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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Search for New Phenomena in Dijet Angular Distributions in Proton-Proton Collisions at s = 8 TeV Measured with the ATLAS Detector

A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of √s=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb⁻¹. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Phase Demodulation by Frequency Chirping in Coherence Microwave Photonic Interferometry

This paper presents a signal processing method to demodulate the optical interference phase of cascaded individual optical fiber intrinsic Fabry-Perot interferometric (IFPI) sensors in a coherent microwave-photonic interferometry (CMPI) distributed sensing system. The new method utilizes the chirp effect of electro-optic modulator (EOM) to create a quasi-quadrature optical interference phase shift between two adjacent pulses which correspond to two adjacent reflection points in the time domain. The phase shift can be controlled by adjusting the bias voltage that is applied to the EOM. The interference phase is calculated by elliptically fitting the phase shift. The interference phase change is proportional to the optical path difference (OPD) change of the interferometer, and the sign can be used to differentiate the increase or decrease of the OPD. The method is demonstrated for distributed strain sensing, showing good linearity, high resolution and large dynamic range.

42 ENGINEERING↗
DOE OSTI2023

A Novel Design for Improving the Control on the Stainless-Steel Vessel Welding Process for Superconducting Magnets

Stainless steel vessels see widespread use in superconducting magnets for particle accelerator applications. Their function varies in different magnet designs: they always provide the necessary liquid helium containment, but in some cases are also used to provide azimuthal prestress and can also be welded to the magnet end plate to provide additional longitudinal stiffness. A magnet designed with the bladder and key technology does not rely on the structural role of the vessel. They are structurally supported using azimuthally prestressed aluminum shells, and the longitudinal constraint by rods. In this case, the magnet designer would generally like to minimize the interaction between the magnet and the stainless-steel vessel and to minimize the coil stress variation due to the vessel. The stress state in the vessel and in the coil is a function of the circumferential interference, defined as the vessel azimuthal length minus the magnet circumference. The vessel and the magnet azimuthal length machining tolerances are relatively large resulting in significant stress variations in the superconducting coils. Here in this paper we introduce an interference-control shim, which can significantly limit the stress variation of the coils for a given variation of the interference. The effectiveness of the interference-control shim is evaluated numerically on the MQXF, the low-β quadrupole for the High Luminosity LHC.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Spectroelectrochemical Sensors: New Polymer Films for Improved Sensitivity

The selectivity of an optical sensor can be improved by combining optical detection with electrochemical oxidation or reduction of the target analyte to change its spectral properties. The changing signal can distinguish the analyte from interferences with similar spectral properties that would otherwise interfere. The analyte is detected by measuring the intensity of the electrochemically modulated signal. In one form this spectroelectrochemical sensor consists of an optically transparent electrode (OTE) coated with a film that preconcentrates the target analyte. The OTE functions as an optical waveguide for attenuated total reflectance (ATR) spectroscopy, which detects the analyte by absorption. Sensitivity relies in part on a large change in molar absorptivity between the two oxidation states used for electrochemical modulation of the optical signal. A critical part of the sensor is the ion selective film. It should preconcentrate the analyte and exclude some interferences. At the same time the film must not interfere with the electrochemistry or the optical detection. Therefore, since the debut of the sensor’s concept one major focus of our group has been developing appropriate films for different analytes. Here we report the development of a series of quaternized poly(vinylpyridine)-co-styrene (QPVP-co-S) anion exchange films for use in spectroelectrochemical sensors to enable sensitive detection of target anionic analytes in complex samples. The films were either 10% or 20% styrene and were prepared with varying degrees of quaternized pyridine groups, up to 70%. Films were characterized with respect to thickness with spectroscopic ellipsometry, degree of quaternization with FTIR, and electrochemically and spectroelectrochemically using the anions ferrocyanide and pertechnetate.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2022

Ionization-Based Optical Structures for the Control of Short-Pulse Lasers (Abbreviated LDRD Report)

The intensity of light from the highest-power lasers is limited by the size of the optics required to amplify, compress, transport, and focus a laser beam. Indeed, optics damage puts strict constraints on the laser energy density that solid optics can sustain; this leads to enormous optics sizes and limits the maximum intensity that these lasers can achieve. In this project we investigated new types of diffractive optics based on mixtures of neutral gas and plasmas. The basic idea is to interfere laser beams in a gas near the ionization threshold, so that plasma is created in the constructive interference regions (i.e., the “bright” fringes of the interference pattern) while the destructive interference regions remain a neutral gas. The resulting refractive index modulation, due to the different indices in gas vs. plasma, effectively turns such structures into diffractive optics elements. We proposed several new types of optics based on this general concept: i) reflection gratings, which can act as mirrors of “pulse cleaners” to eliminate laser pre-pulse; ii) transmission gratings, as part of a new type of pulse compression scheme with the potential to achieve laser intensities orders of magnitude above what is currently feasible using solid-state optics; and iii) holographic lenses, to focus high-power lasers. We conducted laboratory experiments which demonstrated high efficiency reflection gratings, paving the way for practical applications of our new concepts.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

High-fidelity retrieval from instantaneous line-of-sight returns of nacelle-mounted lidar including supervised machine learning

Abstract. Wind turbine applications that leverage nacelle-mounted Doppler lidar are hampered by several sources of uncertainty in the lidar measurement, affecting both bias and random errors. Two problems encountered especially for nacelle-mounted lidar are solid interference due to intersection of the line of sight with solid objects behind, within, or in front of the measurement volume and spectral noise due primarily to limited photon capture. These two uncertainties, especially that due to solid interference, can be reduced with high-fidelity retrieval techniques (i.e., including both quality assurance/quality control and subsequent parameter estimation). Our work compares three such techniques, including conventional thresholding, advanced filtering, and a novel application of supervised machine learning with ensemble neural networks, based on their ability to reduce uncertainty introduced by the two observed nonideal spectral features while keeping data availability high. The approach leverages data from a field experiment involving a continuous-wave (CW) SpinnerLidar from the Technical University of Denmark (DTU) that provided scans of a wide range of flows both unwaked and waked by a field turbine. Independent measurements from an adjacent meteorological tower within the sampling volume permit experimental validation of the instantaneous velocity uncertainty remaining after retrieval that stems from solid interference and strong spectral noise, which is a validation that has not been performed previously. All three methods perform similarly for non-interfered returns, but the advanced filtering and machine learning techniques perform better when solid interference is present, which allows them to produce overall standard deviations of error between 0.2 and 0.3 m s−1, or a 1 %–22 % improvement versus the conventional thresholding technique, over the rotor height for the unwaked cases. Between the two improved techniques, the advanced filtering produces 3.5 % higher overall data availability, while the machine learning offers a faster runtime (i.e., ∼ 1 s to evaluate) that is therefore more commensurate with the requirements of real-time turbine control. The retrieval techniques are described in terms of application to CW lidar, though they are also relevant to pulsed lidar. Previous work by the authors (Brown and Herges, 2020) explored a novel attempt to quantify uncertainty in the output of a high-fidelity lidar retrieval technique using simulated lidar returns; this article provides true uncertainty quantification versus independent measurement and does so for three techniques rather than one.

47 OTHER INSTRUMENTATION↗
DOE OSTI2013

Large-scale fabrication of vertically aligned ZnO nanowire arrays

In a method for growing a nanowire array, a photoresist layer is placed onto a nanowire growth layer configured for growing nanowires therefrom. The photoresist layer is exposed to a coherent light interference pattern that includes periodically alternately spaced dark bands and light bands along a first orientation. The photoresist layer exposed to the coherent light interference pattern along a second orientation, transverse to the first orientation. The photoresist layer developed so as to remove photoresist from areas corresponding to areas of intersection of the dark bands of the interference pattern along the first orientation and the dark bands of the interference pattern along the second orientation, thereby leaving an ordered array of holes passing through the photoresist layer. The photoresist layer and the nanowire growth layer are placed into a nanowire growth environment, thereby growing nanowires from the nanowire growth layer through the array of holes.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Apparatus, system, and method for laser-induced breakdown spectroscopy

In laser-induced breakdown spectroscopy (LIBS), an apparatus includes a pulsed laser configured to generate a pulsed laser signal toward a sample, a constructive interference object and an optical element, each located in a path of light from the sample. The constructive interference object is configured to generate constructive interference patterns of the light. The optical element is configured to disperse the light. A LIBS system includes a first and a second optical element, and a data acquisition module. The data acquisition module is configured to determine an isotope measurement based, at least in part, on light received by an image sensor from the first and second optical elements. A method for performing LIBS includes generating a pulsed laser on a sample to generate light from a plasma, generating constructive interference patterns of the light, and dispersing the light into a plurality of wavelengths.

36 MATERIALS SCIENCE↗
DOE OSTI2023

A Novel Design for Improving the Control on the Stainless-Steel Vessel Welding Process for Superconducting Magnets

Stainless steel vessels see widespread use in superconducting magnets for particle accelerator applications. Their function varies in different magnet designs: they always provide the necessary liquid helium containment, but in some cases are also used to provide azimuthal prestress and can also be welded to the magnet end plate to provide additional longitudinal stiffness. A magnet designed with the bladder and key technology does not rely on the structural role of the vessel. They are structurally supported using azimuthally prestressed aluminum shells, and the longitudinal constraint by rods. In this case, the magnet designer would generally like to minimize the interaction between the magnet and the stainless-steel vessel and to minimize the coil stress variation due to the vessel. The stress state in the vessel and in the coil is a function of the circumferential interference, defined as the vessel azimuthal length minus the magnet circumference. The vessel and the magnet azimuthal length machining tolerances are relatively large resulting in significant stress variations in the superconducting coils. In this paper we introduce an interference control shim, which can significantly limit the stress variation of the coils for a given variation of the interference. The effectiveness of the interference-control shim is evaluated numerically on the MQXF, the low-β quadrupole for the High Luminosity LHC.

43 PARTICLE ACCELERATORS↗
DOE OSTI2019

Remote Technology to Retrieve Waste Below the 324 Building at the Hanford Site - 19622

The Waste Technology Engineering Laboratory (324 Building) is a Category 2 Nuclear Facility at Hanford. The 324 Building Disposition Project is responsible for the removal and remedial actions under CERCLA. Additionally, there are RCRA Dangerous Waste Management Units which the CERCLA actions are presumed to satisfy. The Radiochemical Engineering Complex (REC) is a group of four hot cells (A, B, C and D Cells) with an interconnecting airlock inside of the 324 Building. Underneath the REC B-Cell are contaminated soils that have an estimated 12,793 R/Hr dose rate and remediation is under CERCLA 300-FF-2 Operable Unit. The current action consists of debris removal from the floor of B-Cell, B-Cell floor removal, and excavation of the soils beneath the floor to a depth of up to twelve feet with four Remote Excavator Arms (REA). This paper provides insight into the preparation and performance of high tolerance core drilling into a hot cell complex. Installation of the REA Through Support (REA TS) mechanism through the 4'-6' concrete shield walls is a complex series of tasks with demanding tolerances at each of four locations around the perimeter of B-Cell. The use of training mock ups was included in the completion of this work. The REA TS is two 11 inch diameter high strength steel sleeves that have expandable collars at each end allowing the interstitial space between the outside of the sleeve and inside of the core drill to be grouted to form a substantial structural connection, and a 10 inch pipe with hydraulic hoses to power the REA. There are three cores required for each REA location. The REAs themselves are customized excavator arms, mounted on support columns to be used in the excavation and transfer of the contaminated soil into storage facilities. The tasks for the installation of the REA TSs are: 1) Characterization of B-Cell Cubicles. 2) Embedded Pipe Fill. 3) Interference Removal. a. Internal Walls, b. External Walls. 4) Core Drilling. 5) Go/No-Go gauge, and video inspection. 6) Installation of REA Through Support Assembly. The 324 Building REC Hot Cells have internal, external, and embedded utilities throughout the shield walls in conflict with the REA TS locations. Some of the embedded utilities have connection points inside of the B-Cell Cubicles. There were two separate issues at the conflicted locations. The first issue was the core drill cooling water would flow along the embedded utility potentially spreading legacy chemical and radiological contamination to areas of the facility that was unwanted. The second issue was that the REA TS required a substantial structural connection to the B-Cell wall, the cored diameter is larger than the REA TS and these interstitial areas required a full grouted connection. The embedded utilities posed a hazard that if unfilled, the interstitial grout would flow into the embedded utility and destabilize the required grouted structural connection. The B-Cell Cubicles had not been opened in over 10 years. A mockup was completed to install a glovebag over the cubicle opening and then to verify functionality and port requirements. The embedded utility pipe connections in the cubicles were then opened inside a glovebag to verify the correct connection points, connection method for future embedded pipe fill material delivery system, radiological characterization, and air flow to show that the embedded utility pipes were not blocked and would not pressurize. The embedded pipe fill material and grout system was mocked up and run several times to verify methodology and functionality. The B-Cell Cubicles were then reentered and the embedded utility pipe fill was completed using a hand pump. External interferences at the core drill locations were removed using standard interference removal techniques. Internal interferences at the core drill locations were removed using a remote cutting tool that was controlled through the use of the B-Cell crane, remote cameras and remote lighting. The core drilling was mocked up two separate times, the project's purpose built 'Mock Up Facility' was core drilled to verify tolerances and methodology prior to subcontract award, the core drill subcontractor built a 'dummy wall' to train and practice on achieving the demanding tolerances, coordinated alignments between the cores, short term and long term dose shielding techniques, and contamination control techniques. A core drill template, and additional anchoring techniques were used to maximize accuracy and precision of the REA TS core drills. A 'Go/No-Go' gauge was built and installed at each of the four REA TS locations to verify that the core drill met tolerances. The core drill locations were visually inspected using a boroscope. The REA TS installation was mocked up at the projects 'Mock Up Facility' beginning with basic hazard controls, then with intermediate hazard controls, and finally with full occupational safety, industrial hygiene, and radiological controls. The REA TSs were installed and grouted into place. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

SplitML

SplitML (Signal Processing Library for Interference rejecTion by Machine Learning) is a code repository for a set of tools for interference rejection in complex time-domain signals. The goal of the tools is to provide machine learning modeling capabilities for rejecting interference. Recent related machine learning algorithms for signal processing have focused mostly on speech enhancement or multi-speaker speech separation; the tools in SplitML will extend these innovations to generic time-domain signals of interest. SplitML includes tools for generating synthetic noisy signals, code for customized machine learning models applicable to interference rejection, and tools for evaluating such algorithms against standard signal processing techniques. These components are written in Python, a high-level programming language that takes advantage of the Python ecosystem of high-quality open-source packages for machine learning and signal processing.

Klein, Natalie↗
DOE OSTI2016

Trace-level perchlorate analysis of impacted groundwater by elevated gold ellipse dimer nanoantenna surface-enhanced Raman scattering

Perchlorate (ClO 4 - ) contamination has received increased attention the past two decades because of health concerns from its impact on thyroid function coupled with its environmental ubiquity and persistence. In this paper, we demonstrate the detection of ClO 4 - below micromolar (<1 × 10 -6 moles l -1 ) levels using a portable Raman instrument integrated with novel elevated gold (Au) ellipse dimer nanoantenna surface enhanced Raman scattering (SERS) architectures. The ellipse dimer nanoantenna architectures demonstrate improved ClO 4 - detection limits over previously reported SERS substrates while maintaining good reproducibility. The impact of chloride (Cl - ), nitrate (NO 3 - ), and sulfate (SO 4 2- ) interferences on the detection efficiency is systematically evaluated; SO 4 2- is found to exhibit the largest interference effect at low concentrations while at higher ion concentrations the interference effects among ions are similar. Finally and additionally, ClO 4 - concentrations on the order of 1 mg l -1 are determined in groundwaters collected from an US Department of Defense Navy site demonstrating the applicability of these SERS architectures for the rapid, field detection of trace-level ClO 4 - contamination within complex environmental samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

‘Superluminal paradox’ in wave packet propagation and its quantum mechanical resolution

We analyse in detail the reshaping mechanism leading to apparently ‘superluminal’ advancement of a wave packet traversing a classically forbidden region. In the coordinate representation, a barrier is shown to act as an effective beamsplitter, recombining envelopes of the freely propagating pulse with various spacial shifts. Causality ensures that none of the constituent envelopes are advanced with respect to free propagation, yet the resulting pulse is advanced due to a peculiar interference effect, similar to the one responsible for ‘anomalous’ values which occur in Aharonov’s ‘weak measurements’. In the momentum space, the effect is understood as a bandwidth phenomenon, where the incident pulse probes local, rather than global, analytical properties of the transmission amplitude T(p). The advancement is achieved when T(p) mimics locally an exponential behaviour, similar to the one occurring in Berry’s ‘superoscillations’. Seen in a broader quantum mechanical context, the ‘paradox’ is but a consequence of an attempt to obtain ‘which way?’ information without destroying the interference between the pathways of interest. This explains, to a large extent, the failure to adequately describe tunnelling in terms of a single ‘tunnelling time’. -- Highlights: •Apparent superluminality is described in the language of quantum measurements. •A barrier acts as a beamsplitter delaying copies of the initial pulse. •In the coordinate space the effect is similar to what occurs in ‘weak measurements’. •In the momentum space it relies on superoscillations in the transmission amplitude. •It is an interference effect, unlikely to be explained in simpler physical terms.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Improving the Effectiveness of Burst Buffers for Big Data Processing in HPC Systems with Eley

Here, burst buffer is an effective solution for reducing the data transfer time and the I/O interference in HPC systems. Extending Burst Buffers (BBs) to handle Big Data applications is challenging because BBs must account for the large data inputs of Big Data applications and the Quality-of-Service (QoS) of HPC applications which are considered as first-class citizens in HPC systems. Existing BBs focus on only intermediate data of Big Data applications and incur a high performance degradation of both Big Data and HPC applications. We present Eley , a burst buffer solution that helps to accelerate the performance of Big Data applications while guaranteeing the QoS of HPC applications. To achieve this goal, Eley embraces interference-aware prefetching technique that makes reading data input faster while introducing low interference for HPC applications. Evaluations using a wide range of Big Data and HPC applications demonstrate that Eley improves the performance of Big Data applications by up to 30% compared to existing BBs while maintaining the QoS of HPC applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2018

A Zn based anionic metal-organic framework for trace Hg{sup 2+} ion detection

Highlights: • The anionic MOF Zn-TPTC was prepared by solvothermal method. • Zn-TPTC was characterized by single crystal diffraction, PXRD, EA, TGA, etc. • The Hg{sup 2+} detection LOD was 3.67 nM, much lower than the U.S. EPA standard. • Zn-TPTC could exclude the interference of other ions. • Pore, anionic framework, multiple N sites are pivotal for effective Hg{sup 2+} detection. - Abstract: As one of the most toxic heavy metal ions, Hg{sup 2+} exists widely in the living surroundings of human beings and excessive Hg{sup 2+} possesses a great threat to human health. The maximum allowable concentration of Hg{sup 2+} in drinking water is only 10 nM (2 ppb) by U.S. EPA standard. Ionic metal-organic framework (iMOF) is considered in view of high sensitive, anti-interferential material for Hg{sup 2+} detection still remain a challenge. Herein we designed and synthesized a novel Zn based anionic MOF Zn-TPTC, which was characterized by single crystal diffraction and other method. Its performance on Hg{sup 2+} (10{sup -6}–10{sup -4} M) detection were studied and the detection limit (LOD) is calculated as low as 3.67 nM. Interference experiments showed that Zn-TPTC could exclude the interference of other ions, which could be attributed to the effective pore size, anionic framework and multiple N sites in ligand, providing us new ideas for the selection and design of MOF for detection application.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Germanium Sulfide Nano-Optics Probed by STEM-Cathodoluminescence Spectroscopy

Nano-optical studies of confined modes in planar waveguides have attracted significant interest as a means to probe exciton-polaritons and other hybrid light-matter quasiparticles in layered semiconductors, such as transition metal dichalcogenides or boron nitride. There is a need to broaden such studies to other materials and to identify alternatives to scanning near-field optical microscopy for exciting and measuring confined waveguide modes. Here, we establish an approach for probing the dispersion of traveling waveguide modes by cathodoluminescence spectroscopy excited by the focused electron beam in scanning transmission electron microscopy (STEM-CL) and apply it to solid-state resonators consisting of mesoscale monocrystalline prisms and plates composed of GeS, an anisotropic layered semiconductor with direct bandgap in the near-infrared spectral range. Structure, crystallography, and chemical composition of the mesostructures are analyzed by analytical electron microscopy. STEM-CL maps and spectra show pronounced interference effects and sharp emission peaks at photon energies below the fundamental bandgap of GeS. Our analysis demonstrates that locally excited light emission in STEM-CL launches in-plane waveguide modes in the mesoscale GeS structures, which are internally reflected by highly specular GeS edges to cause interference of the waveguide modes. Reabsorption and secondary luminescence give rise to the intensity modulations detected in the far field. In conclusion, our results highlight avenues for probing light-matter interactions below the diffraction limit in a wide range of quantum materials and open up the possibility of tuning light emission geometrically using interference rather than by the conventional bandgap engineering.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Rapid production of large-area deep sub-wavelength hybrid structures by femtosecond laser light-field tailoring

The goal of creation of large-area deep sub-wavelength nanostructures by femtosecond laser irradiation onto various materials is being hindered by the limited coherence length. Here, we report solution of the problem by light field tailoring of the incident beam with a phase mask, which serves generation of wavelets. Direct interference between the wavelets, here the first-order diffracted beams, and interference between a wavelet and its induced waves such as surface plasmon polariton are responsible for creation of microgratings and superimposed nanogratings, respectively. The principle of wavelets interference enables extension of uniformly induced hybrid structures containing deep sub-wavelength nanofeatures to macro-dimension.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Collision induced ultraviolet structure in nitrogen radar REMPI spectra

We present 2 + 2 radar REMPI measurements in molecular nitrogen under atmospheric conditions and observe a strong interference in the (1,0) vibrational band of the a{sup 1}Π{sub g} ← X{sup 1}Σ{sub g}{sup +} electronic manifold. The interference is suppressed by using circularly polarized light, permitting rotational analysis of the 2 + 2 radar REMPI spectrum. It is observed in pure nitrogen, though the structure varies with gas composition. The structure also varies with temperature and pressure. These results indicate that it is collision induced. We hypothesize that the source of the interference is a 3 + 1 REMPI process through the a{sup ″1}Σ{sub g}{sup +} electronic state.

74 ATOMIC AND MOLECULAR PHYSICS↗