several pot-holes have occurred in the coal mines of South Eastern Coalfields Limited triggering the need for in-depth studies. In line with the requirement, literature review and field investigations were conducted to develop an in-depth under-standing of various parameters influencing the occurrence of pot-holes. The critical parameters identified were rock to soil ratio, depth to height of extraction ratio, brittleness index of rock and rock density. Risk assessment of pot-hole subsidence has been done by developing an empirical rating approach named as pot-hole subsidence rating (PHSR), involving the critical parameters with suitable corrections for certain structural and mining conditions to obtain corrected PHSR (CPHSR). CPHSR was then applied for all the 34 pot-holes studied and it was found that all the pot-holes fall under Class I and Class II category of risk representing a very high to high risk class. An effort was made for the estimation of pot-hole depth uti-lizing the developed CPHSR in both the development and depillaring cases. The developed approach was found to yield consistent results in pot-hole depth prediction.