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At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

DOE OSTI2023

Imaging systems and related methods including radar imaging with moving arrays or moving targets

Imaging systems, including radio frequency, microwave and millimeter-wave arrangements, and related methods are described. According to one aspect, an imaging system includes an antenna array, a position capture system configured to generate position information indicative of locations of one of the antenna array and the target at the first and second moments in time, and wherein the one of the antenna array and the target move between the first and second moments in time, a transceiver configured to control the antenna array to emit electromagnetic energy towards the target and to generate an output that is indicative of the received electromagnetic energy, a data acquisition system configured to generate radar data, processing circuitry configured to process the position information and the radar data to generate image data regarding the target, and an interface configured to use the image data to generate visual images regarding the target.

Sheen, David M.↗

DOE OSTI2024

Wireless power transfer apparatus with radially arrayed magnetic structures

An apparatus includes a first coil, a second coil having a first side facing a first side of the first coil, a first radial array of magnetic material bodies disposed on a second side of the first coil, and a second radial array of magnetic material bodies disposed on a second side of the second coil such that respective magnetic material bodies of the second radial array overlap respective magnetic material bodies of the first radial array. The apparatus may be included in a wireless power transfer system.

Pahl, Birger↗

DOE OSTI2024

Imaging systems and related methods including radar imaging with moving arrays or moving targets

Sheen, David M.↗

DOE OSTI2020

Trace-Level, Multi-Gas Detection for Food Quality Assessment Based on Decorated Silicon Transistor Arrays

Multiplexed gas detection at room temperature is critical for practical applications, such as for tracking the complex chemical environments associated with food decomposition and spoilage. Here, an integrated array of multiple silicon-based, chemical-sensitive field effect transistors (CSFETs) is presented to realize selective, sensitive, and simultaneous measurement of gases typically associated with food spoilage. CSFETs decorated with sensing materials based on ruthenium, silver, and silicon oxide are used to obtain stable room-temperature responses to ammonia (NH 3 ), hydrogen sulfide (H 2 S), and humidity, respectively. For example, one multi-CSFET sensor signal changes from its baseline by 13.34 in response to 1 ppm of NH 3 , 724.45 under 1 ppm H 2 S, and 23.46 under 80% relative humidity, with sensitive detection down to 10 ppb of NH 3 and H 2 S. To demonstrate this sensor for practical applications, the CSFET sensor array is combined with a custom-printed circuit board into a compact, fully integrated, and portable system to conduct real-time monitoring of gases generated by decomposing food. By using existing silicon-based manufacturing methodologies, this room-temperature gas sensing array can be fabricated reproducibly and at low cost, making it an attractive platform for ambient gas measurement needed in food safety applications.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Large-Area Periodic Arrays of Atomically Flat Single-Crystal Gold Nanotriangles Formed Directly on Substrate Surfaces

The advancement of nanoenabled wafer-based devices requires the establishment of core competencies related to the deterministic positioning of nanometric building blocks over large areas. Within this realm, plasmonic single-crystal gold nanotriangles represent one of the most attractive nanoscale components but where the formation of addressable arrays at scale has heretofore proven impracticable. In this work, a benchtop process is presented for the formation of large-area periodic arrays of gold nanotriangles. The devised growth pathway sees the formation of an array of defect-laden seeds using lithographic and vapor-phase assembly processes followed by their placement in a growth solution promoting planar growth and threefold symmetric side-faceting. The nanotriangles formed in this high-yield synthesis distinguish themselves in that they are epitaxially aligned with the underlying substrate, grown to thicknesses that are not readily obtainable in colloidal syntheses, and present atomically flat pristine surfaces exhibiting gold atoms with a close-packed structure. As such, they express crisp and unambiguous plasmonic modes and form photoactive surfaces with highly tunable and readily modeled plasmon resonances. The devised methods, hence, advance the integration of single-crystal gold nanotriangles into device platforms and provide an overall fabrication strategy that is adaptable to other nanomaterials.

42 ENGINEERING↗

DOE OSTI2020

Optical Design and Characterization of 40-GHz Detector and Module for the BICEP Array

Families of cosmic inflation models predict a primordial gravitational-wave background that imprints B-mode polarization pattern in the cosmic microwave background (CMB). High-sensitivity instruments with wide frequency coverage and well-controlled systematic errors are needed to constrain the faint B-mode amplitude. We have developed antenna-coupled transition edge sensor arrays for high-sensitivity polarized CMB observations over a wide range of millimeter-wave bands. BICEP array, the latest phase of the BICEP/Keck experiment series, is a multi-receiver experiment designed to search for inflationary B-mode polarization to a precision σ(r) between 0.002 and 0.004 after 3 full years of observations, depending on foreground complexity and the degree of lensing removal. We describe the electromagnetic design and measured performance of BICEP array’s low-frequency 40-GHz detector, their packaging in focal plane modules, and optical characterization including efficiency and beam matching between polarization pairs. We summarize the design and simulated optical performance, including an approach to improve the optical efficiency due to mismatch losses. Here, we report the measured beam maps for a new broadband corrugation design to minimize beam differential ellipticity between polarization pairs caused by interactions with the module housing frame, which helps minimize polarized beam mismatch that converts CMB temperature to polarization (T→P) anisotropy in CMB maps.

47 OTHER INSTRUMENTATION↗

DOE OSTI2024

Fabrication and Performance Evaluation of Double-Sided Copper Nanowire Arrays as Thermal and Electrical Interfacial Layers

Reducing contact interface thermal and electrical resistances is in great demand across various industries, particularly in the semiconductor industry. This study introduces an approach using double-sided copper nanowire (Cu NW) arrays on copper sheets as both thermal and electrical interfacial layers, designed to effectively accommodate the topographical inconsistencies between contact surfaces. Further, experimental outcomes reveal a significant reduction in thermal contact resistance (TCR), with a value of 2.5 mm 2 K W –1 , thereby exceeding the efficiency of reported nanostructural thermal interface materials (TIMs). Additionally, when utilized as an electrical interfacial layer, these double-sided Cu NWs arrays dramatically reduced electrical contact resistance (ECR), outperforming traditional conductive grease in applications necessitating separable bonding, though showing comparable performance to costly silver-based conductive epoxies required for permanent, inseparable bonds. The promising results of the double-sided Cu NWs arrays in reducing both TCR and ECR, confirmed by finite element simulation, highlight their substantial potential in advancing TIMs and electrical interconnection applications across various sectors.

42 ENGINEERING↗

DOE OSTI2020

Durian-Inspired Design of Bismuth–Antimony Alloy Arrays for Robust Sodium Storage

Sodium-ion batteries have attracted widespread attention for cost-effective and large-scale electric energy storage. However, their practical deployment has been largely retarded by the lack of choice of efficient anode materials featuring large capacity and electrochemical stability and robustness. Herein, we report a durian-inspired design and template-free fabrication of a robust sodium anode based on triangular pyramid arrays of Bi 0.75 Sb 0.25 alloy electrodeposited on Cu substrates. The Bi 0.75 Sb 0.25 arrays exhibit an appreciable electrochemical robustness for sodium storage, sustaining a reversible capability 335 mAh g –1 at a high rate of 2.5 A g –1 and 87% of the initial capacity over 2000 cycles. We further demonstrate the applicability of the Bi 0.75 Sb 0.25 array anode in sodium full cells by pairing it with a Na 3 V 2 (PO 4 ) 3 /C cathode. This full cell achieves a high specific energy of 203 Wh kg –1 (based on both active electrodes). Such an enhanced performance is attributed to the thorny-durian-like architecture and bimetallic alloy composition. In conclusion, the pyramid tip induces ion enrichment for rapid charge-transfer reaction, while the alloy design reduces the electrode volume swelling for stable Na cycling.

25 ENERGY STORAGE↗

DOE OSTI2022

The ultrafast pixel array camera system and its applications in high energy density physics

Diagnostics in high energy density physics, shock physics, and related fields are primarily driven by a need to record rapidly time-evolving signals in single-shot events. These measurements are often limited by channel count and signal degradation issues on cable links between the detector and digitizer. Here we present the Ultrafast Pixel Array Camera (UPAC), a compact and flexible detector readout system with 32 waveform-recording channels at up to 10 Gsample/s and 1.8 GHz analog bandwidth. The compact footprint allows the UPAC to be directly embedded in the detector environment. A key enabling technology is the PSEC4A chip, an eight-channel switch-capacitor array sampling device with up to 1056 samples/channel. The UPAC system includes a high-density input connector that can plug directly into an application-specific detector board, programmable control, and serial readout, with less than 5 W of power consumption in full operation. We present the UPAC design and characterization, including a measured timing resolution of ~20 ps or better on acquisitions of sub-nanosecond pulses with minimal system calibrations. Example applications of the UPAC are also shown to demonstrate operation of a solid-state streak camera, an ultrafast imaging array, and a neutron time-of-flight spectrometer.

47 OTHER INSTRUMENTATION↗

DOE OSTI2023

Effect of material composition of diamond field emission array cathodes on quality of transversely shaped beams

Diamond field emitter array field emission cathodes (DFEA FECs) are attractive for the next generation of injectors due to their ability to produce transversely shaped beams without the need for complex masking or laser schemes. However, reliability of this cathode technology remains a challenging issue as principal mechanisms guiding and allowing for output beam shaping remained poorly understood. Here, this paper reports the results of testing two DFEA FECs with the same pattern and emitter tip geometry. Although both cathodes were able to sustain gradients of 44 MV/m and produce maximum output integral charge of 0.5 nC per radio frequency pulse, their emission patterns were different. One cathode did not produce a shaped beam, while the other one did. This difference was explained by the extent of the local variations of the diamond material across the arrays as discovered by spatially resolved Raman spectroscopy. The main practical takeaways were (i) tip sharpness was not a prerequisite for producing a shaped beam and instead (ii) material characteristics resulting in different cathode ballast resistance affected emission spatial uniformity across the array and hence the beam shaping.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Simple accurate model of silicon donor arrays

Donors in silicon can now be positioned with an accuracy of about one lattice constant, making it possible to form donor arrays for quantum computation or quantum simulation applications. However, the multivalley character of the silicon conduction band combines with central cell corrections to the donor states to convert small atomic scale imperfections in donor placement into strong interdonor hybridization disorder. Here, we present a simple model that is able to account for central cell corrections accurately, and use it to assess the impact of donor positional disorder on donor array properties in both itinerant and localized limits. Our results show that donor arrays in silicon simulate strongly disordered one-dimensional electrons.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Electrolyzer Integrated Modular Nano-Array Monolithic Catalytic Reactors

The project objective is to design and develop a new class of electrolyzer-integrated, modular, nanostructure array (nano-array) monolithic catalytic reactors for high-flux, robust and selective methanol synthesis. The modular reactor features metal oxide nano-array grown on an additively-manufactured channeled honeycomb monolith made of ceramic or metals; this low-pressure carbon dioxide hydrogenation reactor is fueled with hydrogen from a low-temperature water electrolyzer having reduced platinum group metal (PGM) content. Through these nanostructured monolithic reactors, methanol synthesis is enabled with cost-effective hydrogenation reactions under low-temperature (<200°C) and low-pressure (<10 atm) conditions, thus significantly reducing the energy demand of the entire process.

08 HYDROGEN↗

DOE OSTI2023

Development of an advanced ultrasonic phased array for the characterization of thick, reinforced concrete components (Final Scientific/Technical Report)

There are no nondestructive evaluation (NDE) tools capable of characterizing microscale damage throughout the thickness of concrete components, due to the multiphase, heterogeneous and multiscale nature of concrete. Ultrasound is only scattered by features at the same length scale, or smaller, than the wavelength of a wave’s dominant frequency. Successful imaging of microscale damage using ultrasound requires that the ultrasonic wavelength be on the order of a few millimeters (or smaller), yet the heterogeneous microstructure of concrete, with its fine and coarse aggregates, is on this same (and higher) micrometer/millimeter length scale, causing excessive ultrasonic wave scattering even in “good” concrete. The proposed solution applies non-collinear wave mixing to spatially image microscale damage, while still maintaining penetration through thick concrete components. This microscale imaging is possible by combining nonlinear wave mixing, with advanced phased array hardware and software to develop a breakthrough tool that will bring revolutionary changes in NDE of concrete infrastructure in terms of image resolution and depth of penetration. This work uses non-collinear wave mixing which exploits the physics that material nonlinearities such as microscale damage, cause interactions between two intersecting ultrasonic waves due to cross-mixing, which can lead to the generation of a third wave with a frequency and wave number of the sum or difference of the incident waves. The concrete material volume at this mixing point is characterized/imaged. This project delivered a single-sided nonlinear ultrasonic phased array imaging device, that can image microscale damage (microcracks of 100 micrometers) through a 0.5 m thick concrete component and assessed the commercial feasibility of such arrays for improved crack detection.

42 ENGINEERING↗

DOE OSTI2024

RAFT: Reconfigurable Array of High-Efficiency Ducted Turbines for Hydrokinetic Energy Harvesting

Diversifying the energy harvesting portfolio is crucial to achieving the ambitious goal of transitioning to clean energy by 2030. Marine hydrokinetic energy has garnered renewed interest due to its high harvesting potential in the U.S., and the resource's reliability and predictability—remaining relatively constant on a daily basis and available 24/7. However, there are currently few commercial devices capable of harnessing the energy from flowing water. This project aims to bridge that gap by designing and evaluating a novel hydrokinetic turbine concept that can efficiently harvest energy from both rivers and tidal streams. The RAFT (Reconfigurable Array of High-Efficiency Ducted Turbines) concept introduces a duct surrounding the turbine rotor and creates an array of small 5-kW units. The duct serves two primary purposes: (1) it enhances hydrodynamic efficiency by accelerating flow to the rotor, and (2) it functions as a structural component, facilitating the formation of modular arrays that lower costs. This project focuses on demonstrating this concept and validating these benefits through simulations and scaled prototype testing. The project team includes 8 faculty members and over 20 students from 3 universities, organized into three core areas: hydrodynamics, electrical systems, and structural analysis, with additional teams dedicated to system integration, environmental assessment and risk management, and tech-to-market strategy. The team successfully demonstrated the increased hydrodynamic efficiency of a ducted turbine compared to an unducted version using high-fidelity simulations and prototype tests. Moreover, design optimization efforts led to surpassing the SHARKS program's goal of 60% reduction of the levelized cost of energy with a significant margin.

13 HYDRO ENERGY↗

DOE OSTI2022

Low-Power, Flexible Sensor Arrays with Solderless Board-to-Board Connectors for Monitoring Soil Deformation and Temperature

Landslides are a global and frequent natural hazard, affecting many communities and infrastructure networks. Technological solutions are needed for long-term, large-scale condition monitoring of infrastructure earthworks or natural slopes. However, current instruments for slope stability monitoring are often costly, require a complex installation process and/or data processing schemes, or have poor resolution. Wireless sensor networks comprising low-power, low-cost sensors have been shown to be a crucial part of landslide early warning systems. Here, we present the development of a novel sensing approach that uses linear arrays of three-axis accelerometers for monitoring changes in sensor inclination, and thus the surrounding soil’s deformation. By combining these deformation measurements with depth-resolved temperature measurements, we can link our data to subsurface thermal–hydrological regimes where relevant. In this research, we present a configuration of cascaded I2C sensors that (i) have ultra-low power consumption and (ii) enable an adjustable probe length. From an electromechanical perspective, we developed a novel board-to-board connection method that enables narrow, semi-flexible sensor arrays and a streamlined assembly process. The low-cost connection method relies on a specific FR4 printed circuit board design that allows board-to-board press fitting without using electromechanical components or solder connections. The sensor assembly is placed in a thin, semi-flexible tube (inner diameter 6.35 mm) that is filled with an epoxy compound. The resulting sensor probe is connected to an AA-battery-powered data logger with wireless connectivity. We characterize the system’s electromechanical properties and investigate the accuracy of deformation measurements. Our experiments, performed with probes up to 1.8 m long, demonstrate long-term connector stability, as well as probe mechanical flexibility. Furthermore, our accuracy analysis indicates that deformation measurements can be performed with a 0.390 mm resolution and a 95% confidence interval of ±0.73 mm per meter of probe length. This research shows the suitability of low-cost accelerometer arrays for distributed soil stability monitoring. In comparison with emerging low-cost measurements of surface displacement, our approach provides depth-resolved deformation, which can inform about shallow sliding surfaces.

deformation monitoring↗

DOE OSTI2025

Frequency-domain modeling of floating wind arrays with shared mooring lines

A frequency-domain model for floating wind turbine dynamics has been extended to model floating wind farms with couplings from shared mooring systems. The model, called RAFT, could previously calculate the mean offsets and wave-induced response spectra for single floating wind turbines. Now, the model supports multiple floating wind turbines, each with their own properties and responses, along with mooring lines that run directly between floating wind turbines in the array, meaning that shared mooring lines or fully suspended dynamic power cables can be included. This capability is achieved by setting up an array-level solution of the system mean offsets and assembling the full system matrices for solving the dynamic response. The quasi-static mooring model MoorPy is used to linearize the mooring system properties. To compute the floating wind turbine relative motions, phase offsets are applied to each turbine's response as a function of wave frequency based on the wavelength and relative positions in the array. These differential motions are then applied to mooring system tension Jacobians to compute the tension loads in the shared mooring lines. Overall, the capability provides a frequency-domain analog to the modeling capabilities of the floating support structure in FAST.Farm. Mean offsets and power spectral density plots of responses are compared between RAFT and FAST.Farm to verify the implementation. The results indicate good agreement within the expectations of a frequency-domain modeling approach and suggest correct implementation of the shared mooring aspects. Additionally, a unique comb-like frequency response in the shared mooring line tensions has been observed. This phenomenon has a clear physical basis and may be an important design consideration for future shared mooring systems.

17 WIND ENERGY↗

DOE OSTI2020

Synergy of Ion Doping and Spiral Array Architecture on Ti 2 Nb 10 O 29 : A New Way to Achieve High-Power Electrodes

Ameliorating electronic/ionic transport and structural stability of electrode materials is important to the development of power-intensive lithium ion batteries. Despite its great potential as a high-power anode, titanium niobium oxide (Ti 2 Nb 10 O 29 , TNO) still underperforms due to its unsatisfactory electronic/ionic conductivity. In this work, a powerful synergistic strategy by combining ion doping and spiral array architecture to boost high-rate performance of TNO is reported. Cr 3+ doped TNO nanoparticles (Cr-TNO) of 5-10 nm intimately grow on a conductive vertical graphene@TiC-C (VGTC) skeleton, forming novel Cr-TNO@VGTC spiral arrays. The unique spiral growth of TNO is achieved due to the confinement effect of VGTC skeleton. Meanwhile, a more open TNO crystal structure with faster ion transfer paths and enhanced structural stability is realized by Cr 3+ doping, demonstrated via density functional theory calculation and in situ synchrotron X-ray diffraction technique. Benefiting from the superior conductive network, enhanced intrinsic electronic/ionic conductivity of Cr-TNO and reinforced structural stability, the Cr-TNO@VTC arrays show prominent high-power performance with a large capacity of 220 mAh g -1 at 40 C (power density of ≈11 kW kg -1 ) and superior durability (91% retention after 500 cycles). This work provides a new path for the construction of widespread high-power electrodes for fast energy storage.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Fully‐Printed Ion Sensor Arrays for Measuring Agricultural Nitrogen and Potassium Concentrations Using Nernstian and AI Models

Abstract The chemical composition of growing media is a key factor for plant growth, impacting agricultural yield and sustainability. However, there is a lack of affordable chemical sensors for ubiquitous nutrient ion monitoring in agricultural applications. This work investigates using fully printed ion‐sensor arrays to measure the concentrations of nitrate, ammonium, and potassium in mixed‐electrolyte media. Ion sensor arrays composed of nitrate, ammonium, and potassium ion‐selective electrodes and a printed silver‐silver chloride (Ag/AgCl) reference electrode are fabricated and characterized in aqueous solutions in a range of concentrations that encompass what is typical for agricultural growing media (0.01 m m –1 m ). The sensors are also tested in mixed‐electrolyte solutions of NaNO 3 , NH 4 Cl, and KCl of varying concentrations, and the recorded potentials are input into Nernstian and artificial neural network models to compare the prediction accuracy of the models against ground truth. The artificial neural network models demonstrated higher accuracy over the Nernstian model, and the model using only ion‐sensor inputs is 7.5% more accurate than the Nernstian model under the same conditions. By enabling more precise and efficient fertilizer application, these sensor arrays coupled to computational models can help increase crop yields, optimize resource use, and reduce environmental impact.

Goodrich, Payton [University of California Berkele↗