WorldWideScience

Sample records for surfaces subsonic characteristics

  1. Breakup characteristics of a liquid jet in subsonic crossflow

    Science.gov (United States)

    Gopala, Yogish

    This thesis describes an experimental investigation of the breakup processes involved in the formation of a spray created by a liquid jet injected into a gaseous crossflow. This work is motivated by the utilization of this method to inject fuel in combustors and afterburners of airplane engines. This study aims to develop a better understanding of the spray breakup processes and to provide better experimental inputs to improve the fidelity of numerical models. A review of the literature in this field identified the fundamental physical processes involved in the breakup of the spray and the dependence of spray properties on operating conditions. The time taken for the liquid column to break up into ligaments and droplets, the primary breakup time and the effect of injector geometry on the spray formation processes and spray properties as the key research areas in which research done so far has been inadequate. Determination of the location where the liquid column broke up was made difficult by the presence of a large number of droplets surrounding it. This study utilizes the liquid jet light guiding technique that enables accurate measurements of this location for a wide range of operating conditions. Prior to this study, the primary breakup time was thought to be a function the density ratio of the liquid and the gas, the diameter of the orifice and the air velocity. This study found that the time to breakup of the liquid column depends on the Reynolds number of the liquid jet. This suggests that the breakup of a turbulent liquid jet is influenced by both the aerodynamic breakup processes and the turbulent breakup processes. Observations of the phenomenon of the liquid jet splitting up into two or more jets were made at some operating conditions with the aid of the new visualization technique. Finally, this thesis investigates the effect of injector geometry on spray characteristics. One injector was a round edged orifice with a length to diameter ratio of 1 and a

  2. Mixing characteristics of pulsed air-assist liquid jet into an internal subsonic cross-flow

    Science.gov (United States)

    Lee, Inchul; Kang, Youngsu; Koo, Jaye

    2010-04-01

    Penetration depth, spray dispersion angle, droplet sizes in breakup processes and atomization processes are very important parameters in combustor of air-breathing engine. These processes will enhance air/fuel mixing inside the combustor. Experimental results from the pulsed air-assist liquid jet injected into a cross-flow are investigated. And experiments were conducted to a range of cross-flow velocities from 42˜136 m/s. Air is injected with 0˜300kPa, with air-assist pulsation frequency of 0˜20Hz. Pulsation frequency was modulated by solenoid valve. Phase Doppler Particle Analyzer(PDPA) was utilized to quantitatively measuring droplet characteristics. High-speed CCD camera was used to obtain injected spray structure. Pulsed air-assist liquid jet will offer rapid mixing and good liquid jet penetration. Air-assist makes a very fine droplet which generated mist-like spray. Pulsed air-assist liquid jet will introduce additional supplementary turbulent mixing and control of penetration depth into a cross-flow field. The results show that pulsation frequency has an effect on penetration, transverse velocities and droplet sizes. The experimental data generated in these studies are used for a development of active control strategies to optimize the liquid jet penetration in subsonic cross-flow conditions and predict combustion low frequency instability.

  3. Wing-Alone Aerodynamic Characteristics to High Angles of Attack at Subsonic and Transonic Speeds.

    Science.gov (United States)

    1982-11-01

    indicators of symmetry since the wings were unbanked within the limits of tolerances and flow angularity. Longitudinal, spanwise, and vertical... unbanked wings at subsonic and transonic speeds from low to high angles of attack. The wing planforms varied in aspect ratio and taper ratio with

  4. Low-Subsonic-Speed Static Longitudinal Stability and Control Characteristics of a Winged Reentry-Vehicle Configuration Having Wingtip Panels that Fold up for High-Drag Reentry

    Science.gov (United States)

    Ware, George M.

    1960-01-01

    An investigation of the low-subsonic-speed static longitudinal stability and control characteristics of a model of a manned reentry-vehicle configuration capable of high-drag reentry and glide landing has been a made in the Langley free-flight tunnel. The model had a modified 63 deg delta plan-form wing with a fuselage on the upper surface. This configuration had wingtip panels designed to fold up 90 deg for the high-drag reentry phase of the flight and to extend horizontally for the glide landing. Data for the basic configurations and modifications to determine the effects of plan form, wingtip panel incidence, dihedral, and vertical position of the wingtip panels are presented without analysis.

  5. Guidelines for Computing Longitudinal Dynamic Stability Characteristics of a Subsonic Transport

    Science.gov (United States)

    Thompson, Joseph R.; Frank, Neal T.; Murphy, Patrick C.

    2010-01-01

    A systematic study is presented to guide the selection of a numerical solution strategy for URANS computation of a subsonic transport configuration undergoing simulated forced oscillation about its pitch axis. Forced oscillation is central to the prevalent wind tunnel methodology for quantifying aircraft dynamic stability derivatives from force and moment coefficients, which is the ultimate goal for the computational simulations. Extensive computations are performed that lead in key insights of the critical numerical parameters affecting solution convergence. A preliminary linear harmonic analysis is included to demonstrate the potential of extracting dynamic stability derivatives from computational solutions.

  6. Steady, subsonic, lifting surface theory for wings with swept, partial span, trailing edge control surfaces

    Science.gov (United States)

    Medan, R. T.

    1973-01-01

    A method for computing the lifting pressure distribution on a wing with partial span, swept control surfaces is presented. This method is valid within the framework of linearized, steady, potential flow theory and consists of using conventional lifting surface theory in conjuction with a flap pressure mode. The cause of a numerical instability that can occur during the quadrature of the flap pressure mode is discussed, and an efficient technique to eliminate the instability is derived. This technique is valid for both the flap pressure mode and regular pressure modes and could be used to improve existing lifting surface methods. Examples of the use of the flap pressure mode and comparisons among this method, other theoretical methods, and experiments are given. Discrepancies with experiment are indicated and candidate causes are presented. It is concluded that the method can lead to an efficient and accurate solution of the mathematical problem when a partial span, trailing edge flap is involved.

  7. Subsonic aerodynamic characteristic of semispan commercial transport model with wing-mounted advanced ducted propeller operating in reverse thrust. [conducted in the Langley 14 by 22 foot subsonic wind tunnel

    Science.gov (United States)

    Applin, Zachary T.; Jones, Kenneth M.; Gile, Brenda E.; Quinto, P. Frank

    1994-01-01

    A test was conducted in the Langley 14 by 22 Foot Subsonic Tunnel to determine the effect of the reverse-thrust flow field of a wing-mounted advanced ducted propeller on the aerodynamic characteristics of a semispan subsonic high-lift transport model. The advanced ducted propeller (ADP) model was mounted separately in position alongside the wing so that only the aerodynamic interference of the propeller and nacelle affected the aerodynamic performance of the transport model. Mach numbers ranged from 0.14 to 0.26; corresponding Reynolds numbers ranged from 2.2 to 3.9 x 10(exp 6). The reverse-thrust flow field of the ADP shielded a portion of the wing from the free-stream airflow and reduced both lift and drag. The reduction in lift and drag was a function of ADP rotational speed and free-stream velocity. Test results included ground effects data for the transport model and ADP configuration. The ground plane caused a beneficial increase in drag and an undesirable slight increase in lift. The ADP and transport model performance in ground effect was similar to performance trends observed for out of ground effect. The test results form a comprehensive data set that supports the application of the ADP engine and airplane concept on the next generation of advanced subsonic transports. Before this investigation, the engine application was predicted to have detrimental ground effect characteristics. Ground effect test measurements indicated no critical problems and were the first step in proving the viability of this engine and airplane configuration.

  8. Effect of winglets on a first-generation jet transport wing. 5: Stability characteristics of a full-span wing with a generalized fuselage at high subsonic speeds

    Science.gov (United States)

    Jacobs, P. F.

    1978-01-01

    The effects of winglets on the static aerodynamic stability characteristics of a KC-135A jet transport model at high subsonic speeds are presented. The investigation was conducted in the Langley 8 foot transonic pressure tunnel using 0.035-scale wing panels mounted on a generalized research fuselage. Data were taken over a Mach number range from 0.50 to 0.95 at angles of attack ranging from -12 deg to 20 deg and sideslip angles of 0 deg, 5 deg, and -5 deg. The model was tested at two Reynolds number ranges to achieve a wide angle of attack range and to determine the effect of Reynolds number on stability. Results indicate that adding the winglets to the basic wing configuration produces small increases in both lateral and longitudinal aerodynamic stability and that the model stability increases slightly with Reynolds number. The winglets do increase the wing bending moments slightly, but the buffet onset characteristics of the model are not affected by the winglets.

  9. Investigation of Inlet Condition Effect on Flow and Turbulence Characteristics in Subsonic Jets from Conical and Chevron Nozzles Using RANS/ILES High Resolutions Method

    Directory of Open Access Journals (Sweden)

    L. A. Benderskiy

    2015-01-01

    Full Text Available Effect of Mach number and temperature on subsonic jets flow with a combined highresolution RANS/ILES method (Reynolds Averaged Navier-Stokes - RANS, Implicit Large Eddy Simulation - ILES was investigated. Cold Mj=0.985 T0=300К and hot Mj=0.548 T0=858.6К jets were considered (Mj – Mach number at the nozzle exit and T0 – total temperature at the nozzle inlet. Conical and two chevron nozzles with angle of chevrons to the nozzle axis α=5° and α=18.2° were investigated. The jet flow calculations were carried out together with flow calculation in nozzles. Computation grids were Meshes for simulations (2.8-3.2×106 cells. Investigated cases were compared by average velocity and velocity fluctuations at the jet axis and at the mixing layer. The magnitude of velocity fluctuations at the jet axis and at the mixing layer for hot jets is higher than for cold jets. It leads to increasing expansion angle of the mixing layer inward the jet axis. This is why the initial part length of hot jets becomes shorter than in cold jets. Comparison of simulations with the experimental data of other authors showed a good agreement by flow and turbulences characteristics.

  10. Space Shuttle Orbiter trimmed center-of-gravity extension study. Volume 7: Effects of configuration modifications on the subsonic aerodynamic characteristics of the 1140 A/B orbbiter at high Reynolds numbers. [Langley low turbulence pressure tunnel

    Science.gov (United States)

    Phillips, W. P.

    1981-01-01

    Subsonic longitudinal andd laternal directional characteristics were obtained for several modified configurations of the 140 A/B orbiter (0.010 scale). These modifications, designed to extend longitudinal trim capability forward of the 65 percent fuselage length station, consisted of modified wing planform fillet and a canard. Tests were performed in the Langley Low Turbulence Pressure Tunnel at Reynolds numbers from about 4.2 million to 14.3 million based on the fuselage reference length.

  11. Wind-Tunnel Investigation of Subsonic Longitudinal Aerodynamic Characteristics of a Tiltable-Wing Vertical-Take-Off-and-Landing Supersonic Bomber Configuration Including Turbojet Power Effects

    Science.gov (United States)

    Thompson, Robert F.; Vogler, Raymond D.; Moseley, William C., Jr.

    1959-01-01

    Jet-powered model tests were made to determine the low-speed longitudinal aerodynamic characteristics of a vertical-take-off and-landing supersonic bomber configuration. The configuration has an unique engine-wing arrangement wherein six large turbojet engines (three on each side of the fuselage) are buried in a low-aspect-ratio wing which is tilted into the vertical plane for take-off. An essentially two-dimensional variable inlet, spanning the leading edge of each wing semispan, provides air for the engines. Jet flow conditions were simulated for a range of military (nonafterburner) and afterburner turbojet-powered flight at subsonic speeds. Three horizontal tails were tested at a station down-stream of the jet exit and at three heights above the jet axes. A semi-span model was used and test parameters covered wing-fuselage incidence angles from 0 deg to 15 deg, wing angles of attack from -4 deg to 36 deg, a variable range of horizontal-tail incidence angles, and some variations in power simulation conditions. Results show that, with all horizontal tails tested, there were large variations in static stability throughout the lift range. When the wing and fuselage were alined, the model was statically stable throughout the test range only with the largest tail tested (tail span of 1.25 wing span) and only when the tail was located in the low test position which placed the tail nearest to the undeflected jet. For transition flight conditions, none of the tail configurations provided satisfactory longitudinal stability or trim throughout the lift range. Jet flow was destabilizing for most of the test conditions, and varying the jet-exit flow conditions at a constant thrust coefficient had little effect on the stability of this model. Wing leading-edge simulation had some important effects on the longitudinal aerodynamic characteristics.

  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. INCAS SUBSONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Corneliu STOICA

    2009-09-01

    Full Text Available The INCAS Subsonic Wind Tunnel is a closed circuit, continuous, atmospheric pressure facility with a maximum speed of 110 m/s. The test section is octagonal ,of 2.5 m wide, 2.0 m high and 4 m long. The tunnel is powered by a 1200 kW, air cooled variable speed DC motor which drives a 12 blade, 3.5 m diameter fan and is equipped with a six component pyramidal type external mechanical balance with a 700 Kgf maximum lift capacity.The angle of attack range is between -45º and +45º while the yaw angle range is between -140º and +216º .The data acquisition system has been modified recently to allow the recording of all test data on a PC - type computer using LABVIEW and a PXI – type chassis containing specialized data acquisition modules.The tunnel is equipped with a variable frequency electrical supply system for powered models and a 10 bar compressed air supply for pneumatic flow control applications.In the recent years the subsonic wind tunnel has been intensively used for tests within several European projects (AVERT, CESAR and others.

  14. Subsonic Aerodynamic Research Laboratory (SARL)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The SARL is a unique high contraction, open circuit subsonic wind tunnel providing a test velocity up to 436 mph (0.5 Mach number) and a high quality,...

  15. Subsonic potential aerodynamics for complex configurations - A general theory

    Science.gov (United States)

    Morino, L.; Kuo, C.-C.

    1974-01-01

    A general theory of subsonic potential aerodynamic flow around a lifting body having arbitrary shape and motion is presented. By using the Green function method, an integral representation for the velocity potential is obtained for both supersonic and subsonic flow. Under the small perturbation assumption, the potential at any point in the field depends only upon the values of the potential and its normal derivative on the surface of the body. On the surface of the body, this representation reduces to an integro-differential equation relating the potential and its normal derivative (which is known from the boundary conditions) on the surface. The theory is applied to finite-thickness wings in subsonic steady and oscillatory flows.

  16. Rheological characteristics of soft rock structural surface

    Institute of Scientific and Technical Information of China (English)

    陈沅江; 吴超; 傅衣铭

    2008-01-01

    There are two mechanisms of the coarse surface asperity resistance effect and rubbing resistance effect in the course of the soft rock structural surface creep,of which the former plays a dominant role in hindering the deformation in the starting creep phase,so that the structural surface creep usually displays the strong surface roughness effect,and so does the latter when the asperities in the coarse surface were fractured by shearing.Under the low stress condition,there are only two phases of the decelerating creep and the constant creep for the soft rock structural surface,and as the stress increases and overcomes the rubbing resistance,the accelerating creep failure of the structural surface will happen suddenly.Therefore,a multiple rheological model,which combines the nonlinear NEWTON body(NN) of a certain mass and the empirical plastic body(EM) with the classical SAINT VENANT body,NEWTON body,KELVIN body and HOOKE body,could be used to comprehensively describe the creep characteristics of the soft rock structural surface.Its mechanical parameter values will vary owing to the different surface roughness of the structural surface.The parameters of GH,GK and ηL are positively linearly correlative to the surface roughness.The surface roughness and m are negative exponential function correlation.The long-term strength τS is positively correlative to the surface roughness.

  17. Experimental study of subsonic microjet escaping from a rectangular nozzle

    Science.gov (United States)

    Aniskin, V. M.; Maslov, A. A.; Mukhin, K. A.

    2016-10-01

    The first experiments on the subsonic laminar microjets escaping from the nozzles of rectangular shape are carried out. The nozzle size is 83.3x3823 microns. Reynolds number calculated by the nozzle height and the average flow velocity at the nozzle exit ranged from 58 to 154. The working gas was air at room temperature. The velocity decay and velocity fluctuations along the center line of the jet are determined. The fundamental difference between the laminar microjets characteristics and subsonic turbulent jets of macro size is shown. Based on measurements of velocity fluctuations it is shown the presence of laminar-turbulent transition in microjets and its location is determined.

  18. Euler Characteristic and Quadrilaterals of Normal Surfaces

    Indian Academy of Sciences (India)

    Tejas Kalelkar

    2008-05-01

    Let be a compact 3-manifold with a triangulation . We give an inequality relating the Euler characteristic of a surface normally embedded in with the number of normal quadrilaterals in . This gives a relation between a topological invariant of the surface and a quantity derived from its combinatorial description. Secondly, we obtain an inequality relating the number of normal triangles and normal quadrilaterals of , that depends on the maximum number of tetrahedrons that share a vertex in .

  19. Wetting Characteristics of Insect Wing Surfaces

    Institute of Scientific and Technical Information of China (English)

    Doyoung Byun; Jongin Hong; Saputra; Jin Hwan Ko; Young Jong Lee; Hoon Cheol Park; Bong-Kyu Byun; Jennifer R. Lukes

    2009-01-01

    Biological tiny structures have been observed on many kinds of surfaces such as lotus leaves, which have an effect on the coloration of Morpho butterflies and enhance the hydrophobicity of natural surfaces. We investigated the micro-scale and nano-scale structures on the wing surfaces of insects and found that the hierarchical multiple roughness structures help in enhancing the hydrophobicity. After examining 10 orders and 24 species of flying Pterygotan insects, we found that micro-scale and nano-scale structures typically exist on both the upper and lower wing surfaces of flying insects. The tiny structures such as denticle or setae on the insect wings enhance the hydrophobicity, thereby enabling the wings to be cleaned more easily. And the hydrophobic insect wings undergo a transition from Cassie to Wenzel states at pitch/size ratio of about 20. In order to examine the wetting characteristics on a rough surface, a biomimetic surface with micro-scale pillars is fabricated on a silicon wafer,which exhibits the same behavior as the insect wing, with the Cassie-Wenzel transition occurring consistently around a pitch/width value of 20.

  20. Polyspecies biofilm formation on implant surfaces with different surface characteristics

    Directory of Open Access Journals (Sweden)

    Patrick R. SCHMIDLIN

    2013-01-01

    Full Text Available Objective To investigate the microbial adherence and colonization of a polyspecies biofilm on 7 differently processed titanium surfaces. Material and Methods Six-species biofilms were formed anaerobically on 5-mm-diameter sterilized, saliva-preconditioned titanium discs. Material surfaces used were either machined, stained, acid-etched or sandblasted/acid-etched (SLA. Samples of the latter two materials were also provided in a chemically modified form, with increased wettability characteristics. Surface roughness and contact angles of all materials were determined. The discs were then incubated anaerobically for up to 16.5 h. Initial microbial adherence was evaluated after 20 min incubation and further colonization after 2, 4, 8, and 16.5 h using non-selective and selective culture techniques. Results at different time points were compared using ANOVA and Scheffé post hoc analysis. Results The mean differences in microorganisms colonizing after the first 20 min were in a very narrow range (4.5 to 4.8 log CFU. At up to 16.5 h, the modified SLA surface exhibited the highest values for colonization (6.9±0.2 log CFU, p<0.05 but increasing growth was observed on all test surfaces over time. Discrepancies among bacterial strains on the differently crafted titanium surfaces were very similar to those described for total log CFU. F. nucleatum was below the detection limit on all surfaces after 4 h. Conclusion Within the limitations of this in vitro study, surface roughness had a moderate influence on biofilm formation, while wettability did not seem to influence biofilm formation under the experimental conditions described. The modified SLA surface showed the highest trend for bacterial colonization.

  1. Stability of separating subsonic boundary layers

    Science.gov (United States)

    Masad, Jamal A.; Nayfeh, Ali H.

    1994-01-01

    The primary and subharmonic instabilities of separating compressible subsonic two-dimensional boundary layers in the presence of a two-dimensional roughness element on a flat plate are investigated. The roughness elements considered are humps and forward- and backward-facing steps. The use of cooling and suction to control these instabilities is studied. The similarities and differences between the instability characteristics of separating boundary layers and those of the boundary layer over a flat plate with a zero pressure gradient are pointed out and discussed. The theoretical results agree qualitatively and quantitatively with the experimental data of Dovgal and Kozlov. Cooling and suction decrease the growth rates of primary and subharmonic waves in the attached-flow regions but increase them in the separated-flow regions.

  2. Experimental investigation on a high subsonic compressor cascade flow

    Directory of Open Access Journals (Sweden)

    Zhang Haideng

    2015-08-01

    Full Text Available With the aim of deepening the understanding of high-speed compressor cascade flow, this paper reports an experimental study on NACA-65 K48 compressor cascade with high subsonic inlet flow. With the increase of passage pressurizing ability, endwall boundary layer behavior is deteriorated, and the transition zone is extended from suction surface to the endwall as the adverse pressure gradient increases. Cross flow from endwall to midspan, mixing of corner boundary layer and the main stream, and reversal flow on the suction surface are caused by corner separation vortex structures. Passage vortex is the main corner separation vortex. During its movement downstream, the size grows bigger while the rotating direction changes, forming a limiting circle. With higher incidence, corner separation is further deteriorated, leading to higher flow loss. Meanwhile, corner separation structure, flow mixing characteristics and flow loss distribution vary a lot with the change of incidence. Compared with low aspect-ratio model, corner separation of high aspect-ratio model moves away from the endwall and is more sufficiently developed downstream the cascade. Results obtained present details of high-speed compressor cascade flow, which is rare in the relating research fields and is beneficial to mechanism analysis, aerodynamic optimization and flow control design.

  3. Deployment of a Pressure Sensitive Paint System for Measuring Global Surface Pressures on Rotorcraft Blades in Simulated Forward Flight: Preliminary PSP Results from Test 581 in the 14- by 22-Foot Subsonic Tunnel

    Science.gov (United States)

    Watkins, Anthony Neal; Leighty, Bradley D.; Lipford, William E.; Wong, Oliver D.; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

    2011-01-01

    This report will present details of a Pressure Sensitive Paint (PSP) system for measuring global surface pressures on the tips of rotorcraft blades in simulated forward flight at the 14- x 22-Foot Subsonic Tunnel. The system was designed to use a pulsed laser as an excitation source and PSP data was collected using the lifetime-based approach. With the higher intensity of the laser, this allowed PSP images to be acquired during a single laser pulse, resulting in the collection of crisp images that can be used to determine blade pressure at a specific instant in time. This is extremely important in rotorcraft applications as the blades experience dramatically different flow fields depending on their position in the rotor disk. Testing of the system was performed using the U.S. Army General Rotor Model System equipped with four identical blades. Two of the blades were instrumented with pressure transducers to allow for comparison of the results obtained from the PSP. This report will also detail possible improvements to the system.

  4. Dispersion and surface characteristics of nanosilica suspensions.

    Science.gov (United States)

    Kumar, Ranganathan; Milanova, Denitsa

    2009-04-01

    Nanofluids consisting of nanometer-sized particles dispersed in base liquids are known to be effective in extending the saturated boiling regime and critical heat flux in pool boiling. The heat transfer characteristics of nanosilica suspensions with particle sizes of 10 and 20 nm in pool boiling with a suspended heating Nichrome wire have been analyzed. The pH value of the nanosuspensions is important from the point of view that it determines the stability of the particles and their mutual interactions toward the suspended heated wire. When silica is suspended in water with no additives, the surface potential of the nanoparticles determines their movement toward the electrodes. Particles continuously deposit on the wire and extend the burnout heat flux, influenced by the chemical composition of the nanofluids. This agglomeration allows high heat transfer through interagglomerate pores, resulting in a nearly threefold increase in burnout heat flux. Particle size, zeta potential, and the burnout heat flux values under different volume concentrations are provided. The burnout heat flux of the wire does not increase monotonically with concentration, but depends on the agglomeration characteristics, particle shape, and the hydroxylated surface of the nanoparticles.

  5. Investigation of High-Subsonic Performance Characteristics of a 12 Degree 21-Inch Conical Diffuser, Including the Effects of Change in Inlet-Boundary-Layer Thickness

    Science.gov (United States)

    Copp, Martin R.; Klevatt, Paul L.

    1950-01-01

    Investigations were conducted of a 12 degree 21-inch conical diffuser of 2:l area ratio to determine the interrelation of boundary layer growth and performance characteristics. surveys were made of inlet and exit from, longitudinal static pressures were recorded, and velocity profiles were obtained through an inlet Reynolds number range, determined From mass flows and based on inlet diameter of 1.45 x 10(exp 6) to 7.45 x 10(exp 6) and a Mach number range of 0.11 to approximately choking. These investigations were made to two thicknesses of inlet boundary layer. The mean value, over the entire range of inlet velocities, of the displacement thickness of the thinner inlet boundary layer was approximately 0.035 inch and that of the thicker inlet boundary layer was approximately six times this value. The loss coefficient in the case of the thinner inlet boundary layer had a value between 2 to 3 percent of the inlet impact pressure over most of the air-flow range. The loss coefficient with the thicker inlet boundary layer was of the order of twice that of the thinner inlet boundary layer at low speeds and approximately three times at high speeds. In both cases the values were substantially less than those given in the literature for fully developed pipe flow. The static-pressure rise for the thinner inlet boundary layer was of the order of 95 percent of that theoretically possible over the entire speed range. For the thicker inlet boundary layer the static pressure rise, as a percentage of that theoretically possible, ranged from 82 percent at low speeds to 68 percent at high speeds.

  6. Determination of forced convective heat transfer coefficients for subsonic flows over heated asymmetric NANA 4412 airfoil

    Science.gov (United States)

    Dag, Yusuf

    Forced convection over traditional surfaces such as flat plate, cylinder and sphere have been well researched and documented. Data on forced convection over airfoil surfaces, however, remain very scanty in literature. High altitude vehicles that employ airfoils as lifting surfaces often suffer leading edge ice accretions which have tremendous negative consequences on the lifting capabilities and stability of the vehicle. One of the ways of mitigating the effect of ice accretion involves judicious leading edge convective cooling technique which in turn depends on the accuracy of convective heat transfer coefficient used in the analysis. In this study empirical investigation of convective heat transfer measurements on asymmetric airfoil is presented at different angle of attacks ranging from 0° to 20° under subsonic flow regime. The top and bottom surface temperatures are measured at given points using Senflex hot film sensors (Tao System Inc.) and used to determine heat transfer characteristics of the airfoils. The model surfaces are subjected to constant heat fluxes using KP Kapton flexible heating pads. The monitored temperature data are then utilized to determine the heat convection coefficients modelled empirically as the Nusselt Number on the surface of the airfoil. The experimental work is conducted in an open circuit-Eiffel type wind tunnel, powered by a 37 kW electrical motor that is able to generate subsonic air velocities up to around 41 m/s in the 24 square-inch test section. The heat transfer experiments have been carried out under constant heat flux supply to the asymmetric airfoil. The convective heat transfer coefficients are determined from measured surface temperature and free stream temperature and investigated in the form of Nusselt number. The variation of Nusselt number is shown with Reynolds number at various angles of attacks. It is concluded that Nusselt number increases with increasing Reynolds number and increase in angle of attack from 0

  7. Reflectance Spectral Characteristics of Lunar Surface Materials

    Institute of Scientific and Technical Information of China (English)

    Yong-Liao Zou; Jian-Zhong Liu; Jian-Jun Liu; Tao Xu

    2004-01-01

    Based on a comprehensive analysis of the mineral composition of major lunar rocks (highland anorthosite, lunar mare basalt and KREEP rock), we investigate the reflectance spectral characteristics of the lunar rock-forming minerals, including feldspar, pyroxene and olivine. The affecting factors, the variation of the intensity of solar radiation with wavelength and the reflectance spectra of the lunar rocks are studied. We also calculate the reflectivity of lunar mare basalt and highland anorthosite at 300 nm, 415 nm, 750 nm, 900 nm, 950 nm and 1000 nm.It is considered that the difference in composition between lunar mare basalt and highland anorthosite is so large that separate analyses are needed in the study of the reflectivity of lunar surface materials in the two regions covered by mare basalt and highland anorthosite, and especially in the region with high Th contents, which may be the KREEP-distributed region.

  8. 10 CFR 960.5-2-8 - Surface characteristics.

    Science.gov (United States)

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Surface characteristics. 960.5-2-8 Section 960.5-2-8... Closure § 960.5-2-8 Surface characteristics. (a) Qualifying condition. The site shall be located such that, considering the surface characteristics and conditions of the site and surrounding area, including...

  9. Steady- and unsteady-pressure measurements on a supercritical-wing model with oscillating control surfaces at subsonic and transonic speeds

    Science.gov (United States)

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

    1983-01-01

    A high aspect ratio supercritical wing with oscillating control surfaces is described. The semispan wing model was instrumented with 252 static pressure orifices and 164 in situ dynamic pressure gages for studying the effects of control surface position and sinusoidal motion on steady and unsteady pressures. Results from the present test (the third in a series of tests on this model) were obtained in the Langley Transonic Dynamics Tunnel at Mach numbers of 0.60, 0.78, and 0.86 and are presented in tabular form.

  10. Numerical simulation of subsonic and transonic flow flieds and aerodynamic characteristics of anti-tank intelligent mine%反坦克智能雷亚、跨音速气动特性数值仿真

    Institute of Scientific and Technical Information of China (English)

    王妍; 周春桂; 王志军

    2015-01-01

    反坦克智能雷是一种依托高精度探测器件的新型智能反坦克炸弹。智能雷实现高效捕获、毁伤目标时,应考虑风阻系数等因素其飞行特性的影响。本文基于智能雷的三维模型,分析了亚、跨音速智能雷流场以及气动力因数随迎角的增长规律。应用计算流体力学软件对智能雷外流场进行数值计算,得到智能雷压心位置的变化规律。结果显示阻力系数的值比较大,有利于智能雷维持稳定扫描状态。智能雷附近剧烈的流场变化可能导致其扫描运动失效。仿真结果能够作为智能雷扫描稳定性分析、总体性能优化和外形改良的参照。%Anti-tank intelligent mine is a kind of new intelligent anti-tank bomb relying on high precision detector.It can effec-tively capture and damage targets with wind resistance coefficient and other factors affecting its flight characteristics under con-sideration.This article is based on the three-dimensional model of intelligent mine.To analyze its subsonic and transonic flow fields and the change law of aerodynamic force factor with the growth of the angle of attack,computational fluid dynamics soft-ware is used for intelligent mine flow field numerical calculation and the change law of pressure center.The results show that the large drag coefficient is conducive to the stability of scanning.Drastic changes of the flow field near the intelligent mine will disable its scanning movement.The simulation results can provide a reference for scanning stability analysis,overall perform-ance optimization and appearance improvement.

  11. Effect of de-correlating turbulence on the low frequency decay of jet-surface interaction noise in sub-sonic unheated air jets using a CFD-based approach

    Science.gov (United States)

    Afsar, M. Z.; Leib, S. J.; Bozak, R. F.

    2017-01-01

    In this paper we extend the Rapid-distortion theory (RDT)-based model derived by Goldstein, Afsar & Leib (J. Fluid Mech., vol. 736, pp. 532-569, 2013) for the sound generated by the interaction of a large-aspect-ratio rectangular jet with the trailing edge of a flat plate to include a more realistic upstream turbulence spectrum that possess a de-correlation (i.e. negative dip) in its space-time structure and use results from three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solutions to determine the mean flow, turbulent kinetic energy and turbulence length & time scales. Since the interaction noise dominates the low-frequency portion of the spectrum, we use an appropriate asymptotic approximation for the Rayleigh equation Green's function, which enters the analysis, based on a two-dimensional mean flow representation for the jet. We use the model to predict jet-surface interaction noise for a range of subsonic acoustic Mach number jets, nozzle aspect ratios, streamwise and transverse trailing-edge locations and compare them with experimental data. The RANS meanflow computations are also compared with flow data for selected cases to assess their validity. We find that finite de-correlation in the turbulence spectrum increases the low-frequency algebraic decay (the low-frequency "roll-off") of the acoustic spectrum with angular frequency to give a model that has a pure dipole frequency scaling. This gives better agreement with noise data compared to Goldstein et al. (2013) for Strouhal numbers less than the peak jet-surface interaction noise. For example, through sensitivity analysis we find that there is a difference of 10 dB at the lowest frequency for which data exists (relative to a model without de-correlation effects included) for the highest acoustic Mach number case. Secondly, our results for the planar flow theory provide a first estimate of the low-frequency amplification due to the jet-surface interaction for moderate aspect ratio nozzles when RANS

  12. Contact of surfaces and contact characteristics of offset surfaces

    Institute of Scientific and Technical Information of China (English)

    Lixin CAO; Hu GONG; Jian LIU

    2008-01-01

    Based on differential geometry, the contact problems of two surfaces are discussed in this paper. The relationship between the contact status of two sur-faces and that of offset surfaces are also analyzed. For a 5-axis NC machining, some research such as optimization of cutter location and calculation of the geometrical cusp height are important. The research results indicate that the relative normal curvature is an important geometrical invariant for describing the contact state of two surfaces. For point contact two surfaces, the calculation equation for the second order remained error is given. For line contact two surfaces, the condition of the second order line contact is that the principal directions and curvatures of the two surfaces are the same along the contact curve. If two surfaces keep the second order line contact, their two offset surfaces will also keep the second order line contact, and their third order remained errors are also uniform with that of the two offset surfaces.

  13. Subsonic Ultra Green Aircraft Research

    Science.gov (United States)

    Bradley, Marty K.; Droney, Christopher K.

    2011-01-01

    This Final Report summarizes the work accomplished by the Boeing Subsonic Ultra Green Aircraft Research (SUGAR) team in Phase 1, which includes the time period of October 2008 through March 2010. The team consisted of Boeing Research and Technology, Boeing Commercial Airplanes, General Electric, and Georgia Tech. The team completed the development of a comprehensive future scenario for world-wide commercial aviation, selected baseline and advanced configurations for detailed study, generated technology suites for each configuration, conducted detailed performance analysis, calculated noise and emissions, assessed technology risks, and developed technology roadmaps. Five concepts were evaluated in detail: 2008 baseline, N+3 reference, N+3 high span strut braced wing, N+3 gas turbine battery electric concept, and N+3 hybrid wing body. A wide portfolio of technologies was identified to address the NASA N+3 goals. Significant improvements in air traffic management, aerodynamics, materials and structures, aircraft systems, propulsion, and acoustics are needed. Recommendations for Phase 2 concept and technology projects have been identified.

  14. Surface characteristics of PLA and PLGA films

    Energy Technology Data Exchange (ETDEWEB)

    Paragkumar N, Thanki [Laboratoire de Chimie-Physique Macromoleculaire (LCPM), UMR CNRS-INPL 7568, Groupe ENSIC, 1 rue Grandville, B.P. 20451, 54001 Nancy Cedex (France); Edith, Dellacherie [Laboratoire de Chimie-Physique Macromoleculaire (LCPM), UMR CNRS-INPL 7568, Groupe ENSIC, 1 rue Grandville, B.P. 20451, 54001 Nancy Cedex (France); Six, Jean-Luc [Laboratoire de Chimie-Physique Macromoleculaire (LCPM), UMR CNRS-INPL 7568, Groupe ENSIC, 1 rue Grandville, B.P. 20451, 54001 Nancy Cedex (France)]. E-mail: Jean-Luc.Six@ensic.inpl-nancy.fr

    2006-12-30

    Surface segregation and restructuring in polylactides (poly(D,L-lactide) and poly(L-lactide)) and poly(D,L-lactide-co-glycolide) (PLGA) films of various thicknesses were investigated using both attenuated total reflection FTIR (ATR-FTIR) and contact angle relaxation measurements. In case of poly(D,L-lactide) (DLPLA), it was observed that the surface segregation and the surface restructuring of methyl side groups are influenced by the polymer film thickness. This result has been confirmed by X-ray photoelectron spectroscopy (XPS). In the same way, PLGA thick films were also characterized by an extensive surface segregation of methyl side groups. Finally, surface restructuring was investigated by dynamic contact angle measurements and it was observed when film surface comes into contact with water. In parallel, we also found that poly(L-lactide) (PLLA) thin and clear films with thickness {approx}15 {mu}m undergo conformational changes on the surface upon solvent treatment with certain solvents. The solvent treated surface of PLLA becomes hazy and milky white and its hydrophobicity increases compared to untreated surface. FTIR spectroscopic analysis indicated that polymer chains at the surface undergo certain conformational changes upon solvent treatment. These changes are identified as the restricted motions of C-O-C segments and more intense and specific vibrations of methyl side groups. During solvent treatment, the change in water contact angle and FTIR spectrum of PLLA is well correlated.

  15. Optimal Design of a Subsonic Submerged Inlet

    Science.gov (United States)

    Taskinoglu, Ezgi; Jovanovic, Vasilije; Elliott, Gregory; Knight, Doyle

    2003-11-01

    A multi-objective optimization study based on an epsilon-constraint method is conducted for the design optimization of a subsonic submerged air vehicle inlet. The multi-objective optimization problem is reformulated by minimizing one of the objectives and restricting the other objectives within user specified values. The figures of merits are the engine-face distortion and swirl that determines the inlet/engine compatibility. The distortion index is minimized while the feasible design space is determined by the swirl index. The design variables are the geometrical parameters defining the surface alteration. The design algorithm is driven by a gradient-based optimizer, and is constructed by integrating the optimizer with a solid modeller (Pro/Engineer), a mesh generator (Grid/Pro) and a flow solver (GASPex). The optimizer is CFSQP (C code for Feasible Sequential Quadratic Programming). Integration of the software packages is achieved by a Perl script. In order to verify the numerical results, an experimental setup for the same inlet geometry is prepared to run at the same flow conditions. The presentation will describe the numerical approach and summarize the results.

  16. Modeling Characteristics Of Surfaces For Radar Polarimetry

    Science.gov (United States)

    Van Zyl, Jakob J.; Zebker, Howard A.; Durden, Stephen L.

    1992-01-01

    Paper reviews mathematical models of polarimetric radar backscattering characteristics of various types of terrain; forests, grasslands, and lava fields. Represents approach to imaging radar polarimetry in which one accumulates models predicting realistic polarization signatures and represent distinct scattering processes, without attempting full vector solutions of Maxwell's equations in all cases. Idea to develop ability to invert models to identify unknown terrain depicted in polarimetric radar images. Describes models, major scattering characteristics predicted by models, and interpretation of characteristics in terms of dominant scattering mechanisms. Models predict realistic polarization signatures.

  17. Numerical Calculation of Interaction Between Plane Jet and Subsonic Flow

    Directory of Open Access Journals (Sweden)

    V. O. Moskalenko

    2016-01-01

    Full Text Available The paper makes numerical calculation of interaction between plane jet and subsonic flow. Its aim is to determine the jet trajectory, velocity profiles, distribution of pressure coefficient on the plate surface at different jet angles, namely ωj=45°; 90°; 105° and at low blowing strengths ( ≤1.5 as well as a to make comparison with the experimental data of other authors.To simulate a two-dimensional jet in the subsonic flow the software package “CAD SolidWorks Flow Simulation” has been used. Initially, the test task was solved with its calculation results compared with experimental ones [6.8] in order to improve the convergence; the size of the computational domain and a computational grid within the k-ε turbulence model were selected. As a result of the calculation, were identified and analysed the pressure values, jet trajectories, and velocity profiles. In the graphs the solid lines show calculation results, and dots represent experimental data.From the calculation results it is seen that, with increasing intensity of the reduced mass flow ¯q in the above range, the change of the jet pressure coefficient p¯ distribution behind a slotted nozzle is almost linear and significant. Before the nozzle, with increasing ¯q the pressure coefficient increases slightly.Analysis of results has shown that blowing of jets with ωj>90ω, provides a greater perturbation of the subsonic flow. Thus, the jet penetrates into the flow deeper, forms a dead region of the greater length, and more significantly redistributes the pressure coefficient on the surface of the plate.The calculation results are in good compliance with the experimental data both for the jet axis and for the pressure coefficient distribution on the plate surface. The research results can be used in the designing the jet control of aircrafts.

  18. The reflectance characteristics of snow covered surfaces

    Science.gov (United States)

    Batten, E. S.

    1979-01-01

    Data analysis techniques were developed to most efficiently use available satellite measurements to determine and understand components of the surface energy budget for ice and snow-covered areas. The emphasis is placed on identifying the important components of the heat budget related to snow surfaces, specifically the albedo and the energy consumed in the melting process. Ice and snow charts are prepared by NOAA from satellite observations which map areas into three relative reflectivity zones. Field measurements are analyzed of the reflectivity of an open snow field to assist in the interpretation of the NOAA reflectivity zones.

  19. Spatial characteristics of ocean surface waves

    Science.gov (United States)

    Gemmrich, Johannes; Thomson, Jim; Rogers, W. Erick; Pleskachevsky, Andrey; Lehner, Susanne

    2016-08-01

    The spatial variability of open ocean wave fields on scales of O (10km) is assessed from four different data sources: TerraSAR-X SAR imagery, four drifting SWIFT buoys, a moored waverider buoy, and WAVEWATCH III Ⓡ model runs. Two examples from the open north-east Pacific, comprising of a pure wind sea and a mixed sea with swell, are given. Wave parameters attained from observations have a natural variability, which decreases with increasing record length or acquisition area. The retrieval of dominant wave scales from point observations and model output are inherently different to dominant scales retrieved from spatial observations. This can lead to significant differences in the dominant steepness associated with a given wave field. These uncertainties have to be taken into account when models are assessed against observations or when new wave retrieval algorithms from spatial or temporal data are tested. However, there is evidence of abrupt changes in wave field characteristics that are larger than the expected methodological uncertainties.

  20. Surface pore tension and adsorption characteristics of polluted sediment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Most natural sediment particles have numerous pores and a complex surface texture which facilitates their adsorption of contaminants. Particle surface structure,therefore,is an important instrumental factor in the transport of contaminants,especially in water environments. This paper reports on the results of adsorption-desorption experiments to analyze polluted sediment surface pore tension characteristics performed on samples from the bottom of Guanting Reservoir. In our analysis,the Frenkel-Halsey-Hill(FHH) equation is applied to calculate the fractal dimensions of particles to quantify the surface roughness and pore tension characteristics. The results show that the surface fractal dimensions of sediment particle surfaces normally measure from 2.6 to 2.85. The volume of pores smaller than 10 nm changes significantly after being contaminated with pollutants and the fractal dimension decreases because the pores adsorb the contaminants.

  1. Wetting characteristics of 3-dimensional nanostructured fractal surfaces

    Science.gov (United States)

    Davis, Ethan; Liu, Ying; Jiang, Lijia; Lu, Yongfeng; Ndao, Sidy

    2017-01-01

    This article reports the fabrication and wetting characteristics of 3-dimensional nanostructured fractal surfaces (3DNFS). Three distinct 3DNFS surfaces, namely cubic, Romanesco broccoli, and sphereflake were fabricated using two-photon direct laser writing. Contact angle measurements were performed on the multiscale fractal surfaces to characterize their wetting properties. Average contact angles ranged from 66.8° for the smooth control surface to 0° for one of the fractal surfaces. The change in wetting behavior was attributed to modification of the interfacial surface properties due to the inclusion of 3-dimensional hierarchical fractal nanostructures. However, this behavior does not exactly obey existing surface wetting models in the literature. Potential applications for these types of surfaces in physical and biological sciences are also discussed.

  2. Super-hydrophobic characteristics of butterfly wing surface

    Institute of Scientific and Technical Information of China (English)

    CONG Qian; CHEN Guang-hua; FANG Yan; REN Lu-quan

    2004-01-01

    Many biological surface are hydrophobic because of their complicated composition and surface microstructure. Eleven species (four families) of butterflies were selected to study their micro-, nano-structure and super-hydrophobic characteristic by means of Confocal Light Microscopy, Scanning Electron Microscopy and Contact Angle Measurement. The contact angles of water droplets on the butterfly wing surface were consistently measured to be about 150° and 100° with and without the squamas, respectively. The dust on the surface can be easily cleaned by moving spherical droplets when the inclining angle is larger than 3°. It can be concluded that the butterfly wing surface possess a super-hydrophobic, water-repellent,self-cleaning, or "Lotus-effect" characteristic. The contact angle measurement of water droplets on the wing surface with and without the squamas showed that the water-repellent characteristic is a consequence of the microstructure of the squamas.Each water droplet (diameter 2 mm) can cover about 700 squamas with a size of 40 μm×80 μm of each squama. The regular riblets with a width of 1000 nm to 1500 nm are clearly observed on each single squama. Such nanostructure should play a very important role in their super-hydrophobic and self-cleaning characteristic.

  3. Littoral Subsonic Seismoacoustic Phenomena Ultrasonic Modeling

    Science.gov (United States)

    2016-06-07

    Littoral Subsonic Seismoacoustic Phenomena Ultrasonic Modeling Jacques R. Chamuel Sonoquest Advanced Ultrasonics Research P.O. Box 81153 Wellesley... variable water/air content, and benthic shelled animals leading to accurate acoustic modeling of littoral surficial layer and geophysical inversion...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Sonoquest Advanced Ultrasonics Research ,P.O. Box 81153,Wellesley Hills,MA,02481-0001 8

  4. Supersonic and subsonic measurements of mesospheric ionization.

    Science.gov (United States)

    Hale, L. C.; Nickell, L. C.; Kennedy, B.; Powell, T. A.

    1972-01-01

    An Arcas rocket-parachute system was used at night to compare supersonic and subsonic ionization measurements below 75 km. A hemispherical nose-tip probe was used on ascent and a parachute-borne blunt probe on descent to measure polar conductivities, which were due entirely to positive and negative ions. The velocity of the supersonic probe was Mach 2.5 at 50 km and 1.75 at 70 km; the blunt probe was subsonic below 71 km. Between 65 and 75 km the ratio of negative to positive conductivities (and thus of mobilities) determined by the blunt probe was about 1.2, and it approached 1 below this altitude range. The ratio obtained by the nose-tip probe varied from 1.5 at 75 km to .6 at 65 km, thus indicating a rapid variation of the effects of the shock wave on the sampled ions. The absolute values of positive conductivity measured subsonically and supersonically were essentially identical from 60 to 75 km, indicating that the sampled ions were unchanged by the shock. However, below 60 km the shock apparently 'broke up' the positive ions, as indicated by higher measured conductivities.

  5. Influence of shear velocity on frictional characteristics of rock surface

    Indian Academy of Sciences (India)

    T N Singh; A K Verma; Tanmay Kumar; Avi Dutt

    2011-02-01

    Understanding the fundamental issues related with the effect of shear velocity on frictional characteristics at the interface of rock surfaces is an important issue. In this paper, strain-rate dependence on friction is investigated in relation to sliding behaviour under normal load. The phenomenon of stick-slip of granite and shaly sandstone with a tribometer at constant rate of strain under normal loads was observed. Friction at the interface of the rock samples was developed by increasing shear strain at a constant rate by applying constant velocity using the tribometer. For shaly sandstone, state parameters ( and ) played a major role in determining the friction values and roughness of the contact surfaces as well. Higher values of for shaly sandstone may be attributed to the fact that its surface had a greater number of pronounced asperities. Rubbing between the surfaces does not mean that surface becomes smoother. This is because of variation of friction between surfaces.

  6. Effect of Surface Treatment on the Surface Characteristics of AISI 316L Stainless Steel

    Science.gov (United States)

    Trigwell, Steve; Selvaduray, Guna

    2005-01-01

    The ability of 316L stainless steel to maintain biocompatibility, which is dependent upon the surface characteristics, is critical to its effectiveness as an implant material. The surfaces of mechanically polished (MP), electropolished (EP) and plasma treated 316L stainless steel coupons were characterized by X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) for chemical composition, Atomic Force Microscopy for surface roughness, and contact angle measurements for critical surface tension. All surfaces had a Ni concentration that was significantly lower than the bulk concentration of -43%. The Cr content of the surface was increased significantly by electropolishing. The surface roughness was also improved significantly by electropolishing. Plasma treatment had the reverse effect - the surface Cr content was decreased. It was also found that the Cr and Fe in the surface exist in both the oxide and hydroxide states, with the ratios varying according to surface treatment.

  7. Zero Cycles on Certain Surfaces in Arbitrary Characteristic

    Indian Academy of Sciences (India)

    G V Ravindra

    2006-02-01

    Let be a field of arbitrary characteristic. Let be a singular surface defined over with multiple rational curve singularities and suppose that the Chow group of zero cycles of its normalisation $\\overline{S}$ is finite dimensional. We give numerical conditions under which the Chow group of zero cycles of is finite dimensional.

  8. Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

    Institute of Scientific and Technical Information of China (English)

    Makiko YONAMINE; Takanori USHIJIMA; Yoshiaki MIYAZATO; Mitsuharu MASUDA; Hiroshi KATANODA; Kazuyasu MATSUO

    2006-01-01

    In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation,and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves.The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.

  9. Characteristics of surface waves in anisotropic left-handed materials

    Institute of Scientific and Technical Information of China (English)

    Jiang Yong-Yuan; Shi Hong-Yan; Zhang Yong-Qiang; Hou Chun-Feng; Sun Xiu-Dong

    2007-01-01

    We report the coexistence of TE and TM surface modes in certain same frequency domain at the interface between one isotropic regular medium and another biaxially anistotropic left-handed medium. The conditions for the existence of TE and TM polarized surface waves in biaxially anisotropic left-handed materials are identified, respectively.The Poynting vector and the energy density associated with surface modes are calculated. Depending on the system parameters, either TE or TM surface modes can have the time averaged Poynting vector directed to or opposite to the mode phase velocity. It is seen that the characteristics of surface waves in biaxially anisotropic left-handed media are significantly different from that in isotropic left-handed media.

  10. Characteristics of the Surface-Intrinsic Josephson Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Li; XU Wei-wei; YE Su-li; GUO Da-yuan; YOU Li-xing; WU Pei-heng

    2006-01-01

    During the fabrication of intrinsic Josephson junctions (IJJs) with Bi2Sr2CaCu2O8+δ(BSCCO) single crystals,the superconductivity of the surface Cu-O layer is degraded because of a deposited metal film on top of the stack.Thus,the characteristics of the surface junction consisting of the surface Cu-O double layers remarkably differ from those of the junctions deep in the stack,which will be referred to as ordinary IJJs.The electrical transport characteristics of the surface junction,such as I-V,I'c-T,and R-T,show that the critical temperature T'c of the surface junction is always lower than that of ordinary IJJs,and that the change of its critical current I'c with temperature is different from that of ordinary IIJs.Furthermore,by shunting! the surface junction resistively,we are able to observe the AC Josephson effect at 3-mm waveband.

  11. Anatomical characteristics of the cerebral surface in bulimia nervosa.

    Science.gov (United States)

    Marsh, Rachel; Stefan, Mihaela; Bansal, Ravi; Hao, Xuejun; Walsh, B Timothy; Peterson, Bradley S

    2015-04-01

    The aim of this study was to examine morphometric features of the cerebral surface in adolescent and adult female subjects with bulimia nervosa (BN). Anatomical magnetic resonance images were acquired from 34 adolescent and adult female subjects with BN and 34 healthy age-matched control subjects. We compared the groups in the morphological characteristics of their cerebral surfaces while controlling for age and illness duration. Significant reductions of local volumes on the brain surface were detected in frontal and temporoparietal areas in the BN compared with control participants. Reductions in inferior frontal regions correlated inversely with symptom severity, age, and Stroop interference scores in the BN group. These findings suggest that local volumes of inferior frontal regions are smaller in individuals with BN compared with healthy individuals. These reductions along the cerebral surface might contribute to functional deficits in self-regulation and to the persistence of these deficits over development in BN. © 2014 Society of Biological Psychiatry.

  12. Surface characteristics of carbon fibers modified by direct oxyfluorination.

    Science.gov (United States)

    Seo, Min-Kang; Park, Soo-Jin

    2009-02-01

    The effect of oxyfluorinated conditions on the surface characteristics of carbon fibers was investigated. Infrared (IR) spectroscopy results indicated that the oxyfluorinated carbon fibers showed carboxyl/ester groups (CO) at 1632 cm(-1) and hydroxyl groups (OH) at 3450 cm(-1) and had a higher OH peak intensity than that of the fluorinated ones. X-ray photoelectron spectroscopy (XPS) results for the fibers also showed that oxyfluorination introduced a much higher oxygen concentration onto the fiber surfaces than fluorination with F(2) only. Additionally, contact-angle results showed that the surface was better wetted by following oxyfluorination and that the polarity of the surface was increased by increasing the oxyfluorination temperature.

  13. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants.

    Science.gov (United States)

    Sezin, M; Croharé, L; Ibañez, J C

    2016-01-01

    To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm(2) was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces..

  14. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    Science.gov (United States)

    Sezin, M.; Croharé, L.; Ibañez, J.C.

    2016-01-01

    Objective: To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Materials and Methods: Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. Results: The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm2 was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). Conclusion: The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces.. PMID:27335615

  15. Subsonic Mechanical Alignment of Irregular Grains

    CERN Document Server

    Lazarian, Alex

    2007-01-01

    We show that grains can be efficiently aligned by interacting with a subsonic gaseous flow. The alignment arises from grains having irregularities that scatter atoms with different efficiency in the right and left directions. The grains tend to align with long axes perpendicular to magnetic field, which corresponds to Davis-Greenstein predictions, but does not involve magnetic field. For rather conservative factors characterizing the grain helicity and scattering efficiency of impinging atoms, the alignment of helical grains is much more efficient than the Gold-type alignment processes.

  16. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Subsonic radiation waves in neon

    Science.gov (United States)

    Loseva, T. V.; Nemchinov, I. V.

    1989-02-01

    Numerical methods are used to investigate the propagation of plane subsonic radiation waves in neon from an obstacle in the direction opposite to the incident radiation of Nd and CO2 lasers. An analysis is made of the influence of the power density of the incident radiation (in the range 10-100 MW/cm2) and of the initial density of neon (beginning from the normal valuep ρ0 up to 10ρ0) on the various characteristics of subsonic radiation waves. It is shown that waves traveling in neon can provide an effective source of radiation with a continuous spectrum and an efficiency of ~ 12-27% in the ultraviolet range (with a characteristic photon energy ~ 5-10 eV).

  17. Reflection characteristics of a composite planar AMC surface

    Directory of Open Access Journals (Sweden)

    Ruey-Bing Hwang

    2012-03-01

    Full Text Available This study investigates the reflection characteristics of a composite Artificial Magnetic Conductor (AMC surface consisting of multiple orthogonal gradient AMC surfaces arranged in a two-dimensional periodic pattern. The gradient AMC surface in this study consists of square metal patches of variable size printed on a grounded dielectric substrate. Due to the orthogonal placement of the gradient AMC surface, the incident energy of a plane wave normally incident on the composite AMC surface will be reflected into four major lobes away from the impinging direction. To achieve a systematical design, a simple formula based on array antenna theory was developed to determine the reflection pattern of the gradient AMC surface illuminated by a normal incident plane wave. A time-domain full-wave simulation was also carried out to calculate the electromagnetic fields in the structure and the far-field patterns. The scattering patterns of the structure were measured in an electromagnetic anechoic chamber. Results confirm the design principle and procedures in this research. Since such a composite AMC surface can be easily fabricated using the standard printed circuit board technique without via-hole process, it may have potential applications in beam-steering and radar cross section reduction.

  18. Effect of winglets on a first-generation jet transport wing. 6: Stability characteristics for a full-span model at subsonic speeds. [conducted in Langley 8 foot transonic pressure tunnel

    Science.gov (United States)

    Flechner, S. G.

    1979-01-01

    A wind tunnel investigation to identify changes in stability and control characteristics of a model KC-135A due to the addition of winglets is presented. Static longitudinal and lateral-directional aerodynamic characteristics were determined for the model with and without winglets. Variations in the aerodynamic characteristics at various Mach numbers, angles of attack, and angles of slidslip are discussed. The effect of the winglets on the drag and lift coefficients are evaluated and the low speed and high speed characteristics of the model are reported.

  19. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    Science.gov (United States)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-07-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  20. Reflection properties of road surfaces. Contribution to OECD Scientific Expert Group AC4 on Road Surface Characteristics.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1983-01-01

    Photometric characteristics of road surfaces are dealt with. Representation of reflection properties in public lighting; quality criteria of road lighting installations; classification of road surfaces; the relation between reflection characteristics and other properties of road pavements in public

  1. Reflection properties of road surfaces. Contribution to OECD Scientific Expert Group AC4 on Road Surface Characteristics.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1983-01-01

    Photometric characteristics of road surfaces are dealt with. Representation of reflection properties in public lighting; quality criteria of road lighting installations; classification of road surfaces; the relation between reflection characteristics and other properties of road pavements in public

  2. Rotating Stall and Stall-Controlled Performance of a Single Stage Subsonic Axial Compressor

    Institute of Scientific and Technical Information of China (English)

    Eisuke OUTA

    2006-01-01

    Activities by various authors on aerodynamics and control dynamics of rotating stall in axial compressor are first traced. Then, a process of stall cell evolution in a subsonic stage is discussed based on a 2-D CFD. A few numbers of vortices grow ahead of the rotor accumulating vorticity ejected from lightly stalled blades, and eventually organize a cell of circumferentially aligned huge vortices, which merge and recess repeatedly during the rotation. Such stall disturbance is intensified on trailing side of a circumferential inlet distortion and decays on the leading side. Considering these features, a new algorithm for stall warning is developed based on a correlation between pressure waveforms at each passing of a fixed blade. A remarkable change in the correlation level at near-stall provides a warning signal prior to the stall onset with sufficiently large time margin. This scheme is applied to achieve rotating stall prevention by actuating flaps installed on the hub. The last issue is on characteristics of forward swept blade which has much increased throttle margin with decreased tip loss. A 3-D computation shows that a secondary vortex generated in suction surface mid span interacts to reduce the tip leakage vortex that initiates the stall.

  3. Dynamic corona characteristics of water droplets on charged conductor surface

    Science.gov (United States)

    Xu, Pengfei; Zhang, Bo; Wang, Zezhong; Chen, Shuiming; He, Jinliang

    2017-03-01

    The formation of the Taylor cone of a water droplet on the surface of the conductor in a line-ground electrode system is captured using a high-speed camera, while the corona current is synchronously measured using a current measurement system. Repeated Taylor cone deformation is observed, yielding regular groupings of corona current pulses. The underlying mechanism of this deformation is studied and the correlation between corona discharge characteristics and cone deformation is investigated. Depending on the applied voltage and rate of water supply, the Taylor cone may be stable or unstable and has a significant influence on the characteristics of the corona currents. If the rate of water supply is large enough, the Taylor cone tends to be unstable and generates corona-current pulses of numerous induced current pulses with low amplitudes. In consequence, this difference suggests that large rainfall results in simultaneously lower radio interference and higher corona loss.

  4. Full polarization scattering characteristics of sea fractal surface

    Institute of Scientific and Technical Information of China (English)

    Xie Tao; He Yijun; Nan Chengfeng

    2006-01-01

    In the conventional single polarization SAR system, only the scattering information of HH polarization or VV polarization can be obtained. Only co-polarizaion scattering cases are considered and cross-polarizaiton (HV and VH polarization) scattering cases are neglected. Therefore, much important information must be lost. Research on full polarization SAR system is an important approach to extract more useful information from SAR imaging. In this paper, the authors derived the full polarization scattering coefficients of 2-D sea fractal surface and simulated the radar cross section (RCS) of different polarizations. They also gave the exact theoretical explanations of the fully polarization scattering characteristics of sea fractal surface, and confirmed that the depolarization can be neglected. The result is the basis of the full SAR system design and SAR imaging.

  5. Magnetic Characteristics of Surface Sediments of Liaodong Bay, China

    Institute of Scientific and Technical Information of China (English)

    WANG ShuangP; WANG Yonghong; LIU Jian; YU Yiyong

    2015-01-01

    Analysis of magnetic properties of marine surface sediments has been gradually proved to be one of the effective means for researching the source of marine sediments. In this paper, samples from 39 sites in Liaodong Bay were collected to analyze the magnetic characteristics of the surface sediments. Magnetic study indicated that the surface sediments of the Liaodong Bay are char-acterized by magnetite. In the middle and eastern part and the southwest corner of the Bay, the main magnetic grains were coarse multi-domain and pseudo-single-domain particles, while in other areas single-domain and pseudo-single-domain particles constitute the majority. Based on grain size and environmental magnetism data, the content of magnetic minerals has a positive correlation with the hydrodynamic environment when the magnetic mineral domain is finer. However, the content of magnetic minerals is in a complex relationship with the hydrodynamic environment in the coarse magnetic domain of magnetic minerals found in central Liaodong Bay and places outside the Fuzhou Bay, implying that the strong hydrodynamic environment accelerates the sedimentation of coarse magnetic minerals. Based on geographic pattern of magnetic properties, it can be inferred that the main provenance of the surface sediments of the Liaodong Bay is the surrounding rivers, and the comparative analysis indicates that Yellow River substances maybe also exist in the bay.

  6. Starvation-induced effects on bacterial surface characteristics.

    Science.gov (United States)

    Kjelleberg, S; Hermansson, M

    1984-09-01

    Changes in bacterial surface hydrophobicity, charge, and degree of irreversible binding to glass surfaces of seven marine isolates were followed during starvation. The degree of hydrophobicity was measured by hydrophobic interaction chromatography and by two-phase separation in a hexadecane-water system, whereas changes in charge were measured by electrostatic interaction chromatography. All isolates underwent the starvation-induced responses of fragmentation, which is defined as division without growth, and continuous size reduction, which results in populations with increased numbers of smaller cells. The latter process was also responsible for a significant proportion of the total drop in cell volume; this was observed by noting the biovolume (the average cell multiplied by the number of bacteria) of a population after various times of starvation. Four strains exhibited increases in both hydrophobicity and irreversible binding, initiated after different starvation times. The most hydrophilic and most hydrophobic isolates both showed a small increase in the degree of irreversible binding after only 5 h, followed by a small decrease after 22 h. Their hydrophobicity remained constant, however, throughout the entire starvation period. On the other hand, one strain, EF190, increased its hydrophobicity after 5 h of starvation, although the degree of irreversible binding remained constant. Charge effects could not be generally related to the increase in irreversible binding. Scanning electron micrographs showed a large increase in surface roughness throughout the starvation period for all strains that showed marked changes in physicochemical characteristics.

  7. Supersonic—Subsonic Transition in Relatively Narrow Channels

    Institute of Scientific and Technical Information of China (English)

    RudlfDvorak

    2000-01-01

    The flow structure in relatively narrow channels has a strong three-dimensional character with complex flow phenomena.Including regions of localized spearation.various vortical structures.etc.,all of which have to be considered when dealing with the problem of supersonic-subsonic transition.In this paper only the following three problems are considered:1.the effect of channel width on transition form supersonic to subsonic velocities.2.transition from supersonic to subsonic velocities in a system of shock waves-pseudoshock wave.3.transition from subsonic to supersonic velocities in a critical cross section at the end of a duct with fully developed turbulent channel flow.Problems connectewd with vortical structures and flow separation were discussed by the same author elsewhere (see References).

  8. Stability and Existence of Multidimensional Subsonic Phase Transitions

    Institute of Scientific and Technical Information of China (English)

    Ya-Guang Wang; Zhouping Xin

    2003-01-01

    The purpose of this paper is to prove the uniform stability of multidimensional subsonic phase transitions satisfying the viscosity-capillarity criterion in a van der Waals fluid, and further to establish the local existence of phase transition solutions.

  9. Light, shadows and surface characteristics: the multispectral Portable Light Dome

    Science.gov (United States)

    Watteeuw, Lieve; Hameeuw, Hendrik; Vandermeulen, Bruno; Van der Perre, Athena; Boschloos, Vanessa; Delvaux, Luc; Proesmans, Marc; Van Bos, Marina; Van Gool, Luc

    2016-11-01

    A multispectral, multidirectional, portable and dome-shaped acquisition system is developed within the framework of the research projects RICH (KU Leuven) and EES (RMAH, Brussels) in collaboration with the ESAT-VISICS research group (KU Leuven). The multispectral Portable Light Dome (MS PLD) consists of a hemispherical structure, an overhead camera and LEDs emitting in five parts of the electromagnetic spectrum regularly covering the dome's inside surface. With the associated software solution, virtual relighting and enhancements can be applied in a real-time, interactive manner. The system extracts genuine 3D and shading information based on a photometric stereo algorithm. This innovative approach allows for instantaneous alternations between the computations in the infrared, red, green, blue and ultraviolet spectra. The MS PLD system has been tested for research ranging from medieval manuscript illuminations to ancient Egyptian artefacts. Preliminary results have shown that it documents and measures the 3D surface structure of objects, re-visualises underdrawings, faded pigments and inscriptions, and examines the MS results in combination with the actual relief characteristics of the physical object. Newly developed features are reflection maps and histograms, analytic visualisations of the reflection properties of all separate LEDs or selected areas. In its capacity as imaging technology, the system acts as a tool for the analysis of surface materials (e.g. identification of blue pigments, gold and metallic surfaces). Besides offering support in answering questions of attribution and monitoring changes and decay of materials, the PLD also contributes to the identification of materials, all essential factors when making decisions in the conservation protocol.

  10. Characteristics of surface sterilization using electron cyclotron resonance plasma

    Science.gov (United States)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2016-07-01

    The characteristics of surface sterilization using electron cyclotron resonance (ECR) plasma were investigated. High-energy electrons and oxygen radicals were observed in the ECR zone using electric probe and optical emission spectroscopic methods. A biological indicator (BI), Geobacillus stearothermophilus, containing 1 × 106 spores was sterilized in 120 s by exposure to oxygen discharges while maintaining a temperature of approximately 55 °C at the BI installation position. Oxygen radicals and high-energy electrons were found to be the sterilizing species in the ECR region. It was demonstrated that the ECR plasma could be produced in narrow tubes with an inner diameter of 5 mm. Moreover, sterilization tests confirmed that the spores present inside the narrow tube were successfully inactivated by ECR plasma irradiation.

  11. A MIXED LUBRICATION MODEL MODIFIED BY SURFACES' FRACTAL CHARACTERISTICS

    Institute of Scientific and Technical Information of China (English)

    孟凡明; 张有云

    2003-01-01

    Fractal characteristics are introduced into solving lubrication problems. Based on the analysis of the relationship between roughness and engineering surfaces' fractal characteristics and by introducing fractal parameters into the mixed lubrication equation, the relationship between flow factors and fractal dimensions is analyzed. The results show that the pressure flow factors' values increase, while the shear flow factor decreases, with the increasing length to width ratio of a representative asperity γ at the same fractal dimension. It can be also found that these factors experience more irregular and significant variations and show the higher resolution and the local optimal and the worst fractal dimensions, by a fractal dimension D, compared with the oil film thickness to roughness ratio h/Rq. As an example of application of the model to solve the lubrication of the piston skirt in an engine, the frictional force and the load capacity of the oil film in a cylinder were analyzed. The results reveal that the oil film frictional force and the load capacity fluctuate with increasing fractal dimension, showing big values at the small D and smaller ones and slightly variable in the range of bigger one, at the same crank angle.

  12. Surface Characteristics of Green Island Wakes from Satellite Imagery

    Science.gov (United States)

    Cheng, Kai-Ho; Hsu, Po-Chun; Ho, Chung-Ru

    2017-04-01

    Characteristics of an island wake induced by the Kuroshio Current flows pass by Green Island, a small island 40 km off southeast of Taiwan is investigated by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery. The MODIS sea surface temperature (SST) and chlorophyll-a (chl-a) imagery is produced at 250-meter resolution from 2014 to 2015 using the SeaDAS software package which is developed by the National Aeronautics and Space Administration. The wake occurrence is 59% observed from SST images during the data span. The average cooling area is 190 km2, but the area is significantly changed with wind directions. The wake area is increased during southerly winds and is reduced during northerly winds. Besides, the average cooling SST was about 2.1 oC between the front and rear island. Comparing the temperature difference between the wake and its left side, the difference is 1.96 oC. In addition, the wakes have 1 3 times higher than normal in chlorophyll concentration. The results indicate the island mass effect makes the surface water of Green island wake colder and chl-a higher.

  13. Relationship Between Iron Oxides and Surface Charge Characteristics in Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; WANGWEI-JUN

    1991-01-01

    The relationship between iron oxides and surface charge characteristics in variable charge soils (latosol and red earth) was studied in following three ways.(1)Remove free iron oxides (Fed) and amorphous iron oxides (Feo) from the soils with sodium dithionite and acid ammonium oxalate solution respectively.(2) Add 2% glucose (on the basis of air-dry soil weight) to soils and incubate under submerged condition to activate iron oxides,and then the mixtures are dehydrated and air-dried to age iron oxides.(3) Precipitate various crystalline forms of iron oxides onto kaolinite.The results showed that free iron oxides (Fed) were the chief carrier of variable positive charges.Of which crystalline iron oxides (Fed-Feo) presented mainly as discrete particles in the soils and could only play a role of the carrier of positive charges,and did little influence on negative charges.Whereas the amorphous iron oxides (Feo),which presented mainly fas a coating with a large specific surface area,not only had positive charges,but also blocked the negative charge sites in soils.Submerged incubation activated iron oxides in the soils,and increased the amount of amorphous iron oxides and the degree of activation of iron oxide,which resulted in the increase of positive and negative charges of soils.Dehydration and air-dry aged iron oxides in soils and decreased the amount of amorphous iron oxides and the degree of activation of iron oxide,and also led to the decrease of positive and negative charges.Both the submerged incubation and the dehydration and air-dry had no significant influence on net charges.Precipitation of iron oxides onto kaolinite markedly increased positive charges and decreased negative charges.Amorphous iron oxide having a larger surface area contributed more positive charge sites and blocked more negative charge sites in kaolinite than crystalline goethite.

  14. Effects of Surface Treatment of Activated Carbon on Its Surface and Cr(VI) Adsorption Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Park, Soo Jin; Jang, Yu Sin [Advanced Materials Division., Korea Research Institute of Chimical Technology, Taejon (Korea)

    2001-04-01

    In this work, the effect of surface treatments on activated carbons (ACs) has been studied in the context of gas and liquid adsorption behaviors. The chemical solutions used in this experiment were 35% sodium hydroxide, and these were used for the acidic and basic treatments, respectively. The surface properties have been determined by pH, acid-base values, and FT-IR. The adsorption isotherms of Cr(VI) ion on activated carbons have been studied with the 5 mg/l concentration at ambient temperature. N{sub 2} adsorption isotherm characteristics, which include the specific surface area, micro pore volume, and microporosity, were determined by BET and Boer's-plot methods. In case of the acidic treatment of activated carbons, it was observed that the adsorption of Cr(VI) ion was more effective due to the increase acid value (or acidic functional group) of activated carbon surfaces. However, the basic treatment on activated carbons was caused no significant effects, probably due to the decreased specific surface area and total pore volume. 27 refs., 7 figs., 4 tabs.

  15. The effect of surface tension and association on the homogeneous binary spontaneous condensation in a non-steady state subsonic flow of steam. Zum Einfluss der Oberflaechenspannung und Assoziation auf die homogene binaere Spontankondensation in einer instationaeren Unterschalldampfstroemung

    Energy Technology Data Exchange (ETDEWEB)

    Spiegel, G.H.

    1987-05-21

    This work deals with the spontaneous homogneous condensation process of diluted binary steam, which is increasing in importance in many technical and natural processes. In a deep and generally valid theoretical investigation, the introductory cycle of phase change (the binary nucleus formation) and the subsequent process of growth are comprehensively analysed. Similar serious problems in theoretical prediction are found in binary systems with a surface active component. Particularly when these are present in diluted form, the macroscopic surface tension leads to quite insufficient theoretical results.This fact also found by other workers is due to a changed molecule distribution compared to the macroscopic case in the resulting liquid phase during transition to the micro-clusters important in nucleus formation. As both binary solutions examined in this work belong to this category, two recently proposed theoretical models for 'correcting' the surface tension are considered - the adsorption and the mono-layer model. However, it was found that both processes can only be used to a limited extent for the interesting speeds of cooling. It is demonstrated by a comparative analysis carried out for the first time in such detail that only the proposal resulting from this work to use the purely dynamic surface tension has general applicability. (orig./GL).

  16. Effect of mixing technique on surface characteristics of impression materials.

    Science.gov (United States)

    Lepe, X; Johnson, G H; Berg, J C; Aw, T C

    1998-05-01

    Previous studies have shown a relationship between the disinfection process, wettability, and mass change of impression materials. Hand-mixed high viscosity impression materials usually result in a material with numerous voids, which contribute to surface roughness and affect the surface characteristics of the material. This study evaluated the effect of mixing technique on advancing contact angle, receding contact angle, imbibition, and mass loss of various high and low viscosity polyether and polyvinyl siloxane materials. The null hypothesis tested was no differences exist between the different mixing systems. The Wilhelmy technique was used for deriving wetting properties of the materials used (Impregum F and Penta, Permadyne Syringe, Garant and Penta, Dimension Penta and Garant L, Aquasil). Conditions included no disinfection (0 hours) and 1, 5, and 18 hours of immersion disinfection in a full-strength solution of 2% acid glutaraldehyde disinfectant (Banicide). Weight changes before and after disinfection were measured to detect weight loss or mass increase over time. Weight loss in air was also measured to detect mass loss. Data were analyzed with a one-way analysis of variance at alpha = 0.05. All materials displayed some degree of imbibition of the disinfectant and experienced mass loss with polymerization, except the light viscosity polyvinyl that gained 0.18% at 5 hours. No significant differences were found in wettability among the polyether materials after 1 hour of disinfection. Less imbibition was observed for high viscosity mechanically mixed materials compared with the hand-mixed materials for both polyether and polyvinyl siloxane at 1-hour disinfection time. Polyether materials were more wettable than polyvinyl. Imbibition of high viscosity polyether and polyvinyl materials after 1 and 18 hours of disinfection were affected by the mixing system used.

  17. [Backscattering Characteristics of Machining Surfaces and Retrieval of Surface Multi-Parameters].

    Science.gov (United States)

    Tao, Hui-rong; Zhang, Fu-min; Qu, Xing-hua

    2015-07-01

    For no cooperation target laser ranging, the backscattering properties of the long-range and real machined surfaces are uncertain which seriously affect the ranging accuracy. It is an important bottleneck restricting the development of no cooperation ranging technology. In this paper, the backscattering characteristics of three typical machining surfaces (vertidal milling processing method, horizontal milling processing method and plain grinding processing method) under the infrared laser irradiation with 1550 nm were measured. The relation between the surface nachining texture, incident azimuth, roughness and the backscattering distribution were analyzed and the reasons for different processing methods specific backscattering field formed were explored. The experimental results show that the distribution of backscattering spectra is greatly affected by the machined processing methods. Incident angle and roughness have regularity effect on the actual rough surface of each mode. To be able to get enough backscattering, knowing the surface texture direction and the roughness of machined metal is essential for the optimization of the non-contact measurement program in industry. On this basis, a method based on an artificial neural network (ANN) and genetic algorithm (GA), is proposed to retrieve the surface multi-parameters of the machined metal. The generalized regression neural network (GRNN) was investigated and used in this application for the backscattering modeling. A genetic algorithm was used to retrieve the multi-parameters of incident azimuth angle, roughness and processing methods of machined metal sur face. Another processing method of sample (planer processing method) was used to validate data. The final results demonstrated that the method presented was efficient in parameters retrieval tasks. This model can accurately distinguish processing methods and the relative error of incident azimuth and roughness is 1.21% and 1.03%, respectively. The inversion

  18. Aeroelasticity Benchmark Assessment: Subsonic Fixed Wing Program

    Science.gov (United States)

    Florance, Jennifer P.; Chwalowski, Pawel; Wieseman, Carol D.

    2010-01-01

    Aeroelasticity Branch will examine other experimental efforts within the Subsonic Fixed Wing (SFW) program (such as testing of the NASA Common Research Model (CRM)) and other NASA programs and assess aeroelasticity issues and research topics.

  19. Preliminary measurements of velocity, density and total temperature fluctuations in compressible subsonic flow

    Science.gov (United States)

    Stainback, P. C.; Johnson, C. B.; Basnett, C. B.

    1983-01-01

    The heat transfer characteristics of a three-wire hot-wire probe operated with a constant temperature anemometer were investigated in the subsonic compressible flow regime. The sensitivity coefficients, with respect to velocity, density and total temperature, were measured and the results were used to calculate the velocity, density, and total temperature fluctuations in the test section of the Langley 0.3-m Transonic Cryogenic Tunnel (TCT). These results were extended to give estimates for fluctuations due to vorticity, sound, and entropy. In addition, attempts were made to determine the major source of disturbances in the 0.3-m TCT.

  20. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    Energy Technology Data Exchange (ETDEWEB)

    Madooglu, K.; Karagozian, A.R.

    1989-01-01

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill's spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet's effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  1. Burning of a spherical fuel droplet in a uniform subsonic flowfield

    Energy Technology Data Exchange (ETDEWEB)

    Madooglu, K.; Karagozian, A.R.

    1989-12-31

    An analytical/numerical model is described for the evaporation and burning of a spherical fuel droplet in a subsonic crossflow. The external gaseous flowfield is represented using an approximate compressible potential solution, while the internal flowfield of the droplet is represented by the classical Hill`s spherical vortex. This allows numerical solution for the external boundary layer and diffusion flame characteristics to be made, from which the droplet`s effective drag coefficient, rate of mass loss, size, and flame shape are determined. Comparison with experimental data indicate good agreement, and thus the potential for such simplified models in performing parametric studies.

  2. [INVITED] Laser treatment of Inconel 718 alloy and surface characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.; Al-Aqeeli, N.; Karatas, C.

    2016-04-01

    Laser surface texturing of Inconel 718 alloy is carried out under the high pressure nitrogen assisting gas. The combination of evaporation and melting at the irradiated surface is achieved by controlling the laser scanning speed and the laser output power. Morphological and metallurgical changes in the treated surface are analyzed using the analytical tools including optical, electron scanning, and atomic force microscopes, energy dispersive spectroscopy, and X-ray diffraction. Microhardnes and friction coefficient of the laser treated surface are measured. Residual stress formed in the surface region is determined from the X-ray diffraction data. Surface hydrophobicity of the laser treated layer is assessed incorporating the sessile drop method. It is found that laser treated surface is free from large size asperities including cracks and the voids. Surface microhardness increases significantly after the laser treatment process, which is attributed to the dense layer formation at the surface under the high cooling rates, dissolution of Laves phase in the surface region, and formation of nitride species at the surface. Residual stress formed is compressive in the laser treated surface and friction coefficient reduces at the surface after the laser treatment process. The combination of evaporation and melting at the irradiated surface results in surface texture composes of micro/nano-poles and pillars, which enhance the surface hydrophobicity.

  3. A multiobjective shape optimization study for a subsonic submerged inlet

    Science.gov (United States)

    Taskinoglu, Ezgi S.

    The purpose of the present work is to summarize the findings of a multiobjective shape optimization study conducted for a subsonic submerged air vehicle inlet. The objective functions of the optimization problem are distortion and swirl indices defined by the distribution of flow parameters over the exit cross-section of the inlet. The geometry alteration is performed by placing a protrusion in the shape of a fin on the baseline inlet surface. Thus, the design variables of the optimization problem are chosen to be the geometrical parameters defining the fin protrusion; namely fin height, length and incidence angle. The Trade Off (also known as epsilon-constraint) method is employed for finding the Pareto optimal set formed by the nondominated solutions of the feasible design space. Since the flow domain solution is required for every step along the line search, an automated optimization loop is constructed by integrating the optimizer with a surface modeler, a mesh generator and a flow solver through which the flow parameters over the compressor face are computed. In addition, the trade study for fin protrusion, the analyses and the comparison of the baseline and Pareto optimal solutions are presented and observations concerning grid resolution and convergence behaviour are discussed. The results display an irregular and discontinuous Pareto optimal set. Optimum inlet designs are scattered in two regions from which one representative inlet design is chosen and analyzed. As a result, it is concluded that an inlet designer has two options within the framework of this optimization study: an inlet design with high swirl but low distortion or an inlet design with low swirl but higher distortion.

  4. Subsonic loads on wings having sharp leading edges and tips

    Science.gov (United States)

    Kandil, O. A.; Mook, D. T.; Nayfeh, A. H.

    1976-01-01

    A vortex-lattice method for predicting the aerodynamics of wings having separation at the sharp edges in incompressible flows is extended to compressible subsonic flows using a modified Prandtl-Glauert transformation. Numerical results showing the effect of freestream Mach number on the aerodynamic coefficients are compared with available experimental data for several planforms. It is shown that the proposed method is suitable for predicting the aerodynamic loads on low-aspect wings at moderate angles of attack for high subsonic freestream Mach number. The method is limited to angles of attack up to 12 deg for high subsonic freestream Mach number and to angles of attack up to 20 deg for Mach number not exceeding 0.5.

  5. Development of a shock noise prediction code for high-speed helicopters - The subsonically moving shock

    Science.gov (United States)

    Tadghighi, H.; Holz, R.; Farassat, F.; Lee, Yung-Jang

    1991-01-01

    A previously defined airfoil subsonic shock-noise prediction formula whose result depends on a mapping of the time-dependent shock surface to a time-independent computational domain is presently coded and incorporated in the NASA-Langley rotor-noise prediction code, WOPWOP. The structure and algorithms used in the shock-noise prediction code are presented; special care has been taken to reduce computation time while maintaining accuracy. Numerical examples of shock-noise prediction are presented for hover and forward flight. It is confirmed that shock noise is an important component of the quadrupole source.

  6. Overview of the Langley subsonic research effort on SCR configuration

    Science.gov (United States)

    Coe, P. L., Jr.; Thomas, J. D.; Huffman, J. K.; Weston, R. P.; Schoonover, W. E., Jr.; Gentry, C. L., Jr.

    1980-01-01

    Recent advances achieved in the subsonic aerodynamics of low aspect ratio, highly swept wing designs are summarized. The most significant of these advances was the development of leading edge deflection concepts which effectively reduce leading edge flow separation. The improved flow attachment results in substantial improvements in low speed performance, significant delay of longitudinal pitch up, increased trailing edge flap effectiveness, and increased lateral control capability. Various additional theoretical and/or experimental studies are considered which, in conjunction with the leading edge deflection studies, form the basis for future subsonic research effort.

  7. Characteristics of meter-scale surface electrical discharge propagating along water surface at atmospheric pressure

    Science.gov (United States)

    Hoffer, Petr; Sugiyama, Yuki; Hosseini, S. Hamid R.; Akiyama, Hidenori; Lukes, Petr; Akiyama, Masahiro

    2016-10-01

    This paper reports physical characteristics of water surface discharges. Discharges were produced by metal needle-to-water surface geometry, with the needle electrode driven by 47 kV (FWHM) positive voltage pulses of 2 µs duration. Propagation of discharges along the water surface was confined between glass plates with 2 mm separation. This allowed generation of highly reproducible 634 mm-long plasma filaments. Experiments were performed using different atmospheres: air, N2, and O2, each at atmospheric pressure. Time- and spatially-resolved spectroscopic measurements revealed that early spectra of discharges in air and nitrogen atmospheres were dominated by N2 2nd positive system. N2 radiation disappeared after approx. 150 ns, replaced by emissions from atomic hydrogen. Spectra of discharges in O2 atmosphere were dominated by emissions from atomic oxygen. Time- and spatially-resolved emission spectra were used to determine temperatures in plasma. Atomic hydrogen emissions showed excitation temperature of discharges in air to be about 2  ×  104 K. Electron number densities determined by Stark broadening of the hydrogen H β line reached a maximum value of ~1018 cm-3 just after plasma initiation. Electron number densities and temperatures depended only slightly on distance from needle electrode, indicating formation of high conductivity leader channels. Direct observation of discharges by high speed camera showed that the average leader head propagation speed was 412 km · s-1, which is substantially higher value than that observed in experiments with shorter streamers driven by lower voltages.

  8. Interface Characteristics Between Colloidal Gold and Kaolinite Surface by XPS

    Institute of Scientific and Technical Information of China (English)

    HONG Hanlie; TIE Liyun; BIAN Qiujuan; ZHOU Yong

    2006-01-01

    The distribution of gold colloids in kaolinite and the interaction between gold and kaolinite surface were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). There is strong interaction between the gold particles and the edge surfaces of kaolinite,in low pH solution,the edge surface of kaolinite is positively charged and electrostatic attractive force between colloide gold particles and the positive edge surface of kaolinite would facilitate the adsorption of colloidal gold particles onto the suface. TEM observation shows that the aggregate morphology of gold particles was dominated by particle-particle interaction and gold particles were adsorbed on the edge surface of kaolinite crystals, resulting from the electrostatic attractive force between colloidal gold particles and the positive surfaces of kaolinite. XPS data show that in Au4f electron spectra there are four energy peaks related to gold, 83.8 eV, 85.7 eV, 87.5 eV, and 89.4 eV, respectively, which suggests that in chemical states there are metallic gold and Au bonded to O, similar to the form of Au2O3, and composite Au2O3 is formed between the edge surface of kaolinite and colloidal gold surface.

  9. Characteristics of surface plasmon coupled quantum well infrared photodetectors

    Science.gov (United States)

    Hsu, Wei-Cheng; Ling, Hong-Shi; Wang, Shiang-Yu; Lee, Chien-Ping

    2017-06-01

    Quantum Well Infrared Photodetectors (QWIPs) with different structures were characterized for the study of surface plasmon wave coupling. Detailed comparisons between surface plasmon coupled and etched grating coupled devices were investigated. A bias dependence for the enhancement of the responsivity of surface plasmon coupled devices was found, especially for the samples with non-uniform quantum wells. The non-uniform QWIPs with surface plasmon coupling showed an asymmetric enhancement with respect to the bias directions. Stronger enhancements were shown under the biases when a higher effective electric field region is close to the collector. The change of the photocarrier escape probability due to the narrow coupling bandwidth of the surface plasmon wave is attributed to this unexpected bias dependence.

  10. SPHYNX: SPH hydrocode for subsonic hydrodynamical instabilities and strong shocks

    Science.gov (United States)

    Cabezon, Ruben M.; Garcia-Senz, Domingo

    2017-09-01

    SPHYNX addresses subsonic hydrodynamical instabilities and strong shocks; it is Newtonian, grounded on the Euler-Lagrange formulation of the smoothed-particle hydrodynamics technique, and density based. SPHYNX uses an integral approach for estimating gradients, a flexible family of interpolators to suppress pairing instability, and incorporates volume elements to provides better partition of the unity.

  11. The structure of subsonic air wakes behind a flat plate

    Energy Technology Data Exchange (ETDEWEB)

    Barreras, F.; Dopazo, C. [Centro Politecnico Superior de Ingenieros Area de Mecanica de Fluidos, Zaragoza (Spain); Lozano, A.; Yates, A.J. [LITEC/CSIC, Maria de Luna 3 E-50015-Zaragoza (Spain)

    1999-04-01

    Acetone vapor planar laser-induced fluorescence has been used to visualize the structure of a subsonic air wake behind a flat plate. Longitudinal and transversal wavelengths have been directly measured from the acquired images. The ratio between them has been calculated to be 2/5. (orig.) With 3 figs., 1 tab., 10 refs.

  12. Local scaling characteristics of Antarctic surface layer turbulence

    Directory of Open Access Journals (Sweden)

    S. Basu

    2010-03-01

    Full Text Available Over the past years, several studies have validated Nieuwstadt's local scaling hypothesis by utilizing turbulence observations from the mid-latitude, nocturnal stable boundary layers. In this work, we probe into the local scaling characteristics of polar, long-lived stable boundary layers by analyzing turbulence data from the South Pole region of the Antarctic Plateau.

  13. Characteristics of modified martensitic stainless steel surfaces under tribocorrosion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Rozing, Goran [Osijek Univ. (Croatia). Chair of Mechanical Engineering; Marusic, Vlatko [Osijek Univ. (Croatia). Dept. of Engineering Materials; Alar, Vesna [Zagreb Univ. (Croatia). Dept. Materials

    2017-04-01

    Stainless steel samples were tested in the laboratory and under real conditions of tribocorrosion wear. Electrochemical tests were also carried out to verify the corrosion resistance of modified steel surfaces. Metallographic analysis and hardness testing were conducted on stainless steel samples X20Cr13 and X17CrNi16 2. The possibilities of applications of modified surfaces of the selected steels were investigated by testing the samples under real wear conditions. The results have shown that the induction hardened and subsequently nitrided martensitic steels achieved an average wear resistance of up to three orders of magnitude higher as compared to the delivered condition.

  14. Wind Characteristics of Coastal and Inland Surface Flows

    Science.gov (United States)

    Subramanian, Chelakara; Lazarus, Steven; Jin, Tetsuya

    2015-11-01

    Lidar measurements of the winds in the surface layer (up to 80 m) inland and near the beach are studied to better characterize the velocity profile and the effect of roughness. Mean and root-mean-squared profiles of horizontal and vertical wind components are analyzed. The effects of variable time (18, 60 and 600 seconds) averaging on the above profiles are discussed. The validity of common surface layer wind profile models to estimate skin friction drag is assessed in light of these measurements. Other turbulence statistics such as auto- and cross- correlations in spatial and temporal domains are also presented. The help of FIT DMES field measurement crew is acknowledged.

  15. Effect of nitride chemical passivation of the surface of GaAs photodiodes on their characteristics

    Science.gov (United States)

    Kontrosh, E. V.; Lebedeva, N. M.; Kalinovskiy, V. S.; Soldatenkov, F. Yu; Ulin, V. P.

    2016-11-01

    Characteristics of GaAs photodiodes have been studied before and after the chemical nitridation of their surface in hydrazine sulfide solutions, which leads to substitution of surface As atoms with N atoms to give a GaN monolayer. The resulting nitride coatings hinder the oxidation of GaAs in air and provide a decrease in the density of surface states involved in recombination processes. The device characteristics improved by nitridation are preserved during a long time.

  16. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  17. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  18. Tyre - Road Noise, Surface Characteristics and Material Properties

    NARCIS (Netherlands)

    Li, M.

    2013-01-01

    Noise levels due to road traffic have reached intolerable high levels in and around many urban areas all around the world. Because of health reasons and reasons of well- being these noise levels have to be reduced. The noise produced from the interaction between the rolling tyre and road surface is

  19. On fluttering modes for aircraft wing model in subsonic air flow

    Science.gov (United States)

    Shubov, Marianna A.

    2014-01-01

    The paper deals with unstable aeroelastic modes for aircraft wing model in subsonic, incompressible, inviscid air flow. In recent author’s papers asymptotic, spectral and stability analysis of the model has been carried out. The model is governed by a system of two coupled integrodifferential equations and a two-parameter family of boundary conditions modelling action of self-straining actuators. The Laplace transform of the solution is given in terms of the ‘generalized resolvent operator’, which is a meromorphic operator-valued function of the spectral parameter λ, whose poles are called the aeroelastic modes. The residues at these poles are constructed from the corresponding mode shapes. The spectral characteristics of the model are asymptotically close to the ones of a simpler system, which is called the reduced model. For the reduced model, the following result is shown: for each value of subsonic speed, there exists a radius such that all aeroelastic modes located outside the circle of this radius centred at zero are stable. Unstable modes, whose number is always finite, can occur only inside this ‘circle of instability’. Explicit estimate of the ‘instability radius’ in terms of model parameters is given. PMID:25484610

  20. Effect of Initial Condition on Subsonic Jet Noise from Two Rectangular Nozzles

    Science.gov (United States)

    Zaman, K. B. M. Q.

    2012-01-01

    Differences in jet noise data from two small 8:1 aspect ratio nozzles are investigated experimentally. The interiors of the two nozzles are identical but one has a thin-lip at the exit while the has a perpendicular face at the exit (thick-lip). It is found that the thin-lip nozzle is substantially noisier throughout the subsonic Mach number range. As much as 5dB difference in OASPL is noticed around Mj =0.96. Hot-wire measurements are carried out for the characteristics of the exit boundary layer and, overall, the noise difference can be ascribed to differences in the boundary layer state. The boundary layer of the quieter (thick-lip) nozzle goes through transition around M(sub j) =0.25 and at higher M(sub j) it remains "nominally turbulent". In comparison, the boundary layer of the thin-lip nozzle is found to remain "nominally laminar". at high subsonic conditions. The nominally laminar state involves significantly larger turbulence intensities commensurate with the higher radiated noise.

  1. Angular characteristics of a multimode fiber surface plasmon resonance sensor

    CERN Document Server

    Tan, Zhixin; Li, Xuejin; Chen, Yuzhi; Hong, Xueming; Fan, Ping

    2015-01-01

    In this paper the angular characteristics of a multimode fiber SPR sensor are investigated theoretically. By separating the contributions of beams incident at different angles, a compact model is presented to predict the shift of the resonance wavelength with respect to the angle and the environmental refractive index. The result suggests that the performance of conventional fiber SPR sensors can be substantially improved by optimizing the incident angle.

  2. Fractal Characteristics of Aerosols Deposition in the Fiber Surface

    Institute of Scientific and Technical Information of China (English)

    FU Hai-ming; ZHU Hui

    2010-01-01

    To study the effects of particle motion mechanism and size distribution on fractal dimension of dust cake structure,the process of aerosol particles deposition in fibrous filtration medium was simulated on basis of Diffusion-Limited Aggregation(DLA)improving model.In this study,effects of inertia movement and diffusion movement on particles depoition would be considered.In the mean while,ratio of inertia movement to diffusion movement was defined as Pe number.The results show that surface curve of dust cake becomes irregular with Pe reducing and fractal dimension of dust cake surface increased with Pe increasing.The more greater particles dispersion,the more greater dust cake porosity,the more uneven the distribution.The porosity,formed by Pulydisperse dust particles,is less than that formed by monodisperse particles.Stronger particle diffusion movement,more uniform the dust cakes was.

  3. Radar, visual and thermal characteristics of Mars - Rough planar surfaces

    Science.gov (United States)

    Schaber, G. G.

    1980-05-01

    High-resolution Viking Orbiter images contain significant information on Martian surface roughness at 25- to 100-m lateral scales, while earth-based radar observations of Mars are sensitive to roughness at lateral scales of 1 to 30 m or more. High-rms slopes predicted for the Tharsis-Memnonia-Amazonis volcanic plains from extremely weak radar returns are qualitatively confirmed by the Viking image data. Large-scale, curvilinear ridges on lava flows in the Memnonia Fossae region are interpreted as innate flow morphology caused by compressional foldover of moving lava sheets of possible rhyolite-dacite composition. The presence or absence of a recent mantle of fine-grained eolian material on the volcanic surfaces studied was determined by the visibility of fresh impact craters with diameters less than 50 m. Lava flows with surfaces modified by eolian erosion and deposition occur west-northwest of Apollinaris Patera at the border of the cratered equatorial uplands and southern Elysium Planitia. Nearby yardangs, for which radar observations indicate very high-rms slopes, are similar to terrestrial features of similar origin.

  4. Multi-Mission Earth Vehicle Subsonic Dynamic Stability Testing and Analyses

    Science.gov (United States)

    Glaab, Louis J.; Fremaux, C. Michael

    2013-01-01

    Multi-Mission Earth Entry Vehicles (MMEEVs) are blunt-body vehicles designed with the purpose of transporting payloads from outer space to the surface of the Earth. To achieve high-reliability and minimum weight, MMEEVs avoid use of limited-reliability systems, such as parachutes, retro-rockets, and reaction control systems and rely on the natural aerodynamic stability of the vehicle throughout the Entry, Descent, and Landing (EDL) phase of flight. The Multi-Mission Systems Analysis for Planetary Entry (M-SAPE) parametric design tool is used to facilitate the design of MMEEVs for an array of missions and develop and visualize the trade space. Testing in NASA Langley?s Vertical Spin Tunnel (VST) was conducted to significantly improve M-SAPE?s subsonic aerodynamic models. Vehicle size and shape can be driven by entry flight path angle and speed, thermal protection system performance, terminal velocity limitations, payload mass and density, among other design parameters. The objectives of the VST testing were to define usable subsonic center of gravity limits, and aerodynamic parameters for 6-degree-of-freedom (6-DOF) simulations, for a range of MMEEV designs. The range of MMEEVs tested was from 1.8m down to 1.2m diameter. A backshell extender provided the ability to test a design with a much larger payload for the 1.2m MMEEV.

  5. Effect of Electrolytes on Surface Charge Characteristics of Red Soils

    Institute of Scientific and Technical Information of China (English)

    SHAOZONG-CHEN; HEQUN; 等

    1992-01-01

    The zero point of charge (ZPC) and the remaining charge σp at ZPC are two important parameters characterizing surface charge of red soils.Fourteen red soil samples of different soil type and parent material were treated with dithionite-citrate-dicarbonate (DCB) and Na2CO3 respectively.ZPC and σp of the samples in three indifferent electrolytes (NaCl,Na2SO4,and NaH2PO4) were determined.Kaolinite was used as reference.The results showed that ZPC of red soils was affected by the composition of parent materials and clay minerals and in significantly positive correlation with the content of total iron oxide (Fet),free iron oxide (Fed),amorphous iron oxide (Feo),aluminum oxide (Alo) and clay,but it was negatively correlated with the content of total silica (Sit).The σp of red soils was also markedly influenced by mineral components.Organic components were also contributing factor to the value of σp.The surface charges of red soils were evidently affected by the constitution of the electrolytes.Specific adsorption of anions in the electrolytes tended to make the ZPC of red soils shift to a higher pH value and to increase positive surface charges of the soils,thus leading to change of the σp value and decrease of the remaining net negative charges,even to the soils becoming net positive charge carriers.The effect of phosphate anion was greater than that of sulfate ion.

  6. CFD-Based Design Optimization Tool Developed for Subsonic Inlet

    Science.gov (United States)

    1995-01-01

    The traditional approach to the design of engine inlets for commercial transport aircraft is a tedious process that ends with a less-than-optimum design. With the advent of high-speed computers and the availability of more accurate and reliable computational fluid dynamics (CFD) solvers, numerical optimization processes can effectively be used to design an aerodynamic inlet lip that enhances engine performance. The designers' experience at Boeing Corporation showed that for a peak Mach number on the inlet surface beyond some upper limit, the performance of the engine degrades excessively. Thus, our objective was to optimize efficiency (minimize the peak Mach number) at maximum cruise without compromising performance at other operating conditions. Using a CFD code NPARC, the NASA Lewis Research Center, in collaboration with Boeing, developed an integrated procedure at Lewis to find the optimum shape of a subsonic inlet lip and a numerical optimization code, ADS. We used a GRAPE-based three-dimensional grid generator to help automate the optimization procedure. The inlet lip shape at the crown and the keel was described as a superellipse, and the superellipse exponents and radii ratios were considered as design variables. Three operating conditions: cruise, takeoff, and rolling takeoff, were considered in this study. Three-dimensional Euler computations were carried out to obtain the flow field. At the initial design, the peak Mach numbers for maximum cruise, takeoff, and rolling takeoff conditions were 0.88, 1.772, and 1.61, respectively. The acceptable upper limits on the takeoff and rolling takeoff Mach numbers were 1.55 and 1.45. Since the initial design provided by Boeing was found to be optimum with respect to the maximum cruise condition, the sum of the peak Mach numbers at takeoff and rolling takeoff were minimized in the current study while the maximum cruise Mach number was constrained to be close to that at the existing design. With this objective, the

  7. Aerodynamics characteristic of axisymmetric surface protuberance in supersonic regime

    KAUST Repository

    Qamar, Adnan

    2012-01-01

    The present work deals with the problem of an axi-symmetric surface protuberance mounted on a spherical nosed body of revolution. The numerical computations are carried out for laminar supersonic viscous flow for trapezoidal shape axi-symmetric protuberances. A free stream Mach number ranging from 3 to 8 in steps of 1 at a fixed free stream Reynolds number of 1.8x10(4) has been used in the present study. The steady solutions are obtained using a time marching approach. A newly developed Particle Velocity Upwinding (PVU) scheme has been used for the computation. The spatial flow pattern exhibits a strong bow shock in front of the hemispherical nose, which engulfs the entire base body. Near the protuberance, the fluid particle decelerates due to the adverse pressure created by the protuberance and thus the flow separates in front of the protuberance. This point of separation is found to be a function of Mach number and the protuberance shape. A low-pressure expansion region dominates the base region of the obstacle. The reattachment point for the base separation is also a function of Mach number. As the Mach number is increased the reattachment point shifts toward the protuberances base. A weak recompression shock is also seen in the base, which affects the separated zone behind the protuberance. The important design parameters such as skin friction, heat transfer, drag, and surface pressure coefficients are reported extensively.

  8. Subsonic Analysis of 0.04-Scale F-16XL Models Using an Unstructured Euler Code

    Science.gov (United States)

    Lessard, Wendy B.

    1996-01-01

    The subsonic flow field about an F-16XL airplane model configuration was investigated with an inviscid unstructured grid technique. The computed surface pressures were compared to wind-tunnel test results at Mach 0.148 for a range of angles of attack from 0 deg to 20 deg. To evaluate the effect of grid dependency on the solution, a grid study was performed in which fine, medium, and coarse grid meshes were generated. The off-surface vortical flow field was locally adapted and showed improved correlation to the wind-tunnel data when compared to the nonadapted flow field. Computational results are also compared to experimental five-hole pressure probe data. A detailed analysis of the off-body computed pressure contours, velocity vectors, and particle traces are presented and discussed.

  9. A computer program for wing subsonic aerodynamic performance estimates including attainable thrust and vortex lift effects

    Science.gov (United States)

    Carlson, H. W.; Walkley, K. B.

    1982-01-01

    Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.

  10. A Laplace transform/potential-theoretic method for acoustic propagation in subsonic flows

    CERN Document Server

    Hariharan, S I

    2003-01-01

    This paper introduces a competitive computational approach for determining time-dependent far-field sound generated by subsonic flows around lifting airfoils. The procedure assumes the linearity of the sound field away from a bounded region surrounding the airfoil. It is assumed that the sound pressure on the boundary of this enclosed region (referred to as the Kirchhoff surface) is specified, possibly by another procedure such as solving the full Euler equations. Away from the Kirchhoff surface, the Euler equations are linearized about a uniform mean flow. It is well known that linearized Euler equations can be uncoupled into a scalar convective wave equation. However, due to the anisotropy present in the convective wave equation, it is difficult to compute solutions. In this context, direct numerical simulation of the convective wave equation requires proper numerical descriptions of far-field boundary conditions which is a non-trivial task. Moreover, if accurate far-field conditions can be formulated, the ...

  11. Effect of Riblets upon Flow Separation in a Subsonic Diffuser

    Science.gov (United States)

    1988-12-01

    Technology Air University In Partial Fulfillment of the Requirements for the Degree of Master of Science in Aeronautical Engineering Nathan W. Martens...afterburner where the flow leaving the turbine must be 4 slowed from a high subsonic Mach number to a Mach number of about 0.2" (8:305). Physicall ., a...Riblets," Proceedings of the AIAA 20th Aerospace Sciences Meeting. Paper No. 82-0169. New York: American Institute of Aeronautics and Astronautics

  12. The surface heat island of Rotterdam and its relationship with urban surface characteristics

    NARCIS (Netherlands)

    Klok, L.; Zwart, S.; Verhagen, H.; Mauri, E.

    2012-01-01

    Thermal infrared high resolution satellite images from Landsat sensors were used to spatially quantify the surface heat island (SHI) of Rotterdam in the Netherlands. Based on surface temperature maps retrieved on 15 summer days since 1984, the average surface temperature of each district and neighbo

  13. Surface Characteristics of Silicon Nanowires/Nanowalls Subjected to Octadecyltrichlorosilane Deposition and n-octadecane Coating.

    Science.gov (United States)

    Yilbas, Bekir Sami; Salhi, Billel; Yousaf, Muhammad Rizwan; Al-Sulaiman, Fahad; Ali, Haider; Al-Aqeeli, Nasser

    2016-12-09

    In this study, nanowires/nanowalls were generated on a silicon wafer through a chemical etching method. Octadecyltrichlorosilane (OTS) was deposited onto the nanowire/nanowall surfaces to alter their hydrophobicity. The hydrophobic characteristics of the surfaces were further modified via a 1.5-μm-thick layer of n-octadecane coating on the OTS-deposited surface. The hydrophobic characteristics of the resulting surfaces were assessed using the sessile water droplet method. Scratch and ultraviolet (UV)-visible reflectivity tests were conducted to measure the friction coefficient and reflectivity of the surfaces. The nanowires formed were normal to the surface and uniformly extended 10.5 μm to the wafer surface. The OTS coating enhanced the hydrophobic state of the surface, and the water contact angle increased from 27° to 165°. The n-octadecane coating formed on the OTS-deposited nanowires/nanowalls altered the hydrophobic state of the surface. This study provides the first demonstration that the surface wetting characteristics change from hydrophobic to hydrophilic after melting of the n-octadecane coating. In addition, this change is reversible; i.e., the hydrophilic surface becomes hydrophobic after the n-octadecane coating solidifies at the surface, and the process again occurs in the opposite direction after the n-octadecane coating melts.

  14. Resolving high Reynolds numbers in SPH simulations of subsonic turbulence

    CERN Document Server

    Price, Daniel J

    2011-01-01

    Accounting for the Reynolds number is critical in numerical simulations of turbulence, particularly for subsonic flow. For Smoothed Particle Hydrodynamics (SPH) with constant artificial viscosity coefficient alpha, it is shown that the effective Reynolds number in the absence of explicit physical viscosity terms scales linearly with the Mach number - compared to mesh schemes, where the effective Reynolds number is largely independent of the flow velocity. As a result, SPH simulations with alpha=1 will have low Reynolds numbers in the subsonic regime compared to mesh codes, which may be insufficient to resolve turbulent flow. This explains the failure of Bauer and Springel (2011, arXiv:1109.4413v1) to find agreement between the moving-mesh code AREPO and the GADGET SPH code on simulations of driven, subsonic (v ~ 0.3 c_s) turbulence appropriate to the intergalactic/intracluster medium, where it was alleged that SPH is somehow fundamentally incapable of producing a Kolmogorov-like turbulent cascade. We show tha...

  15. Analysis on the Pollution Characteristics of Surface Runoff in Zhenjiang City

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to analyze the pollution characteristics of surface runoff in Zhenjiang City.[Method] On July 4 and August 16,2010,surface runoff samples were collected in different rainfall durations in Zhenjiang City,and the variation characteristics of suspended substance (SS),chemical oxygen demand (CODCr),ammonia nitrogen (NH3-N) and total phosphorus (TP) in surface runoff were analyzed.[Result] With the increase of rainfall duration,SS concentration in surface runoff of Zhenjiang City on July ...

  16. Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin

    2016-05-01

    Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

  17. Nonlinear prediction of the aerodynamic loads on lifting surfaces

    Science.gov (United States)

    Kandil, O. A.; Mook, D. T.; Nayfeh, A. H.

    1974-01-01

    A numerical procedure is used to predict the nonlinear aerodynamic characteristics of lifting surfaces of low aspect ratio at high angles of attack for low subsonic Mach numbers. The procedure utilizes a vortex-lattice method and accounts for separation at sharp tips and leading edges. The shapes of the wakes emanating from the edges are predicted, and hence the nonlinear characteristics are calculated. Parallelogram and delta wings are presented as numerical examples. The numerical results are in good agreement with the experimental data.

  18. Integration of an Advanced Cryogenic Electric Propulsion System (ACEPS) to Aerodynamically Efficient Subsonic Transport Aircraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal defines innovative aerodynamic concepts and technology goals aimed at vehicle efficiency for future subsonic aircraft in the 2020 ? 2030 timeframe....

  19. Surface characteristics and bioactivity of a novel natural HA/Zircon nanocomposite coated on dental implants

    NARCIS (Netherlands)

    Karamian, E.; Khandan, A.; Motamedi, M.R.K.; Mirmohammadi, H.

    2014-01-01

    The surface characteristics of implant which influence the speed and strength of osseointegration include surface chemistry, crystal structure and crystallinity, roughness, strain hardening, and presence of impurities. The aim of this study was to evaluate the bioactivity and roughness of a novel na

  20. Effects of drying temperature and surface characteristics of vegetable on the survival of salmonella.

    Science.gov (United States)

    Hawaree, N; Chiewchan, N; Devahastin, S

    2009-01-01

    The heat resistance of Salmonella Anatum inoculated on the surface of a model vegetable as affected by hot-air drying temperature (50 to 70 degrees C) and surface characteristics was determined in this study. Cabbage was selected as a model vegetable to demonstrate the effect of topographical feature of vegetable surface on the Salmonella attachment ability. An image analysis technique was developed to monitor the change of cabbage surface during drying and the specific surface characteristics were described in terms of the roughness factor (R). It was found that the water activity of the vegetable decreased while R-value increased with longer drying time and higher drying temperature. However, the changes of both parameters during drying did not show a significant effect on the susceptibility of Salmonella attached on the cabbage surface. Drying temperature was found to be a major factor influencing the heat resistance of Salmonella during drying.

  1. Simultaneous, Unsteady PIV and Photogrammetry Measurements of a Tension-Cone Decelerator in Subsonic Flow

    Science.gov (United States)

    Schairer, Edward T.; Heineck, James T.; Walker, Louise Ann; Kushner, Laura Kathryn; Zilliac, Gregory

    2010-01-01

    This paper describes simultaneous, synchronized, high-frequency measurements of both unsteady flow in the wake of a tension-cone decelerator in subsonic flow (by PIV) and the unsteady shape of the decelerator (by photogrammetry). The purpose of these measurements was to develop the test techniques necessary to validate numerical methods for computing fluid-structure interactions of flexible decelerators. A critical need for this effort is to map fabric surfaces that have buckled or wrinkled so that code developers can accurately represent them. This paper describes a new photogrammetric technique that performs this measurement. The work was done in support of the Entry, Descent, and Landing discipline within the Supersonics Project of NASA s Fundamental Aeronautics Program.

  2. Onset of cavity deformation upon subsonic motion of a projectile in a fluid complex plasma.

    Science.gov (United States)

    Zhukhovitskii, D I; Ivlev, A V; Fortov, V E; Morfill, G E

    2013-06-01

    We study the deformation of a cavity around a large projectile moving with subsonic velocity in the cloud of small dust particles. To solve this problem, we employ the Navier-Stokes equation for a compressible fluid with due regard for friction between dust particles and atoms of neutral gas. The solution shows that due to friction, the pressure of a dust cloud at the surface of a cavity around the projectile can become negative, which entails the emergence of a considerable asymmetry of the cavity, i.e., the cavity deformation. Corresponding threshold velocity is calculated, which is found to decrease with increasing cavity size. Measurement of such velocity makes it possible to estimate the static pressure inside the dust cloud.

  3. A Study On Recent Trends In High Subsonic Flow Over Delta Wings .

    Directory of Open Access Journals (Sweden)

    Vishnu G Nair,

    2014-01-01

    Full Text Available An understanding of the vortical structures and vortex breakdown is essential for the development of highly maneuverable and high angle of attack flight. This is primarily due to the physical limits these phenomena impose on aircraft and missiles at extreme flight conditions. In today’s competitive world, demands for more maneuverable and stealthy air vehicles have encouraged the development of new control concepts for separated flows and vortex flow.An overview is given about investigations on a 65◦ delta wing using the Pressure Sensitive Paint (PSP and Particle Image Velocimetry (PIV techniques, carried out in the framework of Vortex flow experiment. For the delta wing with rounded leading edges and subsonic flow, the occurrence of a flat vortical structure as well as the onset of the primary vortex and the development of a vortex system consisting of an inner and outer vortex is described in dependency of the angle of attack and the Reynolds number. The Q - criterion is applied to the measured velocity data to estimate the circulation strength of individual vortices allowing for a quantitative description of the vortex developments and interactions. Furthermore, a case at transonic flow speeds (M = 0.8 is described, showing a sudden occurrence of vortex breakdown above the delta wing, most probably induced by a shock wave.Vortex Flow Experiment provided a variety of experimental data for a 65◦ swept delta wing sharp and blunt leading edges. Flow details including forces and moments, surface pressures,Pressure Sensitive Paint measurements, and off-surface flow variables from Particle Image Velocimetry were made available for comparisons with computational simulations. This paper concentrates on some typical problems of delta wings with rounded leading edges at subsonic speed: the prediction of the main leading edge separation, the generation of the second inner vortex, the effect of transition, and Reynolds number effects.

  4. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.

    Science.gov (United States)

    Valenzuela Melendres, M; Camou, J P; Torrentera Olivera, N G; Alvarez Almora, E; González Mendoza, D; Avendaño Reyes, L; González Ríos, H

    2014-05-01

    Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L, a, and b), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L and a values and decreased weight loss of cooked products (Psensory characteristics of the cooked product (Psensory characteristics evaluated had an acceptable score (>5.6). Thus FS and TP are ingredients that can be used in beef patty preparation.

  5. Multivariate Analysis, Retrieval, and Storage System (MARS). Volume 6: MARS System - A Sample Problem (Gross Weight of Subsonic Transports)

    Science.gov (United States)

    Hague, D. S.; Woodbury, N. W.

    1975-01-01

    The Mars system is a tool for rapid prediction of aircraft or engine characteristics based on correlation-regression analysis of past designs stored in the data bases. An example of output obtained from the MARS system, which involves derivation of an expression for gross weight of subsonic transport aircraft in terms of nine independent variables is given. The need is illustrated for careful selection of correlation variables and for continual review of the resulting estimation equations. For Vol. 1, see N76-10089.

  6. Inverse modeling of soil characteristics from surface soil moisture observations: potential and limitations

    Directory of Open Access Journals (Sweden)

    A. Loew

    2008-01-01

    Full Text Available Land surface models (LSM are widely used as scientific and operational tools to simulate mass and energy fluxes within the soil vegetation atmosphere continuum for numerous applications in meteorology, hydrology or for geobiochemistry studies. A reliable parameterization of these models is important to improve the simulation skills. Soil moisture is a key variable, linking the water and energy fluxes at the land surface. An appropriate parameterisation of soil hydraulic properties is crucial to obtain reliable simulation of soil water content from a LSM scheme. Parameter inversion techniques have been developed for that purpose to infer model parameters from soil moisture measurements at the local scale. On the other hand, remote sensing methods provide a unique opportunity to estimate surface soil moisture content at different spatial scales and with different temporal frequencies and accuracies. The present paper investigates the potential to use surface soil moisture information to infer soil hydraulic characteristics using uncertain observations. Different approaches to retrieve soil characteristics from surface soil moisture observations is evaluated and the impact on the accuracy of the model predictions is quantified. The results indicate that there is in general potential to improve land surface model parameterisations by assimilating surface soil moisture observations. However, a high accuracy in surface soil moisture estimates is required to obtain reliable estimates of soil characteristics.

  7. Laser treatment of a neodymium magnet and analysis of surface characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

    2016-08-01

    Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

  8. Simulation of Atmospheric-Entry Capsules in the Subsonic Regime

    Science.gov (United States)

    Murman, Scott M.; Childs, Robert E.; Garcia, Joseph A.

    2015-01-01

    The accuracy of Computational Fluid Dynamics predictions of subsonic capsule aerodynamics is examined by comparison against recent NASA wind-tunnel data at high-Reynolds-number flight conditions. Several aspects of numerical and physical modeling are considered, including inviscid numerical scheme, mesh adaptation, rough-wall modeling, rotation and curvature corrections for eddy-viscosity models, and Detached-Eddy Simulations of the unsteady wake. All of these are considered in isolation against relevant data where possible. The results indicate that an improved predictive capability is developed by considering physics-based approaches and validating the results against flight-relevant experimental data.

  9. Finite element analysis of inviscid subsonic boattail flow

    Science.gov (United States)

    Chima, R. V.; Gerhart, P. M.

    1981-01-01

    A finite element code for analysis of inviscid subsonic flows over arbitrary nonlifting planar or axisymmetric bodies is described. The code solves a novel primitive variable formulation of the coupled irrotationality and compressible continuity equations. Results for flow over a cylinder, a sphere, and a NACA 0012 airfoil verify the code. Computed subcritical flows over an axisymmetric boattailed afterbody compare well with finite difference results and experimental data. Interative coupling with an integral turbulent boundary layer code shows strong viscous effects on the inviscid flow. Improvements in code efficiency and extensions to transonic flows are discussed.

  10. NASA Subsonic Rotary Wing Project - Structures and Materials Discipline

    Science.gov (United States)

    Halbig, Michael C.; Johnson, Susan M.

    2008-01-01

    The Structures & Materials Discipline within the NASA Subsonic Rotary Wing Project is focused on developing rotorcraft technologies. The technologies being developed are within the task areas of: 5.1.1 Life Prediction Methods for Engine Structures & Components 5.1.2 Erosion Resistant Coatings for Improved Turbine Blade Life 5.2.1 Crashworthiness 5.2.2 Methods for Prediction of Fatigue Damage & Self Healing 5.3.1 Propulsion High Temperature Materials 5.3.2 Lightweight Structures and Noise Integration The presentation will discuss rotorcraft specific technical challenges and needs as well as details of the work being conducted in the six task areas.

  11. Experimental and CFD analysis of nozzle position of subsonic ejector

    Institute of Scientific and Technical Information of China (English)

    Xilai ZHANG; Shiping JIN; Suyi HUANG; Guoqing TIAN

    2009-01-01

    The influence of nozzle position on the performance of an ejector was analyzed qualitatively with free jet flow model. Experimental investigations and computational fluid dynamics (CFD) analysis of the nozzle position of the subsonic ejector were also conducted. The results show that there is an optimum nozzle position for the ejector. The ejecting coefficient reaches its maximum when the nozzle is positioned at the optimum and decreases when deviating. Moreover, the nozzle position of an ejector is not a fixed value, but is influenced greatly by the flow parameters. Considering the complexity of the ejector, CFD is reckoned as a useful tool in the design of ejectors.

  12. 3D Interest Point Detection using Local Surface Characteristics with Application in Action Recognition

    DEFF Research Database (Denmark)

    Holte, Michael Boelstoft

    2014-01-01

    . The proposed Difference-of-Normals (DoN) 3D IP detector operates on the surface mesh, and evaluates the surface structure (curvature) locally (per vertex) in the mesh data. We present an exam- ple of application in action recognition from a sequence of 3-dimensional geometrical data, where local 3D motion de......In this paper we address the problem of detecting 3D inter- est points (IPs) using local surface characteristics. We con- tribute to this field by introducing a novel approach for detec- tion of 3D IPs directly on a surface mesh without any require- ments of additional image/video information...

  13. Enhancing the representation of subgrid land surface characteristics in land surface models

    Directory of Open Access Journals (Sweden)

    Y. Ke

    2013-03-01

    Full Text Available Land surface heterogeneity has long been recognized as important to represent in the land surface models. In most existing land surface models, the spatial variability of surface cover is represented as subgrid composition of multiple surface cover types. In this study, we developed a new subgrid classification method (SGC that accounts for the topographic variability of the vegetation cover. Each model grid cell was represented with a number of elevation classes and each elevation class was further described by a number of vegetation types. The numbers of elevation classes and vegetation types were variable and optimized for each model grid so that the spatial variability of both elevation and vegetation can be reasonably explained given a pre-determined total number of classes. The subgrid structure of the Community Land Model (CLM was used as an example to illustrate the newly developed method in this study. With similar computational burden as the current subgrid vegetation representation in CLM, the new method is able to explain at least 80% of the total subgrid Plant Functional Types (PFTs and greatly reduced the variations of elevation within each subgrid class compared to the baseline method where a single elevation class is assigned to each subgrid PFT. The new method was also evaluated against two other subgrid methods (SGC1 and SGC2 that assigned fixed numbers of elevation and vegetation classes for each model grid with different perspectives of surface cover classification. Implemented at five model resolutions (0.1°, 0.25°, 0.5°, 1.0° and 2.0° with three maximum-allowed total number of classes Nclass of 24, 18 and 12 representing different computational burdens over the North America (NA continent, the new method showed variable performances compared to the SGC1 and SGC2 methods. However, the advantage of the SGC method over the other two methods clearly emerged at coarser model resolutions and with moderate computational

  14. Aero-acoustic simulation of a subsonic hot jet; Simulation aeroacoustique d'un jet chaud subsonique

    Energy Technology Data Exchange (ETDEWEB)

    Biancherin, A.; Rahier, G.; Prieur, J.; Vuillot, F.; Lupoglazoff, N.

    2002-07-01

    This paper presents a numerical simulation of subsonic a hot jet (M 0,7) and its acoustic analysis. The MSD code of the ONERA is used to resolve the Navier-Stokes equations. A detailed study, parametric and theoretical is realized to analyze the influence of the formulation, the position, the part and the nature of the control surface on the acoustic calculation results. The acoustic predictions in far field are compared to measures realized by the ONERA in the anechoic CEPRA 19 wind tunnel. (A.L.B.)

  15. Biochar production from coffee residues: Optimization of surface characteristics and sorptive behavior

    Science.gov (United States)

    Fotopoulou, Kalliopi; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

    2015-04-01

    Biochar with high surface area is a promising sorbent for environmental remediation and is produced by heating biomass in an oxygen-limited environment. Knowing the surface characteristics increases our understanding of biochar interactions with pollutants. The hypothesis of the present study is that by controlling pyrolysis conditions, the surface characteristics and subsequently the sorption behavior of produced biochars can be optimized. Coffee residues were dried overnight at 50oC and then pyrolized into a gradient furnace at 850oC. Different solid/oxygen ratios during pyrolysis were tested as well as the up scaling of the process. The biochars produced were systematically characterized for their surface characteristics such as BET surface area, open surface area, pore and micropore volume, and average pore size. The effect of pyrolysis on the biochar suspension pH was examined with the mass addition technique that involves the addition of increasing amounts of the biochar to bottles containing 0.1 M NaNO3. FTIR analysis was used in order to determine the functional groups of the coffee residue and of the biochars. The macrostructure of the biochars was visualized by Scanning Electron Microscopy (SEM). Total Carbon (TC) in the samples was determined by Carlo Erba Elemental Analyzer CHNS, EO 1108 after calibration with standard samples. The sorption behavior of produced biochars was tested with two different pollutants (Hg(II), phenanthrene) using batch reactors with the same initial single-compound solution and the same mass of coffee residue and different biochars. The biochars produced exhibited a wide range of surface area from 21 to 770 m2/g and open surface area due to macropores from 21 to 65 m2/g. This suggests that the surface area in the biochars with high surface area results from the formation of pores. Actually for the biochar with the highest surface area, it was calculated that up to 90

  16. The Research on Friction Characteristics of Non Smooth Bionic Mesoscopic Surface

    Directory of Open Access Journals (Sweden)

    Su Chunjian

    2014-12-01

    Full Text Available The application of using friction to transmit power and prevent slippage is very widely used, many animals have very strong adhesion climbing ability, and it has important theoretical significance and wide application prospect to research and the prepare bionic surface to increase transmission friction using the bionic technology. In recent years, the research of foot structure of climbing animals shows that their surface morphology has both macro and micro scale features, and only study from the macro to the micro scale surface structure can be better elucidate the mechanism of increasing-friction of climbing animal. This paper will study bionic surface structure on mesoscopic scale from micron to millimeter level, research the influence of foot structure of climbing animal under mesoscopic scale on characteristics of increasing friction using bionic technology, prepare the bionic non-smooth surface of convex or concave using bionic manufacturing technology, establish the friction model of non-smooth surface, investigate the increasing-friction mechanism of the bionic surface morphology on mesoscopic scales, reveals the influence of surface morphology, layout, size and material properties on the friction characteristics, provide the design of bionic friction surface and calculation method of friction coefficient and provide reliable theoretical basis for engineering application.

  17. Acoustic characteristics of bubble bursting at the surface of a high-viscosity liquid

    Institute of Scientific and Technical Information of China (English)

    Liu Xiao-Bo; Zhang Jian-Run; Li Pu

    2012-01-01

    An acoustic pressure model of bubble bursting is proposed.An experiment studying the acoustic characteristics of the bursting bubble at the surface of a high-viscosity liquid is reported.It is found that the sudden bursting of a bubble at the high-viscosity liquid surface generates N-shape wave at first,then it transforms into a jet wave.The fundamental frequency of the acoustic signal caused by the bursting bubble decreases linearly as the bubble size increases.The results of the investigation can be used to understand the acoustic characteristics of bubble bursting.

  18. The Characteristics of the Surface Topography of Excimer Laser Processed Al2O3 Ceramic

    Institute of Scientific and Technical Information of China (English)

    LIUYing; WENShi-zhu

    2004-01-01

    Surface of Al2O3 ceramic was processed by an excimer laser and the characteristics of topography were examined based on the application of thesystem(MEMS). It is indicated that the statistic pararueters of surface topography processed by the excimer laser have an obvioas regularity. The arithmeticmean value Ro and the root-mean square value Rq change with the changing of processing parameters in the same step and trend, and there is a quantitative relation between them. A simplified nuuIel is proposed for the excimer laser processing surface profile, whose results of the analysis and calculation agree basically with the experimental data. Furthermore, the surfaces processed by excimer laser are greatly fiat. Skewness root-mean-square value Zq changed little with the change of the technological parameters. The above characteristics depend on the processing principle of excimer laser, quite different from the cutting processing.

  19. Characteristics of flame spread over the surface of charring solid combustibles at high altitude

    Institute of Scientific and Technical Information of China (English)

    LI Jie; JI Jie; ZHANG Ying; SUN JinHua

    2009-01-01

    To explore the characteristics of flame spread over the surface of charring solid combustibles at high altitude, the whitewood with uniform texture was chosen to conduct a series of experiments in Lhasa and Hefei, with altitude of 3658 m and 50 m respectively. Several parameters, including the flame height, flame spread rate, flame temperature, surface temperature, were measured on samples with different width and inclinations. A quantitative analysis of flame spread characteristics over sample surface at high altitude was performed. Results showed that, in the environment of lower pressure and oxygen concentration at high altitude, the flame height and flame spread rate over sample surface decreased, but the flame temperature increased slightly. However, with increasing of sample width, the relative difference between the flame spread rates at different altitudes decreased.

  20. 3D Characteristic Diagram of Acoustically Induced Surface Vibration with Different Landmines Buried

    Institute of Scientific and Technical Information of China (English)

    吴智强; 张燕丽; 王驰; 朱俊; 徐文文; 袁志文

    2016-01-01

    The 3Dcharacteristic diagram of acoustically induced surface vibration was employed to study the influence of different buried landmines on the acoustic detection signal. By using the vehicular experimental system for acoustic landmine detection and the method of scanning detection, the 3D characteristic diagrams of surface vibration were measured when different objects were buried underground, including big plastic landmine, small plastic landmine, big metal landmine and bricks. The results show that, under the given conditions, the surface vi-bration amplitudes of big plastic landmine, big metal landmine, small plastic landmine and bricks decrease in turn. The 3D characteristic diagrams of surface vibration can be used to further identify the locations of buried land-mines.

  1. Fourier time spectral method for subsonic and transonic flows

    Institute of Scientific and Technical Information of China (English)

    Lei Zhan; Feng Liu; Dimitri Papamoschou

    2016-01-01

    The time accuracy of the exponentially accu-rate Fourier time spectral method (TSM) is examined and compared with a conventional 2nd-order backward differ-ence formula (BDF) method for periodic unsteady flows. In particular, detailed error analysis based on numerical com-putations is performed on the accuracy of resolving the local pressure coefficient and global integrated force coefficients for smooth subsonic and non-smooth transonic flows with moving shock waves on a pitching airfoil. For smooth sub-sonic flows, the Fourier TSM method offers a significant accuracy advantage over the BDF method for the predic-tion of both the local pressure coefficient and integrated force coefficients. For transonic flows where the motion of the discontinuous shock wave contributes significant higher-order harmonic contents to the local pressure fluctuations, a sufficient number of modes must be included before the Fourier TSM provides an advantage over the BDF method. The Fourier TSM, however, still offers better accuracy than the BDF method for integrated force coefficients even for transonic flows. A problem of non-symmetric solutions for symmetric periodic flows due to the use of odd numbers of intervals is uncovered and analyzed. A frequency-searching method is proposed for problems where the frequency is not known a priori. The method is tested on the vortex shedding problem of the flow over a circular cylinder.

  2. Modelling of subsonic COIL with an arbitrary magnetic modulation

    Science.gov (United States)

    Beránek, Jaroslav; Rohlena, Karel

    2007-05-01

    The concept of 1D subsonic COIL model with a mixing length was generalized to include the influence of a variable magnetic field on the stimulated emission cross-section. Equations describing the chemical kinetics were solved taking into account together with the gas temperature also a simplified mixing model of oxygen and iodine molecules. With the external time variable magnetic field the model is no longer stationary. A transformation in the system moving with the mixture reduces partial differential equations to ordinary equations in time with initial conditions given either by the stationary flow at the moment when the magnetic field is switched on combined with the boundary conditions at the injector. Advantage of this procedure is a possibility to consider an arbitrary temporal dependence of the imposed magnetic field and to calculate directly the response of the laser output. The method was applied to model the experimental data measured with the subsonic version of the COIL device in the Institute of Physics, Prague, where the applied magnetic field had a saw-tooth dependence. We found that various values characterizing the laser performance, such as the power density distribution over the active zone cross-section, may have a fairly complicated structure given by combined effects of the delayed reaction to the magnetic switching and the flow velocity. This is necessarily translated in a time dependent spatial inhomogeneity of output beam intensity profile.

  3. Topographical Parameter Characteristics of Dry Sliding Surfaces of Particle-Reinforced Aluminum Composites

    Institute of Scientific and Technical Information of China (English)

    陈跃; 上官宝; 张永振; 孙乐民; 铁喜顺; 夏跃虹

    2004-01-01

    Generally, friction and wear occur on the surface of the materials.It is necessary to investigate the dry sliding friction and wear behavior of surface.In this paper, 3-D topographical parameters were used to investigate the topographical characteristics of dry sliding surfaces for particle-reinforced aluminum composites on semi-metallic friction material.The experimental results indicate that the surface topography of the particle-reinforced aluminum composites can be divided into two types, the flaking-off pit type and the groove type.The composites whose surface topography is the flaking-off pit type possess superior heat conductivity and bearing area, lower wear rate, and higher friction coefficient than the groove type.Consequently, the flaking-off pit type surface topography is much better than the groove type for particle-reinforced aluminum composites on semi-metallic friction materials in dry sliding.

  4. Surface characteristics of aluminum 6061 T6 subjected to Nd:YAG pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sung Ho; Kim, Chung Seok; Jhang, Kyung Young; Shin, Wan Soon [Hanyang University, Seoul (Korea, Republic of)

    2012-07-15

    The objective of this study was to investigate the surface characteristics of an aluminum 6061 T6 alloy subjected to Nd:YAG pulsedlaser irradiation. The test specimens were prepared by a mechanical polishing process using diamond paste and emery polishing paper to obtain different levels of initial surface roughness. After ten pulsed laser shots, the surface morphology was observed via optical microscopy (OM) and scanning electron microscopy (SEM). Nano indentation hardness testing was also conducted on the irradiated surface. The diameter of the melted zone increased with surface roughness because of the multiple reflection and absorption of the laser beam. The relative absorbance was measured as a function of the diameter of the melted zone with varied surface roughness.

  5. Quantitative analysis of surface characteristics and morphology in Death Valley, California using AIRSAR data

    Science.gov (United States)

    Kierein-Young, K. S.; Kruse, F. A.; Lefkoff, A. B.

    1992-01-01

    The Jet Propulsion Laboratory Airborne Synthetic Aperture Radar (JPL-AIRSAR) is used to collect full polarimetric measurements at P-, L-, and C-bands. These data are analyzed using the radar analysis and visualization environment (RAVEN). The AIRSAR data are calibrated using in-scene corner reflectors to allow for quantitative analysis of the radar backscatter. RAVEN is used to extract surface characteristics. Inversion models are used to calculate quantitative surface roughness values and fractal dimensions. These values are used to generate synthetic surface plots that represent the small-scale surface structure of areas in Death Valley. These procedures are applied to a playa, smooth salt-pan, and alluvial fan surfaces in Death Valley. Field measurements of surface roughness are used to verify the accuracy.

  6. Dynamic behavior of water droplets and flashover characteristics on a superhydrophobic silicone rubber surface

    Science.gov (United States)

    Li, Yufeng; Jin, Haiyun; Nie, Shichao; Zhang, Peng; Gao, Naikui

    2017-05-01

    In this paper, a superhydrophobic surface is used to increase the flashover voltage when water droplets are present on a silicone rubber surface. The dynamic behavior of a water droplet and the associated flashover characteristics are studied on common and superhydrophobic silicone rubber surfaces under a high DC voltage. On common silicone rubber, the droplet elongates and the flashover voltage decreases with increasing droplet volume and conductivity. In contrast, the droplet slides off the superhydrophobic surface, leading to an increased flashover voltage. This droplet sliding is due to the low adhesion of the superhydrophobic surface and a sufficiently high electrostatic force provided by the DC voltage. Experimental results show that a superhydrophobic surface is effective at inhibiting flashover.

  7. Fractal Characteristics and Fractal Dimension Measurement on Broken Surfaces of Aluminum Electric Porcelain

    Institute of Scientific and Technical Information of China (English)

    YANG Zhiyuan; ZHOU Anning

    2005-01-01

    The characteristics of broken surfaces were researched by a scanning electron microscope (SEM) and a reflection microscope, and the fractal dimensions of broken surfaces were measured by the Slit Island method. The experimental results indicate that the broken surface of aluminum electric porcelain is a fractal body in statistics, and the fractal dimensions of broken surfaces are different with the different amplification multiple value.In all of measured fractal dimensions,both of values measured in 100× under reflection microscope and in 500× under SEM are maximum, whereas the values measured in 63× under reflection microscope and in 2000× under SEM are obviously minimum. The fractal dimensions of broken surfaces are also affected by the degrees of gray comparison and the kinds of measuring methods. The relationships between the fractal dimensions of broken surfaces and porcelain bend strengths are that they are in positive correlation on the low multiples and in negative correlation on the high multiples.

  8. Effect of surface characteristics on adherence of S. mutans biofilms to indirect resin composites.

    Science.gov (United States)

    Ikeda, Masaomi; Matin, Khairul; Nikaido, Toru; Foxton, Richard M; Tagami, Junji

    2007-11-01

    The purpose of this study was to evaluate the adherence of biofilms to the surfaces of two indirect resin composites, Estenia C&B and Gradia. Slabs were prepared from the materials, and then either ground with 800-grit silicon carbide paper or polished with diamond pastes up to 1 microm. Artificial biofilms of Streptococcus mutans were grown on the composite slabs in an artificial mouth system for 20 hours. Thereafter, the amounts of retained biofilm on the surfaces were measured after sonication. Surface characteristics of the resins--such as surface roughness, amount of residual monomers, and distribution of filler particles--were examined. Two-way ANOVA revealed that the amount of retained biofilm varied (pcomposition and surface roughness of the material. In particular, biofilm adherence was lowest on Estenia C&B slabs when polished with diamond pastes up to 1 microm. It was thus concluded that the surface roughness and composition of a resin composite influenced biofilm adherence.

  9. Surface characteristics of nanocrystalline apatites: effect of mg surface enrichment on morphology, surface hydration species, and cationic environments.

    Science.gov (United States)

    Bertinetti, Luca; Drouet, Christophe; Combes, Christele; Rey, Christian; Tampieri, Anna; Coluccia, Salvatore; Martra, Gianmario

    2009-05-19

    The incorporation of foreign ions, such as Mg2+, exhibiting a biological activity for bone regeneration is presently considered as a promising route for increasing the bioactivity of bone-engineering scaffolds. In this work, the morphology, structure, and surface hydration of biomimetic nanocrystalline apatites were investigated before and after surface exchange with such Mg2+ ions, by combining chemical alterations (ion exchange, H2O-D2O exchanges) and physical examinations (Fourier transform infrared spectroscopy (FTIR) and high-resolution transmission electron microscopy (HRTEM)). HRTEM data suggested that the Mg2+/Ca2+ exchange process did not affect the morphology and surface topology of the apatite nanocrystals significantly, while a new phase, likely a hydrated calcium and/or magnesium phosphate, was formed in small amount for high Mg concentrations. Near-infrared (NIR) and medium-infrared (MIR) spectroscopies indicated that the samples enriched with Mg2+ were found to retain more water at their surface than the Mg-free sample, both at the level of H2O coordinated to cations and adsorbed in the form of multilayers. Additionally, the H-bonding network in defective subsurface layers was also noticeably modified, indicating that the Mg2+/Ca2+ exchange involved was not limited to the surface. This work is intended to widen the present knowledge on Mg-enriched calcium phosphate-based bioactive materials intended for bone repair applications.

  10. Investigation on the adsorption characteristics of anserine on the surface of colloidal silver nanoparticles.

    Science.gov (United States)

    Thomas, S; Maiti, N; Mukherjee, T; Kapoor, S

    2013-08-01

    The surface-enhanced Raman scattering (SERS) studies of anserine (beta-alanyl-N-methylhistidine) was carried out on colloidal silver nanoparticles to understand its adsorption characteristics. The experimentally observed Raman bands were assigned based on the results of DFT calculations. The studies suggest that the interaction of anserine is primarily through the carboxylate group with the imidazole ring in an upright position with respect to the silver surface. Concentration dependent SERS studies suggest a change in orientation at sub-monolayer concentration.

  11. Mechanical theorem proving in the surfaces using the characteristic set method and Wronskian determinant

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we generalize the method of mechanical theorem proving in curves to prove theorems about surfaces in differential geometry with a mechanical procedure. We improve the classical result on Wronskian determinant, which can be used to decide whether the elements in a partial differential field are linearly dependent over its constant field. Based on Wronskian determinant, we can describe the geometry statements in the surfaces by an algebraic language and then prove them by the characteristic set method.

  12. Cell surface characteristics enable encrustation-free survival of neutrophilic iron-oxidizing bacteria

    Science.gov (United States)

    Saini, G.; Chan, C. S.

    2011-12-01

    Microbial growth in mineralizing environments depends on the cells' ability to evade surface precipitation. Cell-mineral interactions may be required for metabolism, but if unmoderated, cells could become encrusted, which would limit diffusion of nutrients and waste across cell walls. A combination of cell surface charge and hydrophobicity could enable the survival of microbes in such environments by inhibiting mineral attachment. To investigate this mechanism, we characterized the surfaces of two neutrophilic iron-oxidizing bacteria (FeOB): Mariprofundus ferrooxydans, a Zetaproteobacterium from Fe(II)-rich submarine hydrothermal vents and a Betaproteobacterium Gallionellales strain R-1, recently isolated from a ferrous groundwater seep. Both bacteria produce iron oxyhydroxides, yet successfully escape surface encrustation while inhabiting milieu where iron minerals are also produced by abiotic processes. SEM-EDX and TEM-EELS analyses of cultured bacteria revealed no iron on the cell surfaces. Zeta potential measurements showed that these bacteria have very small negative surface charge (0 to -4 mV) over a pH range of 4-9, indicating near-neutrally charged surfaces. Water contact angle measurements and thermodynamic calculations demonstrate that both bacteria and abiotically-formed Fe oxhydroxides are hydrophilic. Extended-DLVO calculations showed that hydrophilic repulsion between cells and minerals dominates over electrostatic and Lifshitz-van der Waals interactions. This leads to overall repulsion between microbes and minerals, thus preventing surface encrustation. Low surface charge and hydrophilicity (determined by microbial adhesion to hydrocarbon assay) were common features for both live and azide-inhibited cells, which shows that surface characteristics do not depend on active metabolism. It is remarkable that these two phylogenetically-distant bacteria from different environments employ similar adaptations to prevent surface mineralization. Our results

  13. Correlation between Surface Roughness Characteristics in CO2 Laser Cutting of Mild Steel

    Directory of Open Access Journals (Sweden)

    M. Radovanović

    2012-12-01

    Full Text Available CO2 laser oxygen cutting of mild steel is widely used industrial application. Cut surface quality is a very important characteristic of laser cutting that ensures an advantage over other contour cutting processes. In this paper mathematical models for estimating characteristics of surface quality such as average surface roughness and ten-point mean roughness in CO2 laser cutting of mild steel based on laser cutting parameters were developed. Empirical models were developed using artificial neural networks and experimental data collected. Taguchi’s orthogonal array was implemented for experimental plan. From the analysis of the developed mathematical models it was observed that functional dependence between laser cutting parameters, their interactions and surface roughness characteristics is complex and non-linear. It was also observed that there exist region of minimal average surface roughness to ten-point mean roughness ratio. The relationship between average surface roughness and ten-point mean roughness was found to be nonlinear and can be expressed with a second degree polynomial.

  14. Experimental Study on Surface Characteristics of Laser Cladding Layer Regulated by High-Frequency Microforging

    Science.gov (United States)

    Fan, Xiang Fang; Zhou, Ju; Qiu, Chang Jun; He, Bin; Ye, Jiang; Yuan, Bo; Pi, Zhengqing

    2011-03-01

    High-frequency microforging technology is used to produce micrometer-scale plastic deformation on the surface of material out of the vibration impact of a forging punch, and the cumulative effect of its various frequencies on micrometer-scale plastic deformation can cause changes of surface microstructure and mechanical properties. This study used (1) a self-made machine to treat NiCrBSi alloy, (2) a mechanical comparator and optical microscopy (OM) to study the geometric characteristics of plastic deformation, (3) OM and scanning electric microscopy (SEM) to observe influence on surface microstructure and cracking behavior of the laser cladding layer under microforging, (4) x-ray diffractometer (XRD) to measure the surface residual stress of laser cladding layer before and after forging, and (5) microhardness tester and wearing experimental machine to study changes of microhardness, friction coefficient, and wear characteristics of laser cladding layer after microforging. The results have shown that high-frequency microforging could produce plastic deformation about 150 μm deep on the surface of NiCrBSi alloy clad by laser. Regular dendrite and eutectic crystallization microstructure, which is a peculiar characteristic of the laser cladding layer, was broken into pieces and formed residual compression residual stress on the surface. Resistance to cracking of laser cladding layer improved greatly, microhardness and wearability increased, and the friction coefficient did not under go a noticeable change.

  15. TranAir: A full-potential, solution-adaptive, rectangular grid code for predicting subsonic, transonic, and supersonic flows about arbitrary configurations. User's manual

    Science.gov (United States)

    Johnson, F. T.; Samant, S. S.; Bieterman, M. B.; Melvin, R. G.; Young, D. P.; Bussoletti, J. E.; Hilmes, C. L.

    1992-01-01

    The TranAir computer program calculates transonic flow about arbitrary configurations at subsonic, transonic, and supersonic freestream Mach numbers. TranAir solves the nonlinear full potential equations subject to a variety of boundary conditions modeling wakes, inlets, exhausts, porous walls, and impermeable surfaces. Regions with different total temperature and pressure can be represented. The user's manual describes how to run the TranAir program and its graphical support programs.

  16. Surface soil factors and soil characteristics in geo-physical milieu of Kebbi State Nigeria

    Directory of Open Access Journals (Sweden)

    Suleiman Usman

    2016-07-01

    Full Text Available Soil erodibility (K factor is the most important tool for estimation the erosion. The aim of this study Soil factors and surface soil characteristics are important components of agricultural environment. They support surface and subsurface soils to perform many functions to agriculture and economic human developments. Understanding these factors would aid to the recognition of the values that our soil and land offered to humanity. It is therefore, aim of this study to visualise and examine the soil factors and surface soil characteristics in Kebbi State Nigeria. An Integrated Surface Soil Approach (ISSA was used in the classification and description of soil environment in the study region. The factors constituted in the ISSA are important components of soil science that theories and practice(s noted to provide ideas on how soil environment functioned. The results indicate that the surface soil environments around Arewa, Argungu, Augie, Birnin Kebbi and Dandi are physically familiar with the following surface soil characteristics: bad-lands, blown-out-lands, cirque-lands, fertile-lands, gullied-lands, miscellaneous and rock-outcrops.The major soil factors observed hat played an important role in surface soil manipulations and soil formation are alluvial, colluvial, fluvial and lacustrine; ant, earthworms and termite; and various forms of surface relief supported by temperature, rainfall, relative humidity and wind. Overall, the surface soil environment of the region was describe according to their physical appearance into fadama clay soils, fadama clay-loam soils, dryland sandy soils, dryland sandy-loam soils, dryland stony soils and organic-mineral soils.

  17. Development of Fractal Dimension and Characteristic Roughness Models for Turned Surface of Carbon Steels

    Science.gov (United States)

    Zuo, Xue; Zhu, Hua; Zhou, Yuankai; Ding, Cong; Sun, Guodong

    2016-08-01

    Relationships between material hardness, turning parameters (spindle speed and feed rate) and surface parameters (surface roughness Ra, fractal dimension D and characteristic roughness τ∗) are studied and modeled using response surface methodology (RSM). The experiments are carried out on a CNC lathe for six carbon steel material AISI 1010, AISI 1020, AISI 1030, AISI 1045, AISI 1050 and AISI 1060. The profile of turned surface and the surface roughness value are measured by a JB-5C profilometer. Based on the profile data, D and τ∗ are computed through the root-mean-square method. The analysis of variance (ANOVA) reveals that spindle speed is the most significant factors affecting Ra, while material hardness is the most dominant parameter affecting τ∗. Material hardness and spindle speed have the same influence on D. Feed rate has less effect on three surface parameters than spindle speed and material hardness. The second-order models of RSM are established for estimating Ra, D and τ∗. The validity of the developed models is approximately 80%. The response surfaces show that a surface with small Ra and large D and τ∗ can be obtained by selecting a high speed and a large hardness material. According to the established models, Ra, D and τ∗ of six carbon steels surfaces can be predicted under cutting conditions studied in this paper. The results have an instructive meaning to estimate the surface quality before turning.

  18. Wind Tunnel Application of a Pressure-Sensitive Paint Technique to a Double Delta Wing Model at Subsonic and Transonic Speeds

    Science.gov (United States)

    Erickson, Gary E.; Gonzalez, Hugo A.

    2006-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to study the effect of wing fillets on the global vortex induced surface static pressure field about a sharp leading-edge 76 deg./40 deg. double delta wing, or strake-wing, model at subsonic and transonic speeds. Global calibrations of the PSP were obtained at M(sub infinity) = 0.50, 0.70, 0.85, 0.95, and 1.20, a Reynolds number per unit length of 2.0 million, and angles of attack from 10 degrees to 20 degrees using an insitu method featuring the simultaneous acquisition of electronically scanned pressures (ESP) at discrete locations on the model. The mean error in the PSP measurements relative to the ESP data was approximately 2 percent or less at M(sub infinity) = 0.50 to 0.85 but increased to several percent at M(sub infinity) =0.95 and 1.20. The PSP pressure distributions and pseudo-colored, planform-view pressure maps clearly revealed the vortex-induced pressure signatures at all Mach numbers and angles of attack. Small fillets having parabolic or diamond planforms situated at the strake-wing intersection were respectively designed to manipulate the vortical flows by removing the leading-edge discontinuity or introducing additional discontinuities. The fillets caused global changes in the vortex-dominated surface pressure field that were effectively captured in the PSP measurements. The vortex surface pressure signatures were compared to available off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The fillet effects on the PSP pressure distributions and the observed leading-edge vortex flow characteristics were consistent with the trends in the measured lift, drag, and pitching moment coefficients.

  19. A nozzle boundary layer model including the subsonic sublayer usable for determining boundary layer effects on plume flowfields

    Science.gov (United States)

    Cooper, B. P., Jr.

    1979-01-01

    A model for the boundary layer at the exit plane of a rocket nozzle was developed which, unlike most previous models, includes the subsonic sublayer. The equations for the flow near the nozzle exit plane are presented and the method by which the subsonic sublayer transitions to supersonic flow in the plume is described. The resulting model describes the entire boundary layer and can be used to provide a startline for method-of-characteristics calculations of plume flowfields. The model was incorporated into a method of characteristics computer program and comparisons of computed results to experimental data show good agreement. The data used in the comparisons were obtained in tests in which mass fluxes from a 22.2-N (5 lbf) thrust engine were measured at angles off the nozzle centerline of up to 150 deg. Additional comparisons were made with data obtained during tests of a 0.89-N (0.2 lbr) monopropellant thruster and from the OH-64 space shuttle heating tests. The agreement with the data indicates that the model can be used for calculating plume backflow properties.

  20. Total coloring of graphs embedded in surfaces of nonnegative Euler characteristic

    Institute of Scientific and Technical Information of China (English)

    WANG HuiJuan; LIU Bin; WU JianLiang; WANG Bing

    2014-01-01

    Let G be a graph which can be embedded in a surface of nonnegative Euler characteristic.In this paper,it is proved that the total chromatic number of G is △(G)+1 if △(G)9,where △(G)is the maximum degree of G.

  1. An investigation on the effect of surface characteristics on adhesion between polymer melts and replication tools

    DEFF Research Database (Denmark)

    Delaney, Kevin D.; Kennedy, Jonathan David; Bissacco, Giuliano

    2012-01-01

    Understanding interfacial characteristics between a polymer and its associated tool surface is critical to successful optimization of processes such as injection moulding, embossing and extrusion used to produce polymer parts. One of the factors characterizing the strength of the polymer-tool int...

  2. CHARACTERISTICS OF MOVEMENT OF SURFACE POINT IN DYNAMIC SUBSIDENCE BASIN AND ITS DEFORMATION CALCULATION

    Institute of Scientific and Technical Information of China (English)

    WANGShidao; HUANGPeizhu

    1995-01-01

    Along with underground mining, movement and deformation of overburden gradually extends in all directions and up to the ground surface and finally forms a surface subsidence basin. The surface movement progressively stabilizes until coal mining is completed and forms a stable movement basin. Two types of basins, i.e. static and dynamic subsidence basins are distinguished in the paper, a classification of the basins and a description of their characteristics are presented. Based on the analysis of measured data by Yanzhou Coal Mining Bureau, during mining operation, the movement characteristics of surface point, subsidence equation, subsidence rate equation and the law of distribution of movement parameters of surface point relative to principal section of movement basin are addressed in this paper. Moreover the calculating formula of the movement parameters for an arbitrary surface point and the expression for calculating the maximum subsidence rate are also proposed. On the basis of the findings, the movement deformation formula for an arbitrary surface point in any directions during mining operation is highlighted.

  3. Tribological Characteristic of Titanium Alloy Surface Layers Produced by Diode Laser Gas Nitriding

    Directory of Open Access Journals (Sweden)

    Lisiecki A.

    2016-06-01

    Full Text Available In order to improve the tribological properties of titanium alloy Ti6Al4V composite surface layers Ti/TiN were produced during laser surface gas nitriding by means of a novel high power direct diode laser with unique characteristics of the laser beam and a rectangular beam spot. Microstructure, surface topography and microhardness distribution across the surface layers were analyzed. Ball-on-disk tests were performed to evaluate and compare the wear and friction characteristics of surface layers nitrided at different process parameters, base metal of titanium alloy Ti6Al4V and also the commercially pure titanium. Results showed that under dry sliding condition the commercially pure titanium samples have the highest coefficient of friction about 0.45, compared to 0.36 of titanium alloy Ti6Al4V and 0.1-0.13 in a case of the laser gas nitrided surface layers. The volume loss of Ti6Al4V samples under such conditions is twice lower than in a case of pure titanium. On the other hand the composite surface layer characterized by the highest wear resistance showed almost 21 times lower volume loss during the ball-on-disk test, compared to Ti6Al4V samples.

  4. The Characteristics and Parameterization of Aerodynamic Roughness Length over Heterogeneous Surfaces

    Institute of Scientific and Technical Information of China (English)

    LU Li; LIU Shaomin; XU Ziwei; YANG Kun; CAI Xuhui; JIA Li; WANG Jiemin

    2009-01-01

    Aerodynamic roughness length (zOm) is a key factor in surface flux estimations with remote sensing algorithms and/or land surface models. This paper calculates zOm over several land surfaces, with 3 years of experimental data from Xiaotangshan. The results show that zOm is direction-dependent, mainly due to the heterogeneity of the size and spatial distribution of the roughness elements inside the source area along different wind directions. Furthermore, a heuristic parameterization of the aerodynamic roughness length for heterogeneous surfaces is proposed. Individual zOm over each surface component (patch) is calculated firstly with the characteristic parameters of the roughness elements (vegetation height, leaf area index, etc.), then zOm over the whole experimental field is aggregated, using the footprint weighting method.

  5. Surface characteristics analysis of dry EDMed AISI D2 steel using modified tool design

    Energy Technology Data Exchange (ETDEWEB)

    Pragadish, N.; Kumar, M. Pradeep [Anna University, Chennai (China)

    2015-04-15

    A modified tool design is proposed which helps in drilling holes without any central core, and also enables the effective removal of the debris particles. Experiments were conducted on AISI D2 Steel using copper electrode as tool in both conventional EDM and dry EDM processes and the performance of both processes is compared. Experiments were designed using Taguchi's L27 orthogonal array. Discharge current (I), gap voltage (V), pulse on time (T{sub ON}), gas pressure (P) and tool rotational speed (N) were chosen as the various input parameters, and their effect on the material removal rate (MRR), surface roughness (SR), surface morphology, microstructure and elemental composition of the machined surface is analyzed. The experimental results show better surface characteristics in the surface machined under dry EDM process.

  6. Comparison characteristics of surface acoustic waves propagating on LGT and quartz substrates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Guowei; SHI Wenkang; JI Xiaojun; HAN Tao

    2004-01-01

    For comprehending the propagation characteristics of surface acoustic waves (SAW) on novel piezoelectric crystal Langatate (LGT), the numerical analysis of the most important propagation characteristics of surface acoustic waves (SAW) on LGT are presented and compared with that of quartz. The results are that the phase velocity on LGT is generally about 1000 m/s slower than that on quartz; there are zero temperature cuts and pure mode directions on LGT; the electromechanical coupling coefficient (K2) of LGT is larger than that of quartz. The results show that LGT has lower propagation velocity, higher electromechanical coupling coefficient, good temperature stability and other good characteristic. The results also show that there are somewhat deviations with different material constants, especially, the temperature coefficient of frequency.

  7. Evaluation of the depth of surface deterioration for concrete structure using dispersion characteristics of surface wave

    Science.gov (United States)

    Hsu, Keng-Tsang; Cheng, Chia-Chi; Tao, Hung-Yu; Chiang, Chih-Hung

    2017-02-01

    Surface waves generated by an impact are used to assess depth of deterioration for concrete plate. The proposed method uses one receiver positioned away from the impacting source. The spectrogram of the group velocity obtained from the signal recorded from the receiver is calculated by Short-Time Fourier Transform and the reassignment technique. Experiments were conduct on the concrete plate with top mortar layer to simulate concrete with serious aggregate segregation and bleeding. In the experiment, the responses corresponding to different source-receiver distance were explored. The results were shown by both slowness spectrogram and velocity profile. In the slowness spectrogram, substantial increase of velocity at low frequency domain is found. The velocity profile shows the change of wave speed is at the wave length about 1.2 times the mortar thickness. The results also show the lower velocity corresponding to the weak layer may be identified for source-receiver distance as short as 0.5 m but the wave speed may be underestimated.

  8. Biochemical characteristics and bacterial community structure of the sea surface microlayer in the South Pacific Ocean

    Directory of Open Access Journals (Sweden)

    I. Obernosterer

    2008-05-01

    Full Text Available The chemical and biological characteristics of the surface microlayer were determined during a transect across the South Pacific Ocean in October-December 2004. Concentrations of particulate organic carbon (1.3 to 7.6-fold and nitrogen (1.4 to 7-fold, and POC:PON ratios were consistently higher in the surface microlayer as compared to surface waters (5 m. The large variability in particulate organic matter enrichment was negatively correlated to wind speed. No enhanced concentrations of dissolved organic carbon were detectable in the surface microlayer as compared to 5 m, but chromophoric dissolved organic matter was markedly enriched (by 2 to 4-fold at all sites. Based on pigment analysis and cell counts, no consistent enrichment of any of the major components of the autotrophic and heterotrophic microbial community was detectable. CE-SSCP fingerprints and CARD FISH revealed that the bacterial communities present in the surface microlayer had close similarity (>76% to those in surface waters. By contrast, bacterial heterotrophic production (3H-leucine incorporation was consistently lower in the surface microlayer than in surface waters. By applying CARD-FISH and microautoradiography, we observed that Bacteroidetes and Gammaproteobacteria dominated leucine uptake in the surface microlayer, while in surface waters Bacteroidetes and Alphaproteobacteria were the major groups accounting for leucine incorporation. Our results demonstrate that the microbial community in the surface microlayer closely resembles that of the surface waters of the open ocean. Even a short residence in the surface microlayer influences leucine incorporation by different bacterial groups, probably as a response to the differences in the physical and chemical nature of the two layers.

  9. An Assessment of Land Surface and Lightning Characteristics Associated with Lightning-Initiated Wildfires

    Science.gov (United States)

    Coy, James; Schultz, Christopher J.; Case, Jonathan L.

    2017-01-01

    Can we use modeled information of the land surface and characteristics of lightning beyond flash occurrence to increase the identification and prediction of wildfires? Combine observed cloud-to-ground (CG) flashes with real-time land surface model output, and Compare data with areas where lightning did not start a wildfire to determine what land surface conditions and lightning characteristics were responsible for causing wildfires. Statistical differences between suspected fire-starters and non-fire-starters were peak-current dependent 0-10 cm Volumetric and Relative Soil Moisture comparisons were statistically dependent to at least the p = 0.05 independence level for both polarity flash types Suspected fire-starters typically occurred in areas of lower soil moisture than non-fire-starters. GVF value comparisons were only found to be statistically dependent for -CG flashes. However, random sampling of the -CG non-fire starter dataset revealed that this relationship may not always hold.

  10. Relationships between substrate, surface characteristics, and vegetation in an initial ecosystem

    Directory of Open Access Journals (Sweden)

    P. Biber

    2013-03-01

    Full Text Available Based on a wide range of empirical data we investigated surface and vegetation dynamics in the artificial initial ecosystem "Chicken Creek" (Lusatia, Germany in the years 2008–2011. We scrutinized three different hypotheses concerning (1 the relations between initial geomorphological and substrate characteristics with surface structure and terrain properties, (2 the effects of the latter on the occurrence of grouped plant species, and (3 vegetation density effects on terrain surface change. Our data comprise annual vegetation monitoring results, terrestrial laser scans twice a year, annual groundwater levels, and initially measured soil characteristics. Using Generalized Linear Models (GLMM and Generalized Additive Mixed Models (GAMM we can mostly confirm our hypotheses, revealing statistically significant relations that partly reflect object or period specific effects but also more general processes which mark the transition from a geo-hydro towards a bio-geo-hydro system, where pure geomorphology or substrate feedbacks are changing into vegetation-substrate feedback processes.

  11. Electrochemical Characteristics of Titanium for Dental Implants in Case of the Electroless Surface Modification

    Directory of Open Access Journals (Sweden)

    Klimecka-Tatar D.

    2016-06-01

    Full Text Available In the paper the results of research under effect of electroless phosphate coating of titanium dental implants on potentiokinetic polarization characteristic obtained in artificial saliva were presented. On the basis of electrochemical studies it was concluded that the electroless process of phosphating beneficialy effect on corrosion characteristic of titanium determined in solution simulating the oral cavity. Furthermore, the proposed technique of chemical treatment of titanium surface is conducive to the homogeneous development of the surface, which is extremely important from the point of view of titanium implants biointegration. Phosphating treatment affect on the development of surface geometry, resulting in a slight increase in roughness parameters (Ra, Rz and Rmax. The temperature increase of electroless phosphating treatment promotes the rate of conversion layer formation, whereas the effect of temperature of the chemical treatment efficiency is secondary important at longer exposure times (e.g. 45 minutes.

  12. Effect of random surface errors on radiation characteristics of the side-fed offset Cassegrain antenna

    Institute of Scientific and Technical Information of China (English)

    LIU Shao-dong; JIAO Yong-chang; ZHANG Fu-shun

    2006-01-01

    In this paper the average power pattern of the side-fed offset Cassegrain (SFOC) dual reflector antenna is analyzed,and the effect of the random surface error on radiation characteristics of the antenna is introduced.Here,the random surface error is defined as the error of the standard reflector in its normal direction and the errors in a small zone of the reflector are considered as equal.We also assume that the phase error on the aperture led by the random surface error obeys a Gaussian distribution with zero mean,under which the expression of the average power pattern is deduced.Finally,the data related to the radiation characteristics of the antenna are calculated and the corresponding curves are presented.The obtained results can be used for the user to determine the manufacturing accuracy of the reflector of the SFOC antennas.

  13. On the characteristics of ion implanted metallic surfaces inducing dropwise condensation of steam.

    Science.gov (United States)

    Rausch, Michael H; Leipertz, Alfred; Fröba, Andreas P

    2010-04-20

    The present work provides new information on the characteristics of ion implanted metallic surfaces responsible for the adjustment of stable dropwise condensation (DWC) of steam. The results are based on condensation experiments and surface analyses via contact angle (CA) and surface free energy (SFE) measurements as well as scanning electron microscopy (SEM). For studying possible influences of the base material and the implanted ion species, commercially pure titanium grade 1, aluminum alloy Al 6951, and stainless steel AISI 321 were treated with N(+), C(+), O(+), or Ar(+) using ion beam implantation technology. The studies suggest that chemically inhomogeneous surfaces are instrumental in inducing DWC. As this inhomogeneity is apparently caused by particulate precipitates bonded to the metal surface, the resulting nanoscale surface roughness may also influence the condensation form. On such surfaces nucleation mechanisms seem to be capable of maintaining DWC even when CA and SFE measurements indicate increased wettability. The precipitates are probably formed due to the supersaturation of ion implanted metal surfaces with doping elements. For high-alloyed materials like AISI 321 or Hastelloy C-276, oxidation stimulated by the condensation process obviously tends to produce similar surfaces suitable for DWC.

  14. Aging Characteristics on Epoxy Resin Surface Under Repetitive Microsecond Pulses in Air at Atmospheric Pressure

    Science.gov (United States)

    Xie, Qing; Liu, Xiong; Zhang, Cheng; Wang, Ruixue; Rao, Zhangquan; Shao, Tao

    2016-03-01

    Research on aging characteristics of epoxy resin (EP) under repetitive microsecond pulses is important for the design of insulating materials in high power apparatus. It is because that very fast transient overvoltage always occurs in a power system, which causes flashover and is one of the main factors causing aging effects of EP materials. Therefore, it is essential to obtain a better understanding of the aging effect on an EP surface resulting from flashover. In this work, aging effects on an EP surface were investigated by surface flashover discharge under repetitive microsecond pulses in atmospheric pressure. The investigations of parameters such as the surface micro-morphology and chemical composition of the insulation material under different degrees of aging were conducted with the aid of measurement methods such as atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Results showed that with the accumulation of aging energy on the material surface, the particles formed on the material surface increased both in number and size, leading to the growth of surface roughness and a reduction in the water contact angle; the surface also became more absorbent. Furthermore, in the aging process, the molecular chains of EP on the surface were broken, resulting in oxidation and carbonisation. supported by the Natural Science Foundation of Hebei Province (No. E2015502081), National Natural Science Foundation of China (Nos. 51222701, 51307060), and the National Basic Research Program of China (No. 2014CB239505-3)

  15. Three-Dimensional Inviscid Flow About Supersonic Blunt Cones at Angle of Attack - III: Coupled Subsonic and Supersonic Programs for Inviscid Three-Dimensional Flow

    Energy Technology Data Exchange (ETDEWEB)

    Abbett, M. J.; Fort, R.

    1968-09-01

    The three-dimensional ideal gas flow in the shock layer of a blunted supersonic cone at an angle of attack is calculated using two asymptotic solutions. The first solution calculates the steady state flow in the subsonic nose region by obtaining a time-dependent solution of the hyperbolic equations using numerical techniques. Internal, nonboundary points are calculated using a Lax-Wendroff numerical type technique. Boundary points, shock and body surface, are computed using a time-dependent method of characteristics. When a steady state solution is reached the flow properties on a surface of constant {theta}, (where the Mach number is everywhere > 1) are used for initial data for the afterbody solution. The afterbody solution, using polar coordinates (r, {theta}, {phi}) assumes at r{sub 0} an arbitrary set of initial conditions provided by the nose region solution and computes the downstream flow as a function of {theta}, {phi}, and r until an asymptotic state independent of r develops. The interior mesh points are again calculated using a Lax- Wendroff type technique and the boundary points by a method of characteristics. This report covers the coupling of the time-dependent and radius (r) dependent solutions. Instructions are given for the operation of the resulting Fortran code. The type of input data required is detailed and sample output is provided. Output data is given in two sets of coordinates. One is wind orientated; the other set is given in body orientated coordinates; The analytical transformation from one coordinate system to the other is given.

  16. Influence of skin surface roughness degree on energy characteristics of light scattered by a biological tissue

    Science.gov (United States)

    Barun, V. V.; Ivanov, A. P.

    2017-05-01

    We present the results of modelling of photometric characteristics of light in soft tissues illuminated by a parallel beam along the normal to the surface, obtained with allowance for the skin roughness parameters and the angular structure of radiation approaching the surface from within the tissue. The depth structure of the fluence rate and the spectra of the diffuse reflection of light by the tissue in the interval of wavelengths 300 - 1000 nm are considered. We discuss the influence of the tilt angle variance of rough surface microelements and light refraction on the studied characteristics. It is shown that these factors lead to the reduction of the radiation flux only in the near-surface tissue layer and practically do not affect the depth of light penetration into the tissue. On the other hand, the degree of the surface roughness and the conditions of its illumination from within the tissue essentially affect the coefficient of diffuse reflection of light and lead to its considerable growth compared to the cases of a smooth interface and completely diffuse illumination, often considered to simplify the theoretical problem solution. The role of the roughness of skin surface is assessed in application to the solution of different direct and inverse problems of biomedical optics.

  17. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy.

    Science.gov (United States)

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2016-01-01

    Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autoclave, 1 autoclave cycle, 5 autoclave cycles and 10 autoclave cycles) by SEM under 200× and 1000× magnifications. Data were analyzed using the SPSS software and the paired sample t-test, independent sample t-test and multifactorial repeated measures ANOVA. The level of significance was set at 0.05. New files had debris and pitting on their surfaces. When the autoclave cycles were increased, the mean of surface roughness also increased at both magnifications (Pautoclave increased the surface roughness of the files and this had was directly related to the number of autoclave cycles.

  18. Sub-sonic thermal explosions investigated by radiography

    Energy Technology Data Exchange (ETDEWEB)

    Smilowitz, Laura B [Los Alamos National Laboratory; Henson, Bryan F [Los Alamos National Laboratory; Romero, Jerry J [Los Alamos National Laboratory; Asay, Blaine W [Los Alamos National Laboratory

    2010-01-01

    This paper reviews the past 5 years of experiments utilizing radiographic techniques to study defiagration in thermal explosions in HMX based formulations. Details of triggering and timing synchronization are given. Radiographic images collected using both protons and x-rays are presented. Comparisons of experiments with varying size, case confinement, binder, and synchronization are presented. Techniques for quantifying the data in the images are presented and a mechanism for post-ignition burn propagation in a thermal explosion is discussed. From these experiments, we have observed a mechanism for sub-sonic defiagration with both gas phase convective and solid phase conductive burning. The convective front velocity is directly measured from the radiographic images and consumes only a small fraction of the HE. It lights the HE as it passes beginning the slower solid state conductive burn process. This mechanism is used to create a model to simulate the radiographic results and a comparison will be shown.

  19. Study on the subsonic speed flame spraying coating of hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new method of preparation of biomaterial composite coating by the technique of subsonic thermal sprayingwas discussed in this paper. Ti6A14V and pure Ti were chosen as substrate and sublayer material respectively and the work-ing layer was sprayed with biomaterial hydroxyapatite (HAP), forming the composite coating. The experiments of heatshock and tensile strength showed that the bonding strength between coating and substrate is almost as same as that of spe-cimen in which Ni/Al powder was adopted as sublayer. The phases of TiN, TiO2, and Ti2O3 were formed in the sublayer,which are free of toxic and have no side effects. The powder of working layer HAP was decomposed partly during spraying,but it can be solved by later treatment.

  20. Evaluation of the Advanced Subsonic Technology Program Noise Reduction Benefits

    Science.gov (United States)

    Golub, Robert A.; Rawls, John W., Jr.; Russell, James W.

    2005-01-01

    This report presents a detailed evaluation of the aircraft noise reduction technology concepts developed during the course of the NASA/FAA Advanced Subsonic Technology (AST) Noise Reduction Program. In 1992, NASA and the FAA initiated a cosponsored, multi-year program with the U.S. aircraft industry focused on achieving significant advances in aircraft noise reduction. The program achieved success through a systematic development and validation of noise reduction technology. Using the NASA Aircraft Noise Prediction Program, the noise reduction benefit of the technologies that reached a NASA technology readiness level of 5 or 6 were applied to each of four classes of aircraft which included a large four engine aircraft, a large twin engine aircraft, a small twin engine aircraft and a business jet. Total aircraft noise reductions resulting from the implementation of the appropriate technologies for each class of aircraft are presented and compared to the AST program goals.

  1. Investigation of electrical characteristics of no-insulation coil wound with surface-processed HTS tape

    Science.gov (United States)

    Jeon, Haeryong; Lee, Woo Seung; Kim, Jinsub; Baek, Geonwoo; Jeon, Sangsu; Yoon, Yong Soo; Ko, Tae Kuk

    2017-08-01

    This paper deals with the electrical characteristics of no-insulation coil wound with surface-processed HTS tape. The bypassing current path through turn-to-turn contacts within a coil is formed in the no-insulation coil, and this bypassing current path determines two characteristics: 1) self-protection and 2) charge-discharge delay. The amplitude of bypassing current is determined by contact resistance between the turn-to-turn contacts of the no-insulation coil. The surface roughness of the HTS tape is one of the parameters to change the contact resistance. The HTS tapes were processed to roughen by bead blast and abrasive paper, and the no-insulation coil is fabricated using processed HTS tape. We have studied the charge-discharge delay and self-protecting characteristic of each no-insulation coil by 1) sudden discharge tests and 2) overcurrent tests. The FEM simulations of contact resistance of no-insulation coil were carried out. The contact surface resistance of a case processed by abrasive paper has almost three times larger than that of reference no-insulation coil, and a case processed by bead blast presents almost same contact surface resistance with reference no-insulation coil.

  2. Wintertime land surface characteristics in climatic simulations over the western Himalayas

    Indian Academy of Sciences (India)

    A P Dimri

    2012-04-01

    Wintertime regional climate studies over the western Himalayas with ICTP-RegCM3 simulations through 22 years has shown systematic biases in precipitation and temperature fields. The model simulated precipitation shows systematically wet bias. In surface temperature simulations, positive and negative biases of 2°–4°C occurred. Experiment without (CONT) and with subBATS (SUB) shows that later scheme performs better, especially for precipitation. Apart from the role of topography and model internal variability, land surface characteristics also have profound impact on these climatic variables. Therefore, in the present study, impacts of land surface characteristics are investigated through cool/wet and warm/dry winter climate by CONT and SUB simulations to assess systematic biases. Since SUB experiment uses detailed land-use classification, systematic positive biases in temperature over higher elevation peaks are markedly reduced. The change has shown reduced excessive precipitation as well. Most of the surface characteristics show that major interplay between topography and western disturbances (WDs) takes place along the foothills rather than over the higher peaks of the western Himalayas.

  3. Surface accuracy and radiation pattern characteristics of mesh deployable refector antennas

    Science.gov (United States)

    Ueno, Miyoshi; Ebisui, Takashi; Okamato, Teruki; Orikasa, Teruaki; Sugimoto, Toshio; Iso, Akio

    To facilitate the growth of mobile satellite communications, both an increase in the Equivalent Isotropically Radiated Power (EIRP) of satellites and improved frequency reuse are required to achiveve compact size, low cost terminal usage, and high channel capacity. High gain and low sidelobe antenna technology are very important for high EIRP and frequency reuse, respectively. These requirements are expected to be met by using a large deployable mesh reflector antenna, which is the key technology for future multibeam moble communications systems. In this paper, surface accruracy and related electrical characteristics are studied using a TETRUS-(Tetra Trigonal Prism Truss) type deployable mesh reflector antenna. Surface accuracy and related electrical characteristics of reflector antennas becaue any distortion of the ideal paraboloidal configuration causes antenna patterns to deteriorate, thereby reducing reflector aperture efficiency and increasing sidelobe and grating lobe levels. The sidelobe and grating lobe characteristics are especially important in frequency reuse. First, we show the problem with the radiation pattern characteristics of TETUS antenna. We then propose a new antenna configuration called the 'HYBRID TETRUS' that improves these characteristics. The mechanical performances of two partial deployable models are also described. Mechanical testing results reveal agreement between the calculated and measured values and high rigidities.

  4. Design of Rotary Atomizer Using Characteristics of Thin Film Flow on Solid Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Park, Boo Seong; Kim, Bo Hung [Univ. of Ulsan, Ulsan (Korea, Republic of)

    2013-12-15

    A disc-type rotary atomizer affords advantages such as superior paint transfer efficiency, uniformity of paint pattern and particle size, and less consumption of compressed air compared to a spray-gun-type atomizer. Furthermore, it can be applied to all types of painting materials, and it is suitable for large-scale processes such as car painting. The painting quality, which is closely related to the atomizer performance, is determined by the uniformity and droplet size in accordance with the design of the bell disc surface. This study establishes the basics of how to design a surface by modeling the operating bell disc's RPM, diameter, surface angle, and film thickness considering dye characteristics such as the viscosity, density, and surface affinity.

  5. Analysis of Wetting Characteristics on Microstructured Hydrophobic Surfaces for the Passive Containment Cooling System

    Directory of Open Access Journals (Sweden)

    Wei Zhao

    2015-01-01

    Full Text Available As the heat transfer surface in the passive containment cooling system, the anticorrosion coating (AC of steel containment vessel (CV must meet the requirements on heat transfer performance. One of the wall surface ACs with simple structure, high mechanical strength, and well hydrophobic characteristics, which is conductive to form dropwise condensation, is significant for the heat removal of the CV. In this paper, the grooved structures on silicon wafers by lithographic methods are systematically prepared to investigate the effects of microstructures on the hydrophobic property of the surfaces. The results show that the hydrophobicity is dramatically improved in comparison with the conventional Wenzel and Cassie-Baxter model. In addition, the experimental results are successfully explained by the interface state effect. As a consequence, it is indicated that favorable hydrophobicity can be obtained even if the surface is with lower roughness and without any chemical modifications, which provides feasible solutions for improving the heat transfer performance of CV.

  6. Temperature characteristics of InGaAs/GaAs vertical cavity surface emitting laser

    Institute of Scientific and Technical Information of China (English)

    QU Hong-wei; GUO Xia; DONG Li-min; WANG Hong-hang; DENG Jun; LIAN Peng; ZHOU De-shu; SHEN Guang-di

    2005-01-01

    The temperature characteristics for the different lasing modes at 300 K of intracavity contacted InGaAs/GaAs Vertical Cavity Surface Emitting Lasers(VCSELs) have been investigated experimentally by using the SV-32 cryostat and LD2002C5 test system.In combination with the simulation results of the reflective spectrum and the gain peak at different temperatures,the measurement results have been analyzed.In addition,the dependence of device size on temperature characteristics is discussed.The experimental data can be used to optimally design of VCSEL at high or cryogenic temperature.

  7. Influence of Fine Metal Particles on Surface Discharge Characteristics of Outdoor Insulators

    Directory of Open Access Journals (Sweden)

    Yong Liu

    2016-01-01

    Full Text Available Focusing on the influence of fine metal particles on the insulation characteristics of outdoor insulators, spherical micrometer-level iron powders were used to represent fine metal particles of different parameters on a polymer insulator specimen surface. Dynamic movement and lift-off behavior of fine particles, as well as the triggered surface discharges under AC voltage were investigated in a uniform electric field under different experimental conditions. The results reveal that the inception, propagation and intensity of surface discharges are significantly affected by the particle parameters, including particle size, amount and distributing characteristic. Based on the measurement of light emission during the flashover process using a high-speed camera, the process of surface discharge to flashover triggered by the fine metal particles were investigated to obtain a relationship between flashover voltage, discharge light intensity and particle parameters. It is suggested that particle size smaller than 28 µm and particle amount more than 40 mg in contact with the non-uniform distribution can cause a significant distortion and intensification of the electric field resulting in a higher risk of surface discharges leading to flashover. Such investigations can enhance the operating reliability of outdoor insulators subjected to these conditions.

  8. Investigation of dynamic characteristics of a rotor system with surface coatings

    Science.gov (United States)

    Yang, Yang; Cao, Dengqing; Wang, Deyou

    2017-02-01

    A Jeffcott rotor system with surface coatings capable of describing the mechanical vibration resulting from unbalance and rub-impact is formulated in this article. A contact force model proposed recently to describe the impact force between the disc and casing with coatings is employed to do the dynamic analysis for the rotor system with rubbing fault. Due to the variation of penetration, the contact force model is correspondingly modified. Meanwhile, the Coulomb friction model is applied to simulate the friction characteristics. Then, the case study of rub-impact with surface coatings is simulated by the Runge-Kutta method, in which a linear interpolation method is adopted to predict the rubbing instant. Moreover, the dynamic characteristics of the rotor system with surface coatings are analyzed in terms of bifurcation plot, waveform, whirl orbit, Poincaré map and spectrum plot. And the effects of the hardness of surface coatings on the response are investigated as well. Finally, compared with the classical models, the modified contact force model is shown to be more suitable to solve the rub-impact of aero-engine with surface coatings.

  9. Thermal Characteristics of a Primary Surface Heat Exchanger with Corrugated Channels

    OpenAIRE

    2015-01-01

    This paper presents the heat transfer and pressure drop characteristics of a primary surface heat exchanger (PSHE) with corrugated surfaces. The PSHE was experimentally investigated for a Reynolds number range of 156–921 under various flow conditions on the hot and cold sides. The inlet temperature of the hot side was maintained at 40 °C, while that of the cold side was maintained at 20 °C. A counterflow was used as it has a higher temperature proximity in comparison with a parallel flow. The...

  10. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    Science.gov (United States)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  11. Fractal characteristics investigation on electromagnetic scattering from 2-D Weierstrass fractal dielectric rough surface

    Institute of Scientific and Technical Information of China (English)

    Ren Xin-Cheng; Guo Li-Xin

    2008-01-01

    A normalized two-dimensional band-limited Weierstrass fractal function is used for modelling the dielectric rough surface. An analytic solution of the scattered field is derived based on the Kirchhoff approximation. The variance of scat-tering intensity is presented to study the fractal characteristics through theoretical analysis and numerical calculations. The important conclusion is obtained that the diffracted envelope slopes of scattering pattern can be approximated as a slope of linear equation. This conclusion will be applicable for solving the inverse problem of reconstructing rough surface and remote sensing.

  12. Mechanical theorem proving in the surfaces using the characteristic set method and Wronskian determinant

    Institute of Scientific and Technical Information of China (English)

    FENG RuYong; YU JianPing

    2008-01-01

    In this paper,we generalize the method of mechanical theorem proving in curves to prove theorems about surfaces in differential geometry with a mechanical procedure.We improve the classical result on Wronskian determinant,which can be used to decide whether the elements in a partial differential field are linearly dependent over its constant field.Based on Wronskian determinant,we can describe the geometry statements in the surfaces by an algebraic language and then prove them by the characteristic set method.

  13. Acoustic Prediction Methodology and Test Validation for an Efficient Low-Noise Hybrid Wing Body Subsonic Transport

    Science.gov (United States)

    Kawai, Ronald T. (Compiler)

    2011-01-01

    This investigation was conducted to: (1) Develop a hybrid wing body subsonic transport configuration with noise prediction methods to meet the circa 2007 NASA Subsonic Fixed Wing (SFW) N+2 noise goal of -52 dB cum relative to FAR 36 Stage 3 (-42 dB cum re: Stage 4) while achieving a -25% fuel burned compared to current transports (re :B737/B767); (2) Develop improved noise prediction methods for ANOPP2 for use in predicting FAR 36 noise; (3) Design and fabricate a wind tunnel model for testing in the LaRC 14 x 22 ft low speed wind tunnel to validate noise predictions and determine low speed aero characteristics for an efficient low noise Hybrid Wing Body configuration. A medium wide body cargo freighter was selected to represent a logical need for an initial operational capability in the 2020 time frame. The Efficient Low Noise Hybrid Wing Body (ELNHWB) configuration N2A-EXTE was evolved meeting the circa 2007 NRA N+2 fuel burn and noise goals. The noise estimates were made using improvements in jet noise shielding and noise shielding prediction methods developed by UC Irvine and MIT. From this the Quiet Ultra Integrated Efficient Test Research Aircraft #1 (QUIET-R1) 5.8% wind tunnel model was designed and fabricated.

  14. Relationship between wettability and lubrication characteristics of the surfaces of contacting phospholipid-based membranes.

    Science.gov (United States)

    Pawlak, Zenon; Petelska, Aneta D; Urbaniak, Wieslaw; Yusuf, Kehinde Q; Oloyede, Adekunle

    2013-04-01

    The wettability of the articular surface of cartilage depends on the condition of its surface active phospholipid overlay, which is structured as multi-bilayer. Based on a hypothesis that the surface of cartilage facilitates the almost frictionless lubrication of the joint, we examined the characteristics of this membrane surface entity in both its normal and degenerated conditions using a combination of atomic force microscopy, contact angle measurement, and friction test methods. The observations have led to the conclusions that (1) the acid-base equilibrium condition influences the lubrication effectiveness of the surface of cartilage and (2) the friction coefficient is significantly dependent on the hydrophobicity of the surface of the tissue, thereby confirming the hypothesis tested in this paper. Both wettability angle and interfacial energy were obtained for varying conditions of the cartilage surface both in its wet, dry and lipid-depleted conditions. The interfacial energy also increased with mole fraction of the lipid species reaching an asymptotic value after 0.6. Also, the friction coefficient was found to decrease to an asymptotic level as the wettability angle increased. The result reveal that the interfacial energy increased with pH till pH = 4.0, and then decreased from pH = 4.0 to reach equilibrium at pH = 7.0.

  15. The influence of surface characteristics, topography, and continentality on mountain permafrost in British Columbia

    Directory of Open Access Journals (Sweden)

    A. Hasler

    2014-09-01

    Full Text Available Thermal offset and surface offset are terms that describe the deviation of the mean annual ground temperature from the mean annual air temperature. These offsets are controlled by surface characteristics and topo-climatic factors on a micro- and meso-scales. Macro-climatic conditions may, however, influence the effectiveness of the responsible processes. Existing knowledge on surface- and topography-specific offsets is not easily transferable and limits the applicability of empirical permafrost distribution models over large areas with macro-climatic gradients. In this paper we describe surface and thermal offsets derived from distributed measurements at seven field sites in British Columbia. Key findings are (i a surprisingly small variation of the surface offsets between different surface types and small thermal offsets in general (excluding wetlands and peat, (ii a clear influence of the micro-topography at wind exposed sites (snow cover erosion, (iii a north–south difference of the surface offset of 4 °C in near-vertical bedrock and of 1.5–3 °C on open (no canopy gentle slopes, (iv only small macro-climatic differences caused by the reverse influence of snow cover thickness and annual air temperature amplitude. These findings suggest, that empirical permafrost models based on topo-climatic variables may be applicable across regions with significant macro-climatic differences.

  16. Nanoscale surface modifications to control capillary flow characteristics in PMMA microfluidic devices

    Directory of Open Access Journals (Sweden)

    Mukhopadhyay Subhadeep

    2011-01-01

    Full Text Available Abstract Polymethylmethacrylate (PMMA microfluidic devices have been fabricated using a hot embossing technique to incorporate micro-pillar features on the bottom wall of the device which when combined with either a plasma treatment or the coating of a diamond-like carbon (DLC film presents a range of surface modification profiles. Experimental results presented in detail the surface modifications in the form of distinct changes in the static water contact angle across a range from 44.3 to 81.2 when compared to pristine PMMA surfaces. Additionally, capillary flow of water (dyed to aid visualization through the microfluidic devices was recorded and analyzed to provide comparison data between filling time of a microfluidic chamber and surface modification characteristics, including the effects of surface energy and surface roughness on the microfluidic flow. We have experimentally demonstrated that fluid flow and thus filling time for the microfluidic device was significantly faster for the device with surface modifications that resulted in a lower static contact angle, and also that the incorporation of micro-pillars into a fluidic device increases the filling time when compared to comparative devices.

  17. Surface characteristics, corrosion and bioactivity of chemically treated biomedical grade NiTi alloy.

    Science.gov (United States)

    Chembath, Manju; Balaraju, J N; Sujata, M

    2015-11-01

    The surface of NiTi alloy was chemically modified using acidified ferric chloride solution and the characteristics of the alloy surface were studied from the view point of application as a bioimplant. Chemically treated NiTi was also subjected to post treatments by annealing at 400°C and passivation in nitric acid. The surface of NiTi alloy after chemical treatment developed a nanogrid structure with a combination of one dimensional channel and two dimensional network-like patterns. From SEM studies, it was found that the undulations formed after chemical treatment remained unaffected after annealing, while after passivation process the undulated surface was filled with oxides of titanium. XPS analysis revealed that the surface of passivated sample was enriched with oxides of titanium, predominantly TiO2. The influence of post treatment on the corrosion resistance of chemically treated NiTi alloy was monitored using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) in Phosphate Buffered Saline (PBS) solution. In the chemically treated condition, NiTi alloy exhibited poor corrosion resistance due to the instability of the surface. On the other hand, the breakdown potential (0.8V) obtained was highest for the passivated samples compared to other surface treated samples. During anodic polarization, chemically treated samples displayed dissolution phenomenon which was predominantly activation controlled. But after annealing and passivation processes, the behavior of anodic polarization was typical of a diffusion controlled process which confirmed the enhanced passivity of the post treated surfaces. The total resistance, including the porous and barrier layer, was in the range of mega ohms for passivated surfaces, which could be attributed to the decrease in surface nickel content and formation of compact titanium oxide. The passivated sample displayed good bioactivity in terms of hydroxyapatite growth, noticed after 14days immersion in

  18. Pulsatory characteristics of wind velocity in sand flow over typical underlying surfaces

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Pulsatory characteristics of wind velocity in sand flow over Gobi and mobile sand surface have been investigated experimentally in the wind tunnel. The primary goal of this paper is to reveal the relation- ship between pulsatory characteristics of instantaneous wind speed in sand flow and the motion state of sand grains. For a given underlying surface, pulsation of wind velocities in sand flow on different heights has a good correlation. As the space distance among different heights increases, fluctuation of instantaneous wind speed presents a decreasing trend and its amplitude is closely related to the mo- tion state of sand grains and their transport. Pulsatory intensity increases with the indicated wind speed, but its relative value does not depend on it, only agrees with height.

  19. The Porpoising Characteristics of a Planing Surface Representing the Forebody of a Flying-Boat Hull

    Science.gov (United States)

    Benson, James M.

    1942-01-01

    Porpoising characteristics were observed on V-body fitted with tail surfaces for different combinations of load, speed, moment of inertia, location of pivot, elevator setting, and tail area. A critical trim was found which was unaltered by elevator setting or tail area. Critical trim was lowered by moving pivot either forward or down or increasing radius or gyration. Increase in mass and moment of inertia increased amplitude of oscillations. Complete results are tabulated and shown graphically.

  20. A general theory of two- and three-dimensional rotational flow in subsonic and transonic turbomachines

    Science.gov (United States)

    Wu, Chung-Hua

    1993-01-01

    This report represents a general theory applicable to axial, radial, and mixed flow turbomachines operating at subsonic and supersonic speeds with a finite number of blades of finite thickness. References reflect the evolution of computational methods used, from the inception of the theory in the 50's to the high-speed computer era of the 90's. Two kinds of relative stream surfaces, S(sub 1) and S(sub 2), are introduced for the purpose of obtaining a three-dimensional flow solution through the combination of two-dimensional flow solutions. Nonorthogonal curvilinear coordinates are used for the governing equations. Methods of computing transonic flow along S(sub 1) and S(sub 2) stream surfaces are given for special cases as well as for fully three-dimensional transonic flows. Procedures pertaining to the direct solutions and inverse solutions are presented. Information on shock wave locations and shapes needed for computations are discussed. Experimental data from a Deutsche Forschungs- und Versuchsanstalt fur Luft- und Raumfahrt e.V. (DFVLR) rotor and from a Chinese Academy of Sciences (CAS) transonic compressor rotor are compared with the computed flow properties.

  1. Optimized aerodynamic design process for subsonic transport wing fitted with winglets. [wind tunnel model

    Science.gov (United States)

    Kuhlman, J. M.

    1979-01-01

    The aerodynamic design of a wind-tunnel model of a wing representative of that of a subsonic jet transport aircraft, fitted with winglets, was performed using two recently developed optimal wing-design computer programs. Both potential flow codes use a vortex lattice representation of the near-field of the aerodynamic surfaces for determination of the required mean camber surfaces for minimum induced drag, and both codes use far-field induced drag minimization procedures to obtain the required spanloads. One code uses a discrete vortex wake model for this far-field drag computation, while the second uses a 2-D advanced panel wake model. Wing camber shapes for the two codes are very similar, but the resulting winglet camber shapes differ widely. Design techniques and considerations for these two wind-tunnel models are detailed, including a description of the necessary modifications of the design geometry to format it for use by a numerically controlled machine for the actual model construction.

  2. Theoretical prediction of interference loading on aircraft stores: Part I - Subsonic speeds

    Science.gov (United States)

    Fox, C. H., Jr.; Fernandes, F.

    1973-01-01

    Computer program is developed for theoretically predicting loading on pylon-mounted stores in subsonic compressible flow. Linear theory predicts flow field produced by aircraft wing, nose, inlet, and pylons. Program was written in FORTRAN IV for CDC 6000 computer.

  3. Biochemical characteristics and bacterial community structure of the sea surface microlayer in the South Pacific Ocean

    Directory of Open Access Journals (Sweden)

    I. Obernosterer

    2007-08-01

    Full Text Available The chemical and biological characteristics of the surface microlayer were determined during a transect across the South Pacific Ocean in October-December 2004. Concentrations of particulate organic carbon (1.3 to 7.6-fold and nitrogen (1.4 to 7, and POC:PON ratios were consistently higher in the surface microlayer as compared to subsurface waters (5 m. The large variability in particulate organic matter enrichment was negatively correlated to wind speed. No enhanced concentrations of dissolved organic carbon were detectable in the surface microlayer as compared to 5 m, but chromophoric dissolved organic matter was markedly enriched (by 2 to 4-fold at all sites. Based on pigment analysis and cell counts, no consistent enrichment of any of the major components of the autotrophic and heterotrophic microbial community was detectable. CE-SSCP fingerprints and CARD FISH revealed that the bacterial communities present in the surface microlayer had close similarity (>76% to those in subsurface waters. By contrast, bacterial heterotrophic production (3H-leucine incorporation was consistently lower in the surface microlayer than in subsurface waters. By applying CARD-FISH and microautoradiography, we observed that Bacteroidetes and Gammaproteobacteria dominated leucine uptake in the surface microlayer, while in subsurface waters Bacteroidetes and Alphaproteobacteria were the major groups accounting for leucine incorporation. Our results demonstrate that the microbial community in the surface microlayer closely resembles that of the surface waters of the open ocean. However, even short time periods in the surface microlayer result in differences in bacterial groups accounting for leucine incorporation, probably as a response to the differences in the physical and chemical nature of the two layers.

  4. A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight

    Science.gov (United States)

    2014-07-01

    motions of the projectile about the trajectory due to the angular motion of the projectile . For a stable projectile , these motions are typically small...A Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight by Paul Weinacht ARL-TR-6998 July 2014...Direct-Fire Trajectory Model for Supersonic, Transonic, and Subsonic Projectile Flight Paul Weinacht Weapons and Materials Research Directorate, ARL

  5. Effect of radiation light characteristics on surface hardness of paint-on resin for shade modification.

    Science.gov (United States)

    Arikawa, Hiroyuki; Kanie, Takahito; Fujii, Koichi; Ban, Seiji

    2005-12-01

    The purpose of this study was to investigate the effect of radiation light characteristics--of different types of clinical light-curing unit--on polymerization efficiency, as determined by the surface hardness of light-cured paint-on resins. Four shades of paint-on resin for shade modification of restorative resins were used. Materials were cured using one laboratory and three clinical light-curing units with different light sources, namely tungsten-halogen, LED, plasma arc, and xenon flash lamps. Knoop hardness measurements were taken at both the top and bottom surfaces of the specimens to assess the mechanical properties and degree of polymerization. Both LED and plasma arc light units caused significantly poorer surface hardness than the halogen and laboratory xenon lights. In addition, the transparent shade was more sensitive to surface hardness than other chromatic shades. Our results indicated that the polymerization efficiency of paint-on resin was significantly influenced by the radiation light characteristics of clinical light-curing units.

  6. Relationship between antibacterial activity of chitosan and surface characteristics of cell wall

    Institute of Scientific and Technical Information of China (English)

    Ying-chien CHUNG; Ya-ping SU; Chiing-chang CHEN; Guang JIA; Huey-lan WANG; J C Gaston WU; Jaung-geng LIN

    2004-01-01

    AIM: Five representative waterborne pathogens were used to illustrate the relationship between chitosan's antibacterial activity and the surface characteristics of the bacterial cell wall. METHODS: Chitosan was prepared with averaged 75 % or 95 % deacetylated degree to examine its antibacterial activity against waterborne pathogens.Fresh microbial inoculants for the antibacterial assessment were prepared on nutrient agar at 37 °C for 24 h. The evaluation items of antibacterial mechanism included hydrophilicity and negative charge analysis of cell surface, and adsorptive characteristics of chitosan to bacterial cell. All the experiments were applied in triplicate tests at least.RESULTS: Although cell wall hydrophilicity was similar among Gram-negative bacteria, the distribution of negative charge on their cell surfaces was quite different. More negatively charged cell surfaces had a greater interaction with chitosan, a phenomenon further confirmed by transmission electron micrography (TEM). CONCLUSION:Results showed the hydrophilicity in Gram-negative bacteria was much higher than in Gram-positive ones. The correlation coefficient 0.988 between the amount of absorbed chitosan and its inhibition efficiency indicated a close relationship.

  7. Surface transfer doping induced effective modulation on ambipolar characteristics of few-layer black phosphorus

    Science.gov (United States)

    Xiang, Du; Han, Cheng; Wu, Jing; Zhong, Shu; Liu, Yiyang; Lin, Jiadan; Zhang, Xue-Ao; Ping Hu, Wen; Özyilmaz, Barbaros; Neto, A. H. Castro; Wee, Andrew Thye Shen; Chen, Wei

    2015-03-01

    Black phosphorus, a fast emerging two-dimensional material, has been configured as field effect transistors, showing a hole-transport-dominated ambipolar characteristic. Here we report an effective modulation on ambipolar characteristics of few-layer black phosphorus transistors through in situ surface functionalization with caesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3), respectively. Cs2CO3 is found to strongly electron dope black phosphorus. The electron mobility of black phosphorus is significantly enhanced to ~27 cm2 V-1 s-1 after 10 nm Cs2CO3 modification, indicating a greatly improved electron-transport behaviour. In contrast, MoO3 decoration demonstrates a giant hole-doping effect. In situ photoelectron spectroscopy characterization reveals significant surface charge transfer occurring at the dopants/black phosphorus interfaces. Moreover, the surface-doped black phosphorus devices exhibit a largely enhanced photodetection behaviour. Our findings coupled with the tunable nature of the surface transfer doping scheme ensure black phosphorus as a promising candidate for further complementary logic electronics.

  8. [Residue characteristics and distributions of perfluorinated compounds in surface seawater along Shenzhen coastline].

    Science.gov (United States)

    Chen, Qing-Wu; Zhang, Hong; Chai, Zhi-Fang; Shen, Jin-Can; Yang, Bo

    2012-06-01

    In order to explore the residue characteristics and distributions of 15 perfluorinated compounds (PFCs) in 18 surface seawater samples along Shenzhen coastline, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) combined with solid phase extraction enrichment was applied in this research. The results indicated that residue level of PFCs in coastal surface seawater samples was significantly affected by human activities. Sigma PFCs residue levels in surface seawater from Shenzhen west coast, which locates below the estuary of Pearl River and Donghao River, are much higher than those from the east coast, which has low development and sparse population (P<0.05). Under natural conditions, sigma PFCs residue levels in coastal surface seawater samples from Shenzhen Bays are higher than those out of bays. The major residue species in surface seawater samples along Shenzhen coast were medium- and short-chain PFCs, including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanoic acid and perfluoropentanoic acid. Their similar environmental behavior (P<0.05, P<0.01) is likely associated with the production process of PFCs-related products. Furthermore, cluster analysis results show that PFOS (R2 = 0.4092) level can be used as a representative parameter for evaluating PFCs contamination status in surface seawater along Shenzhen coast.

  9. Dropwise Evaporative Cooling of Heated Surfaces with Various Wettability Characteristics Obtained by Nanostructure Modifications.

    Science.gov (United States)

    Chen, Jian-Nan; Zhang, Zhen; Ouyang, Xiao-Long; Jiang, Pei-Xue

    2016-12-01

    A numerical and experimental investigation was conducted to analyze dropwise evaporative cooling of heated surfaces with various wettability characteristics. The surface wettability was tuned by nanostructure modifications. Spray-cooling experiments on these surfaces show that surfaces with better wettability have better heat transfer rate and higher critical heat flux (CHF). Single droplet impingement evaporative cooling of a heated surface was then investigated numerically with various wettability conditions to characterize the effect of contact angle on spray-cooling heat transfer. The volume of fluid (VOF) model with variable-time stepping was used to capture the time-dependent liquid-gas interface motion throughout the computational domain with the kinetic theory model used to predict the evaporation rate at the liquid-gas interface. The numerical results agree with the spray-cooling experiments that dropwise evaporative cooling is much better on surfaces with better wettability because of the better liquid spreading and convection, better liquid-solid contact, and stronger liquid evaporation.

  10. Do leaf surface characteristics affect Agrobacterium infection in tea [Camellia sinensis (L.) O Kuntze]?

    Indian Academy of Sciences (India)

    Nitish Kumar; Subedar Pandey; Amita Bhattacharya; Paramvir Singh Ahuja

    2004-09-01

    The host range specificity of Agrobacterium with five tea cultivars and an unrelated species (Artemisia parviflora) having extreme surface characteristics was evaluated in the present study. The degree of Agrobacterium infection in the five cultivars of tea was affected by leaf wetness, micro-morphology and surface chemistry. Wettable leaf surfaces of TV1, Upasi-9 and Kangra jat showed higher rate (75%) of Agrobacterium infection compared to Upasi-10 and ST-449, whereas non-wettable leaves of A. parviflora showed minimum (25%) infection. This indicated that the leaves with glabrous surface having lower (larger surface area covered by water droplet), higher phenol and wax content were more suitable for Agrobacterium infection. Caffeine fraction of tea promoted Agrobacterium infection even in leaves poor in wax (Upasi-10), whereas caffeine-free wax inhibited both Agrobacterium growth and infection. Thus, study suggests the importance of leaf surface features in influencing the Agrobacterium infection in tea leaf explants. Our study also provides a basis for the screening of a clone/cultivar of a particular species most suitable for Agrobacterium infection the first step in Agrobacterium-mediated genetic transformation.

  11. Characteristics of free-surface wave on high-speed liquid lithium jet for IFMIF

    Energy Technology Data Exchange (ETDEWEB)

    Kanemura, Takuji, E-mail: kanemura@stu.nucl.eng.osaka-u.ac.jp [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Yoshihashi-Suzuki, Sachiko [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Kondo, Hiroo [Japan Atomic Energy Agency, 2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Sugiura, Hirokazu; Yamaoka, Nobuo [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Ida, Mizuho; Nakamura, Hiroo [Japan Atomic Energy Agency, 2-4 Shirane Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Matsushita, Izuru [Mitsubishi Heavy Industries Mechatronics Systems, Ltd., 1-16 5-chome, Komatsu-dori, Hyogo-ku, Kobe, Hyogo 652-0865 (Japan); Muroga, Takeo [National Institute for Fusion Science, 322-6 Oroshicho, Toki, Gifu 509-5292 (Japan); Horiike, Hiroshi [Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

    2011-10-01

    The characteristics of the surface waves on a high-speed liquid lithium wall jet were examined in a Li circulation loop at Osaka University for the International Fusion Materials Irradiation Facility (IFMIF). Surface fluctuations were measured by a contact-type liquid level sensor at 175 mm downstream from the nozzle exit, which corresponds to the deuteron beam's axis in the IFMIF, and observed with a high-speed video (HSV) camera. Both the observation and measurement results indicated that the surface fluctuations were composed of various scale turbulent fluctuations. The measurement results especially showed good agreement with the log-normal distribution which is one of the turbulent intermittency theories. The dominant wavelength was found to be shorter with increase in the flow velocity, and reached approximately 4 mm at the velocity of 15 m/s, which gave close agreement with the visually observed wavelength.

  12. Thermal Characteristics of a Primary Surface Heat Exchanger with Corrugated Channels

    Directory of Open Access Journals (Sweden)

    Jang-Won Seo

    2015-12-01

    Full Text Available This paper presents the heat transfer and pressure drop characteristics of a primary surface heat exchanger (PSHE with corrugated surfaces. The PSHE was experimentally investigated for a Reynolds number range of 156–921 under various flow conditions on the hot and cold sides. The inlet temperature of the hot side was maintained at 40 °C, while that of the cold side was maintained at 20 °C. A counterflow was used as it has a higher temperature proximity in comparison with a parallel flow. The heat transfer rate and pressure drop were measured for various Reynolds numbers on both the hot and cold sides of the PSHE, with the heat transfer coefficients for both sides computed using a modified Wilson plot method. Based on the results of the experiment, both Nusselt number and friction factor correlations were suggested for a PSHE with corrugated surfaces.

  13. Distribution and Pollution Characteristics Analysis of Heavy Metals in Surface Sediment in Bi River

    Science.gov (United States)

    Huang, Qianrui; Danek, Tomas; Cheng, Xianfeng; Dong, Tao; Qi, Wufu; Zou, Liling; Zhao, Xueqiong; Zhao, Xinliang; Xiang, Yungang

    2016-10-01

    The author analyzes distribution characteristics of heavy metals’ content in surface sediments of Bi River (Cu, Zn, As and Cd) and evaluates the potential ecological harm of heavy metal pollution in surface sediment by index method of potential ecological harm. Results show that heavy metals, such as Cu, Zn, As, Pb and Cd in surface sediments of Bi River are badly out of limitation. Especially, the heavy metals’ content in Jinding mining area is far higher than the national first class standard. The content of heavy metal is still high in the intersection of Bi River and Lancang River, which have certain influence on the Lancang River sediment and its water system. And, Pb and Cd, as the main pollutants, should be regarded as a key research subject.

  14. Study on Propagation Characteristics of Plasma Surface Wave in Medium Tube

    Institute of Scientific and Technical Information of China (English)

    WANG Shiqing; YAN Zelin; LI Wenzhong; LIU Jian; LI Jian; XU Lingfei

    2008-01-01

    Axial propagation characteristics of the axisymmetric surface wave along the plasma in the medium tube were studied. The expressions of electromagnetic field inside and outside the medium tube were deduced. Also, the impacts of several factors, such as plasma density, signal frequency, inner radius of medium tube, collision frequency, etc., on plasma surface wave propa-gation were numerically simulated. The results show that, the properties of plasma with higher density and .lower gas pressure are closer to those of metal conductor. Furthermore, larger radius of medium tube and lower signal frequency are better for surface wave propagation. However, the effect of collision frequency is not obvious. The optimized experimental parameters can be chosen as the plasma density of about 1017 m-3 and the medium radius between 11 mm and 19 mm.

  15. Euler characteristics of Hilbert schemes of points on surfaces with simple singularities

    CERN Document Server

    Gyenge, Ádám; Szendrői, Balázs

    2015-01-01

    This is an announcement of conjectures and results concerning the generating series of Euler characteristics of Hilbert schemes of points on surfaces with simple (Kleinian) singularities. For a quotient surface C^2/G with G a finite subgroup of SL(2, C), we conjecture a formula for this generating series in terms of Lie-theoretic data, which is compatible with existing results for type A singularities. We announce a proof of our conjecture for singularities of type D. The generating series in our conjecture can be seen as a specialized character of the basic representation of the corresponding (extended) affine Lie algebra; we discuss possible representation-theoretic consequences of this fact. Our results, respectively conjectures, imply the modularity of the generating function for surfaces with type A and type D, respectively arbitrary, simple singularities, confirming predictions of S-duality.

  16. Seasonal transition of precipitation characteristics associated with land surface conditions in and around Bangladesh

    Science.gov (United States)

    Ono, M.; Takahashi, H. G.

    2016-10-01

    This study examined the seasonal transition of precipitation characteristics and its association with land surface conditions in and around Bangladesh, where land surface conditions are predominantly wet. Hourly rain rate data from the Global Satellite Mapping of Precipitation Microwave-Infrared Combined Product and 10 day soil moisture data from the Advanced Microwave Scanning Radiometer Earth Observing System were used over the 7 years from 2003 to 2009. Area mean values of soil moisture, and precipitation amount, frequency, and intensity were calculated for each 10 day period. Results showed that higher precipitation amount and frequency were observed over the wet soil conditions, which indicates that soil moisture was influenced by previous precipitation events. However, the soil moisture could also control the precipitation characteristics. The seasonal and interannual variations in all regions suggested that precipitation amount and frequency increased in moist soil conditions, which is associated with an increase of water vapor supplied from the moist land surface. Over a flat plain (87°E-91°E, 23°N-25°N), a higher afternoon precipitation intensity was observed over drier land surfaces. This relationship was observed on seasonal and interannual variations. This suggests that the land surface conditions in this region can affect the afternoon precipitation intensity to some extent, although changes of atmospheric conditions can be a major factor particularly for the seasonal changes. However, this relationship was not observed in mountainous regions. This can be explained by other factors, such as thermally induced local circulations by the surrounding topography, being stronger than the impact of land surface conditions.

  17. Formation and properties of surface-anchored polymer assemblies with tunable physico-chemical characteristics

    Science.gov (United States)

    Wu, Tao

    We describe two new methodologies leading to the formation of novel surface-anchored polymer assemblies on solid substrates. While the main goal is to understand the fundamentals pertaining to the preparation and properties of the surface-bound polymer assemblies (including neutral and chargeable polymers), several examples also are mentioned throughout the Thesis that point out to practical applications of such structures. The first method is based on generating assemblies comprising anchored polymers with a gradual variation of grafting densities on solid substrates. These structures are prepared by first covering the substrate with a molecular gradient of the polymerization initiator, followed by polymerization from these substrate-bound initiator centers ("grafting from"). We apply this technique to prepare grafting density gradients of poly(acryl amide) (PAAm) and poly(acrylic acid) (PAA) on silica-covered substrates. We show that using the grafting density gradient geometry, the characteristics of surface-anchored polymers in both the low grafting density ("mushroom") regime as well as the high grafting density ("brush") regime can be accessed conveniently on a single sample. We use a battery of experimental methods, including Fourier transform infrared spectroscopy (FTIR), Near-edge absorption fine structure spectroscopy (NEXAFS), contact angle, ellipsometry, to study the characteristics of the surface-bound polymer layers. We also probe the scaling laws of neutral polymer as a function of grafting density, and for weak polyelectrolyte, in addition to the grafting density, we study the affect of solution ionic strength and pH values. In the second novel method, which we coined as "mechanically assisted polymer assembly" (MAPA), we form surface anchored polymers by "grafting from" polymerization initiators deposited on elastic surfaces that have been previously extended uniaxially by a certain length increment, Deltax. Upon releasing the strain in the

  18. Mode interactions of a high-subsonic deep cavity

    Science.gov (United States)

    Chen, Zhenli; Adams, Nikolaus A.

    2017-05-01

    To understand the interactions of the acoustic modes associated with the tunnel walls and the cavity oscillations in the experiment, flows over a deep cavity having a length-to-depth ratio L/D = 0.42 at high subsonic speeds with and without an upper tunnel wall were investigated by using an implicit large-eddy simulation with an adaptive local deconvolution method. The results of the simulations with the upper tunnel wall converge well to the experimental results as the resolution increases. However, in the simulations without the upper tunnel wall the flow converges to a different mean state. The mode interactions were analyzed by using a Dynamic Mode Decomposition (DMD) method based on a memory-efficient snapshot algorithm. It was found that nearly trapped global modes, which have almost zero upstream and downstream radiation, can occur. The interactions of the trapped modes, the acoustic resonant modes in the cavity, and the shear-layer modes can be observed in the DMD modes of the flow with the upper tunnel wall, which results in the enhancement of harmonic modes and the existence of higher-order modes. In the flow without the upper tunnel wall, the pressure waves can transmit freely away from the cavity, but the interactions of the acoustic resonant modes and the shear-layer modes can also be observed when the frequencies of both kinds of modes coincide. The effects of the ratio of the cavity depth to the tunnel height (D/H) on the formation of trapped modes were also investigated. As the ratio D/H decreases, the frequency window of the trapped modes shrinks and finally closes, which is consistent with a theoretical model. It can be concluded that the effects of the upper tunnel wall on the dynamics of the cavity flow are strong and are promoted by the interactions of different kinds of modes. The appearance and enhancement of high order harmonic modes in the high-subsonic deep cavity are due to the effects of the trapped modes, but are not due to the directly

  19. Surface characteristics of a self-polymerized dopamine coating deposited on hydrophobic polymer films.

    Science.gov (United States)

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhu, Baoku; Xu, Youyi

    2011-12-06

    This study aims to explore the fundamental surface characteristics of polydopamine (pDA)-coated hydrophobic polymer films. A poly(vinylidene fluoride) (PVDF) film was surface modified by dip coating in an aqueous solution of dopamine on the basis of its self-polymerization and strong adhesion feature. The self-polymerization and deposition rates of dopamine on film surfaces increased with increasing temperature as evaluated by both spectroscopic ellipsometry and scanning electronic microscopy (SEM). Changes in the surface morphologies of pDA-coated films as well as the size and shape of pDA particles in the solution were also investigated by SEM, atomic force microscopy (AFM), and transmission electron microscopy (TEM). The surface roughness and surface free energy of pDA-modified films were mainly affected by the reaction temperature and showed only a slight dependence on the reaction time and concentration of the dopamine solution. Additionally, three other typical hydrophobic polymer films of polytetrafluoroethylene (PTFE), poly(ethylene terephthalate) (PET), and polyimide (PI) were also modified by the same procedure. The lyophilicity (liquid affinity) and surface free energy of these polymer films were enhanced significantly after being coated with pDA, as were those of PVDF films. It is indicated that the deposition behavior of pDA is not strongly dependent on the nature of the substrates. This information provides us with not only a better understanding of biologically inspired surface chemistry for pDA coatings but also effective strategies for exploiting the properties of dopamine to create novel functional polymer materials.

  20. Designing and preparation of cytisine alkaloid surface-imprinted material and its molecular recognition characteristics

    Science.gov (United States)

    Gao, Baojiao; Bi, Concon; Fan, Li

    2015-03-01

    Based on molecular design, a cytisine surface-imprinted material was prepared using the new surface-imprinting technique of "pre-graft polymerizing and post-imprinting". The graft-polymerization of glycidyl methacrylate (GMA) on the surfaces of micron-sized silica gel particles was first performed with a surface-initiating system, preparing the grafted particles PGMA/SiO2. Subsequently, a polymer reaction, the ring-opening reaction of the epoxy groups of the grafted PGMA, was conducted with sodium 2,4-diaminobenzene sulfonate (SAS) as reagent, resulting in the functional grafted particles SAS-PGMA/SiO2. The adsorption of cytisine on SAS-PGMA/SiO2 particles reached saturation via strong electrostatic interaction between the sulfonate groups of SAS-PGMA/SiO2 particles and the protonated N atoms in cytisine molecule. Finally, cytisine surface-imprinting was successfully carried out with glutaraldehyde as crosslinker, obtaining cytisine surface-imprinted material MIP-SASP/SiO2. The binding and recognition characteristics of MIP-SASP/SiO2 towards cytisine were investigated in depth. The experimental results show that there is strong electrostatic interaction between particles and cytisine molecules, and on this basis, cytisine surface-imprinting can be smoothly performed. The surface-imprinted MIP-SASP/SiO2 has special recognition selectivity and excellent binding affinity for cytisine, and the selectivity coefficients of MIP-SASP/SiO2 particles for cytisine relative to matrine and oxymatrine, which were used as two contrast alkaloids, are 9.5 and 6.5, respectively.

  1. Surface characteristics and cell adhesion: a comparative study of four commercial dental implants.

    Science.gov (United States)

    Liu, Ruohong; Lei, Tianhua; Dusevich, Vladimir; Yao, Xiamei; Liu, Ying; Walker, Mary P; Wang, Yong; Ye, Ling

    2013-12-01

    the surface characteristics and different cell adhesion on the osseointegration between implant and bone. © 2013 by the American College of Prosthodontists.

  2. Physicochemical characteristics of ambient particles settling upon leaf surfaces of urban plants in Beijing

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; LIU Lian-you; GAO Shang-yu; HASI Eer-dun; WANG Zhi

    2006-01-01

    Particulate pollution is a serious health problem throughout the world, exacerbating a wide range of respiratory and vascular illnesses in urban areas. Urban plants play an important role in reducing particulate pollution. Physicochemical characteristics of ambient particles settling upon leaf surfaces of eleven roadside plants at four sites of Beijing were studies. Results showed that density of particles on the leaf surfaces greatly varied with plant species and traffic condition. Fraxinus chinensis, Sophora japonica, Ailanthus altissima, Syringa oblata and Prunus persica had larger densities of particles among the tall species. Due to resuspension of road dust,the densities of particles ofEuonymus japonicus and Parthenocissus quinquefolia with low sampling height were 2-35 times to other taller tree species. For test plant species, micro-roughness of leaf surfaces and density of particles showed a close correlation. In general, the larger micro-roughness of leaf surfaces is, the larger density of particles is. Particles settling upon leaf surfaces were dominantly PM10 (particulate matter less than 10 μm in aerodynamic diameter; 98.4%) and PM2.5 (particulate matter less than 2.5 μm in aerodynamic diameter; 64.2%) which were closely relative to human health. Constant elements of particles were C, O, K, Ca, Si,earth dust or industrial emission and SO2, H2SO4 or sulfate. NaCl was derived from sea salt.

  3. Age-related leaf characteristics of surface features and ultrastructure of Dendropanax morbifera.

    Science.gov (United States)

    Kim, Ki Woo; Koo, Young Kuk; Yoon, Chul Jong

    2012-02-01

    Age-related morphological and anatomical changes were investigated by light and electron microscopy with juvenile and adult leaves of Dendropanax morbifera. Most juvenile leaves were glossy and palmate with five deep and narrow lobes divided nearly to two-thirds of the leaf base. Adult leaves were thick and possessed three lobes divided nearly to half of the leaf base. Stomata were ovoid and found on the abaxial surface. The epicuticular waxes of the plant included platelets, angular rodlets and threads. Platelets were attached to the surface at various angles. Distinct angular rodlets could be found on either the adaxial or the abaxial surface. Platelets on surface undulations occurred exclusively on the abaxial surface of adult leaves. Juvenile leaves were ca. 150 μm thick and had few intercellular spaces. Adult leaves were nearly two times thicker than juvenile leaves, and showed highly vacuolated cells and large intercellular spaces. The cuticle proper was apparent on the epidermis and showed distinctly alternating lamellate structures in juvenile leaves. The epidermal cell wall of adult leaves was covered with a cuticle layer for which a lamellate structure was not found. These results suggest that the species is heteroblastic in leaf characteristics with increasing leaf age.

  4. INFLUENCE OF MIXING PARAMETERS ON THE RHEOLOGICAL AND SURFACE APPEARANCE CHARACTERISTICS OF RUBBER COMPOUNDS UNSHAPED PROFILES

    Directory of Open Access Journals (Sweden)

    O. V. Karmanova

    2014-01-01

    Full Text Available Influence the degree of dispersion of the carbon black on the rheological characteristics of the surface appearance and rubber mixtures based on ethylene-propylene rubber EPDM-50 was investigated. Effect of mixing time on the degree of dispersion of the carbon black elastic-viscous and extrusion characteristics of rubber compounds were found. Component tangent of the angle of mechanical losses tgδ to evaluate the rheological and technological properties of the rubber compounds used. Relationship changes tgδ valuesand properties of rubber compounds in the preparation of the compositions of rubber with carbon black was shown. On the curves of the length of the mixing tgδ rubber filler identified three main areas of change in the rheological and techno-logical properties of rubber compounds. This allows you to monitor and make adjustments to the mode of preparation of the compositions in the real world of production. evaluation of the quality of mixing in surface appearance characteristics unshaped profiles was conducted. The resulting patterns formed the basis for the development of recommendations for the selection of optimal blending modes in the production and quality control of production of rubber compounds.

  5. Surface energy characteristics of zeolite embedded PVDF nanofiber films with electrospinning process

    Science.gov (United States)

    Kang, Dong Hee; Kang, Hyun Wook

    2016-11-01

    Electrospinning is a nano-scale fiber production method with various polymer materials. This technique allows simple fiber diameters control by changing the physical conditions such as applied voltage and polymer solution viscosity during the fabrication process. The electrospun polymer fibers form a thin porous film with high surface area to volume ratio. Due to these unique characteristics, it is widely used for many application fields such as photocatalyst, electric sensor, and antibacterial scaffold for tissue engineering. Filtration is one of the main applications of electrospun polymer fibers for specific application of filtering out dust particles and dehumidification. Most polymers which are commonly used in electrospinning are hard to perform the filtering and dehumidification simultaneously because of their low hygroscopic property. To overcome this obstacle, the desiccant polymers are developed such as polyacrylic acid and polysulfobetaine methacrylate. However, the desiccant polymers are generally expensive and need special solvent for electrospinning. An alternating way to solve these problems is mixing desiccant material like zeolite in polymer solution during an electrospinning process. In this study, the free surface energy characteristics of electrospun polyvinylidene fluoride (PVDF) film with various zeolite concentrations are investigated to control the hygroscopic property of general polymers. Fundamental physical property of wettability with PVDF shows hydrophobicity. The electrospun PVDF film with small weight ratio with higher than 0.1% of zeolite powder shows diminished contact angles that certifying the wettability of PVDF can be controlled using desiccant material in electrospinning process. To quantify the surface energy of electrospun PVDF films, sessile water droplets are introduced on the electrospun PVDF film surface and the contact angles are measured. The contact angles of PVDF film are 140° for without zeolite and 80° for with 5

  6. Designing and preparation of cytisine alkaloid surface-imprinted material and its molecular recognition characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Baojiao, E-mail: gaobaojiao@126.com [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Bi, Concon [Department of Chemical Engineering, North University of China, Taiyuan 030051 (China); Fan, Li [School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China)

    2015-03-30

    Highlights: • An elaborate molecular design was well done for molecule surface-imprinting. • The new method of “pre-graft polymerizing and post-imprinting” was used. • Cytisine molecule surface-imprinted material was prepared. • Cytisine surface-imprinting depends on electrostatic interaction between host–guest. • The imprinted material has special recognition selectivity for template cytisine. - Abstract: Based on molecular design, a cytisine surface-imprinted material was prepared using the new surface-imprinting technique of “pre-graft polymerizing and post-imprinting”. The graft-polymerization of glycidyl methacrylate (GMA) on the surfaces of micron-sized silica gel particles was first performed with a surface-initiating system, preparing the grafted particles PGMA/SiO{sub 2}. Subsequently, a polymer reaction, the ring-opening reaction of the epoxy groups of the grafted PGMA, was conducted with sodium 2,4-diaminobenzene sulfonate (SAS) as reagent, resulting in the functional grafted particles SAS-PGMA/SiO{sub 2}. The adsorption of cytisine on SAS-PGMA/SiO{sub 2} particles reached saturation via strong electrostatic interaction between the sulfonate groups of SAS-PGMA/SiO{sub 2} particles and the protonated N atoms in cytisine molecule. Finally, cytisine surface-imprinting was successfully carried out with glutaraldehyde as crosslinker, obtaining cytisine surface-imprinted material MIP-SASP/SiO{sub 2}. The binding and recognition characteristics of MIP-SASP/SiO{sub 2} towards cytisine were investigated in depth. The experimental results show that there is strong electrostatic interaction between particles and cytisine molecules, and on this basis, cytisine surface-imprinting can be smoothly performed. The surface-imprinted MIP-SASP/SiO{sub 2} has special recognition selectivity and excellent binding affinity for cytisine, and the selectivity coefficients of MIP-SASP/SiO{sub 2} particles for cytisine relative to matrine and oxymatrine, which

  7. Responses of herbaceous plants to urban air pollution: effects on growth, phenology and leaf surface characteristics.

    Science.gov (United States)

    Honour, Sarah L; Bell, J Nigel B; Ashenden, Trevor W; Cape, J Neil; Power, Sally A

    2009-04-01

    Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO(x)) representative of urban conditions, in solardome chambers. Annual mean NO(x) concentrations ranged from 77 nl l(-l) to 98 nl l(-1), with NO:NO(2) ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation.

  8. Effects of surface dielectric barrier discharge on aerodynamic characteristic of train

    Science.gov (United States)

    Dong, Lei; Gao, Guoqiang; Peng, Kaisheng; Wei, Wenfu; Li, Chunmao; Wu, Guangning

    2017-07-01

    High-speed railway today has become an indispensable means of transportation due to its remarkable advantages, including comfortability, convenience and less pollution. The increase in velocity makes the air drag become the main source of energy consumption, leading to receiving more and more concerns. The surface dielectric barrier discharge has shown some unique characteristics in terms of active airflow control. In this paper, the influences of surface dielectric barrier discharge on the aerodynamic characteristics of a scaled train model have been studied. Aspects of the discharge power consumption, the temperature distribution, the velocity of induced flow and the airflow field around the train model were considered. The applied AC voltage was set in the range of 20 kV to 28 kV, with a fixed frequency of 9 kHz. Results indicated that the discharge power consumption, the maximum temperature and the induced flow velocity increased with increasing applied voltage. Mechanisms of applied voltage influencing these key parameters were discussed from the point of the equivalent circuit. The airflow field around the train model with different applied voltages was observed by the smoke visualization experiment. Finally, the effects of surface dielectric barrier discharge on the train drag reduction with different applied voltages were analyzed.

  9. Surface chemical structure and doping characteristics of boron-doped Si nanowires fabricated by plasma doping

    Science.gov (United States)

    Oh, Seung-Hoon; Ma, Jin-Won; Bae, Jung Min; Kang, Yu-seon; Ahn, Jae-Pyung; Kang, Hang-Kyu; Chae, Jimin; Suh, Dongchan; Song, Woobin; Kim, Sunjung; Cho, Mann-Ho

    2017-10-01

    We investigated the conduction characteristics of plasma-doped Si nanowires (NWs) after various rapid thermal annealing (RTA) times. The plasma doping (PD) process developed a highly-deposited B layer at the NW surface. RTA process controls electrical conductivity by mediating the dopant diffusion from the surface layer. The surface chemical and substitutional states of the B plasma-doped Si NWs were analyzed by x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. To elucidate the detailed structure of the NWs, we analyzed the change in the optical phonon mode caused by the incorporated B atoms. For this purpose, we examined Fano resonance by the investigation of the asymmetry, line-width, and phonon wavenumber in Raman spectra. The changes in symmetry level of the Raman peak, phonon lifetime, and internal strain were closely related to the number of electrically activated borons, which was drastically increased with RTA time. The change in electrical and optical characterizations related to the doping characteristics of the NWs was investigated using a 4-point probe and terahertz time-domain spectroscopy (THz-TDS). The resistivity of the NWs was 3000 times lower after the annealing process compared to that before the annealing process, which is well consistent with the optical conductivity data. The data provide the potential utility of PD in conformal doping for three-dimensional nanodevices.

  10. Surface Properties and Characteristics of Mars Landing Sites from Remote Sensing Data and Ground Truth

    Science.gov (United States)

    Golombek, M. P.; Haldemann, A. F.; Simpson, R. A.; Furgason, R. L.; Putzig, N. E.; Huertas, A.; Arvidson, R. E.; Heet, T.; Bell, J. F.; Mellon, M. T.; McEwen, A. S.

    2008-12-01

    Surface characteristics at the six sites where spacecraft have successfully landed on Mars can be related favorably to their signatures in remotely sensed data from orbit and from the Earth. Comparisons of the rock abundance, types and coverage of soils (and their physical properties), thermal inertia, albedo, and topographic slope all agree with orbital remote sensing estimates and show that the materials at the landing sites can be used as ground truth for the materials that make up most of the equatorial and mid- to moderately high-latitude regions of Mars. The six landing sites sample two of the three dominant global thermal inertia and albedo units that cover ~80% of the surface of Mars. The Viking, Spirit, Mars Pathfinder, and Phoenix landing sites are representative of the moderate to high thermal inertia and intermediate to high albedo unit that is dominated by crusty, cloddy, blocky or frozen soils (duricrust that may be layered) with various abundances of rocks and bright dust. The Opportunity landing site is representative of the moderate to high thermal inertia and low albedo surface unit that is relatively dust free and composed of dark eolian sand and/or increased abundance of rocks. Rock abundance derived from orbital thermal differencing techniques in the equatorial regions agrees with that determined from rock counts at the surface and varies from ~3-20% at the landing sites. The size-frequency distributions of rocks >1.5 m diameter fully resolvable in HiRISE images of the landing sites follow exponential models developed from lander measurements of smaller rocks and are continuous with these rock distributions indicating both are part of the same population. Interpretation of radar data confirms the presence of load bearing, relatively dense surfaces controlled by the soil type at the landing sites, regional rock populations from diffuse scattering similar to those observed directly at the sites, and root-mean-squared slopes that compare favorably

  11. Dynamical Friction in a Gas: The Subsonic Case

    CERN Document Server

    Lee, Aaron T

    2011-01-01

    We study the force of dynamical friction acting on a gravitating point mass that travels through an extended, isothermal gas. This force is well established in the hypersonic limit, but remains less understood in the subsonic regime. Using perturbation theory, we analyze the changes in gas velocity and density far from the mass. We show analytically that the steady-state friction force is Mdot*V, where Mdot is the mass accretion rate onto an object moving at speed V. It follows that the speed of an object experiencing no other forces declines as the inverse square of its mass. Using a modified version of the classic Bondi-Hoyle interpolation formula for Mdot as a function of V, we derive an analytic expression for the friction force. This expression also holds when mass accretion is thwarted, e.g. by a wind, as long as the wind-cloud interaction is sufficiently confined spatially. Our result should find application in a number of astrophysical settings, such as the motion of galaxies through intracluster gas.

  12. Chaos control for the plates subjected to subsonic flow

    Science.gov (United States)

    Norouzi, Hamed; Younesian, Davood

    2016-07-01

    The suppression of chaotic motion in viscoelastic plates driven by external subsonic air flow is studied. Nonlinear oscillation of the plate is modeled by the von-Kármán plate theory. The fluid-solid interaction is taken into account. Galerkin's approach is employed to transform the partial differential equations of the system into the time domain. The corresponding homoclinic orbits of the unperturbed Hamiltonian system are obtained. In order to study the chaotic behavior of the plate, Melnikov's integral is analytically applied and the threshold of the excitation amplitude and frequency for the occurrence of chaos is presented. It is found that adding a parametric perturbation to the system in terms of an excitation with the same frequency of the external force can lead to eliminate chaos. Variations of the Lyapunov exponent and bifurcation diagrams are provided to analyze the chaotic and periodic responses. Two perturbation-based control strategies are proposed. In the first scenario, the amplitude of control forces reads a constant value that should be precisely determined. In the second strategy, this amplitude can be proportional to the deflection of the plate. The performance of each controller is investigated and it is found that the second scenario would be more efficient.

  13. In-vitro characteristics of cemented titanium femoral stems with a smooth surface finish.

    Science.gov (United States)

    Akiyama, Haruhiko; Yamamoto, Koji; Kaneuji, Ayumi; Matsumoto, Tadami; Nakamura, Takashi

    2013-01-01

    In cemented total hip arthroplasty (THA), a polished tapered femoral stem with a design based on the taper-slip concept enables extremely reliable and durable fixation. In contrast, cemented femoral stems made from titanium alloys are not favored because of reports describing insufficient clinical outcomes. However, we have reported excellent clinical and radiological outcomes for cemented titanium stems made using the composite-beam concept. This study examines the characteristics of cemented titanium femoral stems with a smooth surface. The bonding strength between titanium alloys with different surface finishes and bone cement was evaluated by use of push-out and detachment tests. Torsional stability tests were performed to evaluate the initiation and propagation of disruption of the fixation of cemented stems at the cement-implant interface. The wear resistance was investigated by use of wear-friction tests performed using a multidirectional pin-on-disc machine. The bone strain loaded on to the femoral cortex was measured by use of an implanted Sawbone and analyzed by use of the finite element method. The push-out and detachment tests revealed increasing cement adhesion strength with increasing degree of roughness of the metal surface. The torsional stability tests indicated that a load >1,000 N led to progressive debonding between the cement and the implant with a smooth surface finish. Interestingly, wear-friction tests revealed the wear rate for polished titanium surfaces was clearly higher than for smooth surfaces. In addition, the greater elasticity of titanium stems compared with cobalt-chromium stems transmitted the external load to the proximal side of the femur more effectively. The smooth surface finish of the stems is an important factor for the satisfactory clinical and radiological outcomes of cemented titanium femoral stems. The greater elasticity of a titanium stem effectively transmits the external load to the medial side of the femur.

  14. Surface characteristics of ruthenium in periodate-based slurry during chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jie; Wang, Tongqing; Jiang, Liang; Lu, Xinchun, E-mail: xclu@tsinghua.edu.cn

    2015-10-01

    Highlights: • The Ru surface chemical and mechanical property varies with KIO{sub 4} slurry pH. • In alkaline slurry, the corrosion proceeds uniformly like a direct dissolution. • In neutral and acidic slurries, Ru exhibits passivation behavior. • MRR is highest in neutral slurry due to inhomogeneous RuO{sub 2}·2H{sub 2}O/RuO{sub 3} passivation. • Weak alkaline slurry is preferred to get good MRR and avoid toxic RuO{sub 4} formation. - Abstract: When the feature size of integrated circuit continues to shrink below 14 nm, ruthenium (Ru) has become one of the most promising candidates for the application of novel barrier layer. To reveal the material removal mechanism of Ru during chemical mechanical polishing (CMP), surface characteristics of Ru in KIO{sub 4}-based slurry were investigated. The corrosion behavior of ruthenium was measured by the surface chemistry and morphology analysis. Then the mechanical properties of the passivated/corroded surface were evaluated by AES and tribocorrosion experiments. CMP experiments were carried out to make clear the effects of surface property during polishing. It was found that the Ru surface chemistry and mechanical properties vary obviously as a function of slurry pH. In neutral slurries, the Ru surface is covered with RuO{sub 2}·2H{sub 2}O/RuO{sub 3} inhomogeneous passivation films, with the highest material removal rate obtained during the CMP process. It could be concluded that the material removal mechanism largely depends on the slurry pH values. In near neutral slurries, Ru is passivated with thick and heterogeneous oxides film, which proves the easiest to be mechanically removed during polishing. The weak alkaline slurry is preferred in order to achieve desirable polishing rate as well as avoid the formation of toxic RuO{sub 4}.

  15. Radiation Characteristic Improvement of X-Band Slot Antenna Using New Multiband Frequency-Selective Surface

    Directory of Open Access Journals (Sweden)

    Elham Moharamzadeh

    2014-01-01

    Full Text Available A new configuration of frequency-selective surfaces (FSSs is designed and presented with multiresonance characteristics which covers all of the frequency domain of X-band from 8 to 12 GHz. The proposed FSS comprises three conductor-based split ring resonators, connected together. In this design, two unit cells of the FSS with different lengths are employed side by side to design the FSS. The FSS is used to enhance the gain of the new designed triangle slot antenna at X-band. The proposed FSS is analyzed by using reflected-wave unit-cell box method. The single, double, and array of the FSS cells are studied. Next, the designed FSS along with the antenna is analyzed. The measurement and simulated results of the impedance and radiation characteristics, especially the increment of the gain, are presented.

  16. Chemical characteristics of fulvic acids from Arctic surface waters: Microbial contributions and photochemical transformations

    Science.gov (United States)

    Cory, Rose M.; McKnight, Diane M.; Chin, Yu-Ping; Miller, Penney; Jaros, Chris L.

    2007-12-01

    Dissolved organic matter (DOM) originating from the extensive Arctic tundra is an important source of organic material to the Arctic Ocean. Chemical characteristics of whole water dissolved organic matter (DOM) and the fulvic acid fraction of DOM were studied from nine surface waters in the Arctic region of Alaska to gain insight into the extent of microbial and photochemical transformation of this DOM. All the fulvic acids had a strong terrestrial/higher plant signature, with uniformly depleted δ13C values of -28‰, and low fluorescence indices around 1.3. Several of the measured chemical characteristics of the Arctic fulvic acids were related to water residence time, a measure of environmental exposure to sunlight and microbial activity. For example, fulvic acids from Arctic streams had higher aromatic contents, higher specific absorbance values, lower nitrogen content, lower amino acid-like fluorescence and were more depleted in δ15N relative to fulvic acids isolated from lake and coastal surface waters. The differences in the nitrogen signature between the lake and coastal fulvic acids compared to the stream fulvic acids indicated that microbial contributions to the fulvic acid pool increased with increasing water residence time. The photo-lability of the fulvic acids was positively correlated with water residence time, suggesting that the fulvic acids isolated from source waters with larger water residence times (i.e., lakes and coastal waters) have experienced greater photochemical degradation than the stream fulvic acids. In addition, many of the initial differences in fulvic acid chemical characteristics across the gradient of water residence times were consistent with changes observed in fulvic acid photolysis experiments. Taken together, results from this study suggest that photochemical processes predominantly control the chemical character of fulvic acids in Arctic surface waters. Our findings show that hydrologic transport in addition to

  17. Anisotropy Characteristics of Magnetostatic Surface Wave Propagating in YIG/Dielectric/Metal Layered Structure

    Institute of Scientific and Technical Information of China (English)

    Qing-Hui Yang; Huai-Wu Zhang; Ying-Li Liu

    2007-01-01

    The anisotropy of magnetostatic surface wave (MSSW) propagating in finite width YIG/dielectric/metal layered structure is analyzed. This problem is solved by finding the rigorous solution of each layer from Maxwell equation and the appropriate transmission Green's function matrix (G). From the relationship of Green's function matrixes of dielectric layer and ferrite layer, the dispersion equation is obtained.The MSSW filter is designed to verify the dispersion characteristics. The experiment results are in good agreement with the calculating data from the model.

  18. Determination of the statistical characteristics of the specular points of 3 dimensional Gaussian sea surface

    Science.gov (United States)

    Gardashov, G. R.; Gardashova, T. G.

    2009-10-01

    The inverse problem in the form of Fredholm integral equation of the first kind for determining the distribution density of the number of specular points of 3-D Gaussian sea surface is formulated and solved. The kernel of this equation is determined by the characteristic function of the distribution of radii of curvature at the specular points. On the basis of numerical experiments, and also by using images of the Sun glitters it is shown that on the known distribution density of the intensity of reflected light it is possible to define the distribution densities of both the number of specular points and the radii of curvature at the specular points.

  19. Surface electromyographic characteristics of swallowing in dysphagia secondary to brainstem stroke.

    Science.gov (United States)

    Crary, M A; Baldwin, B O

    1997-01-01

    Surface electromyography (SEMG) provides an noninvasive avenue for evaluating swallowing physiology. This report describes SEMG characteristics associated with swallow attempts in 6 dysphagic patients who had suffered brainstem stroke compared with 6 age and gender-matched controls. Results indicated that patients with dysphagia secondary to brainstem stroke differed in both amplitude and timing aspects of swallowing attempts from asymptomatic controls. Specifically, the results indicated that during swallow attempts, dysphagic patients produced more muscle activity over a shorter duration and with less coordination than controls. Potential physiological mechanisms of these results are discussed.

  20. High-Resolution Radar Scattering Characteristics of a Disturbed Sea Surface and Floating Debris

    Science.gov (United States)

    1977-07-29

    theoretically and experimentally. Oil drums, logs, and aluminum-covered plastic gallon milk bottles were considered and measured. A comparison of the echoing...covered plastic bottle ,38 N R tEPO R1 8 131 0 DBSM L LJ v ’ da) B 6 GH1 0 DSM -- DBSM ib) 9.2 GHz Ils Fig. 29 - Vertically polarized return from wave...j2 ’ NRL Report 8131 (~High-Resolution Radar Scattering Characteristics of a Disturbed Sea Surface and Floating Debris B. L. LEWIS. J. P. HANSEN. 1

  1. Dispersion states and surface characteristics of physically blended polyhedral oligomeric silsesquioxane/polymer hybrid nanocomposites

    Science.gov (United States)

    Misra, Rahul

    nanoscale tribomechanical characteristics in relation to the POSS structures. Chapter 5 probes the molecular miscibility, solution and solid-state chain dynamics in polystyrene solution blended with Oib- and Tsp-POSS based on classical thermodynamic principles. Chapter 6 extends the learnings from chapter 5 to utilize POSS as a dispersion aid to disperse TiO2 nanoparticles in polypropylene. Chapter 7 explores the surface properties of fluorinated and non-fluorinated POSS coated fabrics. Finally, chapter 8 explores a nature-inspired route to modify polymer surfaces utilizing hydrophobin proteins and their impact on surface morphology and nanotribological characteristics.

  2. CHARACTERISTICS OF FATIGUE SURFACE MICROCRACK GROWTH IN VICINAL INCLUSION FOR POWDER METALLURGY ALLOYS

    Institute of Scientific and Technical Information of China (English)

    WangXishu; LiYongqiang

    2003-01-01

    Inclusion flaw is one of the worst flaws of powder metallurgy. The inclusion flaw plays an important role in the failure of high temperature turbine materials in aircraft components and automotive parts, especially fatigue failure. In this paper, an experimental investigation of fatigue microcrack propagation in the vicinal inclusion were carried out by the servo-hydraulic fatigue test system with scanning electron microscope (SEM). It has been found from the SEM images that the fatigue surface microcrack occurs in the matrix and inclusion. According to the SEM images, the characteristics of fatigue crack initiation and growth in vicinal inclusion for powder metallurgy alloys are analyzed in detail. The effect of the geometrical shape and material type of surface inclusions on the cracking is also discussed with the finite element method (FEM).

  3. Doppler lidar investigation of wind turbine wake characteristics and atmospheric turbulence under different surface roughness.

    Science.gov (United States)

    Zhai, Xiaochun; Wu, Songhua; Liu, Bingyi

    2017-06-12

    Four field experiments based on Pulsed Coherent Doppler Lidar with different surface roughness have been carried out in 2013-2015 to study the turbulent wind field in the vicinity of operating wind turbine in the onshore and offshore wind parks. The turbulence characteristics in ambient atmosphere and wake area was analyzed using transverse structure function based on Plane Position Indicator scanning mode. An automatic wake processing procedure was developed to determine the wake velocity deficit by considering the effect of ambient velocity disturbance and wake meandering with the mean wind direction. It is found that the turbine wake obviously enhances the atmospheric turbulence mixing, and the difference in the correlation of turbulence parameters under different surface roughness is significant. The dependence of wake parameters including the wake velocity deficit and wake length on wind velocity and turbulence intensity are analyzed and compared with other studies, which validates the empirical model and simulation of a turbine wake for various atmosphere conditions.

  4. Surface characteristics and mechanical properties of high-strength steel wires in corrosive conditions

    Science.gov (United States)

    Xu, Yang; Li, Shunlong; Li, Hui; Yan, Weiming

    2013-04-01

    Cables are always a critical and vulnerable type of structural components in a long-span cable-stayed bridge in normal operation conditions. This paper presents the surface characteristics and mechanical performance of high-strength steel wires in simulated corrosive conditions. Four stress level (0MPa, 300MPa, 400MPa and 500MPa) steel wires were placed under nine different corrosive exposure periods based on the Salt Spray Test Standards ISO 9227:1990. The geometric feathers of the corroded steel wire surface were illustrated by using fractal dimension analysis. The mechanical performance index including yielding strength, ultimate strength and elastic modulus at different periods and stress levels were tested. The uniform and pitting corrosion depth prediction model, strength degradation prediction model as well as the relationship between strength degradation probability distribution and corrosion crack depth would be established in this study.

  5. Endplate effect on aerodynamic characteristics of threedimensional wings in close free surface proximity

    Science.gov (United States)

    Jung, Jae Hwan; Kim, Mi Jeong; Yoon, Hyun Sik; Hung, Pham Anh; Chun, Ho Hwan; Park, Dong Woo

    2012-12-01

    We investigated the aerodynamic characteristics of a three-dimensional (3D) wing with an endplate in the vicinity of the free surface by solving incompressible Navier-Stokes equations with the turbulence closure model. The endplate causes a blockage effect on the flow, and an additional viscous effect especially near the endplate. These combined effects of the endplate significantly reduce the magnitudes of the velocities under the lower surface of the wing, thereby enhancing aerodynamic performance in terms of the force coefficients. The maximum lift-to-drag ratio of a wing with an endplate is increased 46% compared to that of wing without an endplate at the lowest clearance. The tip vortex of a wing-with-endplate (WWE) moved laterally to a greater extent than that of a wing-without-endplate (WOE). This causes a decrease in the induced drag, resulting in a reduction in the total drag.

  6. Discharge Characteristics in Atmospheric Pressure Glow Surface Discharge in Helium Gas

    Institute of Scientific and Technical Information of China (English)

    LI Xue-Chen; WANG Long

    2005-01-01

    @@ Atmospheric pressure glow discharge is observed for the first time in a surface discharge generator in flowing helium. Electrical and optical methods are used to measure the characteristics of atmospheric pressure glow discharge for different voltages. The results show that discharge current waveforms are asymmetric for the different polarities of the applied voltage. A continuous discharge profile with a width of several microseconds appears for per half cycle of the applied voltage when the voltage is increased to a certain value. The short-pulsed discharge and the continuous current would result from the Townsend breakdown and glow discharge mechanisms respectively. The properties of surface discharge in stagnant helium are completely different from that in flowing helium.

  7. Analysis of the Scattering Characteristics of Sea Surface with the Influence from Internal Wave

    Directory of Open Access Journals (Sweden)

    Wei Yi-wen

    2015-06-01

    Full Text Available The internal wave travels beneath the sea surface and modulate the roughness of the sea surface through the wave-current interaction. This makes some dark and bright bands can be observed in the Synthetic Aperture Radar (SAR images. In this paper, we first establish the profile of the internal wave based on the KdV equations; then, the action balance equation and the wave-current interaction source function are used to modify the sea spectrum; finally, the two-scale theory based facet model is combined with the modified sea spectrum to calculate the scattering characteristics of the sea. We have simulated the scattering coefficient distribution of the sea with an internal wave traveling through. The influence on the scattering coefficients and the Doppler spectra under different internal wave parameters and sea state parameters are analyzed.

  8. Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum%Influence of Surface Carburization of Machinable Ceramics on Its Pulsed Flashover Characteristics in Vacuum

    Institute of Scientific and Technical Information of China (English)

    郑楠; 黄学增; 穆海宝; 张冠军

    2011-01-01

    For pulsed power devices, surface flashover phenomena across solid insulators greatly restrict their overall performance. In recent decades, much attention has been paid on enhancing the surface electric withstanding strength of insulators, and it is found that surface treatment of material is useful to improve the surface flashover voltage. The carburization treatment is employed to modify the surface components of newly-developed machinable ceramics (MC) materials. A series of MC samples with different glucose solution concentration (0%, 10%, 20%, 30% and 40%) are prepared by chemical reactions for surface carburization modification, and their surface fiashover characteristics are investigated under pulsed voltage in vacuum. It is found that the surface carburization treatment greatly modifies the surface resistivity of MCs and hence the flashover behaviors. Based on the reduction of surface resistivity and the secondary electron emission avalanche (SEEA) theory, the adjustment of flashover withstanding ability can be reasonably explained.

  9. Ontogenetic variation in chemical and physical characteristics of adaxial apple leaf surfaces.

    Science.gov (United States)

    Bringe, Katja; Schumacher, Christina F A; Schmitz-Eiberger, Michaela; Steiner, Ulrike; Oerke, Erich-Christian

    2006-01-01

    The reaction of plants to environmental factors often varies with developmental stage. It was hypothesized, that also the cuticle, the outer surface layer of plants is modified during ontogenesis. Apple plantlets, cv. Golden Delicious, were grown under controlled conditions avoiding biotic and abiotic stress factors. The cuticular wax surface of adaxial apple leaves was analyzed for its chemical composition as well as for its micromorphology and hydrophobicity just after unfolding of leaves ending in the seventh leaf insertion. The outer surface of apple leaves was formed by a thin amorphous layer of epicuticular waxes. Epidermal cells of young leaves exhibited a distinctive curvature of the periclinal cell walls resulting in an undulated surface of the cuticle including pronounced lamellae, with the highest density at the centre of cells. As epidermal cells expanded during ontogenesis, the upper surface showed only minor surface sculpturing and a decrease in lamellae. With increasing leaf age the hydrophobicity of adaxial leaf side decreased significantly indicated by a decrease in contact angle. Extracted from plants, the amount of apolar cuticular wax per area unit ranged from only 0.9 microgcm(-2) for the oldest studied leaf to 1.5 microgcm(-2) for the youngest studied leaf. Differences in the total amount of cuticular waxes per leaf were not significant for older leaves. For young leaves, triterpenes (ursolic acid and oleanolic acid), esters and alcohols were the main wax components. During ontogenesis, the proportion of triterpenes in total mass of apolar waxes decreased from 32% (leaf 1) to 13% (leaf 7); absolute amounts decreased by more than 50%. The proportion of wax alcohols and esters, and alkanes to a lesser degree, increased with leaf age, whereas the proportion of acids decreased. The epicuticular wax layer also contained alpha-tocopherol described for the first time to be present also in the epicuticular wax. The modifications in the chemical

  10. Optimization of burnishing parameters and determination of select surface characteristics in engineering materials

    Indian Academy of Sciences (India)

    P Ravindra Babu; K Ankamma; T Siva Prasad; A V S Raju; N Eswara Prasad

    2012-08-01

    The present study is aimed at filling the gaps in scientific understanding of the burnishing process, and also to aid and arrive at technological solutions for the surface modifications based on burnishing of some of the commonly employed engineering materials. The effects of various burnishing parameters on the surface characteristics, surface microstructure, micro hardness are evaluated, reported and discussed in the case of EN Series steels (EN 8, EN 24 and EN 31), Aluminum alloy (AA6061) and Alpha-beta brass. The burnishing parameters considered for studies principally are burnishing speed, burnishing force, burnishing feed and number of passes. Taguchi technique is employed in the present investigation to identify the most influencing parameters on surface roughness. Effort is also made to identify the optimal burnishing parameters and the factors for scientific basis of such optimization. Finally, a brief attempt is made to construct the Burnishing maps with respect to strength level (in this case, average micro hardness of unburnished material).

  11. Influence of the surface finishing on electrochemical corrosion characteristics of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Sylvia Dundeková

    2015-05-01

    Full Text Available Stainless steels from 316 group are very often and successfully uses for medical applications where the good mechanical and chemical properties in combination with non-toxicity of the material assure its safe and long term usage. Corrosion properties of AISI 361L stainless steel are strongly influenced by surface roughness and treatment of the engineering parts (specimens and testing temperature. Electrochemical characteristics of ground, mechanically polished and passivated AISI 316L stainless steel specimens were examined with the aim to identify the polarization resistance evolution due to the surface roughness decrease. Results obtained on mechanically prepared specimens where only natural oxide layer created due to the exposure of the material to the corrosion environment was protecting the materials were compared to the passivated specimens with artificial oxide layer. Also the influence of temperature and stabilization time before measurement were taken into account when discussing the obtained results. Positive influence of decreasing surface roughness was obtained as well as increase of polarization resistance due to the chemical passivation of the surface. Increase of the testing temperature and short stabilization time of the specimen in the corrosion environment were observed negatively influencing corrosion resistance of AISI 316L stainless steel.

  12. Surface Modified Characteristics of the Tetracalcium Phosphate as Light-Cured Composite Resin Fillers

    Directory of Open Access Journals (Sweden)

    Wen-Cheng Chen

    2014-01-01

    Full Text Available The objectives of this study are to characterize the properties of light-cured composite resins that are reinforced with whisker surface-modified particles of tetracalcium phosphate (TTCP and to investigate the influence of thermal cycling on the reinforced composites properties. The characteristics of ultimate diametral tensile strength (DTS, moduli, pH values, and fracture surfaces of the samples with different amounts of surface-modified TTCP (30%–60% were determined before and after thermal cycling between 5°C and 55°C in deionized water for 600 cycles. The trends of all groups were ductile prior to thermal cycling and the moduli of all groups increased after thermal cycling. The ductile property of the control group without filler was not significantly affected. Larger amounts of fillers caused the particles to aggregate, subsequently decreasing the resin’s ability to disperse external forces and leading to brittleness after thermal cycling. Therefore, the trend of composite resins with larger amounts of filler would become more brittle and exhibited higher moduli after thermal cycling. This developed composite resin with surface modified-TTCP fillers has the potential to be successful dental restorative materials.

  13. Research requirements for a real-time flight measurements and data analysis system for subsonic transport high-lift research

    Science.gov (United States)

    Whitehead, Julia H.; Harris, Franklin K.; Lytle, Carroll D.

    1993-01-01

    A multiphased research program to obtain detailed flow characteristics on a multielement high-lift flap system is being conducted on the Transport Systems Research Vehicle (B737-100 aircraft) at NASA Langley Research Center. Upcoming flight tests have required the development of a highly capable and flexible flight measurement and data analysis instrumentation system. This instrumentation system will be more comprehensive than any of the systems used on previous high-lift flight experiment at NASA Langley. The system will provide the researcher near-real-time information for decision making needed to modify a flight test in order to further examine unexpected flow conditions. This paper presents the research requirements and instrumentation design concept for an upcoming flight experiment for the subsonic transport high-lift research program. The flight experiment objectives, the measurement requirements, the data acquisition system, and the onboard data analysis and display capabilities are described.

  14. Importance of surface characteristics of QUARTZ DQ 12 for acute inflammation

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, C.; Becher, A.; Scins, R.P.F.; Hoehr, D.; Unfried, K.; Knaapen, A.M.; Borm, P.J.A. [Institut fuer medizinische Forschung (IUF), Duesseldorf (Germany)

    2004-07-01

    Although quartz is known to induce inflammation in rat lungs, mechanisms are not yet fully understood. The importance of particle surface characteristics was investigated in vivo after intratracheal instillation of different preparations of quartz in rat lungs. Three days after instillation of 2 mg DQ12 quartz, or DQ12 coated with polyvinylpyridine-N-oxide (PVNO) or Aluminium lactate (AL), lungs of female Wistar rats were lavaged in situ to determine markers of inflammation. Control rats received saline or the coating substances alone. DQ12 induced a marked inflammatory response, as indicated by a significant increase in the number of neutrophils and macrophages, as well as in the levels of b-glucuronidase and myeloperoxidase. None of these inflammatory markers was increased for both coated quartz preparations, with the exception of neutrophil influx which was also increased after treatment with AL quartz. Our results indicate that surface characteristics are important in the onset of quartz-induced lung inflammation which could imply a different development of persistent inflammation. This will be investigated in later follow-up time points of the same animal study. (orig.)

  15. Quantitative reconstruction of thermal and dynamic characteristics of lava flow from surface thermal measurements

    Science.gov (United States)

    Korotkii, Alexander; Kovtunov, Dmitry; Ismail-Zadeh, Alik; Tsepelev, Igor; Melnik, Oleg

    2016-06-01

    We study a model of lava flow to determine its thermal and dynamic characteristics from thermal measurements of the lava at its surface. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. We develop a numerical approach to the mathematical problem in the case of steady-state flow. Assuming that the temperature and the heat flow are prescribed at the upper surface of the model domain, we determine the flow characteristics in the entire model domain using a variational (adjoint) method. We have performed computations of model examples and showed that in the case of smooth input data the lava temperature and the flow velocity can be reconstructed with a high accuracy. As expected, a noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. Also we analyse the influence of optimization methods on the solution convergence rate. The proposed method for reconstruction of physical parameters of lava flows can also be applied to other problems in geophysical fluid flows.

  16. Determination of thermal/dynamic characteristics of lava flow from surface thermal measurements

    Science.gov (United States)

    Ismail-Zadeh, Alik; Melnik, Oleg; Korotkii, Alexander; Tsepelev, Igor; Kovtunov, Dmitry

    2016-04-01

    Rapid development of ground based thermal cameras, drones and satellite data allows getting repeated thermal images of the surface of the lava flow. Available instrumentation allows getting a large amount of data during a single lava flow eruption. These data require development of appropriate quantitative techniques to link subsurface dynamics with observations. We present a new approach to assimilation of thermal measurements at lava's surface to the bottom of the lava flow to determine lava's thermal and dynamic characteristics. Mathematically this problem is reduced to solving an inverse boundary problem. Namely, using known conditions at one part of the model boundary we determine the missing condition at the remaining part of the boundary. Using an adjoint method we develop a numerical approach to the mathematical problem based on the determination of the missing boundary condition and lava flow characteristics. Numerical results show that in the case of smooth input data lava temperature and velocity can be determined with a high accuracy. A noise imposed on the smooth input data results in a less accurate solution, but still acceptable below some noise level. The proposed approach to assimilate measured data brings an opportunity to estimate thermal budget of the lava flow.

  17. Electrophysical characteristics of Azospirillum brasilense Sp245 during interaction with antibodies to various cell surface epitopes.

    Science.gov (United States)

    Guliy, Olga I; Matora, Larisa Y; Burygin, Gennady L; Dykman, Lev A; Ostudin, Nikolai A; Bunin, Viktor D; Ignatov, Vladimir V; Ignatov, Oleg V

    2007-11-15

    This work was undertaken to examine the electrooptical characteristics of cells of Azospirillum brasilense Sp245 during their interaction with antibodies developed to various cell surface epitopes. We used the dependences of the cell suspension optical density changes induced by electroorientation on the orienting field frequency (740, 1000, 1450, 2000, and 2800kHz). Cell interactions with homologous strain-specific antibodies to the A. brasilense Sp245 O antigen and with homologous antibodies to whole bacterial cells brought about considerable changes in the electrooptical properties of the bacterial suspension. When genus-specific antibodies to the flagellin of the Azospirillum sheathed flagellum and antibodies to the serologically distinct O antigen of A. brasilense Sp7 were included in the A. brasilense Sp245 suspension, the changes caused in the electrooptical signal were slight and had values close to those for the above changes. These findings agree well with the immunochemical characteristics of the Azospirillum O antigens and with the data on the topographical distribution of the Azospirillum major cell surface antigens. The obtained results can serve as a basis for the development of a rapid test for the intraspecies detection of microorganisms.

  18. Effect of wall cooling on the stability of compressible subsonic flows over smooth humps and backward-facing steps

    Science.gov (United States)

    Al-Maaitah, Ayman A.; Nayfeh, Ali H.; Ragab, Saad A.

    1990-01-01

    The effect of wall cooling on the two-dimensional linear stability of subsonic flows over two-dimensional surface imperfections is investigated. Results are presented for flows over smooth humps and backward-facing steps with Mach numbers up to 0.8. The results show that, whereas cooling decreases the viscous instability, it increases the shear-layer instability and hence it increases the growth rates in the separation region. The coexistence of more than one instability mechanism makes a certain degree of wall cooling most effective. For the Mach numbers 0.5 and 0.8, the optimum wall temperatures are about 80 pct and 60 pct of the adiabatic wall temperature, respectively. Increasing the Mach number decreases the effectiveness of cooling slightly and reduces the optimum wall temperature.

  19. Subsonic pressure distributions around a solid model of an inflatable decelerator attached to the base of an ogive-cylinder

    Science.gov (United States)

    Sawyer, J. W.

    1972-01-01

    A wind-tunnel investigation was conducted at free-stream Mach numbers from 0.20 to 1.00 and corresponding Reynolds numbers, based on maximum afterbody diameter, from 2.25 x one million to 6.90 x one million on a solid model of an attached inflatable decelerator (AID) connected to the base of an ogive-cylinder. Tests were conducted to obtain ram-air and surface pressure distributions about the AID. AID shapes derived for subsonic deployment are dependent on the pressure distributions used in their derivation, and the different shapes obtained are dependent on the Mach number for which the design is made. The resulting pressure distributions were used in a design program to obtain new shapes which were compared with the original pressure-distribution shape.

  20. Hot-wire calibration in subsonic/transonic flow regimes

    Science.gov (United States)

    Nagabushana, K. A.; Ash, Robert L.

    1995-01-01

    A different approach for calibrating hot-wires, which simplifies the calibration procedure and reduces the tunnel run-time by an order of magnitude was sought. In general, it is accepted that the directly measurable quantities in any flow are velocity, density, and total temperature. Very few facilities have the capability of varying the total temperature over an adequate range. However, if the overheat temperature parameter, a(sub w), is used to calibrate the hot-wire then the directly measurable quantity, voltage, will be a function of the flow variables and the overheat parameter i.e., E = f(u,p,a(sub w), T(sub w)) where a(sub w) will contain the needed total temperature information. In this report, various methods of evaluating sensitivities with different dependent and independent variables to calibrate a 3-Wire hot-wire probe using a constant temperature anemometer (CTA) in subsonic/transonic flow regimes is presented. The advantage of using a(sub w) as the independent variable instead of total temperature, t(sub o), or overheat temperature parameter, tau, is that while running a calibration test it is not necessary to know the recovery factor, the coefficients in a wire resistance to temperature relationship for a given probe. It was deduced that the method employing the relationship E = f (u,p,a(sub w)) should result in the most accurate calibration of hot wire probes. Any other method would require additional measurements. Also this method will allow calibration and determination of accurate temperature fluctuation information even in atmospheric wind tunnels where there is no ability to obtain any temperature sensitivity information at present. This technique greatly simplifies the calibration process for hot-wires, provides the required calibration information needed in obtaining temperature fluctuations, and reduces both the tunnel run-time and the test matrix required to calibrate hotwires. Some of the results using the above techniques are presented

  1. Geochemical characteristics and zones of surface snow on east Antarctic Ice Sheet

    Institute of Scientific and Technical Information of China (English)

    KANG Jiancheng; LIU Leibao; QIN Dahe; WANG Dali; WEN Jiahong; TAN Dejun; LI Zhongqin; LI Jun; ZHANG Xiaowei

    2004-01-01

    The surface-snow geochemical characteristics are discussed on the East Antarctic Ice Sheet, depending on the stable isotopes ratios of oxygen and hydrogen, concentration of impurities (soluble-ions and insoluble micro-particle) in surface snow collected on the ice sheet. The purpose is to study geochemical zones on the East Antarctic Ice Sheet and to research sources and transportation route of the water vapor and the impurities in surface snow. It has been found that the ratio coefficients, as S1, d1 in the equation δD = S1δ18O + d1, are changed near the elevation 2000 m on the ice sheet. The weight ratio of Cl(-)/Na+ at the area below the elevation of 2000 m is close to the ratio in the sea salt; but it is about 2 times that of the sea salt, at the inland area up to the elevation of 2000 m. The concentrations of non-sea-salt Ca2+ ion (nssCa2+) and fine-particle increase at the interior up to the elevation 2000 m. At the region below the elevation of 2000 m, the impurity concentration is decreasing with the elevation increasing. Near coastal region, the surface snow has a high concentration of impurity, where the elevation is below 800 m. Combining the translating processes of water-vapor and impurities, it suggests that the region up to the elevation 2000 m is affected by large-scale circulation with longitude-direction, and that water-vapor and impurities in surface snow come from long sources. The region below the elevation 2000 m is affected by some strong cyclones acting at peripheral region of the ice sheet, and the sources of water and impurities could be at high latitude sea and coast. The area below elevation 800 m is affected by local coastal cyclones.

  2. Dynamical characteristics of surface EMG signals of hand grasps via recurrence plot.

    Science.gov (United States)

    Ouyang, Gaoxiang; Zhu, Xiangyang; Ju, Zhaojie; Liu, Honghai

    2014-01-01

    Recognizing human hand grasp movements through surface electromyogram (sEMG) is a challenging task. In this paper, we investigated nonlinear measures based on recurrence plot, as a tool to evaluate the hidden dynamical characteristics of sEMG during four different hand movements. A series of experimental tests in this study show that the dynamical characteristics of sEMG data with recurrence quantification analysis (RQA) can distinguish different hand grasp movements. Meanwhile, adaptive neuro-fuzzy inference system (ANFIS) is applied to evaluate the performance of the aforementioned measures to identify the grasp movements. The experimental results show that the recognition rate (99.1%) based on the combination of linear and nonlinear measures is much higher than those with only linear measures (93.4%) or nonlinear measures (88.1%). These results suggest that the RQA measures might be a potential tool to reveal the sEMG hidden characteristics of hand grasp movements and an effective supplement for the traditional linear grasp recognition methods.

  3. Sensitivity of tropical cyclone characteristics to the radial distribution of sea surface temperature

    Indian Academy of Sciences (India)

    Deepika Rai; S Pattnaik; P V Rajesh

    2016-06-01

    Sea Surface Temperature (SST) is crucial for the development and maintenance of a tropical cyclone(TC) particularly below the storm core region. However, storm data below the core region is the mostdifficult to obtain, hence it is not clear yet that how sensitive the radial distribution of the SST impactthe storm characteristic features such as its inner-core structures, translational speed, track, rainfalland intensity particularly over the Bay of Bengal. To explore the effects of radial SST distributionon the TC characteristics, a series of numerical experiments were carried out by modifying the SSTat different radial extents using two-way interactive, triply-nested, nonhydrostatic Advanced WeatherResearch and Forecast (WRF-ARW) model. It is found that not only the SST under the eyewall (coreregion) contribute significantly to modulate storm track, translational speed and intensity, but also thoseoutside the eyewall region (i.e., 2–2.5 times the radius of maximum wind (RMW)) play a vital role indefining the storm’s characteristics and structure. Out of all the simulated experiments, storm wherethe positive radial change of SST inducted within the 75 km of the storm core (i.e., P75) produced thestrongest storm. In addition, N300 (negative radial changes at 300 km) produced the weakest storm.Further, it is found that SST, stronger within 2–2.5 times of the RMW for P75 experiment, plays adominant role in maintaining 10 m wind speed (WS10), surface entropy flux (SEF) and upward verticalvelocity (w) within the eyewall with warmer air temperature (T) and equivalent potential temperature(θe) within the storm’s eye compared to other experiments.

  4. CFD Simulation and Experimental Study of Winglets at Low Subsonic Flow

    Directory of Open Access Journals (Sweden)

    Sanjay Kumar Sardiwal

    2014-05-01

    Full Text Available A winglet is a device attached at the wingtip, used to improve aircraft efficiency by lowering the induced drag caused by wingtip vortices. It is a vertical or angled extension at the tips of each wing. Winglets work by increasing the effective aspect ratio of a wing without adding greatly to the structural stress and hence necessary weight of the wing structure. This paper describes a CFD 3-dimensional winglets analysis that was performed on a rectangular wing of NACA653218 cross sectional airfoil. The wing is of 660 mm span and 121 mm chord and was analyzed for two shape configurations, semicircle and elliptical. The objectives of the analysis were to compare the aerodynamic characteristics of the two winglet configurations and to investigate the performance of the two winglets shape simulated at selected cant angle of 0, 45 and 60 degrees. The computational simulation was carried out by FLUENT 6.2 solver using Finite Volume Approach. The simulation was done at low subsonic flow and at various angles of attack using Spalart-Allmaras couple implicit solver. A comparison of aerodynamics characteristics of lift coefficient CL , drag coefficient CD and lift to drag ratio, L/D was made and it was found that the addition of the elliptical and semi circular winglet gave a larger lift curve slope and higher Lift-to-Drag Ratio in comparison to the baseline wing alone. Elliptical winglet with 45 degree cant angle was the best overall design giving about 8 percent increase in lift curve slope and the best Lift-to-Drag Ratio.

  5. Nonlinear friction characteristics between silica surfaces in high pH solution.

    Science.gov (United States)

    Taran, Elena; Kanda, Yoichi; Vakarelski, Ivan U; Higashitani, Ko

    2007-03-15

    Molecular-scale characteristics of friction forces between silica particles and silica wafers in aqueous solutions of the normal (pH 5.6) and high pH (pH 10.6) are investigated, using the lateral force measuring procedure of the atomic force microscope (AFM). Various significant differences of friction characteristics between solutions of normal and high pH's are found. In the case of solutions of normal pH, the friction force increases linearly with increasing loading force, as the Amonton's law for solid bodies indicates. However, in the case of high pH solutions, the increasing rate with the loading force is considerably reduced in the low loading region, but the value increases abruptly above a critical loading force to overcome the magnitude of friction force of normal pH above the region of very high loading. It is very interesting to know that this nonlinear force curve at high pH is independent of the atomic-scale roughness of surfaces, although the magnitude of friction is greatly influenced by the roughness in the case of normal pH. The reason why the friction at high pH is independent of the surface roughness is postulated to be due to the hairy-like layer formed on the silica surface. The existence of hairy-like layers at high pH is proven directly by the dynamic method of normal force measurements with AFM and the thickness is estimated to be at least ca. 1.3 nm.

  6. Spatial Aggregation of Land Surface Characteristics: Impact of resolution of remote sensing data on land surface modelling

    NARCIS (Netherlands)

    Pelgrum, H.

    2000-01-01

    Land surface models describe the exchange of heat, moisture and momentum between the land surface and the atmosphere. These models can be solved regionally using remote sensing measurements as input. Input variables which can be derived from remote sensing measurements are surface albedo, surface te

  7. Do skeletal cephalometric characteristics correlate with condylar volume, surface and shape? A 3D analysis

    Directory of Open Access Journals (Sweden)

    Saccucci Matteo

    2012-05-01

    Full Text Available Abstract Objective The purpose of this study was to determine the condylar volume in subjects with different mandibular divergence and skeletal class using cone-beam computed tomography (CBCT and analysis software. Materials and methods For 94 patients (46 females and 48 males; mean age 24.3 ± 6.5 years, resultant rendering reconstructions of the left and right temporal mandibular joints (TMJs were obtained. Subjects were then classified on the base of ANB angle the GoGn-SN angle in three classes (I, II, III . The data of the different classes were compared. Results No significant difference was observed in the whole sample between the right and the left sides in condylar volume. The analysis of mean volume among low, normal and high mandibular plane angles revealed a significantly higher volume and surface in low angle subjects (p  Class III subjects also tended to show a higher condylar volume and surface than class I and class II subjects, although the difference was not significant. Conclusions Higher condylar volume was a common characteristic of low angle subjects compared to normal and high mandibular plane angle subjects. Skeletal class also appears to be associated to condylar volume and surface.

  8. Aerodynamic characteristics of a large-scale hybrid upper surface blown flap model having four engines

    Science.gov (United States)

    Carros, R. J.; Boissevain, A. G.; Aoyagi, K.

    1975-01-01

    Data are presented from an investigation of the aerodynamic characteristics of large-scale wind tunnel aircraft model that utilized a hybrid-upper surface blown flap to augment lift. The hybrid concept of this investigation used a portion of the turbofan exhaust air for blowing over the trailing edge flap to provide boundary layer control. The model, tested in the Ames 40- by 80-foot Wind Tunnel, had a 27.5 deg swept wing of aspect ratio 8 and 4 turbofan engines mounted on the upper surface of the wing. The lift of the model was augmented by turbofan exhaust impingement on the wind upper-surface and flap system. Results were obtained for three flap deflections, for some variation of engine nozzle configuration and for jet thrust coefficients from 0 to 3.0. Six-component longitudinal and lateral data are presented with four engine operation and with the critical engine out. In addition, a limited number of cross-plots of the data are presented. All of the tests were made with a downwash rake installed instead of a horizontal tail. Some of these downwash data are also presented.

  9. Comparison of Flow Characteristics of Different Sphere Geometries Under the Free Surface Effect

    Directory of Open Access Journals (Sweden)

    Sahin B.

    2013-04-01

    Full Text Available Comparison of the experimental results of turbulent flow structures between a smooth sphere and a sphere with a vent hole, roughened, and o-ring is presented in the presence of a free-surface. Dye visualization and particle image velocimetry (PIV techniques were performed to examine effects of passive control methods on the sphere wake for Reynolds number Re = 5000 based on the sphere diameter with a 42.5mm in an open water channel. Instantaneous and time-averaged flow patterns in the wake region of the sphere were examined from point of flow physics for the different sphere locations in the range of 0≤h/D≤2.0 where h was the space between the top point of the sphere and the free surface. The ratio of ventilation hole to sphere diameter was 0.15, o-ring was located at 55° with a 2 mm from front stagnation point of the sphere and roughened surface was formed by means of totally 410 circular holes with a 3 mm diameter and around 2 mm depth in an equilateral triangle arrangement. The flow characteristics of instantaneous velocity vectors, vorticity contours, time-averaged streamline patterns, Reynolds stress correlations and streamwise and cross-stream velocity fluctuations for both the smooth and passively controlled sphere were interpreted.

  10. Comparison of Flow Characteristics of Different Sphere Geometries Under the Free Surface Effect

    Science.gov (United States)

    Ozgoren, M.; Dogan, S.; Okbaz, A.; Aksoy, M. H.; Sahin, B.; Akıllı, H.

    2013-04-01

    Comparison of the experimental results of turbulent flow structures between a smooth sphere and a sphere with a vent hole, roughened, and o-ring is presented in the presence of a free-surface. Dye visualization and particle image velocimetry (PIV) techniques were performed to examine effects of passive control methods on the sphere wake for Reynolds number Re = 5000 based on the sphere diameter with a 42.5mm in an open water channel. Instantaneous and time-averaged flow patterns in the wake region of the sphere were examined from point of flow physics for the different sphere locations in the range of 0≤h/D≤2.0 where h was the space between the top point of the sphere and the free surface. The ratio of ventilation hole to sphere diameter was 0.15, o-ring was located at 55° with a 2 mm from front stagnation point of the sphere and roughened surface was formed by means of totally 410 circular holes with a 3 mm diameter and around 2 mm depth in an equilateral triangle arrangement. The flow characteristics of instantaneous velocity vectors, vorticity contours, time-averaged streamline patterns, Reynolds stress correlations and streamwise and cross-stream velocity fluctuations for both the smooth and passively controlled sphere were interpreted.

  11. Trends of urban surface temperature and heat island characteristics in the Mediterranean

    Science.gov (United States)

    Benas, Nikolaos; Chrysoulakis, Nektarios; Cartalis, Constantinos

    2016-09-01

    Urban air temperature studies usually focus on the urban canopy heat island phenomenon, whereby the city center experiences higher near surface air temperatures compared to its surrounding non-urban areas. The Land Surface Temperature (LST) is used instead of urban air temperature to identify the Surface Urban Heat Island (SUHI). In this study, the nighttime LST and SUHI characteristics and trends in the seventeen largest Mediterranean cities were investigated, by analyzing satellite observations for the period 2001-2012. SUHI averages and trends were based on an innovative approach of comparing urban pixels to randomly selected non-urban pixels, which carries the potential to better standardize satellite-derived SUHI estimations. A positive trend for both LST and SUHI for the majority of the examined cities was documented. Furthermore, a 0.1 °C decade-1 increase in urban LST corresponded to an increase in SUHI by about 0.04 °C decade-1. A longitudinal differentiation was found in the urban LST trends, with higher positive values appearing in the eastern Mediterranean. Examination of urban infrastructure and development factors during the same period revealed correlations with SUHI trends, which can be used to explain differences among cities. However, the majority of the cities examined show considerably increased trends in terms of the enhancement of SUHI. These findings are considered important so as to promote sustainable urbanization, as well as to support the development of heat island adaptation and mitigation plans in the Mediterranean.

  12. Rarefied flow and heat transfer characteristics over a vertical stretched surface

    Directory of Open Access Journals (Sweden)

    Wael Al-Kouz

    2016-08-01

    Full Text Available Similarity solution for the steady-state two-dimensional laminar natural convection heat transfer for a rarefied flow over a linearly vertical stretched surface is being proposed. Similarity conditions are obtained for the boundary layer equations for the vertical flat plate subjected to power law for the temperature variations. It is found that the similarity solution exists for linear temperature variation and linear stretching surface. The study shows that there are three different parameters affecting the flow and heat transfer characteristics for the rarefied flow over a vertical linearly stretched surface. These parameters represent the effects of the velocity slip (K1, temperature jump (K2, and the Prandtl number (Pr. The effects of these parameters are presented. It is found that the velocity slip parameter affects both the hydrodynamic and thermal behaviors of such flows. Correlations for the skin friction as well as Nusselt number are being proposed in terms of Grashof number (Grx, the slip velocity parameter (K1, and the temperature jump parameter (K2.

  13. Synthesis and surface characteristics of nanosilica produced from alkali-extracted rice husk ash

    Energy Technology Data Exchange (ETDEWEB)

    Liou, Tzong-Horng, E-mail: thliou@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gungjuan Rd., Taipei 24301, Taiwan (China); Yang, Chun-Chen [Department of Chemical Engineering, Ming Chi University of Technology, 84 Gungjuan Rd., Taipei 24301, Taiwan (China)

    2011-04-25

    Rice husk is a form of agricultural biomass that provides an abundant silicon source. This study used rice husk as a raw material to prepare nanosilica without adding an extra surfactant. This work investigated a dissolution-precipitation technique as a function of acid treatment, sodium silicate concentration, gelation pH, aging temperature, and aging time to establish optimum conditions for preparing silica nanoparticles. Experimental results showed that silica produced by hydrochloric acid possesses higher surface area than that of sulfuric, oxalic, and citric acids. Surface characteristics of the sample depend mainly upon gelation pH. The highest surface area and pore volume of silica samples were 634 m{sup 2}/g and 0.811 cm{sup 3}/g. Pore diameters were controllable from 3 to 9 nm by adjusting the solution pH value. Particles had a uniform size of 5-30 nm. The objective of this study was to develop a method of nanosilica preparation that enhances the economic benefits of re-using rice husk waste.

  14. The role of angiogenesis in implant dentistry part I: Review of titanium alloys, surface characteristics and treatments

    Science.gov (United States)

    Asatourian, Armen; Garcia-Godoy, Franklin; Sheibani, Nader

    2016-01-01

    Background Angiogenesis plays an important role in osseointegration process by contributing to inflammatory and regenerative phases of surrounding alveolar bone. The present review evaluated the effect of titanium alloys and their surface characteristics including: surface topography (macro, micro, and nano), surface wettability/energy, surface hydrophilicity or hydrophobicity, surface charge, and surface treatments of dental implants on angiogenesis events, which occur during osseointegration period. Material and Methods An electronic search was performed in PubMed, MEDLINE, and EMBASE databases via OVID using the keywords mentioned in the PubMed and MeSH headings regarding the role of angiogenesis in implant dentistry from January 2000-April 2014. Results Of the 2,691 articles identified in our initial search results, only 30 met the inclusion criteria set for this review. The hydrophilicity and topography of dental implants are the most important and effective surface characteristics in angiogenesis and osteogenesis processes. The surface treatments or modifications of dental implants are mainly directed through the enhancement of biological activity and functionalization in order to promote osteogenesis and angiogenesis, and accelerate the osseointegration procedure. Conclusions Angiogenesis is of great importance in implant dentistry in a manner that most of the surface characteristics and treatments of dental implants are directed toward creating a more pro-angiogenic surface on dental implants. A number of studies discussed the effect of titanium alloys, dental implant surface characteristic and treatments on agiogenesis process. However, clinical trials and in-vivo studies delineating the mechanisms of dental implants, and their surface characteristics or treatments, action in angiogenesis processes are lagging. Key words:Angiogenesis, dental implant, osseointergration. PMID:27031073

  15. Residual stress and electromagnetic characteristics in loop type frequency selective surface embedded hybrid structures

    Energy Technology Data Exchange (ETDEWEB)

    Park, Kyung Mi; Seo, Yun Seok; Chun, Heoung Jae [Yonsei University, Seoul (Korea, Republic of); Hong, Ik Pyo [Kongju National University, Cheonan (Korea, Republic of); Park, Yong Bae [Ajoo University, Suwon (Korea, Republic of); Kim, Yoon Jae [Agency for defense development, Daejeon (Korea, Republic of)

    2015-01-15

    Residual stresses occur in frequency-selective surface (FSS)-embedded composite structures after co-curing due to differences between the coefficients of thermal expansion between composite skins and FSSs. Furthermore, the electromagnetic characteristics may be affected by the deformation of the FSS pattern by residual stresses. Therefore, we studied the changes in electromagnetic characteristics due to the deformation of FSS, using residual stresses to deform loop-type FSS-embedded hybrid composites. We considered the effects of loop-type FSS patterns of equal dimension as well as the stacking sequences of composite laminates on the electromagnetic characteristics of FSSs: Square loop, triangular loop and circular loop. The stacking sequences of composite laminates considered in this study were [0]{sub 8}, [0/90]{sub 4}, [+-45]{sub 4} and [0/+-45/90]{sub 2}. The FSS was located between composite laminates in the middle plane. To determine the residual stresses and deformations in the FSS embedded laminate structures, the thermal loading condition in the finite element analysis was induced by cooling the hybrid structures from 125 .deg. C to 20 .deg. C based on the cure cycle of the composite. Also, the electromagnetic reflection characteristics of the hybrid structures were predicted using deformed models by residual stresses, considering the effects of stacking sequence of composite laminates. The results showed that the maximum residual stresses and deformations were produced in the [0]{sub 8} composites with all three loop-types of FSS pattern. However, the maximum resonance frequency shifts occurred in the square and triangle loop-types with stacking sequence of [0]{sub 8} , while the maximum resonance frequency shift occurred in the circular loop-type with stacking sequence of [0/+-45/90]{sub 2}.

  16. Temporal and spatial characteristics of surface ozone depletion events from measurements over the Arctic Ocean

    Science.gov (United States)

    Halfacre, J. W.; Knepp, T. N.; Stephens, C. R.; Pratt, K. A.; Shepson, P.; Simpson, W. R.; Peterson, P. K.; Walsh, S. J.; Matrai, P. A.; Bottenheim, J. W.; Netcheva, S.; Perovich, D. K.; Richter, A.

    2012-12-01

    Arctic tropospheric ozone depletion events (ODEs) have been studied primarily from coastal sites since the mid 1980s with only a few studies occurring over the Arctic Ocean, the hypothesized site of initiation. Despite a multitude of studies, some basic characteristics of ODEs remain poorly defined, including their temporal, spatial, and meteorological characteristics. Several deployments of autonomous, ice-tethered buoys (O-Buoys) were used to elucidate such characteristics from both the Arctic Ocean and coastal sites. The apparent first order decays imply an ozone lifetime (median of 11 hours) that would correspond to a very large BrO concentration, relative to BrO observations obtained from the buoys. These results suggest that ODEs involve a large, unaccounted for source of bromine atoms, that there is a significant contribution from other mechanisms possibly not involving bromine, or that the majority of observed ODEs represent advection of previously-depleted air to the buoy site, even in the Arctic Ocean. Using backward air mass trajectories, the spatial scales for ODEs (defined by time periods with O3 ≤ 15 nmol/mol) were estimated to be ~1800 km (mode), suggesting that most of the lower troposphere above the Arctic Ocean is frequently, at least partially, depleted of ozone. Using the same method, areas estimated to be highly depleted of O3 (ice-tethered O-Buoys provide unique data to study the characteristics of ODEs; however, more remote and simultaneous surface observations over the Arctic Ocean are necessary to enable study of both the site(s) and mechanism(s) of ODE initiation.

  17. Wind Tunnel Application of a Pressure-Sensitive Paint Technique to a Faceted Missile Model at Subsonic and Transonic Speeds

    Science.gov (United States)

    Erickson, Gary E.

    2004-01-01

    A pressure-sensitive paint (PSP) technique was applied in a wind tunnel experiment in the NASA Langley Research Center 8-Foot Transonic Pressure Tunnel to quantify the vortex-induced surface static pressures on a slender, faceted missile model at subsonic and transonic speeds. Satisfactory global calibrations of the PSP were obtained at =0.70, 0.90, and 1.20, angles of attack from 10 degrees to 20 degrees, and angles of sideslip of 0 and 2.5 degrees using an in-situ method featuring the simultaneous acquisition of electronically-scanned pressures (ESP) at 57 discrete locations on the model. Both techniques clearly revealed the significant influence on the surface pressure distributions of the vortices shed from the sharp, chine-like leading edges. The mean error in the PSP measurements relative to the ESP data was approximately 0.6 percent at M infinity =0.70 and 2.6 percent at M infinity =0.90 and 1.20. The vortex surface pressure signatures obtained from the PSP and ESP techniques were correlated with the off-surface vortex cross-flow structures obtained using a laser vapor screen (LVS) flow visualization technique. The on-surface and off-surface techniques were complementary, since each provided details of the vortex-dominated flow that were not clear or apparent in the other.

  18. The spatial geochemical characteristics of groundwater and surface in the Tuul River basin, Ulaanbatar, Mongolia

    Science.gov (United States)

    Batdelger, Odsuren; Tsujimura, Maki; Zorigt, Byambasuren; Togtokh, Enkhjargal

    2017-04-01

    The capital city, Ulaanbaatar, is located along the Tuul River and its water supply totally dependent on the groundwater, which comes from the aquifer of the Tuul River. Due to the rapid growth of the population and the increasing human pressures in this basin, water quality has been deteriorating and has become a crucial issue for sustainable environmental and socio-economic development. Hydro-chemical and stable isotope tracing approaches were applied into the groundwater and surface water in order to study geochemical characteristics and groundwater and surface water interaction. The Tuul River water was mostly characterized by the Ca-HCO3 type, spatially variable and it changed into Ca-Na-HCO3 type in the downstream of the city after wastewater (WW) meets the river. Also, electrical conductivity (EC) values of Tuul River are increasing gradually with distance and it increased more than 2 times after WW meets the stream, therefore anthropogenic activities influence to the downstream of the river. The dominant hydro-chemical facies of groundwater were the Ca-HCO3 type, which represents 83% of the total analyzed samples, while Ca- HCO3-Cl-NO3, Na-HCO3, Ca-HCO3-SO4 each represent 4%, and Ca-mixed and Ca-Mg-HCO3 each represent 2% of the total samples. This suggests that groundwater chemistry is controlled by rock-water interaction and anthropogenic pollution. The floodplain groundwater chemical characteristics were similar to Tuul River water and showing lowest EC values. Groundwater far from floodplain showed higher EC (mean value of 498 μs/cm) values than river waters and floodplain groundwater. Also, different kinds of hydro-chemical facies were observed. The stable isotopic compositions revealed less evaporation effect on the groundwater and surface water, as well as an altitude effect in the river water. The similarity of stable isotopes and chemical characteristics of floodplain groundwater and river water suggests that alluvial groundwater is recharged by

  19. The role of current characteristics of the arc evaporator in formation of the surface metal-coating composite

    Science.gov (United States)

    Plikhunov, V. V.; Petrov, L. M.; Grigorovich, K. V.

    2016-07-01

    The influence of current characteristics of the vacuum arc evaporator on the interaction process of plasma streams with the surface under treatment during generation of the physicochemical properties of the formed metal-coating composite is considered. It is shown that the interaction of plasma streams with the processed surface provides surface heating, defects elimination, change in energy properties, and mass transfer of plasma stream elements activating surface diffusion processes whose intensity is evaluated by the arc current magnitude and location of the processed surface relative to the cathode axis.

  20. Characteristics of Speed Line Cutter and Fringe Analysis of Workpiece Surface

    Directory of Open Access Journals (Sweden)

    Shuai Wang

    2014-02-01

    Full Text Available Easy to operate, speed line cutter has a high machining cost performance, so is very popular among the majority of users. The precision of guide rails, screws and nuts used in most of the machines is not high, and the machine control cannot compensate for the screw pitch error, clearance during the transmission and machining error due to electrode wear. Furthermore, control signal may also be lost in control process. The development of speed line cutter focuses on the quality and machining stability of CNC speed line cutter. This article makes an analysis about the impact of machine’s inherent characteristics on machining workpiece surface, and concludes that analysis shall be made on the irregular fringe, therefore to heighten the machining precision.

  1. Tailoring odorant-binding protein coatings characteristics for surface acoustic wave biosensor development

    Science.gov (United States)

    Di Pietrantonio, F.; Benetti, M.; Dinca, V.; Cannatà, D.; Verona, E.; D'Auria, S.; Dinescu, M.

    2014-05-01

    In this study, wild type bovine odorant-binding proteins (wtbOBPs) were deposited by matrix-assisted pulsed laser evaporation (MAPLE) and utilized as active material on surface acoustic wave (SAW) biosensors. Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) were used to determine the chemical, morphological characteristics of the protein thin films. The FTIR data demonstrates that the functional groups of wtbOBPs do not suffer significant changes in the MAPLE-deposited films when compared to the reference one. The topographical studies show that the homogeneity, density and the roughness of the coatings are related mainly to the laser parameters (fluence and number of pulses). SAW biosensor responses to different concentrations of R-(-)-1-octen-3-ol (octenol) and R-(-)-carvone (carvone) were evaluated. The obtained sensitivities, achieved through the optimization of deposition parameters, demonstrated that MAPLE is a promising deposition technique for SAW biosensor implementation.

  2. Influence of substrate process tolerances on transmission characteristics of frequency-selective surface

    Institute of Scientific and Technical Information of China (English)

    He Zhang; Jun Lu; Guancheng Sun; Hongliang Xiao

    2008-01-01

    Frequency-selective surface (FSS) is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units (or apertures) arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate's thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.

  3. Solar absorption characteristics of several coatings and surface finishes. [for solar energy collectors

    Science.gov (United States)

    Lowery, J. R.

    1977-01-01

    Solar absorption characteristics are established for several films potentially favorable for use as receiving surfaces in solar energy collectors. Included in the investigation were chemically produced black films, black electrodeposits, and anodized coatings. It was found that black nickel exhibited the best combination of selective optical properties of any of the coatings studied. A serious drawback to black nickel was its high susceptibility to degradation in the presence of high moisture environments. Electroplated black chrome generally exhibited high solar absorptivities, but the emissivity varied considerably and was also relatively high under some conditions. The black chrome had the greatest moisture resistance of any of the coatings tested. Black oxide coatings on copper and steel substrates showed the best combination of selective optical properties of any of the chemical conversion films studied.

  4. Improvement in characteristics of natural rubber nanocomposite by surface modification of multi-walled carbon nanotubes

    Science.gov (United States)

    Takeuchi, Kenji; Noguchi, Toru; Ueki, Hiroyuki; Niihara, Ken-ichi; Sugiura, Tomoyoshi; Inukai, Shigeki; Fujishige, Masatsugu

    2015-05-01

    We aim to develop high-level applications of NR through the innovative use of multi-walled carbon nanotubes (MWCNTs) to improve reinforcing performance and thermal resistance. In this study, we examined the structures and characteristics of composite materials in which NR was the matrix and MWCNTs were the fillers. We studied the properties of composites containing surface-activated MWCNTs with three different diameters. The results show that the reinforcing performance improves as MWCNT diameter decreases, while thermal resistance improves as we decrease the heat-treatment temperature. The latter occurs because adherence between MWCNTs and NR becomes stronger at lower heat-treatment temperatures. We also found that for practical applications, we need to control active sites on MWCNTs to balance adhesion against thermal resistance.

  5. Numerical Analysis of Aerodynamic Characteristics of the Finned Surfaces with Cross-inclined Fins

    Directory of Open Access Journals (Sweden)

    Lagutin A. E.

    2016-12-01

    Full Text Available This paper presents results of numerical research and analyses air-side hydraulic performance of tube bundles with cross inclined fins. The numerical simulation of the fin-tube heat exchanger was performed using the Comsol Femlab software. The results of modeling show the influence of fin inclination angle and tube pitch on hydraulic characteristics of finned surfaces. A series of numerical tests were carried out for tube bundles with different inclination angles (γ =900, 850, 650, 60, the fin pitch u=4 mm. The results indicate that tube bundles with cross inclined fins can significantly enhance the average integral value of the air flow rate in channel between fins in comparison with conventional straight fins. Aerodynamic processes on both sides of modificated channel between inclined fins were analyzed. The verification procedures for received results of numerical modeling with experimental data were performed.

  6. Characteristics of high power diode laser removal of multilayer chlorinated rubber coatings from concrete surfaces

    Science.gov (United States)

    Schmidt, Marc J. J.; Li, Lin; Spencer, Julian T.

    1999-08-01

    This paper reports the technical feasibility and process characteristics of removing chlorinated rubber (CR) coatings from concrete surfaces utilising a 60 W continuous wave (cw) diode laser operating at 810 nm wavelength. Coating layers of various thickness have been removed under an oxygen shroud-gas, as well as Ar and N 2. Optical microscopy and energy dispersive analysis of X-rays (EDX) have been utilised to verify this. The reflectivity properties of the CR material from the visible to the near infrared wavelengths, as well as their behaviour under high temperatures have been examined with a normal incidence spectrometer and a differential thermal analysis/thermal gravimetric analysis (DTA/TGA) system. The resulting drop in reflectivity explains the possibility of sustaining the combustion, even though the reflection coefficient of white CR at 810 nm is almost 100%.

  7. Linear coloring of graphs embeddable in a surface of nonnegative characteristic

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A proper vertex coloring of a graph G is linear if the graph induced by the vertices of any two color classes is the union of vertex-disjoint paths. The linear chromatic number lc(G) of the graph G is the smallest number of colors in a linear coloring of G. In this paper, we prove that every graph G with girth g(G) and maximum degree Δ(G) that can be embedded in a surface of nonnegative characteristic has lc(G) = Δ(2G )+ 1 if there is a pair (Δ, g) ∈ {(13, 7), (9, 8), (7, 9), (5, 10), (3, 13)} such that G satisfies Δ(G) Δ and g(G) g.

  8. Linear coloring of graphs embeddable in a surface of nonnegative characteristic

    Institute of Scientific and Technical Information of China (English)

    WANG WeiFan; LI Chao

    2009-01-01

    A proper vertex coloring of a graph G is linear if the graph induced by the vertices of any two color classes is the union of vertex-disjoint paths. The linear chromatic number lc(G) of the graph G is the smallest number of colors in a linear coloring of G. In this paper, we prove that every graph G with girth g(G) and maximum degree △(G) that can be embedded in a surface of nonnegative characteristic has lc(G) = 「△(G)/2」+ 1 if there is a pair (△,g) ∈ {(13, 7), (9, 8), (7, 9), (5, 10), (3, 13)} such that G satisfies △(G) ≥ △ and g(G) ≥ g.

  9. Tailoring odorant-binding protein coatings characteristics for surface acoustic wave biosensor development

    Energy Technology Data Exchange (ETDEWEB)

    Di Pietrantonio, F., E-mail: fabio.dp@idasc.cnr.it [Institute of Acoustics and Sensors “O. M. Corbino”, National Research Council of Italy, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Benetti, M. [Institute of Acoustics and Sensors “O. M. Corbino”, National Research Council of Italy, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Dinca, V. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125 Magurele (Romania); Cannatà, D. [Institute of Acoustics and Sensors “O. M. Corbino”, National Research Council of Italy, Via del Fosso del Cavaliere 100, 00133 Rome (Italy); Verona, E. [Institute for Photonics and Nanotechnologies, National Research Council of Italy, Via del Cineto Romano 42, 00156 Rome (Italy); D’Auria, S. [Institute of Protein Biochemistry, National Research Council of Italy, Via Pietro Castellino 111, 80131 Naples (Italy); Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, PO Box MG-16, 077125 Magurele (Romania)

    2014-05-01

    In this study, wild type bovine odorant-binding proteins (wtbOBPs) were deposited by matrix-assisted pulsed laser evaporation (MAPLE) and utilized as active material on surface acoustic wave (SAW) biosensors. Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) were used to determine the chemical, morphological characteristics of the protein thin films. The FTIR data demonstrates that the functional groups of wtbOBPs do not suffer significant changes in the MAPLE-deposited films when compared to the reference one. The topographical studies show that the homogeneity, density and the roughness of the coatings are related mainly to the laser parameters (fluence and number of pulses). SAW biosensor responses to different concentrations of R-(–)-1-octen-3-ol (octenol) and R-(–)-carvone (carvone) were evaluated. The obtained sensitivities, achieved through the optimization of deposition parameters, demonstrated that MAPLE is a promising deposition technique for SAW biosensor implementation.

  10. Radiation characteristics of input power from surface wave sustained plasma antenna

    Science.gov (United States)

    Naito, T.; Yamaura, S.; Fukuma, Y.; Sakai, O.

    2016-09-01

    This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input power is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.

  11. Radiation characteristics of input power from surface wave sustained plasma antenna

    Energy Technology Data Exchange (ETDEWEB)

    Naito, T., E-mail: Naito.Teruki@bc.MitsubishiElectric.co.jp [Advanced Technology R& D Center, Mitsubishi Electric Corporation, Amagasaki, Hyogo 661-8661 (Japan); Yamaura, S. [Information Technology R& D Center, Mitsubishi Electric Corporation, Kamakura, Kanagawa 247-8501 (Japan); Fukuma, Y. [Communication System Center, Mitsubishi Electric Corporation, Amagasaki, Hyogo 661-8661 (Japan); Sakai, O. [Department of Electronic System Engineering, The University of Shiga Prefecture, Hikone, Shiga 522-8533 (Japan)

    2016-09-15

    This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input power is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.

  12. Hydrogen chloride heterogeneous chemistry on frozen water particles in subsonic aircraft plume. Laboratory studies and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Persiantseva, N.V.; Popovitcheva, O.B.; Rakhimova, T.V. [Moscow State Univ. (Russian Federation)

    1997-12-31

    Heterogeneous chemistry of HCl, as a main reservoir of chlorine content gases, has been considered after plume cooling and ice particle formation. The HCl, HNO{sub 3}, N{sub 2}O{sub 5} uptake efficiencies by frozen water were obtained in a Knudsen-cell flow reactor at the subsonic cruise conditions. The formation of ice particles in the plume of subsonic aircraft is simulated to describe the kinetics of gaseous HCl loss due to heterogeneous processes. It is shown that the HCl uptake by frozen water particles may play an important role in the gaseous HCl depletion in the aircraft plume. (author) 14 refs.

  13. The surface discharge and breakdown characteristics of HTS DC cable and stop joint box

    Science.gov (United States)

    Kim, W. J.; Kim, H. J.; Cho, J. W.; Kim, S. H.

    2014-09-01

    A high temperature superconducting (HTS) DC cable system consists of a HTS cable and cable joint. The HTS DC cable should be electrically connected in joint boxes because of the unit length of HTS cable is limited to several-hundred meters. In particular, the stop joint box (SJB) must be developed for a compact cooling system. Polypropylene laminated paper (PPLP) and epoxy maybe used as insulating materials for HTS DC cable and SJB. To develop a HTS DC cable, it is necessary to develop the cryogenic insulation technology, materials and the joint methods. In this paper, we will mainly discuss on the DC and impulse characteristics of epoxy and PPLP in liquid nitrogen (LN2). The surface discharge characteristics of epoxy included fillers, PPLP and epoxy with PPLP composite (epoxy + PPLP) were measured under 0.4 MPa. Also, the PPLP-insulated mini-model cable was fabricated and then DC, impulse and DC polarity reversal breakdown strength of mini-model cable under 0.4 MPa were investigated.

  14. Optical characteristics of the filamentary and diffuse modes in surface dielectric barrier discharge

    Science.gov (United States)

    Zhang, Ying; Li, Jie; Jiang, Nan; Shang, Ke-Feng; Lu, Na; Wu, Yan

    2016-11-01

    Surface dielectric barrier discharge (DBD) plasmas generally exhibits filamentary and diffuse discharges at atmospheric air. The focus of this investigation is on the different optical characteristics and quantitative research about morphological features of two discharge modes. The temporally and spatially resolved characteristics of discharge phenomenon together with the gas temperature are presented with microsecond time scale. Discharge area is estimated by the sum of pixels that equal to "1" in MATLAB software. The formation of diffuse plasma mainly depends on an increase of the ionization coefficient and a creation of sufficient seed electrons by the Penning effect at low electric fields. Accordingly, experimental measurements show that diffuse discharge during the negative half cycle has good uniformity and stability compared with filamentary discharge during the positive half cycle. The rotational temperatures of plasma are determined by comparing the experimental spectra with the simulated spectra that have been investigated. The plasma gas temperature keeps almost constant in the filamentary discharge phase and subsequently increased by about 115 K during the diffuse discharge. In addition, it is shown to be nearly identical in the axial direction. Non-uniform temperature distribution can be observed in the radial direction with large fluctuations. The plasma length is demonstrated almost the same between two discharge modes.

  15. Effects of muscle fibre shortening on the characteristics of surface motor unit potentials.

    Science.gov (United States)

    Rodriguez-Falces, Javier; Place, Nicolas

    2014-02-01

    Traditionally, studies dealing with muscle shortening have concentrated on assessing its impact on conduction velocity, and to this end, electrodes have been located between the end-plate and tendon regions. Possible morphologic changes in surface motor unit potentials (MUPs) as a result of muscle shortening have not, as yet, been evaluated or characterized. Using a convolutional MUP model, we investigated the effects of muscle shortening on the shape, amplitude, and duration characteristics of MUPs for different electrode positions relative to the fibre-tendon junction and for different depths of the MU in the muscle (MU-to-electrode distance). It was found that the effects of muscle shortening on MUP morphology depended not only on whether the electrodes were between the end-plate and the tendon junction or beyond the tendon junction, but also on the specific distance to this junction. When the electrodes lie between the end-plate and tendon junction, it was found that (1) the muscle shortening effect is not important for superficial MUs, (2) the sensitivity of MUP amplitude to muscle shortening increases with MU-to-electrode distance, and (3) the amplitude of the MUP negative phase is not affected by muscle shortening. This study provides a basis for the interpretation of the changes in MUP characteristics in experiments where both physiological and geometrical aspects of the muscle are varied.

  16. Frequency characteristic of response of surface air pressure to changes in flux of cosmic rays

    Science.gov (United States)

    Bogdanov, M. B.

    2014-11-01

    We compare the series of daily-average values of the surface air pressure for De Bilt and Lugano meteorological stations with subtracted linear trends and seasonal harmonics, as well as the series of the flux of galactic cosmic rays (GCRs) at Jungfraujoch station with subtracted moving average over 200 days. Using the method of superposed epochs, we show that the Forbush decreases at both stations are accompanied by increased pressure. Spectral analysis allows us to conclude that the analyzed series are characterized by nonzero coherence in almost the entire frequency range: from 0.02 day-1 day up to the Nyquist frequency of 0.5 day-1. Using changes in the GCR flux as a probing signal, we obtain amplitude-frequency characteristics of the pressure reaction. For both stations, these characteristics are in qualitative agreement with each other and indicate that the atmospheric response can be described by a second-order linear dynamic system that has wide resonance with a maximum at a frequency of 0.15 day-1.

  17. Numerical methods and a computer program for subsonic and supersonic aerodynamic design and analysis of wings with attainable thrust considerations

    Science.gov (United States)

    Carlson, H. W.; Walkley, K. B.

    1984-01-01

    This paper describes methodology and an associated computer program for the design of wing lifting surfaces with attainable thrust taken into consideration. The approach is based on the determination of an optimum combination of a series of candidate surfaces rather than the more commonly used candidate loadings. Special leading-edge surfaces are selected to provide distributed leading-edge thrust forces which compensate for any failure to achieve the full theoretical leading-edge thrust, and a second series of general candidate surfaces is selected to minimize drag subject to constraints on the lift coefficient and, if desired, on the pitching moment coefficient. A primary purpose of the design approach is the introduction of attainable leading-edge thrust considerations so that relatively mild camber surfaces may be employed in the achievement of aerodynamic efficiencies comparable to those attainable if full theoretical leading-edge thrust could be achieved. The program provides an analysis as well as a design capability and is applicable to both subsonic and supersonic flow.

  18. Characteristics of surface layer proteins from two new and native strains of Lactobacillus brevis.

    Science.gov (United States)

    Mobarak Qamsari, Elahe; Kasra Kermanshahi, Rouha; Erfan, Mohammad; Ghadam, Parinaz; Sardari, Soroush; Eslami, Neda

    2017-02-01

    In this work, some important characteristics of surface layer (S-layer) proteins extracted from two new and native Lactobacillus strains, L.brevis KM3 and L.brevis KM7, were investigated. The presence of S-layer on the external surface of L.brevis KM3 was displayed by thin sectioning and negative staining. SDS-PAGE analysis were shown same dominant protein bands approximately around 48kDa for both S-layer proteins. Moreover, the S-layer reappeared when LiCl treated cells were allowed to grow again. Protein secondary structure and thermal behavior were evaluated by using circular dichroism (CD) and differential scanning calorimetry (DSC), respectively. Both S-layer proteins had high content of β-sheet and low amount of α-helix. The thermograms of lyophilized S-layer proteins of L.brevis KM3 and L.brevis KM7 showed one transition peak at 67.9°C and 59.14°C, respectively. To determine monodispersity of extracted S-layer proteins, dynamic light scattering (DLS) was used. The results indicated that the main population of S-layer molecules in two tested lactobacillus strains were composed of monomer with an expected diameter close to 10nm. Furthermore, Zeta potential measurements were showed positive potential for both S-layer proteins, as expected. Our results could be used as the basis for biotechnological applications of these two new S-layer proteins.

  19. The characteristic of unsaturated polyester resin wettability toward glass fiber orientation, density and surface treatment

    Directory of Open Access Journals (Sweden)

    Saputra Asep H.

    2017-01-01

    Full Text Available Wettability of composite is one of key to increase mechanical properties of composite that affected by structure of reinforcement and type of resin used. Therefore, this research focused on the effect of orientation, density and surface treatment on fiber to the characteristic of composite’s wettability, which is observed by contact angle and wetting time. The fiber used in this research is fiberglass, and the method for contact angle measurement is direct observation from the camera recorder and the data record will be processed and analyzed by using image processing method. The result for those variations can be obtained from the relation of variations toward contact angle and wetting time. According to result of research, fiber with orientation 45°/45° gives lower contact angle but longer wetting time than fiber with orientation 0°/90°. For orientation 45°/45°, the differences in wetting time is 15 second longer than orientation 0°/90°. In case of fiber density, the sheet with fiber density of 900 has 7 second faster for wetting time than sheet with fiber density of 1250. The surface treatment with NaOH 5% can accelerate the wetting time until 10 second.

  20. Uptake characteristics of liposomes by rat alveolar macrophages: influence of particle size and surface mannose modification.

    Science.gov (United States)

    Chono, Sumio; Tanino, Tomoharu; Seki, Toshinobu; Morimoto, Kazuhiro

    2007-01-01

    The influence of particle size and surface mannose modification on the uptake of liposomes by alveolar macrophages (AMs) was investigated in-vitro and in-vivo. Non-modified liposomes of five different particle sizes (100, 200, 400, 1000 and 2000 nm) and mannosylated liposomes with 4-aminophenyl-alpha-D-mannopyranoside (particle size 1000 nm) were prepared, and the uptake characteristics by rat AMs in-vitro and in-vivo were examined. The uptake of non-modified liposomes by rat AMs in-vitro increased with an increase in particle size over the range of 100-1000 nm, and became constant at over 1000 nm. The uptake of non-modified liposomes by AMs after pulmonary administration to rats in-vivo increased with an increase in particle size in the range 100-2000 nm. The uptake of mannosylated liposomes (particle size 1000 nm) by rat AMs both in-vitro and in-vivo was significantly greater than that of non-modified liposomes (particle size 1000 nm). The results indicate that the uptake of liposomes by rat AMs is dependent on particle size and is increased by surface mannose modification.

  1. Abundance and Distribution Characteristics of Microplastics in Surface Seawaters of the Incheon/Kyeonggi Coastal Region.

    Science.gov (United States)

    Chae, Doo-Hyeon; Kim, In-Sung; Kim, Seung-Kyu; Song, Young Kyoung; Shim, Won Joon

    2015-10-01

    Microplastics in marine environments are of emerging concern due to their widespread distribution, their ingestion by various marine organisms, and their roles as a source and transfer vector of toxic chemicals. However, our understanding of their abundance and distribution characteristics in surface seawater (SSW) remains limited. We investigated microplastics in the surface microlayer (SML) and the SSW at 12 stations near-shore and offshore of the Korean west coast, Incheon/Kyeonggi region. Variation between stations, sampling media, and sampling methods were compared based on abundances, size distribution, and composition profiles of microsized synthetic polymer particles. The abundance of microplastics was greater in the SML (152,688 ± 92,384 particles/m(3)) than in SSW and showed a significant difference based on the sampling method for SSWs collected using a hand net (1602 ± 1274 particles/m(3)) and a zooplankton trawl net (0.19 ± 0.14 particles/m(3)). Ship paint particles (mostly alkyd resin polymer) accounted for the majority of microplastics detected in both SML and SSWs, and increased levels were observed around the voyage routes of large vessels. This indicates that polymers with marine-based origins become an important contributor to microplastics in coastal SSWs of this coastal region.

  2. Study on the Generation Characteristics of Dielectric Barrier Discharge Plasmas on Water Surface

    Science.gov (United States)

    Liu, Wenzheng; Li, Chuanhui

    2014-01-01

    A new contact glow discharge electrode on the surface of water was designed and employed in this study. Because of the strong field strength in the small air gap formed by the electrode and the water surface, glow discharge plasmas were generated and used to treat waste water. The electric field distribution of the designed electrode model was simulated by MAXWELL 3D® simulation software, and the discharge parameters were measured. Through a series of experiments, we investigated the impact of optimal designs, such as the dielectric of the electrode, immersion depths, and curvature radii of the electrode on the generation characteristics of plasmas. In addition, we designed an equipotential multi-electrode configuration to treat a Methyl Violet solution and observe the discoloration effect. The experimental and simulation results indicate that the designed electrodes can realize glow discharge with a relative low voltage, and the generated plasmas covered a large area and were in stable state. The efficiency of water treatment is improved and optimized with the designed electrodes.

  3. Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172 surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe River.Section L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East China Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are high. At the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

  4. Characteristics of the near-surface atmosphere over the Ross Ice Shelf, Antarctica

    Science.gov (United States)

    Cassano, John J.; Nigro, Melissa A.; Lazzara, Matthew A.

    2016-04-01

    Two years of data from a 30 m instrumented tower are used to characterize the near-surface atmospheric state over the Ross Ice Shelf, Antarctica. Stable stratification dominates the surface layer at this site, occurring 83% of the time. The strongest inversions occur for wind speeds less than 4 m s-1 and the inversion strength decreases rapidly as wind speed increases above 4 m s-1. In summer unstable stratification occurs 50% of the time and unstable conditions are observed in every season. A novel aspect of this work is the use of an artificial neural network pattern identification technique, known as self-organizing maps, to objectively identify characteristic potential temperature profiles that span the range of profiles present in the 2 year study period. The self-organizing map clustering technique allows the more than 100,000 observed potential temperature profiles to be represented by just 30 patterns. The pattern-averaged winds show distinct and physically consistent relationships with the potential temperature profiles. The strongest winds occur for the nearly well mixed but slightly stable patterns and the weakest winds occur for the strongest inversion patterns. The weakest wind shear over the depth of the tower occurs for slightly unstable profiles and the largest wind shear occurs for moderately strong inversions. Pattern-averaged log wind profiles are consistent with theoretical expectations. The log wind profiles exhibit a kinked profile for the strongest inversion cases indicative of decoupling of the winds between the bottom and top of the tower.

  5. Distribution characteristics of magnetic susceptibility of the surface sediments in the southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    GEShulan; SHIXuefa; HANYibing

    2003-01-01

    The characteristic distributions of magnetic susceptibility (MS) are analyzed on the basis of susceptibility of 172 surface sediment samples in the southern Yellow Sea (SYS). The preliminary results are as follows: first, the distributions clearly correspond to different modern sediment assemblages in the continental sea, which indicates different sediment origins. With the 30 μCGS isoline being taken as demarcation line, the study area can then be divided into section H (high MS value area) and section L (low MS value area). Section H is mainly adjacent to land with two main sources of the Changjiang River and the Huanghe River.Section L is mainly an eddy sediment area, where Yellow Sea Cold Water is entrenched all the year round. The distribution pattern of MS could tell apart strong or weak hydrodynamic conditions and has a close relation to the circulation system in this area. At the areas of the SYS Circumfluent and northern East China Sea (NECS) Circumfluent (weak hydrodynamic), the MS has low values, while in the areas of Coastal Current (strong hydrodynamic), the values are high.At the same time, the oxidizing areas tend to take on higher MS, while the reducing areas have lower one. It seems safe to say that the MS in the continental sea reflects more of the sediment origin and sedimentary environment, which is different from that of loess, lake and surface soil as a climate proxy.

  6. Formation and characteristics of biomimetic mineralo-organic particles in natural surface water

    Science.gov (United States)

    Wu, Cheng-Yeu; Martel, Jan; Wong, Tsui-Yin; Young, David; Liu, Chien-Chun; Lin, Cheng-Wei; Young, John D.

    2016-06-01

    Recent studies have shown that nanoparticles exist in environmental water but the formation, characteristics and fate of such particles remain incompletely understood. We show here that surface water obtained from various sources (ocean, hot springs, and soil) produces mineralo-organic particles that gradually increase in size and number during incubation. Seawater produces mineralo-organic particles following several cycles of filtration and incubation, indicating that this water possesses high particle-seeding potential. Electron microscopy observations reveal round, bacteria-like mineral particles with diameters of 20 to 800 nm, which may coalesce and aggregate to form mineralized biofilm-like structures. Chemical analysis of the particles shows the presence of a wide range of chemical elements that form mixed mineral phases dominated by calcium and iron sulfates, silicon and aluminum oxides, sodium carbonate, and iron sulfide. Proteomic analysis indicates that the particles bind to proteins of bacterial, plant and animal origins. When observed under dark-field microscopy, mineral particles derived from soil-water show biomimetic morphologies, including large, round structures similar to cells undergoing division. These findings have important implications not only for the recognition of biosignatures and fossils of small microorganisms in the environment but also for the geochemical cycling of elements, ions and organic matter in surface water.

  7. Residues and Characteristics of Organochlorine Pesticides in the Surface Water in the Suburb of Beijing

    Science.gov (United States)

    CHEN, Jiawei; LIU, Chen; YANG, Zhongfang; WANG, Jiyuan

    Organochlorine Pesticides (OCPs), such as DDT and HCH, have stable chemical properties and less biodegradability. As a kind of persistent organic pollutants, they have high risk to the environment and human health. Although DDT and HCH have been prohibited in China since 1983, they are still found in some soil and water nowadays. Water resource is very important in natural environment and essential for agriculture. The existence of OCPs in some surface water in Beijing has been detected with different levels according to previous investigations. In recent years, many measures have been taken to control the pollution and to monitor the environment, and more attention has been paid to the status of surface water today. In this study, the water samples were collected from the Wenyu, Beiyun, Yanqing, Fangshan, Changping, and Shunyi Rivers in the suburb of Beijing, and the residues and characteristics of DDT and HCH were studied. The results showed that the contents of DDTs and HCHs were ND-13.98 ng/L and 3.87-146.42 ng/L, respectively. According to the indicators of the ratio values of (DDD+DDE)/DDT and α-HCH/γ-HCH, the source of pollution and its potential risk are also discussed in this article.

  8. Investigations on surface quality characteristics with multi-response parametric optimization and correlations

    Directory of Open Access Journals (Sweden)

    Amlana Panda

    2016-06-01

    Full Text Available This paper presents the parametric optimization on surface quality characteristics (Ra, Rz and Rt in hard turning of EN31 steel using multilayer coated carbide insert (TiN/TiCN/Al2O3 and also finds correlations. The experiments have been conducted based on Taguchi’s L9 orthogonal array. Multiple linear regression analysis has been utilized to find the correlations. The integrated multi-response optimization approach using CQL concept in WPCA coupled with Taguchi technique has been implemented. Based on the S/N ratio, the optimal process parameters for surface roughness i.e. Ra and Rz are the depth of cut at level 3 (0.5 mm, the cutting speed at level 3 (140 m/min, and the feed at level 1 (0.04 mm/rev. The optimal process parameters for Rt are found to be the depth of cut at level 3 (0.5 mm, the cutting speed at level 2 (100 m/min, and the feed at level 1 (0.04 mm/rev. Feed and depth of cut are found to be the significant cutting parameters affecting the responses at 95% confidence limit from ANOVA study. The first order model presented high correlation coefficient between the experimental and predicted values. The optimal parametric combination for multi-response (Ra, Rz and Rt becomes d3–v3–f1 and is greatly improved.

  9. Surface Characteristics and Electrochemical Impedance Investigation of Spark-Anodized Ti-6Al-4V Alloy

    Science.gov (United States)

    Garsivaz jazi, M. R.; Golozar, M. A.; Raeissi, K.; Fazel, M.

    2014-04-01

    In this study, the surface characteristic of oxide films on Ti-6Al-4V alloy formed by an anodic oxidation treatment in H2SO4/H3PO4 electrolyte at potentials higher than the breakdown voltage was evaluated. Morphology of the surface layers was studied by scanning electron microscope. The results indicated that the diameter of pores and porosity of oxide layer increase by increasing the anodizing voltage. The thickness measurement of the oxide layers showed a linear increase of thickness with increasing the anodizing voltage. The EDS analysis of oxide films formed in H2SO4/H3PO4 at potentials higher than breakdown voltage demonstrated precipitation of sulfur and phosphor elements from electrolyte into the oxide layer. X-ray diffraction was employed to exhibit the effect of anodizing voltage on the oxide layer structure. Roughness measurements of oxide layer showed that in spark anodizing, the Ra and Rz parameters would increase by increasing the anodizing voltage. The structure and Corrosion properties of oxide layers were studied using electrochemical impedance spectroscopy (EIS) techniques, in 0.9 wt.% NaCl solution. The obtained EIS spectra and their interpretation in terms of an equivalent circuit with the circuit elements indicated that the detailed impedance behavior is affected by three regions of the interface: the space charge region, the inner compact layer, and outer porous layer.

  10. Characteristics of surface wind structure of tropical cyclones over the north Indian Ocean

    Indian Academy of Sciences (India)

    M Mohapatra; Monica Sharma

    2015-10-01

    Tropical cyclone (TC) wind field monitoring and forecast are important for mariners, ships on sea and modelling group for creation of synthetic vortex, and storm surge and coastal inundation forecasting. Among others, a multi-platform satellite surface wind analysis developed by Co-operative Institute for Research in the Atmosphere (CIRA), USA for the TCs are referred by India Meteorological Department for surface wind field monitoring of TC. Hence, a study has been undertaken to analyze the characteristics of surface wind distribution and hence the structure of TC based on the real time data available from CIRA during 2007–2013. The study includes 19 TCs over the Bay of Bengal (BOB) and six over Arabian Sea (AS). The maximum radial extent of winds reaching threshold values of 34(17), 50(26) and 64(33) knot (ms−1) in each of the four geographical quadrants has been segregated with respect to season of formation, basin of formation and intensity of TC for analysis. The objective is to develop a reference surface wind structure of TC and examine its validity with respect to physical processes. The size of outer core (34(17) knot (ms−1) wind radial extension) as well as inner core (50(26) and 64(33) knot (ms−1) wind radial extension) increases significantly with increase in intensification of TC over BOB during both pre-monsoon and post-monsoon seasons and over AS during pre-monsoon season. The outer core of winds in TCs over the BOB is asymmetric in both pre-monsoon and post-monsoon seasons and for all categories of intensity of TCs. On the other hand, the asymmetry in inner core winds is significantly less. There is also no asymmetry in radial wind extension over the AS during both the seasons, except in case of outer core wind radial extension of VSCS during pre-monsoon season. The low level environment like enhanced cross equatorial flow, lower/middle level relative humidity, vertical wind shear and proximity of TC to the land surface are the determining

  11. Analysis of land surface parameters and turbulence characteristics over the Tibetan Plateau and surrounding region

    Science.gov (United States)

    Wang, Yinjun; Xu, Xiangde; Liu, Huizhi; Li, Yueqing; Li, Yaohui; Hu, Zeyong; Gao, Xiaoqing; Ma, Yaoming; Sun, Jihua; Lenschow, Donald H.; Zhong, Shiyuan; Zhou, Mingyu; Bian, Xindi; Zhao, Ping

    2016-08-01

    Based on the results from 11 flux sites during the third Tibetan Plateau (TP) Experiment (TIPEX III), land surface parameters and the turbulence characteristics of the atmospheric surface layer over the TP and surrounding region are analyzed. Monin-Obukhov similarity theory has been used to calculate the aerodynamic roughness length z0m and the excess resistance to heat transfer kB- 1 = ln(z0m/z0h), and the factors that cause variations of z0m and kB- 1 are investigated. The main drivers for the diurnal variations of surface albedo (α) at different sites are solar elevation, solar radiation, and soil moisture. The eddy correlation method is utilized to inversely calculate bulk transfer coefficients for momentum (CD) and heat (CH) at different sites. The relationships between CD and CH and the wind speed at 10 m follow a power law for unstable stratification. For stable stratification, both CD and CH increase with increasing wind speed when wind speed is less than 5 m/s. Diurnal variations of turbulent fluxes are compared at different sites, and the relationships between turbulent fluxes and other variables are analyzed. Wind speed variance normalized by the friction velocity (σu/u*, σv/u*, σw/u*) for neutral stratification (Cu1, Cv1, Cw1), and temperature and humidity variance normalized by a temperature and humidity scale (σT/T*, σq/q*) under free convection (z/L < -0.1) (CT, Cq) are fitted with similarity relations. The differences in similarity constants (Cu1, Cv1, Cw1, CT, Cq) at different sites are discussed. For stable stratification, cases are divided into weakly stable conditions and intermittent turbulence, and the critical values for these two states are determined. Shear and buoyancy terms in the turbulence kinetic energy equation for different stratifications are analyzed.

  12. Wing surface-jet interaction characteristics of an upper-surface blown model with rectangular exhaust nozzles and a radius flap

    Science.gov (United States)

    Bloom, A. M.; Hohlweg, W. C.; Sleeman, W. C., Jr.

    1976-01-01

    The wing surface jet interaction characteristics of an upper surface blown transport configuration were investigated in the Langley V/STOL tunnel. Velocity profiles at the inboard engine center line were measured for several chordwise locations, and chordwise pressure distributions on the flap were obtained. The model represented a four engine arrangement having relatively high aspect ratio rectangular spread, exhaust nozzles and a simple trailing edge radius flap.

  13. THE AERODYNAMIC CHARACTERISTICS OF A SOFT TYPE AIRSHIP NEAR TO A SCREEN IN VIEW OF A PROPELLER JETS INFLUENCE

    National Research Council Canada - National Science Library

    Le Quoc Dinh; Dang Ngock Than; N. V. Semenchikov; O. V. Yakovlevsky

    2014-01-01

    The results of numerical research of a soft type airship aerodynamic characteristics in subsonic flow of viscous gas are received for the airship locating near to a screen and having the working propellers...

  14. Effects of Er,Cr:YSGG laser irradiation on the surface characteristics of titanium discs: an in vitro study.

    Science.gov (United States)

    Ercan, Esra; Arin, Tuna; Kara, Levent; Çandirli, Celal; Uysal, Cihan

    2014-05-01

    Lasers are used to modify the surfaces of dental implants or to decontaminate exposed implant surfaces. However, research is lacking on whether the laser causes any change on the surfaces of titanium implants. We aimed to determine the effects of laser treatment on the surface characteristics of titanium discs. Nine discs were fabricated using grade-V titanium with resorbable blast texturing surface characteristics. The discs were irradiated with an erbium, chromium: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser under different experimental conditions (R1-9). Scanning electron microscopy was used to evaluate implant surface topography qualitatively, and a mechanical contact profilometer was used to evaluate surface roughness. The R3 and R5 parameters caused no measurable change. Minor cracks and grooves were observed in discs treated with the R1, R2, R4, R7 and R9 parameters. Major changes, such as melting, flattening and deep crack formation, were observed in discs subjected to R6 (2 W, 30 Hz, 2 mm. distance, 30 s) and R8 (3 W, 25 Hz, 2 mm. distance, 45 s) parameters. The lowest surface roughness value was obtained with the R8 parameter. Irradiation distance, duration, frequency and power were the most significant factors affecting surface roughness. Parameters such as wavelength, output power, energy, dose and duration should be considered during irradiation. The results of this study indicate that the distance between the laser tip and the irradiated surface should also be considered.

  15. Geochemically structural characteristics of municipal solid waste incineration fly ash particles and mineralogical surface conversions by chelate treatment.

    Science.gov (United States)

    Kitamura, Hiroki; Sawada, Takaya; Shimaoka, Takayuki; Takahashi, Fumitake

    2016-01-01

    Leaching behaviors of heavy metals contained in municipal solid waste incineration (MSWI) fly ash have been studied well. However, micro-characteristics of MSWI fly ash particles are still uncertain and might be non-negligible to describe their leaching behaviors. Therefore, this study investigated micro-characteristics of MSWI fly ash particles, especially their structural properties and impacts of chelate treatment on surface characteristics. According to SEM observations, raw fly ash particles could be categorized into four types based on their shapes. Because chelate treatment changed the surface of fly ash particles dramatically owing to secondary mineral formations like ettringite, two more types could be categorized for chelate-treated fly ash particles. Acid extraction experiments suggest that fly ash particles, tested in this study, consist of Si-base insoluble core structure, Al/Ca/Si-base semi-soluble matrices inside the body, and KCl/NaCl-base soluble aggregates on the surface. Scanning electron microscope (SEM) observations of the same fly ash particles during twice moistening treatments showed that KCl/NaCl moved under wet condition and concentrated at different places on the particle surface. However, element mobility depended on secondary mineral formations. When insoluble mineral like gypsum was generated and covered the particle surface, it inhibited element transfer under wet condition. Surface characteristics including secondary mineral formation of MSWI fly ash particles are likely non-negligible to describe trace element leaching behaviors.

  16. Comparative Evaluation of Frictional Properties, Load Deflection Rate and Surface Characteristics of Different Coloured TMA Archwires - An Invitro Study.

    Science.gov (United States)

    Aloysius, Arul Pradeep; Vijayalakshmi, Devaki; Deepika; Soundararajan, Nagachandran Kandasamy; Manohar, Vijaykumar Neelam; Khan, Nayeemullah

    2015-12-01

    During tooth movement the success of sliding mechanics is dependent upon various factors which include frictional resistance at bracket-archwire interface, surface roughness of archwire materials and elastic properties of archwires. Ion implantation techniques reduce the frictional force and allow better tooth movement clinically. The main objective of this study was to evaluate and compare the frictional properties, load deflection rate and surface characteristics of Honey dew and Purple coloured (Ion implanted) TMA wires with uncoated TMA wires. Fifteen archwire samples were divided into three groups comprising of five samples in each group namely, Group I - Uncoated TMA wires (Control), Group II - Purple coloured TMA wires and Group III- Honey dew TMA wires. Friction and load deflection rate testing were performed with the Instron Universal testing machine and the surface characteristics of the wires were evaluated before and after sliding using Scanning Electron Microscope. The mean frictional characteristics and surface roughness for Honey dew TMA wires was lesser than Purple coloured TMA wires which was statistically significant. Both the coloured TMA wires showed low frictional characteristics and less surface roughness than uncoated TMA wires (the control). The mean load deflection rate was low for both coloured ion implanted TMA wires when compared to uncoated TMA wires which was statistically significant. Coloured ion implanted TMA wires, especially Honey dew TMA wires have low friction, low load deflection rate and improved surface finish. Hence they can be used in frictionless as well as sliding mechanics, where uncoated TMA wires are inefficient.

  17. Spatial and temporal distribution characteristics of near-surface CO2 concentration over China based on GOSAT data

    Science.gov (United States)

    Zhao, Jing; Cui, Weihong; Sun, Yunhua

    2014-11-01

    To study the spatial and temporal distribution characteristics of near-surface CO2 concentration over China, the data of GOSAT L4B and auxiliary data of Mt Waliguan background observations, population density, total energy consumption (coal) and GDP in 2009 were applied to this study. The ArcGIS Geostatistical Analytical Method was used. The ground-based validation was processed by comparing GOSAT data with Mt Waliguan background observations. The variation characteristics of the near-surface CO2 concentration over China was analysed spatially and temporally. The results show that: GOSAT retrieved near-surface products are consistent with Mt Waliguan ground-based measurement; Near-surface CO2 concentration over China is relatively concentrated, and has significant differences between the East and the West, with a overall characteristic that CO2 concentration in the east of China is high and in the west is low; Near-surface CO2 concentration over China has a significant seasonal variation characteristic, and the monthly average concentration rise to the highest value of 396.512 ppmv in April (spring), which is significantly higher than other seasons, decline to the lowest value of 382.781 ppmv in July (summer); All relationships illustrate a big uncertainty, resulting a conclusion that the reasons causing the spatial distribution of near-surface CO2 concentration may be varied, could not be easily determined as anthropogenic or natural ressons, which need further study.

  18. Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics

    Directory of Open Access Journals (Sweden)

    C. Larsson Wexell

    2013-01-01

    Full Text Available In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography.

  19. Concentrations and characteristics of organic carbon in surface water in Arizona: Influence of urbanization

    Science.gov (United States)

    Westerhoff, P.; Anning, D.

    2000-01-01

    Dissolved (DOC) and total (TOC) organic carbon concentrations and compositions were studied for several river systems in Arizona, USA. DOC composition was characterized by ultraviolet and visible absorption and fluorescence emission (excitation wavelength of 370 nm) spectra characteristics. Ephemeral sites had the highest DOC concentrations, and unregulated perennial sites had lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater-treatment plants (p wastewater-treatment plant effluent were higher in DOC concentration (p wastewater-treatment plants) was found to affect temporal variability in DOC concentration and composition. (C) 2000 Elsevier Science B.V.Dissolved (DOC) and total (TOC) organic carbon concentrations and compositions were studied for several river systems in Arizona, USA. DOC composition was characterized by ultraviolet and visible absorption and fluorescence emission (excitation wavelength of 370 nm) spectra characteristics. Ephemeral sites had the highest DOC concentrations, and unregulated perennial sites had lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater-treatment plants (pwastewater-treatment plant effluent were higher in DOC concentration (pwastewater-treatment plants) was found to affect temporal variability in DOC concentration and composition.The influence of urbanization, becoming increasingly common in arid regions, on dissolved organic carbon (DOC) concentrations in surface water resources was studied. DOC concentration and composition, seasonal watershed runoff events, streamflow variations, water management practices, and urban infrastructure in several Arizona watersheds were monitored. Ephemeral sites had the highest DOC levels, and unregulated perennial sites and lower concentrations than unregulated intermittent sites, regulated sites, and sites downstream from wastewater treatment plants. Reservoir outflows

  20. Amplitude-Phase Characteristics of the Annual Cycle of Surface Air Temperature in the Northern Hemisphere

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The amplitude-phase characteristics (APC) of surface air temperature (SAT) annual cycle (AC)in the Northern Hemisphere are analyzed. From meteorological observations for the 20th century andmeteorological reanalyses for its second half, it is found that over land negative correlation of SAT ACamplitude with annual mean SAT dominates. Nevertheless, some exceptions exist. The positive correlationbetween these two variables is found over the two desert regions: in northern Africa and in Central America.Areas of positive correlations are also found for the northern Pacific and for the tropical Indian and PacificOceans. Southward of the characteristic annual mean snow-ice boundary (SIB) position, the shape ofthe SAT AC becomes more sinusoidal under climate warming. In contrast, northward of it, this shapebecomes less sinusoidal. The latter is also found for the above-mentioned two desert regions. In theFar East (southward of about 50°N), the SAT AC shifts as a whole: here its spring and autumn phasesoccur earlier if the annual mean SAT increases. From energy-balance climate considerations, those trendsfor SAT AC APC in the middle and high latitudes are associated with the influence of the albedo-SATfeedback due to the SIB movement. In the Far East the trends are attributed to the interannual cloudinessvariability, and in the desert regions, to the influence of a further desertification and/or scattering aerosolloading into the atmosphere. In the north Pacific, the exhibited trends could only be explained as aresult of the influence of the greenhouse-gases loading on atmospheric opacity. The trends for SAT ACAPC related to the SIB movement are simulated reasonably well by the climate model of intermediatecomplexity (IAP RAS CM) in the experiment with greenhouse gases atmospheric loading. In contrast,the tendencies resulting from the cloudiness variability are not reproduced by this model. The model alsopartly simulates the tendencies related to the desertification

  1. Chemically-doped graphene with improved surface plasmon characteristics: an optical near-field study.

    Science.gov (United States)

    Zheng, Zebo; Wang, Weiliang; Ma, Teng; Deng, Zexiang; Ke, Yanlin; Zhan, Runze; Zou, Qionghui; Ren, Wencai; Chen, Jun; She, Juncong; Zhang, Yu; Liu, Fei; Chen, Huanjun; Deng, Shaozhi; Xu, Ningsheng

    2016-10-01

    One of the most fascinating and important merits of graphene plasmonics is their tunability over a wide range. While chemical doping has proven to be a facile and effective way to create graphene plasmons, most of the previous studies focused on the macroscopic behaviors of the plasmons in chemically-doped graphene and little was known about their nanoscale responses and related mechanisms. Here, to the best of our knowledge, we present the first experimental near-field optical study on chemically-doped graphene with improved surface plasmon characteristics. By using a scattering-type scanning near-field optical microscope (s-SNOM), we managed to show that the graphene plasmons can be tuned and improved using a facile chemical doping method. Specifically, the plasmon interference patterns near the edge of the monolayer graphene were substantially enhanced via nitric acid (HNO3) exposure. The plasmon-related characteristics can be deduced by analyzing such plasmonic fringes, which exhibited a longer plasmon wavelength and reduced plasmon damping rate. In addition, the local carrier density and therefore the Fermi energy level (EF) of graphene can be obtained from the plasmonic nano-imaging, which indicated that the enhanced plasmon oscillation originated from the injection of free holes into graphene by HNO3. These findings were further corroborated by theoretical calculations using density functional theory (DFT). We believe that our findings provide a clear nanoscale picture on improving graphene plasmonics by chemical doping, which will be helpful for optimizing graphene plasmonics and for elucidating the mechanisms of two-dimensional light confinement by atomically thick materials.

  2. Data Reduction Functions for the Langley 14- by 22-Foot Subsonic Tunnel

    Science.gov (United States)

    Boney, Andy D.

    2014-01-01

    The Langley 14- by 22-Foot Subsonic Tunnel's data reduction software utilizes six major functions to compute the acquired data. These functions calculate engineering units, tunnel parameters, flowmeters, jet exhaust measurements, balance loads/model attitudes, and model /wall pressures. The input (required) variables, the output (computed) variables, and the equations and/or subfunction(s) associated with each major function are discussed.

  3. Subsonic Euler Flows with Large Vorticity Through an Infinitely Long Axisymmetric Nozzle

    Science.gov (United States)

    Du, Lili; Duan, Ben

    2016-09-01

    This paper is a sequel to the earlier work Du and Duan (J Diff Equ 250:813-847, 2011) on well-posedness of steady subsonic Euler flows through infinitely long three-dimensional axisymmetric nozzles. In Du and Duan (J Diff Equ 250:813-847, 2011), the authors showed the existence and uniqueness of the global subsonic Euler flows through an infinitely long axisymmetric nozzle, when the variation of Bernoulli's function in the upstream is sufficiently small and the mass flux of the incoming flow is less than some critical value. The smallness of the variation of Bernoulli's function in the upstream prevents the attendance of the possible singularity in the nozzles, however, at the same time it also leads that the vorticity of the ideal flow is sufficiently small in the whole nozzle and the flows are indeed adjacent to axisymmetric potential flows. The purpose of this paper is to investigate the effects of the vorticity for the smooth subsonic ideal flows in infinitely long axisymmetric nozzles. We modify the formulation of the problem in the previous work Du and Duan (J Diff Equ 250:813-847, 2011) and the existence and uniqueness results on the smooth subsonic ideal polytropic flows in infinitely long axisymmetric nozzles without the restriction on the smallness of the vorticity are shown in this paper.

  4. Two Dimensional Subsonic Euler Flows Past a Wall or a Symmetric Body

    Science.gov (United States)

    Chen, Chao; Du, Lili; Xie, Chunjing; Xin, Zhouping

    2016-08-01

    The existence and uniqueness of two dimensional steady compressible Euler flows past a wall or a symmetric body are established. More precisely, given positive convex horizontal velocity in the upstream, there exists a critical value {ρ_cr} such that if the incoming density in the upstream is larger than {ρ_cr}, then there exists a subsonic flow past a wall. Furthermore, {ρ_cr} is critical in the sense that there is no such subsonic flow if the density of the incoming flow is less than {ρ_cr}. The subsonic flows possess large vorticity and positive horizontal velocity above the wall except at the corner points on the boundary. Moreover, the existence and uniqueness of a two dimensional subsonic Euler flow past a symmetric body are also obtained when the incoming velocity field is a general small perturbation of a constant velocity field and the density of the incoming flow is larger than a critical value. The asymptotic behavior of the flows is obtained with the aid of some integral estimates for the difference between the velocity field and its far field states.

  5. FINITE DIFFERENCE METHOD FOR CALCULATING OF THE GAS FLOW IN A SUBSONIC GAS EJECTOR

    Directory of Open Access Journals (Sweden)

    Kostjantin Kapitanchuk

    2015-12-01

    Full Text Available Describe analysis of eddy viscosity actual mathematical models for numerical simulation a reversal gas flow in subsonic gas ejector. Considered advantages and disadvantages each of it. Proposed use method of finite elements for provides viscous gas flow calculation of gas ejectors.

  6. Surface Partial Discharge Characteristics of Oil-paper Insulation Under Combined AC-DC Voltage

    Institute of Scientific and Technical Information of China (English)

    SHA Yanchao; ZHOU Yuanxiang; NIE Dexin; WU Zhirong; DENG Jiangang; LU Licheng

    2013-01-01

    The valve side windings of converter transformers bear AC,DC,impulse,and reversal-polarity voltages during operation,which could result in serious insulation problems of the equipment.By performing experiments with surface discharge model of oil-paper insulation at 80 ℃ under combined AC-DC voltage for 200 h,we studied the spectrums and statistical parameters of partial discharges at different discharge stages.Furthermore,some fingerprint parameters were calculated in order to estimate the development situation of partial discharge,while the characteristic gases dissolved in the transformer oil were measured by gas chromatography.The surface discharges in the experiments were observed using a high speed camera,and a full discharge process could be marked off into four stages as follows.①The elementary stage.When a partial discharge occurs near electrodes,electrical charges are injected into the region near electrodes and causing bubble generation.②Due to their high resistivity and low dielectric constant,the bubbles would bare the major part of the voltage applied to samples.Therefore,discharge happens inside the small bubbles,and it emits a lot of light.③Micmmolecules of gas are produced in discharge,and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules.④The carrier charge moves forward to electrodes driven by the applied electric field,till they neutralize with the charge from electrodes,and hence discharge channels are formed subsequently.

  7. The impact of marine aerosols on atmospheric characteristics over ocean surface in frontal zones

    Science.gov (United States)

    Pavlova, Hanna; Palamarchuk, Iuliia; Ruban, Igor; Ivanov, Sergiy

    2015-04-01

    Ocean-derived aerosols are particles produced from the ocean surface and remaining suspended in the atmosphere during a certain period of time. Aerosols act as climate forcers both directly (by scattering and absorbing solar radiation) and indirectly (by affecting cloud microphysics as cloud condensation nuclei). To evaluate the degree of marine aerosols impact on weather conditions the numerical experiments with the HARMONIE model were conducted with the model domain covering area over the North Atlantic. The results showed that marine aerosols have a significant impact on characteristics of the atmosphere (such as air temperature, specific humidity, precipitation, and vertical velocity) over the ocean surface. The most significant differences occur along the frontal zones with high gradients at all vertical levels in the atmosphere for all variables. Change in radiative fluxes leads to changes in temperature of the atmosphere. These anomalies appear as mesoscale cells of opposite signs alternating each other. It can be assumed that they are formed as a result of a chain of factors. Thus, the absorption and scattering of solar radiation in the upper troposphere during daytime, increasing of moisture content and subsequent increase in thermal inertia of the air, and enhanced greenhouse effect at nighttime are acting in different directions on formation of vertical structure and convection conditions. This leads to a strengthening/weakening of the updrafts and compensatory movements, and eventually to the changes in processes of precipitation formation. Thus, the simulation of weather conditions in frontal zones over the ocean requires considering the effect of the marine aerosols presence.

  8. Influence of urban surface properties and rainfall characteristics on surface water flood outputs - insights from a physical modelling environment

    Science.gov (United States)

    Green, Daniel; Pattison, Ian; Yu, Dapeng

    2017-04-01

    Surface water (pluvial) flooding occurs when excess rainfall from intense precipitation events is unable to infiltrate into the subsurface or drain via natural or artificial drainage channels. Surface water flood events pose a major hazard to urban regions across the world, with nearly two thirds of flood damages in the UK being caused by surface water flood events. The perceived risk of surface water flooding appears to have increased in recent years due to several factors, including (i) precipitation increases associated with climatic change and variability; (ii) population growth meaning more people are occupying flood risk areas, and; (iii) land-use changes. Because urban areas are often associated with a high proportion of impermeable land-uses (e.g. tarmacked or paved surfaces and buildings) and a reduced coverage of vegetated, permeable surfaces, urban surface water flood risk during high intensity precipitation events is often exacerbated. To investigate the influence of urbanisation and terrestrial factors on surface water flood outputs, rainfall intensity, catchment slope, permeability, building density/layout scenarios were designed within a novel, 9m2 physical modelling environment. The two-tiered physical model used consists of (i) a low-cost, nozzle-type rainfall simulator component which is able to simulate consistent, uniformly distributed rainfall events of varying duration and intensity, and; (ii) a reconfigurable, modular plot surface. All experiments within the physical modelling environment were subjected to a spatiotemporally uniform 45-minute simulated rainfall event, while terrestrial factors on the physical model plot surface were altered systematically to investigate their hydrological response on modelled outflow and depth profiles. Results from the closed, controlled physical modelling experiments suggest that meteorological factors, such as the duration and intensity of simulated rainfall, and terrestrial factors, such as model slope

  9. On the structure of characteristic surfaces related with partial differential equations of first and higher orders. Part 1

    Directory of Open Access Journals (Sweden)

    Natalia K. Prykarpatska

    2005-01-01

    Full Text Available The geometric structure of characteristic surfaces related with partial differential equations of first and higher orders is studied making use the vector field technique on hypersurfaces. It is shown, that corresponding characteristics are defined uniquely up to some smooth tensor fields, thereby supplying additional information about the suitable set of their solutions. In particular, it may be very useful for studying asymptotic properties of solutions to our partial differential equations under some boundary conditions.

  10. The variation characteristics and effect factors of surface ozone concentration in the Taklimakan Desert hinterland

    Institute of Scientific and Technical Information of China (English)

    XinChun Liu; YuTing Zhong; Qing He; YanMei Peng; XingHua Yang; Ali Mamtimin; Wen Huo

    2014-01-01

    Based on automatic continuous surface ozone concentration observation data from June 10, 2010 to March 20, 2012 in the Taklimakan Desert hinterland, combined with corresponding meteorological data, the temporal, seasonal and daily variation characteristics of surface ozone concentrations under different weather conditions were analyzed. At the same time, the main fac-tors affecting ozone variation are discussed. Results show that:(1) Daily variation of ozone concentration was characterized by one obvious peak, with gentle changes during the night and dramatic changes during the day. The lowest concentration was at 09:00 and the highest was at 18:00. Compared to urban areas, there was a slight time delay. (2) Ozone concentration variation had a weekend effect phenomenon. Weekly variation of ozone concentration decreased from Monday to Wednesday with the lowest in Wednesday, and increased after Thursday with the highest in Sunday. (3) The highest monthly average concentration was 89.6μg/m3 in June 2010, and the lowest was 32.0μg/m3 in January 2012. Ozone concentration reduced month by month from June to December in 2010. (4) Ozone concentration in spring and summer was higher than in autumn and winter. The variation trend agreed with those in other large and medium-sized cities. (5) Under four different types of weather, daily ozone concentration var-ied most dramatically in sunny days, followed by slight variation in rain days, and varied gently in cloudy days. Ozone concentra-tion varied inconspicuously before a sandstorm appearance, and dropped rapidly at the onset of a sandstorm. (6) Daily variation of radiation was also characterized by a single peak, and the variation was significantly earlier than ozone concentration variation. Sun radiation intensity had a direct influence on the photochemical reaction speed, leading to variation of ozone concentration. (7) Daily average ozone concentration in dust weather was higher than in slight rain and clear days. The

  11. Experimental Investigation of Subsonic Turbulent Boundary Layer Flow Over a Wall-Mounted Axisymmetric Hill

    Science.gov (United States)

    Bell, James H.; Heineck, James T.; Zilliac, Gregory; Mehta, Rabindra D.; Long, Kurtis R.

    2016-01-01

    An important goal for modern fluid mechanics experiments is to provide datasets which present a challenge for Computational Fluid Dynamics simulations to reproduce. Such "CFD validation experiments" should be well-characterized and well-documented, and should investigate flows which are difficult for CFD to calculate. It is also often convenient for the experiment to be challenging for CFD in some aspects while simple in others. This report is part of the continuing documentation of a series of experiments conducted to characterize the flow around an axisymmetric, modified-cosine-shaped, wall-mounted hill named "FAITH" (Fundamental Aero Investigates The Hill). Computation of this flow is easy in some ways - subsonic flow over a simple shape - while being complex in others - separated flow and boundary layer interactions. The primary set of experiments were performed on a 15.2 cm high, 45.7 cm base diameter machined aluminum model that was tested at mean speeds of 50 m/s (Reynolds Number based on height = 500,000). The ratio of model height to boundary later height was approximately 3. The flow was characterized using surface oil flow visualization, Cobra probe to determine point-wise steady and unsteady 3D velocities, Particle Image Velocimetry (PIV) to determine 3D velocities and turbulence statistics along specified planes, Pressure Sensitive Paint (PSP) to determine mean surface pressures, and Fringe Imaging Skin Friction (FISF) to determine surface skin friction magnitude and direction. A set of pathfinder experiments were also performed in a water channel on a smaller scale (5.1 cm high, 15.2 cm base diameter) sintered nylon model. The water channel test was conducted at a mean test section speed of 3 cm/s (Reynolds Number of 1500), but at the same ratio of model height to boundary layer thickness. Dye injection from both the model and an upstream rake was used to visualize the flow. This report summarizes the experimental set-up, techniques used, and data

  12. [Influence of microcystin-LR on cell viability and surface characteristics of Pseudomonas putida].

    Science.gov (United States)

    Deng, Ting-jin; Ye, Jin-shao; Peng, Hui; Liu, Zhi-chen; Liu, Ze-hua; Yin, Hua; Chen, Shuo-na

    2015-01-01

    In microcystin-LR (MC-LR) degradation system, the change in surface characteristics and cell viability of Pseudomonas putida was studied. The purpose of this study was to reveal the influence of MC-LR on P. putida and elucidate the toxicity of MC-LR on microorganisms. The result demonstrated that MC-LR enhanced the cytoplasmic membrane permeability, as well as affected the ion metabolism and protein release of P. putida. The soluble sugar and Na+, Cl-release increased with the rising concentration of MC-LR ranging from 0 mg x L(-1) to 2.0 mg x L(-1). Flow Cytometry Method(FCM) analysis revealed that MC-LR accelerated the death of P. putida, and the death rate increased with the ascending concentration of MC-LR. Compared with the control, the death rate on day 5 increased by nearly 30% when 2.5 mg x L(-1) MC-LR was added. Scanning electron microscopy (SEM) analysis showed that the cells were deformed under the toxicity of MC-LR. After 5-day exposure to 2.5 mg x L(-1) MC-LR, the majority of the cells were ruptured and the intracellular materials flew out. The cellular structure was severely damaged under this condition.

  13. Standardization of peeling tests for assessing the cohesion and consolidation characteristics of historic stone surfaces.

    Science.gov (United States)

    Drdácký, Miloš; Lesák, Jaroslav; Rescic, Silvia; Slížková, Zuzana; Tiano, Piero; Valach, Jaroslav

    A peeling test known as the "Scotch Tape test" has been used for more than 40 years in conservation practice for assessing the consolidation efficiency of degraded stone. However, the method has not been supported by any standard or reliably verified recommendations for its application. Its applicability is overestimated, and its unrestricted use without adequate knowledge and sufficient understanding can lead to non-comparable, non-reproducible and, in many cases, incorrect and severely biased results and assessments. This paper presents the results of a recent study focused on establishing limits for application, reliable procedures and a "standard" protocol for testing the cohesion characteristics of brittle and quasi-brittle materials, mainly mortars and stones. The main application strategy exploits repeated peeling in the same place on a surface in order to eliminate the effect of the natural decrease in the detached material from the subsurface layers, which might be incorrectly interpreted as a consolidation effect. There is a discussion of factors influencing the performance of the peeling test method, and examples of peeling measurements on various natural and artificial stones are presented.

  14. Prediction for human intelligence using morphometric characteristics of cortical surface: partial least square analysis.

    Science.gov (United States)

    Yang, J-J; Yoon, U; Yun, H J; Im, K; Choi, Y Y; Lee, K H; Park, H; Hough, M G; Lee, J-M

    2013-08-29

    A number of imaging studies have reported neuroanatomical correlates of human intelligence with various morphological characteristics of the cerebral cortex. However, it is not yet clear whether these morphological properties of the cerebral cortex account for human intelligence. We assumed that the complex structure of the cerebral cortex could be explained effectively considering cortical thickness, surface area, sulcal depth and absolute mean curvature together. In 78 young healthy adults (age range: 17-27, male/female: 39/39), we used the full-scale intelligence quotient (FSIQ) and the cortical measurements calculated in native space from each subject to determine how much combining various cortical measures explained human intelligence. Since each cortical measure is thought to be not independent but highly inter-related, we applied partial least square (PLS) regression, which is one of the most promising multivariate analysis approaches, to overcome multicollinearity among cortical measures. Our results showed that 30% of FSIQ was explained by the first latent variable extracted from PLS regression analysis. Although it is difficult to relate the first derived latent variable with specific anatomy, we found that cortical thickness measures had a substantial impact on the PLS model supporting the most significant factor accounting for FSIQ. Our results presented here strongly suggest that the new predictor combining different morphometric properties of complex cortical structure is well suited for predicting human intelligence. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. [Seasonal Provincial Characteristics of Vertical Distribution of Dust Loadings and Heavy Metals near Surface in City].

    Science.gov (United States)

    Li, Xiao-yan; Zhang, Shu-ting

    2015-06-01

    With the emergence of urban high-rise building, the vertical space of human daily life gradually extended upward. Seasonal characteristics of vertical distribution of dust loadings and heavy metals near surface are remarkable. In this study, we collected dust deposited on the windowsill at different space height (1th-8th floor) from three buildings in Guiyang city during spring, summer, autumn and winter, and analyzed the deposition fluxes of dust and elements including Ca, Fe, Cd, Cr, Cu, Ni, Pb and Zn. The results showed that: the total changing trend of vertical distribution of dust loadings was that the deposition fluxes of dust in winter were the highest, followed by those in spring, and the deposition fluxes of dust in summer were the lowest. The degree of variation on dust loadings dependent on the change of elevation was the highest in winter, followed by that in summer, and was relatively lower in spring and autumn. The effect on dust loadings by seasonal changing was relatively heavier on windowsill on the lower level than on the higher level. The levels of elements were the highest in spring dust, while those in autumn were relatively lower. Among the 8 elements, the variability of Zn in dust related to space time variation was the most obvious, and that of Ca was weaker. The atmospheric inversion condition might be one of the reasons that improved the deposition fluxes of dust and the contents of Ph and Zn in dust during winter and spring.

  16. Influence of polymer additive molecular weight on surface and microstructural characteristics of electrodeposited copper

    Indian Academy of Sciences (India)

    R Manu; Sobha Jayakrishnan

    2011-04-01

    Electrodeposition of copper was done with different molecular weight (MW) polyethylene glycol (PEG) as an additive in the plating bath. The adsorbed layer formed of PEG and chloride ion (Cl−) in the presence of copper ions has a definite role in controlling the deposition mechanism and the coating characteristics. The adsorption behaviour and suppressor nature of PEG with different MW (200–20000) on the physicochemical and the surface morphological features of the copper deposit were characterized. The results reveal that depending on the adsorption capacity of the intermediate complex, the deposit properties show gradation. There is a range of morphology with particular grain structure for different MW PEG addition. Grain size and the roughness decreased with increase in PEG MW. The concentration of Cl− ion in the plating bath is also significant in determining the deposit mechanism of the bath as revealed from the shift in cathodic potential. The adsorbing power of the complex depends not only on PEG MW but also on Cl− ion concentration. XRD analysis of the copper deposit obtained with low MW PEG showed (220) as the major plane and with high MW PEG the prominent orientation was (111) and (200).

  17. Lubrication and thermal characteristics of mechanical seal with porous surface based on cavitation

    Science.gov (United States)

    Huilong, Chen; Muzi, Zuo; Tong, Liu; Yu, Wang; Cheng, Xu; Qiangbo, Wu

    2014-04-01

    The theory model of mechanical seals with laser-textured porous surface (LST-MS) was established. The liquid film of LST-MS was simulated by the Fluent software, using full cavitation model and non-cavitation model separately. Dynamic mesh technique and relationship between viscosity and temperature were applied to simulate the internal flow field and heat characteristics of LST-MS, based on the more accurate cavitation model. Influence of porous depth ratio porous diameter ɛ and porous density SP on lubrication performance and the variation of lubrication and thermal properties with shaft speed and sealing pressure were analyzed. The results indicate that the strongest hydrodynamic pressure effect and the biggest thickness of liquid film are obtained when ɛ and SP are respectively about 0.025 and 0.5 which were thought to be the optimum value. The frictional heat leads to the increase of liquid film temperature and the decrease of medium viscosity with the shaft speed increasing. The hydrodynamic pressure effect increases as shaft speed increasing, however it decreases as the impact of frictional heat.

  18. Study on Transmission Torque Characteristics of a Surface-Permanent-Magnet-Type Magnetic Gear

    Science.gov (United States)

    Niguchi, Noboru; Hirata, Katsuhiro; Hayakawa, Yuichi

    Magnetic gears have some advantages such as low mechanical loss and maintenance-free operation that are not observed in conventional mechanical gears. In addition, magnetic gears have inherent overload protection. Therefore, magnetic gears are expected to be used in special applications; for example, they can be used in a joint of a humanoid robot. Recently, various types of new magnetic gears have been proposed. Among these new gears, a surface-permanent-magnet-type (SPM-type) magnetic gear employing harmonic magnetic flux has gained attention because of its high transmission torque density, though it has a complex structure with multipole magnets. Some studies on an SPM-type magnetic gear have been carried out, but there are few papers on cogging torque. This paper describes the transmission torque characteristics of an SPM-type magnetic gear. The operating principle and the transmission torque under synchronous operation are formulated in accordance with the gear ratio. High orders of the cogging torque are computed by employing the 3-D finite element method, and the validity of the analysis is verified by carrying out measurements on a prototype. Furthermore, a method for reducing the cogging torque is discussed.

  19. Analysis of characteristics in the sea surface temperature variability in the East/Japan Sea

    Science.gov (United States)

    Yeh, Sang-Wook; Park, Young-Gyu; Min, HongSik; Kim, Cheol-Ho; Lee, Jae-Hak

    2010-06-01

    We examine the characteristics of sea surface temperature (SST) variability in the East/Japan Sea (EJS) for the period of 1891-2005 using 1°×1° latitude and longitude resolution datasets from the Japan Meteorological Agency and the Hadley Centre. A significant warming trend that manifests itself more strongly over the southern part of the sea is observed. In addition, it is found in the EJS that warming during the boreal winter is more significant than that during the summer. The EJS SST index, obtained from the time series of monthly SST anomaly averaged over the western half of the EJS, where large SST anomaly standard deviation is observed, has a primary spectral density at a frequency longer than a decade and a secondary peak at the annual frequency band. The variability of the low-frequency EJS SST, which is mostly explained by that during winter, is characterized by significant warming from the early 1940s to the late 1940s and from the mid-1980s to the present. Between the two warming periods, the EJS SST variability is dominated by decadal fluctuations. Finally, we discuss possible mechanisms of the low frequency EJS SST variability in conjunction with atmospheric variability. When the northwesterly winter monsoon becomes weaker (stronger), less (greater) amount of cold air is advected to the EJS. Sensible heat loss from the sea to the air becomes smaller (greater) producing a warm (cold) SST anomaly.

  20. Trace metals in surface sediments of the Taiwan Strait: geochemical characteristics and environmental indication.

    Science.gov (United States)

    Gao, Xuelu; Zhou, Fengxia; Lui, Hon-Kit; Lou, Jiann-Yuh; Chen, Chen-Tung Arthur; Zhuang, Wen

    2016-06-01

    The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd > Pb > Ni > Zn > Cu > Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd > Pb > Ni > Cu > Zn > Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.

  1. Growth characteristics of Brevibacterium, Corynebacterium, Microbacterium, and Staphylococcus spp. isolated from surface-ripened cheese.

    Science.gov (United States)

    Mounier, Jérôme; Rea, Mary C; O'Connor, Paula M; Fitzgerald, Gerald F; Cogan, Timothy M

    2007-12-01

    The growth characteristics of five bacteria, Brevibacterium aurantiacum 1-16-58, Corynebacterium casei DPC 5298(T), Corynebacterium variabile DPC 5310, Microbacterium gubbeenense DPC 5286(T), and Staphylococcus saprophyticus 4E61, all of which were isolated from the surface of smear cheese, were studied in complex and chemically defined media. All of the coryneforms, except M. gubbeenense, grew in 12% salt, while B. aurantiacum and S. saprophyticus grew in 15% salt. All five bacteria assimilated lactate in a semisynthetic medium, and none of the coryneform bacteria assimilated lactose. Glucose assimilation was poor, except by S. saprophyticus and C. casei. Five to seven amino acids were assimilated by the coryneforms and 12 by S. saprophyticus. Glutamate, phenylalanine, and proline were utilized by all five bacteria, whereas utilization of serine, threonine, aspartate, histidine, alanine, arginine, leucine, isoleucine, and glycine depended on the organism. Growth of C. casei restarted after addition of glutamate, proline, serine, and lactate at the end of the exponential phase, indicating that these amino acids and lactate can be used as energy sources. Pantothenic acid was essential for the growth of C. casei and M. gubbeenense. Omission of biotin reduced the growth of B. aurantiacum, C. casei, and M. gubbeenense. All of the bacteria contained lactate dehydrogenase activity (with both pyruvate and lactate as substrates) and glutamate pyruvate transaminase activity but not urease activity.

  2. Tuning beam power-splitting characteristics through modulating a photonic crystal slab’s output surface

    Science.gov (United States)

    Feng, Shuai; Xiao, Ting-Hui; Gan, Lin; Wang, Yi-Quan

    2017-01-01

    Light-beam-splitting characteristics are theoretically and experimentally studied in 2D square-lattice photonic crystals (PhCs) with delicately designed and modulated output surfaces. Compared with the traditional branch-waveguide and self-collimation-type PhC splitters, our proposed structure can not only split the input light beam into different numbers of branches but also realize the adjustment of their relative light intensities in each branch. Moreover, the influence of a light beam’s incident angle on both the output branch beams’ relative intensity and propagation direction is investigated. This proposed light beam splitter is able to work within a broad frequency range, and the propagation directions of the output split beams can be modified with the incident beam’s frequency. In addition, when the PhC device becomes thicker, a kind of light-beam-focusing phenomenon is observed. Advantageously, our light-beam-splitting device has no restriction as to the incident light beam’s location and width, so it is much more convenient and practical for achieving optical connection with other functional devices in complicated, large-scale, all-optical integrated circuits.

  3. Nonstructural protein 1 characteristic peak from NS1-saliva mixture with Surface-Enhanced Raman spectroscopy.

    Science.gov (United States)

    Radzol, A R M; Lee, Khuan Y; Mansor, W

    2013-01-01

    Surface Enhanced Raman spectroscopy (SERS) is an enhanced technique of Raman spectroscopy, which amplifies the intensity of Raman scattering to a practical range with adsorption of analyte onto nano-size plasmonic material such as gold, silver or copper. This feature of SERS has given it a niche in tracing molecular structure, especially useful for marking diseases specific biomarker. NS1 protein has been clinically accepted as an alternative biomarker for diseases caused by flavivirus. Detection of Nonstructural Protein 1 (NS1) will allow early diagnosis of the diseases. Its presence in the blood serum has been reported as early as first day of infection. With gold substrate, our work here intends to explore if SERS is suitable to detect NS1 from saliva, with saliva becoming the most favored alternative to blood as diagnostic fluid due to its advantages in sample collection. Our experimental results find both gold coated slide (GS) and saliva being Raman inactive, but the molecular fingerprint of NS1 protein at Raman shift 1012 cm(-1), which has never been reported before. The distinct peak is discovered to be attributed by breathing vibration of the benzene ring structure of NS1 side chain molecule. The characteristic peak is also found to vary in direct proportion to concentration of the NS1-saliva mixture, with a correlation coefficient of +0.96118 and a standard error estimation of 0.11382.

  4. The effects of sorting by aeolian processes on the geochemical characteristics of surface materials: a wind tunnel experiment

    Science.gov (United States)

    Wang, Xunming; Lang, Lili; Hua, Ting; Zhang, Caixia; Li, Hui

    2017-03-01

    The geochemical characteristics of aeolian and surface materials in potential source areas of dust are frequently employed in environmental reconstructions as proxies of past climate and as source tracers of aeolian sediments deposited in downwind areas. However, variations in the geochemical characteristics of these aeolian deposits that result from near-surface winds are currently poorly understood. In this study, we collected surface samples from the Ala Shan Plateau (a major potential dust source area in Central Asia) to determine the influence of aeolian processes on the geochemical characteristics of aeolian transported materials. Correlation analyses show that compared with surface materials, the elements in transported materials (e.g., Cu, As, Pb, Mn, Zn, Al, Ca, Fe, Ga, K, Mg, P, Rb, Co, Cr, Na, Nb, Si, and Zr) were subjected to significant sorting by aeolian processes, and the sorting also varied among different particle size fractions and elements. Variations in wind velocity were significantly correlated with the contents of Cr, Ga, Sr, Ca, Y, Nd, Zr, Nb, Ba, and Al, and with the Zr/Al, Zr/Rb, K/Ca, Sr/Ca, Rb/Sr, and Ca/Al ratios. Given the great variation in the geochemical characteristics of materials transported under different aeolian processes relative to those of the source materials, these results indicate that considerable uncertainty may be introduced to analyses by using surface materials to trace the potential source areas of aeolian deposits that accumulate in downwind areas.

  5. Study of the Material Transfer Characteristics and Surface Morphology Due to Arc Erosion of PtIr Contact Materials

    Institute of Scientific and Technical Information of China (English)

    WANG Saibei; XIE Ming; YANG Youcai; ZHANG Jiming; CHEN Yongtai; LIU Manmen; YANG Yunfeng; HU Jieqiong; CUI Hao

    2012-01-01

    By means of breaking tests on PtIr contact materials via a JF04C contact material testing machine,it was attempted to elucidate the characterstics of the various surface morphology and material transfer after the arc erosion process caused by break arc.The material transfer characteristics appeared in the experiments were concluded and analyzed.Meanwhile,the morphology of the anode and cathode surface were observed and analyzed by SEM.

  6. Structural and chemical characteristics of atomically smooth GaN surfaces prepared by abrasive-free polishing with Pt catalyst

    Science.gov (United States)

    Murata, Junji; Sadakuni, Shun; Okamoto, Takeshi; Hattori, Azusa N.; Yagi, Keita; Sano, Yasuhisa; Arima, Kenta; Yamauchi, Kazuto

    2012-06-01

    This paper reports the structural and chemical characteristics of atomically flat gallium nitride (GaN) surfaces prepared by abrasive-free polishing with platinum (Pt) catalyst. Atomic force microscopy revealed regularly alternating wide and narrow terraces with a step height equivalent to that of a single bilayer on the flattened GaN surfaces, which originate from the differences in etching rate of two neighboring terraces. The material removal characteristics of the method for GaN surfaces were investigated in detail. We confirmed that an atomically smooth GaN surface with an extremely small number of surface defects, including pits and scratches, can be achieved, regardless of the growth method, surface polarity, and doping concentration. X-ray photoelectron spectroscopy showed that the flattening method produces clean GaN surfaces with only trace impurities such as Ga oxide and metallic Ga. Contamination with the Pt catalyst was also evaluated using total-reflection X-ray fluorescence analysis. A wet cleaning method with aqua regia is proposed, which markedly eliminates this Pt contamination without affecting the surface morphology.

  7. Characteristics of the molar surface after removal of cervical enamel projections: comparison of three different rotating instruments

    Science.gov (United States)

    2016-01-01

    Purpose The aim of this study was to evaluate and compare tooth surface characteristics in extracted human molars after cervical enamel projections (CEPs) were removed with the use of three rotating instruments. Methods We classified 60 extracted molars due to periodontal lesion with CEPs into grade I, II, or III, according to the Masters and Hoskins’ criteria. Each group contained 20 specimens. Three rotating instruments were used to remove the CEPs: a piezoelectric ultrasonic scaler, a periodontal bur, and a diamond bur. Tooth surface characteristics before and after removal of the projections were then evaluated with scanning electron microscopy (SEM). We analyzed the characteristics of the tooth surfaces with respect to roughness and whether the enamel projections had been completely removed. Results In SEM images, surfaces treated with the diamond bur were smoothest, but this instrument caused considerable harm to tooth structures near the CEPs. The piezoelectric ultrasonic scaler group produced the roughest surface but caused less harm to the tooth structure near the furcation. In general, the surfaces treated with the periodontal bur were smoother than those treated with the ultrasonic scaler, and the periodontal bur did not invade adjacent tooth structures. Conclusions For removal of grade II CEPs, the most effective instrument was the diamond bur. However, in removing grade III projections, the diamond bur can destroy both adjacent tooth structures and the periodontal apparatus. In such cases, careful use of the periodontal bur may be an appropriate substitute. PMID:27127691

  8. Measurements of water film characteristics on airfol surfaces from wind-tunnel tests with simulated heavy rain

    Science.gov (United States)

    Hastings, E. C., Jr.; Manuel, G. S.

    1985-01-01

    This paper discusses some of the surface water characteristics obtained during recent simulated heavy rain experiments conducted at the Langley Research Center. Water film distributions and discrete film thickness measurements on several model wings are discussed. The water film distributions on the upper surfaces are shown in photographs from cameras mounted above the models, and film thickness data are presented which were obtained using resistance sensors mounted flush with the upper and lower wing model surfaces. The paper also discusses potential sources of performance decrements indicated by the data.

  9. Adhesion-creepage characteristics of wheel/rail system under dry and contaminated rail surfaces

    Science.gov (United States)

    Alzoubi, Mohammed F.

    1998-11-01

    This thesis presents an experimental and theoretical study of adhesion and creepage characteristics of wheel and rail under both dry and contaminated rail surfaces. The experimental work was conducted largely on the IIT 1/4.5 Scale Wheel/Rail Simulation Facility. Based on the experimental data in the laboratory, a theoretical model of adhesion and creepage relationship with different degrees of contamination was developed. Non-dimensional analysis of parameters yielded four important non-dimensional groups, which include the adhesion, creepage coefficients, the elastic properties of the materials, the load on the wheel surface roughness of wheel and rail, train speed and the contaminant density, viscosity and minimum film thickness. Rail contaminants were gathered from several U.S. passenger rail systems and tested on the laboratory facility. It was found that presence of moisture reduce the adhesion levels with these contaminants. Under hot air jet applications, normal adhesion could be achieved. A series of tests were conducted with water contamination on clean rail. Maximum adhesion for different tests was nearly constant and approximately 0.2. Maximum adhesion produced under water contamination is significantly affected by the average roughness of the wheel and the rail. As the roughness decreases, maximum adhesion drops sharply. Maximum adhesion also decreases with speed in the presence of moisture even at relatively low speeds (4--8 mph). An empirical relation of maximum adhesion with axle load, speed and roughness has been derived. An analytical expression for the adhesion-creepage curves under (TOR) lubrication has been derived. The maximum adhesion coefficient achieved for different (TOR) lubricant formulations was found to be approximately proportional to kinematic viscosity. A theoretical approach for estimating potential energy savings with the (TOR) lubricant was developed using the laboratory data of the 1/12.5 scale simulator and 1/4.5 scale test

  10. Cellular Responses Evoked by Different Surface Characteristics of Intraosseous Titanium Implants

    Directory of Open Access Journals (Sweden)

    Liviu Feller

    2015-01-01

    Full Text Available The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration.

  11. Characteristics of laser textured silicon surface and effect of mud adhesion on hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, B.S., E-mail: bsyilbas@kfupm.edu.sa [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Ali, H. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Khaled, M. [CHEM Department, King Fahd University of Petroleum & Minerals, Dhahran (Saudi Arabia); Al-Aqeeli, N.; Abu-Dheir, N. [ME Department, King Fahd University of Petroleum & Minerals, Kfupm box 1913, Dhahran 31261 (Saudi Arabia); Varanasi, K.K. [Mechanical Engineering, Massachusetts Institute of Technology, Boston, MA (United States)

    2015-10-01

    Highlights: • Laser treatment increases surface microhardness and slightly lowers surface fracture toughness. • Residual stress formed is compressive and self-annealing effect of laser tracks lowers residual stress. • Nitride species lowers surface energy and adhesion work required to remove dust. • Mud residues do not have notable effect on fracture toughness and microhardness of treated surface. • Mud residues lower surface hydrophobicity. - Abstract: Laser gas assisted texturing of silicon wafer surface is carried out. Morphological and metallurgical changes in the treated layer are examined using the analytical tools. Microhardness and fracture toughness of the laser treated surface are measured using the indentation technique while residual stress formed is determined from the X-ray diffraction data. The hydrophobicity of the textured surfaces are assessed incorporating the contact angle data and compared with those of as received workpiece surfaces. Environmental dust accumulation and mud formation, due to air humidity, at the laser treated and as received workpiece surfaces are simulated and the effect of the mud residues on the properties of the laser treated surface are studied. The adhesion work due to the presence of the mud on the laser treated surface is also measured. It is found that laser textured surface composes of micro/nano poles and fibers, which in turn improves the surface hydrophobicity significantly. In addition, formation of nitride species contributes to microhardness increase and enhancement of surface hydrophobicity due to their low surface energy. The mud residues do not influence the fracture toughness and microhardness of the laser textured surface; however, they reduced the surface hydrophobicity significantly.

  12. STUDY OF DEPENDENCE OF POLYETHYLENE AND CARBON FIBERS COMPOSITES PROPERNIES ON SURFACE CHARACTERISTICS OF FIBER AND TYPE OF SAMPLES

    OpenAIRE

    Petukhova E. S.

    2015-01-01

    PE2NT11 and chopped carbon fibers and PE2NT11 and modified carbon fibers composites were investigated. It was shown that the mechanical properties depend on the surface characteristics of fibers. It was found that laboratory and tube samples have some difference in mechanical properties that connected with specific distribution of fibers in samples

  13. STUDY OF DEPENDENCE OF POLYETHYLENE AND CARBON FIBERS COMPOSITES PROPERNIES ON SURFACE CHARACTERISTICS OF FIBER AND TYPE OF SAMPLES

    Directory of Open Access Journals (Sweden)

    Petukhova E. S.

    2015-06-01

    Full Text Available PE2NT11 and chopped carbon fibers and PE2NT11 and modified carbon fibers composites were investigated. It was shown that the mechanical properties depend on the surface characteristics of fibers. It was found that laboratory and tube samples have some difference in mechanical properties that connected with specific distribution of fibers in samples

  14. Spatial and Temporal Variations of Surface Characteristics on the Greenland Ice Sheet as Derived from Passive Microwave Observations

    Science.gov (United States)

    Anderson, Mark; Rowe, Clinton; Kuivinen, Karl; Mote, Thomas

    1996-01-01

    The primary goals of this research were to identify and begin to comprehend the spatial and temporal variations in surface characteristics of the Greenland ice sheet using passive microwave observations, physically-based models of the snowpack and field observations of snowpack and firn properties.

  15. [Pollution Characteristics and Potential Ecological Risk of Heavy Metals in Urban Surface Water Sediments from Yongkang].

    Science.gov (United States)

    Qi, Peng; Yu, Shu-quan; Zhang, Chao; Liang, Li-cheng; Che, Ji-lu

    2015-12-01

    In order to understand the pollution characteristics of heavy metals in surface water sediments of Yongkang, we analyzed the concentrations of 10 heavy metals including Ti, Cr, Mn, Co, Ni, Cu, Zn, As, Pb and Fe in 122 sediment samples, explored the underlying source of heavy metals and then assessed the potential ecological risks of those metals by methods of the index of geo-accumulation and the potential ecological risk. The study results showed that: 10 heavy metal contents followed the order: Fe > Ti > Mn > Zn > Cr > Cu > Ph > Ni > As > Co, all heavy metals except for Ti were 1. 17 to 3.78 times higher than those of Zhejiang Jinhua- Quzhou basin natural soils background values; The concentrations of all heavy metals had a significantly correlation between each other, indicating that those heavy metals had similar sources of pollution, and it mainly came from industrial and vehicle pollutions; The pollution extent of heavy metals in sediments by geo-accumulation index (Igeo) followed the order: Cr > Zn > Ni > Cu > Fe > As > Pb >Mn > Ti, thereinto, Cr, Zn, Cu and Ni were moderately polluted or heavily polluted at some sampling sites; The potential ecological risk of 9 heavy metals in sediments were in the following order: Cu > As > Ni > Cr > Pb > Co > Zn > Mn > Ti, Cu and As contributed the most to the total potential ecological risk, accounting for 22.84% and 21. 62% , others had a total of 55.54% , through the ecological risk assessment, 89. 34% of the potential ecological risk indexes ( RI) were low and 10. 66% were higher. The contamination level of heavy metals in Yongkang was slight in total, but was heavy in local areas.

  16. Self-consistent many-electron theory of electron work functions and surface potential characteristics for selected metals

    Science.gov (United States)

    Smith, J. R.

    1969-01-01

    Electron work functions, surface potentials, and electron number density distributions and electric fields in the surface region of 26 metals were calculated from first principles within the free electron model. Calculation proceeded from an expression of the total energy as a functional of the electron number density, including exchange and correlation energies, as well as a first inhomogeneity term. The self-consistent solution was obtained via a variational procedure. Surface barriers were due principally to many-body effects; dipole barriers were small only for some alkali metals, becoming quite large for the transition metals. Surface energies were inadequately described by this model, which neglects atomistic effects. Reasonable results were obtained for electron work functions and surface potential characteristics, maximum electron densities varying by a factor of over 60.

  17. Dynamic performance of a pantograph-catenary system with the consideration of the appearance characteristics of contact surfaces

    Institute of Scientific and Technical Information of China (English)

    Ning ZHOU; Wei-hua ZHANG; Rui-ping LI

    2011-01-01

    In this paper,a modeling method for a pantograph-catenary system is put forward to investigate the dynamic contact behavior in space,taking into consideration of the appearance characteristics of the contact surfaces of the pantograph and catenary.The dynamic performance of the pantograph-catenary system,including contact forces,accelerations,and the corresponding spectra,is analyzed.Furthermore,with the modeling method,the influences of contact wire irregularity and the vibration caused by the front pantograph on the rear pantograph for a pantograph-catenary system with double pantographs are investigated.The results show that the appearance characteristics of the contact surfaces play an important role in the dynamic contact behavior.The appearance characteristics should be considered to reasonably evaluate the dynamic performance of the pantograph-catenary system.

  18. A Facile Method to Modify the Characteristics and Corrosion Behavior of 304 Stainless Steel by Surface Nanostructuring toward Biomedical Applications.

    Science.gov (United States)

    Thangaraj, Balusamy; Nellaiappan, Sankara Narayanan T S; Kulandaivelu, Ravichandran; Lee, Min Ho; Nishimura, Toshiyasu

    2015-08-19

    The study addresses how surface nanostructuring of AISI 304 stainless steel (SS) by surface mechanical attrition treatment (SMAT) influences its characteristic properties and corrosion behavior in Ringer's solution. SMAT of 304 SS induced plastic deformation, enabled surface nanocrystallization, refined the grain size, transformed the austenite phase to strain induced α'-martensite phase, increased the surface roughness, induced defects/dislocations, imparted compressive residual stresses at the surface, decreased the contact angle, and increased surface energy. The change in properties of 304 SS following treatment using 5 and 8 mm ⌀ balls for 15, 30, 45, and 60 min has caused a deleterious influence on its corrosion resistance in Ringer's solution, while an improvement in corrosion behavior is observed for those treated using 2 mm ⌀ balls. The increase in surface roughness, transformation of the austenite to α'-martensite phase, a higher extent of deformation, and the presence of larger number of defects/dislocations are main factors responsible for the lower corrosion resistance observed for 304 SS treated using 5 and 8 mm ⌀ balls in Ringer's solution. In spite of having these attributes with a relatively lower extent, 304 SS treated using 2 mm ⌀ balls offered a better corrosion resistance and exhibits a better passivity. For those treated using 2 mm ⌀ balls, the ability of the nanocrystalline surface to promote passivation outweighs the deleterious influences caused by the limited amount of deformation and defects/dislocations. Based on the findings of this study, it is recommend that SMAT of 304 SS using 2 mm ⌀ balls for 15-30 min is the optimum condition to achieve the suitable surface profile, surface characteristics with better corrosion resistance.

  19. CHLORINE DIOXIDE TREATMENT OF SISAL FIBRE: SURFACE LIGNIN AND ITS INFLUENCES ON FIBRE SURFACE CHARACTERISTICS AND INTERFACIAL BEHAVIOUR OF SISAL FIBRE/PHENOLIC RESIN COMPOSITES

    Directory of Open Access Journals (Sweden)

    Linxin Zhong

    2010-11-01

    Full Text Available This paper describes an investigation of the influences of chlorine dioxide treatment on fibre surface lignin. The fibre surface characteristics and the interfacial behaviour of the sisal fibre/phenolic resin composites were also studied by SEM, AFM, and XPS. The results show that the surface of the untreated fibre contains a large amount of lignin with granular structure and non-granular structure. The surface lignin concentration is up to 51% for the untreated fibre, and then it decreases to 24% and 20% for fibres treated with 1.5 % and 2.0% chlorine dioxide, respectively. The removal of lignin from the fibre surface can enhance the interfacial strength of the composites, giving rise to increases by 36% and 28% in tensile strength and internal bonding strength. These results indicate that the surface properties of single sisal fibres can be tailored to improve the fibre/resin interface. Chlorine dioxide treatment has potential for surface modification of sisal fibre in engineering the interfacial behaviour of composites.

  20. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules

    Science.gov (United States)

    Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treate...

  1. Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Y.F., E-mail: yfzheng@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); State Key Laboratory for Turbulence and Complex System, College of Engineering, Peking University, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China)

    2013-10-15

    The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process.

  2. Investigation of surface characteristics evolution and laser damage performance of fused silica during ion-beam sputtering

    Science.gov (United States)

    Xu, Mingjin; Dai, Yifan; Zhou, Lin; Shi, Feng; Wan, Wen; Xie, Xuhui; Sui, Tingting

    2016-08-01

    Surface characteristics have great influence on the optical properties especially the laser radiation resistivity of optics. In this paper, the surface characteristics evolutions of fused silica during ion-beam sputtering and their effects on the laser damage performance were investigated. The results show that roughness change is strongly removal depth dependent and a super-smooth surface (0.25 nm RMS) can be obtained by the ion-induced smoothing effect. The concentration of metal impurities (especially Ce element) in subsurface can be effectively decreased after the removal of polishing re-deposition layer. During ion-beam sputtering process, the plastic scratches can be removed while the brittle cracks can be broadened and passivated without increase in the depth direction. Laser damage threshold of fused silica improved by 36% after ion-beam sputtering treatment. Research results have a guiding significance for ion-beam sputtering process technology of fused silica optics.

  3. Impact of atomization technique on the stability and transport efficiency of nebulized liposomes harboring different surface characteristics.

    Science.gov (United States)

    Lehofer, Bernhard; Bloder, Florian; Jain, Pritesh P; Marsh, Leigh M; Leitinger, Gerd; Olschewski, Horst; Leber, Regina; Olschewski, Andrea; Prassl, Ruth

    2014-11-01

    The objective of this study was to evaluate the impact of nebulization on liposomes with specific surface characteristics by applying three commercially available inhaler systems (air-jet, ultrasonic and vibrating-mesh). Conventional liposome formulations composed of phosphatidylcholine and cholesterol were compared to sterically stabilized PEGylated liposomes and cationic polymer coated liposomes.Liposomes of similar size (between 140 and 165 nm in diameter with polydispersity indices atomization process, while polymer coated and especially positively charged liposomes showed enhanced leakage. The release rates for the hydrophilic model drug system were highest for the vibrating-mesh nebulizers regardless of the surface characteristics of the liposomes (increasing from 10% to 20% and 50% for the conventional, PEGylated and positively charged formulations, respectively). In view of surface modified liposomes our data suggest that drug delivery via nebulization necessitates the finding of a compromise between nebulizer efficiency, formulation stability and drug release profile to accomplish the development of tailored formulations suitable for advanced inhalation therapy.

  4. Foulant characteristics comparison in recycling cooling water system makeup by municipal reclaimed water and surface water in power plant.

    Science.gov (United States)

    Ping, Xu; Jing, Wang; Yajun, Zhang; Jie, Wang; Shuai, Si

    2015-01-01

    Due to water shortage, municipal reclaimed water rather than surface water was replenished into recycling cooling water system in power plants in some cities in China. In order to understand the effects of the measure on carbon steel corrosion, characteristics of two kinds of foulant produced in different systems were studied in the paper. Differences between municipal reclaimed water and surface water were analyzed firstly. Then, the weight and the morphology of two kinds of foulant were compared. Moreover, other characteristics including the total number of bacteria, sulfate reducing bacteria, iron bacteria, extracellular polymeric substance (EPS), protein (PN), and polysaccharide (PS) in foulant were analyzed. Based on results, it could be concluded that microbial and corrosive risk would be increased when the system replenished by municipal reclaimed water instead of surface water.

  5. Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.

    Science.gov (United States)

    Ma, Lin; Xu, Zhiwu; Zheng, Kun; Yan, Jiuchun; Yang, Shiqin

    2014-03-01

    The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 μm or when the amplitude of the liquid solder surface is higher than 10.2 μm.

  6. Surface Energy Characteristics of Toner Particles by Automated Inverse Gas Chromatography

    NARCIS (Netherlands)

    Segeren, L.H.G.J.; Wouters, M.E.L.; Bos, M.; van den Berg, J.W.A.; Vancso, Gyula J.

    2002-01-01

    Inverse gas chromatography (IGC) was applied to the surface energy study of surfaces of toner particles. The dispersive component of the surface energy was determined for three toner materials by infinite dilution IGC. The values obtained were comparable to the values obtained from contact angle

  7. Measurement of Separated Flow Structures Using a Multiple-Camera DPIV System. [conducted in the Langley Subsonic Basic Research Tunnel

    Science.gov (United States)

    Humphreys, William M., Jr.; Bartram, Scott M.

    2001-01-01

    A novel multiple-camera system for the recording of digital particle image velocimetry (DPIV) images acquired in a two-dimensional separating/reattaching flow is described. The measurements were performed in the NASA Langley Subsonic Basic Research Tunnel as part of an overall series of experiments involving the simultaneous acquisition of dynamic surface pressures and off-body velocities. The DPIV system utilized two frequency-doubled Nd:YAG lasers to generate two coplanar, orthogonally polarized light sheets directed upstream along the horizontal centerline of the test model. A recording system containing two pairs of matched high resolution, 8-bit cameras was used to separate and capture images of illuminated tracer particles embedded in the flow field. Background image subtraction was used to reduce undesirable flare light emanating from the surface of the model, and custom pixel alignment algorithms were employed to provide accurate registration among the various cameras. Spatial cross correlation analysis with median filter validation was used to determine the instantaneous velocity structure in the separating/reattaching flow region illuminated by the laser light sheets. In operation the DPIV system exhibited a good ability to resolve large-scale separated flow structures with acceptable accuracy over the extended field of view of the cameras. The recording system design provided enhanced performance versus traditional DPIV systems by allowing a variety of standard and non-standard cameras to be easily incorporated into the system.

  8. Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine

    Science.gov (United States)

    Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

    1999-01-01

    Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

  9. Subsonic Wake Characterization of the Orion Capsule Using PIV in the Ames UPWT 11-foot Wind Tunnel (Invited)

    Science.gov (United States)

    Heineck, James T.; Ross, James C.; Yamauchi, Gloria K.

    2015-01-01

    The subsonic regime of Crew Capsule reentry has a very turbulent waker through which the Drogue Chutes must deploy. This presentation describes the particle image velocimetry measurement campaign used to help retire the risk.

  10. An Efficient Inverse Aerodynamic Design Method For Subsonic Flows

    Science.gov (United States)

    Milholen, William E., II

    2000-01-01

    Computational Fluid Dynamics based design methods are maturing to the point that they are beginning to be used in the aircraft design process. Many design methods however have demonstrated deficiencies in the leading edge region of airfoil sections. The objective of the present research is to develop an efficient inverse design method which is valid in the leading edge region. The new design method is a streamline curvature method, and a new technique is presented for modeling the variation of the streamline curvature normal to the surface. The new design method allows the surface coordinates to move normal to the surface, and has been incorporated into the Constrained Direct Iterative Surface Curvature (CDISC) design method. The accuracy and efficiency of the design method is demonstrated using both two-dimensional and three-dimensional design cases.

  11. [INVITED] Laser gas assisted treatment of Ti-alloy: Analysis of surface characteristics

    Science.gov (United States)

    Yilbas, B. S.; Ali, H.; Karatas, C.

    2016-04-01

    Laser gas assisted treatment of Ti6Al4V alloy surface is carried out and nitrogen/oxygen mixture with partial pressure of PO2/PN2=1/3 is introduced during the surface treatment process. Analytical tools are used to characterize the laser treated surfaces. The fracture toughness at the surface and the residual stress in the surface region of the laser treated layer are measured. Scratch tests are carried out to determine the friction coefficient of the treated surface. It is found that closely spaced regular laser scanning tracks generates a self-annealing effect in the laser treated layer while lowering the stress levels in the treated region. Introducing high pressure gas mixture impingement at the surface results in formation of oxide and nitride species including, TiO, TiO2, TiN and TiOxNy in the surface region. A dense layer consisting of fine size grains are formed in the surface region of the laser treated layer, which enhances the microhardness at the surface. The fracture toughness reduces after the laser treatment process because of the microhardness enhancement at the surface. The residual stress formed is comprehensive, which is in the order of -350 MPa.

  12. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: the influence of zeolite chemical surface characteristics.

    Science.gov (United States)

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A

    2014-06-15

    In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  13. Directional Characteristics of Thermal-Infrared Beaming from Atmosphereless Planetary Surfaces - A New Thermophysical Model

    CERN Document Server

    Rozitis, Ben

    2012-01-01

    We present a new rough-surface thermophysical model (Advanced Thermophysical Model or ATPM) that describes the observed directional thermal emission from any atmosphereless planetary surface. It explicitly incorporates partial shadowing, scattering of sunlight, selfheating and thermal-infrared beaming (re-radiation of absorbed sunlight back towards the Sun as a result of surface roughness). The model is verified by accurately reproducing ground-based directional thermal emission measurements of the lunar surface using surface properties that are consistent with the findings of the Apollo missions and roughness characterised by an RMS slope of ~32 degrees. By considering the wide range of potential asteroid surface properties, the model implies a beaming effect that cannot be described by a simple parameter or function. It is highly dependent on the illumination and viewing angles as well as surface thermal properties and is predominantly caused by macroscopic rather than microscopic roughness. Roughness alter...

  14. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation

    Science.gov (United States)

    Kikuchi, Y.; Nishijima, D.; Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M.; Kawai, T.; Ueda, Y.; Fukumoto, N.; Doerner, R. P.

    2011-08-01

    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of ˜0.5 ms, incident ion energy of ˜30 eV, and surface absorbed energy density of ˜0.3-0.7 MJ/m2. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of ˜0.7 MJ/m2, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  15. Alignment of dust particles by ion drag forces in subsonic flows

    Energy Technology Data Exchange (ETDEWEB)

    Piel, Alexander [IEAP, Christian-Albrechts-University, D-24098 Kiel (Germany)

    2011-07-15

    The role of ion drag forces for the alignment of dust particles is studied for subsonic flows. While alignment by wake-field attraction is a well known mechanism for supersonic flows, it is argued here that ion-scattering forces become more important in subsonic ion flows. A model of non-overlapping collisions is introduced and numerical results are discussed. For typical conditions of dusty plasma experiments, alignment by drag forces is found strong enough to overcome the destabilizing force from Coulomb repulsion between dust particles. It turns out that the major contribution to the horizontal restoring force originates from the transverse momentum transfer, which is usually neglected in ion drag force calculations because of an assumed rotational symmetry of the flow.

  16. Fluctuation diagrams for hot-wire anemometry in subsonic compressible flows

    Science.gov (United States)

    Stainback, P. C.; Nagabushana, K. A.

    1991-01-01

    The concept of using 'fluctuation diagrams' for describing basic fluctuations in compressible flows was reported by Kovasznay in the 1950's. The application of this technique, for the most part, was restricted to supersonic flows. Recently, Zinovev and Lebiga published reports where they considered the fluctuation diagrams in subsonic compressible flows. For the above studies, the velocity and density sensitivities of the heated wires were equal. However, there are considerable data, much taken in the 1950's, which indicate that under some conditions the velocity and density sensitivities are not equal in subsonic compressible flows. Therefore, possible fluctuation diagrams are described for the cases where the velocity and density sensitivities are equal and the more general cases where they are unequal.

  17. Far-Field Turbulent Vortex-Wake/Exhaust Plume Interaction for Subsonic and HSCT Airplanes

    Science.gov (United States)

    Kandil, Osama A.; Adam, Ihab; Wong, Tin-Chee

    1996-01-01

    Computational study of the far-field turbulent vortex-wake/exhaust plume interaction for subsonic and high speed civil transport (HSCT) airplanes is carried out. The Reynolds-averaged Navier-Stokes (NS) equations are solved using the implicit, upwind, Roe-flux-differencing, finite-volume scheme. The two-equation shear stress transport model of Menter is implemented with the NS solver for turbulent-flow calculation. For the far-field study, the computations of vortex-wake interaction with the exhaust plume of a single engine of a Boeing 727 wing in a holding condition and two engines of an HSCT in a cruise condition are carried out using overlapping zonal method for several miles downstream. These results are obtained using the computer code FTNS3D. The results of the subsonic flow of this code are compared with those of a parabolized NS solver known as the UNIWAKE code.

  18. Improved Performances in Subsonic Flows of an SPH Scheme with Gradients Estimated using an Integral Approach

    CERN Document Server

    Valdarnini, R

    2016-01-01

    In this paper we present results from a series of hydrodynamical tests aimed at validating the performance of a smoothed particle hydrodynamics (SPH) formulation in which gradients are derived from an integral approach. We specifically investigate the code behavior with subsonic flows, where it is well known that zeroth-order inconsistencies present in standard SPH make it particularly problematic to correctly model the fluid dynamics. In particular we consider the Gresho-Chan vortex problem, the growth of Kelvin-Helmholtz instabilities, the statistics of driven subsonic turbulence and the cold Keplerian disc problem. We compare simulation results for the different tests with those obtained, for the same initial conditions, using standard SPH. We also compare the results with the corresponding ones obtained previously with other numerical methods, such as codes based on a moving-mesh scheme or Godunov-type Lagrangian meshless methods. We quantify code performances by introducing error norms and spectral prope...

  19. Materials and Structures Research for Gas Turbine Applications Within the NASA Subsonic Fixed Wing Project

    Science.gov (United States)

    Hurst, Janet

    2011-01-01

    A brief overview is presented of the current materials and structures research geared toward propulsion applications for NASA s Subsonic Fixed Wing Project one of four projects within the Fundamental Aeronautics Program of the NASA Aeronautics Research Mission Directorate. The Subsonic Fixed Wing (SFW) Project has selected challenging goals which anticipate an increasing emphasis on aviation s impact upon the global issue of environmental responsibility. These goals are greatly reduced noise, reduced emissions and reduced fuel consumption and address 25 to 30 years of technology development. Successful implementation of these demanding goals will require development of new materials and structural approaches within gas turbine propulsion technology. The Materials and Structures discipline, within the SFW project, comprise cross-cutting technologies ranging from basic investigations to component validation in laboratory environments. Material advances are teamed with innovative designs in a multidisciplinary approach with the resulting technology advances directed to promote the goals of reduced noise and emissions along with improved performance.

  20. Analysis of laser generated ultrasonic wave frequency characteristics induced by a partially closed surface-breaking crack.

    Science.gov (United States)

    Li, Jia; Zhang, Hongchao; Ni, Chenyin; Shen, Zhonghua

    2013-06-20

    This research focuses on analyzing the frequency characteristics of ultrasonic waves induced by a partially closed surface-breaking crack. When acoustic waves interact with the crack, transmission, reflection, and mode conversions occur and the frequency characteristics of signals perform obvious changes. A pulsed laser line source is used to generate ultrasonic waves in the sample with a partially closed surface-breaking crack, and one can see how the frequency characteristics of detected signals change as the pulsed laser beam scans across the sample surface. The optical deflection beam method is developed to detect the ultrasonic signals experimentally. The fast Fourier transform (FFT) is used to analyze the time-domain data, and the FFT data are visualized by a B-scan plot. A clear disruption in the B-scan can be observed when the laser beam illuminates directly onto the crack, which is due to the changes of frequency characteristics induced by the partially closed crack. A frequency-domain B-scan of numerical simulation results is presented, and the clear disruption can also be observed clearly.

  1. Characteristics of surface ozone and nitrogen oxides at urban, suburban and rural sites in Ningbo, China

    Science.gov (United States)

    Tong, Lei; Zhang, Huiling; Yu, Jie; He, Mengmeng; Xu, Nengbin; Zhang, Jingjing; Qian, Feizhong; Feng, Jiayong; Xiao, Hang

    2017-05-01

    Surface ozone (O3) is a harmful air pollutant that has attracted growing concern in China. In this study, the mixing ratios of O3 and nitrogen oxides (NOx) at three different sites (urban, suburban and rural) of Ningbo were continuously measured to investigate the spatiotemporal characteristics of O3 and its relationships with environmental variables. The diurnal O3 variations were characterized by afternoon maxima (38.7-53.1 ppb on annual average) and early morning minima (11.7-26.2 ppb) at all the three sites. Two seasonal peaks of O3 were observed in spring (April or May) and autumn (October) with minima being observed in winter (December). NOx levels showed generally opposite variations to that of O3 with diurnal and seasonal maxima occurring in morning/evening rush-hours and in winter, respectively. As to the inter-annual variations of air pollutants, generally decreasing and increasing trends were observed in NO and O3 levels, respectively, from 2012 to 2015 at both urban and suburban sites. O3 levels were positively correlated with temperature but negatively correlated with relative humidity and NOx levels. Significant differences in O3 levels were observed for different wind speeds and wind directions (p urban site exhibited lower O3 but higher NOx levels due to the influence of traffic emissions. Larger amplitudes of diurnal and monthly O3 variations were observed at the suburban site than those at the urban and rural sites. In general, the O3 levels at the non-urban sites were more affected by the background transport, while both the local and regional contributions played roles in urban O3 variations. The annual average O3 mixing ratios (22.7-37.7 ppb) in Ningbo were generally similar to those of other regions around the world. However, the recommended air quality standards for O3 were often exceeded during warm seasons, which could be a potential threat to both local population and plant growth.

  2. Projected changes to surface wind characteristics and extremes over North America in CRCM5

    Science.gov (United States)

    Jeong, Dae Il; Sushama, Laxmi

    2017-04-01

    Changes in the tendency of wind speed and direction have significant implications for long-term water cycle, air pollution, arid and semiarid environments, fire activity, and wind energy production. Furthermore, changes in wind extremes have direct impacts on buildings, infrastructures, agriculture, power lines, and trees. This study evaluates projected changes to wind speed characteristics (i.e., seasonal and annual mean, seasonal and diurnal cycles, directional distribution, and extreme events) for the future 2071-2100 period, with respect to the current 1981-2010 period over North America, using four different simulations from the fifth-generation Canadian Regional Climate Model (CRCM5) with two driving GCMs under RCP (Representative Concentration Pathways) 4.5 and 8.5 scenarios. The CRCM5 simulates the climatology of mean sea level pressure gradient and associated wind direction over North America well when compared to ERA-Interim reanalysis dataset. The CRCM5 also reproduces properly the spatial distributions of observed seasonal and annual mean wind speeds obtained from 611 meteorological stations across North America. The CRCM5 simulations generally suggest an increase in future mean wind speed for northern and eastern parts of Canada, due to a decrease of future mean sea level pressure and more intense low pressure air circulation systems already situated in those regions such as Aleutian and Icelandic Lows. Projected changes to annual maximum wind speed show more spatial variability compared to seasonal and annual mean wind speed as extreme wind speed is influenced more by regional-scale features associated with instantaneous surface temperature and air pressure gradients. The CRCM5 simulations suggest some increases in the future 50-year return levels of wind speed, mainly due to changes in the inter-annual variability of annual maximum wind speed. However, the projected changes vary in spatial pattern with the driving GCM fields and emission scenarios

  3. Turbulent characteristics of a semiarid atmospheric surface layer from cup anemometers – effects of soil tillage treatment (Northern Spain

    Directory of Open Access Journals (Sweden)

    S. Yahaya

    Full Text Available This paper deals with the characteristics of turbulent flow over two agricultural plots with various tillage treatments in a fallow, semiarid area (Central Aragon, Spain. The main dynamic characteristics of the Atmospheric Surface Layer (ASL measured over the experimental site (friction velocity, roughness length, etc., and energy budget, have been presented previously (Frangi and Richard, 2000. The current study is based on experimental measurements performed with cup anemometers located in the vicinity of the ground at 5 different levels (from 0.25 to 4 m and sampled at 1 Hz. It reveals that the horizontal wind variance, the Eulerian integral scales, the frequency range of turbulence and the turbulent kinetic energy dissipation rate are affected by the surface roughness. In the vicinity of the ground surface, the horizontal wind variance logarithmically increases with height, directly in relation to the friction velocity and the roughness length scale. It was found that the time integral scale (and subsequently the length integral scale increased with the surface roughness and decreased with the anemometer height. These variations imply some shifts in the meteorological spectral gap and some variations of the spectral peak length scale. The turbulent energy dissipation rate, affected by the soil roughness, shows a z-less stratification behaviour under stable conditions. In addition to the characterization of the studied ASL, this paper intends to show which turbulence characteristics, and under what conditions, are accessible through the cup anemometer.

    Key words. Meteorology and atmospheric dynamics (climatology, turbulence, instruments and techniques

  4. Study of oxidation characteristic on copper surface exposed by surface wave plasma%表面波等离子体暴露下铜表面的氧化特性

    Institute of Scientific and Technical Information of China (English)

    吉田圭佑; 妻鹿义治; 川添博光; 松野隆; 山田刚治; 竹内新

    2011-01-01

    Surface wave plasma (SWP) is a kind of low temperature plasma which can be utilized for material development. In this research, argon and oxygen were used as a working gas for an SWP experiment and the influence of the plasma irradiation on a copper surface was examined. Particular, relation between the spatial characteristics of SWP and wetting characteristics was examined. As a result, it was found that spatial characteritics of the SWP affected the wetting characteristics and the oxidation characteristics.

  5. Wind Tunnel Investigation of Passive Porosity Applied to the Leading-Edge Extension and Leading-Edge Flaps on a Slender Wing at Subsonic Speed

    Science.gov (United States)

    Erickson, Gary E.

    2017-01-01

    A wind tunnel experiment was conducted in the NASA Langley Research Center 7- by 10-Foot High Speed Tunnel to determine the effects of passive surface porosity on the subsonic vortex flow interactions about a general research fighter configuration. Flow-through porosity was applied to the leading-edge extension, or LEX, and leading-edge flaps mounted to a 65deg cropped delta wing model as a potential vortex flow control technique at high angles of attack. All combinations of porous and nonporous LEX and flaps were investigated. Wing upper surface static pressure distributions and six-component forces and moments were obtained at a free-stream Mach number of 0.20 corresponding to a Reynolds number of 1.35(106) per foot, angles of attack up to 45deg, angles of sideslip of 0deg and +/-5deg, and leading-edge flap deflections of 0deg and 30deg.

  6. Automatic computation of Euler-marching and subsonic grids for wing-fuselage configurations

    Science.gov (United States)

    Barger, Raymond L.; Adams, Mary S.; Krishnan, Ramki R.

    1994-01-01

    Algebraic procedures are described for the automatic generation of structured, single-block flow computation grids for relatively simple configurations (wing, fuselage, and fin). For supersonic flows, a quasi two-dimensional grid for Euler-marching codes is developed, and some sample results in graphical form are included. A type of grid for subsonic flow calculation is also described. The techniques are algebraic and are based on a generalization of the method of transfinite interpolation.

  7. Utilization of simple and double control subsonic aircraft for advanced combat training of the military pilots

    Directory of Open Access Journals (Sweden)

    Ioan STEFANESCU

    2012-03-01

    Full Text Available The use of subsonic single control aircraft and especially of double–control ones, instead of supersonic combat aircraft in the military pilot training programs in the operational units, has be-come a necessity due to the economic and financial world-wide crisis which began during the 70’s-80’s, with the advent of the oil crisis, affecting many countries, which have their own Military Air Forces.

  8. Analysis of boundary conditions for SSME subsonic internal viscous flow analysis

    Science.gov (United States)

    Baker, A. J.

    1986-01-01

    A study was completed of mathematically proper boundary conditions for unique numerical solution of internal, viscous, subsonic flows in the space shuttle main engine. The study has concentrated on well posed considerations, with emphasis on computational efficiency and numerically stable boundary condition statements. The method of implementing the established boundary conditions is applicable to a wide variety of finite difference and finite element codes, as demonstrated.

  9. Effects of Surface-modification of Carbon Black on the Characteristics of Polymerized Toner

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun Ho; Kim, Dae Su [Chungbuk National University, Cheongju (Korea, Republic of)

    2013-10-15

    Carbon black was surface-modified to prepare styrene-based suspension polymerized toner with excellent carbon black dispersibility inside toner particles. Carbon black was oxidized first to introduce hydroxyl groups on the surfaces, then esterification between the hydroxyl groups and carboxyl groups of organic acids (oleic acid, palmitic acid, acrylic acid) was followed to obtain organically surface-modified carbon black. The surface-modification of carbon black was confirmed by FTIR. Apparent carbon black dispersibility in the monomer mixture of the binder resin was tested and the particle size of dispersed carbon black was measured by particle size analyzer. Optical micrographs showed that carbon black dispersibility inside toner particles was improved considerably when the carbon black surface-modified with oleic acid was used. The polymerized toner prepared with the carbon black surface-modified with oleic acid showed ideal particle size and size distribution as a toner.

  10. The characteristics of machined surface controlled by multi tip arrayed tool and high speed spindle.

    Science.gov (United States)

    Kim, Yong Woo; Choi, Soo Chang; Park, Jeong Woo; Lee, Deug Woo

    2010-07-01

    In this study, we propose one of the ultra-precision machining methods that can be adapted brittle material as well as soft material by using multi arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because particles of grinding tools are irregular size and material can be fragile. Therefore we were able to design tool paths and machine controlled pattern on surface by multi arrayed diamond tips which has uniform size made in MEMS fabrication and high speed spindle of which maximum speed is about 300,000 rpm. We defined several parameters that can have effect on machining surface. Those are multi array of diamond tips (n * n), speed of the air spindle, and feeding rate. Surface roughness and surface texture can be controlled by those parameters for micro machining.

  11. Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

    Institute of Scientific and Technical Information of China (English)

    Yong-Woo KIM; Soo-Chang CHOI; Jeung-Woo PARK; Deug-Woo LEE

    2009-01-01

    One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

  12. Surface characteristics of Ti-6Al-4V alloy by EDM with Cu-SiC composite electrode

    Science.gov (United States)

    Li, L.; Feng, L.; Bai, X.; Li, Z. Y.

    2016-12-01

    Ti-6Al-4V alloy is widely used in many industries due to its outstanding properties. However, it has poor machinability using conventional mechanical cutting process. Electrical discharge machining is an alternative competitive process to machine titanium alloy by electrical erosion. This article studies the machining characteristics of Ti-6Al-4V with Cu-SiC composite electrode. Surface topography, subsurface microstructure, energy dispersive spectroscopy analysis, and micro-hardness have been analyzed. The machined surfaces show irregular compound structures, droplets of debris, shallow craters, and micro-pores. The surfaces processed by Cu-SiC electrode have fewer number of microcracks compared with that by Cu electrode. Continuous and uniform hardened layer can be achieved by Cu-SiC electrode. The hardened layer has significantly higher hardness than the bulk material because the new phases of TiC and TiSi2 were created on the surface.

  13. Study on characteristics of double surface VOC emissions from dry flat-plate building materials

    Institute of Scientific and Technical Information of China (English)

    WANG Xinke; ZHANG Yinping; ZHAO Rongyi

    2006-01-01

    This paper sets up an analytic model of double surface emission of volatile organic compound (VOC) from dry, flat-plate building materials. Based on it, the influence of factors including air change rate, loading factor of materials in the room, mass diffusion coefficient, partition coefficient, convective mass transfer coefficient, thickness of materials, asymmetric convective flow and initial VOC concentration distribution in the building material on emission is discussed. The conditions for simplifying double surface emission into single surface emission are also discussed. The model is helpful to assess the double surface VOC emission from flat-plate building materials used in indoor furniture and space partition.

  14. Nonlinear evolution of subsonic and supersonic disturbances on a compressible free shear layer

    Science.gov (United States)

    Leib, S. J.

    1991-01-01

    The effects of a nonlinear-nonequilibrium-viscous critical layer on the spatial evolution of subsonic and supersonic instability modes on a compressible free shear layer is considered. It is shown that the instability wave amplitude is governed by an integrodifferential equation with cubic-type nonlinearity. Numerical and asymptotic solutions to this equation show that the amplitude either ends in a singularity at a finite downstream distance or reaches an equilibrium value, depending on the Prandtl number, viscosity law, viscous parameter and a real parameter which is determined by the linear inviscid stability theory. A necessary condition for the existence of the equilibrium solution is derived, and whether or not this condition is met is determined numerically for a wide range of physical parameters including both subsonic and supersonic disturbances. it is found that no equilibrium solution exists for the subsonic modes unless the temperature ratio of the low-to-high-speed streams exceeds a critical value, while equilibrium solutions for the most rapidly growing supersonic mode exist over most of the parameter range examined.

  15. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro, Serguei [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco (Chile); Valdés, Héctor, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Manéro, Marie-Hélène [Université de Toulouse (France); INPT, UPS (France); Laboratoire de Génie Chimique, 4, Allée Emile Monso, F–31030 Toulouse (France); CNRS (France); Laboratoire de Génie Chimique, F–31030 Toulouse (France); Zaror, Claudio A. [Departamento de Ingeniería Química (F. Ingeniería), Universidad de Concepción, Concepción, Correo 3, Casilla 160–C (Chile)

    2014-06-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  16. Evaluation of Surface and Near-Surface Melt Characteristics on the Greenland Ice Sheet using MODIS and QuikSCAT Data

    Science.gov (United States)

    Hall, Dorothy K.; Nghiem, Son V.; Schaaf, Crystal B.; DiGirolamo, Nicolo E.

    2009-01-01

    The Greenland Ice Sheet has been the focus of much attention recently because of increasing melt in response to regional climate warming. To improve our ability to measure surface melt, we use remote-sensing data products to study surface and near-surface melt characteristics of the Greenland Ice Sheet for the 2007 melt season when record melt extent and runoff occurred. Moderate Resolution Imaging Spectroradiometer (MODIS) daily land-surface temperature (LST), MODIS daily snow albedo, and a special diurnal melt product derived from QuikSCAT (QS) scatterometer data, are all effective in measuring the evolution of melt on the ice sheet. These daily products, produced from different parts of the electromagnetic spectrum, are sensitive to different geophysical features, though QS- and MODIS-derived melt generally show excellent correspondence when surface melt is present on the ice sheet. Values derived from the daily MODIS snow albedo product drop in response to melt, and change with apparent grain-size changes. For the 2007 melt season, the QS and MODIS LST products detect 862,769 square kilometers and 766,184 square kilometers of melt, respectively. The QS product detects about 11% greater melt extent than is detected by the MODIS LST product probably because QS is more sensitive to surface melt, and can detect subsurface melt. The consistency of the response of the different products demonstrates unequivocally that physically-meaningful melt/freeze boundaries can be detected. We have demonstrated that these products, used together, can improve the precision in mapping surface and near-surface melt extent on the Greenland Ice Sheet.

  17. Lightning and Rainfall Characteristics in Elevated vs. Surface Based Convection in the Midwest that Produce Heavy Rainfall

    Directory of Open Access Journals (Sweden)

    Joshua S. Kastman

    2017-02-01

    Full Text Available There are differences in the character of surface-based and elevated convection, and one type may pose a greater threat to life or property. The lightning and rainfall characteristics of eight elevated and eight surface-based thunderstorm cases that occurred between 2007 and 2010 over the central Continental United States were tested for statistical differences. Only events that produced heavy rain (>50.8 mm·day−1 were investigated. The nonparametric Mann–Whitney test was used to determine if the characteristics of elevated thunderstorm events were significantly different than the surface based events. Observations taken from these cases include: rainfall–lightning ratios (RLR within the heavy rain area, the extent of the heavy rainfall area, cloud-to-ground (CG lightning flashes, CG flashes·h−1, positive CG flashes, positive CG flashes·h−1, percentage of positive CG flashes within the heavy rainfall area, and maximum and mean rainfall amounts within the heavy rain area. Results show that elevated convection cases produced more rainfall, total CG lightning flashes, and positive CG lightning flashes than surface based thunderstorms. More available moisture and storm morphology explain these differences, suggesting elevated convection is a greater lightning and heavy rainfall threat than surface based convection.

  18. Effects of textural and surface characteristics of microporous activated carbons on the methane adsorption capacity at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Bastos-Neto, M. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Canabrava, D.V. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Torres, A.E.B. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, 29071 Malaga (Spain); Jimenez-Lopez, A. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia (Unidad Asociada al ICP-CSIC), Facultad de Ciencias, Universidad de Malaga, 29071 Malaga (Spain); Azevedo, D.C.S. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil)]. E-mail: diana@gpsa.ufc.br; Cavalcante, C.L. [Grupo de Pesquisas em Separacoes por Adsorcao (GPSA), Departamento de Engenharia Quimica, Universidade Federal do Ceara, Campus Universitario do Pici, Bl 709 60455-760 Fortaleza, CE (Brazil)

    2007-04-30

    The objective of this study is to relate textural and surface characteristics of selected microporous activated carbons to their methane storage capacity. In this work, a magnetic suspension balance (Rubotherm, Germany) was used to measure methane adsorption isotherms of several activated carbon samples. Textural characteristics were assessed by nitrogen adsorption on a regular surface area analyzer (Autosorb-MP, by Quantachrome, USA). N{sub 2} adsorption was analysed by conventional models (BET, DR, HK) and by Monte Carlo molecular simulations. Elemental and surface analyses were performed by X-ray photoelectronic spectroscopy (XPS) for the selected samples. A comparative analysis was then carried out with the purpose of defining some correlation among the variables under study. For the system under study, pore size distribution and micropore volume seem to be a determining factor as long as the solid surface is perfectly hydrophobic. It was concluded that the textural parameters per se do not unequivocally determine natural gas storage capacities. Surface chemistry and methane adsorption equilibria must be taken into account in the decision-making process of choosing an adsorbent for gas storage.

  19. Entropy Assessment on Direct Contact Condensation of Subsonic Steam Jets in a Water Tank through Numerical Investigation

    Directory of Open Access Journals (Sweden)

    Yu Ji

    2016-01-01

    Full Text Available The present article analyzes the dissipation characteristics of the direct contact condensation (DCC phenomenon that occurs when steam is injected into a water tank at a subsonic speed using a new modeling approach for the entropy generation over the calculation domain. The developed entropy assessment model is based on the local equilibrium hypothesis of non-equilibrium thermodynamics. The fluid flow and heat transfer processes are investigated numerically. To describe the condensation and evaporation process at the vapor-liquid interface, a phase change model originated from the kinetic theory of gas is implemented with the mixture model for multiphase flow in the computational fluid dynamics (CFD code ANSYS-FLUENT. The CFD predictions agree well with the published works, which indicates the phase change model combined with the mixture model is a promising way to simulate the DCC phenomenon. In addition, three clear stages as initial stage, developing stage and oscillatory stage are discriminated from both the thermal-hydraulic results and the entropy generation information. During different stages, different proportion of the entropy generation rate owing to heat transfer, viscous direct dissipation, turbulent dissipation and inner phase change in total entropy generation rate is estimated, which is favorable to deeper understanding the irreversibility of DCC phenomenon, designing and optimizing the equipment involved in the process.

  20. Acoustic Data Processing and Transient Signal Analysis for the Hybrid Wing Body 14- by 22-Foot Subsonic Wind Tunnel Test

    Science.gov (United States)

    Bahr, Christopher J.; Brooks, Thomas F.; Humphreys, William M.; Spalt, Taylor B.; Stead, Daniel J.

    2014-01-01

    An advanced vehicle concept, the HWB N2A-EXTE aircraft design, was tested in NASA Langley's 14- by 22-Foot Subsonic Wind Tunnel to study its acoustic characteristics for var- ious propulsion system installation and airframe con gurations. A signi cant upgrade to existing data processing systems was implemented, with a focus on portability and a re- duction in turnaround time. These requirements were met by updating codes originally written for a cluster environment and transferring them to a local workstation while en- abling GPU computing. Post-test, additional processing of the time series was required to remove transient hydrodynamic gusts from some of the microphone time series. A novel automated procedure was developed to analyze and reject contaminated blocks of data, under the assumption that the desired acoustic signal of interest was a band-limited sta- tionary random process, and of lower variance than the hydrodynamic contamination. The procedure is shown to successfully identify and remove contaminated blocks of data and retain the desired acoustic signal. Additional corrections to the data, mainly background subtraction, shear layer refraction calculations, atmospheric attenuation and microphone directivity corrections, were all necessary for initial analysis and noise assessments. These were implemented for the post-processing of spectral data, and are shown to behave as expected.

  1. Room Temperature Characteristics of Polymer-Based Low Ice Adhesion Surfaces

    Science.gov (United States)

    He, Zhiwei; Vågenes, Elisabeth T.; Delabahan, Chrisrosemarie; He, Jianying; Zhang, Zhiliang

    2017-02-01

    Ice adhesion is mainly dictated by surface properties, and water wettability is frequently correlated with ice adhesion strength. However, these established correlations are limited to high ice adhesion and become invalid when the ice adhesion strength is low. Here we carried out an experimental study to explore the relationships between low ice adhesion strength and room temperature surface properties. A variety of room temperature properties of 22 polymer-based hydrophilic and hydrophobic samples consisting of both low and high ice adhesion surfaces were analysed. The properties investigated include water adhesion force, water wettability, roughness, elastic modulus and hardness. Our results show that low ice adhesion strength does not correlate well with water contact angle and its variants, surface roughness and hardness. Low elastic modulus does not guarantee low ice adhesion, however, surfaces with low ice adhesion always show low elastic modulus. Low ice adhesion (below 60 kPa) of tested surfaces may be determinative of small water adhesion force (from 180 to 270 μN). Therefore, measurement of water adhesion force may provide an effective strategy for screening anti-icing or icephobic surfaces, and surfaces within specific values of water adhesion force will possibly lead to a low ice adhesion.

  2. 3D Interest Point Detection using Local Surface Characteristics with Application in Action Recognition

    DEFF Research Database (Denmark)

    Holte, Michael Boelstoft

    2014-01-01

    . The proposed Difference-of-Normals (DoN) 3D IP detector operates on the surface mesh, and evaluates the surface structure (curvature) locally (per vertex) in the mesh data. We present an exam- ple of application in action recognition from a sequence of 3-dimensional geometrical data, where local 3D motion de...

  3. Video system for monitoring sea-surface characteristics in coastal zone

    Science.gov (United States)

    Konstantinov, Oleg G.; Pavlov, Andrey N.

    2012-11-01

    A method of investigation sea surface roughness by analysis polarization images is suggested. Equipment and software were developed and tested at the Pacific Oceanological Institute (POI) It is shown a possibility to study surface manifestations of hydrodynamic processes in coastal zone, such as the dynamics of vortex structures, internal waves, spatio-temporal properties of surface waves by using the panoramic video system for a sea surface control and by the imaging polarimeter. Analysis of a time sequence of transformed to the plane panoramic images obtained using the system allows to estimate a velocity field of vortex structure, phase velocity of surface manifestations of internal waves, intensity and dynamics of surface films of oil pollution. It is shown an ability of sea surface reconstruction by analyzing time sequence of the imaging polarimeter pictures. The results are compared with the height difference of the floats located on the vertical guides that are in the imaging polarimeter field of view. The float heights obtained from its image coordinates. Field experiments were conducted at the POI marine station in the Japan Sea. Moreover, the developed methods and equipment may be used as a source of unique in situ information on the sea surface roughness during satellite optical and radar sensing.

  4. Extrusion Honed Surface Characteristics of Inconel 625 Fabricated By EDM for Square Shape

    Directory of Open Access Journals (Sweden)

    N.L. Murali Krishna

    2014-07-01

    Full Text Available Extrusion Honing (EH is also known as Abrasive flow machining (AFM is an effective method that is used to deburr, clean, polish, remove recast layer and micro cracks by flowing pressurized semisolid abrasive laden visco-elastic media over those surfaces. Inconel 625 is one of the most difficult-to-cut materials because of its low thermal diffusive property, high hardness and high strength at elevated temperature. In this paper, the influence of the process parameters on surface roughness is investigated on Inconel 625 material of square shape fabricated by Electric discharge machining (EDM. The processed surfaces were measured and analyzed with the help of surface roughness tester and Scanning Electron Microscope (SEM. Results show a significant improvement in surface finish and EH/AFM is capable of removing the micro cracks and recast layer.

  5. Study on Surface Energy Characteristics of Poplar and Yellow Pine Strands

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yang; WANG Siqun

    2006-01-01

    The objective of this study was to investigate the surface free energy of poplar and yellow pine strands by Wilhelmy Plate Method.The measurement items included the surface contact angle,surface free energy and change of sample weight.Thirty industrial strands were randomly collected for each condition.The samples were cut down to 25.0-26.0 mm long.7.0-8.0 mm wide.The density and thickness of each sample were also tested.The range of density was from 0.35 to 0.75 g/cm3 and the range of thickness was from 0.5 to 1.0 mm.The research result shows that there is a close relationship between the wettability,mass change and moisture content.Both the density and the thickness of the strand have a small influence on the surface contact angle and the surface free energy.

  6. A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q- stability derivatives. Appendix A: A computer program for calculating alpha- and q- stability derivatives and induced drag for thin elastic aeroplanes at subsonic and supersonic speeds

    Science.gov (United States)

    Roskam, J.; Lan, C.; Mehrotra, S.

    1972-01-01

    The computer program used to determine the rigid and elastic stability derivatives presented in the summary report is listed in this appendix along with instructions for its use, sample input data and answers. This program represents the airplane at subsonic and supersonic speeds as (a) thin surface(s) (without dihedral) composed of discrete panels of constant pressure according to the method of Woodward for the aerodynamic effects and slender beam(s) for the structural effects. Given a set of input data, the computer program calculates an aerodynamic influence coefficient matrix and a structural influence coefficient matrix.

  7. Surface characteristics and degradational history of debris aprons in the Tempe Terra/Mareotis fossae region of Mars

    Science.gov (United States)

    Chuang, Frank C.; Crown, David A.

    2005-12-01

    We have documented the surface characteristics and degradational history of a population of 65 lobate debris aprons in the Tempe Terra/Mareotis fossae region of Mars. These aprons were compared to other martian debris aprons to evaluate similarities and differences among different populations, which can provide insight into the dominant controls on apron development. Tempe/Mareotis debris aprons, found at the bases of isolated or clustered massifs, escarpments, and crater interior walls, were studied using Viking Orbiter, Mars Global Surveyor, and Mars Odyssey datasets in a GIS database. Six textures related to degradation of apron surfaces are identified in MOC images, and they are divided into two groups: an upper-surface group and a lower-surface group. Degradation occurs within an inferred smooth, upper surface mantle of ice and debris, producing a sequence of pitted, ridge and valley, and knobby textures of the upper-surface group. Where upper-surface materials have been removed, smooth and ridged textures of the lower-surface group are exposed. Degradation to various depths may expose lower-surface materials, which may consist of the main apron mass, remnants of mantling deposits, or both. A combination of geologic processes may have caused the degradation, including ice sublimation, ice melt, and eolian activity. Apron surfaces have lower maximum thermal inertias and mean surface temperatures than adjacent plains surfaces, which may be explained by the trapping of unconsolidated materials in low-lying pits and valleys formed by surface degradation or from the disruption of crusts on degraded portions of apron surfaces. One feature observed only on Tempe/Mareotis debris aprons are broad ridges, which mimic the shape of massif bases for tens of kilometers. We propose these to be constructional features that could have formed during cycles of increased debris production. Apron morphometric parameters including area, volume, slope, thickness, relief, and H

  8. Temperature Frequency Characteristics of Hexamethyldisiloxane (HMDSO) Polymer Coated Rayleigh Surface Acoustic Wave (SAW) Resonators for Gas-Phase Sensor Applications

    OpenAIRE

    Ekaterina I. Radeva; Esmeryan, Karekin D.; Avramov, Ivan D.

    2012-01-01

    Temperature induced frequency shifts may compromise the sensor response of polymer coated acoustic wave gas-phase sensors operating in environments of variable temperature. To correct the sensor data with the temperature response of the sensor the latter must be known. This study presents and discusses temperature frequency characteristics (TFCs) of solid hexamethyldisiloxane (HMDSO) polymer coated sensor resonators using the Rayleigh surface acoustic wave (RSAW) mode on ST-cut quartz. Using ...

  9. [Surface characteristics of alkali modified activated carbon and the adsorption capacity of methane].

    Science.gov (United States)

    Zhang, Meng-Zhu; Li, Lin; Liu, Jun-Xin; Sun, Yong-Jun; Li, Guo-Bin

    2013-01-01

    Coconut shell based activated carbon was modified by alkali with different concentrations. The surface structures of tested carbons were observed and analyzed by SEM and BET methods. Boehm's titration and SEM/EDS methods were applied to assay the functional groups and elements on the carbon surface. The adsorption of methane on tested carbons was investigated and adsorption behavior was described by the adsorption isotherms. Results showed that surface area and pore volume of modified carbon increased and surface oxygen groups decreased as the concentration of the alkali used increased, with no obvious change in pore size. When concentration of alkali was higher than 3.3 mol x L(-1), the specific surface area and pore volume of modified carbon was larger than that of original carbon. Methane adsorption capacity of alkali modified carbon increased 24%. Enlargement of surface area and pore volume, reduction of surface oxygen groups will benefit to enhance the methane adsorption ability on activated carbon. Adsorption behavior of methane followed the Langmuir isotherm and the adsorption coefficient was 163.7 m3 x mg(-1).

  10. Characteristics of postural sway in older adults standing on a soft surface.

    Science.gov (United States)

    Tanaka, Hideyuki; Uetake, Teruo

    2005-12-01

    Postural responses to challenging situations were studied in older adults as they stood on a foam surface. The experiment was designed to assess the relative contributions made by visual and somatosensory information to the correction of postural sway. Twenty-four subjects, aged 56-83, stood for 20 s on a 1) firm or 2) foam surface with 1) the eyes open or 2) the eyes closed. Centre-of-pressure trajectories under the subjects' feet were measured by using a force platform. A repeated-measure two-way MANCOVA (two surfaces vs. two vision conditions) showed a significant main effect for the surface, but not for the vision. No covariate effect for age was found. Anterior-posterior sway increased in the subjects who were merely standing on the foam surface independent of the vision condition. Medial-lateral sway dramatically increased if the subjects stood on the foam surface with their eyes closed, but not if they stood with their eyes open. These results indicate that older adults rely more on visual information to correct mediolateral postural sway. It appears that the deterioration in visual acuity that occurs with aging may increase the risk of sideway falls, particularly in challenging situations, e.g., when standing on irregular or soft surfaces.

  11. Gait Characteristics Associated with Trip-Induced Falls on Level and Sloped Irregular Surfaces

    Directory of Open Access Journals (Sweden)

    Andrew Merryweather

    2011-11-01

    Full Text Available Same level falls continue to contribute to an alarming number of slip/trip/fall injuries in the mining workforce. The objective of this study was to investigate how walking on different surface types and transverse slopes influences gait parameters that may be associated with a trip event. Gait analysis was performed for ten subjects on two orientations (level and sloped on smooth, hard surface (control and irregular (gravel, larger rocks surfaces. Walking on irregular surfaces significantly increased toe clearance compared to walking on the smooth surface. There was a significant (p < 0.05 decrease in cadence (steps/min, stride length (m, and speed (m/s from control to gravel to larger rocks. Significant changes in external rotation and increased knee flexion while walking on irregular surfaces were observed. Toe and heel clearance requirements increased on irregular surfaces, which may provide an explanation for trip-induced falls; however, the gait alterations observed in the experienced workers used as subjects would likely improve stability and recovery from a trip.

  12. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Directory of Open Access Journals (Sweden)

    Sakineh Arami

    2014-04-01

    Full Text Available The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP after surface treatment with lasers and airborne-particle abrasion.First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7 and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ and no treatment (controls. Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM.According to ANOVA and Tukey's test, the mean surface roughness (Ra after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers.Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  13. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Science.gov (United States)

    Arami, Sakineh; Tabatabae, Masoume Hasani; Namdar, Seyedeh Fatemeh; Chiniforush, Nasim

    2014-03-01

    The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP) after surface treatment with lasers and airborne-particle abrasion. First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7) and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ) and no treatment (controls). Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM. According to ANOVA and Tukey's test, the mean surface roughness (Ra) after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers. Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  14. A potential-flow/boundary-layer method for calculating subsonic and transonic airfoil flow with trailing-edge separation

    Science.gov (United States)

    Barnwell, R. W.

    1981-01-01

    The development of a potential-flow/boundary-layer method for calculating subsonic and transonic turbulent flow past airfoils with trailing-edge separation is reported. A moment-of-momentum integral boundary-layer method is used which employs the law-of-the-wall/law-of-the-wake velocity profile and a two-layer eddy-viscosity model and ignores the laminar sublayer. All integrals across the boundary layer are obtained in closed form. Separation is assumed to occur when the shearing-stress velocity vanishes. A closed-form solution is derived for separated-flow regions where the shearing stress is negligible. In the potential-flow method, the exact form of the airfoil boundary condition is used, but it is applied at the chord line rather than the airfoil surface. This allows the accurate computation of flow about airfoils at large angles of attack but permits the use of body-oriented Cartesian computational grids. The governing equation for the perturbation velocity potential contains several terms in addition to the classical small-disturbance terms.

  15. Asymmetric spline surfaces - Characteristics and applications. [in high quality optical systems design

    Science.gov (United States)

    Stacy, J. E.

    1984-01-01

    Asymmetric spline surfaces appear useful for the design of high-quality general optical systems (systems without symmetries). A spline influence function defined as the actual surface resulting from a simple perturbation in the spline definition array shows that a subarea is independent of others four or more points away. Optimization methods presented in this paper are used to vary a reflective spline surface near the focal plane of a decentered Schmidt-Cassegrain to reduce rms spot radii by a factor of 3 across the field.

  16. Surface characteristics of modified carbon nanotubes and its application in lead adsorption from aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Carbon nanotubes (CNT) were modified by nitric acid oxidation. Infrared spectroscopy (IR) demonstrated that hydroxyl (-OH) and carbonyl (-C== O) functional groups were introduced to the surface of modified CNT. Micrometrics ASAP 2000 measurement showed that the surface area of modified CNT was slightly increased. Furthermore, the Pb2+ adsorption behavior on the surface of modified CNT has been investigated. The results indicate that the modified CNT has an exceptional adsorption capability for Pb2+ removal. The adsorption isotherms are well described by the Langmuir equation under test temperatures and the kinetics level is three.

  17. Probing characteristics of collagen molecules on various surfaces via atomic force microscopy

    Science.gov (United States)

    Su, Hao-Wei; Ho, Mon-Shu; Cheng, Chao-Min

    2012-06-01

    We examine, herein, specific dynamic responses of collagen molecules (i.e., observations of self-assembly and nanometric adhesion force measurements of type-I collagen molecules) as they interact with either a hydrophobic or a hydrophilic surface at two distinct temperatures, using a liquid-type atomic force microscope. We conclude that, regardless of surface hydrophobicity/hydrophilicity, assembled microfibrils eventually distribute homogeneously in accordance with changes in surface-related mechanical properties of collagen molecules at different self-assembly stages.

  18. Temporal characteristics of surface-acoustic-wave-driven luminescence from a lateral p-n junction

    Science.gov (United States)

    Gell, J. R.; Ward, M. B.; Shields, A. J.; Atkinson, P.; Bremner, S. P.; Anderson, D.; Kataoka, M.; Barnes, C. H. W.; Jones, G. A. C.; Ritchie, D. A.

    2007-07-01

    Short radio frequency pulses were used to study the surface-acoustic-wave-driven light emission from a molecular beam epitaxy regrown GaAs /AlGaAs lateral p-n junction. The luminescence provides a fast probe of the signals arriving at the junction allowing the authors to temporally separate the effect of the surface-acoustic-wave from pickup of the free space electromagnetic wave. Oscillations in the light intensity are resolved at the resonant frequency of the transducer, suggesting that the surface-acoustic-wave is transporting electrons across the junction in packets.

  19. Electron field emission characteristics of different surface morphologies of ZnO nanostructures coated on carbon nanotubes.

    Science.gov (United States)

    Li, Kuan-Wei; Lian, Huan-Bin; Cai, Jhen-Hong; Wang, Yao-Te; Lee, Kuei-Yi

    2011-12-01

    The optimal carbon nanotube (CNT) bundles with a hexagonal arrangement were synthesized using thermal chemical vapor deposition (TCVD). To enhance the electron field emission characteristics of the pristine CNTs, the zinc oxide (ZnO) nanostructures coated on CNT bundles using another TCVD technique. Transmission electron microscopy (TEM) images showed that the ZnO nanostructures were grown onto the CNT surface uniformly, and the surface morphology of ZnO nanostructures varied with the distance between the CNT bundle and the zinc acetate. The results of field emissions showed that the ZnO nanostructures grown onto the CNTs could improve the electron field emission characteristics. The enhancement of field emission characteristics was attributed to the increase of emission sites formed by the nanostructures of ZnO grown onto the CNT surface, and each ZnO nanostructure could be regarded as an individual field emission site. In addition, ZnO-coated CNT bundles exhibited a good emission uniformity and stable current density. These results demonstrated that ZnO-coated CNTs is a promising field emitter material.

  20. Influence of Gate Dielectric and Its Surface Treatment on Electrical Characteristics of Solution-Processed ZnO Transistors.

    Science.gov (United States)

    Song, Dong-Seok; Kim, Jae-Hyun; Jung, Ji-Hoon; Bae, Jin-Hyuk; Zhang, Xue; Park, Ji-Ho; Park, Jaehoon

    2016-02-01

    We report how interface treatments affect electrical performance, including subthreshold characteristics, in solution-processed transparent metal oxide thin-film transistors (TFTs) with SiO2 and SiNx gate dielectrics. Ultra-violet (UV) ozone treatment and O2 plasma treatment are carried out as a surface treatment of the interface between a spin-coated zinc oxide (ZnO) layer and a gate dielectric. With the SiO2 dielectric, UV ozone treatment dominantly affects subthreshold characteristics, while O2 plasma treatment produces enhanced mobility and lower threshold voltage shift. With the SiNx dielectric, every electrical parameter including mobility, threshold voltage shift, and subthreshold characteristics is enhanced by 02 plasma treatment. Our experimental results demonstrate that interface engineering treatments variously influence the electrical performance in solution-processed ZnO TFTs.

  1. Metrological characteristics of the flat voltammetric electrode in time domain with a reversible electrochemical reaction running on the surface

    Science.gov (United States)

    Suchocki, Krzysztof

    2016-11-01

    The study deals with metrological characteristics of the flat voltammetric electrode used for determination of ions concentration by the DC voltammetric method, where a reversible reaction of electrochemical oxidation/reduction takes place on the surface. The analysis shows that such voltammetric electrode acts as a transducer of the first order, where the input signal is a concentration of marked ions in tested solution and the output signal is the current associated with a reversible reaction of oxidation / reduction. Metrological characteristics of such electrode in the time domain are determined by its sensitivity and time constant. The values of these parameters are defined by measurements of characteristics of the voltammetric electrode, polarization voltage and marked ions. To determine the effect of a particular volume of each of these parameters several numerical simulations are presented.

  2. Solubility and Surface Adsorption Characteristics of Metal Oxides to High Temperature

    Energy Technology Data Exchange (ETDEWEB)

    D.J. Wesolowski; M.L. Machesky; S.E. Ziemniak; C. Xiao; D.A. Palmer; L.M. Anovitz; P. Benezeth

    2001-05-04

    The interaction of high temperature aqueous solutions with mineral surfaces plays a key role in many aspects of fossil, geothermal and nuclear energy production. This is an area of study in which the subsurface geochemical processes that determine brine composition, porosity and permeability changes, reservoir integrity, and fluid flow rates overlap with the industrial processes associated with corrosion of metal parts and deposition of solids in pipes and on heat exchanger surfaces. The sorption of ions on mineral surfaces is also of great interest in both the subsurface and ''above ground'' regimes of power production, playing a key role in subsurface migration of contaminants (nuclear waste disposal, geothermal brine re-injection, etc.) and in plant operations (corrosion mitigation, migration of radioactive metals from reactor core to heat exchanger, etc.). In this paper, results of the solubility and surface chemistry of metal oxides relevant to both regimes are summarized.

  3. Microimpact phenomena on Australasian microtektites: Implications for ejecta plume characteristics and lunar surface processes

    Digital Repository Service at National Institute of Oceanography (India)

    ShyamPrasad, M.; Sudhakar, M.

    and dust, craters generated by projectiles defining an oblique trajectory, high-velocity "pitless" craters, and the conventional hypervelocity craters with well-defined central pits and radial and concentric cracks-found commonly on lunar surface materials...

  4. Ni-Zr alloys: relationship between surface characteristics and electrocatalytic behavior

    Science.gov (United States)

    Angelini; Antonione; Baricco; Daolio; Fabrizio; Rosalbino

    2000-01-01

    A relationship between electrocatalytic activity for the hydrogen evolution reaction and the surface composition of the electrode was established for Ni-Zr crystalline and amorphous alloys by means of secondary ion mass spectrometry (SIMS). Electrocatalytic activity was tested by means of cathodic polarization in 1 M KOH at 25 degrees C and the resulting exchange current density has been taken as a measure of catalytic efficiency. Surface activation treatment involved chemical etching in HF solutions; the consequent morphological and compositional surface changes were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behavior of the pure elements (Ni and Zr) was also considered for comparison. All samples submitted to chemical etching in HF solutions showed an increase in electrocatalytic activity, particularly the alloy with the highest Ni content. The beneficial effect of chemical etching is due to dissolution of the zirconium oxide layer and to the formation of nanocrystalline Ni on the surfaces.

  5. Analysis of selected surface characteristics and latent heat storage for passive solar space heating

    Energy Technology Data Exchange (ETDEWEB)

    Fthenakis, V.; Leigh, R.

    1981-12-01

    Results are presented of an analysis of the value of various technical improvements in the solar collector and thermal storage subsystems of passive solar residential, agricultural, and industrial systems for two regions of the country. The evaluated improvements are: decreased emissivity and increased absorptivity of absorbing surfaces, decreased reflectivity, and decreased emissivity of glazing surface, and the substitution of sensible heat storage media with phase change materials. The value of each improvement is estimated by the additional energy savings resulting from the improvement.

  6. Evaluation of characteristics on titanium surface treatment for absorption of functional groups

    Institute of Scientific and Technical Information of China (English)

    JIN Guang-chun; PARK Rl-song; PARK Hyeoung-ho; SEO Jae-min; LEE Sook-jeong; LEE Min-ho

    2010-01-01

    Background In order to bind or fix bioactive materials directly to the surface of a Ti implant, the prior binding process of functional groups (FGs, -COOH and -OH) to the implant surface is necessary. Conventional binding processes are so high-cost and complex, so it is essential to find a simple and effective procedure for Ti-FG binding.Methods Various electrolyte compositions and electrochemical processing were adopted in this study to develop a relatively simple and effective Ti-FG binding process. The ability of Ti-FG binding and calcium (Ca)/phosphorous (P)absorption and corrosion resistance were evaluated according to various titanium surface treatment in electrolyte involving -COOH and -OH ion by using X ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FE-SEM) and potentiodynamic scan method respectively.Results In cases of -COOH, the anodic oxidation process (AN) showed an effective binding ability between -COOH and Ti surface. On the other hand, in cases of -OH, there were no significant differences in the result between the conditions used. In regard to the absorption of Ca and P on Ti surface, there was a minimal amount of Ca absorbed but no P was absorbed. The anodic oxidation series showed homogenous corrosion, whereas the electrolyte immersion (EL)series showed unstable corrosion. Although EL-OH showed a novel corrosion potential, the EL-COOH series showed good corrosion resistance over the anodic potential range.Conclusions The ability of binding between FG and the Ti surface and Ca/P absorption were strongly associated with the surface potential (ξ, potential), which was dependent on the pH of the electrolyte. Accordingly, in order to achieve the effective absorption of various FGs on the Ti surface, it is needed to develop the combination process in addition to the electric affinity, relation with the ξ, potential.

  7. Surface functional characteristics (C, O, S) of waste tire-derived carbon black before and after steam activation.

    Science.gov (United States)

    Lin, Hsun-Yu; Chen, Wei-Chin; Yuan, Chung-Shin; Hung, Chung-Hsuang

    2008-01-01

    The effects of steam activation on the surface functional characteristics of waste tire-derived carbon black were investigated. Two carbon-based materials, powdered carbon black (PCB) and PCB-derived powdered activated carbon (PCB-PAC), were selected for this study. A stainless steel tubular oven was used to activate the PCB at an activation temperature of 900 degrees C and 1 atm using steam as an activating reagent. X-ray photoelectron spectroscopy (XPS) was adopted to measure the surface composition and chemical structure of carbon surface. Various elemental spectra (C, O, and S) of each carbon sample were further deconvoluted by peak synthesis. Results showed that the surfaces of PCB and PCB-PAC consisted mainly of C-C and C-O. The PCB-PAC surface had a higher percentage of oxygenated functional groups (C=O and O-C=O) than PCB. The O1s spectra show that the oxygen detected on the PCB surface was mainly bonded to carbon (C-O), whereas the oxygen on the PCB-PAC surface could be bonded to hydrogen (O-H) and carbon (C-O). Sulfur on the surface of PCB consisted of 58.9 wt% zinc sulfide (ZnS) and 41.1 wt% S=C=S, whereas that on the surfaces of PCB-PAC consisted mainly of S=C=S. Furthermore, the increase of oxygen content from 9.6% (PCB) to 11.9% (PCB-PAC) resulted in the increase of the pH values of PCB-PAC after steam activation.

  8. Distribution and characteristics of methylmercury in surface sediment in Minamata Bay.

    Science.gov (United States)

    Matsuyama, Akito; Yano, Shinichiro; Hisano, Akihiro; Kindaichi, Michiaki; Sonoda, Ikuko; Tada, Akihide; Akagi, Hirokatsu

    2016-08-15

    This study was carried out to evaluate the present-day chemical properties of methylmercury in surface sediment in Minamata Bay where a dredging project was completed 28years ago. Present-day sediment from Minamata Bay consists of sandy silt, and the average loss-on-ignition in surface sediment was 7.0±2.3%. The average methylmercury concentrations in the upper sediment layers were significantly higher than those in the lower sediment layers. Currently, the concentrations in sediments in Minamata Bay do not exceed the Japanese regulatory standard value for mercury. The average concentration of methylmercury in Minamata Bay surface sediment was 1.74±1.0ng/g on a dry weight basis (n=107). The methylmercury concentration in Minamata Bay surface sediment was almost 16 times higher than that in surface sediment from Isahaya Bay surface sediment, which was 0.11±0.045ng/g on a dry weight basis (n=5).

  9. The Fast Simulation of Scattering Characteristics from a Simplified Time Varying Sea Surface

    Directory of Open Access Journals (Sweden)

    Yiwen Wei

    2015-01-01

    Full Text Available This paper aims at applying a simplified sea surface model into the physical optics (PO method to accelerate the scattering calculation from 1D time varying sea surface. To reduce the number of the segments and make further improvement on the efficiency of PO method, a simplified sea surface is proposed. In this simplified sea surface, the geometry of long waves is locally approximated by tilted facets that are much longer than the electromagnetic wavelength. The capillary waves are considered to be sinusoidal line superimposing on the long waves. The wavenumber of the sinusoidal waves is supposed to satisfy the resonant condition of Bragg waves which is dominant in all the scattered short wave components. Since the capillary wave is periodical within one facet, an analytical integration of the PO term can be performed. The backscattering coefficient obtained from a simplified sea surface model agrees well with that obtained from a realistic sea surface. The Doppler shifts and width also agree well with the realistic model since the capillary waves are taken into consideration. The good agreements indicate that the simplified model is reasonable and valid in predicting both the scattering coefficients and the Doppler spectra.

  10. [Temporal and Spatial Characteristics of Lake Taihu Surface Albedo and Its Impact Factors].

    Science.gov (United States)

    Cao, Chang; Li, Xu-hui; Zhang, Mi; Liu, Shou-dong; Xiao, Wei; Xiao, Qi-tao; Xu, Jia-ping

    2015-10-01

    Lake surface albedo determines energy balance of water-atmospheric interface and water physical environment. Solar elevation angle, cloudiness, wind speed, water quality and other factors can affect lake surface albedo. Using solar radiation, wind speed, and water quality data (turbidity and chlorophyll-a concentration) which were observed in four eddy covariance sites (Meiliangwan, Dapukou, Bifenggang and Xiaoleishan i. e. MLW, DPK, BFG and XLS) in Lake Taihu and clearness index (k(t)), the influence of these factors on Lake Taihu surface albedo and the reasons that led to its spatial difference were investigated. The results showed that solar elevation angle played a leading role in the diurnal and seasonal change of lake surface albedo; lake surface albedo reached two peaks in 0 BFG > DPK > MLW. XLS and BFG belonged to the higher albedo group, while DPK and MLW belonged to the lower albedo group. The different biological environments caused by aquatic macrophytes and algae resulting in the spatial variation of Lake Taihu surface albedo. The relationship between albedo and chlorophyll-a concentration was not a very sensitive factor for indicating the outbreak of algae. This study can provide theoretical reference for lake albedo parameterization.

  11. Thermal Characteristics of Air-Water Spray Impingement Cooling of Hot Metallic Surface under Controlled Parametric Conditions

    Institute of Scientific and Technical Information of China (English)

    Santosh Kumar Nayak; Purna Chandra Mishra

    2016-01-01

    Experimental results on the thermal characteristics of air-water spray impingement cooling of hot metallic surface are presented and discussed in this paper.The controlling input parameters investigated were the combined air and water pressures,plate thickness,water flow rate,nozzle height from the target surface and initial temperature of the hot surface.The effects of these input parameters on the important thermal characteristics such as heat transfer rate,heat transfer coefficient and wetting front movement were measured and examined.Hot flat plate samples of mild steel with dimension 120 mm in length,120 mm breadth and thickness of 4 mm,6 mm,and 8 mm respectively were tested.The air assisted water spray was found to be an effective cooling media and method to achieve very high heat transfer rate from the surface.Higher heat transfer rate and heat transfer coefficients were obtained for the lesser i.e,4 mm thick plates.Increase in the nozzle height reduced the heat transfer efficiency of spray cooling.At an inlet water pressure of 4 bar and air pressure of 3 bar,maximum cooling rates 670℃/s and average cooling rate of 305.23℃/s were achieved for a temperature of 850℃ of the steel plate.

  12. Evapotranspiration over a Japanese cypress forest. I. Eddy covariance fluxes and surface conductance characteristics for 3 years

    Science.gov (United States)

    Kosugi, Yoshiko; Takanashi, Satoru; Tanaka, Hiroki; Ohkubo, Shinjiro; Tani, Makoto; Yano, Masato; Katayama, Tatsuya

    2007-04-01

    SummaryEvapotranspiration above a Japanese cypress ( Chamaecyparis obtusa Sieb. et Zucc.) forest with complex topography in central Japan were observed for 3 years using the eddy covariance method. The observations describe the magnitude and seasonal and inter-annual variations in sensible and latent heat fluxes, evapotranspiration and the parameters describing bulk canopy characteristics. Average annual evapotranspiration over the period was approximately 735 mm. Despite large fluctuations in precipitation (1179-1971 mm) during the 3 years, inter-annual fluctuations in evapotranspiration were small. Midday average dry canopy surface conductance was 6.7 mm s -1 during midseason and decreased in winter. The midday average dry canopy decoupling factor ( Ω) was 0.21 during midseason and decreased in winter. This forest is characterized by relatively small values of surface conductance and decoupling factor compared to other forests. However, several other coniferous forests show smaller values. Surface conductance, and thus stomatal regulation, is important in controlling dry-canopy transpiration in this forest. Inter-annual fluctuations of bulk parameters were small; surface conductance characteristics affected by soil moisture did not vary between dry and wet years.

  13. Decontamination Characteristics of Stainless Steel Surface Contaminated with Cs{sup +} Ion by Light Ablation

    Energy Technology Data Exchange (ETDEWEB)

    Baigalmaa, Byambatseren; Won, Hui-Jun; Moon, Jei-Kwon; Jung, Chong-Hun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Hyun, Jae-Hyuk [Chungnam National University, Daejeon (Korea, Republic of)

    2008-05-15

    The characteristics of decontamination method by light ablation are the remote operation, a short application time, and the high removal efficiency. Furthermore, the generation of the secondary waste is negligible. The radioactivity of hot cells in DFDF (Dupic Fuel Development Facility) is presumed to be very high and the predominant radionuclide is Cs-137. A series of laser decontamination studies by the fabricated Qswitched Nd-YAG laser system were performed on the stainless steel specimens artificially contaminated with Cs{sup +} ion. Decontamination characteristics of the stainless steel were analyzed by SEM and EPMA.

  14. Pool boiling characteristics and critical heat flux mechanisms of microporous surfaces and enhancement through structural modification

    Science.gov (United States)

    Ha, Minseok; Graham, Samuel

    2017-08-01

    Experimental studies have shown that microporous surfaces induce one of the highest enhancements in critical heat flux (CHF) during pool boiling. However, microporous surfaces may also induce a very large surface superheat (>100 °C) which is not desirable for applications such as microelectronics cooling. While the understanding of the CHF mechanism is the key to enhancing boiling heat transfer, a comprehensive understanding is not yet available. So far, three different theories for the CHF of microporous surfaces have been suggested: viscous-capillary model, hydrodynamic instability model, and dryout of the porous coatings. In general, all three theories account for some aspects of boiling phenomena. In this study, the theories are examined through their correlations with experimental data on microporous surfaces during pool boiling using deionized (DI) water. It was found that the modulation of the vapor-jet through the pore network enables a higher CHF than that of a flat surface based on the hydrodynamic instability theory. In addition, it was found that as the heat flux increases, a vapor layer grows in the porous coatings described by a simple thermal resistance model which is responsible for the large surface superheat. Once the vapor layer grows to fill the microporous structure, transition to film boiling occurs and CHF is reached. By disrupting the formation of this vapor layer through the fabrication of channels to allow vapor escape, an enhancement in the CHF and heat transfer coefficient was observed, allowing CHF greater than 3500 kW/m2 at a superheat less than 50 °C.

  15. Effects of Leucin-Enkephalins on Surface Characteristics and Morphology of Model Membranes Composed of Raft-Forming Lipids.

    Science.gov (United States)

    Tsanova, Asya; Jordanova, A; Lalchev, Z

    2016-06-01

    During the last decades opioid peptides, like enkephalins (Tyr-Gly-Gly-Phe-Met/Leu) are subject to extensive studies due to their antinociceptive action in organism. According to the membrane catalysis theory, in order to adopt a proper conformation for binding to their receptors, opioid peptides interact with the lipid phase of the membrane receptor surrounding. With this regard, the aim of the present work was to study the effects of synthetic leucine-enkephalin and leucine-enkephalinamide on surface characteristics and morphology of lipid monolayers, composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, sphingomyelin, and cholesterol alone and with their mixtures. The lipids were chosen to represent a model of a membrane raft, since it is known that G-protein-coupled receptors, including opioid receptors, are located preferably in membrane rafts. By using Langmuir's monolayer method, the change in surface pressure of the model membranes before and after the addition of the synthetic enkephalins was studied, and the compressional moduli of the lipids and lipid-peptides monolayers were determined. In addition, by Brewster angle microscopy, the surface morphology of the lipid monolayers alone and after the injection of both enkephalins was monitored. Our results showed that both leucine-enkephalins affected the lipid monolayers surface characteristics, and led to an increase in surface density of the mixed surface lipids/enkephalins films at loose lipid packing. This effect was more pronounced for the enkephalinamide, suggesting a different mechanism of interaction for the amidated enkephalin with the lipid phase, as compared to leucine-enkephalin.

  16. Effect of passivation and surface modification on the dissolution behavior and nano-surface characteristics of Ti-6Al-4V in Hank/EDTA solution.

    Science.gov (United States)

    Lee, T M

    2006-01-01

    The aim of the present study was to investigate the effects of passivation treatment (34% nitric acid passivation, 400 ( composite function)C heated in air, and aged in 100 ( composite function)C de-ionized water) and surface modification (2 hr and 8 hr vacuum-brazed treatments) on the ion dissolution and nano-surface characteristics of Ti-6Al-4V exposed in Hank's solution with 8.0 mM ethylene diamine tetra-acetic acid (EDTA) at 37 ( composite function)C. The results indicated that the original nano-surface characteristics and microstructure would influence the ion dissolution but not change the capability of the Ca and P adsorption upon immersion. Of the three passivated treatments, 400 ( composite function)C thermal treatment for both 2 hr brazed Ti-6Al-4V (B2) and 8 hr brazed Ti-6Al-4V (B8) exhibits a substantial reduction in the constituent release compared to the acid passivated and water aged treatment, because the thicker thickness and rutile structure of surface oxide could provide the better dissolution resistance for 400 ( composite function)C-treated specimens. Moreover, the reduced Ti(2)Cu and increased alpha -titanium structure in B8 specimen could also improve ion dissolution resistance in comparison with B2 specimen. After soaking in Hank/EDTA solution, the adsorbed non-elemental Ca and P for all groups of specimens were observed by XPS analysis, and the AES depth-profile analysis indicate that the oxide films of all groups of specimens thicken with the longer immersion periods. The increasing oxide thickness may be the factor in the improved dissolution resistance at the longer immersion periods. The relation between lower dissolution rate and thicker oxide films were observed for all groups of specimens. The results suggest that the dissolution kinetics was governed by the metal ion transport through the oxide film in this study.

  17. Formation of nanostructure on hair surface: its characteristic optical properties and application to hair care products.

    Science.gov (United States)

    Watanabe, Shunsuke; Sato, Hirayuki; Shibuichi, Satoshi; Okamoto, Masayuki; Inoue, Shigeto; Satoh, Naoki

    2007-01-01

    Uneven structures on hair fiber surface, such as lift up of cuticle or build up of hair spray ingredients, generally cause a diffuse reflection which results in a dull and unhealthy appearance. However, in the case of finer structure than wavelength of visible light, the optical properties change significantly. An application of the phenomenon to hair care products is reported in this paper. Formation of the fine structure on hair surface was achieved by only a shampoo and rinse-off conditioner system including amino-silicone. Chroma enhancement of hair and light introduction into hair fibers were observed simultaneously with formation of the fine structure on the hair surface. The light introduction phenomenon is understood in terms of "Effective Medium Approximation" (EMA). The simulation study based on EMA indicates that a very low refractive index surface is expected to be realized, which well explains the optical experimental results. When the shampoo and conditioner system developed to form the structure on fiber surface was applied to dyed hair, enhancement and long-lasting of vivid appearance was confirmed in spite of dye elution.

  18. Influence of cell surface characteristics on adhesion of Saccharomyces cerevisiae to the biomaterial hydroxylapatite.

    Science.gov (United States)

    White, Jane S; Walker, Graeme M

    2011-02-01

    The influence of the physicochemical properties of biomaterials on microbial cell adhesion is well known, with the extent of adhesion depending on hydrophobicity, surface charge, specific functional groups and acid-base properties. Regarding yeasts, the effect of cell surfaces is often overlooked, despite the fact that generalisations may not be made between closely related strains. The current investigation compared adhesion of three industrially relevant strains of Saccharomyces cerevisiae (M-type, NCYC 1681 and ALY, strains used in production of Scotch whisky, ale and lager, respectively) to the biomaterial hydroxylapatite (HAP). Adhesion of the whisky yeast was greatest, followed by the ale strain, while adhesion of the lager strain was approximately 10-times less. According to microbial adhesion to solvents (MATS) analysis, the ale strain was hydrophobic while the whisky and lager strains were moderately hydrophilic. This contrasted with analyses of water contact angles where all strains were characterised as hydrophilic. All yeast strains were electron donating, with low electron accepting potential, as indicated by both surface energy and MATS analysis. Overall, there was a linear correlation between adhesion to HAP and the overall surface free energy of the yeasts. This is the first time that the relationship between yeast cell surface energy and adherence to a biomaterial has been described.

  19. Soil, Groundwater, Surface Water, and Sediments of Kennedy Space Center, Florida: Background Chemical and Physical Characteristics

    Science.gov (United States)

    Shmalzer, Paul A.; Hensley, Melissa A.; Mota, Mario; Hall, Carlton R.; Dunlevy, Colleen A.

    2000-01-01

    This study documented background chemical composition of soils, groundwater, surface; water, and sediments of Kennedy Space Center. Two hundred soil samples were collected, 20 each in 10 soil classes. Fifty-one groundwater wells were installed in 4 subaquifers of the Surficial Aquifer and sampled; there were 24 shallow, 16 intermediate, and 11 deep wells. Forty surface water and sediment samples were collected in major watershed basins. All samples were away from sites of known contamination. Samples were analyzed for organochlorine pesticides, aroclors, chlorinated herbicides, polycyclic aromatic hydrocarbons (PAH), total metals, and other parameters. All aroclors (6) were below detection in all media. Some organochlorine pesticides were detected at very low frequencies in soil, sediment, and surface water. Chlorinated herbicides were detected at very low frequencies in soil and sediments. PAH occurred in low frequencies in soiL, shallow groundwater, surface water, and sediments. Concentrations of some metals differed among soil classes, with subaquifers and depths, and among watershed basins for surface water but not sediments. Most of the variation in metal concentrations was natural, but agriculture had increased Cr, Cu, Mn, and Zn.

  20. Synthesis and Characteristics of Mesoporous Silica Aerogels with One-step Solvent Exchange/Surface Modification

    Institute of Scientific and Technical Information of China (English)

    WANG Lijiu; ZHAO Shanyu

    2009-01-01

    The synthesis procedures and physical properties of the ambient dried hydrophobic silica aerogels by using different contents of ethanol(EtOH)/trimethylchlorosilane(TMCS)/n-Hexane as surface modification agent were investigated.One-step solvent exchange and surface modification were simultaneously progressed by immersing silica hydrogels in EtOH/TMCS/n-Hexane solution.It is found that microstructures as well as properties of silica aerogels like porosity,specific density and specific surface area are affected by the contents of surface modification agent in the sol from the re-sults of SEM,TEM morphology,FT-IR chemical structure,BET surface area and BJH pore size analyses.The volume of TMCS is of 10%and 20%of hydrogels,and the final product is hydrophilic xerogels.When TMCS's percent(v/v)is elevated to 75%-100%,hydrophobic silica aerogels with good performance are synthesized,the porosities of aerogels are in the range of 93.5%-95.8%and the av-erage pore size diameter is less than 20 nm.

  1. Surface characteristics of hydroxyapatite films deposited on anodized titanium by an electrochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang [Research Institute, Kuwotech, 970–88, Wolchul-dong, Buk-ku, Gwangju (Korea, Republic of); Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of); Jeong, Yong-Hoon; Brantley, William A. [Division of Restorative, Prosthetic and Primary Care Dentistry, College of Dentistry, The Ohio State, University, Columbus, OH (United States); Choe, Han-Cheol, E-mail: hcchoe@chosun.ac.kr [Department of Dental Materials and Research Center of Nano-Interface Activation for Biomaterials, School of Dentistry, Chosun University, Gwangju (Korea, Republic of)

    2013-11-01

    The biocompatibility of anodized titanium (Ti) was improved by an electrochemically deposited calcium phosphate (CaP) layer. The CaP layer was grown on the anodized Ti surface in modified simulated body fluid (M-SBF) at 85 °C. The phases and morphologies for the CaP layers were influenced by the electrolyte concentration. Nano flake-like precipitates that formed under low M-SBF concentrations were identified as hydroxyapatite (HAp) crystals orientated in the c-axis direction. In high M-SBF concentrations, the CaP layer formed micro plate-like precipitates on anodized Ti, and micropores were covered with HAp. Proliferation of murine preosteoblast cell (MC3T3-E1) on the HAp/anodized Ti surfaces was significantly higher than for untreated Ti and anodized Ti surfaces. - Highlights: • CaP layers were grown on anodized Ti surfaces by an electrochemical deposition process. • Phases and morphologies of layers were influenced by the electrolyte concentration. • Superior cell proliferation was observed on hydroxyapatite-coated anodized surfaces.

  2. Age related effects of transitional floor surfaces and obstruction of view on gait characteristics related to slips and falls.

    Science.gov (United States)

    Bunterngchit, Yuthachai; Lockhart, Thurmon; Woldstad, Jeffrey C; Smith, James L

    2000-02-01

    A laboratory study was conducted to examine gait changes between younger and older subjects as they walked across different floor surfaces. Twenty subjects participated in the experiment (five each of older and younger males and females). For half of the trials, subjects carried light loads that blocked their view of the floor surface immediately in front of them. Subjects walked on slippery (soapy water on vinyl) and stable (outdoor carpet) floor surfaces, as well as transitioning from one surface to another. Responses studied included: required coefficient of friction (RCOF), stride length (SL), and minimum toe clearance (MTC). Significant effects were found for the floor surface, load versus no load condition, and some interactions involving age (older versus younger subjects). Not all expected differences due to age were found in this experiment. The lack of significant differences between younger and older subjects could be due to the older subjects that participated in the experiment. They were volunteers at a local medical center, were in good physical shape, and were probably not typical of the population of people over 65 years of age. RELEVANCE TO INDUSTRY: Slips and falls in industry are costly safety issues in terms of human suffering as well as financial compensation. In many facilities and at home, people make transitions from one floor surface to another many times each day, while carrying loads or just walking. A better understanding of characteristics of people as they walk on slippery floor surfaces and the changes that might occur with age, will allow engineers to design better floor surfaces to reduce the incidence of slips and falls.

  3. Surface Characteristics of Rare Earth Treated Carbon Fibers and Interfacial Properties of Composites

    Institute of Scientific and Technical Information of China (English)

    Xu Zhiwei; Huang Yudong; Song Yuanjun; Zhang Chunhua; Liu Li

    2007-01-01

    Effect of rare earth treatment on surface physicochemical properties of carbon fibers and interfacial properties of carbon fiber/epoxy composites was investigated, and the interfacial adhesion mechanism of treated carbon fiber/epoxy composite was analyzed. It was found that rare earth treatment led to an increase of fiber surface roughness, improvement of oxygen-containing groups, and introduction of rare earth element on the carbon fiber surface. As a result, coordination linkages between fibers and rare earth, and between rare earth and resin matrix were formed separately, thereby the interlaminar shear strength (ILSS) of composites increased, which indicated the improvement of the interfacial adhesion between fibers and matrix resin resulting from the increase of carboxyl and carbonyl.

  4. Surface-modified micrometre nickel hollow spheres and their microwave characteristics

    Science.gov (United States)

    Deng, Yida; Shen, Bin; Liu, Lei; Wu, Yating; Hu, Wenbin

    2009-08-01

    To improve the magnetic properties, nickel hollow spheres (NHSs) were surface-modified with a cellular Co structure by a facile electroless cobalt plating route. The microstructures and properties of the modified NHSs were characterized by field emission scanning electron microscopy, x-ray diffraction, Brunauer-Emmett-Teller specific surface area and a vibrating sample magnetometer. Microwave properties were evaluated by mixing NHSs with polyvinyl butyral as coaxial samples. The SEM images showed that the NHSs were coated by the Co cellular films, which not only increased the specific surface area but also enhanced the coercivity and magnetization. Also, the modified NHSs composites presented low RL min values below -30 dB at thicknesses between 1.0 and 2.0 mm, and exhibited a broad absorption bandwidth ΔW at 'thin' thickness.

  5. Surface-modified micrometre nickel hollow spheres and their microwave characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Deng Yida; Shen Bin; Liu Lei; Wu Yating; Hu Wenbin, E-mail: wbhu@263.ne [State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2009-08-07

    To improve the magnetic properties, nickel hollow spheres (NHSs) were surface-modified with a cellular Co structure by a facile electroless cobalt plating route. The microstructures and properties of the modified NHSs were characterized by field emission scanning electron microscopy, x-ray diffraction, Brunauer-Emmett-Teller specific surface area and a vibrating sample magnetometer. Microwave properties were evaluated by mixing NHSs with polyvinyl butyral as coaxial samples. The SEM images showed that the NHSs were coated by the Co cellular films, which not only increased the specific surface area but also enhanced the coercivity and magnetization. Also, the modified NHSs composites presented low R{sub Lmin} values below -30 dB at thicknesses between 1.0 and 2.0 mm, and exhibited a broad absorption bandwidth {Delta}W at 'thin' thickness.

  6. Optimizing surface characteristics for cell adhesion and proliferation on titanium plasma spray coatings on polyetheretherketone.

    Science.gov (United States)

    Yoon, Byung Jo Victor; Xavier, Fred; Walker, Brendon R; Grinberg, Samuel; Cammisa, Frank P; Abjornson, Celeste

    2016-10-01

    Titanium plasma spray coating on polyetheretherketone (PEEK) is a recent innovation to interbody spacer technology. The inherent hydrophobic properties of standard, uncoated PEEK implants can hamper cell attachment and bone healing during fusion. The addition of titanium coating not only offers initial stability due to increased surface roughness but also long-term stability due to bony ongrowth created from osteoconductive microenvironment on the device surface. The previously established hydrophilic and osteophilic properties of commercially pure titanium (CPTi) can potentially provide an ideal environment promoting cell attachment and bony ongrowth when applied at the end plate level of the fusion site. Because the surface material composition and topography is what seems to directly affect cell adhesion, it is important to determine the ideal titanium coating for the highest effectiveness. The purpose of the study is to determine whether there is an optimal surface roughness for the titanium coatings and whether different polishing methods have a greater effect than roughness or topography in mediating cell adhesion to the surface. The study was divided into two phases. In Phase 1, the effects of varying surface roughnesses on identical polishing method were compared. In Phase 2, the effect of varying polishing methods was compared on identical surface roughnesses. Coating thickness, porosity, and surface roughness were characterized using an optical microscope as per ASTM F 1854 standards. For both phases, PEEK coupons with plasma-sprayed CPTi were used, and human mesenchymal stem cells (hMSCs) at an initial density of 25,000 cells/cm(2) were seeded and cultured for 24 hours before fixation in 10% formalin. The cultured hMSCs were visualized by 4',6-diamidino-2-phenylindole (DAPI) staining, a fluorescent stain that binds to the DNA of living cells. Samples were imaged using an environmental scanning electron microscope (eSEM) (Carl Zeiss Microscopy

  7. Overview of the Characteristics of Micro- and Nano-Structured Surface Plasmon Resonance Sensors

    Directory of Open Access Journals (Sweden)

    Byoungho Lee

    2011-01-01

    Full Text Available The performance of bio-chemical sensing devices has been greatly improved by the development of surface plasmon resonance (SPR based sensors. Advancements in micro- and nano-fabrication technologies have led to a variety of structures in SPR sensing systems being proposed. In this review, SPR sensors (from typical Kretschmann prism configurations to fiber sensor schemes with micro- or nano-structures for local light field enhancement, extraordinary optical transmission, interference of surface plasmon waves, plasmonic cavities, etc. are discussed. We summarize and compare their performances and present guidelines for the design of SPR sensors.

  8. Drag characteristics of power law fluids on an upstream moving surface

    Institute of Scientific and Technical Information of China (English)

    Liancun Zheng; Xinxin Zhang; Jicheng He

    2005-01-01

    The specific problem to be considered here concerns the boundary layer problem of a non-Newtonian fluid on a flat plate in length, whose surface has a constant velocity opposite in the direction to that of the mainstream with Uw >> U∞, or alternatively when the plate surface velocity is kept fixed but the stream speed is reduced to zero. A theoretical analysis for a boundary layer flow is made and the self-similar equation is determined. Solutions are presented numerically for special power index and the associated transfer behavior is discussed.

  9. Characteristics and Corrosion Behavior of Pure Titanium Subjected to Surface Mechanical Attrition

    Science.gov (United States)

    Fu, Tianlin; Wang, Xiao; Liu, Jianxiong; Li, Li; Yu, Xiaohua; Zhan, Zhaolin

    2017-08-01

    A stable passive film exhibiting good corrosion resistance in a 3.5 wt.% NaCl solution was formed on the surface of pure titanium (Ti) subjected to a surface mechanical attrition treatment (SMAT). The corrosion potential (-0.21 V) of the film was significantly higher than that (-0.92 V) of the untreated sample. Moreover, the corrosion current density was an order of magnitude lower than that of the untreated sample. SMAT resulted in a decrease in the vacancy condensation in the TiO2 film, thereby inhibiting the invasion and diffusion of Cl- in the film.

  10. Establishing Consensus Turbulence Statistics for Hot Subsonic Jets

    Science.gov (United States)

    Bridges, James; Werner, Mark P.

    2010-01-01

    Many tasks in fluids engineering require knowledge of the turbulence in jets. There is a strong, although fragmented, literature base for low order statistics, such as jet spread and other meanvelocity field characteristics. Some sources, particularly for low speed cold jets, also provide turbulence intensities that are required for validating Reynolds-averaged Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) codes. There are far fewer sources for jet spectra and for space-time correlations of turbulent velocity required for aeroacoustics applications, although there have been many singular publications with various unique statistics, such as Proper Orthogonal Decomposition, designed to uncover an underlying low-order dynamical description of turbulent jet flow. As the complexity of the statistic increases, the number of flows for which the data has been categorized and assembled decreases, making it difficult to systematically validate prediction codes that require high-level statistics over a broad range of jet flow conditions. For several years, researchers at NASA have worked on developing and validating jet noise prediction codes. One such class of codes, loosely called CFD-based or statistical methods, uses RANS CFD to predict jet mean and turbulent intensities in velocity and temperature. These flow quantities serve as the input to the acoustic source models and flow-sound interaction calculations that yield predictions of far-field jet noise. To develop this capability, a catalog of turbulent jet flows has been created with statistics ranging from mean velocity to space-time correlations of Reynolds stresses. The present document aims to document this catalog and to assess the accuracies of the data, e.g. establish uncertainties for the data. This paper covers the following five tasks: Document acquisition and processing procedures used to create the particle image velocimetry (PIV) datasets. Compare PIV data with hotwire and laser Doppler

  11. The NASA Subsonic Jet Particle Image Velocimetry (PIV) Dataset

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2011-01-01

    Many tasks in fluids engineering require prediction of turbulence of jet flows. The present document documents the single-point statistics of velocity, mean and variance, of cold and hot jet flows. The jet velocities ranged from 0.5 to 1.4 times the ambient speed of sound, and temperatures ranged from unheated to static temperature ratio 2.7. Further, the report assesses the accuracies of the data, e.g., establish uncertainties for the data. This paper covers the following five tasks: (1) Document acquisition and processing procedures used to create the particle image velocimetry (PIV) datasets. (2) Compare PIV data with hotwire and laser Doppler velocimetry (LDV) data published in the open literature. (3) Compare different datasets acquired at the same flow conditions in multiple tests to establish uncertainties. (4) Create a consensus dataset for a range of hot jet flows, including uncertainty bands. (5) Analyze this consensus dataset for self-consistency and compare jet characteristics to those of the open literature. The final objective was fulfilled by using the potential core length and the spread rate of the half-velocity radius to collapse of the mean and turbulent velocity fields over the first 20 jet diameters.

  12. Post-buckled precompressed (PBP) subsonic micro flight control actuators and surfaces

    NARCIS (Netherlands)

    Barrett, R.; Vos, R.; De Breuker, R.

    2007-01-01

    This paper describes a new class of flight control actuators using Post-Buckled Precompressed (PBP) piezoelectric elements to provide much improved actuator performance. These PBP actuator elements are modeled using basic large deflection Euler-beam estimations accounting for laminated plate effects

  13. Extraction of quantitative surface characteristics from AIRSAR data for Death Valley, California

    Science.gov (United States)

    Kierein-Young, K. S.; Kruse, F. A.

    1992-01-01

    Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were collected for the Geologic Remote Sensing Field Experiment (GRSFE) over Death Valley, California, USA, in Sep. 1989. AIRSAR is a four-look, quad-polarization, three frequency instrument. It collects measurements at C-band (5.66 cm), L-band (23.98 cm), and P-band (68.13 cm), and has a GIFOV of 10 meters and a swath width of 12 kilometers. Because the radar measures at three wavelengths, different scales of surface roughness are measured. Also, dielectric constants can be calculated from the data. The AIRSAR data were calibrated using in-scene trihedral corner reflectors to remove cross-talk; and to calibrate the phase, amplitude, and co-channel gain imbalance. The calibration allows for the extraction of accurate values of rms surface roughness, dielectric constants, sigma(sub 0) backscatter, and polarization information. The radar data sets allow quantitative characterization of small scale surface structure of geologic units, providing information about the physical and chemical processes that control the surface morphology. Combining the quantitative information extracted from the radar data with other remotely sensed data sets allows discrimination, identification and mapping of geologic units that may be difficult to discern using conventional techniques.

  14. Ab initio Investigation of Adsorption Characteristics of Bisphosphonates on Hydroxyapatite (001) Surface

    CERN Document Server

    Ri, Mun-Hyok; Yu, Chol-Jun; Kim, Song-Un

    2016-01-01

    The structures of some bisphosphonates (clodronate, etidronate, pamidronate, alendronate, risedronate, zoledronate, minodronate) were obtained and analyzed, and their adsorption energies onto hydroxyapatite (001) surface were compared to find out ranking order of binding affinity, which shows that the adsorption energy is the largest for pamidronate, followed by alendronate, zoledronate, clodronate, ibandronate, the lowest for minodronate and etidronate.

  15. Effects of surface characteristics on the plantar shape of feet and subjects' perceived sensations.

    Science.gov (United States)

    Witana, Channa P; Goonetilleke, Ravindra S; Xiong, Shuping; Au, Emily Y L

    2009-03-01

    Orthotics and other types of shoe inserts are primarily designed to reduce injury and improve comfort. The interaction between the plantar surface of the foot and the load-bearing surface contributes to foot and surface deformations and hence to perceived comfort, discomfort or pain. The plantar shapes of 16 participants' feet were captured when standing on three support surfaces that had different cushioning properties in the mid-foot region. Foot shape deformations were quantified using 3D laser scans. A questionnaire was used to evaluate the participant's perceptions of perceived shape and perceived feeling. The results showed that the structure in the mid-foot could change shape, independent of the rear-foot and forefoot regions. Participants were capable of identifying the shape changes with distinct preferences towards certain shapes. The cushioning properties of the mid-foot materials also have a direct influence on perceived feelings. This research has strong implications for the design and material selection of orthotics, insoles and footwear.

  16. Surface layer temperature inversion in the Bay of Bengal: Main characteristics and related mechanisms

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Suresh, I.; Gautham, S.; PrasannaKumar, S.; Lengaigne, M.; Rao, R.R.; Neetu, S.; Hegde, A.

    amplitude (~0.26°C). Heat budget analysis of the mixed layer reveals that the net surface heat loss is the most dominant process controlling the formation and maintenance of SLTI. However, there are instances of episodic advection of cold, low-saline waters...

  17. The Characteristics of Near-surface Velocity During the Upwelling Season on the Northern Portugal Shelf

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Observations made on the northern Portugal mid-shelf between May 13 and June 15, 2002 were used to characterise the near-surface velocity during one upwelling season. It was found that in the surface mixed layer, the 'tidal current' was diurnal, but the tidal elevation was semi-diurnal. Both the residual current and the major axes of all tidal constituents were nearly perpendicular to the isobaths and the tidal current ellipses rotated clockwise; the major axis of the major tidal ellipse was about 3 cm s-1. The extremely strong diurnal current in the surface layer was probably due to diurnal heating, cooling, and wind mixing that induced diurnal oscillations, including the diurnal oscillation of wind stress. This is a case different from the results measured in the other layers in this area. The near-inertial spectral peaks occurred with periods ranging from 1 047 min to 1 170 min, the longest periods being observed in deeper layers, and the shortest in the surface layer. Weak inertial events appeared during strong upwelling events, while strong inertial events appeared during downwelling or weak subinertial events. The near-inertial currents were out of phase between 5 m and 35 m layers for almost the entire measurement period, but such relationship was very weak during periods of irregular weak wind. Strong persistent southerly wind blew from May 12 to 17 and forced a significant water transport onshore and established a strong barotropic poleward jet with a surface speed exceeding 20 cm s-1. The subinertial current was related to wind variation, especially in the middle layers of 15 m and 35 m, the maximum correlation between alongshore current and alongshore wind was about 0.5 at the 5 m layer and 0.8 at the 35 m layer. The alongshore current reacted more rapidly than the cross-shore current. The strongest correlation was found at a time lag of 20 h in the upper layer and of 30 h in the deeper layer. The wind-driven surface velocity obtained from the PWP model

  18. Creation of coating surfaces possessing superhydrophobic and superoleophobic characteristics with fluoroalkyl end-capped vinyltrimethoxysilane oligomeric nanocomposites having biphenylene segments.

    Science.gov (United States)

    Goto, Yuki; Takashima, Hiroki; Takishita, Katsuhisa; Sawada, Hideo

    2011-10-15

    Fluoroalkyl end-capped vinyltrimethoxysilane oligomeric nanocomposites having biphenylene units [R(F)-(VM-SiO(2))(n)-R(F)/Ar-SiO(2)] were prepared by the sol-gel reaction of the corresponding oligomer [R(F)-(VM)(n)-R(F)] with 4,4'-bis(triethoxysilyl)-1,1'-biphenyl [Ar-Si(OEt)(3)] under alkaline conditions. R(F)-(VM-SiO(2))(n)-R(F)/Ar-SiO(2) nanocomposites were applied to the surface modification of PMMA to exhibit not only a good oleophobicity imparted by fluorine but also a fluorescent emission ability on the surface. Methanol sol solutions of R(F)-(VM-SiO(2))(n)-R(F)/Ar-SiO(2) nanocomposites were effective for the surface modification of glass through the dipping technique to exhibit good oleophobicity with superhydrophobicity on the modified glass surface. On the other hand, 1,2-dichloroethane sol solutions enabled R(F)-(VM-SiO(2))(n)-R(F)/Ar-SiO(2) nanocomposites to exhibit both superhydrophobic and superoleophobic characteristics on the modified surface through dipping the glass in these sol solutions.

  19. Surface layer temperature inversion in the Bay of Bengal: Main characteristics and related mechanisms

    Science.gov (United States)

    Thadathil, Pankajakshan; Suresh, I.; Gautham, S.; Prasanna Kumar, S.; Lengaigne, Matthieu; Rao, R. R.; Neetu, S.; Hegde, Akshay

    2016-08-01

    Surface layer temperature inversion (SLTI), a warm layer sandwiched between surface and subsurface colder waters, has been reported to frequently occur in conjunction with barrier layers in the Bay of Bengal (BoB), with potentially commensurable impacts on climate and postmonsoon tropical cyclones. Lack of systematic measurements from the BoB in the past prevented a thorough investigation of the SLTI spatiotemporal variability, their formation mechanisms, and their contribution to the surface temperature variations. The present study benefits from the recent Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) buoys located in BoB along 90°E at 4°N, 8°N, 12°N, and 15°N over the 2006-2014 period. Analysis of data from these RAMA buoys indicates that SLTI forms after the summer monsoon and becomes fully developed during winter (December-February). SLTI exhibits a strong geographical dependency, with more frequent (80% times during winter) and intense inversions (amplitude, ΔT ˜ 0.7°C) occurring only in the northern BoB compared to central and southern Bay. SLTI also exhibits large interannual and intraseasonal variations, with intraseasonal amplitude significantly larger (ΔT ˜ 0.44°C) than the interannual amplitude (˜0.26°C). Heat budget analysis of the mixed layer reveals that the net surface heat loss is the most dominant process controlling the formation and maintenance of SLTI. However, there are instances of episodic advection of cold, low-saline waters over warm-saline waters leading to the formation of SLTI as in 2012-2013. Vertical processes contribute significantly to the mixed layer heat budget during winter, by warming the surface layer through entrainment and vertical diffusion.

  20. Surface characteristics of grasslands in Inner Mongolia as detected by micrometeorological measurements.

    Science.gov (United States)

    Ketzer, Bettina; Liu, Huizhi; Bernhofer, Christian

    2008-09-01

    A roving tower concept was used to compare a semi-arid grassland site in Inner Mongolia (China), which was fenced in 1979 and ungrazed thereafter (UG79) with differently grazed semi-arid steppe ecosystems. The study was conducted during three consecutive years characterised by contrasting precipitation. The different grazing intensities included continuously and moderately grazed (CG), winter grazed (WG), and heavily grazed (HG). Here, we compare the energy fluxes and surface parameters that characterise the differently managed plots. The main focus is on sensible heat flux (H), available energy (AE), surface temperature (T ( s )), and surface albedo (alpha). Systematic errors were excluded by a side-to-side intercomparison of the instruments, and systematic climatic differences were minimised by the close distance between the fixed and the roving eddy covariance tower. Statistically, AE and T ( s ) were always significantly different between two simultaneously measured grazing intensities. Whereas AE was higher at UG79 in all years (mean difference of about 19Wm(-2)), T ( s ) was typically lower at UG79 (mean differences of 0.4 degrees C to about 2 degrees C). The exception was the end of the vegetation period in 2004 when T ( s ) was 0.6 degrees C higher at UG79 compared to CG. At UG79 alpha was typically significantly lower, and H was typically significantly higher. Consequently, latent heat fluxes (both as energy balance residual and directly measured) do not differ much between the different grazing intensities. It is concluded, that (1) the roving tower concept is able to detect differences due to grazing, (2) differences between the sites can be attributed to real surface differences, and (3) differences due to grazing intensities are small compared to interannual differences in surface fluxes.

  1. Surface characteristics of debris-covered glacier tongues in the Khumbu Himalaya derived from remote sensing texture analysis

    Science.gov (United States)

    Racoviteanu, Adina; Arnaud, Yves; Nicholson, Lindsay

    2013-04-01

    The delineation of debris-covered glaciers remains a challenge in optical remote sensing, due to the similarity of the spectral signature of debris-covered ice to surrounding lateral moraines, making it difficult to apply standard semi-automated algorithms commonly used for clean ice delineation. Furthermore, supraglacial debris exhibits considerable spatial variability in its characteristics such as debris cover thickness, particle size, thermal resistance and thermal conductivity. These properties are needed in order to map the extent of debris cover and to estimate ice melt under the debris cover or at the surface. In this study we evaluate the potential of texture analysis for detecting surface characteristics of debris-cover glacier tongues in the Khumbu Himalaya, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and high-resolution Ikonos data. We focus on mapping supra-glacier lakes and exposed ice walls using texture analysis algorithms such as grey-level co-occurrence measures (GLCM), filtering, image segmentation, and particle boundaries. We compare the performance of various existing commercial software suitable for texture analysis such as ERDAS Objective, Aphelion, as well as public domain image display and analysis software used originally for medical analysis, notably Image SXM and ImageJ. Preliminary results based on geostatistics and GLCM measures show differences in surface roughness of debris cover when compared to surrounding ice-free moraines. We expand on these results and aim at developing a quasi-automated algorithm for extracting surface features, which will be used as input in an energy balance model for estimating melting under debris cover as well as surface ice melt.

  2. [Association of CD34 cell surface antigen expression with cytomorphological characteristics of acute promyelocytic leukemia blasts and clinical characteristics of patients: one center experience].

    Science.gov (United States)

    Ostojić, Alen; Pazur, Marina; Siftar, Zoran; Paro, Mirjana Mariana Kardum; Jelić-Puskarić, Biljana; Gredelj-Simec, Njetocka; Radić-Kristo, Delfa; Kardum-Skelin, Ika; Vrhovac, Radovan; Jaksić, Branimir

    2011-09-01

    The aims of the study were to investigate the association between cytomorphology and immunophenotypic expression of CD34 cell surface antigen of blasts and their relationship with clinical and laboratory characteristics of patients with acute promyelocytic leukemia (APL). Sixteen consecutive patients (male 69% and female 31%) diagnosed with APL at Department of Hematology, Merkur University Hospital between August 1998 and December 2010 were included in the study. The mean age of patients was 43.9 (range: 18-78, SD 14.9). The patients' clinical and laboratory features, cytomorphological characteristics of APL-blasts and their immunophenotype determined by flow cytometry were analyzed. Patients were divided into two groups, CD34- and CD34+, and were then compared according to clinical and laboratory characteristics. There was no difference according to age, sex or white blood cell count between two groups. The mean value of hypogranular/agranular APL-blasts was markedly higher in CD34+ group than CD34- group (34%, range 9-60, SD 24.4 vs. 11.5%, range 0-38, SD 13.7), with borderline statistical significance (P=0.055). CD34- patients had significantly better overall survival than CD34+ ones (P=0.02). Patients without Auer rods detected in APL-blasts had higher CD34 expression (69.4% +/- 33.8) compared to patients with detected Auer rods (7.3% +/- 24.8), but statistical significance was not reached (p=0.053). Our results are consistent with the results of other published studies and point to the fact that higher CD34 expression and lower cytoplasmic granularity of APL-blasts are factors that seem to define a specific subgroup of APL patients. Together with other diagnostic tools currently available, they could be of value in planning treatment of APL patients.

  3. The effect of surface microgrooves and anodic oxidation on the surface characteristics of titanium and the osteogenic activity of human periodontal ligament cells.

    Science.gov (United States)

    Lee, Myung Hyun; Kang, Jong Ho; Lee, Suk Won

    2013-01-01

    The purpose of this study was to investigate the effect of titanium (Ti) surface microgrooves and anodic oxidation on the surface characteristics of titanium and the osteogenic activity of human periodontal ligament cells (PLCs) cultured on theses surfaces. Mechanically ground Ti was used as the control substratum (NE0). Truncated V-shaped microgrooves, 60μm-wide and 10μm-deep in cross-sections, were created on the Ti substrata by photolithography (NE60/10). Anodically oxidized Ti (NE0AO) and anodically oxidized microgrooved Ti (NE60/10AO) were also prepared. Scanning electron microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were performed for surface characterization. Cell proliferation assay, osteoblast differentiation assay, and quantitative real-time PCR analysis were performed to compare the osteogenic activity of PLCs on NE0, NE60/10, NEAO, and NE60/10AO. A decrease in the microgroove-width of NE60/10AO compared to NE60/10 due to Ti oxide layer generation by anodic oxidation was detected with XRD and XPS. Cell proliferation, osteoblast differentiation, and osteo-related gene expression were enhanced on the NE60/10AO substrata compared with NE0, NE60/10, and NE0AO. The combination of Ti surface microgrooves and subsequent anodic oxidation treatment synergistically upregulated osteo-related gene expression, despite showing limited ability to increase cell proliferation and osteoblast differentiation levels in PLCs. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Moisture adsorption desorption characteristics of stainless steel tubing measured by ball surface acoustic wave trace moisture analyzer

    Science.gov (United States)

    Tsuji, Toshishiro; Akao, Shingo; Oizumi, Toru; Takeda, Nobuo; Tsukahara, Yusuke; Yamanaka, Kazushi

    2017-07-01

    A ball surface acoustic wave (SAW) trace moisture analyzer (TMA) was applied to measuring the adsorption and desorption (AD) characteristics of a stainless steel tube. For the first time, two-frequency measurement for precise temperature compensation was attempted at intervals of 3 s using a burst waveform undersampling circuit. We succeeded in measuring the variations of moisture transit time and dry-down dynamics caused by inner surface treatments such as bright annealing (BA), electropolishing (EP), and electrochemical buffing (ECB) using a sample-tube length of only 100 mm at a flow rate of 0.1 L/min. Net moisture adsorption was evaluated from the measured adsorption subtracted by the background adsorption. As a result, it was found that the adsorption on the ECB tube was smaller than those on EP and BA tubes by 1/3 and 1/4, respectively, at a baseline concentration of 13 ppbv. From these results, it was demonstrated that the ball SAW TMA could be used for measuring the AD characteristics of stainless steel tubes with various surface treatments.

  5. Optimization in CNC end milling of UNS C34000 medium leaded brass with multiple surface roughnesses characteristics

    Indian Academy of Sciences (India)

    Bharat Chandra Routara; Saumya Darsan Mohanty; Saurav Datta; Asish Bandyopadhyay; Siba Sankar Mahapatra

    2010-10-01

    The present study highlights a multi-objective optimization problem by applying utility concept coupled with Taguchi method through a case study in CNC end milling of UNS C34000 medium leaded brass. The study aimed at evaluating the best process environment which could simultaneously satisfy multiple requirements of surface quality. In view of the fact, the traditional Taguchi method cannot solve a multi-objective optimization problem; to overcome this limitation, utility theory has been coupled with Taguchi method. Depending on Taguchi’s Lower-the-Better (LB) response criteria; individual surface quality characteristics has been transformed into corresponding utility values. Individual utility values have been aggregated finally to compute overall utility degree which serves as representative objective function for optimizing using Taguchi method. Utility theory has been adopted to convert a multi-response optimization problem into a single response optimization problem; in which overall utility degree serves as the representative single objective function for optimization. The study of combined utility theory and Taguchi method for predicting optimal setting. Based on Taguchi’s Signal-to-Noise ratio (S/N), analysis has been made on the overall utility degree and optimal process environment has been selected finally which corresponds to highest S/N Ratio. Optimal result has been verified through confirmatory test. The case study indicates application feasibility of the aforesaid methodology proposed for multiresponse optimization and off-line control of multiple surface quality characteristics in CNC end milling.

  6. Anti-fouling characteristics of surface-confined oligonucleotide strands bioconjugated on streptavidin platforms in the presence of nanomaterials.

    Science.gov (United States)

    Mir, Mònica; Cameron, Petra J; Zhong, Xinhua; Azzaroni, Omar; Alvarez, Marta; Knoll, Wolfgang

    2009-05-15

    This work describes our studies on the molecular design of interfacial architectures suitable for DNA sensing which could resist non-specific binding of nanomaterials commonly used as labels for amplifying biorecognition events. We observed that the non-specific binding of bio-nanomaterials to surface-confined oligonucleotide strands is highly dependent on the characteristics of the interfacial architecture. Thiolated double stranded oligonucleotide arrays assembled on Au surfaces evidence significant fouling in the presence of nanoparticles (NPs) at the nanomolar level. The non-specific interaction between the oligonucleotide strands and the nanomaterials can be sensitively minimized by introducing streptavidin (SAv) as an underlayer conjugated to the DNA arrays. The role of the SAv layer was attributed to the significant hydrophilic repulsion between the SAv-modified surface and the nanomaterials in close proximity to the interface, thus conferring outstanding anti-fouling characteristics to the interfacial architecture. These results provide a simple and straightforward strategy to overcome the limitations introduced by the non-specific binding of labels to achieve reliable detection of DNA-based biorecognition events.

  7. Contact angle dynamics in droplets impacting on flat surfaces with different wetting characteristics

    Science.gov (United States)

    Bayer, Ilker S.; Megaridis, Constantine M.

    2006-07-01

    An experimental study is presented on contact angle dynamics during spreading/recoiling of mm-sized water droplets impacting orthogonally on various surfaces with We {=} O(0.1)-O(10), Ca {=} O(0.001)-O(0.01), Re {=} O(100)-O(1000), Oh {=} O(0.001) and Bo {=} O(0.1). In this impact regime, inertial, viscous and capillary phenomena act in unison to influence contact angle dynamics. The wetting properties of the target surfaces range from wettable to non-wettable. The experiments feature accelerating and decelerating wetting lines, capillary surface waves in the early impact stages, contact angle hysteresis, and droplet rebound under non-wetting conditions. The objective of the work is to provide insight into the dynamic behaviour of the apparent (macroscopic) contact angle theta and its dependence on contact line velocity V_{scriptsizeCL} at various degrees of surface wetting. By correlating the temporal behaviours of theta and V_{scriptsizeCL}, the angle vs. speed relationship is established for each case examined. The results reveal that surface wettability has a critical influence on dynamic contact angle behaviour. The hydrodynamic wetting theory of Cox (J. Fluid Mech. vol. 357, 1998, p. 249) and the molecular-kinetic theory of wetting by Blake & Haynes (J. Colloid Interface Sci.) vol. 30, 1969, p. 421) are implemented to extract values of the corresponding microscopic wetting parameters required to match the experimentally observed theta vs. V_{scriptsizeCL} data. Application of hydrodynamic theory indicates that in the slow stage of forced spreading the slip length and the microscopic contact angle should be contact line velocity dependent. The hydrodynamic theory performs well during kinematic (fast) spreading, in which solid/liquid interactions are weak. Application of the molecular kinetic theory yields physically reasonable molecular wetting parameters, which, however, vary with impact conditions. The results indicate that even for a single liquid there is

  8. Characteristics of woodland rhizobial populations from surface- and deep-soil environments of the sonoran desert.

    Science.gov (United States)

    Waldon, H B; Jenkins, M B; Virginia, R A; Harding, E E

    1989-12-01

    A collection of 74 rhizobial isolates recovered from nodules of the desert woody legumes Prosopis glandulosa, Psorothamnus spinosus, and Acacia constricta were characterized by using 61 nutritional and biochemical tests. We compared isolates from A. constricta and Prosopis glandulosa and tested the hypothesis that the rhizobia from a deep-phreatic rooting zone of a Prosopis woodland in the Sonoran Desert of southern California were phenetically distinct from rhizobia from surface soils. Cluster analysis identified four major homogeneous groups. The first phenon contained slow-growing (SG) Prosopis rhizobia from surface and deep-phreatic-soil environments. These isolates grew poorly on most of the media used in the study, probably because of their requirement for a high medium pH. The second group of isolates primarily contained SG Prosopis rhizobia from the deep-phreatic rooting environment and included two fast-growing (FG) Psorothamnus rhizobia. These isolates were nutritionally versatile and grew over a broad pH range. The third major phenon was composed mainly of FG Prosopis rhizobia from surface and dry subsurface soils. While these isolates used a restricted range of carbohydrates (including sucrose) as sole carbon sources, they showed better growth on a range of organic acids as sole carbon sources and amino acids as sole carbon and nitrogen sources than did other isolates in the study. They grew better at 36 degrees C than at 26 degrees C. The FG Acacia rhizobia from surface-soil environments formed a final major phenon that was distinct from the Prosopis isolates. They produced very high absorbance readings on all of the carbohydrates tested except sucrose, grew poorly on many of the other substrates tested, and preferred a 36 to a 26 degrees C incubation temperature. The surface populations of Prosopis rhizobia required a higher pH for growth and, under the conditions used in this study, were less tolerant of low solute potential and high growth

  9. Monitoring of chemical and physical characteristics of stone surfaces by a portable spectroradiometer

    Science.gov (United States)

    Camaiti, Mara; Benvenuti, Marco; Costagliola, Pilar; Di Benedetto, Francesco; Del Ventisette, Chiara; Garfagnoli, Francesca; Lombardi, Luca; Moretti, Sandro; Pecchioni, Elena; Vettori, Silvia

    2013-04-01

    A portable radiometer (ASD-FieldSpec FP Pro spectroradiometer), which continuously and rapidly acquires punctual reflectance spectra in the 350-2500 nm spectral range, has been recently proposed as non-destructive and non-invasive technology for detecting gypsum and other materials (inorganic as well as organic) on surfaces of historical buildings [1,2,3]. The instrument, which is also capable to quantitatively assess physical changes of the surfaces (i. e. color changes), has the potentialities to be used for monitoring the state of conservation of stone surfaces through the monitoring of the relative abundance of some components considered precursor symptoms of decay. The increase of gypsum or the decrease of the relative abundance of organic materials used as protective materials allows, in fact, to control and detect the chemical attack of carbonate surfaces, as well as the efficacy and durability of protective treatments. Although the relative abundance of any compound is theoretically related to the signal intensities of its spectral signature, a quantitative analysis is often compromised by some factors such as the grain dimension of crystals [2 4]. However the monitoring of critical areas may give useful information on the progression of decay provided that the same areas are investigated. The spectroradiometer can operate both in natural light conditions and by a contact probe with fixed illumination and geometry of shot; in this study the second condition was preferred since the same operative conditions can be maintained for all the measurements during the monitoring. Aim of this work was to find an easy to use and accurate system for repositioning the spectroradiometer probe in the same small areas of interest during the long-term monitoring. Two systems (theodolite and distance measuring laser) have been tested and their accuracy has been evaluated on some Florentine historical buildings (Cathedral of Santa Maria del Fiore and Basilica of San Miniato

  10. Influence of surface texture on the galling characteristics of lean duplex and austenitic stainless steels

    DEFF Research Database (Denmark)

    Wadman, Boel; Eriksen, J.; Olsson, M.;

    2010-01-01

    of sheet materials and lubricants. The strip reduction test, a severe sheet forming tribology test was used to simulate the conditions during ironing. This investigation shows that the risk of galling is highly dependent on the surface texture of the duplex steel. Trials were also performed......Two simulative test methods were used to study galling in sheet forming of two types of stainless steel sheet: austenitic (EN 1.4301) and lean duplex LDX 2101 (EN 1.4162) in different surface conditions. The pin-on-disc test was used to analyse the galling resistance of different combinations...... in an industrial tool used for high volume production of pump components, to compare forming of LDX 2101 and austenitic stainless steel with equal thickness. The forming forces, the geometry and the strains in the sheet material were compared for the same component. It was found that LDX steels can be formed...

  11. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Science.gov (United States)

    Shih, Yi-Ting; Li, Kuan-Wei; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

    2017-06-01

    The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75-85% range. The proposed design provides a facile new method for developing SED applications.

  12. Characteristics of dynamic contact-angle in presence of surface-charge

    CERN Document Server

    Acharya, Palash V; Chakraborty, Suman

    2015-01-01

    We account for the presence of surface charges towards describing variations in the dynamic contact angle of an advancing liquid-gas meniscus. Starting from the thin-film based formalism, we present closed-form analytical expressions relating the dynamic contact-angle with the capillary number (essentially normalized contact-line speed) and other interfacial parameters. Specifically, our analysis presents, within the realm of hydrodynamic paradigm, a connection between the micro- and macro-scale physics at the vicinity of the contact-line region, taking the combined confluence of viscous and capillary forces along with van der Waals and electrostatic interactions. This connection rationalizes the hitherto reported anomalous window of the magnitude of the microscopic length scales required to corroborate experimental data for ionic liquids. Moreover, our analysis shows the possibility of a transition from strong to weak influence of surface charge in a dynamic fashion with contact-line speed along with other e...

  13. Characteristics and realization of the second generation surface acoustic wave's wavelet device

    Institute of Scientific and Technical Information of China (English)

    Wen Changbao; Zhu Changchun; Lu Wenke; Liu Qinghong; Liu Junhua

    2006-01-01

    To overcome the bulk acoustic wave (BAW), the triple transit signals and the discontinuous frequency band in the first generation surface acoustic wave's (FGSAW's) wavelet device, the full transfer multistrip coupler (MSC) is applied to implement wavelet device, and a novel structure of the second generation surface acoustic wave's (SGSAW's) wavelet device is proposed. In the SGSAW's wavelet device, the BAW is separated and eliminated in different acoustic propagating tracks, and the triple transit signal is suppressed. For arbitrary wavelet scale device, the center frequency is three times the radius of frequency band, which ensures that the frequency band of the SGSAW's wavelet device is continuous, and avoids losing signals caused by the discontinuation of frequency band. Experimental result confirms that the BAW suppression, ripples in band, receiving loss and insertion loss of the SGSAW's wavelet device are remarkably improved compared with those of the FGSAW's wavelet device.

  14. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents

    Science.gov (United States)

    Fu, C. H.; Liu, J. F.; Guo, Andrew

    2015-10-01

    Nitinol alloys have been widely used in manufacturing of vascular stents due to the outstanding properties such as superelasticity, shape memory, and superior biocompatibility. Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone (HAZ), and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

  15. Anchorage of titanium implants with different surface characteristics: an experimental study in rabbits

    DEFF Research Database (Denmark)

    Gotfredsen, K; Berglundh, T; Lindhe, J

    2000-01-01

    ) TiO2-blasted with particles of grain size 10 to 53 microns; (3) TiO2-blasted, grain size 63 to 90 microns; (4) TiO2-blasted, grain size 90 to 125 microns; (5) titanium plasma-sprayed (TPS). The surface topography was determined by the use of an optical instrument. Twelve rabbits, divided into two...... in group B were 9 and 12 weeks. The tibiae were removed, and each implant site was dissected, fixed, and embedded in light-curing resin. Ground sections were made, and the peri-implant bone was analyzed using fluorescence and light microscopy. RESULTS: The turned implants had the lowest Sa and Sy values......: The present study demonstrated that a clear relation exists between surface roughness, described in Sa values, and implant anchorage assessed by RMT measurements. The anchorage appeared to increase with the maturation of bone tissue during healing....

  16. A fast model for mean and turbulent wind characteristics over terrain with mixed surface roughness

    DEFF Research Database (Denmark)

    Astrup, P.; Mikkelsen, T.; Jensen, N.O.

    1997-01-01

    The real-time near-range atmospheric model chain in RODOS already includes the fast spectral LINCOM code, which was originally developed by Rise for modelling the mean wind fields over hilly, but otherwise homogeneous, terrain. Its output is used as a wind field driver for the dispersion model...... of arrival of radioactive clouds traversing, for instance, a land/water/land surface, and (2) for calculation of the turbulent shear stress, and thereby the scaling parameters, over mixed terrain....

  17. Experimental Study of Thermo-hydraulic Characteristics of Surfaces with In-line Dimple Arrangement

    Directory of Open Access Journals (Sweden)

    S. A. Burtsev

    2015-01-01

    Full Text Available The paper presents a conducted experimental study of the heat exchange intensification on the surfaces covered with a regular vortex-generating relief that is an in-line array of the shallow hemispherical dimples. Using 12 configuration options with the Reynolds numbers in the range of (0.2-7.0 106 as an example, it analyses how a longitudinal and cross step of the in-line dimple array (density dimples effects on the processes of heat exchange intensification and resistance.The monocomponent strain-gauge balance allows us to define a value of the resistance coefficient by direct weighing of models (located in parallel in a flow of "relief" and smooth "reference" ones being under study. Distribution fields of heat – transfer factor are determined by recording a cooling process of the surface of studied models having high spatial and temporary resolution. All researches were conducted with one-shot data record of these thermal and hydraulic measurements for the smooth (reference surfaces and the studied surfaces covered with a regular vortex-generating relief (dimples. The error of determined parameters was no more than ±5%.The oil-sooty method allows us to visualize flow around a regular relief and obtain a flow pattern for 12 options of dimples configuration. The analysis has been carried out and a compliance of the flow patterns with the field of heat-transfer factors has been obtained.It has been found that for the in-line configuration a Reynolds analogy factor for most models is nonlinearly dependent on the Reynolds number. The friction intensification, at first, falls (to some Reynolds number and, further, starts increasing, tending to the friction intensification value with self-similarity flow around. Thus with increasing Reynolds number, the heattransfer factor intensification falls (more slowly than resistance intensification.

  18. Cycle Classes on the Moduli of K3 surfaces in positive characteristic

    CERN Document Server

    Ekedahl, Torsten

    2011-01-01

    This paper provides explicit closed formulas in terms of tautological classes for the cycle classes of the height and Artin invariant strata in families of K3 surfaces. The proof is uniform for all strata and uses a flag space as the computations in [arXiv:math/0412272] for the Ekedahl-Oort strata for families of abelian varieties, but employs a Pieri formula formula to determine the push down to the base space.

  19. The effects of formulation and processing on surface characteristics and functional properties of dairy powders

    OpenAIRE

    Kelly, Grace M.

    2016-01-01

    The objectives of this thesis were to (i) study the effect of increasing protein concentration in milk protein concentrate (MPC) powders on surface composition and sorption properties; (ii) examine the effect of increasing protein content on the rehydration properties of MPC; (iii) study the physicochemical properties of spraydried emulsion-containing powders having different water and oil contents; (iv) analyse the effect of protein type on water sorption and diffusivity properties in a prot...

  20. Improved Performances in Subsonic Flows of an SPH Scheme with Gradients Estimated Using an Integral Approach

    Science.gov (United States)

    Valdarnini, R.

    2016-11-01

    In this paper, we present results from a series of hydrodynamical tests aimed at validating the performance of a smoothed particle hydrodynamics (SPH) formulation in which gradients are derived from an integral approach. We specifically investigate the code behavior with subsonic flows, where it is well known that zeroth-order inconsistencies present in standard SPH make it particularly problematic to correctly model the fluid dynamics. In particular, we consider the Gresho-Chan vortex problem, the growth of Kelvin-Helmholtz instabilities, the statistics of driven subsonic turbulence and the cold Keplerian disk problem. We compare simulation results for the different tests with those obtained, for the same initial conditions, using standard SPH. We also compare the results with the corresponding ones obtained previously with other numerical methods, such as codes based on a moving-mesh scheme or Godunov-type Lagrangian meshless methods. We quantify code performances by introducing error norms and spectral properties of the particle distribution, in a way similar to what was done in other works. We find that the new SPH formulation exhibits strongly reduced gradient errors and outperforms standard SPH in all of the tests considered. In fact, in terms of accuracy, we find good agreement between the simulation results of the new scheme and those produced using other recently proposed numerical schemes. These findings suggest that the proposed method can be successfully applied for many astrophysical problems in which the presence of subsonic flows previously limited the use of SPH, with the new scheme now being competitive in these regimes with other numerical methods.

  1. Surface characteristics and antibacterial activity of a silver-doped carbon monolith

    Directory of Open Access Journals (Sweden)

    Marija Vukčević et al

    2008-01-01

    Full Text Available A carbon monolith with a silver coating was prepared and its antimicrobial behaviour in a flow system was examined. The functional groups on the surface of the carbon monolith were determined by temperature-programmed desorption and Boehm's method, and the point of zero charge was determined by mass titration. The specific surface area was examined by N2 adsorption using the Brunauer, Emmett and Teller (BET method. As a test for the surface activity, the deposition of silver from an aqueous solution of a silver salt was used. The morphology and structure of the silver coatings were characterized by scanning electron microscopy and x-ray diffraction. The resistance to the attrition of the silver deposited on the carbon monolith was tested. The antimicrobial activity of the carbon monolith with a silver coating was determined using standard microbiological methods. Carbon monolith samples with a silver coating showed good antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans, and are therefore suitable for water purification, particularly as personal disposable water filters with a limited capacity.

  2. Effect of laser surface melting on microstructure and corrosion characteristics of AM60B magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cancan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Liang, Jun, E-mail: jliang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou, Jiansong, E-mail: jszhou@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Lingqian [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li, Qingbiao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100039 (China)

    2015-07-15

    Highlights: • Laser surface melting was used on AM60B Mg alloy. • The microstructure, composition and corrosion behavior of the as-received and LSM treated specimens were compared. • The laser treated alloy exhibited better corrosion resistance than the as-received one in the long term. • A model of two different corrosion mechanisms was established. - Abstract: Surface modification of laser surface melting (LSM) was applied to the AM60B magnesium alloy using a 10 kW continuous-wave CO{sub 2} laser. The microstructure, composition and corrosion resistance of AM60B magnesium alloy after LSM treatment were investigated by using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) and corrosion tests, respectively. Results showed that the LSM treatment produced a continuous and homogeneous modified layer with refined grains, enriched Al element and redistributed intermetallic compounds on AM60B alloy. The corrosion resistance of the AM60B alloy was enhanced by the LSM treatment. The enhancement of the corrosion resistance was mainly attributed to the reduced corrosion susceptibility of Al enriched α-Mg matrix and the barrier effect of uniformly distributed β-phase of the LSM modified layer.

  3. Statistical characteristics of surface integrity by fiber laser cutting of Nitinol vascular stents

    Energy Technology Data Exchange (ETDEWEB)

    Fu, C.H., E-mail: cfu5@crimson.ua.edu [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Liu, J.F. [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); Guo, Andrew [Dept of Mechanical Engineering, The University of Alabama, Tuscaloosa, AL 35487 (United States); College of Arts and Science, Vanderbilt University, Nashville, TN 37235 (United States)

    2015-10-30

    Graphical abstract: - Highlights: • Precision kerf with tight tolerance of Nitinol stents can be cut by fiber laser. • No HAZ in the subsurface was detected due to large grain size. • Recast layer has lower hardness than the bulk. • Laser cutting speed has a higher influence on surface integrity than laser power. - Abstract: Nitinol alloys have been widely used in manufacturing of vascular stents due to the outstanding properties such as superelasticity, shape memory, and superior biocompatibility. Laser cutting is the dominant process for manufacturing Nitinol stents. Conventional laser cutting usually produces unsatisfactory surface integrity which has a significant detrimental impact on stent performance. Emerging as a competitive process, fiber laser with high beam quality is expected to produce much less thermal damage such as striation, dross, heat affected zone (HAZ), and recast layer. To understand the process capability of fiber laser cutting of Nitinol alloy, a design-of-experiment based laser cutting experiment was performed. The kerf geometry, roughness, topography, microstructure, and hardness were studied to better understand the nature of the HAZ and recast layer in fiber laser cutting. Moreover, effect size analysis was conducted to investigate the relationship between surface integrity and process parameters.

  4. Nanoscale Probing of Local Electrical Characteristics on MBE-Grown Bi₂Te₃ Surfaces under Ambient Conditions.

    Science.gov (United States)

    Macedo, Rita J; Harrison, Sara E; Dorofeeva, Tatiana S; Harris, James S; Kiehl, Richard A

    2015-07-08

    The local electrical characteristics on the surface of MBE-grown Bi2Te3 are probed under ambient conditions by conductive atomic force microscopy. Nanoscale mapping reveals a 10-100× enhancement in current at step-edges compared to that on terraces. Analysis of the local current-voltage characteristics indicates that the transport mechanism is similar for step-edges and terraces. Comparison of the results with those for control samples shows that the current enhancement is not a measurement artifact but instead is due to local differences in electronic properties. The likelihood of various possible mechanisms is discussed. The absence of enhancement at the step-edges for graphite terraces is consistent with the intriguing possibility that spin-orbit coupling and topological effects play a significant role in the step-edge current enhancement in Bi2Te3.

  5. Stable carbon isotope characteristics of different plant species and surface soil in arid regions

    Institute of Scientific and Technical Information of China (English)

    Jianying MA; Wei SUN; Huiwen ZHANG; Dunsheng XIA; Chengbang AN; Fahu CHEN

    2009-01-01

    The stable carbon isotope composition in surface soil organic matter (δ13Csoil) contains integrative information on the carbon isotope composition of the standing terrestrial plants (δ13Cleaf). In order to obtain valuable vegetation information from the δ13C of terrestrial sediment, it is necessary to understand the relationship between the δ13C value in modem surface soil and the standing vegetation. In this paper, we studied the δ13C value in modem surface soil organic matter and standing vegetation in arid areas in China, Australia and the United States. The isotopic discrepancy between δ13Csoil andδ13Cleaf of the standing dominant vegetation was examined in those different arid regions. The results show that the δ13Csoil values were consistently enriched compared to the δ13Cleaf. The δ13Cleaf values were positively correlated with δ13Csoil, which suggests that the interference of microorganisms and hydrophytes on the isotopic composition of surface soil organic matter during soil organic matter formation could be ignored in arid regions. The averaged discrepancy between δ13Csoil and δ13Cleaf is about 1.71%0 in Tamarix L. in the Tarim Basin in China, 1.50 ‰ in Eucalytus near Orange in Australia and 1.22 ‰ in Artemisia in Saratoga in the United States, which are different from the results of other studies. The results indicate that the discrepancies in the δ13C value between surface soil organic matter and standing vegetation were highly influenced by the differences in geophysical location and the dominant species of the studied ecosystems. We suggest that caution should be taken when organic matter δ13C in terrestrial sediment is used to extract paleovegetation information (C3/C4 vegetation composition), as the δ13C in soil organic matter is not only determined by the ratio of C3/C4 species, but also profoundly affected by climate change induced variation in the δ13C in dominant species.

  6. Mechanical characteristics of fused cast basalt tube encased in steel pipe for protecting steel surface

    Institute of Scientific and Technical Information of China (English)

    Jee-Seok WANG; Jong-Do KIM; Hee-Jong YOON

    2009-01-01

    Because of the various excellent characteristics of cast basalt materials, such as, anti-corrosion, anti-wearing, good hardness, high chemical stability, of which steel may not possess, the steel-basalt composite pipes are used in severe environments for compensating the defects of steel. The limit of bending moment with which steel-basalt composite pipe may safely endure was calculated and the limit curvature of the composite pipe in the safe range was presented. The application temperature of steel-basalt pipe was examined due to a different coefficient among basalt, mortar and mild steel.

  7. Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zuhui [Lee-Kuan-Yew Postdoctoral Fellow, 2007-2010, Nanyang Technological University, Singapore 639798 (Singapore); Jie Binbin; Sah Chihtang, E-mail: bb_jie@msn.com [Department of Physics, Xiamen University, Xiamen 361005 (China)

    2010-12-15

    Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombination (R-DCIV) at SiO{sub 2}/Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Read-Hall recombination kinetics and the Fermi distributions for electrons and holes. Insignificant distortion is observed over 90% of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory. This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range. (invited papers)

  8. Model analysis of the chemical conversion of exhaust species in the expanding plumes of subsonic aircraft

    Energy Technology Data Exchange (ETDEWEB)

    Moellhoff, M.; Hendricks, J.; Lippert, E.; Petry, H. [Koeln Univ. (Germany). Inst. fuer Geophysik und Meteorologie; Sausen, R. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Oberpfaffenhofen (Germany). Inst. fuer Physik der Atmosphaere

    1997-12-31

    A box model and two different one-dimensional models are used to investigate the chemical conversion of exhaust species in the dispersing plume of a subsonic aircraft flying at cruise altitude. The effect of varying daytime of release as well as the impact of changing dispersion time is studied with special respect to the aircraft induced O{sub 3} production. Effective emission amounts for consideration in mesoscale and global models are calculated. Simulations with modified photolysis rates are performed to show the sensitivity of the photochemistry to the occurrence of cirrus clouds. (author) 8 refs.

  9. Quasi-Steady Simulations for the Efficient Generation of Static Aerodynamic Coefficients at Subsonic Velocity

    Science.gov (United States)

    2016-09-01

    Introduction 1 2. Solution Technique 3 2.1 Steady-State Simulation 3 2.2 Quasi-Steady Sweep Simulation 4 3. Geometry 5 3.1 Model Geometry 5 3.2...Location of the projectile at various stages of the sweep procedure ..... 5 Fig. 2 Subsonic geometries : BF (top) and body–fin–canard configuration...scheme using a Harten–Lax–van Leer-Contact (commonly, HLLC) Riemann solver and Metacomp’s multidimensional Total-Variation-Diminishing (commonly

  10. 3D CFD modeling of subsonic and transonic flowing-gas DPALs with different pumping geometries

    Science.gov (United States)

    Yacoby, Eyal; Sadot, Oren; Barmashenko, Boris D.; Rosenwaks, Salman

    2015-10-01

    Three-dimensional computational fluid dynamics (3D CFD) modeling of subsonic (Mach number M ~ 0.2) and transonic (M ~ 0.9) diode pumped alkali lasers (DPALs), taking into account fluid dynamics and kinetic processes in the lasing medium is reported. The performance of these lasers is compared with that of supersonic (M ~ 2.7 for Cs and M ~ 2.4 for K) DPALs. The motivation for this study stems from the fact that subsonic and transonic DPALs require much simpler hardware than supersonic ones where supersonic nozzle, diffuser and high power mechanical pump (due to a drop in the gas total pressure in the nozzle) are required for continuous closed cycle operation. For Cs DPALs with 5 x 5 cm2 flow cross section pumped by large cross section (5 x 2 cm2) beam the maximum achievable power of supersonic devices is higher than that of the transonic and subsonic devices by only ~ 3% and ~ 10%, respectively. Thus in this case the supersonic operation mode has no substantial advantage over the transonic one. The main processes limiting the power of Cs supersonic DPALs are saturation of the D2 transition and large ~ 60% losses of alkali atoms due to ionization, whereas the influence of gas heating is negligible. For K transonic DPALs both the gas heating and ionization effects are shown to be unimportant. The maximum values of the power are higher than those in Cs transonic laser by ~ 11%. The power achieved in the supersonic and transonic K DPAL is higher than for the subsonic version, with the same resonator and K density at the inlet, by ~ 84% and ~ 27%, respectively, showing a considerable advantaged of the supersonic device over the transonic one. For pumping by rectangular beams of the same (5 x 2 cm2) cross section, comparison between end-pumping - where the laser beam and pump beam both propagate at along the same axis, and transverse-pumping - where they propagate perpendicularly to each other, shows that the output power and optical-to-optical efficiency are not

  11. Unsteady flow in a supersonic cascade with subsonic leading-edge locus

    Science.gov (United States)

    Adamczyk, J. J.; Goldstein, M. E.

    1978-01-01

    Linearized theory is used to predict the unsteady flow in a supersonic cascade with subsonic axial flow velocity. A closed-form analytical solution is obtained by using a double application of the Wiener-Hopf technique. Although numerical and semianalytical solutions of this problem have already appeared in the literature, this paper contains the first completely analytical solution. It has been stated in the literature that the blade source should vanish at the infinite duct resonance condition. The present analysis shows that this does not occur. This apparent discrepancy is explained in the paper.

  12. Subsonic flow past an oscillating cascade with steady blade loading - Basic formulation

    Science.gov (United States)

    Verdon, J. M.; Caspar, J. R.; Adamczyk, J. J.

    1975-01-01

    A nonlinear boundary value problem governing the subsonic flow in a single, extended, blade passage region of a high-deflection, two dimensional, oscillating cascade is derived. The blades are assumed to be undergoing identical harmonic motions of small amplitude with constant phase angle between the motion of adjacent blades. An asymptotic perturbation approach is used to determine the velocity potential. This formulation can be used in the numerical determination of unsteady potential and thus the unsteady aerodynamic force and moment under various combinations of cascade and flow parameters.

  13. Trim and Structural Optimization of Subsonic Transport Wings Using Nonconventional Aeroelastic Tailoring

    Science.gov (United States)

    Stanford, Bret K.; Jutte, Christine V.

    2014-01-01

    Several minimum-mass aeroelastic optimization problems are solved to evaluate the effectiveness of a variety of novel tailoring schemes for subsonic transport wings. Aeroelastic strength and panel buckling constraints are imposed across a variety of trimmed maneuver loads. Tailoring with metallic thickness variations, functionally graded materials, composite laminates, tow steering, and distributed trailing edge control effectors are all found to provide reductions in structural wing mass with varying degrees of success. The question as to whether this wing mass reduction will offset the increased manufacturing cost is left unresolved for each case.

  14. Self-similar solution of the subsonic radiative heat equations using a binary equation of state

    OpenAIRE

    Heizler, Shay I.; Shussman, Tomer; Malka, Elad

    2016-01-01

    Radiative subsonic heat waves, and their radiation driven shock waves, are important hydro-radiative phenomena. The high pressure, causes hot matter in the rear part of the heat wave to ablate backwards. At the front of the heat wave, this ablation pressure generates a shock wave which propagates ahead of the heat front. Although no self-similar solution of both the ablation and shock regions exists, a solution for the full problem was found in a previous work. Here, we use this model in orde...

  15. Utilization of satellite-derived estimates of meteorological and land surface characteristics in the Land Surface Model for vast agricultural region territory

    Science.gov (United States)

    Muzylev, Eugene; Startseva, Zoya; Uspensky, Alexander; Volkova, Elena

    2015-04-01

    The method has been elaborated to evaluate the water and heat regime characteristics of the territory on a regional scale for the vegetation season based on a physical-mathematical model of water and heat exchange between vegetation covered land surface and atmosphere (LSM, Land Surface Model) appropriate for using satellite information on land surface and meteorological conditions. The developed model is intended for calculating soil water content, evapotranspiration (evaporation from bare soil and transpiration by vegetation), vertical water and heat fluxes as well as land surface and vegetation cover temperatures and vertical distributions of temperature and moisture in the active soil layer. Parameters of the model are soil and vegetation characteristics and input variables are meteorological characteristics. Their values have been obtained from ground-based observations at agricultural meteorological stations and satellite-based measurements by scanning radiometers AVHRR/NOAA, MODIS/EOS Terra and Aqua and SEVIRI (geostationary satellites Meteosat-9, -10). The AVHRR data have been used to build the estimates of three types of land surface temperature (LST): land skin temperature Tsg, air temperature at a level of vegetation cover Ta and efficient radiation temperature Tseff, emissivity E, normalized vegetation index NDVI, vegetation cover fraction B, leaf area index LAI, and precipitation. The set of estimates derived from MODIS data has comprised values of LST Tls, E, NDVI and LAI. The SEVIRI-based retrievals have included Tls, Ta, Е at daylight and nighttime, LAI (daily) and precipitation. The case study has been carried out for agricultural Central Black Earth region of the European Russia of 227,300 sq.km containing 7 regions of the Russian Federation for years 2009-2013 vegetation seasons. Estimates of described characteristics have been built with the help of the developed original and improved pre-existing methods and technologies of thematic processing

  16. On the magma chamber characteristics as inferred from surface geology and geochemistry: examples from Mexican geothermal areas

    Science.gov (United States)

    Verma, Surendra P.

    1985-12-01

    A procedure is described which enables us to obtain estimates of some physical and chemical characteristics of sub-surface magma chambers. This is applied to three geothermal areas of the Mexican Volcanic Belt (MVB) in central Mexico. The approximate volumes estimated for the underlying chemically and thermally zoned magma chambers are: 1500 km 3 for Los Humeros, 600 km 3 for La Primavera, and 400 km 3 for Los Azufres. These estimates will have to be modified as more geological-geochemical data become available.

  17. On propagation characteristics of SH-type surface acoustic waves in periodic metal gratings by variational principle

    Institute of Scientific and Technical Information of China (English)

    XU Fangqian; HE Shitang; LIU Jiansheng; CHEN Yixiang

    2009-01-01

    Based on D.P. Chen and Haus' theory, a theoretical method was presented to analyze dispersion characteristics of SH-type surface acoustic waves (SAWs) propagating on periodic metallic grating structures with a variational principle and coupling-of-modes equation. Without using complicated Green's function, the calculating results of the method agree well with those of Hashimoto's theory. On the other hand, Hashimoto's method is helpless for calculating the dispersion relation of short-circuited gratings on ST-90°X quartz etc. However, the method developed in this paper can successfully calculate it.

  18. The temporal and spatial characteristics of the surface air temperature variations over the Antarctic and its surrounding area

    Institute of Scientific and Technical Information of China (English)

    陆龙骅; 卞林根; 贾朋群

    1997-01-01

    The characteristics of the spatial distribution, temporal variations trend and oscillation for the surface air temperature variations during 1957-1993 in the Antarctic and its surrounding area were analyzed. The results show that the short-time climate change in the Antarctic is complex both temporally and spatially. The Antarctic is by no means the strongest responding region to the global greenhouse effect. There is a distinguished difference in the trends of the temperature changes for the Antarctic and global mean, which could not be explained simply by the global greenhouse effect.

  19. Investigation of secondary droplet characteristics produced by an isooctane drop chain impact onto a heated piston surface

    Science.gov (United States)

    Richter, B.; Dullenkopf, K.; Bauer, H.-J.

    2005-08-01

    The physics of the impingement process of small hydrocarbon droplets is mostly unknown due to the difficulties of obtaining experimental data. In this publication, the impingement of small isooctane droplets on a hot piston surface is studied. The emphasis was put on the image-based investigation of the process of successive impingements and its influence on secondary droplet formation. The diameter and velocity of the secondary droplets were found to depend on the wall temperature and impingement frequency. Thus, the temporal interaction has a significant influence on the secondary droplet characteristics.

  20. RESEARCH ON MODELING AND CHARACTERISTICS OF THE SPINDLE DYNAMIC COUPLING ABSORBERING SYSTEM OF A SUPER-PRECISION SURFACE GRINDING MACHINE

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The bearing is described by constrain matrix, and the spindle system of a NC surface grinding machine is simplified as elastic-coupling beam, then modal synthesis method is used to establish the dynamic model of beam.Moreover, the response of the end of rotor is analyzed, and the natural frequency, principle mode and other dynamic characteristics of the coupling system are studied, the law of bearing stiffness to coupling frequency and amplitude of rotor is also found.Finally, according to the actual condition, a dynamic absorber is designed.The simulation and experimental results show that the amplitude of spindle can be declined effectively when the dynamic absorber is attached.