Experimental characterization of the effects induced by passive plasma lens on high brightness electron bunches

NASA Astrophysics Data System (ADS)

Marocchino, A.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Bini, S.; Bisesto, F.; Brentegani, E.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Giribono, A.; Lollo, V.; Marongiu, M.; Mostacci, A.; Di Pirro, G.; Pompili, R.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

2017-10-01

We report on the experimental characterization of the effect that a passive plasma lens in the overdense regime has on high-brightness bunch quality by means of 6D phase-space analysis. The passive lens is generated by confining hydrogen gas with a capillary tube pre-ionized with a high-voltage discharge. We observed that the optimum condition is retrieved at the end of the overdense regime with almost no effect on bunch brightness. The presence of gas jets, leaking from the hollow capillary end-points, extends the lens effects also outside of the capillary, resulting in longer focusing channels. Experimental results are supported with numerical simulations of the complete accelerator line together with the plasma channel section.

Opto-electronic characterization of third-generation solar cells.

PubMed

Neukom, Martin; Züfle, Simon; Jenatsch, Sandra; Ruhstaller, Beat

2018-01-01

We present an overview of opto-electronic characterization techniques for solar cells including light-induced charge extraction by linearly increasing voltage, impedance spectroscopy, transient photovoltage, charge extraction and more. Guidelines for the interpretation of experimental results are derived based on charge drift-diffusion simulations of solar cells with common performance limitations. It is investigated how nonidealities like charge injection barriers, traps and low mobilities among others manifest themselves in each of the studied cell characterization techniques. Moreover, comprehensive parameter extraction for an organic bulk-heterojunction solar cell comprising PCDTBT:PC 70 BM is demonstrated. The simulations reproduce measured results of 9 different experimental techniques. Parameter correlation is minimized due to the combination of various techniques. Thereby a route to comprehensive and accurate parameter extraction is identified.

Characterization of a Laser-Generated Perturbation in High-Speed Flow for Receptivity Studies

NASA Technical Reports Server (NTRS)

Chou, Amanda; Schneider, Steven P.; Kegerise, Michael A.

2014-01-01

A better understanding of receptivity can contribute to the development of an amplitude-based method of transition prediction. This type of prediction model would incorporate more physics than the semi-empirical methods, which are widely used. The experimental study of receptivity requires a characterization of the external disturbances and a study of their effect on the boundary layer instabilities. Characterization measurements for a laser-generated perturbation were made in two different wind tunnels. These measurements were made with hot-wire probes, optical techniques, and pressure transducer probes. Existing methods all have their limitations, so better measurements will require the development of new instrumentation. Nevertheless, the freestream laser-generated perturbation has been shown to be about 6 mm in diameter at a static density of about 0.045 kg/cubic m. The amplitude of the perturbation is large, which may be unsuitable for the study of linear growth.

LABORATORY ANALYSES OF CORONA DISCHARGES

EPA Science Inventory

The paper discusses an experimental research program to characterize corona generation from different electrode geometries in a range of conditions comparable to those found in electrostatic precipitators (ESPs). A wire-parallel plate device and a wire-cylinder device were used t...

LABORATORY ANALYSIS OF BACK-CORONA DISCHARGE

EPA Science Inventory

The paper discusses an experimental research program to characterize back-corona generation and behavior in a range of environments and geometries common to electrostatic precipitators (ESPs). A wire-parallel plate device was used to monitor the intensity and distribution of back...

Liquid-in-gas droplet microfluidics; experimental characterization of droplet morphology, generation frequency, and monodispersity in a flow-focusing microfluidic device

NASA Astrophysics Data System (ADS)

Tirandazi, Pooyan; Hidrovo, Carlos H.

2017-07-01

Microfluidic techniques for production of uniform droplets usually rely on the use of two immiscible liquids (e.g. water-in-oil emulsions). It has been shown recently that a continuous gas flow instead of a second liquid carrier can be used as an alternative approach in droplet microfluidics. In this work we experimentally investigate the generation of liquid water droplets within air in flow-focusing configurations. Over a wide range of flow conditions we identify six distinct flow regimes inside the microchannel: Co-flowing, Threading, Plugging, Dripping, Multi-Satellite Formation, and Jetting. Flow regimes and their transitions are plotted and characterized based on the Weber number (We) of the system. We further investigate the impact of liquid microchannel size on the flow maps. Generation frequency, morphology, and monodispersity of the droplets are characterized in more detail in the Dripping regime. Generation frequency can be related to the product of the liquid and gas flow rates. However, droplet morphology (length and width) is more dependent on the gas flow rate. We demonstrate the production of monodisperse droplets (d < 100 µm and σ/d < 5 %) up to kHz formation rates in liquid-gas microfluidic systems for the first time. The results of this work provide practical and useful guidelines for precise, oil-free delivery of ultra-small volumes of fluid which can be integrated in lab-on-a-chip systems for a variety of applications in biochemical research and material synthesis.

Three key regimes of single pulse generation per round trip of all-normal-dispersion fiber lasers mode-locked with nonlinear polarization rotation.

PubMed

Smirnov, Sergey; Kobtsev, Sergey; Kukarin, Sergey; Ivanenko, Aleksey

2012-11-19

We show experimentally and numerically new transient lasing regime between stable single-pulse generation and noise-like generation. We characterize qualitatively all three regimes of single pulse generation per round-trip of all-normal-dispersion fiber lasers mode-locked due to effect of nonlinear polarization evolution. We study spectral and temporal features of pulses produced in all three regimes as well as compressibility of such pulses. Simple criteria are proposed to identify lasing regime in experiment.

Enhanced third-harmonic generation in silicon nanoparticles driven by magnetic response.

PubMed

Shcherbakov, Maxim R; Neshev, Dragomir N; Hopkins, Ben; Shorokhov, Alexander S; Staude, Isabelle; Melik-Gaykazyan, Elizaveta V; Decker, Manuel; Ezhov, Alexander A; Miroshnichenko, Andrey E; Brener, Igal; Fedyanin, Andrey A; Kivshar, Yuri S

2014-11-12

We observe enhanced third-harmonic generation from silicon nanodisks exhibiting both electric and magnetic dipolar resonances. Experimental characterization of the nonlinear optical response through third-harmonic microscopy and spectroscopy reveals that the third-harmonic generation is significantly enhanced in the vicinity of the magnetic dipole resonances. The field localization at the magnetic resonance results in two orders of magnitude enhancement of the harmonic intensity with respect to unstructured bulk silicon with the conversion efficiency limited only by the two-photon absorption in the substrate.

Opto-electronic characterization of third-generation solar cells

PubMed Central

Jenatsch, Sandra

2018-01-01

Abstract We present an overview of opto-electronic characterization techniques for solar cells including light-induced charge extraction by linearly increasing voltage, impedance spectroscopy, transient photovoltage, charge extraction and more. Guidelines for the interpretation of experimental results are derived based on charge drift-diffusion simulations of solar cells with common performance limitations. It is investigated how nonidealities like charge injection barriers, traps and low mobilities among others manifest themselves in each of the studied cell characterization techniques. Moreover, comprehensive parameter extraction for an organic bulk-heterojunction solar cell comprising PCDTBT:PC70BM is demonstrated. The simulations reproduce measured results of 9 different experimental techniques. Parameter correlation is minimized due to the combination of various techniques. Thereby a route to comprehensive and accurate parameter extraction is identified. PMID:29707069

Experimental evolution and the dynamics of adaptation and genome evolution in microbial populations.

PubMed

Lenski, Richard E

2017-10-01

Evolution is an on-going process, and it can be studied experimentally in organisms with rapid generations. My team has maintained 12 populations of Escherichia coli in a simple laboratory environment for >25 years and 60 000 generations. We have quantified the dynamics of adaptation by natural selection, seen some of the populations diverge into stably coexisting ecotypes, described changes in the bacteria's mutation rate, observed the new ability to exploit a previously untapped carbon source, characterized the dynamics of genome evolution and used parallel evolution to identify the genetic targets of selection. I discuss what the future might hold for this particular experiment, briefly highlight some other microbial evolution experiments and suggest how the fields of experimental evolution and microbial ecology might intersect going forward.

Experimental Characterization of Piezoelectric Radial Field Diaphragms for Fluidic Control

NASA Technical Reports Server (NTRS)

Bryant, R. G.; Kavli, S. E.; Thomas, R. A., Jr.; Darji, K. J.; Mossi, K. M.

2004-01-01

NASA has recently developed a new piezoelectric actuator, the Radial Field Diaphragm or RFD. This actuator uses a radially-directed electric field to generate concentric out-of-plane (Z-axis) motion that allows this packaged device to be used as a pump or valve diaphragm. In order to efficiently use this new active device, experimental determination of pressure, flow rate, mechanical work, power consumption and overall efficiency needs to be determined by actually building a pump. However, without an optimized pump design, it is difficult to assess the quality of the data, as these results are inherent to the actual pump. Hence, separate experiments must be conducted in order to generate independent results to help guide the design criteria and pump quality. This paper focuses on the experiments used to generate the RFD's operational parameters and then compares these results to the experimentally determined results of several types of ball pumps. Also discussed are how errors are inherently introduced into the experiments, the pump design, experimental hardware and their effects on the overall system efficiency.

Modeling defect cluster evolution in irradiated structural materials: Focus on comparing to high-resolution experimental characterization studies

DOE PAGES

Wirth, Brian D.; Hu, Xunxiang; Kohnert, Aaron; ...

2015-03-02

Exposure of metallic structural materials to irradiation environments results in significant microstructural evolution, property changes, and performance degradation, which limits the extended operation of current generation light water reactors and restricts the design of advanced fission and fusion reactors. Further, it is well recognized that these irradiation effects are a classic example of inherently multiscale phenomena and that the mix of radiation-induced features formed and the corresponding property degradation depend on a wide range of material and irradiation variables. This inherently multiscale evolution emphasizes the importance of closely integrating models with high-resolution experimental characterization of the evolving radiation-damaged microstructure. Lastly,more » this article provides a review of recent models of the defect microstructure evolution in irradiated body-centered cubic materials, which provide good agreement with experimental measurements, and presents some outstanding challenges, which will require coordinated high-resolution characterization and modeling to resolve.« less

Experimental Verification of Entanglement Generated in a Plasmonic System.

PubMed

Dieleman, F; Tame, M S; Sonnefraud, Y; Kim, M S; Maier, S A

2017-12-13

A core process in many quantum tasks is the generation of entanglement. It is being actively studied in a variety of physical settings-from simple bipartite systems to complex multipartite systems. In this work we experimentally study the generation of bipartite entanglement in a nanophotonic system. Entanglement is generated via the quantum interference of two surface plasmon polaritons in a beamsplitter structure, i.e., utilizing the Hong-Ou-Mandel (HOM) effect, and its presence is verified using quantum state tomography. The amount of entanglement is quantified by the concurrence and we find values of up to 0.77 ± 0.04. Verifying entanglement in the output state from HOM interference is a nontrivial task and cannot be inferred from the visibility alone. The techniques we use to verify entanglement could be applied to other types of photonic system and therefore may be useful for the characterization of a range of different nanophotonic quantum devices.

Analytical investigation of critical phenomena in MHD power generators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1980-07-31

Critical phenomena in the Arnold Engineering Development Center (AEDC) High Performance Demonstration Experiment (HPDE) and the US U-25 Experiment, are analyzed. Also analyzed are the performance of a NASA-specified 500 MW(th) flow train and computations concerning critica issues for the scale-up of MHD Generators. The HPDE is characterized by computational simulations of both the nominal conditions and the conditions during the experimental runs. The steady-state performance is discussed along with the Hall voltage overshoots during the start-up and shutdown transients. The results of simulations of the HPDE runs with codes from the Q3D and TRANSIENT code families are compared tomore » the experimental results. The results of the simulations are in good agreement with the experimental data. Additional critica phenomena analyzed in the AEDC/HPDE are the optimal load schedules, parametric variations, the parametric dependence of the electrode voltage drops, the boundary layer behavior, near electrode phenomena with finite electrode segmentation, and current distribution in the end regions. The US U-25 experiment is characterized by computational simulations of the nominal operating conditions. The steady-state performance for the nominal design of the US U-25 experiment is analyzed, as is the dependence of performance on the mass flow rate. A NASA-specified 500 MW(th) MHD flow train is characterized for computer simulation and the electrical, transport, and thermodynamic properties at the inlet plane are analyzed. Issues for the scale-up of MHD power trains are discussed. The AEDC/HPDE performance is analyzed to compare these experimental results to scale-up rules.« less

Investigation of torque generated by Test Blanket Module mock-up in DIII-D

NASA Astrophysics Data System (ADS)

Salmi, A.; Tala, T.; Lanctot, M.; Degrassie, J. S.; Paz-Soldan, C.; Logan, N.; Solomon, W. M.; Grierson, B. A.

2015-11-01

Experiments at DIII-D have investigated the scaling of Test Blanket Module (TBM) torque with plasma pressure and collisionality by performing dimensionless parameter scans. In each configuration, neutral beam torque modulation and TBM torque modulation were sequentially applied to allow experimental characterization of the TBM generated torque and the underlying transport. Calculations of the neoclassical toroidal viscosity (NTV) torque with PENT code of these plasmas find that TBM torque is strongly edge localized while the tentative experimental analysis indicates a more radially broad TBM torque profile. Both the experimental and PENT results will be elaborated and experimental TBM torque scaling with pressure and collisionality presented. Experimental validation of existing plasma response and NTV torque models is an important step toward understanding the impact of magnetic field ripple on plasma rotation, and for predicting the required compensation fields. Work supported by the US Department of Energy under DE-AC52-07NA27344, DE-FC02-04ER54698 and DE-AC02-09CH11466.

A biphasic approach for the study of lift generation in soft porous media

NASA Astrophysics Data System (ADS)

Wu, Qianhong; Santhanam, Sridhar; Nathan, Rungun; Wang, Qiuyun

2017-04-01

Lift generation in highly compressible porous media under rapid compression continues to be an important topic in porous media flow. Although significant progress has been made, how to model different lifting forces during the compression process remains unclear. This is mainly because the input parameters of the existing theoretical studies, including the Darcy permeability of the porous media and the viscous damping coefficient of its solid phase, were manually adjusted so as to match the experimental data. In the current paper, we report a biphasic approach to experimentally and theoretically treat this limitation. Synthetic fibrous porous materials, whose permeability were precisely measured, were subsequently exposed to sudden impacts using a porous-walled cylinder-piston apparatus. The obtained time-dependent compression of the porous media, along with the permeability data, was applied in two different theoretical models to predict the pore pressure generation, a plug flow model and a consolidation model [Q. Wu et al., J. Fluid Mech. 542, 281 (2005a)]. Comparison between the theory and the experiments on the pore pressure distribution proved the validity of the consolidation model. Furthermore, a viscoelastic model, containing a nonlinear spring in conjunction with a linear viscoelastic generalized Maxwell mechanical module, was developed to characterize the solid phase lifting force. The model matched the experimental data very well. The paper presented herein, as one of the series studies on this topic, provides an important biphasic approach to characterize different forces that contribute to the lift generation in a soft porous medium under rapid compression.

Couette-Poiseuille flow experiment with zero mean advection velocity: Subcritical transition to turbulence

NASA Astrophysics Data System (ADS)

Klotz, L.; Lemoult, G.; Frontczak, I.; Tuckerman, L. S.; Wesfreid, J. E.

2017-04-01

We present an experimental setup that creates a shear flow with zero mean advection velocity achieved by counterbalancing the nonzero streamwise pressure gradient by moving boundaries, which generates plane Couette-Poiseuille flow. We obtain experimental results in the transitional regime for this flow. Using flow visualization, we characterize the subcritical transition to turbulence in Couette-Poiseuille flow and show the existence of turbulent spots generated by a permanent perturbation. Due to the zero mean advection velocity of the base profile, these turbulent structures are nearly stationary. We distinguish two regions of the turbulent spot: the active turbulent core, which is characterized by waviness of the streaks similar to traveling waves, and the surrounding region, which includes in addition the weak undisturbed streaks and oblique waves at the laminar-turbulent interface. We also study the dependence of the size of these two regions on Reynolds number. Finally, we show that the traveling waves move in the downstream (Poiseuille) direction.

Selectable light-sheet uniformity using tuned axial scanning

PubMed Central

Duocastella, Martí; Arnold, Craig B.; Puchalla, Jason

2016-01-01

Light-sheet fluorescence microscopy (LSFM) is an optical sectioning technique capable of rapid three-dimensional (3D) imaging of a wide range of specimens with reduced phototoxicity and superior background rejection. However, traditional light-sheet generation approaches based on elliptical or circular Gaussian beams suffer an inherent trade-off between light-sheet thickness and area over which this thickness is preserved. Recently, an increase in light-sheet uniformity was demonstrated using rapid biaxial Gaussian beam scanning along the lateral and beam propagation directions. Here we apply a similar scanning concept to an elliptical beam generated by a cylindrical lens. In this case, only z-scanning of the elliptical beam is required and hence experimental implementation of the setup can be simplified. We introduce a simple dimensionless uniformity statistic to better characterize scanned light-sheets and experimentally demonstrate custom tailored uniformities up to a factor of 5 higher than those of un-scanned elliptical beams. This technique offers a straightforward way to generate and characterize a custom illumination profile that provides enhanced utilization of the detector dynamic range and field of view, opening the door to faster and more efficient 2D and 3D imaging. PMID:28132409

Detection and characterization of fatigue cracks in thin metal plates by low frequency resonant model analysis

NASA Technical Reports Server (NTRS)

Wincheski, B.; Namkung, M.; Birt, E. A.

1992-01-01

Low-frequency resonant model analysis, a technique for the detection and characterization of fatigue cracks in thin metal plates, which could be adapted to rapid scan or large area testing, is considered. Experimental data displaying a direct correlation between fatigue crack geometry and resonance frequency for the second vibrational plate mode are presented. FEM is used to calculate the mechanical behavior of the plates, and provides a comparison basis for the experimentally determined resonance frequency values. The waveform of the acoustic emission generated at the resonant frequency is examined; it provides the basis for a model of the interaction of fatigue crack faces during plate vibration.

Theoretical and material studies on thin-film electroluminescent devices

NASA Technical Reports Server (NTRS)

Summers, C. J.; Brennan, K. F.

1986-01-01

Electroluminescent materials and device technology were assessed. The evaluation strongly suggests the need for a comprehensive theoretical and experimental study of both materials and device structures, particularly in the following areas: carrier generation and multiplication; radiative and nonradiative processes of luminescent centers; device modeling; new device concepts; and single crystal materials growth and characterization. Modeling of transport properties of hot electrons in ZnSe and the generation of device concepts were initiated.

Experimental realization of underdense plasma photocathode wakefield acceleration at FACET

NASA Astrophysics Data System (ADS)

Scherkl, Paul

2017-10-01

Novel electron beam sources from compact plasma accelerator concepts currently mature into the driving technology for next generation high-energy physics and light source facilities. Particularly electron beams of ultra-high brightness could pave the way for major advances for both scientific and commercial applications, but their generation remains tremendously challenging. The presentation outlines the experimental demonstration of the world's first bright electron beam source from spatiotemporally synchronized laser pulses injecting electrons into particle-driven plasma wakefields at FACET. Two distinctive types of operation - laser-triggered density downramp injection (``Plasma Torch'') and underdense plasma photocathode acceleration (``Trojan Horse'') - and their intermediate transitions are characterized and contrasted. Extensive particle-in-cell simulations substantiate the presentation of experimental results. In combination with novel techniques to minimize the beam energy spread, the acceleration scheme presented here promises ultra-high beam quality and brightness.

Drainage fracture networks in elastic solids with internal fluid generation

NASA Astrophysics Data System (ADS)

Kobchenko, Maya; Hafver, Andreas; Jettestuen, Espen; Galland, Olivier; Renard, François; Meakin, Paul; Jamtveit, Bjørn; Dysthe, Dag K.

2013-06-01

Experiments in which CO2 gas was generated by the yeast fermentation of sugar in an elastic layer of gelatine gel confined between two glass plates are described and analyzed theoretically. The CO2 gas pressure causes the gel layer to fracture. The gas produced is drained on short length scales by diffusion and on long length scales by flow in a fracture network, which has topological properties that are intermediate between river networks and hierarchical-fracture networks. A simple model for the experimental system with two parameters that characterize the disorder and the intermediate (river-fracture) topology of the network was developed and the results of the model were compared with the experimental results.

Experimentally Generated Random Numbers Certified by the Impossibility of Superluminal Signaling

NASA Astrophysics Data System (ADS)

Bierhorst, Peter; Shalm, Lynden K.; Mink, Alan; Jordan, Stephen; Liu, Yi-Kai; Rommal, Andrea; Glancy, Scott; Christensen, Bradley; Nam, Sae Woo; Knill, Emanuel

Random numbers are an important resource for applications such as numerical simulation and secure communication. However, it is difficult to certify whether a physical random number generator is truly unpredictable. Here, we exploit the phenomenon of quantum nonlocality in a loophole-free photonic Bell test experiment to obtain data containing randomness that cannot be predicted by any theory that does not also allow the sending of signals faster than the speed of light. To certify and quantify the randomness, we develop a new protocol that performs well in an experimental regime characterized by low violation of Bell inequalities. Applying an extractor function to our data, we obtain 256 new random bits, uniform to within 10- 3 .

Generation and characterization of koi herpesvirus recombinants lacking viral enzymes of nucleotide metabolism.

PubMed

Fuchs, Walter; Fichtner, Dieter; Bergmann, Sven M; Mettenleiter, Thomas C

2011-06-01

Koi herpesvirus (KHV) causes a fatal disease in koi and common carp, but no reliable and genetically characterized vaccines are available up to now. Therefore, we generated KHV recombinants possessing deletions within the viral ribonucleotide reductase (RNR), thymidine kinase (TK), dUTPase, or TK and dUTPase genes, and their corresponding rescuants. All KHV mutants were replication competent in cultured cells. Whereas plaque sizes and titers of RNR-negative KHV were reduced, replication of the other mutants was not affected. Experimental infection of carp indicated attenuation of TK- or dUTPase-deleted KHV, and PCR analysis of tissue samples permitted differentiation of mutant from wild-type virus.

Dynamic Characterization and Modeling of Potting Materials for Electronics Assemblies

NASA Astrophysics Data System (ADS)

Joshi, Vasant; Lee, Gilbert; Santiago, Jaime

2015-06-01

Prediction of survivability of encapsulated electronic components subject to impact relies on accurate modeling. Both static and dynamic characterization of encapsulation material is needed to generate a robust material model. Current focus is on potting materials to mitigate high rate loading on impact. In this effort, encapsulation scheme consists of layers of polymeric material Sylgard 184 and Triggerbond Epoxy-20-3001. Experiments conducted for characterization of materials include conventional tension and compression tests, Hopkinson bar, dynamic material analyzer (DMA) and a non-conventional accelerometer based resonance tests for obtaining high frequency data. For an ideal material, data can be fitted to Williams-Landel-Ferry (WLF) model. A new temperature-time shift (TTS) macro was written to compare idealized temperature shift factor (WLF model) with experimental incremental shift factors. Deviations can be observed by comparison of experimental data with the model fit to determine the actual material behavior. Similarly, another macro written for obtaining Ogden model parameter from Hopkinson Bar tests indicates deviations from experimental high strain rate data. In this paper, experimental results for different materials used for mitigating impact, and ways to combine data from resonance, DMA and Hopkinson bar together with modeling refinements will be presented.

Nondestructive Complete Mechanical Characterization of Zinc Blende and Wurtzite GaAs Nanowires Using Time-Resolved Pump-Probe Spectroscopy.

PubMed

Mante, Pierre-Adrien; Lehmann, Sebastian; Anttu, Nicklas; Dick, Kimberly A; Yartsev, Arkady

2016-08-10

We have developed and demonstrated an experimental method, based on the picosecond acoustics technique, to perform nondestructive complete mechanical characterization of nanowires, that is, the determination of the complete elasticity tensor. By means of femtosecond pump-probe spectroscopy, coherent acoustic phonons were generated in an ensemble of nanowires and their dynamics was resolved. Specific phonon modes were identified and the detection mechanism was addressed via wavelength dependent experiments. We calculated the exact phonon dispersion relation of the nanowires by fitting the experimentally observed frequencies, thus allowing the extraction of the complete elasticity tensor. The elasticity tensor and the nanowire diameter were determined for zinc blende GaAs nanowires and were found to be in a good agreement with literature data and independent measurements. Finally, we have applied this technique to characterize wurtzite GaAs nanowires, a metastable phase in bulk, for which no experimental values of elastic constants are currently available. Our results agree well with previous first principle calculations. The proposed approach to the complete and nondestructive mechanical characterization of nanowires will allow the efficient mechanical study of new crystal phases emerging in nanostructures, as well as size-dependent properties of nanostructured materials.

Fragmentation efficiency of explosive volcanic eruptions: A study of experimentally generated pyroclasts

NASA Astrophysics Data System (ADS)

Kueppers, Ulrich; Scheu, Bettina; Spieler, Oliver; Dingwell, Donald B.

2006-05-01

Products of magma fragmentation can pose a severe threat to health, infrastructure, environment, and aviation. Systematic evaluation of the mechanisms and the consequences of volcanic fragmentation is very difficult as the adjacent processes cannot be observed directly and their deposits undergo transport-related sorting. However, enhanced knowledge is required for hazard assessment and risk mitigation. Laboratory experiments on natural samples allow the precise characterization of the generated pyroclasts and open the possibility for substantial advances in the quantification of fragmentation processes. They hold the promise of precise characterization and quantification of fragmentation efficiency and its dependence on changing material properties and the physical conditions at fragmentation. We performed a series of rapid decompression experiments on three sets of natural samples from Unzen volcano, Japan. The analysis comprised grain-size analysis and surface area measurements. The grain-size analysis is performed by dry sieving for particles larger than 250 μm and wet laser refraction for smaller particles. For all three sets of samples, the grain-size of the most abundant fraction decreases and the weight fraction of newly generated ash particles (up to 40 wt.%) increases with experimental pressure/potential energy for fragmentation. This energy can be estimated from the volume of the gas fraction and the applied pressure. The surface area was determined through Argon adsorption. The fragmentation efficiency is described by the degree of fine-particle generation. Results show that the fragmentation efficiency and the generated surface correlate positively with the applied energy.

Second-harmonic generation from a thin spherical layer and No-generation conditions

NASA Astrophysics Data System (ADS)

Kapshai, V. N.; Shamyna, A. A.

2017-09-01

In the Rayleigh-Gans-Debye approximation, we solve the problem of second-harmonic generation by an elliptically polarized electromagnetic wave incident on the surface of a spherical particle that is coated by an optically nonlinear layer and is placed in a dielectric. The formulas obtained characterize the spatial distribution of the electric field of the second harmonic in the far-field zone. The most general form of the second-order dielectric susceptibility tensor is considered, which contains four independent components, with three of them being nonchiral and one, chiral. Consistency and inconsistencies between the obtained solution and formulas from works of other authors are found. We analyze the directivity patterns that characterize the spatial distribution of the generated radiation for the nonchiral layer and their dependences on the anisotropy and ellipticity coefficients of the incident wave. It is found that, with increasing radius of the nonlinear layer, the generated radiation becomes more directional. Combinations of parameters for which no radiation is generated are revealed. Based on this, we propose methods for experimental determination of the anisotropy coefficients.

Characterization of Pulsed Vortex Generator Jets for Active Flow Control

DTIC Science & Technology

2003-10-01

significant role in the developing vortex, were assessed; most of which used Amtec Engineering’s provided the net momentum flux rate is maintained. 7 The...incorporated in a single Tecplot macro, system allowed experimental data to be obtained very close to Since this method was developed, Amtec

Characterizing the discoloration of methylene blue in Fe0/H2O systems.

PubMed

Noubactep, C

2009-07-15

Methylene blue (MB) was used as a model molecule to characterize the aqueous reactivity of metallic iron in Fe(0)/H(2)O systems. Likely discoloration mechanisms under used experimental conditions are: (i) adsorption onto Fe(0) and Fe(0) corrosion products (CP), (ii) co-precipitation with in situ generated iron CP, (iii) reduction to colorless leukomethylene blue (LMB). MB mineralization (oxidation to CO(2)) is not expected. The kinetics of MB discoloration by Fe(0), Fe(2)O(3), Fe(3)O(4), MnO(2), and granular activated carbon were investigated in assay tubes under mechanically non-disturbed conditions. The evolution of MB discoloration was monitored spectrophotometrically. The effect of availability of CP, Fe(0) source, shaking rate, initial pH value, and chemical properties of the solution were studied. The results present evidence supporting co-precipitation of MB with in situ generated iron CP as main discoloration mechanism. Under high shaking intensities (>150 min(-1)), increased CP generation yields a brownish solution which disturbed MB determination, showing that a too high shear stress induced the suspension of in situ generated corrosion products. The present study clearly demonstrates that comparing results from various sources is difficult even when the results are achieved under seemingly similar conditions. The appeal for an unified experimental procedure for the investigation of processes in Fe(0)/H(2)O systems is reiterated.

Focusing of Shear Shock Waves

NASA Astrophysics Data System (ADS)

Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

2018-01-01

Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

Alu repeat discovery and characterization within human genomes

PubMed Central

Hormozdiari, Fereydoun; Alkan, Can; Ventura, Mario; Hajirasouliha, Iman; Malig, Maika; Hach, Faraz; Yorukoglu, Deniz; Dao, Phuong; Bakhshi, Marzieh; Sahinalp, S. Cenk; Eichler, Evan E.

2011-01-01

Human genomes are now being rapidly sequenced, but not all forms of genetic variation are routinely characterized. In this study, we focus on Alu retrotransposition events and seek to characterize differences in the pattern of mobile insertion between individuals based on the analysis of eight human genomes sequenced using next-generation sequencing. Applying a rapid read-pair analysis algorithm, we discover 4342 Alu insertions not found in the human reference genome and show that 98% of a selected subset (63/64) experimentally validate. Of these new insertions, 89% correspond to AluY elements, suggesting that they arose by retrotransposition. Eighty percent of the Alu insertions have not been previously reported and more novel events were detected in Africans when compared with non-African samples (76% vs. 69%). Using these data, we develop an experimental and computational screen to identify ancestry informative Alu retrotransposition events among different human populations. PMID:21131385

Development and performance characterization of an electric ground vehicle with independently actuated in-wheel motors

NASA Astrophysics Data System (ADS)

Wang, Rongrong; Chen, Yan; Feng, Daiwei; Huang, Xiaoyu; Wang, Junmin

This paper presents the development and experimental characterizations of a prototyping pure electric ground vehicle, which is equipped with four independently actuated in-wheel motors (FIAIWM) and is powered by a 72 V 200 Ah LiFeYPO 4 battery pack. Such an electric ground vehicle (EGV) employs four in-wheel (or hub) motors to independently drive/brake the four wheels and is one of the promising vehicle architectures primarily due to its actuation flexibility, energy efficiency, and performance potentials. Experimental data obtained from the EGV chassis dynamometer tests were employed to generate the in-wheel motor torque response and power efficiency maps in both driving and regenerative braking modes. A torque distribution method is proposed to show the potentials of optimizing the FIAIWM EGV operational energy efficiency by utilizing the actuation flexibility and the characterized in-wheel motor efficiency and torque response.

Characterization of the powertrain components for a hybrid quadricycle

NASA Astrophysics Data System (ADS)

De Santis, M.; Agnelli, S.; Silvestri, L.; Di Ilio, G.; Giannini, O.

2016-06-01

This paper presents the experimental characterization of a prototyping hybrid electric quadricycle, which is equipped with two independently actuated hub (in-wheel) motors and powered by a 51 V 132 Ah LiFeYPO4 battery pack. Such a vehicle employs two hub motors located in the rear axles in order to independently drive/brake the rear wheels; such architecture allows to implement a torque vectoring system to improve the vehicle dynamics. Due to its actuation flexibility, energy efficiency and performance potentials, this architecture is one of the promising powertrain design for electric quadricycle. Experimental data obtained from measurements on the vehicle powertrain components going from the battery pack to the inverter and to the in-wheel motor were employed to generate the hub motor torque response and power efficiency maps in both driving and regenerative braking modes. Furthermore, the vehicle is equipped with a gasoline internal combustion engine as range extender whose efficiency was also characterized.

Experimental investigation of criteria for continuous variable entanglement.

PubMed

Bowen, W P; Schnabel, R; Lam, P K; Ralph, T C

2003-01-31

We generate a pair of entangled beams from the interference of two amplitude squeezed beams. The entanglement is quantified in terms of EPR paradox and inseparability criteria, with both results clearly beating the standard quantum limit. We experimentally analyze the effect of decoherence on each criterion and demonstrate qualitative differences. We also characterize the number of required and excess photons present in the entangled beams and provide contour plots of the efficacy of quantum information protocols in terms of these variables.

Device-independent randomness generation from several Bell estimators

NASA Astrophysics Data System (ADS)

Nieto-Silleras, Olmo; Bamps, Cédric; Silman, Jonathan; Pironio, Stefano

2018-02-01

Device-independent randomness generation and quantum key distribution protocols rely on a fundamental relation between the non-locality of quantum theory and its random character. This relation is usually expressed in terms of a trade-off between the probability of guessing correctly the outcomes of measurements performed on quantum systems and the amount of violation of a given Bell inequality. However, a more accurate assessment of the randomness produced in Bell experiments can be obtained if the value of several Bell expressions is simultaneously taken into account, or if the full set of probabilities characterizing the behavior of the device is considered. We introduce protocols for device-independent randomness generation secure against classical side information, that rely on the estimation of an arbitrary number of Bell expressions or even directly on the experimental frequencies of measurement outcomes. Asymptotically, this results in an optimal generation of randomness from experimental data (as measured by the min-entropy), without having to assume beforehand that the devices violate a specific Bell inequality.

Three-dimensional direct observation of Gouy phase shift in a terajet produced by a dielectric cuboid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen Pham, Hai Huy, E-mail: haihuynguyenpham135@s.ee.es.osaka-u.ac.jp; Hisatake, Shintaro, E-mail: hisatake@ee.es.osaka-u.ac.jp; Nagatsuma, Tadao, E-mail: nagatuma@ee.es.osaka-u.ac.jp

2016-05-09

The generation of the terajet at the terahertz (THz) frequency with the capability of subwavelength beam-compression has been attracting increasing research interest, as did the generation of the nanojet at the optical frequency. In particular, a terajet generated from a dielectric cuboid was not previously studied experimentally in the THz region. We here experimentally demonstrate three-dimensional visualizations and characterization of a terajet generated from a dielectric cuboid with a refractive index of n = 1.46 at 125 GHz. The subwavelength compressed beam and the Gouy phase shift phenomena of the terajet are directly observed. It is also found out that a calculation modelmore » of Gouy phase shift based on focused Gaussian beam by a lens cannot explain the Gouy phase shift of compressed beam by the terajet. The intensity enhancement of about 7.4 dB and full width at half maximum of 0.6λ are obtained at the distance 0.5λ from the cuboid.« less

Experimental characterization and macro-modeling of mechanical strength of multi-sheets and multi-materials spot welds under pure and mixed modes I and II

NASA Astrophysics Data System (ADS)

Chtourou, Rim; Haugou, Gregory; Leconte, Nicolas; Zouari, Bassem; Chaari, Fahmi; Markiewicz, Eric

2015-09-01

Resistance Spot Welding (RSW) of multiple sheets with multiple materials are increasingly realized in the automotive industry. The mechanical strength of such new generation of spot welded assemblies is not that much dealt with. This is true in particular for experiments dedicated to investigate the mechanical strength of spot weld made by multi sheets of different grades, and their macro modeling in structural computations. Indeed, the most published studies are limited to two sheet assemblies. Therefore, in the first part of this work an advanced experimental set-up with a reduced mass is proposed to characterize the quasi-static and dynamic mechanical behavior and rupture of spot weld made by several sheets of different grades. The proposed device is based on Arcan test, the plates contribution in the global response is, thus, reduced. Loading modes I/II are, therefore, combined and well controlled. In the second part a simplified spot weld connector element (macroscopic modeling) is proposed to describe the nonlinear response and rupture of this new generation of spot welded assemblies. The weld connector model involves several parameters to be set. The remaining parameters are finally identified through a reverse engineering approach using mechanical responses of experimental tests presented in the first part of this work.

Space-Time Characterization of Laser Plasma Interactions in the Warm Dense Matter Regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, L F; Uschmann, I; Forster, E

2008-04-30

Laser plasma interaction experiments have been performed using a fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. The electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were compared with hydrodynamic simulation. First results to characterize the plasma density and temperature as a function of space and time are obtained. This work aims to generate plasmas in the warm dense matter (WDM) regime at near solid-density in anmore » ultra-fast laser target interaction process. Plasmas under these conditions can serve as targets to develop x-ray Thomson scattering as a plasma diagnostic tool, e.g., using the VUV free-electron laser (FLASH) at DESY Hamburg.« less

Measurements of the interaction of wave groups with shorter wind-generated waves

NASA Technical Reports Server (NTRS)

Chu, Jacob S.; Long, Steven R.; Phillips, O. M.

1992-01-01

Fields of statistically steady wind-generated waves produced in a wind wave facility were perturbed by the injection of groups of longer, mechanically generated waves with various slopes. The time histories of the surface displacements were measured at four fetches in ensembles consisting of 100 realizations of each set of experimental conditions; the data were stored and analyzed digitally. Four distinct stages in the overall interaction are identified and characterized. The properties of the wave energy front are documented, and a preliminary discussion is given of the dynamic processes involved in its formation.

Experimental characterization and constitutive modeling of the mechanical behavior of molybdenum under electromagnetically applied compression-shear ramp loading

DOE PAGES

Alexander, C. Scott; Ding, Jow -Lian; Asay, James Russell

2016-03-09

Magnetically applied pressure-shear (MAPS) is a new experimental technique that provides a platform for direct measurement of material strength at extreme pressures. The technique employs an imposed quasi-static magnetic field and a pulsed power generator that produces an intense current on a planar driver panel, which in turn generates high amplitude magnetically induced longitudinal compression and transverse shear waves into a planar sample mounted on the drive panel. In order to apply sufficiently high shear traction to the test sample, a high strength material must be used for the drive panel. Molybdenum is a potential driver material for the MAPSmore » experiment because of its high yield strength and sufficient electrical conductivity. To properly interpret the results and gain useful information from the experiments, it is critical to have a good understanding and a predictive capability of the mechanical response of the driver. In this work, the inelastic behavior of molybdenum under uniaxial compression and biaxial compression-shear ramp loading conditions is experimentally characterized. It is observed that an imposed uniaxial magnetic field ramped to approximately 10 T through a period of approximately 2500 μs and held near the peak for about 250 μs before being tested appears to anneal the molybdenum panel. In order to provide a physical basis for model development, a general theoretical framework that incorporates electromagnetic loading and the coupling between the imposed field and the inelasticity of molybdenum was developed. Based on this framework, a multi-axial continuum model for molybdenum under electromagnetic loading is presented. The model reasonably captures all of the material characteristics displayed by the experimental data obtained from various experimental configurations. Additionally, data generated from shear loading provide invaluable information not only for validating but also for guiding the development of the material model for multiaxial loadings.« less

Design and modeling of energy generated magneto rheological damper

NASA Astrophysics Data System (ADS)

Ahamed, Raju; Rashid, Muhammad Mahbubur; Ferdaus, Md Meftahul; Yusof, Hazlina Md.

2016-02-01

In this paper an energy generated mono tube MR damper model has been developed for vehicle suspension systems. A 3D model of energy generated MR damper is developed in Solid Works electromagnetic simulator (EMS) where it is analyzed extensively by finite element method. This dynamic simulation clearly illustrates the power generation ability of the damper. Two magnetic fields are induced inside this damper. One is in the outer coil of the power generator and another is in the piston head coils. The complete magnetic isolation between these two fields is accomplished here, which can be seen in the finite element analysis. The induced magnetic flux densities, magnetic field intensities of this damper are analyzed for characterizing the damper's power generation ability. Finally, the proposed MR damper's energy generation ability was studied experimentally.

Raman-tailored photonic crystal fiber for telecom band photon-pair generation.

PubMed

Cordier, M; Orieux, A; Gabet, R; Harlé, T; Dubreuil, N; Diamanti, E; Delaye, P; Zaquine, I

2017-07-01

We report on the experimental characterization of a novel nonlinear liquid-filled hollow-core photonic crystal fiber for the generation of photon pairs at a telecommunication wavelength through spontaneous four-wave mixing (SFWM). We show that the optimization procedure in view of this application links the choice of the nonlinear liquid to the design parameters of the fiber, and we give an example of such an optimization at telecom wavelengths. Combining the modeling of the fiber and classical characterization techniques at these wavelengths, we identify for the chosen fiber and liquid combination SFWM phase-matching frequency ranges with no Raman scattering noise contamination. This is a first step toward obtaining a telecom band fibered photon-pair source with a high signal-to-noise ratio.

Measurements and modeling of flow structure in the wake of a low profile wishbone vortex generator

NASA Technical Reports Server (NTRS)

Wendt, B. J.; Hingst, W. R.

1994-01-01

The results of an experimental examination of the vortex structures shed from a low profile 'wishbone' generator are presented. The vortex generator height relative to the turbulent boundary layer was varied by testing two differently sized models. Measurements of the mean three-dimensional velocity field were conducted in cross-stream planes downstream of the vortex generators. In all cases, a counter-rotating vortex pair was observed. Individual vortices were characterized by three descriptors derived from the velocity data; circulation, peak vorticity, and cross-stream location of peak vorticity. Measurements in the cross plane at two axial locations behind the smaller wishbone characterize the downstream development of the vortex pairs. A single region of stream wise velocity deficit is shared by both vortex cores. This is in contrast to conventional generators, where each core coincides with a region of velocity deficit. The measured cross-stream velocities for each case are compared to an Oseen model with matching descriptors. The best comparison occurs with the data from the larger wishbone.

Experimental study of the response functions of direct-reading instruments measuring surface-area concentration of airborne nanostructured particles

NASA Astrophysics Data System (ADS)

Bau, Sébastien; Witschger, Olivier; Gensdarmes, François; Thomas, Dominique

2009-05-01

An increasing number of experimental and theoretical studies focus on airborne nanoparticles (NP) in relation with many aspects of risk assessment to move forward our understanding of the hazards, the actual exposures in the workplace, and the limits of engineering controls and personal protective equipment with regard to NP. As a consequence, generating airborne NP with controlled properties constitutes an important challenge. In parallel, toxicological studies have been carried out, and most of them support the concept that surface-area could be a relevant metric for characterizing exposure to airborne NP [1]. To provide NP surface-area concentration measurements, some direct-reading instruments have been designed, based on attachment rate of unipolar ions to NP by diffusion. However, very few information is available concerning the performances of these instruments and the parameters that could affect their responses. In this context, our work aims at characterizing the actual available instruments providing airborne NP surface-area concentration. The instruments (a- LQ1-DC, Matter Engineering; b-AeroTrak™ 9000, TSI; c- NSAM, TSI model 3550;) are thought to be relevant for further workplace exposure characterization and monitoring. To achieve our work, an experimental facility (named CAIMAN) was specially designed, built and characterized.

Temporal Genetic Dynamics of an Experimental, Biparental Field Population of Phytophthora capsici

PubMed Central

Carlson, Maryn O.; Gazave, Elodie; Gore, Michael A.; Smart, Christine D.

2017-01-01

Defining the contributions of dispersal, reproductive mode, and mating system to the population structure of a pathogenic organism is essential to estimating its evolutionary potential. After introduction of the devastating plant pathogen, Phytophthora capsici, into a grower’s field, a lack of aerial spore dispersal restricts migration. Once established, coexistence of both mating types results in formation of overwintering recombinant oospores, engendering persistent pathogen populations. To mimic these conditions, in 2008, we inoculated a field with two P. capsici isolates of opposite mating type. We analyzed pathogenic isolates collected in 2009–2013 from this experimental population, using genome-wide single-nucleotide polymorphism markers. By tracking heterozygosity across years, we show that the population underwent a generational shift; transitioning from exclusively F1 in 2009–2010, to multi-generational in 2011, and ultimately all inbred in 2012–2013. Survival of F1 oospores, characterized by heterozygosity excess, coupled with a low rate of selfing, delayed declines in heterozygosity due to inbreeding and attainment of equilibrium genotypic frequencies. Large allele and haplotype frequency changes in specific genomic regions accompanied the generational shift, representing putative signatures of selection. Finally, we identified an approximately 1.6 Mb region associated with mating type determination, constituting the first detailed genomic analysis of a mating type region (MTR) in Phytophthora. Segregation patterns in the MTR exhibited tropes of sex-linkage, where maintenance of allele frequency differences between isolates of opposite mating type was associated with elevated heterozygosity despite inbreeding. Characterizing the trajectory of this experimental system provides key insights into the processes driving persistent, sexual pathogen populations. PMID:28348576

Discrete Breathers in One-Dimensional Diatomic Granular Crystals

NASA Astrophysics Data System (ADS)

Boechler, N.; Theocharis, G.; Job, S.; Kevrekidis, P. G.; Porter, Mason A.; Daraio, C.

2010-06-01

We report the experimental observation of modulational instability and discrete breathers in a one-dimensional diatomic granular crystal composed of compressed elastic beads that interact via Hertzian contact. We first characterize their effective linear spectrum both theoretically and experimentally. We then illustrate theoretically and numerically the modulational instability of the lower edge of the optical band. This leads to the dynamical formation of long-lived breather structures, whose families of solutions we compute throughout the linear spectral gap. Finally, we experimentally observe the manifestation of the modulational instability and the resulting generation of localized breathing modes with quantitative characteristics that agree with our numerical results.

Measuring and characterizing beat phenomena with a smartphone

NASA Astrophysics Data System (ADS)

Osorio, M.; Pereyra, C. J.; Gau, D. L.; Laguarda, A.

2018-03-01

Nowadays, smartphones are in everyone’s life. Apart from being excellent tools for work and communication, they can also be used to perform several measurements of simple physical magnitudes, serving as a mobile and inexpensive laboratory, ideal for use physics lectures in high schools or universities. In this article, we use a smartphone to analyse the acoustic beat phenomena by using a simple experimental setup, which can complement lessons in the classroom. The beats were created by the superposition of the waves generated by two tuning forks, with their natural frequencies previously characterized using different applications. After the characterization, we recorded the beats and analysed the oscillations in time and frequency.

Nanosecond pulsed laser micromachining for experimental fatigue life study of Ti-3Al-2.5V tubes

NASA Astrophysics Data System (ADS)

Lin, Yaomin; Gupta, Mool C.; Taylor, Robert E.; Lei, Charles; Stone, William; Spidel, Tom; Yu, Michael; Williams, Reanne

2009-01-01

Defects on external surface of in-service hydraulic tubes can reduce total life cycles for operation. Evaluation of fatigue life of the tubes with damage is thus critical for safety reasons. A methodology of generating defects in the Ti-3Al-2.5V tube—a widely used pipeline in hydraulic systems of aircrafts—using nanosecond pulsed laser for experimental fatigue life study is described in this paper. Straight tubes of five different sizes were laser micromachined to generate notches of given length and depths on the outside surface. Approaches were developed to precisely control the notch dimensions. The laser-notched tubes were tested with cyclic internal impulse pressure and fatigue life was measured. The laser notches and fatigue cracks were characterized after the test. It is concluded that laser micromachining generated consistent notches, and the influence of notch depth on fatigue life of the tube is significant. Based on the experimental test results, the relationship between the fatigue life of the Ti-3Al-2.5V tube and the notch depth was revealed. The research demonstrated that laser micromachining is applicable for experimental fatigue life study of titanium tubes. The presented test data are useful for estimating the damage limits of the titanium tubes in service environment and for further theoretical studies.

Fulfilling the promise of the materials genome initiative with high-throughput experimental methodologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Green, Martin L.; Choi, C. L.; Hattrick-Simpers, J. R.

The Materials Genome Initiative, a national effort to introduce new materials into the market faster and at lower cost, has made significant progress in computational simulation and modeling of materials. To build on this progress, a large amount of experimental data for validating these models, and informing more sophisticated ones, will be required. High-throughput experimentation generates large volumes of experimental data using combinatorial materials synthesis and rapid measurement techniques, making it an ideal experimental complement to bring the Materials Genome Initiative vision to fruition. This paper reviews the state-of-the-art results, opportunities, and challenges in high-throughput experimentation for materials design. Asmore » a result, a major conclusion is that an effort to deploy a federated network of high-throughput experimental (synthesis and characterization) tools, which are integrated with a modern materials data infrastructure, is needed.« less

Fulfilling the promise of the materials genome initiative with high-throughput experimental methodologies

DOE PAGES

Green, Martin L.; Choi, C. L.; Hattrick-Simpers, J. R.; ...

2017-03-28

The Materials Genome Initiative, a national effort to introduce new materials into the market faster and at lower cost, has made significant progress in computational simulation and modeling of materials. To build on this progress, a large amount of experimental data for validating these models, and informing more sophisticated ones, will be required. High-throughput experimentation generates large volumes of experimental data using combinatorial materials synthesis and rapid measurement techniques, making it an ideal experimental complement to bring the Materials Genome Initiative vision to fruition. This paper reviews the state-of-the-art results, opportunities, and challenges in high-throughput experimentation for materials design. Asmore » a result, a major conclusion is that an effort to deploy a federated network of high-throughput experimental (synthesis and characterization) tools, which are integrated with a modern materials data infrastructure, is needed.« less

Heterogeneity of activated carbons in adsorption of phenols from aqueous solutions—Comparison of experimental isotherm data and simulation predictions

NASA Astrophysics Data System (ADS)

Podkościelny, P.; Nieszporek, K.

2007-01-01

Surface heterogeneity of activated carbons is usually characterized by adsorption energy distribution (AED) functions which can be estimated from the experimental adsorption isotherms by inverting integral equation. The experimental data of phenol adsorption from aqueous solution on activated carbons prepared from polyacrylonitrile (PAN) and polyethylene terephthalate (PET) have been taken from literature. AED functions for phenol adsorption, generated by application of regularization method have been verified. The Grand Canonical Monte Carlo (GCMC) simulation technique has been used as verification tool. The definitive stage of verification was comparison of experimental adsorption data and those obtained by utilization GCMC simulations. Necessary information for performing of simulations has been provided by parameters of AED functions calculated by regularization method.

Experimental characterization of plasma formation and shockwave propagation induced by high power pulsed underwater electrical discharge.

PubMed

Claverie, A; Deroy, J; Boustie, M; Avrillaud, G; Chuvatin, A; Mazanchenko, E; Demol, G; Dramane, B

2014-06-01

High power pulsed electrical discharges into liquids are investigated for new industrial applications based on the efficiency of controlled shock waves. We present here new experimental data obtained by combination of detailed high speed imaging equipments. It allows the visualization of the very first instants of plasma discharge formation, and then the pulsations of the gaseous bubble with an accurate timing of events. The time history of the expansion/compression of this bubble leads to an estimation of the energy effectively transferred to water during the discharge. Finally, the consecutive shock generation driven by this pulsating bubble is optically monitored by shadowgraphs and schlieren setup. These data provide essential information about the geometrical pattern and chronometry associated with the shock wave generation and propagation.

Plume splitting and oscillatory behavior in transient plasmas generated by high-fluence laser ablation in vacuum

NASA Astrophysics Data System (ADS)

Focsa, C.; Gurlui, S.; Nica, P.; Agop, M.; Ziskind, M.

2017-12-01

We present a short overview of studies performed in our research groups over the last decade on the characterization of transient plasma plumes generated by laser ablation in various temporal regimes, from nanosecond to femtosecond. New results are also presented along with this overview, both being placed in the context of similar studies performed by other investigators. Optical (fast gate intensified CCD camera imaging and space- and time-resolved emission spectroscopy) and electrical (mainly Langmuir probe) methods have been applied to experimentally explore the dynamics of the plasma plume and its constituents. Peculiar effects as plume splitting and sharpening or oscillations onset have been evidenced in vacuum at high laser fluence. New theoretical approaches have been developed to account for the experimental observations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blume-Kohout, Robin J.; Gamble, John King; Nielsen, Erik

Quantum tomography is used to characterize quantum operations implemented in quantum information processing (QIP) hardware. Traditionally, state tomography has been used to characterize the quantum state prepared in an initialization procedure, while quantum process tomography is used to characterize dynamical operations on a QIP system. As such, tomography is critical to the development of QIP hardware (since it is necessary both for debugging and validating as-built devices, and its results are used to influence the next generation of devices). But tomography suffers from several critical drawbacks. In this report, we present new research that resolves several of these flaws. Wemore » describe a new form of tomography called gate set tomography (GST), which unifies state and process tomography, avoids prior methods critical reliance on precalibrated operations that are not generally available, and can achieve unprecedented accuracies. We report on theory and experimental development of adaptive tomography protocols that achieve far higher fidelity in state reconstruction than non-adaptive methods. Finally, we present a new theoretical and experimental analysis of process tomography on multispin systems, and demonstrate how to more effectively detect and characterize quantum noise using carefully tailored ensembles of input states.« less

Helicopter cabin noise: Methods of source and path identification and characterization

NASA Technical Reports Server (NTRS)

Murray, B. S.; Wilby, J. F.

1978-01-01

Internal noise sources in a helicopter are considered. These include propulsion machinery, comprising engine and transmission, and turbulent boundary layer effects. It is shown that by using relatively simple concepts together with careful experimental work it is possible to generate reliable data on which to base the design of high performance noise control treatments.

Wind turbine generator interaction with conventional diesel generators on Block Island, Rhode Island. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

Wilreker, V. F.; Stiller, P. H.; Scott, G. W.; Kruse, V. J.; Smith, R. F.

1984-01-01

Primary results are summarized for a three-part study involving the effects of connecting a MOD-OA wind turbine generator to an isolated diesel power system. The MOD-OA installation considered was the third of four experimental nominal 200 kW wind turbines connected to various utilities under the Federal Wind Energy Program and was characterized by the highest wind energy penetration levels of four sites. The study analyses address: fuel displacement, dynamic interaction, and three modes of reactive power control. These analyses all have as their basis the results of the data acquisition program conducted on Block Island, Rhode Island.

Underwater acoustic wave generation by filamentation of terawatt ultrashort laser pulses.

PubMed

Jukna, Vytautas; Jarnac, Amélie; Milián, Carles; Brelet, Yohann; Carbonnel, Jérôme; André, Yves-Bernard; Guillermin, Régine; Sessarego, Jean-Pierre; Fattaccioli, Dominique; Mysyrowicz, André; Couairon, Arnaud; Houard, Aurélien

2016-06-01

Acoustic signals generated by filamentation of ultrashort terawatt laser pulses in water are characterized experimentally. Measurements reveal a strong influence of input pulse duration on the shape and intensity of the acoustic wave. Numerical simulations of the laser pulse nonlinear propagation and the subsequent water hydrodynamics and acoustic wave generation show that the strong acoustic emission is related to the mechanism of superfilamention in water. The elongated shape of the plasma volume where energy is deposited drives the far-field profile of the acoustic signal, which takes the form of a radially directed pressure wave with a single oscillation and a very broad spectrum.

The structure and development of streamwise vortex arrays embedded in a turbulent boundary layer. Ph.D. Thesis - Case Western Reserve Univ.

NASA Technical Reports Server (NTRS)

Wendt, Bruce J.; Greber, Isaac; Hingst, Warren R.

1991-01-01

An investigation of the structure and development of streamwise vortices embedded in a turbulent boundary layer was conducted. The vortices were generated by a single spanwise row of rectangular vortex generator blades. A single embedded vortex was examined, as well as arrays of embedded counter rotating vortices produced by equally spaced vortex generators. Measurements of the secondary velocity field in the crossplane provided the basis for characterization of vortex structure. Vortex structure was characterized by four descriptors. The center of each vortex core was located at the spanwise and normal position of peak streamwise vorticity. Vortex concentration was characterized by the magnitude of the peak streamwise vorticity, and the vortex strength by its circulation. Measurements of the secondary velocity field were conducted at two crossplane locations to examine the streamwise development of the vortex arrays. Large initial spacings of the vortex generators produced pairs of strong vortices which tended to move away from the wall region while smaller spacings produced tight arrays of weak vortices close to the wall. A model of vortex interaction and development is constructed using the experimental results. The model is based on the structure of the Oseen Vortex. Vortex trajectories are modelled by including the convective effects of neighbors.

Gingival Mesenchymal Stem/Progenitor Cells: A Unique Tissue Engineering Gem

PubMed Central

Fawzy El-Sayed, Karim M.; Dörfer, Christof E.

2016-01-01

The human gingiva, characterized by its outstanding scarless wound healing properties, is a unique tissue and a pivotal component of the periodontal apparatus, investing and surrounding the teeth in their sockets in the alveolar bone. In the last years gingival mesenchymal stem/progenitor cells (G-MSCs), with promising regenerative and immunomodulatory properties, have been isolated and characterized from the gingival lamina propria. These cells, in contrast to other mesenchymal stem/progenitor cell sources, are abundant, readily accessible, and easily obtainable via minimally invasive cell isolation techniques. The present review summarizes the current scientific evidence on G-MSCs' isolation, their characterization, the investigated subpopulations, the generated induced pluripotent stem cells- (iPSC-) like G-MSCs, their regenerative properties, and current approaches for G-MSCs' delivery. The review further demonstrates their immunomodulatory properties, the transplantation preconditioning attempts via multiple biomolecules to enhance their attributes, and the experimental therapeutic applications conducted to treat multiple diseases in experimental animal models in vivo. G-MSCs show remarkable tissue reparative/regenerative potential, noteworthy immunomodulatory properties, and primary experimental therapeutic applications of G-MSCs are very promising, pointing at future biologically based therapeutic techniques, being potentially superior to conventional clinical treatment modalities. PMID:27313628

Single shot polarization characterization of XUV FEL pulses from crossed polarized undulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrari, E.; Allaria, E.; Buck, J.

Polarization control is a key feature of light generated by short-wavelength free-electron lasers. In this work, we report the first experimental characterization of the polarization properties of an extreme ultraviolet high gain free-electron laser operated with crossed polarized undulators. We research the average degree of polarization and the shot-to-shot stability and we analyze aspects such as existing possibilities for controlling and switching the polarization state of the emitted light. The results are in agreement with predictions based on Gaussian beams propagation.

Experimental characterization of vertical-axis wind turbine noise.

PubMed

Pearson, C E; Graham, W R

2015-01-01

Vertical-axis wind turbines are wind-energy generators suitable for use in urban environments. Their associated noise thus needs to be characterized and understood. As a first step, this work investigates the relative importance of harmonic and broadband contributions via model-scale wind-tunnel experiments. Cross-spectra from a pair of flush-mounted wall microphones exhibit both components, but further analysis shows that the broadband dominates at frequencies corresponding to the audible range in full-scale operation. This observation has detrimental implications for noise-prediction reliability and hence also for acoustic design optimization.

Single shot polarization characterization of XUV FEL pulses from crossed polarized undulators

DOE PAGES

Ferrari, E.; Allaria, E.; Buck, J.; ...

2015-08-28

Polarization control is a key feature of light generated by short-wavelength free-electron lasers. In this work, we report the first experimental characterization of the polarization properties of an extreme ultraviolet high gain free-electron laser operated with crossed polarized undulators. We research the average degree of polarization and the shot-to-shot stability and we analyze aspects such as existing possibilities for controlling and switching the polarization state of the emitted light. The results are in agreement with predictions based on Gaussian beams propagation.

Evaluation of smallpox vaccines using variola neutralization.

PubMed

Damon, Inger K; Davidson, Whitni B; Hughes, Christine M; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Frey, Sharon E; Newman, Frances; Belshe, Robert B; Yan, Lihan; Karem, Kevin

2009-08-01

The search for a 'third'-generation smallpox vaccine has resulted in the development and characterization of several vaccine candidates. A significant barrier to acceptance is the absence of challenge models showing induction of correlates of protective immunity against variola virus. In this light, virus neutralization provides one of few experimental methods to show specific 'in vitro' activity of vaccines against variola virus. Here, we provide characterization of the ability of a modified vaccinia virus Ankara vaccine to induce variola virus-neutralizing antibodies, and we provide comparison with the neutralization elicited by standard Dryvax vaccination.

A new XUV optical end-station to characterize compact and flexible photonic devices using synchrotron radiation

NASA Astrophysics Data System (ADS)

Marcelli, A.; Mazuritskiy, M. I.; Dabagov, S. B.; Hampai, D.; Lerer, A. M.; Izotova, E. A.; D'Elia, A.; Turchini, S.; Zema, N.; Zuccaro, F.; de Simone, M.; Javad Rezvani, S.; Coreno, M.

2018-03-01

In this contribution we present the new experimental end-station to characterize XUV diffractive optics, such as Micro Channel Plates (MCPs) and other polycapillary optics, presently under commission at the Elettra synchrotron radiation laboratory (Trieste, Italy). To show the opportunities offered by these new optical devices for 3rd and 4th generation radiation sources, in this work we present also some patterns collected at different energies of the primary XUV radiation transmitted by MCP optical devices working in the normal incidence geometry.

Multipulse technique exploiting the intermodulation of ultrasound waves in a nonlinear medium.

PubMed

Biagi, Elena; Breschi, Luca; Vannacci, Enrico; Masotti, Leonardo

2009-03-01

In recent years, the nonlinear properties of materials have attracted much interest in nondestructive testing and in ultrasound diagnostic applications. Acoustic nonlinear parameters represent an opportunity to improve the information that can be extracted from a medium such as structural organization and pathologic status of tissue. In this paper, a method called pulse subtraction intermodulation (PSI), based on a multipulse technique, is presented and investigated both theoretically and experimentally. This method allows separation of the intermodulation products, which arise when 2 separate frequencies are transmitted in a nonlinear medium, from fundamental and second harmonic components, making them available for improved imaging techniques or signal processing algorithms devoted to tissue characterization. The theory of intermodulation product generation was developed according the Khokhlov-Zabolotskaya-Kuznetsov (KZK) nonlinear propagation equation, which is consistent with experimental results. The description of the proposed method, characterization of the intermodulation spectral contents, and quantitative results coming from in vitro experimentation are reported and discussed in this paper.

The interaction of intense subpicosecond laser pulses with underdense plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coverdale, Christine Ann

1995-05-11

Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10 16 W/cm 2 laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L plasma ≥ 2L Rayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n o ≤ 0.05n cr). Specifically, themore » parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.« less

Experimental characterization of novel microdiffuser elements

NASA Astrophysics Data System (ADS)

Ehrlich, L.; Punch, J.; Jeffers, N.; Stafford, J.

2014-07-01

Micropumps can play a significant role in thermal management applications, as a component of microfluidic cooling systems. For next-generation high density optical communication systems, in particular, heat flux levels are sufficiently high to require a microfluidic circuit for cooling. Valveless piezoelectrically-actuated micropumps are a particularly promising technology to be deployed for this application. These pumps exploit the asymmetric flow behaviour of microdiffusers to achieve net flow. They feature no rotating or contacting parts, which make them intrinsically reliable in comparison to micropumps with active valves. In this paper, two novel microdiffuser elements are reported and characterized. The micropumps were fabricated using a 3D Printer. Each single diffuser had a length of 1800 pm and a depth of 400 pm. An experimental characterization was conducted in which the flow rate and differential pressure were measured as a function of operating frequency. In comparison with standard diffuser, both elements showed an increase in differential pressure in the range of 40 - 280 %, but only one of the elements exhibited an improved flow rate, of about 85 %.

Characterization of Acoustic Droplet Vaporization Using MRI

NASA Astrophysics Data System (ADS)

Li, David; Allen, Steven; Hernandez-Garcia, Luis; Bull, Joseph

2013-11-01

Acoustic droplet vaporization (ADV) is the selective vaporization of liquid droplets to form larger gas bubbles. The ADV process is currently being researched for biomedical applications such as gas embolotherapy, drug delivery, and phase-change contrast agents. In this study an albumin encapsulated dodecafluoropentane (DDFP, CAS: 678-26-2) microdroplet suspension was vaporized using a single element focused (f/2, D = 19 mm) 3.5 MHz transducer (Panametrics A321S, Olympus, Waltham, MA). The resulting DDFP bubble clouds were imaged using both bright field microscopy and MRI (Varian 7T, Agilent Technologies Inc., Santa Clara, CA). Field distortions due to DDFP bubble generation were characterized against the bright field images as a function of acoustic power and bubble cloud size. Experimentally a direct correlation between bubble cloud dimensions generated and field distortions seen in the MRI was observed. Additionally, MR velocimetry was used to measure the flow field resulting from ADV. The field distortions due to the bubbles were further characterized by modeling Maxwell's equations using COMSOL (COMSOL Inc., Burlington, MA). The ability to characterize ADV with alternative imaging modalities may prove useful in further development of ADV based biomedical therapies.

Optical fiber sensor for the detection of laser-generated ultrasound in arterial tissues

NASA Astrophysics Data System (ADS)

Beard, Paul C.; Mills, Timothy N.

1995-02-01

Theoretical and experimental aspects of an extrinsic Fabry-Perot optical fiber ultrasound sensor for use in a photoacoustic-guided laser angioplasty system are described. The sensor has been characterized using laser generated thermoelastic waves as a source of wideband ultrasound. A system sensitivity of 25 mV/MPa and an acoustic noise floor of 2 Pa/Hz1/2 are reported using a transparent polymer film as the sensing element. The system demonstrates the required bandwidth for sensing thermoelastic waves containing frequency components up to 20 MHz.

Characterization and application of Shape Memory Alloy wires for micro and meso positioning systems

NASA Astrophysics Data System (ADS)

Khan, Afzal

The properties of Shape Memory Alloy (SMA) wires are determined by experimentation, and previously used experimental equipment contributes to measurement errors in data. In this study, various characterization experiments are designed and carried out using a precision characterization instrument for shape memory alloy wires to determine the properties and parameters of the alloy. These experiments demonstrate the behavior of SMA wires under different thermal and loading conditions as they occur in actuation applications. As SMA wires go through phase transformation, a significant amount of contraction force is produced. This actuation force has been used in bias spring actuators and differential actuators. In this dissertation, the force generated during the twinning of martensite is used to actuate positioning systems with small displacements at the micrometer level. A micropositioning system is designed and tested that has a positioning accuracy of about +/-0.15 mum. A relation between the current input and the displacement output is determined for the specific preload. The transformation force generated during the phase change from martensite to austenite is used as an actuation force for a second positioning system that uses linear bearing with a displacement range of about a millimeter. This positioning system actuated with a single nitinol wire and guided by symmetric parallel diaphragm flexures, was designed and tested. The actuation is repeatable to about +/-15 mum with variation of about +/-5 mum in postion at steady temperature.

Growth Twinning and Generation of High-Frequency Surface Nanostructures in Ultrafast Laser-Induced Transient Melting and Resolidification.

PubMed

Sedao, Xxx; Shugaev, Maxim V; Wu, Chengping; Douillard, Thierry; Esnouf, Claude; Maurice, Claire; Reynaud, Stéphanie; Pigeon, Florent; Garrelie, Florence; Zhigilei, Leonid V; Colombier, Jean-Philippe

2016-07-26

The structural changes generated in surface regions of single crystal Ni targets by femtosecond laser irradiation are investigated experimentally and computationally for laser fluences that, in the multipulse irradiation regime, produce sub-100 nm high spatial frequency surface structures. Detailed experimental characterization of the irradiated targets combining electron back scattered diffraction analysis with high-resolution transmission electron microscopy reveals the presence of multiple nanoscale twinned domains in the irradiated surface regions of single crystal targets with (111) surface orientation. Atomistic- and continuum-level simulations performed for experimental irradiation conditions reproduce the generation of twinned domains and establish the conditions leading to the formation of growth twin boundaries in the course of the fast transient melting and epitaxial regrowth of the surface regions of the irradiated targets. The observation of growth twins in the irradiated Ni(111) targets provides strong evidence of the role of surface melting and resolidification in the formation of high spatial frequency surface structures. This also suggests that the formation of twinned domains can be used as a sensitive measure of the levels of liquid undercooling achieved in short pulse laser processing of metals.

Light Diffraction by Large Amplitude Ultrasonic Waves in Liquids

NASA Technical Reports Server (NTRS)

Adler, Laszlo; Cantrell, John H.; Yost, William T.

2016-01-01

Light diffraction from ultrasound, which can be used to investigate nonlinear acoustic phenomena in liquids, is reported for wave amplitudes larger than that typically reported in the literature. Large amplitude waves result in waveform distortion due to the nonlinearity of the medium that generates harmonics and produces asymmetries in the light diffraction pattern. For standing waves with amplitudes above a threshold value, subharmonics are generated in addition to the harmonics and produce additional diffraction orders of the incident light. With increasing drive amplitude above the threshold a cascade of period-doubling subharmonics are generated, terminating in a region characterized by a random, incoherent (chaotic) diffraction pattern. To explain the experimental results a toy model is introduced, which is derived from traveling wave solutions of the nonlinear wave equation corresponding to the fundamental and second harmonic standing waves. The toy model reduces the nonlinear partial differential equation to a mathematically more tractable nonlinear ordinary differential equation. The model predicts the experimentally observed cascade of period-doubling subharmonics terminating in chaos that occurs with increasing drive amplitudes above the threshold value. The calculated threshold amplitude is consistent with the value estimated from the experimental data.

THz acoustic phonon spectroscopy and nanoscopy by using piezoelectric semiconductor heterostructures.

PubMed

Mante, Pierre-Adrien; Huang, Yu-Ru; Yang, Szu-Chi; Liu, Tzu-Ming; Maznev, Alexei A; Sheu, Jinn-Kong; Sun, Chi-Kuang

2015-02-01

Thanks to ultrafast acoustics, a better understanding of acoustic dynamics on a short time scale has been obtained and new characterization methods at the nanoscale have been developed. Among the materials that were studied during the development of ultrafast acoustics, nitride based heterostructures play a particular role due to their piezoelectric properties and the possibility to generate phonons with over-THz frequency and bandwidth. Here, we review some of the work performed using this type of structure, with a focus on THz phonon spectroscopy and nanoscopy. First, we present a brief description of the theory of coherent acoustic phonon generation by piezoelectric heterostructure. Then the first experimental observation of coherent acoustic phonon generated by the absorption of ultrashort light pulses in piezoelectric heterostructures is presented. From this starting point, we then present some methods developed to realize customizable phonon generation. Finally we review some more recent applications of these structures, including imaging with a nanometer resolution, broadband attenuation measurements with a frequency up to 1THz and phononic bandgap characterization. Copyright © 2014 Elsevier B.V. All rights reserved.

Experimental research of different plasma cathodes for generation of high-current electron beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafir, G.; Kreif, M.; Gleizer, J. Z.

2015-11-21

The results of experimental studies of different types of cathodes—carbon-epoxy rods, carbon-epoxy capillary, edged graphite, and metal-dielectric—under the application of high-voltage pulses with an amplitude of several hundreds of kV and pulse duration of several nanoseconds are presented. The best diode performance was achieved with the edged graphite and carbon-epoxy-based cathodes characterized by uniform and fast (<1 ns) formation of explosive emission plasma spots and quasi-constant diode impedance. This result was achieved for both annular cathodes in a strong magnetic field and planar cathodes of a similar diameter (∼2 cm) with no external magnetic field. The cathodes based on carbon-epoxy rods andmore » carbon-epoxy capillaries operating with an average current density up to 1 kA/cm{sup 2} showed insignificant erosion along 10{sup 6} pulses of the generator and the generated electron beam current showed excellent reproducibility in terms of the amplitude and waveform.« less

Near-field non-radial motion generation from underground chemical explosions in jointed granite

NASA Astrophysics Data System (ADS)

Vorobiev, Oleg; Ezzedine, Souheil; Hurley, Ryan

2018-01-01

This paper describes analysis of non-radial ground motion generated by chemical explosions in a jointed rock formation during the Source Physics Experiment (SPE). Such motion makes it difficult to discriminate between various subsurface events such as explosions, implosions (i.e. mine collapse) and earthquakes. We apply 3-D numerical simulations to understand experimental data collected during the SPEs. The joints are modelled explicitly as compliant thin inclusions embedded into the rock mass. Mechanical properties of the rock and the joints as well as the joint spacing and orientation are inferred from experimental test data, and geophysical and geological characterization of the SPE site which is dominantly Climax Stock granitic outcrop. The role of various factors characterizing the joints such as joint spacing, frictional properties, orientation and persistence in generation of non-radial motion is addressed. The joints in granite at the SPE site are oriented in nearly orthogonal directions with two vertical sets dipping at 70-80 degrees with the same strike angle, one vertical set almost orthogonal to the first two and one shallow angle joint set dipping 15 degrees. In this study we establish the relationship between the joint orientation and azimuthal variations in the polarity of the observed shear motion. The majority of the shear motion is generated due to the effects of non-elastic sliding on the joints near the source, where the wave can create significant shear stress to overcome the cohesive forces at the joints. Near the surface the joints are less confined and are subject to sliding when the pressure waves are reflected. In the far field, where the cohesive forces on the joints cannot be overcome, additional shear motion can be generated due to elastic anisotropy of the rock mass given by preferred spatial orientations of compliant joints.

Characterizing rare-event property distributions via replicate molecular dynamics simulations of proteins.

PubMed

Krishnan, Ranjani; Walton, Emily B; Van Vliet, Krystyn J

2009-11-01

As computational resources increase, molecular dynamics simulations of biomolecules are becoming an increasingly informative complement to experimental studies. In particular, it has now become feasible to use multiple initial molecular configurations to generate an ensemble of replicate production-run simulations that allows for more complete characterization of rare events such as ligand-receptor unbinding. However, there are currently no explicit guidelines for selecting an ensemble of initial configurations for replicate simulations. Here, we use clustering analysis and steered molecular dynamics simulations to demonstrate that the configurational changes accessible in molecular dynamics simulations of biomolecules do not necessarily correlate with observed rare-event properties. This informs selection of a representative set of initial configurations. We also employ statistical analysis to identify the minimum number of replicate simulations required to sufficiently sample a given biomolecular property distribution. Together, these results suggest a general procedure for generating an ensemble of replicate simulations that will maximize accurate characterization of rare-event property distributions in biomolecules.

Mechanical response of unidirectional boron/aluminum under combined loading

NASA Technical Reports Server (NTRS)

Becker, Wolfgang; Pindera, Marek-Jerzy; Herakovich, Carl T.

1987-01-01

Three test methods were employed to characterize the response of unidirectional Boron/Aluminum metal matrix composite material under monotonic and cyclic loading conditions, namely, losipescu shear, off-axis tension and compression. The characterization of the elastic and plastic response includes the elastic material properties, yielding and subsequent hardening of the unidirectional composite under different stress ratios in the material principal coordinate system. Yield loci generated for different stress ratios are compared for the three different test methods, taking into account residual stresses and specimen geometry. Subsequently, the yield locus for in-plane shear is compared with the prediction of an analytical, micromechanical model. The influence of the scatter in the experimental data on the predicted yield surface is also analyzed. Lastly, the experimental material strengths in tension and compression are correlated with the maximum stress and the Tsai-Wu failure criterion.

Mechanical behavior and fracture characteristics of off-axis fiber composites. 1: Experimental investigation. [at the Lewis Research Center

NASA Technical Reports Server (NTRS)

Sinclair, J. H.; Chamis, C. C.

1977-01-01

The mechanical behavior, fracture surfaces, and fracture modes of unidirectional high-modulus graphite-fiber/epoxy composites subjected to off-axis tensile loads were investigated experimentally. The investigation included the generation of stress-strain-to-fracture data and scanning electron microscope studies of the fractured surfaces. The results led to the identification of fracture modes and distinct fracture surface characteristics for off-axis tensile loading. The results also led to the formulation of critical for identifying and characterizing these fracture modes and their associated fracture surfaces. The results presented and discussed herein were used in the theoretical investigation and comparisons described in Part 2. These results should also provide a good foundation for identifying, characterizing, and quantifying fracture modes in both off-axis and angle-plied laminates.

An Italian network to improve hybrid rocket performance: Strategy and results

NASA Astrophysics Data System (ADS)

Galfetti, L.; Nasuti, F.; Pastrone, D.; Russo, A. M.

2014-03-01

The new international attention to hybrid space propulsion points out the need of a deeper understanding of physico-chemical phenomena controlling combustion process and fluid dynamics inside the motor. This research project has been carried on by a network of four Italian Universities; each of them being responsible for a specific topic. The task of Politecnico di Milano is an experimental activity concerning the study, development, manufacturing and characterization of advanced hybrid solid fuels with a high regression rate. The University of Naples is responsible for experimental activities focused on rocket motor scale characterization of the solid fuels developed and characterized at laboratory scale by Politecnico di Milano. The University of Rome has been studying the combustion chamber and nozzle of the hybrid rocket, defined in the coordinated program by advanced physical-mathematical models and numerical methods. Politecnico di Torino has been working on a multidisciplinary optimization code for optimal design of hybrid rocket motors, strongly related to the mission to be performed. The overall research project aims to increase the scientific knowledge of the combustion processes in hybrid rockets, using a strongly linked experimental-numerical approach. Methods and obtained results will be applied to implement a potential upgrade for the current generation of hybrid rocket motors. This paper presents the overall strategy, the organization, and the first experimental and numerical results of this joined effort to contribute to the development of improved hybrid propulsion systems.

Characterization and simulation of noise in PET images reconstructed with OSEM: Development of a method for the generation of synthetic images.

PubMed

Castro, P; Huerga, C; Chamorro, P; Garayoa, J; Roch, M; Pérez, L

2018-04-17

The goals of the study are to characterize imaging properties in 2D PET images reconstructed with the iterative algorithm ordered-subset expectation maximization (OSEM) and to propose a new method for the generation of synthetic images. The noise is analyzed in terms of its magnitude, spatial correlation, and spectral distribution through standard deviation, autocorrelation function, and noise power spectrum (NPS), respectively. Their variations with position and activity level are also analyzed. This noise analysis is based on phantom images acquired from 18 F uniform distributions. Experimental recovery coefficients of hot spheres in different backgrounds are employed to study the spatial resolution of the system through point spread function (PSF). The NPS and PSF functions provide the baseline for the proposed simulation method: convolution with PSF as kernel and noise addition from NPS. The noise spectral analysis shows that the main contribution is of random nature. It is also proven that attenuation correction does not alter noise texture but it modifies its magnitude. Finally, synthetic images of 2 phantoms, one of them an anatomical brain, are quantitatively compared with experimental images showing a good agreement in terms of pixel values and pixel correlations. Thus, the contrast to noise ratio for the biggest sphere in the NEMA IEC phantom is 10.7 for the synthetic image and 8.8 for the experimental image. The properties of the analyzed OSEM-PET images can be described by NPS and PSF functions. Synthetic images, even anatomical ones, are successfully generated by the proposed method based on the NPS and PSF. Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.

Induction of a specific strong polyantigenic cellular immune response after short-term chemotherapy controls bacillary reactivation in murine and guinea pig experimental models of tuberculosis.

PubMed

Guirado, Evelyn; Gil, Olga; Cáceres, Neus; Singh, Mahavir; Vilaplana, Cristina; Cardona, Pere-Joan

2008-08-01

RUTI is a therapeutic vaccine that is generated from detoxified and liposomed Mycobacterium tuberculosis cell fragments that has demonstrated its efficacy in the control of bacillus reactivation after short-term chemotherapy. The aim of this study was to characterize the cellular immune response generated after the therapeutic administration of RUTI and to corroborate the lack of toxicity of the vaccine. Mouse and guinea pig experimental models were infected with a low-dose M. tuberculosis aerosol. RUTI-treated animals showed the lowest bacillary load in both experimental models. RUTI also decreased the percentage of pulmonary granulomatous infiltration in the mouse and guinea pig models. This was not the case after Mycobacterium bovis BCG treatment. Cellular immunity was studied through the characterization of the intracellular gamma interferon (IFN-gamma)-producing cells after the splenocytes' stimulation with M. tuberculosis-specific structural and growth-related antigens. Our data show that the difference between the therapeutic administration of BCG and RUTI resides mainly in the stronger activation of IFN-gamma(+) CD4(+) cells and CD8(+) cells against tuberculin purified protein derivative, ESAT-6, and Ag85B that RUTI generates. Both vaccines also triggered a specific immune response against the M. tuberculosis structural antigens Ag16kDa and Ag38kDa and a marked mRNA expression of IFN-gamma, tumor necrosis factor, interleukin-12, inducible nitric oxide synthase, and RANTES in the lung. The results show that RUTI's therapeutic effect is linked not only to the induction of a Th1 response but also to the stimulation of a quicker and stronger specific immunity against structural and growth-related antigens that reduces both the bacillary load and the pulmonary pathology.

Induction of a Specific Strong Polyantigenic Cellular Immune Response after Short-Term Chemotherapy Controls Bacillary Reactivation in Murine and Guinea Pig Experimental Models of Tuberculosis▿

PubMed Central

Guirado, Evelyn; Gil, Olga; Cáceres, Neus; Singh, Mahavir; Vilaplana, Cristina; Cardona, Pere-Joan

2008-01-01

RUTI is a therapeutic vaccine that is generated from detoxified and liposomed Mycobacterium tuberculosis cell fragments that has demonstrated its efficacy in the control of bacillus reactivation after short-term chemotherapy. The aim of this study was to characterize the cellular immune response generated after the therapeutic administration of RUTI and to corroborate the lack of toxicity of the vaccine. Mouse and guinea pig experimental models were infected with a low-dose M. tuberculosis aerosol. RUTI-treated animals showed the lowest bacillary load in both experimental models. RUTI also decreased the percentage of pulmonary granulomatous infiltration in the mouse and guinea pig models. This was not the case after Mycobacterium bovis BCG treatment. Cellular immunity was studied through the characterization of the intracellular gamma interferon (IFN-γ)-producing cells after the splenocytes' stimulation with M. tuberculosis-specific structural and growth-related antigens. Our data show that the difference between the therapeutic administration of BCG and RUTI resides mainly in the stronger activation of IFN-γ+ CD4+ cells and CD8+ cells against tuberculin purified protein derivative, ESAT-6, and Ag85B that RUTI generates. Both vaccines also triggered a specific immune response against the M. tuberculosis structural antigens Ag16kDa and Ag38kDa and a marked mRNA expression of IFN-γ, tumor necrosis factor, interleukin-12, inducible nitric oxide synthase, and RANTES in the lung. The results show that RUTI's therapeutic effect is linked not only to the induction of a Th1 response but also to the stimulation of a quicker and stronger specific immunity against structural and growth-related antigens that reduces both the bacillary load and the pulmonary pathology. PMID:18524883

Inelastic response of metal matrix composites under biaxial loading

NASA Technical Reports Server (NTRS)

Mirzadeh, F.; Pindera, Marek-Jerzy; Herakovich, Carl T.

1990-01-01

Elements of the analytical/experimental program to characterize the response of silicon carbide titanium (SCS-6/Ti-15-3) composite tubes under biaxial loading are outlined. The analytical program comprises prediction of initial yielding and subsequent inelastic response of unidirectional and angle-ply silicon carbide titanium tubes using a combined micromechanics approach and laminate analysis. The micromechanics approach is based on the method of cells model and has the capability of generating the effective thermomechanical response of metal matrix composites in the linear and inelastic region in the presence of temperature and time-dependent properties of the individual constituents and imperfect bonding on the initial yield surfaces and inelastic response of (0) and (+ or - 45)sub s SCS-6/Ti-15-3 laminates loaded by different combinations of stresses. The generated analytical predictions will be compared with the experimental results. The experimental program comprises generation of initial yield surfaces, subsequent stress-strain curves and determination of failure loads of the SCS-6/Ti-15-3 tubes under selected loading conditions. The results of the analytical investigation are employed to define the actual loading paths for the experimental program. A brief overview of the experimental methodology is given. This includes the test capabilities of the Composite Mechanics Laboratory at the University of Virginia, the SCS-6/Ti-15-3 composite tubes secured from McDonnell Douglas Corporation, a text fixture specifically developed for combined axial-torsional loading, and the MTS combined axial-torsion loader that will be employed in the actual testing.

Characterization of short-pulse laser-produced x-rays for diagnosing magnetically driven cylindrical isentropic compression

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi; Daykin, Tyler; Bauer, Bruno; Beg, Farhat

2017-10-01

We have developed an experimental platform to study material properties of magnetically compressed cylinder using a 1 MA pulsed power generator Zebra and a 50 TW subpicosecond short-pulse laser Leopard at the UNR's Nevada Terawatt Facility. According to a MHD simulation, strong magnetic fields generated by 100 ns rise time Zebra current can quasi-isentropically compress a material to the strongly coupled plasma regime. Taking advantage of the cylindrical geometry, a metal rod can be brought to higher pressures than that in the planar geometry. To diagnose the compressed rod with high precision x-ray measurements, an initial laser-only experiment was carried out to characterize laser-produced x-rays. Interaction of a high-intensity, short-pulse laser with solids produces broadband and monochromatic x-rays with photon energies high enough to probe dense metal rods. Bremsstrahlung was measured with Imaging plate-based filter stack spectrometers and monochromatic 8.0 keV Cu K-alpha was recorded with an absolutely calibrated Bragg crystal spectrometer. The broadband x-ray source was applied to radiography of thick metal objects and different filter materials were tested. The experimental results and a design of a coupled experiment will be presented.

Multi-model approach to characterize human handwriting motion.

PubMed

Chihi, I; Abdelkrim, A; Benrejeb, M

2016-02-01

This paper deals with characterization and modelling of human handwriting motion from two forearm muscle activity signals, called electromyography signals (EMG). In this work, an experimental approach was used to record the coordinates of a pen tip moving on the (x, y) plane and EMG signals during the handwriting act. The main purpose is to design a new mathematical model which characterizes this biological process. Based on a multi-model approach, this system was originally developed to generate letters and geometric forms written by different writers. A Recursive Least Squares algorithm is used to estimate the parameters of each sub-model of the multi-model basis. Simulations show good agreement between predicted results and the recorded data.

Experimental investigation of an inversion technique for the determination of broadband duct mode amplitudes by the use of near-field sensor arrays.

PubMed

Castres, Fabrice O; Joseph, Phillip F

2007-08-01

This paper is an experimental investigation of an inverse technique for deducing the amplitudes of the modes radiated from a turbofan engine, including schemes for stablizing the solution. The detection of broadband modes generated by a laboratory-scaled fan inlet is performed using a near-field array of microphones arranged in a geodesic geometry. This array geometry is shown to allow a robust and accurate modal inversion. The sound power radiated from the fan inlet and the coherence function between different modal amplitudes are also presented. The knowledge of such modal content is useful in helping to characterize the source mechanisms of fan broadband noise generation, for determining the most appropriate mode distribution model for duct liner predictions, and for making sound power measurements of the radiated sound field.

Validation of Laser-Induced Fluorescent Photogrammetric Targets on Membrane Structures

NASA Technical Reports Server (NTRS)

Jones, Thomas W.; Dorrington, Adrian A.; Shortis, Mark R.; Hendricks, Aron R.

2004-01-01

The need for static and dynamic characterization of a new generation of inflatable space structures requires the advancement of classical metrology techniques. A new photogrammetric-based method for non-contact ranging and surface profiling has been developed at NASA Langley Research Center (LaRC) to support modal analyses and structural validation of this class of space structures. This full field measurement method, known as Laser-Induced Fluorescence (LIF) photogrammetry, has previously yielded promising experimental results. However, data indicating the achievable measurement precision had not been published. This paper provides experimental results that indicate the LIF-photogrammetry measurement precision for three different target types used on a reflective membrane structure. The target types were: (1) non-contact targets generated using LIF, (2) surface attached retro-reflective targets, and (3) surface attached diffuse targets. Results from both static and dynamic investigations are included.

Characterization of Dispersive Ultrasonic Rayleigh Surface Waves in Asphalt Concrete

NASA Astrophysics Data System (ADS)

In, Chi-Won; Kim, Jin-Yeon; Jacobs, Laurence J.; Kurtis, Kimberly E.

2008-02-01

This research focuses on the application of ultrasonic Rayleigh surface waves to nondestructively characterize the mechanical properties and structural defects (non-uniformly distributed aggregate) in asphalt concrete. An efficient wedge technique is developed in this study to generate Rayleigh surface waves that is shown to be effective in characterizing Rayleigh waves in this highly viscoelastic (attenuating) and heterogeneous medium. Experiments are performed on an asphalt-concrete beam produced with uniformly distributed aggregate. Ultrasonic techniques using both contact and non-contact sensors are examined and their results are compared. Experimental results show that the wedge technique along with an air-coupled sensor appears to be effective in characterizing Rayleigh waves in asphalt concrete. Hence, measurement of theses material properties needs to be investigated in non-uniformly distributed aggregate material using these techniques.

Strong terahertz field generation, detection, and application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ki-Yong

2016-05-22

This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-drivenmore » extremely nonlinear phenomena in a university laboratory.« less

Strong terahertz field generation, detection, and application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Ki-Yong

2016-05-15

This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-drivenmore » extremely nonlinear phenomena in a university laboratory.« less

Cryogenic Autogenous Pressurization Testing for Robotic Refueling Mission 3

NASA Technical Reports Server (NTRS)

Boyle, R.; DiPirro, M.; Tuttle, J.; Francis, J.; Mustafi, S.; Li, X.; Barfknecht, P.; DeLee, C. H.; McGuire, J.

2015-01-01

A wick-heater system has been selected for use to pressurize the Source Dewar of the Robotic Refueling Mission Phase 3 on-orbit cryogen transfer experiment payload for the International Space Station. Experimental results of autogenous pressurization of liquid argon and liquid nitrogen using a prototype wick-heater system are presented. The wick-heater generates gas to increase the pressure in the tank while maintaining a low bulk fluid temperature. Pressurization experiments were performed in 2013 to characterize the performance of the wick heater. This paper describes the experimental setup, pressurization results, and analytical model correlations.

Density waves in granular flow

NASA Astrophysics Data System (ADS)

Herrmann, H. J.; Flekkøy, E.; Nagel, K.; Peng, G.; Ristow, G.

Ample experimental evidence has shown the existence of spontaneous density waves in granular material flowing through pipes or hoppers. Using Molecular Dynamics Simulations we show that several types of waves exist and find that these density fluctuations follow a 1/f spectrum. We compare this behaviour to deterministic one-dimensional traffic models. If positions and velocities are continuous variables the model shows self-organized criticality driven by the slowest car. We also present Lattice Gas and Boltzmann Lattice Models which reproduce the experimentally observed effects. Density waves are spontaneously generated when the viscosity has a nonlinear dependence on density which characterizes granular flow.

Characterization of the proton beam from an IBA Cyclone 18/9 with radiochromic film EBT2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sansaloni, F.; Lagares, J. I.; Arce, P.

2012-12-19

The use of radiochromic films is widespread in different areas of medical physics like radiotherapy and hadrontherapy; however, radiochromic films have been scarcely used in the characterization of proton or deuteron beams generated in biomedical cyclotrons. In this paper the radiochromic film EBT2 was used to study the beam size and the proton beam energy of an IBA Cyclone 18/9 cyclotron. The results indicate that the beam size can be easily measured at a very low expense; however, an accurate determination of the beam energy might require the implementation of certain experimental improvements.

A new experimental method for the accelerated characterization of composite materials

NASA Technical Reports Server (NTRS)

Brinson, H. F.; Morris, D. H.; Yeow, Y. T.

1978-01-01

A method which permits the prediction of long-term properties of graphite/epoxy laminates on the basis of short-term (15 min) laboratory tests is described. Demonstration of delayed viscoelastic fracture in one laminate configuration, and data on the time and temperature response of a matrix-dominated unidirectional laminate contributed to a characterization of the viscoelastic process in the graphite/epoxy composites. Master curves from short-term tests of certain laminate configurations can be employed to generate long-term master curves. In addition, analytical predictions from short-term results can be used to predict long-term (25-hour) laminate properties.

Evaluation of smallpox vaccines using variola neutralization

PubMed Central

Damon, Inger K.; Davidson, Whitni B.; Hughes, Christine M.; Olson, Victoria A.; Smith, Scott K.; Holman, Robert C.; Frey, Sharon E.; Newman, Frances; Belshe, Robert B.; Yan, Lihan; Karem, Kevin

2009-01-01

The search for a ‘third’-generation smallpox vaccine has resulted in the development and characterization of several vaccine candidates. A significant barrier to acceptance is the absence of challenge models showing induction of correlates of protective immunity against variola virus. In this light, virus neutralization provides one of few experimental methods to show specific ‘in vitro’ activity of vaccines against variola virus. Here, we provide characterization of the ability of a modified vaccinia virus Ankara vaccine to induce variola virus-neutralizing antibodies, and we provide comparison with the neutralization elicited by standard Dryvax vaccination. PMID:19339477

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hattrick-Simpers, Jason R.; Gregoire, John M.; Kusne, A. Gilad

With their ability to rapidly elucidate composition-structure-property relationships, high-throughput experimental studies have revolutionized how materials are discovered, optimized, and commercialized. It is now possible to synthesize and characterize high-throughput libraries that systematically address thousands of individual cuts of fabrication parameter space. An unresolved issue remains transforming structural characterization data into phase mappings. This difficulty is related to the complex information present in diffraction and spectroscopic data and its variation with composition and processing. Here, we review the field of automated phase diagram attribution and discuss the impact that emerging computational approaches will have in the generation of phase diagrams andmore » beyond.« less

Experimental characterization of nonlinear, rate-dependent behavior in advanced polymer matrix composites

NASA Technical Reports Server (NTRS)

Gates, Thomas S.

1992-01-01

In order to support materials selection for the next-generation supersonic civilian-passenger transport aircraft, a study has been undertaken to evaluate the material stress/strain relationships needed to describe advanced polymer matrix composites under conditions of high load and elevated temperature. As part of this effort, this paper describes the materials testing which was performed to investigate the viscoplastic behavior of graphite/thermoplastic and graphite/bismaleimide composites. Test procedures, results and data-reduction schemes which were developed for generating material constants for tension and compression loading, over a range of useful temperatures, are explained.

Comparison of natural gases accumulated in Oligocene strata with hydrous pyrolysis gases from Menilite Shales of the Polish Outer Carpathians

USGS Publications Warehouse

Kotarba, M.J.; Curtis, John B.; Lewan, M.D.

2009-01-01

This study examined the molecular and isotopic compositions of gases generated from different kerogen types (i.e., Types I/II, II, IIS and III) in Menilite Shales by sequential hydrous pyrolysis experiments. The experiments were designed to simulate gas generation from source rocks at pre-oil-cracking thermal maturities. Initially, rock samples were heated in the presence of liquid water at 330 ??C for 72 h to simulate early gas generation dominated by the overall reaction of kerogen decomposition to bitumen. Generated gas and oil were quantitatively collected at the completion of the experiments and the reactor with its rock and water was resealed and heated at 355 ??C for 72 h. This condition simulates late petroleum generation in which the dominant overall reaction is bitumen decomposition to oil. This final heating equates to a cumulative thermal maturity of 1.6% Rr, which represents pre-oil-cracking conditions. In addition to the generated gases from these two experiments being characterized individually, they are also summed to characterize a cumulative gas product. These results are compared with natural gases produced from sandstone reservoirs within or directly overlying the Menilite Shales. The experimentally generated gases show no molecular compositions that are distinct for the different kerogen types, but on a total organic carbon (TOC) basis, oil prone kerogens (i.e., Types I/II, II and IIS) generate more hydrocarbon gas than gas prone Type III kerogen. Although the proportionality of methane to ethane in the experimental gases is lower than that observed in the natural gases, the proportionality of ethane to propane and i-butane to n-butane are similar to those observed for the natural gases. ??13C values of the experimentally generated methane, ethane and propane show distinctions among the kerogen types. This distinction is related to the ??13C of the original kerogen, with 13C enriched kerogen generating more 13C enriched hydrocarbon gases than kerogen less enriched in 13C. The typically assumed linear trend for ??13C of methane, ethane and propane versus their reciprocal carbon number for a single sourced natural gas is not observed in the experimental gases. Instead, the so-called "dogleg" trend, exemplified by relatively 13C depleted methane and enriched propane as compared to ethane, is observed for all the kerogen types and at both experimental conditions. Three of the natural gases from the same thrust unit had similar "dogleg" trends indicative of Menilite source rocks with Type III kerogen. These natural gases also contained varying amounts of a microbial gas component that was approximated using the ????13C for methane and propane determined from the experiments. These approximations gave microbial methane components that ranged from 13-84%. The high input of microbial gas was reflected in the higher gas:oil ratios for Outer Carpathian production (115-1568 Nm3/t) compared with those determined from the experiments (65-302 Nm3/t). Two natural gas samples in the far western part of the study area had more linear trends that suggest a different organic facies of the Menilite Shales or a completely different source. This situation emphasizes the importance of conducting hydrous pyrolysis on samples representing the complete stratigraphic and lateral extent of potential source rocks in determining specific genetic gas correlations. ?? 2009 Elsevier Ltd.

Practical characterization of quantum devices without tomography

NASA Astrophysics Data System (ADS)

Landon-Cardinal, Olivier; Flammia, Steven; Silva, Marcus; Liu, Yi-Kai; Poulin, David

2012-02-01

Quantum tomography is the main method used to assess the quality of quantum information processing devices, but its complexity presents a major obstacle for the characterization of even moderately large systems. Part of the reason for this complexity is that tomography generates much more information than is usually sought. Taking a more targeted approach, we develop schemes that enable (i) estimating the ?delity of an experiment to a theoretical ideal description, (ii) learning which description within a reduced subset best matches the experimental data. Both these approaches yield a signi?cant reduction in resources compared to tomography. In particular, we show how to estimate the ?delity between a predicted pure state and an arbitrary experimental state using only a constant number of Pauli expectation values selected at random according to an importance-weighting rule. In addition, we propose methods for certifying quantum circuits and learning continuous-time quantum dynamics that are described by local Hamiltonians or Lindbladians.

Laboratory test methods for combustion stability properties of solid propellants

NASA Technical Reports Server (NTRS)

Strand, L. D.; Brown, R. S.

1992-01-01

An overview is presented of experimental methods for determining the combustion-stability properties of solid propellants. The methods are generally based on either the temporal response to an initial disturbance or on external methods for generating the required oscillations. The size distribution of condensed-phase combustion products are characterized by means of the experimental approaches. The 'T-burner' approach is shown to assist in the derivation of pressure-coupled driving contributions and particle damping in solid-propellant rocket motors. Other techniques examined include the rotating-valve apparatus, the impedance tube, the modulated throat-acoustic damping burner, and the magnetic flowmeter. The paper shows that experimental methods do not exist for measuring the interactions between acoustic velocity oscillations and burning propellant.

Efficient high-throughput biological process characterization: Definitive screening design with the ambr250 bioreactor system.

PubMed

Tai, Mitchell; Ly, Amanda; Leung, Inne; Nayar, Gautam

2015-01-01

The burgeoning pipeline for new biologic drugs has increased the need for high-throughput process characterization to efficiently use process development resources. Breakthroughs in highly automated and parallelized upstream process development have led to technologies such as the 250-mL automated mini bioreactor (ambr250™) system. Furthermore, developments in modern design of experiments (DoE) have promoted the use of definitive screening design (DSD) as an efficient method to combine factor screening and characterization. Here we utilize the 24-bioreactor ambr250™ system with 10-factor DSD to demonstrate a systematic experimental workflow to efficiently characterize an Escherichia coli (E. coli) fermentation process for recombinant protein production. The generated process model is further validated by laboratory-scale experiments and shows how the strategy is useful for quality by design (QbD) approaches to control strategies for late-stage characterization. © 2015 American Institute of Chemical Engineers.

Broadband Microwave Study of Reaction Intermediates and Products Through the Pyrolysis of Oxygenated Biofuels

NASA Astrophysics Data System (ADS)

Abeysekera, Chamara; Hernandez-Castillo, Alicia O.; Fritz, Sean; Zwier, Timothy S.

2017-06-01

The rapidly growing list of potential plant-derived biofuels creates a challenge for the scientific community to provide a molecular-scale understanding of their combustion. Development of accurate combustion models rests on a foundation of experimental data on the kinetics and product branching ratios of their individual reaction steps. Therefore, new spectroscopic tools are necessary to selectively detect and characterize fuel components and reactive intermediates generated by pyrolysis and combustion. Substituted furans, including furanic ethers, are considered second-generation biofuel candidates. Following the work of the Ellison group, an 8-18 GHz microwave study was carried out on the unimolecular and bimolecular decomposition of the smallest furanic ether, 2-methoxy furan, and it`s pyrolysis intermediate, the 2-furanyloxy radical, formed in a high-temperature pyrolysis source coupled to a supersonic expansion. Details of the experimental setup and analysis of the spectrum of the radical will be discussed.

Dynamic electromechanical characterization of the ferroelectric ceramic PZT 95/5

NASA Astrophysics Data System (ADS)

Setchell, R. E.; Chhabildas, L. C.; Furnish, M. D.; Montgomery, S. T.; Holman, G. T.

1998-07-01

Shock-induced depoling of the ferroelectric ceramic PZT 95/5 has been utilized in pulsed power applications for many years. Recently, new design and certification requirements have generated a strong interest in numerically simulating the operation of pulsed power devices. Because of a scarcity of relevant experimental data obtained within the past twenty years, we have initiated an extensive experimental study of the dynamic behavior of this material in support of simulation efforts. The experiments performed to date have been limited to examining the behavior of unpoled material. Samples of PZT 95/5 have been shocked to axial stresses from 0.5 to 5.0 GPa in planar impact experiments. Impact face conditions have been recorded using PVDF stress gauges, and transmitted wave profiles have been recorded either at window interfaces or at a free surface using laser interferometry (VISAR). The results significantly extend the stresses examined in prior studies of unpoled material, and ensure that a comprehensive experimental characterization of the mechanical behavior under shock loading is available for continuing development of PZT 95/5 material models.

Etch depth mapping of phase binary computer-generated holograms by means of specular spectroscopic scatterometry

NASA Astrophysics Data System (ADS)

Korolkov, Victor P.; Konchenko, Alexander S.; Cherkashin, Vadim V.; Mironnikov, Nikolay G.; Poleshchuk, Alexander G.

2013-09-01

Detailed analysis of etch depth map for phase binary computer-generated holograms intended for testing aspheric optics is a very important task. In particular, diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. We offer a simplified version of the specular spectroscopic scatterometry method. It is based on the spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase the phase depth of the grooves by a factor of 2 and measure more precisely shallow phase gratings. Measurement uncertainty is mainly defined by the following parameters: shifts of the spectrum maximums that occur due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method we describe can ensure 1% error. However, fiber spectrometers are more convenient for scanning measurements of large area computer-generated holograms. Our experimental system for characterization of binary computer-generated holograms was developed using a fiber spectrometer.

Fundamental Understanding of Crack Growth in Structural Components of Generation IV Supercritical Light Water Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iouri I. Balachov; Takao Kobayashi; Francis Tanzella

2004-11-17

This work contributes to the design of safe and economical Generation-IV Super-Critical Water Reactors (SCWRs) by providing a basis for selecting structural materials to ensure the functionality of in-vessel components during the entire service life. During the second year of the project, we completed electrochemical characterization of the oxide film properties and investigation of crack initiation and propagation for candidate structural materials steels under supercritical conditions. We ranked candidate alloys against their susceptibility to environmentally assisted degradation based on the in situ data measure with an SRI-designed controlled distance electrochemistry (CDE) arrangement. A correlation between measurable oxide film properties andmore » susceptibility of austenitic steels to environmentally assisted degradation was observed experimentally. One of the major practical results of the present work is the experimentally proven ability of the economical CDE technique to supply in situ data for ranking candidate structural materials for Generation-IV SCRs. A potential use of the CDE arrangement developed ar SRI for building in situ sensors monitoring water chemistry in the heat transport circuit of Generation-IV SCWRs was evaluated and proved to be feasible.« less

Experimental Estimation of Mutation Rates in a Wheat Population With a Gene Genealogy Approach

PubMed Central

Raquin, Anne-Laure; Depaulis, Frantz; Lambert, Amaury; Galic, Nathalie; Brabant, Philippe; Goldringer, Isabelle

2008-01-01

Microsatellite markers are extensively used to evaluate genetic diversity in natural or experimental evolving populations. Their high degree of polymorphism reflects their high mutation rates. Estimates of the mutation rates are therefore necessary when characterizing diversity in populations. As a complement to the classical experimental designs, we propose to use experimental populations, where the initial state is entirely known and some intermediate states have been thoroughly surveyed, thus providing a short timescale estimation together with a large number of cumulated meioses. In this article, we derived four original gene genealogy-based methods to assess mutation rates with limited bias due to relevant model assumptions incorporating the initial state, the number of new alleles, and the genetic effective population size. We studied the evolution of genetic diversity at 21 microsatellite markers, after 15 generations in an experimental wheat population. Compared to the parents, 23 new alleles were found in generation 15 at 9 of the 21 loci studied. We provide evidence that they arose by mutation. Corresponding estimates of the mutation rates ranged from 0 to 4.97 × 10−3 per generation (i.e., year). Sequences of several alleles revealed that length polymorphism was only due to variation in the core of the microsatellite. Among different microsatellite characteristics, both the motif repeat number and an independent estimation of the Nei diversity were correlated with the novel diversity. Despite a reduced genetic effective size, global diversity at microsatellite markers increased in this population, suggesting that microsatellite diversity should be used with caution as an indicator in biodiversity conservation issues. PMID:18689900

Experimental estimation of mutation rates in a wheat population with a gene genealogy approach.

PubMed

Raquin, Anne-Laure; Depaulis, Frantz; Lambert, Amaury; Galic, Nathalie; Brabant, Philippe; Goldringer, Isabelle

2008-08-01

Microsatellite markers are extensively used to evaluate genetic diversity in natural or experimental evolving populations. Their high degree of polymorphism reflects their high mutation rates. Estimates of the mutation rates are therefore necessary when characterizing diversity in populations. As a complement to the classical experimental designs, we propose to use experimental populations, where the initial state is entirely known and some intermediate states have been thoroughly surveyed, thus providing a short timescale estimation together with a large number of cumulated meioses. In this article, we derived four original gene genealogy-based methods to assess mutation rates with limited bias due to relevant model assumptions incorporating the initial state, the number of new alleles, and the genetic effective population size. We studied the evolution of genetic diversity at 21 microsatellite markers, after 15 generations in an experimental wheat population. Compared to the parents, 23 new alleles were found in generation 15 at 9 of the 21 loci studied. We provide evidence that they arose by mutation. Corresponding estimates of the mutation rates ranged from 0 to 4.97 x 10(-3) per generation (i.e., year). Sequences of several alleles revealed that length polymorphism was only due to variation in the core of the microsatellite. Among different microsatellite characteristics, both the motif repeat number and an independent estimation of the Nei diversity were correlated with the novel diversity. Despite a reduced genetic effective size, global diversity at microsatellite markers increased in this population, suggesting that microsatellite diversity should be used with caution as an indicator in biodiversity conservation issues.

Modeling and simulation of pressure waves generated by nano-thermite reactions

NASA Astrophysics Data System (ADS)

Martirosyan, Karen S.; Zyskin, Maxim; Jenkins, Charles M.; (Yuki) Horie, Yasuyuki

2012-11-01

This paper reports the modeling of pressure waves from the explosive reaction of nano-thermites consisting of mixtures of nanosized aluminum and oxidizer granules. Such nanostructured thermites have higher energy density (up to 26 kJ/cm3) and can generate a transient pressure pulse four times larger than that from trinitrotoluene (TNT) based on volume equivalence. A plausible explanation for the high pressure generation is that the reaction times are much shorter than the time for a shock wave to propagate away from the reagents region so that all the reaction energy is dumped into the gaseous products almost instantaneously and thereby a strong shock wave is generated. The goal of the modeling is to characterize the gas dynamic behavior for thermite reactions in a cylindrical reaction chamber and to model the experimentally measured pressure histories. To simplify the details of the initial stage of the explosive reaction, it is assumed that the reaction generates a one dimensional shock wave into an air-filled cylinder and propagates down the tube in a self-similar mode. Experimental data for Al/Bi2O3 mixtures were used to validate the model with attention focused on the ratio of specific heats and the drag coefficient. Model predictions are in good agreement with the measured pressure histories.

Exhaustively characterizing feasible logic models of a signaling network using Answer Set Programming.

PubMed

Guziolowski, Carito; Videla, Santiago; Eduati, Federica; Thiele, Sven; Cokelaer, Thomas; Siegel, Anne; Saez-Rodriguez, Julio

2013-09-15

Logic modeling is a useful tool to study signal transduction across multiple pathways. Logic models can be generated by training a network containing the prior knowledge to phospho-proteomics data. The training can be performed using stochastic optimization procedures, but these are unable to guarantee a global optima or to report the complete family of feasible models. This, however, is essential to provide precise insight in the mechanisms underlaying signal transduction and generate reliable predictions. We propose the use of Answer Set Programming to explore exhaustively the space of feasible logic models. Toward this end, we have developed caspo, an open-source Python package that provides a powerful platform to learn and characterize logic models by leveraging the rich modeling language and solving technologies of Answer Set Programming. We illustrate the usefulness of caspo by revisiting a model of pro-growth and inflammatory pathways in liver cells. We show that, if experimental error is taken into account, there are thousands (11 700) of models compatible with the data. Despite the large number, we can extract structural features from the models, such as links that are always (or never) present or modules that appear in a mutual exclusive fashion. To further characterize this family of models, we investigate the input-output behavior of the models. We find 91 behaviors across the 11 700 models and we suggest new experiments to discriminate among them. Our results underscore the importance of characterizing in a global and exhaustive manner the family of feasible models, with important implications for experimental design. caspo is freely available for download (license GPLv3) and as a web service at http://caspo.genouest.org/. Supplementary materials are available at Bioinformatics online. santiago.videla@irisa.fr.

Exhaustively characterizing feasible logic models of a signaling network using Answer Set Programming

PubMed Central

Guziolowski, Carito; Videla, Santiago; Eduati, Federica; Thiele, Sven; Cokelaer, Thomas; Siegel, Anne; Saez-Rodriguez, Julio

2013-01-01

Motivation: Logic modeling is a useful tool to study signal transduction across multiple pathways. Logic models can be generated by training a network containing the prior knowledge to phospho-proteomics data. The training can be performed using stochastic optimization procedures, but these are unable to guarantee a global optima or to report the complete family of feasible models. This, however, is essential to provide precise insight in the mechanisms underlaying signal transduction and generate reliable predictions. Results: We propose the use of Answer Set Programming to explore exhaustively the space of feasible logic models. Toward this end, we have developed caspo, an open-source Python package that provides a powerful platform to learn and characterize logic models by leveraging the rich modeling language and solving technologies of Answer Set Programming. We illustrate the usefulness of caspo by revisiting a model of pro-growth and inflammatory pathways in liver cells. We show that, if experimental error is taken into account, there are thousands (11 700) of models compatible with the data. Despite the large number, we can extract structural features from the models, such as links that are always (or never) present or modules that appear in a mutual exclusive fashion. To further characterize this family of models, we investigate the input–output behavior of the models. We find 91 behaviors across the 11 700 models and we suggest new experiments to discriminate among them. Our results underscore the importance of characterizing in a global and exhaustive manner the family of feasible models, with important implications for experimental design. Availability: caspo is freely available for download (license GPLv3) and as a web service at http://caspo.genouest.org/. Supplementary information: Supplementary materials are available at Bioinformatics online. Contact: santiago.videla@irisa.fr PMID:23853063

New technologies accelerate the exploration of non-coding RNAs in horticultural plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Degao; Mewalal, Ritesh; Hu, Rongbin

Non-coding RNAs (ncRNAs), that is, RNAs not translated into proteins, are crucial regulators of a variety of biological processes in plants. While protein-encoding genes have been relatively well-annotated in sequenced genomes, accounting for a small portion of the genome space in plants, the universe of plant ncRNAs is rapidly expanding. Recent advances in experimental and computational technologies have generated a great momentum for discovery and functional characterization of ncRNAs. Here we summarize the classification and known biological functions of plant ncRNAs, review the application of next-generation sequencing (NGS) technology and ribosome profiling technology to ncRNA discovery in horticultural plants andmore » discuss the application of new technologies, especially the new genome-editing tool clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) systems, to functional characterization of plant ncRNAs.« less

Stability characterization and modeling of robust distributed benthic microbial fuel cell (DBMFC) system.

PubMed

Karra, Udayarka; Huang, Guoxian; Umaz, Ridvan; Tenaglier, Christopher; Wang, Lei; Li, Baikun

2013-09-01

A novel and robust distributed benthic microbial fuel cell (DBMFC) was developed to address the energy supply issues for oceanographic sensor network applications, especially under scouring and bioturbation by aquatic life. Multi-anode/cathode configuration was employed in the DBMFC system for enhanced robustness and stability in the harsh ocean environment. The results showed that the DBMFC system achieved peak power and current densities of 190mW/m(2) and 125mA/m(2) respectively. Stability characterization tests indicated the DBMFC with multiple anodes achieved higher power generation over the systems with single anode. A computational model that integrated physical, electrochemical and biological factors of MFCs was developed to validate the overall performance of the DBMFC system. The model simulation well corresponded with the experimental results, and confirmed the hypothesis that using a multi anode/cathode MFC configuration results in reliable and robust power generation. Published by Elsevier Ltd.

New technologies accelerate the exploration of non-coding RNAs in horticultural plants

PubMed Central

Liu, Degao; Mewalal, Ritesh; Hu, Rongbin; Tuskan, Gerald A; Yang, Xiaohan

2017-01-01

Non-coding RNAs (ncRNAs), that is, RNAs not translated into proteins, are crucial regulators of a variety of biological processes in plants. While protein-encoding genes have been relatively well-annotated in sequenced genomes, accounting for a small portion of the genome space in plants, the universe of plant ncRNAs is rapidly expanding. Recent advances in experimental and computational technologies have generated a great momentum for discovery and functional characterization of ncRNAs. Here we summarize the classification and known biological functions of plant ncRNAs, review the application of next-generation sequencing (NGS) technology and ribosome profiling technology to ncRNA discovery in horticultural plants and discuss the application of new technologies, especially the new genome-editing tool clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated protein 9 (Cas9) systems, to functional characterization of plant ncRNAs. PMID:28698797

Formation of high-order acoustic Bessel beams by spiral diffraction gratings

NASA Astrophysics Data System (ADS)

Jiménez, Noé; Picó, R.; Sánchez-Morcillo, V.; Romero-García, V.; García-Raffi, L. M.; Staliunas, K.

2016-11-01

The formation of high-order Bessel beams by a passive acoustic device consisting of an Archimedes' spiral diffraction grating is theoretically, numerically, and experimentally reported in this paper. These beams are propagation-invariant solutions of the Helmholtz equation and are characterized by an azimuthal variation of the phase along its annular spectrum producing an acoustic vortex in the near field. In our system, the scattering of plane acoustic waves by the spiral grating leads to the formation of the acoustic vortex with zero pressure on axis and the angular phase dislocations characterized by the spiral geometry. The order of the generated Bessel beam and, as a consequence, the size of the generated vortex can be fixed by the number of arms in the spiral diffraction grating. The obtained results allow for obtaining Bessel beams with controllable vorticity by a passive device, which has potential applications in low-cost acoustic tweezers and acoustic radiation force devices.

Low spatial frequency characterization of holographic recording materials applied to correlation

NASA Astrophysics Data System (ADS)

Márquez, A.; Neipp, C.; Beléndez, A.; Campos, J.; Pascual, I.; Yzuel, M. J.; Fimia, A.

2003-09-01

Accurate recording of computer-generated holograms (CGH) on a phase material is not a trivial task. The range of available phase materials is large, and their suitability depends on the fabrication technique chosen to produce the hologram. We are particularly interested in low-cost fabrication techniques, easily available for any lab. In this work we present the results obtained with a wide variety of phase holographic recording materials, characterized at low spatial frequencies (leq32 lp mm-1) which is the range associated with the technique we use to produce the CGHs. We have considered bleached emulsion, silver halide sensitized gelatin (SHSG) and dichromated gelatin. Some interesting differences arise between the behaviour of these materials in the usual holographic range (>1000 lp mm-1), and the low-frequency range intended for digital holography. The ultimate goal of this paper is to establish the suitability of different phase materials as the media to generate correlation filters for optical pattern recognition. In all the materials considered, the phase filters generated ensure the discrimination of the target in the recognition process. Taking into account all the experimental results, we can say that SHSG is the best material to generate phase CGHs with low spatial frequencies.

Dynamic characterization and modeling of potting materials for electronics assemblies

NASA Astrophysics Data System (ADS)

Joshi, Vasant S.; Lee, Gilbert F.; Santiago, Jaime R.

2017-01-01

Prediction of survivability of encapsulated electronic components subject to impact relies on accurate modeling, which in turn needs both static and dynamic characterization of individual electronic components and encapsulation material to generate reliable material parameters for a robust material model. Current focus is on potting materials to mitigate high rate loading on impact. In this effort, difficulty arises in capturing one of the critical features characteristic of the loading environment in a high velocity impact: multiple loading events coupled with multi-axial stress states. Hence, potting materials need to be characterized well to understand its damping capacity at different frequencies and strain rates. An encapsulation scheme to protect electronic boards consists of multiple layers of filled as well as unfilled polymeric materials like Sylgard 184 and Trigger bond Epoxy # 20-3001. A combination of experiments conducted for characterization of materials used Split Hopkinson Pressure Bar (SHPB), and dynamic material analyzer (DMA). For material which behaves in an ideal manner, a master curve can be fitted to Williams-Landel-Ferry (WLF) model. To verify the applicability of WLF model, a new temperature-time shift (TTS) macro was written to compare idealized temperature shift factor with experimental incremental shift factor. Deviations can be readily observed by comparison of experimental data with the model fit to determine if model parameters reflect the actual material behavior. Similarly, another macro written for obtaining Ogden model parameter from Hopkinson Bar tests can readily indicate deviations from experimental high strain rate data. Experimental results for different materials used for mitigating impact, and ways to combine data from DMA and Hopkinson bar together with modeling refinements are presented.

A theoretical and experimental study of neuromorphic atomic switch networks for reservoir computing.

PubMed

Sillin, Henry O; Aguilera, Renato; Shieh, Hsien-Hang; Avizienis, Audrius V; Aono, Masakazu; Stieg, Adam Z; Gimzewski, James K

2013-09-27

Atomic switch networks (ASNs) have been shown to generate network level dynamics that resemble those observed in biological neural networks. To facilitate understanding and control of these behaviors, we developed a numerical model based on the synapse-like properties of individual atomic switches and the random nature of the network wiring. We validated the model against various experimental results highlighting the possibility to functionalize the network plasticity and the differences between an atomic switch in isolation and its behaviors in a network. The effects of changing connectivity density on the nonlinear dynamics were examined as characterized by higher harmonic generation in response to AC inputs. To demonstrate their utility for computation, we subjected the simulated network to training within the framework of reservoir computing and showed initial evidence of the ASN acting as a reservoir which may be optimized for specific tasks by adjusting the input gain. The work presented represents steps in a unified approach to experimentation and theory of complex systems to make ASNs a uniquely scalable platform for neuromorphic computing.

A theoretical and experimental study of neuromorphic atomic switch networks for reservoir computing

NASA Astrophysics Data System (ADS)

Sillin, Henry O.; Aguilera, Renato; Shieh, Hsien-Hang; Avizienis, Audrius V.; Aono, Masakazu; Stieg, Adam Z.; Gimzewski, James K.

2013-09-01

Atomic switch networks (ASNs) have been shown to generate network level dynamics that resemble those observed in biological neural networks. To facilitate understanding and control of these behaviors, we developed a numerical model based on the synapse-like properties of individual atomic switches and the random nature of the network wiring. We validated the model against various experimental results highlighting the possibility to functionalize the network plasticity and the differences between an atomic switch in isolation and its behaviors in a network. The effects of changing connectivity density on the nonlinear dynamics were examined as characterized by higher harmonic generation in response to AC inputs. To demonstrate their utility for computation, we subjected the simulated network to training within the framework of reservoir computing and showed initial evidence of the ASN acting as a reservoir which may be optimized for specific tasks by adjusting the input gain. The work presented represents steps in a unified approach to experimentation and theory of complex systems to make ASNs a uniquely scalable platform for neuromorphic computing.

Generation and characterization of highly strained dibenzotetrakisdehydro[12]- and dibenzopentakisdehydro[14]annulenes.

PubMed

Hisaki, Ichiro; Eda, Takeshi; Sonoda, Motohiro; Niino, Hiroyuki; Sato, Tadatake; Wakabayashi, Tomonari; Tobe, Yoshito

2005-03-04

To generate dibenzotetrakisdehydro[12]- and dibenzopentakisdehydro[14]annulenes ([12]- and [14]DBAs) having a highly deformed triyne moiety, [4.3.2]propellatriene-anneleted dehydro[12]- and dehydro[14]annulenes were prepared as their precursors. UV irradiation of the precursors resulted in the photochemical [2 + 2] cycloreversion to generate the strained [12]- and [14]DBAs, respectively. The [12]DBA was not detected by 1H NMR spectroscopy, but it was intercepted as Diels-Alder adducts in solution, suggesting its intermediacy. Its spectroscopic characterization was successfully carried out by UV-vis spectroscopy in a 2-methyltetrahydrofuran (MTHF) glass matrix at 77 K and by FT-IR spectroscopy in an argon matrix at 20 K. On the other hand, the [14]DBA was stable enough for observation by 1H and 13C NMR spectra in solution, though it was not isolated because of the low efficiency of the cycloreversion. The [14]DBA was also characterized by interception as Diels-Alder adducts in solution and by UV-vis spectroscopy in a MTHF glass matrix at 77 K. The kinetic stabilities of the DBAs are compared with the related dehydrobenzoannulenes with respect to the topology of the pi-systems. In addition, the tropicity of the [14]DBA is discussed based on its experimental and theoretical 1H NMR chemical shifts.

Characterizing Microbe-Environment Interactions Through Experimental Evolution: The Autonomous Adaptive Directed Evolution Chamber

NASA Astrophysics Data System (ADS)

Ibanez, C. R.; Blaich, J.; Owyang, S.; Storrs, A.; Moffet, A.; Wong, N.; Zhou, J.; Gentry, D.

2015-12-01

We are developing a laboratory system for studying micro- to meso-scale interactions between microorganisms and their physicochemical environments. The Autonomous Adaptive Directed Evolution Chamber (AADEC) cultures microorganisms in controlled,small-scale geochemical environments. It observes corresponding microbial interactions to these environments and has the ability to adjust thermal, chemical, and other parameters in real time in response to these interactions. In addition to the sensed data, the system allows the generation of time-resolved ecological, genomic, etc. samples on the order of microbial generations. The AADEC currently houses cultures in liquid media and controls UVC radiation, heat exposure, and nutrient supply. In a proof-of-concept experimental evolution application, it can increase UVC radiation resistance of Escherichia coli cultures by iteratively exposing them to UVC and allowing the surviving cells to regrow. A baseline characterization generated a million fold resistance increase. This demonstration uses a single-well growth chamber prototype, but it was limited by scalability. We have expanded upon this system by implementing a microwell plate compatible fluidics system and sensor housing. This microwell plate system increases the diversity of microbial interactions seen in response to the geochemical environments generated by the system, allowing greater control over individual cultures' environments and detection of rarer events. The custom microfluidic card matches the footprint of a standard microwell plate. This card enables controllable fluid flow between wells and introduces multiple separate exposure and sensor chambers, increasing the variety of sensors compatible with the system. This gives the device control over scale and the interconnectedness of environments within the system. The increased controllability of the multiwell system provides a platform for implementing machine learning algorithms that will autonomously adjust geochemical environmental parameters.

Ultrashort polarization-tailored bichromatic fields from a CEP-stable white light supercontinuum.

PubMed

Kerbstadt, Stefanie; Timmer, Daniel; Englert, Lars; Bayer, Tim; Wollenhaupt, Matthias

2017-05-29

We apply ultrafast polarization shaping to an ultrabroadband carrier envelope phase (CEP) stable white light supercontinuum to generate polarization-tailored bichromatic laser fields of low-order frequency ratio. The generation of orthogonal linearly and counter-rotating circularly polarized bichromatic fields is achieved by introducing a composite polarizer in the Fourier plane of a 4 f polarization shaper. The resulting Lissajous- and propeller-type polarization profiles are characterized experimentally by cross-correlation trajectories. The scheme provides full control over all bichromatic parameters and allows for individual spectral phase modulation of both colors. Shaper-based CEP control and the generation of tailored bichromatic fields is demonstrated. These bichromatic CEP-stable polarization-shaped ultrashort laser pulses provide a versatile class of waveforms for coherent control experiments.

Effects of Passive Fuel-Air Mixing Control on Burner Emissions Via Lobed Fuel Injectors

NASA Technical Reports Server (NTRS)

Mitchell, M. G.; Smith, O. I.; Karagozian, A. R.

1999-01-01

The present experimental study examines the effects of differing levels of passive fuel-air premixing on flame structures and their associated NO(x) and CO emissions. Four alternative fuel injector geometries were explored, three of which have lobed shapes. These lobed injectors mix fuel and air and strain species inter-faces to differing extents due to streamwise vorticity generation, thus creating different local or core equivalence ratios within flow regions upstream of flame ignition and stabilization. Prior experimental studies of two of these lobed injector flowfields focused on non-reactive mixing characteristics and emissions measurements for the case where air speeds were matched above and below the fuel injector, effectively generating stronger streamwise vorticity than spanwise vorticity. The present studies examine the effects of airstream mismatch (and hence additional spanwise vorticity generation), effects of confinement of the crossflow to reduce the local equivalence ratio, and the effects of altering the geometry and position of the flameholders. NO(x) and CO emissions as well as planar laser-induced fluorescence imaging (PLIF) of seeded acetone are used to characterize injector performance and reactive flow evolution.

Control and characterization of a bistable laminate generated with piezoelectricity

NASA Astrophysics Data System (ADS)

Lee, Andrew J.; Moosavian, Amin; Inman, Daniel J.

2017-08-01

Extensive research has been conducted on utilizing smart materials such as piezoelectric and shape memory alloy actuators to induce snap through of bistable structures for morphing applications. However, there has only been limited success in initiating snap through from both stable states due to the lack of actuation authority. A novel solution in the form of a piezoelectrically generated bistable laminate consisting of only macro fiber composites (MFC), allowing complete configuration control without any external assistance, is explored in detail here. Specifically, this paper presents the full analytical, computational, and experimental results of the laminate’s design, geometry, bifurcation behavior, and snap through capability. By bonding two actuated MFCs in a [0MFC/90MFC]T layup and releasing the voltage post cure, piezoelectric strain anisotropy and the resulting in-plane residual stresses yield two statically stable states that are cylindrically shaped. The analytical model uses the Rayleigh-Ritz minimization of total potential energy and finite element analysis is implemented in MSC Nastran. The [0MFC/90MFC]T laminate is then manufactured and experimentally characterized for model validation. This paper demonstrates the adaptive laminate’s unassisted forward and reverse snap through capability enabled by the efficiencies gained from simultaneously being the actuator and the primary structure.

S-Duct Engine Inlet Flow Control Using SDBD Plasma Streamwise Vortex Generators

NASA Astrophysics Data System (ADS)

Kelley, Christopher; He, Chuan; Corke, Thomas

2009-11-01

The results of a numerical simulation and experiment characterizing the performance of plasma streamwise vortex generators in controlling separation and secondary flow within a serpentine, diffusing duct are presented. A no flow control case is first run to check agreement of location of separation, development of secondary flow, and total pressure recovery between the experiment and numerical results. Upon validation, passive vane-type vortex generators and plasma streamwise vortex generators are implemented to increase total pressure recovery and reduce flow distortion at the aerodynamic interface plane: the exit of the S-duct. Total pressure recovery is found experimentally with a pitot probe rake assembly at the aerodynamic interface plane. Stagnation pressure distortion descriptors are also presented to show the performance increase with plasma streamwise vortex generators in comparison to the baseline no flow control case. These performance parameters show that streamwise plasma vortex generators are an effective alternative to vane-type vortex generators in total pressure recovery and total pressure distortion reduction in S-duct inlets.

Investigation of the fundamentals of low-energy nanosecond pulse ignition: Final CRADA Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallner, Thomas; Scarcelli, Riccardo; Zhang, Anqi

A detailed investigation of the fundamentals of low-energy nanosecond pulse ignition was performed with the objective to overcome the barrier presented by limited knowledge and characterization of nonequilibrium plasma ignition for realistic internal combustion engine applications (be it in the automotive or power generation field) and shed light on the mechanisms which improve the performance of the advanced TPS ignition system compared to conventional state-of-the-art hardware. Three main tasks of the research included experimental evaluation on a single-cylinder automotive gasoline engine, experimental evaluation on a single-cylinder stationary natural gas engine and energy quantification using x-ray diagnostics.

Technical, analytical and computer support

NASA Technical Reports Server (NTRS)

1972-01-01

The development of a rigorous mathematical model for the design and performance analysis of cylindrical silicon-germanium thermoelectric generators is reported that consists of two parts, a steady-state (static) and a transient (dynamic) part. The material study task involves the definition and implementation of a material study that aims to experimentally characterize the long term behavior of the thermoelectric properties of silicon-germanium alloys as a function of temperature. Analytical and experimental efforts are aimed at the determination of the sublimation characteristics of silicon germanium alloys and the study of sublimation effects on RTG performance. Studies are also performed on a variety of specific topics on thermoelectric energy conversion.

Through-the-wall high-resolution imaging of a human and experimental characterization of the transmission of wall materials

NASA Astrophysics Data System (ADS)

Nilsson, S.; Jänis, A.; Gustafsson, M.; Kjellgren, J.; Sume, Ain

2008-10-01

This paper describes the research efforts made at the Swedish Defence Research Agency (FOI) concerning through-the-wall imaging radar, as well as fundamental characterization of various wall materials. These activities are a part of two FOI-projects concerning security sensors in the aspects of Military Operations in Urban Terrain (MOUT) and Homeland Defence. Through-the-wall high resolution imaging of a human between 28-40 GHz has been performed at FOI. The UWB radar that was used is normally a member of the instrumentation of the FOI outdoor RCS test range Lilla Gåra. The armed test person was standing behind different kinds of walls. The radar images were generated by stepping the turntable in azimuth and elevation. The angular resolution in the near-field was improved by refocusing the parabolic antennas, which in combination with the large bandwidth (12 GHz) gave extremely high resolution radar images. A 3D visualization of the person even exposed the handgun tucked into one hip pocket. A qualitative comparison between the experimental results and simulation results (physical optics-based method) will also be presented. The second part of this paper describes results from activities at FOI concerning material characterization in the 2-110 GHz region. The transmission of building, packing and clothing materials has been experimentally determined. The wide-band measurements in free space were carried out with a scalar network analyzer. In this paper results from these characterizations will be presented. Furthermore, an experimental investigation will be reported of how the transmission properties for some moisted materials change as a function of water content and frequency. We will also show experimental results of how the transmission properties of a pine panel are affected when the surface is coated with a thin surface layer of water.

Generation of arbitrary order Bessel beams via 3D printed axicons at the terahertz frequency range.

PubMed

Wei, Xuli; Liu, Changming; Niu, Liting; Zhang, Zhongqi; Wang, Kejia; Yang, Zhengang; Liu, Jinsong

2015-12-20

We present the generation of arbitrary order Bessel beams at 0.3 THz through the implementation of suitably designed axicons based on 3D printing technology. The helical axicons, which possess thickness gradients in both radial and azimuthal directions, can convert the incident Gaussian beam into a high-order Bessel beam with spiral phase structure. The evolution of the generated Bessel beams are characterized experimentally with a three-dimensional field scanner. Moreover, the topological charges carried by the high-order Bessel beams are determined by the fork-like interferograms. This 3D-printing-based Bessel beam generation technique is useful not only for THz imaging systems with zero-order Bessel beams but also for future orbital-angular-momentum-based THz free-space communication with higher-order Bessel beams.

Design and Test of a 65nm CMOS Front-End with Zero Dead Time for Next Generation Pixel Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaioni, L.; Braga, D.; Christian, D.

This work is concerned with the experimental characterization of a synchronous analog processor with zero dead time developed in a 65 nm CMOS technology, conceived for pixel detectors at the HL-LHC experiment upgrades. It includes a low noise, fast charge sensitive amplifier with detector leakage compensation circuit, and a compact, single ended comparator able to correctly process hits belonging to two consecutive bunch crossing periods. A 2-bit Flash ADC is exploited for digital conversion immediately after the preamplifier. A description of the circuits integrated in the front-end processor and the initial characterization results are provided

Nonlinearity characterization of temperature sensing systems for integrated circuit testing by intermodulation products monitoring.

PubMed

Altet, J; Mateo, D; Perpiñà, X; Grauby, S; Dilhaire, S; Jordà, X

2011-09-01

This work presents an alternative characterization strategy to quantify the nonlinear behavior of temperature sensing systems. The proposed approach relies on measuring the temperature under thermal sinusoidal steady state and observing the intermodulation products that are generated within the sensing system itself due to its nonlinear temperature-output voltage characteristics. From such intermodulation products, second-order interception points can be calculated as a figure of merit of the measuring system nonlinear behavior. In this scenario, the present work first shows a theoretical analysis. Second, it reports the experimental results obtained with three thermal sensing techniques used in integrated circuits. © 2011 American Institute of Physics

Research pressure instrumentation for NASA Space Shuttle main engine, modification no. 5

NASA Technical Reports Server (NTRS)

Anderson, P. J.; Nussbaum, P.; Gustafson, G.

1984-01-01

The objective of the research project described is to define and demonstrate methods to advance the state of the art of pressure sensors for the space shuttle main engine (SSME). Silicon piezoresistive technology was utilized in completing tasks: generation and testing of three transducer design concepts for solid state applications; silicon resistor characterization at cryogenic temperatures; experimental chip mounting characterization; frequency response optimization and prototype design and fabrication. Excellent silicon sensor performance was demonstrated at liquid nitrogen temperature. A silicon resistor ion implant dose was customized for SSME temperature requirements. A basic acoustic modeling software program was developed as a design tool to evaluate frequency response characteristics.

The Mechanical Properties of Nanowires

PubMed Central

Wang, Shiliang; Shan, Zhiwei

2017-01-01

Applications of nanowires into future generation nanodevices require a complete understanding of the mechanical properties of the nanowires. A great research effort has been made in the past two decades to understand the deformation physics and mechanical behaviors of nanowires, and to interpret the discrepancies between experimental measurements and theoretical predictions. This review focused on the characterization and understanding of the mechanical properties of nanowires, including elasticity, plasticity, anelasticity and strength. As the results from the previous literature in this area appear inconsistent, a critical evaluation of the characterization techniques and methodologies were presented. In particular, the size effects of nanowires on the mechanical properties and their deformation mechanisms were discussed. PMID:28435775

Faraday Waves-Based Integrated Ultrasonic Micro-Droplet Generator and Applications

PubMed Central

Tsai, Chen S.; Mao, Rong W.; Tsai, Shirley C.; Shahverdi, Kaveh; Zhu, Yun; Lin, Shih K.; Hsu, Yu-Hsiang; Boss, Gerry; Brenner, Matt; Mahon, Sari; Smaldone, Gerald C.

2017-01-01

An in-depth review on a new ultrasonic micro-droplet generator which utilizes megahertz (MHz) Faraday waves excited by silicon-based multiple Fourier horn ultrasonic nozzles (MFHUNs) and its potential applications is presented. The new droplet generator has demonstrated capability for producing micro droplets of controllable size and size distribution and desirable throughput at very low electrical drive power. For comparison, the serious deficiencies of current commercial droplet generators (nebulizers) and the other ultrasonic droplet generators explored in recent years are first discussed. The architecture, working principle, simulation, and design of the multiple Fourier horns (MFH) in resonance aimed at the amplified longitudinal vibration amplitude on the end face of nozzle tip, and the fabrication and characterization of the nozzles are then described in detail. Subsequently, a linear theory on the temporal instability of Faraday waves on a liquid layer resting on the planar end face of the MFHUN and the detailed experimental verifications are presented. The linear theory serves to elucidate the dynamics of droplet ejection from the free liquid surface and predict the vibration amplitude onset threshold for droplet ejection and the droplet diameters. A battery-run pocket-size clogging-free integrated micro droplet generator realized using the MFHUN is then described. The subsequent report on the successful nebulization of a variety of commercial pulmonary medicines against common diseases and on the experimental antidote solutions to cyanide poisoning using the new droplet generator serves to support its imminent application to inhalation drug delivery. PMID:29250438

Faraday Waves-Based Integrated Ultrasonic Micro-Droplet Generator and Applications.

PubMed

Tsai, Chen S; Mao, Rong W; Tsai, Shirley C; Shahverdi, Kaveh; Zhu, Yun; Lin, Shih K; Hsu, Yu-Hsiang; Boss, Gerry; Brenner, Matt; Mahon, Sari; Smaldone, Gerald C

2017-01-01

An in-depth review on a new ultrasonic micro-droplet generator which utilizes megahertz (MHz) Faraday waves excited by silicon-based multiple Fourier horn ultrasonic nozzles (MFHUNs) and its potential applications is presented. The new droplet generator has demonstrated capability for producing micro droplets of controllable size and size distribution and desirable throughput at very low electrical drive power. For comparison, the serious deficiencies of current commercial droplet generators (nebulizers) and the other ultrasonic droplet generators explored in recent years are first discussed. The architecture, working principle, simulation, and design of the multiple Fourier horns (MFH) in resonance aimed at the amplified longitudinal vibration amplitude on the end face of nozzle tip, and the fabrication and characterization of the nozzles are then described in detail. Subsequently, a linear theory on the temporal instability of Faraday waves on a liquid layer resting on the planar end face of the MFHUN and the detailed experimental verifications are presented. The linear theory serves to elucidate the dynamics of droplet ejection from the free liquid surface and predict the vibration amplitude onset threshold for droplet ejection and the droplet diameters. A battery-run pocket-size clogging-free integrated micro droplet generator realized using the MFHUN is then described. The subsequent report on the successful nebulization of a variety of commercial pulmonary medicines against common diseases and on the experimental antidote solutions to cyanide poisoning using the new droplet generator serves to support its imminent application to inhalation drug delivery.

Statistical behavior of ten million experimental detection limits

NASA Astrophysics Data System (ADS)

Voigtman, Edward; Abraham, Kevin T.

2011-02-01

Using a lab-constructed laser-excited fluorimeter, together with bootstrapping methodology, the authors have generated many millions of experimental linear calibration curves for the detection of rhodamine 6G tetrafluoroborate in ethanol solutions. The detection limits computed from them are in excellent agreement with both previously published theory and with comprehensive Monte Carlo computer simulations. Currie decision levels and Currie detection limits, each in the theoretical, chemical content domain, were found to be simply scaled reciprocals of the non-centrality parameter of the non-central t distribution that characterizes univariate linear calibration curves that have homoscedastic, additive Gaussian white noise. Accurate and precise estimates of the theoretical, content domain Currie detection limit for the experimental system, with 5% (each) probabilities of false positives and false negatives, are presented.

Mitochondrial protection by low doses of insulin-like growth factor- I in experimental cirrhosis.

PubMed

Pérez, Raquel; García-Fernández, María; Díaz-Sánchez, Matías; Puche, Juan E; Delgado, Gloria; Conchillo, Marian; Muntané, Jordi; Castilla-Cortázar, Inma

2008-05-07

To characterize the mitochondrial dysfunction in experimental cirrhosis and to study whether insulin-like growth factor-I (IGF- I) therapy (4 wk) is able to induce beneficial effects on damaged mitochondria leading to cellular protection. Wistar rats were divided into three groups: Control group, untreated cirrhotic rats and cirrhotic rats treated with IGF- I treatment (2 microg/100 g bw/d). Mitochondrial function was analyzed by flow cytometry in isolated hepatic mitochondria, caspase 3 activation was assessed by Western blot and apoptosis by TUNEL in the three experimental groups. Untreated cirrhotic rats showed a mitochondrial dysfunction characterized by a significant reduction of mitochondrial membrane potential (in status 4 and 3); an increase of intramitochondrial reactive oxigen species (ROS) generation and a significant reduction of ATPase activity. IGF- I therapy normalized mitochondrial function by increasing the membrane potential and ATPase activity and reducing the intramitochondrial free radical production. Activity of the electron transport complexes I and III was increased in both cirrhotic groups. In addition, untreated cirrhotic rats showed an increase of caspase 3 activation and apoptosis. IGF- I therapy reduced the expression of the active peptide of caspase 3 and resulted in reduced apoptosis. These results show that IGF- I exerts a mitochondrial protection in experimental cirrhosis leading to reduced apoptosis and increased ATP production.

Mitochondrial protection by low doses of insulin-like growth factor-Iin experimental cirrhosis

PubMed Central

Pérez, Raquel; García-Fernández, María; Díaz-Sánchez, Matías; Puche, Juan E; Delgado, Gloria; Conchillo, Marian; Muntané, Jordi; Castilla-Cortázar, Inma

2008-01-01

AIM: To characterize the mitochondrial dysfunction in experimental cirrhosis and to study whether insulin-like growth factor-I(IGF-I) therapy (4 wk) is able to induce beneficial effects on damaged mitochondria leading to cellular protection. METHODS: Wistar rats were divided into three groups: Control group, untreated cirrhotic rats and cirrhotic rats treated with IGF-Itreatment (2 μg/100 g bw/d). Mitochondrial function was analyzed by flow cytometry in isolated hepatic mitochondria, caspase 3 activation was assessed by Western blot and apoptosis by TUNEL in the three experimental groups. RESULTS: Untreated cirrhotic rats showed a mitochondrial dysfunction characterized by a significant reduction of mitochondrial membrane potential (in status 4 and 3); an increase of intramitochondrial reactive oxigen species (ROS) generation and a significant reduction of ATPase activity. IGF-Itherapy normalized mitochondrial function by increasing the membrane potential and ATPase activity and reducing the intramitochondrial free radical production. Activity of the electron transport complexes Iand III was increased in both cirrhotic groups. In addition, untreated cirrhotic rats showed an increase of caspase 3 activation and apoptosis. IGF-Itherapy reduced the expression of the active peptide of caspase 3 and resulted in reduced apoptosis. CONCLUSION: These results show that IGF-Iexerts a mitochondrial protection in experimental cirrhosis leading to reduced apoptosis and increased ATP production. PMID:18461658

Tempest: Tools for Addressing the Needs of Next-Generation Climate Models

NASA Astrophysics Data System (ADS)

Ullrich, P. A.; Guerra, J. E.; Pinheiro, M. C.; Fong, J.

2015-12-01

Tempest is a comprehensive simulation-to-science infrastructure that tackles the needs of next-generation, high-resolution, data intensive climate modeling activities. This project incorporates three key components: TempestDynamics, a global modeling framework for experimental numerical methods and high-performance computing; TempestRemap, a toolset for arbitrary-order conservative and consistent remapping between unstructured grids; and TempestExtremes, a suite of detection and characterization tools for identifying weather extremes in large climate datasets. In this presentation, the latest advances with the implementation of this framework will be discussed, and a number of projects now utilizing these tools will be featured.

Characterization of Bond Strength of U-Mo Fuel Plates Using the Laser Shockwave Technique: Capabilities and Preliminary Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. A. Smith; D. L. Cottle; B. H. Rabin

2013-09-01

This report summarizes work conducted to-date on the implementation of new laser-based capabilities for characterization of bond strength in nuclear fuel plates, and presents preliminary results obtained from fresh fuel studies on as-fabricated monolithic fuel consisting of uranium-10 wt.% molybdenum alloys clad in 6061 aluminum by hot isostatic pressing. Characterization involves application of two complementary experimental methods, laser-shock testing and laser-ultrasonic imaging, collectively referred to as the Laser Shockwave Technique (LST), that allows the integrity, physical properties and interfacial bond strength in fuel plates to be evaluated. Example characterization results are provided, including measurement of layer thicknesses, elastic properties ofmore » the constituents, and the location and nature of generated debonds (including kissing bonds). LST provides spatially localized, non-contacting measurements with minimum specimen preparation, and is ideally suited for applications involving radioactive materials, including irradiated materials. The theoretical principles and experimental approaches employed in characterizing nuclear fuel plates are described, and preliminary bond strength measurement results are discussed, with emphasis on demonstrating the capabilities and limitations of these methods. These preliminary results demonstrate the ability to distinguish bond strength variations between different fuel plates. Although additional development work is necessary to validate and qualify the test methods, these results suggest LST is viable as a method to meet fuel qualification requirements to demonstrate acceptable bonding integrity.« less

Can the experimental evolution programme help us elucidate the genetic basis of adaptation in nature?

PubMed

Bailey, Susan F; Bataillon, Thomas

2016-01-01

There have been a variety of approaches taken to try to characterize and identify the genetic basis of adaptation in nature, spanning theoretical models, experimental evolution studies and direct tests of natural populations. Theoretical models can provide formalized and detailed hypotheses regarding evolutionary processes and patterns, from which experimental evolution studies can then provide important proofs of concepts and characterize what is biologically reasonable. Genetic and genomic data from natural populations then allow for the identification of the particular factors that have and continue to play an important role in shaping adaptive evolution in the natural world. Further to this, experimental evolution studies allow for tests of theories that may be difficult or impossible to test in natural populations for logistical and methodological reasons and can even generate new insights, suggesting further refinement of existing theories. However, as experimental evolution studies often take place in a very particular set of controlled conditions--that is simple environments, a small range of usually asexual species, relatively short timescales--the question remains as to how applicable these experimental results are to natural populations. In this review, we discuss important insights coming from experimental evolution, focusing on four key topics tied to the evolutionary genetics of adaptation, and within those topics, we discuss the extent to which the experimental work compliments and informs natural population studies. We finish by making suggestions for future work in particular a need for natural population genomic time series data, as well as the necessity for studies that combine both experimental evolution and natural population approaches. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

Near-field non-radial motion generation from underground chemical explosions in jointed granite

DOE PAGES

Vorobiev, Oleg; Ezzedine, Souheil; Hurley, Ryan

2017-09-22

Here, this paper describes analysis of non-radial ground motion generated by chemical explosions in a jointed rock formation during the Source Physics Experiment (SPE). Such motion makes it difficult to discriminate between various subsurface events such as explosions, implosions (i.e. mine collapse) and earthquakes. We apply 3-D numerical simulations to understand experimental data collected during the SPEs. The joints are modelled explicitly as compliant thin inclusions embedded into the rock mass. Mechanical properties of the rock and the joints as well as the joint spacing and orientation are inferred from experimental test data, and geophysical and geological characterization of themore » SPE site which is dominantly Climax Stock granitic outcrop. The role of various factors characterizing the joints such as joint spacing, frictional properties, orientation and persistence in generation of non-radial motion is addressed. The joints in granite at the SPE site are oriented in nearly orthogonal directions with two vertical sets dipping at 70–80 degrees with the same strike angle, one vertical set almost orthogonal to the first two and one shallow angle joint set dipping 15 degrees. In this study we establish the relationship between the joint orientation and azimuthal variations in the polarity of the observed shear motion. The majority of the shear motion is generated due to the effects of non-elastic sliding on the joints near the source, where the wave can create significant shear stress to overcome the cohesive forces at the joints. Near the surface the joints are less confined and are subject to sliding when the pressure waves are reflected. In the far field, where the cohesive forces on the joints cannot be overcome, additional shear motion can be generated due to elastic anisotropy of the rock mass given by preferred spatial orientations of compliant joints.« less

Near-field non-radial motion generation from underground chemical explosions in jointed granite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vorobiev, Oleg; Ezzedine, Souheil; Hurley, Ryan

Here, this paper describes analysis of non-radial ground motion generated by chemical explosions in a jointed rock formation during the Source Physics Experiment (SPE). Such motion makes it difficult to discriminate between various subsurface events such as explosions, implosions (i.e. mine collapse) and earthquakes. We apply 3-D numerical simulations to understand experimental data collected during the SPEs. The joints are modelled explicitly as compliant thin inclusions embedded into the rock mass. Mechanical properties of the rock and the joints as well as the joint spacing and orientation are inferred from experimental test data, and geophysical and geological characterization of themore » SPE site which is dominantly Climax Stock granitic outcrop. The role of various factors characterizing the joints such as joint spacing, frictional properties, orientation and persistence in generation of non-radial motion is addressed. The joints in granite at the SPE site are oriented in nearly orthogonal directions with two vertical sets dipping at 70–80 degrees with the same strike angle, one vertical set almost orthogonal to the first two and one shallow angle joint set dipping 15 degrees. In this study we establish the relationship between the joint orientation and azimuthal variations in the polarity of the observed shear motion. The majority of the shear motion is generated due to the effects of non-elastic sliding on the joints near the source, where the wave can create significant shear stress to overcome the cohesive forces at the joints. Near the surface the joints are less confined and are subject to sliding when the pressure waves are reflected. In the far field, where the cohesive forces on the joints cannot be overcome, additional shear motion can be generated due to elastic anisotropy of the rock mass given by preferred spatial orientations of compliant joints.« less

Quadratic spatial soliton interactions

NASA Astrophysics Data System (ADS)

Jankovic, Ladislav

Quadratic spatial soliton interactions were investigated in this Dissertation. The first part deals with characterizing the principal features of multi-soliton generation and soliton self-reflection. The second deals with two beam processes leading to soliton interactions and collisions. These subjects were investigated both theoretically and experimentally. The experiments were performed by using potassium niobate (KNBO 3) and periodically poled potassium titanyl phosphate (KTP) crystals. These particular crystals were desirable for these experiments because of their large nonlinear coefficients and, more importantly, because the experiments could be performed under non-critical-phase-matching (NCPM) conditions. The single soliton generation measurements, performed on KNBO3 by launching the fundamental component only, showed a broad angular acceptance bandwidth which was important for the soliton collisions performed later. Furthermore, at high input intensities multi-soliton generation was observed for the first time. The influence on the multi-soliton patterns generated of the input intensity and beam symmetry was investigated. The combined experimental and theoretical efforts indicated that spatial and temporal noise on the input laser beam induced multi-soliton patterns. Another research direction pursued was intensity dependent soliton routing by using of a specially engineered quadratically nonlinear interface within a periodically poled KTP sample. This was the first time demonstration of the self-reflection phenomenon in a system with a quadratic nonlinearity. The feature investigated is believed to have a great potential for soliton routing and manipulation by engineered structures. A detailed investigation was conducted on two soliton interaction and collision processes. Birth of an additional soliton resulting from a two soliton collision was observed and characterized for the special case of a non-planar geometry. A small amount of spiraling, up to 30 degrees rotation, was measured in the experiments performed. The parameters relevant for characterizing soliton collision processes were also studied in detail. Measurements were performed for various collision angles (from 0.2 to 4 degrees), phase mismatch, relative phase between the solitons and the distance to the collision point within the sample (which affects soliton formation). Both the individual and combined effects of these collision variables were investigated. Based on the research conducted, several all-optical switching scenarios were proposed.

Experimental colitis models: Insights into the pathogenesis of inflammatory bowel disease and translational issues.

PubMed

Valatas, Vassilis; Bamias, Giorgos; Kolios, George

2015-07-15

Inflammatory bowel diseases, ulcerative colitis and Crohn׳s disease are characterized by chronic relapsing inflammation of the gastrointestinal tract of unknown etiology that seems to be the consequence of a genetically driven dysregulated immune response against various local and environmental triggers through a defective epithelial barrier. During the last decades, a large number of animal experimental models of intestinal inflammation have been generated and provided valuable insights into the mechanisms that either maintain mucosal homeostasis or drive intestinal inflammation. Their study enabled the identification of various treatment targets and the development a large pipeline of new drugs, mostly biologics. Safety and therapeutic efficacy of these agents have been evaluated in a large number of clinical trials but only a minority has reached the clinic so far. Translational successes but mostly translational failures have prompted to re-evaluate results of efficacy and safety generated by pre-clinical testing and to re-examine the way to interpret experimental in vivo data. This review examines the contribution of the most popular experimental colitis models to our understanding of the pathogenesis of human inflammatory bowel diseases and their translational input in drug development and discusses ways to improve translational outcome. Copyright © 2015 Elsevier B.V. All rights reserved.

From single muscle fiber to whole muscle mechanics: a finite element model of a muscle bundle with fast and slow fibers.

PubMed

Marcucci, Lorenzo; Reggiani, Carlo; Natali, Arturo N; Pavan, Piero G

2017-12-01

Muscles exhibit highly complex, multi-scale architecture with thousands of muscle fibers, each with different properties, interacting with each other and surrounding connective structures. Consequently, the results of single-fiber experiments are scarcely linked to the macroscopic or whole muscle behavior. This is especially true for human muscles where it would be important to understand of how skeletal muscles disorders affect patients' life. In this work, we developed a mathematical model to study how fast and slow muscle fibers, well characterized in single-fiber experiments, work and generate together force and displacement in muscle bundles. We characterized the parameters of a Hill-type model, using experimental data on fast and slow single human muscle fibers, and comparing experimental data with numerical simulations obtained from finite element (FE) models of single fibers. Then, we developed a FE model of a bundle of 19 fibers, based on an immunohistochemically stained cross section of human diaphragm and including the corresponding properties of each slow or fast fiber. Simulations of isotonic contractions of the bundle model allowed the generation of its apparent force-velocity relationship. Although close to the average of the force-velocity curves of fast and slow fibers, the bundle curve deviates substantially toward the fast fibers at low loads. We believe that the present model and the characterization of the force-velocity curve of a fiber bundle represents the starting point to link the single-fiber properties to those of whole muscle with FE application in phenomenological models of human muscles.

Polynomial law for controlling the generation of n-scroll chaotic attractors in an optoelectronic delayed oscillator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Márquez, Bicky A., E-mail: bmarquez@ivic.gob.ve; Suárez-Vargas, José J., E-mail: jjsuarez@ivic.gob.ve; Ramírez, Javier A.

2014-09-01

Controlled transitions between a hierarchy of n-scroll attractors are investigated in a nonlinear optoelectronic oscillator. Using the system's feedback strength as a control parameter, it is shown experimentally the transition from Van der Pol-like attractors to 6-scroll, but in general, this scheme can produce an arbitrary number of scrolls. The complexity of every state is characterized by Lyapunov exponents and autocorrelation coefficients.

Fault-tolerant composite Householder reflection

NASA Astrophysics Data System (ADS)

Torosov, Boyan T.; Kyoseva, Elica; Vitanov, Nikolay V.

2015-07-01

We propose a fault-tolerant implementation of the quantum Householder reflection, which is a key operation in various quantum algorithms, quantum-state engineering, generation of arbitrary unitaries, and entanglement characterization. We construct this operation using the modular approach of composite pulses and a relation between the Householder reflection and the quantum phase gate. The proposed implementation is highly insensitive to variations in the experimental parameters, which makes it suitable for high-fidelity quantum information processing.

Modeling and experimental parametric study of a tri-leg compliant orthoplanar spring based multi-mode piezoelectric energy harvester

NASA Astrophysics Data System (ADS)

Dhote, Sharvari; Yang, Zhengbao; Zu, Jean

2018-01-01

This paper presents the modeling and experimental parametric study of a nonlinear multi-frequency broad bandwidth piezoelectric vibration-based energy harvester. The proposed harvester consists of a tri-leg compliant orthoplanar spring (COPS) and multiple masses with piezoelectric plates attached at three different locations. The vibration modes, resonant frequencies, and strain distributions are studied using the finite element analysis. The prototype is manufactured and experimentally investigated to study the effect of single as well as multiple light-weight masses on the bandwidth. The dynamic behavior of the harvester with a mass at the center is modeled numerically and characterized experimentally. The simulation and experimental results are in good agreement. A wide bandwidth with three close nonlinear vibration modes is observed during the experiments when four masses are added to the proposed harvester. The current generator with four masses shows a significant performance improvement with multiple nonlinear peaks under both forward and reverse frequency sweeps.

Kinetic modeling sheds light on the mode of action of recombinant factor VIIa on thrombin generation.

PubMed

Mitrophanov, Alexander Y; Reifman, Jaques

2011-10-01

The therapeutic potential of a hemostatic agent can be assessed by investigating its effects on the quantitative parameters of thrombin generation. For recombinant activated factor VII (rFVIIa)--a promising hemostasis-inducing biologic--experimental studies addressing its effects on thrombin generation yielded disparate results. To elucidate the inherent ability of rFVIIa to modulate thrombin production, it is necessary to identify rFVIIa-induced effects that are compatible with the available biochemical knowledge about thrombin generation mechanisms. The existing body of knowledge about coagulation biochemistry can be rigorously represented by a computational model that incorporates the known reactions and parameter values constituting the biochemical network. We used a thoroughly validated numerical model to generate activated factor VII (FVIIa) titration curves in the cases of normal blood composition, hemophilia A and B blood, blood lacking factor VII, blood lacking tissue factor pathway inhibitor, and diluted blood. We utilized the generated curves to perform systematic fold-change analyses for five quantitative parameters characterizing thrombin accumulation. The largest fold changes induced by increasing FVIIa concentration were observed for clotting time, thrombin peak time, and maximum slope of the thrombin curve. By contrast, thrombin peak height was much less affected by FVIIa titrations, and the area under the thrombin curve stayed practically unchanged. Comparisons with experimental data demonstrated that the computationally derived patterns can be observed in vitro. rFVIIa modulates thrombin generation primarily by accelerating the process, without significantly affecting the total amount of generated thrombin. Copyright © 2011 Elsevier Ltd. All rights reserved.

Pulsed eddy current inspection of broach support plates in steam generators

NASA Astrophysics Data System (ADS)

Mokros, Sarah Gwendolyn

Steam Generators (SGs) are a critical component of nuclear reactors, employing thousands of SG tubes to convert heat generated in the reactor core into useable energy. SG tubes are supported at numerous locations by Broach Support Plates (BSPs) that have trefoil shaped holes, which prevent excessive tube vibrations, while allowing water to easily flow through the support structures. A number of degradation modes occur in SGs, such as SG tube fretting, cracking or denting, requiring periodic inspection. Currently, conventional Eddy Current Testing (ECT) is used to non-destructively assess the condition of SG tubes and components. However, as reactors age, new modes of degradation will likely appear that may be difficult to detect and characterize using conventional ECT, such as wall loss in BSPs and build-up of corrosion products, which typically form as a hard sludge called magnetite. Pulsed Eddy Current (PEC) technologies are an emerging technique that is presented in this work as a method to further advance inspection techniques used in CANDURTM nuclear reactors. A PEC probe was designed to inspect the unique shape of the trefoil shaped hole to detect and characterize wall loss and the presence of magnetite in A516 carbon steel BSPs with trefoil shaped holes from within 15.9 mm (5/8") Alloy-800 SG tubes. PEC was also used to observe how measurements of wall loss were affected by the presence of magnetite. This work presents Finite Element Method (FEM) simulations and experimental results collected to observe these degradation modes. The probe was demonstrated to be capable of detecting far side wall loss as low as 20%, locating and characterizing the relative permeability of magnetite, and of detecting wall loss when magnetite was present. FEM simulations and experimental results were found to be in good agreement, suggesting that additional investigations of the effects of BSP degradation on PEC signal response may also be performed using FEM models.

Development of a high-efficiency motor/generator for flywheel energy storage

NASA Astrophysics Data System (ADS)

Lashley, Christopher; Anand, Dave K.; Kirk, James A.; Zmood, Ronald B.

This study addresses the design changes and extensions necessary to construct and test a working prototype of a motor/generator for a magnetically suspended flywheel energy storage system. The brushless motor controller for the motor was specified and the electronic commutation arrangement designed. The laminations were redesigned and fabricated using laser machining. Flux density measurements were made and the results used to redesign the armature windings. A test rig was designed and built, and the motor/generator was installed and speed tested to 9000 rpm. Experimental methods of obtaining the machine voltage and torque constants Kv and Kt, obtaining the useful air-gap flux density, and characterizing the motor and other system components are described. The measured Kv and Kt were approximately 40 percent greater than predicted by theory and initial experiment.

Generation of radio vortex beams with designable polarization using anisotropic frequency selective surface

NASA Astrophysics Data System (ADS)

Yang, Jin; Zhang, Cheng; Ma, Hui Feng; Zhao, Jie; Dai, Jun Yan; Yuan, Wei; Yang, Liu Xi; Cheng, Qiang; Cui, Tie Jun

2018-05-01

We propose a strategy to convert a linearly polarized wave from a single point source to an orbital angular momentum (OAM) wave by arbitrary polarization via an anisotropic frequency selective surface (FSS) in the microwave frequency. By tailoring the geometries of FSS elements, reflection-phases in x and y polarizations are engineered and encoded independently, which allows us to design the eventual polarization state of the generated OAM vortex beam by elaborately selecting individual coding sequences for each polarization. Two types of FSSs are designed and experimentally characterized to demonstrate the capability of OAM generation with circular and linear polarizations, respectively, showing excellent performance in a wide bandwidth from 14 to 16 GHz. This method provides opportunities for polarization multiplexing in microwave OAM communication systems.

Development of a high-efficiency motor/generator for flywheel energy storage

NASA Technical Reports Server (NTRS)

Lashley, Christopher; Anand, Dave K.; Kirk, James A.; Zmood, Ronald B.

1991-01-01

This study addresses the design changes and extensions necessary to construct and test a working prototype of a motor/generator for a magnetically suspended flywheel energy storage system. The brushless motor controller for the motor was specified and the electronic commutation arrangement designed. The laminations were redesigned and fabricated using laser machining. Flux density measurements were made and the results used to redesign the armature windings. A test rig was designed and built, and the motor/generator was installed and speed tested to 9000 rpm. Experimental methods of obtaining the machine voltage and torque constants Kv and Kt, obtaining the useful air-gap flux density, and characterizing the motor and other system components are described. The measured Kv and Kt were approximately 40 percent greater than predicted by theory and initial experiment.

Characterizing single isolated radiation-damage events from molecular dynamics via virtual diffraction methods

DOE PAGES

Stewart, James A.; Brookman, G.; Price, Patrick Michael; ...

2018-04-25

In this study, the evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage productionmore » and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. Finally, this characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.« less

Characterizing Sorghum Panicles using 3D Point Clouds

NASA Astrophysics Data System (ADS)

Lonesome, M.; Popescu, S. C.; Horne, D. W.; Pugh, N. A.; Rooney, W.

2017-12-01

To address demands of population growth and impacts of global climate change, plant breeders must increase crop yield through genetic improvement. However, plant phenotyping, the characterization of a plant's physical attributes, remains a primary bottleneck in modern crop improvement programs. 3D point clouds generated from terrestrial laser scanning (TLS) and unmanned aerial systems (UAS) based structure from motion (SfM) are a promising data source to increase the efficiency of screening plant material in breeding programs. This study develops and evaluates methods for characterizing sorghum (Sorghum bicolor) panicles (heads) in field plots from both TLS and UAS-based SfM point clouds. The TLS point cloud over experimental sorghum field at Texas A&M farm in Burleston County TX were collected using a FARO Focus X330 3D laser scanner. SfM point cloud was generated from UAS imagery captured using a Phantom 3 Professional UAS at 10m altitude and 85% image overlap. The panicle detection method applies point cloud reflectance, height and point density attributes characteristic of sorghum panicles to detect them and estimate their dimensions (panicle length and width) through image classification and clustering procedures. We compare the derived panicle counts and panicle sizes with field-based and manually digitized measurements in selected plots and study the strengths and limitations of each data source for sorghum panicle characterization.

Characterizing single isolated radiation-damage events from molecular dynamics via virtual diffraction methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stewart, James A.; Brookman, G.; Price, Patrick Michael

In this study, the evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage productionmore » and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. Finally, this characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.« less

Characterizing single isolated radiation-damage events from molecular dynamics via virtual diffraction methods

NASA Astrophysics Data System (ADS)

Stewart, J. A.; Brookman, G.; Price, P.; Franco, M.; Ji, W.; Hattar, K.; Dingreville, R.

2018-04-01

The evolution and characterization of single-isolated-ion-strikes are investigated by combining atomistic simulations with selected-area electron diffraction (SAED) patterns generated from these simulations. Five molecular dynamics simulations are performed for a single 20 keV primary knock-on atom in bulk crystalline Si. The resulting cascade damage is characterized in two complementary ways. First, the individual cascade events are conventionally quantified through the evolution of the number of defects and the atomic (volumetric) strain associated with these defect structures. These results show that (i) the radiation damage produced is consistent with the Norgett, Robinson, and Torrens model of damage production and (ii) there is a net positive volumetric strain associated with the cascade structures. Second, virtual SAED patterns are generated for the resulting cascade-damaged structures along several zone axes. The analysis of the corresponding diffraction patterns shows the SAED spots approximately doubling in size, on average, due to broadening induced by the defect structures. Furthermore, the SAED spots are observed to exhibit an average radial outward shift between 0.33% and 0.87% depending on the zone axis. This characterization approach, as utilized here, is a preliminary investigation in developing methodologies and opportunities to link experimental observations with atomistic simulations to elucidate microstructural damage states.

Application of fiber spectrometers for etch depth measurement of binary computer-generated holograms

NASA Astrophysics Data System (ADS)

Korolkov, V. P.; Konchenko, A. S.; Poleshchuk, A. G.

2013-01-01

Novel spectrophotometric method of computer-generated holograms depth measurement is presented. It is based on spectral properties of binary phase multi-order gratings. An intensity of zero order is a periodical function of illumination light wave number. The grating grooves depth can be calculated as it is inversely proportional to the period. Measurement in reflection allows one to increase a phase depth of the grooves by factor of 2 and measure more precisely shallow phase gratings. Diffraction binary structures with depth from several hundreds to thousands nanometers could be measured by the method. Measurement uncertainty is mainly defined by following parameters - shifts of the spectrum maximums that are occurred due to the tilted grooves sidewalls, uncertainty of light incidence angle measurement, and spectrophotometer wavelength error. It is theoretically and experimentally shown that the method can ensure 0.25-1% error for desktop spectrophotometers. However fiber spectrometers are more convenient for creation of real measurement system with scanning measurement of large area computer-generated holograms which are used for optical testing of aspheric optics. Especially diffractive Fizeau null lenses need to be carefully tested for uniformity of etch depth. Experimental system for characterization of binary computer-generated holograms was developed using spectrophotometric unit of confocal sensor CHR-150 (STIL SA).

Functional identification of spike-processing neural circuits.

PubMed

Lazar, Aurel A; Slutskiy, Yevgeniy B

2014-02-01

We introduce a novel approach for a complete functional identification of biophysical spike-processing neural circuits. The circuits considered accept multidimensional spike trains as their input and comprise a multitude of temporal receptive fields and conductance-based models of action potential generation. Each temporal receptive field describes the spatiotemporal contribution of all synapses between any two neurons and incorporates the (passive) processing carried out by the dendritic tree. The aggregate dendritic current produced by a multitude of temporal receptive fields is encoded into a sequence of action potentials by a spike generator modeled as a nonlinear dynamical system. Our approach builds on the observation that during any experiment, an entire neural circuit, including its receptive fields and biophysical spike generators, is projected onto the space of stimuli used to identify the circuit. Employing the reproducing kernel Hilbert space (RKHS) of trigonometric polynomials to describe input stimuli, we quantitatively describe the relationship between underlying circuit parameters and their projections. We also derive experimental conditions under which these projections converge to the true parameters. In doing so, we achieve the mathematical tractability needed to characterize the biophysical spike generator and identify the multitude of receptive fields. The algorithms obviate the need to repeat experiments in order to compute the neurons' rate of response, rendering our methodology of interest to both experimental and theoretical neuroscientists.

Calculations to support JET neutron yield calibration: Modelling of neutron emission from a compact DT neutron generator

NASA Astrophysics Data System (ADS)

Čufar, Aljaž; Batistoni, Paola; Conroy, Sean; Ghani, Zamir; Lengar, Igor; Milocco, Alberto; Packer, Lee; Pillon, Mario; Popovichev, Sergey; Snoj, Luka; JET Contributors

2017-03-01

At the Joint European Torus (JET) the ex-vessel fission chambers and in-vessel activation detectors are used as the neutron production rate and neutron yield monitors respectively. In order to ensure that these detectors produce accurate measurements they need to be experimentally calibrated. A new calibration of neutron detectors to 14 MeV neutrons, resulting from deuterium-tritium (DT) plasmas, is planned at JET using a compact accelerator based neutron generator (NG) in which a D/T beam impinges on a solid target containing T/D, producing neutrons by DT fusion reactions. This paper presents the analysis that was performed to model the neutron source characteristics in terms of energy spectrum, angle-energy distribution and the effect of the neutron generator geometry. Different codes capable of simulating the accelerator based DT neutron sources are compared and sensitivities to uncertainties in the generator's internal structure analysed. The analysis was performed to support preparation to the experimental measurements performed to characterize the NG as a calibration source. Further extensive neutronics analyses, performed with this model of the NG, will be needed to support the neutron calibration experiments and take into account various differences between the calibration experiment and experiments using the plasma as a source of neutrons.

Experimental Testing of a Van De Graaff Generator as an Electromagnetic Pulse Generator

DTIC Science & Technology

2016-07-01

EXPERIMENTAL TESTING OF A VAN DE GRAAFF GENERATOR AS AN ELECTROMAGNETIC PULSE GENERATOR THESIS...protection in the United States AFIT-ENP-MS-16-S-075 EXPERIMENTAL TESTING OF A VAN DE GRAAFF GENERATOR AS AN ELECTROMAGNETIC PULSE GENERATOR...RELEASE; DISTRIBUTION UNLIMITED. AFIT-ENP-MS-16-S-075 EXPERIMENTAL TESTING OF A VAN DE GRAAFF GENERATOR AS AN ELECTROMAGNETIC PULSE GENERATOR

Hollow Gaussian beam generation through nonlinear interaction of photons with orbital angular momentum

PubMed Central

Chaitanya, N. Apurv; Jabir, M. V.; Banerji, J.; Samanta, G. K.

2016-01-01

Hollow Gaussian beams (HGB) are a special class of doughnut shaped beams that do not carry orbital angular momentum (OAM). Such beams have a wide range of applications in many fields including atomic optics, bio-photonics, atmospheric science, and plasma physics. Till date, these beams have been generated using linear optical elements. Here, we show a new way of generating HGBs by three-wave mixing in a nonlinear crystal. Based on nonlinear interaction of photons having OAM and conservation of OAM in nonlinear processes, we experimentally generated ultrafast HGBs of order as high as 6 and power >180 mW at 355 nm. This generic concept can be extended to any wavelength, timescales (continuous-wave and ultrafast) and any orders. We show that the removal of azimuthal phase of vortices does not produce Gaussian beam. We also propose a new and only method to characterize the order of the HGBs. PMID:27581625

Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

NASA Astrophysics Data System (ADS)

Montanini, Roberto; Quattrocchi, Antonino

2016-06-01

A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d31 mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequency highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.

Experimental characterization of cantilever-type piezoelectric generator operating at resonance for vibration energy harvesting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montanini, Roberto, E-mail: rmontanini@unime.it; Quattrocchi, Antonino, E-mail: aquattrocchi@unime.it

A cantilever-type resonant piezoelectric generator (RPG) has been designed by gluing a PZT patch working in d{sub 31} mode onto a glass fibre reinforced composite cantilever beam with a discrete mass applied on its free end. The electrical and dynamic behaviour of the RPG prototype has been investigated by carrying out laboratory tests aimed to assess the effect of definite design parameters, specifically the electric resistance load and the excitation frequency. Results showed that an optimum resistance load exists, at which power generation is maximized. Moreover, it has been showed that power generation is strongly influenced by the vibration frequencymore » highlighting that, at resonance, output power can be increased by more than one order of magnitude. Possible applications include inertial resonant harvester for energy recovery from vibrating machines, sea waves or wind flux and self-powering of wireless sensor nodes.« less

Microfluidic diffusion diluter: bulging of PDMS microchannels under pressure-driven flow

NASA Astrophysics Data System (ADS)

Holden, Matthew A.; Kumar, Saurabh; Beskok, Ali; Cremer, Paul S.

2003-05-01

The bulging of microfluidic systems during pressure-driven flow is potentially a major consideration for polydimethylsiloxane (PDMS)-based devices. Microchannel cross-sectional areas can change drastically as a function of flow rate and downstream microchannel position. Such geometrical flexibility leads to difficulties in predicting convective/diffusive transport for these systems. We have previously introduced a non-dimensional parameter, kappa, for characterizing convection and diffusion behavior for pressure-driven flow in rigid all-glass systems. This paper describes a modification of that concept for application to non-rigid systems, which is accomplished by incorporating an experimental step to account for the bulging in PDMS/glass microsystems. Specifically, an experimental measurement of channel height by fluorescence microscopy is combined with the aforementioned theory to characterize convective/diffusive behavior at a single location in the device. This allowed the parameter kappa to be determined at that point and applied to predict fluid flow in the subsequent portion of the PDMS microsystem. This procedure was applied to a PDMS/glass microfluidic diffusion dilution (muDD) device designed for generating concentration gradients. Theoretically predicted and experimentally measured distributions of concentrations within the microsystem matched well.

Conception d'un système de mesure automatisé pour la caractérisation expérimentale des moteurs piézo-électriquesAn automated test system for piezoelectric motors

NASA Astrophysics Data System (ADS)

Ferreira, A.

1996-04-01

This paper describes an automated test system for piezoelectric motors allowing the experimental characterization of its electromechanical behaviour. In the first part, an experimental method is given for evaluation of losses generated in the different mechanisms of conversion: electric energy into ultrasonic vibrating energy and ultrasonic vibrating energy into mechanical energy of revolving motion. In the second part, the present method is experimentally validated on a travelling-wave-type rotary motor (Shinsei USR-60). The free stator vibration is analysed by a laser vibrometer which gives a picture both of amplitude and of phase vibration. This result allows one to obtain an identification of vibrations modes and an evaluation of ultrasonic vibrating energy and electromechanical efficiency. To characterize the working of the complete motor, the no-load working mode is first considered. The measurement of its maximal mechanical characteristics (maximal no-load rotating speed, maximal driving torque) with respect to axial load allows the choice of optimum axial load. For this optimum value, the load working mode is, finally, investigated for the evaluation of load characteristics and conversion losses.

Local versus field scale soil heterogeneity characterization - a challenge for representative sampling in pollution studies

NASA Astrophysics Data System (ADS)

Kardanpour, Z.; Jacobsen, O. S.; Esbensen, K. H.

2015-06-01

This study is a contribution to development of a heterogeneity characterisation facility for "next generation" sampling aimed at more realistic and controllable pesticide variability in laboratory pots in experimental environmental contaminant assessment. The role of soil heterogeneity on quantification of a set of exemplar parameters, organic matter, loss on ignition (LOI), biomass, soil microbiology, MCPA sorption and mineralization is described, including a brief background on how heterogeneity affects sampling/monitoring procedures in environmental pollutant studies. The Theory of Sampling (TOS) and variographic analysis has been applied to develop a fit-for-purpose heterogeneity characterization approach. All parameters were assessed in large-scale profile (1-100 m) vs. small-scale (0.1-1 m) replication sampling pattern. Variographic profiles of experimental analytical results concludes that it is essential to sample at locations with less than a 2.5 m distance interval to benefit from spatial auto-correlation and thereby avoid unnecessary, inflated compositional variation in experimental pots; this range is an inherent characteristic of the soil heterogeneity and will differ among soils types. This study has a significant carrying-over potential for related research areas e.g. soil science, contamination studies, and environmental monitoring and environmental chemistry.

Experimental validation of a 0-D numerical model for phase change thermal management systems in lithium-ion batteries

NASA Astrophysics Data System (ADS)

Schweitzer, Ben; Wilke, Stephen; Khateeb, Siddique; Al-Hallaj, Said

2015-08-01

A lumped (0-D) numerical model has been developed for simulating the thermal response of a lithium-ion battery pack with a phase-change composite (PCC™) thermal management system. A small 10s4p battery pack utilizing PCC material was constructed and subjected to discharge at various C-rates in order to validate the lumped model. The 18650 size Li-ion cells used in the pack were electrically characterized to determine their heat generation, and various PCC materials were thermally characterized to determine their apparent specific heat as a function of temperature. Additionally, a 2-D FEA thermal model was constructed to help understand the magnitude of spatial temperature variation in the pack, and to understand the limitations of the lumped model. Overall, good agreement is seen between experimentally measured pack temperatures and the 0-D model, and the 2-D FEA model predicts minimal spatial temperature variation for PCC-based packs at C-rates of 1C and below.

Performance of ZnO based piezo-generators under controlled compression

NASA Astrophysics Data System (ADS)

Tao, Ran; Parmar, Mitesh; Ardila, Gustavo; Oliveira, Paulo; Marques, Daniel; Montès, Laurent; Mouis, Mireille

2017-06-01

This paper reports on the fabrication and characterization of ZnO based vertically integrated nanogenerator (VING) devices under controlled compression. The basic NG structure is a composite material integrating hydrothermally grown vertical piezoelectric zinc oxide (ZnO) nanowires (NWs) into a dielectric matrix (PMMA). A specific characterization set-up has been developed to control the applied compression and the perpendicularity of the applied force on the devices. The role of different fabrication parameters has been evaluated experimentally and compared with previously reported theoretical models, including the thickness of the top PMMA layer and the density of the NWs array in the matrix. Finally, the performance of the VING structure has been evaluated experimentally for different resistive loads obtaining a power density of 85 μW cm-3 considering only the active layer of the device. This has been compared to the performance of a commercial bulk layer of PZT (25 μW cm-3) under the same applied force of 5 N.

Temporal Cyber Attack Detection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ingram, Joey Burton; Draelos, Timothy J.; Galiardi, Meghan

Rigorous characterization of the performance and generalization ability of cyber defense systems is extremely difficult, making it hard to gauge uncertainty, and thus, confidence. This difficulty largely stems from a lack of labeled attack data that fully explores the potential adversarial space. Currently, performance of cyber defense systems is typically evaluated in a qualitative manner by manually inspecting the results of the system on live data and adjusting as needed. Additionally, machine learning has shown promise in deriving models that automatically learn indicators of compromise that are more robust than analyst-derived detectors. However, to generate these models, most algorithms requiremore » large amounts of labeled data (i.e., examples of attacks). Algorithms that do not require annotated data to derive models are similarly at a disadvantage, because labeled data is still necessary when evaluating performance. In this work, we explore the use of temporal generative models to learn cyber attack graph representations and automatically generate data for experimentation and evaluation. Training and evaluating cyber systems and machine learning models requires significant, annotated data, which is typically collected and labeled by hand for one-off experiments. Automatically generating such data helps derive/evaluate detection models and ensures reproducibility of results. Experimentally, we demonstrate the efficacy of generative sequence analysis techniques on learning the structure of attack graphs, based on a realistic example. These derived models can then be used to generate more data. Additionally, we provide a roadmap for future research efforts in this area.« less

Unraveling the benzocaine-receptor interaction at molecular level using mass-resolved spectroscopy.

PubMed

Aguado, Edurne; León, Iker; Millán, Judith; Cocinero, Emilio J; Jaeqx, Sander; Rijs, Anouk M; Lesarri, Alberto; Fernández, José A

2013-10-31

The benzocaine-toluene cluster has been used as a model system to mimic the interaction between the local anesthetic benzocaine and the phenylalanine residue in Na(+) channels. The cluster was generated in a supersonic expansion of benzocaine and toluene in helium. Using a combination of mass-resolved laser-based experimental techniques and computational methods, the complex was fully characterized, finding four conformational isomers in which the molecules are bound through N-H···π and π···π weak hydrogen bonds. The structures of the detected isomers closely resemble those predicted for benzocaine in the inner pore of the ion channels, giving experimental support to previously reported molecular chemistry models.

Integrated Kerr comb-based reconfigurable transversal differentiator for microwave photonic signal processing

NASA Astrophysics Data System (ADS)

Xu, Xingyuan; Wu, Jiayang; Shoeiby, Mehrdad; Nguyen, Thach G.; Chu, Sai T.; Little, Brent E.; Morandotti, Roberto; Mitchell, Arnan; Moss, David J.

2018-01-01

An arbitrary-order intensity differentiator for high-order microwave signal differentiation is proposed and experimentally demonstrated on a versatile transversal microwave photonic signal processing platform based on integrated Kerr combs. With a CMOS-compatible nonlinear micro-ring resonator, high quality Kerr combs with broad bandwidth and large frequency spacings are generated, enabling a larger number of taps and an increased Nyquist zone. By programming and shaping individual comb lines' power, calculated tap weights are realized, thus achieving a versatile microwave photonic signal processing platform. Arbitrary-order intensity differentiation is demonstrated on the platform. The RF responses are experimentally characterized, and systems demonstrations for Gaussian input signals are also performed.

First-principles studies on infrared properties of semiconducting graphene monoxide

NASA Astrophysics Data System (ADS)

Pu, H. H.; Mattson, E. C.; Rhim, S. H.; Gajdardziksa-Josifovska, M.; Hirschmugl, C. J.; Weinert, M.; Chen, J. H.

2013-10-01

Graphene monoxide (GMO), a recently proposed 2D crystalline material in the graphene family, is attractive for next-generation nanoelectronics because of its predicted tunable band gap. As a guide to GMO experimental characterization, we calculate the vibrational properties and obtain three infrared active vibration modes (B1u, B2u, and B3u) and six Raman active modes (B1g, B2g, 2B3g, and 2Ag) for intrinsic GMO. The frequencies of the infrared active modes depend on both local structural deformations and interactions between adjacent GMO layers. These results are consistent with experimental observations and provide a means of estimating the number of layers in intrinsic GMO.

Uncertainty quantification applied to the radiological characterization of radioactive waste.

PubMed

Zaffora, B; Magistris, M; Saporta, G; Chevalier, J-P

2017-09-01

This paper describes the process adopted at the European Organization for Nuclear Research (CERN) to quantify uncertainties affecting the characterization of very-low-level radioactive waste. Radioactive waste is a by-product of the operation of high-energy particle accelerators. Radioactive waste must be characterized to ensure its safe disposal in final repositories. Characterizing radioactive waste means establishing the list of radionuclides together with their activities. The estimated activity levels are compared to the limits given by the national authority of the waste disposal. The quantification of the uncertainty affecting the concentration of the radionuclides is therefore essential to estimate the acceptability of the waste in the final repository but also to control the sorting, volume reduction and packaging phases of the characterization process. The characterization method consists of estimating the activity of produced radionuclides either by experimental methods or statistical approaches. The uncertainties are estimated using classical statistical methods and uncertainty propagation. A mixed multivariate random vector is built to generate random input parameters for the activity calculations. The random vector is a robust tool to account for the unknown radiological history of legacy waste. This analytical technique is also particularly useful to generate random chemical compositions of materials when the trace element concentrations are not available or cannot be measured. The methodology was validated using a waste population of legacy copper activated at CERN. The methodology introduced here represents a first approach for the uncertainty quantification (UQ) of the characterization process of waste produced at particle accelerators. Copyright © 2017 Elsevier Ltd. All rights reserved.

Integrative Structure Determination of Protein Assemblies by Satisfaction of Spatial Restraints

NASA Astrophysics Data System (ADS)

Alber, Frank; Chait, Brian T.; Rout, Michael P.; Sali, Andrej

To understand the cell, we need to determine the structures of macromolecular assemblies, many of which consist of tens to hundreds of components. A great variety of experimental data can be used to characterize the assemblies at several levels of resolution, from atomic structures to component configurations. To maximize completeness, resolution, accuracy, precision and efficiency of the structure determination, a computational approach is needed that can use spatial information from a variety of experimental methods. We propose such an approach, defined by its three main components: a hierarchical representation of the assembly, a scoring function consisting of spatial restraints derived from experimental data, and an optimization method that generates structures consistent with the data. We illustrate the approach by determining the configuration of the 456 proteins in the nuclear pore complex from Baker's yeast.

An Experimental Study of a Low-Jitter Pulsed Electromagnetic Plasma Accelerator

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Lee, Michael; Eskridge, Richard; Smith, James; Martin, Adam; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

An experimental plasma accelerator for a variety of applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 kilometers per second have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

The PANDA tests for SBWR certification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varadi, G.; Dreier, J.; Bandurski, Th.

1996-03-01

The ALPHA project is centered around the experimental and analytical investigation of the long-term decay heat removal from the containments of the next generation of {open_quotes}passive{close_quotes} ALWRs. The project includes integral system tests in the large-scale (1:25 in volume) PANDA facility as well as several other series of tests and supporting analytical work. The first series of experiments to be conducted in PANDA have become a required experimental element in the certification process for the General Electric Simplified Boiling Water Reactor (SBWR). The PANDA general experimental philosophy, facility design, scaling, and instrumentation are described. Steady-state PCCS condenser performance tests andmore » extensive facility characterization tests were already conducted. The transient system behavior tests are underway; preliminary results from the first transient test M3 are reviewed.« less

Experimental investigation of a four-qubit linear-optical quantum logic circuit

NASA Astrophysics Data System (ADS)

Stárek, R.; Mičuda, M.; Miková, M.; Straka, I.; Dušek, M.; Ježek, M.; Fiurášek, J.

2016-09-01

We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C3Z gate and several two-qubit and single-qubit gates. The C3Z gate introduces a sign flip if and only if all four qubits are in the computational state |1>. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses.

Experimental investigation of a four-qubit linear-optical quantum logic circuit.

PubMed

Stárek, R; Mičuda, M; Miková, M; Straka, I; Dušek, M; Ježek, M; Fiurášek, J

2016-09-20

We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C(3)Z gate and several two-qubit and single-qubit gates. The C(3)Z gate introduces a sign flip if and only if all four qubits are in the computational state |1〉. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses.

Next-generation phenotyping: requirements and strategies for enhancing our understanding of genotype-phenotype relationships and its relevance to crop improvement.

PubMed

Cobb, Joshua N; Declerck, Genevieve; Greenberg, Anthony; Clark, Randy; McCouch, Susan

2013-04-01

More accurate and precise phenotyping strategies are necessary to empower high-resolution linkage mapping and genome-wide association studies and for training genomic selection models in plant improvement. Within this framework, the objective of modern phenotyping is to increase the accuracy, precision and throughput of phenotypic estimation at all levels of biological organization while reducing costs and minimizing labor through automation, remote sensing, improved data integration and experimental design. Much like the efforts to optimize genotyping during the 1980s and 1990s, designing effective phenotyping initiatives today requires multi-faceted collaborations between biologists, computer scientists, statisticians and engineers. Robust phenotyping systems are needed to characterize the full suite of genetic factors that contribute to quantitative phenotypic variation across cells, organs and tissues, developmental stages, years, environments, species and research programs. Next-generation phenotyping generates significantly more data than previously and requires novel data management, access and storage systems, increased use of ontologies to facilitate data integration, and new statistical tools for enhancing experimental design and extracting biologically meaningful signal from environmental and experimental noise. To ensure relevance, the implementation of efficient and informative phenotyping experiments also requires familiarity with diverse germplasm resources, population structures, and target populations of environments. Today, phenotyping is quickly emerging as the major operational bottleneck limiting the power of genetic analysis and genomic prediction. The challenge for the next generation of quantitative geneticists and plant breeders is not only to understand the genetic basis of complex trait variation, but also to use that knowledge to efficiently synthesize twenty-first century crop varieties.

Enhancing efficiency and quality of statistical estimation of immunogenicity assay cut points through standardization and automation.

PubMed

Su, Cheng; Zhou, Lei; Hu, Zheng; Weng, Winnie; Subramani, Jayanthi; Tadkod, Vineet; Hamilton, Kortney; Bautista, Ami; Wu, Yu; Chirmule, Narendra; Zhong, Zhandong Don

2015-10-01

Biotherapeutics can elicit immune responses, which can alter the exposure, safety, and efficacy of the therapeutics. A well-designed and robust bioanalytical method is critical for the detection and characterization of relevant anti-drug antibody (ADA) and the success of an immunogenicity study. As a fundamental criterion in immunogenicity testing, assay cut points need to be statistically established with a risk-based approach to reduce subjectivity. This manuscript describes the development of a validated, web-based, multi-tier customized assay statistical tool (CAST) for assessing cut points of ADA assays. The tool provides an intuitive web interface that allows users to import experimental data generated from a standardized experimental design, select the assay factors, run the standardized analysis algorithms, and generate tables, figures, and listings (TFL). It allows bioanalytical scientists to perform complex statistical analysis at a click of the button to produce reliable assay parameters in support of immunogenicity studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Sustained State-Independent Quantum Contextual Correlations from a Single Ion

NASA Astrophysics Data System (ADS)

Leupold, F. M.; Malinowski, M.; Zhang, C.; Negnevitsky, V.; Alonso, J.; Home, J. P.; Cabello, A.

2018-05-01

We use a single trapped-ion qutrit to demonstrate the quantum-state-independent violation of noncontextuality inequalities using a sequence of randomly chosen quantum nondemolition projective measurements. We concatenate 53 ×106 sequential measurements of 13 observables, and unambiguously violate an optimal noncontextual bound. We use the same data set to characterize imperfections including signaling and repeatability of the measurements. The experimental sequence was generated in real time with a quantum random number generator integrated into our control system to select the subsequent observable with a latency below 50 μ s , which can be used to constrain contextual hidden-variable models that might describe our results. The state-recycling experimental procedure is resilient to noise and independent of the qutrit state, substantiating the fact that the contextual nature of quantum physics is connected to measurements and not necessarily to designated states. The use of extended sequences of quantum nondemolition measurements finds applications in the fields of sensing and quantum information.

Measurements on a guitar string as an example of a physical nonlinear driven oscillator

NASA Astrophysics Data System (ADS)

Carlà, Marcello; Straulino, Samuele

2017-08-01

An experimental study is described to characterize the oscillation of a guitar string around resonance. A periodic force was applied to the string, generated by the electromagnetic interaction between an alternating current flowing in the string and a magnetic field. The oscillation was studied by measuring the voltage induced in the string itself, which is proportional to the velocity. Accurate quantitative data were obtained for the velocity, both modulus and phase, with a time resolution of 3 ms, corresponding to the oscillation period. The measuring instrument was a personal computer with its sound card and an electronic amplifier, both used to generate the excitation current and record the velocity signal, while performing the required frequency sweep. The study covered an excitation force range more than two and half decades wide (51 dB). The experimental results showed very good agreement with the theoretical behavior of a Duffing oscillator with nonlinear damping over about two decades.

Explosively produced fracture of oil shale

NASA Astrophysics Data System (ADS)

Morris, W. A.

1982-05-01

Rock fragmentation research in oil shale to develop the blasting technologies and designs required to prepare a rubble bed for a modified in situ retort is reported. Experimental work is outlined, proposed studies in explosive characterization are detailed and progress in numerical calculation techniques to predict fracture of the shale is described. A detailed geologic characterization of two Anvil Points experiment sites is related to previous work at Colony Mine. The second section focuses on computer modeling and theory. The latest generation of the stress wave code SHALE, its three dimensional potential, and the slide line package for it are described. A general stress rate equation that takes energy dependence into account is discussed.

Ice Accretion Roughness Measurements and Modeling

NASA Technical Reports Server (NTRS)

McClain, Stephen T.; Vargas, Mario; Tsao, Jen-Ching; Broeren, Andy P.; Lee, Sam

2017-01-01

Roughness on aircraft ice accretions is very important to the overall ice accretion process and to the resulting degradation in aircraft aerodynamic performance. Roughness enhances the local convection leading to more rapid ice accumulation rates, and roughness generates local flow perturbations that lead to higher skin friction. This paper presents 1) a review of the developments in ice shape three-dimensional laser scanning developed at NASA Glenn, 2) a review of the approach of McClain and Kreeger employed to characterize ice roughness evolution on an airfoil surface, and 3) a review of the experimental efforts that have been performed over the last five years to characterize, scale, and model ice roughness evolution physics.

Perspective: Composition–structure–property mapping in high-throughput experiments: Turning data into knowledge

DOE PAGES

Hattrick-Simpers, Jason R.; Gregoire, John M.; Kusne, A. Gilad

2016-05-26

With their ability to rapidly elucidate composition-structure-property relationships, high-throughput experimental studies have revolutionized how materials are discovered, optimized, and commercialized. It is now possible to synthesize and characterize high-throughput libraries that systematically address thousands of individual cuts of fabrication parameter space. An unresolved issue remains transforming structural characterization data into phase mappings. This difficulty is related to the complex information present in diffraction and spectroscopic data and its variation with composition and processing. Here, we review the field of automated phase diagram attribution and discuss the impact that emerging computational approaches will have in the generation of phase diagrams andmore » beyond.« less

Formation and acceleration of uniformly filled ellipsoidal electron bunches obtained via space-charge-driven expansion from a cesium-telluride photocathode

NASA Astrophysics Data System (ADS)

Piot, P.; Sun, Y.-E.; Maxwell, T. J.; Ruan, J.; Secchi, E.; Thangaraj, J. C. T.

2013-01-01

We report the experimental generation, acceleration, and characterization of a uniformly filled electron bunch obtained via space-charge-driven expansion (often referred to as “blow-out regime”) in an L-band (1.3-GHz) radiofrequency photoinjector. The beam is photoemitted from a cesium-telluride semiconductor photocathode using a short (<200fs) ultraviolet laser pulse. The produced electron bunches are characterized with conventional diagnostics and the signatures of their ellipsoidal character are observed. We especially demonstrate the production of ellipsoidal bunches with charges up to ˜0.5nC corresponding to a ˜20-fold increase compared to previous experiments with metallic photocathodes.

Multi-Mode Excitation and Data Reduction for Fatigue Crack Characterization in Conducting Plates

NASA Technical Reports Server (NTRS)

Wincheski, B.; Namkung, M.; Fulton, J. P.; Clendenin, C. G.

1992-01-01

Advances in the technique of fatigue crack characterization by resonant modal analysis have been achieved through a new excitation mechanism and data reduction of multiple resonance modes. A non-contacting electromagnetic device is used to apply a time varying Lorentz force to thin conducting sheets. The frequency and direction of the Lorentz force are such that resonance modes are generated in the test sample. By comparing the change in frequency between distinct resonant modes of a sample, detecting and sizing of fatigue cracks are achieved and frequency shifts caused by boundary condition changes can be discriminated against. Finite element modeling has been performed to verify experimental results.

Space Shuttle Project

NASA Image and Video Library

1995-10-20

A Great Blue Heron seems oblivious to the tremendous spectacle of light and sound generated by a Shuttle liftoff, as the Space Shuttle Columbia (STS-73) soars skyward from Launch Pad 39B. Columbia's seven member crew's mission included continuing experimentation in the Marshall managed payloads including the United States Microgravity Laboratory 2 (USML-2) and the keel-mounted accelerometer that characterizes the very low frequency acceleration environment of the orbiter payload bay during space flight, known as the Orbital Acceleration Research Experiment (OARE).

Feasibility of Dual Optics/Ultrasound Imaging and Contrast Media for the Detection and Characterization of Prostate Cancer

DTIC Science & Technology

2010-03-01

ultrasound microbubbles and generation of higher harmonic modulation. We also demonstrated acousto- optic detection with a novel SPAD detector. During...NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON USAMRMC a. REPORT U b. ABSTRACT U c . THIS PAGE U UU 27 19b. TELEPHONE NUMBER (include...pass Filter Digital Scope Silicon Photodetector (a) (b) ( c ) Figure 2a) Experimental set-up for detection of ultrasound-modulated

A novel recombinant Leishmania donovani p45, a partial coding region of methionine aminopeptidase, generates protective immunity by inducing a Th1 stimulatory response against experimental visceral leishmaniasis.

PubMed

Gupta, Reema; Kushawaha, Pramod K; Tripathi, Chandra Dev Pati; Sundar, Shyam; Dube, Anuradha

2012-05-01

The development of a vaccine against visceral leishmaniasis (VL) conferring long-lasting immunity remains a challenge. Identification and proteomic characterization of parasite proteins led to the detection of p45, a member of the methionine aminopeptidase family. To our knowledge the present study is the first known report that describes the molecular and immunological characterization of p45. Recombinant Leishmania donovani p45 (rLdp45) induced cellular responses in cured hamsters and generated Th1-type cytokines from peripheral blood mononuclear cells of cured/endemic VL patients. Immunization with rLdp45 exerted considerable prophylactic efficacy (∼85%) supported by an increase in mRNA expression of iNOS, IFN-γ, TNF-α and IL-12 and decrease in TGF-β and IL-4, indicating its potential as a vaccine candidate against VL. Copyright © 2012. Published by Elsevier Ltd.

A forward model-based validation of cardiovascular system identification

NASA Technical Reports Server (NTRS)

Mukkamala, R.; Cohen, R. J.

2001-01-01

We present a theoretical evaluation of a cardiovascular system identification method that we previously developed for the analysis of beat-to-beat fluctuations in noninvasively measured heart rate, arterial blood pressure, and instantaneous lung volume. The method provides a dynamical characterization of the important autonomic and mechanical mechanisms responsible for coupling the fluctuations (inverse modeling). To carry out the evaluation, we developed a computational model of the cardiovascular system capable of generating realistic beat-to-beat variability (forward modeling). We applied the method to data generated from the forward model and compared the resulting estimated dynamics with the actual dynamics of the forward model, which were either precisely known or easily determined. We found that the estimated dynamics corresponded to the actual dynamics and that this correspondence was robust to forward model uncertainty. We also demonstrated the sensitivity of the method in detecting small changes in parameters characterizing autonomic function in the forward model. These results provide confidence in the performance of the cardiovascular system identification method when applied to experimental data.

Developing instrumentation to characterize thermoelectric generator modules.

PubMed

Liu, Dawei; Li, Qiming; Peng, Wenbo; Zhu, Lianjun; Gao, Hu; Meng, Qingsen; Jin, A J

2015-03-01

Based on the law of physics, known as "Seebeck effect," a thermoelectric generator (TEG) produces electricity when the temperature differential is applied across the TEG. This article reports a precision method in characterizing TEG modules. A precision instrument is constructed to study thermoelectric conversion in terms of output power and efficiency of TEG modules. The maximum allowable TEG module size is 150 mm, and the preferred size is from 30 mm to 60 mm. During measurements, the highest hot side temperature is 500 °C and the cold side temperature can be adjusted from room temperature to 100 °C. A mechanical structure is developed to control the pressure and parallelism of the clamping force of the TEG on both its hot and cold sides. A heat flux measurement module is installed at its cold side, and the heat flux through TEGs can be measured in position. Finally, the energy conversion efficiency of TEGs is calculated from experimental data of both an output power and a heat flux.

Measurements of heat generation in prismatic Li-ion batteries

NASA Astrophysics Data System (ADS)

Chen, Kaiwei; Unsworth, Grant; Li, Xianguo

2014-09-01

An accurate understanding of the characteristics of battery heat generation is essential to the development and success of thermal management systems for electric vehicles. In this study, a calorimeter capable of measuring the heat generation rates of a prismatic battery is developed and verified by using a controllable electric heater. The heat generation rates of a prismatic A123 LiFePO4 battery is measured for discharge rates ranging from 0.25C to 3C and operating temperature ranging from -10 °C to 40 °C. At low rates of discharge the heat generation is not significant, even becoming endothermic at the battery operating temperatures of 30 °C and 40 °C. Heat of mixing is observed to be a non-negligible component of total heat generation at discharge rates as low as 0.25C for all tested battery operating temperatures. A double plateau in battery discharge curve is observed for operating temperatures of 30 °C and 40 °C. The developed experimental facility can be used for the characterization of heat generation for any prismatic battery, regardless of chemistries.

Techniques for the characterization of sub-10-fs optical pulses: a comparison

NASA Astrophysics Data System (ADS)

Gallmann, L.; Sutter, D. H.; Matuschek, N.; Steinmeyer, G.; Keller, U.

Several methods have been proposed for the phase and amplitude characterization of sub-10-fs pulses with nJ energies. An overview of these techniques is presented, with a focus on the comparison of second-harmonic generation frequency-resolved optical gating (SHG-FROG) and spectral phase interferometry for direct electric-field reconstruction (SPIDER). We describe a collinear FROG variant based on type-II phase-matching that completely avoids the geometrical blurring artifact and use both this and SPIDER for the characterization of sub-10-fs Ti:sapphire laser pulses. The results of both methods are compared in an extensive statistical analysis. From this first direct experimental comparison of FROG and SPIDER, guidelines for accurate measurements of sub-10-fs pulses are derived. We point out limitations of both methods for pulses in this ultrashort pulse regime.

Characterization of a Setup to test the Impact of High-Amplitude Pressure Waves on Living Cells

PubMed Central

Schmidt, Mischa; Kahlert, Ulf; Wessolleck, Johanna; Maciaczyk, Donata; Merkt, Benjamin; Maciaczyk, Jaroslaw; Osterholz, Jens; Nikkhah, Guido; Steinhauser, Martin O.

2014-01-01

The impact of pressure waves on cells may provide several possible applications in biology and medicine including the direct killing of tumors, drug delivery or gene transfection. In this study we characterize the physical properties of mechanical pressure waves generated by a nanosecond laser pulse in a setup with well-defined cell culture conditions. To systematically characterize the system on the relevant length and time scales (micrometers and nanoseconds) we use photon Doppler velocimetry (PDV) and obtain velocity profiles of the cell culture vessel at the passage of the pressure wave. These profiles serve as input for numerical pressure wave simulations that help to further quantify the pressure conditions on the cellular length scale. On the biological level we demonstrate killing of glioblastoma cells and quantify experimentally the pressure threshold for cell destruction. PMID:24458018

Sequence Data for Clostridium autoethanogenum using Three Generations of Sequencing Technologies

DOE PAGES

Utturkar, Sagar M.; Klingeman, Dawn Marie; Bruno-Barcena, José M.; ...

2015-04-14

During the past decade, DNA sequencing output has been mostly dominated by the second generation sequencing platforms which are characterized by low cost, high throughput and shorter read lengths for example, Illumina. The emergence and development of so called third generation sequencing platforms such as PacBio has permitted exceptionally long reads (over 20 kb) to be generated. Due to read length increases, algorithm improvements and hybrid assembly approaches, the concept of one chromosome, one contig and automated finishing of microbial genomes is now a realistic and achievable task for many microbial laboratories. In this paper, we describe high quality sequencemore » datasets which span three generations of sequencing technologies, containing six types of data from four NGS platforms and originating from a single microorganism, Clostridium autoethanogenum. The dataset reported here will be useful for the scientific community to evaluate upcoming NGS platforms, enabling comparison of existing and novel bioinformatics approaches and will encourage interest in the development of innovative experimental and computational methods for NGS data.« less

Experimental Testing of a Metamaterial Slow Wave Structure for High-Power Microwave Generation

NASA Astrophysics Data System (ADS)

Shipman, K.; Prasad, S.; Andreev, D.; Fisher, D. M.; Reass, D. B.; Schamiloglu, E.; Gilmore, M.

2017-10-01

A high-power L band source has been developed using a metamaterial (MTM) to produce a double negative slow wave structure (SWS) for interaction with an electron beam. The beam is generated by a 700 kV, 6 kA short pulse (10 ns) accelerator. The design of the SWS consists of a cylindrical waveguide, loaded with alternating split-rings that are arrayed axially down the waveguide. The beam is guided down the center of the rings, where electrons interact with the MTM-SWS producing radiation. Power is extracted axially via a circular waveguide, and radiated by a horn antenna. Microwaves are characterized by an external detector placed in a waveguide. Mode characterization is performed using a neon bulb array. The bulbs are lit by the electric field, resulting in an excitation pattern that resembles the field pattern. This is imaged using an SLR camera. The MTM structure has electrically small features so breakdown is a concern. In addition to high speed cameras, a fiber-optic-fed, sub-ns photomultiplier tube array diagnostic has been developed and used to characterize breakdown light. Work supported by the Air Force Office of Scientific Research, MURI Grant FA9550-12-1-0489.

Comparative Characterization of Crofelemer Samples Using Data Mining and Machine Learning Approaches With Analytical Stability Data Sets.

PubMed

Nariya, Maulik K; Kim, Jae Hyun; Xiong, Jian; Kleindl, Peter A; Hewarathna, Asha; Fisher, Adam C; Joshi, Sangeeta B; Schöneich, Christian; Forrest, M Laird; Middaugh, C Russell; Volkin, David B; Deeds, Eric J

2017-11-01

There is growing interest in generating physicochemical and biological analytical data sets to compare complex mixture drugs, for example, products from different manufacturers. In this work, we compare various crofelemer samples prepared from a single lot by filtration with varying molecular weight cutoffs combined with incubation for different times at different temperatures. The 2 preceding articles describe experimental data sets generated from analytical characterization of fractionated and degraded crofelemer samples. In this work, we use data mining techniques such as principal component analysis and mutual information scores to help visualize the data and determine discriminatory regions within these large data sets. The mutual information score identifies chemical signatures that differentiate crofelemer samples. These signatures, in many cases, would likely be missed by traditional data analysis tools. We also found that supervised learning classifiers robustly discriminate samples with around 99% classification accuracy, indicating that mathematical models of these physicochemical data sets are capable of identifying even subtle differences in crofelemer samples. Data mining and machine learning techniques can thus identify fingerprint-type attributes of complex mixture drugs that may be used for comparative characterization of products. Copyright © 2017 American Pharmacists Association®. All rights reserved.

Hydrodynamic simulations of long-scale-length plasmas for two-plasmon-decay planar-target experiments on the NIF

NASA Astrophysics Data System (ADS)

Solodov, A. A.; Rosenberg, M. J.; Myatt, J. F.; Epstein, R.; Regan, S. P.; Seka, W.; Shaw, J.; Hohenberger, M.; Bates, J. W.; Moody, J. D.; Ralph, J. E.; Turnbull, D. P.; Barrios, M. A.

2016-05-01

The two-plasmon-decay (TPD) instability can be detrimental for direct-drive inertial confinement fusion because it generates high-energy electrons that can preheat the target, thereby reducing target performance. Hydrodynamic simulations to design a new experimental platform to investigate TPD and other laser-plasma instabilities relevant to direct-drive-ignition implosions at the National Ignition Facility are presented. The proposed experiments utilize planar plastic targets with an embedded Mo layer to characterize generation of hot electrons through Mo Kα fluorescence and hard x-ray emission. Different laser-irradiation geometries approximate conditions near both the equator and the pole of a polar-direct-drive implosion.

Emitted radiation characteristics of plutonium dioxide radioisotope thermoelectric generators

NASA Technical Reports Server (NTRS)

Gingo, P. J.; Steyn, J. J.

1971-01-01

The nuclear and emitted radiation characteristics of the radioisotope elements and impurities in commercial grade plutonium dioxide are presented in detail. The development of the methods of analysis are presented. Radioisotope thermoelectric generators (RTG) of 1575, 3468 and 5679 thermal watts are characterized with respect to neutron and gamma photon source strength as well as spatial and number flux distribution. The results are presented as a function of detector position and light element contamination concentration for fuel age ranging from 'fresh' to 18 years. The data may be used to obtain results for given O-18 and Pu-236 concentrations. The neutron and gamma photon flux and dose calculations compare favorably with reported experimental values for SNAP-27.

Calibration of Kinect for Xbox One and Comparison between the Two Generations of Microsoft Sensors

PubMed Central

Pagliari, Diana; Pinto, Livio

2015-01-01

In recent years, the videogame industry has been characterized by a great boost in gesture recognition and motion tracking, following the increasing request of creating immersive game experiences. The Microsoft Kinect sensor allows acquiring RGB, IR and depth images with a high frame rate. Because of the complementary nature of the information provided, it has proved an attractive resource for researchers with very different backgrounds. In summer 2014, Microsoft launched a new generation of Kinect on the market, based on time-of-flight technology. This paper proposes a calibration of Kinect for Xbox One imaging sensors, focusing on the depth camera. The mathematical model that describes the error committed by the sensor as a function of the distance between the sensor itself and the object has been estimated. All the analyses presented here have been conducted for both generations of Kinect, in order to quantify the improvements that characterize every single imaging sensor. Experimental results show that the quality of the delivered model improved applying the proposed calibration procedure, which is applicable to both point clouds and the mesh model created with the Microsoft Fusion Libraries. PMID:26528979

Plasma characterization for application in ballistics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katulka, G.; Nusca, M.; White, K.

1996-12-31

There is currently a strong motivation for improving the existing performance of fielded military gun systems. For that objective, research over the past several years has been carried out in an effort to enhance performance by addition of energy into the gun chamber by way of a plasma generator. This energy addition, referred to as Electro-thermal Chemical (ETC) propulsion, can be readily controlled electrically where it can be used to ignite the chamber`s energetic material, enhance the total energy, and control the interior process through control of the propellant combustion. To realize the potential advantages of this system it ismore » important to characterize the plasma generator in terms of (a) the impedance characteristics and its relationship to the pulse forming network used to generate the plasma, (b) the plasma output energy components such as radiation and convection in both time and space, (c) the details of the hydrodynamic interactions of the plasma with the propelling charge bed in the gun chamber and, (d) the direct effect of the plasma on the propellant reactions. Experimental studies have been carried out to study the effect of the plasma radiation on the propellant characteristics related to combustion.« less

Calibration of Kinect for Xbox One and Comparison between the Two Generations of Microsoft Sensors.

PubMed

Pagliari, Diana; Pinto, Livio

2015-10-30

In recent years, the videogame industry has been characterized by a great boost in gesture recognition and motion tracking, following the increasing request of creating immersive game experiences. The Microsoft Kinect sensor allows acquiring RGB, IR and depth images with a high frame rate. Because of the complementary nature of the information provided, it has proved an attractive resource for researchers with very different backgrounds. In summer 2014, Microsoft launched a new generation of Kinect on the market, based on time-of-flight technology. This paper proposes a calibration of Kinect for Xbox One imaging sensors, focusing on the depth camera. The mathematical model that describes the error committed by the sensor as a function of the distance between the sensor itself and the object has been estimated. All the analyses presented here have been conducted for both generations of Kinect, in order to quantify the improvements that characterize every single imaging sensor. Experimental results show that the quality of the delivered model improved applying the proposed calibration procedure, which is applicable to both point clouds and the mesh model created with the Microsoft Fusion Libraries.

High-spatial-resolution sub-surface imaging using a laser-based acoustic microscopy technique.

PubMed

Balogun, Oluwaseyi; Cole, Garrett D; Huber, Robert; Chinn, Diane; Murray, Todd W; Spicer, James B

2011-01-01

Scanning acoustic microscopy techniques operating at frequencies in the gigahertz range are suitable for the elastic characterization and interior imaging of solid media with micrometer-scale spatial resolution. Acoustic wave propagation at these frequencies is strongly limited by energy losses, particularly from attenuation in the coupling media used to transmit ultrasound to a specimen, leading to a decrease in the depth in a specimen that can be interrogated. In this work, a laser-based acoustic microscopy technique is presented that uses a pulsed laser source for the generation of broadband acoustic waves and an optical interferometer for detection. The use of a 900-ps microchip pulsed laser facilitates the generation of acoustic waves with frequencies extending up to 1 GHz which allows for the resolution of micrometer-scale features in a specimen. Furthermore, the combination of optical generation and detection approaches eliminates the use of an ultrasonic coupling medium, and allows for elastic characterization and interior imaging at penetration depths on the order of several hundred micrometers. Experimental results illustrating the use of the laser-based acoustic microscopy technique for imaging micrometer-scale subsurface geometrical features in a 70-μm-thick single-crystal silicon wafer with a (100) orientation are presented.

Exit blade geometry and part-load performance of small axial flow propeller turbines: An experimental investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Punit; Nestmann, Franz

2010-09-15

A detailed experimental investigation of the effects of exit blade geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of blade profile, geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle couldmore » be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model's limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it can be made capable for accurate characterization of blade geometric effects. (author)« less

Three dimensional (3D) microstructure-based finite element modeling of Al-SiC nanolaminates using focused ion beam (FIB) tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayer, Carl R.

Al-SiC nanolaminate composites show promise as high performance coating materials due to their combination of strength and toughness. Although a significant amount of modeling effort has been focused on materials with an idealized flat nanostructure, experimentally these materials exhibit complex undulating layer geometries. This work utilizes FIB tomography to characterize this nanostructure in 3D and finite element modeling to determine the effect that this complex structure has on the mechanical behavior of these materials. A sufficiently large volume was characterized such that a 1 × 2 μm micropillar could be generated from the dataset and compared directly to experimental results.more » The mechanical response from this nanostructure was then compared to pillar models using simplified structures with perfectly flat layers, layers with sinusoidal waviness, and layers with arc segment waviness. The arc segment based layer geometry showed the best agreement with the experimentally determined structure, indicating it would be the most appropriate geometry for future modeling efforts. - Highlights: •FIB tomography was used to determine the structure of an Al-SiC nanolaminate in 3D. •FEM was used to compare the deformation of the nanostructure to experimental results. •Idealized structures from literature were compared to the FIB determined structure. •Arc segment based structures approximated the FIB determined structure most closely.« less

Experimental Characterization of Nonlinear Viscoelastic and Adhesive Properties of Elastomers

DTIC Science & Technology

2006-07-27

Final report to the Office of Naval Research on the Experimental Characterization of Nonlinear Viscoelastic and Adhesive Properties of Elastomers ...Experimental Characterization of Nonlinear Viscoelastic and Adhesive Properties of Elastomers 5b. GRANT NUMBER N000 14-1-0400 5c. PROGRAM ELEMENT...Experimental Characterization of Nonlinear Viscoelastic and Adhesive Properties of Elastomers Principal Investigator K. Ravi-Chandar Organization The University

Experimental characterization of turbulent inflow noise on a full-scale wind turbine

NASA Astrophysics Data System (ADS)

Buck, Steven; Oerlemans, Stefan; Palo, Scott

2016-12-01

An extensive experimental campaign was conducted on a 108-m diameter 2.3-MW wind turbine in order to assess the effect of inflow turbulence conditions on wind turbine acoustics. Over 50 h of continuous acoustic data was acquired at power-generating wind speeds. Twelve precision microphones were used, arranged in a one rotor radius ring about the turbine tower in order to assess the directivity of the noise emission. Turbine operational and atmospheric conditions were gathered simultaneously with acoustics measurements. The testing and analysis constitute perhaps the most thorough experimental characterization of turbulent inflow noise from a wind turbine to date. Turbulence intensities typically varied between 10 percent and 35 percent, and wind speeds covered most of the operational range of the wind turbine, from cut-on to well above its rated power. A method was developed for using blade-mounted accelerometers for determining the turbulence conditions in the immediate vicinity of the blades, which are the primary turbulence noise generating bodies. The method uses the blades' vibrational energy within a specified frequency range to estimate the overall turbulence conditions by assuming a von Kármán turbulence spectrum. Using this method, a clear positive correlation is shown between turbulence intensity and noise levels. The turbulence noise is dominant at low frequencies and is primarily observed in the upwind and downwind directions. Low frequency noise increases by as much as 6 dB for the range of turbulence conditions measured. Comparisons are made between the measured turbine noise directivity and theory using a simple acoustic model of the turbine as three point-sources. Strong agreement is found between the theoretical leading edge noise directivity model and the measured low frequency noise directivity.

Generation of a femtosecond electron microbunch train from a photocathode using twofold Michelson interferometer

NASA Astrophysics Data System (ADS)

Shevelev, M.; Aryshev, A.; Terunuma, N.; Urakawa, J.

2017-10-01

The interest in producing ultrashort electron bunches has risen sharply among scientists working on the design of high-gradient wakefield accelerators. One attractive approach generating electron bunches is to illuminate a photocathode with a train of femtosecond laser pulses. In this paper we describe the design and testing of a laser system for an rf gun based on a commercial titanium-sapphire laser technology. The technology allows the production of four femtosecond laser pulses with a continuously variable pulse delay. We also use the designed system to demonstrate the experimental generation of an electron microbunch train obtained by illuminating a cesium-telluride semiconductor photocathode. We use conventional diagnostics to characterize the electron microbunches produced and confirm that it may be possible to control the main parameter of an electron microbunch train.

Dynamic generation of Ince-Gaussian modes with a digital micromirror device

NASA Astrophysics Data System (ADS)

Ren, Yu-Xuan; Fang, Zhao-Xiang; Gong, Lei; Huang, Kun; Chen, Yue; Lu, Rong-De

2015-04-01

Ince-Gaussian (IG) beam with elliptical profile, as a connection between Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) beams, has showed unique advantages in some applications such as quantum entanglement and optical micromanipulation. However, its dynamic generation with high switching frequency is still challenging. Here, we experimentally reported the quick generation of Ince-Gaussian beam by using a digital micro-mirror device (DMD), which has the highest switching frequency of 5.2 kHz in principle. The configurable properties of DMD allow us to observe the quasi-smooth variation from LG (with ellipticity ɛ = 0 ) to IG and HG ( ɛ = ∞ ) beam. This approach might pave a path to high-speed quantum communication in terms of IG beam. Additionally, the characterized axial plane intensity distribution exhibits a 3D mould potentially being employed for optical micromanipulation.

Automated CFD Database Generation for a 2nd Generation Glide-Back-Booster

NASA Technical Reports Server (NTRS)

Chaderjian, Neal M.; Rogers, Stuart E.; Aftosmis, Michael J.; Pandya, Shishir A.; Ahmad, Jasim U.; Tejmil, Edward

2003-01-01

A new software tool, AeroDB, is used to compute thousands of Euler and Navier-Stokes solutions for a 2nd generation glide-back booster in one week. The solution process exploits a common job-submission grid environment using 13 computers located at 4 different geographical sites. Process automation and web-based access to the database greatly reduces the user workload, removing much of the tedium and tendency for user input errors. The database consists of forces, moments, and solution files obtained by varying the Mach number, angle of attack, and sideslip angle. The forces and moments compare well with experimental data. Stability derivatives are also computed using a monotone cubic spline procedure. Flow visualization and three-dimensional surface plots are used to interpret and characterize the nature of computed flow fields.

Online impedance spectroscopy of lead acid batteries for storage management of a standalone power plant

NASA Astrophysics Data System (ADS)

Depernet, Daniel; Ba, Oumar; Berthon, Alain

2012-12-01

This paper presents a contribution to implementation of hybrid power plants in rural areas without electricity in Senegal. Wind and photovoltaic generators coupling is used to benefit from renewable energy resources in this country. Lead acid storage batteries are coupled with the generators to ensure smoothness of the electricity generation. This work is focused in particular on the development of a low cost online impedance spectroscopy method to address the problem of limited lifetime of batteries and the difficulties of their maintenance in isolated areas. Control of static converter associated with the battery is adapted to integrate the functionality of characterization of batteries by impedance spectroscopy. An experimental platform developed in the laboratory has validated the method for online measurement of battery impedance spectrum and to initiate a phase of data monitoring.

Generation, Analysis and Characterization of Anisotropic Engineered Meta Materials

NASA Astrophysics Data System (ADS)

Trifale, Ninad T.

A methodology for a systematic generation of highly anisotropic micro-lattice structures was investigated. Multiple algorithms for generation and validation of engineered structures are developed and evaluated. Set of all possible permutations of structures for an 8-node cubic unit cell were considered and the degree of anisotropy of meta-properties in heat transport and mechanical elasticity were evaluated. Feasibility checks were performed to ensure that the generated unit cell network was repeatable and a continuous lattice structure. Four different strategies for generating permutations of the structures are discussed. Analytical models were developed to predict effective thermal, mechanical and permeability characteristics of these cellular structures.Experimentation and numerical modeling techniques were used to validate the models that are developed. A self-consistent mechanical elasticity model was developed which connects the meso-scale properties to stiffness of individual struts. A three dimensional thermal resistance network analogy was used to evaluate the effective thermal conductivity of the structures. The struts were modeled as a network of one dimensional thermal resistive elements and effective conductivity evaluated. Models were validated against numerical simulations and experimental measurements on 3D printed samples. Model was developed to predict effective permeability of these engineered structures based on Darcy's law. Drag coefficients were evaluated for individual connections in transverse and longitudinal directions and an interaction term was calibrated from the experimental data in literature in order to predict permeability. Generic optimization framework coupled to finite element solver is developed for analyzing any application involving use of porous structures. An objective functions were generated structure to address frequently observed trade-off between the stiffness, thermal conductivity, permeability and porosity. Three application were analyzed for potential use of engineered materials. Heat spreader application involving thermal and mechanical constraints, artificial bone grafts application involving mechanical and permeability constraints and structural materials applications involving mechanical, thermal and porosity constraints is analyzed. Recommendations for optimum topologies for specific operating conditions are provided.

A chlorophyll fluorescence-based method for the integrated characterization of the photophysiological response to light stress.

PubMed

Serôdio, João; Schmidt, William; Frankenbach, Silja

2017-02-01

This work introduces a new experimental method for the comprehensive description of the physiological responses to light of photosynthetic organisms. It allows the integration in a single experiment of the main established manipulative chlorophyll fluorescence-based protocols. It enables the integrated characterization of the photophysiology of samples regarding photoacclimation state (generating non-sequential light-response curves of effective PSII quantum yield, electron transport rate or non-photochemical quenching), photoprotection capacity (running light stress-recovery experiments, quantifying non-photochemical quenching components) and the operation of photoinactivation and photorepair processes (measuring rate constants of photoinactivation and repair for different light levels and the relative quantum yield of photoinactivation). The new method is based on a previously introduced technique, combining the illumination of a set of replicated samples with spatially separated actinic light beams of different intensity, and the simultaneous measurement of the fluorescence emitted by all samples using an imaging fluorometer. The main novelty described here is the independent manipulation of light intensity and duration of exposure for each sample, and the control of the cumulative light dose applied. The results demonstrate the proof of concept for the method, by comparing the responses of cultures of Chlorella vulgaris acclimated to low and high light regimes, highlighting the mapping of light stress responses over a wide range of light intensity and exposure conditions, and the rapid generation of paired light-response curves of photoinactivation and repair rate constants. This approach represents a chlorophyll fluorescence 'protocol of everything', contributing towards the high throughput characterization of the photophysiology of photosynthetic organisms. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Attrition of limestone by impact loading in fluidized beds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fabrizio Scala; Fabio Montagnaro; Piero Salatino

2007-09-15

The present study addresses limestone attrition and fragmentation associated with impact loading, a process which may occur extensively in various regions of fluidized bed (FB) combustors/gasifiers, primarily the jetting region of the bottom bed, the exit region of the riser, and the cyclone. An experimental protocol for the characterization of the propensity of limestone to undergo attrition/fragmentation by impact loading is reported. The application of the protocol is demonstrated with reference to an Italian limestone whose primary fragmentation and attrition by surface wear have already been characterized in previous studies. The experimental procedure is based on the characterization of themore » amount and particle size distribution of the debris generated upon the impact of samples of sorbent particles against a target. Experiments were carried out at a range of particle impact velocities between 10 and 45 m/s, consistent with jet velocities corresponding to typical pressure drops across FB gas distributors. The protocol has been applied to either raw or preprocessed limestone samples. In particular, the effect of calcination, sulfation, and calcination/recarbonation cycles on the impact damage suffered by sorbent particles has been assessed. The measurement of particle voidage and pore size distribution by mercury intrusion was also accomplished to correlate fragmentation with the structural properties of the sorbent samples. Fragmentation by impact loading of the limestone is significant. Lime displays the largest propensity to undergo impact damage, followed by the sorbent sulfated to exhaustion, the recarbonated sorbent, and the raw limestone. Fragmentation of the raw limestone and of the sulfated lime follows a pattern typical of the failure of brittle materials. The fragmentation behavior of lime and recarbonated lime better conforms to a disintegration failure mode, with an extensive generation of very fine fragments. 27 refs., 9 figs. 1 tab.« less

Thermomechanical deformation testing and modeling in the presence of metallurgical instabilities. M.S. Thesis - Akron Univ. Final Report

NASA Technical Reports Server (NTRS)

Castelli, Michael G.

1990-01-01

A number of viscoplastic constitutive models were developed to describe deformation behavior under complex combinations of thermal and mechanical loading. Questions remain, however, regarding the validity of procedures used to characterize these models for specific structural alloys. One area of concern is that the majority of experimental data available for this purpose are determined under isothermal conditions. This experimental study is aimed at determining whether viscoplastic constitutive theories characterized using an isothermal data base can adequately model material response under the complex thermomechanical loading conditions typical of power generation service. The approach adopted was to conduct a series of carefully controlled thermomechanical experiments on a nickel-based superalloy, Hastelloy Alloy X. Previous investigations had shown that this material experiences metallurgical instabilities leading to complex hardening behavior, termed dynamic strain aging. Investigating this phenomenon under full thermomechanical conditions leads to a number of challenging experimental difficulties which up to the present work were unresolved. To correct this situation, a number of advances were made in thermomechanical testing techniques. Advanced methods for dynamic temperature gradient control, phasing control and thermal strain compensation were developed and incorporated into real time test control software. These advances allowed the thermomechanical data to be analyzed with minimal experimental uncertainty. The thermomechanical results were evaluated on both a phenomenological and microstructural basis. Phenomenological results revealed that the thermomechanical hardening trends were not bounded by those displayed under isothermal conditions. For the case of Hastelloy Alloy X (and similar dynamic strain aging materials), this strongly suggests that some form of thermomechanical testing is necessary when characterizing a thermoviscoplastic deformation model. Transmission electron microscopy was used to study the microstructural physics, and analyze the unique phenomenological behavior.

Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis

PubMed Central

Wolfram, Christopher J.; Rubloff, Gary W.; Luo, Xiaolong

2016-01-01

Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradient-generating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, non-flowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication. PMID:27917249

Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis.

PubMed

Wolfram, Christopher J; Rubloff, Gary W; Luo, Xiaolong

2016-11-01

Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradient-generating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, non-flowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication.

Experimental Characterization of a Grid-Loss Event on a 2.5-MW Dynamometer Using Advanced Operational Modal Analysis: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Helsen, J.; Weijtjens, W.; Guo, Y.

2015-02-01

This paper experimentally investigates a worst case grid loss event conducted on the National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) drivetrain mounted on the 2.5MW NREL dynamic nacelle test-rig. The GRC drivetrain has a directly grid-coupled, fixed speed asynchronous generator. The main goal is the assessment of the dynamic content driving this particular assess the dynamic content of the high-speed stage of the GRC gearbox. In addition to external accelerometers, high frequency sampled measurements of strain gauges were used to assess torque fluctuations and bending moments both at the nacelle main shaft and gearbox high-speed shaft (HSS) throughmore » the entire duration of the event. Modal analysis was conducted using a polyreference Least Squares Complex Frequency-domain (pLSCF) modal identification estimator. The event driving the torsional resonance was identified. Moreover, the pLSCF estimator identified main drivetrain resonances based on a combination of acceleration and strain measurements. Without external action during the grid-loss event, a mode shape characterized by counter phase rotation of the rotor and generator rotor determined by the drivetrain flexibility and rotor inertias was the main driver of the event. This behavior resulted in significant torque oscillations with large amplitude negative torque periods. Based on tooth strain measurements of the HSS pinion, this work showed that at each zero-crossing, the teeth lost contact and came into contact with the backside flank. In addition, dynamic nontorque loads between the gearbox and generator at the HSS played an important role, as indicated by strain gauge-measurements.« less

Recognition without identification, erroneous familiarity, and déjà vu.

PubMed

O'Connor, Akira R; Moulin, Chris J A

2010-06-01

Déjà vu is characterized by the recognition of a situation concurrent with the awareness that this recognition is inappropriate. Although forms of déjà vu resolve in favor of the inappropriate recognition and therefore have behavioral consequences, typical déjà vu experiences resolve in favor of the awareness that the sensation of recognition is inappropriate. The resultant lack of behavioral modification associated with typical déjà vu means that clinicians and experimenters rely heavily on self-report when observing the experience. In this review, we focus on recent déjà vu research. We consider issues facing neuropsychological, neuroscientific, and cognitive experimental frameworks attempting to explore and experimentally generate the experience. In doing this, we suggest the need for more experimentation and a more cautious interpretation of research findings, particularly as many techniques being used to explore déjà vu are in the early stages of development.

Thermal functionalization of GaN surfaces with 1-alkenes.

PubMed

Schwarz, Stefan U; Cimalla, Volker; Eichapfel, Georg; Himmerlich, Marcel; Krischok, Stefan; Ambacher, Oliver

2013-05-28

A thermally induced functionalization process for gallium nitride surfaces with 1-alkenes is introduced. The resulting functionalization layers are characterized with atomic force microscopy and X-ray photoelectron spectroscopy and compared to reference samples without and with a photochemically generated functionalization layer. The resulting layers show very promising characteristics as functionalization for GaN based biosensors. On the basis of the experimental results, important characteristics of the functionalization layers are estimated and a possible chemical reaction scheme is proposed.

Long-Term Production and Delivery of Human Growth Hormone In vivo

NASA Astrophysics Data System (ADS)

Heartlein, Michael W.; Roman, Victoria A.; Jiang, Ji-Lei; Sellers, Joan W.; Zuliani, Antoinette M.; Treco, Douglas A.; Selden, Richard F.

1994-11-01

The application of somatic cell gene therapy to large patient populations will require the development of safe and practical approaches to the generation and characterization of genetically manipulated cells. Transkaryotic implantation is a gene therapy system based on the production of clonal strains of engineered primary and secondary cells, using nonviral methods. We demonstrate here that, on implantation, these clonal cell strains stably and reproducibly deliver pharmacologic quantities of protein for the lifetime of the experimental animals.

Critical threshold behavior for steady-state internal transport barriers in burning plasmas.

PubMed

García, J; Giruzzi, G; Artaud, J F; Basiuk, V; Decker, J; Imbeaux, F; Peysson, Y; Schneider, M

2008-06-27

Burning tokamak plasmas with internal transport barriers are investigated by means of integrated modeling simulations. The barrier sustainment in steady state, differently from the barrier formation process, is found to be characterized by a critical behavior, and the critical number of the phase transition is determined. Beyond a power threshold, alignment of self-generated and noninductively driven currents occurs and steady state becomes possible. This concept is applied to simulate a steady-state scenario within the specifications of the International Thermonuclear Experimental Reactor.

Frequency steerable acoustic transducers

NASA Astrophysics Data System (ADS)

Senesi, Matteo

Structural health monitoring (SHM) is an active research area devoted to the assessment of the structural integrity of critical components of aerospace, civil and mechanical systems. Guided wave methods have been proposed for SHM of plate-like structures using permanently attached piezoelectric transducers, which generate and sense waves to evaluate the presence of damage. Effective interrogation of structural health is often facilitated by sensors and actuators with the ability to perform electronic, i.e. phased array, scanning. The objective of this research is to design an innovative directional piezoelectric transducer to be employed for the localization of broadband acoustic events, or for the generation of Lamb waves for active interrogation of structural health. The proposed Frequency Steerable Acoustic Transducers (FSATs) are characterized by a spatial arrangement of active material which leads to directional characteristics varying with frequency. Thus FSATs can be employed both for directional sensing and generation of guided waves without relying on phasing and control of a large number of channels. The analytical expression of the shape of the FSATs is obtained through a theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. The FSAT configurations analyzed in this work are a quadrilateral array and a geometry which corresponds to a spiral in the wavenumber domain. The quadrilateral array is experimentally validated, confirming the concept of frequency-dependent directionality. Its limited directivity is improved by the Wavenumber Spiral FSAT (WS-FSAT), which, instead, is characterized by a continuous frequency dependent directionality. Preliminary validations of the WS-FSAT, using a laser doppler vibrometer, are followed by the implementation of the WS-FSAT as a properly shaped piezo transducer. The prototype is first used for localization of acoustic broadband sources. Signal processing algorithms and related imaging techniques for damage location are also presented. Finally, the WS-FSAT has also been experimentally validated in generation.

Scaled CMOS Technology Reliability Users Guide

NASA Technical Reports Server (NTRS)

White, Mark

2010-01-01

The desire to assess the reliability of emerging scaled microelectronics technologies through faster reliability trials and more accurate acceleration models is the precursor for further research and experimentation in this relevant field. The effect of semiconductor scaling on microelectronics product reliability is an important aspect to the high reliability application user. From the perspective of a customer or user, who in many cases must deal with very limited, if any, manufacturer's reliability data to assess the product for a highly-reliable application, product-level testing is critical in the characterization and reliability assessment of advanced nanometer semiconductor scaling effects on microelectronics reliability. A methodology on how to accomplish this and techniques for deriving the expected product-level reliability on commercial memory products are provided.Competing mechanism theory and the multiple failure mechanism model are applied to the experimental results of scaled SDRAM products. Accelerated stress testing at multiple conditions is applied at the product level of several scaled memory products to assess the performance degradation and product reliability. Acceleration models are derived for each case. For several scaled SDRAM products, retention time degradation is studied and two distinct soft error populations are observed with each technology generation: early breakdown, characterized by randomly distributed weak bits with Weibull slope (beta)=1, and a main population breakdown with an increasing failure rate. Retention time soft error rates are calculated and a multiple failure mechanism acceleration model with parameters is derived for each technology. Defect densities are calculated and reflect a decreasing trend in the percentage of random defective bits for each successive product generation. A normalized soft error failure rate of the memory data retention time in FIT/Gb and FIT/cm2 for several scaled SDRAM generations is presented revealing a power relationship. General models describing the soft error rates across scaled product generations are presented. The analysis methodology may be applied to other scaled microelectronic products and their key parameters.

[Rationalities of knowledge production: on transformations of objects, technologies and information in biomedicine and the life sciences].

PubMed

Paul, Norbert W

2009-09-01

Since decades, scientific change has been interpreted in the light of paradigm shifts and scientific revolutions. The Kuhnian interpretation of scientific change however is now more and more confronted with non-disciplinary thinking in both, science and studies on science. This paper explores how research in biomedicine and the life sciences can be characterized by different rationalities, sometimes converging, sometimes contradictory, all present at the same time with varying ways of influence, impact, and visibility. In general, the rationality of objects is generated by fitting new objects and findings into a new experimental context. The rationality of hypotheses is a move towards the construction of novel explanatory tools and models. This is often inseparable meshing with the third, the technological rationality, in which a technology-driven, self-supporting and sometimes self-referential refinement of methods and technologies comes along with an extension into other fields. During the second and the third phase, the new and emerging fields tend to expand their explanatory reach not only across disciplinary boundaries but also into the social sphere, creating what has been characterized as "exceptionalism" (e.g. genetic exceptionalism or neuro-exceptionalism). Finally, recent biomedicine and life-sciences reach a level in which experimental work becomes more and more data-driven because the technologically constructed experimental systems generate a plethora of findings (data) which at some point start to blur the original hypotheses. For the rationality of information the materiality of research practices becomes secondary and research objects are more and more getting out of sight. Finally, the credibility of science as a practice becomes more and more dependent on consensus about the applicability and relevance of its results. The rationality of interest (and accountability) has become more and more characteristic for a research process which is no longer primarily determined by the desire for knowledge but by the desire for relevance. This paper explores in which ways object-driven and hypotheses-driven experimental life-sciences transformed into domains of experimental research evolving in a technologically constructed, data-driven environment in which they are subjected to constant morphing due to the forces of different rationalities.

Analytical modelling of Halbach linear generator incorporating pole shifting and piece-wise spring for ocean wave energy harvesting

NASA Astrophysics Data System (ADS)

Tan, Yimin; Lin, Kejian; Zu, Jean W.

2018-05-01

Halbach permanent magnet (PM) array has attracted tremendous research attention in the development of electromagnetic generators for its unique properties. This paper has proposed a generalized analytical model for linear generators. The slotted stator pole-shifting and implementation of Halbach array have been combined for the first time. Initially, the magnetization components of the Halbach array have been determined using Fourier decomposition. Then, based on the magnetic scalar potential method, the magnetic field distribution has been derived employing specially treated boundary conditions. FEM analysis has been conducted to verify the analytical model. A slotted linear PM generator with Halbach PM has been constructed to validate the model and further improved using piece-wise springs to trigger full range reciprocating motion. A dynamic model has been developed to characterize the dynamic behavior of the slider. This analytical method provides an effective tool in development and optimization of Halbach PM generator. The experimental results indicate that piece-wise springs can be employed to improve generator performance under low excitation frequency.

Fabrication and Characterization of CMOS-MEMS Thermoelectric Micro Generators

PubMed Central

Kao, Pin-Hsu; Shih, Po-Jen; Dai, Ching-Liang; Liu, Mao-Chen

2010-01-01

This work presents a thermoelectric micro generator fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-CMOS process. The micro generator is composed of 24 thermocouples in series. Each thermocouple is constructed by p-type and n-type polysilicon strips. The output power of the generator depends on the temperature difference between the hot and cold parts in the thermocouples. In order to prevent heat-receiving in the cold part in the thermocouples, the cold part is covered with a silicon dioxide layer with low thermal conductivity to insulate the heat source. The hot part of the thermocouples is suspended and connected to an aluminum plate, to increases the heat-receiving area in the hot part. The generator requires a post-CMOS process to release the suspended structures. The post-CMOS process uses an anisotropic dry etching to remove the oxide sacrificial layer and an isotropic dry etching to etch the silicon substrate. Experimental results show that the micro generator has an output voltage of 67 μV at the temperature difference of 1 K. PMID:22205869

A simplified approach to characterizing a kilovoltage source spectrum for accurate dose computation.

PubMed

Poirier, Yannick; Kouznetsov, Alexei; Tambasco, Mauro

2012-06-01

To investigate and validate the clinical feasibility of using half-value layer (HVL) and peak tube potential (kVp) for characterizing a kilovoltage (kV) source spectrum for the purpose of computing kV x-ray dose accrued from imaging procedures. To use this approach to characterize a Varian® On-Board Imager® (OBI) source and perform experimental validation of a novel in-house hybrid dose computation algorithm for kV x-rays. We characterized the spectrum of an imaging kV x-ray source using the HVL and the kVp as the sole beam quality identifiers using third-party freeware Spektr to generate the spectra. We studied the sensitivity of our dose computation algorithm to uncertainties in the beam's HVL and kVp by systematically varying these spectral parameters. To validate our approach experimentally, we characterized the spectrum of a Varian® OBI system by measuring the HVL using a Farmer-type Capintec ion chamber (0.06 cc) in air and compared dose calculations using our computationally validated in-house kV dose calculation code to measured percent depth-dose and transverse dose profiles for 80, 100, and 125 kVp open beams in a homogeneous phantom and a heterogeneous phantom comprising tissue, lung, and bone equivalent materials. The sensitivity analysis of the beam quality parameters (i.e., HVL, kVp, and field size) on dose computation accuracy shows that typical measurement uncertainties in the HVL and kVp (±0.2 mm Al and ±2 kVp, respectively) source characterization parameters lead to dose computation errors of less than 2%. Furthermore, for an open beam with no added filtration, HVL variations affect dose computation accuracy by less than 1% for a 125 kVp beam when field size is varied from 5 × 5 cm(2) to 40 × 40 cm(2). The central axis depth dose calculations and experimental measurements for the 80, 100, and 125 kVp energies agreed within 2% for the homogeneous and heterogeneous block phantoms, and agreement for the transverse dose profiles was within 6%. The HVL and kVp are sufficient for characterizing a kV x-ray source spectrum for accurate dose computation. As these parameters can be easily and accurately measured, they provide for a clinically feasible approach to characterizing a kV energy spectrum to be used for patient specific x-ray dose computations. Furthermore, these results provide experimental validation of our novel hybrid dose computation algorithm. © 2012 American Association of Physicists in Medicine.

Combinatorial and high-throughput screening of materials libraries: review of state of the art.

PubMed

Potyrailo, Radislav; Rajan, Krishna; Stoewe, Klaus; Takeuchi, Ichiro; Chisholm, Bret; Lam, Hubert

2011-11-14

Rational materials design based on prior knowledge is attractive because it promises to avoid time-consuming synthesis and testing of numerous materials candidates. However with the increase of complexity of materials, the scientific ability for the rational materials design becomes progressively limited. As a result of this complexity, combinatorial and high-throughput (CHT) experimentation in materials science has been recognized as a new scientific approach to generate new knowledge. This review demonstrates the broad applicability of CHT experimentation technologies in discovery and optimization of new materials. We discuss general principles of CHT materials screening, followed by the detailed discussion of high-throughput materials characterization approaches, advances in data analysis/mining, and new materials developments facilitated by CHT experimentation. We critically analyze results of materials development in the areas most impacted by the CHT approaches, such as catalysis, electronic and functional materials, polymer-based industrial coatings, sensing materials, and biomaterials.

Activity-dependent self-regulation of viscous length scales in biological systems

NASA Astrophysics Data System (ADS)

Nandi, Saroj Kumar

2018-05-01

The cellular cortex, which is a highly viscous thin cytoplasmic layer just below the cell membrane, controls the cell's mechanical properties, which can be characterized by a hydrodynamic length scale ℓ . Cells actively regulate ℓ via the activity of force-generating molecules, such as myosin II. Here we develop a general theory for such systems through a coarse-grained hydrodynamic approach including activity in the static description of the system providing an experimentally accessible parameter and elucidate the detailed mechanism of how a living system can actively self-regulate its hydrodynamic length scale, controlling the rigidity of the system. Remarkably, we find that ℓ , as a function of activity, behaves universally and roughly inversely proportional to the activity of the system. Our theory rationalizes a number of experimental findings on diverse systems, and comparison of our theory with existing experimental data shows good agreement.

Experimental evidence of quantum radiation reaction in aligned crystals.

PubMed

Wistisen, Tobias N; Di Piazza, Antonino; Knudsen, Helge V; Uggerhøj, Ulrik I

2018-02-23

Quantum radiation reaction is the influence of multiple photon emissions from a charged particle on the particle's dynamics, characterized by a significant energy-momentum loss per emission. Here we report experimental radiation emission spectra from ultrarelativistic positrons in silicon in a regime where quantum radiation reaction effects dominate the positron's dynamics. Our analysis shows that while the widely used quantum approach is overall the best model, it does not completely describe all the data in this regime. Thus, these experimental findings may prompt seeking more generally valid methods to describe quantum radiation reaction. This experiment is a fundamental test of quantum electrodynamics in a regime where the dynamics of charged particles is strongly influenced not only by the external electromagnetic fields but also by the radiation field generated by the charges themselves and where each photon emission may significantly reduce the energy of the charge.

Theoretical predictor for candidate structure assignment from IMS data of biomolecule-related conformational space.

PubMed

Schenk, Emily R; Nau, Frederic; Fernandez-Lima, Francisco

2015-06-01

The ability to correlate experimental ion mobility data with candidate structures from theoretical modeling provides a powerful analytical and structural tool for the characterization of biomolecules. In the present paper, a theoretical workflow is described to generate and assign candidate structures for experimental trapped ion mobility and H/D exchange (HDX-TIMS-MS) data following molecular dynamics simulations and statistical filtering. The applicability of the theoretical predictor is illustrated for a peptide and protein example with multiple conformations and kinetic intermediates. The described methodology yields a low computational cost and a simple workflow by incorporating statistical filtering and molecular dynamics simulations. The workflow can be adapted to different IMS scenarios and CCS calculators for a more accurate description of the IMS experimental conditions. For the case of the HDX-TIMS-MS experiments, molecular dynamics in the "TIMS box" accounts for a better sampling of the molecular intermediates and local energy minima.

Structuring Stokes correlation functions using vector-vortex beam

NASA Astrophysics Data System (ADS)

Kumar, Vijay; Anwar, Ali; Singh, R. P.

2018-01-01

Higher order statistical correlations of the optical vector speckle field, formed due to scattering of a vector-vortex beam, are explored. Here, we report on the experimental construction of the Stokes parameters covariance matrix, consisting of all possible spatial Stokes parameters correlation functions. We also propose and experimentally realize a new Stokes correlation functions called Stokes field auto correlation functions. It is observed that the Stokes correlation functions of the vector-vortex beam will be reflected in the respective Stokes correlation functions of the corresponding vector speckle field. The major advantage of proposing Stokes correlation functions is that the Stokes correlation function can be easily tuned by manipulating the polarization of vector-vortex beam used to generate vector speckle field and to get the phase information directly from the intensity measurements. Moreover, this approach leads to a complete experimental Stokes characterization of a broad range of random fields.

Experimental investigation of a four-qubit linear-optical quantum logic circuit

PubMed Central

Stárek, R.; Mičuda, M.; Miková, M.; Straka, I.; Dušek, M.; Ježek, M.; Fiurášek, J.

2016-01-01

We experimentally demonstrate and characterize a four-qubit linear-optical quantum logic circuit. Our robust and versatile scheme exploits encoding of two qubits into polarization and path degrees of single photons and involves two crossed inherently stable interferometers. This approach allows us to design a complex quantum logic circuit that combines a genuine four-qubit C3Z gate and several two-qubit and single-qubit gates. The C3Z gate introduces a sign flip if and only if all four qubits are in the computational state |1〉. We verify high-fidelity performance of this central four-qubit gate using Hofmann bounds on quantum gate fidelity and Monte Carlo fidelity sampling. We also experimentally demonstrate that the quantum logic circuit can generate genuine multipartite entanglement and we certify the entanglement with the use of suitably tailored entanglement witnesses. PMID:27647176

Quantification of ultrasonic texture intra-heterogeneity via volumetric stochastic modeling for tissue characterization.

PubMed

Al-Kadi, Omar S; Chung, Daniel Y F; Carlisle, Robert C; Coussios, Constantin C; Noble, J Alison

2015-04-01

Intensity variations in image texture can provide powerful quantitative information about physical properties of biological tissue. However, tissue patterns can vary according to the utilized imaging system and are intrinsically correlated to the scale of analysis. In the case of ultrasound, the Nakagami distribution is a general model of the ultrasonic backscattering envelope under various scattering conditions and densities where it can be employed for characterizing image texture, but the subtle intra-heterogeneities within a given mass are difficult to capture via this model as it works at a single spatial scale. This paper proposes a locally adaptive 3D multi-resolution Nakagami-based fractal feature descriptor that extends Nakagami-based texture analysis to accommodate subtle speckle spatial frequency tissue intensity variability in volumetric scans. Local textural fractal descriptors - which are invariant to affine intensity changes - are extracted from volumetric patches at different spatial resolutions from voxel lattice-based generated shape and scale Nakagami parameters. Using ultrasound radio-frequency datasets we found that after applying an adaptive fractal decomposition label transfer approach on top of the generated Nakagami voxels, tissue characterization results were superior to the state of art. Experimental results on real 3D ultrasonic pre-clinical and clinical datasets suggest that describing tumor intra-heterogeneity via this descriptor may facilitate improved prediction of therapy response and disease characterization. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Noise Characteristics of a Four-Jet Impingement Device Inside a Broadband Engine Noise Simulator

NASA Technical Reports Server (NTRS)

Brehm, Christoph; Housman, Jeffrey A.; Kiris, Cetin C.; Hutcheson, Florence V.

2015-01-01

The noise generation mechanisms for four directly impinging supersonic jets are investigated employing implicit large eddy simulations with a higher-order accurate weighted essentially non-oscillatory shock-capturing scheme. Impinging jet devices are often used as an experimental apparatus to emulate a broadband noise source. Although such devices have been used in many experiments, a detailed investigation of the noise generation mechanisms has not been conducted before. Thus, the underlying physical mechanisms that are responsible for the generation of sound waves are not well understood. The flow field is highly complex and contains a wide range of temporal and spatial scales relevant for noise generation. Proper orthogonal decomposition of the flow field is utilized to characterize the unsteady nature of the flow field involving unsteady shock oscillations, large coherent turbulent flow structures, and the sporadic appearance of vortex tubes in the center of the impingement region. The causality method based on Lighthill's acoustic analogy is applied to link fluctuations of flow quantities inside the source region to the acoustic pressure in the far field. It will be demonstrated that the entropy fluctuation term in the Lighthill's stress tensor plays a vital role in the noise generation process. Consequently, the understanding of the noise generation mechanisms is employed to develop a reduced-order linear acoustic model of the four-jet impingement device. Finally, three linear acoustic FJID models are used as broadband noise sources inside an engine nacelle and the acoustic scattering results are validated against far-field acoustic experimental data.

Plasma Liner Development for MTF Applications: A Status Report

NASA Technical Reports Server (NTRS)

Eskridge, R. E.; Thio, Y. F.; Lee, M.; Martin, A.; Smith, J. W.; Griffin, S. T.; Schafer, Charles (Technical Monitor)

2001-01-01

An experimental plasma gun for Magnetic Target Fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. This gun has been tested experimentally and plasma jet velocities of approximately 50 km/sec have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter has been characterized and future work for second generation "ultra-low jitter" gun development is identified.

Background feature descriptor for offline handwritten numeral recognition

NASA Astrophysics Data System (ADS)

Ming, Delie; Wang, Hao; Tian, Tian; Jie, Feiran; Lei, Bo

2011-11-01

This paper puts forward an offline handwritten numeral recognition method based on background structural descriptor (sixteen-value numerical background expression). Through encoding the background pixels in the image according to a certain rule, 16 different eigenvalues were generated, which reflected the background condition of every digit, then reflected the structural features of the digits. Through pattern language description of images by these features, automatic segmentation of overlapping digits and numeral recognition can be realized. This method is characterized by great deformation resistant ability, high recognition speed and easy realization. Finally, the experimental results and conclusions are presented. The experimental results of recognizing datasets from various practical application fields reflect that with this method, a good recognition effect can be achieved.

Nonlinear characterization of a single-axis acoustic levitator.

PubMed

Andrade, Marco A B; Ramos, Tiago S; Okina, Fábio T A; Adamowski, Julio C

2014-04-01

The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.

A comparative study of experimental and simulated ultrasonic pulse-echo signals from multilayered structures

NASA Technical Reports Server (NTRS)

Abedin, M. N.; Prabhu, D. R.; Winfree, W. P.; Johnston, P. H.

1992-01-01

The effect on the system acoustic response of variations in the adhesive thickness, coupling thickness, and paint thickness is considered. Both simulations and experimental measurements are used to characterize and classify A-scans from test regions, and to study the effects of various parameters such as paint thickness and epoxy thickness on the variations in the reflected signals. A 1D model of sound propagation in multilayered structures is used to verify the validity of the measured signals, and is also used to computationally generate signals for a class of test locations with gradually varying parameters. This approach exploits the ability of numerical simulations to provide a good understanding of the ultrasonic pulses reflected at disbonds.

Complementary Speckle Patterns: Deterministic Interchange of Intrinsic Vortices and Maxima through Scattering Media.

PubMed

Gateau, Jérôme; Rigneault, Hervé; Guillon, Marc

2017-01-27

Intensity maxima and zeros of speckle patterns obtained behind a diffuser are experimentally interchanged by applying a spiral phase delay of charge ±1 to the impinging coherent beam. This transform arises from the expectation that tightly focused beams, which have a planar wave front around the focus, are so changed into vortex beams and vice versa. The statistics of extrema locations and the intensity distribution of the so-generated "complementary" patterns are characterized by numerical simulations. It is demonstrated experimentally that the incoherent superposition of the three "complementary speckle patterns" yield a synthetic speckle grain size enlarged by a factor of sqrt[3]. A cyclic permutation of optical vortices and intensity maxima is unexpectedly observed and discussed.

Nonlinear characterization of a single-axis acoustic levitator

NASA Astrophysics Data System (ADS)

Andrade, Marco A. B.; Ramos, Tiago S.; Okina, Fábio T. A.; Adamowski, Julio C.

2014-04-01

The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jump phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.

Experimental Flight Characterization of Spin Stabilized Projectiles at High Angle of Attack

DTIC Science & Technology

2017-08-07

ARL-TR-8082 ● AUG 2017 US Army Research Laboratory Experimental Flight Characterization of Spin- Stabilized Projectiles at High ...Experimental Flight Characterization of Spin- Stabilized Projectiles at High Angle of Attack by Frank Fresconi and Ilmars Celmins Weapons and Materials...June 2016–June 2017 4. TITLE AND SUBTITLE Experimental Flight Characterization of Spin-Stabilized Projectiles at High Angle of Attack 5a. CONTRACT

Experimental Investigation of Jet Impingement Heat Transfer Using Thermochromic Liquid Crystals

NASA Technical Reports Server (NTRS)

Dempsey, Brian Paul

1997-01-01

Jet impingement cooling of a hypersonic airfoil leading edge is experimentally investigated using thermochromic liquid crystals (TLCS) to measure surface temperature. The experiment uses computer data acquisition with digital imaging of the TLCs to determine heat transfer coefficients during a transient experiment. The data reduction relies on analysis of a coupled transient conduction - convection heat transfer problem that characterizes the experiment. The recovery temperature of the jet is accounted for by running two experiments with different heating rates, thereby generating a second equation that is used to solve for the recovery temperature. The resulting solution requires a complicated numerical iteration that is handled by a computer. Because the computational data reduction method is complex, special attention is paid to error assessment. The error analysis considers random and systematic errors generated by the instrumentation along with errors generated by the approximate nature of the numerical methods. Results of the error analysis show that the experimentally determined heat transfer coefficients are accurate to within 15%. The error analysis also shows that the recovery temperature data may be in error by more than 50%. The results show that the recovery temperature data is only reliable when the recovery temperature of the jet is greater than 5 C, i.e. the jet velocity is in excess of 100 m/s. Parameters that were investigated include nozzle width, distance from the nozzle exit to the airfoil surface, and jet velocity. Heat transfer data is presented in graphical and tabular forms. An engineering analysis of hypersonic airfoil leading edge cooling is performed using the results from these experiments. Several suggestions for the improvement of the experimental technique are discussed.

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

PubMed Central

Smits, Kathleen; Eagen, Victoria; Trautz, Andrew

2015-01-01

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages. PMID:26131928

Organic/inorganic-doped aromatic derivative crystals: Growth and properties

NASA Astrophysics Data System (ADS)

Stanculescu, F.; Ionita, I.; Stanculescu, A.

2014-09-01

Results of a comparative study on the growth from melt by the Bridgman-Stockbarger method of meta-dinitrobenzene (m-DNB) and benzil (Bz) crystals in the same experimental set-up and the same experimental conditions are presented. The incorporation of an inorganic (iodine) dopant in m-DNB was analyzed in the given experimental conditions from the point of view of the solid-liquid interface stability. The limits for a stable growth and the conditions that favor the generation of morphological instability are emphasized. These limits for m-DNB are compatible with those previously determined for Bz, and therefore, even for a high gradient concentration at the growth interface, it is possible to grow m-DNB and Bz crystals in the same experimental conditions characterized by a high ΔT and v. The optical properties were investigated in relation with the dopant incorporation in the crystal in the mentioned experimental conditions. Effects of the dopant (m-DNB/iodine in Bz and iodine in m-DNB) on the optical band gap and optical non-linear properties of the crystals are discussed.

Docking-based modeling of protein-protein interfaces for extensive structural and functional characterization of missense mutations.

PubMed

Barradas-Bautista, Didier; Fernández-Recio, Juan

2017-01-01

Next-generation sequencing (NGS) technologies are providing genomic information for an increasing number of healthy individuals and patient populations. In the context of the large amount of generated genomic data that is being generated, understanding the effect of disease-related mutations at molecular level can contribute to close the gap between genotype and phenotype and thus improve prevention, diagnosis or treatment of a pathological condition. In order to fully characterize the effect of a pathological mutation and have useful information for prediction purposes, it is important first to identify whether the mutation is located at a protein-binding interface, and second to understand the effect on the binding affinity of the affected interaction/s. Computational methods, such as protein docking are currently used to complement experimental efforts and could help to build the human structural interactome. Here we have extended the original pyDockNIP method to predict the location of disease-associated nsSNPs at protein-protein interfaces, when there is no available structure for the protein-protein complex. We have applied this approach to the pathological interaction networks of six diseases with low structural data on PPIs. This approach can almost double the number of nsSNPs that can be characterized and identify edgetic effects in many nsSNPs that were previously unknown. This can help to annotate and interpret genomic data from large-scale population studies, and to achieve a better understanding of disease at molecular level.

Docking-based modeling of protein-protein interfaces for extensive structural and functional characterization of missense mutations

PubMed Central

2017-01-01

Next-generation sequencing (NGS) technologies are providing genomic information for an increasing number of healthy individuals and patient populations. In the context of the large amount of generated genomic data that is being generated, understanding the effect of disease-related mutations at molecular level can contribute to close the gap between genotype and phenotype and thus improve prevention, diagnosis or treatment of a pathological condition. In order to fully characterize the effect of a pathological mutation and have useful information for prediction purposes, it is important first to identify whether the mutation is located at a protein-binding interface, and second to understand the effect on the binding affinity of the affected interaction/s. Computational methods, such as protein docking are currently used to complement experimental efforts and could help to build the human structural interactome. Here we have extended the original pyDockNIP method to predict the location of disease-associated nsSNPs at protein-protein interfaces, when there is no available structure for the protein-protein complex. We have applied this approach to the pathological interaction networks of six diseases with low structural data on PPIs. This approach can almost double the number of nsSNPs that can be characterized and identify edgetic effects in many nsSNPs that were previously unknown. This can help to annotate and interpret genomic data from large-scale population studies, and to achieve a better understanding of disease at molecular level. PMID:28841721

Cryo-Infrared Optical Characterization at NASA GSFC

NASA Technical Reports Server (NTRS)

Boucarut, Ray; Quijada, Manuel A.; Henry, Ross M.

2004-01-01

The development of large space infrared optical systems, such as the Next Generation Space Telescope (NGST), has increased requirements for measurement accuracy in the optical properties of materials. Many materials used as optical components in infrared optical systems, have strong temperature dependence in their optical properties. Unfortunately, data on the temperature dependence of most of these materials is sparse. In this paper, we provide a description of the capabilities existing in the Optics Branch at the Goddard Space Flight Center that enable the characterization of the refractive index and absorption coefficient changes and other optical properties in infrared materials at cryogenic temperatures. Details of the experimental apparatus, which include continuous flow liquid helium optical cryostat, and a Fourier Transform Infrared (FTIR) spectrometer are discussed.

Experimental and Simulated Characterization of a Beam Shaping Assembly for Accelerator- Based Boron Neutron Capture Therapy (AB-BNCT)

NASA Astrophysics Data System (ADS)

Burlon, Alejandro A.; Girola, Santiago; Valda, Alejandro A.; Minsky, Daniel M.; Kreiner, Andrés J.

2010-08-01

In the frame of the construction of a Tandem Electrostatic Quadrupole Accelerator facility devoted to the Accelerator-Based Boron Neutron Capture Therapy, a Beam Shaping Assembly has been characterized by means of Monte-Carlo simulations and measurements. The neutrons were generated via the 7Li(p, n)7Be reaction by irradiating a thick LiF target with a 2.3 MeV proton beam delivered by the TANDAR accelerator at CNEA. The emerging neutron flux was measured by means of activation foils while the beam quality and directionality was evaluated by means of Monte Carlo simulations. The parameters show compliance with those suggested by IAEA. Finally, an improvement adding a beam collimator has been evaluated.

Silica nanoparticles produced by DC arc plasma from a solid raw materials

NASA Astrophysics Data System (ADS)

Kosmachev, P. V.; Vlasov, V. A.; Skripnikova, N. K.

2017-05-01

Plasma synthesis of SiO2 nanoparticles in experimental atmospheric pressure plasma reactor on the basis of DC arc plasma generator was presented in this paper. Solid high-silica raw materials such as diatomite from Kamyshlovskoye deposit in Russia, quartzite from Chupinskoye deposit in Russia and milled window glass were used. The obtained nanoparticles were characterized based on their morphology, chemical composition and size distribution. Scanning electron microscopy, laser diffractometry, nitrogen absorption (Brunauer-Emmett-Teller method), X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy were used to characterize the synthesized products. The obtained silica nanoparticles are agglomerated, have spherical shape and primary diameters between 10-300 nm. All samples of synthesized nanopowders were compared with commercial nanopowders.

Predicting network modules of cell cycle regulators using relative protein abundance statistics.

PubMed

Oguz, Cihan; Watson, Layne T; Baumann, William T; Tyson, John J

2017-02-28

Parameter estimation in systems biology is typically done by enforcing experimental observations through an objective function as the parameter space of a model is explored by numerical simulations. Past studies have shown that one usually finds a set of "feasible" parameter vectors that fit the available experimental data equally well, and that these alternative vectors can make different predictions under novel experimental conditions. In this study, we characterize the feasible region of a complex model of the budding yeast cell cycle under a large set of discrete experimental constraints in order to test whether the statistical features of relative protein abundance predictions are influenced by the topology of the cell cycle regulatory network. Using differential evolution, we generate an ensemble of feasible parameter vectors that reproduce the phenotypes (viable or inviable) of wild-type yeast cells and 110 mutant strains. We use this ensemble to predict the phenotypes of 129 mutant strains for which experimental data is not available. We identify 86 novel mutants that are predicted to be viable and then rank the cell cycle proteins in terms of their contributions to cumulative variability of relative protein abundance predictions. Proteins involved in "regulation of cell size" and "regulation of G1/S transition" contribute most to predictive variability, whereas proteins involved in "positive regulation of transcription involved in exit from mitosis," "mitotic spindle assembly checkpoint" and "negative regulation of cyclin-dependent protein kinase by cyclin degradation" contribute the least. These results suggest that the statistics of these predictions may be generating patterns specific to individual network modules (START, S/G2/M, and EXIT). To test this hypothesis, we develop random forest models for predicting the network modules of cell cycle regulators using relative abundance statistics as model inputs. Predictive performance is assessed by the areas under receiver operating characteristics curves (AUC). Our models generate an AUC range of 0.83-0.87 as opposed to randomized models with AUC values around 0.50. By using differential evolution and random forest modeling, we show that the model prediction statistics generate distinct network module-specific patterns within the cell cycle network.

Experimental study of strained and destrained turbulence

NASA Astrophysics Data System (ADS)

Chen, Jun; Meneveau, Charles; Katz, Joseph

2003-11-01

Planar Particle Image Velocimetry measurements are performed in a water tank facility in which high Reynolds number turbulence is generated by an array of spinning grids. Straining fields are applied using a piston with rectangular cross-section which is pushed towards the bottom of the tank, setting up a planar straining field there. The facility can also be used to reverse the distortion ("destraining'') by pulling the piston upwards. We present calibration tests characterizing the flow in the facility. The initial turbulent state is characterized by means of ditributions of rms values and energy spectra, and corresponds closely to isotropic, homogeneous turbulence. The applied straining is characterized using high-speed camera and PIV measurements of the mean flow without turbulence. Initial results of turbulence subjected to a sequence of straining and destraining motions are presented, with particular emphasis on the flux of kinetic energy from large to small scales and possible backscatter during destraining.

Interactive Sonification Exploring Emergent Behavior Applying Models for Biological Information and Listening

PubMed Central

Choi, Insook

2018-01-01

Sonification is an open-ended design task to construct sound informing a listener of data. Understanding application context is critical for shaping design requirements for data translation into sound. Sonification requires methodology to maintain reproducibility when data sources exhibit non-linear properties of self-organization and emergent behavior. This research formalizes interactive sonification in an extensible model to support reproducibility when data exhibits emergent behavior. In the absence of sonification theory, extensibility demonstrates relevant methods across case studies. The interactive sonification framework foregrounds three factors: reproducible system implementation for generating sonification; interactive mechanisms enhancing a listener's multisensory observations; and reproducible data from models that characterize emergent behavior. Supramodal attention research suggests interactive exploration with auditory feedback can generate context for recognizing irregular patterns and transient dynamics. The sonification framework provides circular causality as a signal pathway for modeling a listener interacting with emergent behavior. The extensible sonification model adopts a data acquisition pathway to formalize functional symmetry across three subsystems: Experimental Data Source, Sound Generation, and Guided Exploration. To differentiate time criticality and dimensionality of emerging dynamics, tuning functions are applied between subsystems to maintain scale and symmetry of concurrent processes and temporal dynamics. Tuning functions accommodate sonification design strategies that yield order parameter values to render emerging patterns discoverable as well as rehearsable, to reproduce desired instances for clinical listeners. Case studies are implemented with two computational models, Chua's circuit and Swarm Chemistry social agent simulation, generating data in real-time that exhibits emergent behavior. Heuristic Listening is introduced as an informal model of a listener's clinical attention to data sonification through multisensory interaction in a context of structured inquiry. Three methods are introduced to assess the proposed sonification framework: Listening Scenario classification, data flow Attunement, and Sonification Design Patterns to classify sound control. Case study implementations are assessed against these methods comparing levels of abstraction between experimental data and sound generation. Outcomes demonstrate the framework performance as a reference model for representing experimental implementations, also for identifying common sonification structures having different experimental implementations, identifying common functions implemented in different subsystems, and comparing impact of affordances across multiple implementations of listening scenarios. PMID:29755311

Self-Assembly Behavior of Amphiphilic Janus Dendrimers in Water: A Combined Experimental and Coarse-Grained Molecular Dynamics Simulation Approach.

PubMed

Elizondo-García, Mariana E; Márquez-Miranda, Valeria; Araya-Durán, Ingrid; Valencia-Gallegos, Jesús A; González-Nilo, Fernando D

2018-04-21

Amphiphilic Janus dendrimers (JDs) are repetitively branched molecules with hydrophilic and hydrophobic components that self-assemble in water to form a variety of morphologies, including vesicles analogous to liposomes with potential pharmaceutical and medical application. To date, the self-assembly of JDs has not been fully investigated thus it is important to gain insight into its mechanism and dependence on JDs’ molecular structure. In this study, the aggregation behavior in water of a second-generation bis-MPA JD was evaluated using experimental and computational methods. Dispersions of JDs in water were carried out using the thin-film hydration and ethanol injection methods. Resulting assemblies were characterized by dynamic light scattering, confocal microscopy, and atomic force microscopy. Furthermore, a coarse-grained molecular dynamics (CG-MD) simulation was performed to study the mechanism of JDs aggregation. The obtaining of assemblies in water with no interdigitated bilayers was confirmed by the experimental characterization and CG-MD simulation. Assemblies with dendrimersome characteristics were obtained using the ethanol injection method. The results of this study establish a relationship between the molecular structure of the JD and the properties of its aggregates in water. Thus, our findings could be relevant for the design of novel JDs with tailored assemblies suitable for drug delivery systems.

A new index for characterizing micro-bead motion in a flow induced by ciliary beating: Part I, experimental analysis.

PubMed

Bottier, Mathieu; Blanchon, Sylvain; Pelle, Gabriel; Bequignon, Emilie; Isabey, Daniel; Coste, André; Escudier, Estelle; Grotberg, James B; Papon, Jean-François; Filoche, Marcel; Louis, Bruno

2017-07-01

Mucociliary clearance is one of the major lines of defense of the respiratory system. The mucus layer coating the pulmonary airways is moved along and out of the lung by the activity of motile cilia, thus expelling the particles trapped in it. Here we compare ex vivo measurements of a Newtonian flow induced by cilia beating (using micro-beads as tracers) and a mathematical model of this fluid flow, presented in greater detail in a second companion article. Samples of nasal epithelial cells placed in water are recorded by high-speed video-microscopy and ciliary beat pattern is inferred. Automatic tracking of micro-beads, used as markers of the flow generated by cilia motion, enables us also to assess the velocity profile as a function of the distance above the cilia. This profile is shown to be essentially parabolic. The obtained experimental data are used to feed a 2D mathematical and numerical model of the coupling between cilia, fluid, and micro-bead motion. From the model and the experimental measurements, the shear stress exerted by the cilia is deduced. Finally, this shear stress, which can easily be measured in the clinical setting, is proposed as a new index for characterizing the efficiency of ciliary beating.

A new index for characterizing micro-bead motion in a flow induced by ciliary beating: Part I, experimental analysis

PubMed Central

Bottier, Mathieu; Blanchon, Sylvain; Pelle, Gabriel; Bequignon, Emilie; Coste, André; Escudier, Estelle; Grotberg, James B.; Papon, Jean-François

2017-01-01

Mucociliary clearance is one of the major lines of defense of the respiratory system. The mucus layer coating the pulmonary airways is moved along and out of the lung by the activity of motile cilia, thus expelling the particles trapped in it. Here we compare ex vivo measurements of a Newtonian flow induced by cilia beating (using micro-beads as tracers) and a mathematical model of this fluid flow, presented in greater detail in a second companion article. Samples of nasal epithelial cells placed in water are recorded by high-speed video-microscopy and ciliary beat pattern is inferred. Automatic tracking of micro-beads, used as markers of the flow generated by cilia motion, enables us also to assess the velocity profile as a function of the distance above the cilia. This profile is shown to be essentially parabolic. The obtained experimental data are used to feed a 2D mathematical and numerical model of the coupling between cilia, fluid, and micro-bead motion. From the model and the experimental measurements, the shear stress exerted by the cilia is deduced. Finally, this shear stress, which can easily be measured in the clinical setting, is proposed as a new index for characterizing the efficiency of ciliary beating. PMID:28708889

A fragile zero watermarking scheme to detect and characterize malicious modifications in database relations.

PubMed

Khan, Aihab; Husain, Syed Afaq

2013-01-01

We put forward a fragile zero watermarking scheme to detect and characterize malicious modifications made to a database relation. Most of the existing watermarking schemes for relational databases introduce intentional errors or permanent distortions as marks into the database original content. These distortions inevitably degrade the data quality and data usability as the integrity of a relational database is violated. Moreover, these fragile schemes can detect malicious data modifications but do not characterize the tempering attack, that is, the nature of tempering. The proposed fragile scheme is based on zero watermarking approach to detect malicious modifications made to a database relation. In zero watermarking, the watermark is generated (constructed) from the contents of the original data rather than introduction of permanent distortions as marks into the data. As a result, the proposed scheme is distortion-free; thus, it also resolves the inherent conflict between security and imperceptibility. The proposed scheme also characterizes the malicious data modifications to quantify the nature of tempering attacks. Experimental results show that even minor malicious modifications made to a database relation can be detected and characterized successfully.

Characterization of microwave plasma in a multicusp using 2D emission based tomography: Bessel modes and wave absorption

NASA Astrophysics Data System (ADS)

Rathore, Kavita; Bhattacharjee, Sudeep; Munshi, Prabhat

2017-06-01

A tomographic method based on the Fourier transform is used for characterizing a microwave plasma in a multicusp (MC), in order to obtain 2D distribution of plasma emissions, plasma (electron) density (Ne) and temperature (Te). The microwave plasma in the MC is characterized as a function of microwave power, gas pressure, and axial distance. The experimentally obtained 2D emission profiles show that the plasma emissions are generated in a circular ring shape. There are usually two bright rings, one at the plasma core and another near the boundary. The experimental results are validated using a numerical code that solves Maxwell's equations inside a waveguide filled with a plasma in a magnetic field, with collisions included. It is inferred that the dark and bright circular ring patterns are a result of superposition of Bessel modes (TE11 and TE21) of the wave electric field inside the plasma filled MC, which are in reasonable agreement with the plasma emission profiles. The tomographically obtained Ne and Te profiles indicate higher densities in the plasma core (˜1010 cm-3) and enhanced electron temperature in the ECR region (˜13 eV), which are in agreement with earlier results using a Langmuir probe and optical emission spectroscopy (OES) diagnostics.

Phase control of attosecond pulses in a train

NASA Astrophysics Data System (ADS)

Guo, Chen; Harth, Anne; Carlström, Stefanos; Cheng, Yu-Chen; Mikaelsson, Sara; Mårsell, Erik; Heyl, Christoph; Miranda, Miguel; Gisselbrecht, Mathieu; Gaarde, Mette B.; Schafer, Kenneth J.; Mikkelsen, Anders; Mauritsson, Johan; Arnold, Cord L.; L'Huillier, Anne

2018-02-01

Ultrafast processes in matter can be captured and even controlled by using sequences of few-cycle optical pulses, which need to be well characterized, both in amplitude and phase. The same degree of control has not yet been achieved for few-cycle extreme ultraviolet pulses generated by high-order harmonic generation (HHG) in gases, with duration in the attosecond range. Here, we show that by varying the spectral phase and carrier-envelope phase (CEP) of a high-repetition rate laser, using dispersion in glass, we achieve a high degree of control of the relative phase and CEP between consecutive attosecond pulses. The experimental results are supported by a detailed theoretical analysis based upon the semi-classical three-step model for HHG.

Coding for stable transmission of W-band radio-over-fiber system using direct-beating of two independent lasers.

PubMed

Yang, L G; Sung, J Y; Chow, C W; Yeh, C H; Cheng, K T; Shi, J W; Pan, C L

2014-10-20

We demonstrate experimentally Manchester (MC) coding based W-band (75 - 110 GHz) radio-over-fiber (ROF) system to reduce the low-frequency-components (LFCs) signal distortion generated by two independent low-cost lasers using spectral shaping. Hence, a low-cost and higher performance W-band ROF system is achieved. In this system, direct-beating of two independent low-cost CW lasers without frequency tracking circuit (FTC) is used to generate the millimeter-wave. Approaches, such as delayed self-heterodyne interferometer and heterodyne beating are performed to characterize the optical-beating-interference sub-terahertz signal (OBIS). Furthermore, W-band ROF systems using MC coding and NRZ-OOK are compared and discussed.

Development of an angle-scanning spectropolarimeter: Preliminary results

NASA Astrophysics Data System (ADS)

Nouri, Sahar A.; Gregory, Don A.; Fuller, Kirk

2018-02-01

A fixed-angle spectropolarimeter capable of measuring the Mueller matrix of particle deposits and conventional optical elements over the 300-1100 nm spectral range has been built, calibrated and extensively tested. A second generation of this instrument is being built which can scan from 0° to near 180° in both scattering angle and sample orientation, enabling studies of the bidirectional Mueller matrices of nanoparticle arrays, atmospheric aerosol deposits, and nano- and microstructured surfaces. This system will also provide a much needed metrology capability for fully characterizing the performance of optical devices and device components from the near-infrared through the medium wave ultraviolet. Experimental results taken using the first generation fixed-angle arrangement will be presented along with the rationale for building the second.

Generation of the Ares I-X Flight Test Vehicle Aerodynamic Data Book and Comparison To Flight

NASA Technical Reports Server (NTRS)

Bauer, Steven X.; Krist, Steven E.; Compton, William B.

2011-01-01

A 3.5-year effort to characterize the aerodynamic behavior of the Ares I-X Flight Test Vehicle (AIX FTV) is described in this paper. The AIX FTV was designed to be representative of the Ares I Crew Launch Vehicle (CLV). While there are several differences in the outer mold line from the current revision of the CLV, the overall length, mass distribution, and flight systems of the two vehicles are very similar. This paper briefly touches on each of the aerodynamic databases developed in the program, describing the methodology employed, experimental and computational contributions to the generation of the databases, and how well the databases and underlying computations compare to actual flight test results.

Characterization of Aerosols of Titanium Dioxide Nanoparticles Following Three Generation Methods Using an Optimized Aerosolization System Designed for Experimental Inhalation Studies

PubMed Central

Pujalté, Igor; Serventi, Alessandra; Noël, Alexandra; Dieme, Denis; Haddad, Sami; Bouchard, Michèle

2017-01-01

Nanoparticles (NPs) can be released in the air in work settings, but various factors influence the exposure of workers. Controlled inhalation experiments can thus be conducted in an attempt to reproduce real-life exposure conditions and assess inhalation toxicology. Methods exist to generate aerosols, but it remains difficult to obtain nano-sized and stable aerosols suitable for inhalation experiments. The goal of this work was to characterize aerosols of titanium dioxide (TiO2) NPs, generated using a novel inhalation system equipped with three types of generators—a wet collision jet nebulizer, a dry dust jet and an electrospray aerosolizer—with the aim of producing stable aerosols with a nano-diameter average (<100 nm) and monodispersed distribution for future rodent exposures and toxicological studies. Results showed the ability of the three generation systems to provide good and stable dispersions of NPs, applicable for acute (continuous up to 8 h) and repeated (21-day) exposures. In all cases, the generated aerosols were composed mainly of small aggregates/agglomerates (average diameter <100 nm) with the electrospray producing the finest (average diameter of 70–75 mm) and least concentrated aerosols (between 0.150 and 2.5 mg/m3). The dust jet was able to produce concentrations varying from 1.5 to 150 mg/m3, and hence, the most highly concentrated aerosols. The nebulizer collision jet aerosolizer was the most versatile generator, producing both low (0.5 mg/m3) and relatively high concentrations (30 mg/m3). The three optimized generators appeared suited for possible toxicological studies of inhaled NPs. PMID:29051446

Connecting Time and Frequency in the RC Circuit

NASA Astrophysics Data System (ADS)

Moya, A. A.

2017-04-01

Charging and discharging processes of a capacitor through a resistor, as well as the concept of impedance in alternating current circuits, are topics covered in introductory physics courses. The experimental study of the charge and discharge of a capacitor through a resistor is a well-established lab exercise that is used to introduce concepts such as exponential increase or decrease and time constant. Determining the time constant of the RC circuit has important practical applications because, for example, it can be used to measure unknown values of resistance or capacitance. The transient experiment can be done by using a voltmeter and stopwatch, signal generator and oscilloscope, or even low-cost data acquisition systems such as Arduino. An equivalent topic when studying alternating current circuits arises from the characterization of the impedance of the series or parallel combination of the capacitor and the resistor as a function of frequency. Determining the time constant of the RC circuit by means of impedance measurements for different frequencies is a known experimental technique that can be done using not only LCR meters but also basic instrumentation in the physics lab such as a signal generator, frequency counter, and multimeter. However, lab exercises dealing with RC circuits in alternating current usually focus on their use as filters, and the potential applications in the field of the electrical characterization of material systems are ignored. In this work, we describe a simple exercise showing how the time constant of the RC circuit can easily be determined in the introductory physics lab by means of impedance measurements as a function of frequency. This exercise allows students to learn experimental techniques that find application to characterize the time constants of the charge transport processes in material systems. Moreover, comparison of the time constants obtained from transient and frequency analysis allows us to relate the time and frequency domains, which plays a central role in the advanced analysis of electric circuits, once the concept of Laplace transform has been introduced in order to simplify the problem of dealing with differential equations in the time domain by converting them into algebraic equations within the frequency domain.

A Hybrid Approach for the Automated Finishing of Bacterial Genomes

PubMed Central

Robins, William P.; Chin, Chen-Shan; Webster, Dale; Paxinos, Ellen; Hsu, David; Ashby, Meredith; Wang, Susana; Peluso, Paul; Sebra, Robert; Sorenson, Jon; Bullard, James; Yen, Jackie; Valdovino, Marie; Mollova, Emilia; Luong, Khai; Lin, Steven; LaMay, Brianna; Joshi, Amruta; Rowe, Lori; Frace, Michael; Tarr, Cheryl L.; Turnsek, Maryann; Davis, Brigid M; Kasarskis, Andrew; Mekalanos, John J.; Waldor, Matthew K.; Schadt, Eric E.

2013-01-01

Dramatic improvements in DNA sequencing technology have revolutionized our ability to characterize most genomic diversity. However, accurate resolution of large structural events has remained challenging due to the comparatively shorter read lengths of second-generation technologies. Emerging third-generation sequencing technologies, which yield markedly increased read length on rapid time scales and for low cost, have the potential to address assembly limitations. Here we combine sequencing data from second- and third-generation DNA sequencing technologies to assemble the two-chromosome genome of a recent Haitian cholera outbreak strain into two nearly finished contigs at > 99.9% accuracy. Complex regions with clinically significant structure were completely resolved. In separate control assemblies on experimental and simulated data for the canonical N16961 reference we obtain 14 and 8 scaffolds greater than 1kb, respectively, correcting several errors in the underlying source data. This work provides a blueprint for the next generation of rapid microbial identification and full-genome assembly. PMID:22750883

Stochastic modeling of the hypothalamic pulse generator activity.

PubMed

Camproux, A C; Thalabard, J C; Thomas, G

1994-11-01

Luteinizing hormone (LH) is released by the pituitary in discrete pulses. In the monkey, the appearance of LH pulses in the plasma is invariably associated with sharp increases (i.e, volleys) in the frequency of the hypothalamic pulse generator electrical activity, so that continuous monitoring of this activity by telemetry provides a unique means to study the temporal structure of the mechanism generating the pulses. To assess whether the times of occurrence and durations of previous volleys exert significant influence on the timing of the next volley, we used a class of periodic counting process models that specify the stochastic intensity of the process as the product of two factors: 1) a periodic baseline intensity and 2) a stochastic regression function with covariates representing the influence of the past. This approach allows the characterization of circadian modulation and memory range of the process underlying hypothalamic pulse generator activity, as illustrated by fitting the model to experimental data from two ovariectomized rhesus monkeys.

Atom probe trajectory mapping using experimental tip shape measurements.

PubMed

Haley, D; Petersen, T; Ringer, S P; Smith, G D W

2011-11-01

Atom probe tomography is an accurate analytical and imaging technique which can reconstruct the complex structure and composition of a specimen in three dimensions. Despite providing locally high spatial resolution, atom probe tomography suffers from global distortions due to a complex projection function between the specimen and detector which is different for each experiment and can change during a single run. To aid characterization of this projection function, this work demonstrates a method for the reverse projection of ions from an arbitrary projection surface in 3D space back to an atom probe tomography specimen surface. Experimental data from transmission electron microscopy tilt tomography are combined with point cloud surface reconstruction algorithms and finite element modelling to generate a mapping back to the original tip surface in a physically and experimentally motivated manner. As a case study, aluminium tips are imaged using transmission electron microscopy before and after atom probe tomography, and the specimen profiles used as input in surface reconstruction methods. This reconstruction method is a general procedure that can be used to generate mappings between a selected surface and a known tip shape using numerical solutions to the electrostatic equation, with quantitative solutions to the projection problem readily achievable in tens of minutes on a contemporary workstation. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.

Reflection and diffraction corrections for nonlinear materials characterization by quasi-static pulse measurement

NASA Astrophysics Data System (ADS)

Nagy, Peter B.; Qu, Jianmin; Jacobs, Laurence J.

2014-02-01

A harmonic acoustic tone burst propagating through an elastic solid with quadratic nonlinearity produces not only a parallel burst of second harmonic but also an often neglected quasi-static pulse associated with the acoustic radiation-induced eigenstrain. Although initial analytical and experimental studies by Yost and Cantrell suggested that the pulse might have a right-angled triangular shape with the peak displacement at the leading edge being proportional to the length of the tone burst, more recent theoretical, analytical, numerical, and experimental studies proved that the pulse has a flat-top shape and the peak displacement is proportional to the propagation length. In this paper, analytical and numerical simulation results are presented to illustrate two types of finite-size effects. First, the finite axial dimension of the specimen cannot be simply accounted for by a linear reflection coefficient that neglects the nonlinear interaction between the combined incident and reflected fields. Second, the quasistatic pulse generated by a transducer of finite aperture suffers more severe divergence than both the fundamental and second harmonic pulses generated by the same transducer. These finite-size effects can make the top of the quasi-static pulse sloped rather than flat and therefore must be taken into consideration in the interpretation of experimental data.

Reflection and diffraction corrections for nonlinear materials characterization by quasi-static pulse measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagy, Peter B.; Qu, Jianmin; Jacobs, Laurence J.

A harmonic acoustic tone burst propagating through an elastic solid with quadratic nonlinearity produces not only a parallel burst of second harmonic but also an often neglected quasi-static pulse associated with the acoustic radiation-induced eigenstrain. Although initial analytical and experimental studies by Yost and Cantrell suggested that the pulse might have a right-angled triangular shape with the peak displacement at the leading edge being proportional to the length of the tone burst, more recent theoretical, analytical, numerical, and experimental studies proved that the pulse has a flat-top shape and the peak displacement is proportional to the propagation length. In thismore » paper, analytical and numerical simulation results are presented to illustrate two types of finite-size effects. First, the finite axial dimension of the specimen cannot be simply accounted for by a linear reflection coefficient that neglects the nonlinear interaction between the combined incident and reflected fields. Second, the quasistatic pulse generated by a transducer of finite aperture suffers more severe divergence than both the fundamental and second harmonic pulses generated by the same transducer. These finite-size effects can make the top of the quasi-static pulse sloped rather than flat and therefore must be taken into consideration in the interpretation of experimental data.« less

Dynamic generation of Ince-Gaussian modes with a digital micromirror device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Yu-Xuan, E-mail: yxren@ustc.edu.cn; Fang, Zhao-Xiang; Chen, Yue

Ince-Gaussian (IG) beam with elliptical profile, as a connection between Hermite-Gaussian (HG) and Laguerre-Gaussian (LG) beams, has showed unique advantages in some applications such as quantum entanglement and optical micromanipulation. However, its dynamic generation with high switching frequency is still challenging. Here, we experimentally reported the quick generation of Ince-Gaussian beam by using a digital micro-mirror device (DMD), which has the highest switching frequency of 5.2 kHz in principle. The configurable properties of DMD allow us to observe the quasi-smooth variation from LG (with ellipticity ε=0) to IG and HG (ε=∞) beam. This approach might pave a path to high-speedmore » quantum communication in terms of IG beam. Additionally, the characterized axial plane intensity distribution exhibits a 3D mould potentially being employed for optical micromanipulation.« less

Production and characterization of pure cryogenic inertial fusion targets

NASA Astrophysics Data System (ADS)

Boyd, B. A.; Kamerman, G. W.

An experimental cryogenic inertial fusion target generator and two optical techniques for automated target inspection are described. The generator produces 100 microns diameter solid hydrogen spheres at a rate compatible with fueling requirements of conceptual inertial fusion power plants. A jet of liquified hydrogen is disrupted into droplets by an ultrasonically excited nozzle. The droplets solidify into microspheres while falling through a chamber maintained below the hydrogen triple point pressure. Stable operation of the generator has been demonstrated for up to three hours. The optical inspection techniques are computer aided photomicrography and coarse diffraction pattern analysis (CDPA). The photomicrography system uses a conventional microscope coupled to a computer by a solid state camera and digital image memory. The computer enhances the stored image and performs feature extraction to determine pellet parameters. The CDPA technique uses Fourier transform optics and a special detector array to perform optical processing of a target image.

Episodic Future Thinking in Generalized Anxiety Disorder

PubMed Central

Wu, Jade Q.; Szpunar, Karl K.; Godovich, Sheina A.; Schacter, Daniel L.; Hofmann, Stefan G.

2015-01-01

Research on future-oriented cognition in generalized anxiety disorder (GAD) has primarily focused on worry, while less is known about the role of episodic future thinking (EFT), an imagery-based cognitive process. To characterize EFT in this disorder, we used the experimental recombination procedure, in which 21 GAD and 19 healthy participants simulated positive, neutral and negative novel future events either once or repeatedly, and rated their phenomenological experience of EFT. Results showed that healthy controls spontaneously generated more detailed EFT over repeated simulations. Both groups found EFT easier to generate after repeated simulations, except when GAD participants simulated positive events. They also perceived higher plausibility of negative—not positive or neutral—future events than did controls. These results demonstrate a negativity bias in GAD individuals’ episodic future cognition, and suggest their relative deficit in generating vivid EFT. We discuss implications for the theory and treatment of GAD. PMID:26398003

Laser generated Ge ions accelerated by additional electrostatic field for implantation technology

NASA Astrophysics Data System (ADS)

Rosinski, M.; Gasior, P.; Fazio, E.; Ando, L.; Giuffrida, L.; Torrisi, L.; Parys, P.; Mezzasalma, A. M.; Wolowski, J.

2013-05-01

The paper presents research on the optimization of the laser ion implantation method with electrostatic acceleration/deflection including numerical simulations by the means of the Opera 3D code and experimental tests at the IPPLM, Warsaw. To introduce the ablation process an Nd:YAG laser system with repetition rate of 10 Hz, pulse duration of 3.5 ns and pulse energy of 0.5 J has been applied. Ion time of flight diagnostics has been used in situ to characterize concentration and energy distribution in the obtained ion streams while the postmortem analysis of the implanted samples was conducted by the means of XRD, FTIR and Raman Spectroscopy. In the paper the predictions of the Opera 3D code are compared with the results of the ion diagnostics in the real experiment. To give the whole picture of the method, the postmortem results of the XRD, FTIR and Raman characterization techniques are discussed. Experimental results show that it is possible to achieve the development of a micrometer-sized crystalline Ge phase and/or an amorphous one only after a thermal annealing treatment.

Simultaneous density-field visualization and PIV of the Richtmyer-Meshkov instability

NASA Astrophysics Data System (ADS)

Prestridge, Katherine; Rightley, Paul; Benjamin, Robert; Kurnit, Norman; Boxx, Isaac; Vorobieff, Peter

1999-11-01

We describe a highly-detailed experimental characterization of the Richtmyer-Meshkov instability. A vertical curtain of heavy gas (SF_6) flows into the test section of an air-filled, horizontal shock tube, and the instability evolves after the passage of a Mach 1.2 shock past the curtain. The evolution of the curtain is visualized by seeding the SF6 with small (d ≈ 0.5 μm) glycol/water droplets using a modified theatrical fog generator. Because the event lasts only 1 ms and the initial conditions vary from test to test, rapid and high-resolution (both spatial and temporal) data acquisition is required in order to characterize the initial and dynamic conditions for each experimental event. A customized, frequency-doubled, burst mode Nd:YAG laser and a commercial single-pulse laser are used for the implementation of simultaneous density-field imaging and PIV diagnostics. We have provided data about flow scaling and mixing through image analysis, and PIV data gives us further quantitative physical insight into the evolution of the Richtmyer-Meshkov instability.

Integrated Genomic Analysis of Diverse Induced Pluripotent Stem Cells from the Progenitor Cell Biology Consortium.

PubMed

Salomonis, Nathan; Dexheimer, Phillip J; Omberg, Larsson; Schroll, Robin; Bush, Stacy; Huo, Jeffrey; Schriml, Lynn; Ho Sui, Shannan; Keddache, Mehdi; Mayhew, Christopher; Shanmukhappa, Shiva Kumar; Wells, James; Daily, Kenneth; Hubler, Shane; Wang, Yuliang; Zambidis, Elias; Margolin, Adam; Hide, Winston; Hatzopoulos, Antonis K; Malik, Punam; Cancelas, Jose A; Aronow, Bruce J; Lutzko, Carolyn

2016-07-12

The rigorous characterization of distinct induced pluripotent stem cells (iPSC) derived from multiple reprogramming technologies, somatic sources, and donors is required to understand potential sources of variability and downstream potential. To achieve this goal, the Progenitor Cell Biology Consortium performed comprehensive experimental and genomic analyses of 58 iPSC from ten laboratories generated using a variety of reprogramming genes, vectors, and cells. Associated global molecular characterization studies identified functionally informative correlations in gene expression, DNA methylation, and/or copy-number variation among key developmental and oncogenic regulators as a result of donor, sex, line stability, reprogramming technology, and cell of origin. Furthermore, X-chromosome inactivation in PSC produced highly correlated differences in teratoma-lineage staining and regulator expression upon differentiation. All experimental results, and raw, processed, and metadata from these analyses, including powerful tools, are interactively accessible from a new online portal at https://www.synapse.org to serve as a reusable resource for the stem cell community. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Breaching peripheral tolerance promotes the production of HIV-1–neutralizing antibodies

PubMed Central

Schroeder, Kristin M.S.; Harper, Michael S.; Santiago, Mario L.

2017-01-01

A subset of characterized HIV-1 broadly neutralizing antibodies (bnAbs) are polyreactive with additional specificities for self-antigens and it has been proposed immunological tolerance may present a barrier to their participation in protective humoral immunity. We address this hypothesis by immunizing autoimmune-prone mice with HIV-1 Envelope (Env) and characterizing the primary antibody response for HIV-1 neutralization. We find autoimmune mice generate neutralizing antibody responses to tier 2 HIV-1 strains with alum treatment alone in the absence of Env. Importantly, experimentally breaching immunological tolerance in wild-type mice also leads to the production of tier 2 HIV-1–neutralizing antibodies, which increase in breadth and potency following Env immunization. In both genetically prone and experimentally induced mouse models of autoimmunity, increased serum levels of IgM anti-histone H2A autoantibodies significantly correlated with tier 2 HIV-1 neutralization, and anti-H2A antibody clones were found to neutralize HIV-1. These data demonstrate that breaching peripheral tolerance permits a cross-reactive HIV-1 autoantibody response able to neutralize HIV-1. PMID:28698284

Development of a shape memory alloy actuated biomimetic vehicle

NASA Astrophysics Data System (ADS)

Garner, L. J.; Wilson, L. N.; Lagoudas, D. C.; Rediniotis, O. K.

2000-10-01

The development of a biomimetic active hydrofoil that utilizes shape memory alloy (SMA) actuator technology is presented. This work is the first stage prototype of a vehicle that will consist of many actuated body segments. The current work describes the design, modeling and testing of a single-segment demonstration SMA actuated hydrofoil. The SMA actuation elements are two sets of thin wires on either side of an elastomeric component that joins together the leading and trailing edges of the hydrofoil. Controlled heating and cooling of the two wire sets generates bi-directional bending of the elastomer, which in turn deflects the trailing edge of the hydrofoil. In this paper the design of the hydrofoil and the experimental tests preformed thereon are explained. A detailed account of SMA actuator preparation (training) and material characterization is given. Finite-element method (FEM) modeling of hydrofoil response to electrical heating of the SMA actuators is carried out using a thermomechanical constitutive model for the SMA with input from the material characterization. The modeling predictions are finally compared with experimental measurements of the trailing edge deflection and the SMA actuator temperature.

Landau-Squire jet as a versatile probe to measure flow rate through individual nanochannel and nanotubes

NASA Astrophysics Data System (ADS)

Secchi, Eleonora; Marbach, Sophie; Siria, Alessandro; Bocquet, Lyderic

2015-11-01

Over the last decade, nanometric sized channels have been intensively investigated since new model of fluid transport are expected due to the flow confinement at the nanometric scale. Nanoconfinement generates new phenomena, such as superfast flows in carbon nanotubes and slippage over smooth surfaces. However, a major challenge of nanofluidics lies in fabricating nanoscale fluidic devices and developing new velocimetry techniques able to measure flow rates down to femtoL/s. In this work we report the experimental study of the velocity fields generated by pressure driven flow from glass nanochannel with a diameter ranging from 1 μm to 100nm. The flow emerging from these channels can be described by the classical Landau-Squire solution of the Navier-Stokes equation for a point jet. We show that due to the peculiarity of this flow, it can be used as an efficient probe to characterize the permeability of nanochannels. Velocity field is measured experimentally seeding the fluid in the reservoir with 500 nm Polystyrene particles and measuring the velocity with a standard PIV algorithm. Predictions are tested for nanochannels of several dimensions and supported by ionic current measurement. This demonstrates that this technique is a powerful tool to characterize the flow through nanochannels. We finally apply this method to the measurement of the flow emerging from a single carbon nanotube inserted in the nanochannels and present first data of permeability measurement through a single nanotube.

Random field assessment of nanoscopic inhomogeneity of bone

PubMed Central

Dong, X. Neil; Luo, Qing; Sparkman, Daniel M.; Millwater, Harry R.; Wang, Xiaodu

2010-01-01

Bone quality is significantly correlated with the inhomogeneous distribution of material and ultrastructural properties (e.g., modulus and mineralization) of the tissue. Current techniques for quantifying inhomogeneity consist of descriptive statistics such as mean, standard deviation and coefficient of variation. However, these parameters do not describe the spatial variations of bone properties. The objective of this study was to develop a novel statistical method to characterize and quantitatively describe the spatial variation of bone properties at ultrastructural levels. To do so, a random field defined by an exponential covariance function was used to present the spatial uncertainty of elastic modulus by delineating the correlation of the modulus at different locations in bone lamellae. The correlation length, a characteristic parameter of the covariance function, was employed to estimate the fluctuation of the elastic modulus in the random field. Using this approach, two distribution maps of the elastic modulus within bone lamellae were generated using simulation and compared with those obtained experimentally by a combination of atomic force microscopy and nanoindentation techniques. The simulation-generated maps of elastic modulus were in close agreement with the experimental ones, thus validating the random field approach in defining the inhomogeneity of elastic modulus in lamellae of bone. Indeed, generation of such random fields will facilitate multi-scale modeling of bone in more pragmatic details. PMID:20817128

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE PAGES

Li, Liang; Zhang, Rui; Vinson, John; ...

2018-03-05

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Imaging Catalytic Activation of CO 2 on Cu 2O (110): A First-Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Liang; Zhang, Rui; Vinson, John

Balancing global energy needs against increasing greenhouse gas emissions requires new methods for efficient CO 2 reduction. While photoreduction of CO 2 is a viable approach for fuel generation, the rational design of photocatalysts hinges on precise characterization of the surface catalytic reactions. Cu 2O is a promising next-generation photocatalyst, but the atomic-scale description of the interaction between CO 2 and the Cu 2O surface is largely unknown, and detailed experimental measurements are lacking. In this study, density-functional-theory (DFT) calculations have been performed to identify the Cu 2O (110) surface stoichiometry that favors CO 2 reduction. To facilitate interpretation ofmore » scanning tunneling microscopy (STM) and X-ray absorption near-edge structures (XANES) measurements, which are useful for characterizing catalytic reactions, we present simulations based on DFT-derived surface morphologies with various adsorbate types. STM and XANES simulations were performed using the Tersoff Hamann approximation and Bethe-Salpeter equation (BSE) approach, respectively. The results provide guidance for observation of CO 2 reduction reaction on, and rational surface engineering of, Cu 2O (110). In conclusion, they also demonstrate the effectiveness of computational image and spectroscopy modeling as a predictive tool for surface catalysis characterization.« less

Dynamic optimization of walker-assisted FES-activated paraplegic walking: simulation and experimental studies.

PubMed

Nekoukar, Vahab; Erfanian, Abbas

2013-11-01

In this paper, we propose a musculoskeletal model of walker-assisted FES-activated paraplegic walking for the generation of muscle stimulation patterns and characterization of the causal relationships between muscle excitations, multi-joint movement, and handle reaction force (HRF). The model consists of the lower extremities, trunk, hands, and a walker. The simulation of walking is performed using particle swarm optimization to minimize the tracking errors from the desired trajectories for the lower extremity joints, to reduce the stimulations of the muscle groups acting around the hip, knee, and ankle joints, and to minimize the HRF. The results of the simulation studies using data recorded from healthy subjects performing walker-assisted walking indicate that the model-generated muscle stimulation patterns are in agreement with the EMG patterns that have been reported in the literature. The experimental results on two paraplegic subjects demonstrate that the proposed methodology can improve walking performance, reduce HRF, and increase walking speed when compared to the conventional FES-activated paraplegic walking. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Rapid computation of photoacoustic fields from normal and pathological red blood cells using a Green's function method

NASA Astrophysics Data System (ADS)

Saha, Ratan K.; Fadhel, Muhannad N.; Lawrence, Aamna; Karmakar, Subhajit; Adhikari, Arunabha; Kolios, Michael C.

2017-03-01

Photoacoustic (PA) field calculations using a Green's function approach is presented. The method has been applied to predict PA spectra generated by normal (discocyte) and pathological (stomatocyte) red blood cells (RBCs). The contours of normal and pathological RBCs were generated by employing a popular parametric model and accordingly, fitted with the Legendre polynomial expansions for surface parametrization. The first frequency minimum of theoretical PA spectrum approximately appears at 607 MHz for a discocyte and 410 MHz for a stomatocyte when computed from the direction of symmetry axis. The same feature occurs nearly at 247 and 331 MHz, respectively, for those particles when measured along the perpendicular direction. The average experimental spectrum for normal RBCs is found to be flat over a bandwidth of 150-500 MHz when measured along the direction of symmetry axis. For spherical RBCs, both the theoretical and experimental spectra demonstrate negative slope over a bandwidth of 250-500 MHz. Using the Green's function method discussed, it may be possible to rapidly characterize cellular morphology from single-particle PA spectra.

Direct femtosecond laser ablation of copper with an optical vortex beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anoop, K. K.; Rubano, A.; Marrucci, L.

Laser surface structuring of copper is induced by laser ablation with a femtosecond optical vortex beam generated via spin-to-orbital conversion of the angular momentum of light by using a q-plate. The variation of the produced surface structures is studied as a function of the number of pulses, N, and laser fluence, F. After the first laser pulse (N=1), the irradiated surface presents an annular region characterized by a corrugated morphology made by a rather complex network of nanometer-scale ridges, wrinkles, pores, and cavities. Increasing the number of pulses (21000) and a deep crater is formed. The nanostructure variation with themore » laser fluence, F, also evidences an interesting dependence, with a coarsening of the structure morphology as F increases. Our experimental findings demonstrate that direct femtosecond laser ablation with optical vortex beams produces interesting patterns not achievable by the more standard beams with a Gaussian intensity profile. They also suggest that appropriate tuning of the experimental conditions (F, N) can allow generating micro- and/or nano-structured surface for any specific application.« less

Mechanical output of myosin II motors is regulated by myosin filament size and actin network mechanics

NASA Astrophysics Data System (ADS)

Stam, Samantha; Alberts, Jonathan; Gardel, Margaret; Munro, Edwin

2013-03-01

The interactions of bipolar myosin II filaments with actin arrays are a predominate means of generating forces in numerous physiological processes including muscle contraction and cell migration. However, how the spatiotemporal regulation of these forces depends on motor mechanochemistry, bipolar filament size, and local actin mechanics is unknown. Here, we simulate myosin II motors with an agent-based model in which the motors have been benchmarked against experimental measurements. Force generation occurs in two distinct regimes characterized either by stable tension maintenance or by stochastic buildup and release; transitions between these regimes occur by changes to duty ratio and myosin filament size. The time required for building force to stall scales inversely with the stiffness of a network and the actin gliding speed of a motor. Finally, myosin motors are predicted to contract a network toward stiffer regions, which is consistent with experimental observations. Our representation of myosin motors can be used to understand how their mechanical and biochemical properties influence their observed behavior in a variety of in vitro and in vivo contexts.

Design of flat pneumatic artificial muscles

NASA Astrophysics Data System (ADS)

Wirekoh, Jackson; Park, Yong-Lae

2017-03-01

Pneumatic artificial muscles (PAMs) have gained wide use in the field of robotics due to their ability to generate linear forces and motions with a simple mechanism, while remaining lightweight and compact. However, PAMs are limited by their traditional cylindrical form factors, which must increase radially to improve contraction force generation. Additionally, this form factor results in overly complicated fabrication processes when embedded fibers and sensor elements are required to provide efficient actuation and control of the PAMs while minimizing the bulkiness of the overall robotic system. In order to overcome these limitations, a flat two-dimensional PAM capable of being fabricated using a simple layered manufacturing process was created. Furthermore, a theoretical model was developed using Von Karman’s formulation for large deformations and the energy methods. Experimental characterizations of two different types of PAMs, a single-cell unit and a multi-cell unit, were performed to measure the maximum contraction lengths and forces at input pressures ranging from 0 to 150 kPa. Experimental data were then used to verify the fidelity of the theoretical model.

Long pulse Soft X-ray Emission from Laser Generated Irradiated Gold Foils

NASA Astrophysics Data System (ADS)

Davis, Joshua; Frank, Yechiel; Raicher, Erez; Fraenkel, Moshe; Keiter, Paul; Klein, Sallee; Drake, R. P.; Shvarts, Dov

2016-10-01

Long pulse soft x-ray sources (SXS) allow for flexibility in high-energy-density experimental designs by providing a means of driving matter to the high temperatures needed, for example to study radiation waves in different materials. SXSs can be made by using lasers to heat a high-Z thin foil, which then acts as a quasi-blackbody emitter. Previous studies of the x-ray emission characteristics of gold foils have focused on laser pulses of 1ns or less. We performed experiments using a 6.0ns laser pulse with energy of 2kJ on the Omega-60 system to generate and characterize multi-ns laser heated Au foils of thicknesses between 0.5-2.0 μm. We measured the 2D spatial profile of the emission with a soft x-ray camera and the time history of the emission with the Dante photodiode array . Effective temperatures for the emission were then calculated using the Dante measurements. Discussion of experimental results and a comparison with 1-D Rad-Hydro NLTE simulations will be presented.

Development and numerical/experimental characterization of a lab-scale flat flame reactor allowing the analysis of pulverized solid fuel devolatilization and oxidation at high heating rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemaire, R., E-mail: romain.lemaire@mines-douai.fr; Menanteau, S.

2016-01-15

This paper deals with the thorough characterization of a new experimental test bench designed to study the devolatilization and oxidation of pulverized fuel particles in a wide range of operating conditions. This lab-scale facility is composed of a fuel feeding system, the functioning of which has been optimized by computational fluid dynamics. It allows delivering a constant and time-independent mass flow rate of fuel particles which are pneumatically transported to the central injector of a hybrid McKenna burner using a carrier gas stream that can be inert or oxidant depending on the targeted application. A premixed propane/air laminar flat flamemore » stabilized on the porous part of the burner is used to generate the hot gases insuring the heating of the central coal/carrier-gas jet with a thermal gradient similar to those found in industrial combustors (>10{sup 5} K/s). In the present work, results issued from numerical simulations performed a priori to characterize the velocity and temperature fields in the reaction chamber have been analyzed and confronted with experimental measurements carried out by coupling particle image velocimetry, thermocouple and two-color pyrometry measurements so as to validate the order of magnitude of the heating rate delivered by such a new test bench. Finally, the main features of the flat flame reactor we developed have been discussed with respect to those of another laboratory-scale system designed to study coal devolatilization at a high heating rate.« less

Development and numerical/experimental characterization of a lab-scale flat flame reactor allowing the analysis of pulverized solid fuel devolatilization and oxidation at high heating rates

NASA Astrophysics Data System (ADS)

Lemaire, R.; Menanteau, S.

2016-01-01

This paper deals with the thorough characterization of a new experimental test bench designed to study the devolatilization and oxidation of pulverized fuel particles in a wide range of operating conditions. This lab-scale facility is composed of a fuel feeding system, the functioning of which has been optimized by computational fluid dynamics. It allows delivering a constant and time-independent mass flow rate of fuel particles which are pneumatically transported to the central injector of a hybrid McKenna burner using a carrier gas stream that can be inert or oxidant depending on the targeted application. A premixed propane/air laminar flat flame stabilized on the porous part of the burner is used to generate the hot gases insuring the heating of the central coal/carrier-gas jet with a thermal gradient similar to those found in industrial combustors (>105 K/s). In the present work, results issued from numerical simulations performed a priori to characterize the velocity and temperature fields in the reaction chamber have been analyzed and confronted with experimental measurements carried out by coupling particle image velocimetry, thermocouple and two-color pyrometry measurements so as to validate the order of magnitude of the heating rate delivered by such a new test bench. Finally, the main features of the flat flame reactor we developed have been discussed with respect to those of another laboratory-scale system designed to study coal devolatilization at a high heating rate.

Magnetostrictive energy generator for harvesting the rotation of human knee joint

NASA Astrophysics Data System (ADS)

Yan, Baiping; Zhang, Chengming; Li, Liyi

2018-05-01

This paper presents the design and fabrication of a rotary-impact magnetostrictive energy generator, used to harvest the rotation of human knee joint. The harvester consists of twelve movable Terfenol-D rods, surrounded by the picked up coils respectively, and alternate permanent magnet (PM) array sandwiched in each part of the shell. Rotational electromagnetic power generating effect and impacted magnetostrictive power generating effect are designed in the harvester. Modeling and simulation are used to validate the concept. Then, magnetic field and leakage of the harvester are analyzed, electromagnetic force in the harvester is simulated. A prototype of harvester is fabricated, and subjected to the experimental characterization. It can be concluded that huge induced voltage generated in the short-time impact situation and that induced voltage in the harvester can reach up to 60-80 volts at 0.91Hz low frequency rotation. Also, the presented harvester has good harvesting effects at low frequency human walking and periodic swing crus situation, which are suitable to be used for future researches of wearable knee joint applications.

Design and Analysis of Nano-Pulse Generator for Industrial Wastewater Application

NASA Astrophysics Data System (ADS)

Jang, Sung-Duck; Son, Yoon-Kyoo; Cho, Moo-Hyun; Norov, Enkhbat

2018-05-01

Recently, the application of a pulsed power system is being extended to environmental and industrial fields. The non-dissolution wastewater pollutants from industrial plants can be processed by applying high-voltage pulses with a fast rising time (a few nanoseconds) and short duration (nano to microseconds) in a pulsed corona discharge reactor. The high-voltage nano-pulse generator with a magnetic switch has been developed. It can be used for a spray type water treatment facility. Its corona current in load can be adjusted by pulse width and repetition rate. We investigated the performance of the nano-pulse generator by using the dummy load that is composed of resistor and capacitor equivalent to the actual reactor. In this paper, the results of design, construction and characterization of a high-voltage nano-pulse generator for an industrial wastewater treatment are reported. Consequently, a pulse width of 1.1 μs at the repetition rate of 200 pps, a peak voltage of 41 kV for the nano-pulse generator were achieved across a 640 Ω load. The simulation results on magnetic switch show reasonable agreement with experimental ones.

Optical-Based Artificial Palpation Sensors for Lesion Characterization

PubMed Central

Lee, Jong-Ha; Kim, Yoon Nyun; Ku, Jeonghun; Park, Hee-Jun

2013-01-01

Palpation techniques are widely used in medical procedures to detect the presence of lumps or tumors in the soft breast tissues. Since these procedures are very subjective and depend on the skills of the physician, it is imperative to perform detailed a scientific study in order to develop more efficient medical sensors to measure and generate palpation parameters. In this research, we propose an optical-based, artificial palpation sensor for lesion characterization. This has been developed using a multilayer polydimethylsiloxane optical waveguide. Light was generated at the critical angle to reflect totally within the flexible and transparent waveguide. When a waveguide was compressed by an external force, its contact area would deform and cause the light to scatter. The scattered light was captured by a high-resolution camera and saved as an image format. To test the performance of the proposed system, we used a realistic tissue phantom with embedded hard inclusions. The experimental results show that the proposed sensor can detect inclusions and provide the relative value of size, depth, and Young's modulus of an inclusion. PMID:23966198

High-order harmonic generation driven by inhomogeneous plasmonics fields spatially bounded: influence on the cut-off law

NASA Astrophysics Data System (ADS)

Neyra, E.; Videla, F.; Ciappina, M. F.; Pérez-Hernández, J. A.; Roso, L.; Lewenstein, M.; Torchia, G. A.

2018-03-01

We study high-order harmonic generation (HHG) in model atoms driven by plasmonic-enhanced fields. These fields result from the illumination of plasmonic nanostructures by few-cycle laser pulses. We demonstrate that the spatial inhomogeneous character of the laser electric field, in a form of Gaussian-shaped functions, leads to an unexpected relationship between the HHG cutoff and the laser wavelength. Precise description of the spatial form of the plasmonic-enhanced field allows us to predict this relationship. We combine the numerical solutions of the time-dependent Schrödinger equation (TDSE) with the plasmonic-enhanced electric fields obtained from 3D finite element simulations. We additionally employ classical simulations to supplement the TDSE outcomes and characterize the extended HHG spectra by means of their associated electron trajectories. A proper definition of the spatially inhomogeneous laser electric field is instrumental to accurately describe the underlying physics of HHG driven by plasmonic-enhanced fields. This characterization opens up new perspectives for HHG control with various experimental nano-setups.

Temperature-Dependent Characterization, Modeling, and Switching Speed-Limitation Analysis of Third-Generation 10-kV SiC MOSFET

DOE PAGES

Ji, Shiqi; Zheng, Sheng; Wang, Fei; ...

2017-07-06

The temperature-dependent characteristics of the third-generation 10-kV/20-A SiC MOSFET including the static characteristics and switching performance are carried out in this paper. The steady-state characteristics, including saturation current, output characteristics, antiparallel diode, and parasitic capacitance, are tested. Here, a double pulse test platform is constructed including a circuit breaker and gate drive with >10-kV insulation and also a hotplate under the device under test for temperature-dependent characterization during switching transients. The switching performance is tested under various load currents and gate resistances at a 7-kV dc-link voltage from 25 to 125 C and compared with previous 10-kV MOSFETs. A simplemore » behavioral model with its parameter extraction method is proposed to predict the temperature-dependent characteristics of the 10-kV SiC MOSFET. The switching speed limitations, including the reverse recovery of SiC MOSFET's body diode, overvoltage caused by stray inductance, crosstalk, heat sink, and electromagnetic interference to the control are discussed based on simulations and experimental results.« less

Temperature-Dependent Characterization, Modeling, and Switching Speed-Limitation Analysis of Third-Generation 10-kV SiC MOSFET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Shiqi; Zheng, Sheng; Wang, Fei

The temperature-dependent characteristics of the third-generation 10-kV/20-A SiC MOSFET including the static characteristics and switching performance are carried out in this paper. The steady-state characteristics, including saturation current, output characteristics, antiparallel diode, and parasitic capacitance, are tested. Here, a double pulse test platform is constructed including a circuit breaker and gate drive with >10-kV insulation and also a hotplate under the device under test for temperature-dependent characterization during switching transients. The switching performance is tested under various load currents and gate resistances at a 7-kV dc-link voltage from 25 to 125 C and compared with previous 10-kV MOSFETs. A simplemore » behavioral model with its parameter extraction method is proposed to predict the temperature-dependent characteristics of the 10-kV SiC MOSFET. The switching speed limitations, including the reverse recovery of SiC MOSFET's body diode, overvoltage caused by stray inductance, crosstalk, heat sink, and electromagnetic interference to the control are discussed based on simulations and experimental results.« less

Optimizing the choice of spin-squeezed states for detecting and characterizing quantum processes

DOE PAGES

Rozema, Lee A.; Mahler, Dylan H.; Blume-Kohout, Robin; ...

2014-11-07

Quantum metrology uses quantum states with no classical counterpart to measure a physical quantity with extraordinary sensitivity or precision. Most such schemes characterize a dynamical process by probing it with a specially designed quantum state. The success of such a scheme usually relies on the process belonging to a particular one-parameter family. If this assumption is violated, or if the goal is to measure more than one parameter, a different quantum state may perform better. In the most extreme case, we know nothing about the process and wish to learn everything. This requires quantum process tomography, which demands an informationallymore » complete set of probe states. It is very convenient if this set is group covariant—i.e., each element is generated by applying an element of the quantum system’s natural symmetry group to a single fixed fiducial state. In this paper, we consider metrology with 2-photon (“biphoton”) states and report experimental studies of different states’ sensitivity to small, unknown collective SU( 2) rotations [“ SU( 2) jitter”]. Maximally entangled N00 N states are the most sensitive detectors of such a rotation, yet they are also among the worst at fully characterizing an a priori unknown process. We identify (and confirm experimentally) the best SU( 2)-covariant set for process tomography; these states are all less entangled than the N00 N state, and are characterized by the fact that they form a 2-design.« less

Bioinformatic Characterization of Glycyl Radical Enzyme-Associated Bacterial Microcompartments

PubMed Central

Zarzycki, Jan; Erbilgin, Onur

2015-01-01

Bacterial microcompartments (BMCs) are proteinaceous organelles encapsulating enzymes that catalyze sequential reactions of metabolic pathways. BMCs are phylogenetically widespread; however, only a few BMCs have been experimentally characterized. Among them are the carboxysomes and the propanediol- and ethanolamine-utilizing microcompartments, which play diverse metabolic and ecological roles. The substrate of a BMC is defined by its signature enzyme. In catabolic BMCs, this enzyme typically generates an aldehyde. Recently, it was shown that the most prevalent signature enzymes encoded by BMC loci are glycyl radical enzymes, yet little is known about the function of these BMCs. Here we characterize the glycyl radical enzyme-associated microcompartment (GRM) loci using a combination of bioinformatic analyses and active-site and structural modeling to show that the GRMs comprise five subtypes. We predict distinct functions for the GRMs, including the degradation of choline, propanediol, and fuculose phosphate. This is the first family of BMCs for which identification of the signature enzyme is insufficient for predicting function. The distinct GRM functions are also reflected in differences in shell composition and apparently different assembly pathways. The GRMs are the counterparts of the vitamin B12-dependent propanediol- and ethanolamine-utilizing BMCs, which are frequently associated with virulence. This study provides a comprehensive foundation for experimental investigations of the diverse roles of GRMs. Understanding this plasticity of function within a single BMC family, including characterization of differences in permeability and assembly, can inform approaches to BMC bioengineering and the design of therapeutics. PMID:26407889

WIPP waste characterization program sampling and analysis guidance manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1991-01-01

The Waste Isolation Pilot Plant (WIPP) Waste Characterization Program Sampling and Analysis Guidance Manual (Guidance Manual) provides a unified source of information on the sampling and analytical techniques that enable Department of Energy (DOE) facilities to comply with the requirements established in the current revision of the Quality Assurance Program Plan (QAPP) for the WIPP Experimental-Waste Characterization Program (the Program). This Guidance Manual includes all of the sampling and testing methodologies accepted by the WIPP Project Office (DOE/WPO) for use in implementing the Program requirements specified in the QAPP. This includes methods for characterizing representative samples of transuranic (TRU) wastesmore » at DOE generator sites with respect to the gas generation controlling variables defined in the WIPP bin-scale and alcove test plans, as well as waste container headspace gas sampling and analytical procedures to support waste characterization requirements under the WIPP test program and the Resource Conservation and Recovery Act (RCRA). The procedures in this Guidance Manual are comprehensive and detailed and are designed to provide the necessary guidance for the preparation of site specific procedures. The use of these procedures is intended to provide the necessary sensitivity, specificity, precision, and comparability of analyses and test results. The solutions to achieving specific program objectives will depend upon facility constraints, compliance with DOE Orders and DOE facilities' operating contractor requirements, and the knowledge and experience of the TRU waste handlers and analysts. With some analytical methods, such as gas chromatography/mass spectrometry, the Guidance Manual procedures may be used directly. With other methods, such as nondestructive/destructive characterization, the Guidance Manual provides guidance rather than a step-by-step procedure.« less

Experimental evaluation of a cruciform piezoelectric energy harvester

NASA Astrophysics Data System (ADS)

Tsuruta, Karina M.; Rade, Domingos A.; Finzi Neto, Roberto M.; Cavalini, Aldemir A.

2016-10-01

This paper describes the development and experimental evaluation of a particular type of piezoelectric energy harvester, composed of four aluminum cantilever blades to which piezoelectric patches are bonded, in such way that electric energy is generated when the blades undergo bending vibrations. Concentrated masses, whose values can be varied, are attached to the tips of the blades. Due to the geometric shape of the harvester, in which the four blades are oriented forming right angles, the harvester is named cruciform. As opposed to the large majority of previous works on the subject, in which harvesters are excited at their bases by prescribed acceleration, herein the harvester is connected to a vibrating structure excited by an imbalance force. Hence, the amount of harvested energy depends upon the dynamic interaction between the harvester and the host structure. Laboratory experiments were carried-out on a prototype connected to a tridimensional truss. The experimental setup includes a force generator consisting of an imbalanced disc driven by an electrical motor whose rotation is controlled electronically, a voltage rectifier circuit, and a battery charged with the harvested energy. After characterization of the dynamic behavior of the harvester and the host structure, both numerically and experimentally, the results of experiments are presented and discussed in terms of the voltage output of the piezoelectric transducers as function of the excitation frequency and the values of the tip masses. Also, the capacity of the harvester to charge a Lithium battery is evaluated.

Ultrasonic nondestructive materials characterization

NASA Technical Reports Server (NTRS)

Green, R. E., Jr.

1986-01-01

A brief review of ultrasonic wave propagation in solid materials is presented with consideration of the altered behavior in anisotropic and nonlinear elastic materials in comparison with isotropic and linear elastic materials. Some experimental results are described in which ultrasonic velocity and attenuation measurements give insight into materials microstructure and associated mechanical properties. Recent developments with laser beam non-contact generation and detection of ultrasound are presented. The results of several years of experimental measurements using high-power ultrasound are discussed, which provide substantial evidence of the inability of presently accepted theories to fully explain the interaction of ultrasound with solid materials. Finally, a special synchrotron X-ray topographic system is described which affords the possibility of observing direct interaction of ultrasonic waves with the microstructural features of real crystalline solid materials for the first time.

Fostering synergy between cell biology and systems biology.

PubMed

Eddy, James A; Funk, Cory C; Price, Nathan D

2015-08-01

In the shared pursuit of elucidating detailed mechanisms of cell function, systems biology presents a natural complement to ongoing efforts in cell biology. Systems biology aims to characterize biological systems through integrated and quantitative modeling of cellular information. The process of model building and analysis provides value through synthesizing and cataloging information about cells and molecules, predicting mechanisms and identifying generalizable themes, generating hypotheses and guiding experimental design, and highlighting knowledge gaps and refining understanding. In turn, incorporating domain expertise and experimental data is crucial for building towards whole cell models. An iterative cycle of interaction between cell and systems biologists advances the goals of both fields and establishes a framework for mechanistic understanding of the genome-to-phenome relationship. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Nonlinear characterization of a single-axis acoustic levitator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrade, Marco A. B.; Ramos, Tiago S.; Okina, Fábio T. A.

2014-04-15

The nonlinear behavior of a 20.3 kHz single-axis acoustic levitator formed by a Langevin transducer with a concave radiating surface and a concave reflector is experimentally investigated. In this study, a laser Doppler vibrometer is applied to measure the nonlinear sound field in the air gap between the transducer and the reflector. Additionally, an electronic balance is used in the measurement of the acoustic radiation force on the reflector as a function of the distance between the transducer and the reflector. The experimental results show some effects that cannot be described by the linear acoustic theory, such as the jumpmore » phenomenon, harmonic generation, and the hysteresis effect. The influence of these nonlinear effects on the acoustic levitation of small particles is discussed.« less

Investigation of arterial gas occlusions. [effect of noncondensable gases on high performance heat pipes

NASA Technical Reports Server (NTRS)

Saaski, E. W.

1974-01-01

The effect of noncondensable gases on high-performance arterial heat pipes was investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate, and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, were used to postulate stability criteria for arterial heat pipes under isothermal and non-isothermal condensate flow conditions. A rigorous second-order gas-loaded heat pipe model, incorporating axial conduction and one-dimensional vapor transport, was produced and used for thermal and gas studies. A Freon-22 (CHCIF2) heat pipe was used with helium and xenon to validate modeling. With helium, experimental data compared well with theory. Unusual gas-control effects with xenon were attributed to high solubility.

Magnetic field generation from shear flow in flux ropes

NASA Astrophysics Data System (ADS)

Intrator, T. P.; Sears, J.; Gao, K.; Klarenbeek, J.; Yoo, C.

2012-10-01

In the Reconnection Scaling Experiment (RSX) we have measured out of plane quadrupole magnetic field structure in situations where magnetic reconnection was minimal. This quadrupole out of plane magnetic signature has historically been presumed to be the smoking gun harbinger of reconnection. On the other hand, we showed that when flux ropes bounced instead of merging and reconnecting, this signature could evolve. This can follow from sheared fluid flows in the context of a generalized Ohms Law. We reconstruct a shear flow model from experimental data for flux ropes that have been experimentally well characterized in RSX as screw pinch equilibria, including plasma ion and electron flow, with self consistent profiles for magnetic field, pressure, and current density. The data can account for the quadrupole field structure.

Reconstruction-free sensitive wavefront sensor based on continuous position sensitive detectors.

PubMed

Godin, Thomas; Fromager, Michael; Cagniot, Emmanuel; Brunel, Marc; Aït-Ameur, Kamel

2013-12-01

We propose a new device that is able to perform highly sensitive wavefront measurements based on the use of continuous position sensitive detectors and without resorting to any reconstruction process. We demonstrate experimentally its ability to measure small wavefront distortions through the characterization of pump-induced refractive index changes in laser material. In addition, it is shown using computer-generated holograms that this device can detect phase discontinuities as well as improve the quality of sharp phase variations measurements. Results are compared to reference Shack-Hartmann measurements, and dramatic enhancements are obtained.

Self-referenced interferometer for cylindrical surfaces.

PubMed

Šarbort, Martin; Řeřucha, Šimon; Holá, Miroslava; Buchta, Zdeněk; Lazar, Josef

2015-11-20

We present a new interferometric method for shape measurement of hollow cylindrical tubes. We propose a simple and robust self-referenced interferometer where the reference and object waves are represented by the central and peripheral parts, respectively, of the conical wave generated by a single axicon lens. The interferogram detected by a digital camera is characterized by a closed-fringe pattern with a circular carrier. The interference phase is demodulated using spatial synchronous detection. The capabilities of the interferometer are experimentally tested for various hollow cylindrical tubes with lengths up to 600 mm.

Pepper-pot based emittance measurements of the AWA photoinjector.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Power, J. G.; Conde, M. E.; Gai, W.

2008-01-01

The Argonne Wakefield Accelerator (AWA) RF photocathode gun is a 1.5 cell, L-band, RF photocathode gun operating at 77 MV/m, with emittance compensating solenoids, a magnesium photocathode, and generates an 8 MeV, 1 nC - 100 nC beam. In this paper, we report on a parametric set of measurements to characterize the transverse trace space of the 1 nC electron beam directly out of the gun. We emphasize details of the experimental setup, image analysis, and end with a comparison of the measurements to PARMELA simulations.

Time-resolved photoacoustic measurement for evaluation of viscoelastic properties of biological tissues

NASA Astrophysics Data System (ADS)

Zhao, Yue; Chen, Conggui; Liu, Hongwei; Yang, Sihua; Xing, Da

2016-11-01

In this letter, we proposed a method for viscoelastic characterization of biological tissues based on time-resolved photoacoustic measurement. The theoretical and experimental study was performed on the influence of viscoelasticity effects on photoacoustic generation. Taking the time delay between the photoacoustic signal and the exciting laser, the viscoelasticity distribution of biological tissues can be mapped. To validate our method, gelatin phantoms with different densities were measured. We also applied this method in discrimination between fat and liver to confirm the usefulness of the viscoelastic evaluation. Furthermore, pilot experiments were performed on atherosclerosis artery from an apolipoprotein E-knockout mouse to show the viscoelastic characterization of atherosclerotic plaque. Our results demonstrate that this technique has the potential for visualizing the biomechanical properties and lesions of biological tissues.

Design of a power-asymmetric actuator for a transtibial prosthesis.

PubMed

Bartlett, Harrison L; Lawson, Brian E; Goldfarb, Michael

2017-07-01

This paper presents the design and characterization of a power-asymmetric actuator for a transtibial prosthesis. The device is designed to provide the combination of: 1) joint locking, 2) high power dissipation, and 3) low power generation. This actuator functionality allows for a prosthesis to be designed with minimal mass and power consumption relative to a fully-powered robotic prosthesis while maintaining much of the functionality necessary for activities of daily living. The actuator achieves these design characteristics while maintaining a small form factor by leveraging a combination of electromechanical and hydraulic components. The design of the actuator is described herein, and results of an experimental characterization are provided that indicate that the actuator is capable of providing the functional capabilities required of an ankle prosthesis in a compact and lightweight package.

Three-Dimensional Modeling of Low-Mode Asymmetries in OMEGA Cryogenic Implosions

NASA Astrophysics Data System (ADS)

Anderson, K. S.; McKenty, P. W.; Shvydky, A.; Collins, T. J. B.; Forrest, C. J.; Knauer, J. P.; Marozas, J. A.; Marshall, F. J.; Radha, P. B.; Sefkow, A. B.; Marinak, M. M.

2017-10-01

In direct-drive inertial confinement fusion implosions, long-wavelength asymmetries resulting from target offset, laser power imbalance, beam mispointing, etc. can be highly detrimental to target performance. Characterizing the effects of these asymmetry sources requires 3-D simulations performed in full-sphere geometry to accurately capture the evolution of shell perturbations and hot-spot flow. This paper will present 3-D HYDRA simulations characterizing the impact of these perturbation sources on yield and shell modulation. Various simulated observables are generated, and trends are analyzed and compared with experimental data. This material is based on work supported by the Department of Energy National Nuclear Security Administration under Award Numbers DE-NA0001944 and performed under the auspices of the LLNL under Contract No. DE-AC52-07NA27344.

Shrinking microbubbles with microfluidics: mathematical modelling to control microbubble sizes.

PubMed

Salari, A; Gnyawali, V; Griffiths, I M; Karshafian, R; Kolios, M C; Tsai, S S H

2017-11-29

Microbubbles have applications in industry and life-sciences. In medicine, small encapsulated bubbles (<10 μm) are desirable because of their utility in drug/oxygen delivery, sonoporation, and ultrasound diagnostics. While there are various techniques for generating microbubbles, microfluidic methods are distinguished due to their precise control and ease-of-fabrication. Nevertheless, sub-10 μm diameter bubble generation using microfluidics remains challenging, and typically requires expensive equipment and cumbersome setups. Recently, our group reported a microfluidic platform that shrinks microbubbles to sub-10 μm diameters. The microfluidic platform utilizes a simple microbubble-generating flow-focusing geometry, integrated with a vacuum shrinkage system, to achieve microbubble sizes that are desirable in medicine, and pave the way to eventual clinical uptake of microfluidically generated microbubbles. A theoretical framework is now needed to relate the size of the microbubbles produced and the system's input parameters. In this manuscript, we characterize microbubbles made with various lipid concentrations flowing in solutions that have different interfacial tensions, and monitor the changes in bubble size along the microfluidic channel under various vacuum pressures. We use the physics governing the shrinkage mechanism to develop a mathematical model that predicts the resulting bubble sizes and elucidates the dominant parameters controlling bubble sizes. The model shows a good agreement with the experimental data, predicting the resulting microbubble sizes under different experimental input conditions. We anticipate that the model will find utility in enabling users of the microfluidic platform to engineer bubbles of specific sizes.

Experimental and computational study of the effect of 1 atm background gas on nanoparticle generation in femtosecond laser ablation of metals

NASA Astrophysics Data System (ADS)

Wu, Han; Wu, Chengping; Zhang, Nan; Zhu, Xiaonong; Ma, Xiuquan; Zhigilei, Leonid V.

2018-03-01

Laser ablation of metal targets is actively used for generation of chemically clean nanoparticles for a broad range of practical applications. The processes involved in the nanoparticle formation at all relevant spatial and temporal scales are still not fully understood, making the precise control of the size and shape of the nanoparticles challenging. In this paper, a combination of molecular dynamics simulations and experiments is applied to investigate femtosecond laser ablation of aluminum targets in vacuum and in 1 atm argon background gas. The results of the simulations reveal a strong effect of the background gas environment on the initial plume expansion and evolution of the nanoparticle size distribution. The suppression of the generation of small/medium-size Al clusters and formation of a dense layer at the front of the expanding ablation plume, observed during the first nanosecond of the plume expansion in a simulation performed in the gas environment, have important implications on the characteristics of the nanoparticles deposited on a substrate and characterized in the experiments. The nanoparticles deposited in the gas environment are found to be more round-shaped and less flattened as compared to those deposited in vacuum. The nanoparticle size distributions exhibit power-law dependences with similar values of exponents obtained from fitting experimental and simulated data. Taken together, the results of this study suggest that the gas environment may be effectively used to control size and shape of nanoparticles generated by laser ablation.

An open experimental database for exploring inorganic materials

DOE PAGES

Zakutayev, Andriy; Wunder, Nick; Schwarting, Marcus; ...

2018-04-03

The use of advanced machine learning algorithms in experimental materials science is limited by the lack of sufficiently large and diverse datasets amenable to data mining. If publicly open, such data resources would also enable materials research by scientists without access to expensive experimental equipment. Here, we report on our progress towards a publicly open High Throughput Experimental Materials (HTEM) Database (htem.nrel.gov). This database currently contains 140,000 sample entries, characterized by structural (100,000), synthetic (80,000), chemical (70,000), and optoelectronic (50,000) properties of inorganic thin film materials, grouped in >4,000 sample entries across >100 materials systems; more than a half ofmore » these data are publicly available. This article shows how the HTEM database may enable scientists to explore materials by browsing web-based user interface and an application programming interface. This paper also describes a HTE approach to generating materials data, and discusses the laboratory information management system (LIMS), that underpin HTEM database. Finally, this manuscript illustrates how advanced machine learning algorithms can be adopted to materials science problems using this open data resource.« less

An open experimental database for exploring inorganic materials.

PubMed

Zakutayev, Andriy; Wunder, Nick; Schwarting, Marcus; Perkins, John D; White, Robert; Munch, Kristin; Tumas, William; Phillips, Caleb

2018-04-03

The use of advanced machine learning algorithms in experimental materials science is limited by the lack of sufficiently large and diverse datasets amenable to data mining. If publicly open, such data resources would also enable materials research by scientists without access to expensive experimental equipment. Here, we report on our progress towards a publicly open High Throughput Experimental Materials (HTEM) Database (htem.nrel.gov). This database currently contains 140,000 sample entries, characterized by structural (100,000), synthetic (80,000), chemical (70,000), and optoelectronic (50,000) properties of inorganic thin film materials, grouped in >4,000 sample entries across >100 materials systems; more than a half of these data are publicly available. This article shows how the HTEM database may enable scientists to explore materials by browsing web-based user interface and an application programming interface. This paper also describes a HTE approach to generating materials data, and discusses the laboratory information management system (LIMS), that underpin HTEM database. Finally, this manuscript illustrates how advanced machine learning algorithms can be adopted to materials science problems using this open data resource.

An open experimental database for exploring inorganic materials

PubMed Central

Zakutayev, Andriy; Wunder, Nick; Schwarting, Marcus; Perkins, John D.; White, Robert; Munch, Kristin; Tumas, William; Phillips, Caleb

2018-01-01

The use of advanced machine learning algorithms in experimental materials science is limited by the lack of sufficiently large and diverse datasets amenable to data mining. If publicly open, such data resources would also enable materials research by scientists without access to expensive experimental equipment. Here, we report on our progress towards a publicly open High Throughput Experimental Materials (HTEM) Database (htem.nrel.gov). This database currently contains 140,000 sample entries, characterized by structural (100,000), synthetic (80,000), chemical (70,000), and optoelectronic (50,000) properties of inorganic thin film materials, grouped in >4,000 sample entries across >100 materials systems; more than a half of these data are publicly available. This article shows how the HTEM database may enable scientists to explore materials by browsing web-based user interface and an application programming interface. This paper also describes a HTE approach to generating materials data, and discusses the laboratory information management system (LIMS), that underpin HTEM database. Finally, this manuscript illustrates how advanced machine learning algorithms can be adopted to materials science problems using this open data resource. PMID:29611842

An open experimental database for exploring inorganic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakutayev, Andriy; Wunder, Nick; Schwarting, Marcus

The use of advanced machine learning algorithms in experimental materials science is limited by the lack of sufficiently large and diverse datasets amenable to data mining. If publicly open, such data resources would also enable materials research by scientists without access to expensive experimental equipment. Here, we report on our progress towards a publicly open High Throughput Experimental Materials (HTEM) Database (htem.nrel.gov). This database currently contains 140,000 sample entries, characterized by structural (100,000), synthetic (80,000), chemical (70,000), and optoelectronic (50,000) properties of inorganic thin film materials, grouped in >4,000 sample entries across >100 materials systems; more than a half ofmore » these data are publicly available. This article shows how the HTEM database may enable scientists to explore materials by browsing web-based user interface and an application programming interface. This paper also describes a HTE approach to generating materials data, and discusses the laboratory information management system (LIMS), that underpin HTEM database. Finally, this manuscript illustrates how advanced machine learning algorithms can be adopted to materials science problems using this open data resource.« less

New Experimental Models of Diabetic Nephropathy in Mice Models of Type 2 Diabetes: Efforts to Replicate Human Nephropathy

PubMed Central

Soler, María José; Riera, Marta; Batlle, Daniel

2012-01-01

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease. The use of experimental models of DN has provided valuable information regarding many aspects of DN, including pathophysiology, progression, implicated genes, and new therapeutic strategies. A large number of mouse models of diabetes have been identified and their kidney disease was characterized to various degrees. Most experimental models of type 2 DN are helpful in studying early stages of DN, but these models have not been able to reproduce the characteristic features of more advanced DN in humans such as nodules in the glomerular tuft or glomerulosclerosis. The generation of new experimental models of DN created by crossing, knockdown, or knockin of genes continues to provide improved tools for studying DN. These models provide an opportunity to search for new mechanisms involving the development of DN, but their shortcomings should be recognized as well. Moreover, it is important to recognize that the genetic background has a substantial effect on the susceptibility to diabetes and kidney disease development in the various models of diabetes. PMID:22461787

Caracterisation des contraintes residuelles engendrees par l'expansion a froid de trous dans des alliages d'aluminium

NASA Astrophysics Data System (ADS)

Lapalme, Maxime

Cold Expansion (CX) is a process which consists in plastically deforming assembly holes in metallic alloys by drawing an oversize mandrel through them. The major interference caused by the mandrel generates residual constraints around the hole. The tangential part of those constraints is beneficial for the hole fatigue life since an highly compressive zone is created which will retard fatigue cracks propagation. However, farther from this compressive zone, balancing tensile stresses are generated. The resultant of the CX process is a considerable increase in the fatigue life of the hole which has been demonstrated by the industry over the last decades. The present study objectives were the characterization of the residual stress field induced by CX and the development of a simulation method for it. The complexity of the generated stresses is increased tenfold by two main elements. First, the progressive drawing of the mandrel through the hole causes a scalable interference which produces variable stress states in the thickness of the perforated plate. Second, for easier application and productivity, the interference between the hole and the mandrel is actually caused by an interference object, the sleeve, that is rolled to a cylindrical form from a thin steel sheet. At its critical interference position, a split is opened in the sleeve which causes a non-uniform mechanical loading applied to the walls of the hole. In order to conceive a physically realistic tridimensional finite element model, laboratory measurements were first performed. The mandrel was digitized to introduce its exact shape in the model. Dimensional measurements have also helped to characterize the sleeve mechanical behavior during the CX and the effect of its split on the final hole state. These measurements and observations allowed defining the behavior of various interfaces of contact and geometries in the FE model. Characterization of the residual stress field and the validation of the simulation model of CX were performed using a variety of experimental data generated as part of this study. First, X-ray diffraction yielded measurements of stress on both sides of the sample. Then, full field planar strains were measured using digital image correlation on both sides of samples. Finally, optical measurements were carried out to determine the out-of-plane displacements at the vicinity of the hole, movement which is caused by the passage of the mandrel and the flow of material as it moves. The experimental data showed that through the thickness of a plate with a hardened hole, the residual stresses and strains are quite different, and therefore that the CX process has important three-dimensional effects. Moreover, the opening in the sleeve causes a state of nonuniform deformation on the circumference of the hole. The results of the simulation using the developed FE model show a very good correlation with the experimental data gathered for stress, strain and displacement. This comparison shows that to properly simulate the CX process, it is important to consider the exact geometry of the parts and tools as well as contacts between all of these interfaces. Following CX, the hole is generally reamed to the dimensions required for the subsequent assembly with a fastener. This machining causes a redistribution of the stress previously generated by CX. No experimental results have been collected on the impact of the reaming in the context of this study. However, a simulation method was used in the FE model to represent this last operation. The analysis shows that the reaming uniforms stress state across the thickness of the hardened sample. A validation of this observation would be necessary since the effect is significant on the final condition of the residual stresses generated by CX.

Third generation snacks manufactured from orange by-products: physicochemical and nutritional characterization.

PubMed

Tovar-Jiménez, Xochitl; Caro-Corrales, José; Gómez-Aldapa, Carlos A; Zazueta-Morales, José; Limón-Valenzuela, Víctor; Castro-Rosas, Javier; Hernández-Ávila, Juan; Aguilar-Palazuelos, Ernesto

2015-10-01

A mixture of orange vesicle flour, commercial nixtamalized corn flour and potato starch was extruded using a Brabender Laboratory single screw extruder (2:1 L/D). The resulting pellets were expanded by microwaves. Expansion index, bulk density, penetration force, carotenoid content, and dietary fiber were measured for this third-generation snack and optimum production conditions were estimated. Response surface methodology was applied using a central composite rotatable experimental design to evaluate the effect of moisture content and extrusion temperature. Temperature mainly affected the expansion index, bulk density and penetration force, while carotenoids content was affected by moisture content. Surface overlap was used to identify optimum processing conditions: temperature: 128-130 °C; moisture content: 22-24 %. Insoluble dietary fiber decreased and soluble dietary fiber increased after extrusion.

Measurement of in-plane displacements using the phase singularities generated by directional wavelet transforms of speckle pattern images.

PubMed

Vadnjal, Ana Laura; Etchepareborda, Pablo; Federico, Alejandro; Kaufmann, Guillermo H

2013-03-20

We present a method to determine micro and nano in-plane displacements based on the phase singularities generated by application of directional wavelet transforms to speckle pattern images. The spatial distribution of the obtained phase singularities by the wavelet transform configures a network, which is characterized by two quasi-orthogonal directions. The displacement value is determined by identifying the intersection points of the network before and after the displacement produced by the tested object. The performance of this method is evaluated using simulated speckle patterns and experimental data. The proposed approach is compared with the optical vortex metrology and digital image correlation methods in terms of performance and noise robustness, and the advantages and limitations associated to each method are also discussed.

Generation and Characterization of Electron Bunches with Ramped Current Profiles in a Dual-Frequency Superconducting Linear Accelerator

DOE PAGES

Piot, P.; Behrens, C.; Gerth, C.; ...

2011-09-07

We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a superconducing radiofrequency linear accelerator operating at two frequencies and a current-enhancing dispersive section. The produced {approx} 700-MeV bunches have peak currents of the order of a kilo-Ampere. Data taken for various accelerator settings demonstrate the versatility of the method and in particular its ability to produce current profiles that have a quasi-linear dependency on the longitudinal (temporal) coordinate. The measured bunch parameters are shown, via numerical simulations, to produce gigavolt-per-meter peak acceleratingmore » electric fields with transformer ratios larger than 2 in dielectric-lined waveguides.« less

Resonant Mode-hopping Micromixing

PubMed Central

Jang, Ling-Sheng; Chao, Shih-Hui; Holl, Mark R.; Meldrum, Deirdre R.

2009-01-01

A common micromixer design strategy is to generate interleaved flow topologies to enhance diffusion. However, problems with these designs include complicated structures and dead volumes within the flow fields. We present an active micromixer using a resonating piezoceramic/silicon composite diaphragm to generate acoustic streaming flow topologies. Circulation patterns are observed experimentally and correlate to the resonant mode shapes of the diaphragm. The dead volumes in the flow field are eliminated by rapidly switching from one discrete resonant mode to another (i.e., resonant mode-hop). Mixer performance is characterized by mixing buffer with a fluorescence tracer containing fluorescein. Movies of the mixing process are analyzed by converting fluorescent images to two-dimensional fluorescein concentration distributions. The results demonstrate that mode-hopping operation rapidly homogenized chamber contents, circumventing diffusion-isolated zones. PMID:19551159

Generation and characterization of electron bunches with ramped current profiles in a dual-frequency superconducting linear accelerator.

PubMed

Piot, P; Behrens, C; Gerth, C; Dohlus, M; Lemery, F; Mihalcea, D; Stoltz, P; Vogt, M

2012-01-20

We report on the successful experimental generation of electron bunches with ramped current profiles. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a superconducing radio frequency linear accelerator operating at two frequencies and a current-enhancing dispersive section. The produced ~700-MeV bunches have peak currents of the order of a kilo-Ampère. Data taken for various accelerator settings demonstrate the versatility of the method and, in particular, its ability to produce current profiles that have a quasilinear dependency on the longitudinal (temporal) coordinate. The measured bunch parameters are shown, via numerical simulations, to produce gigavolt-per-meter peak accelerating electric fields with transformer ratios larger than 2 in dielectric-lined waveguides. © 2012 American Physical Society

Reversed Cherenkov emission of terahertz waves from an ultrashort laser pulse in a sandwich structure with nonlinear core and left-handed cladding.

PubMed

Bakunov, M I; Mikhaylovskiy, R V; Bodrov, S B; Luk'yanchuk, B S

2010-01-18

We propose a scheme for an experimental verification of the reversed Cherenkov effect in left-handed media. The scheme uses optical-to-terahertz conversion in a planar sandwichlike structure that consists of a nonlinear core cladded with a material that exhibits left-handedness at terahertz frequencies. The focused into a line femtosecond laser pulse propagates in the core and emits Cherenkov wedge of terahertz waves in the cladding. We developed a theory that describes terahertz generation in such a structure and calculated spatial distribution of the generated terahertz field, its energy spectrum, and optical-to-terahertz conversion efficiency. The proposed structure can be a useful tool for characterization of the electromagnetic properties of metamaterials in the terahertz frequency range.

Development of hierarchical structures for actions and motor imagery: a constructivist view from synthetic neuro-robotics study.

PubMed

Nishimoto, Ryunosuke; Tani, Jun

2009-07-01

The current paper shows a neuro-robotics experiment on developmental learning of goal-directed actions. The robot was trained to predict visuo-proprioceptive flow of achieving a set of goal-directed behaviors through iterative tutor training processes. The learning was conducted by employing a dynamic neural network model which is characterized by their multiple time-scale dynamics. The experimental results showed that functional hierarchical structures emerge through stages of developments where behavior primitives are generated in earlier stages and their sequences of achieving goals appear in later stages. It was also observed that motor imagery is generated in earlier stages compared to actual behaviors. Our claim that manipulatable inner representation should emerge through the sensory-motor interactions is corresponded to Piaget's constructivist view.

Ultrasonic Nondestructive Characterization of Porous Materials

NASA Astrophysics Data System (ADS)

Yang, Ningli

2011-12-01

Wave propagation in porous media is studied in a wide range of technological applications. In the manufacturing industry, determining porosity of materials in the manufacturing process is required for strict quality control. In the oil industry, acoustic signals and seismic surveys are used broadly to determine the physical properties of the reservoir rock which is a porous media filled with oil or gas. In porous noise control materials, a precise prediction of sound absorption with frequency and evaluation of tortuosity are necessary. Ultrasonic nondestructive methods are a very important tool for characterization of porous materials. The dissertation deals with two types of porous media: materials with relatively low and closed porosity and materials with comparatively high and open porosity. Numerical modeling, Finite Element simulations and experimental characterization are all discussed in this dissertation. First, ultrasonic scattering is used to determine the porosity in porous media with closed pores. In order get a relationship between the porosity in porous materials and ultrasonic scattering independently and to increase the sensitivity to obtain scattering information, ultrasonic imaging methods are applied and acoustic waves are focused by an acoustic lens. To verify the technique, engineered porous acrylic plates with varying porosity are measured by ultrasonic scanning and ultrasonic array sensors. Secondly, a laser based ultrasonic technique is explored for predicting the mechanical integrity and durability of cementitious materials. The technique used involves the measurement of the phase velocity of fast and slow longitudinal waves in water saturated cement paste. The slow wave velocity is related to the specimen's tortuosity. The fast wave speed is dependent on the elastic properties of porous solid. Experimental results detailing the generation and detection of fast and slow wave waves in freshly prepared and aged water-saturated cement samples with varying water-to-cement ratios are presented in the dissertation. The third part concerns the ultrasonic characterization of air-saturated porous materials. Using airborne reflected and transmitted ultrasonic experimental data, the open porosity and tortuosity value of a porous acrylic plate with graded void content and a polyimide foam are determined simultaneously. Experimental and numerical results of the method are presented.

Integrated Sources of Polarization Entangled Photon Pair States via Spontaneous Four-Wave Mixing in AlGaAs Waveguides

NASA Astrophysics Data System (ADS)

Kultavewuti, Pisek

Polarization-entangled photon pair states (PESs) are indispensable in several quantum protocols that should be implemented in an integrated photonic circuit for realizing a practical quantum technology. Preparing such states in integrated waveguides is in fact a challenge due to polarization mode dispersion. Unlike other conventional ways that are plagued with complications in fabrication or in state generation, in this thesis, the scheme based on parallel spontaneous four-wave mixing processes of two polarization waveguide modes is thoroughly studied in theory and experimentation for the polarization entanglement generation. The scheme in fact needs the modal dispersion, contradictory to the general perception, as revealed by a full quantum mechanical framework. The proper modal dispersion balances the effects of temporal walk-off and state factorizability. The study also shows that the popular standard platform such as a silicon-on-insulator wafer is far from suitable to implement the proposed simple generation technique. Proven by the quantum state tomography, the technique produces a highly-entangled state with a maximum concurrence of 0.97 +/- 0:01 from AlGaAs waveguides. In addition, the devices directly generated Bell states with an observed fidelity of 0.92 +/- 0:01 without any post-generation compensating steps. Novel suspended device structures, including their components, are then investigated numerically and experimentally characterized in pursuit of finding the geometry with the optimal dispersion property. The 700 nm x 1100 nm suspended rectangular waveguide is identified as the best geometry with a predicted maximum concurrence of 0.976 and a generation bandwidth of 3.3 THz. The suspended waveguide fabrication procedure adds about 15 dB/cm and 10 dB/cm of propagation loss to the TE and TM mode respectively, on top of the loss in corresponding full-cladding waveguides. Bridges, which structurally support the suspended waveguides, are optimized using the particle swarm algorithm to maximize the power transmission, and they were experimentally verified. This work greatly simplifies the generation of the PES and identifies a novel device structure suitable for such the PES generation. In combination with the reported promising advances in interferometric components and single photon detectors implemented in AlGaAs, the result of this thesis represents a step toward realizing a complete integrated quantum photonic circuit empowered by polarization-based protocols.

Study of guided wave propagation on a plate between two solid bodies with imperfect contact conditions.

PubMed

Balvantín, A J; Diosdado-De-la-Peña, J A; Limon-Leyva, P A; Hernández-Rodríguez, E

2018-02-01

In this work, fundamental symmetric Lamb wave S0 mode is characterized in terms of its velocity variation as function of the interfacial conditions between solid bodies in contact. Imperfect contact conditions are numerically and experimentally determined by using ultrasonic Lamb wave propagation parameters. For the study, an experimental system was used, formed by two solid aluminum rods (25.4mm in diameter) axially loading a thin aluminum plate to control contact interfacial stiffness. The axially applied load on the aluminum plate was varied from 0MPa to 10MPa. Experimental Lamb wave signals were excited on the plate through two longitudinal contact transducers (1MHz of central frequency) using a pitch-catch configuration. Numerical simulations of contact conditions and Lamb wave propagation were performed through Finite Element Analysis (FEA) in commercial software, ANSYS 15®. Simulated Lamb wave signals were generated by means of a 5 cycles tone burst signals with different frequency values. Results indicate a velocity change in both, experimental and simulated Lamb wave signals as function of the applied load. Finally, a comparison between numerical results and experimental measurements was performed obtaining a good agreement. Copyright © 2017 Elsevier B.V. All rights reserved.

Use of SRIM and Garfield with Geant4 for the characterization of a hybrid 10B/3He neutron detector

NASA Astrophysics Data System (ADS)

van der Ende, B. M.; Rand, E. T.; Erlandson, A.; Li, L.

2018-06-01

This paper describes a method for more complete neutron detector characterization using Geant4's Monte Carlo methods for characterizing overall detector response rate and Garfield interfaced with SRIM for the simulation of the detector's raw pulses, as applied to a hybrid 10B/3He detector. The Geant4 models characterizing the detector's interaction with a 252Cf point source and parallel beams of mono-energetic neutrons (assuming ISO 8529 reference energy values) compare and agree well with calibrated 252Cf measurements to within 6.4%. Validated Geant4 model outputs serve as input to Garfield+SRIM calculations to provide meaningful pulse height spectra. Modifications to Garfield for this work were necessary to account for simultaneous tracking of electrons resulting from proton and triton reaction products from a single 3He neutron capture event, and it was further necessary to interface Garfield with the energy loss, range, and straggling calculations provided by SRIM. Individual raw pulses generated by Garfield+SRIM are also observed to agree well with experimentally measured raw pulses from the detector.

Hurdles and sorting by inversions: combinatorial, statistical, and experimental results.

PubMed

Swenson, Krister M; Lin, Yu; Rajan, Vaibhav; Moret, Bernard M E

2009-10-01

As data about genomic architecture accumulates, genomic rearrangements have attracted increasing attention. One of the main rearrangement mechanisms, inversions (also called reversals), was characterized by Hannenhalli and Pevzner and this characterization in turn extended by various authors. The characterization relies on the concepts of breakpoints, cycles, and obstructions colorfully named hurdles and fortresses. In this paper, we study the probability of generating a hurdle in the process of sorting a permutation if one does not take special precautions to avoid them (as in a randomized algorithm, for instance). To do this we revisit and extend the work of Caprara and of Bergeron by providing simple and exact characterizations of the probability of encountering a hurdle in a random permutation. Using similar methods we provide the first asymptotically tight analysis of the probability that a fortress exists in a random permutation. Finally, we study other aspects of hurdles, both analytically and through experiments: when are they created in a sequence of sorting inversions, how much later are they detected, and how much work may need to be undone to return to a sorting sequence.

High strain rate characterization of soft materials: past, present and possible futures

NASA Astrophysics Data System (ADS)

Siviour, Clive

2015-06-01

The high strain rate properties of low impedance materials have long been of interest to the community: the very first paper by Kolsky on his eponymous bars included data from man-made polymers and natural rubber. However, it has also long been recognized that characterizing soft or low impedance specimens under dynamic loading presents a number of challenges, mainly owing to the low sound speed in, and low stresses supported by, these materials. Over the past 20 years, significant progress has been made in high rate testing techniques, including better experimental design, more sensitive data acquisition and better understanding of specimen behavior. Further, a new generation of techniques, in which materials are characterized using travelling waves, rather than in a state of static equilibrium, promise to turn those properties that were previously a drawback into an advantage. This paper will give an overview of the history of high rate characterization, the current state of the art after an exciting couple of decades and some of the techniques currently being developed that have the potential to offer increased quality data in the future.

Study to perform preliminary experiments to evaluate particle generation and characterization techniques for zero-gravity cloud physics experiments

NASA Technical Reports Server (NTRS)

Katz, U.

1982-01-01

Methods of particle generation and characterization with regard to their applicability for experiments requiring cloud condensation nuclei (CCN) of specified properties were investigated. Since aerosol characterization is a prerequisite to assessing performance of particle generation equipment, techniques for characterizing aerosol were evaluated. Aerosol generation is discussed, and atomizer and photolytic generators including preparation of hydrosols (used with atomizers) and the evaluation of a flight version of an atomizer are studied.

Structure, IR and Raman spectra of phosphotrihydrazide studied by DFT

NASA Astrophysics Data System (ADS)

Furer, V. L.; Vandyukov, A. E.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

2016-09-01

The FTIR and FT Raman measurements of the phosphotrihydrazide (S)P[N(Me)-NH2]3 have been performed. This compound is a zero generation dendrimer G0 with terminal amine groups. Structural optimization and normal mode analysis were obtained for G0 by the density functional theory (DFT). Optimized geometric bond length and angles obtained by DFT show good agreement with experiment. The amine terminal groups are characterized by the well-defined bands at 3321, 3238, 1614 cm- 1 in the experimental IR spectrum and by bands at 3327, 3241 cm- 1 in the Raman spectrum of G0. The experimental frequencies of asymmetric and symmetric NH2 stretching vibrations of amine group are lower than theoretical values due to intramolecular Nsbnd H ⋯ S hydrogen bond. This hydrogen bond is also responsible for higher experimental infrared intensity of these bands as compared with theoretical values. Relying on DFT calculations a complete vibrational assignment is proposed for the studied dendrimer.

Microstructural evolution of type 304 and 316 stainless steels under neutron irradiation at LWR relevant conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lizhen; Stoller, Roger E.; Field, Kevin G.

Extension of light water reactors' useful life will expose austenitic internal core components to irradiation damage levels beyond 100 displacements per atom (dpa), which will lead to profound microstructural evolution and consequent degradation of macroscopic properties. Microstructural evolution, including Frank loops, cavities, precipitates, and segregation at boundaries and the resultant radiation hardening in type 304 and 316 stainless steel (SS) variants, were studied in this work via experimental characterization and multiple simulation methods. Experimental data for up to 40 heats of type 304SS and 316SS variants irradiated in different reactors to 0.6–120 dpa at 275–375°C were either generated from thismore » work or collected from literature reports. These experimental data were then combined with models of Frank loop and cavity evolution, computational thermodynamics and precipitation, and ab initio and rate theory integrated radiation-induced segregation models to provide insights into microstructural evolution and degradation at higher radiation doses.« less

Microstructural evolution of type 304 and 316 stainless steels under neutron irradiation at LWR relevant conditions

DOE PAGES

Tan, Lizhen; Stoller, Roger E.; Field, Kevin G.; ...

2015-12-11

Extension of light water reactors' useful life will expose austenitic internal core components to irradiation damage levels beyond 100 displacements per atom (dpa), which will lead to profound microstructural evolution and consequent degradation of macroscopic properties. Microstructural evolution, including Frank loops, cavities, precipitates, and segregation at boundaries and the resultant radiation hardening in type 304 and 316 stainless steel (SS) variants, were studied in this work via experimental characterization and multiple simulation methods. Experimental data for up to 40 heats of type 304SS and 316SS variants irradiated in different reactors to 0.6–120 dpa at 275–375°C were either generated from thismore » work or collected from literature reports. These experimental data were then combined with models of Frank loop and cavity evolution, computational thermodynamics and precipitation, and ab initio and rate theory integrated radiation-induced segregation models to provide insights into microstructural evolution and degradation at higher radiation doses.« less

An Experimental Study of the Influence of in-Plane Fiber Waviness on Unidirectional Laminates Tensile Properties

NASA Astrophysics Data System (ADS)

Zhao, Cong; Xiao, Jun; Li, Yong; Chu, Qiyi; Xu, Ting; Wang, Bendong

2017-12-01

As one of the most common process induced defects of automated fiber placement, in-plane fiber waviness and its influences on mechanical properties of fiber reinforced composite lack experimental studies. In this paper, a new approach to prepare the test specimen with in-plane fiber waviness is proposed in consideration of the mismatch between the current test standard and actual fiber trajectory. Based on the generation mechanism of in-plane fiber waviness during automated fiber placement, the magnitude of in-plane fiber waviness is characterized by axial compressive strain of prepreg tow. The elastic constants and tensile strength of unidirectional laminates with in-plane fiber waviness are calculated by off-axis and maximum stress theory. Experimental results show that the tensile properties infade dramatically with increasing magnitude of the waviness, in good agreement with theoretical analyses. When prepreg tow compressive strain reaches 1.2%, the longitudinal tensile modulus and strength of unidirectional laminate decreased by 25.5% and 57.7%, respectively.

Electret accelerometers: physics and dynamic characterization.

PubMed

Hillenbrand, J; Haberzettl, S; Motz, T; Sessler, G M

2011-06-01

Electret microphones are produced in numbers that significantly exceed those for all other microphone types. This is due to the fact that air-borne electret sensors are of simple and low-cost design but have very good acoustical properties. In contrast, most of the discrete structure-borne sound sensors (or accelerometers) are based on the piezoelectric effect. In the present work, capacitive accelerometers utilizing the electret principle were constructed, built, and characterized. These electret accelerometers comprise a metallic seismic mass, covered by an electret film, a ring of a soft cellular polymer supplying the restoring force, and a metallic backplate. These components replace membrane, spacer, and back electrode, respectively, of the electret microphone. An adjustable static pressure to the seismic mass is generated by two metal springs. The dynamic characterization of the accelerometers was carried out by using an electrodynamic shaker and an external charge or voltage amplifier. Sensors with various seismic masses, air gap distances, and electret voltages were investigated. Charge sensitivities from 10 to 40 pC/g, voltage sensitivities from 600 to 2000 mV/g, and resonance frequencies from 3 to 1.5 kHz were measured. A model describing both the charge and the voltage sensitivity is presented. Good agreement of experimental and calculated values is found. The experimental results show that sensitive, lightweight, and inexpensive electret accelerometers can be built. © 2011 Acoustical Society of America

Formulation, optimization and characterization of cationic polymeric nanoparticles of mast cell stabilizing agent using the Box-Behnken experimental design.

PubMed

Gajra, Balaram; Patel, Ravi R; Dalwadi, Chintan

2016-01-01

The present research work was intended to develop and optimize sustained release of biodegradable chitosan nanoparticles (CSNPs) as delivery vehicle for sodium cromoglicate (SCG) using the circumscribed Box-Behnken experimental design (BBD) and evaluate its potential for oral permeability enhancement. The 3-factor, 3-level BBD was employed to investigate the combined influence of formulation variables on particle size and entrapment efficiency (%EE) of SCG-CSNPs prepared by ionic gelation method. The generated polynomial equation was validated and desirability function was utilized for optimization. Optimized SCG-CSNPs were evaluated for physicochemical, morphological, in-vitro characterizations and permeability enhancement potential by ex-vivo and uptake study using CLSM. SCG-CSNPs exhibited particle size of 200.4 ± 4.06 nm and %EE of 62.68 ± 2.4% with unimodal size distribution having cationic, spherical, smooth surface. Physicochemical and in-vitro characterization revealed existence of SCG in amorphous form inside CSNPs without interaction and showed sustained release profile. Ex-vivo and uptake study showed the permeability enhancement potential of CSNPs. The developed SCG-CSNPs can be considered as promising delivery strategy with respect to improved permeability and sustained drug release, proving importance of CSNPs as potential oral delivery system for treatment of allergic rhinitis. Hence, further studies should be performed for establishing the pharmacokinetic potential of the CSNPs.

Design and Initial Characterization of the SC-200 Proteomics Standard Mixture

PubMed Central

Bauman, Andrew; Higdon, Roger; Rapson, Sean; Loiue, Brenton; Hogan, Jason; Stacy, Robin; Napuli, Alberto; Guo, Wenjin; van Voorhis, Wesley; Roach, Jared; Lu, Vincent; Landorf, Elizabeth; Stewart, Elizabeth; Kolker, Natali; Collart, Frank; Myler, Peter; van Belle, Gerald

2011-01-01

Abstract High-throughput (HTP) proteomics studies generate large amounts of data. Interpretation of these data requires effective approaches to distinguish noise from biological signal, particularly as instrument and computational capacity increase and studies become more complex. Resolving this issue requires validated and reproducible methods and models, which in turn requires complex experimental and computational standards. The absence of appropriate standards and data sets for validating experimental and computational workflows hinders the development of HTP proteomics methods. Most protein standards are simple mixtures of proteins or peptides, or undercharacterized reference standards in which the identity and concentration of the constituent proteins is unknown. The Seattle Children's 200 (SC-200) proposed proteomics standard mixture is the next step toward developing realistic, fully characterized HTP proteomics standards. The SC-200 exhibits a unique modular design to extend its functionality, and consists of 200 proteins of known identities and molar concentrations from 6 microbial genomes, distributed into 10 molar concentration tiers spanning a 1,000-fold range. We describe the SC-200's design, potential uses, and initial characterization. We identified 84% of SC-200 proteins with an LTQ-Orbitrap and 65% with an LTQ-Velos (false discovery rate = 1% for both). There were obvious trends in success rate, sequence coverage, and spectral counts with protein concentration; however, protein identification, sequence coverage, and spectral counts vary greatly within concentration levels. PMID:21250827

Design and initial characterization of the SC-200 proteomics standard mixture.

PubMed

Bauman, Andrew; Higdon, Roger; Rapson, Sean; Loiue, Brenton; Hogan, Jason; Stacy, Robin; Napuli, Alberto; Guo, Wenjin; van Voorhis, Wesley; Roach, Jared; Lu, Vincent; Landorf, Elizabeth; Stewart, Elizabeth; Kolker, Natali; Collart, Frank; Myler, Peter; van Belle, Gerald; Kolker, Eugene

2011-01-01

High-throughput (HTP) proteomics studies generate large amounts of data. Interpretation of these data requires effective approaches to distinguish noise from biological signal, particularly as instrument and computational capacity increase and studies become more complex. Resolving this issue requires validated and reproducible methods and models, which in turn requires complex experimental and computational standards. The absence of appropriate standards and data sets for validating experimental and computational workflows hinders the development of HTP proteomics methods. Most protein standards are simple mixtures of proteins or peptides, or undercharacterized reference standards in which the identity and concentration of the constituent proteins is unknown. The Seattle Children's 200 (SC-200) proposed proteomics standard mixture is the next step toward developing realistic, fully characterized HTP proteomics standards. The SC-200 exhibits a unique modular design to extend its functionality, and consists of 200 proteins of known identities and molar concentrations from 6 microbial genomes, distributed into 10 molar concentration tiers spanning a 1,000-fold range. We describe the SC-200's design, potential uses, and initial characterization. We identified 84% of SC-200 proteins with an LTQ-Orbitrap and 65% with an LTQ-Velos (false discovery rate = 1% for both). There were obvious trends in success rate, sequence coverage, and spectral counts with protein concentration; however, protein identification, sequence coverage, and spectral counts vary greatly within concentration levels.

Measurements and modeling of the impact of weak magnetic fields on the plasma properties of a planar slot antenna driven plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshikawa, Jun, E-mail: jun.yoshikawa@tel.com; Susa, Yoshio; Ventzek, Peter L. G.

The radial line slot antenna plasma source is a type of surface wave plasma source driven by a planar slot antenna. Microwave power is transmitted through a slot antenna structure and dielectric window to a plasma characterized by a generation zone adjacent to the window and a diffusion zone that contacts a substrate. The diffusion zone is characterized by a very low electron temperature. This renders the source useful for soft etch applications and thin film deposition processes requiring low ion energy. Another property of the diffusion zone is that the plasma density tends to decrease from the axis tomore » the walls under the action of ambipolar diffusion at distances far from where the plasma is generated. A previous simulation study [Yoshikawa and. Ventzek, J. Vac. Sci. Technol. A 31, 031306 (2013)] predicted that the anisotropy in transport parameters due to weak static magnetic fields less than 50 G could be leveraged to manipulate the plasma profile in the radial direction. These simulations motivated experimental tests in which weak magnetic fields were applied to a radial line slot antenna source. Plasma absorption probe measurements of electron density and etch rate showed that the magnetic fields remote from the wafer were able to manipulate both parameters. A summary of these results is presented in this paper. Argon plasma simulation trends are compared with experimental plasma and etch rate measurements. A test of the impact of magnetic fields on charge up damage showed no perceptible negative effect.« less

Characterization and damage evaluation of advanced materials

NASA Astrophysics Data System (ADS)

Mitrovic, Milan

Mechanical characterization of advanced materials, namely magnetostrictive and graphite/epoxy composite materials, is studied in this dissertation, with an emphasis on damage evaluation of composite materials. Consequently, the work in this dissertation is divided into two parts, with the first part focusing on characterization of the magneto-elastic response of magnetostrictlve materials, while the second part of this dissertation describes methods for evaluating the fatigue damage in composite materials. The objective of the first part of this dissertation is to evaluate a nonlinear constitutive relation which more closely depict the magneto-elastic response of magnetostrictive materials. Correlation between experimental and theoretical values indicate that the model adequately predicts the nonlinear strain/field relations in specific regimes, and that the currently employed linear approaches are inappropriate for modeling the response of this material in a structure. The objective of the second part of this dissertation is to unravel the complexities associated with damage events associated with polymeric composite materials. The intent is to characterize and understand the influence of impact and fatigue induced damage on the residual thermo-mechanical properties and compressive strength of composite systems. The influence of fatigue generated matrix cracking and micro-delaminations on thermal expansion coefficient (TEC) and compressive strength is investigated for woven graphite/epoxy composite system. Experimental results indicate that a strong correlation exists between TEC and compressive strength measurements, indicating that TEC measurements can be used as a damage metric for this material systems. The influence of delaminations on the natural frequencies and mode shapes of a composite laminate is also investigated. Based on the changes of these parameters as a function of damage, a methodology for determining the size and location of damage is suggested. Finally, the influence of loading parameters on impact damage growth is investigated experimentally though constant amplitude and spectrum loading fatigue tests. Based on observed impact damage growth during these tests it is suggested that the low load levels can be deleted from the standardized test sequence without significant influence on impact damage propagation.

Impact of pentacene film thickness on the photoresponse spectra: Determination of the photocarrier generation mechanism

NASA Astrophysics Data System (ADS)

Gorgolis, S.; Giannopoulou, A.; Anastassopoulos, D.; Kounavis, P.

2012-07-01

Photocurrent response, optical absorption, and x-ray diffraction (XRD) measurements in pentacene films grown on glass substrates are performed in order to obtain an insight into the mobile photocarriers generation mechanism. For film thickness of the order of 50 nm and lower, the photocurrent response spectra are found to follow the optical absorption spectra demonstrating the so-called symbatic response. Upon increasing the film thickness, the photoresponse demonstrates a transition to the so-called antibatic response, which is characterized by a maximum and minimum photocurrent for photon energies of minimum and maximum optical absorption, respectively. The experimental results are not in accordance with the model of important surface recombination rate. By taking into account the XRD patterns, the experimental photoresponse spectra can be reproduced by model simulations assuming efficient exciton dissociation at a narrow layer of the order of 20 nm near the pentacene-substrate interface. The simulated spectra are found sensitive to the film thickness, the absolute optical absorption coefficient, and the diffusion exciton length. By comparing the experimental with the simulated spectra, it is deduced that the excitons, which are created by optical excitation in the spectral region of 1.7-2.2 eV, diffuse with a diffusion length of the order of 10-80 nm to the pentacene-substrate interface where efficiently dissociate into mobile charge carriers.

A comprehensive transcript index of the human genome generated using microarrays and computational approaches

PubMed Central

Schadt, Eric E; Edwards, Stephen W; GuhaThakurta, Debraj; Holder, Dan; Ying, Lisa; Svetnik, Vladimir; Leonardson, Amy; Hart, Kyle W; Russell, Archie; Li, Guoya; Cavet, Guy; Castle, John; McDonagh, Paul; Kan, Zhengyan; Chen, Ronghua; Kasarskis, Andrew; Margarint, Mihai; Caceres, Ramon M; Johnson, Jason M; Armour, Christopher D; Garrett-Engele, Philip W; Tsinoremas, Nicholas F; Shoemaker, Daniel D

2004-01-01

Background Computational and microarray-based experimental approaches were used to generate a comprehensive transcript index for the human genome. Oligonucleotide probes designed from approximately 50,000 known and predicted transcript sequences from the human genome were used to survey transcription from a diverse set of 60 tissues and cell lines using ink-jet microarrays. Further, expression activity over at least six conditions was more generally assessed using genomic tiling arrays consisting of probes tiled through a repeat-masked version of the genomic sequence making up chromosomes 20 and 22. Results The combination of microarray data with extensive genome annotations resulted in a set of 28,456 experimentally supported transcripts. This set of high-confidence transcripts represents the first experimentally driven annotation of the human genome. In addition, the results from genomic tiling suggest that a large amount of transcription exists outside of annotated regions of the genome and serves as an example of how this activity could be measured on a genome-wide scale. Conclusions These data represent one of the most comprehensive assessments of transcriptional activity in the human genome and provide an atlas of human gene expression over a unique set of gene predictions. Before the annotation of the human genome is considered complete, however, the previously unannotated transcriptional activity throughout the genome must be fully characterized. PMID:15461792

Scattering of circumferential waves in a cracked annulus

NASA Astrophysics Data System (ADS)

Valle, Christine; Qu, Jianmin; Jacobs, Laurence J.

2000-05-01

This paper considers guided waves propagating in the circumferential direction of an annulus with a radial crack, with the objective of developing an ultrasonic technique that can detect and characterize these cracks. Specifically, the finite element method is used to simulate the propagation and scattering of guided circumferential waves in a cracked annulus. This method fosters a better understanding of the wave fields, so that a transducer configuration used in the field can be optimized for crack detection/characterization. Both a point source (simulating laser generated ultrasound) and a distributed source (simulating a PZT transducer) are modeled and compared to corresponding experimental results. Animations (snapshots at different instants in time) of the strain energy field in the annulus are given for various combinations of load profiles, incident angles, and incident frequencies. Results of this paper provide the necessary design guidelines for developing nondestructive ultrasonic techniques for the detection/characterization of radial cracks in cylindrical pressure vessels, gas/oil pipes, and shaft/bearing systems.

Indirect Reconstruction of Pore Morphology for Parametric Computational Characterization of Unidirectional Porous Iron.

PubMed

Kovačič, Aljaž; Borovinšek, Matej; Vesenjak, Matej; Ren, Zoran

2018-01-26

This paper addresses the problem of reconstructing realistic, irregular pore geometries of lotus-type porous iron for computer models that allow for simple porosity and pore size variation in computational characterization of their mechanical properties. The presented methodology uses image-recognition algorithms for the statistical analysis of pore morphology in real material specimens, from which a unique fingerprint of pore morphology at a certain porosity level is derived. The representative morphology parameter is introduced and used for the indirect reconstruction of realistic and statistically representative pore morphologies, which can be used for the generation of computational models with an arbitrary porosity. Such models were subjected to parametric computer simulations to characterize the dependence of engineering elastic modulus on the porosity of lotus-type porous iron. The computational results are in excellent agreement with experimental observations, which confirms the suitability of the presented methodology of indirect pore geometry reconstruction for computational simulations of similar porous materials.

Isolation and genomic characterization of gosling gout caused by a novel goose astrovirus.

PubMed

Yang, Jing; Tian, Jiajun; Tang, Yi; Diao, Youxiang

2018-06-19

A severe infectious disease characterized with gout, haemorrhage and swellings of kidneys has affected goslings around the major goose-producing regions in China since November 2016. A Novel goose-origin astrovirus (AStV), designated as AStV/SDPY/Goose/1116/17 (AStV-SDPY) strain, was isolated from diseased goslings, and experimental reproduction of gout was successful using the AStV-SDPY strain. Additionally, the AStV-SDPY was conducted for its full genome sequencing characterization using next-generation sequencing (NGS) technique on Illumina HiSeq platform. A complete genome of the AStV-SDPY was 7,252 nt in length and encoded three viral proteins. Phylogenetic analysis revealed that AStV-SDPY strain belongs to an independent branch of avian astroviruses, and the nucleotide homology among AStV-SDPY and other classic avian astrovirus strains was only 48.8%-68.2%. Results of above data indicated the causative agent of the gosling gout occurring in China is a novel divergent goose astrovirus. © 2018 Blackwell Verlag GmbH.

Complementarity As Generative Principle: A Thought Pattern for Aesthetic Appreciations and Cognitive Appraisals in General

PubMed Central

Bao, Yan; von Stosch, Alexandra; Park, Mona; Pöppel, Ernst

2017-01-01

In experimental aesthetics the relationship between the arts and cognitive neuroscience has gained particular interest in recent years. But has cognitive neuroscience indeed something to offer when studying the arts? Here we present a theoretical frame within which the concept of complementarity as a generative or creative principle is proposed; neurocognitive processes are characterized by the duality of complementary activities like bottom-up and top-down control, or logistical functions like temporal control and content functions like perceptions in the neural machinery. On that basis a thought pattern is suggested for aesthetic appreciations and cognitive appraisals in general. This thought pattern is deeply rooted in the history of philosophy and art theory since antiquity; and complementarity also characterizes neural operations as basis for cognitive processes. We then discuss some challenges one is confronted with in experimental aesthetics; in our opinion, one serious problem is the lack of a taxonomy of functions in psychology and neuroscience which is generally accepted. This deficit makes it next to impossible to develop acceptable models which are similar to what has to be modeled. Another problem is the severe language bias in this field of research as knowledge gained in many languages over the ages remains inaccessible to most scientists. Thus, an inspection of research results or theoretical concepts is necessarily too narrow. In spite of these limitations we provide a selective summary of some results and viewpoints with a focus on visual art and its appreciation. It is described how questions of art and aesthetic appreciations using behavioral methods and in particular brain-imaging techniques are analyzed and evaluated focusing on such issues like the representation of artwork or affective experiences. Finally, we emphasize complementarity as a generative principle on a practical level when artists and scientists work directly together which can lead to new insights and broader perspectives on both sides. PMID:28536548

Complementarity As Generative Principle: A Thought Pattern for Aesthetic Appreciations and Cognitive Appraisals in General.

PubMed

Bao, Yan; von Stosch, Alexandra; Park, Mona; Pöppel, Ernst

2017-01-01

In experimental aesthetics the relationship between the arts and cognitive neuroscience has gained particular interest in recent years. But has cognitive neuroscience indeed something to offer when studying the arts? Here we present a theoretical frame within which the concept of complementarity as a generative or creative principle is proposed; neurocognitive processes are characterized by the duality of complementary activities like bottom-up and top-down control, or logistical functions like temporal control and content functions like perceptions in the neural machinery. On that basis a thought pattern is suggested for aesthetic appreciations and cognitive appraisals in general. This thought pattern is deeply rooted in the history of philosophy and art theory since antiquity; and complementarity also characterizes neural operations as basis for cognitive processes. We then discuss some challenges one is confronted with in experimental aesthetics; in our opinion, one serious problem is the lack of a taxonomy of functions in psychology and neuroscience which is generally accepted. This deficit makes it next to impossible to develop acceptable models which are similar to what has to be modeled. Another problem is the severe language bias in this field of research as knowledge gained in many languages over the ages remains inaccessible to most scientists. Thus, an inspection of research results or theoretical concepts is necessarily too narrow. In spite of these limitations we provide a selective summary of some results and viewpoints with a focus on visual art and its appreciation. It is described how questions of art and aesthetic appreciations using behavioral methods and in particular brain-imaging techniques are analyzed and evaluated focusing on such issues like the representation of artwork or affective experiences. Finally, we emphasize complementarity as a generative principle on a practical level when artists and scientists work directly together which can lead to new insights and broader perspectives on both sides.

A novel embeddable spherical smart aggregate for structural health monitoring: part I. Fabrication and electrical characterization

NASA Astrophysics Data System (ADS)

Kong, Qingzhao; Fan, Shuli; Bai, Xiaolong; Mo, Y. L.; Song, Gangbing

2017-09-01

Recently developed piezoceramic-based transducers, known as smart aggregates (SAs), have shown their applicability and versatility in various applications of structural health monitoring (SHM). The lead zirconate titanate (PZT) patches embedded inside SAs have different modes that are more suitable for generating or receiving different types of stress waves (e.g. P and S waves, each of which has a unique role in SHM). However, due to the geometry of the 2D PZT patch, the embedded SA can only generate or receive the stress wave in a single direction and thus greatly limits its applications. This paper is the first of a series of two companion papers that introduces the authors’ latest work in developing a novel, embeddable spherical smart aggregate (SSA) for the health monitoring of concrete structures. In addition to the 1D guided wave produced by SA, the SSA embedded in concrete structures can generate or receive omni-directional stress waves that can significantly improve the detection aperture and provide additional functionalities in SHM. In the first paper (Part I), the detailed fabrication procedures with the help of 3D printing technology and electrical characterization of the proposed SSA is presented. The natural frequencies of the SSA were experimentally obtained and further compared with the numerical results. In addition, the influence of the components’ thickness (spherical piezoceramic shell and epoxy) and outer radius (spherical piezoceramic shell and protection concrete) on the natural frequencies of the SSA were analytically studied. The results will help elucidate the key parameters that determine the natural frequencies of the SSA. The natural frequencies of the SSA can thus be designed for suitability in the damage detection of concrete structures. In the second paper (Part II), further numerical and experimental verifications on the performance of the proposed SSA in concrete structures will be discussed.

Plasmonic trapping potentials for cold atoms

NASA Astrophysics Data System (ADS)

Mildner, Matthias; Horrer, Andreas; Fleischer, Monika; Zimmermann, Claus; Slama, Sebastian

2018-07-01

This paper reports on conceptual and experimental work towards the realization of plasmonic surface traps for cold atoms. The trapping mechanism is based on the combination of a repulsive and an attractive potential generated by evanescent light waves that are plasmonically enhanced. The strength of enhancement can be locally manipulated via the thickness of a metal nanolayer deposited on top of a dielectric substrate. Thus, in principle the trapping geometry can be predefined by the metal layer design. We present simulations of a plasmonic lattice potential using a gold grating with sinusoidally modulated thickness. Experimentally, a first plasmonic test structure is presented and characterized. Furthermore, the surface potential landscape is detected by reflecting ultracold atom clouds from the test structure revealing the influence of both evanescent waves. A parameter range is identified where stable traps can be expected.

Nonlinear acoustics experimental characterization of microstructure evolution in Inconel 617

NASA Astrophysics Data System (ADS)

Yao, Xiaochu; Liu, Yang; Lissenden, Cliff J.

2014-02-01

Inconel 617 is a candidate material for the intermediate heat exchanger in a very high temperature reactor for the next generation nuclear power plant. This application will require the material to withstand fatigue-ratcheting interaction at temperatures up to 950°C. Therefore nondestructive evaluation and structural health monitoring are important capabilities. Acoustic nonlinearity (which is quantified in terms of a material parameter, the acoustic nonlinearity parameter, β) has been proven to be sensitive to microstructural changes in material. This research develops a robust experimental procedure to track the evolution of damage precursors in laboratory tested Inconel 617 specimens using ultrasonic bulk waves. The results from the acoustic non-linear tests are compared with stereoscope surface damage results. Therefore, the relationship between acoustic nonlinearity and microstructural evaluation can be clearly demonstrated for the specimens tested.

Striking differences in properties of geometric isomers of [Ir(tpy)(ppy)H](+): Experimental and computational studies on their hydricities, interaction with CO 2, and photochemistry

DOE PAGES

Garg, Komal; Fujita, Etsuko; Matsubara, Yasuo; ...

2015-11-16

Here, we prepared two geometric isomers of [Ir(tpy)(ppy)H] +, previously proposed as a key intermediate in the photochemical reduction of CO 2 to CO, and characterized their notably different ground- and excited-state interactions with CO 2 and their hydricities using experimental and computational methods. Only one isomer, C-trans-[Ir(tpy)(ppy)H] +, reacts with CO 2 to generate the formato complex in the ground state, consistent with its calculated hydricity. Under photocatalytic conditions in CH 3CN/TEOA, a common reactive C-trans-[Ir(tpy)(ppy)] 0 species, irrespective of the starting isomer or monodentate ligand (such as hydride or Cl), reacts with CO 2 and produces CO withmore » the same catalytic efficiency.« less

Rodent models of insomnia: a review of experimental procedures that induce sleep disturbances.

PubMed

Revel, Florent G; Gottowik, Juergen; Gatti, Sylvia; Wettstein, Joseph G; Moreau, Jean-Luc

2009-06-01

Insomnia, the most common sleep disorder, is characterized by persistent difficulty in falling or staying asleep despite adequate opportunity to sleep, leading to daytime fatigue and mental dysfunction. As sleep is a sophisticated physiological process generated by a network of neuronal systems that cannot be reproduced in-vitro, pre-clinical development of hypnotic drugs requires in-vivo investigations. Accordingly, this review critically evaluates current and putative rodent models of insomnia which could be used to screen novel hypnotics. Only few valid insomnia models are currently available, although many experimental conditions lead to disturbance of physiological sleep. We categorized these conditions as a function of the procedure used to induce perturbation of sleep, and we discuss their respective advantages and pitfalls with respect to validity, feasibility and translational value to human research.

Hydrogen fluoride overtone laser: experimental methods of characterization

NASA Astrophysics Data System (ADS)

Wisniewski, Charles F.; Hewett, Kevin B.; Manke, Gerald C., II; Truman, C. Randall; Hager, Gordon D.

2004-09-01

The uncertainty in both the fluorine atom concentration and the gain length has inhibited the development of accurate and device independent models of HF overtone lasers. Furthermore, previous methods of measuring the small signal gain were cumbersome and could not easily generate spatial maps of the gain in the cavity. Experimental techniques have been developed to directly measure the concentration of fluorine atoms, the gain length and the small signal gain in a hydrogen fluoride 5 cm slit nozzle laser. A gas phase titration technique was utilized to measure the fluorine atom concentration using HCl as the titrant. The gain length was measured using a pitot probe to locate the interface of the primary flow with the high Mach number shroud flows. A tunable diode laser was utilized to perform small signal gain measurements on HF overtone (ν=2-->0) transitions.

Magnetic Field Generation by a Laser-Driven Capacitor-Coil Target

NASA Astrophysics Data System (ADS)

Cheng, Jessica; Gao, Lan

2016-10-01

Magnetic fields generated by currents flowing through a capacitor-coil target were characterized using ultrafast proton radiography at the OMEGA EP Laser System. Two 1.25 kJ, 1-ns laser pulses propagated through the laser entrance holes in one foil of the capacitor, and were focused to the other with an intensity of 3 ×1016 W/cm2. The intense laser-solid interaction induced a high voltage between the foils and generated a large current in the connecting coil. The proton data show tens of kA current producing tens of Tesla magnetic fields at the center of the coil. Theoretical lumped circuit models based on the experimental parameters were developed to simulate the target behavior and calculate the time evolution of the current in the coil. The models take into account important elements such as plasmas conditions for building up the voltage, the capacitance between the gap, the resistive heating and skin effect to gain insights on the field generation mechanism. Applications to other coil geometries and magnetic field configurations will also be described.

Cortical pyramidal cells as non-linear oscillators: experiment and spike-generation theory.

PubMed

Brumberg, Joshua C; Gutkin, Boris S

2007-09-26

Cortical neurons are capable of generating trains of action potentials in response to current injections. These discharges can take different forms, e.g., repetitive firing that adapts during the period of current injection or bursting behaviors. We have used a combined experimental and computational approach to characterize the dynamics leading to action potential responses in single neurons. Specifically we investigated the origin of complex firing patterns in response to sinusoidal current injections. Using a reduced model, the theta-neuron, alongside recordings from cortical pyramidal cells we show that both real and simulated neurons show phase-locking to sine wave stimuli up to a critical frequency, above which period skipping and 1-to-x phase-locking occurs. The locking behavior follows a complex "devil's staircase" phenomena, where locked modes are interleaved with irregular firing. We further show that the critical frequency depends on the time scale of spike generation and on the level of spike frequency adaptation. These results suggest that phase-locking of neuronal responses to complex input patterns can be explained by basic properties of the spike-generating machinery.

Study of Transition Mechanism in a Wake Behind an Airfoil with a Small Angle of Attack by Using a Towing Wind Tunnel

NASA Astrophysics Data System (ADS)

Morita, Toshiyuki; Maekawa, Hiroshi

This paper describes an experimental investigation of the transitional mechanism of a wake generated behind a thin airfoil with a small angle of attack in a towing wind tunnel. A linear stability analysis shows that the wake is characterized by a region of absolute instability in the near wake (x=30mm) and one of convective instability further downstream. When the airfoil starts to run in the tunnel, boundary layers develop on the upper/lower airfoil surfaces with different thickness. Since the asymmetric wake is generated, starting vortices of a single row are observed first in the wake, which is different from the Karman vortex street. The experimental results show that time-harmonic fluctuations of the starting vortex sustain in the natural transition process due to a self sustained resonance in the absolutely unstable region behind the trailing edge. The wake profile in the saturation steady state yields the vortex street structure, where the fluctuation frequency defined as the fundamental unstable mode is found in the final saturation steady state. The growth of the fundamental unstable mode in the convectively unstable region suppresses the high frequency fluctuations associated with the starting vortex generation. On the other hand, low-frequency fluctuations in the quasi-steady state sustaining in the saturation state grow gradually during the vortex street formation, which lead to the vortex deformation downstream.

[The new face of Portuguese medicine: the generation of 1911 and the research school of Marck Athias].

PubMed

Amaral, Isabel Maria

2011-01-01

This paper aims to demonstrate that with Marck Athias, the Portuguese medicine inaugurated a new chapter in its history, in the Republic period, characterized by the experimental training at the laboratory. Thus, book-based knowledge gave way to a more clinically based approach favouring laboratory practice and basic research within several scientific domains. This new perspective operated important changes in the Portuguese medical community in the first half of century XX. Marck Athias (1857-1946), a Portuguese, was a physician trained at the University of Paris under Mathias Duval (a former student of Santiago Rámon y Cajal). It was in his laboratory that Athias began his career as researcher. Returning to Portugal, Athias founded a research school in physiology and histology which stressed a new approach in medicine based on experimental research. At the beginning of the twentieth century, scientific research in Portugal was virtually devoid of any of the practical clinic aspects. It is in fact Athias who introduced a new scientific perspective in Portuguese scientific community as well as influenced generations of graduate students in several national higher education and scientific research centres associated with Medicine. His influence and impact was due in great part to the underlying ideology of a positivist nature which succeeded in attracting several generations of followers, promoting a new step for the modernization of Portuguese medicine.

Random field assessment of nanoscopic inhomogeneity of bone.

PubMed

Dong, X Neil; Luo, Qing; Sparkman, Daniel M; Millwater, Harry R; Wang, Xiaodu

2010-12-01

Bone quality is significantly correlated with the inhomogeneous distribution of material and ultrastructural properties (e.g., modulus and mineralization) of the tissue. Current techniques for quantifying inhomogeneity consist of descriptive statistics such as mean, standard deviation and coefficient of variation. However, these parameters do not describe the spatial variations of bone properties. The objective of this study was to develop a novel statistical method to characterize and quantitatively describe the spatial variation of bone properties at ultrastructural levels. To do so, a random field defined by an exponential covariance function was used to represent the spatial uncertainty of elastic modulus by delineating the correlation of the modulus at different locations in bone lamellae. The correlation length, a characteristic parameter of the covariance function, was employed to estimate the fluctuation of the elastic modulus in the random field. Using this approach, two distribution maps of the elastic modulus within bone lamellae were generated using simulation and compared with those obtained experimentally by a combination of atomic force microscopy and nanoindentation techniques. The simulation-generated maps of elastic modulus were in close agreement with the experimental ones, thus validating the random field approach in defining the inhomogeneity of elastic modulus in lamellae of bone. Indeed, generation of such random fields will facilitate multi-scale modeling of bone in more pragmatic details. Copyright © 2010 Elsevier Inc. All rights reserved.

Influence of beta-cyclodextrin complexation on glipizide release from hydroxypropyl methylcellulose matrix tablets.

PubMed

Shivakumar, H N; Desai, B G; Pandya, Saumyak; Karki, S S

2007-01-01

Glipizide was complexed with beta-cyclodextrin in an attempt to enhance the drug solubility. The phase solubility diagram was classified as A(L) type, which was characterized by an apparent 1:1 stability constant that had a value of 413.82 M(-1). Fourier transform infrared spectrophotometry, differential scanning calorimetry, powder x-ray diffractometry and proton nuclear magnetic resonance spectral analysis indicated considerable interaction between the drug and beta-cyclodextrin. A 2(3) factorial design was employed to prepare hydroxypropyl methylcellulose (HPMC) matrix tablets containing the drug or its complex. The effect of the total polymer loads (X1), levels of HPMC K100LV (X9), and complexation (X3) on release at first hour (Y1), 24 h (Y2), time taken for 50% release (Y3), and diffusion exponent (Y4) was systematically analyzed using the F test. Mathematical models containing only the significant terms (P < 0.05) were generated for each parameter by multiple linear regression analysis and analysis of variance. Complexation was found to exert a significant effect on Y1, Y2, and Y3, whereas total polymer loads significantly influenced all the responses. The models generated were validated by developing two new formulations with a combination of factors within the experimental domain. The experimental values of the response parameters were in close agreement with the predicted values, thereby proving-the validity of the generated mathematical models.

Guided Wave Sensing In a Carbon Steel Pipe Using a Laser Vibrometer System

NASA Astrophysics Data System (ADS)

Ruíz Toledo, Abelardo; Salazar Soler, Jordi; Chávez Domínguez, Juan Antonio; García Hernández, Miguel Jesús; Turó Peroy, Antoni

2010-05-01

Non-Destructive Evaluation (NDE) techniques have achieved a great development during the last decades as a valuable tool for material characterization, manufacturing control and structural integrity tests. Among these tools, the guided wave technology has been rapidly extended because it reduces inspection time and costs compared to the ordinary point by point testing in large structures, as well as because of the possibility of inspecting under insulation and coating conditions. This fast development has motivated the creation of several inspection and material characterization systems including different technologies which can be combined with this technique. Different measurements systems based on laser techniques have been presented in order to inspect pipes, plates and diverse structures. Many of them are experimental systems of high cost and complexity which combine the employment of a laser for generation of waves in the structure and an interferometer for detection. Some of them employ air-coupled ultrasound generation transducers, with high losses in air and which demand high energy for exciting waves in materials of high stiffness. The combined employment of a commercial vibrometer system for Lamb wave sensing in plates has been successfully shown in the literature. In this paper we present a measurement system based on the combined employment of a piezoelectric wedge transducer and a laser vibrometer to sense guided acoustic waves in carbon steel pipes. The measurement system here presented is mainly compounded of an angular wedge transducer, employed to generate the guided wave and a commercial laser vibrometer used in the detection process. The wedge transducer is excited by means of a signal function generator whose output signal has been amplified with a power signal amplifier. A high precision positioning system is employed to place the laser beam at different points through the pipe surface. The signal detected by the laser vibrometer system is amplified with a signal amplifier and then it is displayed in a digital storage oscilloscope. This set-up offers the possibility of analyzing in a simpler way the wave propagation and the material evaluation in pipes of certain wall thickness. The material characterization considering distinct wave propagation modes can be easily achieved, changing the different incident angles of the wedge piezoelectric probe and their combined employment with several driving signals. Moreover, this experimental sensing system offers other possibilities of inspecting and analyzing the wave propagation in some features (bends, flange joints, welds,…) of the pipe surface which cause very large reflections and mode conversions and which in practice limits the inspection range when are inspected with conventional receiving transducer arrangements.

The use of one- and two- photon induced fluorescence spectroscopy for the optical characterization of carcinogenic aflatoxins

NASA Astrophysics Data System (ADS)

Smeesters, L.; Meulebroeck, W.; Raeymaekers, S.; Thienpont, H.

2014-09-01

Carcinogenic and toxic contaminants in food and feed products are nowadays mostly detected by destructive, time-consuming chemical analyses, like HPLC and LC-MS/MS methods. However, as a consequence of the severe and growing regulations on food products by the European Union, there arose an increased demand for the ultra-fast, high-sensitive and non-destructive detection of contaminants in food and feed products. Therefore, we have investigated fluorescence spectroscopy for the characterization of carcinogenic aflatoxins. With the use of a tunable titanium-sapphire laser in combination with second and third harmonic wavelength generation, both one- and two-photon induced fluorescence excitation wavelengths could be generated using the same setup. We characterized and compared the one- and two-photon induced fluorescence spectra of pure aflatoxin powder, after excitation with 365nm and 730nm respectively. Moreover, we investigated the absolute fluorescence intensity as function of the excitation power density. Afterwards, we applied our characterization setup to the detection of aflatoxins in maize grains. The fluorescence spectra of both healthy and contaminated maize samples were experimentally characterized. In addition to the fluorescence spectrum of the pure aflatoxin, we observed an unwanted influence of the intrinsic fluorescence of the maize. Depending on the excitation wavelength, a varying contrast between the fluorescence spectra of the healthy and contaminated samples was obtained. After a comparison of the measured fluorescence signals, a detection criterion for the optical identification of the contaminated maize samples could be defined. As a result, this illustrates the use of fluorescence spectroscopy as a valuable tool for the non-destructive, real-time and high-sensitive detection of aflatoxins in maize.

Modeling the influence of nozzle-generated turbulence on diesel sprays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magnotti, G M; Matusik, K E; Duke, D J

The physical mechanisms governing spray breakup in direct injection engines, such as aerodynamic induced instabilities and nozzle-generated cavitation and turbulence, are not well understood due to the experimental and computational limitations in resolving these processes. Recent x-ray and visible extinction measurements have been con-ducted with a targeted interest in the spray formation region in order to characterize the distribution of droplet sizes throughout the spray. Detailed analysis of these measurements shows promise of yielding insight into likely mechanisms governing atomization, which can inform the improvement of spray models for engine computational fluid dynamic (CFD) codes. In order to investigate potentialmore » atomization mechanisms, we employ a joint experimental and computational approach to characterize the structure of the spray formation region using the Engine Combustion Network Spray D injector. X-ray tomography, radiography and ultra-small angle x-ray scattering measurements conducted at the Advanced Photon Source at Argonne National Laboratory quantify the injector geometry, liquid fuel mass and Sauter mean diameter (SMD) distributions under non-vaporizing conditions. Diffused back-illumination imaging measurements, conducted at the Georgia Institute of Technology, characterize the asymmetry of the spray structure. The selected range of injection pressures (50 – 150 MPa) and ambient densities (1.2 – 22.8 kg/m3) allow for the influence of aerodynamic forces on the spray to be studied in a controlled and systematic manner, while isolating the atomization process from the effects of vaporization. In comparison to high ambient density conditions, the spray is observed to be more asymmetric at low ambient density conditions. Although several mechanisms may cause asymmetries in the nozzle exit flow conditions and ultimately the spray distribution, irregularities in the internal nozzle geometry were identified, suggesting an increased sensitivity of the spray structure to internal nozzle surface finish imperfections at such conditions. The presence of these asymmetries may influence the ability to interpret line-of-sight measurements and their derived SMD values and trends from a single viewing angle of the spray. With this consideration in mind, the measured local sensitivities to ambient density suggest that for ambient densities less than 2.4 kg/m3, aerodynamic effects are likely suppressed, allowing the influence of turbulent-induced breakup to be isolated. In concert with the experimental measurements, we utilize three-dimensional, CFD Lagrangian-Eulerian spray simulations in CONVERGE to evaluate the details of the predicted spray structure. In particular, we compare measured and predicted sensitivities of the SMD distribution to changes in injection and ambient conditions from three different atomization models, namely Kelvin Helmholtz (KH), KH Aerodynamics Cavitation Turbulence (KH-ACT), and the newly developed KH-Faeth hybrid model. While none of the existing hybrid spray models were able to replicate the experimentally observed sensitivities, it was found that the scales characterizing the KH-Faeth model show promise of capturing the experimentally observed trends if the effects of secondary droplet breakup are neglected. These results inform recommendations for future experiments and computational studies that can guide the development of an improved spray breakup model.« less

Scale-dependent cyclone-anticyclone asymmetry in a forced rotating turbulence experiment

NASA Astrophysics Data System (ADS)

Gallet, B.; Campagne, A.; Cortet, P.-P.; Moisy, F.

2014-03-01

We characterize the statistical and geometrical properties of the cyclone-anticyclone asymmetry in a statistically steady forced rotating turbulence experiment. Turbulence is generated by a set of vertical flaps which continuously inject velocity fluctuations towards the center of a tank mounted on a rotating platform. We first characterize the cyclone-anticyclone asymmetry from conventional single-point vorticity statistics. We propose a phenomenological model to explain the emergence of the asymmetry in the experiment, from which we predict scaling laws for the root-mean-square velocity in good agreement with the experimental data. We further quantify the cyclone-anticyclone asymmetry using a set of third-order two-point velocity correlations. We focus on the correlations which are nonzero only if the cyclone-anticyclone symmetry is broken. They offer two advantages over single-point vorticity statistics: first, they are defined from velocity measurements only, so an accurate resolution of the Kolmogorov scale is not required; second, they provide information on the scale-dependence of the cyclone-anticyclone asymmetry. We compute these correlation functions analytically for a random distribution of independent identical vortices. These model correlations describe well the experimental ones, indicating that the cyclone-anticyclone asymmetry is dominated by the large-scale long-lived cyclones.

Multi-camera volumetric PIV for the study of jumping fish

NASA Astrophysics Data System (ADS)

Mendelson, Leah; Techet, Alexandra H.

2018-01-01

Archer fish accurately jump multiple body lengths for aerial prey from directly below the free surface. Multiple fins provide combinations of propulsion and stabilization, enabling prey capture success. Volumetric flow field measurements are crucial to characterizing multi-propulsor interactions during this highly three-dimensional maneuver; however, the fish's behavior also drives unique experimental constraints. Measurements must be obtained in close proximity to the water's surface and in regions of the flow field which are partially-occluded by the fish body. Aerial jump trajectories must also be known to assess performance. This article describes experiment setup and processing modifications to the three-dimensional synthetic aperture particle image velocimetry (SAPIV) technique to address these challenges and facilitate experimental measurements on live jumping fish. The performance of traditional SAPIV algorithms in partially-occluded regions is characterized, and an improved non-iterative reconstruction routine for SAPIV around bodies is introduced. This reconstruction procedure is combined with three-dimensional imaging on both sides of the free surface to reveal the fish's three-dimensional wake, including a series of propulsive vortex rings generated by the tail. In addition, wake measurements from the anal and dorsal fins indicate their stabilizing and thrust-producing contributions as the archer fish jumps.

Effect of phytoplackton-derived organic matter on the behavior of marine aerosols

NASA Astrophysics Data System (ADS)

Fuentes, E.; Coe, H.; McFiggans, G.; Green, D.

2009-04-01

The presence of significant concentrations of organic material in marine aerosols has been appreciated for several decades; however, only recently has significant progress been made towards demonstrating that this organic content is biogenically formed. Biogenic organics of placktonic life origin are incorporated in marine aerosol composition as a result of bubble bursting/breaking waves mechanisms that occur at the ocean surface. The presence of organic surfactants in the marine aerosol composition might have a significant impact on the properties of the generated aerosols by affecting the particles surface tension and solution balance properties. Nevertheless, it remains uncertain the role of such organics on the physical-chemical behavior of marine aerosols. In this work an experimental study was performed in order to determine the influence of biogenic marine organic compounds on the size distribution, hygroscopicity and cloud-nucleating properties of marine aerosols. For the experimental study a laboratory water recirculation system (bubble tank), designed for the simulation of bubble-burst aerosol formation, was used as marine aerosol generator. The bubble spectra produced by such system was characterized by means of an optical bubble measuring device (BMS) and it was found to be consistent with oceanic bubble spectra properties. Seawater proxy solutions were prepared from laboratory biologically-synthesized exudates produced by oceanic representative algal species and introduced in the tank for the generation of marine aerosol by bubble bursting. Two experimental methods were employed for seawater proxies preparation: the formation of surface monolayers from the biogenic surfactants extracted by a solid phase extraction technique (monolayer method) and the mixing of the exudates in the sea salt water bulk (bulk mixing method). Particle size distribution, hygroscopicity and cloud condensation nuclei experiments for different monolayers, and exudate mixtures were performed. This contribution provides an overview of the experimental study conducted and the most relevant results found in this research work.

Lysozyme oxidation by singlet molecular oxygen: Peptide characterization using [18 O]-labeling oxygen and nLC-MS/MS.

PubMed

Marques, Emerson Finco; Medeiros, Marisa H G; Di Mascio, Paolo

2017-11-01

Singlet molecular oxygen ( 1 O 2 ) is generated in biological systems and reacts with different biomolecules. Proteins are a major target for 1 O 2 , and His, Tyr, Met, Cys, and Trp are oxidized at physiological pH. In the present study, the modification of lysozyme protein by 1 O 2 was investigated using mass spectrometry approaches. The experimental findings showed methionine, histidine, and tryptophan oxidation. The experiments were achieved using [ 18 O]-labeled 1 O 2 released from thermolabile endoperoxides in association with nano-scale liquid chromatography coupled to electrospray ionization mass spectrometry. The structural characterization by nLC-MS/MS of the amino acids in the tryptic peptides of the proteins showed addition of [ 18 O]-labeling atoms in different amino acids. Copyright © 2017 John Wiley & Sons, Ltd.

Two-step phase-shifting SPIDER

NASA Astrophysics Data System (ADS)

Zheng, Shuiqin; Cai, Yi; Pan, Xinjian; Zeng, Xuanke; Li, Jingzhen; Li, Ying; Zhu, Tianlong; Lin, Qinggang; Xu, Shixiang

2016-09-01

Comprehensive characterization of ultrafast optical field is critical for ultrashort pulse generation and its application. This paper combines two-step phase-shifting (TSPS) into the spectral phase interferometry for direct electric-field reconstruction (SPIDER) to improve the reconstruction of ultrafast optical-fields. This novel SPIDER can remove experimentally the dc portion occurring in traditional SPIDER method by recording two spectral interferograms with π phase-shifting. As a result, the reconstructed results are much less disturbed by the time delay between the test pulse replicas and the temporal widths of the filter window, thus more reliable. What is more, this SPIDER can work efficiently even the time delay is so small or the measured bandwidth is so narrow that strong overlap happens between the dc and ac portions, which allows it to be able to characterize the test pulses with complicated temporal/spectral structures or narrow bandwidths.

Subvisible (2-100 μm) Particle Analysis During Biotherapeutic Drug Product Development: Part 1, Considerations and Strategy.

PubMed

Narhi, Linda O; Corvari, Vincent; Ripple, Dean C; Afonina, Nataliya; Cecchini, Irene; Defelippis, Michael R; Garidel, Patrick; Herre, Andrea; Koulov, Atanas V; Lubiniecki, Tony; Mahler, Hanns-Christian; Mangiagalli, Paolo; Nesta, Douglas; Perez-Ramirez, Bernardo; Polozova, Alla; Rossi, Mara; Schmidt, Roland; Simler, Robert; Singh, Satish; Spitznagel, Thomas M; Weiskopf, Andrew; Wuchner, Klaus

2015-06-01

Measurement and characterization of subvisible particles (defined here as those ranging in size from 2 to 100 μm), including proteinaceous and nonproteinaceous particles, is an important part of every stage of protein therapeutic development. The tools used and the ways in which the information generated is applied depends on the particular product development stage, the amount of material, and the time available for the analysis. In order to compare results across laboratories and products, it is important to harmonize nomenclature, experimental protocols, data analysis, and interpretation. In this manuscript on perspectives on subvisible particles in protein therapeutic drug products, we focus on the tools available for detection, characterization, and quantification of these species and the strategy around their application. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Probabilistic Reasoning Over Seismic Time Series: Volcano Monitoring by Hidden Markov Models at Mt. Etna

NASA Astrophysics Data System (ADS)

Cassisi, Carmelo; Prestifilippo, Michele; Cannata, Andrea; Montalto, Placido; Patanè, Domenico; Privitera, Eugenio

2016-07-01

From January 2011 to December 2015, Mt. Etna was mainly characterized by a cyclic eruptive behavior with more than 40 lava fountains from New South-East Crater. Using the RMS (Root Mean Square) of the seismic signal recorded by stations close to the summit area, an automatic recognition of the different states of volcanic activity (QUIET, PRE-FOUNTAIN, FOUNTAIN, POST-FOUNTAIN) has been applied for monitoring purposes. Since values of the RMS time series calculated on the seismic signal are generated from a stochastic process, we can try to model the system generating its sampled values, assumed to be a Markov process, using Hidden Markov Models (HMMs). HMMs analysis seeks to recover the sequence of hidden states from the observations. In our framework, observations are characters generated by the Symbolic Aggregate approXimation (SAX) technique, which maps RMS time series values with symbols of a pre-defined alphabet. The main advantages of the proposed framework, based on HMMs and SAX, with respect to other automatic systems applied on seismic signals at Mt. Etna, are the use of multiple stations and static thresholds to well characterize the volcano states. Its application on a wide seismic dataset of Etna volcano shows the possibility to guess the volcano states. The experimental results show that, in most of the cases, we detected lava fountains in advance.

Linear Transformer Drivers for Z-pinch Based Propulsion

NASA Technical Reports Server (NTRS)

Adams, Robert; Seidler, William; Giddens, Patrick; Fabisinski, Leo; Cassibry, Jason

2017-01-01

The MSFC/UAH team has been developing of a novel power management and distribution system called a Linear Transformer Driver (LTD). LTD's hold the promise of dramatically reducing the required mass to drive a z-pinch by replacing the capacitor banks which constitute half the mass of the entire system. The MSFC?UAH tea, is developing this technology in hope of integrating it with the Pulsed Fission Fusion (PuFF) propulsion concept. High-Voltage pulsed power systems used for Z-Pinch experimentation have in the past largely been based on Marx Generators. Marx generators deliver the voltage and current required for the Z-Pinch, but suffer from two significant drawbacks when applied to a flight system: they are very massive, consisting of high-voltage capacitor banks insulated in oil-filled tanks and they do not lend themselves to rapid pulsing. The overall goal of Phase 2 is to demonstrate the construction of a higher voltage stack from a number of cavities each of the design proven in Phase 1 and to characterize and understand the techniques for designing the stack. The overall goal of Phase 3 is to demonstrate the feasibility of constructing a higher energy cavity from a number of smaller LTD stacks, to characterize and understand the way in which the constituent stacks combine, and to extend this demonstration LTD to serve as the basis for a 64 kJ pulse generator for Z-Pinch experiments.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano

Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has mademore » piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing requirements by increasing harvested power, shifting optimal conditioning impedance, inducing significant voltage supply fluctuations and ultimately rendering idealized sinusoidal and random analyses insufficient.« less

The pumping lid: investigating multi-material 3D printing for equipment-free, programmable generation of positive and negative pressures for microfluidic applications.

PubMed

Begolo, Stefano; Zhukov, Dmitriy V; Selck, David A; Li, Liang; Ismagilov, Rustem F

2014-12-21

Equipment-free pumping is a challenging problem and an active area of research in microfluidics, with applications for both laboratory and limited-resource settings. This paper describes the pumping lid method, a strategy to achieve equipment-free pumping by controlled generation of pressure. Pressure was generated using portable, lightweight, and disposable parts that can be integrated with existing microfluidic devices to simplify workflow and eliminate the need for pumping equipment. The development of this method was enabled by multi-material 3D printing, which allows fast prototyping, including composite parts that combine materials with different mechanical properties (e.g. both rigid and elastic materials in the same part). The first type of pumping lid we describe was used to produce predictable positive or negative pressures via controlled compression or expansion of gases. A model was developed to describe the pressures and flow rates generated with this approach and it was validated experimentally. Pressures were pre-programmed by the geometry of the parts and could be tuned further even while the experiment was in progress. Using multiple lids or a composite lid with different inlets enabled several solutions to be pumped independently in a single device. The second type of pumping lid, which relied on vapor-liquid equilibrium to generate pressure, was designed, modeled, and experimentally characterized. The pumping lid method was validated by controlling flow in different types of microfluidic applications, including the production of droplets, control of laminar flow profiles, and loading of SlipChip devices. We believe that applying the pumping lid methodology to existing microfluidic devices will enhance their use as portable diagnostic tools in limited resource settings as well as accelerate adoption of microfluidics in laboratories.

Flexible Material Systems Testing

NASA Technical Reports Server (NTRS)

Lin, John K.; Shook, Lauren S.; Ware, Joanne S.; Welch, Joseph V.

2010-01-01

An experimental program has been undertaken to better characterize the stress-strain characteristics of flexible material systems to support a NASA ground test program for inflatable decelerator material technology. A goal of the current study is to investigate experimental methods for the characterization of coated woven material stiffness. This type of experimental mechanics data would eventually be used to define the material inputs of fluid-structure interaction simulation models. The test methodologies chosen for this stress-strain characterization are presented along with the experimental results.

The era of the wandering mind? Twenty-first century research on self-generated mental activity.

PubMed

Callard, Felicity; Smallwood, Jonathan; Golchert, Johannes; Margulies, Daniel S

2013-01-01

The first decade of the twenty-first century was characterized by renewed scientific interest in self-generated mental activity (activity largely generated by the individual, rather than in direct response to experimenters' instructions or specific external sensory inputs). To understand this renewal of interest, we interrogated the peer-reviewed literature from 2003 to 2012 (i) to explore recent changes in use of terms for self-generated mental activity; (ii) to investigate changes in the topics on which mind wandering research, specifically, focuses; and (iii) to visualize co-citation communities amongst researchers working on self-generated mental activity. Our analyses demonstrated that there has been a dramatic increase in the term "mind wandering" from 2006, and a significant crossing-over of psychological investigations of mind wandering into cognitive neuroscience (particularly in relation to research on the default mode and default mode network). If our article concludes that this might, indeed, be the "era of the wandering mind," it also calls for more explicit reflection to be given by researchers in this field to the terms they use, the topics and brain regions they focus on, and the research literatures that they implicitly foreground or ignore.

Resonant-frequency discharge in a multi-cell radio frequency cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Popovic, S; Upadhyay, J; Mammosser, J

2014-11-07

We are reporting experimental results on microwave discharge operating at resonant frequency in a multi-cell radio frequency (RF) accelerator cavity. Although the discharge operated at room temperature, the setup was constructed so that it could be used for plasma generation and processing in fully assembled active superconducting radio-frequency (SRF) cryomodule (in situ operation). This discharge offers an efficient mechanism for removal of a variety of contaminants, organic or oxide layers, and residual particulates from the interior surface of RF cavities through the interaction of plasma-generated radicals with the cavity walls. We describe resonant RF breakdown conditions and address the problemsmore » related to generation and sustaining the multi-cell cavity plasma, which are breakdown and resonant detuning. We have determined breakdown conditions in the cavity, which was acting as a plasma vessel with distorted cylindrical geometry. We discuss the spectroscopic data taken during plasma removal of contaminants and use them to evaluate plasma parameters, characterize the process, and estimate the volatile contaminant product removal.« less

Chromatic effect in a novel THz generation scheme

NASA Astrophysics Data System (ADS)

Li, Bin; Zhang, Wenyan; Liu, Xiaoqing; Deng, Haixiao; Lan, Taihe; Liu, Bo; Liu, Jia; Wang, Xingtao; Zeng, Zhinan; Zhang, Lijian

2017-11-01

Deriving single or few cycle terahertz (THz) pulse by an intense femtosecond laser through cascaded optical rectification is a crucial technique in cutting-edge time-resolved spectroscopy to characterize micro-scale structures and ultrafast dynamics. Due to the broadband nature of the ultrafast driving laser, the chromatic effect limits the THz conversion efficiency in optical rectification crystals, especially for those implementing the pulse-front tilt scheme, e.g. lithium niobate (LN) crystal, has been prevalently used in the past decade. In this research we developed a brand new type of LN crystal utilizing Brewster coupling, and conducted systematically experimental and simulative investigation for the chromatic effect and multi-dimensionally entangled parameters in THz generation, predicting that an extreme conversion efficiency of ˜10% would be potentially achievable at the THz absorption coefficient of ˜0.5 cm-1. Moreover, we first discovered that the chirp of the driving laser plays a decisive role in the pulse-front tilt scheme, and the THz generation efficiency could be enhanced tremendously by applying an appropriate chirp.

Spatial measurement in rotating magnetic field plasma acceleration method by using two-dimensional scanning instrument and thrust stand

NASA Astrophysics Data System (ADS)

Furukawa, T.; Takizawa, K.; Yano, K.; Kuwahara, D.; Shinohara, S.

2018-04-01

A two-dimensional scanning probe instrument has been developed to survey spatial plasma characteristics in our electrodeless plasma acceleration schemes. In particular, diagnostics of plasma parameters, e.g., plasma density, temperature, velocity, and excited magnetic field, are essential for elucidating physical phenomena since we have been concentrating on next generation plasma propulsion methods, e.g., Rotating Magnetic Field plasma acceleration method, by characterizing the plasma performance. Moreover, in order to estimate the thrust performance in our experimental scheme, we have also mounted a thrust stand, which has a target type, on this movable instrument, and scanned the axial profile of the thrust performance in the presence of the external magnetic field generated by using permanent magnets, so as to investigate the plasma captured in a stand area, considering the divergent field lines in the downstream region of a generation antenna. In this paper, we will introduce the novel measurement instrument and describe how to measure these parameters.

Anechoic wind tunnel study of turbulence effects on wind turbine broadband noise

NASA Technical Reports Server (NTRS)

Loyd, B.; Harris, W. L.

1995-01-01

This paper describes recent results obtained at MIT on the experimental and theoretical modelling of aerodynamic broadband noise generated by a downwind rotor horizontal axis wind turbine. The aerodynamic broadband noise generated by the wind turbine rotor is attributed to the interaction of ingested turbulence with the rotor blades. The turbulence was generated in the MIT anechoic wind tunnel facility with the aid of biplanar grids of various sizes. The spectra and the intensity of the aerodynamic broadband noise have been studied as a function of parameters which characterize the turbulence and of wind turbine performance parameters. Specifically, the longitudinal integral scale of turbulence, the size scale of turbulence, the number of turbine blades, and free stream velocity were varied. Simultaneous measurements of acoustic and turbulence signals were made. The sound pressure level was found to vary directly with the integral scale of the ingested turbulence but not with its intensity level. A theoretical model based on unsteady aerodynamics is proposed.

An Intelligent Automation Platform for Rapid Bioprocess Design.

PubMed

Wu, Tianyi; Zhou, Yuhong

2014-08-01

Bioprocess development is very labor intensive, requiring many experiments to characterize each unit operation in the process sequence to achieve product safety and process efficiency. Recent advances in microscale biochemical engineering have led to automated experimentation. A process design workflow is implemented sequentially in which (1) a liquid-handling system performs high-throughput wet lab experiments, (2) standalone analysis devices detect the data, and (3) specific software is used for data analysis and experiment design given the user's inputs. We report an intelligent automation platform that integrates these three activities to enhance the efficiency of such a workflow. A multiagent intelligent architecture has been developed incorporating agent communication to perform the tasks automatically. The key contribution of this work is the automation of data analysis and experiment design and also the ability to generate scripts to run the experiments automatically, allowing the elimination of human involvement. A first-generation prototype has been established and demonstrated through lysozyme precipitation process design. All procedures in the case study have been fully automated through an intelligent automation platform. The realization of automated data analysis and experiment design, and automated script programming for experimental procedures has the potential to increase lab productivity. © 2013 Society for Laboratory Automation and Screening.

An Intelligent Automation Platform for Rapid Bioprocess Design

PubMed Central

Wu, Tianyi

2014-01-01

Bioprocess development is very labor intensive, requiring many experiments to characterize each unit operation in the process sequence to achieve product safety and process efficiency. Recent advances in microscale biochemical engineering have led to automated experimentation. A process design workflow is implemented sequentially in which (1) a liquid-handling system performs high-throughput wet lab experiments, (2) standalone analysis devices detect the data, and (3) specific software is used for data analysis and experiment design given the user’s inputs. We report an intelligent automation platform that integrates these three activities to enhance the efficiency of such a workflow. A multiagent intelligent architecture has been developed incorporating agent communication to perform the tasks automatically. The key contribution of this work is the automation of data analysis and experiment design and also the ability to generate scripts to run the experiments automatically, allowing the elimination of human involvement. A first-generation prototype has been established and demonstrated through lysozyme precipitation process design. All procedures in the case study have been fully automated through an intelligent automation platform. The realization of automated data analysis and experiment design, and automated script programming for experimental procedures has the potential to increase lab productivity. PMID:24088579

Characterization of pulsed atmospheric-pressure plasma streams (PAPS) generated by a plasma gun

NASA Astrophysics Data System (ADS)

Robert, E.; Sarron, V.; Riès, D.; Dozias, S.; Vandamme, M.; Pouvesle, J.-M.

2012-06-01

An experimental study of atmospheric-pressure rare gas plasma propagation in a high-aspect-ratio capillary is reported. The plasma is generated with a plasma gun device based on a dielectric barrier discharge (DBD) reactor powered by either nanosecond or microsecond rise-time high-voltage pulses at single-shot to multi-kHz frequencies. The influence of the voltage waveform, pulse polarity, pulse repetition rate and capillary material have been studied using nanosecond intensified charge-coupled device imaging and plasma-front velocity measurements. The evolution of the plasma appearance during its propagation and the study of the role of the different experimental parameters lead us to suggest a new denomination of pulsed atmospheric-pressure plasma streams to describe all the plasma features, including the previously so-called plasma bullet. The unique properties of such non-thermal plasma launching in capillaries, far from the primary DBD plasma, are associated with a fast ionization wave travelling with velocity in the 107-108 cm s-1 range. Voltage pulse tailoring is shown to allow for a significant improvement of such plasma delivery. Thus, the plasma gun device affords unique opportunities in biomedical endoscopic applications.

Experimental Evaluation of the "Polished Panel Optical Receiver" Concept on the Deep Space Network's 34 Meter Antenna

NASA Technical Reports Server (NTRS)

Vilnrotter, Victor A.

2012-01-01

The potential development of large aperture ground-based "photon bucket" optical receivers for deep space communications has received considerable attention recently. One approach currently under investigation proposes to polish the aluminum reflector panels of 34-meter microwave antennas to high reflectance, and accept the relatively large spotsize generated by even state-of-the-art polished aluminum panels. Here we describe the experimental effort currently underway at the Deep Space Network (DSN) Goldstone Communications Complex in California, to test and verify these concepts in a realistic operational environment. A custom designed aluminum panel has been mounted on the 34 meter research antenna at Deep-Space Station 13 (DSS-13), and a remotely controlled CCD camera with a large CCD sensor in a weather-proof container has been installed next to the subreflector, pointed directly at the custom polished panel. Using the planet Jupiter as the optical point-source, the point-spread function (PSF) generated by the polished panel has been characterized, the array data processed to determine the center of the intensity distribution, and expected communications performance of the proposed polished panel optical receiver has been evaluated.

A temporal PIV study of flame/obstacle generated vortex interactions within a semi-confined combustion chamber

NASA Astrophysics Data System (ADS)

Jarvis, S.; Hargrave, G. K.

2006-01-01

Experimental data obtained using a new multiple-camera digital particle image velocimetry (PIV) technique are presented for the interaction between a propagating flame and the turbulent recirculating velocity field generated during flame-solid obstacle interaction. The interaction between the gas movement and the obstacle creates turbulence by vortex shedding and local wake recirculations. The presence of turbulence in a flammable gas mixture can wrinkle a flame front, increasing the flame surface area and enhancing the burning rate. To investigate propagating flame/turbulence interaction, a novel multiple-camera digital PIV technique was used to provide high spatial and temporal characterization of the phenomenon for the turbulent flow field in the wake of three sequential obstacles. The technique allowed the quantification of the local flame speed and local flow velocity. Due to the accelerating nature of the explosion flow field, the wake flows develop 'transient' turbulent fields. Multiple-camera PIV provides data to define the spatial and temporal variation of both the velocity field ahead of the propagating flame and the flame front to aid the understanding of flame-vortex interaction. Experimentally obtained values for flame displacement speed and flame stretch are presented for increasing vortex complexity.

Characterization of an induced pressure pumping force for microfluidics

NASA Astrophysics Data System (ADS)

Jiang, Hai; Fan, Na; Peng, Bei; Weng, Xuan

2017-05-01

The electro-osmotic pumping and pressure-driven manipulation of fluids are considered as the most common strategies in microfluidic devices. However, both of them exhibit major disadvantages such as hard integration and high reagent consumption, and they are destructive methods for detection and photo bleaching. In this paper, an electric field-effect flow control approach, combining the electro-osmotic pumping force and the pressure-driven pumping force, was developed to generate the induced pressure-driven flow in a T-shaped microfluidic chip. Electro-osmotic flow between the T-intersection and two reservoirs was demonstrated, and it provided a stable, continuous, and electric field-free flow in the section of the microchannel without the electrodes. The velocity of the induced pressure-driven flow was linearly proportional to the applied voltages. Both numerical and experimental investigations were conducted to prove the concept, and the experimental results showed good agreement with the numerical simulations. In comparison to other induced pressure pumping methods, this approach can induce a high and controllable pressure drop in the electric field-free segment, subsequently causing an induced pressure-driven flow for transporting particles or biological cells. In addition, the generation of bubbles and the blocking of the microchannel are avoided.

The microbiota revolution: Excitement and caution.

PubMed

Rescigno, Maria

2017-09-01

Scientific progress is characterized by important technological advances. Next-generation DNA sequencing has, in the past few years, led to a major scientific revolution: the microbiome revolution. It has become possible to generate a fingerprint of the whole microbiota of any given environment. As it becomes clear that the microbiota affects several aspects of our lives, each new scientific finding should ideally be analyzed in light of these communities. For instance, animal experimentation should consider animal sources and husbandry; human experimentation should include analysis of microenvironmental cues that might affect the microbiota, including diet, antibiotic, and drug use, genetics. When analyzing the activity of a drug, we should remember that, according to the microbiota of the host, different drug activities might be observed, either due to modification or degradation by the microbiota, or because the microbiota changes the immune system of the host in a way that makes that drug more or less effective. This minireview will not be a comprehensive review on the interaction between the host and microbiota, but it will aim at creating awareness on why we should not forget the contribution of the microbiota in any single aspect of biology. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Second order harmonic guided wave mutual interactions in plate: Vector analysis, numerical simulation, and experimental results

NASA Astrophysics Data System (ADS)

Hasanian, Mostafa; Lissenden, Cliff J.

2017-08-01

The extraordinary sensitivity of nonlinear ultrasonic waves to the early stages of material degradation makes them excellent candidates for nondestructive material characterization. However, distinguishing weak material nonlinearity from instrumentation nonlinearity remains problematic for second harmonic generation approaches. A solution to this problem is to mix waves having different frequencies and to let their mutual interaction generate sum and difference harmonics at frequencies far from those of the instrumentation. Mixing of bulk waves and surface waves has been researched for some time, but mixing of guided waves has not yet been investigated in depth. A unique aspect of guided waves is their dispersive nature, which means we need to assure that a wave can propagate at the sum or difference frequency. A wave vector analysis is conducted that enables selection of primary waves traveling in any direction that generate phase matched secondary waves. We have tabulated many sets of primary waves and phase matched sum and difference harmonics. An example wave mode triplet of two counter-propagating collinear shear horizontal waves that interact to generate a symmetric Lamb wave at the sum frequency is simulated using finite element analysis and then laboratory experiments are conducted. The finite element simulation eliminates issues associated with instrumentation nonlinearities and signal-to-noise ratio. A straightforward subtraction method is used in the experiments to identify the material nonlinearity induced mutual interaction and show that the generated Lamb wave propagates on its own and is large enough to measure. Since the Lamb wave has different polarity than the shear horizontal waves the material nonlinearity is clearly identifiable. Thus, the mutual interactions of shear horizontal waves in plates could enable volumetric characterization of material in remote regions from transducers mounted on just one side of the plate.

An experimental study of the noise generating mechanisms in supersonic jets

NASA Technical Reports Server (NTRS)

Mclaughlin, D. K.

1979-01-01

Flow fluctuation measurements with normal and X-wire hot-wire probes and acoustic measurements with a traversing condenser microphone were carried out in small air jets in the Mach number range from M = 0.9 to 2.5. One of the most successful studies involved a moderate Reynolds number M = 2.1 jet. The large scale turbulence properties in the jet, and the noise radiation were characterized. A parallel study involved similar measurements on a low Reynolds number M = 0.9 jet. These measurements show that there are important differences in the noise generation process of the M = 0.9 jet in comparison with low supersonic Mach number (M = 1.4) jets. Problems encounted while performing X-wire measurements in low Reynolds number jets of M = 2.1 and 2.5, and in installing a vacuum pump are discussed.

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

NASA Astrophysics Data System (ADS)

Manuel, M. J.-E.; Kuranz, C. C.; Rasmus, A. M.; Klein, S. R.; MacDonald, M. J.; Trantham, M. R.; Fein, J. R.; Belancourt, P. X.; Young, R. P.; Keiter, P. A.; Drake, R. P.; Pollock, B. B.; Park, J.; Hazi, A. U.; Williams, G. J.; Chen, H.

2015-12-01

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysical systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. This result is a topic of ongoing investigation.

Nanoplasmon-enabled macroscopic thermal management

PubMed Central

Jonsson, Gustav Edman; Miljkovic, Vladimir; Dmitriev, Alexandre

2014-01-01

In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive nanoplasmonic materials. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. Naturally, approaches to the direct experimental probing of macroscopic temperature increase resulting from these absorbers are welcomed. Here we derive a general quantitative method of characterizing heat-generating properties of optically absorptive layers via macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to a large number of applications where thermal management is crucial. PMID:24870613

Measuring the jitter of ring oscillators by means of information theory quantifiers

NASA Astrophysics Data System (ADS)

Antonelli, M.; De Micco, L.; Larrondo, H. A.

2017-02-01

Ring oscillators (RO's) are elementary blocks widely used in digital design. Jitter is unavoidable in RO's, its presence is an undesired behavior in many applications, as clock generators. On the contrary, jitter may be used as the noise source in RO-based true-random numbers generators (TRNG). Consequently, jitter measure is a relevant issue to characterize a RO, and it is the subject of this paper. The main contribution is the use of Information Theory Quantifiers (ITQ) as measures of RO's jitter. It is shown that among several ITQ evaluated, two of them emerge as good measures because they are independent of parameters used for their statistical determination. They turned out to be robust and may be implemented experimentally. We encountered that a dual entropy plane allows a visual comparison of results.

Investigation of laser pulse length and pre-plasma scale length impact on hot electron generation on OMEGA-EP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peebles, J.; Wei, M. S.; Arefiev, A. V.

A series of experiments studying pre-plasma’s effect on electron generation and transport due to a high intensity laser were conducted on the OMEGA-EP laser facility. A controlled pre-plasma was produced in front of an aluminum foil target prior to the arrival of the high intensity short pulse beam. Energetic electron spectra were characterized with magnetic and bremsstrahlung spectrometers. Preplasma and pulse length were shown to have a large impact on the temperature of lower energy, ponderomotive scaling electrons. Furthermore, super-ponderomotive electrons, seen in prior pre-plasma experiments with shorter pulses, were observed without any initial pre-plasma in our experiment. 2D particle-in-cellmore » and radiation-hydrodynamic simulations shed light on and validate these experimental results.« less

Investigation of laser pulse length and pre-plasma scale length impact on hot electron generation on OMEGA-EP

DOE PAGES

Peebles, J.; Wei, M. S.; Arefiev, A. V.; ...

2017-02-02

A series of experiments studying pre-plasma’s effect on electron generation and transport due to a high intensity laser were conducted on the OMEGA-EP laser facility. A controlled pre-plasma was produced in front of an aluminum foil target prior to the arrival of the high intensity short pulse beam. Energetic electron spectra were characterized with magnetic and bremsstrahlung spectrometers. Preplasma and pulse length were shown to have a large impact on the temperature of lower energy, ponderomotive scaling electrons. Furthermore, super-ponderomotive electrons, seen in prior pre-plasma experiments with shorter pulses, were observed without any initial pre-plasma in our experiment. 2D particle-in-cellmore » and radiation-hydrodynamic simulations shed light on and validate these experimental results.« less

Plastic protein microarray to investigate the molecular pathways of magnetic nanoparticle-induced nanotoxicity

NASA Astrophysics Data System (ADS)

Liu, Yingshuai; Li, Xuelian; Bao, Shujuan; Lu, Zhisong; Li, Qing; Li, Chang Ming

2013-05-01

Superparamagnetic iron oxide nanoparticles (SPIONs) (about 15 nm) were synthesized via a hydrothermal method and characterized by field emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, x-ray diffraction, and vibrating sample magnetometer. The molecular pathways of SPIONs-induced nanotoxicity was further investigated by protein microarrays on a plastic substrate from evaluation of cell viability, reactive oxygen species (ROS) generation and cell apoptosis. The experimental results reveal that 50 μg ml-1 or higher levels of SPIONs cause significant loss of cell viability, considerable generation of ROS and cell apoptosis. It is proposed that high level SPIONs could induce cell apoptosis via a mitochondria-mediated intrinsic pathway by activation of caspase 9 and caspase 3, an increase of the Bax/Bcl-2 ratio, and down-regulation of HSP70 and HSP90 survivor factors.

Considerations on data acquisition in laser ablation-inductively coupled plasma-mass spectrometry with low-dispersion interfaces

NASA Astrophysics Data System (ADS)

Van Malderen, Stijn J. M.; van Elteren, Johannes T.; Šelih, Vid S.; Vanhaecke, Frank

2018-02-01

This work describes the aliasing effects induced by undersampling the high-frequency signal patterns generated by a laser ablation-inductively coupled plasma-mass spectrometer equipped with a low-dispersion ablation cell and sequential mass analyzer. By characterizing the width of the signal peak generated from a single shot on the sample, critical experimental parameters, such as the laser repetition rate and detector cycle timings for the individual nuclides can be matched so as to avoid these imaging artifacts (spectral skew) induced by an insufficient sampling rate. By increasing the laser repetition rate by a factor 2-3, masses at the end of the mass scan can be sampled at higher sensitivity. Furthermore, the dwell times can be redistributed over the nuclides of interest based on the signal-to-noise ratio to increase the image contrast.

Potentials of storing solar energy in the form of hydrogen for Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdel, A.A.L.; Mohamed, M.A.

1989-01-01

A seemingly insatiable demand for energy characterizes Egypt as it approaches the end of the twentieth century. With the limited energy resources in the country, R and D to utilize renewable sources of energy is a must. This paper examines first the energy situation in Egypt and explores the potential of using solar energy in hydrogen production from water. Different schemes of dissociating water are reviewed next. Finally, research findings are reported for some experimental runs carried out for the electrolysis of water by solar energy, utilizing an eight-water photovoltaic cell (Telephonken type) to generate the DC current.

Contact line friction of electrowetting actuated viscous droplets

NASA Astrophysics Data System (ADS)

Vo, Quoc; Tran, Tuan

2018-06-01

We examine the contact line friction coefficient of viscous droplets spreading and retracting on solid surfaces immersed in ambient oil. By using the electrowetting effect, we generate a surface tension imbalance to drive the spreading and the retracting motion of the three-phase contact line (TCL). We show that neither the driving force intensity nor TCL direction significantly influences the friction coefficient. Instead, the friction coefficient depends equivalently on the viscosity of liquid droplets and the surrounding oil. We derive and experimentally verify a transient timescale that can be used to characterize both the spreading and retracting dynamics.

Roughness Perception of Haptically Displayed Fractal Surfaces

NASA Technical Reports Server (NTRS)

Costa, Michael A.; Cutkosky, Mark R.; Lau, Sonie (Technical Monitor)

2000-01-01

Surface profiles were generated by a fractal algorithm and haptically rendered on a force feedback joystick, Subjects were asked to use the joystick to explore pairs of surfaces and report to the experimenter which of the surfaces they felt was rougher. Surfaces were characterized by their root mean square (RMS) amplitude and their fractal dimension. The most important factor affecting the perceived roughness of the fractal surfaces was the RMS amplitude of the surface. When comparing surfaces of fractal dimension 1.2-1.35 it was found that the fractal dimension was negatively correlated with perceived roughness.

Microbubble cloud characterization by nonlinear frequency mixing.

PubMed

Cavaro, M; Payan, C; Moysan, J; Baqué, F

2011-05-01

In the frame of the fourth generation forum, France decided to develop sodium fast nuclear reactors. French Safety Authority requests the associated monitoring of argon gas into sodium. This implies to estimate the void fraction, and a histogram indicating the bubble population. In this context, the present letter studies the possibility of achieving an accurate determination of the histogram with acoustic methods. A nonlinear, two-frequency mixing technique has been implemented, and a specific optical device has been developed in order to validate the experimental results. The acoustically reconstructed histograms are in excellent agreement with those obtained using optical methods.

Progressive damage, fracture predictions and post mortem correlations for fiber composites

NASA Technical Reports Server (NTRS)

1985-01-01

Lewis Research Center is involved in the development of computational mechanics methods for predicting the structural behavior and response of composite structures. In conjunction with the analytical methods development, experimental programs including post failure examination are conducted to study various factors affecting composite fracture such as laminate thickness effects, ply configuration, and notch sensitivity. Results indicate that the analytical capabilities incorporated in the CODSTRAN computer code are effective in predicting the progressive damage and fracture of composite structures. In addition, the results being generated are establishing a data base which will aid in the characterization of composite fracture.

Design and Fabrication of Cherenkov Counters for the Detection of SNM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson, Anna S.; Lanza, Richard; Galaitsis, Anthony

2011-12-13

The need for large-size detectors for long-range active interrogation (AI) detection of SNM has generated interest in water-based detector technologies. Water Cherenkov Detectors (WCD) were selected for this research because of their transportability, scalability, and an inherent energy threshold. The detector design and analysis was completed using the Geant4 toolkit. It was demonstrated both computationally and experimentally that it is possible to use WCD to detect and characterize gamma rays. Absolute efficiency of the detector (with no energy cuts applied) was determined to be around 30% for a {sup 60}Co source.

Synergy between scientific advancement and technological innovation, illustrated by a mechanism-based model characterizing sodium-glucose cotransporter-2 inhibition.

PubMed

Zhang, Liping; Ng, Chee M; List, James F; Pfister, Marc

2010-09-01

Advances in experimental medicine and technological innovation during the past century have brought tremendous progress in modern medicine and generated an ever-increasing amount of data from bench and bedside. The desire to extend scientific knowledge motivates effective data integration. Technological innovation makes this possible, which in turn accelerates the advancement in science. This mutually beneficial interaction is illustrated by the development of an expanded mechanism-based model for understanding a novel mechanism, sodium-glucose cotransporter-2 SGLT2 inhibition for potential treatment of type 2 diabetes mellitus.

Highly Unsaturated Platinum and Palladium Carbenes PtC 3 and PdC 3 Isolated and Characterized in the Gas Phase

DOE PAGES

Bittner, Dror M.; Zaleski, Daniel P.; Tew, David P.; ...

2016-02-16

Carbenes of platinum and palladium, PtC 3 and PdC 3 , were generated in the gas phase through laser vaporization of a metal target in the presence of a low concentration of a hydrocarbon precursor undergoing supersonic expansion. Rotational spectroscopy and abinitio calculations confirm that both molecules are linear. The geometry of PtC 3 was accurately determined by fitting to the experimental moments of inertia of twenty-six isotopologues. In conclusion, the results are consistent with the proposal of an autogenic isolobal relationship between O, Au + , and Ptatoms.

Characterization of vascular complications in experimental model of fructose-induced metabolic syndrome.

PubMed

El-Bassossy, Hany M; Dsokey, Nora; Fahmy, Ahmed

2014-12-01

Vascular dysfunction is an important complication associated with metabolic syndrome (MS). Here we fully characterized vascular complications in a rat model of fructose-induced MS. MS was induced by adding fructose (10%) to drinking water to male Wistar rats of 6 weeks age. Blood pressure (BP) and isolated aorta responses phenylephrine (PE), KCl, acetylcholine (ACh), and sodium nitroprusside (SNP) were recorded after 6, 9, and 12 weeks of fructose administration. In addition, serum levels of glucose, insulin, uric acid, tumor necrosis factor α (TNFα), lipids, advanced glycation end products (AGEs), and arginase activity were determined. Furthermore, aortic reactive oxygen species (ROS) generation, hemeoxygenase-1 expression, and collagen deposition were examined. Fructose administration resulted in a significant hyperinslinemia after 6 weeks which continued for 12 weeks. It was also associated with a significant increase in BP after 6 weeks which was stable for 12 weeks. Aorta isolated from MS animals showed exaggerated contractility to PE and KCl and impaired relaxation to ACh compared with control after 6 weeks which were clearer at 12 weeks of fructose administration. In addition, MS animals showed significant increases in serum levels of lipids, uric acid, AGEs, TNFα, and arginase enzyme activity after 12 weeks of fructose administration. Furthermore, aortae isolated from MS animals were characterized by increased ROS generation and collagen deposition. In conclusion, adding fructose (10%) to drinking water produces a model of MS with vascular complications after 12 weeks that are characterized by insulin resistance, hypertension, disturbed vascular reactivity and structure, hyperuricemia, dyslipidemia, and low-grade inflammation.

Nonlinear Optical Properties of Traditional and Novel Materials

NASA Astrophysics Data System (ADS)

Krupa, Sean J.

Nonlinear optical processes are an excellent candidate to provide the heralded, indistinguishable, or entangled photons necessary for development of quantum mechanics based technology which currently lack bright sources of these photons. In order to support these technologies, and others, two classes of materials: traditional and novel, were investigated via optical characterization methods with goal of gaining insight into which materials and experimental conditions yield the greatest nonlinear optical effects. Optical characterization of periodically poled lithium niobate (PPLN) helped support the development of a simple, efficient photon pair source that could be easily integrated into optical networks. Additionally, an in-situ measurement of the 2nd order nonlinear optical coefficient was developed to aid in the characterization of PPLN pair sources. Lastly, an undergraduate demonstration of quantum key distribution was constructed such that students could see the primary application for PPLN photon pair sources in an affordable, approachable demonstration. A class of novel optical materials known as 2D materials has been identified as potential replacements to the traditional nonlinear optical materials discussed in Part I. Through optical characterization of second harmonic generation (SHG) the ideal conditions for spontaneous parametric downconversion were established as well as signal thresholds for successful detection. Attempts to observe SPDC produces hints that weak generate SPDC may be present in WS2 samples however this is incredibly difficult to confirm. As growth techniques of 2D materials improve, a photonic device constructed from these materials may be possible, however it will need some mechanism e.g. stacking, a cavity, etc. to help enhance the SPDC signal.

Replacing critical rare earth materials in high energy density magnets

NASA Astrophysics Data System (ADS)

McCallum, R. William

2012-02-01

High energy density permanent magnets are crucial to the design of internal permanent magnet motors (IPM) for hybride and electric vehicles and direct drive wind generators. Current motor designs use rare earth permanent magnets which easily meet the performance goals, however, the rising concerns over cost and foreign control of the current supply of rare earth resources has motivated a search for non-rare earth based permanent magnets alloys with performance metrics which allow the design of permanent magnet motors and generators without rare earth magnets. This talk will discuss the state of non-rare-earth permanent magnets and efforts to both improve the current materials and find new materials. These efforts combine first principles calculations and meso-scale magnetic modeling with advance characterization and synthesis techniques in order to advance the state of the art in non rare earth permanent magnets. The use of genetic algorithms in first principle structural calculations, combinatorial synthesis in the experimental search for materials, atom probe microscopy to characterize grain boundaries on the atomic level, and other state of the art techniques will be discussed. In addition the possibility of replacing critical rare earth elements with the most abundant rare earth Ce will be discussed.

Generation and partial characterization of an eosinophil chemotactic cytokine produced by sensitized equine mononuclear cells stimulated with Strongylus vulgaris antigen.

PubMed

Dennis, V A; Klei, T R; Chapman, M R

1993-07-01

Supernatants generated by stimulation of peripheral blood mononuclear cells (PBMC) from Strongylus vulgaris sensitized or immunized ponies were assayed in vitro for eosinophil chemotactic activity (ECA) using the filter system in blind well chambers. The supernatants from these cultures were chemotactic for eosinophils, but not for neutrophils. Supernates from cultures of unsensitized PBMC stimulated with S. vulgaris antigen were not chemotactic for eosinophils. ECA was first detected in culture supernatants after 1.5 h of incubation and was dependent on both antigen and PBMC concentrations, but independent of serum concentrations. Both female and male S. vulgaris worm antigens stimulated ECA production from sensitized PBMC. ECA was not induced by in vitro stimulation of sensitized S. vulgaris PBMC by female Strongylus edentatus worm antigen. Partial characterization of the eosinophil chemotactic cytokine showed it to be nondialyzable, greater than 8000 molecular weight (MW), and sensitive to heating (56 and 95 degrees C), trypsin, and sodium metaperiodate treatments, suggesting that the cytokine is a protein containing some essential carbohydrate moieties. The cytokine described in this paper could partially contribute to the in vivo blood and tissue eosinophilia in experimental S. vulgaris infection.

Regulation of muscle contraction by Drebrin-like protein 1 probed by atomic force microscopy

NASA Astrophysics Data System (ADS)

Garces, Renata; Butkevich, Eugenia; Platen, Mitja; Schmidt, Christoph F.; Biophysics Team

Sarcomeres are the fundamental contractile units of striated muscle cells. They are composed of a variety of structural and regulatory proteins functioning in a precisely orchestrated fashion to enable coordinated force generation in striated muscles. Recently, we have identified a C. elegans drebrin-like protein 1 (DBN-1) as a novel sarcomere component, which stabilizes actin filaments during muscle contraction. To further characterize the function of DBN-1 in muscle cells, we generated a new dbn-1 loss-of-function allele. Absence of DBN-1 resulted in a unique worm movement phenotype, characterized by hyper-bending. It is not clear yet if DBN-1 acts to enhance or reduce the capacity for contraction. We present here an experimental mechanical study on C. elegans muscle mechanics. We measured the stiffness of the worm by indenting living C. eleganswith a micron-sized sphere adhered to the cantilever of an atomic force microscope (AFM). Modeling the worm as a pressurized elastic shell allows us to monitor the axial tension in the muscle through the measured stiffness. We compared responses of wild-type and mutant C. elegans in which DBN-1 is not expressed..

Experimental characterization of a small custom-built double-acting gamma-type stirling engine

NASA Astrophysics Data System (ADS)

Intsiful, Peter; Mensah, Francis; Thorpe, Arthur

This paper investigates characterization of a small custom-built double-acting gamma-type stirling engine. Stirling-cycle engine is a reciprocating energy conversion machine with working spaces operating under conditions of oscillating pressure and flow. These conditions may be due to compressibility as wells as pressure and temperature fluctuations. In standard literature, research indicates that there is lack of basic physics to account for the transport phenomena that manifest themselves in the working spaces of reciprocating engines. Previous techniques involve governing equations: mass, momentum and energy. Some authors use engineering thermodynamics. None of these approaches addresses this particular engine. A technique for observing and analyzing the behavior of this engine via parametric spectral profiles has been developed, using laser beams. These profiles enabled the generation of pv-curves and other trajectories for investigating the thermos-physical and thermos-hydrodynamic phenomena that manifest in the exchangers. The engine's performance was examined. The results indicate that with current load of 35.78A, electric power of 0.505 kW was generated at a speed of 240 rpm and 29.50 percent efficiency was obtained. Nasa grants to Howard University NASA/HBCU-NHRETU & CSTEA.

Experimental study of plume induced by nanosecond repetitively pulsed spark microdischarges in air at atmospheric pressure

NASA Astrophysics Data System (ADS)

Orriere, Thomas; Benard, Nicolas; Moreau, Eric; Pai, David

2016-09-01

Nanosecond repetitively pulsed (NRP) spark discharges have been widely studied due to their high chemical reactivity, low gas temperature, and high ionization efficiency. They are useful in many research areas: nanomaterials synthesis, combustion, and aerodynamic flow control. In all of these fields, particular attention has been devoted to chemical species transport and/or hydrodynamic and thermal effects for applications. The aim of this study is to generate an electro-thermal plume by combining an NRP spark microdischarge in a pin-to-pin configuration with a third DC-biased electrode placed a few centimeters away. First, electrical characterization and optical emission spectroscopy were performed to reveal important plasma processes. Second, particle image velocimetry was combined with schlieren photography to investigate the main characteristics of the generated flow. Heating processes are measured by using the N2(C ->B) (0,2) and (1,3) vibrational bands, and effects due to the confinement of the discharge are described. Moreover, the presence of atomic ions N+ and O+ is discussed. Finally, the electro-thermal plume structure is characterized by a flow velocity around 1.8 m.s-1, and the thermal kernel has a spheroidal shape.

Experimental Flight Characterization of a Canard-Controlled, Subsonic Missile

DTIC Science & Technology

2017-08-01

ARL-TR-8086 ● AUG 2017 US Army Research Laboratory Experimental Flight Characterization of a Canard- Controlled , Subsonic Missile...Laboratory Experimental Flight Characterization of a Canard- Controlled , Subsonic Missile by Frank Fresconi, Ilmars Celmins, James Maley, and...valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) August 2017 2. REPORT TYPE Technical

Chemoenzymatic Synthesis, Characterization, and Scale-Up of Milk Thistle Flavonolignan Glucuronides.

PubMed

Gufford, Brandon T; Graf, Tyler N; Paguigan, Noemi D; Oberlies, Nicholas H; Paine, Mary F

2015-11-01

Plant-based therapeutics, including herbal products, continue to represent a growing facet of the contemporary health care market. Mechanistic descriptions of the pharmacokinetics and pharmacodynamics of constituents composing these products remain nascent, particularly for metabolites produced following herbal product ingestion. Generation and characterization of authentic metabolite standards are essential to improve the quantitative mechanistic understanding of herbal product disposition in both in vitro and in vivo systems. Using the model herbal product, milk thistle, the objective of this work was to biosynthesize multimilligram quantities of glucuronides of select constituents (flavonolignans) to fill multiple knowledge gaps in the understanding of herbal product disposition and action. A partnership between clinical pharmacology and natural products chemistry expertise was leveraged to optimize reaction conditions for efficient glucuronide formation and evaluate alternate enzyme and reagent sources to improve cost effectiveness. Optimized reaction conditions used at least one-fourth the amount of microsomal protein (from bovine liver) and cofactor (UDP glucuronic acid) compared with typical conditions using human-derived subcellular fractions, providing substantial cost savings. Glucuronidation was flavonolignan-dependent. Silybin A, silybin B, isosilybin A, and isosilybin B generated five, four, four, and three monoglucuronides, respectively. Large-scale synthesis (40 mg of starting material) generated three glucuronides of silybin A: silybin A-7-O-β-D-glucuronide (15.7 mg), silybin A-5-O-β-D-glucuronide (1.6 mg), and silybin A-4´´-O-β-D-glucuronide (11.1 mg). This optimized, cost-efficient method lays the foundation for a systematic approach to synthesize and characterize herbal product constituent glucuronides, enabling an improved understanding of mechanisms underlying herbal product disposition and action. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Shock-induced microstructural response of mono- and nanocrystalline SiC ceramics

NASA Astrophysics Data System (ADS)

Branicio, Paulo S.; Zhang, Jingyun; Rino, José P.; Nakano, Aiichiro; Kalia, Rajiv K.; Vashishta, Priya

2018-04-01

The dynamic behavior of mono- and nanocrystalline SiC ceramics under plane shock loading is revealed using molecular-dynamics simulations. The generation of shock-induced elastic compression, plastic deformation, and structural phase transformation is characterized at different crystallographic directions as well as on a 5-nm grain size nanostructure at 10 K and 300 K. Shock profiles are calculated in a wide range of particle velocities 0.1-6.0 km/s. The predicted Hugoniot agree well with experimental data. Results indicate the generation of elastic waves for particle velocities below 0.8-1.9 km/s, depending on the crystallographic direction. In the intermediate range of particle velocities between 2 and 5 km/s, the shock wave splits into an elastic precursor and a zinc blende-to-rock salt structural transformation wave, which is triggered by shock pressure over the ˜90 GPa threshold value. A plastic wave, with a strong deformation twinning component, is generated ahead of the transformation wave for shocks in the velocity range between 1.5 and 3 km/s. For particle velocities greater than 5-6 km/s, a single overdriven transformation wave is generated. Surprisingly, shocks on the nanocrystalline sample reveal the absence of wave splitting, and elastic, plastic, and transformation wave components are seamlessly connected as the shock strength is continuously increased. The calculated strengths 15.2, 31.4, and 30.9 GPa for ⟨001⟩, ⟨111⟩, and ⟨110⟩ directions and 12.3 GPa for the nanocrystalline sample at the Hugoniot elastic limit are in excellent agreement with experimental data.

A new test procedure to evaluate the performance of substations for collective heating systems

NASA Astrophysics Data System (ADS)

Baetens, Robin; Verhaert, Ivan

2017-11-01

The overall heat demand of a single dwelling, existing out of space heating and domestic hot water production, decreases due to higher insulation rates. Because of this, investing in efficient and renewable heat generation becomes less interesting. Therefore, to incorporate renewables or residual heat on a larger scale, district heating or collective heating systems grow in importance. Within this set-up, the substation is responsible for the interaction between local demand for comfort and overall energy performance of the collective heating system. Many different configurations of substations exist, which influence both local comfort and central system performance. Next to that, also hybrids exist with additional local energy input. To evaluate performance of such substations, a new experimental-based test procedure is developed in order to evaluate these different aspects, characterized by the two roles a substation has, namely as heat generator and as heat consumer. The advantage of this approach is that an objective comparison between individual and central systems regarding performance on delivering local comfort can be executed experimentally. The lab set-up consists out of three different subsystems, namely the central system, the domestic hot water consumption and the local space heating. The central system can work with different temperature regimes and control strategies, as these aspects have proven to have the largest influence on actual performance. The domestic hot water system is able to generate similar tap profiles according to eco-design regulation for domestic hot water generation. The space heating system is able to demand a modular heat load.

Development of neutron/gamma generators and a polymer semiconductor detector for homeland security applications

NASA Astrophysics Data System (ADS)

King, Michael Joseph

Instrumentation development is essential to the advancement and success of homeland security systems. Active interrogation techniques that scan luggage and cargo containers for shielded special nuclear materials or explosives hold great potential in halting further terrorist attacks. The development of more economical, compact and efficient source and radiation detection devices will facilitate scanning of all containers and luggage while maintaining high-throughput and low-false alarms Innovative ion sources were developed for two novel, specialized neutron generating devices and initial generator tests were performed. In addition, a low-energy acceleration gamma generator was developed and its performance characterized. Finally, an organic semiconductor was investigated for direct fast neutron detection. A main part of the thesis work was the development of ion sources, crucial components of the neutron/gamma generator development. The use of an externally-driven radio-frequency antenna allows the ion source to generate high beam currents with high, mono-atomic species fractions while maintaining low operating pressures, advantageous parameters for neutron generators. A dual "S" shaped induction antenna was developed to satisfy the high current and large extraction area requirements of the high-intensity neutron generator. The dual antenna arrangement generated a suitable current density of 28 mA/cm2 at practical RF power levels. The stringent requirements of the Pulsed Fast Neutron Transmission Spectroscopy neutron generator necessitated the development of a specialized ten window ion source of toroidal shape with a narrow neutron production target at its center. An innovative ten antenna arrangement with parallel capacitors was developed for driving the multi-antenna arrangement and uniform coupling of RF power to all ten antennas was achieved. To address the desire for low-impact, low-radiation dose active interrogation systems, research was performed on mono-energetic gamma generators that operate at low-acceleration energies and leverage neutron generator technologies. The dissertation focused on the experimental characterization of the generator performance and involved MCNPX simulations to evaluate and analyze the experimental results. The emission of the 11.7 MeV gamma-rays was observed to be slightly anisotropic and the gamma yield was measured to be 2.0*105 gamma/s-mA. The lanthanum hexaboride target suffered beam damage from a high power density beam; however, this may be overcome by sweeping the beam across a larger target area. The efficient detection of fast neutrons is vital to active interrogation techniques for the detection of both SNM and explosives. Novel organic semiconductors are air-stable, low-cost materials that demonstrate direct electronic particle detection. As part of the development of a pi-conjugated organic polymer for fast neutron detection, charge generation and collection properties were investigated. By devising a dual, thin-film detector test arrangement, charge collection was measured for high energy protons traversing the dual detector arrangement that allowed the creation of variable track lengths by tilting the detector. The results demonstrated that an increase in track length resulted in a decreased signal collection. This can be understood by assuming charge carrier transport along the track instead of along the field lines, which was made possible by the filling of traps. However, this charge collection mechanism may be insufficient to generate a useful signal. This dissertation has explored the viability of a new generation of radiation sources and detectors, where the newly developed ion source technologies and prototype generators will further enhance the capabilities of existing threat detection systems and promote the development of cutting-edge detection technologies.

Toward Understanding Pore Formation And Mobility During Controlled Directional Solidification In A Microgravity Environment Investigation (PFMI)

NASA Technical Reports Server (NTRS)

Grugel, R. N.; Anilkumar, A.; Luz, P.; Jeter, L.; Volz, M. P.; Spivey, R.; Smith, G. A.; Curreri, Peter A. (Technical Monitor)

2002-01-01

The generation and inclusion of detrimental porosity, e.g., "pipes" and "rattails" can occur during controlled directional solidification processing. The origin of these defects is generally attributed to gas evolution and entrapment during solidification of the melt. On Earth, owing to buoyancy, an initiated bubble can rapidly rise through the liquid melt and "pop" at the surface; this is obviously not ensured in a low gravity or microgravity environment. Clearly, porosity generation and inclusion is detrimental to conducting any meaningful solidification-science studies in microgravity. Thus it is essential that model experiments be conducted in microgravity, to understand the details of the generation and mobility of porosity, so that methods can be found to eliminate it. In hindsight, this is particularly relevant given the results of the previous directional solidification experiments conducted in Space. The current International Space Station (ISS) Microgravity Science Glovebox (MSG) investigation addresses the central issue of porosity formation and mobility during controlled directional solidification processing in microgravity. The study will be done using a transparent metal-analogue material, succinonitrile (SCN) and succinonitrile-water "alloys", so that direct observation and recording of pore generation and mobility can be made during the experiments. Succinonitrile is particularly well suited for the proposed investigation because it is transparent, it solidifies in a manner analogous to most metals, it has a convenient melting point, its material properties are well characterized and, it has been successfully used in previous microgravity experiments. The PFMI experiment will be launched on the UF-2, STS-111 flight. Highlighting the porosity development problem in metal alloys during microgravity processing, the poster will describe: (i) the intent of the proposed experiments, (ii) the theoretical rationale behind using SCN as the study material for porosity generation and migration and, (iii) the experimental protocol for the investigation of the effects of the processing parameters. Photographs of the flight experimental hardware, and the novel sample ampoule, will be exhibited. The experimental apparatus will be described in detail and a summary of the scientific objectives will be presented.

Toward Understanding Pore Formation and Mobility during Controlled Directional Solidification in a Microgravity Environment Investigation (PFMI)

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Anilkumar, A. V.; Luz, Paul; Jeter, Linda; Volz, Martin P.; Spivey, Reggie; Smith, G.

2003-01-01

The generation and inclusion of detrimental porosity, e.g., pipes and rattails can occur during controlled directional solidification processing. The origin of these defects is generally attributed to gas evolution and entrapment during solidification of the melt. On Earth, owing to buoyancy, an initiated bubble can rapidly rise through the liquid melt and pop at the surface; this is obviously not ensured in a low gravity or microgravity environment. Clearly, porosity generation and inclusion is detrimental to conducting any meaningful solidification-science studies in microgravity. Thus it is essential that model experiments be conducted in microgravity, to understand the details of the generation and mobility of porosity, so that methods can be found to eliminate it. In hindsight, this is particularly relevant given the results of the previous directional solidification experiments conducted in Space. The current International Space Station (ISS) Microgravity Science Glovebox (MSG) investigation addresses the central issue of porosity formation and mobility during controlled directional solidification processing in microgravity. The study will be done using a transparent metal-analogue material, succinonitrile (SCN) and succinonitrile-water 'alloys', so that direct observation and recording of pore generation and mobility can be made during the experiments. Succinonitrile is particularly well suited for the proposed investigation because it is transparent, it solidifies in a manner analogous to most metals, it has a convenient melting point, its material properties are well characterized and, it has been successfully used in previous microgravity experiments. The PFMI experiment will be launched on the UF-2, STS-111 flight. Highlighting the porosity development problem in metal alloys during microgravity processing, the poster will describe: (i) the intent of the proposed experiments, (ii) the theoretical rationale behind using SCN as the study material for porosity generation and migration and, (iii) the experimental protocol for the investigation of the effects of the processing parameters. Photographs of the flight experimental hardware, and the novel sample ampoule, will be exhibited. The experimental apparatus will be described in detail and a summary of the scientific objectives will be presented.

Radionuclide 131I-labeled multifunctional dendrimers for targeted SPECT imaging and radiotherapy of tumors

NASA Astrophysics Data System (ADS)

Zhu, Jingyi; Zhao, Lingzhou; Cheng, Yongjun; Xiong, Zhijuan; Tang, Yueqin; Shen, Mingwu; Zhao, Jinhua; Shi, Xiangyang

2015-10-01

We report the synthesis, characterization, and utilization of radioactive 131I-labeled multifunctional dendrimers for targeted single-photon emission computed tomography (SPECT) imaging and radiotherapy of tumors. In this study, amine-terminated poly(amidoamine) dendrimers of generation 5 (G5.NH2) were sequentially modified with 3-(4'-hydroxyphenyl)propionic acid-OSu (HPAO) and folic acid (FA) linked with polyethylene glycol (PEG), followed by acetylation modification of the dendrimer remaining surface amines and labeling of radioactive iodine-131 (131I). The generated multifunctional 131I-G5.NHAc-HPAO-PEG-FA dendrimers were characterized via different methods. We show that prior to 131I labeling, the G5.NHAc-HPAO-PEG-FA dendrimers conjugated with approximately 9.4 HPAO moieties per dendrimer are noncytotoxic at a concentration up to 20 μM and are able to target cancer cells overexpressing FA receptors (FAR), thanks to the modified FA ligands. In the presence of a phenol group, radioactive 131I is able to be efficiently labeled onto the dendrimer platform with good stability and high radiochemical purity, and render the platform with an ability for targeted SPECT imaging and radiotherapy of an FAR-overexpressing xenografted tumor model in vivo. The designed strategy to use the facile dendrimer nanotechnology may be extended to develop various radioactive theranostic nanoplatforms for targeted SPECT imaging and radiotherapy of different types of cancer.We report the synthesis, characterization, and utilization of radioactive 131I-labeled multifunctional dendrimers for targeted single-photon emission computed tomography (SPECT) imaging and radiotherapy of tumors. In this study, amine-terminated poly(amidoamine) dendrimers of generation 5 (G5.NH2) were sequentially modified with 3-(4'-hydroxyphenyl)propionic acid-OSu (HPAO) and folic acid (FA) linked with polyethylene glycol (PEG), followed by acetylation modification of the dendrimer remaining surface amines and labeling of radioactive iodine-131 (131I). The generated multifunctional 131I-G5.NHAc-HPAO-PEG-FA dendrimers were characterized via different methods. We show that prior to 131I labeling, the G5.NHAc-HPAO-PEG-FA dendrimers conjugated with approximately 9.4 HPAO moieties per dendrimer are noncytotoxic at a concentration up to 20 μM and are able to target cancer cells overexpressing FA receptors (FAR), thanks to the modified FA ligands. In the presence of a phenol group, radioactive 131I is able to be efficiently labeled onto the dendrimer platform with good stability and high radiochemical purity, and render the platform with an ability for targeted SPECT imaging and radiotherapy of an FAR-overexpressing xenografted tumor model in vivo. The designed strategy to use the facile dendrimer nanotechnology may be extended to develop various radioactive theranostic nanoplatforms for targeted SPECT imaging and radiotherapy of different types of cancer. Electronic supplementary information (ESI) available: Part of the experimental details and additional experimental results. See DOI: 10.1039/c5nr05585g

Highly Efficient Design-of-Experiments Methods for Combining CFD Analysis and Experimental Data

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Haller, Harold S.

2009-01-01

It is the purpose of this study to examine the impact of "highly efficient" Design-of-Experiments (DOE) methods for combining sets of CFD generated analysis data with smaller sets of Experimental test data in order to accurately predict performance results where experimental test data were not obtained. The study examines the impact of micro-ramp flow control on the shock wave boundary layer (SWBL) interaction where a complete paired set of data exist from both CFD analysis and Experimental measurements By combining the complete set of CFD analysis data composed of fifteen (15) cases with a smaller subset of experimental test data containing four/five (4/5) cases, compound data sets (CFD/EXP) were generated which allows the prediction of the complete set of Experimental results No statistical difference were found to exist between the combined (CFD/EXP) generated data sets and the complete Experimental data set composed of fifteen (15) cases. The same optimal micro-ramp configuration was obtained using the (CFD/EXP) generated data as obtained with the complete set of Experimental data, and the DOE response surfaces generated by the two data sets were also not statistically different.

Experimental investigation of powerful pulse current generators based on capacitive storage and explosive magnetic generators

NASA Astrophysics Data System (ADS)

Shurupov, A. V.; Zavalova, V. E.; Kozlov, A. V.; Shurupov, M. A.; Povareshkin, M. N.; Kozlov, A. A.; Shurupova, N. P.

2018-01-01

Experimental models of microsecond duration powerful generators of current pulses on the basis of explosive magnetic generators and voltage impulse generator have been developed for the electromagnetic pulse effects on energy facilities to verify their stability. Exacerbation of voltage pulse carried out through the use of electro explosive current interrupter made of copper wires with diameters of 80 and 120 μm. Experimental results of these models investigation are represented. Voltage fronts about 100 ns and the electric field strength of 800 kV/m are registered.

A Computational Clonal Analysis of the Developing Mouse Limb Bud

PubMed Central

Marcon, Luciano; Arqués, Carlos G.; Torres, Miguel S.; Sharpe, James

2011-01-01

A comprehensive spatio-temporal description of the tissue movements underlying organogenesis would be an extremely useful resource to developmental biology. Clonal analysis and fate mappings are popular experiments to study tissue movement during morphogenesis. Such experiments allow cell populations to be labeled at an early stage of development and to follow their spatial evolution over time. However, disentangling the cumulative effects of the multiple events responsible for the expansion of the labeled cell population is not always straightforward. To overcome this problem, we develop a novel computational method that combines accurate quantification of 2D limb bud morphologies and growth modeling to analyze mouse clonal data of early limb development. Firstly, we explore various tissue movements that match experimental limb bud shape changes. Secondly, by comparing computational clones with newly generated mouse clonal data we are able to choose and characterize the tissue movement map that better matches experimental data. Our computational analysis produces for the first time a two dimensional model of limb growth based on experimental data that can be used to better characterize limb tissue movement in space and time. The model shows that the distribution and shapes of clones can be described as a combination of anisotropic growth with isotropic cell mixing, without the need for lineage compartmentalization along the AP and PD axis. Lastly, we show that this comprehensive description can be used to reassess spatio-temporal gene regulations taking tissue movement into account and to investigate PD patterning hypothesis. PMID:21347315

Non-destructive testing techniques based on nonlinear methods for assessment of debonding in single lap joints

NASA Astrophysics Data System (ADS)

Scarselli, G.; Ciampa, F.; Ginzburg, D.; Meo, M.

2015-04-01

Nonlinear ultrasonic non-destructive evaluation (NDE) methods can be used for the identification of defects within adhesive bonds as they rely on the detection of nonlinear elastic features for the evaluation of the bond strength. In this paper the nonlinear content of the structural response of a single lap joint subjected to ultrasonic harmonic excitation is both numerically and experimentally evaluated to identify and characterize the defects within the bonded region. Different metallic samples with the same geometry were experimentally tested in order to characterize the debonding between two plates by using two surface bonded piezoelectric transducers in pitch-catch mode. The dynamic response of the damaged samples acquired by the single receiver sensor showed the presence of higher harmonics (2nd and 3rd) and subharmonics of the fundamental frequencies. These nonlinear elastic phenomena are clearly due to nonlinear effects induced by the poor adhesion between the two plates. A new constitutive model aimed at representing the nonlinear material response generated by the interaction of the ultrasonic waves with the adhesive joint is also presented. Such a model is implemented in an explicit FE software and uses a nonlinear user defined traction-displacement relationship implemented by means of a cohesive material user model interface. The developed model is verified for the different geometrical and material configurations. Good agreement between the experimental and numerical nonlinear response showed that this model can be used as a simple and useful tool for understanding the quality of the adhesive joint.

Plasma behaviour in the neighbourhood of the hot-spot during an active experiment

NASA Astrophysics Data System (ADS)

Sallago, Patricia

In order to study the physical quantities that characterize a plasma, several active experiments have been done by many researcher groups around the world. These experimental papers, describing their measurements and the observed phenomena under a variety of geomagnetical conditions, bring some clues about the plasma behaviour in the neighbourhood of the hot-spot during and soon after the turn-off of ionospheric heating devices. A review of these works was faced in the frame of the application of IAR (Argentinian Radioas-tronomy Institute), La Plata, Argentine, as a site of installation for the AMISR (Advanced Modular Incoherent Scatter Radar), in a contest of research projets called by NSF (National Scientific Foundation). The present contribution gives a possible theoretical explanation, based on the generation and propagation of Alfven waves, of the plasma behaviour in the neighbourhood of the hot-spot during an active experiment and, as a consequence, for some experimental results.

Progress In Plasma Accelerator Development for Dynamic Formation of Plasma Liners

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Cassibry, Jason T.; Griffin, Steven; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

An experimental plasma accelerator for magnetic target fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a coaxial pulsed plasma thruster (Figure 1). It has been tested experimentally and plasma jet velocities of approx.50 km/sec have been obtained. The plasma jet has been photographed with 10-ns exposure times to reveal a stable and repeatable plasma structure (Figure 2). Data for velocity profile information has been obtained using light pipes and magnetic probes embedded in the gun walls to record the plasma and current transit respectively at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter is being characterized and future work for second generation "ultra-low jitter" gun development is being identified.

Plasma Accelerator Development for Dynamic Formation of Plasma Liners: A Status Report

NASA Technical Reports Server (NTRS)

Thio, Y. C. Francis; Eskridge, Richard; Martin, Adam; Smith, James; Lee, Michael; Rodgers, Stephen L. (Technical Monitor)

2001-01-01

An experimental plasma accelerator for magnetic target fusion (MTF) applications under development at the NASA Marshall Space Flight Center is described. The accelerator is a pulsed plasma thruster and has been tested experimentally and plasma jet velocities of approximately 50 km/sec have been obtained. The plasma jet structure has been photographed with 10 ns exposure times to reveal a stable and repeatable plasma structure. Data for velocity profile information has been obtained using light pipes embedded in the gun walls to record the plasma transit at various barrel locations. Preliminary spatially resolved spectral data and magnetic field probe data are also presented. A high speed triggering system has been developed and tested as a means of reducing the gun "jitter". This jitter is being characterized and future work for second generation "ultra-low jitter" gun development is being identified.

Independent-particle models for light negative atomic ions

NASA Technical Reports Server (NTRS)

Ganas, P. S.; Talman, J. D.; Green, A. E. S.

1980-01-01

For the purposes of astrophysical, aeronomical, and laboratory application, a precise independent-particle model for electrons in negative atomic ions of the second and third period is discussed. The optimum-potential model (OPM) of Talman et al. (1979) is first used to generate numerical potentials for eight of these ions. Results for total energies and electron affinities are found to be very close to Hartree-Fock solutions. However, the OPM and HF electron affinities both depart significantly from experimental affinities. For this reason, two analytic potentials are developed whose inner energy levels are very close to the OPM and HF levels but whose last electron eigenvalues are adjusted precisely with the magnitudes of experimental affinities. These models are: (1) a four-parameter analytic characterization of the OPM potential and (2) a two-parameter potential model of the Green, Sellin, Zachor type. The system O(-) or e-O, which is important in upper atmospheric physics is examined in some detail.

Interaction of two walkers: wave-mediated energy and force.

PubMed

Borghesi, Christian; Moukhtar, Julien; Labousse, Matthieu; Eddi, Antonin; Fort, Emmanuel; Couder, Yves

2014-12-01

A bouncing droplet, self-propelled by its interaction with the waves it generates, forms a classical wave-particle association called a "walker." Previous works have demonstrated that the dynamics of a single walker is driven by its global surface wave field that retains information on its past trajectory. Here we investigate the energy stored in this wave field for two coupled walkers and how it conveys an interaction between them. For this purpose, we characterize experimentally the "promenade modes" where two walkers are bound and propagate together. Their possible binding distances take discrete values, and the velocity of the pair depends on their mutual binding. The mean parallel motion can be either rectilinear or oscillating. The experimental results are recovered analytically with a simple theoretical framework. A relation between the kinetic energy of the droplets and the total energy of the standing waves is established.

Debris characterization diagnostic for the NIF

NASA Astrophysics Data System (ADS)

Miller, M. C.; Celeste, J. R.; Stoyer, M. A.; Suter, L. J.; Tobin, M. T.; Grun, J.; Davis, J. F.; Barnes, C. W.; Wilson, D. C.

2001-01-01

Generation of debris from targets and by x-ray ablation of surrounding materials will be a matter of concern for experimenters and National Ignition Facility (NIF) operations. Target chamber and final optics protection, for example debris shield damage, drive the interest for NIF operations. Experimenters are primarily concerned with diagnostic survivability, separation of mechanical versus radiation induced test object response in the case of effects tests, and radiation transport through the debris field when the net radiation output is used to benchmark computer codes. In addition, radiochemical analysis of activated capsule debris during ignition shots can provide a measure of the ablator <ρr>. Conceptual design of the Debris Monitor and Rad-Chem Station, one of the NIF core diagnostics, is presented. Methods of debris collection, particle size and mass analysis, impulse measurement, and radiochemical analysis are given. A description of recent experiments involving debris collection and impulse measurement on the OMEGA and Pharos lasers is also provided.

Establishment of primary cell culture and an intracranial xenograft model of pediatric ependymoma: a prospect for therapy development and understanding of tumor biology.

PubMed

Pavon, Lorena Favaro; Sibov, Tatiana Tais; Caminada de Toledo, Silvia Regina; Mara de Oliveira, Daniela; Cabral, Francisco Romero; Gabriel de Souza, Jean; Boufleur, Pamela; Marti, Luciana C; Malheiros, Jackeline Moraes; Ferreira da Cruz, Edgar; Paiva, Fernando F; Malheiros, Suzana M F; de Paiva Neto, Manoel A; Tannús, Alberto; Mascarenhas de Oliveira, Sérgio; Silva, Nasjla Saba; Cappellano, Andrea Maria; Petrilli, Antonio Sérgio; Chudzinski-Tavassi, Ana Marisa; Cavalheiro, Sérgio

2018-04-24

Ependymoma (EPN), the third most common pediatric brain tumor, is a central nervous system (CNS) malignancy originating from the walls of the ventricular system. Surgical resection followed by radiation therapy has been the primary treatment for most pediatric intracranial EPNs. Despite numerous studies into the prognostic value of histological classification, the extent of surgical resection and adjuvant radiotherapy, there have been relatively few studies into the molecular and cellular biology of EPNs. We elucidated the ultrastructure of the cultured EPN cells and characterized their profile of immunophenotypic pluripotency markers (CD133, CD90, SSEA-3, CXCR4). We established an experimental EPN model by the intracerebroventricular infusion of EPN cells labeled with multimodal iron oxide nanoparticles (MION), thereby generating a tumor and providing a clinically relevant animal model. MRI analysis was shown to be a valuable tool when combined with effective MION labeling techniques to accompany EPN growth. We demonstrated that GFAP/CD133+CD90+/CD44+ EPN cells maintained key histopathological and growth characteristics of the original patient tumor. The characterization of EPN cells and the experimental model could facilitate biological studies and preclinical drug screening for pediatric EPNs. In this work, we established notoriously challenging primary cell culture of anaplastic EPNs (WHO grade III) localized in the posterior fossa (PF), using EPNs obtained from 1 to 10-year-old patients ( n = 07), and then characterized their immunophenotype and ultrastructure to finally develop a xenograft model.

Low-Turnover Drug Molecules: A Current Challenge for Drug Metabolism Scientists.

PubMed

Hutzler, J Matthew; Ring, Barbara J; Anderson, Shelby R

2015-12-01

In vitro assays using liver subcellular fractions or suspended hepatocytes for characterizing the metabolism of drug candidates play an integral role in the optimization strategy employed by medicinal chemists. However, conventional in vitro assays have limitations in their ability to predict clearance and generate metabolites for low-turnover (slowly metabolized) drug molecules. Due to a rapid loss in the activity of the drug-metabolizing enzymes, in vitro incubations are typically performed for a maximum of 1 hour with liver microsomes to 4 hours with suspended hepatocytes. Such incubations are insufficient to generate a robust metabolic response for compounds that are slowly metabolized. Thus, the challenge of accurately estimating low human clearance with confidence has emerged to be among the top challenges that drug metabolism scientists are confronted with today. In response, investigators have evaluated novel methodologies to extend incubation times and more sufficiently measure metabolism of low-turnover drugs. These methods include plated human hepatocytes in monoculture, and a novel in vitro methodology using a relay of sequential incubations with suspended cryopreserved hepatocytes. In addition, more complex in vitro cellular models, such as HepatoPac (Hepregen, Medford, MA), a micropatterned hepatocyte-fibroblast coculture system, and the HµREL (Beverley Hills, CA) hepatic coculture system, have been developed and characterized that demonstrate prolonged enzyme activity. In this review, the advantages and disadvantages of each of these in vitro methodologies as it relates to the prediction of clearance and metabolite identification will be described in an effort to provide drug metabolism scientists with the most up-to-date experimental options for dealing with the complex issue of low-turnover drug candidates. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Profiles in fibromyalgia: algometry, auditory evoked potentials and clinical characterization of different subtypes.

PubMed

Triñanes, Yolanda; González-Villar, Alberto; Gómez-Perretta, Claudio; Carrillo-de-la-Peña, María T

2014-11-01

The heterogeneity found in fibromyalgia (FM) patients has led to the investigation of disease subgroups, mainly based on clinical features. The aim of this study was to test the hypothesis that clinical FM subgroups are associated with different underlying pathophysiological mechanisms. Sixty-three FM patients were classified in type I or type II, according to the Fibromyalgia Impact Questionnaire (FIQ), and in mild/moderate versus severe FM, according to the severity of three cardinal symptoms considered in the American College of Rheumatology (ACR) 2010 criteria (unrefreshed sleep, cognitive problems and fatigue). To validate the subgroups obtained by these two classifications, we calculated the area under the receiver operating characteristic curves for various clinical variables and for two potential biomarkers of FM: Response to experimental pressure pain (algometry) and the amplitude/intensity slopes of the auditory evoked potentials (AEPs) obtained to stimuli of increasing intensity. The variables that best discriminated type I versus type II were those related to depression, while the indices of clinical or experimental pain (threshold or tolerance) did not significantly differ between them. The variables that best discriminated the mild/moderate versus severe subgroups were those related to the algometry. The AEPs did not allow discrimination among the generated subsets. The FIQ-based classification allows the identification of subgroups that differ in psychological distress, while the index based on the ACR 2010 criteria seems to be useful to characterize the severity of FM mainly based on hyperalgesia. The incorporation of potential biomarkers to generate or validate classification criteria is crucial to advance in the knowledge of FM and in the understanding of pathophysiological pathways.

Collapse dynamics of ultrasound contrast agent microbubbles

NASA Astrophysics Data System (ADS)

King, Daniel Alan

Ultrasound contrast agents (UCAs) are micron-sized gas bubbles encapsulated with thin shells on the order of nanometers thick. The damping effects of these viscoelastic coatings are widely known to significantly alter the bubble dynamics for linear and low-amplitude behavior; however, their effects on strongly nonlinear and destruction responses are much less studied. This dissertation examines the behaviors of single collapsing shelled microbubbles using experimental and theoretical methods. The study of their dynamics is particularly relevant for emerging experimental uses of UCAs which seek to leverage localized mechanical forces to create or avoid specialized biomedical effects. The central component in this work is the study of postexcitation rebound and collapse, observed acoustically to identify shell rupture and transient inertial cavitation of single UCA microbubbles. This time-domain analysis of the acoustic response provides a unique method for characterization of UCA destruction dynamics. The research contains a systematic documentation of single bubble postexcitation collapse through experimental measurement with the double passive cavitation detection (PCD) system at frequencies ranging from 0.9 to 7.1 MHz and peak rarefactional pressure amplitudes (PRPA) ranging from 230 kPa to 6.37 MPa. The double PCD setup is shown to improve the quality of collected data over previous setups by allowing symmetric responses from a localized confocal region to be identified. Postexcitation signal percentages are shown to generally follow trends consistent with other similar cavitation metrics such as inertial cavitation, with greater destruction observed at both increased PRPA and lower frequency over the tested ranges. Two different types of commercially available UCAs are characterized and found to have very different collapse thresholds; lipid-shelled Definity exhibits greater postexcitation at lower PRPAs than albumin-shelled Optison. Furthermore, by altering the size distributions of these UCAs, it is shown that the shell material has a large influence on the occurrence of postexcitation rebound at all tested frequencies while moderate alteration of the size distribution may only play a significant role within certain frequency ranges. Finally, the conditions which generate the experimental postexcitation signal are examined theoretically using several forms of single bubble models. Evidence is provided for the usefulness of modeling this large amplitude UCA behavior with a size-varying surface tension as described in the Marmottant model; better agreement for lipid-shelled Definity UCAs is obtained by considering the dynamic response with a rupturing shell rather than either a non-rupturing or nonexistent shell. Moreover, the modeling indicates that maximum radial expansion from the initial UCA size is a suitable metric to predict postexcitation collapse, and that both shell rupture and inertial cavitation are necessary conditions to generate this behavior. Postexcitation analysis is found to be a beneficial characterization metric for studying the destruction behaviors of single UCAs when measured with the double PCD setup. This work provides quantitative documentation of UCA collapse, exploration into UCA material properties which affect this collapse, and comparison of existing single bubble models with experimentally measured postexcitation signals.

Design and characterization of molecular nonlinear optical switches.

PubMed

Castet, Frédéric; Rodriguez, Vincent; Pozzo, Jean-Luc; Ducasse, Laurent; Plaquet, Aurélie; Champagne, Benoît

2013-11-19

Nanoscale structures, including molecules, supramolecules, polymers, functionalized surfaces, and crystalline/amorphous solids, can commute between two or more forms, displaying contrasts in their nonlinear optical (NLO) properties. Because of this property, they have high potential for applications in data storage, signal processing, and sensing. As potential candidates for integration into responsive materials, scientists have been intensely studying organic and organometallic molecules with switchable first hyperpolarizability over the past two decades. As a result of this, researchers have been able to synthesize and characterize several families of molecular NLO switches that differ by the stimulus used to trigger the commutation. These stimuli can include light irradiation, pH variation, redox reaction, and ion recognition, among others. The design of multistate (including several switchable units) and multifunctional (triggered with different stimuli) systems has also motivated a large amount of work, aiming at the improvement of the storage capacity of optical memories or the diversification of the addressability of the devices. In complement to the synthesis of the compounds and the characterization of their NLO responses by means of hyper-Rayleigh scattering, quantum chemical calculations play a key role in the design of molecular switches with high first hyperpolarizability contrasts. Through the latter, we can gain a fundamental understanding of the various factors governing the efficiency of the switches. These are not easily accessible experimentally, and include donor/acceptor contributions, frequency dispersion, and solvent effects. In this Account, we illustrate the similarities of the experimental and theoretical tools to design and characterize highly efficient NLO switches but also the difficulties in comparing them. After providing a critical overview of the different theoretical approaches used for evaluating the first hyperpolarizabilities, we report two case studies in which theoretical simulations have provided guidelines to design NLO switches with improved efficiencies. The first example presents the joint theoretical/experimental characterization of a new family of multi-addressable NLO switches based on benzazolo-oxazolidine derivatives. The second focuses on the photoinduced commutation in merocyanine-spiropyran systems, where the significant NLO contrast could be exploited for metal cation identification in a new generation of multiusage sensing devices. Finally, we illustrate the impact of environment on the NLO switching properties, with examples based on the keto-enol equilibrium in anil derivatives. Through these representative examples, we demonstrate that the rational design of molecular NLO switches, which combines experimental and theoretical approaches, has reached maturity. Future challenges consist in extending the investigated objects to supramolecular architectures involving several NLO-responsive units, in order to exploit their cooperative effects for enhancing the NLO responses and contrasts.

Ultrasound excited thermography: an efficient tool for the characterization of vertical cracks

NASA Astrophysics Data System (ADS)

Mendioroz, A.; Celorrio, R.; Salazar, A.

2017-11-01

Ultrasound excited thermography has gained a renewed interest in the last two decades as a nondestructive testing technique aimed at detecting and characterizing surface breaking and shallow subsurface discontinuities. It is based on measurement of the IR radiation emitted by the specimen surface to detect temperature rises produced by the heating of defects under high amplitude ultrasound excitation and is primarily addressed to flaws with contacting faces, such as kissing cracks or tight delaminations. The simplicity of application and the ability to detect small cracks in challenging media makes it an attractive emerging technology, which is still in a development stage. However, it has proven to provide an opportunity for the quantitative characterization of defects, mainly of vertical cracks. In this review, we present the principles of the technique and the different experimental implementations, we put it in context with other nondestructive tests and we summarize the work done in order to improve defect detectability and test reliability, with the final goal of determining the probability of detection. Then we review the contributions aimed at characterizing vertical cracks, i.e. retrieving the geometry and location of the crack from surface temperature data, generated by ultrasonic excitation.

Systematic Proteomic Approach to Characterize the Impacts of ...

EPA Pesticide Factsheets

Chemical interactions have posed a big challenge in toxicity characterization and human health risk assessment of environmental mixtures. To characterize the impacts of chemical interactions on protein and cytotoxicity responses to environmental mixtures, we established a systems biology approach integrating proteomics, bioinformatics, statistics, and computational toxicology to measure expression or phosphorylation levels of 21 critical toxicity pathway regulators and 445 downstream proteins in human BEAS-28 cells treated with 4 concentrations of nickel, 2 concentrations each of cadmium and chromium, as well as 12 defined binary and 8 defined ternary mixtures of these metals in vitro. Multivariate statistical analysis and mathematical modeling of the metal-mediated proteomic response patterns showed a high correlation between changes in protein expression or phosphorylation and cellular toxic responses to both individual metals and metal mixtures. Of the identified correlated proteins, only a small set of proteins including HIF-1a is likely to be responsible for selective cytotoxic responses to different metals and metals mixtures. Furthermore, support vector machine learning was utilized to computationally predict protein responses to uncharacterized metal mixtures using experimentally generated protein response profiles corresponding to known metal mixtures. This study provides a novel proteomic approach for characterization and prediction of toxicities of

Characterization of Radial Curved Fin Heat Sink under Natural and Forced Convection

NASA Astrophysics Data System (ADS)

Khadke, Rishikesh; Bhole, Kiran

2018-02-01

Heat exchangers are important structures widely used in power plants, food industries, refrigeration, and air conditioners and now widely used in computing systems. Finned type of heat sink is widely used in computing systems. The main aim of the design of the heat sink is to maintain the optimum temperature level. To achieve this goal so many geometrical configurations are implemented. This paper presents a characterization of radially curved fin heat sink under natural and forced convection. Forced convection is studied for the optimization of temperature for better efficiency. The different alternatives in geometry are considered in characterization are heat intensity, the height of the fin and speed of the fan. By recognizing these alternatives the heat sink is characterized by the heat flux usually generated in high-end PCs. The temperature drop characteristics across height and radial direction are presented for the constant heat input and air flow in the heat sink. The effect of dimensionless elevation height (0 ≤ Z* ≤ 1) and Elenbaas Number (0.4 ≤ El ≤ 2.8) of the heat sink were investigated for study of the Nusselt number. Based on experimental characterization, process plan has been developed for the selection of the similar heat sinks for desired output (heat dissipation and temperature distribution).

Development of a multiphysics model to characterize the responsive behavior of urea-sensitive hydrogel as biosensor.

PubMed

Goh, K B; Li, Hua; Lam, K Y

2017-05-15

A remarkable feature of biomaterials is their ability to deform in response to certain external bio-stimuli. Here, a novel biochemo-electro-mechanical model is developed for the numerical characterization of the urea-sensitive hydrogel in response to the external stimulus of urea. The urea sensitivity of the hydrogel is usually characterized by the states of ionization and denaturation of the immobilized urease, as such the model includes the effect of the fixed charge groups and temperature coupled with pH on the activity of the urease. Therefore, a novel rate of reaction equation is proposed to characterize the hydrolysis of urea that accounts for both the ionization and denaturation states of the urease subject to the environmental conditions. After examination with the published experimental data, it is thus confirmed that the model can characterize well the responsive behavior of the urea-sensitive hydrogel subject to the urea stimulus, including the distribution patterns of the electrical potential and pH of the hydrogel. The results point to an innovative means for generating electrical power via the enzyme-induced pH and electrical potential gradients, when the hydrogel comes in contact with the urea-rich solution, such as human urine. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantifying the Hydrodynamic Performance of an Explosively-Driven Two-Shock Source

NASA Astrophysics Data System (ADS)

Furlanetto, Michael; Bauer, Amy; King, Robert; Buttler, William; Olson, Russell; Hagelberg, Carl

2015-06-01

An explosively-driven experimental package capable of generating a tunable two-shock drive would enable a host of experiments in shock physics. To make the best use of such a platform, though, its symmetry, reproducibility, and performance must be characterized thoroughly. We report on a series of experiments on a particular two-shock design that used shock reverberation between the sample and a heavy anvil to produce a second shock. Drive package diameters were varied between 50 and 76 mm in order to investigate release wave propagation. We used proton radiography to characterize the detonation and reverberation fronts within the high explosive elements of the packages, as well as surface velocimetry to measure the resulting shock structure in the sample under study. By fielding more than twenty channels of velocimetry per shot, we were able to quantify the symmetry and reproducibility of the drive.

Terahertz photonic crystals

NASA Astrophysics Data System (ADS)

Jian, Zhongping

This thesis describes the study of two-dimensional photonic crystals slabs with terahertz time domain spectroscopy. In our study we first demonstrate the realization of planar photonic components to manipulate terahertz waves, and then characterize photonic crystals using terahertz pulses. Photonic crystal slabs at the scale of micrometers are first designed and fabricated free of defects. Terahertz time domain spectrometer generates and detects the electric fields of single-cycle terahertz pulses. By putting photonic crystals into waveguide geometry, we successfully demonstrate planar photonic components such as transmission filters, reflection frequency-selective filters, defects modes as well as superprisms. In the characterization study of out-of-plane properties of photonic crystal slabs, we observe very strong dispersion at low frequencies, guided resonance modes at middle frequencies, and a group velocity anomaly at high frequencies. We employ Finite Element Method and Finite-Difference Time-Domain method to simulate the photonic crystals, and excellent agreement is achieved between simulation results and experimental results.

Development and experimental characterization of a new non contact sensor for blade tip timing

NASA Astrophysics Data System (ADS)

Brouckaert, Jean-Francois; Marsili, Roberto; Rossi, Gianluca; Tomassini, Roberto

2012-06-01

Performances of blade tip timing measurement systems (BTT), recently used for non contact turbine blade vibration measurements, in terms of uncertainty and resolution are strongly affected by sensor characteristics. The sensors used for BTT generate pulses, to be used also for precise measurements of turbine blades time of arrival. All the literature on this measurement techniques do not address this problem in a clear way, defining the relevant dynamic and static sensor characteristics, fundamental for this application. Till now proximity sensors used are based on optical, capacitive, eddy current and microwave measuring principle. Also pressure sensors has been used. In this paper a new sensing principle is proposed. A proximity sensor based on magnetoresistive sensing element has been assembled end tested. A simple and portable test bench with variable speed, blade tip width, variable clearance was built and used in order to characterize the main sensor performances.

Design, fabrication, and characterization of a valveless magnetic travelling-wave micropump

NASA Astrophysics Data System (ADS)

Yu, Huawei; Ye, Weixiang; Zhang, Wei; Yue, Zhao; Liu, Guohua

2015-06-01

In this paper, we propose a valveless magnetic micropump for lab-on-a-chip and microfluidic applications. The micropump, based on polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA), consists primarily of a saw-toothed microchannel, two substrates, and two integrated NdFeB permanent magnetic arrays. The travelling wave beneath the top wall of the elastic microchannel can be induced by the proper magnetic pole orientation arrangement of these magnetic arrays, and the liquid particles are then transported along with the travelling wave in the microchannel. Appropriate geometry of the saw-toothed microchannel was also studied for optimizing the performance of the micropump. Experimental characterization of the micropump has been performed in terms of the frequency response of the flow rate and backpressure. The results demonstrate that this micropump is capable of reliably generating a maximum flow rate of 342.4 μL min-1 and operating against a high backpressure of 1.67 kPa.

Chemical structure and dynamics: Annual report 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Colson, S.D.; McDowell, R.S.

1997-03-01

The Chemical Structure and Dynamics (CS&D) program is a major component of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) developed by Pacific Northwest National Laboratory (PNNL) to provide a state-of-the-art collaborative facility for studies of chemical structure and dynamics. We respond to the need for a fundamental, molecular-level understanding of chemistry at a wide variety of environmentally important interfaces by (1) extending the experimental characterization and theoretical description of chemical reactions to encompass the effects of condensed media and interfaces; (2) developing a multidisciplinary capability for describing interfacial chemical processes within which the new knowledge generated can bemore » brought to bear on complex phenomena in environmental chemistry and in nuclear waste processing and storage; and (3) developing state-of-the-art analytical methods for characterizing waste tanks and pollutant distributions, and for detecting and monitoring trace atmospheric species.« less

Optical gating and streaking of free electrons with sub-optical cycle precision

PubMed Central

Kozák, M.; McNeur, J.; Leedle, K. J.; Deng, H.; Schönenberger, N.; Ruehl, A.; Hartl, I.; Harris, J. S.; Byer, R. L.; Hommelhoff, P.

2017-01-01

The temporal resolution of ultrafast electron diffraction and microscopy experiments is currently limited by the available experimental techniques for the generation and characterization of electron bunches with single femtosecond or attosecond durations. Here, we present proof of principle experiments of an optical gating concept for free electrons via direct time-domain visualization of the sub-optical cycle energy and transverse momentum structure imprinted on the electron beam. We demonstrate a temporal resolution of 1.2±0.3 fs. The scheme is based on the synchronous interaction between electrons and the near-field mode of a dielectric nano-grating excited by a femtosecond laser pulse with an optical period duration of 6.5 fs. The sub-optical cycle resolution demonstrated here is promising for use in laser-driven streak cameras for attosecond temporal characterization of bunched particle beams as well as time-resolved experiments with free-electron beams. PMID:28120930

Functional profiles of orphan membrane transporters in the life cycle of the malaria parasite

PubMed Central

Kenthirapalan, Sanketha; Waters, Andrew P.; Matuschewski, Kai; Kooij, Taco W. A.

2016-01-01

Assigning function to orphan membrane transport proteins and prioritizing candidates for detailed biochemical characterization remain fundamental challenges and are particularly important for medically relevant pathogens, such as malaria parasites. Here we present a comprehensive genetic analysis of 35 orphan transport proteins of Plasmodium berghei during its life cycle in mice and Anopheles mosquitoes. Six genes, including four candidate aminophospholipid transporters, are refractory to gene deletion, indicative of essential functions. We generate and phenotypically characterize 29 mutant strains with deletions of individual transporter genes. Whereas seven genes appear to be dispensable under the experimental conditions tested, deletion of any of the 22 other genes leads to specific defects in life cycle progression in vivo and/or host transition. Our study provides growing support for a potential link between heavy metal homeostasis and host switching and reveals potential targets for rational design of new intervention strategies against malaria. PMID:26796412

Depth estimation of laser glass drilling based on optical differential measurements of acoustic response

NASA Astrophysics Data System (ADS)

Gorodesky, Niv; Ozana, Nisan; Berg, Yuval; Dolev, Omer; Danan, Yossef; Kotler, Zvi; Zalevsky, Zeev

2016-09-01

We present the first steps of a device suitable for characterization of complex 3D micro-structures. This method is based on an optical approach allowing extraction and separation of high frequency ultrasonic sound waves induced to the analyzed samples. Rapid, non-destructive characterization of 3D micro-structures are limited in terms of geometrical features and optical properties of the sample. We suggest a method which is based on temporal tracking of secondary speckle patterns generated when illuminating a sample with a laser probe while applying known periodic vibration using an ultrasound transmitter. In this paper we investigated lasers drilled through glass vias. The large aspect ratios of the vias possess a challenge for traditional microscopy techniques in analyzing depth and taper profiles of the vias. The correlation of the amplitude vibrations to the vias depths is experimentally demonstrated.

Modeling and testing of a tube-in-tube separation mechanism of bodies in space

NASA Astrophysics Data System (ADS)

Michaels, Dan; Gany, Alon

2016-12-01

A tube-in-tube concept for separation of bodies in space was investigated theoretically and experimentally. The separation system is based on generation of high pressure gas by combustion of solid propellant and restricting the expansion of the gas only by ejecting the two bodies in opposite directions, in such a fashion that maximizes generated impulse. An interior ballistics model was developed in order to investigate the potential benefits of the separation system for a large range of space body masses and for different design parameters such as geometry and propellant. The model takes into account solid propellant combustion, heat losses, and gas phase chemical reactions. The model shows that for large bodies (above 100 kg) and typical separation velocities of 5 m/s, the proposed separation mechanism may be characterized by a specific impulse of 25,000 s, two order of magnitude larger than that of conventional solid rockets. It means that the proposed separation system requires only 1% of the propellant mass that would be needed for a conventional rocket for the same mission. Since many existing launch vehicles obtain such separation velocities by using conventional solid rocket motors (retro-rockets), the implementation of the new separation system design can reduce dramatically the mass of the separation system and increase safety. A dedicated experimental setup was built in order to demonstrate the concept and validate the model. The experimental results revealed specific impulse values of up to 27,000 s and showed good correspondence with the model.

Experimental grid connected PV system power analysis

NASA Astrophysics Data System (ADS)

Semaoui, Smail; Abdeladim, Kamel; Arab, Amar Hadj; Boulahchich, Saliha; Amrouche, Said Ould; Yassaa, Noureddine

2018-05-01

Almost 80 % of Algerian territory is appropriate for the exploitation of solar energy. The Algerian energetic strategy provides a substantial injection of PV electricity to the national grid. Currently, about 344 MWp of PV arrays which corresponds approximately to 2,34 km2 of module surfaces, are connected on electricity grid over the national territory. The Algerian Northern regions are characterized by strong pollution and high humidity. These phenomena affect the energetic productivity of PV generator. The objective of our study is to analyze experimental grid connected PV system power in coastal locations. Hence, experiments have been conducted on three identical PV systems to determine the electrical performances. Transformer-less inverters are the most attractive for the ground-based photovoltaic (PV) system due to their efficiencies, reduced cost and weight. Besides, the absence of the galvanic isolation generates problems of capacitive leakage current on the AC side and the degradation of the insulation resistance on the DC side of the inverter. In this work, experimental study of the behavior of single-phase inverters without transformers is presented. The main objective of this work is to study the degradation of the insulation resistance at the input of the inverter, and the capacitive leakage current at the output of the inverter. This study was achieved at the CDER on a rainy day of 15/03/2017, on the first PV plant connected to the low voltage network in Algeria. This investigation can help forecasting the PV array energetic production by taking into account natural conditions.

The role of stochastic storms on hillslope runoff generation and connectivity in a dryland basin

NASA Astrophysics Data System (ADS)

Michaelides, K.; Singer, M. B.; Mudd, S. M.

2016-12-01

Despite low annual rainfall, dryland basins can generate significant surface runoff during certain rainstorms, which can cause flash flooding and high rates of erosion. However, it remains challenging to anticipate the nature and frequency of runoff generation in hydrological systems which are driven by spatially and temporally stochastic rainstorms. In particular, the stochasticity of rainfall presents challenges to simulating the hydrological response of dryland basins and understanding flow connectivity from hillslopes to the channel. Here we simulate hillslope runoff generation using rainfall characteristics produced by a simple stochastic rainfall generator, which is based on a rich rainfall dataset from the Walnut Gulch Experimental Watershed (WGEW) in Arizona, USA. We assess hillslope runoff generation using the hydrological model, COUP2D, driven by a subset of characteristic output from multiple ensembles of decadal monsoonal rainfall from the stochastic rainfall generator. The rainfall generator operates across WGEW by simulating storms with areas smaller than the basin and enables explicit characterization of rainfall characteristics at any location. We combine the characteristics of rainfall intensity and duration with data on rainstorm area and location to model the surface runoff properties (depth, velocity, duration, distance downslope) on a range of hillslopes within the basin derived from LiDAR analysis. We also analyze connectivity of flow from hillslopes to the channel for various combinations of hillslopes and storms. This approach provides a framework for understanding spatial and temporal dynamics of runoff generation and connectivity that is faithful to the hydrological characteristics of dryland environments.

Characterization of Defects in Scaled Mis Dielectrics with Variable Frequency Charge Pumping

NASA Astrophysics Data System (ADS)

Paulsen, Ronald Eugene

1995-01-01

Historically, the interface trap has been extensively investigated to determine the effects on device performance. Recently, much attention has been paid to trapping in near-interface oxide traps. Performance of high precision analog circuitry is affected by charge trapping in near-interface oxide traps which produces hysteresis, charge redistribution errors, and dielectric relaxation effects. In addition, the performance of low power digital circuitry, with reduced noise margins, may be drastically affected by the threshold voltage shifts associated with charge trapping in near -interface oxide traps. Since near-interface oxide traps may substantially alter the performance of devices, complete characterization of these defects is necessary. In this dissertation a new characterization technique, variable frequency charge pumping, is introduced which allows charge trapped at the interface to be distinguished from the charge trapped within the oxide. The new experimental technique is an extension of the charge pumping technique to low frequencies such that tunneling may occur from interface traps to near-interface oxide traps. A generalized charge pumping model, based on Shockley-Read-Hall statistics and trap-to-trap tunneling theory, has been developed which allows a more complete characterization of near-interface oxide traps. A pair of coupled differential equations governing the rate of change of occupied interface and near-interface oxide traps have been developed. Due to the experimental conditions in the charge pumping technique the equations may be decoupled, leading to an equation governing the rate of change of occupied interface traps and an equation governing the rate of change of occcupied near-interface oxide traps. Solving the interface trap equation and applying non-steady state charge dynamics leads to an interface trap component of the charge pumping current. In addition, solution to the near-interface oxide trap equation leads to an additional oxide trap component to the charge pumping current. Numerical simulations have been performed to support the analytical development of the generalized charge pumping model. By varying the frequency of the applied charge pumping waveform and monitoring the charge recombined per cycle, the contributions from interface traps may be separated from the contributions of the near-interface oxide traps. The generalized charge pumping model allows characterization of the density and spatial distribution of near-interface oxide traps from this variable frequency charge pumping technique. Characterization of interface and near-interface oxide trap generation has been performed on devices exposed to ionizing radiation, hot electron injection, and high -field/Fowler-Nordheim stressing. Finally, using SONOS nonvolatile memory devices, a framework has been established for experimentally determining not only the spatial distribution of near-interface oxide traps, but also the energetic distribution. An experimental approach, based on tri-level charge pumping, is discussed which allows the energetic distribution of near-interface oxide traps to be determined.

Dynamic Electromechanical Characterization of the Ferroelectric Ceramic PZT 95/5

NASA Astrophysics Data System (ADS)

Setchell, R. E.; Chhabildas, L. C.; Furnish, M. D.; Montgomery, S. T.; Holman, G. T.

1997-07-01

Shock-induced depoling of the ferroelectric ceramic PZT 95/5 has been utilized in a number of pulsed power applications. The dynamic behavior of the poled ceramic is complex, with nonlinear coupling between mechanical and electrical variables. Recent efforts to improve numerical simulations of this process have been limited by the scarcity of relevant experimental studies within the last twenty years. Consequently, we have initiated an extensive experimental study of the dynamic electromechanical behavior of this material. Samples of the poled ceramic are shocked to axial stresses from 0.5 to 5 GPa in planar impact experiments and observed with laser interferometry (VISAR) to obtain transmitted wave profiles. Current generation due to shock-induced depoling is observed using different external loads to vary electric field strengths within the samples. Experimental configurations either have the remanent polarization parallel to the direction of shock motion (axially poled) or perpendicular (normally poled). Initial experiments on unpoled samples utilized PVDF stress gauges as well as VISAR, and extended prior data on shock loading and release behavior. (Supported by the U. S. Department of Energy under contract DE-AC04-94AL85000). abstract.

Getting a grip on the transverse motion in a Zeeman decelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dulitz, Katrin; Softley, Timothy P., E-mail: tim.softley@chem.ox.ac.uk; Motsch, Michael

2014-03-14

Zeeman deceleration is an experimental technique in which inhomogeneous, time-dependent magnetic fields generated inside an array of solenoid coils are used to manipulate the velocity of a supersonic beam. A 12-stage Zeeman decelerator has been built and characterized using hydrogen atoms as a test system. The instrument has several original features including the possibility to replace each deceleration coil individually. In this article, we give a detailed description of the experimental setup, and illustrate its performance. We demonstrate that the overall acceptance in a Zeeman decelerator can be significantly increased with only minor changes to the setup itself. This ismore » achieved by applying a rather low, anti-parallel magnetic field in one of the solenoid coils that forms a temporally varying quadrupole field, and improves particle confinement in the transverse direction. The results are reproduced by three-dimensional numerical particle trajectory simulations thus allowing for a rigorous analysis of the experimental data. The findings suggest the use of a modified coil configuration to improve transverse focusing during the deceleration process.« less

Predicting repeat protein folding kinetics from an experimentally determined folding energy landscape

PubMed Central

Street, Timothy O; Barrick, Doug

2009-01-01

The Notch ankyrin domain is a repeat protein whose folding has been characterized through equilibrium and kinetic measurements. In previous work, equilibrium folding free energies of truncated constructs were used to generate an experimentally determined folding energy landscape (Mello and Barrick, Proc Natl Acad Sci USA 2004;101:14102–14107). Here, this folding energy landscape is used to parameterize a kinetic model in which local transition probabilities between partly folded states are based on energy values from the landscape. The landscape-based model correctly predicts highly diverse experimentally determined folding kinetics of the Notch ankyrin domain and sequence variants. These predictions include monophasic folding and biphasic unfolding, curvature in the unfolding limb of the chevron plot, population of a transient unfolding intermediate, relative folding rates of 19 variants spanning three orders of magnitude, and a change in the folding pathway that results from C-terminal stabilization. These findings indicate that the folding pathway(s) of the Notch ankyrin domain are thermodynamically selected: the primary determinants of kinetic behavior can be simply deduced from the local stability of individual repeats. PMID:19177351

Experimental High Temperature Characterization of a Magnetic Bearing for Turbomachinery

NASA Technical Reports Server (NTRS)

Montague, Gerald; Jansen, Mark; Provenza, Andrew; Palazzolo, Alan; Jansen, Ralph; Ebihara, Ben

2003-01-01

Open loop, experimental force and power measurements of a radial, redundant-axis, magnetic bearing at temperatures to 1000 F (538 C) and rotor speeds to 15,000 RPM along with theoretical temperature and force models are presented in this paper. The experimentally measured force produced by a single C-core using 22A was 600 lb. (2.67 kN) at room temperature and 380 lb. (1.69 kN) at 1000 F (538 C). These values were compared with force predictions based on a 1D magnetic circuit analysis and a thermal analysis of gap growth as a function of temperature. Tests under rotating conditions showed that rotor speed has a negligible effect on the bearing s load capacity. One C-core required approximately 340 W of power to generate 190 lb. (8.45 kN) of magnetic force at 1000 F (538 C); however the magnetic air gap was much larger than at room temperature. The data presented is after the bearing had already operated six thermal cycles and eleven total (not consecutive) hours at 1000 F (538 C).

An Experimental Framework for Generating Evolvable Chemical Systems in the Laboratory

NASA Astrophysics Data System (ADS)

Baum, David A.; Vetsigian, Kalin

2017-12-01

Most experimental work on the origin of life has focused on either characterizing the chemical synthesis of particular biochemicals and their precursors or on designing simple chemical systems that manifest life-like properties such as self-propagation or adaptive evolution. Here we propose a new class of experiments, analogous to artificial ecosystem selection, where we select for spontaneously forming self-propagating chemical assemblages in the lab and then seek evidence of a response to that selection as a key indicator that life-like chemical systems have arisen. Since surfaces and surface metabolism likely played an important role in the origin of life, a key experimental challenge is to find conditions that foster nucleation and spread of chemical consortia on surfaces. We propose high-throughput screening of a diverse set of conditions in order to identify combinations of "food," energy sources, and mineral surfaces that foster the emergence of surface-associated chemical consortia that are capable of adaptive evolution. Identification of such systems would greatly advance our understanding of the emergence of self-propagating entities and the onset of adaptive evolution during the origin of life.

Structural characterization of precious-mean quasiperiodic Mo/V single-crystal superlattices grown by dual-target magnetron sputtering

NASA Astrophysics Data System (ADS)

Birch, J.; Severin, M.; Wahlström, U.; Yamamoto, Y.; Radnoczi, G.; Riklund, R.; Sundgren, J.-E.; Wallenberg, L. R.

1990-05-01

A class of quasiperiodic superlattice structures, which can be generated by the concurrent inflation rule A-->AmB and B-->A (where m=positive integer), has been studied both theoretically and experimentally. Given that the ratios between the thicknesses of the two superlattice building blocks, A and B, are chosen to be γ(m)=[m+(m2+4)1/2]/2 (known as the ``precious means''), then the x-ray- and electron-diffraction peak positions are analytically found to be located at the wave vectors q=2πΛ-1r[γ(m)]k, where r and k are integers and Λ is an average superlattice wavelength. The analytically obtained results have been compared to experimental results from single-crystalline Mo/V superlattice structures, generated with m=1, 2, and 3. The superlattices were grown by dual-target dc-magnetron sputtering on MgO(001) substrates kept at 700 °C. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) showed that the analytical model mentioned above predicts the peak positions of the experimental XRD and SAED spectra with a very high accuracy. Furthermore, numerical calculations of the diffraction intensities based on a kinematical model of diffraction showed good agreement with the experimental data for all three cases. In addition to a direct verification of the quasiperiodic modulation, both conventional and high-resolution cross-sectional transmission electron microscopy (XTEM) showed that the superlattices are of high crystalline quality with sharp interfaces. Based on lattice resolution images, the width of the interfaces was determined to be less than two (002) lattice-plane spacings (~=0.31 nm).

Designing a SCAR molecular marker for monitoring Trichoderma cf. harzianum in experimental communities.

PubMed

Pérez, Gabriel; Verdejo, Valentina; Gondim-Porto, Clarissa; Orlando, Julieta; Carú, Margarita

2014-11-01

Several species of the fungal genus Trichoderma establish biological interactions with various micro- and macro-organisms. Some of these interactions are relevant in ecological terms and in biotechnological applications, such as biocontrol, where Trichoderma could be considered as an invasive species that colonizes a recipient community. The success of this invasion depends on multiple factors, which can be assayed using experimental communities as study models. Therefore, the aim of this work is to develop a species-specific sequence-characterized amplified region (SCAR) marker to monitor the colonization and growth of T. cf. harzianum when it invades experimental communities. For this study, 16 randomly amplified polymorphic DNA (RAPD) primers of 10-mer were used to generate polymorphic patterns, one of which generated a band present only in strains of T. cf. harzianum. This band was cloned, sequenced, and five primers of 20-23 mer were designed. Primer pairs 2F2/2R2 and 2F2/2R3 successfully and specifically amplified fragments of 278 and 448 bp from the T. cf. harzianum BpT10a strain DNA, respectively. Both primer pairs were also tested against the DNA from 14 strains of T. cf. harzianum and several strains of different fungal genera as specificity controls. Only the DNA from the strains of T. cf. harzianum was successfully amplified. Moreover, primer pair 2F2/2R2 was assessed by quantitative real-time polymerase chain reaction (PCR) using fungal DNA mixtures and DNA extracted from fungal experimental communities as templates. T. cf. harzianum was detectable even when as few as 100 copies of the SCAR marker were available or even when its population represented only 0.1% of the whole community.

Designing a SCAR molecular marker for monitoring Trichoderma cf. harzianum in experimental communities* #

PubMed Central

Pérez, Gabriel; Verdejo, Valentina; Gondim-Porto, Clarissa; Orlando, Julieta; Carú, Margarita

2014-01-01

Several species of the fungal genus Trichoderma establish biological interactions with various micro- and macro-organisms. Some of these interactions are relevant in ecological terms and in biotechnological applications, such as biocontrol, where Trichoderma could be considered as an invasive species that colonizes a recipient community. The success of this invasion depends on multiple factors, which can be assayed using experimental communities as study models. Therefore, the aim of this work is to develop a species-specific sequence-characterized amplified region (SCAR) marker to monitor the colonization and growth of T. cf. harzianum when it invades experimental communities. For this study, 16 randomly amplified polymorphic DNA (RAPD) primers of 10-mer were used to generate polymorphic patterns, one of which generated a band present only in strains of T. cf. harzianum. This band was cloned, sequenced, and five primers of 20–23 mer were designed. Primer pairs 2F2/2R2 and 2F2/2R3 successfully and specifically amplified fragments of 278 and 448 bp from the T. cf. harzianum BpT10a strain DNA, respectively. Both primer pairs were also tested against the DNA from 14 strains of T. cf. harzianum and several strains of different fungal genera as specificity controls. Only the DNA from the strains of T. cf. harzianum was successfully amplified. Moreover, primer pair 2F2/2R2 was assessed by quantitative real-time polymerase chain reaction (PCR) using fungal DNA mixtures and DNA extracted from fungal experimental communities as templates. T. cf. harzianum was detectable even when as few as 100 copies of the SCAR marker were available or even when its population represented only 0.1% of the whole community. PMID:25367789

Observation of beat oscillation generation by coupled waves associated with parametric decay during radio frequency wave heating of a spherical tokamak plasma.

PubMed

Nagashima, Yoshihiko; Oosako, Takuya; Takase, Yuichi; Ejiri, Akira; Watanabe, Osamu; Kobayashi, Hiroaki; Adachi, Yuuki; Tojo, Hiroshi; Yamaguchi, Takashi; Kurashina, Hiroki; Yamada, Kotaro; An, Byung Il; Kasahara, Hiroshi; Shimpo, Fujio; Kumazawa, Ryuhei; Hayashi, Hiroyuki; Matsuzawa, Haduki; Hiratsuka, Junichi; Hanashima, Kentaro; Kakuda, Hidetoshi; Sakamoto, Takuya; Wakatsuki, Takuma

2010-06-18

We present an observation of beat oscillation generation by coupled modes associated with parametric decay instability (PDI) during radio frequency (rf) wave heating experiments on the Tokyo Spherical Tokamak-2. Nearly identical PDI spectra, which are characterized by the coexistence of the rf pump wave, the lower-sideband wave, and the low-frequency oscillation in the ion-cyclotron range of frequency, are observed at various locations in the edge plasma. A bispectral power analysis was used to experimentally discriminate beat oscillation from the resonant mode for the first time. The pump and lower-sideband waves have resonant mode components, while the low-frequency oscillation is exclusively excited by nonlinear coupling of the pump and lower-sideband waves. Newly discovered nonlocal transport channels in spectral space and in real space via PDI are described.

Catenary optics for achromatic generation of perfect optical angular momentum

PubMed Central

Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

2015-01-01

The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a “true mathematical and mechanical form” in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer. PMID:26601283

Experiments and modelling of active quasi-single helicity regime generation in a reversed field pinch

NASA Astrophysics Data System (ADS)

Frassinetti, L.; Brunsell, P. R.; Drake, J. R.

2009-07-01

The interaction of a static resonant magnetic perturbation (RMP) with a tearing mode (TM) is becoming a relevant topic in fusion plasma physics. RMPs can be generated by active coils and then used to affect the properties of TMs and of the corresponding magnetic islands. This paper shows how the feedback system of the EXTRAP T2R reversed field pinch (RFP) can produce a RMP that affects a rotating TM and stimulate the transition to the so-called quasi-single helicity (QSH) regime, a RFP plasma state characterized by a magnetic island surrounded by low magnetic chaos. The application of the RMP can increase the QSH probability up to 10% and enlarge the size of the corresponding island. Part of the experimental results are supported by a theoretical study that models the effect of the active coils on the magnetic island.

Exploiting bistable oscillator subharmonics for magnified broadband vibration energy harvesting

NASA Astrophysics Data System (ADS)

Huguet, Thomas; Badel, Adrien; Lallart, Mickaël

2017-10-01

Recent research on primary battery alternatives for supplying autonomous wireless devices has recently highlighted the advantages of nonlinear oscillators' dynamics and more particularly bistable oscillators' behavior for ambient vibration harvesting. The key property of bistable oscillators compared to linear ones is their enhanced operational frequency bandwidth under harmonic excitation, potentially leading to a better adaptation to the environment. However, the classical frequency response characterization of such devices does not reveal all the possible dynamic behaviors offered by bistable oscillators. Thus, subharmonic motions are experimentally investigated in this letter, and their energy harvesting potential as well as their ability to enhance the bistable generator bandwidth is evaluated. The results obtained with a generator integrating buckled beams for the bistability feature show that, in addition to the commonly considered harmonic behavior, subharmonics allow widening of the useful operating frequency band of the bistable microgenerator by 180% compared to the sole exploitation of the first harmonic motion.

Second generation PMR polyimide/fiber composites

NASA Technical Reports Server (NTRS)

Cavano, P. J.

1979-01-01

A second generation polymerization monomeric reactants (PMR) polyimdes matrix system (PMR 2) was characterized in both neat resin and composite form with two different graphite fiber reinforcements. Three different formulated molecular weight levels of laboratory prepared PMR 2 were examined, in addition to a purchased experimental fully formulated PMR 2 precurser solution. Isothermal aging of graphite fibers, neat resin samples and composite specimens in air at 316 C were investigated. Humidity exposures at 65 C and 97 percent relative humidity were conducted for both neat resin and composites for eight day periods. Anaerobic char of neat resin and fire testing of composites were conducted with PMR 15, PMR 2, and an epoxy system. Composites were fire tested on a burner rig developed for this program. Results indicate that neat PMR 2 resins exhibit excellent isothermal resistance and that PMR 2 composite properties appear to be influenced by the thermo-oxidative stability of the reinforcing fiber.

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

DOE PAGES

Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.; ...

2014-08-20

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysicalmore » systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.« less

Experimental results from magnetized-jet experiments executed at the Jupiter Laser Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manuel, M. J. -E.; Kuranz, C. C.; Rasmus, A. M.

Recent experiments at the Jupiter Laser Facility investigated magnetization effects on collimated plasma jets. Laser-irradiated plastic-cone-targets produced collimated, millimeter-scale plasma flows as indicated by optical interferometry. Proton radiography of these jets showed no indication of strong, self-generated magnetic fields, suggesting a dominantly hydrodynamic collimating mechanism. Targets were placed in a custom-designed solenoid capable of generating field strengths up to 5 T. Proton radiographs of the well-characterized B-field, without a plasma jet, suggested an external source of trapped electrons that affects proton trajectories. The background magnetic field was aligned with the jet propagation direction, as is the case in many astrophysicalmore » systems. Optical interferometry showed that magnetization of the plasma results in disruption of the collimated flow and instead produces a hollow cavity. Furthermore, this result is a topic of ongoing investigation.« less

Light-induced depigmentation in planarians models the pathophysiology of acute porphyrias.

PubMed

Stubenhaus, Bradford M; Dustin, John P; Neverett, Emily R; Beaudry, Megan S; Nadeau, Leanna E; Burk-McCoy, Ethan; He, Xinwen; Pearson, Bret J; Pellettieri, Jason

2016-05-31

Porphyrias are disorders of heme metabolism frequently characterized by extreme photosensitivity. This symptom results from accumulation of porphyrins, tetrapyrrole intermediates in heme biosynthesis that generate reactive oxygen species when exposed to light, in the skin of affected individuals. Here we report that in addition to producing an ommochrome body pigment, the planarian flatworm Schmidtea mediterranea generates porphyrins in its subepithelial pigment cells under physiological conditions, and that this leads to pigment cell loss when animals are exposed to intense visible light. Remarkably, porphyrin biosynthesis and light-induced depigmentation are enhanced by starvation, recapitulating a common feature of some porphyrias - decreased nutrient intake precipitates an acute manifestation of the disease. Our results establish planarians as an experimentally tractable animal model for research into the pathophysiology of acute porphyrias, and potentially for the identification of novel pharmacological interventions capable of alleviating porphyrin-mediated photosensitivity or decoupling dieting and fasting from disease pathogenesis.

Defect generation in electronic devices under plasma exposure: Plasma-induced damage

NASA Astrophysics Data System (ADS)

Eriguchi, Koji

2017-06-01

The increasing demand for higher performance of ULSI circuits requires aggressive shrinkage of device feature sizes in accordance with Moore’s law. Plasma processing plays an important role in achieving fine patterns with anisotropic features in metal-oxide-semiconductor field-effect transistors (MOSFETs). This article comprehensively addresses the negative aspect of plasma processing — plasma-induced damage (PID). PID naturally not only modifies the surface morphology of materials but also degrades the performance and reliability of MOSFETs as a result of defect generation in the materials. Three key mechanisms of PID, i.e., physical, electrical, and photon-irradiation interactions, are overviewed in terms of modeling, characterization techniques, and experimental evidence reported so far. In addition, some of the emerging topics — control of parameter variability in ULSI circuits caused by PID and recovery of PID — are discussed as future perspectives.

A genomic perspective on the generation and maintenance of genetic diversity in herbivorous insects

PubMed Central

Gloss, Andrew D.; Groen, Simon C.; Whiteman, Noah K.

2017-01-01

Understanding the processes that generate and maintain genetic variation within populations is a central goal in evolutionary biology. Theory predicts that some of this variation is maintained as a consequence of adapting to variable habitats. Studies in herbivorous insects have played a key role in confirming this prediction. Here, we highlight theoretical and conceptual models for the maintenance of genetic diversity in herbivorous insects, empirical genomic studies testing these models, and pressing questions within the realm of evolutionary and functional genomic studies. To address key gaps, we propose an integrative approach combining population genomic scans for adaptation, genome-wide characterization of targets of selection through experimental manipulations, mapping the genetic architecture of traits influencing fitness, and functional studies. We also stress the importance of studying the maintenance of genetic variation across biological scales—from variation within populations to divergence among populations—to form a comprehensive view of adaptation in herbivorous insects. PMID:28736510

A low-cost programmable pulse generator for physiology and behavior

PubMed Central

Sanders, Joshua I.; Kepecs, Adam

2014-01-01

Precisely timed experimental manipulations of the brain and its sensory environment are often employed to reveal principles of brain function. While complex and reliable pulse trains for temporal stimulus control can be generated with commercial instruments, contemporary options remain expensive and proprietary. We have developed Pulse Pal, an open source device that allows users to create and trigger software-defined trains of voltage pulses with high temporal precision. Here we describe Pulse Pal’s circuitry and firmware, and characterize its precision and reliability. In addition, we supply online documentation with instructions for assembling, testing and installing Pulse Pal. While the device can be operated as a stand-alone instrument, we also provide application programming interfaces in several programming languages. As an inexpensive, flexible and open solution for temporal control, we anticipate that Pulse Pal will be used to address a wide range of instrumentation timing challenges in neuroscience research. PMID:25566051

Generation of first hard X-ray pulse at Tsinghua Thomson Scattering X-ray Source.

PubMed

Du, Yingchao; Yan, Lixin; Hua, Jianfei; Du, Qiang; Zhang, Zhen; Li, Renkai; Qian, Houjun; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

2013-05-01

Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard X-ray source in China based on the Thomson scattering between a terawatt ultrashort laser and relativistic electron beams. In this paper, we report the experimental generation and characterization of the first hard X-ray pulses (51.7 keV) via head-on collision of an 800 nm laser and 46.7 MeV electron beams. The measured yield is 1.0 × 10(6) per pulse with an electron bunch charge of 200 pC and laser pulse energy of 300 mJ. The angular intensity distribution and energy spectra of the X-ray pulse are measured with an electron-multiplying charge-coupled device using a CsI scintillator and silicon attenuators. These measurements agree well with theoretical and simulation predictions. An imaging test using the X-ray pulse at the TTX is also presented.

Experimental Investigation of Laser-sustained Plasma in Supersonic Argon Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sperber, David; Eckel, Hans-Albert; Moessinger, Peter

Laser-induced energy deposition is widely discussed as a flow control technique in supersonic transportation. In case of thermal laser-plasma upstream of a blunt body, a substantial adaptation of shock wave geometry and magnitude of wave drag is predicted. Related to the research on laser supported detonation, the paper describes the implementation of laser-sustained plasma in a supersonic Argon jet. The stable plasma state is generated by the intersection of a Q-switched Nd:YAG-laser and a continuous wave CO{sub 2}-laser beams, for ignition and maintenance of the plasma respectively. A miniature supersonic Ludwieg tube test facility generates a supersonic jet at velocitiesmore » of Mach 2.1. Modifications of the flow and plasma conditions are investigated and characterized by Schlieren flow visualisation, laser energy transmission and plasma radiation measurements. The results include the discussions of the flow field as well as the required laser and gas parameters.« less

Catenary optics for achromatic generation of perfect optical angular momentum.

PubMed

Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

2015-10-01

The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.

Experimental study of defoaming by air-borne power ultrasonic technology

NASA Astrophysics Data System (ADS)

Rodríguez, Germán; Riera, Enrique; Gallego-Juárez, Juan A.; Acosta, Víctor M.; Pinto, Alberto; Martínez, Ignacio; Blanco, Alfonso

2010-01-01

Foam is a dispersion of gas in a liquid in which the distances between the gas bubbles are very small. Foams are frequently generated in the manufacture of many products as result from the aeration and agitation of liquids, from the vaporization of the liquid and also from biological or chemical reactions. Foams are generally an unwanted product in industrial processes because they cause difficulties in process control and in equipment operation. The most efficient conventional method for defoaming is the use of chemical agents but they contaminate the product. High-intensity ultrasonic waves offer a clean procedure to break foam bubbles. The potential use of ultrasound for foam breaking that was known since many years has been recently reinforced by the application of a new type of ultrasonic defoamer based on the stepped-plate high-power transducers to generate air-borne ultrasound. This defoamer has been successfully applied in several industrial problems such as the control of excess foam produced during the filling operation of bottles and cans on high-speed canning lines and in fermenting vessels and other reactors of great dimensions. The treatment of such industrial problems requires the proper characterization and quantification of the main parameters involved in the mechanisms of the defoaming effect. This paper deals with an experimental study about the separate influence of such parameters with the aim of improving the application of the stepped-plate power ultrasonic generators for the production of the defoaming action on industrial processes

Developing a laser shockwave model for characterizing diffusion bonded interfaces

NASA Astrophysics Data System (ADS)

Lacy, Jeffrey M.; Smith, James A.; Rabin, Barry H.

2015-03-01

The US National Nuclear Security Agency has a Global Threat Reduction Initiative (GTRI) with the goal of reducing the worldwide use of high-enriched uranium (HEU). A salient component of that initiative is the conversion of research reactors from HEU to low enriched uranium (LEU) fuels. An innovative fuel is being developed to replace HEU in high-power research reactors. The new LEU fuel is a monolithic fuel made from a U-Mo alloy foil encapsulated in Al-6061 cladding. In order to support the fuel qualification process, the Laser Shockwave Technique (LST) is being developed to characterize the clad-clad and fuel-clad interface strengths in fresh and irradiated fuel plates. LST is a non-contact method that uses lasers for the generation and detection of large amplitude acoustic waves to characterize interfaces in nuclear fuel plates. However, because the deposition of laser energy into the containment layer on a specimen's surface is intractably complex, the shock wave energy is inferred from the surface velocity measured on the backside of the fuel plate and the depth of the impression left on the surface by the high pressure plasma pulse created by the shock laser. To help quantify the stresses generated at the interfaces, a finite element method (FEM) model is being utilized. This paper will report on initial efforts to develop and validate the model by comparing numerical and experimental results for back surface velocities and front surface depressions in a single aluminum plate representative of the fuel cladding.

WaterTransport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Vernon Cole; Abhra Roy; Ashok Damle

2012-10-02

Water management in Proton Exchange Membrane, PEM, Fuel Cells is challenging because of the inherent conflicts between the requirements for efficient low and high power operation. Particularly at low powers, adequate water must be supplied to sufficiently humidify the membrane or protons will not move through it adequately and resistance losses will decrease the cell efficiency. At high power density operation, more water is produced at the cathode than is necessary for membrane hydration. This excess water must be removed effectively or it will accumulate in the Gas Diffusion Layers, GDLs, between the gas channels and catalysts, blocking diffusion pathsmore » for reactants to reach the catalysts and potentially flooding the electrode. As power density of the cells is increased, the challenges arising from water management are expected to become more difficult to overcome simply due to the increased rate of liquid water generation relative to fuel cell volume. Thus, effectively addressing water management based issues is a key challenge in successful application of PEMFC systems. In this project, CFDRC and our partners used a combination of experimental characterization, controlled experimental studies of important processes governing how water moves through the fuel cell materials, and detailed models and simulations to improve understanding of water management in operating hydrogen PEM fuel cells. The characterization studies provided key data that is used as inputs to all state-of-the-art models for commercially important GDL materials. Experimental studies and microscopic scale models of how water moves through the GDLs showed that the water follows preferential paths, not branching like a river, as it moves toward the surface of the material. Experimental studies and detailed models of water and airflow in fuel cells channels demonstrated that such models can be used as an effective design tool to reduce operating pressure drop in the channels and the associated costs and weight of blowers and pumps to force air and hydrogen gas through the fuel cell. Promising improvements to materials structure and surface treatments that can potentially aid in managing the distribution and removal of liquid water were developed; and improved steady-state and freeze-thaw performance was demonstrated for a fuel cell stack under the self-humidified operating conditions that are promising for stationary power generation with reduced operating costs.« less

Nanobodies that block gating of the P2X7 ion channel ameliorate inflammation.

PubMed

Danquah, Welbeck; Meyer-Schwesinger, Catherine; Rissiek, Björn; Pinto, Carolina; Serracant-Prat, Arnau; Amadi, Miriam; Iacenda, Domenica; Knop, Jan-Hendrik; Hammel, Anna; Bergmann, Philine; Schwarz, Nicole; Assunção, Joana; Rotthier, Wendy; Haag, Friedrich; Tolosa, Eva; Bannas, Peter; Boué-Grabot, Eric; Magnus, Tim; Laeremans, Toon; Stortelers, Catelijne; Koch-Nolte, Friedrich

2016-11-23

Ion channels are desirable therapeutic targets, yet ion channel-directed drugs with high selectivity and few side effects are still needed. Unlike small-molecule inhibitors, antibodies are highly selective for target antigens but mostly fail to antagonize ion channel functions. Nanobodies-small, single-domain antibody fragments-may overcome these problems. P2X7 is a ligand-gated ion channel that, upon sensing adenosine 5'-triphosphate released by damaged cells, initiates a proinflammatory signaling cascade, including release of cytokines, such as interleukin-1β (IL-1β). To further explore its function, we generated and characterized nanobodies against mouse P2X7 that effectively blocked (13A7) or potentiated (14D5) gating of the channel. Systemic injection of nanobody 13A7 in mice blocked P2X7 on T cells and macrophages in vivo and ameliorated experimental glomerulonephritis and allergic contact dermatitis. We also generated nanobody Dano1, which specifically inhibited human P2X7. In endotoxin-treated human blood, Dano1 was 1000 times more potent in preventing IL-1β release than small-molecule P2X7 antagonists currently in clinical development. Our results show that nanobody technology can generate potent, specific therapeutics against ion channels, confirm P2X7 as a therapeutic target for inflammatory disorders, and characterize a potent new drug candidate that targets P2X7. Copyright © 2016, American Association for the Advancement of Science.