Science.gov

Sample records for afm experimental results

  1. Development of portable experimental set-up for AFM to work at cryogenic temperature

    NASA Astrophysics Data System (ADS)

    Agarwal, D. H.; Bhatt, P. M.; Pathan, A. M.; Patel, Hitarthi; Joshi, U. S.

    2012-06-01

    We report on the designing aspects and fabrication of low temperature atomic force microscope (AFM) to study the surface structures of nanomaterials. Several key features of design including liquid nitrogen reservoir, vacuum chamber, vibration isolation table etc. have been presented. The whole set up was assembled in-house at a fairly low cost to be used with any commercial AFM system. The surface morphology of important oxide (In0.94Sn0.04)2O3 (ITO) thin film nanostructures has been investigated using the cryogenic AFM set up.

  2. SAA drift: Experimental results

    NASA Astrophysics Data System (ADS)

    Grigoryan, O. R.; Romashova, V. V.; Petrov, A. N.

    According to the paleomagnetic analysis there are variations of Earth’s magnetic field connected with magnetic moment changing. These variations affect on the South Atlantic Anomaly (SAA) location. Indeed different observations approved the existence of the SAA westward drift rate (0.1 1.0 deg/year) and northward drift rate (approximately 0.1 deg/year). In this work, we present the analysis of experimental results obtained in Scobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU) onboard different Earth’s artificial satellites (1972 2003). The fluxes of protons with energy >50 MeV, gamma quanta with energy >500 keV and neutrons with energy 0.1 1.0 MeV in the SAA region have been analyzed. The mentioned above experimental data were obtained onboard the orbital stations Salut-6 (1979), MIR (1991, 1998) and ISS (2003) by the similar experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact that the SAA drifts westward. Moreover the analysis of fluxes of electrons with energy about hundreds keV (Cosmos-484 (1972) and Active (Interkosmos-24, 1991) satellites) verified not only the SAA westward drift but northward drift also.

  3. Experimental evidence of ultrathin polymer film stratification by AFM force spectroscopy.

    PubMed

    Delorme, Nicolas; Chebil, Mohamed Souheib; Vignaud, Guillaume; Le Houerou, Vincent; Bardeau, Jean-François; Busselez, Rémi; Gibaud, Alain; Grohens, Yves

    2015-06-01

    By performing Atomic Force Microscopy measurements of pull-off force as a function of the temperature, we were able to probe the dynamic of supported thin polystyrene (PS) films. Thermal transitions induce modifications in the surface energy, roughness and surface modulus that are clearly detected by AFM and related to PS chain relaxation mechanisms. We demonstrated the existence of three transition temperatures that can be associated to the relaxation of polymer chains located at different depth regions within the polymer film. Independently of the film thickness, we have confirmed the presence of a region of high mobility for the polymer chains at the free interface. The thickness of this region is estimated to be above 7nm. The detection of a transition only present for film thicker than the gyration radius Rg is linked to the dynamics of polymer chains in a bulk conformation (i.e. not in contact with the free interface). We claim here that our results demonstrate, in agreement with other techniques, the stratification of thin polymer film depth profile in terms of relaxation behavior. PMID:26087914

  4. Afm Measrurements of Martian Soil Particles Using Mems Technology - Results from the PHOENIX Mission

    NASA Astrophysics Data System (ADS)

    Gautsch, S.; Parrat, D.; de Rooij, N. F.; Staufer, U.; Morookian, J. M.; Hecht, M. H.; Vijendran, S.; Sykulska, H.; Pike, W. T.

    2011-12-01

    Light scattering experiments conducted on Mars indicated that soil particles have dimensions around 1 μm. Particles in that range play an important role in the gas exchange between sub-surface water ice and the atmosphere. Their shape can help tracing the geological history and may indicate past presence of liquid water. NASA's Phoenix mission therefore decided to analyze soil and dust particles in the sub-micrometer to a few micrometer range using an atomic force microscope (AFM) for the first time on another planet. The co-axially mounted AFM was capable of resolving particles with 10nm lateral resolution. A MEMS approach combined with mechatronic concepts for the scanner was selected for implementing the AFM. For redundancy, the sensor chip featured eight silicon cantilevers each with a 7 to 8 μm high tip. The cantilevers could be cleaved off if contaminated. During NASA's Phoenix Mission, which operated on the red planet from May to October 2008, we could demonstrate successful AFM operations. The instrument has executed 85 experiments of which 26 were needed for calibration. Of the remaining experiments about half (28) returned images where signatures of particles could be discerned.

  5. PDX experimental results

    SciTech Connect

    Meade, D.; Arunasalam, V.; Barnes, C.

    1981-01-01

    The main objectives of the Poloidal Divertor Experiment (PDX) are to: (1) determine the effectiveness of poloidal divertors in controlling impurities in high temperature plasmas, (2) use the poloidal divertor to provide clean plasmas for confinement and high beta studies, and (3) investigate the effect of cross-section shaping on plasma confinement and MHD properties. In this paper, we report the results obtained during initial divertor operation of the PDX.

  6. AFM study of glucagon fibrillation via oligomeric structures resulting in interwoven fibrils

    NASA Astrophysics Data System (ADS)

    Dong, Mingdong; Bruun Hovgaard, Mads; Xu, Sailong; Otzen, Daniel Erik; Besenbacher, Flemming

    2006-08-01

    Glucagon is a 29-residue amphiphatic hormone involved in the regulation of blood glucose levels in conjunction with insulin. In concentrated aqueous solutions, glucagon spontaneously aggregates to form amyloid fibrils, destroying its biological activity. In this study we utilize the atomic force microscope (AFM) to elucidate the fibrillation mechanism of glucagon at the nanoscale under acidic conditions (pH 2.0) by visualizing the nanostructures of fibrils formed at different stages of the incubation. Hollow disc-shaped oligomers form at an early stage in the process and subsequently rearrange to more solid oligomers. These oligomers co-exist with, and most likely act as precursors for, protofibrils, which subsequently associate to form at least three different classes of higher-order fibrils of different heights. A repeat unit of around 50 nm along the main fibril axis suggests a helical arrangement of interwoven protofibrils. The diversity of oligomeric and fibrillar arrangements formed at pH 2.0 complements previous spectroscopic analyses that revealed that fibrils formed under different conditions can differ substantially in stability and secondary structure.

  7. SAA drift:experimental results

    NASA Astrophysics Data System (ADS)

    Grigoryan, O. R.; Kudela, K.; Romashova, V. V.; Drozdov, A. Yu.

    According to the paleomagnetic analysis there are variations of Earth's magnetic field connected with magnetic momentum changing. Besides these variations affects on the trapped belt South Atlantic Anomaly (SAA) location. Indeed different observations including Space Shuttle short-time flights approved the existence SAA westward drift with speed 0.1-1.0 (deg/year) and northward drift with speed approximately 0.1 (deg/year). In this work we present the analysis of experimental results obtained in SINP MSU in 1972-2003 from different satellites. There were analyzed the fluxes of protons with energy > 50 MeV, gamma quanta with energy > 500 keV and neutrons with energy 0.1-1.0 MeV in SAA area and their maxima location. The data about fluxes were obtained onboard the orbital stations ``Salut-6'' (1979), MIR (1991, 1998) and ISS (2003) by the identical experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact of the SAA westward drift. Moreover the same analysis of maximum flux location of electrons with hundreds keV energy (satellites ``Kosmos-484'' (1972), ``Interkosmos-17'' (1977) and ``Activny'' (``Interkosmos-24'', 1991)) confirmed not only the SAA westward drift but northward drift also.

  8. Majorana Thermosyphon Prototype Experimental Results

    SciTech Connect

    Fast, James E.; Reid, Douglas J.; Aguayo Navarrete, Estanislao

    2010-12-17

    Objective The Majorana demonstrator will operate at liquid Nitrogen temperatures to ensure optimal spectrometric performance of its High Purity Germanium (HPGe) detector modules. In order to transfer the heat load of the detector module, the Majorana demonstrator requires a cooling system that will maintain a stable liquid nitrogen temperature. This cooling system is required to transport the heat from the detector chamber outside the shield. One approach is to use the two phase liquid-gas equilibrium to ensure constant temperature. This cooling technique is used in a thermosyphon. The thermosyphon can be designed so the vaporization/condensing process transfers heat through the shield while maintaining a stable operating temperature. A prototype of such system has been built at PNNL. This document presents the experimental results of the prototype and evaluates the heat transfer performance of the system. The cool down time, temperature gradient in the thermosyphon, and heat transfer analysis are studied in this document with different heat load applied to the prototype.

  9. Hydration states of AFm cement phases

    SciTech Connect

    Baquerizo, Luis G.; Matschei, Thomas; Scrivener, Karen L.; Saeidpour, Mahsa; Wadsö, Lars

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  10. Pentaquarks: the latest experimental results

    SciTech Connect

    M. Battaglieri; R. De Vita; Valery Kubarovsky

    2006-01-01

    After the claim of the possible discovery of a pentaquark state, many experiments reported positive and negative results opening a discussion about the pentaquark existence. New experiments with high resolution and high statistics are needed in the reaction channels and for the kinematics of the positive results to solve the controversy. Jefferson Lab started a comprehensive program to search for pentaquark in photoproduction at threshold on proton and deuteron targets, collecting more than 10 times the existing statistics. The first experiment on the proton (g11) just finished to analyze the data, and the first results of the pentaquark search are reported here.

  11. Kinetics of degradation of dipalmitoylphosphatidylcholine (DPPC) bilayers as a result of vipoxin phospholipase A2 activity: an atomic force microscopy (AFM) approach.

    PubMed

    Balashev, Konstantin; Atanasov, Vasil; Mitewa, Mariana; Petrova, Svetla; Bjørnholm, Thomas

    2011-01-01

    In this paper we used AFM as an analytical tool to visualize the degradation of a phospholipid bilayer undergoing hydrolysis of the vipoxin's PLA(2). We obtained time series images during the degradation process of supported 1, 2-dipalmitoylphosphatidylcholine (DPPC) bilayers and evaluated the occurrence and the growth rate of the bilayer defects. The special resolution of the AFM images allowed us to measure the area and the perimeter length of these defects and to draw conclusions about the kinetics of the enzyme reaction. Moreover, we also report for some unique characteristics discovered during the vipoxin's PLA(2) action. Experimentally for the first time, we observed the appearance and the growth of three-dimensional (3D), crystal-like structures within the formed defects of the degraded bilayer. In an effort to explain their nature, we applied bearing image analysis to estimate the volume of these crystals and we found that their growth rate follows a similar kinetic pattern as the degradation rate of the supported bilayer. PMID:20959114

  12. Characterization of the interaction between AFM tips and surface nanobubbles.

    PubMed

    Walczyk, Wiktoria; Schönherr, Holger

    2014-06-24

    While the presence of gaseous enclosures observed at various solid-water interfaces, the so-called "surface nanobubles", has been confirmed by many groups in recent years, their formation, properties, and stability have not been convincingly and exhaustively explained. Here we report on an atomic force microscopy (AFM) study of argon nanobubbles on highly oriented pyrolitic graphite (HOPG) in water to elucidate the properties of nanobubble surfaces and the mechanism of AFM tip-nanobubble interaction. In particular, the deformation of the nanobubble-water interface by the AFM tip and the question whether the AFM tip penetrates the nanobubble during scanning were addressed by this combined intermittent contact (tapping) mode and force volume AFM study. We found that the stiffness of nanobubbles was smaller than the cantilever spring constant and comparable with the surface tension of water. The interaction with the AFM tip resulted in severe quasi-linear deformation of the bubbles; however, in the case of tip-bubble attraction, the interface deformed toward the tip. We tested two models of tip-bubble interaction, namely, the capillary force and the dynamic interaction model, and found, depending on the tip properties, good agreement with experimental data. The results showed that the tip-bubble interaction strength and the magnitude of the bubble deformation depend strongly on tip and bubble geometry and on tip and substrate material, and are very sensitive to the presence of contaminations that alter the interfacial tension. In particular, nanobubbles interacted differently with hydrophilic and hydrophobic AFM tips, which resulted in qualitatively and quantitatively different force curves measured on the bubbles in the experiments. To minimize bubble deformation and obtain reliable AFM results, nanobubbles must be measured with a sharp hydrophilic tip and with a cantilever having a very low spring constant in a contamination-free system. PMID:24856074

  13. Detection of Pathogens Using AFM and SPR

    NASA Astrophysics Data System (ADS)

    Vaseashta, Ashok

    2005-03-01

    A priori detection of pathogens in food and water has become a subject of paramount importance. Several recent incidents have resulted in the government passing stringent regulations for tolerable amounts of contamination of food products. Identification and/or monitoring of bacterial contamination in food are critical. The conventional methods of pathogen detection require time-consuming steps to arrive disembark at meaningful measurement in a timely manner as the detection time exceeds the time in which perishable food recycles through the food chain distribution. The aim of this presentation is to outline surface plasmon resonance (SPR) and atomic force microscopy (AFM) as two methods for fast detect6ion of pathogens. Theoretical basis of SPR and experimental results of SPR and AFM on E. coli O157:H7 and prion are presented.

  14. Selectivity and the production of experimental results.

    NASA Astrophysics Data System (ADS)

    Franklin, A.

    1998-12-01

    The author studies possible relations between the application of selection criteria in analyzing and interpreting the results of physical experiments and the mental preconceptions and expectations of the experimenters. He presents a detailed account of five famous cases of purported experimental results and the controversies following their publication. These cases include Joseph Weber's 1969 claim to have detected gravitational radiation - possibly originating in the center of the Milky Way, and the controversy arising from the 1985 "detection" of the 17 keV (heavy) neutrino by Simpson. Extensive bibliographical references are given for each case.

  15. Experimental Results in DIS from Jefferson Laboratory

    SciTech Connect

    Sebastian Kuhn

    2009-10-01

    We are summarizing the experimental program of Jefferson Lab (Thomas Jefferson National Accelerator Facility in Newport News, VA) in deep inelastic electron scattering. We show recent results and discuss future plans for both the present 6 GeV era and the 12 GeV energy-upgraded facility.

  16. Imaging resolution of AFM with probes modified with FIB.

    PubMed

    Skibinski, J; Rebis, J; Wejrzanowski, T; Rozniatowski, K; Pressard, K; Kurzydlowski, K J

    2014-11-01

    This study concerns imaging of the structure of materials using AFM tapping (TM) and phase imaging (PI) mode, using probes modified with focused ion beam (FIB). Three kinds of modifications were applied - thinning of the cantilever, sharpening of the tip and combination of these two modifications. Probes shaped in that way were used for AFM investigations with Bruker AFM Nanoscope 8. As a testing material, titanium roughness standard supplied by Bruker was used. The results show that performed modifications influence the oscillation of the probes. In particular thinning of the cantilever enables one to acquire higher self-resonant frequencies, which can be advantageous for improving the quality of imaging in PI mode. It was found that sharpening the tip improves imaging resolution in tapping mode, which is consistent with existing knowledge, but lowered the quality of high frequency topography images. In this paper the Finite Element Method (FEM) was used to explain the results obtained experimentally. PMID:25080273

  17. Microwave radiometry for humanitarian demining: experimental results

    NASA Astrophysics Data System (ADS)

    Johnson, Joel T.; Kim, Hyunjin; Wiggins, David R.; Cheon, Yonghun

    2002-08-01

    Previous modeling studies have indicated that a multi-frequency radiometer could prove advantageous for humanitarian demining due to the oscillatory patterns in brightness temperature versus frequency that would be observed in the presence of a sub-surface target. Initial experimental results are reported in this paper from a multi-frequency radiometer (MFRAD) system operating at 19 frequencies in the 2.1-6.5 GHz band. The basic design of MFRAD is reviewed, and the calibration and noise background removal procedures discussed. Experimental results with sub-surface metallic and styrofoam targets are then provided that demonstrate the predicted oscillatory behavior. An FFT-based detection algorithm is also described and applied to measured data. Further plans for experiments and tests with this system are also detailed.

  18. PDX experimental results in FY82

    SciTech Connect

    Kaye, S.M.; Bell, M.; Bol, K.; Bitter, M.; Buchenauer, D.; Budny, R.; Brau, K.; Crowley, T.; Davis, S.; Dylla, H.

    1983-08-01

    This report presents a detailed summary of the major experimental results of PDX in FY82 and represents the efforts of the entire PDX group. Topics covered include ..beta..-scaling and fishbone studies, fluctuations, disruptions, impurities and impurity transport, power handling, limiter conditioning, edge studies, plasma fueling, counter-injection, and diagnostic development. A less detailed version will appear as the FY82 PDX contribution to the PPPL Annual Report.

  19. Experimental Results for Space-Wire-D

    NASA Astrophysics Data System (ADS)

    Parkes, Steve; Gibson, David; Ferrer, Albert

    2015-09-01

    SpaceWire-D is a deterministic extension to SpaceWire that uses time-division multiplexing to schedule traffic within time-slots. It allows a single SpaceWire network to be used for both time-critical avionics control applications and asynchronous payload data-handling simultaneously using existing SpaceWire technology. In this paper we describe the services of SpaceWire-D and present experimental results for each service.

  20. Qplus AFM driven nanostencil.

    PubMed

    Grévin, B; Fakir, M; Hayton, J; Brun, M; Demadrille, R; Faure-Vincent, J

    2011-06-01

    We describe the development of a novel setup, in which large stencils with suspended silicon nitride membranes are combined with atomic force microscopy (AFM) regulation by using tuning forks. This system offers the possibility to perform separate AFM and nanostencil operations, as well as combined modes when using stencil chips with integrated tips. The flexibility and performances are demonstrated through a series of examples, including wide AFM scans in closed loop mode, probe positioning repeatability of a few tens of nanometer, simultaneous evaporation of large (several hundred of micron square) and nanoscopic metals and fullerene patterns in static, multistep, and dynamic modes. This approach paves the way for further developments, as it fully combines the advantages of conventional stenciling with the ones of an AFM driven shadow mask. PMID:21721701

  1. Tuning the resonance of a photonic crystal microcavity with an AFM probe.

    PubMed

    Märki, Iwan; Salt, Martin; Herzig, Hans Peter

    2006-04-01

    We present theoretical and experimental results on switching and tuning of a two-dimensional photonic crystal resonant microcavity by means of a silicon AFM tip, probing the highly localized optical field in the vicinity of the cavity. On-off switching and modulation of the transmission signal in the kHz range is achieved by bringing an AFM tip onto the center of the microcavity, inducing a damping effect on the transmission resonance. Tuning of the resonant wavelength in the order of several nanometers becomes possible by inserting the AFM tip into one of the holes of the Bragg mirror forming the microcavity in the propagation direction. PMID:19516436

  2. Fuel-rich, catalytic reaction experimental results

    NASA Technical Reports Server (NTRS)

    Rollbuhler, R. James

    1991-01-01

    Future aeropropulsion gas turbine combustion requirements call for operating at very high inlet temperatures, pressures, and large temperature rises. At the same time, the combustion process is to have minimum pollution effects on the environment. Aircraft gas turbine engines utilize liquid hydrocarbon fuels which are difficult to uniformly atomize and mix with combustion air. An approach for minimizing fuel related problems is to transform the liquid fuel into gaseous form prior to the completion of the combustion process. Experimentally obtained results are presented for vaporizing and partially oxidizing a liquid hydrocarbon fuel into burnable gaseous components. The presented experimental data show that 1200 to 1300 K reaction product gas, rich in hydrogen, carbon monoxide, and light-end hydrocarbons, is formed when flowing 0.3 to 0.6 fuel to air mixes through a catalyst reactor. The reaction temperatures are kept low enough that nitrogen oxides and carbon particles (soot) do not form. Results are reported for tests using different catalyst types and configurations, mass flowrates, input temperatures, and fuel to air ratios.

  3. Superspreading: molecular dynamics simulations and experimental results

    NASA Astrophysics Data System (ADS)

    Theodorakis, Panagiotis; Kovalchuk, Nina; Starov, Victor; Muller, Erich; Craster, Richard; Matar, Omar

    2015-11-01

    The intriguing ability of certain surfactant molecules to drive the superspreading of liquids to complete wetting on hydrophobic substrates is central to numerous applications that range from coating flow technology to enhanced oil recovery. Recently, we have observed that for superspreading to occur, two key conditions must be simultaneously satisfied: the adsorption of surfactants from the liquid-vapor surface onto the three-phase contact line augmented by local bilayer formation. Crucially, this must be coordinated with the rapid replenishment of liquid-vapor and solid-liquid interfaces with surfactants from the interior of the droplet. Here, we present the structural characteristics and kinetics of the droplet spreading during the different stages of this process, and we compare our results with experimental data for trisiloxane and poly oxy ethylene surfactants. In this way, we highlight and explore the differences between surfactants, paving the way for the design of molecular architectures tailored specifically for applications that rely on the control of wetting. EPSRC Platform Grant MACIPh (EP/L020564/).

  4. An overview of STAR experimental results

    NASA Astrophysics Data System (ADS)

    Xu, Nu

    2014-11-01

    With large acceptance and excellent particle identification, STAR is one of the best mid-rapidity collider experiments for studying high-energy nuclear collisions. The STAR experiment provides full information on initial conditions, properties of the hot and dense medium as well as the properties at freeze-out. In Au+Au collisions at √{sNN} = 200 GeV, STAR's focus is on the nature of the sQGP produced at RHIC. In order to explore the properties of the QCD phase diagram, since 2010, the experiment has collected sizable data sets of Au+Au collisions at the lower collision energy region where the net-baryon density is large. At the 2014 Quark Matter Conference, the STAR experiment made 16 presentations that cover physics topics including collective dynamics, electromagnetic probes, heavy-flavor, initial state physics, jets, QCD phase diagram, thermodynamics and hadron chemistry, and future experimental facilities, upgrades, and instrumentation[1]. In this overview we will highlight a few results from the STAR experiment, especially those from the recent measurements of the RHIC beam energy scan program. At the end, instead of a summary, we will discuss STAR's near future physics programs at RHIC.

  5. VALIDATION DATA FOR PHOTOCHEMICAL MECHANISMS: EXPERIMENTAL RESULTS

    EPA Science Inventory

    The smog chamber facility of the University of North Carolina (UNC) was used to provide experimental data for the EPA and atmospheric model developers for testing and validating kinetic mechanisms of photochemical smog formation. In the study, 71 dual-experiments were performed u...

  6. Membrane-based actuation for high-speed single molecule force spectroscopy studies using AFM.

    PubMed

    Sarangapani, Krishna; Torun, Hamdi; Finkler, Ofer; Zhu, Cheng; Degertekin, Levent

    2010-07-01

    Atomic force microscopy (AFM)-based dynamic force spectroscopy of single molecular interactions involves characterizing unbinding/unfolding force distributions over a range of pulling speeds. Owing to their size and stiffness, AFM cantilevers are adversely affected by hydrodynamic forces, especially at pulling speeds >10 microm/s, when the viscous drag becomes comparable to the unbinding/unfolding forces. To circumvent these adverse effects, we have fabricated polymer-based membranes capable of actuating commercial AFM cantilevers at speeds >or=100 microm/s with minimal viscous drag effects. We have used FLUENT, a computational fluid dynamics (CFD) software, to simulate high-speed pulling and fast actuation of AFM cantilevers and membranes in different experimental configurations. The simulation results support the experimental findings on a variety of commercial AFM cantilevers and predict significant reduction in drag forces when membrane actuators are used. Unbinding force experiments involving human antibodies using these membranes demonstrate that it is possible to achieve bond loading rates >or=10(6) pN/s, an order of magnitude greater than that reported with commercial AFM cantilevers and systems. PMID:20054686

  7. Novel Polymer Linkers for Single Molecule AFM Force Spectroscopy

    PubMed Central

    Tong, Zenghan; Mikheikin, Andrey; Krasnoslobodtsev, Alexey; Lv, Zhengjian; Lyubchenko, Yuri L.

    2013-01-01

    Flexible polymer linkers play an important role in various imaging and probing techniques that require surface immobilization, including atomic force microscopy (AFM). In AFM force spectroscopy, polymer linkers are necessary for the covalent attachment of molecules of interest to the AFM tip and the surface. The polymer linkers tether the molecules and provide their proper orientation in probing experiments. Additionally, the linkers separate specific interactions from nonspecific short-range adhesion and serve as a reference point for the quantitative analysis of single molecule probing events. In this report, we present our results on the synthesis and testing of a novel polymer linker and the identification of a number of potential applications for its use in AFM force spectroscopy experiments. The synthesis of the linker is based on the well-developed phosphoramidate (PA) chemistry that allows the routine synthesis of linkers with predetermined lengths and PA composition. These linkers are homogeneous in length and can be terminated with various functional groups. PA linkers with different functional groups were synthesized and tested in experimental systems utilizing different immobilization chemistries. We probed interactions between complementary DNA oligonucleotides; DNA and protein complexes formed by the site-specific binding protein SfiI; and interactions between amyloid peptide (Aβ42). The results of the AFM force spectroscopy experiments validated the feasibility of the proposed approach for the linker design and synthesis. Furthermore, the properties of the tether (length, functional groups) can be adjusted to meet the specific requirements for different force spectroscopy experiments and system characteristics, suggesting that it could be used for a large number of various applications. PMID:23624104

  8. Experimental results of the betatron sum resonance

    SciTech Connect

    Wang, Y.; Ball, M.; Brabson, B.

    1993-06-01

    The experimental observations of motion near the betatron sum resonance, {nu}{sub x} + 2{nu}{sub z} = 13, are presented. A fast quadrupole (Panofsky-style ferrite picture-frame magnet with a pulsed power supplier) producing a betatron tune shift of the order of 0.03 at rise time of 1 {mu}s was used. This quadrupole was used to produce betatron tunes which jumped past and then crossed back through a betatron sum resonance line. The beam response as function of initial betatron amplitudes were recorded turn by turn. The correlated growth of the action variables, J{sub x} and J{sub z}, was observed. The phase space plots in the resonance frame reveal the features of particle motion near the nonlinear sum resonance region.

  9. Experimental rotordynamic coefficient results for honeycomb seals

    NASA Technical Reports Server (NTRS)

    Elrod, David A.; Childs, Dara W.

    1988-01-01

    Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

  10. Adaptive structures - Test hardware and experimental results

    NASA Technical Reports Server (NTRS)

    Wada, Ben K.; Fanson, James L.; Chen, Gun-Shing; Kuo, Chin-Po

    1990-01-01

    The facilities and procedures used at JPL to test adaptive structures such as the large deployable reflector (LDR) are described and preliminary results are reported. The applications of adaptive structures in future NASA missions are outlined, and the techniques which are employed to modify damping, stiffness, and isolation characteristics, as well as geometric changes, are listed. The development of adaptive structures is shown to be effective as a result of new actuators and sensors, and examples are listed for categories such as fiber optics, shape-memory materials, piezoelectrics, and electrorheological fluids. Some ground test results are described for laboratory truss structures and truss test beds, which are shown to be efficient and easy to assemble in space. Adaptive structures are shown to be important for precision space structures such as the LDR, and can alleviate ground test requirements.

  11. The Humanoid Robot LOLA—Experimental Results

    NASA Astrophysics Data System (ADS)

    Favot, V.; Schwienbacher, M.; Buschmann, T.; Lohmeier, S.; Ulbrich, H.

    2010-09-01

    With the experience gathered during the development and construnction of the robot JOHNNIE, a new humanoid robot LOLA was built. Goal of this project is to realize a fast, human-like walking. Different aspects of this complex mechatronic system and the first experiments results are presented. The lightweight construction and the custom build multi-sensory joint drives with high torque brushless motors are introduced. The new decentralized electronic control/sensing network is also discuss as well as the simulation environment, the trajectory planning algorithm and the stabilizing walking control. Finally the first experiments result are presented.

  12. Numerical taxonomy on data: Experimental results

    SciTech Connect

    Cohen, J.; Farach, M.

    1997-12-01

    The numerical taxonomy problems associated with most of the optimization criteria described above are NP - hard [3, 5, 1, 4]. In, the first positive result for numerical taxonomy was presented. They showed that if e is the distance to the closest tree metric under the L{sub {infinity}} norm. i.e., e = min{sub T} [L{sub {infinity}} (T-D)], then it is possible to construct a tree T such that L{sub {infinity}} (T-D) {le} 3e, that is, they gave a 3-approximation algorithm for this problem. We will refer to this algorithm as the Single Pivot (SP) heuristic.

  13. Experimental results on constructed wetland pilot system.

    PubMed

    González, J M; Ansola, G; Luis, E

    2001-01-01

    Research into a constructed wetland for wastewater treatment using M.H.E.A. (Hierarchical Mosaic of Artificial Ecosystems) pilot system was carried out over a vegetative period in 8 different flow and vegetable composition series. The system consisted of a free water pond as a first step working as primary treatment followed by a zone with Typha sp. and surface flow and finally a woody zone with a subsurface flow and planted with ligneous species (Salixsp., Populus sp., Fraxinus sp. and Alnus sp.). Removal efficiency in the study reflects an optimal result: 80-99% total suspended matter removal, 82-98% organic matter removal, 70-98% nutrients removal and up to 99.9% faecal bacterial disinfecting. Effluent characteristics were in accordance with European Union legislation criteria for wastewater treatment systems. PMID:11804123

  14. Nulling interferometry: symmetry requirements and experimental results

    NASA Astrophysics Data System (ADS)

    Serabyn, Eugene

    2000-07-01

    This paper provides a derivation from first principles of the stringent symmetry and stability requirements which deep stellar nulling demands, and also includes a brief status report on recent nulling results obtained with the Jet Propulsion Laboratory's fiber-coupled rotational-shearing interferometer. To date, the deepest transient nulls obtained (at red wavelengths) are 2 X 10-6 with a laser diode source, and 1.4 X 10-5 with a single- polarization thermal white-light source filtered to provide an 18% passband. In addition, both the laser and white light nulls have been stabilized to the 10-4 level. This visible wavelength laboratory nuller thus meets essentially all of the performance goals for the planned nulling experiment on board NASA's Space Interferometer Mission, with the sole exception of dual-polarization operation.

  15. Reactor-pumped laser experimental results

    SciTech Connect

    Hebner, G.A.; Hays, G.N.

    1994-12-31

    Reactor pumped lasers have the potential to be scaled to multi-megawatt power levels with long run times. In proposed designs, the laser will be capable of output powers of several megawatts of power for run times of several hours. Such a laser would have many diverse applications such as material processing, space debris removal and power beaming to geosynchronous satellites or the moon. However, before such systems can be designed, fundamental laser parameters such as small signal gain, saturation intensity and efficiency must be determined over a wide operational parameter space. The authors have recently measured fundamental laser parameters for a selection of nuclear pumped visible and near IR laser transitions in atomic neon, argon and xenon. An overview of the results of this investigation will be presented.

  16. Experimental results from the TFTR tokamak

    SciTech Connect

    Hawryluk, R.J.; Arunasalam, V.; Bell, J.D.; Bell, M.G.; Bitter, M.; Blanchard, W.R.; Bloody, F.; Bretz, N.; Budny, R.; Bush, C.E.

    1986-10-01

    Recent experiments on TFTR have extended the operating regime of TFTR in both ohmic- and neutral-beam-heated discharges. The TFTR tokamak has reached its original machine design specifications (I/sub p/ = 2.5 MA and B/sub T/ = 5.2 T). Initial neutral-beam-heating experiments used up to 6.3 MW of deuterium beams. With the recent installation of two additional beamlines, the power has been increased up to 11 MW. A deuterium pellet injector was used to increase the central density to 2.5 x 10/sup 20/ m/sup -3/ in high current discharges. At the opposite extreme, by operating at low plasma current (I/sub p/ approx. 0.8 MA) and low density (anti n/sub e/ approx. 1 x 10/sup 19/ m/sup -3/), high ion temperatures (9 +- 2 keV) and rotation speeds (7 x 10/sup 5/ m/s) have been achieved during injection. In addition, plasma compression experiments have demonstrated acceleration of beam ions from 82 keV to 150 keV, in accord with expectations. The wide operating range of TFTR, together with an extensive set of diagnostics and a flexible control system, has facilitated transport and scaling studies of both ohmic- and neutral-beam-heated discharges. The results of these confinement studies are presented.

  17. Overview of the initial NSTX experimental results

    NASA Astrophysics Data System (ADS)

    Ono, M.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W.; Darrow, D. S.; Fredrickson, E. D.; Gates, D. A.; Grisham, L. R.; Hosea, J. C.; Johnson, D. W.; Kaita, R.; Kaye, S. M.; Kubota, S.; Kugel, H. W.; LeBlanc, B. P.; Maingi, R.; Maqueda, R.; Mazzucato, E.; Menard, J.; Mueller, D.; Nelson, B. A.; Neumeyer, C.; Paoletti, F.; Paul, S. F.; Peng, Y.-K. M.; Ramakrishnan, S.; Raman, R.; Ryan, P. M.; Sabbagh, S. A.; Skinner, C. H.; Stevenson, T.; Stutman, D.; Swain, D. W.; Synakowski, E. J.; Taylor, G.; Von Halle, A.; Wilgen, J.; Williams, M.; Wilson, J. R.; Zweben, S. J.; Ackers, R.; Barry, R. E.; Bers, A.; Bialek, J. M.; Bonoli, P. T.; Carter, M. D.; Chrzanowski, J.; Davis, W.; Doyle, E. J.; Dudek, L.; Efthimion, P. C.; Ellis, R.; Ferron, J. R.; Finkenthal, M.; Fredd, E.; Gibney, T.; Goldston, R. J.; Hatcher, R. E.; Hawryluck, R. J.; Hayashiya, H.; Hill, K. W.; Jarboe, T. R.; Jardin, S. C.; Ji, H.; Kalish, M.; La Marche, P.; Lao, L. L.; Lee, K. C.; Levinton, F. M.; Luhmann, N. C.; Majeski, R.; Manickam, J.; Marsala, R.; Mau, T. K.; McCormack, B.; Medley, S. S.; Menon, M. M.; Mitarai, O.; Nagata, M.; Nishino, N.; Oliaro, G.; Park, H. K.; Parsells, R.; Pearson, G.; Peebles, T.; Phillips, C. K.; Pinsker, R.; Porter, G. D.; Ram, A. K.; Robinson, J.; Roney, P.; Roquemore, A. L.; Rosenberg, A.; Schaffer, M.; Shiraiwa, S.; Sichta, P.; Stotler, D.; Stratton, B. C.; Takase, Y.; Wampler, W. R.; Wurden, G. A.; Xu, X. Q.; Yang, J. G.; Zeng, L.; Zhu, W.

    2001-10-01

    The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 MA on 14 December 1999. The planned plasma shaping parameters, elongation κ = 1.6-2.2 and triangularity δ = 0.2-0.4, were achieved in inner wall limited, and single null and double null diverted configurations. The coaxial helicity injection (CHI) and high harmonic fast wave (HHFW) experiments were also initiated. CHI current of 27 kA produced up to 260 kA toroidal current without using an ohmic solenoid. With the injection of 2.3 MW of HHFW power, using 12 antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a central density of 3.5 × 1013 cm-3, increasing the plasma energy to 59 kJ and the toroidal β, βT, to 10%. The NBI system commenced operation in September 2000. The initial results with two ion sources (PNBI = 2.8 MW) show good heating, producing a total plasma stored energy of 90 kJ corresponding to βT approx 18% at a plasma current of 1.1 MA.

  18. Liquid hydrogen for automotive vehicles - Experimental results

    SciTech Connect

    Peschka, W.

    1981-01-01

    A BMW-518 has been adapted for LH2-fuel, representing the first LH2-fueled car in Europe. This is a joint program between the German Research and Testing Laboratory for Aeronautics and the Research Institute for Motor-Transport Service and Automotive Engines at the University of Stuttgart. The program was established for demonstration of successful car-operation and and the safe handling of LH2-fuel during car operation and refueling. Based on earlier papers, more recent test results and experiences are reported about car operation and engine performance. The car has been driven over an accumulated distance of about 1800 km on a test track. The test track consists of a loop of about 2.5 km in length, including a proper combination of straight level sections, curved sections and ascending sections. In order to demonstrate a safe liquid hydrogen refueling procedure that could also be used by untrained people, a semiautomatic computer operated refueling station has been developed. This refueling station is in successful operation.

  19. Overview of the Initial NSTX Experimental Results

    SciTech Connect

    M. Ono; M. Bell; R. E. Bell; T. Bigelow; M. Bitter; et al

    2000-11-16

    The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 million amperes on December 14, 1999. The planned plasma shaping parameters, k = 1.6 {+-} 2.2 and d = 0.2 {+-} 0.4, were achieved in inner limited, single null and double null configurations. The CHI (Coaxial Helicity Injection) and HHFW (High Harmonic Fast Wave) experiments were also initiated. A CHI injected current of 27 kA produced up to 260 kA of toroidal current without using an ohmic solenoid. With an injection of 2.3 MW of HHFW power, using twelve antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a centraldensity of 3.5 x 1013 cm-3 increasing the plasma energy to 59 kJ and the toroidal beta, bT to 10 %. Finally, the NBI system commenced operatio n in Sept. 2000. The initial results with two ion sources (PNBI = 2.8 MW) shows good heating, producing a total plasma stored energy of 90 kJ corresponding to bT = 18 % at a plasma current of 1.1 MA

  20. Buckling and post-buckling of stressed straight-sided wrinkles: experimental AFM observations of bubbles formation and finite element simulations

    SciTech Connect

    Parry, G.; Coupeau, C.; Colin, J.; Cimetiere, A.; Grilhe, J

    2004-08-02

    The transition from a straight-sided wrinkle to a periodic distribution of bubbles has been experimentally studied by atomic force microscopy for a stressed thin film relying on a substrate. A non-linear numerical analysis has been carried out and the different steps of the wrinkle evolution have been characterized. Different parameters of the buckling structure such as the shape parameter of the blisters and the stress relaxation have been determined and compared to the experimental data. The comparison of elastic strain energies has highlighted the possible coexistence of structures with different wavelengths.

  1. A Batch Fabricated SECM-AFM Probe

    NASA Astrophysics Data System (ADS)

    Dobson, P. S.; Macpherson, J. V.; Holder, M.; Weaver, J. M. R.

    2003-12-01

    A scheme for the fabrication of combined Scanning Electrochemical Microscopy — Atomic Force Microscopy (SECM-AFM) probes is presented for both silicon nitride and silicon cantilevers. The advantages over exsisting methods used for their production is explained. The process flow is described and initial results from electrodeposition of silver are presented.

  2. A sub-50 nm three-step height sample for AFM calibration

    NASA Astrophysics Data System (ADS)

    Yang, Shuming; Li, Changsheng; Wang, Chenying; Jiang, Zhuangde

    2014-12-01

    In this paper, a sub-50 nm three-step height sample was made for vertical calibration of atomic force microscopy (AFM) and a new step height evaluation algorithm based on polynomial fitting is discussed. The influences of AFM artefacts such as particles, image bow and high-order errors on step height were studied. The experimental results showed that the polynomial order p2 and threshold t were not critical factors. However, the increment Δh and the polynomial order p used in the calculation of optimal shifting distance were important and must be carefully considered. Δh = 0.1 nm and p ≥ 4 were determined to get a stable step height. The sample had small roughness and good uniformity. It has the potential to serve as a high quality step height standard sample for AFM calibration.

  3. Results from an experimental railgun system: ERGS-1A

    NASA Astrophysics Data System (ADS)

    Thio, Y. C.; Clark, G. A.; Bedford, A. J.

    1983-03-01

    One phase of the Materials Research Laboratories (MRL) Experimental Rail-gun System (ERGS-1) program is for experimentation in the energy range 50 to 500 kJ. The first, and highly successful, ERGS-1 experiment was conducted in September 1981 using a barrel segment 200 mm in length. Comparison of experimental results with the theory developed by Thio yielded good agreement, particularly the values for capacitor voltage, current through the rails, plasma voltage and muzzle velocity of the projectile.

  4. Conservative and dissipative tip-sample interaction forces probed with dynamic AFM

    NASA Astrophysics Data System (ADS)

    Gotsmann, B.; Seidel, C.; Anczykowski, B.; Fuchs, H.

    1999-10-01

    The conservative and dissipative forces between tip and sample of a dynamic atomic force microscopy (AFM) were investigated using a combination of computer simulations and experimental AFM data obtained by the frequency modulation technique. In this way it became possible to reconstruct complete force versus distance curves and damping coefficient versus distance curves from experimental data without using fit parameters for the interaction force and without using analytical interaction models. A comparison with analytical approaches is given and a way to determine a damping coefficient curve from experimental data is proposed. The results include the determination of the first point of repulsive contact of a vibrating tip when approaching a sample. The capability of quantifying the tip-sample interaction is demonstrated using experimental data obtained with a silicon tip and a mica sample in UHV.

  5. Microrheology using a custom-made AFM

    NASA Astrophysics Data System (ADS)

    Kosgodagan Acharige, Sebastien; Benzaquen, Michael; Steinberger, Audrey

    In the past few years, a new method was developed to measure local properties of liquids (X. Xiong et al., Phys. Rev. E 80, 2009). This method consists of gluing a micron-sized glass fiber at the tip of an AFM cantilever and probing the liquid with it. In ENS Lyon, this method was perfected (C. Devailly et al., EPL, 106 5, 2014) with the help of an interferometer developped in the same laboratory (L. Bellon et al., Opt. Commun. 207 49, 2002 and P. Paolino et al., Rev. Sci. Instrum. 84, 2013), which background noise can reach 10-14 m /√{ Hz } . This method allows us to measure a wide range of viscosities (1 mPa . s to 500 mPa . s) of transparent and opaque fluids using a small sample volume ( 5 mL). In this presentation, I will briefly describe the interferometer developped in ENS Lyon, then explain precisely the microrheology measurements and then compare the experimental results to a model developped by M. Benzaquen. This work is supported financially by the ANR project NANOFLUIDYN (Grant Number ANR-13-BS10-0009).

  6. Manufacturing process of nanofluidics using afm probe

    NASA Astrophysics Data System (ADS)

    Karingula, Varun Kumar

    A new process for fabricating a nano fluidic device that can be used in medical application is developed and demonstrated. Nano channels are fabricated using a nano tip in indentation mode on AFM (Atomic Force Microscopy). The nano channels are integrated between the micro channels and act as a filter to separate biomolecules. Nano channels of 4 to7 m in length, 80nm in width, and at varying depths from 100nm to 850 nm allow the resulting device to separate selected groups of lysosomes and other viruses. Sharply developed vertical micro channels are produced from a deep reaction ion etching followed by deposition of different materials, such as gold and polymers, on the top surface, allowing the study of alternative ways of manufacturing a nanofluidic device. PDMS (Polydimethylsiloxane) bonding is performed to close the top surface of the device. An experimental setup is used to test and validate the device by pouring fluid through the channels. A detailed cost evaluation is conducted to compare the economical merits of the proposed process. It is shown that there is a 47:7% manufacturing time savings and a 60:6% manufacturing cost savings.

  7. Particle deformation induced by AFM tapping under different setpoint voltages

    NASA Astrophysics Data System (ADS)

    Wu, Chung-Lin; Farkas, Natalia; Dagata, John A.; He, Bo-Ching; Fu, Wei-En

    2014-09-01

    The measured height of polystyrene nanoparticles varies with setpoint voltage during atomic force microscopy (AFM) tapping-mode imaging. Nanoparticle height was strongly influenced by the magnitude of the deformation caused by the AFM tapping forces, which was determined by the setpoint voltage. This influence quantity was studied by controlling the operational AFM setpoint voltage. A test sample consisting of well-dispersed 60-nm polystyrene and gold nanoparticles co-adsorbed on poly-l-lysine-coated mica was studied in this research. Gold nanoparticles have not only better mechanical property than polystyrene nanoparticles, but also obvious facets in AFM phase image. By using this sample of mixed nanoparticles, it allows us to confirm that the deformation resulted from the effect of setpoint voltage, not noise. In tapping mode, the deformation of polystyrene nanoparticles increased with decreasing setpoint voltage. Similar behavior was observed with both open loop and closed loop AFM instruments.

  8. Effective AFM cantilever tip size: methods for in-situ determination

    NASA Astrophysics Data System (ADS)

    Maragliano, Carlo; Glia, Ayoub; Stefancich, Marco; Chiesa, Matteo

    2015-01-01

    In atomic force microscopy (AFM) investigations, knowledge of the cantilever tip radius R is essential for the quantitative interpretation of experimental observables. Here we propose two techniques to rapidly quantify in-situ the effective tip radius of AFM probes. The first method is based on the strong dependency of the minimum value of the free amplitude required to observe a sharp transition from attractive to repulsive force regimes on the AFM probe radius. Specifically, the sharper the tip, the smaller the value of free amplitude required to observe such a transition. The key trait of the second method is to treat the tip-sample system as a capacitor. Provided with an analytical model that takes into account the geometry of the tip-sample’s capacitance, one can quantify the effective size of the tip apex fitting the experimental capacitance versus distance curve. Flowchart-like algorithms, easily implementable on any hardware, are provided for both methods, giving a guideline to AFM practitioners. The methods’ robustness is assessed over a wide range of probes of different tip radii R (i.e. 4 < R < 50 nm) and geometries. Results obtained from both methods are compared with the nominal values given by manufacturers and verified by acquiring scanning electron microscopy images. Our observations show that while both methods are reliable and robust over the range of tip sizes tested, the critical amplitude method is more accurate for relatively sharp tips (4 nm < R < 10 nm).

  9. CDSEM AFM hybrid metrology for the characterization of gate-all-around silicon nano wires

    NASA Astrophysics Data System (ADS)

    Levi, Shimon; Schwarzband, Ishai; Weinberg, Yakov; Cornell, Roger; Adan, Ofer; Cohen, Guy M.; Gignac, Lynne; Bangsaruntip, Sarunya; Hand, Sean; Osborne, Jason; Feinstein, Adam

    2014-04-01

    In an ongoing study of the physical characterization of Gate-All-Around Silicon Nano Wires (GAASiNW), we found that the thin, suspended wires are prone to buckling as a function of their length and diameter. This buckling takes place between the fixed source and drain regions of the suspended wire, and can affect the device performance and therefore must be studied and controlled. For cylindrical SiNW, theory predicts that buckling has no directional preference. However, 3D CDSEM measurement results indicated that cylindrical wires prefer to buckle towards the wafer. To validate these results and to determine if the electron beam or charging is affecting our observations, we used 3D-AFM measurements to evaluate the buckling. To assure that the CDSEM and 3D-AFM measure the exact same locations, we developed a design based recipe generation approach to match the 3D-AFM and CDSEM coordinate systems. Measuring the exact same sites enables us to compare results and use 3D-AFM data to optimize CDSEM models. In this paper we will present a hybrid metrology approach to the characterization of GAASiNW for sub-nanometer variations, validating experimental results, and proposing methods to improve metrology capabilities.

  10. Experimental study of the Timoshenko beam theory predictions: Further results

    NASA Astrophysics Data System (ADS)

    Monsivais, G.; Díaz-de-Anda, A.; Flores, J.; Gutiérrez, L.; Morales, A.

    2016-08-01

    In a previous paper (2012) we presented experimental results proving that the critical frequency fC predicted by Timoshenko beam theory indeed exists. We also showed that for frequencies f smaller than fC the spectrum is formed by almost equally spaced levels whereas for f >fC the spectrum consists of pairs of eigenvalues very close to each other as predicted by numerical solutions of Timoshenko's equation: we shall refer to them as Timoshenko doublets. In this work we measure for the first time experimental dispersion relations. For this purpose it was necessary to obtain normal-mode amplitudes with a high precision, which was done with a new experimental setup developed by us. We found that experimental dispersion relations coincide very well with theoretical predictions. Furthermore, we provide an explanation of Timoshenko doublets.

  11. Ultrasonic radiation from wedges of cubic profile: Experimental results.

    PubMed

    Anderson, Brian E; Remillieux, Marcel C; Le Bas, Pierre-Yves; Ulrich, T J; Pieczonka, Lukasz

    2015-12-01

    This paper presents experimental results demonstrating the increase in ultrasonic radiation obtained from a wedge of cubic profile relative to a plate of uniform thickness. The wedge of cubic profile provides high efficiency sound radiation matching layer from a mounted piezoelectric transducer into the surrounding air. Previous research on structures with indentations of power-law profile has focused on vibration mitigation using the so called "acoustic black-hole" effect, whereas here such structures are used to enhance ultrasonic radiation. The work provides experimental verification of the numerical results of Remillieux et al. (2014). PMID:26166628

  12. Analysis of AFM cantilever dynamics close to sample surface

    NASA Astrophysics Data System (ADS)

    Habibnejad Korayem, A.; Habibnejad Korayem, Moharam; Ghaderi, Reza

    2013-07-01

    For imaging and manipulation of biological specimens application of atomic force microscopy (AFM) in liquid is necessary. In this paper, tapping-mode AFM cantilever dynamics in liquid close to sample surface is modeled and simulated by well defining the contact forces. The effect of cantilever tilting angle has been accounted carefully. Contact forces have some differences in liquid in comparison to air or vacuum in magnitude or formulation. Hydrodynamic forces are also applied on the cantilever due to the motion in liquid. A continuous beam model is used with its first mode and forward-time simulation method for simulation of its hybrid dynamics and the frequency response and amplitude versus separation diagrams are extracted. The simulation results show a good agreement with experimental results. The resonance frequency in liquid is so small in comparison to air due to additional mass and also additional damping due to the viscosity of the liquid around. The results show that the effect of separation on free vibration amplitude is great. Its effect on resonance frequency is considerable too.

  13. Comparison of calculated and experimental results of fragmenting cylinder experiments

    SciTech Connect

    WILSON,L.T.; REEDAL,D.R.; KIPP,MARLIN E.; MARTINEZ,REINA R.; GRADY,D.E.

    2000-06-02

    The Grady-Kipp fragmentation model provides a physically based method for determining the fracture and breakup of materials under high loading rates. Recently, this model has been implemented into the CTH Shock Physics Code and has been used to simulate several published experiments. Materials studied in this paper are AerMet 100 steel and a 90% tungsten alloy. The experimental geometry consists of a right circular cylinder filled with an explosive main charge that is initiated at its center. The sudden expansion of the resulting detonation products causes fracture of the cylinder. Strain rates seen in the cylinder are on the order of 10{sup 4} s{sup {minus}1}. The average fragment sizes calculated with the Grady-Kipp fragmentation model successfully replicate the mean fragment size obtained from the experimental fragment distribution. When Poisson statistics are applied to the calculated local average fragment sizes, good correlation is also observed with the shape of the experimental cumulative fragment distribution. The experimental fragmentation results, CTH numerical simulations, and correlation of these numerical results with the experimental data are described.

  14. PREFACE: Non-contact AFM Non-contact AFM

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.; Morita, Seizo

    2012-02-01

    This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

  15. Adhesion forces in AFM of redox responsive polymer grafts: Effects of tip hydrophilicity

    NASA Astrophysics Data System (ADS)

    Feng, Xueling; Kieviet, Bernard D.; Song, Jing; Schön, Peter M.; Vancso, G. Julius

    2014-02-01

    The adherence between silicon nitride AFM tips and redox-active poly(ferrocenylsilanes) (PFS) grafts on gold was investigated by electrochemical AFM force spectroscopy. Before the adhesion measurements silicon nitride AFM probes were cleaned with organic solvents (acetone and ethanol) or piranha solution. Interestingly, these different AFM tip cleaning procedures drastically affected the observed adhesion forces. Water contact angle measurements on the corresponding AFM probe chips showed that piranha treatment resulted in a significant increase of AFM probe chip surface hydrophilicity compared to the organic solvent treatment. Obviously this hydrophilicity change caused drastic, even opposite changes in the tip-PFS adhesive force measurement upon electrode potential change to reversibly oxidize and reduce the PFS grafts. Our findings are of pivotal importance for AFM tip adhesion measurements utilizing standard silicon nitride AFM tips. Probe hydrophilicity must be carefully taken into consideration and controlled.

  16. Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

    PubMed Central

    Castanié, Fabien; Nony, Laurent; Gauthier, Sébastien

    2012-01-01

    Summary Background: Characterization at the atomic scale is becoming an achievable task for FM-AFM users equipped, for example, with a qPlus sensor. Nevertheless, calculations are necessary to fully interpret experimental images in some specific cases. In this context, we developed a numerical AFM (n-AFM) able to be used in different modes and under different usage conditions. Results: Here, we tackled FM-AFM image calculations of three types of graphitic structures, namely a graphite surface, a graphene sheet on a silicon carbide substrate with a Si-terminated surface, and finally, a graphene nanoribbon. We compared static structures, meaning that all the tip and sample atoms are kept frozen in their equilibrium position, with dynamic systems, obtained with a molecular dynamics module allowing all the atoms to move freely during the probe oscillations. Conclusion: We found a very good agreement with experimental graphite and graphene images. The imaging process for the deposited nanoribbon demonstrates the stability of our n-AFM to image a non-perfectly planar substrate exhibiting a geometrical step as well as a material step. PMID:22497004

  17. Raman and AFM study of gamma irradiated plastic bottle sheets

    SciTech Connect

    Ali, Yasir; Kumar, Vijay; Dhaliwal, A. S.; Sonkawade, R. G.

    2013-02-05

    In this investigation, the effects of gamma irradiation on the structural properties of plastic bottle sheet are studied. The Plastic sheets were exposed with 1.25MeV {sup 60}Co gamma rays source at various dose levels within the range from 0-670 kGy. The induced modifications were followed by micro-Raman and atomic force microscopy (AFM). The Raman spectrum shows the decrease in Raman intensity and formation of unsaturated bonds with an increase in the gamma dose. AFM image displays rough surface morphology after irradiation. The detailed Raman analysis of plastic bottle sheets is presented here, and the results are correlated with the AFM observations.

  18. AFM Studies of Conformational Changes in Proteins and Peptides

    NASA Astrophysics Data System (ADS)

    Ploscariu, Nicoleta; Sukthankar, Pinakin; Tomich, John; Szoszkiewicz, Robert

    2015-03-01

    Here, we present estimates of molecular stiffness and mechanical energy dissipation factors for some examples of proteins and peptides. The results are obtained from AFM force spectroscopy measurements. To determine molecular stiffness and mechanical energy dissipation factors we developed a model based on measuring several resonance frequencies of an AFM cantilever in contact with either single protein molecule or peptides adsorbed on arbitrary surface. We used compliant AFM cantilevers with a small aspect ratio - a ratio of length to width - in air and in liquid, including biologically relevant phosphate buffered saline medium. Department of Physics.

  19. CSI sensing and control: Analytical and experimental results

    NASA Technical Reports Server (NTRS)

    Junkins, J. L.; Pollock, T. C.; Rahman, Z. H.

    1989-01-01

    Recent work on structural identification and large-angle maneuvers with vibration suppression was presented. The recent work has sought to balance structural and controls analysis activities by involving the analysts directly in the validation and experimental aspects of the research. Some new sensing, actuation, system identification, and control concepts were successfully implemented. An overview of these results is given.

  20. Dual AFM probes alignment based on vision guidance

    NASA Astrophysics Data System (ADS)

    Zhang, Hua-kun; Gao, Si-tian; Lu, Ming-zhen; Wang, Long-long

    2013-10-01

    Atomic force microscope (AFM) with dual probes that operate together can measure both side walls excellently at the same time, which virtually eliminates the prevalent effect of probe width that contributes a large component of uncertainty in measurement results and finally obtains the critical dimension (CD)(e.g. the linewidth) through data synthesis. In calibration process, the dual probes must contact each other in advance, which realizes the alignment in the three dimensions, to establish a zero reference point and ensure the accuracy of measurement. Because nowadays the optical resolution of advanced lens have exceeded micrometer range, and the size of probes is within micro level, it is possible to acquire dual probes images in both horizontal and vertical directions, through which the movement of the probes can be controlled in time. In order to further enhance the alignment precision, sub-pixel edge detection method based on Zernike orthogonal moment is used to obtain relative position between these two probes, which helps the tips alignment attains sub-micron range. Piezoelectric nanopositioning stages calibrated by laser interferometer are used to implement fine movement of the probes to verify the accuracy of the experimental results. To simplify the system, novel self-sensing and self-actuating probe based on a quartz tuning fork combined with a micromachined cantilever is used for dynamic mode AFM. In this case, an external optical detection system is not needed, so the system is simple and small.

  1. Modeling the Interaction between AFM Tips and Pinned Surface Nanobubbles.

    PubMed

    Guo, Zhenjiang; Liu, Yawei; Xiao, Qianxiang; Schönherr, Holger; Zhang, Xianren

    2016-01-26

    Although the morphology of surface nanobubbles has been studied widely with different AFM modes, AFM images may not reflect the real shapes of the nanobubbles due to AFM tip-nanobubble interactions. In addition, the interplay between surface nanobubble deformation and induced capillary force has not been well understood in this context. In our work we used constraint lattice density functional theory to investigate the interaction between AFM tips and pinned surface nanobubbles systematically, especially concentrating on the effects of tip hydrophilicity and shape. For a hydrophilic tip contacting a nanobubble, its hydrophilic nature facilitates its departure from the bubble surface, displaying a weak and intermediate-range attraction. However, when the tip squeezes the nanobubble during the approach process, the nanobubble shows an elastic effect that prevents the tip from penetrating the bubble, leading to a strong nanobubble deformation and repulsive interactions. On the contrary, a hydrophobic tip can easily pierce the vapor-liquid interface of the nanobubble during the approach process, leading to the disappearance of the repulsive force. In the retraction process, however, the adhesion between the tip and the nanobubble leads to a much stronger lengthening effect on nanobubble deformation and a strong long-range attractive force. The trends of force evolution from our simulations agree qualitatively well with recent experimental AFM observations. This favorable agreement demonstrates that our model catches the main intergradient of tip-nanobubble interactions for pinned surface nanobubbles and may therefore provide important insight into how to design minimally invasive AFM experiments. PMID:26751634

  2. Design and experimental results for the S805 airfoil

    SciTech Connect

    Somers, D.M.

    1997-01-01

    An airfoil for horizontal-axis wind-turbine applications, the S805, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  3. Design and experimental results for the S809 airfoil

    SciTech Connect

    Somers, D M

    1997-01-01

    A 21-percent-thick, laminar-flow airfoil, the S809, for horizontal-axis wind-turbine applications, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  4. Experimental results of a predictive neural network HVAC controller

    SciTech Connect

    Jeannette, E.; Assawamartbunlue, K.; Kreider, J.F.; Curtiss, P.S.

    1998-12-31

    Proportional, integral, and derivative (PID) control is widely used in many HVAC control processes and requires constant attention for optimal control. Artificial neural networks offer the potential for improved control of processes through predictive techniques. This paper introduces and shows experimental results of a predictive neural network (PNN) controller applied to an unstable hot water system in an air-handling unit. Actual laboratory testing of the PNN and PID controllers show favorable results for the PNN controller.

  5. Characterizing Cell Mechanics with AFM and Microfluidics

    NASA Astrophysics Data System (ADS)

    Walter, N.; Micoulet, A.; Suresh, S.; Spatz, J. P.

    2007-03-01

    Cell mechanical properties and functionality are mainly determined by the cytoskeleton, besides the cell membrane, the nucleus and the cytosol, and depend on various parameters e.g. surface chemistry and rigidity, surface area and time available for cell spreading, nutrients and drugs provided in the culture medium. Human epithelial pancreatic and mammary cancer cells and their keratin intermediate filaments are the main focus of our work. We use Atomic Force Microscopy (AFM) to study cells adhering to substrates and Microfluidic Channels to probe cells in suspension, respectively. Local and global properties are extracted by varying AFM probe tip size and the available adhesion area for cells. Depth-sensing, instrumented indentation tests with AFM show a clear difference in contact stiffness for cells that are spread of controlled substrates and those that are loosely attached. Microfluidic Channels are utilized in parallel to evaluate cell deformation and ``flow resistance'', which are dependent on channel cross section, flow rate, cell nucleus size and the mechanical properties of cytoskeleton and membrane. The results from the study are used to provide some broad and quantitative assessments of the connections between cellular/subcellular mechanics and biochemical origins of disease states.

  6. Robustness to noise in synchronization of network motifs: Experimental results

    NASA Astrophysics Data System (ADS)

    Buscarino, Arturo; Fortuna, Luigi; Frasca, Mattia; Iachello, Marco; Pham, Viet-Thanh

    2012-12-01

    In this work, we experimentally investigate the robustness to noise of synchronization in all the four-nodes network motifs. The experimental setup consists of four Chua's circuits diffusively coupled in order to implement the six different undirected network motifs that can be obtained with four nodes. In this experimental setup, synchronization in the presence of noise injected in one of the network nodes is investigated and network motifs are compared in terms of the synchronization error obtained. The analysis has been then extended to some selected case studies of networks with five and six nodes. Numerical simulations have been also performed and results in agreement with experiments have been obtained. A correlation between node degree and robustness to noise has been found also in these networks.

  7. Experimental results for a hypersonic nozzle/afterbody flow field

    NASA Technical Reports Server (NTRS)

    Spaid, Frank W.; Keener, Earl R.; Hui, Frank C. L.

    1995-01-01

    This study was conducted to experimentally characterize the flow field created by the interaction of a single-expansion ramp-nozzle (SERN) flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5 Foot Hypersonic Wind Tunnel at the NASA Ames Research Center, in a cooperative experimental program involving Ames and McDonnell Douglas Aerospace. The model design and test planning were performed in close cooperation with members of the Ames computational fluid dynamics (CFD) team for the National Aerospace Plane (NASP) program. This paper presents experimental results consisting of oil-flow and shadow graph flow-visualization photographs, afterbody surface-pressure distributions, rake boundary-layer measurements, Preston-tube skin-friction measurements, and flow field surveys with five-hole and thermocouple probes. The probe data consist of impact pressure, flow direction, and total temperature profiles in the interaction flow field.

  8. Novel Thermoelectric Modules for Cooling Powerful LEDs: Experimental Results

    NASA Astrophysics Data System (ADS)

    Semenyuk, V.; Dekhtiaruk, R.

    2013-07-01

    We present the results of an experimental study of a cooling system based on a novel thermoelectric module specifically designed for thermal management of high-power light-emitting diodes (LEDs). The Seoul Semiconductor LED W724C0 device was chosen for experimental validation of the efficiency of the proposed cooling unit. Two cooling systems with identical heat sinks were tested for comparison: a state-of-the-art one based on an insulated metal substrate-printed circuit board (IMS-PCB), and a system with thermoelectric cooling. The obtained results show that use of thermoelectrics results in a considerable reduction of the LED operating temperature, providing increased light output and greatly increased LED lifetime.

  9. Feedback control of a cupola - concepts and experimental results

    SciTech Connect

    Moore, K.L.; Abdelrahman, M.A.; Larsen, E.; Clark, D.; King, P.

    1998-10-01

    In this paper we present some final results from a research project focused on introducing automatic control to the operation of cupola iron furnaces. The main aim of this research is to improve the operational efficiency and performance of the cupola furnace, an important foundry process used to melt iron. Previous papers have described the development of appropriate control system architectures for the cupola. These results are summarized. Then we describe the experimental results obtained with the U.S. Department of Energy Albany Research Center`s research cupola. First, experimental data is used to calibrate the model, which is taken as a first-order multivariable system with time delay. Then relative gain analysis is used to select loop pairings to be used in a multi-loop controller. The resulting controller pairs meltrate with blast volume, iron temperature with oxygen addition, and carbon composition with percent coke. Special (nonlinear) filters are used to compute meltrate from actual scale readings of the amount of iron produced and to smooth the temperature measurement. The temperature and meltrate loops use single-loop PI control. The composition loop uses a Smith predictor to discount the deadtime associated with mass transport through the furnace. Experimental results validate the conceptual controller design and provide proof-of-concept of the idea of controlling a foundry cupola. Future research directions are discussed, including the concept of an integrated, intelligent industrial process controller, or I{sup 3}PC.

  10. Cellular mechanoadaptation to substrate mechanical properties: contributions of substrate stiffness and thickness to cell stiffness measurements using AFM.

    PubMed

    Vichare, Shirish; Sen, Shamik; Inamdar, Mandar M

    2014-02-28

    Mechanosensing by adherent cells is usually studied by quantifying cell responses on hydrogels that are covalently linked to a rigid substrate. Atomic force microscopy (AFM) represents a convenient way of characterizing the mechanoadaptation response of adherent cells on hydrogels of varying stiffness and thickness. Since AFM measurements reflect the effective cell stiffness, therefore, in addition to measuring real cytoskeletal alterations across different conditions, these measurements might also be influenced by the geometry and physical properties of the substrate itself. To better understand how the physical attributes of the gel influence AFM stiffness measurements of cells, we have used finite element analysis to simulate the indentation of cells of various spreads resting on hydrogels of varying stiffness and thickness. Consistent with experimental results, our simulation results indicate that for well spread cells, stiffness values are significantly over-estimated when experiments are performed on cells cultured on soft and thin gels. Using parametric studies, we have developed scaling relationships between the effective stiffness probed by AFM and the bulk cell stiffness, taking cell and tip geometry, hydrogel properties, nuclear stiffness and cell contractility into account. Finally, using simulated mechanoadaptation responses, we have demonstrated that a cell stiffening response may arise purely due to the substrate properties. Collectively, our results demonstrate the need to take hydrogel properties into account while estimating cell stiffness using AFM indentation. PMID:24651595

  11. Study of relaxation and transport processes by means of AFM based dielectric spectroscopy

    SciTech Connect

    Miccio, Luis A.

    2014-05-15

    Since its birth a few years ago, dielectric spectroscopy studies based on atomic force microscopy (AFM) have gained a growing interest. Not only the frequency and temperature ranges have become broader since then but also the kind of processes that can be studied by means of this approach. In this work we analyze the most adequate experimental setup for the study of several dielectric processes with a spatial resolution of a few nanometers by using force mode AFM based dielectric spectroscopy. Proof of concept experiments were performed on PS/PVAc blends and PMMA homopolymer films, for temperatures ranging from 300 to 400 K. Charge transport processes were also studied by this approach. The obtained results were analyzed in terms of cantilever stray contribution, film thickness and relaxation strength. We found that the method sensitivity is strongly coupled with the film thickness and the relaxation strength, and that it is possible to control it by using an adequate experimental setup.

  12. Charge Measurement of Atoms and Atomic Resolution of Molecules with Noncontact AFM

    NASA Astrophysics Data System (ADS)

    Gross, Leo

    2010-03-01

    Individual gold and silver adatoms [1] and pentacene molecules [2] on ultrathin NaCl films on Cu(111) were investigated using a qPlus tuning fork atomic force microscope (AFM) operated at 5 Kelvin with oscillation amplitudes in the sub-ångstrom regime. Charging a gold adatom by one electron charge increased the force on the AFM tip by a few piconewtons. Employing Kelvin probe force microscopy (KPFM) we also measured the local contact potential difference (LCPD). We observed that the LCPD is shifted depending on the sign of the charge and allows the discrimination of positively charged, neutral, and negatively charged atoms. To image pentacene molecules we modified AFM tips by means of vertical manipulation techniques, i.e. deliberately picking up known atoms and molecules, such as Au, Ag, Cl, CO, and pentacene. Using a CO terminated tip we resolved all individual atoms and bonds within a pentacene molecule. Three dimensional force maps showing the site specific distance dependence above the molecule were extracted. We compared our experimental results with density functional theory (DFT) calculations to gain insight on the physical origin of AFM contrast formation. We found that atomic resolution is only obtained due to repulsive force contributions originating from the Pauli exclusion principle. [4pt] [1] L. Gross, F. Mohn, P. Liljeroth, J. Repp, F. J. Giessibl, G. Meyer, Science 324, 1428 (2009). [0pt] [2] L. Gross, F. Mohn, N. Moll, P. Liljeroth, G. Meyer, Science 325, 1110 (2009).

  13. Ability of Lactobacillus rhamnosus GAF01 to remove AFM1 in vitro and to counteract AFM1 immunotoxicity in vivo.

    PubMed

    Abbès, Samir; Salah-Abbès, Jalila Ben; Sharafi, Hakimeh; Jebali, Rania; Noghabi, Kambiz Akbari; Oueslati, Ridha

    2013-01-01

    Aflatoxin M1 (AFM1) has been detected in many parts of the world both in raw milk and many dairy products, causing great economic losses and human disease. Unfortunately, there are few studies dealing with AFM1 immunotoxicity/interactions with lactic acid bacteria for potential application as a natural preventive agent. The aim of this study was to isolate (from dairy products) food-grade probiotic bacteria able to degrade/bind AFM1 in vitro and evaluate whether the same organism(s) could impart a protective role against AFM1-induced immunotoxicity in exposed Balb/c mice. Bacteria (Lactobacillus plantarum MON03 and L. rhamnosus GAF01) were isolated from Tunisian artisanal butter and then tested for abilities to eliminate AFM1 from phosphate-buffered saline (PBS) and reconstituted milk (containing 0.05, 0.10, and 0.20 µg AFM1/ml) after 0, 6, and 24 h at 37°C. Results showed that the selected bacteria could 'remove' AFM1 both in PBS and skimmed milk. The binding abilities of AFM1 by L. plantarum MON03 and L. rhamnosus GAF01 strains (at 10(8) CFU/ml) in PBS and reconstituted milk ranged, respectively, from 16.1-78.6% and 15.3-95.1%; overall, L. rhamnosus showed a better potential for removal than L. plantarum. 'Removal' appeared to be by simple binding; the bacteria/AFM1 complex was stable and only a very small proportion of mycotoxin was released back into the solution. L. rhamnosus GAF01 had the highest binding capacity and was selected for use in the in vivo study. Those results indicated that use of the organism prevented AFM1-induced effects on total white and red blood cells, and lymphocyte subtypes, after 15 days of host treatment. These studies clearly indicated that L. rhamnosus GAF01 was able to bind AFM1 in vitro and-by mechanisms that might also be related to a binding effect-counteract AFM1-induced immunotoxicity. Moreover, by itself, this bacterium was not toxic and could potentially be used as an additive in dairy products and in biotechnology for

  14. Experimental overview of COMPASS and CLAS results on TMDs

    NASA Astrophysics Data System (ADS)

    Riedl, Caroline

    2016-03-01

    In the past years, distribution functions depending on the transverse momentum of partons in the nucleon (TMDs) have been intensely studied in spin physics. The TMDs represent one approach to disentangle the multi-dimensional structure of the nucleon. Correlations of the transverse spin of quarks with their transverse momentum can be observed by measuring spin azimuthal asymmetries. Experimental results from the COMPASS (CERN) and CLAS (Jefferson Laboratory) collaborations are presented and an outlook to upcoming measurements at these facilities is given.

  15. Modeling and experimental result analysis for high-power VECSELs

    NASA Astrophysics Data System (ADS)

    Zakharian, Aramais R.; Hader, Joerg; Moloney, Jerome V.; Koch, Stephan W.; Lutgen, Stephan; Brick, Peter; Albrecht, Tony; Grotsch, Stefan; Luft, Johann; Spath, Werner

    2003-06-01

    We present a comparison of experimental and microscopically based model results for optically pumped vertical external cavity surface emitting semiconductor lasers. The quantum well gain model is based on a quantitative ab-initio approach that allows calculation of a complex material susceptibility dependence on the wavelength, carrier density and lattice temperature. The gain model is coupled to the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, with temperature and carrier density dependent pump absorption. The radial distribution of the refractive index and gain due to temperature variation are computed. Thermal managment issues, highlighted by the experimental data, are discussed. Experimental results indicate a critical dependence of the input power, at which thermal roll-over occurs, on the thermal resistance of the device. This requires minimization of the substrate thickness and optimization of the design and placement of the heatsink. Dependence of the model results on the radiative and non-radiative carrier recombination lifetimes and cavity losses are evaluated.

  16. Mechanical properties of triaxially braided composites: Experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Masters, John E.; Foye, Raymond L.; Pastore, Christopher M.; Gowayed, Yasser A.

    1992-01-01

    The unnotched tensile properties of 2-D triaxial braid reinforced composites from both an experimental and an analytical viewpoint are studied. The materials are graphite fibers in an epoxy matrix. Three different reinforcing fiber architectures were considered. Specimens were cut from resin transfer molded (RTM) composite panels made from each braid. There were considerable differences in the observed elastic constants from different size strain gage and extensometer reading. Larger strain gages gave more consistent results and correlated better with the extensometer reading. Experimental strains correlated reasonably well with analytical predictions in the longitudinal, 0 degrees, fiber direction but not in the transverse direction. Tensile strength results were not always predictable even in reinforcing directions. Minor changes in braid geometry led to disproportionate strength variations. The unit cell structure of the triaxial braid was discussed with the assistance of computer analysis of the microgeometry. Photomicrographs of braid geometry were used to improve upon the computer graphics representations of unit cells. These unit cells were used to predict the elastic moduli with various degrees of sophistication. The simple and the complex analyses were generally in agreement but none adequately matched the experimental results for all the braids.

  17. Mechanical properties of triaxially braided composites: Experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Masters, John E.; Foye, Raymond L.; Pastore, Christopher M.; Gowayed, Yasser A.

    1992-01-01

    This paper investigates the unnotched tensile properties of two-dimensional triaxial braid reinforced composites from both an experimental and analytical viewpoint. The materials are graphite fibers in an epoxy matrix. Three different reinforcing fiber architectures were considered. Specimens were cut from resin transfer molded (RTM) composite panels made from each braid. There were considerable differences in the observed elastic constants from different size strain gage and extensometer readings. Larger strain gages gave more consistent results and correlated better with the extensometer readings. Experimental strains correlated reasonably well with analytical predictions in the longitudinal, zero degree, fiber direction but not in the transverse direction. Tensile strength results were not always predictable even in reinforcing directions. Minor changes in braid geometry led to disproportionate strength variations. The unit cell structure of the triaxial braid was discussed with the assistence of computer analysis of the microgeometry. Photomicrographs of the braid geometry were used to improve upon the computer graphics representations of unit cells. These unit cells were used to predict the elastic moduli with various degrees of sophistication. The simple and the complex analyses were generally in agreement but none adequately matched the experimental results for all the braids.

  18. Label-free and quantitative evaluation of cytotoxicity based on surface nanostructure and biophysical property of cells utilizing AFM.

    PubMed

    Lee, Young Ju; Lee, Gi-Ja; Kang, Sung Wook; Cheong, Youjin; Park, Hun-Kuk

    2013-06-01

    In this study, the four commonly used cytotoxicity assays and the mechanical properties as evaluated by atomic force microscopy (AFM) were compared in a cellular system. A cytotoxicity assay is the first and most essential test to evaluate biocompatibility of various toxic substances. Many of the cytotoxicity methods require complicated and labor-intensive process, as well as introduce experimental error. In addition, these methods cannot provide instantaneous and quantitative cell viability information. AFM has become an exciting analytical tool in medical, biological, and biophysical research due to its unique abilities. AFM-based force-distance curve measurements precisely measure the changes in the biophysical properties of the cell. Therefore, we observed the morphological changes and mechanical property changes in L929 cells following sodium lauryl sulfate (SLS) treatment utilizing AFM. AFM imaging showed that the toxic effects of SLS changed not only the spindle-like shape of L929 cells into a round shape, but also made a rough cell surface. As the concentration of SLS was increased, the surface roughness of L929 cell was increased, and stiffness decreased. We confirmed that inhibition of proliferation clearly increased with increases in SLS concentration based on results from MTT, WST, neutral red uptake, and LIVE/DEAD viability/cytotoxicity assays. The estimated IC₅₀ value by AFM analysis was similar to those of other conventional assays and was included within the 95% confidence interval range. We suggest that an AFM quantitative analysis of the morphological and biophysical changes in cells can be utilized as a new method for evaluating cytotoxicity. PMID:23582483

  19. Experimental results on the enhanced backscatter phenomenon and its dynamics

    NASA Astrophysics Data System (ADS)

    Wu, Chensheng; Nelson, William; Ko, Jonathan; Davis, Christopher C.

    2014-10-01

    Enhanced backscatter effects have long been predicted theoretically and experimentally demonstrated. The reciprocity of a turbulent channel generates a group of paired rays with identical trajectory and phase information that leads to a region in phase space with double intensity and scintillation index. Though simulation work based on phase screen models has demonstrated the existence of the phenomenon, few experimental results have been published describing its characteristics, and possible applications of the enhanced backscatter phenomenon are still unclear. With the development of commercially available high powered lasers and advanced cameras with high frame rates, we have successfully captured the enhanced backscatter effects from different reflection surfaces. In addition to static observations, we have also tilted and pre-distorted the transmitted beam at various frequencies to track the dynamic properties of the enhanced backscatter phenomenon to verify its possible application in guidance and beam and image correction through atmospheric turbulence. In this paper, experimental results will be described, and discussions on the principle and applications of the phenomenon will be included. Enhanced backscatter effects are best observed in certain levels of turbulence (Cn 2≍10-13 m-2/3), and show significant potential for providing self-guidance in beam correction that doesn't introduce additional costs (unlike providing a beacon laser). Possible applications of this phenomenon include tracking fast moving object with lasers, long distance (>1km) alignment, and focusing a high-power corrected laser beam over long distances.

  20. Experimental results from an airborne static Fourier transform imaging spectrometer.

    PubMed

    Ferrec, Yann; Taboury, Jean; Sauer, Hervé; Chavel, Pierre; Fournet, Pierre; Coudrain, Christophe; Deschamps, Joël; Primot, Jérôme

    2011-10-20

    A high étendue static Fourier transform spectral imager has been developed for airborne use. This imaging spectrometer, based on a Michelson interferometer with rooftop mirrors, is compact and robust and benefits from a high collection efficiency. Experimental airborne images were acquired in the visible domain. The processing chain to convert raw images to hyperspectral data is described, and airborne spectral images are presented. These experimental results show that the spectral resolution is close to the one expected, but also that the signal to noise ratio is limited by various phenomena (jitter, elevation fluctuations, and one parasitic image). We discuss the origin of those limitations and suggest solutions to circumvent them. PMID:22015418

  1. On collisional disruption - Experimental results and scaling laws

    NASA Technical Reports Server (NTRS)

    Davis, Donald R.; Ryan, Eileen V.

    1990-01-01

    Both homogeneous and inhomogeneous targets have been addressed by the present experimental consideration of the impact strengths, fragment sizes, and fragment velocities generated by cement mortar targets whose crushing strengths vary by an order of magnitude, upon impact of projectiles in the velocity range of 50-5700 m/sec. When combined with additional published data, dynamic impact strength is found to correlate with quasi-static material strengths for materials ranging in character from basalt to ice; two materials not following this trend, however, are weak mortar and clay targets. Values consistent with experimental results are obtainable with a simple scaling algorithm based on impact energy, material properties, and collisional strain rate.

  2. Design and experimental results for the S814 airfoil

    SciTech Connect

    Somers, D.M.

    1997-01-01

    A 24-percent-thick airfoil, the S814, for the root region of a horizontal-axis wind-turbine blade has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of high maximum lift, insensitive to roughness, and low profile drag have been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results show good agreement with the exception of maximum lift which is overpredicted. Comparisons with other airfoils illustrate the higher maximum lift and the lower profile drag of the S814 airfoil, thus confirming the achievement of the objectives.

  3. Experimental study of radiometric forces with comparison to computational results

    NASA Astrophysics Data System (ADS)

    Selden, Nathaniel P.

    A study of the radiometric forces on heated plates has been conducted both experimentally and computationally. The experiments were carried out at USC in two vacuum chambers up to a maximum pressure of 6 Pa for various carrier gases. The computations were performed with both the DSMC and ES-BGK methods for a 2-D gas flow over a comparable range of pressures. It is shown that the radiometric devices provide maximum force at a Knudsen number approximating 0.1. Of the various gases tested, helium provides the largest peak force. Qualitatively, the experimental data and computational results are similar. A lack of experimental data on gas-surface accommodation and flow three-dimensionality yields up to a 40% difference in the magnitude of the measured and computed forces, but it is shown that this discrepancy can be used to predict accommodation values. Comparison of four geometric configurations has shown that the effect of the area is significant at pressures up to where the force is maximum. It is also demonstrated that the size of the chamber in which the radiometer resides is of primary importance, where the chamber dimensions are inversely related to the generated force. Finally, simulation of multi-vane configurations have shown that the optimal spacing of vanes can be tailored for specific uses; for maximum force production a tight spacing should be used, while maximum efficiency requires spacing on the order of a vane dimension. While the results so far are encouraging, they are far from complete. Further improvements would include: a new experimental setup to reduce uncertainty with highly accurate temperature control and measurement, an in situ way to prepare the surface as well as measure its cleanliness, and an in depth iterative computational study observing the impact of multiple radiometer vanes at numerous seperations.

  4. Comparison of Calculated and Experimental Results for a Boiling/Condensing Experimental Facility

    SciTech Connect

    Carbajo, Juan J; McDuffee, Joel Lee; Felde, David K

    2016-01-01

    A new experimental facility for materials irradiation and testing at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) is being developed. Details of this facility have been presented before [1, 2]. A prototype of this facility, the Thermo-Syphon Test Loop (TSTL) has been built and experimental data have been obtained and analyzed [3, 4]. Pre-test calculations for this facility with the RELAP5-3D code [5] have been presented previously [6] as well as other calculations [7, 8] with the TRACE code [9]. The results of both codes were very different [7]. RELAP5-3D predicted much higher pressures and temperatures than TRACE. This paper compares calculated results with the TSTL experimental data.

  5. Comparison of computational and experimental results for a supercritical airfoil

    NASA Technical Reports Server (NTRS)

    Rivers, Melissa B.; Wahls, Richard A.

    1994-01-01

    A computational investigation was performed to study the flow over a supercritical airfoil model. Solutions were obtained for steady-state transonic flow conditions using a thin-layer Navier-Stokes flow solver. The results from this computational study were compared with time-averaged experimental data obtained over a wide Reynolds number range at transonic speeds in the Langley 0.3-Meter Transonic Cryogenic Tunnel. Comparisons were made at a nominal Mach number of 0.72 and at Reynolds numbers ranging from 6 x 10(exp 6) to 35 x 10(exp 6).

  6. ANOVA parameters influence in LCF experimental data and simulation results

    NASA Astrophysics Data System (ADS)

    Delprete, C.; Sesanaa, R.; Vercelli, A.

    2010-06-01

    The virtual design of components undergoing thermo mechanical fatigue (TMF) and plastic strains is usually run in many phases. The numerical finite element method gives a useful instrument which becomes increasingly effective as the geometrical and numerical modelling gets more accurate. The constitutive model definition plays an important role in the effectiveness of the numerical simulation [1, 2] as, for example, shown in Figure 1. In this picture it is shown how a good cyclic plasticity constitutive model can simulate a cyclic load experiment. The component life estimation is the subsequent phase and it needs complex damage and life estimation models [3-5] which take into account of several parameters and phenomena contributing to damage and life duration. The calibration of these constitutive and damage models requires an accurate testing activity. In the present paper the main topic of the research activity is to investigate whether the parameters, which result to be influent in the experimental activity, influence the numerical simulations, thus defining the effectiveness of the models in taking into account of all the phenomena actually influencing the life of the component. To obtain this aim a procedure to tune the parameters needed to estimate the life of mechanical components undergoing TMF and plastic strains is presented for commercial steel. This procedure aims to be easy and to allow calibrating both material constitutive model (for the numerical structural simulation) and the damage and life model (for life assessment). The procedure has been applied to specimens. The experimental activity has been developed on three sets of tests run at several temperatures: static tests, high cycle fatigue (HCF) tests, low cycle fatigue (LCF) tests. The numerical structural FEM simulations have been run on a commercial non linear solver, ABAQUS®6.8. The simulations replied the experimental tests. The stress, strain, thermal results from the thermo structural FEM

  7. Large aperture spatial heterodyne imaging spectrometer: Principle and experimental results

    NASA Astrophysics Data System (ADS)

    Xiangli, Bin; Cai, Qisheng; Du, Shusong

    2015-12-01

    A large aperture spatial heterodyne imaging spectrometer (LASHIS) is proposed. It is a kind of pushbroom Fourier transform ultraspectral imager with no moving parts. This imaging spectrometer, based on a Sagnac lateral shearing interferometer combined with a pair of gratings, has the advantages of high spectral resolution, high throughput and robustness. The principle of LASHIS and its spectral retrieval method are introduced. The processing chain to convert raw images to ultraspectral datacube is also described. Experimental results demonstrate the high resolving power of LASHIS with the emission spectrum of a low pressure sodium lamp.

  8. Experimental and simulational result multipactors in 112 MHz QWR injector

    SciTech Connect

    Xin, T.; Ben-Zvi, I.; Belomestnykh, S.; Brutus, J. C.; Skaritka, J.; Wu, Q.; Xiao, B.

    2015-05-03

    The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were installed and tested for the first time. During this experiment, we observed several multipacting barriers at different gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.8 MV gun voltage under pulsed mode after several round of conditioning processes.

  9. Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis

    NASA Astrophysics Data System (ADS)

    Gabriele, Papadia; Antonio, Del Prete; Alfredo, Anglani

    2010-06-01

    The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.

  10. Single And Double Pulse Irradiation And Comparison With Experimental Results

    SciTech Connect

    Fornarini, L.; Fantoni, R.; Colao, F.; Santagata, A.; Teghil, R.

    2009-09-27

    A theoretical model of laser ablation has been previously developed and applied to Laser Induced Breakdown Spectroscopy (LIBS) analysis of bronzes with the aim to improve quantitative results and to focus on problems arising in the interpretation of experimental data. The model describes laser-solid matter interaction, plume expansion, plasma formation and laser-plasma interaction. A two temperature approach has been also introduced to take into account the initial temperature dynamics of the alloy surface upon ultra-short laser irradiation. We examined various target compositions, typical of archaeological artworks, and different laser characteristics such as wavelength (355 nm, 530 nm, 1064 nm) and pulse duration (8 ns, 250 fs). In this work, the model has been extended to simulate double pulse LIBS configuration in order to clarify the mechanism involved in the process and for better interpreting the experimental data. Plasma composition, relevant parameters (temperature, electron density) and their kinetic evolutions have been measured. Results have been compared with the simulation obtained using the same irradiation conditions and set of targets.

  11. Some new experimental results on the Zr Nb Fe system

    NASA Astrophysics Data System (ADS)

    Ramos, C.; Saragovi, C.; Granovsky, M. S.

    2007-06-01

    The scope of this study is the identification and characterization of intermetallic phases and their binary and ternary fields in the Zr-Nb-Fe phase diagram. A construction of the central region of the phase diagram at 900 °C was proposed using new experimental results obtained by optical and scanning electron microscopies, X-ray diffraction and microprobe analysis. In addition to the well-known Laves C15-type (ZrNb)Fe 2 phase (the polytypic C14 and C36 structures were not detected in the studied compositions), another Laves C14-type phase was found (Zr(NbFe) 2). Watson and Bennett maps helped to predict the occurrence of both of these phases. Moreover, the validity of the Pettifor prediction model for Laves phases in pseudobinary systems with transition elements was checked, verifying the obtained experimental results in the Zr-Nb-Fe system. On the other hand it was determined that the Zr-Nb-Fe ternary system at 900 °C, as it happens in the binary Zr-Nb system, would have a miscibility gap (β-Zr + β-Nb) in the 25-70 at.% Nb composition range, accepting up to 3 at.% Fe approximately.

  12. Liquid contact resonance AFM: analytical models, experiments, and limitations

    NASA Astrophysics Data System (ADS)

    Parlak, Zehra; Tu, Qing; Zauscher, Stefan

    2014-11-01

    Contact resonance AFM (CR-AFM) is a scanning probe microscopy technique that utilizes the contact resonances of the AFM cantilever for concurrent imaging of topography and surface stiffness. The technique has not been used in liquid until recently due to analytical and experimental difficulties, associated with viscous damping of cantilever vibrations and fluid loading effects. To address these difficulties, (i) an analytical approach for contact resonances in liquid is developed, and (ii) direct excitation of the contact resonances is demonstrated by actuating the cantilever directly in a magnetic field. By implementing the analytical approach and the direct actuation through magnetic particles, quantitative stiffness imaging on surfaces with a wide range of stiffness can be achieved in liquid with soft cantilevers and low contact forces.

  13. Atmospheric turbulence correction using digital holographic detection: experimental results.

    PubMed

    Marron, Joseph C; Kendrick, Richard L; Seldomridge, Nathan; Grow, Taylor D; Höft, Thomas A

    2009-07-01

    The performance of long distance imaging systems is typically degraded by phase errors imparted by atmospheric turbulence. In this paper we apply coherent imaging methods to determine, and remove, these phase errors by digitally processing coherent recordings of the image data. In this manner we are able to remove the effects of atmospheric turbulence without needing a conventional adaptive optical system. Digital holographic detection is used to record the coherent, complex-valued, optical field for a series of atmospheric and object realizations. Correction of atmospheric phase errors is then based on maximizing an image sharpness metric to determine the aberrations present and correct the underlying image. Experimental results that demonstrate image recovery in the presence of turbulence are presented. Results obtained with severe turbulence that gives rise to anisoplanatism are also presented. PMID:19582079

  14. Implications of the contact radius to line step (CRLS) ratio in AFM for nanotribology measurements.

    PubMed

    Helt, James M; Batteas, James D

    2006-07-01

    Investigating the mechanisms of defect generation and growth at surfaces on the nanometer scale typically requires high-resolution tools such as the atomic force microscope (AFM). To accurately assess the kinetics and activation parameters of defect production over a wide range of loads (F(z)), the AFM data should be properly conditioned. Generally, AFM wear trials are performed over an area defined by the length of the slow (L(sscan)) and fast scan axes. The ratio of L(sscan) to image resolution (res, lines per image) becomes an important experimental parameter in AFM wear trials because it defines the magnitude of the line step (LS = L(sscan)/res), the distance the AFM tip steps along the slow scan axis. Comparing the contact radius (a) to the line step (LS) indicates that the overlap of successive scans will result unless the contact radius-line step ratio (CRLS) is < or =(1)/(2). If this relationship is not considered, then the scan history (e.g., contact frequency) associated with a single scan is not equivalent at different loads owing to the scaling of contact radius with load (a proportional variant F(z)(1/3)). Here, we present a model in conjunction with empirical wear tests on muscovite mica to evaluate the effects of scan overlap on surface wear. Using the Hertz contact mechanics definition of a, the CRLS model shows that scan overlap pervades AFM wear trials even under low loads. Such findings indicate that simply counting the number of scans (N(scans)) in an experiment underestimates the full history conveyed to the surface by the tip and translates into an error in the actual extent to which a region on the surface is contacted. Utilizing the CRLS method described here provides an approach to account for image scan history accurately and to predict the extent of surface wear. This general model also has implications for any AFM measurement where one wishes to correlate scan-dependent history to image properties as well as feature resolution in scanned

  15. Electrical and thermal behavior of unsaturated soils: experimental results

    NASA Astrophysics Data System (ADS)

    Nouveau, Marie; Grandjean, Gilles; Leroy, Philippe; Philippe, Mickael; Hedri, Estelle; Boukcim, Hassan

    2016-05-01

    When soil is affected by a heat source, some of its properties are modified, and in particular, the electrical resistivity due to changes in water content. As a result, these changes affect the thermal properties of soil, i.e., its thermal conductivity and diffusivity. We experimentally examine the changes in electrical resistivity and thermal conductivity for four soils with different grain size distributions and clay content over a wide range of temperatures, from 20 to 100 °C. This temperature range corresponds to the thermal conditions in the vicinity of a buried high voltage cable or a geothermal system. Experiments were conducted at the field scale, at a geothermal test facility, and in the laboratory using geophysical devices and probing systems. The results show that the electrical resistivity decreases and the thermal conductivity increases with temperature up to a critical temperature depending on soil types. At this critical temperature, the air volume in the pore space increases with temperature, and the resulting electrical resistivity also increases. For higher temperatures , the thermal conductivity increases sharply with temperature up to a second temperature limit. Beyond it, the thermal conductivity drops drastically. This limit corresponds to the temperature at which most of the water evaporates from the soil pore space. Once the evaporation is completed, the thermal conductivity stabilizes. To explain these experimental results, we modeled the electrical resistivity variations with temperature and water content in the temperature range 20 - 100°C, showing that two critical temperatures influence the main processes occurring during heating at temperatures below 100 °C.

  16. Non-shock initiation model for explosive families : experimental results.

    SciTech Connect

    Anderson, Mark U.; Jensen, Charles B.; Todd, Steven N.; Hugh, Chance G.; Caipen, Terry L.

    2010-03-01

    The 'DaMaGe-Initiated-Reaction' (DMGIR) computational model has been developed to predict the response of high explosives to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of a reaction in the explosive, and its growth to detonation. Specifically designed experiments were used to study the initiation process of each explosive family with embedded shock sensors and optical diagnostics. The experimental portion of this model development began with a study of PBXN-5 to develop DMGIR model coefficients for the rigid plastic bonded family, followed by studies of the cast, and bulk-moldable explosive families. The experimental results show an initiation mechanism that is related to input energy and material damage, with well defined initiation thresholds for each explosive family. These initiation details will extend the predictive capability of the DMGIR model from the rigid family into the cast and bulk-moldable families.

  17. Registration of multimodal brain images: some experimental results

    NASA Astrophysics Data System (ADS)

    Chen, Hua-mei; Varshney, Pramod K.

    2002-03-01

    Joint histogram of two images is required to uniquely determine the mutual information between the two images. It has been pointed out that, under certain conditions, existing joint histogram estimation algorithms like partial volume interpolation (PVI) and linear interpolation may result in different types of artifact patterns in the MI based registration function by introducing spurious maxima. As a result, the artifacts may hamper the global optimization process and limit registration accuracy. In this paper we present an extensive study of interpolation-induced artifacts using simulated brain images and show that similar artifact patterns also exist when other intensity interpolation algorithms like cubic convolution interpolation and cubic B-spline interpolation are used. A new joint histogram estimation scheme named generalized partial volume estimation (GPVE) is proposed to eliminate the artifacts. A kernel function is involved in the proposed scheme and when the 1st order B-spline is chosen as the kernel function, it is equivalent to the PVI. A clinical brain image database furnished by Vanderbilt University is used to compare the accuracy of our algorithm with that of PVI. Our experimental results show that the use of higher order kernels can effectively remove the artifacts and, in cases when MI based registration result suffers from the artifacts, registration accuracy can be improved significantly.

  18. Controlled nanodot fabrication by rippling polycarbonate surface using an AFM diamond tip

    PubMed Central

    2014-01-01

    The single scratching test of polymer polycarbonate (PC) sample surface using an atomic force microscope (AFM) diamond tip for fabricating ripple patterns has been studied with the focus on the evaluation of the effect of the tip scratching angle on the pattern formation. The experimental results indicated that the different oriented ripples can be easily machined by controlling the scratching angles of the AFM. And, the effects of the normal load and the feed on the ripples formation and their periods were also studied. Based on the ripple pattern formation, we firstly proposed a two-step scratching method to fabricate controllable and oriented complex three-dimensional (3D) nanodot arrays. These typical ripple formations can be described via a stick-slip and crack formation process. PMID:25114660

  19. Physical mechanism of comet outbursts - An experimental result

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.

    1993-01-01

    Attention is given to an experimental investigation of the physical mechanism of comet outbursts which is consistent with the general picture of mantle presence on comets and clarifies the relation of mantles to eruptive activity. The experiment and closeup observation of Comet P/Halley suggest a result different from most mathematical models in that the release of gas pressure does not occur only from uniform gas flow out of the entire surface. In some active comets near perihelion within a few AU of the sun, gas production rates and disturbance of the surface may be so high that the outflow is nearly continuous, with the regolith being entirely stripped away, as in many of the models. The present model provides a cyclic eruption and recharge mechanism which is lacking in most other models.

  20. Beta decay and the origins of biological chirality - Experimental results

    NASA Technical Reports Server (NTRS)

    Gidley, D. W.; Rich, A.; Van House, J.; Zitzewitz, P. W.

    1982-01-01

    Preliminary experimental results are presented of an investigation of the possible role of preferential radiolysis by electrons emitted in the beta decay of radionuclides, a parity-nonconserving process, in the universal causation of the optical activity of biological compounds. Experiments were designed to measure the asymmetry in the production of triplet positronium upon the bombardment of an amino acid powder target by a collimated beam of positrons as positron helicity or target chirality is reversed. No asymmetry down to a level of 0.0007 is found in experiments on the D and L forms of cystine and tryptophan, indicating an asymmetry in positronium formation cross section of less than 0.01, while an asymmetry of 0.0031 is found for leucine, corresponding to a formation cross section asymmetry of about 0.04

  1. Robotic follower experimentation results: ready for FCS increment I

    NASA Astrophysics Data System (ADS)

    Jaczkowski, Jeffrey J.

    2003-09-01

    Robotics is a fundamental enabling technology required to meet the U.S. Army's vision to be a strategically responsive force capable of domination across the entire spectrum of conflict. The U. S. Army Research, Development and Engineering Command (RDECOM) Tank Automotive Research, Development & Engineering Center (TARDEC), in partnership with the U.S. Army Research Laboratory, is developing a leader-follower capability for Future Combat Systems. The Robotic Follower Advanced Technology Demonstration (ATD) utilizes a manned leader to provide a highlevel proofing of the follower's path, which operates with minimal user intervention. This paper will give a programmatic overview and discuss both the technical approach and operational experimentation results obtained during testing conducted at Ft. Bliss, New Mexico in February-March 2003.

  2. Object impedance control for cooperative manipulation - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Schneider, Stanley A.; Cannon, Robert H., Jr.

    1989-01-01

    The dynamic control module being developed in the Dynamic and Strategic Control of Cooperative Manipulators (DASCCOM) project at the Stanford University Aerospace Robotics Laboratory is described. First, the cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. Next, a control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to the strategic controller. Experimental results for a dual two-link arm robotic system are presented to verify the controllers performance, for both free-motion slews and environmental contact.

  3. Preliminary Experimental Results from a MARS Micro-CT System

    PubMed Central

    He, Peng; Yu, Hengyong; Thayer, Patrick; Jin, Xin; Xu, Qiong; Bennett, James; Tappenden, Rachael; Wei, Biao; Goldstein, Aaron; Renaud, Peter; Butler, Anthony; Butler, Phillip; Wang, Ge

    2013-01-01

    The Medipix All Resolution System (MARS) system is a commercial spectral/multi-energy micro-CT scanner designed and assembled by the MARS Bioimaging, Ltd. in New Zealand. This system utilizes the state-of-the-art Medipix photon-counting, energy-discriminating detector technology developed by a collaboration based at European Organization for Nuclear Research (CERN). In this paper, we report our preliminary experimental results using this system, including geometrical alignment, photon energy characterization, protocol optimization, and spectral image reconstruction. We produced our scan datasets with a multi-material phantom, and then applied ordered subset-simultaneous algebraic reconstruction technique (OS-SART) to reconstruct images in different energy ranges and principal component analysis (PCA) to evaluate spectral deviation between the energy ranges. PMID:22635175

  4. Selected experimental results from heavy-ion collisions at LHC

    DOE PAGESBeta

    Singh, Ranbir; Kumar, Lokesh; Netrakanti, Pawan Kumar; Mohanty, Bedangadas

    2013-01-01

    We reviewmore » a subset of experimental results from the heavy-ion collisions at the Large Hadron Collider (LHC) facility at CERN. Excellent consistency is observed across all the experiments at the LHC (at center of mass energysNN=2.76 TeV) for the measurements such as charged particle multiplicity density, azimuthal anisotropy coefficients, and nuclear modification factor of charged hadrons. Comparison to similar measurements from the Relativistic Heavy Ion Collider (RHIC) at lower energy (sNN=200 GeV) suggests that the system formed at LHC has a higher energy density and larger system size and lives for a longer time. These measurements are compared to model calculations to obtain physical insights on the properties of matter created at the RHIC and LHC.« less

  5. Solving and Learning Soft Temporal Constraints: Experimental Setting and Results

    NASA Technical Reports Server (NTRS)

    Rossi, F.; Sperduti, A.; Venable, K. B.; Khatib, L.; Morris, P.; Morris, R.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Soft temporal constraints problems allow to describe in a natural way scenarios where events happen over time and preferences are associated to event distances and durations. However, sometimes such local preferences are difficult to set, and it may be easier instead to associate preferences to some complete solutions of the problem. Machine learning techniques can be useful in this respect. In this paper we describe two solvers (one more general and the other one more efficient) for tractable subclasses of soft temporal problems, and we show some experimental results. The random generator used to build the problems on which tests are performed is also described. We also compare the two solvers highlighting the tradeoff between performance and representational power. Finally, we present a learning module and we show its behavior on randomly-generated examples.

  6. Experimental results to study astrophysical plasma jets using Intense Lasers

    NASA Astrophysics Data System (ADS)

    Loupias, B.; Gregory, C. D.; Falize, E.; Waugh, J.; Seiichi, D.; Pikuz, S.; Kuramitsu, Y.; Ravasio, A.; Bouquet, S.; Michaut, C.; Barroso, P.; Rabec Le Gloahec, M.; Nazarov, W.; Takabe, H.; Sakawa, Y.; Woolsey, N.; Koenig, M.

    2009-08-01

    We present experimental results of plasma jet, interacted with an ambient medium, using intense lasers to investigate the complex features of astrophysical jets. This experiment was performed in France at the LULI facility, Ecole Polytechnique, using one long pulse laser to generate the jet and a short pulse laser to probe it by proton radiography. A foam filled cone target was used to generate high velocity plasma jet, and a gas jet nozzle produced the well known ambient medium. Using visible pyrometry and interferometry, we were able to measure the jet velocity and electronic density. We get a panel of measurements at various gas density and time delay. From these measurements, we could underline the growth of a perturbed shape of the jet interaction with the ambient medium. The reason of this last observation is still in debate and will be presented in the article.

  7. Arm-free paraplegic standing--Part II: Experimental results.

    PubMed

    Matjacić, Z; Bajd, T

    1998-06-01

    In Part I, we proposed an approach for restoring unsupported standing to thoracic-level paraplegics. The theoretical analysis and simulation of an underactuated double inverted pendulum, representing the standing subject, showed that arm-free standing might be achieved. Here in Part II, we present the mechanical apparatus which we used in our experiments and experimental results from tests of the balance-control strategy. We demonstrate that an intact and a paraplegic subject could perform quiet standing with the ankle stiffness set to 8 Nm/degree or even less (the intact subject). Both were also able to recover from disturbances, imposed by the artificial ankle joint of the apparatus. Introducing cognitive auditory feedback greatly improved the standing abilities of both subjects. PMID:9631321

  8. Object impedance control for cooperative manipulation - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Schneider, Stanley A.; Cannon, Robert H., Jr.

    1992-01-01

    This paper presents the dynamic control module of the Dynamic and Strategic Control of Cooperating Manipulators (DASCCOM) project at Stanford University's Aerospace Robotics Laboratory. First, the cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. Next, a control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to higher level strategic control modules. Experimental results from a dual two-link-arm robotic system are used to compare the object impedance controller with other strategies, both for free-motion slews and environmental contact.

  9. Experimental Results of Rover-Based Coring and Caching

    NASA Technical Reports Server (NTRS)

    Backes, Paul G.; Younse, Paulo; DiCicco, Matthew; Hudson, Nicolas; Collins, Curtis; Allwood, Abigail; Paolini, Robert; Male, Cason; Ma, Jeremy; Steele, Andrew; Conrad, Pamela G.

    2011-01-01

    Experimental results are presented for experiments performed using a prototype rover-based sample coring and caching system. The system consists of a rotary percussive coring tool on a five degree-of-freedom manipulator arm mounted on a FIDO-class rover and a sample caching subsystem mounted on the rover. Coring and caching experiments were performed in a laboratory setting and in a field test at Mono Lake, California. Rock abrasion experiments using an abrading bit on the coring tool were also performed. The experiments indicate that the sample acquisition and caching architecture is viable for use in a 2018 timeframe Mars caching mission and that rock abrasion using an abrading bit may be feasible in place of a dedicated rock abrasion tool.

  10. Integrated radar-camera security system: experimental results

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Palka, N.; Trzcinski, T.; Dulski, R.; Kastek, M.; Trzaskawka, P.

    2011-06-01

    The nature of the recent military conflicts and terrorist attacks along with the necessity to protect bases, convoys and patrols have made a serious impact on the development of more effective security systems. Current widely-used perimeter protection systems with zone sensors will soon be replaced with multi-sensor systems. Multi-sensor systems can utilize day/night cameras, IR uncooled thermal cameras, and millimeter-wave radars which detect radiation reflected from targets. Ranges of detection, recognition and identification for all targets depend on the parameters of the sensors used and of the observed scene itself. In this paper two essential issues connected with multispectral systems are described. We will focus on describing the autonomous method of the system regarding object detection, tracking, identification, localization and alarm notifications. We will also present the possibility of configuring the system as a stationary, mobile or portable device as in our experimental results.

  11. Experimental Progress and Results of a Visible Nulling Coronagraph

    NASA Technical Reports Server (NTRS)

    Samuele, Rocco; Wallace, J. Kent; Schmidtlin, Edouard; Shao, Mike; Levine, B. Martin; Fregoso, Santos

    2007-01-01

    The crux of visible exoplanet detection is overcoming significant star-planet contrast ratios on the order of 10(exp -7) to 10(exp -10)-at very small angular separations. We are developing an interferometric nulling coronagraph designed to achieve a 10(exp -6) contrast ratio at a working science bandpass of 20% visible light. Achieving large, broadband suppression requires a pseudo-achromatic phase flip, while maintaining a strict error budget. Recent results from our nulling interferometer testbed yield contrast ratios at the 1.05x10(exp -6) level, with a 15% visible bandpass. This result is at 65% of our final bandpass requirement, although limitations of our current configuration make major hardware changes essential to broadening the bandpass. We make the argument that broadening the bandpass should not necessarily adversely affect the null depth until beyond the 20% visible light level. Using the same setup we are able to reach monochromatic null depths of 1.11x10(exp -7) (?= 638 nm)averaged over three seconds. This paper will describe our experimental approach for achieving deep broadband nulls, as well as error considerations and limitations, and the most recent results for our nulling coronagraph testbed.

  12. Experimental Results for Titan Aerobot Thermo-Mechanical Subsystem Development

    NASA Technical Reports Server (NTRS)

    Hall, Jeffrey L.; Jones, J. A.; Kerzhanovich, V. V.; Lachenmeier, T.; Mahr, P.; Pauken, M.; Plett, G. A.; Smith, L.; VanLuvender, M. L.; Yavrouian, A. H.

    2006-01-01

    This paper describes experimental results from a development program focused in maturing Titan aerobot technology in the areas of mechanical and thermal subsystems. Results from four key activities are described: first, a cryogenic balloon materials development program involving coupon and cylinder tests and culminating in the fabrication and testing of an inflated 4.6 m long prototype blimp at 93 K; second, a combined lab experiment and numerical simulation effort to assess potential problems resulting from radioisotope thermal generator waste heat generation near an inflated blimp; third, an aerial deployment and inflation development program consisting of laboratory and helicopter drop tests on a near full scale (11 m long) prototype blimp; and fourth, a proof of concept experiment demonstrating the viability of using a mechanically steerable high gain antenna on a floating blimp to perform direct to Earth telecommunications from Titan. The paper provides details on all of these successful activities and discusses their impact on the overall effort to produce mature systems technology for future Titan aerobot missions.

  13. Internal wave emission from baroclinic jets: experimental results

    NASA Astrophysics Data System (ADS)

    Borcia, Ion D.; Rodda, Costanza; Harlander, Uwe

    2016-04-01

    Large-scale balanced flows can spontaneously radiate meso-scale inertia-gravity waves (IGWs) and are thus in fact unbalanced. While flow-dependent parameterizations for the radiation of IGWs from orographic and convective sources do exist, the situation is less developed for spontaneously emitted IGWs. Observations identify increased IGW activity in the vicinity of jet exit regions. A direct interpretation of those based on geostrophic adjustment might be tempting. However, directly applying this concept to the parameterization of spontaneous imbalance is difficult since the dynamics itself is continuously re-establishing an unbalanced flow which then sheds imbalances by GW radiation. Examining spontaneous IGW emission in the atmosphere and validating parameterization schemes confronts the scientist with particular challenges. Due to its extreme complexity, GW emission will always be embedded in the interaction of a multitude of interdependent processes, many of which are hardly detectable from analysis or campaign data. The benefits of repeated and more detailed measurements, while representing the only source of information about the real atmosphere, are limited by the non-repeatability of an atmospheric situation. The same event never occurs twice. This argues for complementary laboratory experiments, which can provide a more focused dialogue between experiment and theory. Indeed, life cycles are also examined in rotating-annulus laboratory experiments. Thus, these experiments might form a useful empirical benchmark for theoretical and modeling work that is also independent of any sort of subgrid model. In addition, the more direct correspondence between experimental and model data and the data reproducibility makes lab experiments a powerful testbed for parameterizations. Here we show first results from a small rotating annulus experiments and we will further present our new experimental facility to study wave emission from jets and fronts.

  14. Experimental results of guided wave travel time tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Vos, Hendrik

    2012-05-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation matches very well with the objective to reduce cost while maintaining a high safety level. Guided waves are very attractive for permanent monitoring systems because it provides a wall thickness map in between two sensor rings. The wall thickness map provides quantitative information about the remaining wall thickness, location and extent of the corrosion. The performance of guided wave tomography has been evaluated experimentally assessing the sizing accuracy and the smallest corrosion spots that can be detected with this technology. The results show accurate sizing, with a sizing accuracy better than 10% of the nominal wall thickness. Additionally, the maximum distance between the transmitter and receiver rings and the presence of different coatings has been evaluated. The results demonstrate the robustness of the technology under a range of practical conditions.

  15. Experimental Results from a Resonant Dielectric Laser Accelerator

    NASA Astrophysics Data System (ADS)

    Yoder, Rodney; McNeur, Joshua; Sozer, Esin; Travish, Gil; Hazra, Kiran Shankar; Matthews, Brian; England, Joel; Peralta, Edgar; Wu, Ziran

    2015-04-01

    Laser-powered accelerators have the potential to operate with very large accelerating gradients (~ GV/m) and represent a path toward extremely compact colliders and accelerator technology. Optical-scale laser-powered devices based on field-shaping structures (known as dielectric laser accelerators, or DLAs) have been described and demonstrated recently. Here we report on the first experimental results from the Micro-Accelerator Platform (MAP), a DLA based on a slab-symmetric resonant optical-scale structure. As a resonant (rather than near-field) device, the MAP is distinct from other DLAs. Its cavity resonance enhances its accelerating field relative to the incoming laser fields, which are coupled efficiently through a diffractive optic on the upper face of the device. The MAP demonstrated modest accelerating gradients in recent experiments, in which it was powered by a Ti:Sapphire laser well below its breakdown limit. More detailed results and some implications for future developments will be discussed. Supported in part by the U.S. Defense Threat Reduction Agency (UCLA); U.S. Dept of Energy (SLAC); and DARPA (SLAC).

  16. Breaking the resolution limit: an exciting experimental result

    NASA Astrophysics Data System (ADS)

    Simonetti, Francesco

    2006-03-01

    For more than a century the possibility of imaging the structure of a medium with diffracting wavefields has been limited by the tradeoff between resolution and imaging depth. While long wavelengths can penetrate deep into a medium, the resolution limit precludes the possibility of observing subwavelength structures. Recent progress in microscopy has shown that by exploiting the super-oscillatory properties of evanescent fields, resolution several orders of magnitude smaller than the wavelength can be achieved so leading to Near-field Scanning Optical Microscopy. Based on a similar argument, this paper investigates the possibility of obtaining super resolution in the far-field (here far-field refers to a distance greater than λ, which would enable high resolution imaging at relatively large depth. The theoretical principles which result in the resolution limit are reviewed and a new strategy to overcome it is proposed. An advanced imaging algorithm for linear and two-dimensional array probing systems is presented and its capability of resolving targets as close as λ/3 is demonstrated experimentally, the targets being at several wavelength distance from the array. The results show that the method is superior to conventional techniques such as Synthetic Aperture Focusing, Synthetic Phased Arrays and Time Reversal.

  17. Experimental results of an iodine plasma in PEGASES gridded thruster

    NASA Astrophysics Data System (ADS)

    Grondein, Pascaline; Aanesland, Ane

    2015-09-01

    In the electric gridded thruster PEGASES, both positive and negative ions are expelled after extraction from an ion-ion plasma. This ion-ion plasma is formed downstream a localized magnetic field placed a few centimeters from the ionization region, trapping and cooling down the electron to allow a better attachment to an electronegative gas. For this thruster concept, iodine has emerged as the most attractive option. Heavy, under diatomic form and therefore good for high thrust, its low ionization threshold and high electronegativity lead to high ion-ion densities and low RF power. After the proof-of-concept of PEGASES using SF6 as propellant, we present here experimental results of an iodine plasma studied inside PEGASES thruster. At solid state at standard temperature and pressure, iodine is heated to sublimate, then injected inside the chamber where the neutral gas is heated and ionized. The whole injection system is heated to avoid deposition on surfaces and a mass flow controller allows a fine control on the neutral gas mass flow. A 3D translation stage inside the vacuum chamber allows volumetric plasma studies using electrostatic probes. The results are also compared with the global model dedicated to iodine as propellant for electric gridded thrusters. This work has been done within the LABEX Plas@par project, and received financial state aid managed by the Agence Nationale de la Recherche, as part of the programme ``Investissements d'avenir.''

  18. Experimental Results of Guided Wave Travel Time Tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Mast, Arjan; Bloom, Joost

    2010-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Both economical and social requirements are pushing the industry to even higher levels of availability, reliability and safety of installations. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections reducing uncertainty and extending inspection intervals. Guided wave travel time tomography is a promising method to monitor the wall thickness quantitatively over large areas. Obviously the robustness and reliability of such a monitoring system is of paramount importance. Laboratory experiments have been carried out on a 10″ pipe with a nominal wall thickness of 8 mm. Multiple, inline defects have been created with a realistic morphology. The depth of the defects was increased stepwise from 0.5 mm to 2 mm. Additionally the influences of the presence of liquid inside the pipe and surface roughness have been evaluated as well. Experimental results show that this method is capable of providing quantitative wall thickness information over a distance of 4 meter, with a sufficient accuracy such that results can be used for trending. The method has no problems imaging multiple defects.

  19. Experimental results of a single emittance compensation solenoidal magnet

    SciTech Connect

    Palmer, D.T.; Miller, R.H.; Wang, X.J.; Ben-Zvi, I.; Skaritka, J.

    1997-07-01

    A new iron dominated single emittance compensation solenoidal magnet was designed to be integrated with the BNL/SLAC/UCLA 1.6 cell S-Band Photocathode rf Gun. This emittance compensated photoinjector is now in operation at the Brookhaven Accelerator Test Facility. It has produced a 0.329 {+-} 0.012 pC, {tau}{sub 95%} = 10.9 psec electron bunches with a normalized rms transverse emittance of {epsilon}{sub n,rms} = 1.17 {+-} 0.16 {pi} mm mrad. POISSON field maps were used with PARMELA to optimize the emittance compensation solenoidal magnet design. Magnetic field measurements show that at the cathode plane B{sub z} {le} 10 G for a peak magnetic field of B{sub z,max} = 3 kG. Which is in agreement with POISSON simulation. A single emittance compensation solenoidal magnet will produces an initial angular momentum of the electron bunch that manifests itself in a initial magnetic emittance term that cannot be eliminated. This magnetic emittance {epsilon}{sub n,rms}{sup mag} scales as 0.010 {pi} mm mrad/G as the cathode, which is in agreement with PARMELA simulations. Experimental beam dynamics results are presented that shows relative angular rotation and spot size as a function of cathode magnetic field. These results are compared to theory.

  20. Theoretical and Experimental Results Regarding LENR/CF

    SciTech Connect

    Robert W. Bass; Wm. Stan Gleeson

    2000-11-12

    We challenge the predominant view that low-energy nuclear reactions (LENRs) are prohibited by standard quantum mechanics (QM). This view, supposedly based on standard nuclear theory, need not apply in condensed-matter environments. These considerations indicate that seemingly novel experimental evidence of rapid aneutronic bulk-process transmutation, at extraordinarily low-energy levels, in a simple electrochemical reactor, can occur. This explains: (a) induced rapid decay of radioactive thorium into stable nuclides, e.g., Cu and (b) resulting, anomalous distribution of Cu isotopes. We reexamine arguments of Peebles cited as evidence that standard QM 'forbids' cold fusion (CF). We note oversimplifications in those and present an alternative, more sophisticated calculation (see Bass, Refs. 3 through 8) demonstrating that conventional wisdom about impenetrability of the 'Coulomb barrier' fails as a result of periodic-order-induced resonance. We also examine empirical evidence. In three independent tests of an LENR electrolysis cell, using different I-V-T (current/voltage/time) protocols, the percentage of radiation reduction (RR) transmutation achieved {eta}=[23{percent}, 50{percent}, 83{percent}] versus expended energy E=[0.6535, 32.5, 74.6] (Watt-hours), obtained by numerical integration of recorded product I{center_dot}V for processing time T, provides near-perfect straight-line correlation: {eta}={alpha}{center_dot}E + {eta}{sub 0}, {alpha}=0.8105, {eta}{sub 0}=22.888, (0.65 < E < 0.75).

  1. Recent experimental results of KSTAR RF heating and current drive

    SciTech Connect

    Wang, S. J. Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-10

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  2. Recent experimental results of KSTAR RF heating and current drive

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-01

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  3. Experimental Results of Hydrate Reservoir Destabilization Through Heating

    NASA Astrophysics Data System (ADS)

    Leeman, J.; Hornbach, M. J.; Elwood-Madden, M.; Phelps, T. J.; Rawn, C. J.

    2011-12-01

    Gas clathrate reservoirs have been considered as possible sources of energy, as hazards to deep water drilling operations, and as contributors to global climate change. Clathrate destabilization may occur through depressurization of the reservoir, addition of chemical inhibitors, or heating the reservoir. Meso-scale heat conduction experiments were conducted in the Seafloor Process Simulator (SPS) at Oak Ridge National Laboratory in an attempt to apply experimental constraints to purely numerical models of heat transfer within a nearly isobaric reservoir. A column of saturated sediment was place inside the pressure vessel and pressurized to conditions sufficient to form methane clathrate at seafloor temperatures, while the system remained at room temperature (298K). Once pressurized, the temperature of the vessel was then lowered to approximately 275K, forming pore filling clathrate in the sediment column. Following hydrate formation, heat was supplied to the center of the clathrate reservoir through a hot fluid heat exchanger embedded in the sediment column to dissociate the methane hydrate. Relative changes in temperature within the hydrate-sediment column were monitored with a fiber optic quasi-distributed sensing system (DSS), along with temperature and pressure within the vessel headspace. Using the DSS Plotter analysis software, it was determined that an axis-symmetric section of clathrate was dissociated around the heat exchanger. Clathrate dissociation was accompanied by a small rise in vessel headspace pressure in addition to the expected thermal expansion of the headspace gas. The quantity of heat input to the system was calculated from the drop in fluid temperature as it flowed through the heat exchanger. Increased heat input resulted in an increase in the volume of hydrate dissociated. Clathrate rapidly reformed immediately upon the removal of the heat energy. A simple numerical model has been developed to simulate the heat flow in the system. Early

  4. Design and experimental results of coaxial circuits for gyroklystron amplifiers

    SciTech Connect

    Flaherty, M.K.E.; Lawson, W.; Cheng, J.; Calame, J.P.; Hogan, B.; Latham, P.E.; Granatstein, V.L.

    1994-12-31

    At the University of Maryland high power microwave source development for use in linear accelerator applications continues with the design and testing of coaxial circuits for gyroklystron amplifiers. This presentation will include experimental results from a coaxial gyroklystron that was tested on the current microwave test bed, and designs for second harmonic coaxial circuits for use in the next generation of the gyroklystron program. The authors present test results for a second harmonic coaxial circuit. Similar to previous second harmonic experiments the input cavity resonated at 9.886 GHz and the output frequency was 19.772 GHz. The coaxial insert was positioned in the input cavity and drift region. The inner conductor consisted of a tungsten rod with copper and ceramic cylinders covering its length. Two tungsten rods that bridged the space between the inner and outer conductors supported the whole assembly. The tube produced over 20 MW of output power with 17% efficiency. Beam interception by the tungsten rods resulted in minor damage. Comparisons with previous non-coaxial circuits showed that the coaxial configuration increased the parameter space over which stable operation was possible. Future experiments will feature an upgraded modulator and beam formation system capable of producing 300 MW of beam power. The fundamental frequency of operation is 8.568 GHz. A second harmonic coaxial gyroklystron circuit was designed for use in the new system. A scattering matrix code predicts a resonant frequency of 17.136 GHz and Q of 260 for the cavity with 95% of the outgoing microwaves in the desired TE032 mode. Efficiency studies of this second harmonic output cavity show 20% expected efficiency. Shorter second harmonic output cavity designs are also being investigated with expected efficiencies near 34%.

  5. Acoustic analysis in Mudejar-Gothic churches: experimental results.

    PubMed

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. PMID:15957758

  6. Acoustic analysis in Mudejar-Gothic churches: Experimental results

    NASA Astrophysics Data System (ADS)

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. .

  7. Preliminary Experimental Result of Magnetic Reconnection in Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Zhang, S. B.; Xie, J. L.; Hu, G. H.; Li, H.; Huang, G. L.; Liu, W. D.

    2011-05-01

    Magnetic reconnection is one of the most important physical processes in astrophysical plasmas. Lots of theoretical works, numerical simulations and observations have been done. Some experimental programs have been activated to investigate the basic mechanisms of magnetic reconnection. In order to investigate the electron dynamic near the electron diffusion region in magnetic reconnection process, an upgrade is accomplished in the LMP (Linear magnetic plasmas) device at University of Science and Technology of China. The magnetic field of reconnection is produced by passing two identical currents axially through two copper plates. Magnetic field and parallel electric field are measured by magnetic probes and emissive probes, respectively. The existence of a large electric field related to the reconnection process is verified. The plasma is driven by electric field and magnetic field, so the magnetic reconnection appears. The magnitude of axial current is found to scale with the number of passing particles. In the configuration of current bars, passing particles are even more and our measured axial current is about 10 A. Magnetic flux doesn't pile up because of the parameter region in our case, which is consistent with the result of numerical simulation.

  8. Experimental results on atomic oxygen corrosion of silver

    NASA Technical Reports Server (NTRS)

    Fromhold, Albert T.

    1988-01-01

    The results of an experimental study of the reaction kinetics of silver with atomic oxygen in 10 degree increments over the temperature range of 0 to 70 C is reported. The silver specimens, of the order of 10,000 A in thickness, were prepared by thermal evaporation onto 3 inch diameter polished silicon wafers. There were later sliced into pieces having surface areas of the order of 1/4 to 1/2 square inch. Atomic oxygen was generated by a gas discharge in a commercial plasmod asher operating in the megahertz frequency range. The sample temperature within the chamber was controlled by means of a thermoelectric unit. Exposure of the silver specimens to atomic oxygen was incremental, with oxide film thickness measurements being carried out between exposures by means of an automated ellipsometer. For the early growth phase, the data can be described satisfactorily by a logarithmic growth law: the oxide film thickness increases as the logarithm of the exposure time. Furthermore, the oxidation process is thermally activated, the rate increasing with increasing temperature. However, the empirical activation energy parameter deduced from Arrhenius plots is quite low, being of the order of 0.1 eV.

  9. Energy-resolved computed tomography: first experimental results

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2008-10-01

    First experimental results with energy-resolved computed tomography (CT) are reported. The contrast-to-noise ratio (CNR) in CT has been improved with x-ray energy weighting for the first time. Further, x-ray energy weighting improved the CNR in material decomposition CT when applied to CT projections prior to dual-energy subtraction. The existing CT systems use an energy (charge) integrating x-ray detector that provides a signal proportional to the energy of the x-ray photon. Thus, the x-ray photons with lower energies are scored less than those with higher energies. This underestimates contribution of lower energy photons that would provide higher contrast. The highest CNR can be achieved if the x-ray photons are scored by a factor that would increase as the x-ray energy decreases. This could be performed by detecting each x-ray photon separately and measuring its energy. The energy selective CT data could then be saved, and any weighting factor could be applied digitally to a detected x-ray photon. The CT system includes a photon counting detector with linear arrays of pixels made from cadmium zinc telluride (CZT) semiconductor. A cylindrical phantom with 10.2 cm diameter made from tissue-equivalent material was used for CT imaging. The phantom included contrast elements representing calcifications, iodine, adipose and glandular tissue. The x-ray tube voltage was 120 kVp. The energy selective CT data were acquired, and used to generate energy-weighted and material-selective CT images. The energy-weighted and material decomposition CT images were generated using a single CT scan at a fixed x-ray tube voltage. For material decomposition the x-ray spectrum was digitally spilt into low- and high-energy parts and dual-energy subtraction was applied. The x-ray energy weighting resulted in CNR improvement of calcifications and iodine by a factor of 1.40 and 1.63, respectively, as compared to conventional charge integrating CT. The x-ray energy weighting was also applied

  10. AFM investigation of Martian soil simulants on micromachined Si substrates.

    PubMed

    Vijendran, S; Sykulska, H; Pike, W T

    2007-09-01

    The micro and nanostructures of Martian soil simulants with particles in the micrometre-size range have been studied using a combination of optical and atomic force microscopy (AFM) in preparation for the 2007 NASA Phoenix Mars Lander mission. The operation of an atomic force microscope on samples of micrometre-sized soil particles is a poorly investigated area where the unwanted interaction between the scanning tip and loose particles results in poor image quality and tip contamination by the sample. In order to mitigate these effects, etched silicon substrates with a variety of features have been used to facilitate the sorting and gripping of particles. From these experiments, a number of patterns were identified that were particularly good at isolating and immobilizing particles for AFM imaging. This data was used to guide the design of micromachined substrates for the Phoenix AFM. Both individual particles as well as aggregates were successfully imaged, and information on sizes, shapes and surface morphologies were obtained. This study highlights both the strengths and weaknesses of AFM for the potential in situ investigation of Martian soil and dust. Also presented are more general findings of the limiting operational constraints that exist when attempting the AFM of high aspect ratio particles with current technology. The performance of the final designs of the substrates incorporated on Phoenix will be described in a later paper. PMID:17760618

  11. Experimental results for an experimental condensation heat exchanger with a spiral minichanel tube. Comparison to numerical imulations

    NASA Astrophysics Data System (ADS)

    Peukert, P.; Hrubý, J.

    2013-04-01

    The paper describes new results for an experimental heat exchanger equipped with a single corrugated capillary tube, basic information about the measurements and the experimental setup. Some of the results were compared with numerical simulations.

  12. Can plumes collapse?: Experimental results and applications to Iceland.

    NASA Astrophysics Data System (ADS)

    Pears, M.; Lithgow-Bertelloni, C.

    2012-04-01

    Iceland has produced magma in a series of episodic events. From lava chemistry it has been inferred that the plume temperature decreased over the first 5 Myr by ~50°C and for the next 3 Myr following continental break up it continued to oscillate by ~25°C. Such data has been used to infer possible episodic collapse of the Iceland plume. Collapsing plumes are not common fluid dynamical features. In thermochemical plumes it is possible to achieve collapse by varying the relative buoyancy due to chemistry and due to temperature. In thermal plumes however, with a constant heat source we would expect plumes not to collapse but to not continue to rise after reaching a point of neutral buoyancy. We expect thermal plumes, like those Earth's bottom thermal boundary layer is capable of producing, to either rise to the surface or be deflected but not to collapse. We have designed an experimental setup to investigate the conditions that may lead to collapse in thermal plumes with constant heat sources. We used high-Prandtl number fluids with strongly temperature-dependent viscosities (Lyle Golden syrup and Liquidose 436) as analogues to Earth's high viscosity mantle in a cubic Plexiglas tank (26.5cm inner sides), heated by a circular 2cm diameter heater (flat with the base of the tank). We explored ΔTs between 3-60°C. The flow was visualized with shadowgraphs and an automated -3D Stereoscopic Particle Image Velocimetry (SPIV) system to measure velocities. In Lyle's Golden Syrup collapse occurred at ΔTs as high as 8°C, while in Liquidose 436 the 8°C ΔT run showed only partial collapse. The difference is not unexpected given the different physical properties. Partial collapse was seen even for ΔTs as high as 50°C. Both complete and partial collapse manifested themselves as downwelling flow in the central part of the conduit. Collapse stopped in the hotter plumes when the downwelling fluid met the hottest part of the conduit. The observed results suggest that diffusive

  13. Can plumes collapse?: Experimental results and applications to Iceland

    NASA Astrophysics Data System (ADS)

    Pears, M.; Lithgow-Bertelloni, C. R.

    2011-12-01

    Iceland has produced magma in a series of episodic events. From lava chemistry it has been inferred that the plume temperature decreased over the first 5 Myr by ~50°C and for the next 3 Myr following continental break up it continued to oscillate by ~25°C. Such data has been used to infer possible episodic collapse of the Iceland plume. Collapsing plumes are not common fluid dynamical features. In thermochemical plumes it is possible to achieve collapse by varying the relative buoyancy due to chemistry and due to temperature. In thermal plumes however, with a constant heat source we would expect plumes not to collapse but to not continue to rise after reaching a point of neutral buoyancy. We expect thermal plumes, like those Earth's bottom thermal boundary layer is capable of producing, to either rise to the surface or be deflected but not to collapse. We have designed an experimental setup to investigate the conditions that may lead to collapse in thermal plumes with constant heat sources. We used high-Prandtl number fluids with strongly temperature-dependent viscosities (Lyle Golden syrup and Liquidose 436) as analogues to Earth's high viscosity mantle in a cubic Plexiglas tank (26.5cm inner sides), heated by a circular 2cm diameter heater (flat with the base of the tank). We explored ΔTs between 3-60°C. The flow was visualized with shadowgraphs and an automated -3D Stereoscopic Particle Image Velocimetry (SPIV) system to measure velocities. In Lyle's Golden Syrup collapse occurred at ΔTs as high as 8°C, while in Liquidose 436 the 8° ΔT run showed only partial collapse. The difference is not unexpected given the different physical properties. Partial collapse was seen even for ΔTs as high as 50°C. Both complete and partial collapse manifested themselves as downwelling flow in the central part of the conduit. Collapse stopped in the hotter plumes when the downwelling fluid met the hottest part of the conduit. The observed results suggest that diffusive

  14. Dynamic Strength of Peridotite at Seismic Slip Rates: Experimental Results

    NASA Astrophysics Data System (ADS)

    Del Gaudio, P.; di Toro, G.; Han, R.; Hirose, T.; Shimamoto, T.; Cocco, M.

    2006-12-01

    Ultramafic pseudotachylytes (solidified melts produced during seismic slip) decorate exhumed faults within the Balmuccia peridotite from the Ivrea zone (Italy). Unpublished studies suggest that these pseudotachylytes were produced in the upper-mantle/lower-crust. Kanamori et al. (1998) proposed extensive production of seismic melts during the Mw = 8.3 Bolivian 1994 deep focus (~600 km in depth) earthquake. It follows that seismic melting might occur in the mantle. We conducted high-velocity rock friction experiments with the Balmuccia peridotite to determine the dynamic strength of faults in the presence of ultramafic melts. During each experiment, shear stress evolved with displacement: after an initial peak shear stress, fault strength gradually decreased towards a steady-state value. Dynamic fault weakening was associated with the formation of a molten layer along the slipping zone. By performing experiments for increasing normal stresses (5 to 13 MPa) and slip rates (0.37÷1.14 m/s or ~seismic slip rates), steady-state shear stress (1) slightly increased with increasing normal stress and (2), for a given normal stress, decreased with increasing slip rate. The ratio between steady-state shear stress and normal stress was 0.13, well below the solid rock friction coefficient (~0.8). Experiments conducted under argon or fresh air flux yielded similar shear stress magnitudes, suggesting that olivine oxidation did not affect significantly the fault strength in the high-velocity experiments. The slight dependence of shear stress with normal stress suggests melt lubrication. Since the physics of melt lubrication is somehow predictable (see poster by Nielsen et al.), these experimental results might be extrapolated to the study of rupture dynamics in mantle rocks.

  15. Experimental subarachnoid haemorrhage results in multifocal axonal injury.

    PubMed

    Kummer, Terrance T; Magnoni, Sandra; MacDonald, Christine L; Dikranian, Krikor; Milner, Eric; Sorrell, James; Conte, Valeria; Benetatos, Joey J; Zipfel, Gregory J; Brody, David L

    2015-09-01

    The great majority of acute brain injury results from trauma or from disorders of the cerebrovasculature, i.e. ischaemic stroke or haemorrhage. These injuries are characterized by an initial insult that triggers a cascade of injurious cellular processes. The nature of these processes in spontaneous intracranial haemorrhage is poorly understood. Subarachnoid haemorrhage, a particularly deadly form of intracranial haemorrhage, shares key pathophysiological features with traumatic brain injury including exposure to a sudden pressure pulse. Here we provide evidence that axonal injury, a signature characteristic of traumatic brain injury, is also a prominent feature of experimental subarachnoid haemorrhage. Using histological markers of membrane disruption and cytoskeletal injury validated in analyses of traumatic brain injury, we show that axonal injury also occurs following subarachnoid haemorrhage in an animal model. Consistent with the higher prevalence of global as opposed to focal deficits after subarachnoid haemorrhage and traumatic brain injury in humans, axonal injury in this model is observed in a multifocal pattern not limited to the immediate vicinity of the ruptured artery. Ultrastructural analysis further reveals characteristic axonal membrane and cytoskeletal changes similar to those associated with traumatic axonal injury. Diffusion tensor imaging, a translational imaging technique previously validated in traumatic axonal injury, from these same specimens demonstrates decrements in anisotropy that correlate with histological axonal injury and functional outcomes. These radiological indicators identify a fibre orientation-dependent gradient of axonal injury consistent with a barotraumatic mechanism. Although traumatic and haemorrhagic acute brain injury are generally considered separately, these data suggest that a signature pathology of traumatic brain injury-axonal injury-is also a functionally significant feature of subarachnoid haemorrhage, raising

  16. Experimental subarachnoid haemorrhage results in multifocal axonal injury

    PubMed Central

    Magnoni, Sandra; MacDonald, Christine L.; Dikranian, Krikor; Milner, Eric; Sorrell, James; Conte, Valeria; Benetatos, Joey J.; Zipfel, Gregory J.; Brody, David L.

    2015-01-01

    The great majority of acute brain injury results from trauma or from disorders of the cerebrovasculature, i.e. ischaemic stroke or haemorrhage. These injuries are characterized by an initial insult that triggers a cascade of injurious cellular processes. The nature of these processes in spontaneous intracranial haemorrhage is poorly understood. Subarachnoid haemorrhage, a particularly deadly form of intracranial haemorrhage, shares key pathophysiological features with traumatic brain injury including exposure to a sudden pressure pulse. Here we provide evidence that axonal injury, a signature characteristic of traumatic brain injury, is also a prominent feature of experimental subarachnoid haemorrhage. Using histological markers of membrane disruption and cytoskeletal injury validated in analyses of traumatic brain injury, we show that axonal injury also occurs following subarachnoid haemorrhage in an animal model. Consistent with the higher prevalence of global as opposed to focal deficits after subarachnoid haemorrhage and traumatic brain injury in humans, axonal injury in this model is observed in a multifocal pattern not limited to the immediate vicinity of the ruptured artery. Ultrastructural analysis further reveals characteristic axonal membrane and cytoskeletal changes similar to those associated with traumatic axonal injury. Diffusion tensor imaging, a translational imaging technique previously validated in traumatic axonal injury, from these same specimens demonstrates decrements in anisotropy that correlate with histological axonal injury and functional outcomes. These radiological indicators identify a fibre orientation-dependent gradient of axonal injury consistent with a barotraumatic mechanism. Although traumatic and haemorrhagic acute brain injury are generally considered separately, these data suggest that a signature pathology of traumatic brain injury—axonal injury—is also a functionally significant feature of subarachnoid haemorrhage

  17. Experimental Results on Jets in pA

    NASA Astrophysics Data System (ADS)

    Appelt, Eric

    2015-04-01

    The experimentally observed reduction of jet yields in ultrarelativistic heavy ion (AA) collisions relative to proton-proton (pp) collisions is widely interpreted in terms of energy loss of a hard scattered parton traversing a quark-gluon plasma (QGP) before fragmenting into a jet of hadrons. In order to constrain proposed mechanisms of energy loss, a variety of measurements are needed that quantify both how the jet yields and jet structure are modified in the medium. However, jets may also be modified by differences in the initial state of the nucleus relative to that of the proton. The precise determination of the QGP properties relies on disentangling these additional modifications, collectively termed ``cold nuclear matter'' effects, from energy loss in the QGP. Collisions between heavy ions and protons (pA) provide a potential control environment where cold nuclear matter effects should be present, but QGP formation is generally not expected to occur. In this talk, an overview of recent jet results from proton-lead collisions produced at the LHC will be given. The yield of inclusive jets and distributions of dijet pairs are shown to be compatible with generally accepted theoretical expectations, although significant modification is observed when yields are measured from specific centrality classes of pA collision events. Some measurements of high-pT charged hadron yields suggest a larger modification in pA collisions relative to pp collisions than for inclusive jet yields. The potential implications of this difference along with other measurements relating to jet structure will be discussed.

  18. Single ricin detection by AFM chemomechanical mapping

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research reports a method of detecting ricin molecules immobilized on chemically modified gold (Au;111) surface by chemomechanically mapping the molecular interactions with a chemically modified Atomic Force Microscope (AFM) tip. AFM images resolved the different fold-up conformations of single...

  19. Effect of tip mass on frequency response and sensitivity of AFM cantilever in liquid.

    PubMed

    Farokh Payam, Amir; Fathipour, Morteza

    2015-03-01

    The effect of tip mass on the frequency response and sensitivity of atomic force microscope (AFM) cantilever in the liquid environment is investigated. For this purpose, using Euler-Bernoulli beam theory and considering tip mass and hydrodynamic functions in a liquid environment, an expression for the resonance frequencies of AFM cantilever in liquid is derived. Then, based on this expression, the effect of the surface contact stiffness on the flexural mode of a rectangular AFM cantilever in fluid is investigated and compared with the case where the AFM cantilever operates in the air. The results show that in contrast with an air environment, the tip mass has no significant impact on the resonance frequency and sensitivity of the AFM cantilever in the liquid. Hence, analysis of AFM behaviour in liquid environment by neglecting the tip mass is logical. PMID:25562584

  20. Charging C60 islands with the AFM tip.

    PubMed

    Hoff, Brice; Henry, Claude R; Barth, Clemens

    2016-01-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. PMID:26617348

  1. Mounting of Escherichia coli spheroplasts for AFM imaging.

    SciTech Connect

    Sullivan, Claretta J; Morrell-Falvey, Jennifer L; Allison, David P; Doktycz, Mitchel John

    2005-11-01

    The cytoplasmic membrane of Escherichia coli (E. coli) is the location of numerous, chemically specific transporters and recognition elements. Investigation of this membrane in vivo by atomic force microscopy (AFM) requires removal of the cell wall and stable immobilization of the spheroplast. AFM images demonstrate that spheroplasts can be secured with warm gelatin applied to the mica substrate just before the addition of a spheroplast suspension. The resulting preparation can be repeatedly imaged by AFM over the course of several hours. Confocal fluorescence imaging confirms the association of the spheroplasts with the gelatin layer. Gelatin molecules are known to reorder into a network after heating. Entrapment within this gelatin network is believed to be responsible for the immobilization of spheroplasts on mica.

  2. Surface Morphological Studies on Nerve Cells by AFM

    NASA Astrophysics Data System (ADS)

    Durkaya, Goksel; Zhong, Lei; Rehder, Vincent; Dietz, Nikolaus

    2009-03-01

    Surface morphological properties of fixed and living nerve cells removed from the buccal ganglion of Helisoma trivolvis have been studied by using Atomic Force Microscopy (AFM). Identified, individual neurons were removed from the buccal ganglion of Helisoma trivolvis and plated into poly-L-lysine coated glass cover-slips. The growth of the nerve cells was stopped and fixed with 0.1% Glutaraldehyde and 4% Formaldehyde solution after extension of growth cones at the tip of the axons. Topography and softness of growth cone filopodia and overlying lamellopodium (veil) were probed by AFM. Information obtained from AFM's amplitude and phase channels have been used for determination of softness of the region probed. The results of structural studies on the cells are linked to their mechanical properties and internal molecular density distribution.

  3. Hydrodynamic effects in fast AFM single-molecule force measurements.

    PubMed

    Janovjak, Harald; Struckmeier, Jens; Müller, Daniel J

    2005-02-01

    Atomic force microscopy (AFM) allows the critical forces that unfold single proteins and rupture individual receptor-ligand bonds to be measured. To derive the shape of the energy landscape, the dynamic strength of the system is probed at different force loading rates. This is usually achieved by varying the pulling speed between a few nm/s and a few microm/s, although for a more complete investigation of the kinetic properties higher speeds are desirable. Above 10 microm/s, the hydrodynamic drag force acting on the AFM cantilever reaches the same order of magnitude as the molecular forces. This has limited the maximum pulling speed in AFM single-molecule force spectroscopy experiments. Here, we present an approach for considering these hydrodynamic effects, thereby allowing a correct evaluation of AFM force measurements recorded over an extended range of pulling speeds (and thus loading rates). To support and illustrate our theoretical considerations, we experimentally evaluated the mechanical unfolding of a multi-domain protein recorded at 30 microm/s pulling speed. PMID:15257425

  4. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    NASA Technical Reports Server (NTRS)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 C temperature increase from the nominal vapor temperature. The 19 C temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  5. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    NASA Technical Reports Server (NTRS)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  6. GPIM AF-M315E Propulsion System

    NASA Technical Reports Server (NTRS)

    Spores, Ronald A.; Masse, Robert; Kimbrel, Scott; McLean, Chris

    2014-01-01

    The NASA Space Technology mission Directorate's (STMD) Green Propellant Infusion Mission (GPIM) Technology Demonstration Mission (TDM) will demonstrate an operational AF-M315E green propellant propulsion system. Aerojet-Rocketdyne is responsible for the development of the propulsion system payload. This paper statuses the propulsion system module development, including thruster design and system design; Initial test results for the 1N engineering model thruster are presented. The culmination of this program will be high-performance, green AF-M315E propulsion system technology at TRL 7+, with components demonstrated to TRL 9, ready for direct infusion to a wide range of applications for the space user community.

  7. Charging C60 islands with the AFM tip

    NASA Astrophysics Data System (ADS)

    Hoff, Brice; Henry, Claude R.; Barth, Clemens

    2015-12-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system.We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR04541J

  8. Experimental results from a reverse flow annual combustor

    NASA Astrophysics Data System (ADS)

    Joubert, F. M.; Hattingh, H. V.

    Computer-predicted temperature distributions in the wall liners of a combustion chamber were compared to the experimentally obtained values from combustion tests carried out in a small, full-scale reverse-flow annular combustor at sea level take-off conditionns. The largest discrepancies between the measured and predicted linear temperatures occured in the primary zone, with most of the predictions falling above the measured values, and with neither of the two computer programs satisfying the accuracy of 4 percent (of the experimental values) needed for making estimates on the life of a combustor. On the other hand, the correlation between the measured and predicted liner pressure drop was satisfactory. The validity and usefulnes of simple computer models as aids in the design of gas turbine combustion chambers are discussed.

  9. CP Violation in B Meson Decays: Experimental Results

    SciTech Connect

    Lanceri, Livio; /Trieste U. /INFN, Trieste

    2005-08-30

    CP violation is intimately connected with the puzzle of matter-antimatter asymmetry and baryogenesis. In the Standard Model of particle physics, the observed CP violation phenomena are accounted for by the Cabibbo-Kobayashi-Maskawa mechanism involving a phase in the quark mixing matrix. This paper is devoted to a review of the experimental status of CP violation in the decays of B mesons.

  10. Experimental Results for an Annular Aerospike with Differential Throttling

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph H.; McDaniels, David M.

    2005-01-01

    A) MSFC funded an internal study on Altitude Compensating Nozzles: 1) Develop an ACN design and performance prediction tool. 2) Design, build and test cold flow ACN nozzles. 3) An annular aerospike nozzle was designed and tested. 4) Incorporated differential throttling to assess Thrust Vector Control. B) Objective of the test hardware: 1) Provide design tool verification. 2) Provide benchmark data for CFD calculations. 3) Experimentally measure side force, or TVC, for a differentially throttled annular aerospike.

  11. Optimal active vibration absorber - Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1993-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  12. Experimental overview of Generalized Parton Distribution results from HERMES

    SciTech Connect

    Zihlmann, B.

    2009-08-04

    Over the course of more than a decade the HERMES experiment has accumulated a wealth of data with electron and positron beams on various gaseous targets from Hydrogen up to Xenon. In addition, the beams and targets can be polarized. This data set is viewed in the context of Generalized Parton Distributions, a theoretical formalism with an explicit three dimensional view of the structure of the nucleon. It provides a link between experimental observables and the total angular momentum of the quarks in the nucleon.

  13. RFI in hybrid loops - Simulation and experimental results.

    NASA Technical Reports Server (NTRS)

    Ziemer, R. E.; Nelson, D. R.; Raghavan, H. R.

    1972-01-01

    A digital simulation of an imperfect second-order hybrid phase-locked loop (HPLL) operating in radio frequency interference (RFI) is described. Its performance is characterized in terms of phase error variance and phase error probability density function (PDF). Monte-Carlo simulation is used to show that the HPLL can be superior to the conventional phase-locked loops in RFI backgrounds when minimum phase error variance is the goodness criterion. Similar experimentally obtained data are given in support of the simulation data.

  14. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  15. Optimal active vibration absorber: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  16. High-fidelity AFM scanning stage based on multilayer ceramic capacitors.

    PubMed

    Chen, Jian; Zhang, Lian Sheng; Feng, Zhi Hua

    2016-05-01

    A kind of multilayer ceramic capacitors (MLCCs) has been verified to have good micro-actuating properties, thus making them good candidates for nano-positioning. In this paper, we successfully employed the MLCCs as lateral scanners for a tripod scanning stage. The MLCC-based lateral scanners display hysteresis under 1.5% and a nonlinearity less than 2% even with the simplest open-loop voltage drive. The developed scanning stage was integrated into a commercial AFM to evaluate its imaging performance. Experimental results showed that sample images with high fidelities were obtained. SCANNING 38:184-190, 2016. © 2015 Wiley Periodicals, Inc. PMID:26367125

  17. Titanium as reactor material for SCWO applications. First experimental results

    SciTech Connect

    Boukis, N.; Friedrich, C.; Dinjus, E.

    1998-12-31

    According to literature data, nickel base alloys are not sufficiently corrosion resistant in chloride bearing SCWO environments. Titanium was proposed several times as a suitable material for the construction of a corrosion resistant reactor. Titanium does not show the required mechanical strength for high temperature high pressure applications and it can only be used to form liners for an SCWO apparatus. Therefore, pressure tubes made of alloy 625 were lined with titanium grade 2. Additionally corrosion tests with coupons made of titanium grades 2, 5, 7, 12 and {beta}-C were performed. The coupons were placed inside an alumina-lined reactor. Materials were exposed to simulated SCWO feeds consisting of water, oxygen and HCl, H{sub 2}SO{sub 4}, or H{sub 3}PO{sub 4}. Experimental temperatures were up to 600 C, pressures up to 27 MPa and experimental times up to 200 hours. Corrosion in chloride containing solution is low. In the presence of sulfate or phosphate, corrosion of titanium grade 2 becomes severe. For these environments an upper limit of the corrosion rate could be estimated.

  18. CSI Flight Computer System and experimental test results

    NASA Technical Reports Server (NTRS)

    Sparks, Dean W., Jr.; Peri, F., Jr.; Schuler, P.

    1993-01-01

    This paper describes the CSI Computer System (CCS) and the experimental tests performed to validate its functionality. This system is comprised of two major components: the space flight qualified Excitation and Damping Subsystem (EDS) which performs controls calculations; and the Remote Interface Unit (RIU) which is used for data acquisition, transmission, and filtering. The flight-like RIU is the interface between the EDS and the sensors and actuators positioned on the particular structure under control. The EDS and RIU communicate over the MIL-STD-1553B, a space flight qualified bus. To test the CCS under realistic conditions, it was connected to the Phase-0 CSI Evolutionary Model (CEM) at NASA Langley Research Center. The following schematic shows how the CCS is connected to the CEM. Various tests were performed which validated the ability of the system to perform control/structures experiments.

  19. Experimental results on spin physics at the AGS

    SciTech Connect

    Makdisi, Y.I.

    1986-01-01

    The AGS ran with polarized protons towards the end of 1985 and through the first two months of 1986. This comprised commissioning periods interleaved with two runs for physics at 13.5 GeV/c with beam polarization of 50 to 60%, and 18.5 GeV/c with an average beam polarization of 40%. Later, the AGS polarized beam reached peak energy of 22 GeV/c and polarization of 46%. This article describes the various spin related experimental efforts since the VI Symposium at Marseille. These will be grouped into those using unpolarized beams and the rest are the polarized proton beam users. Afterwards the future of the program is described as extensions of current experiments in addition to other measurements that are yet to be proposed.

  20. Experimental results for a microscale ethanol vapor jet ejector

    NASA Astrophysics Data System (ADS)

    Gardner, W. G.; Jaworski, J. W.; Camacho, A. P.; Protz, J. M.

    2010-04-01

    A microscale jet ejector driven by ethanol vapor is designed and tested to induce a suction draft using a supersonic converging-diverging micronozzle. A three-dimensional axisymmetric nozzle is fabricated using electro-discharge machining to produce a throat diameter of 187 µm with an expansion ratio of 3:1. The motive nozzle achieves a design mass flow efficiency of 93% compared to isentropic calculations. Two different ejector area ratios are compared using ethanol vapor and nitrogen gas separately to motivate and entrain ambient air. The experimental data indicate that the ejector can produce a sufficient suction draft to satisfy both microengine mass flow and power off-take requirements to enable its substitution for high-speed microscale pumping turbomachinery.

  1. Geoacoustic and source tracking using particle filtering: experimental results.

    PubMed

    Yardim, Caglar; Gerstoft, Peter; Hodgkiss, William S

    2010-07-01

    A particle filtering (PF) approach is presented for performing sequential geoacoustic inversion of a complex ocean acoustic environment using a moving acoustic source. This approach treats both the environmental parameters [e.g., water column sound speed profile (SSP), water depth, sediment and bottom parameters] at the source location and the source parameters (e.g., source depth, range and speed) as unknown random variables that evolve as the source moves. This allows real-time updating of the environment and accurate tracking of the moving source. As a sequential Monte Carlo technique that operates on nonlinear systems with non-Gaussian probability densities, the PF is an ideal algorithm to perform tracking of environmental and source parameters, and their uncertainties via the evolving posterior probability densities. The approach is demonstrated on both simulated data in a shallow water environment with a sloping bottom and experimental data collected during the SWellEx-96 experiment. PMID:20649203

  2. ezAFM: A low cost Atomic Force Microscope(AFM)

    NASA Astrophysics Data System (ADS)

    Celik, Umit; Celik, Kubra; Aslan, Husnu; Kehribar, Ihsan; Dede, Munir; Ozgur Ozer, H.; Oral, Ahmet

    2012-02-01

    A low cost AFM, ezAFM is developed for educational purposes as well as research. Optical beam deflection method is used to measure the deflection of cantilever. ezAFM scanner is built using voice coil motors (VCM) with ˜50x50x6 μm scan area. The microscope uses alignment free cantilevers, which minimizes setup times. FPGA based AFM feedback Control electronics is developed. FPGA technology allows us to drive all peripherals in parallel. ezAFM Controller is connected to PC by USB 2.0 interface as well as Wi-Fi. We have achieved <5nm lateral and ˜0.01nm vertical resolution. ezAFM can image single atomic steps in HOPG and mica. An optical microscope with <3 μm resolution is also integrated into the system. ezAFM supports different AFM operation modes such as dynamic mode, contact mode, lateral force microscopy. Advanced modes like magnetic force microscopy and electric force microscopy will be implemented later on. The new ezAFM system provides, short learning times for student labs, quick setup and easy to transport for portable applications with the best price/performance ratio. The cost of the system starts from 15,000, with system performance comparable with the traditional AFM systems.

  3. Implementation of a four quadrant optic fibre bundle as a deflection sensor to get rid of heat sources in an AFM head

    NASA Astrophysics Data System (ADS)

    Boukellal, Younes; Ducourtieux, Sebastien

    2015-09-01

    In the frame of developing a thermally passive atomic force microscope head, a new kind of 2D displacement sensor based on a four quadrant optic fibre bundle has been implemented. The aim is to replace the quad cell photodiode used in the optical beam deflection method to detect cantilever deflection. The use of the bundle as a position sensor has already been modelled and experimentally evaluated in a previous work. This article reports on the implementation of the bundle as a deflection sensor for atomic force microscopy. The main motivation for such a development was to reduce the heat sources in the instrument. To reach this goal the photodiode and its conditioning circuit used for the measurement of cantilever deflection has been externalized from the AFM head. For the same reason, the laser diode and its electronic driver have been deported using optic fibre. To test the AFM head prototype in real conditions, approach curves and AFM images have been performed. The results show that the bundle is very well suited for AFM applications that require very low heat sources such as metrological AFM where each error source has to be managed.

  4. Hydrodynamic effects of the tip movement on surface nanobubbles: a combined tapping mode, lift mode and force volume mode AFM study.

    PubMed

    Walczyk, Wiktoria; Hain, Nicole; Schönherr, Holger

    2014-08-28

    We report on an Atomic Force Microscopy (AFM) study of AFM tip-nanobubble interactions in experiments conducted on argon surface nanobubbles on HOPG (highly oriented pyrolytic graphite) in water in tapping mode, lift mode and Force Volume (FV) mode AFM. By subsequent data acquisition on the same nanobubbles in these three different AFM modes, we could directly compare the effect of different tip-sample interactions. The tip-bubble interaction strength was found to depend on the vertical and horizontal position of the tip on the bubble with respect to the bubble center. The interaction forces measured experimentally were in good agreement with the forces calculated using the dynamic interaction model. The strength of the hydrodynamic effect was also found to depend on the direction of the tip movement. It was more pronounced in the FV mode, in which the tip approaches the bubble from the top, than in the lift mode, in which the tip approaches the bubble from the side. This result suggests that the direction of tip movement influences the bubble deformation. The effect should be taken into account when nanobubbles are analysed by AFM in various scanning modes. PMID:24988375

  5. Construction of a WMR for Trajectory Tracking Control: Experimental Results

    PubMed Central

    Silva-Ortigoza, R.; Márquez-Sánchez, C.; Marcelino-Aranda, M.; Marciano-Melchor, M.; Silva-Ortigoza, G.; Bautista-Quintero, R.; Ramos-Silvestre, E. R.; Rivera-Díaz, J. C.; Muñoz-Carrillo, D.

    2013-01-01

    This paper reports a solution for trajectory tracking control of a differential drive wheeled mobile robot (WMR) based on a hierarchical approach. The general design and construction of the WMR are described. The hierarchical controller proposed has two components: a high-level control and a low-level control. The high-level control law is based on an input-output linearization scheme for the robot kinematic model, which provides the desired angular velocity profiles that the WMR has to track in order to achieve the desired position (x∗, y∗) and orientation (φ∗). Then, a low-level control law, based on a proportional integral (PI) approach, is designed to control the velocity of the WMR wheels to ensure those tracking features. Regarding the trajectories, this paper provides the solution or the following cases: (1) time-varying parametric trajectories such as straight lines and parabolas and (2) smooth curves fitted by cubic splines which are generated by the desired data points {(x1∗, y1∗),..., (xn∗, yn∗)}. A straightforward algorithm is developed for constructing the cubic splines. Finally, this paper includes an experimental validation of the proposed technique by employing a DS1104 dSPACE electronic board along with MATLAB/Simulink software. PMID:23997679

  6. EXPERIMENTAL RESULTS FROM A MICROWAVE CAVITY BEAM POSITION MONITOR.

    SciTech Connect

    BALAKIN,V.; BAZHAN,A.; LUNEV,P.; SOLYAK,N.; VOGEL,V.; ZHOGOLEV,P.; LISITSYN,A.; YAKIMENKO,V.

    1999-03-29

    Future Linear Colliders have hard requirements for the beam transverse position stability in the accelerator. A beam Position Monitor (BPM) with the resolution better than 0.1 micron in the single bunch regime is needed to control the stability of the beam position along the linac. Proposed BPM is based on the measurement of the asymmetrical mode excited by single bunch in the cavity. Four stages of signal processing (space-, time-, frequency- and phase-filtering providing the required signal-to-noise ratio) are used to obtain extremely high resolution. The measurement set-up was designed by BINP and installed at ATF/BNL to test experimentally this concept. The set-up includes three two-coordinates BPM's at the frequency of 13.566 GHz, and reference intensity/phase cavity. BPM's were mounted on support table. The two-coordinates movers allow to move and align BPM's along the straight line, using the signals from the beam. The position of each monitor is controlled by the sensors with the accuracy 0.03 micron. The information from three monitors allows to exclude angle and position jitter of the beam and measure BPM resolution. In the experiments the resolution of about 0.15 micron for 0.25 nC beam intensity was obtained, that is close to the value required.

  7. Modeling of rock friction 1. Experimental results and constitutive equations

    USGS Publications Warehouse

    Dieterich, J.H.

    1979-01-01

    Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of ??6 MPa demonstrate that competing time, displacement, and velocity effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip is also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability. Copyright ?? 1979 by the American Geophysical Union.

  8. Construction of a WMR for trajectory tracking control: experimental results.

    PubMed

    Silva-Ortigoza, R; Márquez-Sánchez, C; Marcelino-Aranda, M; Marciano-Melchor, M; Silva-Ortigoza, G; Bautista-Quintero, R; Ramos-Silvestre, E R; Rivera-Díaz, J C; Muñoz-Carrillo, D

    2013-01-01

    This paper reports a solution for trajectory tracking control of a differential drive wheeled mobile robot (WMR) based on a hierarchical approach. The general design and construction of the WMR are described. The hierarchical controller proposed has two components: a high-level control and a low-level control. The high-level control law is based on an input-output linearization scheme for the robot kinematic model, which provides the desired angular velocity profiles that the WMR has to track in order to achieve the desired position (x∗, y∗) and orientation (φ∗). Then, a low-level control law, based on a proportional integral (PI) approach, is designed to control the velocity of the WMR wheels to ensure those tracking features. Regarding the trajectories, this paper provides the solution or the following cases: (1) time-varying parametric trajectories such as straight lines and parabolas and (2) smooth curves fitted by cubic splines which are generated by the desired data points {(x₁∗, y₁∗),..., (x(n)∗, y(n)∗)}. A straightforward algorithm is developed for constructing the cubic splines. Finally, this paper includes an experimental validation of the proposed technique by employing a DS1104 dSPACE electronic board along with MATLAB/Simulink software. PMID:23997679

  9. Experimental results with hydrogen fueled internal combustion engines

    NASA Technical Reports Server (NTRS)

    De Boer, P. C. T.; Mclean, W. J.; Homan, H. S.

    1975-01-01

    The paper focuses on the most important experimental findings for hydrogen-fueled internal combustion engines, with particular reference to the application of these findings to the assessment of the potential of hydrogen engines. Emphasis is on the various tradeoffs that can be made, such as between maximum efficiency, maximum power, and minimum NO emissions. The various possibilities for induction and ignition are described. Some projections are made about areas in which hydrogen engines may find their initial application and about optimum ways to design such engines. It is shown that hydrogen-fueled reciprocal internal combustion engines offer important advantages with respect to thermal efficiency and exhaust emissions. Problems arising from preignition can suitably be avoided by restricting the fuel-air equivalence ratio to values below about 0.5. The direct cylinder injection appears to be a very attractive way to operate the engine, because it combines a wide range of possible power outputs with a high thermal efficiency and very low NO emissions at part loads.

  10. AFM CHARACTERIZATION OF LASER INDUCED DAMAGE ON CDZNTE CRYSTAL SURFACES

    SciTech Connect

    Hawkins, S; Lucile Teague, L; Martine Duff, M; Eliel Villa-Aleman, E

    2008-06-10

    Semi-conducting CdZnTe (or CZT) crystals can be used in a variety of detector-type applications. CZT shows great promise for use as a gamma radiation spectrometer. However, its performance is adversely affected by point defects, structural and compositional heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), secondary phases and in some cases, damage caused by external forces. One example is damage that occurs during characterization of the surface by a laser during Raman spectroscopy. Even minimal laser power can cause Te enriched areas on the surface to appear. The Raman spectra resulting from measurements at moderate intensity laser power show large increases in peak intensity that is attributed to Te. Atomic Force Microscopy (AFM) was used to characterize the extent of damage to the CZT crystal surface following exposure to the Raman laser. AFM data reveal localized surface damage in the areas exposed to the Raman laser beam. The degree of surface damage to the crystal is dependent on the laser power, with the most observable damage occurring at high laser power. Moreover, intensity increases in the Te peaks of the Raman spectra are observed even at low laser power with little to no visible damage observed by AFM. AFM results also suggest that exposure to the same amount of laser power yields different amounts of surface damage depending on whether the exposed surface is the Te terminating face or the Cd terminating face of CZT.

  11. Experimental test results of a generalized parameter fuel control

    NASA Technical Reports Server (NTRS)

    Batterton, P. G.; Gold, H.

    1973-01-01

    Considerable interest has been generated recently in low cost jet propulsion systems. One of the more complicated components of jet engines is the fuel control. Results of an effort to develop a simpler hydromechanical fuel control are presented. This prototype fuel control was installed on a J85-GE-13 jet engine. Results show that the fuel control provided satisfactory engine performance at sea level static conditions over its normal nonafterburning operating range, including startup. Results of both bench and engine tests are presented; the difficulties encountered are described.

  12. An advanced AFM sensor: its profile accuracy and low probe wear property for high aspect ratio patterns

    NASA Astrophysics Data System (ADS)

    Watanabe, Masahiro; Baba, Shuichi; Nakata, Toshihiko; Kurenuma, Toru; Kunitomo, Yuichi; Edamura, Manabu

    2007-03-01

    Design rule shrinkage and wider adoption of new device structures such as STI, copper damascene interconnects, and deep trench structures have made the need for in-line process monitoring of step heights and profiles of device structures more urgent. To monitor active device patterns, as opposed to test patterns as in OCD, AFM is the only non-destructive 3D monitoring tool. The barriers to using AFM in-line monitoring are its slow throughput and the accuracy degradation associated with probe tip wear and spike noise caused by unwanted oscillation on the steep slopes of high-aspect-ratio patterns. Our proprietary AFM scanning method, StepIn TM mode, is the method best suited to measuring high-aspect-ratio pattern profiles. Because the probe is not dragged on the sample surface as in conventional AFM, the profile trace fidelity across steep slopes is excellent. Because the probe does not oscillate and hit the sample at a high frequency, as in AC scanning mode, this mode is free from unwanted spurious noises on steep sample slopes and incurs extremely little probe tip wear. To take full advantage of the above properties, we have developed an AFM sensor that is optimized for in-line use and produces accurate profile data at high speeds and incurs little probe tip wear. The control scheme we have developed for the AFM sensor, which we call "Advanced StepIn TM", elaborately analyses the contact force signal, enabling efficient probe tip scanning and a low and stable contact force. With a developed AFM sensor that realizes this concept, we conducted an intensive evaluation on the effect of low and stable contact force scan. Probes with HDC (high density carbon) tips were used for the evaluation. The experiment proves that low contact force enhances the measured profile fidelity by preventing probe tip slip on steep slopes. Dynamics simulation of these phenomena was also conducted, and its results agreed well with the experimental results. The low contact force scan also

  13. Primary simulation and experimental results of a coaxial plasma accelerator

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Huang, J.; Han, J.; Zhang, Z.; Quan, R.; Wang, L.; Yang, X.; Feng, C.

    A coaxial plasma accelerator with a compressing coil is developed to simulate the impacting and erosion effect of space debris on exposed materials of spacecrafts During its adjustment operation some measurements are conducted including discharging current by Rogowski coil average plasma speed in the coaxial gun by magnetic coils and ejected particle speed by piezoelectric sensor etc In concert with the experiment a primary physical model is constructed in which only the coaxial gun is taken into account with the compressor coil not considered for its unimportant contribution to the plasma ejection speed The calculation results by the model agree well with the diagnostic results considering some assumptions for simplification Based on the simulation result some important suggestions for optimum design and adjustment of the accelerator are obtained for its later operation

  14. Railgun hybrid armatures, experimental results and performance characteristics

    NASA Astrophysics Data System (ADS)

    Crawford, Roger; Keefer, Dennis; Sedghinasab, Ahad

    1991-01-01

    Six hybrid armature designs were evaluated in the UTSI one-centimeter square-bore railgun. Advanced diagnostic instrumentation was used to determine the characteristics of hybrid armatures which include a compound armature (current in plasma brushes to the metal armature followed by a plasma armature). The hybrid armatures were compact, with shorter current distributions than plasma armatures as measured with both optical and electromagnetic probes. Although the results are preliminary, due to the limited geometries investigated, the results are very encouraging. The short (less than one-bore-diameter) hybrids demonstrated efficiencies equal to or greater than plasma armatures and good armature stability.

  15. Pegasus liner stability experiments: Diagnostics and experimental results

    SciTech Connect

    Clark, D.A.; Morgan, D.V.; Rodriguez, G.

    1998-12-31

    A series of experiments to compare imploding cylindrical liner performance with Magneto-HydroDynamic (MHD) modeling has been performed at the Los Alamos National Laboratory Pegasus capacitor bank. Several configurations of aluminum liners have been used; some with initial perturbations and some smooth. Instability growth resulting from the perturbations has been observed with high resolution. Load diagnostics included radial x-rays, fiber optic impact pins, and VISAR (Velocity Interferometer for a Surface of Any Reflector). Diagnostic results and comparisons for several liner stability (LS) experiments are presented.

  16. Conductive supports for combined AFM SECM on biological membranes

    NASA Astrophysics Data System (ADS)

    Frederix, Patrick L. T. M.; Bosshart, Patrick D.; Akiyama, Terunobu; Chami, Mohamed; Gullo, Maurizio R.; Blackstock, Jason J.; Dooleweerdt, Karin; de Rooij, Nico F.; Staufer, Urs; Engel, Andreas

    2008-09-01

    Four different conductive supports are analysed regarding their suitability for combined atomic force and scanning electrochemical microscopy (AFM-SECM) on biological membranes. Highly oriented pyrolytic graphite (HOPG), MoS2, template stripped gold, and template stripped platinum are compared as supports for high resolution imaging of reconstituted membrane proteins or native membranes, and as electrodes for transferring electrons from or to a redox molecule. We demonstrate that high resolution topographs of the bacterial outer membrane protein F can be recorded by contact mode AFM on all four supports. Electrochemical feedback experiments with conductive cantilevers that feature nanometre-scale electrodes showed fast re-oxidation of the redox couple Ru(NH3)63+/2+ with the two metal supports after prolonged immersion in electrolyte. In contrast, the re-oxidation rates decayed quickly to unpractical levels with HOPG or MoS2 under physiological conditions. On HOPG we observed heterogeneity in the re-oxidation rate of the redox molecules with higher feedback currents at step edges. The latter results demonstrate the capability of conductive cantilevers with small electrodes to measure minor variations in an SECM signal and to relate them to nanometre-scale features in a simultaneously recorded AFM topography. Rapid decay of re-oxidation rate and surface heterogeneity make HOPG or MoS2 less attractive for combined AFM-SECM experiments on biological membranes than template stripped gold or platinum supports.

  17. Qualitative versus Quantitative Results: An Experimental Introduction to Data Interpretation.

    ERIC Educational Resources Information Center

    Johnson, Eric R.; Alter, Paula

    1989-01-01

    Described is an experiment in which the student can ascertain the meaning of a negative result from a qualitative test by performing a more sensitive quantitative test on the same sample. Methodology for testing urinary glucose with a spectrophotometer at 630 nm and with commercial assaying glucose strips is presented. (MVL)

  18. Comments on experimental results of energy confinement of tokamak plasmas

    SciTech Connect

    Chu, T.K.

    1989-04-01

    The results of energy-confinement experiments on steady-state tokamak plasmas are examined. For plasmas with auxiliary heating, an analysis based on the heat diffusion equation is used to define heat confinement time (the incremental energy confinement time). For ohmically sustained plasmas, experiments show that the onset of the saturation regime of energy confinement, marfeing, detachment, and disruption are marked by distinct values of the parameter /bar n//sub e///bar j/. The confinement results of the two types of experiments can be described by a single surface in 3-dimensional space spanned by the plasma energy, the heating power, and the plasma density: the incremental energy confinement time /tau//sub inc/ = ..delta..W/..delta..P is the correct concept for describing results of heat confinement in a heating experiment; the commonly used energy confinement time defined by /tau//sub E/ = W/P is not. A further examination shows that the change of edge parameters, as characterized by the change of the effective collision frequency ..nu../sub e/*, governs the change of confinement properties. The totality of the results of tokamak experiments on energy confinement appears to support a hypothesis that energy transport is determined by the preservation of the pressure gradient scale length. 70 refs., 6 figs., 1 tab.

  19. Joint Soviet-American experiment on hypokinesia: Experimental results

    NASA Technical Reports Server (NTRS)

    Burovskiy, N. N.

    1979-01-01

    Comprehensive results are reported from the Soviet portion of a joint Soviet-American experiment involving hypokinesia. The main emphases are on chemical analyses of blood and urine, functional tests, and examination of the cardiovascular system by electrocardiography, echocardiography, and plethysmography.

  20. Recent Experimental Results from Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Sangster, T. C.; Goncharov, V. N.; Radha, P. B.; Betti, R.; Boehly, T. R.; Glebov, V. Yu.; Hu, S. X.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Seka, W.; Smalyuk, V. A.; Frenje, J. A.; Petrasso, R. D.; Shvarts, D.

    2008-11-01

    The implosion performance of energy-scaled cryogenic D2 and DT targets on the 60-beam OMEGA laser is important for understanding the physics of highly compressed fuel and the validation of ignition designs for the NIF. Recent experiments have demonstrated good performance using a multi-shock drive that has been tuned based on cryogenic cone-in-shell targets. Fuel areal densities are now consistently exceeding 80% of the 1-D prediction, while the yields are between 10% and 20% of 1-D predictions. These results demonstrate the benefit (and necessity) of an independent shock-timing platform. This talk will present the latest implosion performance results and potentially show the first cryogenic-fuel-core radiographs using a short pulse beam from the new OMEGA EP Laser Facility. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

  1. The behavior of delaminations in composite materials - experimental results

    NASA Astrophysics Data System (ADS)

    Chermoshentseva, A. S.; Pokrovskiy, A. M.; Bokhoeva, L. A.

    2016-02-01

    Delamination is one of the most common failure modes of composite materials. It may occur as a consequence of imperfections in the production process or the effects of external factors during the operational life of the composite laminates, such as the impact by foreign objects. This paper presents the results of mechanical tests and the optimum degrees of filling the composite materials (CM) with hydrophobic powder (Tarkosil T-20) depending on the latter mass concentration. The results present test samples of the CM with the underlying interlayer defects. The samples were fabricated of twenty-ply pre-preg (fiberglass or carbon fiber). The industrial grade glass is T-25 (VM) specification 6-11-380-76. The composite materials have nanosized additives in structure. The volume concentration of nanopowders is varying from 0.1% to 0.5%. This kind of research has been done for the first time.

  2. Delaminations in composite plates under transverse static loads - Experimental results

    NASA Technical Reports Server (NTRS)

    Finn, Scott R.; He, Yi-Fei; Springer, George S.

    1992-01-01

    Tests were performed measuring the damage initiation loads and the locations, shapes, and sizes of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite-PEEK plates subjected to transverse static loads. The data were compared to the results of the Finn-Springer model, and good agreements were found between the measured and calculated delamination lengths and widths.

  3. Nano Mechanical Machining Using AFM Probe

    NASA Astrophysics Data System (ADS)

    Mostofa, Md. Golam

    Complex miniaturized components with high form accuracy will play key roles in the future development of many products, as they provide portability, disposability, lower material consumption in production, low power consumption during operation, lower sample requirements for testing, and higher heat transfer due to their very high surface-to-volume ratio. Given the high market demand for such micro and nano featured components, different manufacturing methods have been developed for their fabrication. Some of the common technologies in micro/nano fabrication are photolithography, electron beam lithography, X-ray lithography and other semiconductor processing techniques. Although these methods are capable of fabricating micro/nano structures with a resolution of less than a few nanometers, some of the shortcomings associated with these methods, such as high production costs for customized products, limited material choices, necessitate the development of other fabricating techniques. Micro/nano mechanical machining, such an atomic force microscope (AFM) probe based nano fabrication, has, therefore, been used to overcome some the major restrictions of the traditional processes. This technique removes material from the workpiece by engaging micro/nano size cutting tool (i.e. AFM probe) and is applicable on a wider range of materials compared to the photolithographic process. In spite of the unique benefits of nano mechanical machining, there are also some challenges with this technique, since the scale is reduced, such as size effects, burr formations, chip adhesions, fragility of tools and tool wear. Moreover, AFM based machining does not have any rotational movement, which makes fabrication of 3D features more difficult. Thus, vibration-assisted machining is introduced into AFM probe based nano mechanical machining to overcome the limitations associated with the conventional AFM probe based scratching method. Vibration-assisted machining reduced the cutting forces

  4. Experimental results on the atmospheric muon charge ratio

    NASA Astrophysics Data System (ADS)

    Mauri, N.

    2016-07-01

    The atmospheric muon charge ratio, defined as the number of positive over negative charged muons, is a highly informative observable both for cosmic rays and particle physics. It allows studying the features of high-energy hadronic interactions in the forward region and the composition of primary cosmic rays. In this review results from underground experiments measuring the charge ratio around 1 TeV are discussed. The measurements in the TeV energy region constrain the associated kaon production, which is particularly important e.g. for the calculation of the atmospheric neutrino flux.

  5. Delaminations in composite plates under transverse impact loads - Experimental results

    NASA Technical Reports Server (NTRS)

    Finn, Scott R.; He, Ye-Fei; Springer, George S.

    1993-01-01

    Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

  6. Persistent GMTI surveillance: theoretical performance bounds and some experimental results

    NASA Astrophysics Data System (ADS)

    Balaji, Bhashyam; Damini, Anthony; Wang, Kai

    2010-04-01

    In certain operational radar modes, slow ground moving targets are detected over several processing intervals using space-time adaptive processing. This enables use of Bayesian filtering and smoothing algorithms for estimation of time-varying moving target parameters. In this paper, some Bayesian filtering algorithms are investigated. The Craḿer-Rao bounds based on subsets of radar measurements (range, angle and Doppler) are derived for typical maneuvering targets and compared against simulated results from Bayesian filters. The performance is also evaluated using real data obtained from DRDC Ottawa's XWEAR radar.

  7. Parallel and Distributed Computational Fluid Dynamics: Experimental Results and Challenges

    NASA Technical Reports Server (NTRS)

    Djomehri, Mohammad Jahed; Biswas, R.; VanderWijngaart, R.; Yarrow, M.

    2000-01-01

    This paper describes several results of parallel and distributed computing using a large scale production flow solver program. A coarse grained parallelization based on clustering of discretization grids combined with partitioning of large grids for load balancing is presented. An assessment is given of its performance on distributed and distributed-shared memory platforms using large scale scientific problems. An experiment with this solver, adapted to a Wide Area Network execution environment is presented. We also give a comparative performance assessment of computation and communication times on both the tightly and loosely-coupled machines.

  8. Mars ionosphere: A review of experimental results and modeling studies

    NASA Astrophysics Data System (ADS)

    Haider, S. A.; Mahajan, K. K.; Kallio, E.

    2011-10-01

    In this paper we review results from atmospheric and ionospheric experiments on the early planetary missions like the Mariners, Mars, and Viking 1 and 2 Orbiters/Landers. We then discuss the new results obtained from the two latest missions, namely, the Mars Global Surveyor (MGS) and Mars Express (MEX). The MGS had three ionospheric and atmospheric related experiments, namely, (1) the radio science experiment, which generated 5600 electron density profiles covering a major portion of sunspot cycle 23; (2) the magnetometer/electron reflectometer experiment, which very clearly answered the question about the presence or absence of Martian intrinsic magnetic field; and (3) the accelerometer experiment, which provided a large database of atmospheric density at various Martian locations during the aerobraking phases. The topside sounder on the MEX provided electron density profiles for altitudes above the primary ionospheric peak with a very high time resolution, thereby providing opportunity for exploring ionospheric conditions during events of rapid changes like solar flares. Unlike Venus, where simultaneous electron density, ion density, and magnetic field measurements were made, Mars lacks this kind of information. Consequently, most of our current understanding of Mars' plasma environment is based on theoretical models. We therefore review the various atmospheric and ionospheric models for Mars, which have been generated during the last 4 decades.

  9. Experimental Results of Guided Wave Travel Time Tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Bloom, Joost

    2011-06-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation matches very well with the objective to reduce cost while maintaining a high safety level. Guided waves are very attractive for permanent monitoring systems because they can travel over large distances and therefore provide the essential large area coverage. Making use of the dispersive behavior of the guided waves, a wall thickness map over a distance of several meters can be made using only two rings of guided wave transducers. Travel time tomography is used to translate transmission travel times into a wall thickness map. This method has been applied in the field for the first time to map the wall thickness under two clearly corroded pipe supports of a 8″ and 10″ gas pipe line. The tomographic inversion results clearly maps the corrosion under the supports. Independent reference measurements confirm the tomographic inversion results.

  10. Space Launch System Base Heating Test: Experimental Operations & Results

    NASA Technical Reports Server (NTRS)

    Dufrene, Aaron; Mehta, Manish; MacLean, Matthew; Seaford, Mark; Holden, Michael

    2016-01-01

    NASA's Space Launch System (SLS) uses four clustered liquid rocket engines along with two solid rocket boosters. The interaction between all six rocket exhaust plumes will produce a complex and severe thermal environment in the base of the vehicle. This work focuses on a recent 2% scale, hot-fire SLS base heating test. These base heating tests are short-duration tests executed with chamber pressures near the full-scale values with gaseous hydrogen/oxygen engines and RSRMV analogous solid propellant motors. The LENS II shock tunnel/Ludwieg tube tunnel was used at or near flight duplicated conditions up to Mach 5. Model development was based on the Space Shuttle base heating tests with several improvements including doubling of the maximum chamber pressures and duplication of freestream conditions. Test methodology and conditions are presented, and base heating results from 76 runs are reported in non-dimensional form. Regions of high heating are identified and comparisons of various configuration and conditions are highlighted. Base pressure and radiometer results are also reported.

  11. IP voice over ATM satellite: experimental results over satellite channels

    NASA Astrophysics Data System (ADS)

    Saraf, Koroush A.; Butts, Norman P.

    1999-01-01

    IP telephony, a new technology to provide voice communication over traditional data networks, has the potential to revolutionize telephone communication within the modern enterprise. This innovation uses packetization techniques to carry voice conversations over IP networks. This packet switched technology promises new integrated services, and lower cost long-distance communication compared to traditional circuit switched telephone networks. Future satellites will need to carry IP traffic efficiently in order to stay competitive in servicing the global data- networking and global telephony infrastructure. However, the effects of Voice over IP over switched satellite channels have not been investigated in detail. To fully understand the effects of satellite channels on Voice over IP quality; several experiments were conducted at Lockheed Martin Telecommunications' Satellite Integration Lab. The result of those experiments along with suggested improvements for voice communication over satellite are presented in this document. First, a detailed introduction of IP telephony as a suitable technology for voice communication over future satellites is presented. This is followed by procedures for the experiments, along with results and strategies. In conclusion we hope that these capability demonstrations will alleviate any uncertainty regarding the applicability of this technology to satellite networks.

  12. Acceleration and torque feedback for robotic control - Experimental results

    NASA Technical Reports Server (NTRS)

    Mclnroy, John E.; Saridis, George N.

    1990-01-01

    Gross motion control of robotic manipulators typically requires significant on-line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.

  13. Experimental Results from Oak Ridge Isomer Spectrometer and Separator (ORISS)

    NASA Astrophysics Data System (ADS)

    Piechaczek, A.; Batchelder, J. C.; Carter, H. K.; Goans, R. E.; Liu, S.; Shchepunov, V.; Zganjar, E. F.; Unirib Collaboration

    2013-10-01

    ORISS is a linear multi reflection time-of-flight mass analyzer developed by the University Radioactive Ion Beam Consortium. It will be used to separate any isobar and many isomers for decay spectroscopy experiments. The entire system's operation was demonstrated with a less than ideal multi-isotopic ion source and achieved a mass resolving power as high as 430,000. To better characterize the system we have installed a monoisotopic 133Cs ion source. The radiofrequency quadrupole ion cooler and buncher, which serves as the ion injector into ORISS, was tested in stand-alone mode and achieved a longitudinal emittance of 22 π eV × ns and transmission >40%. These very good results confirm our expectation that ORISS can achieve the design goals. Using the improved ion source, we expect, very soon, to demonstrate the complete system's design goals of 400,000 mass resolving power and 50% transmission.

  14. Experimental results on low alpha electron-storage rings

    SciTech Connect

    Robin, D.; Hama, H.; Nadji, A.

    1995-09-01

    The authors report on experiments performed in two synchrotron light sources, UVSOR and Super-ACO, where the momentum compaction factor is reduced in order to reduce the bunch length. By controlling the second-order momentum compaction factor, UVSOR and Super-ACO have managed to reduce the first-order momentum compaction factor by 100. At low current the resulting bunch lengths are less than 10 ps, a factor of 10 smaller than normal. Measurements of current dependent bunch lengthening in UVSOR are presented and the cause of the bunch lengthening is determined to be potential-well distortion. The authors also show that by operating with a negative momentum compaction factor, SuperACO has achieved shorter bunch lengthening and higher peak currents than at positive momentum compaction.

  15. Microgravity Fluid Separation Physics: Experimental and Analytical Results

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. Michael; Schrage, Dean S.

    1997-01-01

    Effective, low power, two-phase separation systems are vital for the cost-effective study and utilization of two-phase flow systems and flow physics of two-phase flows. The study of microgravity flows have the potential to reveal significant insight into the controlling mechanisms for the behavior of flows in both normal and reduced gravity environments. The microgravity environment results in a reduction in gravity induced buoyancy forces acting on the discrete phases. Thus, surface tension, viscous, and inertial forces exert an increased influence on the behavior of the flow as demonstrated by the axisymmetric flow patterns. Several space technology and operations groups have studied the flow behavior in reduced gravity since gas-liquid flows are encountered in several systems such as cabin humidity control, wastewater treatment, thermal management, and Rankine power systems.

  16. Wide-field Fizeau imaging telescope: experimental results.

    PubMed

    Kendrick, R L; Aubrun, Jean-Noel; Bell, Ray; Benson, Robert; Benson, Larry; Brace, David; Breakwell, John; Burriesci, Larry; Byler, Eric; Camp, John; Cross, Gene; Cuneo, Peter; Dean, Peter; Digumerthi, Ramji; Duncan, Alan; Farley, John; Green, Andy; Hamilton, Howard H; Herman, Bruce; Lauraitis, Kris; de Leon, Erich; Lorell, Kenneth; Martin, Rob; Matosian, Ken; Muench, Tom; Ni, Mel; Palmer, Alice; Roseman, Dennis; Russell, Sheldon; Schweiger, Paul; Sigler, Rob; Smith, John; Stone, Richard; Stubbs, David; Swietek, Gregg; Thatcher, John; Tischhauser, C; Wong, Harvey; Zarifis, Vassilis; Gleichman, Kurt; Paxman, Rick

    2006-06-20

    A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described. PMID:16778931

  17. New experimental results in atlas-based brain morphometry

    NASA Astrophysics Data System (ADS)

    Gee, James C.; Fabella, Brian A.; Fernandes, Siddharth E.; Turetsky, Bruce I.; Gur, Ruben C.; Gur, Raquel E.

    1999-05-01

    In a previous meeting, we described a computational approach to MRI morphometry, in which a spatial warp mapping a reference or atlas image into anatomic alignment with the subject is first inferred. Shape differences with respect to the atlas are then studied by calculating the pointwise Jacobian determinant for the warp, which provides a measure of the change in differential volume about a point in the reference as it transforms to its corresponding position in the subject. In this paper, the method is used to analyze sex differences in the shape and size of the corpus callosum in an ongoing study of a large population of normal controls. The preliminary results of the current analysis support findings in the literature that have observed the splenium to be larger in females than in males.

  18. M-I-S solar cell - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Childs, R.; Fortuna, J.; Geneczko, J.; Fonash, S. J.

    1976-01-01

    The paper presents an operating-mode analysis of an MIS solar cell and discusses the advantages which can arise as a result of the use of transport control, field shaping (increased n factor), and zero bias barrier height modification. It is noted that for an n-type semiconductor, it is relatively easy to obtain an enhanced n factor using acceptor-like states without an increase in diode saturation current, the converse being true for p-type semiconductors. Several MIS configurations are examined: an acceptor-like, localized state configuration producing field shaping and no change in diode saturation current, and acceptor-like localized configurations producing field shaping, with a decrease of diode saturation current, in one case, and an increase in the other.

  19. Experimental Results in DIS, SIDIS and DES from Jefferson Lab

    SciTech Connect

    Kuhn, Sebastian E.

    2011-07-15

    Jefferson Lab's electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering--DIS--at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum-dependent (TMD) structure functions using Semi-Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic space will become available. The 12 GeV program taking shape will complete a detailed mapping of inclusive, TMD and generalized distribution functions for quarks, antiquarks and gluons in the valence region and beyond.

  20. Experimental Results in DIS, SIDIS and DES from Jefferson Lab

    SciTech Connect

    Sebastian Kuhn

    2011-07-01

    Jefferson Lab's electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum-dependent (TMD) structure functions using Semi-Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic space will become available. The 12 GeV program taking shape will complete a detailed mapping of inclusive, TMD and generalized distribution functions for quarks, antiquarks and gluons in the valence region and beyond.

  1. Longitudinal variation of the equatorial ionosphere: Modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Souza, J. R.; Asevedo, W. D.; dos Santos, P. C. P.; Petry, A.; Bailey, G. J.; Batista, I. S.; Abdu, M. A.

    2013-02-01

    We describe a new version of the Parameterized Regional Ionospheric Model (PARIM) which has been modified to include the longitudinal dependences. This model has been reconstructed using multidimensional Fourier series. To validate PARIM results, the South America maps of critical frequencies for the E (foE) and F (foF2) regions were compared with the values calculated by Sheffield Plasmasphere-Ionosphere Model (SUPIM) and IRI representations. PARIM presents very good results, the general characteristics of both regions, mainly the presence of the equatorial ionization anomaly, were well reproduced for equinoctial conditions of solar minimum and maximum. The values of foF2 and hmF2 recorded over Jicamarca (12°S; 77°W; dip lat. 1°N; mag. declination 0.3°) and sites of the conjugate point equatorial experiment (COPEX) campaign Boa Vista (2.8°N; 60.7°W; dip lat. 11.4°; mag. declination -13.1°), Cachimbo (9.5°S; 54.8°W; dip lat. -1.8°; mag. declination -15.5°), and Campo Grande (20.4°S; 54.6°W; dip lat. -11.1°; mag. declination -14.0°) have been used in this work. foF2 calculated by PARIM show good agreement with the observations, except during morning over Boa Vista and midnight-morning over Campo Grande. Some discrepancies were also found for the F-region peak height (hmF2) near the geomagnetic equator during times of F3 layer occurrences. IRI has underestimated both foF2 and hmF2 over equatorial and low latitude sectors during evening-nighttimes, except for Jicamarca where foF2 values were overestimated.

  2. Experimental results: Pilot plant calcine dissolution and liquid feed stability

    SciTech Connect

    Herbst, R.S.; Fryer, D.S.; Brewer, K.N.; Johnson, C.K.; Todd, T.A.

    1995-02-01

    The dissolution of simulated Idaho Chemical Processing Plant pilot plant calcines, containing none of the radioactive actinides, lanthanides or fission products, was examined to evaluate the solubility of calcine matrix materials in acidic media. This study was a necessary precursor to dissolution and optimization experiments with actual radionuclide-containing calcines. The importance of temperature, nitric acid concentration, ratio of acid volume to calcine mass, and time on the amount, as a weight percentage of calcine dissolved, was evaluated. These parameters were studied for several representative pilot plant calcine types: (1) Run No. 74 Zirconia calcine; (2) Run No. 17 Zirconia/Sodium calcine; (3) Run No. 64 Zirconia/Sodium calcine; (3) Run No. 1027 Alumina calcine; and (4) Run No. 20 Alumina/Zirconia/Sodium calcine. Statistically designed experiments with the different pilot plant calcines indicated the effect of the studied process variables on the amount of calcine dissolved decreases in the order: Acid/Calcine Ratio > Temperature > HNO{sub 3} Concentration > Dissolution Time. The following conditions are suitable to achieve greater than 90 wt. % dissolution of most Zr, Al, or Na blend calcines: (1) Maximum nitric acid concentration of 5M; (2) Minimum acid/calcine ratio of 10 mL acid/1 gram calcine; (3) Minimum dissolution temperature of 90{degrees}C; and (4) Minimum dissolution time of 30 minutes. The formation of calcium sulphate (CaSO{sub 4}) precipitates was observed in certain dissolved calcine solutions during the dissolution experiments. Consequently, a study was initiated to evaluate if and under what conditions the resulting dissolved calcine solutions would be unstable with regards to precipitate formation. The results indicate that precipitate formation in the calcine solutions prepared under the above proposed dissolution conditions are not anticipated.

  3. First experimental results on the IShTAR testbed

    NASA Astrophysics Data System (ADS)

    D'Inca, R.; Jacquot, J.; Ochoukov, R.; Morgal, I.; Crombe, K.; Louche, F.; Van Eester, D.; Heuraux, S.; Devaux, S.; Moritz, J.; Faudot, E.; Fünfgelder, H.; Faugel, H.; Noterdaeme, J.-M.

    2015-12-01

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetized plasma test facility dedicated to the investigation of RF wave/plasma interaction [1] in the Ion Cyclotron Range of Frequencies (ICRF). It provides a better accessibility for the instrumentation than tokamaks while being representative of the neighboring region of the wave emitter. It is equipped with a magnetized plasma source (1 m long, 0.4 m diameter) powered by a helical antenna up to 3 kW at 11 MHz. We present the results of the first analysis of the plasma characteristics (plasma density, electron temperature) in function of the operating parameters (injected power, neutral pressure and magnetic field) as measured with fixed and movable Langmuir probes, spectrometer and cameras. The plasma is presently produced only by the helical antenna (no ICRF). We show that the plasma exists in three regime depending on the power level: the first two ones are stable and separated by a jump in density; a first spatial profile of the plasma density has been established for these modes; The third mode is unstable, characterized by strong oscillations of the plasma tube position.

  4. Experimental Results of Integrated Refrigeration and Storage System Testing

    NASA Technical Reports Server (NTRS)

    Notardonato, W. U.; Johnson, W. L.; Jumper, K.

    2009-01-01

    Launch operations engineers at the Kennedy Space Center have identified an Integrated Refrigeration and Storage system as a promising technology to reduce launch costs and enable advanced cryogenic operations. This system uses a close cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for the potential of a zero loss storage and transfer system, as well and control of the state of the propellant through densification or re-liquefaction. However, the behavior of the fluid in this type of system is different than typical cryogenic behavior, and there will be a learning curve associated with its use. A 400 liter research cryostat has been designed, fabricated and delivered to KSC to test the thermo fluid behavior of liquid oxygen as energy is removed from the cryogen by a simulated DC cycle cryocooler. Results of the initial testing phase focusing on heat exchanger characterization and zero loss storage operations using liquid oxygen are presented in this paper. Future plans for testing of oxygen densification tests and oxygen liquefaction tests will also be discussed. KEYWORDS: Liquid Oxygen, Refrigeration, Storage

  5. Experimental Results on Electrorheology of Liquid Crystalline Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Neves, S.; Leal, C. R.; Cidade, M. T.

    2008-07-01

    The electrorheological (ER) effect is known as the enhancement of the apparent viscosity upon application of an external electric field. Suspensions of polarizable particles in non-conducting solvents are the most studied electrorheological fluids, however, liquid crystalline materials may also present ER effect as long as their dielectric anisotropy is positive. In the liquid crystalline state of a positive dielectric anisotropy, the application of the electric field makes the director align perpendicular to the flow direction, thus increasing the apparent viscosity. In this work results of two liquid crystalline polymer solutions, acetoxypropylcellulose (APC) in dimethylacetamide (DMAc) and poly-γ-benzyl-L-glutamate (PBLG) in 1,4-dioxane, presenting opposite behavior upon application of the electric field, will be presented. APC/DMAc (negative dielectric anisotropy) presents a decrease of the apparent viscosity upon application of the electric field, as expected, while PBLG/1,4-dioxane (positive dielectric anisotropy) presents the opposite behavior. For this last solution we will present the shear flow curves for different electric fields in function of polymer molecular weight and solution concentration.

  6. The experimental results and analysis of a borehole radar prototype

    NASA Astrophysics Data System (ADS)

    Liu, Sixin; Wu, Junjun; Dong, Hang; Fu, Lei; Wang, Fei

    2012-04-01

    A prototype of borehole radar has been successfully tested in three sites for different purposes under a field condition. The objective of the prototype is providing an effective down-hole tool for detecting targets in deep boreholes situated in a relatively high conductivity area such as the metal ores. The first testing site is at a geothermal field. The fractures extending more than 20 m from the borehole are delineated by the borehole radar in the single-hole reflection mode. The second testing site is located in a jade mine for basement evaluation. The cross-hole measurement mode was used to detect the cavities made by previous unorganized mining activities. Several high-velocity anomalies were found in the velocity profile and presumably the targets of the mine shafts and tunnels. The third test site is located in a mineralized belt characterized by low resistivity less than 1000 Ohm m, the surface-borehole measurement was carried out and the data were processed with velocity tomography. The low-velocity zone corresponds to a mineralized zone from geological records. The three testing results proved the readiness of this borehole radar prototype for further deployment in more complicated and realistic field situations.

  7. Infrared thermography for CFRP inspection: computational model and experimental results

    NASA Astrophysics Data System (ADS)

    Fernandes, Henrique C.; Zhang, Hai; Morioka, Karen; Ibarra-Castanedo, Clemente; López, Fernando; Maldague, Xavier P. V.; Tarpani, José R.

    2016-05-01

    Infrared Thermography (IRT) is a well-known Non-destructive Testing (NDT) technique. In the last decades, it has been widely applied in several fields including inspection of composite materials (CM), specially the fiber-reinforced polymer matrix ones. Consequently, it is important to develop and improve efficient NDT techniques to inspect and assess the quality of CM parts in order to warranty airworthiness and, at the same time, reduce costs of airline companies. In this paper, active IRT is used to inspect carbon fiber-reinforced polymer (CFRP) at laminate with artificial inserts (built-in sample) placed on different layers prior to the manufacture. Two optical active IRT are used. The first is pulsed thermography (PT) which is the most widely utilized IRT technique. The second is a line-scan thermography (LST) technique: a dynamic technique, which can be employed for the inspection of materials by heating a component, line-by-line, while acquiring a series of thermograms with an infrared camera. It is especially suitable for inspection of large parts as well as complex shaped parts. A computational model developed using COMSOL Multiphysics® was used in order to simulate the inspections. Sequences obtained from PT and LST were processed using principal component thermography (PCT) for comparison. Results showed that it is possible to detect insertions of different sizes at different depths using both PT and LST IRT techniques.

  8. First experimental results on the IShTAR testbed

    SciTech Connect

    D’Inca, R.; Jacquot, J.; Ochoukov, R.; Morgal, I.; Fünfgelder, H.; Faugel, H.; Crombe, K.; Louche, F.; Van Eester, D.; Heuraux, S.; Devaux, S.; Moritz, J.; Faudot, E.; Noterdaeme, J.-M.

    2015-12-10

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetized plasma test facility dedicated to the investigation of RF wave/plasma interaction [1] in the Ion Cyclotron Range of Frequencies (ICRF). It provides a better accessibility for the instrumentation than tokamaks while being representative of the neighboring region of the wave emitter. It is equipped with a magnetized plasma source (1 m long, 0.4 m diameter) powered by a helical antenna up to 3 kW at 11 MHz. We present the results of the first analysis of the plasma characteristics (plasma density, electron temperature) in function of the operating parameters (injected power, neutral pressure and magnetic field) as measured with fixed and movable Langmuir probes, spectrometer and cameras. The plasma is presently produced only by the helical antenna (no ICRF). We show that the plasma exists in three regime depending on the power level: the first two ones are stable and separated by a jump in density; a first spatial profile of the plasma density has been established for these modes; The third mode is unstable, characterized by strong oscillations of the plasma tube position.

  9. Impact ejecta dynamics in an atmosphere - Experimental results and extrapolations

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.; Gault, D. E.

    1982-01-01

    It is noted that the impacts of 0.635-cm aluminum projectiles at 6 km/sec into fine pumice dust, at 1 atm, generate a ball of ionized gas behind an expanding curtain of upward moving ejecta. The gas ball forms a toroid which dissolves as it is driven along the interior of the ejecta curtain, by contrast to near-surface explosions in which a fireball envelops early-time crater growth. High frame rate Schlieren photographs show that the atmosphere at the base of the ejecta curtain is initially turbulent, but later forms a vortex. These experiments suggest that although small size ejecta may be decelerated by air drag, they are not simply lofted and suspended but become incorporated in an ejecta cloud that is controlled by air flow which is produced by the response of the atmosphere to the impact. The extrapolation of these results to large body impacts on the earth suggests such contrasts with laboratory experiments as a large quantity of impact-generated vapor, the supersonic advance of the ejecta curtain, the lessened effect of air drag due to the tenuous upper atmosphere, and the role of secondary cratering.

  10. Bridge Testing With Ground-Based Interferometric Radar: Experimental Results

    NASA Astrophysics Data System (ADS)

    Chiara, P.; Morelli, A.

    2010-05-01

    The research of innovative non-contact techniques aimed at the vibration measurement of civil engineering structures (also for damage detection and structural health monitoring) is continuously directed to the optimization of measures and methods. Ground-Based Radar Interferometry (GBRI) represents the more recent technique available for static and dynamic control of structures and ground movements. Dynamic testing of bridges and buildings in operational conditions are currently performed: (a) to assess the conformity of the structure to the project design at the end of construction; (b) to identify the modal parameters (i.e. natural frequencies, mode shapes and damping ratios) and to check the variation of any modal parameters over the years; (c) to evaluate the amplitude of the structural response to special load conditions (i.e. strong winds, earthquakes, heavy railway or roadway loads). If such tests are carried out by using a non-contact technique (like GBRI), the classical issues of contact sensors (like accelerometers) are easily overtaken. This paper presents and discusses the results of various tests carried out on full-scale bridges by using a Stepped Frequency-Continuous Wave radar system.

  11. Bridge Testing With Ground-Based Interferometric Radar: Experimental Results

    SciTech Connect

    Chiara, P.; Morelli, A.

    2010-05-28

    The research of innovative non-contact techniques aimed at the vibration measurement of civil engineering structures (also for damage detection and structural health monitoring) is continuously directed to the optimization of measures and methods. Ground-Based Radar Interferometry (GBRI) represents the more recent technique available for static and dynamic control of structures and ground movements.Dynamic testing of bridges and buildings in operational conditions are currently performed: (a) to assess the conformity of the structure to the project design at the end of construction; (b) to identify the modal parameters (i.e. natural frequencies, mode shapes and damping ratios) and to check the variation of any modal parameters over the years; (c) to evaluate the amplitude of the structural response to special load conditions (i.e. strong winds, earthquakes, heavy railway or roadway loads). If such tests are carried out by using a non-contact technique (like GBRI), the classical issues of contact sensors (like accelerometers) are easily overtaken.This paper presents and discusses the results of various tests carried out on full-scale bridges by using a Stepped Frequency-Continuous Wave radar system.

  12. Sodium-layer laser-guide-star experimental results

    SciTech Connect

    Avicola, K.; Brase, J.M.; Morris, J.R.

    1994-02-01

    The authors describe a series of experiments to characterize the sodium-layer guide star that was formed with the highpower laser developed for the Lawrence Livermore National Laboratory Atomic Vapor Laser Isotope Separation program. An emission spot size of 3.0 m was measured, with an implied laser irradiance spot diameter of 2.0 m. The rms spot motion at the higher laser powers, with active beam-pointing control, was less than 0.5 arcsec and had little effect on the observed spot size under these conditions. The authors measured the resonant backscatter from the sodium layer as a function of laser power to obtain a saturation curve. With a transmitted power of 1100 W and an atmospheric transmission of 0.6, the irradiance from the guide star at the ground was 10 (photons/cm{sup 2})/ms, corresponding to a visual magnitude of 5.1. The implications for the performance of wave-front sensors with a laser guide star of this magnitude and resulting closed-loop adaptive-optics performance are discussed. 13 refs., 9 figs.

  13. EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY

    SciTech Connect

    Fox, K.; Edwards, T.

    2009-11-09

    This study is the third phase in a series of experiments designed to reduce conservatism in the model that predicts the formation of nepheline, a crystalline phase that can reduce the durability of high level waste glass. A Phase I study developed a series of glass compositions that were very durable while their nepheline discriminator values were well below the current nepheline discriminator limit of 0.62, where nepheline is predicted to crystallize upon slow cooling. A Phase II study selected glass compositions to identify any linear effects of composition on nepheline crystallization and that were restricted to regions that fell within the validation ranges of the Defense Waste Processing Facility (DWPF) Product Composition Control System (PCCS) models. However, it was not possible to identify any linear effects of composition on chemical durability performance for this set of study glasses. The results of the Phase II study alone were not sufficient to recommend modification of the current nepheline discriminator. It was recommended that the next series of experiments continue to focus not only on compositional regions where the PCCS models are considered applicable (i.e., the model validation ranges), but also be restricted to compositional regions where the only constraint limiting processing is the current nepheline discriminator. Two methods were used in selecting glasses for this Phase III nepheline study. The first was based on the relationship of the current nepheline discriminator model to the other DWPF PCCS models, and the second was based on theory of crystallization in mineral and glass melts. A series of 29 test glass compositions was selected for this study using a combination of the two approaches. The glasses were fabricated and characterized in the laboratory. After reviewing the data, the study glasses generally met the target compositions with little issue. Product Consistency Test results correlated well with the crystallization analyses in

  14. OPERA and MINOS Experimental Result Prove Big Bang Theory Invalid

    NASA Astrophysics Data System (ADS)

    Pressler, David E.

    2012-03-01

    The greatest error in the history of science is the misinterpretation of the Michelson-Morley Experiment. The speed of light was measured to travel at the same speed in all three directions (x, y, z axis) in ones own inertial reference system; however, c will always be measured as having an absolute different speed in all other inertial frames at different energy levels. Time slows down due to motion or a gravity field. Time is the rate of physical process. Speed = Distance/Time. If the time changes the distance must change. Therefore, BOTH mirrors must move towards the center of the interferometer and space must contract in all-three-directions; C-Space. Gravity is a C-Space condition, and is the cause of redshift in our universe-not motion. The universe is not expanding. OPERA results are directly indicated; at the surface of earth, the strength of the gravity field is at maximum-below the earth's surface, time and space is less distorted, C-Space; therefore, c is faster. Newtonian mechanics dictate that a spherical shell of matter at greater radii, with uniform density, produces no net force on an observer located centrally. An observer located on the sphere's surface, like our Earth's or a large sphere, like one located in a remote galaxy, will construct a picture centered on himself to be identical to the one centered inside the spherical shell of mass. Both observers will view the incoming radiation, emitted by the other observer, as redshifted, because they lay on each others radial line. The Universe is static and very old.

  15. Impact Flash Physics: Modeling and Comparisons With Experimental Results

    NASA Astrophysics Data System (ADS)

    Rainey, E.; Stickle, A. M.; Ernst, C. M.; Schultz, P. H.; Mehta, N. L.; Brown, R. C.; Swaminathan, P. K.; Michaelis, C. H.; Erlandson, R. E.

    2015-12-01

    horizontal. High-speed radiometer measurements were made of the time-dependent impact flash at wavelengths of 350-1100 nm. We will present comparisons between these measurements and the output of APL's model. The results of this validation allow us to determine basic relationships between observed optical signatures and impact conditions.

  16. Tissue section AFM: In situ ultrastructural imaging of native biomolecules

    PubMed Central

    Graham, Helen K.; Hodson, Nigel W.; Hoyland, Judith A.; Millward-Sadler, Sarah J.; Garrod, David; Scothern, Anthea; Griffiths, Christopher E.M.; Watson, Rachel E.B.; Cox, Thomas R.; Erler, Janine T.; Trafford, Andrew W.; Sherratt, Michael J.

    2010-01-01

    Conventional approaches for ultrastructural high-resolution imaging of biological specimens induce profound changes in bio-molecular structures. By combining tissue cryo-sectioning with non-destructive atomic force microscopy (AFM) imaging we have developed a methodology that may be applied by the non-specialist to both preserve and visualize bio-molecular structures (in particular extracellular matrix assemblies) in situ. This tissue section AFM technique is capable of: i) resolving nm–µm scale features of intra- and extracellular structures in tissue cryo-sections; ii) imaging the same tissue region before and after experimental interventions; iii) combining ultrastructural imaging with complimentary microscopical and micromechanical methods. Here, we employ this technique to: i) visualize the macro-molecular structures of unstained and unfixed fibrillar collagens (in skin, cartilage and intervertebral disc), elastic fibres (in aorta and lung), desmosomes (in nasal epithelium) and mitochondria (in heart); ii) quantify the ultrastructural effects of sequential collagenase digestion on a single elastic fibre; iii) correlate optical (auto fluorescent) with ultrastructural (AFM) images of aortic elastic lamellae. PMID:20144712

  17. STM and AFM; Which is Better for Surface Structural Analysis? Non- contact AFM Studies on Ge/Si(105) Surface

    NASA Astrophysics Data System (ADS)

    Hasegawa, Yukio

    2006-03-01

    Scanning tunneling microscopy (STM) has been utilized to determine surface atomic structure with its highly resolved images. Probing surface electronic states near the Fermi energy (EF), STM images, however, do not necessarily represent the atomic structure of surfaces. It has been believed that atomic force microscopy (AFM) provides us surface topographic images without being disturbed by the electronic states. In order to prove the surpassing performance, we performed noncontact (nc) AFM on the Ge/Si(105) surface [1], which is a facet plane of the ?hut? clusters formed on Ge-deposited Si(001) surface. It is found that STM images taken on the surface, either filled- or empty-state images, do not show all surface atoms because of the electronic effect; some surface atoms have dangling bond states below EF and other surface atoms have states above EF. [2]. In a nc-AFM image, on the other hand, all surface atoms having a dangling bond are observed [3], directly representing an atomic structure of the surface. Electronic information can also be obtained in AFM by using a Kelvin-probe method. From atomically resolved potential profile we obtained, charge transfer among the dangling bond states is directly demonstrated. These results clearly demonstrate that highly-resolved nc-AFM with a Kelvin-probe method is an ideal tool for analysis of atomic structures and electronic properties of surfaces. This work was done in collaboration with T. Eguchi, K. Akiyama, T. An, and M. Ono, ISSP, Univ. Tokyo and JST, Y. Fujikawa and T. Sakurai, IMR. Tohoku Univ. T. Hashimoto, AIST, Y. Morikawa, ISIR, Osaka Univ. K. Terakura, Hokkaido Univ., and M.G. Lagally, University of Wisconsin-Madison. [1] T. Eguchi et al., Phys. Rev. Lett. 93, 266102 (2004). [2] Y. Fujikawa et al., Phys. Rev. Lett. 88, 176101 (2002). [3] T. Eguchi and Y. Hasegawa, Phys. Rev. Lett. 89, 256105 (2002)

  18. Solid Electrolyte/Electrode Interfaces: Atomistic Behavior Analyzed Via UHV-AFM, Surface Spectroscopies, and Computer Simulations Computational and Experimental Studies of the Cathode/Electrolyte Interface in Oxide Thin Film Batteries

    SciTech Connect

    Garofalini, Stephen H

    2012-03-21

    The goals of the research were to understand the structural, dynamic, and chemical properties of solid electrolyte surfaces and the cathode/electrolyte interface at an atomistic and nanometer level using both computational and experimental techniques.

  19. AFM indentation study of breast cancer cells

    SciTech Connect

    Li, Q.S.; Lee, G.Y.H.; Ong, C.N.; Lim, C.T.

    2008-10-03

    Mechanical properties of individual living cells are known to be closely related to the health and function of the human body. Here, atomic force microscopy (AFM) indentation using a micro-sized spherical probe was carried out to characterize the elasticity of benign (MCF-10A) and cancerous (MCF-7) human breast epithelial cells. AFM imaging and confocal fluorescence imaging were also used to investigate their corresponding sub-membrane cytoskeletal structures. Malignant (MCF-7) breast cells were found to have an apparent Young's modulus significantly lower (1.4-1.8 times) than that of their non-malignant (MCF-10A) counterparts at physiological temperature (37 deg. C), and their apparent Young's modulus increase with loading rate. Both confocal and AFM images showed a significant difference in the organization of their sub-membrane actin structures which directly contribute to their difference in cell elasticity. This change may have facilitated easy migration and invasion of malignant cells during metastasis.

  20. On the molecular interaction between albumin and ibuprofen: An AFM and QCM-D study.

    PubMed

    Eleta-Lopez, Aitziber; Etxebarria, Juan; Reichardt, Niels-Christian; Georgieva, Radostina; Bäumler, Hans; Toca-Herrera, José L

    2015-10-01

    The adsorption of proteins on surfaces often results in a change of their structural behavior and consequently, a loss of bioactivity. One experimental method to study interactions on a molecular level is single molecular force spectroscopy that permits to measure forces down to the pico-newton range. In this work, the binding force between human serum albumin (HSA), covalently immobilized on glutaraldehyde modified gold substrates, and ibuprofen sodium salt was studied by means of single molecular force spectroscopy. First of all, a protocol was established to functionalize atomic force microscopy (AFM) tips with ibuprofen. The immobilization protocol was additionally tested by quartz crystal microbalance with dissipation (QCM-D) and contact angle measurements. AFM was used to characterize the adsorption of HSA on gold substrates, which lead to a packed monolayer of thickness slightly lower than the reported value in solution. Finally, single molecule spectroscopy results were used to characterize the binding force between albumin and ibuprofen and calculate the distance of the transition state (0.6 nm) and the dissociation rate constant (0.055 s(-1)). The results might indicate that part of the adsorbed protein still preserves its functionality upon adsorption. PMID:26218522

  1. Conductance of AFM Deformed Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anatram, M. P.; Biegel, Bryan (Technical Monitor)

    2002-01-01

    This viewgraph presentation provides information on the electrical conductivity of carbon nanotubes upon deformation by atomic force microscopy (AFM). The density of states and conductance were computed using four orbital tight-binding method with various parameterizations. Different chiralities develop bandgap that varies with chirality.

  2. Contact nanomechanical measurements with the AFM

    NASA Astrophysics Data System (ADS)

    Geisse, Nicholas

    2013-03-01

    The atomic force microscope (AFM) has found broad use in the biological sciences largely due to its ability to make measurements on unfixed and unstained samples under liquid. In addition to imaging at multiple spatial scales ranging from micro- to nanometer, AFMs are commonly used as nanomechanical probes. This is pertinent for cell biology, as it has been demonstrated that the geometrical and mechanical properties of the extracellular microenvironment are important in such processes as cancer, cardiovascular disease, muscular dystrophy, and even the control of cell life and death. Indeed, the ability to control and quantify these external geometrical and mechanical parameters arises as a key issue in the field. Because AFM can quantitatively measure the mechanical properties of various biological samples, novel insights to cell function and to cell-substrate interactions are now possible. As the application of AFM to these types of problems is widened, it is important to understand the performance envelope of the technique and its associated data analyses. This talk will discuss the important issues that must be considered when mechanical models are applied to real-world data. Examples of the effect of different model assumptions on our understanding of the measured material properties will be shown. Furthermore, specific examples of the importance of mechanical stimuli and the micromechanical environment to the structure and function of biological materials will be presented.

  3. AFM study of polymer lubricants on hard disk surfaces

    NASA Astrophysics Data System (ADS)

    Bao, G. W.; Troemel, M.; Li, S. F. Y.

    Thin liquid films of PFPE (perfluoropolyether) lubricants dip-coated on hard disk surfaces were imaged with non-contact mode AFM. Demnum lubricants with phosphazene additives exhibited strong interactions with a silicon tip due to the formation of liquid bridges between the lubricants and the tip, as indicated by a remarkable hysteresis loop between approach and retraction curves in force vs. distance measurements. Features resulting from capillary forces due to tip tapping to the lubricants were revealed, which demonstrated that the capillary forces could be used to lock the non-contacting tip at a certain separation from the substrate surface to obtain AFM images. Force vs. distance curves for Fomblin Z-dol lubricants showed negligible hysteresis effects and features corresponding to lateral distortion of the tip by the lubricants only were observed. In both cases, only when the tip was positioned far above the surfaces could the natural distributions of the lubricants be imaged.

  4. Investigation of the Mechanoelectrical Transduction at Single Stereocilia by Afm

    NASA Astrophysics Data System (ADS)

    Langer, M. G.; Fink, S.; Löffler, K.; Koitschev, A.; Zenner, H.-P.

    2003-02-01

    The transduction of sound into an electrical signal in the inner ear is closely related to the mechanical properties of the hair bundles cytoskeleton and cross-linkage. In this study the effect of lateral cross-links on hair bundle mechanics and the transduction current response is demonstrated on the level of individual stereocilia. For experiments stereocilia of outer hair cells of postnatal rats (P3 - P8) were scanned with a sharp AFM tip at nanometerscale. Transduction currents were simultaneously recorded in the whole-cell-recording mode with patch clamp. AFM was used as a nanotool for local mechanical stimulation and force measurement at stereocilia whereas patch clamp serves as a detector for the electrical response of the cell. In a first experiment force transmission between adjacent stereocilia of the V- and W- shaped hair bundles of outer hair cells was investigated. Results showed that a force exerted to a single stereocilium declined to 36 % at the nearest adjacent stereocilium of the same row. This result supposes AFM to be convenient for local displacement of single stereocilia. For control, the local response of transduction channels was measured at single stereocilia of the same hair bundle. Measured transduction current amplitudes ranged from 9 to 49 pA supposing an opening of one to five transduction channels. Both, weak force transmission by lateral cross-links and small transduction current amplitudes indicate a weak mechanical interaction between individual stereocilia of the tallest row of stereocilia of outer hair cells from postnatal rats.

  5. AFM nanoscale indentation in air of polymeric and hybrid materials with highly different stiffness

    NASA Astrophysics Data System (ADS)

    Suriano, Raffaella; Credi, Caterina; Levi, Marinella; Turri, Stefano

    2014-08-01

    In this study, nanomechanical properties of a variety of polymeric materials was investigated by means of AFM. In particular, selecting different AFM probes, poly(methyl methacrylate) (PMMA), polydimethylsiloxane (PDMS) bulk samples, sol-gel hybrid thin films and hydrated hyaluronic acid hydrogels were indented in air to determine the elastic modulus. The force-distance curves and the indentation data were found to be greatly affected by the cantilever stiffness and by tip geometry. AFM indentation tests show that the choice of the cantilever spring constant and of tip shape is crucially influenced by elastic properties of samples. When adhesion-dominated interactions occur between the tip and the surface of samples, force-displacement curves reveal that a suitable functionalization of AFM probes allows the control of such interactions and the extraction of Young' modulus from AFM curves that would be otherwise unfeasible. By applying different mathematical models depending on AFM probes and materials under investigation, the values of Young's modulus were obtained and compared to those measured by rheological and dynamic mechanical analysis or to literature data. Our results show that a wide range of elastic moduli (10 kPa-10 GPa) can be determined by AFM in good agreement with those measured by conventional macroscopic measurements.

  6. Insight into mechanics of AFM tip-based nanomachining: bending of cantilevers and machined grooves.

    PubMed

    Al-Musawi, R S J; Brousseau, E B; Geng, Y; Borodich, F M

    2016-09-23

    Atomic force microscope (AFM) tip-based nanomachining is currently the object of intense research investigations. Values of the load applied to the tip at the free end of the AFM cantilever probe used for nanomachining are always large enough to induce plastic deformation on the specimen surface contrary to the small load values used for the conventional contact mode AFM imaging. This study describes an important phenomenon specific for AFM nanomachining in the forward direction: under certain processing conditions, the deformed shape of the cantilever probe may change from a convex to a concave orientation. The phenomenon can principally change the depth and width of grooves machined, e.g. the grooves machined on a single crystal copper specimen may increase by 50% on average following such a change in the deformed shape of the cantilever. It is argued that this phenomenon can take place even when the AFM-based tool is operated in the so-called force-controlled mode. The study involves the refined theoretical analysis of cantilever probe bending, the analysis of experimental signals monitored during the backward and forward AFM tip-based machining and the inspection of the topography of produced grooves. PMID:27532247

  7. Quantitative nano-mechanics of biological cells with AFM

    NASA Astrophysics Data System (ADS)

    Sokolov, Igor

    2013-03-01

    The importance of study of living cells is hard to overestimate. Cell mechanics is a relatively young, yet not a well-developed area. Besides just a fundamental interest, large practical need has emerged to measure cell mechanics quantitatively. Recent studies revealed a significant correlation between stiffness of biological cells and various human diseases, such as cancer, malaria, arthritis, and even aging. However, really quantitative studies of mechanics of biological cells are virtually absent. It is not even clear if the cell, being a complex and heterogeneous object, can be described by the elastic modulus at all. Atomic force microscopy (AFM) is a natural instrument to study properties of cells in their native environments. Here we will demonstrate that quantitative measurements of elastic modulus of cells with AFM are possible. Specifically, we will show that the ``cell body'' (cell without ``brush'' surface layer, a non-elastic layer surrounding cells) typically demonstrates the response of a homogeneous elastic medium up to the deformation of 10-20%, but if and only if a) the cellular brush layer is taken into account, b) rather dull AFM probes are used. This will be justified with the help of the strong condition of elastic behavior of material: the elastic modulus is shown to be independent on the indentation depth. We will also demonstrate that an attempt either to ignore the brush layer or to use sharp AFM probes will result in the violation of the strong condition, which implies impossibility to use the concept of the elastic modulus to describe cell mechanics in such experiments. Examples of quantitative measurements of the Young's modulus of the cell body and the cell brush parameters will be given for various cells. Address when submitting: Clarkson University, Potsdam, NY 13699

  8. Near-Field Spectroscopy with Nanoparticles Deposited by AFM

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S.

    2008-01-01

    An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

  9. Using XAFS, EDAX and AFM in comparative study of various natural and synthetic emeralds

    NASA Astrophysics Data System (ADS)

    Parikh, P.; Saini, N. L.; Dalela, S.; Bhardwaj, D. M.; Fernandes, S.; Gupta, R. P.; Garg, K. B.

    2003-01-01

    We have performed XAFS, EDAX and AFM studies on some natural and synthetic emeralds. While the XAFS results yield information on changes in the valence of the Cr ion and the n-n distance the AFM is used to determine the areal atomic density on surface of the crystals. It is a pilot study to explore if the three techniques can offer a possible way of distinguishing between the natural and synthetic emeralds and the results are promising.

  10. Inter-species extrapolation of skin heating resulting from millimeter wave irradiation: modeling and experimental results.

    PubMed

    Nelson, D A; Walters, T J; Ryan, K L; Emerton, K B; Hurt, W D; Ziriax, J M; Johnson, L R; Mason, P A

    2003-05-01

    This study reports measurements of the skin surface temperature elevations during localized irradiation (94 GHz) of three species: rat (irradiated on lower abdomen), rhesus monkey (posterior forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high power density microwaves (HPM). Temperature histories were compared with calculations from a bio-heat transfer model. The mean peak surface temperature increase was approximately 7.0 degrees C for the short-term HPM exposures for all three species/locations, and 8.5 degrees C (monkey, human) to 10.5 degrees C (rat) for the longer-duration LPM exposures. The HPM temperature histories are in close agreement with a one-dimensional conduction heat transfer model with negligible blood flow. The LPM temperature histories were compared with calculations from the bio-heat model, evaluated for various (constant) blood flow rates. Results suggest a variable blood flow model, reflecting a dynamic thermoregulatory response, may be more suited to describing skin surface temperature response under long-duration MMW irradiation. PMID:12747480

  11. AFM Studies on Liquid Superlubricity between Silica Surfaces Achieved with Surfactant Micelles.

    PubMed

    Li, Jinjin; Zhang, Chenhui; Cheng, Peng; Chen, Xinchun; Wang, Weiqi; Luo, Jianbin

    2016-06-01

    By using atomic force microscopy (AFM), we showed that the liquid superlubricity with a superlow friction coefficient of 0.0007 can be achieved between two silica surfaces lubricated by hexadecyltrimethylammonium bromide (C16TAB) solution. There exists a critical load that the lubrication state translates from superlow friction to high friction reversibly. To analyze the superlow friction mechanism and the factors influencing the critical load, we used AFM to measure the structure of adsorbed C16TAB molecules and the normal force between two silica surfaces. Experimental results indicate that the C16TAB molecules are firmly adsorbed on the two silica surfaces by electrostatic interaction, forming cylinder-like micelles. Meanwhile, the positively charged headgroups exposed to solution produce the hydration and double layer repulsion to bear the applied load. By controlling the concentration of C16TAB solution, it is confirmed that the critical load of superlow friction is determined by the maximal normal force produced by the hydration layer. Finally, the superlow friction mechanism was proposed that the adsorbed micellar layer forms the hydration layer, making the two friction surfaces be in the repulsive region and meanwhile providing excellent fluidity without adhesion between micelles. PMID:27192019

  12. Review and perspectives of AFM application on the study of deformable drop/bubble interactions.

    PubMed

    Wang, Wei; Li, Kai; Ma, Mengyu; Jin, Hang; Angeli, Panagiota; Gong, Jing

    2015-11-01

    The applications of Atomic Force Microscopy (AFM) on the study of dynamic interactions and film drainage between deformable bodies dispersed in aqueous solutions are reviewed in this article. Novel experimental designs and recent advances in experimental methodologies are presented, which show the advantage of using AFM as a tool for probing colloidal interactions. The effects of both DLVO and non-DLVO forces on the colloid stabilization mechanism are discussed. Good agreement is found between the force - drop/bubble deformation behaviour revealed by AFM measurements and the theoretical modeling of film drainage process, giving a convincing explanation of the occurrence of certain phenomenon. However, the behaviour and shape of deformable drops as they approach or retract is still not well resolved. In addition, when surfactants are present further research is needed on the absorption of surfactant molecules into the interfaces, their mobility and the effects on interfacial film properties. PMID:26344865

  13. Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM.

    PubMed

    Avdic, A; Lugstein, A; Wu, M; Gollas, B; Pobelov, I; Wandlowski, T; Leonhardt, K; Denuault, G; Bertagnolli, E

    2011-04-01

    We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes. PMID:21368355

  14. Fabrication of cone-shaped boron doped diamond and gold nanoelectrodes for AFM-SECM

    NASA Astrophysics Data System (ADS)

    Avdic, A.; Lugstein, A.; Wu, M.; Gollas, B.; Pobelov, I.; Wandlowski, T.; Leonhardt, K.; Denuault, G.; Bertagnolli, E.

    2011-04-01

    We demonstrate a reliable microfabrication process for a combined atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM) measurement tool. Integrated cone-shaped sensors with boron doped diamond (BDD) or gold (Au) electrodes were fabricated from commercially available AFM probes. The sensor formation process is based on mature semiconductor processing techniques, including focused ion beam (FIB) machining, and highly selective reactive ion etching (RIE). The fabrication approach preserves the geometry of the original AFM tips resulting in well reproducible nanoscaled sensors. The feasibility and functionality of the fully featured tips are demonstrated by cyclic voltammetry, showing good agreement between the measured and calculated currents of the cone-shaped AFM-SECM electrodes.

  15. Diamond-modified AFM probes: from diamond nanowires to atomic force microscopy-integrated boron-doped diamond electrodes.

    PubMed

    Smirnov, Waldemar; Kriele, Armin; Hoffmann, René; Sillero, Eugenio; Hees, Jakob; Williams, Oliver A; Yang, Nianjun; Kranz, Christine; Nebel, Christoph E

    2011-06-15

    In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are

  16. The Advancing State of AF-M315E Technology

    NASA Technical Reports Server (NTRS)

    Masse, Robert; Spores, Ronald A.; McLean, Chris

    2014-01-01

    The culmination of twenty years of applied research in hydroxyl ammonium nitrate (HAN)-based monopropellants, the NASA Space Technology mission Directorate's (STMD) Green Propellant Infusion Mission (GPIM) will achieve the first on-orbit demonstration of an operational AF-M315E green propellant propulsion system by the end of 2015. Following an contextual overview of the completed flight design of the GPIM propellant storage and feed system, results of first operation of a flight-representative heavyweight 20-N engineering model thruster (to be conducted in mid-2014) are presented with performance comparisons to prior lab model (heavyweight) test articles.

  17. Results from experimental investigations of the performance of air condensers for steam turbine units

    NASA Astrophysics Data System (ADS)

    Fedorov, V. A.; Mil'man, O. O.; Kolesnikov, N. V.; Anan'ev, P. A.; Dunaev, S. N.; Mikhal'kov, A. M.; Mosin, A. V.; Kondrat'ev, A. V.

    2013-02-01

    Results from experimental investigations of the model versions of Type ABC GI air condensers are presented, and it is shown that these condensers have better performance characteristics as compared with their analogs that are currently in operation.

  18. BOREAS AFM-6 Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) collected surface meteorological data from 21 May to 20 Sep 1994 near the Southern Study Area-Old Jack Pine (SSA-OJP) tower site. The data are in tabular ASCII files. The surface meteorological data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  19. Characterization of single 1.8-nm Au nanoparticle attachments on AFM tips for single sub-4-nm object pickup

    PubMed Central

    2013-01-01

    This paper presents a novel method for the attachment of a 1.8-nm Au nanoparticle (Au-NP) to the tip of an atomic force microscopy (AFM) probe through the application of a current-limited bias voltage. The resulting probe is capable of picking up individual objects at the sub-4-nm scale. We also discuss the mechanisms involved in the attachment of the Au-NP to the very apex of an AFM probe tip. The Au-NP-modified AFM tips were used to pick up individual 4-nm quantum dots (QDs) using a chemically functionalized method. Single QD blinking was reduced considerably on the Au-NP-modified AFM tip. The resulting AFM tips present an excellent platform for the manipulation of single protein molecules in the study of single protein-protein interactions. PMID:24237663

  20. Sub-surface imaging of carbon nanotube-polymer composites using dynamic AFM methods.

    PubMed

    Cadena, Maria J; Misiego, Rocio; Smith, Kyle C; Avila, Alba; Pipes, Byron; Reifenberger, Ron; Raman, Arvind

    2013-04-01

    High-resolution sub-surface imaging of carbon nanotube (CNT) networks within polymer nanocomposites is demonstrated through electrical characterization techniques based on dynamic atomic force microscopy (AFM). We compare three techniques implemented in the single-pass configuration: DC-biased amplitude modulated AFM (AM-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) in terms of the physics of sub-surface image formation and experimental robustness. The methods were applied to study the dispersion of sub-surface networks of single-walled nanotubes (SWNTs) in a polyimide (PI) matrix. We conclude that among these methods, the KPFM channel, which measures the capacitance gradient (∂C/∂d) at the second harmonic of electrical excitation, is the best channel to obtain high-contrast images of the CNT network embedded in the polymer matrix, without the influence of surface conditions. Additionally, we propose an analysis of the ∂C/∂d images as a tool to characterize the dispersion and connectivity of the CNTs. Through the analysis we demonstrate that these AFM-based sub-surface methods probe sufficiently deep within the SWNT composites, to resolve clustered networks that likely play a role in conductivity percolation. This opens up the possibility of dynamic AFM-based characterization of sub-surface dispersion and connectivity in nanostructured composites, two critical parameters for nanocomposite applications in sensors and energy storage devices. PMID:23478510

  1. Development of a new generation of active AFM tools for applications in liquids

    NASA Astrophysics Data System (ADS)

    Rollier, A.-S.; Jenkins, D.; Dogheche, E.; Legrand, B.; Faucher, M.; Buchaillot, L.

    2010-08-01

    Atomic force microscopy (AFM) is a powerful imaging tool with high-resolution imaging capability. AFM probes consist of a very sharp tip at the end of a silicon cantilever that can respond to surface artefacts to produce an image of the topography or surface features. They are intrinsically passive devices. For imaging soft biological samples, and also for samples in liquid, it is essential to control the AFM tip position, both statically and dynamically, and this is not possible using external actuators mounted on the AFM chip. AFM cantilevers have been fabricated using silicon micromachining to incorporate a piezoelectric thin film actuator for precise control. The piezoelectric thin films have been fully characterized to determine their actuation performance and to characterize the operation of the integrated device. Examples of the spatial and vertical response are presented to illustrate their imaging capability. For operation in a liquid environment, the dynamic behaviour has been modelled and verified experimentally. The optimal drive conditions for the cantilever, along with their dynamic response, including frequency and phase in air and water, are presented.

  2. Effect of AFM probe geometry on visco-hyperelastic characterization of soft materials.

    PubMed

    Boccaccio, Antonio; Lamberti, Luciano; Papi, Massimiliano; De Spirito, Marco; Pappalettere, Carmine

    2015-08-14

    Atomic force microscopy (AFM) nanoindentation is very suited for nano- and microscale mechanical characterization of soft materials. Although the structural response of polymeric networks that form soft matter depends on viscous effects caused by the relative slippage of polymeric chains, the usual assumption made in the AFM-based characterization is that the specimen behaves as a purely elastic material and viscous forces are negligible. However, for each geometric configuration of the AFM tip, there will be a limit indentation rate above which viscous effects must be taken into account to correctly determine mechanical properties. A parametric finite element study conducted on 12 geometric configurations of a blunt cone AFM tip (overall, the study included about 200 finite element analyses) allowed us to determine the limit indentation rate for each configuration. The selected tip dimensions cover commercially available products and account for changes in tip geometry caused by serial measurements. Nanoindentation rates cover typical experimental conditions set in AFM bio-measurements on soft matter. Viscous effects appear to be more significant in the case of sharper tips. This implies that, if quantitative data on sample viscosity are not available, using a rounded indenter and carrying out experiments below the limit indentation rate will allow errors in the determination of mechanical properties to be minimized. PMID:26201503

  3. Multiparametric high-resolution imaging of native proteins by force-distance curve-based AFM.

    PubMed

    Pfreundschuh, Moritz; Martinez-Martin, David; Mulvihill, Estefania; Wegmann, Susanne; Muller, Daniel J

    2014-05-01

    A current challenge in the life sciences is to understand how the properties of individual molecular machines adjust in order to meet the functional requirements of the cell. Recent developments in force-distance (FD) curve-based atomic force microscopy (FD-based AFM) enable researchers to combine sub-nanometer imaging with quantitative mapping of physical, chemical and biological properties. Here we present a protocol to apply FD-based AFM to the multiparametric imaging of native proteins under physiological conditions. We describe procedures for experimental FD-based AFM setup, high-resolution imaging of proteins in the native unperturbed state with simultaneous quantitative mapping of multiple parameters, and data interpretation and analysis. The protocol, which can be completed in 1-3 d, enables researchers to image proteins and protein complexes in the native unperturbed state and to simultaneously map their biophysical and biochemical properties at sub-nanometer resolution. PMID:24743419

  4. An approach towards 3D sensitive AFM cantilevers

    NASA Astrophysics Data System (ADS)

    Koops, Richard; Fokkema, Vincent

    2014-04-01

    The atomic force microscope (AFM) tapping mode is a highly sensitive local probing technique that is very useful to study and measure surface properties down to the atomic scale. The tapping mode is mostly implemented using the resonance of the first bending mode of the cantilever and therefore provides sensitivity mainly along the direction of this oscillation. Driven by the semiconductor industry, there is an increasing need for accurate measurements of nanoscale structures for side wall characterization by AFM that requires additional sensitivity in the lateral direction. The conventional tapping mode has been augmented by various authors, for example by tilting the cantilever system (Cho et al 2011 Rev. Sci. Instrum. 82 023707) to access the sidewall or using a torsion mode (Dai et al 2011 Meas. Sci. Technol. 22 094009) of the cantilever to provide additional lateral sensitivity. These approaches however trade lateral sensitivity for vertical sensitivity or still lack sensitivity in the remaining lateral direction. We present an approach towards true 3D sensitivity for AFM cantilevers based on simultaneous excitation and optical detection of multiple cantilever resonance modes along three axes. Tuning the excitation of the cantilever to specific frequencies provides a mechanism to select only those cantilever modes that have the desired characteristics. Additionally, cantilever engineering has been used to design and create a substructure within the cantilever that has been optimized for specific resonance behavior around 4 MHz. In contrast to the conventional approach of using a piezo to actuate the cantilever modulation, we present results on photo-thermal excitation using an intensity modulated low-power laser source. By tightly focusing the excitation spot on the cantilever we were able to attain a deflection efficiency of 0.7 nm µW-1 for the first bending mode. The presented approach results in an efficient all optical excitation and deflection detection

  5. FM-AFM crossover in vanadium oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Demishev, S. V.; Chernobrovkin, A. L.; Glushkov, V. V.; Grigorieva, A. V.; Goodilin, E. A.; Sluchanko, N. E.; Samarin, N. A.; Semeno, A. V.

    2010-01-01

    The magnetic properties of nanomaterials based on vanadium oxide (multiwall nanotubes, nanorods, and nanolayers) have been investigated in the temperature range of 1.8-220 K by high-frequency (60-GHz) EPR. A transition from a ferromagnetic temperature dependence to an antiferromagnetic temperature dependence has been observed in nanorods and nanotubes with a decrease in the temperature. The FM-AFM crossover observed near T C ˜ 110 K is accompanied by a low-temperature increase in the Curie constant by a factor of 2.7-7. The comparison of the experimental data for various VO x nanoparticles indicates that the most probable cause of the change in the type of magnetic interaction is a change in the concentration of V4+ magnetic ions.

  6. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1993-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field has been conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a backswept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and in several cases provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  7. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1994-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field was conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a back-swept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and, in several cases, provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  8. Experimental study of tilting-pad journal bearings - Comparison with theoretical thermoelastohydrodynamic results

    NASA Astrophysics Data System (ADS)

    Fillon, Michel; Bligoud, Jean-Claude; Frene, Jean

    1992-07-01

    Operating characteristics of four-shoe tilting-pad journal bearings of 100 mm diameter and 70 mm length are determined on an experimental device. The load, between pad configuration, varies from 0 to 10,000 N and the rotational speed is up to 4000 rpm. Forty thermocouples are used in order to measure bearing element temperatures (babbitt, shaft, housing and oil baths). The influence of operating conditions and preload ratio on bearing performances are studied. Comparison between theoretical and experimental results is presented. The theoretical model is also performed on a large tilting-pad journal bearing which was investigated experimentally by other authors.

  9. Optical scattering by biological aerosols: experimental and computational results on spore simulants

    NASA Astrophysics Data System (ADS)

    Sindoni, Orazio I.; Saija, Rosalba; Iatì, Maria Antonia; Borghese, Ferdinando; Denti, Paolo; Fernandes, Gustavo E.; Pan, Yong-Le; Chang, Richard K.

    2006-07-01

    We present both a computational and an experimental approach to the problem of biological aerosol characterization, joining the expertises reached in the field of theoretical optical scattering by complex, arbitrary shaped particles (multipole expansion of the electromagnetic fields and Transition Matrix), and a novel experimental technique based on two-dimensional angular optical scattering (TAOS). The good agreement between experimental and computational results, together with the possibility for a laboratory single-particle angle-resolved investigation, opens a new scenario in biological particle modelling, and might have major implications for a rapid discrimination of airborne particles.

  10. Experimental results on p (d) + A collisions at RHIC and the LHC

    NASA Astrophysics Data System (ADS)

    Sickles, Anne M.

    2014-11-01

    Recent experimental results at both the LHC and RHIC show evidence for hydrodynamic behavior in proton-nucleus and deuteron-nucleus collisions (p + A). This unexpected finding has prompted new measurements in p + A collisions in order to understand whether matter with similar properties is created in A + A and p + A collisions or whether another explanation is needed. In this proceedings, we will discuss the new experimental data and its interpretation within the context of heavy-ion collisions.

  11. Performance analysis of wick-assisted heat pipe solar collector and comparison with experimental results

    NASA Astrophysics Data System (ADS)

    Azad, E.

    2009-03-01

    The performance of heat pipe solar collector is investigated theoretically and experimentally. The system employs wick-assisted heat pipe for the heat transfer from the absorber (evaporator) to a heat exchanger (condenser). The heat pipe is made with a copper tube and the evaporator section is finned with aluminium plate. Theoretical model predicts the outlet water from heat exchanger, heat pipe temperature and also the thermal efficiency of solar collector. The results are compared with experimental data.

  12. Strength by atomic force microscopy (AFM): Molecular dynamics of water layer squeezing on magnesium oxide

    NASA Astrophysics Data System (ADS)

    Kendall, K.; Dhir, Aman; Yong, Chin W.

    2010-11-01

    Localised strength testing of materials is often carried out in an atomic force microscope (AFM), as foreseen by Kelly in his book Strong Solids (Clarendon Press, Oxford, 1966). During AFM indentation experiments, contamination can strongly influence the observed strength and theoretical interpretation of the results is a major problem. Here, we use molecular dynamics computer modelling to describe the contact of NaCl and MgO crystal probes onto surfaces, comparable to an AFM experiment. Clean NaCl gave elastic, brittle behaviour in contact simulations at 300 K, whereas MgO was more plastic, leading to increased toughness. This paper also considers the strength of an oxide substrate contaminated by water molecules and tested by indentation with a pyramidal probe of oxide crystal. Recent theory on the effect of liquid contaminant layers on surface strength has been mainly focussed on Lennard Jones (LJ) molecules with some studies on alcohols and water, described by molecular dynamics, which allows the molecules to be squeezed out as the crystal lattice is deformed. In this work, we have focused on water by studying the forces between a magnesium oxide (MgO) atomic force microscope (AFM) probe and an MgO slab. Force versus separation has been plotted as the AFM probe was moved towards and away from the substrate. Simulation results showed that the water layers could be removed in steps, giving up to four force peaks. The last monolayer of water could not be squeezed out, even at pressures where MgO deformed plastically. Interestingly, with water present, strength was reduced, but more in tensile than compressive measurements. In conclusion, water contaminating the oxide surface in AFM strength testing is structured. Water layer squeezing removal can be predicted by molecular modelling, which may be verified by AFM experiments to show that water can influence the strength of perfect crystals at the nanometre scale.

  13. Numerical simulation and experimental results of ultrasonic waves scattering on a model of the artery

    NASA Astrophysics Data System (ADS)

    Wojcik, J.; Powalowski, T.; Trawinski, Z.

    2008-02-01

    The aim of this paper is to compare the results of the mathematical modeling and experimental results of the ultrasonic waves scattering in the inhomogeneous dissipative medium. The research was carried out for an artery model (a pipe made of a latex), with internal diameter of 5 mm and wall thickness of 1.25 mm. The numerical solver was created for calculation of the fields of ultrasonic beams and scattered fields under different boundary conditions, different angles and transversal displacement of ultrasonic beams with respect to the position of the arterial wall. The investigations employed the VED ultrasonic apparatus. The good agreement between the numerical calculation and experimental results was obtained.

  14. Experimental results of a load management system for large commercial customers

    SciTech Connect

    Johnson, W.A.; Devaney, T.M.; Maher, A.M.

    1985-09-01

    Encouraging experimental results have been obtained from a two-way load management system for large commercial as well as governmental customers on the Potomac Electric Power Company (PEPCo) system. This paper presents these results and describes the inovative twoway load management system that was developed and installed to achieve them. The Robinton Products, Inc. system operates from a central processor located in PEPCO's control center and it communicates with the customer locations through a telephone system called ''Select-A-Station''. Future plans for the expansion of the system are presented along with experimental results.

  15. Charge injection in thin dielectric layers by atomic force microscopy: influence of geometry and material work function of the AFM tip on the injection process

    NASA Astrophysics Data System (ADS)

    Villeneuve-Faure, C.; Makasheva, K.; Boudou, L.; Teyssedre, G.

    2016-06-01

    Charge injection and retention in thin dielectric layers remain critical issues for the reliability of many electronic devices because of their association with a large number of failure mechanisms. To overcome this drawback, a deep understanding of the mechanisms leading to charge injection close to the injection area is needed. Even though the charge injection is extensively studied and reported in the literature to characterize the charge storage capability of dielectric materials, questions about charge injection mechanisms when using atomic force microscopy (AFM) remain open. In this paper, a thorough study of charge injection by using AFM in thin plasma-processed amorphous silicon oxynitride layers with properties close to that of thermal silica layers is presented. The study considers the impact of applied voltage polarity, work function of the AFM tip coating and tip curvature radius. A simple theoretical model was developed and used to analyze the obtained experimental results. The electric field distribution is computed as a function of tip geometry. The obtained experimental results highlight that after injection in the dielectric layer the charge lateral spreading is mainly controlled by the radial electric field component independently of the carrier polarity. The injected charge density is influenced by the nature of electrode metal coating (work function) and its geometry (tip curvature radius). The electron injection is mainly ruled by the Schottky injection barrier through the field electron emission mechanism enhanced by thermionic electron emission. The hole injection mechanism seems to differ from the electron one depending on the work function of the metal coating. Based on the performed analysis, it is suggested that for hole injection by AFM, pinning of the metal Fermi level with the metal-induced gap states in the studied silicon oxynitride layers starts playing a role in the injection mechanisms.

  16. Charge injection in thin dielectric layers by atomic force microscopy: influence of geometry and material work function of the AFM tip on the injection process.

    PubMed

    Villeneuve-Faure, C; Makasheva, K; Boudou, L; Teyssedre, G

    2016-06-17

    Charge injection and retention in thin dielectric layers remain critical issues for the reliability of many electronic devices because of their association with a large number of failure mechanisms. To overcome this drawback, a deep understanding of the mechanisms leading to charge injection close to the injection area is needed. Even though the charge injection is extensively studied and reported in the literature to characterize the charge storage capability of dielectric materials, questions about charge injection mechanisms when using atomic force microscopy (AFM) remain open. In this paper, a thorough study of charge injection by using AFM in thin plasma-processed amorphous silicon oxynitride layers with properties close to that of thermal silica layers is presented. The study considers the impact of applied voltage polarity, work function of the AFM tip coating and tip curvature radius. A simple theoretical model was developed and used to analyze the obtained experimental results. The electric field distribution is computed as a function of tip geometry. The obtained experimental results highlight that after injection in the dielectric layer the charge lateral spreading is mainly controlled by the radial electric field component independently of the carrier polarity. The injected charge density is influenced by the nature of electrode metal coating (work function) and its geometry (tip curvature radius). The electron injection is mainly ruled by the Schottky injection barrier through the field electron emission mechanism enhanced by thermionic electron emission. The hole injection mechanism seems to differ from the electron one depending on the work function of the metal coating. Based on the performed analysis, it is suggested that for hole injection by AFM, pinning of the metal Fermi level with the metal-induced gap states in the studied silicon oxynitride layers starts playing a role in the injection mechanisms. PMID:27158768

  17. [AFM fishing of proteins under impulse electric field].

    PubMed

    Ivanov, Yu D; Pleshakova, T O; Malsagova, K A; Kaysheva, A L; Kopylov, A T; Izotov, A A; Tatur, V Yu; Vesnin, S G; Ivanova, N D; Ziborov, V S; Archakov, A I

    2016-05-01

    A combination of (atomic force microscopy)-based fishing (AFM-fishing) and mass spectrometry allows to capture protein molecules from solutions, concentrate and visualize them on an atomically flat surface of the AFM chip and identify by subsequent mass spectrometric analysis. In order to increase the AFM-fishing efficiency we have applied pulsed voltage with the rise time of the front of about 1 ns to the AFM chip. The AFM-chip was made using a conductive material, highly oriented pyrolytic graphite (HOPG). The increased efficiency of AFM-fishing has been demonstrated using detection of cytochrome b5 protein. Selection of the stimulating pulse with a rise time of 1 ns, corresponding to the GHz frequency range, by the effect of intrinsic emission from water observed in this frequency range during water injection into the cell. PMID:27562998

  18. Experimental Results with Airfoils Tested in the High-speed Tunnel at Guidonia

    NASA Technical Reports Server (NTRS)

    Ferri, Antonio

    1940-01-01

    The results are presented of a triple series of tests using force measurements, pressure-distribution measurements, and air flow photographs on airfoil sections suitably selected so that comparison could be made between the experimental and theoretical results. The comparison with existing theory is followed by a discussion of the divergences found, and an attempt is made to find their explanation.

  19. Novel tip shape reconstruction method for restoration of AFM topography images using nano-structures with given shapes.

    PubMed

    Onishi, Keiko; Fujita, Daisuke

    2011-01-01

    The establishment of more accurate imaging of surface microstructures is needed. The most significant distortion in atomic force microscopy (AFM) imaging is induced by the probe tip shape, whenever the sample surface contains features whose dimensions are comparable to the probe tip size. The acquired AFM image is the dilation between the tip shape and the sample topography. To restore the original topographical profile, a numerical erosion procedure using a precise probe shape function is required. Here, a new technique for reconstruction of probe shape function using a well-defined nanostructure is proposed. First, AFM topography images of the given-shape nanostructure dispersed on flat substrates are taken. Then, a probe shape function is determined by a numerical calculation procedure. By using the experimentally determined probe shape function, the most probable surface morphologies from the observed AFM topography images of unknown samples can be extracted. PMID:21321438

  20. Comparison of kinetic theory predictions with experimental results for a vibrated three-dimensional granular bed

    NASA Astrophysics Data System (ADS)

    Viswanathan, H.; Wildman, R. D.; Huntley, J. M.; Martin, T. W.

    2006-11-01

    The three-dimensional conservation equations relating energy and momentum transfer in a vibrated three-dimensional granular bed have been solved numerically by the finite element method. Two closures based on granular kinetic theory were used: one, the standard Fourier law relating heat flux to temperature gradient and the other, including an additional concentration gradient term. Each prediction of the two-dimensional axisymmetric granular temperature and packing fraction fields was compared against a one-dimensional model and three-dimensional experimental results, acquired using the technique of positron emission particle tracking. Both closures resulted in solutions that were in reasonable agreement with the experimental results, but it was found that differences between the predictions of each of the closures were relatively small in comparison to the anisotropy of the experimentally determined temperature distribution.

  1. BOREAS AFM-06 Mean Temperature Profile Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21 May 1994 to 20 Sep 1994. The data set provides temperature profiles at 15 heights, containing the variables of virtual temperature, vertical velocity, the speed of sound, and w-bar. The data are stored in tabular ASCII files. The mean temperature profile data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  2. BOREAS AFM-6 Boundary Layer Height Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) site. This data set provides boundary layer height information over the site. The data were collected from 21 May 1994 to 20 Sep 1994 and are stored in tabular ASCII files. The boundary layer height data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  3. BOREAS AFM-06 Mean Wind Profile Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from the National Oceanic and Atmospheric Administration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) tower from 21 May 1994 to 20 Sep 1994. The data set provides wind profiles at 38 heights, containing the variables of wind speed; wind direction; and the u-, v-, and w-components of the total wind. The data are stored in tabular ASCII files. The mean wind profile data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  4. Iron oxide mineral-water interface reactions studied by AFM

    SciTech Connect

    Hawley, M.E.; Rogers, P.S.Z.

    1994-07-01

    Natural iron mineral surfaces have been examined in air by atomic force (AFM) and scanning tunneling (STM) microscopies. A number of different surface features were found to be characteristic of the native surface. Even surfaces freshly exposed by crushing larger crystals were found to have a pebbly surface texture caused by the presence of thin coatings of what might be surface precipitates. This finding is interpreted as evidence for previous exposure to water, probably through an extensive network of microfractures. Surface reactions on the goethite crystals were studied by AFM at size resolutions ranging from microns to atomic resolution before, during, and after reaction with distilled water and 0.lN HCl. Immediate and extensive surface reconfiguration occurred on contact with water. In one case, after equilibration with water for 3 days, surface reprecipitation, etching and pitting were observed. Atomic resolution images taken under water were found to be disordered. The result of surface reaction was generally to increase the surface area substantially through the extension of surface platelet arrays, present prior to reaction. This work is being done in support of the site characterization project at Yucca Mountain.

  5. Comparison of particle sizes determined with impactor, AFM and SEM

    NASA Astrophysics Data System (ADS)

    Gwaze, Patience; Annegarn, Harold J.; Huth, Joachim; Helas, Günter

    2007-11-01

    Particles size comparisons were made between conventional aerodynamic and mobility sizing techniques and physical geometric sizes measured by high resolution microscopes. Atmospheric particles were collected during the wet and dry seasons in the Amazonian ecosystems. Individual particles deposited on four stages of the MOUDI (Micro-Orifice Uniform Deposition Impactor) were characterised for particle volumes, projected surface diameters and morphologies with an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). AFM and SEM size distributions were verified against distributions derived from response functions of individual MOUDI stages as specified by Winklmayr et al. [Winklmayr, W., Wang, H.-C., John, W., 1990. Adaptation of the Twomey algorithm to the inversion of cascade impactor data. Aerosol Science and Technology 13, 322-331.]. Particles indicated inherent discrepancies in sizing techniques. Particle volumes were systematically lower than expected by factors of up to 3.6. Differences were attributed to loss of mass, presumably water adsorbed on particles. Losses were high and could not be accounted for by measured humidity growth factors suggesting significant losses of other volatile compounds as well, particularly on particles that were collected during the wet season. Microscopy results showed that for hygroscopic particles, microscopy sizes depend on the relative humidity history of particles before and after sampling. Changes in relative humidity significantly altered particle morphologies. Depending on when changes occur, such losses will bias not only microscopy particle sizes but also impactor mass distributions and number concentrations derived from collected particles.

  6. AFM analysis of bleaching effects on dental enamel microtopography

    NASA Astrophysics Data System (ADS)

    Pedreira de Freitas, Ana Carolina; Espejo, Luciana Cardoso; Botta, Sergio Brossi; Teixeira, Fernanda de Sa; Luz, Maria Aparecida A. Cerqueira; Garone-Netto, Narciso; Matos, Adriana Bona; Salvadori, Maria Cecilia Barbosa da Silveira

    2010-02-01

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm × 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  7. Oscillatory structural forces due to nonionic surfactant micelles: data by colloidal-probe AFM vs theory.

    PubMed

    Christov, Nikolay C; Danov, Krassimir D; Zeng, Yan; Kralchevsky, Peter A; von Klitzing, Regine

    2010-01-19

    Micellar solutions of nonionic surfactants Brij 35 and Tween 20 are confined between two surfaces in a colloidal-probe atomic-force microscope (CP-AFM). The experimentally detected oscillatory forces due to the layer-by-layer expulsion of the micelles agree very well with the theoretical predictions for hard-sphere fluids. While the experiment gives parts of the stable branches of the force curve, the theoretical model allows reconstruction of the full oscillatory curve. Therewith, the strength and range of the ordering could be determined. The resulting aggregation number from the fits of the force curves for Brij 35 is close to 70 and exhibits a slight tendency to increase with the surfactant concentration. The last layer of micelles cannot be pressed out. The measured force-vs-distance curve has nonequilibrium portions, which represent "jumps" from one to another branch of the respective equilibrium oscillatory curve. In the case of Brij 35, at concentrations <150 mM spherical micelles are present and the oscillation period is close to the micelle diameter, slightly decreasing with the rise of concentration. For elongated micelles (at concentration 200 mM), no harmonic oscillations are observed anymore; instead, the period increases with the decrease of film thickness. In the case of Tween 20, the force oscillations are almost suppressed, which implies that the micelles of this surfactant are labile and are demolished by the hydrodynamic shear stresses due to the colloidal-probe motion. The comparison of the results for the two surfactants demonstrates that in some cases the micelles can be destroyed by the CP-AFM, but in other cases they can be stable and behave as rigid particles. This behavior correlates with the characteristic times of the slow micellar relaxation process for these surfactants. PMID:20067306

  8. Single-Molecule Studies of Integrins by AFM-Based Force Spectroscopy on Living Cells

    NASA Astrophysics Data System (ADS)

    Eibl, Robert H.

    The characterization of cell adhesion between two living cells at the single-molecule level, i.e., between one adhesion receptor and its counter-receptor, appears to be an experimental challenge. Atomic force microscopy (AFM) can be used in its force spectroscopy mode to determine unbinding forces of a single pair of adhesion receptors, even with a living cell as a probe. This chapter provides an overview of AFM force measurements of the integrin family of cell adhesion receptors and their ligands. A focus is given to major integrins expressed on leukocytes, such as lymphocyte function-associated antigen 1 (LFA-1) and very late antigen 4 (VLA-4). These receptors are crucial for leukocyte trafficking in health and disease. LFA-1 and VLA-1 can be activated within the bloodstream from a low-affinity to a high-affinity receptor by chemokines in order to adhere strongly to the vessel wall before the receptor-bearing leukocytes extravasate. The experimental considerations needed to provide near-physiological conditions for a living cell and to be able to measure adequate forces at the single-molecule level are discussed in detail. AFM technology has been developed into a modern and extremely sensitive tool in biomedical research. It appears now that AFM force spectroscopy could enter, within a few years, medical applications in diagnosis and therapy of cancer and autoimmune diseases.

  9. Three-dimensional convection in horizontal cylinders - Numerical solutions and comparison with experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Smutek, C.; Bontoux, P.; Roux, B.; Schiroky, G. H.; Hurford, A. C.

    1985-01-01

    The results of a three-dimensional numerical simulation of Boussinesq free convection in a horizontal differentially heated cylinder are presented. The computation was based on a Samarskii-Andreyev scheme (described by Leong, 1981) and a false-transient advancement in time, with vorticity, velocity, and temperature as dependent variables. Solutions for velocity and temperature distributions were obtained for Rayleigh numbers (based on the radius) Ra = 74-18,700, thus covering the core- and boundary-layer-driven regimes. Numerical solutions are compared with asymptotic analytical solutions and experimental data. The numerical results well represent the complex three-dimensional flows found experimentally.

  10. Preliminary Experimental Results on Controlled Cardiac Computed Tomography: A Phantom Study

    PubMed Central

    Lu, Yang; Cai, Zhijun; Wang, Ge; Zhao, Jun; Bai, Er-Wei

    2010-01-01

    In this paper, we present the preliminary experimental results on controlled cardiac computed tomography (CT), which aims to reduce the motion artifacts by means of controlling the x-ray source rotation speed. An innovative cardiac phantom enables us to perform this experiment without modifying the scanner. It is the first experiment on the cardiac CT with speed controlled x-ray source. Experimental results demonstrate that the proposed method successfully separates the phantom images at different phases (improve the temporal resolution) though controlling the x-ray speed. PMID:19696470

  11. Parametric Evaluation of Absorption Losses and Comparison of Numerical Results to Boeing 707 Aircraft Experimental HIRF Results

    NASA Astrophysics Data System (ADS)

    Kitaygorsky, J.; Amburgey, C.; Elliott, J. R.; Fisher, R.; Perala, R. A.

    A broadband (100 MHz-1.2 GHz) plane wave electric field source was used to evaluate electric field penetration inside a simplified Boeing 707 aircraft model with a finite-difference time-domain (FDTD) method using EMA3D. The role of absorption losses inside the simplified aircraft was investigated. It was found that, in this frequency range, none of the cavities inside the Boeing 707 model are truly reverberant when frequency stirring is applied, and a purely statistical electromagnetics approach cannot be used to predict or analyze the field penetration or shielding effectiveness (SE). Thus it was our goal to attempt to understand the nature of losses in such a quasi-statistical environment by adding various numbers of absorbing objects inside the simplified aircraft and evaluating the SE, decay-time constant τ, and quality factor Q. We then compare our numerical results with experimental results obtained by D. Mark Johnson et al. on a decommissioned Boeing 707 aircraft.

  12. Comparison of energy deposition calculations by the LAHET Code System with experimental results

    SciTech Connect

    Beard, C.A.; Lisowski, P.W.; Russell, G.J.; Waters, L.S.

    1993-08-01

    A comparison was performed between the energy deposition predicted by the LAHET Code System (LCS) with experimental values determined by Belyakov-Bodin et al. for 800, 1000, and 1200 MeV protons on targets composed of lead, bismuth, beryllium, carbon, and aluminum. The lead and bismuth showed agreement within approximately 10% at locations throughout the targets, and the agreement of the total energy deposited over the axial length of the targets ranged from 1% to 25%. For the lead and bismuth cases, the LCS predictions were always greater than the experimental results. For the lighter materials, the agreement at locations throughout the target only agreed within approximately 20%. No definable trend could be determined for the lighter materials since some LCS predictions were greater than the experimental results, some were less than the experimental results, and some showed very good agreement. The total energy deposited over the axial length of the targets was not compared for the lighter materials since it was not explicitly given with the experimental data.

  13. Effect of the molecular weight on deformation states of the polystyrene film by AFM single scanning.

    PubMed

    Sun, Yang; Yan, Yongda; Liang, Yingchun; Hu, Zhenjiang; Zhao, Xuesen; Sun, Tao; Dong, Shen

    2013-01-01

    Nanobundles patterns can be formed on the surface of most thermoplastic polymers when the atomic force microscope (AFM)-based nanomechanical machining method is employed to scratch their surfaces. Such patterns are reviewed as three-dimensional sine-wave structures. In the present study, the single-line scratch test is used firstly to study different removal states of the polystyrene (PS) polymer with different molecular weights (MWs). Effects of the scratching direction and the scratching velocity on deformation of the PS film and the state of the removed materials are also investigated. Single-wear box test is then employed to study the possibility of forming bundle structures on PS films with different MWs. The experimental results show that the state between the tip and the sample plays a key role in the nano machining process. If the contact radius between the AFM tip and the polymer surface is larger than the chain end-to-end distance, it is designated as the "cutting" state that means the area of both side ridges is less than the area of the groove and materials are removed. If the contact radius is less than the chain end-to-end distance, it is designated as the "plowing" state that means the area of both side ridges is larger than the area of the groove and no materials are removed at all. For the perfect bundles formation on the PS film, the plowing state is ideal condition for the larger MW polymers because of the chains' entanglement. PMID:23229843

  14. Photon Detection with Cooled Avalanche Photodiodes: Theory and Preliminary Experimental Results

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Hays, D. A.

    1985-01-01

    Avalanche photodiodes (APDs) can be operated in a geiger-tube mode so that they can respond to single electron events and thus be used as photon counting detectors. Operational characteristics and theory of APDs while used in this mode are analyzed and assessed. Preliminary experimental investigation of several commercially available APDs has commenced, and initial results for dark count statistics are presented.

  15. Solving System Of Linear Equations Using The Bimodal Optical Computer (Experimental Results)

    NASA Astrophysics Data System (ADS)

    Habli, M. A.; Abushagur, M. A. G.; Caulfield, H. J.

    1988-08-01

    Hardware and software design of the Bimodal Optical Computer (BOC) and its implementations are presented. Experimental results of the BOC for solving a system of linear equations Ax = b is reported. The effect of calibration, the convergence reliability of the BOC, and the convergence of problems with singular matrices are studied.

  16. An outcome-based learning model to identify emerging threats : experimental and simulation results.

    SciTech Connect

    Martinez-Moyano, I. J.; Conrad, S. H.; Andersen, D. F.; Decision and Information Sciences; SNL; Univ. at Albany

    2007-01-01

    The authors present experimental and simulation results of an outcome-based learning model as it applies to the identification of emerging threats. This model integrates judgment, decision making, and learning theories to provide an integrated framework for the behavioral study of emerging threats.

  17. At Odds: Reconciling Experimental and Theoretical Results in High School Physics

    ERIC Educational Resources Information Center

    Gates, Joshua

    2009-01-01

    For this experiment, students are divided into 2 groups and presented with a static equilibrium force-balance problem to solve. One group works entirely experimentally and the other group theoretically, using Newton's laws. The groups present their seemingly dissimilar results and must reconcile them through discussion. (Contains 3 figures.)

  18. AFM as an analysis tool for high-capacity sulfur cathodes for Li-S batteries.

    PubMed

    Hiesgen, Renate; Sörgel, Seniz; Costa, Rémi; Carlé, Linus; Galm, Ines; Cañas, Natalia; Pascucci, Brigitta; Friedrich, K Andreas

    2013-01-01

    In this work, material-sensitive atomic force microscopy (AFM) techniques were used to analyse the cathodes of lithium-sulfur batteries. A comparison of their nanoscale electrical, electrochemical, and morphological properties was performed with samples prepared by either suspension-spraying or doctor-blade coating with different binders. Morphological studies of the cathodes before and after the electrochemical tests were performed by using AFM and scanning electron microscopy (SEM). The cathodes that contained polyvinylidene fluoride (PVDF) and were prepared by spray-coating exhibited a superior stability of the morphology and the electric network associated with the capacity and cycling stability of these batteries. A reduction of the conductive area determined by conductive AFM was found to correlate to the battery capacity loss for all cathodes. X-ray diffraction (XRD) measurements of Li2S exposed to ambient air showed that insulating Li2S hydrolyses to insulating LiOH. This validates the significance of electrical ex-situ AFM analysis after cycling. Conductive tapping mode AFM indicated the existence of large carbon-coated sulfur particles. Based on the analytical findings, the first results of an optimized cathode showed a much improved discharge capacity of 800 mA·g(sulfur)(-1) after 43 cycles. PMID:24205455

  19. AFM as an analysis tool for high-capacity sulfur cathodes for Li–S batteries

    PubMed Central

    Sörgel, Seniz; Costa, Rémi; Carlé, Linus; Galm, Ines; Cañas, Natalia; Pascucci, Brigitta; Friedrich, K Andreas

    2013-01-01

    Summary In this work, material-sensitive atomic force microscopy (AFM) techniques were used to analyse the cathodes of lithium–sulfur batteries. A comparison of their nanoscale electrical, electrochemical, and morphological properties was performed with samples prepared by either suspension-spraying or doctor-blade coating with different binders. Morphological studies of the cathodes before and after the electrochemical tests were performed by using AFM and scanning electron microscopy (SEM). The cathodes that contained polyvinylidene fluoride (PVDF) and were prepared by spray-coating exhibited a superior stability of the morphology and the electric network associated with the capacity and cycling stability of these batteries. A reduction of the conductive area determined by conductive AFM was found to correlate to the battery capacity loss for all cathodes. X-ray diffraction (XRD) measurements of Li2S exposed to ambient air showed that insulating Li2S hydrolyses to insulating LiOH. This validates the significance of electrical ex-situ AFM analysis after cycling. Conductive tapping mode AFM indicated the existence of large carbon-coated sulfur particles. Based on the analytical findings, the first results of an optimized cathode showed a much improved discharge capacity of 800 mA·g(sulfur)−1 after 43 cycles. PMID:24205455

  20. Device level 3D characterization using PeakForce AFM

    NASA Astrophysics Data System (ADS)

    Timoney, Padraig; Zhang, Xiaoxiao; Vaid, Alok; Hand, Sean; Osborne, Jason; Milligan, Eric; Feinstein, Adam

    2016-03-01

    Traditional metrology solutions face a range of challenges at the 1X node such as three dimensional (3D) measurement capabilities, shrinking overlay and critical dimension (CD) error budgets driven by multi-patterning and via in trench CD measurements. With advent of advanced technology nodes and 3D processing, an increasing need is emerging for in-die metrology including across-structure and structure-to-structure characterization. A myriad of work has emerged in the past few years intending to address these challenges from various aspects; in-die OCD with reduced spot size and tilt beam on traditional critical dimension scanning electron microscopy (CDSEM) for height measurements. This paper explores the latest capability offered by PeakForceTM Tapping Atomic Force Microscopy (PFT-AFM). The use of traditional harmonic tapping mode for scanning high aspect ratio, and complex "3D" wafer structures, results in limited depth probing capability as well as excessive tip wear. These limitations arise due to the large tip-sample interaction volume in such confined spaces. PeakForce Tapping eliminates these limitations through direct real time control of the tip-sample interaction contact force. The ability of PeakForce to measure, and respond directly to tip- sample interaction forces results in more detailed feature resolution, reduced tip wear, and improved depth capability. In this work, the PFT-AFM tool was applied for multiple applications, including the 14nm fin and replacement metal gate (RMG) applications outlined below. Results from DOE wafers, detailed measurement precision studies and correlation to reference metrology are presented for validation of this methodology. With the fin application, precision of 0.3nm is demonstrated by measuring 5 dies with 10 consecutive runs. Capability to resolve within-die and localized within-macro height variation is also demonstrated. Results obtained from the fin measurements support the increasing trend that measurements

  1. Design and Experimental Results for a Natural-Laminar-Flow Airfoil for General Aviation Applications

    NASA Technical Reports Server (NTRS)

    Somers, D. M.

    1981-01-01

    A natural-laminar-flow airfoil for general aviation applications, the NLF(1)-0416, was designed and analyzed theoretically and verified experimentally in the Langley Low-Turbulence Pressure Tunnel. The basic objective of combining the high maximum lift of the NASA low-speed airfoils with the low cruise drag of the NACA 6-series airfoils was achieved. The safety requirement that the maximum lift coefficient not be significantly affected with transition fixed near the leading edge was also met. Comparisons of the theoretical and experimental results show excellent agreement. Comparisons with other airfoils, both laminar flow and turbulent flow, confirm the achievement of the basic objective.

  2. Non-destructive evaluation of metal-to-metal adhesive joints using vibration analysis: experimental results

    NASA Astrophysics Data System (ADS)

    Pandurangan, Pradeep; Buckner, Gregory D.

    2006-03-01

    Vibration based non-destructive evaluation shows promise for damage detection in metal-to-metal adhesive joints. This research investigates an experimental technique to diagnose damage in single-lap adhesive joints subject to cyclical tensile loading. Vibration analysis reveals that damage can be correlated with changes in identified modal damping ratios. Constant amplitude forcing functions are employed to eliminate amplitude-dependent nonlinearities in the dynamic response profiles. Damping estimates obtained from time-domain analyses correlate well with damage magnitudes. Finite element modal analysis of the lap joints supports the experimental results.

  3. Experimental results concerning global observables from the CERN SPS heavy ion program

    SciTech Connect

    Young, G.R.

    1990-06-01

    A brief overview is given of experimental results obtained during the initial operation of the heavy-ion program at the CERN SPS during the period 1986--1988. This paper confines itself to a presentation of results on so-called global observables, such as energy flow and multiplicity distributions, and on information extracted from them. Of particular interest among the latter are an estimate of the magnitude and spatial distribution of the energy density attained. 3 refs., 27 figs.

  4. Applying computational methods to interpret experimental results in tribology and enantioselective catalysis

    NASA Astrophysics Data System (ADS)

    Garvey, Michael T.

    Computational methods are rapidly becoming a mainstay in the field of chemistry. Advances in computational methods (both theory and implementation), increasing availability of computational resources and the advancement of parallel computing are some of the major forces driving this trend. It is now possible to perform density functional theory (DFT) calculations with chemical accuracy for model systems that can be interrogated experimentally. This allows computational methods to supplement or complement experimental methods. There are even cases where DFT calculations can give insight into processes and interactions that cannot be interrogated directly by current experimental methods. This work presents several examples of the application of computational methods to the interpretation and analysis of experimentally obtained results. First, triobological systems were investigated primarily with full-potential linearized augmented plane wave (FLAPW) method DFT calculations. Second, small organic molecules adsorbed on Pd(111) were studied using projector-augmented wave (PAW) method DFT calculations and scanning tunneling microscopy (STM) image simulations to investigate molecular interactions involved in enantioselective heterogeneous catalysis. A method for method for calculating pressure-dependent shear properties of model boundary-layer lubricants is demonstrated. The calculated values are compared with experimentally obtained results. For the case of methyl pyruvate adsorbed on Pd(111), DFT-calculated adsorption energies and structures are used along with STM simulations to identify species observed by STM imaging. A previously unobserved enol species is discovered to be present along with the expected keto species. The information about methyl pyruvate species on Pd(111) is combined with previously published studies of S-alpha-(1-naphthyl)-ethylamine (NEA) to understand the nature of their interaction upon coadsorption on Pd(111). DFT calculated structures and

  5. Automated detection of discourse segment and experimental types from the text of cancer pathway results sections.

    PubMed

    Burns, Gully A P C; Dasigi, Pradeep; de Waard, Anita; Hovy, Eduard H

    2016-01-01

    Automated machine-reading biocuration systems typically use sentence-by-sentence information extraction to construct meaning representations for use by curators. This does not directly reflect the typical discourse structure used by scientists to construct an argument from the experimental data available within a article, and is therefore less likely to correspond to representations typically used in biomedical informatics systems (let alone to the mental models that scientists have). In this study, we develop Natural Language Processing methods to locate, extract, and classify the individual passages of text from articles' Results sections that refer to experimental data. In our domain of interest (molecular biology studies of cancer signal transduction pathways), individual articles may contain as many as 30 small-scale individual experiments describing a variety of findings, upon which authors base their overall research conclusions. Our system automatically classifies discourse segments in these texts into seven categories (fact, hypothesis, problem, goal, method, result, implication) with an F-score of 0.68. These segments describe the essential building blocks of scientific discourse to (i) provide context for each experiment, (ii) report experimental details and (iii) explain the data's meaning in context. We evaluate our system on text passages from articles that were curated in molecular biology databases (the Pathway Logic Datum repository, the Molecular Interaction MINT and INTACT databases) linking individual experiments in articles to the type of assay used (coprecipitation, phosphorylation, translocation etc.). We use supervised machine learning techniques on text passages containing unambiguous references to experiments to obtain baseline F1 scores of 0.59 for MINT, 0.71 for INTACT and 0.63 for Pathway Logic. Although preliminary, these results support the notion that targeting information extraction methods to experimental results could provide

  6. Automated detection of discourse segment and experimental types from the text of cancer pathway results sections

    PubMed Central

    Burns, Gully A.P.C.; Dasigi, Pradeep; de Waard, Anita; Hovy, Eduard H.

    2016-01-01

    Automated machine-reading biocuration systems typically use sentence-by-sentence information extraction to construct meaning representations for use by curators. This does not directly reflect the typical discourse structure used by scientists to construct an argument from the experimental data available within a article, and is therefore less likely to correspond to representations typically used in biomedical informatics systems (let alone to the mental models that scientists have). In this study, we develop Natural Language Processing methods to locate, extract, and classify the individual passages of text from articles’ Results sections that refer to experimental data. In our domain of interest (molecular biology studies of cancer signal transduction pathways), individual articles may contain as many as 30 small-scale individual experiments describing a variety of findings, upon which authors base their overall research conclusions. Our system automatically classifies discourse segments in these texts into seven categories (fact, hypothesis, problem, goal, method, result, implication) with an F-score of 0.68. These segments describe the essential building blocks of scientific discourse to (i) provide context for each experiment, (ii) report experimental details and (iii) explain the data’s meaning in context. We evaluate our system on text passages from articles that were curated in molecular biology databases (the Pathway Logic Datum repository, the Molecular Interaction MINT and INTACT databases) linking individual experiments in articles to the type of assay used (coprecipitation, phosphorylation, translocation etc.). We use supervised machine learning techniques on text passages containing unambiguous references to experiments to obtain baseline F1 scores of 0.59 for MINT, 0.71 for INTACT and 0.63 for Pathway Logic. Although preliminary, these results support the notion that targeting information extraction methods to experimental results could provide

  7. Aflatoxin M1 Concentration in Various Dairy Products: Evidence for Biologically Reduced Amount of AFM1 in Yoghurt

    PubMed Central

    RAHIMIRAD, Amir; MAALEKINEJAD, Hassan; OSTADI, Araz; YEGANEH, Samal; FAHIMI, Samira

    2014-01-01

    Abstract Background Aflatoxin M1 (AFM1), a carcinogenic substance is found in milk and dairy products. The effect of season and type of dairy products on AFMi level in northern Iran was investigated in this study. Methods Three hundred samples (each season 75 samples) including raw and pasteurized milk, yoghurt, cheese, and cream samples were collected from three distinct milk producing farms. The samples were subjected to chemical and solid phase extractions and were analyzed by using HPLC technique. Recovery percentages, limit of detection and limit of quantification values were determined. Results Seventy percent and 98% were the minimum and maximum recoveries for cheese and raw milk, respectively and 0.021 and 0.063 ppb were the limit of detection and limit of quantification values for AFM1. We found that in autumn and winter the highest level (0.121 ppb) of AFM1 in cheese and cream samples and failed to detect any AFM1 in spring samples. Interestingly, our data showed that the yoghurt samples had the lowest level of AFM1 in all seasons. Conclusion There are significant differences between the AFM1 levels in dairy products in various seasons and also various types of products, suggesting spring and summer yoghurt samples as the safest products from AFM1 level point of view. PMID:25927044

  8. Predictions of the equation of state of cerium yield interesting insights into experimental results

    SciTech Connect

    Cherne, Frank J; Jensen, Brian J; Rigg, Paulo A; Elkin, Vyacheslav M

    2009-01-01

    There has been much interest in the past in understanding the dynamic properties of phase changing materials. In this paper we begin to explore the dynamic properties of the complex material of cerium. Cerium metal is a good candidate material to explore capabilities in determining a dynamic phase diagram on account of its low dynamic phase boundaries, namely, the {gamma}-{alpha}, and {alpha}-liquid phase boundaries. Here we present a combination of experimental results with calculated results to try to understand the dynamic behavior of the material. Using the front surface impact technique, we performed a series of experiments which displayed a rarefaction shock upon release. These experiments show that the reversion shock stresses occur at different magnitudes, allowing us to plot out the {gamma}-{alpha} phase boundary. Applying a multiphase equation of state a broader understanding of the experimental results will be discussed.

  9. Propagation effects for land mobile satellite systems: Overview of experimental and modeling results

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius; Vogel, Wolfhard J.

    1992-01-01

    Models developed and experiments performed to characterize the propagation environment associated with land mobile communication using satellites are discussed. Experiments were carried out with transmitters on stratospheric balloons, remotely piloted aircraft, helicopters, and geostationary satellites. This text is comprised of compiled experimental results for the expressed use of communications engineers, designers of planned Land Mobile Satellite Systems (LMSS), and modelers of propagation effects. The results presented here are mostly derived from systematic studies of propagation effects for LMSS geometries in the United States associated with rural and suburban regions. Where applicable, the authors also draw liberally from the results of other related investigations in Canada, Europe, and Australia. Frequencies near 1500 MHz are emphasized to coincide with frequency bands allocated for LMSS by the International Telecommunication Union, although earlier experimental work at 870 MHz is also included.

  10. AFM CHARACTERIZATION OF RAMAN LASER INDUCED DAMAGE ON CDZNTECRYSTAL SURFACES

    SciTech Connect

    Teague, L.; Duff, M.

    2008-10-07

    High quality CdZnTe (or CZT) crystals have the potential for use in room temperature gamma-ray and X-ray spectrometers. Over the last decade, the methods for growing high quality CZT have improved the quality of the produced crystals however there are material features that can influence the performance of these materials as radiation detectors. The presence of structural heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), and secondary phases (SPs) can have an impact on the detector performance. There is considerable need for reliable and reproducible characterization methods for the measurement of crystal quality. With improvements in material characterization and synthesis, these crystals may become suitable for widespread use in gamma radiation detection. Characterization techniques currently utilized to test for quality and/or to predict performance of the crystal as a gamma-ray detector include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In some cases, damage caused by characterization methods can have deleterious effects on the crystal performance. The availability of non-destructive analysis techniques is essential to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection. The work presented herein discusses the damage that occurs during characterization of the CZT surface by a laser during Raman spectroscopy, even at minimal laser powers. Previous Raman studies have shown that the localized annealing from tightly focused, low powered lasers results in areas of higher Te concentration on the CZT surface. This type of laser damage on the surface resulted in decreased detector performance which was most likely due to increased leakage current caused by areas of higher Te concentration. In this study

  11. Numerical predictions and experimental results of a dry bay fire environment.

    SciTech Connect

    Suo-Anttila, Jill Marie; Gill, Walter; Black, Amalia Rebecca

    2003-11-01

    The primary objective of the Safety and Survivability of Aircraft Initiative is to improve the safety and survivability of systems by using validated computational models to predict the hazard posed by a fire. To meet this need, computational model predictions and experimental data have been obtained to provide insight into the thermal environment inside an aircraft dry bay. The calculations were performed using the Vulcan fire code, and the experiments were completed using a specially designed full-scale fixture. The focus of this report is to present comparisons of the Vulcan results with experimental data for a selected test scenario and to assess the capability of the Vulcan fire field model to accurately predict dry bay fire scenarios. Also included is an assessment of the sensitivity of the fire model predictions to boundary condition distribution and grid resolution. To facilitate the comparison with experimental results, a brief description of the dry bay fire test fixture and a detailed specification of the geometry and boundary conditions are included. Overall, the Vulcan fire field model has shown the capability to predict the thermal hazard posed by a sustained pool fire within a dry bay compartment of an aircraft; although, more extensive experimental data and rigorous comparison are required for model validation.

  12. Relationship between model bacterial peptidoglycan network structures and AFM force-distance curves

    NASA Astrophysics Data System (ADS)

    Brown, Aidan; Wickham, Robert; Touhami, Ahmed; Dutcher, John

    2010-03-01

    Recent atomic force microscopy (AFM) measurements have involved pulling on Gram-negative bacterial sacculi with the AFM tip as a means of distinguishing between different proposed structures of the peptidoglycan network. The goal of the present study is to provide the theoretical connection between a given network structure and its response to the pulling force. We model the glycan strands as hinged rods, and the peptide cross-links as wormlike chains. Using Monte Carlo simulation to equilibrate the three-dimensional network, subject to a fixed AFM tip-to-substrate distance, we can compute the force exerted by the network on the AFM tip. The effects of adhesion of the sacculi to the substrate and enzymatic action on the network are included. We have modeled both the layered and the scaffold model for the peptidoglycan network structure. We have compared our theoretical force-distance curves for each network structure with experimental curves to determine which structure provides the best agreement with experiment.

  13. BOREAS AFM-07 SRC Surface Meteorological Data

    NASA Technical Reports Server (NTRS)

    Osborne, Heather; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Young, Kim; Wittrock, Virginia; Shewchuck, Stan; Smith, David E. (Technical Monitor)

    2000-01-01

    The Saskatchewan Research Council (SRC) collected surface meteorological and radiation data from December 1993 until December 1996. The data set comprises Suite A (meteorological and energy balance measurements) and Suite B (diffuse solar and longwave measurements) components. Suite A measurements were taken at each of ten sites, and Suite B measurements were made at five of the Suite A sites. The data cover an approximate area of 500 km (North-South) by 1000 km (East-West) (a large portion of northern Manitoba and northern Saskatchewan). The measurement network was designed to provide researchers with a sufficient record of near-surface meteorological and radiation measurements. The data are provided in tabular ASCII files, and were collected by Aircraft Flux and Meteorology (AFM)-7. The surface meteorological and radiation data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  14. IFNAR signaling directly modulates T lymphocyte activity, resulting in milder experimental autoimmune encephalomyelitis development.

    PubMed

    Kavrochorianou, Nadia; Evangelidou, Maria; Markogiannaki, Melina; Tovey, Michael; Thyphronitis, George; Haralambous, Sylva

    2016-01-01

    Although interferon-β is used as first-line therapy for multiple sclerosis, the cell type-specific activity of type I interferons in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis, remains obscure. In this study, we have elucidated the in vivo immunomodulatory role of type I interferon signaling in T cells during experimental autoimmune encephalomyelitis by use of a novel transgenic mouse, carrying a cd2-ifnar1 transgene on a interferon-α/β receptor 1 null genetic background, thus allowing expression of the interferon-α/β receptor 1 and hence, a functional type I interferon receptor exclusively on T cells. These transgenic mice exhibited milder experimental autoimmune encephalomyelitis with reduced T cell infiltration, demyelination, and axonal damage in the central nervous system. It is noteworthy that interferon-β administration in transgenic mice generated a more pronounced, protective effect against experimental autoimmune encephalomyelitis compared with untreated littermates. In vivo studies demonstrated that before experimental autoimmune encephalomyelitis onset, endogenous type I interferon receptor signaling in T cells led to impaired T-helper 17 responses, with a reduced fraction of CCR6(+) CD4(+) T cells in the periphery. At the acute phase, an increased proportion of interleukin-10- and interferon-γ-producing CD4(+) T cells was detected in the periphery of the transgenic mice, accompanied by up-regulation of the interferon-γ-induced gene Irgm1 in peripheral T cells. Together, these results reveal a hitherto unknown T cell-associated protective role of type I interferon in experimental autoimmune encephalomyelitis that may provide valuable clues for designing novel therapeutic strategies for multiple sclerosis. PMID:26232452

  15. FRAME (Force Review Automation Environment): MATLAB-based AFM data processor.

    PubMed

    Partola, Kostyantyn R; Lykotrafitis, George

    2016-05-01

    Data processing of force-displacement curves generated by atomic force microscopes (AFMs) for elastic moduli and unbinding event measurements is very time consuming and susceptible to user error or bias. There is an evident need for consistent, dependable, and easy-to-use AFM data processing software. We have developed an open-source software application, the force review automation environment (or FRAME), that provides users with an intuitive graphical user interface, automating data processing, and tools for expediting manual processing. We did not observe a significant difference between manually processed and automatically processed results from the same data sets. PMID:26972765

  16. Adhesion forces between AFM tips and superficial dentin surfaces.

    PubMed

    Pelin, I M; Piednoir, A; Machon, D; Farge, P; Pirat, C; Ramos, S M M

    2012-06-15

    In this work, we study the adhesion forces between atomic force microscopy (AFM) tips and superficial dentin etched with phosphoric acid. Initially, we quantitatively analyze the effect of acid etching on the surface heterogeneity and the surface roughness, two parameters that play a key role in the adhesion phenomenon. From a statistical study of the force-distance curves, we determine the average adhesion forces on the processed substrates. Our results show that the average adhesion forces, measured in water, increase linearly with the acid exposure time. The highest values of such forces are ascribed to the high density of collagen fibers on the etched surfaces. The individual contribution of exposed collagen fibrils to the adhesion force is highlighted. We also discuss in this paper the influence of the environmental medium (water/air) in the adhesion measurements. We show that the weak forces involved require working in the aqueous medium. PMID:22472512

  17. Advanced Supersonic Nozzle Concepts: Experimental Flow Visualization Results Paired With LES

    NASA Astrophysics Data System (ADS)

    Berry, Matthew; Magstadt, Andrew; Stack, Cory; Gaitonde, Datta; Glauser, Mark; Syracuse University Team; The Ohio State University Team

    2015-11-01

    Advanced supersonic nozzle concepts are currently under investigation, utilizing multiple bypass streams and airframe integration to bolster performance and efficiency. This work focuses on the parametric study of a supersonic, multi-stream jet with aft deck. The single plane of symmetry, rectangular nozzle, displays very complex and unique flow characteristics. Flow visualization techniques in the form of PIV and schlieren capture flow features at various deck lengths and Mach numbers. LES is compared to the experimental results to both validate the computational model and identify limitations of the simulation. By comparing experimental results to LES, this study will help create a foundation of knowledge for advanced nozzle designs in future aircraft. SBIR Phase II with Spectral Energies, LLC under direction of Barry Kiel.

  18. Parallel Path Magnet Motor: Development of the Theoretical Model and Analysis of Experimental Results

    NASA Astrophysics Data System (ADS)

    Dirba, I.; Kleperis, J.

    2011-01-01

    Analytical and numerical modelling is performed for the linear actuator of a parallel path magnet motor. In the model based on finite-element analysis, the 3D problem is reduced to a 2D problem, which is sufficiently precise in a design aspect and allows modelling the principle of a parallel path motor. The paper also describes a relevant numerical model and gives comparison with experimental results. The numerical model includes all geometrical and physical characteristics of the motor components. The magnetic flux density and magnetic force are simulated using FEMM 4.2 software. An experimental model has also been developed and verified for the core of switchable magnetic flux linear actuator and motor. The results of experiments are compared with those of theoretical/analytical and numerical modelling.

  19. Gradual ordering in mollusk shell nacre: theoretical modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Coppersmith, Susan N.

    2013-03-01

    Biominerals have attracted the attention of materials scientists, biologists, and mineralogists as well as physicists because of their remarkable mechanical properties and incompletely elucidated formation mechanisms. Nacre, or mother-of-pearl, is a layered biomineral composite that is widely studied because of its self-assembled, efficient and accurately ordered architecture results in remarkable resistance to fracture. New experimental tools enable us to obtain new information about the organization and structure of the mineral tablets in nacre. Our experimental and theoretical investigations yield strong evidence that orientational ordering of these tablets is the result of dynamical self-organization. This work was supported by NSF award CHE&DMR-0613972, DOE award DE-FG02-07ER15899, UW-Graduate School Vilas Award to P.U.P.A. Gilbert, and NSF awards DMR-0209630 and DMR-0906951 to SNC.

  20. Controls-structures interaction guest investigator program: Overview and phase 1 experimental results and future plans

    NASA Technical Reports Server (NTRS)

    Smith-Taylor, Rudeen; Tanner, Sharon E.

    1993-01-01

    The NASA Controls-Structures Interaction (CSI) Guest Investigator program is described in terms of its support of the development of CSI technologies. The program is based on the introduction of CSI researchers from industry and academia to available test facilities for experimental validation of technologies and methods. Phase 1 experimental results are reviewed with attention given to their use of the Mini-MAST test facility and the facility for the Advance Control Evaluation of Structures. Experiments were conducted regarding the following topics: collocated/noncollocated controllers, nonlinear math modeling, controller design, passive/active suspension systems design, and system identification and fault isolation. The results demonstrate that significantly enhanced performance from the control techniques can be achieved by integrating knowledge of the structural dynamics under consideration into the approaches.

  1. Experimental results of TDM/TDMA system via ETS-V

    NASA Astrophysics Data System (ADS)

    Sakasai, Makoto; Morikawa, Eihisa; Miura, Ryu; Arakaki, Yoshiya

    1992-07-01

    The Engineering Test Satellite-V (ETS-V) was launched in 1987, helping realize the Experimental Mobile Satellite System, where several types of mobile satellite communication experiments have been conducted. A simplified TDM/TDMA communication terminal equipment developed by the Communication Research Laboratory was used in ship experiments in the Pacific Ocean and South China Sea. This paper describes the data transmission, synchronization hold and initial acquisition characteristics resulting from these experiments.

  2. FIRST EXPERIMENTAL RESULTS FROM DEGAS, THE QUANTUM LIMITED BRIGHTNESS ELECTRON SOURCE

    SciTech Connect

    Zolotorev, Max S.; Commins, Eugene D.; Oneill, James; Sannibale, Fernando; Tremsin, Anton; Wan, Weishi

    2008-06-23

    The construction of DEGAS (DEGenerate Advanced Source), a proof of principle for a quantum limited brightness electron source, has been completed at the Lawrence Berkeley National Laboratory. The commissioning and the characterization of this source, designed to generate coherent single electron 'bunches' with brightness approaching the quantum limit at a repetition rate of few MHz, has been started. In this paper the first experimental results are described.

  3. Columbus meteoroid/debris protection study - Experimental simulation techniques and results

    NASA Astrophysics Data System (ADS)

    Schneider, E.; Kitta, K.; Stilp, A.; Lambert, M.; Reimerdes, H. G.

    1992-08-01

    The methods and measurement techniques used in experimental simulations of micrometeoroid and space debris impacts with the ESA's laboratory module Columbus are described. Experiments were carried out at the two-stage light gas gun acceleration facilities of the Ernst-Mach Institute. Results are presented on simulations of normal impacts on bumper systems, oblique impacts on dual bumper systems, impacts into cooled targets, impacts into pressurized targets, and planar impacts of low-density projectiles.

  4. Experimental results on combined ultraviolet-proton excitation of moon rock luminescence.

    NASA Technical Reports Server (NTRS)

    Nash, D. B.

    1973-01-01

    The experimental results reported indicate that a small synergistic effect may exist between near-UV radiation and solar-wind-energy protons in solar radiation that could slightly enhance luminescence generation on the moon's surface. The magnitude of the effect, however, is far too small to account for the apparent orders-of-magnitude discrepancy between reported telescope measurements of lunar luminescence and the limitation of lunar luminescence intensity based on lab studies of moon rocks.

  5. Optimal SNR exposure time for speckle imaging: experimental results with frequency-dependent detector noise

    NASA Astrophysics Data System (ADS)

    Tyler, David W.; Suzuki, Andrew H.; von Bokern, Mark A.; Keating, Donna D.; Roggemann, Michael C.

    1994-06-01

    We review recent arguments for using increased spectral bandwidth and exposure times to optimize the signal-to-noise ratio of speckle imaging estimators and discuss the tradeoff between camera exposure time and the number of data frames collected when observing time is fixed. We compare experimental results with a previously-derived expression for optimal exposure time and find reasonable agreement after accounting for frequency-dependent camera noise.

  6. A digital computer propulsion control facility: Description of capabilities and summary of experimental program results

    NASA Technical Reports Server (NTRS)

    Zeller, J. R.; Arpasi, D. J.; Lehtinen, B.

    1976-01-01

    Flight weight digital computers are being used today to carry out many of the propulsion system control functions previously delegated exclusively to hydromechanical controllers. An operational digital computer facility for propulsion control mode studies has been used successfully in several experimental programs. This paper describes the system and some of the results concerned with engine control, inlet control, and inlet engine integrated control. Analytical designs for the digital propulsion control modes include both classical and modern/optimal techniques.

  7. Surface-enhanced spectroscopy on plasmonic oligomers assembled by AFM nanoxerography

    NASA Astrophysics Data System (ADS)

    Moutet, Pierre; Sangeetha, Neralagatta M.; Ressier, Laurence; Vilar-Vidal, Noelia; Comesaña-Hermo, Miguel; Ravaine, Serge; Vallée, Renaud A. L.; Gabudean, Ana Maria; Astilean, Simion; Farcau, Cosmin

    2015-01-01

    Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from individual plasmonic oligomers are investigated by confocal Raman micro-spectroscopy and time-resolved fluorescence microscopy coupled to steady state micro-spectroscopy. The nanoparticle (NP) oligomers are made of either ligand protected Au or Au@SiO2 core-shell colloidal NPs, which were assembled into ordered arrays by atomic force microscopy (AFM) nanoxerography. A strong dependence of the SERS emission on the polarization of incident light relative to the specific geometry of the plasmonic oligomer was observed. The SEF studies, performed on a large collection of NP oligomers of various known configurations showed interesting fluorophore decay rate modification and red-shift of the emission spectra. The experimental results are analyzed theoretically by employing finite-difference time-domain (FDTD) simulations on equivalent realistic structures, within the local density of optical states (LDOS) framework. The presented results, together with the proven potential of the LDOS approach as a useful common tool for analyzing both SERS and SEF effects further the general understanding of plasmon-related phenomena in nanoparticle oligomers.Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from individual plasmonic oligomers are investigated by confocal Raman micro-spectroscopy and time-resolved fluorescence microscopy coupled to steady state micro-spectroscopy. The nanoparticle (NP) oligomers are made of either ligand protected Au or Au@SiO2 core-shell colloidal NPs, which were assembled into ordered arrays by atomic force microscopy (AFM) nanoxerography. A strong dependence of the SERS emission on the polarization of incident light relative to the specific geometry of the plasmonic oligomer was observed. The SEF studies, performed on a large collection of NP oligomers of various known configurations showed interesting fluorophore decay rate

  8. Characterisation and optimisation of flexible transfer lines for liquid helium. Part I: Experimental results

    NASA Astrophysics Data System (ADS)

    Dittmar, N.; Haberstroh, Ch.; Hesse, U.; Krzyzowski, M.

    2016-04-01

    The transfer of liquid helium (LHe) into mobile dewars or transport vessels is a common and unavoidable process at LHe decant stations. During this transfer reasonable amounts of LHe evaporate due to heat leak and pressure drop. Thus generated helium gas needs to be collected and reliquefied which requires a huge amount of electrical energy. Therefore, the design of transfer lines used at LHe decant stations has been optimised to establish a LHe transfer with minor evaporation losses which increases the overall efficiency and capacity of LHe decant stations. This paper presents the experimental results achieved during the thermohydraulic optimisation of a flexible LHe transfer line. An extensive measurement campaign with a set of dedicated transfer lines equipped with pressure and temperature sensors led to unique experimental data of this specific transfer process. The experimental results cover the heat leak, the pressure drop, the transfer rate, the outlet quality, and the cool-down and warm-up behaviour of the examined transfer lines. Based on the obtained results the design of the considered flexible transfer line has been optimised, featuring reduced heat leak and pressure drop.

  9. Estimating the hyperfine coupling parameters of the avian compass by comprehensively considering the available experimental results.

    PubMed

    Xu, Bao-Ming; Zou, Jian; Li, Jun-Gang; Shao, Bin

    2013-09-01

    Migratory birds can utilize the geomagnetic field for orientation and navigation through a widely accepted radical-pair mechanism. Although many theoretical works have been done, the available experimental results have not been fully considered, especially the temporary disorientation induced by the field which is increased by 30% of the geomagnetic field and the disorientation of the very weak resonant field of 15 nT. In this paper, we consider the monotonicity of the singlet yield angular profile as the prerequisite of direction sensitivity, and find that for some optimal values of the hyperfine coupling parameters (that is, the order of 10^{-7}∼10^{-6} meV) the experimental results available so far can be satisfied. We also investigate the effects of two decoherence environments and demonstrate that, in order to satisfy the available experimental results, the decoherence rate should be lower than the recombination rate. Finally, we investigate the effects of the fluctuating magnetic noises and find that the vertical noise destroys the monotonicity of the profile completely, but the parallel noise preserves the monotonicity perfectly and even can enhance the direction sensitivity. PMID:24125290

  10. In-Situ AFM Investigation of Solid Electrolyte Interphase Formation and Failure Mechanisms in Lithium -Ion Batteries

    NASA Astrophysics Data System (ADS)

    Mueller, Thomas; Kumar, Ravi; Tokranov, Anton; Huang, Teddy; Li, Chunzeng; Xiao, Xingcheng; Sheldon, Brian

    The formation and evolution of the solid electrolyte interphase (SEI) is critical for lifetime and performance of lithium-ion batteries (LIBs), particularly for LIBs with high energy density materials such as silicon. Si has almost ten time theoretical specific capacity vs graphite, but its volume changes during cycling (up to 400%) put enormous strains on the SEI layer, resulting in continuous capacity loss. In this study we report in situ atomic force microscopy (AFM) investigation on the formation and failure mechanisms of SEI layer using patterned Si island structures. Due to the shear lag effect, patterned Si islands go through lateral expansion and Contraction, putting the SEI layer in tension and compression during lithiation and delithiation, respectively. Experimentally, we performed the studies in a glovebox with <1 ppm O2 and H2O, using PeakForce Tapping to image the extremely fragile SEI layer. We show for the first time the in operando cracking of SEI layer. To understand the mechanics of the SEI layer, the critical strain for cracking was derived from a progression of the AFM images. Our studies provide new insight into SEI formation, evolution and its mechanical response, and offer guidance to tailor passivation layers for optimal performance.

  11. Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

    SciTech Connect

    Choi, E.M.; Marchewka, C.D.; Mastovsky, I.; Sirigiri, J.R.; Shapiro, M.A.; Temkin, R.J.

    2006-02-15

    A new result from a 110 GHz gyrotron at MIT is reported with an output power of 1.67 MW and an efficiency of 42% when operated at 97 kV and 41 A for 3 {mu}s pulses in the TE{sub 22,6} mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43 MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE{sub 19,7} mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110 GHz gyrotron.

  12. The co-design of interface sensing and tailoring of ultra-thin film with ultrasonic vibration-assisted AFM system.

    PubMed

    Shi, Jialin; Liu, Lianqing; Li, Guangyong

    2016-06-10

    Ultra-thin films (e.g., graphene, MoS2, and black phosphorus) have shown amazing performance in a variety of applications. The tailoring or machining of these ultra-thin films is often the preliminary step to manufacturing them into functional devices. Atomic force microscopy (AFM) is a flexible, high-efficiency and low-cost tailoring or machining tool with the advantages of high resolution and precision. However, the current AFM-based tailoring methods are often set up as an open loop regarding the machined depth and state. Thus, because of a lack of real-time feedback, an inappropriate applied force leads to over-cutting or under-cutting, which limits the performance of the manufactured devices. In this study, we propose a real-time tailoring and sensing method based on an ultrasonic vibration-assisted (USV-assisted) AFM system to solve the above problems. With the proposed method, the machined depth and state can be sensed in real time by detecting the phase value of the vibrating cantilever. To characterize and gain insight into the phase responses of the cantilever to the machined depth and sample material, a theoretical dynamic model of a cantilever-film vibrating system is introduced to model the machining process, and a sensing theory of machined depth and state is developed based on a USV-assisted AFM system. The experimental results verify the feasibility and effectiveness of the proposed method, which in turn lay the foundation for a closed-loop tailoring control strategy for ultra-thin films. PMID:27146083

  13. The co-design of interface sensing and tailoring of ultra-thin film with ultrasonic vibration-assisted AFM system

    NASA Astrophysics Data System (ADS)

    Shi, Jialin; Liu, Lianqing; Li, Guangyong

    2016-06-01

    Ultra-thin films (e.g., graphene, MoS2, and black phosphorus) have shown amazing performance in a variety of applications. The tailoring or machining of these ultra-thin films is often the preliminary step to manufacturing them into functional devices. Atomic force microscopy (AFM) is a flexible, high-efficiency and low-cost tailoring or machining tool with the advantages of high resolution and precision. However, the current AFM-based tailoring methods are often set up as an open loop regarding the machined depth and state. Thus, because of a lack of real-time feedback, an inappropriate applied force leads to over-cutting or under-cutting, which limits the performance of the manufactured devices. In this study, we propose a real-time tailoring and sensing method based on an ultrasonic vibration-assisted (USV-assisted) AFM system to solve the above problems. With the proposed method, the machined depth and state can be sensed in real time by detecting the phase value of the vibrating cantilever. To characterize and gain insight into the phase responses of the cantilever to the machined depth and sample material, a theoretical dynamic model of a cantilever-film vibrating system is introduced to model the machining process, and a sensing theory of machined depth and state is developed based on a USV-assisted AFM system. The experimental results verify the feasibility and effectiveness of the proposed method, which in turn lay the foundation for a closed-loop tailoring control strategy for ultra-thin films.

  14. Probing the PEDOT:PSS/cell interface with conductive colloidal probe AFM-SECM

    NASA Astrophysics Data System (ADS)

    Knittel, P.; Zhang, H.; Kranz, C.; Wallace, G. G.; Higgins, M. J.

    2016-02-01

    Conductive colloidal probe Atomic Force-Scanning Electrochemical Microscopy (AFM-SECM) is a new approach, which employs electrically insulated AFM probes except for a gold-coated colloid located at the end of the cantilever. Hence, force measurements can be performed while biasing the conductive colloid under physiological conditions. Moreover, such colloids can be modified by electrochemical polymerization resulting, e.g. in conductive polymer-coated spheres, which in addition may be loaded with specific dopants. In contrast to other AFM-based single cell force spectroscopy measurements, these probes allow adhesion measurements at the cell-biomaterial interface on multiple cells in a rapid manner while the properties of the polymer can be changed by applying a bias. In addition, spatially resolved electrochemical information e.g., oxygen reduction can be obtained simultaneously. Conductive colloid AFM-SECM probes modified with poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonate (PEDOT:PSS) are used for single cell force measurements in mouse fibroblasts and single cell interactions are investigated as a function of the applied potential.Conductive colloidal probe Atomic Force-Scanning Electrochemical Microscopy (AFM-SECM) is a new approach, which employs electrically insulated AFM probes except for a gold-coated colloid located at the end of the cantilever. Hence, force measurements can be performed while biasing the conductive colloid under physiological conditions. Moreover, such colloids can be modified by electrochemical polymerization resulting, e.g. in conductive polymer-coated spheres, which in addition may be loaded with specific dopants. In contrast to other AFM-based single cell force spectroscopy measurements, these probes allow adhesion measurements at the cell-biomaterial interface on multiple cells in a rapid manner while the properties of the polymer can be changed by applying a bias. In addition, spatially resolved electrochemical

  15. Numerical prediction of freezing fronts in cryosurgery: comparison with experimental results.

    PubMed

    Fortin, André; Belhamadia, Youssef

    2005-08-01

    Recent developments in scientific computing now allow to consider realistic applications of numerical modelling to medicine. In this work, a numerical method is presented for the simulation of phase change occurring in cryosurgery applications. The ultimate goal of these simulations is to accurately predict the freezing front position and the thermal history inside the ice ball which is essential to determine if cancerous cells have been completely destroyed. A semi-phase field formulation including blood flow considerations is employed for the simulations. Numerical results are enhanced by the introduction of an anisotropic remeshing strategy. The numerical procedure is validated by comparing the predictions of the model with experimental results. PMID:16298846

  16. Summary of experimental heat-transfer results from the turbine hot section facility

    NASA Astrophysics Data System (ADS)

    Gladden, Herbert J.; Yeh, Fredrick C.

    1993-04-01

    Experimental data from the turbine Hot Section Facility are presented and discussed. These data include full-coverage film-cooled airfoil results as well as special instrumentation results obtained at simulated real engine conditions. Local measurements of airfoil wall temperature, airfoil gas-path static-pressure distribution, and local heat-transfer coefficient distributions are presented and discussed. In addition, measured gas and coolant temperatures and pressures are presented. These data are also compared with analyses from Euler and boundary-layer codes.

  17. Comparison of Finite Element Non-Linear Beam Random Response with Experimental Results

    NASA Astrophysics Data System (ADS)

    Chen, R. R.; Mei, C.; Wolfe, HF

    1996-09-01

    A finite element formulation combined with the equivalent linearization technique and normal mode method is developed for the non-linear random response of beams subjected to acoustic and thermal loads applied simultaneously. To validate the present formulation and solution procedure, results are compared with the classical continuum solution and the Fokker-Planck-Kolmogorov equation solution. Comparison is also made with experimental data for a pre-stretched clamped beam. Random responses of thermally buckled simply supported beam, clamped beam and simply supported-clamped beam are presented. The comparison of the present simultaneously loaded response with the existing sequentially loaded results shows a significant difference between them.

  18. Studies of Multipactor in Dielectric-Loaded Accelerator Structures: Comparison of Simulation Results with Experimental Data

    SciTech Connect

    Sinitsyn, Oleksandr; Nusinovich, Gregory; Antonsen, Thomas Jr.

    2010-11-04

    In this paper new results of numerical studies of multipactor in dielectric-loaded accelerator structures are presented. The results are compared with experimental data obtained during recent studies of such structures performed by Argonne National Laboratory, the Naval Research Laboratory, SLAC National Accelerator Laboratory and Euclid TechLabs, LLC. Good agreement between the theory and experiment was observed for the structures with larger inner diameter, however the structures with smaller inner diameter demonstrated a discrepancy between the two. Possible reasons for such discrepancy are discussed.

  19. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, T.; Sholes, J. E.

    1975-01-01

    The preliminary results of two projects in the development phase of reliable wind turbines designed to supply cost-competitive electrical energy were discussed. An experimental 100 kW wind turbine design and its status are first reviewed. The results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs are also discussed. These studies predict wind energy costs of 1.5 to 7 cents per kW-h for wind turbines produced in quantities of 100 to 1000 per year and located at sites having average winds of 12 to 18 mph.

  20. The 3D structure of the hadrons: recents results and experimental program at Jefferson Lab

    SciTech Connect

    Munoz Camacho, Carlos

    2014-04-01

    The understanding of Quantum Chromodynamics (QCD) at large distances still remains one of the main outstanding problems of nuclear physics. Studying the internal structure of hadrons provides a way to probe QCD in the non-perturbative domain and can help us unravel the internal structure of the most elementary blocks of matter. Jefferson Lab (JLab) has already delivered results on how elementary quarks and gluons create nucleon structure and properties. The upgrade of JLab to 12 GeV will allow the full exploration of the valence-quark structure of nucleons and the extraction of real threedimensional pictures. I will present recent results and review the future experimental program at JLab.

  1. A three-phase series-parallel resonant converter -- analysis, design, simulation and experimental results

    SciTech Connect

    Bhat, A.K.S.; Zheng, L.

    1995-12-31

    A three-phase dc-to-dc series-parallel resonant converter is proposed and its operating modes for 180{degree} wide gating pulse scheme are explained. A detailed analysis of the converter using constant current model and Fourier series approach is presented. Based on the analysis, design curves are obtained and a design example of 1 kW converter is given. SPICE simulation results for the designed converter and experimental results for a 500 W converter are presented to verify the performance of the proposed converter for varying load conditions. The converter operates in lagging PF mode for the entire load range and requires a narrow variation in switching frequency.

  2. Segmental calibration for commercial AFM in vertical direction

    NASA Astrophysics Data System (ADS)

    Shi, Yushu; Gao, Sitian; Lu, Mingzhen; Li, Wei; Xu, Xuefang

    2013-01-01

    Atomic force microscopy (AFM) is most widely applied in scientific research and industrial production. AFM is a scanning probe imaging and measuring device, useful for physical and chemical studies. Depends on its basic structure, microscopic surface pattern can be measured and captured by mechanically scanning. Its vertical and horizon resolution can reach to 0.01nm and 0.1nm. Commonly the measurement values of commercial AFM are directly from scanning piezoelectric tube, so that it not a traceable value. In order to solve the problem of commercial AFM's traceability, step height standard references are applied to calibrate the piezoelectric ceramic housing in scanning tube. All of the serial of step height standard references, covering the commercial AFM vertical scale, are calibrated by Metrology AFM developed by National Institute of Metrology (NIM), China. Three interferometers have been assembled in its XYZ axis, therefore the measurement value can directly trace to laser wavelength. Because of nonlinear characteristic of PZT, the method of segmental calibration is proposed. The measurement scale can be divided into several subsections corresponding to the calibrated values of the series of step height standards references. By this method the accuracy of measurements can be ensured in each segment measurement scale and the calibration level of the whole instrument can be promoted. In order to get a standard step shape by commercial AFM, substrate removal method is applied to deal with the bow shape problem.

  3. Experimental Results of NWCF Run H4 Calcine Dissolution Studies Performed in FY-98 and -99

    SciTech Connect

    Garn, Troy Gerry; Herbst, Ronald Scott; Batcheller, Thomas Aquinas; Sierra, Tracy Laureena

    2001-08-01

    Dissolution experiments were performed on actual samples of NWCF Run H-4 radioactive calcine in fiscal years 1998 and 1999. Run H-4 is an aluminum/sodium blend calcine. Typical dissolution data indicates that between 90-95 wt% of H-4 calcine can be dissolved using 1gram of calcine per 10 mLs of 5-8M nitric acid at boiling temperature. Two liquid raffinate solutions composed of a WM-188/aluminum nitrate blend and a WM-185/aluminum nitrate blend were converted into calcine at the NWCF. Calcine made from each blend was collected and transferred to RAL for dissolution studies. The WM-188/aluminum nitrate blend calcine was dissolved with resultant solutions used as feed material for separation treatment experimentation. The WM-185/aluminum nitrate blend calcine dissolution testing was performed to determine compositional analyses of the dissolved solution and generate UDS for solid/liquid separation experiments. Analytical fusion techniques were then used to determine compositions of the solid calcine and UDS from dissolution. The results from each of these analyses were used to calculate elemental material balances around the dissolution process, validating the experimental data. This report contains all experimental data from dissolution experiments performed using both calcine blends.

  4. Wind Code Application to External Forebody Flowfields with Comparisons to Experimental Results

    NASA Technical Reports Server (NTRS)

    Frate, F. C.; Kim, H. D.

    2001-01-01

    The WIND Code, a general purpose Navier-Stokes solver, has been utilized to obtain supersonic external flowfield Computational Fluid Dynamics (CFD) solutions over an axisymmetric, parabolic forebody with comparisons made to wind tunnel experimental results. Various cases have been investigated at supersonic freestream conditions ranging from Mach 2.0 to 3.5, at 0 deg and 3 deg angles-of-attack, and with either a sharp-nose or blunt-nose forebody configuration. Both a turbulent (Baldwin-Lomax algebraic turbulence model) and a laminar model have been implemented in the CFD. Obtaining the solutions involved utilizing either the parabolized- or full-Navier-Stokes analyses supplied in WIND. Comparisons have been made with static pressure measurements, with boundary-layer rake and flowfield rake pitot pressure measurements, and with temperature sensitive paint experimental results. Using WIND's parabolized Navier-Stokes capability, grid sequencing, and the Baldwin-Lomax algebraic turbulence model allowed for significant reductions in computational time while still providing good agreement with experiment. Given that CFD and experiment compare well, WIND is found to be a good computational platform for solving this type of forebody problem, and the grids developed in conjunction with it will be used in the future to investigate varying freestream conditions not tested experimentally.

  5. Respiratory rate detection algorithm based on RGB-D camera: theoretical background and experimental results.

    PubMed

    Benetazzo, Flavia; Freddi, Alessandro; Monteriù, Andrea; Longhi, Sauro

    2014-09-01

    Both the theoretical background and the experimental results of an algorithm developed to perform human respiratory rate measurements without any physical contact are presented. Based on depth image sensing techniques, the respiratory rate is derived by measuring morphological changes of the chest wall. The algorithm identifies the human chest, computes its distance from the camera and compares this value with the instantaneous distance, discerning if it is due to the respiratory act or due to a limited movement of the person being monitored. To experimentally validate the proposed algorithm, the respiratory rate measurements coming from a spirometer were taken as a benchmark and compared with those estimated by the algorithm. Five tests were performed, with five different persons sat in front of the camera. The first test aimed to choose the suitable sampling frequency. The second test was conducted to compare the performances of the proposed system with respect to the gold standard in ideal conditions of light, orientation and clothing. The third, fourth and fifth tests evaluated the algorithm performances under different operating conditions. The experimental results showed that the system can correctly measure the respiratory rate, and it is a viable alternative to monitor the respiratory activity of a person without using invasive sensors. PMID:26609383

  6. Artificial cochlea and acoustic black hole travelling waves observation: Model and experimental results

    NASA Astrophysics Data System (ADS)

    Foucaud, Simon; Michon, Guilhem; Gourinat, Yves; Pelat, Adrien; Gautier, François

    2014-07-01

    An inhomogeneous fluid structure waveguide reproducing passive behaviour of the inner ear is modelled with the help of the Wentzel-Kramers-Brillouin method. A physical setup is designed and built. Experimental results are compared with a good correlation to theoretical ones. The experimental setup is a varying width plate immersed in fluid and terminated with an acoustic black hole. The varying width plate provides a spatial repartition of the vibration depending on the excitation frequency. The acoustic black hole is made by decreasing the plate's thickness with a quadratic profile and by covering this region with a thin film of viscoelastic material. Such a termination attenuates the flexural wave reflection at the end of the waveguide, turning standing waves into travelling waves.

  7. Shuttle Return To Flight Experimental Results: Cavity Effects on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Horvath, Thomas J.; Berry, Scott A.

    2006-01-01

    The effect of an isolated rectangular cavity on hypersonic boundary layer transition of the windward surface of the Shuttle Orbiter has been experimentally examined in the Langley Aerothermodynamics Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for return to flight. This experimental study was initiated to provide a cavity effects database for developing hypersonic transition criteria to support on-orbit decisions to repair a damaged thermal protection system. Boundary layer transition results were obtained using 0.0075-scale Orbiter models with simulated tile damage (rectangular cavities) of varying length, width, and depth. The database contained within this report will be used to formulate cavity-induced transition correlations using predicted boundary layer edge parameters.

  8. Design and Experimental Results for the S825 Airfoil; Period of Performance: 1998-1999

    SciTech Connect

    Somers, D. M.

    2005-01-01

    A 17%-thick, natural-laminar-flow airfoil, the S825, for the 75% blade radial station of 20- to 40-meter, variable-speed and variable-pitch (toward feather), horizontal-axis wind turbines has been designed and analyzed theoretically and verified experimentally in the NASA Langley Low-Turbulence Pressure Tunnel. The two primary objectives of high maximum lift, relatively insensitive to roughness and low-profile drag have been achieved. The airfoil exhibits a rapid, trailing-edge stall, which does not meet the design goal of a docile stall. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results generally show good agreement.

  9. Radio propagation at 900 MHz in urban areas: Models with a fixed frequency and experimental results

    NASA Astrophysics Data System (ADS)

    Olivier, P.; Tiffon, J.

    1984-09-01

    Models which describe multipath propagation are examined in order to design a 900 MHz mobile communication system adapted to urban areas. A justification of the experimental data treatment is derived from this analysis. The measurements were made at a fixed 855 MHz frequency, transmitting from three locations. The fast fluctuations of the received signals are well represented by a Rayleigh process, which means that there are practically no paths of direct transmission. The coherence length is 1 m. The statistical distribution of the average field is Gaussian and the normal deviation decreases with the distance emitter-receiver. The empiric Okumura-Hata prediction model agrees well with the experimental results, giving an average cell field decreasing with distance with a logarithmic law.

  10. Shuttle Return To Flight Experimental Results: Protuberance Effects on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Berry, Scott A.; Horvath, Thomas J.

    2006-01-01

    The effect of isolated roughness elements on the windward boundary layer of the Shuttle Orbiter has been experimentally examined in the Langley Aerothermodynamic Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for return to flight. This experimental effort was initiated to provide a roughness effects database for developing transition criteria to support on-orbit decisions to repair damage to the thermal protection system. Boundary layer transition results were obtained using trips of varying heights and locations along the centerline and attachment lines of 0.0075-scale models. Global heat transfer images using phosphor thermography of the Orbiter windward surface and the corresponding heating distributions were used to infer the state of the boundary layer (laminar, transitional, or turbulent). The database contained within this report will be used to formulate protuberance-induced transition correlations using predicted boundary layer edge parameters.

  11. Use of dynamic theory to describe experimental results from volume holography

    NASA Technical Reports Server (NTRS)

    Magnusson, R.; Gaylord, T. K.

    1976-01-01

    The general applicability of dynamic theory to the description of the recording and readout characteristics of volume (thick) hologram gratings is indicated. In dynamic theory (as opposed to static theory), the volume nature of the thick holographic grating allows the interference of an incident light beam with its own diffracted beam inside the recording medium. This effect causes the continuous recording of another grating that alters the initial one, producing a resultant grating that is not uniform through the thickness of the recording material and a grating whose writing and reading characteristics may vary dramatically, depending on the recording material and the experimental conditions. A large number of diverse types of writing, reading, and angular-selectivity behavior have been reported. The dynamic theory of thick-hologram writing and reading is shown to predict qualitatively all of these various types of experimental behavior.

  12. Design and Experimental Results for the S827 Airfoil; Period of Performance: 1998--1999

    SciTech Connect

    Somers, D. M.

    2005-01-01

    A 21%-thick, natural-laminar-flow airfoil, the S827, for the 75% blade radial station of 40- to 50-meter, stall-regulated, horizontal-axis wind turbines has been designed and analyzed theoretically and verified experimentally in the NASA Langley Low-Turbulence Pressure Tunnel. The primary objective of restrained maximum lift has not been achieved, although the maximum lift is relatively insensitive to roughness, which meets the design goal. The airfoil exhibits a relatively docile stall, which meets the design goal. The primary objective of low profile drag has been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results generally show good agreement with the exception of maximum lift, which is significantly underpredicted.

  13. Stimulating Contributions to Public Goods through Information Feedback: Some Experimental Results

    PubMed Central

    Janssen, Marco A.; Lee, Allen; Sundaram, Hari

    2016-01-01

    In traditional public good experiments participants receive an endowment from the experimenter that can be invested in a public good or kept in a private account. In this paper we present an experimental environment where participants can invest time during five days to contribute to a public good. Participants can make contributions to a linear public good by logging into a web application and performing virtual actions. We compared four treatments, with different group sizes and information of (relative) performance of other groups. We find that information feedback about performance of other groups has a small positive effect if we control for various attributes of the groups. Moreover, we find a significant effect of the contributions of others in the group in the previous day on the number of points earned in the current day. Our results confirm that people participate more when participants in their group participate more, and are influenced by information about the relative performance of other groups. PMID:27459070

  14. Activity of "nonspecific pancreatic carboxylesterase" in rat serum in experimentally induced acute pancreatitis (preliminary results).

    PubMed

    Kálmán, A; Kálmán, Z; Velösy, G; Vargha, G; Vargha, G; Papp, M

    1989-01-01

    The aim of this study was to obtain more information on the serum level of "nonspecific pancreatic carboxylesterase" (PCE) in experimentally induced acute pancreatitis in rats. The effects of caerulein stimulation, hepatic duct ligation, bile-pancreatic duct ligation or the effect of retrograde injection of saline, 5% taurocholate and sunflower oil were investigated. The activity of PCE and amylase was measured in the serum, pancreatic tissue, pancreatic juice and ascitic fluid. The changes in PCE activity were greater (both in directions to increase or decrease) than that of amylase, produced by different experimental procedures. The results confirm the thesis that the serum activity of PCE is a more sensitive diagnostic method than that of amylase to detect the inflammatory process in the pancreas or the effect of obstruction of the pancreatic duct. PMID:2480696

  15. Circular Samples as Objects for Magnetic Resonance Imaging - Mathematical Simulation, Experimental Results

    NASA Astrophysics Data System (ADS)

    Frollo, Ivan; Krafčík, Andrej; Andris, Peter; Přibil, Jiří; Dermek, Tomáš

    2015-12-01

    Circular samples are the frequent objects of "in-vitro" investigation using imaging method based on magnetic resonance principles. The goal of our investigation is imaging of thin planar layers without using the slide selection procedure, thus only 2D imaging or imaging of selected layers of samples in circular vessels, eppendorf tubes,.. compulsorily using procedure "slide selection". In spite of that the standard imaging methods was used, some specificity arise when mathematical modeling of these procedure is introduced. In the paper several mathematical models were presented that were compared with real experimental results. Circular magnetic samples were placed into the homogenous magnetic field of a low field imager based on nuclear magnetic resonance. For experimental verification an MRI 0.178 Tesla ESAOTE Opera imager was used.

  16. Rotational knee strain resulting in patellar dislocation. An experimental study in rabbits.

    PubMed

    Finsterbush, A

    1982-09-01

    The right lower extremities of 64 young rabbits were immobilized by a plaster spica. The animals developed a gait pattern, which included internal tibial rotation and adduction of the left (unimmobilized) tibia. Twenty-one of the animals developed medial patellar dislocation in the unimmobilized lower extremity. The mechanism of the patellar dislocation in this experimental model was possibly overstretching of the lateral colateral ligament and the lateral side of the joint capsule, associated with medial rotation of the tibia and the tibial tubercle. The direction of patellar pull when gliding inferiorly during knee flexion was shifted medially, resulting in patellar dislocation and secondarily, in formation of an exostosis under the displaced patella. Hip arthrodesis in humans, as a course of rotational instability of the contralateral knee, resembles some aspects of this experimental condition. PMID:7105585

  17. LBE water interaction in sub-critical reactors: First experimental and modelling results

    NASA Astrophysics Data System (ADS)

    Ciampichetti, A.; Agostini, P.; Benamati, G.; Bandini, G.; Pellini, D.; Forgione, N.; Oriolo, F.; Ambrosini, W.

    2008-06-01

    This paper concerns the study of the phenomena involved in the interaction between LBE and pressurised water which could occur in some hypothetical accidents in accelerator driven system type reactors. The LIFUS 5 facility was designed and built at ENEA-Brasimone to reproduce this kind of interaction in a wide range of conditions. The first test of the experimental program was carried out injecting water at 70 bar and 235 °C in a reaction vessel containing LBE at 1 bar and 350 °C. A pressurisation up to 80 bar was observed in the test section during the considered transient. The SIMMER III code was used to simulate the performed test. The calculated data agree in a satisfactory way with the experimental results giving confidence in the possibility to use this code for safety analyses of heavy liquid metal cooled reactors.

  18. Supersonic Retropropulsion Experimental Results from the NASA Ames 9- x 7-Foot Supersonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Rhode, Matthew N.; Edquist, Karl T.

    2012-01-01

    Supersonic retropropulsion was experimentally examined in the Ames Research Center 9x7-Foot Supersonic Wind Tunnel at Mach 1.8 and 2.4. The experimental model, previously designed for and tested in the Langley Research Center Unitary Plan Wind Tunnel at Mach 2.4, 3.5 and 4.6, was a 5-in diameter 70-deg sphere-cone forebody with a 9.55-in long cylindrical aftbody. The forebody was designed to accommodate up to four 4:1 area ratio nozzles, one on the model centerline and the other three on the half radius spaced 120-deg apart. Surface pressure and flow visualization were the primary measurements, including high-speed data to investigate the dynamics of the interactions between the bow and nozzle shocks. Three blowing configurations were tested with thrust coefficients up to 10 and angles of attack up to 20-deg. Preliminary results and observations from the test are provided

  19. Crystalline and Spectroscopic Experimental Study of the Dinitromesithylen (DNM) Compared with the Theoretical Results

    NASA Astrophysics Data System (ADS)

    Brihi, O.; Medjroubi, M. L.; Hamdouni, N.; Meinnel, J.; Boucekkine, A.; Boudjada, A.

    The aim by our group is to understand the behaviour of the grouping methyl starting from the study of molecules having a great symmetry. In this part of work, it is had the crystalline structure of the dinitromesitylen (DNM) who is solved starting from the diffraction of x-rays starting from a monocrystal at the ambient temperature. Parallel to the experimental study, we undertook theoretical calculations conformation of the insulated molecule of DNM by using the methods of the DFT (Density Functional Theory).Calculations of optimization of the molecular conformation of the DNM by using the chain of program GAUSSIAN03 and functional MPW1PW91, B3LYP level with the 6-311G and LANL2DZ bases gave a conformation Cs with results very close to the experiment for the lengths and the angles of bond. The computation results obtained starting from the base set (6-311G) and functional MPW1PW91 give for the conformation of Dinitromesitylen (DNM) a good agreement of about a 1.9% for the lengths of bond and 1.2% for the angles of bond compared with the results of the diffraction of x-rays. Calculations of Raman and infra-red spectroscopy undertaken starting from the results of optimization by using same functional MPW1PW91 and B3LYP and the sets of bases 6-311G LanL2DZ led to the values of frequencies very close to the experimental results.

  20. Vibration Based Crack Detection in a Rotating Disk. Part 2; Experimental Results

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Haase, Wayne C.; Baaklini, George

    2005-01-01

    This paper describes the experimental results concerning the detection of a crack in a rotating disk. The goal was to utilize blade tip clearance and shaft vibration measurements to monitor changes in the system's center of mass and/or blade deformation behaviors. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system's center of mass occurs. Here, a notch was used to simulate an actual crack. The vibration based experimental results failed to identify the existence of a notch when utilizing the approach described above, even with a rather large, circumferential notch (l.2 in.) located approximately mid-span on the disk (disk radius = 4.63 in. with notch at r = 2.12 in.). This was somewhat expected, since the finite element based results in Part 1 of this study predicted changes in blade tip clearance as well as center of mass shifts due to a notch to be less than 0.001 in. Therefore, the small changes incurred by the notch could not be differentiated from the mechanical and electrical noise of the rotor system. Although the crack detection technique of interest failed to identify the existence ofthe notch, the vibration data produced and captured here will be utilized in upcoming studies that will focus on different data mining techniques concerning damage detection in a disk.

  1. Dynamics of the nanoneedle probe in trolling mode AFM.

    PubMed

    Abdi, Ahmad; Pishkenari, Hossein Nejat; Keramati, Ramtin; Minary-Jolandan, Majid

    2015-05-22

    Atomic force microscopy (AFM), as an indispensable tool for nanoscale characterization, presents major drawbacks for operation in a liquid environment arising from the large hydrodynamic drag on the vibrating cantilever. The newly introduced 'Trolling mode' (TR-mode) AFM resolves this complication by using a specialized nanoneedle cantilever that keeps the cantilever outside of the liquid. Herein, a mechanical model with a lumped mass was developed to capture the dynamics of such a cantilever with a nanoneedle tip. This new developed model was applied to investigate the effects of the needle-liquid interface on the performance of the AFM, including the imaging capability in liquid. PMID:25915451

  2. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results

    PubMed Central

    Humada, Ali M.; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M.; Ahmed, Mushtaq N.

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  3. Comparison between experimental and analytical results for seesaw energy dissipation systems using fluid viscous dampers

    NASA Astrophysics Data System (ADS)

    Kang, Jae-Do; Tagawa, Hiroshi

    2016-03-01

    This paper presents results of experimental and numerical investigations of a seesaw energy dissipation system (SEDS) using fluid viscous dampers (FVDs). To confirm the characteristics of the FVDs used in the tests, harmonic dynamic loading tests were conducted in advance of the free vibration tests and the shaking table tests. Shaking table tests were conducted to demonstrate the damping capacity of the SEDS under random excitations such as seismic waves, and the results showed SEDSs have sufficient damping capacity for reducing the seismic response of frames. Free vibration tests were conducted to confirm the reliability of simplified analysis. Time history response analyses were also conducted and the results are in close agreement with shaking table test results.

  4. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results.

    PubMed

    Humada, Ali M; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M; Ahmed, Mushtaq N

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  5. Comparison of Computational and Experimental Microphone Array Results for an 18%-Scale Aircraft Model

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Humphreys, William M.; Khorrami, Mehdi R.; Fares, Ehab; Casalino, Damiano; Ravetta, Patricio A.

    2015-01-01

    An 18%-scale, semi-span model is used as a platform for examining the efficacy of microphone array processing using synthetic data from numerical simulations. Two hybrid RANS/LES codes coupled with Ffowcs Williams-Hawkings solvers are used to calculate 97 microphone signals at the locations of an array employed in the NASA LaRC 14x22 tunnel. Conventional, DAMAS, and CLEAN-SC array processing is applied in an identical fashion to the experimental and computational results for three different configurations involving deploying and retracting the main landing gear and a part span flap. Despite the short time records of the numerical signals, the beamform maps are able to isolate the noise sources, and the appearance of the DAMAS synthetic array maps is generally better than those from the experimental data. The experimental CLEAN-SC maps are similar in quality to those from the simulations indicating that CLEAN-SC may have less sensitivity to background noise. The spectrum obtained from DAMAS processing of synthetic array data is nearly identical to the spectrum of the center microphone of the array, indicating that for this problem array processing of synthetic data does not improve spectral comparisons with experiment. However, the beamform maps do provide an additional means of comparison that can reveal differences that cannot be ascertained from spectra alone.

  6. Supersonic Retropropulsion Experimental Results from the NASA Langley Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Rhode, Matthew N.; Edquist, Karl T.; Player, Charles J.

    2011-01-01

    A new supersonic retropropulsion experimental effort, intended to provide code validation data, was recently completed in the Langley Research Center Unitary Plan Wind Tunnel Test Section 2 over the Mach number range from 2.4 to 4.6. The experimental model was designed using insights gained from pre-test computations, which were instrumental for sizing and refining the model to minimize tunnel wall interference and internal flow separation concerns. A 5-in diameter 70-deg sphere-cone forebody with a roughly 10-in long cylindrical aftbody was the baseline configuration selected for this study. The forebody was designed to accommodate up to four 4:1 area ratio supersonic nozzles. Primary measurements for this model were a large number of surface pressures on the forebody and aftbody. Supplemental data included high-speed Schlieren video and internal pressures and temperatures. The run matrix was developed to allow for the quantification of various sources of experimental uncertainty, such as random errors due to run-to-run variations and bias errors due to flow field or model misalignments. Preliminary results and observations from the test are presented, while detailed data and uncertainty analyses are ongoing.

  7. Transdermal flux predictions for selected selective oestrogen receptor modulators (SERMs): comparison with experimental results.

    PubMed

    Güngör, Sevgi; Delgado-Charro, M Begoña; Masini-Etévé, Valérie; Potts, Russell O; Guy, Richard H

    2013-12-28

    The aim of this work was to evaluate the feasibility of delivering transdermally a series of highly lipophilic compounds (log P ~4-7), comprising several selective oestrogen receptor modulators and a modified testosterone (danazol). The maximum fluxes of the drugs were predicted theoretically using the modified Potts & Guy algorithm (to determine the permeability coefficient (kp) from water) and the calculated aqueous solubilities. The correction provided by Cleek & Bunge took into account the contribution of the viable epidermal barrier to the skin permeation of highly lipophilic compounds. Experimental measurements of drug fluxes from saturated hydroalcoholic solutions were determined in vitro through excised pig skin. Overall, the predicted fluxes were in good general agreement (within a factor of 10) with the experimental results. Most of the experimental fluxes were greater than those predicted theoretically suggesting that the 70:30 v/v ethanol-water vehicle employed may have had a modest skin penetration enhancement effect. This investigation shows that the transdermal fluxes of highly lipophilic compounds can be reasonably predicted from first principles provided that the viable epidermis, underlying the stratum corneum, is included as a potentially important contributor to the skin's overall barrier function. Furthermore, the absolute values of the measured fluxes, when considered in parallel with previous clinical studies, indicate that it might be feasible to topically deliver a therapeutically useful amount of some of the compounds considered to treat cancerous breast tissue. PMID:24076520

  8. Experimental results of the investigation of a laboratory cold seal TEC

    SciTech Connect

    Yarygin, V.I.; Mironov, V.S.; Kiryushenko, A.I.; Mikheyev, A.S.; Tulin, S.M.; Meleta, Y.A.; Yarygin, D.V.; Wolff, L.R.

    1998-07-01

    The results of experimental investigation of characteristics of a laboratory Cold Seal Thermionic Energy Converter (CS TEC) with a built-in gas regulated heat pipe are discussed. They were obtained to justify the electric-thermal-physical characteristics of a flame heated CS TEC. The CS TEC design is being developed by a joint Russian-Dutch team of researchers with support of the Netherlands Organization for Scientific Research (NWO). The concept of this flame heated Cold Seal TEC was presented in a previous publication. This paper deals with experimental data on the emission properties of electrodes and the voltage-current characteristics (JVC) of an electrically heated laboratory TEC. They were studied over a wide interval of variation in the electrode temperature and interelectrode distance. The cesium vapour working pressure in the interelectrode space was regulated both by the conventional method (using a cesium reservoir) and by means of a gas regulated cesium heat pipe. This allows one to use a rubber (viton) seal in the non-condensing gas (argon) area. The acquired experimental characteristics will allow one to identify the inner parameters at further stages of their work when testing the full-scale flame heated CS TEC.

  9. Comparison of experimental data with results of some drying models for regularly shaped products

    NASA Astrophysics Data System (ADS)

    Kaya, Ahmet; Aydın, Orhan; Dincer, Ibrahim

    2010-05-01

    This paper presents an experimental and theoretical investigation of drying of moist slab, cylinder and spherical products to study dimensionless moisture content distributions and their comparisons. Experimental study includes the measurement of the moisture content distributions of slab and cylindrical carrot, slab and cylindrical pumpkin and spherical blueberry during drying at various temperatures (e.g., 30, 40, 50 and 60°C) at specific constant velocity ( U = 1 m/s) and the relative humidity φ = 30%. In theoretical analysis, two moisture transfer models are used to determine drying process parameters (e.g., drying coefficient and lag factor) and moisture transfer parameters (e.g., moisture diffusivity and moisture transfer coefficient), and to calculate the dimensionless moisture content distributions. The calculated results are then compared with the experimental moisture data. A considerably high agreement is obtained between the calculations and experimental measurements for the cases considered. The effective diffusivity values were evaluated between 0.741 × 10-5 and 5.981 × 10-5 m2/h for slab products, 0.818 × 10-5 and 6.287 × 10-5 m2/h for cylindrical products and 1.213 × 10-7 and 7.589 × 10-7 m2/h spherical products using the Model-I and 0.316 × 10-5-5.072 × 10-5 m2/h for slab products, 0.580 × 10-5-9.587 × 10-5 m2/h for cylindrical products and 1.408 × 10-7-13.913 × 10-7 m2/h spherical products using the Model-II.

  10. SWAP Modeling Results of Monitored Soil Water Moisture Data of Irrigation Experimental Study

    NASA Astrophysics Data System (ADS)

    Zeiliger, A.; Garsia-Orenes, F.; van den Elsen, E.; Mataix-Solera, J.; Semenov, V.

    2009-04-01

    In arid and semiarid zones of the Mediterranean regions a shortage of fresh water resources constitutes some time dramatic problem. In these regions with growing population and the scarce of rainfall irregularity in time during growing season an efficient use of water irrigation became a main challenge for future extensive agriculture development. In the frame of FP6 Water-Reuse project 516731 project a special field experimentation has been carried out in Alicante Region of Spain (Location UTM X: 693.809, Y: 4.279.922, Z: 626) on a Sandy Typic Xerofkuvent (Soil Survey Staff, 1999), Calcaric Fluvisol (WRB, FAO, 1989). with aim to investigate water regime in water repellent soils under irrigation of vine Vitus Labrusca. During field experimentation from 2006 till 2008 on 9 plots, there the same regime of irrigation water application was maintained, a monitoring of weather parameters was done by automatic meteorological station as well as a monitoring of soil water moisture was done by set of data-loggers and TDR-soil moisture sensors ECO-2 installed at different depts. SWAP model was used to simulate water regime of irrigated plots. Empirical coefficients of van Genuchten-Mualem's equations were calculated by pedotransfer functions derived from HYPRES data base using measured values of bulk density, organic matter content and soil texture. Testing of validity of the use of estimated curves was done by comparison with unsaturated soil hydraulic parameters of water retention and hydraulic conductivity measured in vitro by Wind's method on soil samples. Calibration of SWAP model for each plot was done on measured soil moisture data of irrigation events by adjusting a value of saturated hydraulic coefficient. Verification of the SWAP model was done by full range of experimental data. Similarity and non-similarity of the water regime at experimental plots as well as results of verification of SWAP model were analyzed

  11. AFM Investigation of Liquid-Filled Polymer Microcapsules Elasticity.

    PubMed

    Sarrazin, Baptiste; Tsapis, Nicolas; Mousnier, Ludivine; Taulier, Nicolas; Urbach, Wladimir; Guenoun, Patrick

    2016-05-10

    Elasticity of polymer microcapsules (MCs) filled with a liquid fluorinated core is studied by atomic force microscopy (AFM). Accurately characterized spherical tips are employed to obtain the Young's moduli of MCs having four different shell thicknesses. We show that those moduli are effective ones because the samples are composites. The strong decrease of the effective MC elasticity (from 3.0 to 0.1 GPa) as the shell thickness decreases (from 200 to 10 nm) is analyzed using a novel numerical approach. This model describes the evolution of the elasticity of a coated half-space according to the contact radius, the thickness of the film, and the elastic moduli of bulk materials. This numerical model is consistent with the experimental data and allows simulating the elastic behavior of MCs at high frequencies (5 MHz). While the quasi-static elasticity of the MCs is found to be very dependent on the shell thickness, the high frequency (5 MHz) elastic behavior of the core leads to a stable behavior of the MCs (from 2.5 to 3 GPa according to the shell thickness). Finally, the effect of thermal annealing on the MCs elasticity is investigated. The Young's modulus is found to decrease because of the reduction of the shell thickness due to the loss of the polymer. PMID:27058449

  12. Seeded free electron laser operating with two colors: Comments on experimental results

    NASA Astrophysics Data System (ADS)

    Carpanese, M.; Ciocci, F.; Dattoli, G.; Petralia, A.; Petrillo, V.; Torre, A.

    2016-05-01

    Free electron lasers operating with two colors are promising devices for applications. The relevant modelization has provided a good understanding of the underlying physics. In this paper we present an analysis of the experimental results obtained at SPARC_LAB concerning seeded two-colors free electron laser (FEL) operation. The use of an ad hoc developed semi-analytical model based on the small-signal FEL integral equation reproduces most of the observed phenomenology. The paper discusses the reliability of the proposed method, the range of validity and its possible improvement.

  13. Comparison of Theoretical Stresses and Deflections of Multicell Wings with Experimental Results Obtained from Plastic Models

    NASA Technical Reports Server (NTRS)

    Zender, George W

    1956-01-01

    The experimental deflections and stresses of six plastic multicell-wing models of unswept, delta, and swept plan form are presented and compared with previously published theoretical results obtained by the electrical analog method. The comparisons indicate that the theory is reliable except for the evaluation of stresses in the vicinity of the leading edge of delta wings and the leading and trailing edges of swept wings. The stresses in these regions are questionable, apparently because of simplifications employed in idealizing the actual structure for theoretical purposes and because of local effects of concentrated loads.

  14. Experimental results of a deflected thrust V/STOL nozzle research program

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Johns, A. L.

    1983-01-01

    Four deflected thrust nozzle concepts, designed to operate at the low pressure ratio typical of high bypass-ratio turbofan engines for medium speed (subsonic) V/STOL aircraft, were studied. Maps of overall performance characteristics and exit velocity distributions are used to highlight similarities and differences between the four concepts. Analytically determined secondary flows at the exit of a 90 deg circular pipe bend are compared with the experimental results from the more complex three dimensional geometries. The relative impact of total-pressure losses and secondary flows on nozzle thrust coefficient is addressed by numerical integration of exit velocity measurements. Previously announced in STAR as N83-25657

  15. Experimental results of a deflected thrust V/STOL nozzle research program

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Johns, A. L.

    1983-01-01

    Four deflected thrust nozzle concepts, designed to operate at the low pressure ratio typical of high bypass-ratio turbofan engines for medium speed (subsonic) V/STOL aircraft, were studied. Maps of overall performance characteristics and exit velocity distributions are used to highlight similarities and differences between the four concepts. Analytically determined secondary flows at the exit of a 90 deg circular pipe bend are compared with the experimental results from the more complex three dimensional geometries. The relative impact of total-pressure losses and secondary flows on nozzle thrust coefficient is addressed by numerical integration of exit velocity measurements.

  16. Development of X-ray microcalorimeters based on SOI technology and experimental results

    NASA Astrophysics Data System (ADS)

    Szeflinski, V.; Aliane, A.; De Moro, F.; Pigot, C.; Sauvageot, J.-L.; Agnèse, P.; Gasse, A.; Ribot, H.; Gremion, E.; De La Broise, X.; Navick, X. F.

    2009-10-01

    We are developing an X-ray spectro-imaging detector at cryogenic temperature (<100 mK) for next space generation missions, using silicon technology. Each pixel of this array detector is made of a tantalum absorber bonded by indium bump hybridization, to an implanted and high-temperature diffused silicon thermistor. The thermo-mechanical link, provided by the indium bump hybridization, is being improved in terms of thermal capacitance. We present the state of development and experimental results on this new generation of X-ray microcalorimeters.

  17. Experimental and Theoretical Results in Output-Trajectory Redesign for Flexible Structures

    NASA Technical Reports Server (NTRS)

    Dewey, J. S.; Devasia, Santosh

    1996-01-01

    In this paper we study the optimal redesign of output trajectory for linear invertible systems. This is particularly important for tracking control of flexible structures because the input-state trajectories that achieve the required output may cause excessive vibrations in the structure. A trade-off is then required between tracking and vibrations reduction. We pose and solve this problem as the minimization of a quadratic cost function. The theory is developed and applied to the output tracking of a flexible structure and experimental results are presented.

  18. Active vibration absorber for the CSI evolutionary model - Design and experimental results. [Controls Structures Interaction

    NASA Technical Reports Server (NTRS)

    Bruner, Anne M.; Belvin, W. Keith; Horta, Lucas G.; Juang, Jer-Nan

    1991-01-01

    The development of control of large flexible structures technology must include practical demonstrations to aid in the understanding and characterization of controlled structures in space. To support this effort, a testbed facility has been developed to study practical implementation of new control technologies under realistic conditions. The paper discusses the design of a second order, acceleration feedback controller which acts as an active vibration absorber. This controller provides guaranteed stability margins for collocated sensor/actuator pairs in the absence of sensor/actuator dynamics and computational time delay. Experimental results in the presence of these factors are presented and discussed. The robustness of this design under model uncertainty is demonstrated.

  19. Recent experimental results from a long-pulse J-band relativistic klystron amplifier developmental effort

    SciTech Connect

    Kato, K.G.; Crouch, D.D.; Sar, D.R.; Speciale, R.A.; Carlsten, B.E.; Fazio, M.V.; Haynes, W.B.; Stringfield, R.M.

    1994-12-31

    Recent experimental results, supporting simulations, and design modeling are presented from a developmental effort to a produce a long pulse ({approximately}1{mu}s) J-band (5.85-8.2 GHz) relativistic klystron amplifier (RKA) of the high current NRL genealogy. This RKA is designed to operate at approximately 6.6 GHz, with a desired RF output {approximately}700 MW. Conversion of electron beam energy to microwave energy is obtained by a mock magnetically insulated coaxial converter which, in various incarnations, can be made to be either a cavity gap extractor or an inverse cathode.

  20. Experimental Results From the Thermal Energy Storage-1 (TES-1) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Jacqmin, David

    1995-01-01

    The Thermal Energy Storage (TES) experiments are designed to provide data to help researchers understand the long-duration microgravity behavior of thermal energy storage fluoride salts that undergo repeated melting and freezing. Such data, which have never been obtained before, have direct application to space-based solar dynamic power systems. These power systems will store solar energy in a thermal energy salt, such as lithium fluoride (LiF) or a eutectic of lithium fluoride/calcium difluoride (LiF-CaF2) (which melts at a lower temperature). The energy will be stored as the latent heat of fusion when the salt is melted by absorbing solar thermal energy. The stored energy will then be extracted during the shade portion of the orbit, enabling the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes have been developed to predict the performance of a spacebased solar dynamic power system. However, the analytical predictions must be verified experimentally before the analytical results can be used for future space power design applications. Four TES flight experiments will be used to obtain the needed experimental data. This article focuses on the flight results from the first experiment, TES-1, in comparison to the predicted results from the Thermal Energy Storage Simulation (TESSIM) analytical computer code.

  1. Impulsivity in Multiplayer Online Battle Arena Gamers: Preliminary Results on Experimental and Self-Report Measures.

    PubMed

    Nuyens, Filip; Deleuze, Jory; Maurage, Pierre; Griffiths, Mark D; Kuss, Daria J; Billieux, Joël

    2016-06-01

    Background and aims Multiplayer Online Battle Arena (MOBA) games have become the most popular type of video games played worldwide, superseding the playing of Massively Multiplayer Online Role-Playing Games and First-Person Shooter games. However, empirical studies focusing on the use and abuse of MOBA games are still very limited, particularly regarding impulsivity, which is an indicator of addictive states but has not yet been explored in MOBA games. In this context, the objective of the present study is to explore the associations between impulsivity and symptoms of addictive use of MOBA games in a sample of highly involved League of Legends (LoL, currently the most popular MOBA game) gamers. Methods Thirty-six LoL gamers were recruited and completed both experimental (Single Key Impulsivity Paradigm) and self-reported impulsivity assessments (s-UPPS-P Impulsive Behavior Scale, Barratt Impulsiveness Scale), in addition to an assessment of problematic video game use (Problematic Online Gaming Questionnaire). Results Results showed links between impulsivity-related constructs and signs of excessive MOBA game involvement. Findings indicated that impaired ability to postpone rewards in an experimental laboratory task was strongly related to problematic patterns of MOBA game involvement. Although less consistent, several associations were also found between self-reported impulsivity traits and signs of excessive MOBA game involvement. Conclusions Despite these results are preliminary and based upon a small (self-selected) sample, the present study highlights potential psychological factors related to the addictive use of MOBA games. PMID:27156376

  2. Investigation of sonar transponders for offshore wind farms: modeling approach, experimental setup, and results.

    PubMed

    Fricke, Moritz B; Rolfes, Raimund

    2013-11-01

    The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed. PMID:24180764

  3. Femtosecond laser for glaucoma treatment: the comparison between simulation and experimentation results on ocular tissue removal

    NASA Astrophysics Data System (ADS)

    Hou, Dong Xia; Ngoi, Bryan K. A.; Hoh, Sek Tien; Koh, Lee Huat K.; Deng, Yuan Zi

    2005-04-01

    In ophthalmology, the use of femtosecond lasers is receiving more attention than ever due to its extremely high intensity and ultra short pulse duration. It opens the highly beneficial possibilities for minimized side effects during surgery process, and one of the specific areas is laser surgery in glaucoma treatment. However, the sophisticated femtosecond laser-ocular tissue interaction mechanism hampers the clinical application of femtosecond laser to treat glaucoma. The potential contribution in this work lies in the fact, that this is the first time a modified moving breakdown theory is applied, which is appropriate for femtosecond time scale, to analyze femtosecond laser-ocular tissue interaction mechanism. Based on this theory, energy deposition and corresponding thermal increase are studied by both simulation and experimentation. A simulation model was developed using Matlab software, and the simulation result was validated through in-vitro laser-tissue interaction experiment using pig iris. By comparing the theoretical and experimental results, it is shown that femtosecond laser can obtain determined ocular tissue removal, and the thermal damage is evidently reduced. This result provides a promising potential for femtosecond laser in glaucoma treatment.

  4. A Comparison of Experimental and Theoretical Results for Labyrinth Gas Seals. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph Kirk

    1987-01-01

    The basic equations are derived for a two control volume model for compressible flow in a labyrinth seal. The flow is assumed to be completely turbulent and isoenergetic. The wall friction factors are determined using the Blasius formula. Jet flow theory is used for the calculation of the recirculation velocity in the cavity. Linearized zeroth and first order perturbation equations are developed for small motion about a centered position by an expansion in the eccentricity ratio. The zeroth order pressure distribution is found by satisfying the leakage equation. The circumferential velocity distribution is determined by satisfying the momentum equations. The first order equations are solved by a separation of variable solution. Integration of the resultant pressure distribution along and around the seal defines the reaction force developed by the seal and the corresponding dynamic coefficients. The results of this analysis are compared to experimental test results.

  5. Heavy vehicle suspension parameters identification and estimation of vertical forces: experimental results

    NASA Astrophysics Data System (ADS)

    Imine, H.; Madani, T.

    2015-02-01

    The aim of the present work is to estimate the vertical forces of heavy vehicle and identify the unknown dynamic parameters using sliding mode observer approach. This observation needs a good knowledge of dynamic parameters such as damping coefficient, spring stiffness, etc. In this paper, suspension stiffness and unsprung masses have been identified. Experimental results carried out on an instrumented tractor have been presented in order to show the quality of the state observation, parameters identification and force estimation. These estimation results are then compared to the measured one coming from the sensors installed in the tractor. Many scenarios have been tested. In this paper, the results coming from zigzag test have been shown and commented.

  6. Experimental results for a two-dimensional supersonic inlet used as a thrust deflecting nozzle

    NASA Technical Reports Server (NTRS)

    Johns, Albert L.; Burstadt, Paul L.

    1984-01-01

    Nearly all supersonic V/STOL aircraft concepts are dependent on the thrust deflecting capability of a nozzle. In one unique concept, referred to as the reverse flow dual fan, not only is there a thrust deflecting nozzle for the fan and core engine exit flow, but because of the way the propulsion system operates during vertical takeoff and landing, the supersonic inlet is also used as a thrust deflecting nozzle. This paper presents results of an experimental study to evaluate the performance of a supersonic inlet used as a thrust deflecting nozzle for this reverse flow dual fan concept. Results are presented in terms of nozzle thrust coefficient and thrust vector angle for a number of inlet/nozzle configurations. Flow visualization and nozzle exit flow survey results are also shown.

  7. Atomic force microscopy combined with optical tweezers (AFM/OT)

    NASA Astrophysics Data System (ADS)

    Pierini, F.; Zembrzycki, K.; Nakielski, P.; Pawłowska, S.; Kowalewski, T. A.

    2016-02-01

    The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.

  8. Nanomechanical probing of soft matter through hydrophobic AFM tips fabricated by two-photon polymerization

    NASA Astrophysics Data System (ADS)

    Suriano, Raffaella; Zandrini, Tommaso; De Marco, Carmela; Osellame, Roberto; Turri, Stefano; Bragheri, Francesca

    2016-04-01

    Atomic force microscopy (AFM) nanoindentation of soft materials is a powerful tool for probing mechanical properties of biomaterials. Though many results have been reported in this field over the last decade, adhesion forces between the tip and the sample hinder the elastic modulus measurement when hydrophilic soft samples are investigated. Here, two-photon polymerization (2PP) technology was used to fabricate hydrophobic perfluoropolyether-based AFM tips. The hydrophobic 2PP tips allowed us to overcome the limitations of commercial and functionalized tips as well as to successfully measure the elastic modulus of medically relevant soft materials in air. Our results obtained in the characterization of poly(dimethyl siloxane) and polyethylene glycol hydrogels showed lower adhesion forces over a larger measurement range when compared to measurements performed with commercial tips. The elastic moduli measured by means of hydrophobic 2PP AFM tips were also found to be comparable to those obtained using conventional techniques for macroscopic samples. We successfully showed that the hydrophobic AFM tips developed by this highly versatile technology enable the study of mechanical properties of soft matter, benefiting from reduced sample-tip interactions, and a custom-made shape and dimension of the tips.

  9. AFM tip characterization by using FFT filtered images of step structures.

    PubMed

    Yan, Yongda; Xue, Bo; Hu, Zhenjiang; Zhao, Xuesen

    2016-01-01

    The measurement resolution of an atomic force microscope (AFM) is largely dependent on the radius of the tip. Meanwhile, when using AFM to study nanoscale surface properties, the value of the tip radius is needed in calculations. As such, estimation of the tip radius is important for analyzing results taken using an AFM. In this study, a geometrical model created by scanning a step structure with an AFM tip was developed. The tip was assumed to have a hemispherical cone shape. Profiles simulated by tips with different scanning radii were calculated by fast Fourier transform (FFT). By analyzing the influence of tip radius variation on the spectra of simulated profiles, it was found that low-frequency harmonics were more susceptible, and that the relationship between the tip radius and the low-frequency harmonic amplitude of the step structure varied monotonically. Based on this regularity, we developed a new method to characterize the radius of the hemispherical tip. The tip radii estimated with this approach were comparable to the results obtained using scanning electron microscope imaging and blind reconstruction methods. PMID:26517548

  10. Nanomechanical probing of soft matter through hydrophobic AFM tips fabricated by two-photon polymerization.

    PubMed

    Suriano, Raffaella; Zandrini, Tommaso; De Marco, Carmela; Osellame, Roberto; Turri, Stefano; Bragheri, Francesca

    2016-04-15

    Atomic force microscopy (AFM) nanoindentation of soft materials is a powerful tool for probing mechanical properties of biomaterials. Though many results have been reported in this field over the last decade, adhesion forces between the tip and the sample hinder the elastic modulus measurement when hydrophilic soft samples are investigated. Here, two-photon polymerization (2PP) technology was used to fabricate hydrophobic perfluoropolyether-based AFM tips. The hydrophobic 2PP tips allowed us to overcome the limitations of commercial and functionalized tips as well as to successfully measure the elastic modulus of medically relevant soft materials in air. Our results obtained in the characterization of poly(dimethyl siloxane) and polyethylene glycol hydrogels showed lower adhesion forces over a larger measurement range when compared to measurements performed with commercial tips. The elastic moduli measured by means of hydrophobic 2PP AFM tips were also found to be comparable to those obtained using conventional techniques for macroscopic samples. We successfully showed that the hydrophobic AFM tips developed by this highly versatile technology enable the study of mechanical properties of soft matter, benefiting from reduced sample-tip interactions, and a custom-made shape and dimension of the tips. PMID:26926558

  11. An active reference spring array for in-situ calibration of the normal spring constant of AFM cantilevers

    NASA Astrophysics Data System (ADS)

    Gao, S.; Brand, U.; Hahn, S.; Hiller, K.

    2015-05-01

    In this paper the concept of an "active reference spring array (ARSA)" for the AFM cantilever normal spring constant calibration is proposed. The ARSA with nominal stiffness varying from 0.4 N/m to 150 N/m will be available on these arrays with the aim to calibrate the normal stiffness of cantilevers ranging from 0.04 N/m to 1500 N/m. The fabrication process of the MEMS ARSA on basis of the Bonding Deep RIE technology developed at Chemnitz University of Technology is reported. A first characterization of the MEMS and the traceable determination of the stiffness of the MEMS suspending system have been realized. First experimental results compare very well with the Finite Element (FE) simulation of the numerical design, and prove the feasibility of the proposed concept.

  12. Nanoscale structural features determined by AFM for single virus particles.

    PubMed

    Chen, Shu-wen W; Odorico, Michael; Meillan, Matthieu; Vellutini, Luc; Teulon, Jean-Marie; Parot, Pierre; Bennetau, Bernard; Pellequer, Jean-Luc

    2013-11-21

    In this work, we propose "single-image analysis", as opposed to multi-image averaging, for extracting valuable information from AFM images of single bio-particles. This approach allows us to study molecular systems imaged by AFM under general circumstances without restrictions on their structural forms. As feature exhibition is a resolution correlation, we have performed AFM imaging on surfaces of tobacco mosaic virus (TMV) to demonstrate variations of structural patterns with probing resolution. Two AFM images were acquired with the same tip at different probing resolutions in terms of pixel width, i.e., 1.95 and 0.49 nm per pixel. For assessment, we have constructed an in silico topograph based on the three-dimensional crystal structure of TMV as a reference. The prominent artifacts observed in the AFM-determined shape of TMV were attributed to tip convolutions. The width of TMV rod was systematically overestimated by ~10 nm at both probing resolutions of AFM. Nevertheless, the effects of tip convolution were less severe in vertical orientation so that the estimated height of TMV by AFM imaging was in close agreement with the in silico X-ray topograph. Using dedicated image processing algorithms, we found that at low resolution (i.e., 1.95 nm per pixel), the extracted surface features of TMV can be interpreted as a partial or full helical repeat (three complete turns with ~7.0 nm in length), while individual protein subunits (~2.5 nm) were perceivable only at high resolution. The present study shows that the scales of revealed structural features in AFM images are subject to both probing resolution and processing algorithms for image analysis. PMID:24056758

  13. The Conductance of Nanotubes Deformed by the AFM Tip

    NASA Technical Reports Server (NTRS)

    Svizhenko, Alexei; Maiti, Amitesh; Anantram, M. P.

    2003-01-01

    The conductance drop under AFM-tip deformation can be explained by stretching of the tube length. NT sensors can be built utilizing uniform stretching. Single sp3 bond cross section cannot block electrons, because another conducting path may exist. AFM tip which forms sp3 bonds with the tube will decrease conductance. In the "table experiment" a conductance drop of 2 orders of magnitude happened only after some bonds were broken.

  14. Fuel-rich, catalytic reaction experimental results. [fuel development for high-speed civil transport aircraft

    NASA Technical Reports Server (NTRS)

    Rollbuhler, Jim

    1991-01-01

    Future aeropropulsion gas turbine combustion requirements call for operating at very high inlet temperatures, pressures, and large temperature rises. At the same time, the combustion process is to have minimum pollution effects on the environment. Aircraft gas turbine engines utilize liquid hydrocarbon fuels which are difficult to uniformly atomize and mix with combustion air. An approach for minimizing fuel related problems is to transform the liquid fuel into gaseous form prior to the completion of the combustion process. Experimentally obtained results are presented for vaporizing and partially oxidizing a liquid hydrocarbon fuel into burnable gaseous components. The presented experimental data show that 1200 to 1300 K reaction product gas, rich in hydrogen, carbon monoxide, and light-end hydrocarbons, is formed when flowing 0.3 to 0.6 fuel to air mixes through a catalyst reactor. The reaction temperatures are kept low enough that nitrogen oxides and carbon particles (soot) do not form. Results are reported for tests using different catalyst types and configurations, mass flowrates, input temperatures, and fuel to air ratios.

  15. Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 1. Experimental results

    NASA Astrophysics Data System (ADS)

    Queloz, Pierre; Bertuzzo, Enrico; Carraro, Luca; Botter, Gianluca; Miglietta, Franco; Rao, P. S. C.; Rinaldo, Andrea

    2015-04-01

    This paper reports about the experimental evidence collected on the transport of five fluorobenzoate tracers injected under controlled conditions in a vegetated hydrologic volume, a large lysimeter (fitted with load cells, sampling ports, and an underground chamber) where two willows prompting large evapotranspiration fluxes had been grown. The relevance of the study lies in the direct and indirect measures of the ways in which hydrologic fluxes, in this case, evapotranspiration from the upper surface and discharge from the bottom drainage, sample water and solutes in storage at different times under variable hydrologic forcings. Methods involve the accurate control of hydrologic inputs and outputs and a large number of suitable chemical analyses of water samples in discharge waters. Mass extraction from biomass has also been performed ex post. The results of the 2 year long experiment established that our initial premises on the tracers' behavior, known to be sorption-free under saturated conditions which we verified in column leaching tests, were unsuitable as large differences in mass recovery appeared. Issues on reactivity thus arose and were addressed in the paper, in this case attributed to microbial degradation and solute plant uptake. Our results suggest previously unknown features of fluorobenzoate compounds as hydrologic tracers, potentially interesting for catchment studies owing to their suitability for distinguishable multiple injections, and an outlook on direct experimental closures of mass balance in hydrologic transport volumes involving fluxes that are likely to sample differently stored water and solutes.

  16. Comparison of experimental and analytical results for free vibration of laminated composite plates

    SciTech Connect

    Maryuama, Koichi; Narita, Yoshihiro; Ichinomiya, Osamu

    1995-11-01

    Fibrous composite materials are being increasingly employed in high performance structures, including pressured vessel and piping applications. These materials are usually used in the form of laminated flat or curved plates, and the understanding of natural frequencies and the corresponding mode shapes is essential to a reliable structural design. Although many references have been published on analytical study of laminated composite plates, a limited number of experimental studies have appeared for dealing with vibration characteristics of the plates. This paper presents both experimental and analytical results for the problems. In the experiment, the holographic interferometry is used to measure the resonant frequencies and corresponding mode shapes of six-layered CFRP (carbon fiber reinforced plastic) composite plates. The material constants of a lamina are calculated from fiber and matrix material constants by using some different composite rules. With the calculated constants, the natural frequencies of the laminated CFRP plates are theoretically determined by the Ritz method. From the comparison of two sets of the results, the effect of choosing different composite rules is discussed in the vibration study of laminated composite plates.

  17. Tilted wheel satellite attitude control with air-bearing table experimental results

    NASA Astrophysics Data System (ADS)

    Inumoh, Lawrence O.; Forshaw, Jason L.; Horri, Nadjim M.

    2015-12-01

    Gyroscopic actuators for satellite control have attracted significant research interest over the years, but their viability for the control of small satellites has only recently started to become clear. Research on variable speed gyroscopic actuators has long been focused on single gimbal actuators; double gimbal actuators typically operate at constant wheel spin rate and allow tilt angle ranges far larger than the ranges needed to operate most satellite missions. This research examines a tilted wheel, a newly proposed type of inertial actuator that can generate torques in all three principal axes of a rigid satellite using a spinning wheel and a double tilt mechanism. The tilt mechanism tilts the angular momentum vector about two axes providing two degree of freedom control, while variation of the wheel speed provides the third. The equations of motion of the system lead to a singularity-free system during nominal operation avoiding the need for complex steering logic. This paper describes the hardware design of the tilted wheel and the experimental setup behind both standalone and spherical air-bearing tables used to test it. Experimental results from the air bearing table are provided with the results depicting the high performance capabilities of the proposed actuator in torque generation.

  18. Experimental Impeller Fragmentation of Iliocaval Thrombosis Under Tulip Filter Protection: Preliminary Results

    SciTech Connect

    Schmitz-Rode, Thomas; Vorwerk, Dierk; Schuermann, Karl; Guenther, Rolf W.

    1996-04-15

    Purpose: To assess the efficacy of catheter fragmentation of massive caval thrombosis and of filter protection against procedure-related pulmonary embolism. Methods: In 10 sheep, a self-expanding tulip-shaped filter made from Wallstent mesh (diameter 25 mm) was introduced from the right jugular approach into the proximal inferior vena cava. Experimentally induced massive iliocaval thrombosis was fragmented by an impeller catheter (expanded diameter 14 mm), which was advanced coaxially through the sheath of the expanded filter. Post-procedural cavography and pulmonary angiography were performed to document the extent of caval recanalization and pulmonary embolism. Results: In all cases, impeller fragmentation cleared the inferior vena cava and the iliac veins of thrombi completely. Fragments washed downstream were trapped in the filter. In two of the first cases, parts of the clots caused pulmonary embolism before the filter was in place. Further events were avoided by a modification of the experimental setup. Except for some small peripheral perfusion defects in two cases, pulmonary angiograms did not show any incidence of pulmonary embolism. Conclusion: Our preliminary results suggest that impeller fragmentation of iliocaval thrombi under tulip filter protection is effective and does not cause significant pulmonary embolism.

  19. Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

    PubMed Central

    Jang, Neo W.; Zakrzewski, Aaron; Rossi, Christina; Dalecki, Diane; Gracewski, Sheryl

    2011-01-01

    Motivated by various clinical applications of ultrasound contrast agents within blood vessels, the natural frequencies of two bubbles in a compliant tube are studied analytically, numerically, and experimentally. A lumped parameter model for a five degree of freedom system was developed, accounting for the compliance of the tube and coupled response of the two bubbles. The results were compared to those produced by two different simulation methods: (1) an axisymmetric coupled boundary element and finite element code previously used to investigate the response of a single bubble in a compliant tube and (2) finite element models developed in comsol Multiphysics. For the simplified case of two bubbles in a rigid tube, the lumped parameter model predicts two frequencies for in- and out-of-phase oscillations, in good agreement with both numerical simulation and experimental results. For two bubbles in a compliant tube, the lumped parameter model predicts four nonzero frequencies, each asymptotically converging to expected values in the rigid and compliant limits of the tube material. PMID:22088008

  20. Epistemology and expectations survey about experimental physics: Development and initial results

    NASA Astrophysics Data System (ADS)

    Zwickl, Benjamin M.; Hirokawa, Takako; Finkelstein, Noah; Lewandowski, H. J.

    2014-06-01

    In response to national calls to better align physics laboratory courses with the way physicists engage in research, we have developed an epistemology and expectations survey to assess how students perceive the nature of physics experiments in the contexts of laboratory courses and the professional research laboratory. The Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS) evaluates students' epistemology at the beginning and end of a semester. Students respond to paired questions about how they personally perceive doing experiments in laboratory courses and how they perceive an experimental physicist might respond regarding their research. Also, at the end of the semester, the E-CLASS assesses a third dimension of laboratory instruction, students' reflections on their course's expectations for earning a good grade. By basing survey statements on widely embraced learning goals and common critiques of teaching labs, the E-CLASS serves as an assessment tool for lab courses across the undergraduate curriculum and as a tool for physics education research. We present the development, evidence of validation, and initial formative assessment results from a sample that includes 45 classes at 20 institutions. We also discuss feedback from instructors and reflect on the challenges of large-scale online administration and distribution of results.

  1. Direct electrochemical and AFM detection of amyloid-β peptide aggregation on basal plane HOPG

    NASA Astrophysics Data System (ADS)

    Lopes, Paula; Xu, Meng; Zhang, Min; Zhou, Ting; Yang, Yanlian; Wang, Chen; Ferapontova, Elena E.

    2014-06-01

    Amyloidogenesis is associated with more than 30 human diseases, including Alzheimer's which is related to aggregation of β-amyloid peptide (Aβ). Here, consecutive stages of Aβ42 aggregation and amyloid fibril formation were followed electrochemically via oxidation of tyrosines in Aβ42 adsorbed on the basal plane graphite electrode and directly correlated with Aβ42 morphological changes observed by atomic force microscopy of the same substrate. The results offer new tools for analysis of mechanisms of Aβ aggregation.Amyloidogenesis is associated with more than 30 human diseases, including Alzheimer's which is related to aggregation of β-amyloid peptide (Aβ). Here, consecutive stages of Aβ42 aggregation and amyloid fibril formation were followed electrochemically via oxidation of tyrosines in Aβ42 adsorbed on the basal plane graphite electrode and directly correlated with Aβ42 morphological changes observed by atomic force microscopy of the same substrate. The results offer new tools for analysis of mechanisms of Aβ aggregation. Electronic supplementary information (ESI) available: Experimental details: procedures for Aβ42 aggregation and electrode modification, DPV/AFM measurements and analysis. See DOI: 10.1039/c4nr02413c

  2. Surface-enhanced spectroscopy on plasmonic oligomers assembled by AFM nanoxerography.

    PubMed

    Moutet, Pierre; Sangeetha, Neralagatta M; Ressier, Laurence; Vilar-Vidal, Noelia; Comesaña-Hermo, Miguel; Ravaine, Serge; Vallée, Renaud A L; Gabudean, Ana Maria; Astilean, Simion; Farcau, Cosmin

    2015-02-01

    Surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from individual plasmonic oligomers are investigated by confocal Raman micro-spectroscopy and time-resolved fluorescence microscopy coupled to steady state micro-spectroscopy. The nanoparticle (NP) oligomers are made of either ligand protected Au or Au@SiO2 core-shell colloidal NPs, which were assembled into ordered arrays by atomic force microscopy (AFM) nanoxerography. A strong dependence of the SERS emission on the polarization of incident light relative to the specific geometry of the plasmonic oligomer was observed. The SEF studies, performed on a large collection of NP oligomers of various known configurations showed interesting fluorophore decay rate modification and red-shift of the emission spectra. The experimental results are analyzed theoretically by employing finite-difference time-domain (FDTD) simulations on equivalent realistic structures, within the local density of optical states (LDOS) framework. The presented results, together with the proven potential of the LDOS approach as a useful common tool for analyzing both SERS and SEF effects further the general understanding of plasmon-related phenomena in nanoparticle oligomers. PMID:25553777

  3. Probing Nanoscale Surface Enhanced Raman Scattering Fluctuation Dynamics using Correlated AFM and Confocal Ultramicroscopy

    SciTech Connect

    Suh, Yung D.; Schenter, Gregory K.; Zhu, Leyun; Lu, H PETER.

    2003-10-01

    We have studied the laser-excitation-intensity-dependent and Ag-nanocluster interstitial-site-dependent SERS intensity fluctuations under low molecule surface coverage of rhodamine 6G and cytochrome c. a new two-channel photon time-stamping system coupled with atomic force microscopic (AFM), Raman spectroscopic, and imaging microscopy was developed and applied to record Raman intensity fluctuation trajectories at sub-microsecond resolution correlated with in-situ characterization of the nanoparticle clusters. Our experimental results suggest that the nanoconfinement of the local electromagnetic-field enhancement and the interaction of the local field with the molecules, presumably under rotational motions, result in nano-Raman fluctuations. The SERS spectral fluctuation was pertinent to the nanoscale local enhancement and local interaction of the molecules with the surface when the number of molecules to contribute the microscopic Raman signal collected from a diffraction-limited focus spot. The SERS fluctuation dynamics were both photo-induced and spontaneous for rhodamine 6G, but only the photo-induced interstitial sites with heterogeneous geometries. To interpret the observed nano-SERS fluctuation dynamics, we used computer simulation of optical multiple scattering, based on multi-sphere scattering Mie theory, and rotational diffusion of molecules at an interstitial site, based on a random walk in orientation space.

  4. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM.

    PubMed

    Zhang, Wen; Stack, Andrew G; Chen, Yongsheng

    2011-02-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite (α-Fe(2)O(3)) and corundum (α-Al(2)O(3)) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3±0.7nN to 0.8±0.4nN as hematite NPs increased from 26nm to 98nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson-Kendall-Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed. PMID:20932723

  5. Forced Unfolding of the Coiled-Coils of Fibrinogen by Single-Molecule AFM

    NASA Astrophysics Data System (ADS)

    Brown, Andre; Litvinov, Rustem; Discher, Dennis; Weisel, John

    2007-03-01

    A blood clot needs to have the right degree of stiffness and plasticity for hemostasis, but the origin of these mechanical properties is unknown. Here we report the first measurements using single molecule atomic force microscopy (AFM) to study the forced unfolding of fibrinogen to begin addressing this problem. To generate longer reproducible curves than are possible using monomer, factor XIIIa cross-linked, single chain fibrinogen oligomers were used. When extended under force, these oligomers showed sawtooth shaped force-extension patterns characteristic of unfolding proteins with a peak-to-peak separation of approximately 26 nm, consistent with the independent unfolding of the coiled-coils. These results were then reproduced using a Monte Carlo simulation with parameters in the same range as those previously used for unfolding globular domains. In particular, we found that the refolding time was negligible on experimental time and force scales in contrast to previous work on simpler coiled-coils. We suggest that this difference may be due to fibrinogen's structurally and topologically more complex coiled-coils and that an interaction between the alpha C and central domains may be involved. These results suggest a new functional property of fibrinogen and that the coiled-coil is more than a passive structural element of this molecule.

  6. Interaction force measurement between E. coli cells and nanoparticles immobilized surfaces by using AFM

    SciTech Connect

    Zhang, Wen; Chen, Yongsheng

    2011-01-01

    To better understand environmental behaviors of nanoparticles (NPs), we used the atomic force microscopy (AFM) to measure interaction forces between E. coli cells and NPs immobilized on surfaces in an aqueous environment. The results showed that adhesion force strength was significantly influenced by particle size for both hematite ( -Fe2 O3 ) and corundum ( -Al2 O3 ) NPs whereas the effect on the repulsive force was not observed. The adhesion force decreased from 6.3 0.7 nN to 0.8 0.4 nN as hematite NPs increased from 26 nm to 98 nm in diameter. Corundum NPs exhibited a similar dependence of adhesion force on particle size. The Johnson Kendall Roberts (JKR) model was employed to estimate the contact area between E. coli cells and NPs, and based on the JKR model a new model that considers local effective contact area was developed. The prediction of the new model matched the size dependence of adhesion force in experimental results. Size effects on adhesion forces may originate from the difference in local effective contact areas as supported by our model. These findings provide fundamental information for interpreting the environmental behaviors and biological interactions of NPs, which barely have been addressed.

  7. Mode coupling in a hanging-fiber AFM used as a rheological probe

    NASA Astrophysics Data System (ADS)

    Devailly, C.; Laurent, J.; Steinberger, A.; Bellon, L.; Ciliberto, S.

    2014-06-01

    We analyze the advantages and drawbacks of a method which measures the viscosity of liquids at microscales, using a thin glass fiber fixed on the tip of a cantilever of an ultra-low-noise Atomic Force Microscope (AFM). When the fiber is dipped into a liquid, the dissipation of the cantilever-fiber system, which is linked to the liquid viscosity, can be computed from the power spectral density of the thermal fluctuations of the cantilever deflection. The high sensitivity of the AFM allows us to show the existence and to develop a model of the coupling between the dynamics of the fiber and that of the cantilever. This model, which accurately fits the experimental data, gives also more insights into the dynamics of coupled microdevices in a viscous environment.

  8. Experimental and raytrace results for throat-to-throat compound parabolic concentrators

    NASA Technical Reports Server (NTRS)

    Leviton, D. B.; Leitch, J. W.

    1986-01-01

    Compound parabolic concentrators are nonimaging cone-shaped optics with useful angular transmission characteristics. Two cones used throat-to-throat accept radiant flux within one well-defined acceptance angle and redistribute it into another. If the entrance cone is fed with Lambertian flux, the exit cone produces a beam whose half-angle is the exit cone's acceptance angle and whose cross section shows uniform irradiance from near the exit mouth to infinity. (The pair is a beam angle transformer). The design of one pair of cones is discussed, also an experiment to map the irradiance of the emergent beam, and a raytracing program which models the cones fed by Lambertian flux. Experimental results compare favorably with raytrace results.

  9. Experimental Results for a Flapped Natural-laminar-flow Airfoil with High Lift/drag Ratio

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Viken, J. K.; Pfenninger, W.; Beasley, W. D.; Harvey, W. D.

    1984-01-01

    Experimental results have been obtained for a flapped natural-laminar-flow airfoil, NLF(1)-0414F, in the Langley Low-Turbulence Pressure Tunnel. The tests were conducted over a Mach number range from 0.05 to 0.40 and a chord Reynolds number range from about 3.0 x 10(6) to 22.0 x 10(6). The airfoil was designed for 0.70 chord laminar flow on both surfaces at a lift coefficient of 0.40, a Reynolds number of 10.0 x 10(6), and a Mach number of 0.40. A 0.125 chord simple flap was incorporated in the design to increase the low-drag, lift-coefficient range. Results were also obtained for a 0.20 chord split-flap deflected 60 deg.

  10. The Langley Research Center CSI phase-0 evolutionary model testbed-design and experimental results

    NASA Technical Reports Server (NTRS)

    Belvin, W. K.; Horta, Lucas G.; Elliott, K. B.

    1991-01-01

    A testbed for the development of Controls Structures Interaction (CSI) technology is described. The design philosophy, capabilities, and early experimental results are presented to introduce some of the ongoing CSI research at NASA-Langley. The testbed, referred to as the Phase 0 version of the CSI Evolutionary model (CEM), is the first stage of model complexity designed to show the benefits of CSI technology and to identify weaknesses in current capabilities. Early closed loop test results have shown non-model based controllers can provide an order of magnitude increase in damping in the first few flexible vibration modes. Model based controllers for higher performance will need to be robust to model uncertainty as verified by System ID tests. Data are presented that show finite element model predictions of frequency differ from those obtained from tests. Plans are also presented for evolution of the CEM to study integrated controller and structure design as well as multiple payload dynamics.

  11. Non-Shock Initiation of the Plastic Bonded Explosive PBXN-5: Experimental Results

    NASA Astrophysics Data System (ADS)

    Lappo, K. N.; Todd, S. N.; Anderson, M. U.; Vogler, T. J.

    2007-12-01

    The plastic bonded explosive PBXN-5 was studied under impulsive loading experiments to relate impact-induced mechanical damage to the onset of, and the extent of reaction produced. A small diameter projectile generated shock and release conditions at the impact interface, on the microsecond time scale during the initial portion of the impulsive loading. These shock and release wave interactions generate significant damage, resulting in a porous, powder compaction-type initiation behavior. Experimental measurements show an energy threshold for initiation of reaction which relates to impact-induced kinetic energy. These results are implemented in the model development and validation phases of the damage-induced reaction (DMGIR) model, which is used to simulate impact scenarios of explosives, explosive components, and explosive systems.

  12. A three-phase series-parallel resonant converter -- analysis, design, simulation, and experimental results

    SciTech Connect

    Bhat, A.K.S.; Zheng, R.L.

    1996-07-01

    A three-phase dc-to-dc series-parallel resonant converter is proposed /and its operating modes for a 180{degree} wide gating pulse scheme are explained. A detailed analysis of the converter using a constant current model and the Fourier series approach is presented. Based on the analysis, design curves are obtained and a design example of a 1-kW converter is given. SPICE simulation results for the designed converter and experimental results for a 500-W converter are presented to verify the performance of the proposed converter for varying load conditions. The converter operates in lagging power factor (PF) mode for the entire load range and requires a narrow variation in switching frequency, to adequately regulate the output power.

  13. Comparison of results of experimental research with numerical calculations of a model one-sided seal

    NASA Astrophysics Data System (ADS)

    Joachimiak, Damian; Krzyślak, Piotr

    2015-06-01

    Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.

  14. Fault detection, isolation and reconfiguration in FTMP Methods and experimental results. [fault tolerant multiprocessor

    NASA Technical Reports Server (NTRS)

    Lala, J. H.

    1983-01-01

    The Fault-Tolerant Multiprocessor (FTMP) is a highly reliable computer designed to meet a goal of 10 to the -10th failures per hour and built with the objective of flying an active-control transport aircraft. Fault detection, identification, and recovery software is described, and experimental results obtained by injecting faults in the pin level in the FTMP are presented. Over 21,000 faults were injected in the CPU, memory, bus interface circuits, and error detection, masking, and error reporting circuits of one LRU of the multiprocessor. Detection, isolation, and reconfiguration times were recorded for each fault, and the results were found to agree well with earlier assumptions made in reliability modeling.

  15. Experimental results on the design for the APS PID global orbit control system.

    SciTech Connect

    Chung, Y.; Kirchman, J. A.

    1997-12-05

    The Advanced Photon Source third generation synchrotrons light source needs a stabilized particle beam position to produce high brightness and low emittance radiation. Global orbit correction control is introduced and is utilized to satisfy the demanding needs of the accelerator. This paper presents the experimental results for determining an effective and optimal controller to meet the global orbit correction requirements. These requirements include frequency/time domain demands consisting of vibrational noise attenuation, limiting of controller gains for stability and improving the system time response. Experiments were conducted with a digital signal processor implementing various PID sets to make comparisons between simulations and experiments. Measurements at these PID sets supported the results of software simulation.

  16. Low pollution combustor designs for CTOL engines - Results of the Experimental Clean Combustor Program

    NASA Technical Reports Server (NTRS)

    Roberts, R.; Peduzzi, A.; Niedzwiecki, R. W.

    1976-01-01

    The NASA/Pratt & Whitney Aircraft Experimental Clean Combustor Program is a multi-year, major contract effort. Primary program objectives are the generation of combustor technology for development of advanced commercial CTOL engines with lower exhaust emissions than current aircraft and demonstration of this technology in a full-scale JT9D engine in 1976. This paper describes the pollution and performance goals, Phase I and II test results, and the Phase III combustor hardware, pollution sampling techniques, and test plans. Best results were obtained with the Vorbix concept which employs multiple burning zones and improved fuel preparation and distribution. Substantial reductions were achieved in all pollutant categories, meeting the 1979 EPA standards for NOx, THC, and smoke when extrapolated to JT9D cycle conditions. The Vorbix concept additionally demonstrated the capability for acceptable altitude relight and did not appear to have unsolvable durability or exit temperature distribution problems.

  17. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, J. E.

    1975-01-01

    A major phase of the wind energy program is the development of reliable wind turbines for supplying cost-competitive electrical energy. This paper discusses the preliminary results of two projects in this phase of the program. First an experimental 100 kW wind turbine design and its status are reviewed. Also discussed are the results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs. These studies show wind energy costs of 7 to 1.5 c/kWH for wind turbines produced in quantities of 100 to 1000 a year and located at sites having average winds of 12 to 18 mph.

  18. Survey of Experimental Results in High-Contrast Imaging for Future Exoplanet Missions

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Belikov, R.; Cash, W.; Clampin, M.; Glassman, T.; Guyon, O.; Kasdin, N. J.; Kern, B. D.; Lyon, R.; Mawet, D.; Moody, D.; Samuele, R.; Serabyn, E.; Sirbu, D.; Trauger, J.

    2013-01-01

    We present and compare experimental results in high contrast imaging representing the state of the art in coronagraph and starshade technology. These experiments have been undertaken with the goal of demonstrating the capability of detecting Earth-like planets around nearby Sun-like stars. The contrast of an Earth seen in reflected light around a Sun-like star would be about 1.2 x 10(exp -10). Several of the current candidate technologies now yield raw contrasts of 1.0 x 10(exp -9) or better, and so should enable the detection of Earths, assuming a gain in sensitivity in post-processing of a factor of 10. We present results of coronagraph and starshade experiments conducted at visible and infrared wavelengths. Cross-sections of dark fields are directly compared as a function of field angle and bandwidth. The strength and differences of the techniques are compared.

  19. Interfacial Chemical Interactions in the (Alumina/Graphite/Al Alloys) System: Thermodynamic Modeling and Experimental Results

    NASA Astrophysics Data System (ADS)

    Gelbstein, M.; Edry, I.; Froumin, N.; Frage, N.

    2009-04-01

    The stability of alumina-coated graphite couples in liquid Al is investigated in the 1373 to 1573 K temperature range. A thermodynamic model was carried out to determine the mechanisms controlling the couple stability and the effect of alloying Al with high melting point element for instance U (up to 3 at. pct). It was established that the dissolved uranium dose not play any role in the interfacial interactions and that the couple stability is governed by the interactions with Al resulting in the release of gaseous products. The experiments focused on wetting kinetics under conditions allowing for an in-situ reduction of the alumina coating by the liquid Al. The experimental results confirm the predictions of the thermodynamic analysis.

  20. Comparative quantification and statistical analysis of η′ and η precipitates in aluminum alloy AA7075-T651 by TEM and AFM

    SciTech Connect

    Garcia-Garcia, Adrian Luis Dominguez-Lopez, Ivan Lopez-Jimenez, Luis Barceinas-Sanchez, J.D. Oscar

    2014-01-15

    Quantification of nanometric precipitates in metallic alloys has been traditionally performed using transmission electron microscopy, which is nominally a low throughput technique. This work presents a comparative study of quantification of η′ and η precipitates in aluminum alloy AA7075-T651 using transmission electron microscopy (TEM) and non-contact atomic force microscopy (AFM). AFM quantification was compared with 2-D stereological results reported elsewhere. Also, a method was developed, using specialized software, to characterize nanometric size precipitates observed in dark-field TEM micrographs. Statistical analysis of the quantification results from both measurement techniques supports the use of AFM for precipitate characterization. Once the precipitate stoichiometry has been determined by appropriate analytical techniques like TEM, as it is the case for η′ and η in AA7075-T651, the relative ease with which specimens are prepared for AFM analysis could be advantageous in product and process development, and quality control, where a large number of samples are expected for analysis on a regular basis. - Highlights: • Nanometric MgZn{sub 2} precipitates in AA7075-T651 were characterized using AFM and TEM. • Phase-contrast AFM was used to differentiate metal matrix from MgZn{sub 2} precipitates. • TEM and AFM micrographs were analyzed using commercially available software. • AFM image analysis and TEM 2-D stereology render statistically equivalent results.

  1. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    SciTech Connect

    O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  2. Recovery of yttrium from cathode ray tubes and lamps’ fluorescent powders: experimental results and economic simulation

    SciTech Connect

    Innocenzi, V. De Michelis, I.; Ferella, F.; Vegliò, F.

    2013-11-15

    Highlights: • Fluorescent powder of lamps. • Fluorescent powder of cathode ray rubes. • Recovery of yttrium from fluorescent powders. • Economic simulation for the processes to recover yttrium from WEEE. - Abstract: In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides. Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%. Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes.

  3. A Review of Out-of-School Time Program Quasi-Experimental and Experimental Evaluation Results. Out-of-School Time Evaluation Snapshot.

    ERIC Educational Resources Information Center

    Little, Priscilla M. D.; Harris, Erin

    As the amount of resources allocated to out-of-school (OST) programming and policymakers' demands for research-based results increase, there is increasing interest in rigorous research designs to examine OST program outcomes. This issue of "Out-of-School Time Evaluation Snapshots" reviews 27 quasi-experimental and experimental OST evaluations and…

  4. Tapping and contact mode imaging of native chromosomes and extraction of genomic DNA using AFM tips

    NASA Astrophysics Data System (ADS)

    Sun, Yingchun; Arakawa, Hideo; Osada, Toshiya; Ikai, Atsushi

    2002-03-01

    It is very important both in medicine and biology to clarify the chromosomal structure to understand its functions. In a standard cytogenetic procedure, chromosomes are often fixed in a mixture of acetic acid and methanol. This process most likely changes the mechanical property of chromosomes. We adopted a method to prepare native and unfixed chromosomes from mouse 3T3 cells and used tapping and contact mode atomic force microscopy (AFM) to image and manipulate them. Modified AFM tips were used to image chromosomes in contact mode in air, and then the chromosome samples were immobilized on a substrate and placed in a buffer solution to pull out DNA-histone complexes from them after they were optimally treated with trypsin. From the AFM images, we could see several bands and granular structures on chromosomes. We obtained force curves indicating long fiber extensions from native chromosomes both with low (in high concentration of NaCl) and high forces (physiological conditions). The result suggested that the degree of chromosome condensation decreased in high concentration of salt. It agrees with the known fact of histone H1 dissociation in a high concentration of salt. We intend to pull out DNA-histone complexes from chromosomes for later molecular operations on them using an AFM.

  5. Accurate Calibration and Uncertainty Estimation of the Normal Spring Constant of Various AFM Cantilevers

    PubMed Central

    Song, Yunpeng; Wu, Sen; Xu, Linyan; Fu, Xing

    2015-01-01

    Measurement of force on a micro- or nano-Newton scale is important when exploring the mechanical properties of materials in the biophysics and nanomechanical fields. The atomic force microscope (AFM) is widely used in microforce measurement. The cantilever probe works as an AFM force sensor, and the spring constant of the cantilever is of great significance to the accuracy of the measurement results. This paper presents a normal spring constant calibration method with the combined use of an electromagnetic balance and a homemade AFM head. When the cantilever presses the balance, its deflection is detected through an optical lever integrated in the AFM head. Meanwhile, the corresponding bending force is recorded by the balance. Then the spring constant can be simply calculated using Hooke’s law. During the calibration, a feedback loop is applied to control the deflection of the cantilever. Errors that may affect the stability of the cantilever could be compensated rapidly. Five types of commercial cantilevers with different shapes, stiffness, and operating modes were chosen to evaluate the performance of our system. Based on the uncertainty analysis, the expanded relative standard uncertainties of the normal spring constant of most measured cantilevers are believed to be better than 2%. PMID:25763650

  6. EASE (Experimental Assembly of Structures in EVA) overview of selected results

    NASA Technical Reports Server (NTRS)

    Akin, David L.

    1987-01-01

    Experimental Assembly of Structures in EVA (EASE) objectives, experimental protocol, neutral buoyancy simulation, task time distribution, assembly task performance, metabolic rate/biomedical readouts are summarized. This presentation is shown in charts, figures, and graphs.

  7. Copper Content in Synthetic Copper Carbonate: A Statistical Comparison of Experimental and Expected Results

    NASA Astrophysics Data System (ADS)

    Sheeran, Daniel

    1998-04-01

    This paper describes a general chemistry experiment which was implemented in the 1995-96 academic year and which is based on the preparation of a basic copper(II) carbonate, Cu(OH)2(CO3), and its analysis for copper. Individual results of the copper determination were compiled and a class mean and standard deviation were computed and a frequency plot was constructed for the purpose of comparing class results to the expected result. From a student perspective, the expected result was not Cu(OH)2(CO3), rather it was CuCO3. Students were unaware that they prepared a basic salt, and assumed they prepared CuCO3. This assumption originates in the synthesis which has the appearance of a double displacement reaction. Students expected the copper determination to verify this assumption and were quite surprised when it did not. Statistics was used to reveal the discrepancy between experimental and expected results, and a t-test established that this discrepancy was significant--the prepared material cannot be formulated as CuCO3. The statistical conclusion was further substantiated by observational evidence in the synthesis and analysis steps.

  8. Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

    NASA Technical Reports Server (NTRS)

    Banin, A.; Rishpon, J.

    1979-01-01

    Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

  9. Induced current electrical impedance tomography system: experimental results and numerical simulations.

    PubMed

    Zlochiver, Sharon; Radai, M Michal; Abboud, Shimon; Rosenfeld, Moshe; Dong, Xiu-Zhen; Liu, Rui-Gang; You, Fu-Sheng; Xiang, Hai-Yan; Shi, Xue-Tao

    2004-02-01

    In electrical impedance tomography (EIT), measurements of developed surface potentials due to applied currents are used for the reconstruction of the conductivity distribution. Practical implementation of EIT systems is known to be problematic due to the high sensitivity to noise of such systems, leading to a poor imaging quality. In the present study, the performance of an induced current EIT (ICEIT) system, where eddy current is applied using magnetic induction, was studied by comparing the voltage measurements to simulated data, and examining the imaging quality with respect to simulated reconstructions for several phantom configurations. A 3-coil, 32-electrode ICEIT system was built, and an iterative modified Newton-Raphson algorithm was developed for the solution of the inverse problem. The RMS norm between the simulated and the experimental voltages was found to be 0.08 +/- 0.05 mV (<3%). Two regularization methods were implemented and compared: the Marquardt regularization and the Laplacian regularization (a bounded second-derivative regularization). While the Laplacian regularization method was found to be preferred for simulated data, it resulted in distinctive spatial artifacts for measured data. The experimental reconstructed images were found to be indicative of the angular positioning of the conductivity perturbations, though the radial sensitivity was low, especially when using the Marquardt regularization method. PMID:15005319

  10. Experimental Estimation Of Energy Damping During Free Rocking Of Unreinforced Masonry Walls. First Results

    SciTech Connect

    Sorrentino, Luigi; Masiani, Renato; Benedetti, Stefano

    2008-07-08

    This paper presents an ongoing experimental program on unreinforced masonry walls undergoing free rocking. Aim of the laboratory campaign is the estimation of kinetic energy damping exhibited by walls released with non-zero initial conditions of motion. Such energy damping is necessary for dynamic modelling of unreinforced masonry local mechanisms. After a brief review of the literature on this topic, the main features of the laboratory tests are presented. The program involves the experimental investigation of several parameters: 1) unit material (brick or tuff), 2) wall aspect ratio (ranging between 14.5 and 7.1), 3) restraint condition (two-sided or one-sided rocking), and 4) depth of the contact surface between facade and transverse walls (one-sided rocking only). All walls are single wythe and the mortar is pozzuolanic. The campaign is still in progress. However, it is possible to present the results on most of the mechanical properties of mortar and bricks. Moreover, a few time histories are reported, already indicating the need to correct some of the assumptions frequent in the literature.

  11. Preliminary results of the LLNL airborne experimental test-bed SAR system

    SciTech Connect

    Miller, M.G.; Mullenhoff, C.J.; Kiefer, R.D.; Brase, J.M.; Wieting, M.G.; Berry, G.L.; Jones, H.E.

    1996-01-16

    The Imaging and Detection Program (IDP) within Laser Programs at Lawrence Livermore National Laboratory (LLNL) in cooperation with the Hughes Aircraft Company has developed a versatile, high performance, airborne experimental test-bed (AETB) capability. The test-bed has been developed for a wide range of research and development experimental applications including radar and radiometry plus, with additional aircraft modifications, optical systems. The airborne test-bed capability has been developed within a Douglas EA-3B Skywarrior jet aircraft provided and flown by Hughes Aircraft Company. The current test-bed payload consists of an X-band radar system, a high-speed data acquisition, and a real-time processing capability. The medium power radar system is configured to operate in a high resolution, synthetic aperture radar (SAR) mode and is highly configurable in terms of waveforrns, PRF, bandwidth, etc. Antennas are mounted on a 2-axis gimbal in the belly radome of the aircraft which provides pointing and stabilization. Aircraft position and antenna attitude are derived from a dedicated navigational system and provided to the real-time SAR image processor for instant image reconstruction and analysis. This paper presents a further description of the test-bed and payload subsystems plus preliminary results of SAR imagery.

  12. Experimental results and modeling tests of an adsorptive air-conditioning unit

    SciTech Connect

    Guilleminot, J.J.; Poyelle, F.; Meunier, F.

    1998-10-01

    Experimental tests have been performed on a zeolite-water adsorptive system suitable for air conditioning and consisting of two adsorbers filled with a consolidated composite made of zeolite mixed with a highly conductive matrix. This paper describes the experimental results of such a heat pump unit operating with a heat and mass recovery cycle. An important enhancement of the specific cooling power (SCP) has been achieved. At evaporating temperature T = 4 C, mass transfer resistance controls the process and limits the expected COP. Tests carried out at higher evaporating pressure make it possible to achieve the predicted COP and SCP. A predictive model developed and validated elsewhere in order to describe the temperature evolution of components and the heat and mass transfer in the adsorbers explains the mass transfer resistance in the adsorbent. Last, a new highly conductive adsorbent composite with good mass transfer properties is developed. The model is used to predict the performances of this new material. Very good SCP and COP can be achieved.

  13. Experimental results of flooding experiments in an inclined tube with liquid nitrogen and its vapor

    NASA Astrophysics Data System (ADS)

    Chen, Jianye; Xu, Lu; Xiong, Wei; Qiu, Limin; Zhang, Xiaobin

    2014-07-01

    Counter-current two-phase flow behaviors of saturated liquid nitrogen and its vapor at the onset of flooding are experimentally investigated. The experiments are carried out in a vacuum-insulated 20 mm i.d. transparent tube with the inclination angles of 30°, 45° and 60° corresponding to the horizontal. The common slug flow phenomenon happened with water-air is not observed with liquid nitrogen-vapor, instead, the big interfacial wave is found to be crushed to tiny droplets. The phenomenal difference is primarily attributed to the larger viscosity of water than liquid nitrogen. Correspondingly, the sharp rise of pressure drop with water-air is largely due to the blockage of gas flow by the formed slug, while it is primarily due to the tiny droplet entrainment for the liquid nitrogen-vapor pairs. The effects of inclination angles on the incipient flooding velocity are specially emphasized and investigated. A new correlation base on Ohnesorge number and modified Froude number are presented, and the results coincide with the experimental data of both room-temperature and cryogenic fluids with the uncertainty of 20%.

  14. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    NASA Astrophysics Data System (ADS)

    Menapace, E.; Birattari, C.; Bonardi, M. L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-01

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  15. Frequency-dependent seismic attenuation in shales: experimental results and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Delle Piane, Claudio; Sarout, Joel; Madonna, Claudio; Saenger, Erik H.; Dewhurst, David N.; Raven, Mark

    2014-07-01

    Samples of shales from the Ordovician Bongabinni and Goldwyer source rock formations were recovered from the Canning Basin (Western Australia). Attenuation was experimentally measured on preserved plugs from these formations in the frequency range between 10-2 and 102 Hz. Samples cored with different orientations with respect to the sedimentary bedding were prepared and tested in their native saturated state and after drying in the oven at 105 °C for 24 hr to assess the effect of fluids and of the sediment anisotropy on attenuation. To aid the interpretation of the experimental results, the clay-rich samples were characterized in terms of mineralogy, water content, porosity, permeability and microstructure. The two shales have significantly different quality factors; and this is seen to be dependent on both the saturation state of the samples and the propagation direction of the oscillatory signal. The attenuation coefficient for compression/extension parallel to bedding is less than that vertical to bedding in both the preserved and partially dehydrated situations. No frequency dependency is observed in the preserved samples within the range of frequencies explored in this study. On the other hand partially saturated samples show peaks in attenuation at around 40 Hz when the stress perturbation is transmitted normal to the macroscopic bedding. The interpretation of the attenuation measurements in terms of well-established theoretical models is discussed in view of the physical characteristics and microstructure of the tested rocks.

  16. Fate and Transport of Graphene Oxide in Granular Porous Media: Experimental Results and Modeling

    NASA Astrophysics Data System (ADS)

    Gao, Bin

    2014-05-01

    Although graphene oxide (GO) has been used in many applications to improve human life quality, its environmental fate and behavior are still largely unknown. In this work, a range of laboratory experiments were conducted to explore the aggregation, deposition, and transport mechanisms of GO nano-sheets in porous media under various conditions. Stability experimental data showed that both cation valence and pH showed significant effect on the aggregation of GO sheets. The measured critical coagulation concentrations were in good agreement with the predictions of the extended Schulze-Hardy rule. Sand column experimental results indicated that deposition and transport of GO in porous media were strongly dependent on solution ionic strength. Particularly, GO showed high mobility under low ionic strength conditions in both saturated and unsaturated columns. Increasing ionic strength dramatically increased the retention of GO in porous media, mainly through secondary-minimum deposition. Recovery rates of GO in unsaturated sand columns were lower than that in saturated columns under the same ionic strength conditions, suggesting moisture content also played an important role in the retention of GO in porous media. Findings from the bubble column experiments showed that the GO did not attach to the air-water interface, which is consistent with the XDLVO predictions. Additional retention mechanisms, such as film straining, thus could be responsible to the reduced mobility of GO in unsaturated porous media. The breakthrough curves of GO in saturated and unsaturated columns could be accurately simulated by an advection-dispersion-reaction model.

  17. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    SciTech Connect

    Menapace, E.; Birattari, C.; Bonardi, M.L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-24

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  18. Structural and vibrational study of graphene oxide via coronene based models: theoretical and experimental results

    NASA Astrophysics Data System (ADS)

    Almeida de Mendonça, João Paulo; Henrique de Lima, Alessandro; Amaral Junqueira, Georgia Maria; Gianini Quirino, Welber; Legnani, Cristiano; Oliveira Maciel, Indhira; Sato, Fernando

    2016-05-01

    We use the Coronene (C24H12), a simple and finite molecule, to make a model to study the spectroscopic and structural alterations generated by oxygenated groups in graphene oxide (GO). Based on the Lerf–Klinowski model, we chose the hydroxyl [OH‑], the carboxyl [COOH‑] and the epoxy [the ring C2O inside the molecule] as our radicals of interest and study their collective and isolated effects. We perform geometry optimization, vibrational IR (via AM1 and DFT-B3LYP) and Raman spectra (via DFT-B3LYP) of a series of functionalized coronene molecules. As results, we obtain some useful data for the analysis of IR and Raman spectra of GO, which facilitate the understanding and identification of the peaks found in the experiment. Finally, we suggest a new model to study GO, producing an accurate signature when compared to our experimental data. Such molecule shows in more details of the structural effects caused by functionalization when compared to experimental data.

  19. Experimental Results from the Thermal Energy Storage-1 (TES-1) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Wald, Lawrence W.; Tolbert, Carol; Jacqmin, David

    1995-01-01

    The Thermal Energy Storage-1 (TES-1) is a flight experiment that flew on the Space Shuttle Columbia (STS-62), in March 1994, as part of the OAST-2 mission. TES-1 is the first experiment in a four experiment suite designed to provide data for understanding the long duration microgravity behavior of thermal energy storage fluoride salts that undergo repeated melting and freezing. Such data have never been obtained before and have direct application for the development of space-based solar dynamic (SD) power systems. These power systems will store solar energy in a thermal energy salt such as lithium fluoride or calcium fluoride. The stored energy is extracted during the shade portion of the orbit. This enables the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes have been developed for predicting performance of a spaced-based solar dynamic power system. Experimental verification of the analytical predictions is needed prior to using the analytical results for future space power design applications. The four TES flight experiments will be used to obtain the needed experimental data. This paper will focus on the flight results from the first experiment, TES-1, in comparison to the predicted results from the Thermal Energy Storage Simulation (TESSIM) analytical computer code. The TES-1 conceptual development, hardware design, final development, and system verification testing were accomplished at the NASA lewis Research Center (LeRC). TES-1 was developed under the In-Space Technology Experiment Program (IN-STEP), which sponsors NASA, industry, and university flight experiments designed to enable and enhance space flight technology. The IN-STEP Program is sponsored by the Office of Space Access and Technology (OSAT).

  20. Drying in porous media with gravity-stabilized fronts: experimental results.

    PubMed

    Yiotis, A G; Salin, D; Tajer, E S; Yortsos, Y C

    2012-08-01

    In a recent paper [Yiotis et al., Phys. Rev. E 85, 046308 (2012)] we developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer, and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. In this paper, we test the theory using laboratory experiments. A series of isothermal drying experiments in glass bead packings saturated with volatile hydrocarbons is conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. The experimental results agree very well with theory, provided that the latter is generalized to account for the effects of corner roundness in the film region (which was neglected in the theoretical part). We demonstrate the existence of an early constant rate period (CRP), which lasts as long as the films saturate the surface of the packing, and of a subsequent falling rate period (FRP), which begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. Theoretical and experimental results compare favorably for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on the capillary Ca(f), Bond Bo, and Sherwood Sh numbers. PMID:23005857

  1. Immiscible liquid-liquid pressure-driven flow in capillary tubes: Experimental results and numerical comparison

    NASA Astrophysics Data System (ADS)

    Soares, Edson J.; Thompson, Roney L.; Niero, Debora C.

    2015-08-01

    The immiscible displacement of one viscous liquid by another in a capillary tube is experimentally and numerically analyzed in the low inertia regime with negligible buoyancy effects. The dimensionless numbers that govern the problem are the capillary number Ca and the viscosity ratio of the displaced to the displacing fluids Nμ. In general, there are two output quantities of interest. One is associated to the relation between the front velocity, Ub, and the mean velocity of the displaced fluid, U ¯ 2 . The other is the layer thickness of the displaced fluid that remains attached to the wall. We compute these quantities as mass fractions in order to make them able to be compared. In this connection, the efficiency mass fraction, me, is defined as the complement of the mass fraction of the displaced fluid that leaves the tube while the displacing fluid crosses its length. The geometric mass fraction, mg, is defined as the fraction of the volume of the layer that remains attached to the wall. Because in gas-liquid displacement, these two quantities coincide, it is not uncommon in the literature to use mg as a measure of the displacement efficiency for liquid-liquid displacements. However, as is shown in the present paper, these two quantities have opposite tendencies when we increase the viscosity of the displacing fluid, making this distinction a crucial aspect of the problem. Results from a Galerkin finite element approach are also presented in order to make a comparison. Experimental and numerical results show that while the displacement efficiency decreases, the geometrical fraction increases when the viscosity ratio decreases. This fact leads to different decisions depending on the quantity to be optimized. The quantitative agreement between the numerical and experimental results was not completely achieved, especially for intermediate values of Ca. The reasons for that are still under investigation. The experiments conducted were able to achieve a wide range

  2. Implementation and experimental results of 4D tumor tracking using robotic couch

    SciTech Connect

    Buzurovic, I.; Yu, Y.; Werner-Wasik, M.; Biswas, T.; Anne, P. R.; Dicker, A. P.; Podder, T. K.

    2012-11-15

    Purpose: This study presents the implementation and experimental results of a novel technique for 4D tumor tracking using a commercially available and commonly used treatment couch and evaluates the tumor tracking accuracy in clinical settings. Methods: Commercially available couch is capable of positioning the patient accurately; however, currently there is no provision for compensating physiological movement using the treatment couch in real-time. In this paper, a real-time couch tracking control technique is presented together with experimental results in tumor motion compensation in four dimensions (superior-inferior, lateral, anterior-posterior, and time). To implement real-time couch motion for tracking, a novel control system for the treatment couch was developed. The primary functional requirements for this novel technique were: (a) the treatment couch should maintain all previous/normal features for patient setup and positioning, (b) the new control system should be used as a parallel system when tumor tracking would be deployed, and (c) tracking could be performed in a single direction and/or concurrently in all three directions of the couch motion (longitudinal, lateral, and vertical). To the authors' best knowledge, the implementation of such technique to a regular treatment couch for tumor tracking has not been reported so far. To evaluate the performance of the tracking couch, we investigated the mechanical characteristics of the system such as system positioning resolution, repeatability, accuracy, and tracking performance. Performance of the tracking system was evaluated using dosimetric test as an endpoint. To investigate the accuracy of real-time tracking in the clinical setting, the existing clinical treatment couch was replaced with our experimental couch and the linear accelerator was used to deliver 3D conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) treatment plans with and without tracking. The results of

  3. Motion effects on an IFR hovering task: Analytical predictions and experimental results

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.; Stapleford, R. L.; Magdaleno, R. E.

    1971-01-01

    An analytical pilot model incorporating the effects of motion cues and display scanning and sampling is tested by comparing predictions against experimental results on a moving base simulator. The simulated task is that of precision hovering of a VTOL having varying amounts of rate damping, and using separated instrument displays. Motion cue effects are investigated by running the experiment under fixed and moving base conditions, the latter in two modes; full motion, and angular motion only. Display scanning behavior is measured on some of the runs. The results of the program show that performance is best with angular motion only, most probably because a g-vector tilt cue is available to the pilot in this motion condition. This provides an attitude indication even when not visually fixating the attitude display. Vestibular threshold effects are also present in the results because of the display scaling used to permit hovering position control within the motion simulator limits; no washouts are used in the simulator drive signals. The IFR nature of the task results in large decrements in pilot opinion and performance relative to VFR conditions because of the scanning workload. Measurements of scanning behavior are sensitive to motion conditions and show more attention to attitude control under fixed base conditions.

  4. Preliminary experimental results on studying possibility of variable mass liner (VML) formation

    SciTech Connect

    1995-12-31

    The main objective of the present experiment was to study the formation process and initial stage of acceleration of a variable-mass plasma liner (VML). The method is based on magnetic acceleration of a liner with the mass reduced during such acceleration. The experiment was carried out on February 16 at VNIIEF. This report describes the results of measurements obtained in the experiment and preliminary analysis of the results characterizing operation of the test facility main units: helical EMG; 5-module disk EMG 400 mm in diameter (DEMG); ponderomotive unit (PU) with a cylindric condensed liner and a special tooth-cutoff. The first part of the report presents measurement results obtained on the VNIIEF`s diagnostic equipment that are compared with those obtained by American specialists on their diagnostic equipment. Information submitted by American specialists is included in part 2 of this report. The second part of the report presents preliminary computational-theoretic analysis of the main measured results describing operation of DEMG TL system in the experiment; experimental data are compared with theoretical ones obtained before and after the experiment. But more emphasis is placed on the data preliminary analysis indicating that in the experiment a variable mass liner is formed (VML or plasma bubble).

  5. Experimental and computer simulation results of the spot welding process using SORPAS software

    NASA Astrophysics Data System (ADS)

    Al-Jader, M. A.; Cullen, J. D.; Athi, N.; Al-Shamma'a, A. I.

    2009-07-01

    The highly competitive nature of the automotive industry drives demand for improvements and increased precision engineering in resistance spot welding. Currently there are about 4300 weld points on the average steel vehicle. Current industrial monitoring systems check the quality of the nugget after processing 15 cars, once every two weeks. The nuggets are examined off line using a destructive process, which takes approximately 10 days to complete causing a long delay in the production process. This paper presents a simulation of the spot welding growth curves, along with a comparison to growth curves performed on an industrial spot welding machine. The correlation of experimental results shows that SORPAS simulations can be used as an off line measurement to reduce factory energy usage. The first section in your paper

  6. Lateral and axial resolutions of an angle-deviation microscope for different numerical apertures: experimental results

    NASA Astrophysics Data System (ADS)

    Chiu, Ming-Hung; Lai, Chin-Fa; Tan, Chen-Tai; Lin, Yi-Zhi

    2011-03-01

    This paper presents a study of the lateral and axial resolutions of a transmission laser-scanning angle-deviation microscope (TADM) with different numerical aperture (NA) values. The TADM is based on geometric optics and surface plasmon resonance principles. The surface height is proportional to the phase difference between two marginal rays of the test beam, which is passed through the test medium. We used common-path heterodyne interferometry to measure the phase difference in real time, and used a personal computer to calculate and plot the surface profile. The experimental results showed that the best lateral and axial resolutions for NA = 0.41 were 0.5 μm and 3 nm, respectively, and the lateral resolution breaks through the diffraction limits.

  7. Inlet Flow Test Calibration for a Small Axial Compressor Facility. Part 1: Design and Experimental Results

    NASA Technical Reports Server (NTRS)

    Miller, D. P.; Prahst, P. S.

    1994-01-01

    An axial compressor test rig has been designed for the operation of small turbomachines. The inlet region consisted of a long flowpath region with two series of support struts and a flapped inlet guide vane. A flow test was run to calibrate and determine the source and magnitudes of the loss mechanisms in the inlet for a highly loaded two-stage axial compressor test. Several flow conditions and IGV angle settings were established in which detailed surveys were completed. Boundary layer bleed was also provided along the casing of the inlet behind the support struts and ahead of the IGV. A detailed discussion of the flowpath design along with a summary of the experimental results are provided in Part 1.

  8. Deuteron induced reactions on Ho and La: Experimental excitation functions and comparison with code results

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam-Rebeles, R.; Tarkanyi, F.; Takacs, S.; Csikai, J.; Takacs, M. P.; Ignatyuk, A.

    2013-09-01

    Activation products of rare earth elements are gaining importance in medical and technical applications. In stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross-sections for production of 161,165Er, 166gHo on 165Ho and 135,137m,137g,139Ce, 140La, 133m,133g,cumBa and 136Cs on natLa targets were measured up to 50 MeV. Reduced uncertainty is obtained by simultaneous remeasurement of the 27Al(d,x)24,22Na monitor reactions over the whole energy range. A comparison with experimental literature values and results from updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2012 online library) is discussed.

  9. School Context and Educational Outcomes: Results from a Quasi-Experimental Study

    PubMed Central

    Casciano, Rebecca; Massey, Douglas S.

    2013-01-01

    In this study we draw on data from a quasi-experimental study to test whether moving into a subsidized housing development in an affluent suburb yields educational benefits to the children of residents, compared to the educations they would have received had they not moved into the development. Results suggest that resident children experienced a significant improvement in school quality compared with a comparison group of students whose parents also had applied for residence. Parents who were residents of the development also displayed higher levels of school involvement compared with the comparison group of non-resident parents, and their children were exposed to significantly lower levels of school disorder and violence within school and spent more time reading outside of school. Living in the development did not influence GPA directly, but did indirectly increase GPA by increasing the time residents spent reading outside of school. PMID:25342878

  10. Rainfall estimation using microwave links. Results from an experimental setup in Luxembourg

    NASA Astrophysics Data System (ADS)

    Fenicia, Fabrizio; Matgen, Patrick; Pfister, Laurent

    2010-05-01

    Microwave links represent a valid alternative to traditional rainfall estimation methods. They are commonly used in mobile phone communication, and they constitute built-in widely distributed networks. Due to their ability of providing high temporal and spatial resolution measurements, their use is particularly suitable in urban settings. We here show results from an experimental setup in Luxembourg City, where two dual frequency links have been installed. The links cover a distance of about 4km, and measure power attenuation at 1 min. timestep. The links have been equipped with several recording raingauges, which measure rainfall in real-time communicating through a wireless connection. This set-up has been used to analyze in detail the mapping between attenuation and rainfall intensity, and gain insights into the potential accuracy of these instruments. In addition, we investigated the relation between rainfall and discharge response of the urban area of Luxembourg, which shows the potential utility of high frequency rainfall measurements for urban environments.

  11. Knowledge-Aided Multichannel Adaptive SAR/GMTI Processing: Algorithm and Experimental Results

    NASA Astrophysics Data System (ADS)

    Wu, Di; Zhu, Daiyin; Zhu, Zhaoda

    2010-12-01

    The multichannel synthetic aperture radar ground moving target indication (SAR/GMTI) technique is a simplified implementation of space-time adaptive processing (STAP), which has been proved to be feasible in the past decades. However, its detection performance will be degraded in heterogeneous environments due to the rapidly varying clutter characteristics. Knowledge-aided (KA) STAP provides an effective way to deal with the nonstationary problem in real-world clutter environment. Based on the KA STAP methods, this paper proposes a KA algorithm for adaptive SAR/GMTI processing in heterogeneous environments. It reduces sample support by its fast convergence properties and shows robust to non-stationary clutter distribution relative to the traditional adaptive SAR/GMTI scheme. Experimental clutter suppression results are employed to verify the virtue of this algorithm.

  12. Noise characteristics of upper surface blown configurations. Experimental program and results

    NASA Technical Reports Server (NTRS)

    Brown, W. H.; Searle, N.; Blakney, D. F.; Pennock, A. P.; Gibson, J. S.

    1977-01-01

    An experimental data base was developed from the model upper surface blowing (USB) propulsive lift system hardware. While the emphasis was on far field noise data, a considerable amount of relevant flow field data were also obtained. The data were derived from experiments in four different facilities resulting in: (1) small scale static flow field data; (2) small scale static noise data; (3) small scale simulated forward speed noise and load data; and (4) limited larger-scale static noise flow field and load data. All of the small scale tests used the same USB flap parts. Operational and geometrical variables covered in the test program included jet velocity, nozzle shape, nozzle area, nozzle impingement angle, nozzle vertical and horizontal location, flap length, flap deflection angle, and flap radius of curvature.

  13. Active vibration absorber for CSI evolutionary model: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Bruner, Anne M.; Belvin, W. Keith; Horta, Lucas G.; Juang, Jer-Nan

    1991-01-01

    The development of control of large flexible structures technology must include practical demonstration to aid in the understanding and characterization of controlled structures in space. To support this effort, a testbed facility was developed to study practical implementation of new control technologies under realistic conditions. The design is discussed of a second order, acceleration feedback controller which acts as an active vibration absorber. This controller provides guaranteed stability margins for collocated sensor/actuator pairs in the absence of sensor/actuator dynamics and computational time delay. The primary performance objective considered is damping augmentation of the first nine structural modes. Comparison of experimental and predicted closed loop damping is presented, including test and simulation time histories for open and closed loop cases. Although the simulation and test results are not in full agreement, robustness of this design under model uncertainty is demonstrated. The basic advantage of this second order controller design is that the stability of the controller is model independent.

  14. Comparison of thermal modeling and experimental results of a generic model for ground vehicle

    NASA Astrophysics Data System (ADS)

    Bushlin, Y.; Lessin, A.; Reinov, A.

    2006-05-01

    Accurate thermal modeling requires verification and validation of the model and software being used. For basic evaluation of thermal prediction models and software tools, a generic model - CUBI was build. The model was designed to have simple geometry yet, consisted of similar characteristics as of a ground vehicle. The model was equipped with thermocouples for measuring its temperature variations and was placed in a typical desert environment for field testing. The experimental setup also included a meteorological station. The data collected was used for the thermal behavior analysis of the generic model and for comparison with the thermal calculations predictions. Comparison of the results shows sufficient compliance but yet reviles some issues in the modeling that should be addressed.

  15. Modelling Viscoelastic Behaviour of Polymer by A Mixed Velocity, Displacement Formulation - Numerical and Experimental Results

    SciTech Connect

    Pham, VT.; Silva, L.; Digonnet, H.; Combeaud, C.; Billon, N.; Coupez, T.

    2011-05-04

    The objective of this work is to model the viscoelastic behaviour of polymer from the solid state to the liquid state. With this objective, we perform experimental tensile tests and compare with simulation results. The chosen polymer is a PMMA whose behaviour depends on its temperature. The computation simulation is based on Navier-Stokes equations where we propose a mixed finite element method with an interpolation P1+/P1 using displacement (or velocity) and pressure as principal variables. The implemented technique uses a mesh composed of triangles (2D) or tetrahedra (3D). The goal of this approach is to model the viscoelastic behaviour of polymers through a fluid-structure coupling technique with a multiphase approach.

  16. Experimental Results from Droop Compensation for the High Voltage Converter Modulators

    SciTech Connect

    Patel, Gunjan P; Anderson, David E; Peplov, Vladimir V; Saethre, Robert B; Solley, Dennis J; Wezensky, Mark W

    2013-01-01

    The High Voltage Convertor Modulators are used to power the RF klystrons used throughout the linear accelerator at the Spallation Neutron Source. The output voltage of the modulator has significant voltage droop and ripple which, combined with low level RF system limitations, affect performance and stability of the accelerator cavities. In conjunction with the progress in the development of the new controller, different modulation techniques were implemented and studied on the test modulator. This paper discusses experimental results from implementation of different modulation schemes has on the modulator output voltage pulse. Thermal measurements were carried out to determine the effect of these modulations schemes on long term reliability of the modulator. Future plans are also discussed.

  17. An aerodynamic analysis of the autogiro rotor with a comparison between calculated and experimental results

    NASA Technical Reports Server (NTRS)

    Wheatley, John B

    1935-01-01

    This report presents an extension of the autogiro theory of Glauert and Lock in which the influence of a pitch varying with the blade radius is evaluated and methods of approximating the effect of blade tip losses and the influence of reversed velocities on the retreating blades are developed. A comparison of calculated and experimental results showed that most of the rotor characteristics could be calculated with reasonable accuracy, and that the type of induced flow assumed has a secondary effect upon the net rotor forces, although the flapping motion is influenced appreciably. An approximate evaluation of the effect of parasite drag on the rotor blades established the importance of including this factor in the analysis.

  18. Physical model and experimental results of cathode erosion related to power supply ripple

    NASA Technical Reports Server (NTRS)

    Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.

    1992-01-01

    This paper discusses the physical effects of power supply ripple on cathode erosion and cathode arc attachment in a water-cooled, 30 kW nitrogen arcjet. Experimental results are presented for 2 percent thoriated tungsten, which show that the long-term cathode erosion rate is a decreasing function of current ripple over the range 1-13 percent. Above this range, the cathode discharge becomes unstable, and the erosion rate rapidly increases. A qualitative model of this effect is given in terms of a magnetically induced radial motion of the arc column, and an overall increase in the cathode spot radius due to the higher peak current associated with higher ripple. The most important effect of power supply ripple is therefore shown to be its ability to collectively drive the cathode attachment away from the cathode center. This leads to an increase in the cathode attachment area, and a subsequent decrease in the cathode erosion rate.

  19. Simulation and experimental results of optical and thermal modeling of gold nanoshells.

    PubMed

    Ghazanfari, Lida; Khosroshahi, Mohammad E

    2014-09-01

    This paper proposes a generalized method for optical and thermal modeling of synthesized magneto-optical nanoshells (MNSs) for biomedical applications. Superparamagnetic magnetite nanoparticles with diameter of 9.5 ± 1.4 nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8 ± 3.5 nm MNSs. In this paper, simulations and detailed analysis are carried out for different nanoshell geometry to achieve a maximum heat power. Structural, magnetic and optical properties of MNSs are assessed using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), UV-VIS spectrophotometer, dynamic light scattering (DLS), and transmission electron microscope (TEM). Magnetic saturation of synthesized magnetite nanoparticles are reduced from 46.94 to 11.98 emu/g after coating with gold. The performance of the proposed optical-thermal modeling technique is verified by simulation and experimental results. PMID:25063109

  20. Optical constants of Titan aerosols and their tholins analogs: Experimental results and modeling/observational data

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

    2015-05-01

    Since Bishun Khare's pioneer works on Titan tholins, many studies have been performed to improve the experimental database of the optical constants of Titan tholins. The determination of the optical constants of Titan aerosols is indeed essential to quantify their capacity to absorb and scatter solar radiation, and thus to evaluate their role on Titan's radiative balance and climate. The study of the optical properties is also crucial to analyze and better interpret many of Titan's observational data, in particular those acquired during the Cassini-Huygens mission. This review paper critically summarizes these new results and presents constraints on Titan's aerosols optical constants. Finally, the information lacking in this field is highlighted as well as some possible investigations that could be carried out to fill these gaps.

  1. NACA0012 benchmark model experimental flutter results with unsteady pressure distributions

    NASA Technical Reports Server (NTRS)

    Rivera, Jose A., Jr.; Dansberry, Bryan E.; Bennett, Robert M.; Durham, Michael H.; Silva, Walter A.

    1992-01-01

    The Structural Dynamics Division at NASA Langley Research Center has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of this program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type computational fluid dynamics codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. This paper describes results obtained from a second wind tunnel test of the first model in the Benchmark Models Program. This first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree of freedom mount system. Experimental flutter boundaries and corresponding unsteady pressure distribution data acquired over two model chords located at the 60 and 95 percent span stations are presented.

  2. First experimental results of the BNL inverse free electron laser accelerator

    SciTech Connect

    Steenbergen, A. van; Gallardo, J.; Babzien, M.; Skaritka, J.; Wang, X.J.; Sandweiss, J.; Fang, J.M.; Qiu, X.

    1996-10-01

    A 40 MeV electron beam, using the inverse3e free-electron laser interaction, has been accelerated by {Delta}E/E = 2.5% over a distance of 0.47 m. The electrons interact with a 1--2 GW CO{sub 2} laser beam bounded by a 2.8 mm ID sapphire circular waveguide in the presence of a tapered wiggler with Bmax {approx} 1 T and a period 2.89 cm {le} {lambda}{sub w} {le} 3.14 cm. The experimental results of {Delta}E/E as a function of electron energy E, peak magnetic field Bw and laser power W{sub 1} compare well with analytical and 1-D numerical simulations and permit scaling to higher laser power and electron energy.

  3. Experimental results of active control on a large structure to suppress vibration

    NASA Technical Reports Server (NTRS)

    Dunn, H. J.

    1991-01-01

    Three design methods, Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR), H-infinity, and mu-synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. Time histories of the measured motion are presented, and modal damping obtained during the experiments are compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed.

  4. Fault induction dynamic model, suitable for computer simulation: Simulation results and experimental validation

    NASA Astrophysics Data System (ADS)

    Baccarini, Lane Maria Rabelo; de Menezes, Benjamim Rodrigues; Caminhas, Walmir Matos

    2010-01-01

    The study of induction motor behavior under not normal conditions and the ability to detect and predict these conditions has been an area of increasing interest. Early detection and diagnosis of incipient faults are desirable for interactive evaluation over the running condition, product quality guarantee, and improved operational efficiency of induction motors. The main difficulty in this task is the lack of accurate analytical models to describe a faulty motor. This paper proposes a dynamic model to analyze electrical and mechanical faults in induction machines and includes net asymmetries and load conditions. The model permits to analyze the interactions between different faults in order to detect possible false alarms. Simulations and experimental results were performed to confirm the validity of the model.

  5. Some experimental results on the L-star instability of metallized composite propellants. [combustion instability

    NASA Technical Reports Server (NTRS)

    Kumar, R. N.

    1975-01-01

    Experimental results are reported on the L-star instability characteristics of three AP/composite propellants. The metal content of the propellants is 2, 16, and 16%. Chuffing, bulk mode oscillations, and time-independent combustion are observed with all three of these propellants. The stability boundary, defined as the boundary between time-independent and unstable combustion, is found to be well defined for two of the propellants in agreement with recognized trends available in the literature on other propellants. The frequency of bulk mode oscillations is presented as a function of the chamber characteristic length. One of the propellants tested has shown bulk mode instability at as high a pressure as 217 psia.

  6. Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons

    SciTech Connect

    Bodek, Arie

    2015-09-01

    We present preliminary results on an experimental study of the nuclear modification of the longitudinal (σL) and transverse (σT) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= σLT for nuclei (RA) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, RA < RD.

  7. Theoretical versus experimental results for the rotordynamic coefficients of eccentric, smooth, gas annular seal annular gas seals

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.; Alexander, Chis

    1994-01-01

    This viewgraph presentation presents the following results: (1) The analytical results overpredict the experimental results for the direct stiffness values and incorrectly predict increasing stiffness with decreasing pressure ratios. (2) Theory correctly predicts increasing cross-coupled stiffness, K(sub YX), with increasing eccentricity and inlet preswirl. (3) Direct damping, C(sub XX), underpredicts the experimental results, but the analytical results do correctly show that damping increases with increasing eccentricity. (4) The whirl frequency values predicted by theory are insensitive to changes in the static eccentricity ratio. Although these values match perfectly with the experimental results at 16,000 rpm, the results at the lower speed do not correspond. (5) Theoretical and experimental mass flow rates match at 5000 rpm, but at 16,000 rpm the theoretical results overpredict the experimental mass flow rates. (6) Theory correctly shows the linear pressure profiles and the associated entrance losses with the specified rotor positions.

  8. Reduction of FeO in smelting slags by solid carbon: Experimental results

    NASA Astrophysics Data System (ADS)

    Sarma, B.; Cramb, A. W.; Fruehan, R. J.

    1996-10-01

    The reduction of CaO-SiO2-Al2O3-FeO slags containing less than 10 wt pct FeO by solid carbonaceous materials such as graphite, coke, and coal char was investigated at reaction temperatures of 1400 °C to 1450 °C. The carbon monoxide evolution rate from the system was measured using stationary and rotating carbon rods, stationary horizontal carbon surfaces, and pinned stationary spheres as the reductants. The measured reaction rate ranged from 3.25 × 10-7 mol cm-2 s-1 at 2.1 pct FeO under static conditions to 3.6 × 10-6 mol cm-2 s-1 at 9.5 pct FeO for a rotating rod experiment. Visualization of the experiment using X-ray fluoroscopy showed that gas evolution from the reduction reaction caused the slag to foam during the experiment and that a gas film formed between the carbon surface and the slag at all times during experimentation. The reaction rate increased with increased slag FeO contents under all experimental conditions; however, this variation was not linear with FeO content. The reaction rate also increased with the rotation speed of the carbon rod at a given FeO content. A small increase in the reaction rate, at a given FeO content, was found when horizontal coke surfaces and coke spheres were used as the reductant as compared to graphite and coal char. The results of these experiments do not fit the traditional mass transfer correlations due to the evolution of gas during the experiment. The experimental results are consistent, however, with the hypothesis that liquid phase mass transfer of iron oxide is a major factor in the rate of reduction of iron oxide from slags by carbonaceous materials. In a second article, the individual rates of the possible limiting steps will be compared and a mixed control model will be used to explain the measured reaction rates.

  9. Using leg muscles as shock absorbers: theoretical predictions and experimental results of drop landing performance.

    PubMed

    Minetti, A E; Ardigò, L P; Susta, D; Cotelli, F

    1998-12-01

    The use of muscles as power dissipators is investigated in this study, both from the modellistic and the experimental points of view. Theoretical predictions of the drop landing manoeuvre for a range of initial conditions have been obtained by accounting for the mechanical characteristics of knee extensor muscles, the limb geometry and assuming maximum neural activation. Resulting dynamics have been represented in the phase plane (vertical displacement versus speed) to better classify the damping performance. Predictions of safe landing in sedentary subjects were associated to dropping from a maximum (feet) height of 1.6-2.0 m (about 11 m on the moon). Athletes can extend up to 2.6-3.0 m, while for obese males (m = 100 kg, standard stature) the limit should reduce to 0.9-1.3 m. These results have been calculated by including in the model the estimated stiffness of the 'global elastic elements' acting below the squat position. Experimental landings from a height of 0.4, 0.7, 1.1 m (sedentary males (SM) and male (AM) and female (AF) athletes from the alpine ski national team) showed dynamics similar to the model predictions. While the peak power (for a drop height of about 0.7 m) was similar in SM and AF (AM shows a +40% increase, about 33 W/kg), AF stopped the downward movement after a time interval (0.219 +/- 0.030 s) from touch-down 20% significantly shorter than SM. Landing strategy and the effect of anatomical constraints are discussed in the paper. PMID:9857837

  10. Shuttle Damage/Repair from the Perspective of Hypersonic Boundary Layer Transition - Experimental Results

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; Berry, Scott A.; Merski, N. Ronald; Berger, Karen T.; Buck, Gregory M.; Liechty, Derek S.; Schneider, Steven P.

    2006-01-01

    An overview is provided of the experimental wind tunnel program conducted at the NASA Langley Research Center Aerothermodynamics Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for Return-to-Flight. The effect of an isolated protuberance and an isolated rectangular cavity on hypersonic boundary layer transition onset on the windward surface of the Shuttle Orbiter has been experimentally characterized. These experimental studies were initiated to provide a protuberance and cavity effects database for developing hypersonic transition criteria to support on-orbit disposition of thermal protection system damage or repair. In addition, a synergistic experimental investigation was undertaken to assess the impact of an isolated mass-flow entrainment source (simulating pyrolysis/outgassing from a proposed tile repair material) on boundary layer transition. A brief review of the relevant literature regarding hypersonic boundary layer transition induced from cavities and localized mass addition from ablation is presented. Boundary layer transition results were obtained using 0.0075-scale Orbiter models with simulated tile damage (rectangular cavities) of varying length, width, and depth and simulated tile damage or repair (protuberances) of varying height. Cavity and mass addition effects were assessed at a fixed location (x/L = 0.3) along the model centerline in a region of near zero pressure gradient. Cavity length-to-depth ratio was systematically varied from 2.5 to 17.7 and length-to-width ratio of 1 to 8.5. Cavity depth-to-local boundary layer thickness ranged from 0.5 to 4.8. Protuberances were located at several sites along the centerline and port/starboard attachment lines along the chine and wing leading edge. Protuberance height-to-boundary layer thickness was varied from approximately 0.2 to 1.1. Global heat transfer images and heating distributions of the Orbiter windward surface using phosphor thermography were used to infer the

  11. Comparison Between Numerical and Experimental Results on Mechanical Stirrer and Bubbling in a Cylindrical Tank - 13047

    SciTech Connect

    Lima da Silva, M.; Sauvage, E.; Brun, P.; Gagnoud, A.; Fautrelle, Y.; Riva, R.

    2013-07-01

    The process of vitrification in a cold crucible heated by direct induction is used in the fusion of oxides. Its feature is the production of high-purity materials. The high-level of purity of the molten is achieved because this melting technique excludes the contamination of the charge by the crucible. The aim of the present paper is to analyze the hydrodynamic of the vitrification process by direct induction, with the focus in the effects associated with the interaction between the mechanical stirrer and bubbling. Considering the complexity of the analyzed system and the goal of the present work, we simplified the system by not taking into account the thermal and electromagnetic phenomena. Based in the concept of hydraulic similitude, we performed an experimental study and a numerical modeling of the simplified model. The results of these two studies were compared and showed a good agreement. The results presented in this paper in conjunction with the previous work contribute to a better understanding of the hydrodynamics effects resulting from the interaction between the mechanical stirrer and air bubbling in the cold crucible heated by direct induction. Further works will take into account thermal and electromagnetic phenomena in the presence of mechanical stirrer and air bubbling. (authors)

  12. Results of the NASA/General Electric Experimental Clean Combustor Program

    NASA Technical Reports Server (NTRS)

    Gleason, C. C.; Niedzwiecki, R. W.

    1976-01-01

    The NASA/General Electric Experimental Clean Combustor Program is a multi-year, major contract effort. Primary program objectives are the generation of technology for development of advanced commercial CTOL engines with lower exhaust emissions than current aircraft and, demonstrations of this technology in a full-scale CF6-50C engine in 1976. This paper describes pollution and performance goals, Phase I and II test results and Phase III hardware, pollution sampling techniques and test plans. Pollution results are presented in emission index and Environmental Protection Agency 1979 Standard Parameters (EPAP). Best results were obtained with a double annular combustor concept. This concept, which incorporates multistage burning, produced EPAP values extrapolated to CF6-50C engine conditions for CO, HC, and NOx of 3.3, 0.3 and 4.5, respectively. These represent respective CO, HC and NOx percentage reductions of 69, 93 and 42%, compared to current CF6-50 engine values. The combustor also met development engine performance requirements.

  13. Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results

    NASA Astrophysics Data System (ADS)

    Botta, F.; Marx, N.; Gentili, S.; Schwingshackl, C. W.; Di Mare, L.; Cerri, G.; Dini, D.

    2012-04-01

    It is well known that the gas turbine blade vibrations can give rise to catastrophic failures and a reduction of the blades life because of fatigue related phenomena[1]-[3] . In last two decades, the adoption of piezoelectric elements, has received considerable attention by many researcher for its potential applicability to different areas of mechanical, aerospace, aeronautical and civil engineering. Recently, a number of studies of blades vibration control via piezoelectric plates and patches have been reported[4]-[6] . It was reported that the use of piezoelectric elements can be very effective in actively controlling vibrations. In one of their previous contributions[7] , the authors of the present manuscript studied a model to control the blade vibrations by piezoelectric elements and validated their results using a multi-physics finite elements package (COMSOL) and results from the literature. An optimal placement method of piezoelectric plate has been developed and applied to different loading scenarios for realistic configurations encountered in gas turbine blades. It has been demonstrated that the optimal placement depends on the spectrum of the load, so that segmented piezoelectric patches have been considered and, for different loads, an optimal combination of sequential and/or parallel actuation and control of the segments has been studied. In this paper, an experimental investigation carried out by the authors using a simplified beam configuration is reported and discussed. The test results obtained by the investigators are then compared with the numerical predictions [7] .

  14. Experimental results of the influence of ionic strength in liquid environment on fiber life

    NASA Astrophysics Data System (ADS)

    Overgaard, Jette V.

    1996-01-01

    Stress free corrosion such as chemical dissolution of silica optical fibers is normally assumed to be a pure pH dependent reaction. In our investigation we have found that it is not only the pH values that influence the lifetime of the fiber in water, but also the ionic strength of the water in contact with the fiber. We have seen that the lifetime of the normal dual coated fibers is severely reduced in seawater compared to the lifetime in deionized water. Carbon coated fibers show better results in these harsh conditions; but the experiments also demonstrate that the carbon coated fibers begin to fail before they have had a sufficient lifetime. A chemical explanation of the results, based on dissolution of glass in water and influence from the ions in question, is given. In this paper, experimental results from long term static fatigue tests on fibers in different liquid environments is shown. In the laboratory we have samples still living after almost four years in different environments. We have buffered water at pH values from 3 to 11, artificial seawater and deionized water. The fibers in the tests are both commercially available dual coated and carbon coated fibers and carbon coated test fibers.

  15. Large Fluorescence Enhancements of Fluorophore Ensembles with Multilayer Plasmonic Substrates: Comparison of Theory and Experimental Results

    PubMed Central

    Szmacinski, Henryk; Badugu, Ramachandram; Mahdavi, Farhad; Blair, Steve; Lakowicz, Joseph R.

    2013-01-01

    Multilayer substrates consisting of a glass slide, silver mirror, silica layer, and silver nanoparticles were fabricated using magnetron sputtering. This new geometry of substrates with backplane mirror and dielectric photonic cavity produced large average fluorescence enhancements up to 190-fold. Fluorescence enhancements of five fluorescent probes were measured over the broad spectral range from 470 to 800 nm. Fluorescent probes were streptavidin conjugates attached to the substrate surface through a layer of biotinylated bovine serum albumin. The protein layers represent a common surface modification for surface-based bioassays such as immunoassays or molecular diagnostic assays. We found that optimal enhancement is dependent on the thickness of the dielectric layer separating the silver mirror and the silver nanoparticles and on the spectral range. We performed numerical calculations for enhancement in both the excitation and emission using finite element method (FEM) the results of which were in qualitative agreement with the experimental results. The described method for fabrication multilayered substrates and the results obtained with protein layers demonstrate great potential for the design of simple and ultrasensitive fluorometric bioassays with large optical amplifications compared to the standard approaches of enzyme-based bioassays with dielectric surfaces. PMID:24163712

  16. Theoretical and experimental examination of recovery in the context of trueness of analytical results.

    PubMed

    Stafiński, Maciej; Wieczorek, Marcin; Janicki, Piotr; Kościelniak, Paweł

    2012-07-15

    In the report of the International Union of Pure and Applied Chemistry (IUPAC) estimation of analyte recovery (RV) is recommended as one of the ways for assessment of trueness of analytical results. RV is usually estimated with the use of samples spiked with known amount of analyte. However, neither the IUPAC guidelines, nor the available literature take into consideration various effects of different nature that may occur along the sample preparation steps prior and during measurements. Hence, in this work the attempt was made to classify these effects and to evaluate their influence on the analyte recovery. For this purpose a mathematical model has been developed, enabling to judge usefulness of the recovery test in objective estimation of trueness, and the results predicted by the model were checked experimentally. Trueness was estimated on the basis of analytical results obtained by both interpolative and extrapolative ways. The experiments were performed with the use of a dedicated flow injection system coupled to UV/VIS spectrometer and covered determination of chromium(III) as chromium(III) nitrate at a wavelength of 590nm. PMID:22817925

  17. An experimental investigation of multi-element airfoil ice accretion and resulting performance degradation

    NASA Technical Reports Server (NTRS)

    Potapczuk, Mark G.; Berkowitz, Brian M.

    1989-01-01

    An investigation of the ice accretion pattern and performance characteristics of a multi-element airfoil was undertaken in the NASA Lewis 6- by 9-Foot Icing Research Tunnel. Several configurations of main airfoil, slat, and flaps were employed to examine the effects of ice accretion and provide further experimental information for code validation purposes. The text matrix consisted of glaze, rime, and mixed icing conditions. Airflow and icing cloud conditions were set to correspond to those typical of the operating environment anticipated tor a commercial transport vehicle. Results obtained included ice profile tracings, photographs of the ice accretions, and force balance measurements obtained both during the accretion process and in a post-accretion evaluation over a range of angles of attack. The tracings and photographs indicated significant accretions on the slat leading edge, in gaps between slat or flaps and the main wing, on the flap leading-edge surfaces, and on flap lower surfaces. Force measurments indicate the possibility of severe performance degradation, especially near C sub Lmax, for both light and heavy ice accretion and performance analysis codes presently in use. The LEWICE code was used to evaluate the ice accretion shape developed during one of the rime ice tests. The actual ice shape was then evaluated, using a Navier-Strokes code, for changes in performance characteristics. These predicted results were compared to the measured results and indicate very good agreement.

  18. A stereo triangulation system for structural identification: Analytical and experimental results

    NASA Technical Reports Server (NTRS)

    Junkins, J. L.; James, G. H., III; Pollock, T. C.; Rahman, Z. H.

    1988-01-01

    , and have established conclusively the feasibility and desirability of this approach. We discuss, in summary, recent advances in analog and digital video processing methodology, actuation methods, and bring them to bear on the structural identification problem. We include a brief discussion of our experimental hardware and some recent experimental results which support the practical feasibility of this structural vibration sensing approach.

  19. Phase-space analysis and experimental results for secondary focusing at X-ray beamlines

    SciTech Connect

    Huang, Rong; Meron, Mati; Kujala, Naresh; Barrea, Raul A.

    2011-11-17

    Micro-focusing optical devices at synchrotron beamlines usually have a limited acceptance, but more flux can be intercepted if such optics are used to focus secondary sources created by the primary optics. Flux throughput can be maximized by placing the secondary focusing optics close to or exactly at the secondary source position. However, standard methods of beamline optics analysis, such as the lens equation or matching the mirror surface to an ellipse, work poorly when the source-to-optics distance is very short. In this paper the general characteristics of the focusing of beams with Gaussian profiles by a 'thin lens' are analysed under the paraxial approximation in phase space, concluding that the focusing of a beam with a short source-to-optics distance is distinct from imaging the source; slope errors are successfully included in all the formulas so that they can be used to calculate beamline focusing with good accuracy. A method is also introduced to use the thin-lens result to analyse the micro-focusing produced by an elliptically bent trapezoid-shaped Kirkpatrick-Baez mirror. The results of this analysis are in good agreement with ray-tracing simulations and are confirmed by the experimental results of the secondary focusing at the 18-ID Bio-CAT beamline (at the APS). The result of secondary focusing carried out at 18-ID using a single-bounce capillary can also be explained using this phase-space analysis. A discussion of the secondary focusing results is presented at the end of this paper.

  20. Synthesizing large-scale pyroclastic flows: Experimental design, scaling, and first results from PELE

    NASA Astrophysics Data System (ADS)

    Lube, G.; Breard, E. C. P.; Cronin, S. J.; Jones, J.

    2015-03-01

    Pyroclastic flow eruption large-scale experiment (PELE) is a large-scale facility for experimental studies of pyroclastic density currents (PDCs). It is used to generate high-energy currents involving 500-6500 m3 natural volcanic material and air that achieve velocities of 7-30 m s-1, flow thicknesses of 2-4.5 m, and runouts of >35 m. The experimental PDCs are synthesized by a controlled "eruption column collapse" of ash-lapilli suspensions onto an instrumented channel. The first set of experiments are documented here and used to elucidate the main flow regimes that influence PDC dynamic structure. Four phases are identified: (1) mixture acceleration during eruption column collapse, (2) column-slope impact, (3) PDC generation, and (4) ash cloud diffusion. The currents produced are fully turbulent flows and scale well to natural PDCs including small to large scales of turbulent transport. PELE is capable of generating short, pulsed, and sustained currents over periods of several tens of seconds, and dilute surge-like PDCs through to highly concentrated pyroclastic flow-like currents. The surge-like variants develop a basal <0.05 m thick regime of saltating/rolling particles and shifting sand waves, capped by a 2.5-4.5 m thick, turbulent suspension that grades upward to lower particle concentrations. Resulting deposits include stratified dunes, wavy and planar laminated beds, and thin ash cloud fall layers. Concentrated currents segregate into a dense basal underflow of <0.6 m thickness that remains aerated. This is capped by an upper ash cloud surge (1.5-3 m thick) with 100 to 10-4 vol % particles. Their deposits include stratified, massive, normally and reversely graded beds, lobate fronts, and laterally extensive veneer facies beyond channel margins.

  1. Responses of Tundra Ecosystems to Environmental Change: Observational and Experimental Results

    NASA Astrophysics Data System (ADS)

    Henry, G. H.

    2004-05-01

    Evidence of environmental changes due to human-enhanced climate warming continues to accumulate from polar regions. Responses in tundra and taiga ecosystems to climate changes have been variable because of the wide range in process response rates, from metabolic processes to adjustments in ecosystem carbon balance, and the variability in environmental settings across local to regional scales. For example, strong increases in rates of plant growth and changes in species composition and abundance have been observed in parts of the Low Arctic, but very little change has been measured in high arctic tundra. A dramatic increase in the cover of deciduous shrubs in areas of the western North American Arctic is predicted to result in positive feedbacks to soil temperature, through increased surface roughness and snow depth, and to atmospheric heating by reducing albedo. Increased shrub cover has also been found in long-term experimental warming studies conducted throughout the tundra biome as part of the International Tundra Experiment (ITEX). Warming is also affecting the carbon balance of tundra and taiga, which hold 25% of the soil carbon of global terrestrial ecosystems. However, trajectories of these changes are largely unknown for most northern systems, and differ because of initial conditions of the carbon and nutrient economy. Over the longer-term, the positive increases in plant growth may be constrained by negative feedbacks to nutrient cycling, as increases in C:N ratios of plant litter slow the release of nitrogen to soils. However, nitrogen availability has been shown to increase in response to short-term warming. In this presentation, I will review the responses of tundra ecosystems to climate variability and change, both through observational and experimental studies.

  2. Dynamics of Dual Prism Adaptation: Relating Novel Experimental Results to a Minimalistic Neural Model

    PubMed Central

    Arévalo, Orlando; Bornschlegl, Mona A.; Eberhardt, Sven; Ernst, Udo; Pawelzik, Klaus; Fahle, Manfred

    2013-01-01

    In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo–motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements (‘dual–adaptation’). A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual–adaptation be faster if switches (‘phase changes’) between the environments occur more frequently? We investigated the dynamics of dual–adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo–motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual–adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual–adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of

  3. Beryllium metal I. experimental results on acute oral toxicity, local skin and eye effects, and genotoxicity.

    PubMed

    Strupp, Christian

    2011-01-01

    The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral

  4. Dynamics of dual prism adaptation: relating novel experimental results to a minimalistic neural model.

    PubMed

    Arévalo, Orlando; Bornschlegl, Mona A; Eberhardt, Sven; Ernst, Udo; Pawelzik, Klaus; Fahle, Manfred

    2013-01-01

    In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo-motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements ('dual-adaptation'). A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual-adaptation be faster if switches ('phase changes') between the environments occur more frequently? We investigated the dynamics of dual-adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo-motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual-adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual-adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of prism adaptation, as

  5. Beryllium Metal I. Experimental Results on Acute Oral Toxicity, Local Skin and Eye Effects, and Genotoxicity

    PubMed Central

    Strupp, Christian

    2011-01-01

    The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral

  6. A study of water droplet between an AFM tip and a substrate using dissipative particle dynamics

    NASA Astrophysics Data System (ADS)

    Pal, Souvik; Lan, Chuanjin; Li, Zhen; Hirleman, E. Daniel; Ma, Yanbao

    2014-11-01

    Formation of a water droplet between a sharp AFM tip and a substrate due to capillary condensation affects the tip-substrate interaction. As a consequence, AFM measurements lose precision and often produce incorrect sample topology. Understanding the physics of liquid bridges is also important in the field of Dip-pen nanolithography (DPN). Significant research is being carried out to understand the mechanics of the formation of the liquid bridge and its dependence of surface properties, ambient conditions etc. The in-between length scale, i.e., mesoscale (~100 nm) associated with this phenomenon presents a steep challenge for experimental measurements. In addition, molecular dynamics (MD) can be computationally prohibitive to model the entire system, especially over microseconds to seconds. Theoretical analysis using Young Laplace equation has so far provided some qualitative insights only. We study this system using Dissipative Particle Dynamics (DPD) which is a simulation technique suitable for describing mesoscopic hydrodynamic behavior of fluids. In this work, we carry out simulations to improve understanding of the process of formation of the meniscus, the mechanics of manipulation and control of its shape, and better estimation of capillary forces. The knowledge gained through our study will help in correcting the AFM measurements affected by capillary condensation. Moreover, it will improve understanding of more accurate droplet manipulation in DPN.

  7. Ultrasharp high-aspect-ratio probe array for SECM and AFM Analysis

    NASA Astrophysics Data System (ADS)

    Tao, Ye; Fasching, Rainer J.; Prinz, Fritz B.

    2004-07-01

    A powerful experimental tool, ultra-sharp nano-electrode array is designed, fabricated and characterized. The application on a combination of Scanning Electrochemical Microscopy (SECM) and the Atomic Force Microcopy (AFM) is demonstrated. It can measure sample electrochemically initiated by SECM changes of topography while detecting topography using AFM. In order to realize this, a specialized probe system that is composed of a micro-mechanical bending structure necessary for the AFM mode and an electrochemical UME-tip required for a high performance SECM is crucial. The probe array is a row of silicon transducers embedded in silicon nitride cantilever array. The sharp high-aspect ratio (20:1) silicon tips are shaped and a thin layer of silicon nitride is deposited, which embeds the silicon tips in a silicon nitride layer so that they protrude through the nitride. Thus, the embedded silicon tips with a diameter less than 600 nm, the top radius less than 20 nm, and the aspect ratio as high as 20 can be achieved. A metal layer and an insulator layer are deposited on these tip structures to make each probe selectively conductive. Finally, cantilever structures are shaped and released by etching the silicon substrate from the backside. Electrochemical and impedance spectroscopic characterization show electrochemical functionality of the transducer system.

  8. Not so simple: a quasi-experimental study of how researchers adjudicate genetic research results

    PubMed Central

    Hayeems, Robin Zoe; Miller, Fiona Alice; Li, Li; Bytautas, Jessica Peace

    2011-01-01

    Ethicists contend that researchers are obliged to report genetic research findings to individual study participants when they are clinically significant, that is, when they are clinically useful or personally meaningful to participants. Yet whether such standards are well understood and can be consistently applied remains unknown. We conducted an international, cross-sectional survey of cystic fibrosis (CF) and autism genetics researchers using a quasi-experimental design to explore factors influencing researchers' judgments. Eighty percent of researchers agreed, in principle, that clinically significant findings should be reported to individual participants. Yet judgments about when a specific finding was considered clinically significant or warranted reporting varied by scientific factors (replication, robustness, intentionality, and disease context), capacity of the research team to explain the results, and type of research ethics guidance. Further, judgments were influenced by the researchers' disease community (autism or CF), their primary role (clinical, molecular, statistical) and their beliefs regarding a general reporting obligation. In sum, judgments about the clinical significance of genetic research results, and about whether they should be reported, are influenced by scientific parameters as well as contextual factors related to the specific research project and the individual researcher. These findings call into question the assumption that the conditions under which an obligation to disclose arises are uniformly understood and actionable. Adjudicating the clinical readiness of provisional data may be a responsibility better suited to evaluative experts at arms' length of the provisional data in question, rather than a responsibility imposed upon researchers themselves. PMID:21407262

  9. Quantitative Assessment of the CCMC's Experimental Real-time SWMF-Geospace Results

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael; Ganushkina, Natalia; De Zeeuw, Darren; Welling, Daniel; Toth, Gabor; Ilie, Raluca; Gombosi, Tamas; van der Holst, Bart; Kuznetsova, Maria; Maddox, Marlo; Rastaetter, Lutz

    2016-04-01

    Experimental real-time simulations of the Space Weather Modeling Framework (SWMF) are conducted at the Community Coordinated Modeling Center (CCMC), with results available there (http://ccmc.gsfc.nasa.gov/realtime.php), through the CCMC Integrated Space Weather Analysis (iSWA) site (http://iswa.ccmc.gsfc.nasa.gov/IswaSystemWebApp/), and the Michigan SWMF site (http://csem.engin.umich.edu/realtime). Presently, two configurations of the SWMF are running in real time at CCMC, both focusing on the geospace modules, using the BATS-R-US magnetohydrodynamic model, the Ridley Ionosphere Model, and with and without the Rice Convection Model for inner magnetospheric drift physics. While both have been running for several years, nearly continuous results are available since July 2015. Dst from the model output is compared against the Kyoto real-time Dst, in particular the daily minimum value of Dst to quantify the ability of the model to capture storms. Contingency tables are presented, showing that the run with the inner magnetosphere model is much better at reproducing storm-time values. For disturbances with a minimum Dst lower than -50 nT, this version yields a probability of event detection of 0.86 and a Heidke Skill Score of 0.60. In the other version of the SWMF, without the inner magnetospheric module included, the modeled Dst never dropped below -50 nT during the examined epoch.

  10. Experimental Results for Temporally Overlapping Pulses from Quantel EverGreen 200 Laser

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal

    2013-01-01

    This report will detail the experimental results and observations obtained while investigating the feasibility of temporally overlapping the two laser pulses from a Quantel EverGreen 200 Laser. This laser was specifically designed for Particle Imaging Velocimetry (PIV) applications and operate by emitting two 532 nm laser pulses that are seperated by an adjustable finite time (typically on the order of ten to hundreds of microseconds). However, the use of this model laser has found recent application for Pressure Sensitive Paint (PSP) testing, especially for rotorcraft research. For this testing, it is desired to only use one laser pulse. While this is easily done by only firing one of the laser heads, more excitation energy could conceivably be had if both laser heads are fired with zero pulse separation. In addition, recently large field-of-view PIV measurements have become possible and need ever increasing laser power to illuminate the larger areas. For this work, two different methods of timing the laser are investigated using both a traditional power meter to monitor laser power as well as a fast photodiode to determine pulse separation. The results are presented here as well as some simple implications for PIV experiments using these methods.

  11. A comparison of experimental results of soot production in laminar premixed flames

    NASA Astrophysics Data System (ADS)

    Caetano, Nattan R.; Soares, Diego; Nunes, Roger P.; Pereira, Fernando M.; Smith Schneider, Paulo; Vielmo, Horácio A.; van der Laan, Flávio Tadeu

    2015-05-01

    Soot emission has been the focus of numerous studies due to the numerous applications in industry, as well as the harmful effects caused to the environment. Thus, the purpose of this work is to analyze the soot formation in a flat flame burner using premixed compressed natural gas and air, where these quasi-adiabatic flames have one-dimensional characteristics. The measurements were performed applying the light extinction technique. The air/fuel equivalence ratiowas varied to assess the soot volume fractions for different flame configurations. Soot production along the flamewas also analyzed by measurements at different heights in relation to the burner surface. Results indicate that soot volume fraction increases with the equivalence ratio. The higher regions of the flamewere analyzed in order to map the soot distribution on these flames. The results are incorporated into the experimental database for measurement techniques calibration and for computational models validation of soot formation in methane premixed laminar flames, where the equivalence ratio ranging from 1.5 up to 8.

  12. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    NASA Astrophysics Data System (ADS)

    Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun; Zhou, Xiu-Wen; Yang, Yi

    2015-07-01

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ˜10 MA, 70 ns rise-time (10%-90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132-300 tungsten wires with 5-10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (˜50 TW) and total radiated energy (˜500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

  13. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    SciTech Connect

    Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun; Zhou, Xiu-Wen; Yang, Yi

    2015-07-15

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

  14. Using the Viking biology experimental results to obtain chemical information about Martian regolith

    NASA Technical Reports Server (NTRS)

    Plumb, Robert C.

    1992-01-01

    Although initially formulated as biology experiments, most of the results produced by the Viking Labeled Release (LR), Gas Exchange (GEX), and Pyrolytic Release (PR) experiments have been reproduced by chemical means. The experiments do not need more study as 'biological' phenomena, but they do deserve much more careful consideration from a chemical viewpoint. They are the only 'wet-chemical' experiments that scientists have performed on another planet, but they have not found very general use as sources of scientific information. There is a large set of potentially useful chemical observations, e.g., the three resolvable and precisely measured kinetic components of the release of C-14-labeled gases, the thermal sensitivity and magnitudes of the oxidation reaction(s) of the LR experiments, the kinetics and magnitude of the O2 and CO2 release of the GEX experiments, the thermal sensitivity of the GEX results, the differences between the thermal sensitivity of the GEX and the thermal sensitivity of the LR responses, and the kinetics and magnitudes of the LR successive injection reabsorption effect. It should be possible to test many chemical aspects of hypothetical martian phenomena in experiments using the biology experimental configurations and derive much valuable information by comparisons with the Viking observations.

  15. COMPARISON OF EXPERIMENTAL RESULTS TO CFD MODELS FOR BLENDING IN A TANK USING DUAL OPPOSING JETS

    SciTech Connect

    Leishear, R.

    2011-08-07

    Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1- 4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.

  16. Thermodiffusion in concentrated ferrofluids: Experimental and numerical results on magnetic thermodiffusion

    SciTech Connect

    Sprenger, Lisa Lange, Adrian; Odenbach, Stefan

    2014-02-15

    Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: S{sub T‖} = −0.152 K{sup −1} and S{sub T⊥} = −0.257 K{sup −1} at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ{sub ‖} and ξ{sub ⊥} used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field, the parameter can

  17. Modal characterization of the ASCIE segmented optics testbed: New algorithms and experimental results

    NASA Technical Reports Server (NTRS)

    Carrier, Alain C.; Aubrun, Jean-Noel

    1993-01-01

    New frequency response measurement procedures, on-line modal tuning techniques, and off-line modal identification algorithms are developed and applied to the modal identification of the Advanced Structures/Controls Integrated Experiment (ASCIE), a generic segmented optics telescope test-bed representative of future complex space structures. The frequency response measurement procedure uses all the actuators simultaneously to excite the structure and all the sensors to measure the structural response so that all the transfer functions are measured simultaneously. Structural responses to sinusoidal excitations are measured and analyzed to calculate spectral responses. The spectral responses in turn are analyzed as the spectral data become available and, which is new, the results are used to maintain high quality measurements. Data acquisition, processing, and checking procedures are fully automated. As the acquisition of the frequency response progresses, an on-line algorithm keeps track of the actuator force distribution that maximizes the structural response to automatically tune to a structural mode when approaching a resonant frequency. This tuning is insensitive to delays, ill-conditioning, and nonproportional damping. Experimental results show that is useful for modal surveys even in high modal density regions. For thorough modeling, a constructive procedure is proposed to identify the dynamics of a complex system from its frequency response with the minimization of a least-squares cost function as a desirable objective. This procedure relies on off-line modal separation algorithms to extract modal information and on least-squares parameter subset optimization to combine the modal results and globally fit the modal parameters to the measured data. The modal separation algorithms resolved modal density of 5 modes/Hz in the ASCIE experiment. They promise to be useful in many challenging applications.

  18. Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results

    SciTech Connect

    Li, Y.Y.

    1997-01-01

    The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243{degrees}C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling.

  19. AFM-based force microsensor for a microrobot

    NASA Astrophysics Data System (ADS)

    Fatikow, Sergej; Fahlbusch, Stephan

    2001-10-01

    Microrobots are the result of increasing research activities at the border between microsystem technology and robotics. Today already, robots with dimensions of a few cubic- centimeters can be developed. Like conventional robots, microrobots represent a complex system that usually contains several different types of actuators and sensors. The measurement of gripping forces is the most important sensor application in micromanipulation besides visual servoing to protect the parts from too high surface pressures and thereby damage during the assembly process. Very small forces in the range of 200 (mu) N down to 0.1 (mu) N or even less have to be sensed. Thus, the aim of our current research activities is the development of a high-resolution integrated force microsensor for measuring gripping forces in a microhandling robot. On the one hand, the sensor should be a device for teleoperated manipulation tasks in a flexible microhandling station. On the other hand, typical microhandling operations should to a large extend be automated with the aid of computer-based signal processing of sensor information. The user should be provided with an interface for teleoperated manipulation and an interface for partially automated manipulation of microobjects. In this paper, a concept for the measurement of gripping forces in microrobotics using piezoresistive AFM (atomic force microscope) cantilevers is introduced. Further on, the concept of a microrobot-based SEM station and its applications are presented.

  20. Nanoscopic polypyrrole AFM-SECM probes enabling force measurements under potential control

    NASA Astrophysics Data System (ADS)

    Knittel, P.; Higgins, M. J.; Kranz, C.

    2014-01-01

    Conductive polymers, and in particular polypyrrole, are frequently used as biomimetic interfaces facilitating growth and/or differentiation of cells and tissues. Hence, studying forces and local interactions between such polymer interfaces and cells at the nanoscale is of particular interest. Frequently, such force interactions are not directly accessible with high spatial resolution. Consequently, we have developed nanoscopic polypyrrole electrodes, which are integrated in AFM-SECM probes. Bifunctional AFM-SECM probes were modified via ion beam-induced deposition resulting in pyramidal conductive Pt-C composite electrodes. These nanoscopic electrodes then enabled localized polypyrrole deposition, thus resulting in polymer-modified AFM probes with a well-defined geometry. Furthermore, such probes may be reversibly switched from an insulating to a conductive state. In addition, the hydrophilicity of such polymer tips is dependent on the dopant, and hence, on the oxidation state. Force studies applying different tip potentials were performed at plasma-treated glass surfaces providing localized information on the associated force interactions, which are dependent on the applied potential and the dopant.Conductive polymers, and in particular polypyrrole, are frequently used as biomimetic interfaces facilitating growth and/or differentiation of cells and tissues. Hence, studying forces and local interactions between such polymer interfaces and cells at the nanoscale is of particular interest. Frequently, such force interactions are not directly accessible with high spatial resolution. Consequently, we have developed nanoscopic polypyrrole electrodes, which are integrated in AFM-SECM probes. Bifunctional AFM-SECM probes were modified via ion beam-induced deposition resulting in pyramidal conductive Pt-C composite electrodes. These nanoscopic electrodes then enabled localized polypyrrole deposition, thus resulting in polymer-modified AFM probes with a well

  1. Experimental Results from the Thermal Energy Storage-2 (TES-2) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Tolbert, Carol

    2000-01-01

    Thermal Energy Storage-2 (TES-2) is a flight experiment that flew on the Space Shuttle Endeavour (STS-72), in January 1996. TES-2 originally flew with TES-1 as part of the OAST-2 Hitchhiker payload on the Space Shuttle Columbia (STS-62) in early 1994. The two experiments, TES-1 and TES-2 were identical except for the fluoride salts to be characterized. TES-1 provided data on lithium fluoride (LiF), TES-2 provided data on a fluoride eutectic (LiF/CaF2). Each experiment was a complex autonomous payload in a Get-Away-Special payload canister. TES-1 operated flawlessly for 22 hr. Results were reported in a paper entitled, Effect of Microgravity on Materials Undergoing Melting and Freezing-The TES Experiment, by David Namkoong et al. A software failure in TES-2 caused its shutdown after 4 sec of operation. TES-1 and 2 were the first experiments in a four experiment suite designed to provide data for understanding the long duration microgravity behavior of thermal energy storage salts that undergo repeated melting and freezing. Such data have never been obtained before and have direct application for the development of space-based solar dynamic (SD) power systems. These power systems will store energy in a thermal energy salt such as lithium fluoride or a eutectic of lithium fluoride/calcium difluoride. The stored energy is extracted during the shade portion of the orbit. This enables the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes were developed for predicting performance of a space-based solar dynamic power system. Experimental verification of the analytical predictions were needed prior to using the analytical results for future space power design applications. The four TES flight experiments were to be used to obtain the needed experimental data. This paper will address the flight results from the first and second experiments, TES-1 and 2, in comparison to the predicted results from the Thermal

  2. AFM of biological complexes: what can we learn?

    PubMed Central

    Gaczynska, Maria; Osmulski, Pawel A.

    2009-01-01

    The term “biological complexes” broadly encompasses particles as diverse as multisubunit enzymes, viral capsids, transport cages, molecular nets, ribosomes, nucleosomes, biological membrane components and amyloids. The complexes represent a broad range of stability and composition. Atomic force microscopy offers a wealth of structural and functional data about such assemblies. For this review, we choose to comment on the significance of AFM to study various aspects of biology of selected nonmembrane protein assemblies. Such particles are large enough to reveal many structural details under the AFM probe. Importantly, the specific advantages of the method allow for gathering dynamic information about their formation, stability or allosteric structural changes critical for their function. Some of them have already found their way to nanomedical or nanotechnological applications. Here we present examples of studies where the AFM provided pioneering information about the biology of complexes, and examples of studies where the simplicity of the method is used toward the development of potential diagnostic applications. PMID:19802337

  3. Improvement in metrology on new 3D-AFM platform

    NASA Astrophysics Data System (ADS)

    Schmitz, Ingo; Osborn, Marc; Hand, Sean; Chen, Qi

    2008-10-01

    According to the 2007 edition of the ITRS roadmap, the requirement for CD uniformity of isolated lines on a binary or attenuated phase shift mask is 2.1nm (3σ) in 2008 and requires improvement to1.3 nm (3σ) in 2010. In order to meet the increasing demand for CD uniformity on photo masks, improved CD metrology is required. A next generation AFM, InSightTM 3DAFM, has been developed to meet these increased requirements for advanced photo mask metrology. The new system achieves 2X improvement in CD and depth precision on advanced photo masks features over the previous generation 3D-AFM. This paper provides measurement data including depth, CD, and sidewall angle metrology. In addition the unique capabilities of damage-free defect inspection and Nanoimprint characterization by 3D AFM are presented.

  4. Active behavior of abdominal wall muscles: Experimental results and numerical model formulation.

    PubMed

    Grasa, J; Sierra, M; Lauzeral, N; Muñoz, M J; Miana-Mena, F J; Calvo, B

    2016-08-01

    In the present study a computational finite element technique is proposed to simulate the mechanical response of muscles in the abdominal wall. This technique considers the active behavior of the tissue taking into account both collagen and muscle fiber directions. In an attempt to obtain the computational response as close as possible to real muscles, the parameters needed to adjust the mathematical formulation were determined from in vitro experimental tests. Experiments were conducted on male New Zealand White rabbits (2047±34g) and the active properties of three different muscles: Rectus Abdominis, External Oblique and multi-layered samples formed by three muscles (External Oblique, Internal Oblique, and Transversus Abdominis) were characterized. The parameters obtained for each muscle were incorporated into a finite strain formulation to simulate active behavior of muscles incorporating the anisotropy of the tissue. The results show the potential of the model to predict the anisotropic behavior of the tissue associated to fibers and how this influences on the strain, stress and generated force during an isometric contraction. PMID:27111629

  5. The dependence of ultrasonic backscatter on trabecular thickness in human calcaneus: theoretical and experimental results.

    PubMed

    Wear, Keith A; Laib, Andres

    2003-08-01

    Trabecular thickness within cancellous bone is an important determinant of osteoporotic fracture risk. Noninvasive assessment of trabecular thickness potentially could yield useful diagnostic information. Faran's theory of elastic scattering from a cylindrical object immersed in a fluid has been used to predict the dependence of ultrasonic backscatter on trabecular thickness. The theory predicts that, in the range of morphological and material properties expected for trabecular bone, the backscatter coefficient at 500 kHz should be approximately proportional to trabecular thickness to the power of 2.9. Experimental measurements of backscatter coefficient were performed on 43 human calcaneus samples in vitro. Mean trabecular thicknesses on the 43 samples were assessed using micro computed tomography (CT). A power law fit to the data showed that the backscatter coefficient empirically varied as trabecular thickness to the 2.8 power. The 95% confidence interval for this exponent was 1.7 to 3.9. The square of the correlation coefficient for the linear regression to the log transformed data was 0.40. This suggests that 40% of variations in backscatter may be attributed to variations in trabecular thickness. These results reinforce previous studies that offered validation for the Faran cylinder model for prediction of scattering properties of cancellous bone, and provide added evidence for the potential diagnostic utility of the backscatter measurement. PMID:12952089

  6. First Experimental Results with a New Type of Stent: The Double-Coil Device

    SciTech Connect

    Strecker, Ernst-Peter Song, Ho-Young; Kang, Sung-Gwon; Hou Dongming; Schumacher, M.

    2003-06-15

    Purpose: To introduce a new stent design and evaluate its technical properties. Methods: This stent consists of two nitinol wires partially connected to each other.After delivery through a catheter a tube-like helical stent forms within the artery. After experimental tests in flow models regarding mechanical properties, introduction and delivery technique, 15 stents were implanted into iliac, femoral, and carotid arteries of seven dogs.After 3-12 weeks angiographic follow-up stents were explanted for microscopic examination. Results: Stents with expanded diameters of 5-10 mm can be introduced through a 5 Fr catheter with 0.038 inch luminal diameter. Thrombotic vessel occlusion was observed in one iliac artery after incorrect stent placement with diameter mismatch. Fourteen of 15 stents remained patent and revealed minor intimal hyperplasia in the areas of the stent strut connection points as well as some reduction in medial thickness. Conclusion: This new stent design has a small introduction diameter which is independent of the expanded diameter. The stent's principal characteristics may serve as a basis for further special developments.

  7. Two-dimensional discrete element models of debris avalanches: Parameterization and the reproducibility of experimental results

    NASA Astrophysics Data System (ADS)

    Banton, J.; Villard, P.; Jongmans, D.; Scavia, C.

    2009-11-01

    Application of the discrete element method (DEM) to model avalanches of granular materials requires determining the correct geometric and rheological parameters for and between the particles as well as for the basal surface. The use of spherical (circular in 2-D) particles enhances particle rolling, yielding excessive runout values. The solution usually adopted to correct this effect is to introduce a drag force which artificially slows down the particle velocities. The aim of this study is to test the capability of the DEM to simulate well-controlled unsteady channelized granular flows, considering the measured properties of the particles and of the basal surface which naturally contribute to dissipate energy. We first performed a parametrical analysis on a simple 2-D model in order to estimate the influence of particle shape, friction parameters, and restitution coefficients on the dynamics of the flow and on the deposit geometry. We then simulated three channelized laboratory experiments performed with two materials and two bed linings. Using the geometrical layout and the values of the mechanical parameters provided by the authors, we obtained a remarkable agreement between the observed and 2-D simulated deposit shapes for the three experiments. Also, the computed mass evolution with time was very consistent with the experimental snapshots in all cases. These results highlight the capability of the DEM technique for modeling avalanche of granular material when the particle shape as well as the friction and restitution coefficients are properly considered.

  8. Inhibiting diffusion of complex contagions in social networks: theoretical and experimental results

    PubMed Central

    Anil Kumar, V.S.; Marathe, Madhav V.; Ravi, S.S.; Rosenkrantz, Daniel J.

    2014-01-01

    We consider the problem of inhibiting undesirable contagions (e.g. rumors, spread of mob behavior) in social networks. Much of the work in this context has been carried out under the 1-threshold model, where diffusion occurs when a node has just one neighbor with the contagion. We study the problem of inhibiting more complex contagions in social networks where nodes may have thresholds larger than 1. The goal is to minimize the propagation of the contagion by removing a small number of nodes (called critical nodes) from the network. We study several versions of this problem and prove that, in general, they cannot even be efficiently approximated to within any factor ρ ≥ 1, unless P = NP. We develop efficient and practical heuristics for these problems and carry out an experimental study of their performance on three well known social networks, namely epinions, wikipedia and slashdot. Our results show that these heuristics perform significantly better than five other known methods. We also establish an efficiently computable upper bound on the number of nodes to which a contagion can spread and evaluate this bound on many real and synthetic networks. PMID:25750583

  9. Experimental results on the thermal contact resistance of G-10CR composites at cryogenic temperatures

    SciTech Connect

    Phelan, P.E.; Mei, S.

    1999-07-01

    The composite material G-10CR, an epoxy resin laminate reinforced with glass filaments, is widely used in cryogenic structures, especially where thermal insulation is required. The thermal contact resistance, or its inverse, the thermal contact conductance, at a G-10CR/G-10CR interface has not previously been investigated at cryogenic temperatures. Consequently, an experimental apparatus was designed and constructed to permit measurements of the thermal contact conductance over a temperature range from 10 to 300 K, while enabling a controlled contact pressure to be applied. Such measurements for these composite materials indicated that the fiber orientation, plays a crucial role in determining the thermal contact conductance, which is greatest in the warp direction, where the glass fibers offer a high-thermal-conductance path for heat flow in parallel to the epoxy matrix. Typical results demonstrating the effect of fiber orientation on thermal contact conductance are displayed. The dimensionless contact conductance was shown to vary with dimensionless contact pressure with a power-law exponent near 0.28, in broad agreement with other data reported for graphite fiber composites.

  10. Male physical aggression as a function of alcohol intoxication and frustration: experimental results and methodological considerations.

    PubMed

    Gustafson, R

    1991-03-01

    Forty-five undergraduate students were assigned to either an Alcohol, a Placebo, or a Control group. The alcohol dose was 0.80 g of 100% alcohol/kg body weight. Subjects were informed that they could win a sum of money depending on the performance of a partner. They then supervised the partner over a series of trials on a visual scan test and could influence the partner by either giving an uncomfortable electric shock (aggressive alternative) or a comfortable vibration (nonaggressive alternative) at each incorrect response from the partner. Both alternatives were said to be equally instrumental in reaching the goal of winning the money and both could be varied in intensity on a 10-point scale and without limits in terms of duration. Aggression was measured as number of aggressive responses chosen, and in terms of intensity and duration. Nonaggression was measured in terms of intensity and duration. Intoxicated subjects did not increase their aggression but all groups chose significantly more nonaggressive responses and did so with higher intensity and duration. Frustration did not significantly affect these types of responding. Results are discussed in terms of methodological considerations and the importance of using realistic experimental paradigms is stressed. Also, theoretical implications are discussed. PMID:2058788

  11. Experimental Results From a 2kW Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David; Mason, Lee; Birchenough, Arthur

    2003-01-01

    This paper presents experimental test results from operation of a 2 kWe Brayton power conversion unit. The Brayton converter was developed for a solar dynamic power system flight experiment planned for the Mir Space Station in 1997. The flight experiment was cancelled, but the converter was tested at Glenn Research Center as part of the Solar Dynamic Ground Test Demonstration system which included a solar concentrator, heat receiver, and space radiator. In preparation for the current testing, the heat receiver was removed and replaced with an electrical resistance heater, simulating the thermal input of a steady-state nuclear source. The converter was operated over a full range of thermal input power levels and rotor speeds to generate an overall performance map. The converter unit will serve as the centerpiece of a Nuclear Electric Propulsion Testbed at Glenn. Future potential uses for the Testbed include high voltage electrical controller development, integrated electric thruster testing and advanced radiator demonstration testing to help guide high power Brayton technology development for Nuclear Electric Propulsion (NEP).

  12. Joint computational/experimental aerodynamics research on a reentry vehicle: Part 2, Computational results

    SciTech Connect

    Walker, M.M.; Oberkampf, W.L.

    1990-01-01

    Computational aerodynamics simulation applied to supersonic and hypersonic flight vehicles has significantly increased during the last several years. Flow field simulations have been computed for a wide variety of vehicles from ballistic reentry vehicles to the Space Shuttle. Although computational aerodynamics simulation has been taking more responsibility during this time, wind tunnel experimentation has continued to play the major role in flight vehicle analysis and design. This role, however, is changing because of the great strides in the capability and confidence in numerical simulations. In this paper computational results are obtained for a spherically blunted cone with a slice parallel to the cone axis. Aerodynamic force and moment predictions from Sandia's CFD codes are compared with wind tunnel data from the Sandia Mach 8 hypersonic wind tunnel. These comparisons are made on a sliced reentry vehicle both with and without a windward flap. The windward flap will be deflected 10{degree}, 20{degree}, and 30{degree}. Inviscid/boundary layer codes and the Parabolized Navier-Stokes code are used to generate solutions for the sliced vehicle. In the region of the flap, some reversed flow is apparent and a full Navier-Stokes code will be used to provide comparisons with the data. Force and moment and surface flow visualization comparisons are made for laminar, ideal gas flow. This will be the first of a series of papers providing comparisons with the Sandia wind tunnel data. Additional papers will report comparisons with surface pressure measurements. 21 refs., 9 figs., 1 tab.

  13. Optimal piezoelectric beam shape for single and broadband vibration energy harvesting: Modeling, simulation and experimental results

    NASA Astrophysics Data System (ADS)

    Muthalif, Asan G. A.; Nordin, N. H. Diyana

    2015-03-01

    Harvesting energy from the surroundings has become a new trend in saving our environment. Among the established ones are solar panels, wind turbines and hydroelectric generators which have successfully grown in meeting the world's energy demand. However, for low powered electronic devices; especially when being placed in a remote area, micro scale energy harvesting is preferable. One of the popular methods is via vibration energy scavenging which converts mechanical energy (from vibration) to electrical energy by the effect of coupling between mechanical variables and electric or magnetic fields. As the voltage generated greatly depends on the geometry and size of the piezoelectric material, there is a need to define an optimum shape and configuration of the piezoelectric energy scavenger. In this research, mathematical derivations for unimorph piezoelectric energy harvester are presented. Simulation is done using MATLAB and COMSOL Multiphysics software to study the effect of varying the length and shape of the beam to the generated voltage. Experimental results comparing triangular and rectangular shaped piezoelectric beam are also presented.

  14. Experimental Results From Stitched Composite Multi-Bay Fuselage Panels Tested Under Uni-Axial Compression

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.

    2004-01-01

    The experimental results from two stitched VARTM composite panels tested under uni-axial compression loading are presented. The curved panels are divided by frames and stringers into five or six bays with a column of three bays along the compressive loading direction. The frames are supported at the ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field measurement technique that utilizes a camera-based-stero-vision system was used to record displacements. The panels were loaded in increments to determine the first bay to buckle. Loading was discontinued at limit load and the panels were removed from the test machine for impact testing. After impacting at 20 ft-lbs to 25 ft-lbs of energy with a spherical indenter, the panels were loaded in compression until failure. Impact testing reduced the axial stiffness 4 percent and less than 1 percent. Postbuckled axial panel stiffness was 52 percent and 70 percent of the pre-buckled stiffness.

  15. Optimization of MCAO performances: experimental results on ONERA laboratory MCAO bench

    NASA Astrophysics Data System (ADS)

    Costille, Anne; Petit, Cyril; Conan, Jean-Marc; Fusco, Thierry; Kulcsár, Caroline; Raynaud, Henri-François

    2008-07-01

    Classic Adaptive Optics (AO) is now a proven technique to correct turbulence on earth based astronomical telescopes. The corrected field of view is however limited by the anisoplanatism effect. Multi-Conjugate AO (MCAO) aims at providing a wide field of view correction through the use of several deformable mirrors and of multi-guide-star wavefront sensing. However the performance optimization of such complex systems raises new questions in terms of calibration and control. We present our current developments on performance optimization of MCAO systems. We show that performance can be significantly improved with tomographic control based on Linear Quadratic Gaussian control, compared with more standard methods. An experimental demonstration of this new approach is going to be implemented on HOMER, the recent bench developed at ONERA devoted to MCAO laboratory research. We present here results in closed-loop in AO, GLAO and MCAO with an integrator control. This bench implements two deformable mirrors and a wide field Shack-Hartman wavefront sensor.

  16. Experimental Results of High Pressure and High Strain Rate Tantalum Flow Stress on Omega and NIF

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Arsenlis, A.; Barton, N.; Benedetti, L.; Huntington, C.; McNaney, J.; Orlikowski, D.; Prisbrey, S.; Remington, B.; Rudd, R.; Swift, D.; Weber, S.; Wehrenberg, C.; Comley, A.

    2015-11-01

    Understanding the high pressure, high strain rate plastic deformation dynamics of materials is an area of research of high interest to planetary formation dynamics, meteor impact dynamics, and inertial confinement fusion designs. Developing predictive theoretical and computational descriptions of such systems, however, has been a difficult undertaking. We have performed many experiments on Omega, LCLS and NIF to test Ta strength models at high pressures (~ up to 4 Mbar), high strain rates (~ 107 s-1) and high strains (>30%) under ramped compression conditions using Rayleigh-Taylor and Richtmyer-Meshkov instability properties. These experiments use plasma drive to ramp compress the sample to higher pressure without shock-melting. We also studied lattice level strength mechanisms under shocked compression using a diffraction-based technique. Our studies show that the strength mechanisms from macro to micro scales are different from the traditional strength model predictions and that they are loading path dependent. We will report the experimental results. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  17. Preparation, conduct, and experimental results of the AVR loss-of-coolant accident simulation test

    SciTech Connect

    Kruger, K.; Bergerfurth, A.; Burger, S.; Pohl, P.; Wimmers, M. ); Cleveland, J.C. )

    1991-02-01

    A loss-of-coolant accident (LOCA) is one of the most severe accidents for a nuclear power plant. To demonstrate inherent safety characteristics incorporated into small high-temperature gas-cooled reactor (HTGR) design, LOCA simulation tests have been conducted at the Arbeitsgemeinschaft Versuchsreaktor (AVR), the German pebble-bed-high-temperature reactor plant. The AVR is the only nuclear power plant ever to have been intentionally subjected to LOCA conditions without emergency cooling. This paper presents the planning and licensing activities including pretest predictions performed for the LOCA test are described, and the conduct of the test and experimental results. The LOCA test was planned to create conditions that would exist if a rapid LOCA occurred with the reactor operating at full power. The test demonstrated this reactor's safe response to an accident in which the coolant escapes from the reactor core and no emergency system is available to provide coolant flow to the core. The test is of special interest because it demonstrates the inherent safety features incorporated into optimized modular HTGR designs. The main LOCA test lasted for 5 days. After the test began, core temperatures increased for {approx}13 h and then gradually and continually decreased as the rate of heat dissipation from the core exceeded the simulated decay power. Throughout the test, temperatures remained below limiting values for the core and other reactor components.

  18. Vibrational reduction in integral-damped composite fan blades: experimental results

    NASA Astrophysics Data System (ADS)

    Kosmatka, John B.; Mehmed, Oral

    1998-06-01

    The experimental behavior of spinning laminated composite pretwisted plates (turbo-fan blade-like) with small (less than 10% by volume) integral viscoelastic damping patches is investigated. Two different plate sets were examined. The first set investigated tailoring patch locations and definitions to damp specific modes on spinning flat graphite/epoxy plates as a function of rotational speed. The second set investigated damping patch size and location on specific modes of pretwisted (30 degrees) graphite/epoxy plates. The results reveal that: (1) significant amount of damping can be added using a small amount of damping material, (2) the damped plates experienced no failures up to the tested 28,000 g's and 750,000 cycles, (3) centrifugal loads caused an increase in bending frequencies and corresponding reductions in bending damping levels that are proportional to the bending stiffness increase, and (4) the centrifugal loads caused a decrease in torsion natural frequency and increase in damping levels of pretwisted composite plates.

  19. Experimental results performed in the framework of the HIPER European Project

    NASA Astrophysics Data System (ADS)

    Batani, D.; Koenig, M.; Baton, S.; Perez, F.; Gizzi, L. A.; Koester, P.; Labate, L.; Honrubia, J.; Debayle, A.; Santos, J.; Schurtz, G.; Hulin, S.; Ribeyre, X.; Fourment, C.; Nicolai, P.; Vauzour, B.; Gremillet, L.; Nazarov, W.; Pasley, J.; Tallents, G.; Richetta, M.; Lancaster, K.; Spindloe, Ch.; Tolley, M.; Neely, D.; Norreys, P.; Kozlova, M.; Nejdl, J.; Rus, B.; Antonelli, L.; Morace, A.; Volpe, L.,; Davies, J.; Wolowski, J.; Badziak, J.

    2011-06-01

    This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to "Advanced Ignition Schemes", i.e. the Fast Ignition and the Shock Ignition Approaches to Inertial Fusion. Such schemes are aimed at achieving a higher gain, as compared to the classical approach which is used in NIF, as required for future reactors, and making fusion possible with smaller facilities. In particular, a series of experiments related to Fast Ignition were performed at the RAL (UK) and LULI, France) Laboratories and were addressed to study the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser-plasma coupling in the 1016 W/cm2 intensity regime of interest for Shock Ignition.

  20. Non-Shock Initiation Model for Plastic Bonded Explosive PBXN-5 and Cast Explosive: Experimental Results

    NASA Astrophysics Data System (ADS)

    Anderson, Mark; Todd, Steven; Caipen, Terry; Jensen, Charlie; Hughs, Chance

    2009-06-01

    A damage initiated reaction (DMGIR) computational model is being developed for the CTH shock physics code to predict the response of an explosive to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of reaction in the explosive, and its growth to detonation. The DMGIR model is a complement to the History Variable Reactive Burn (HVRB) model embedded in the current CTH code. Specifically designed experiments are supporting the development, implementation, and validation of the DMGIR numerical approach. PBXN-5 was the initial explosive material used experimentally to develop the DMGIR model. This explosive represents a family of plastically bonded explosives with good mechanical strength and rigid body properties. The model has been extended to cast explosives represented by Composition B. Furthermore, the DMGIR model will extended to predict results of non-shock mechanical insults for moldable plastic explosives such as C4 and PrimaSheet.