SEARCH · Engineering Papers
Results for “pixel”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Keck-PAD Fast-Framing Hybrid X-ray Pixel Array Detector
Explore the source record for details and available documents.
Wide dynamic range x-ray Mixed-Mode Pixel Array Detector
Explore the source record for details and available documents.
Radiation Hard Pixel Tracking Sensor for High Luminosity Colliders (Final Scientific/Technical Report)
Explore the source record for details and available documents.
Wide Dynamic Range X-ray Mixed-Mode Pixel Array Detector
Explore the source record for details and available documents.
BNL - Alphacore Silicon Carbide Monolithic Active Pixel Sensors (BASiC MAPS)
Explore the source record for details and available documents.
Evaluation of a Variable-Aperture Full-Ring SPECT System using Large-Area Pixelated CZT Modules: A Simulation Study for Brain SPECT Applications
Single photon emission computed tomography (SPECT) scanner using cadmium zinc telluride (CZT) offers improved imaging capability over conventional NaI (Tl)-based SPECT scanner. We aim to demonstrate a full-ring SPECT system design with eight large-area CZT detectors that can be used for a broad spectrum of SPECT radiopharmaceuticals and provides higher sensitivity and better spatial resolution than those of conventional NaI (Tl)-based gamma cameras. A newly-designed full-ring SPECT system is composed of 8 large-area CZT cameras (128 mm × 179.2 mm effective area) that can be independently swiveled around their own axes of rotation independently and can have radial motion for varying aperture sizes that can be adapted to different sizes of imaging volume. Extended projection data were generated by conjoining projections of two adjacent detectors to overcome the limited field-of-view (FOV) by each CZT camera. Using Monte Carlo simulations, we evaluated this new system design with digital phantoms including a Derenzo hot-rod phantom and a Zubal brain phantom. Comparison of performance metrics such as spatial resolution, sensitivity, contrast-to-noise ratio (CNR), and contrast-recovery ratio were made between our design and a conventional SPECT scanner. The proposed scanner could result in up to about 3 times faster in acquisition time over conventional scan time at same acquisition time per step. The spatial resolution of our proposed scanner was similar or better to that of the conventional scanner, and there was significant performance improvement over the conventional scanner particularly in sensitivity (approximately 4 times). Overall, we successfully reconstructed the phantom image for both 99 mTc-based perfusion and 123 I-based dopamine transporter (DaT) brain studies simulated for our new design. In particular, the striatal/background contrast-recovery ratio in 3-to-1 reference ratio was over the 0.8 for the 123 I-based DaT study. In conclusion, we demonstrated the potential of our new full-ring CZT SPECT design, showing improved performance metrics such as improved system sensitivity and CNR while maintaining other important imaging parameters such as spatial resolution.
Crafting pixels in wood: understanding the interplay of technologies and visual perception in wooden photo engraving
This paper delves into the realm of laser engraving of photographs on wooden surfaces and explores the diferences between mathematical and human perception. A comprehensive quality study was conducted to explore the results achieved by 27 diferent realizations. The evaluation process involves both objective analyses and subjective assessments from hundreds of ratings of 60 evaluators, with the aim of unravelling the intricate interplay between technology and visual perception. The study also poses the intriguing question of whether the image most accurately transferred onto a wooden surface is also the most favourably perceived by potential customers and what are their preferences for laser engraved products.
Development of a Small-Pixel Ir-TES for Optical Applications
We designed and fabricated a photon-number-resolving detector based on an iridium (Ir) transition-edge sensors (TES) with small timing jitter time for coherent optical communication. The current–voltage relationship of the small Ir-TES, with an effective area of 7 μm × 7 μm, was measured, and its electrothermal feedback operation was confirmed. This device had a transition temperature of 280 mK, which is higher than that of bulk Ir, because of the wide contact area.
MAPPRAISER: A massively parallel map-making framework for multi-kilo pixel CMB experiments
Forthcoming cosmic microwave background (CMB) polarized anisotropy experiments have the potential to revolutionize our understanding of the Universe and fundamental physics. The sought-after, tale-telling signatures will be however distributed over voluminous data sets which these experiments will collect. These data sets will need to be efficiently processed and unwanted contributions due to astrophysical, environmental, and instrumental effects characterized and efficiently mitigated in order to uncover the signatures. This poses a significant challenge to data analysis methods, techniques, and software tools which will not only have to be able to cope with huge volumes of data but to do so with unprecedented precision driven by the demanding science goals posed for the new experiments. A keystone of efficient CMB data analysis is solvers of very large linear systems of equations. Such systems appear in very diverse contexts throughout CMB data analysis pipelines, however they typically display similar algebraic structures and can therefore be solved using similar numerical techniques. Linear systems arising in the so-called map-making problem are one of the most prominent and common ones. In this work we present a massively parallel, flexible and extensible framework, comprised of a numerical library, MIDAPACK, and a high level code, MAPPRAISER, which provide tools for solving efficiently such systems. Here, the framework implements iterative solvers based on conjugate gradient techniques: enlarged and preconditioned using different preconditioners. We demonstrate the framework on simulated examples reflecting basic characteristics of the forthcoming data sets issued by ground-based and satellite-borne instruments, executing it on as many as 16,384 compute cores. The software is developed as an open source project freely available to the community at: https://github.com/B3Dcmb/midapack.
An extrapolation method to remove spurious stress concentration in micromechanical analyses of composites using pixel-based meshes
It is easier to generate a finite element mesh of complicated geometries with voxel-based meshes compared to conformal meshes. However, the local stresses in voxel-based meshes are higher owing to artificial stress concentration caused due to jagged lines that approximate a curve. Here, we propose a method that accounts for this anomaly which would lead to accurate prediction of maximum von Mises stress in voxel-based meshes. The method is based on the variation of reciprocal of stresses and associated numerical gradient. The prediction of the proposed method is compared against the results of a conformal mesh by considering four two-dimensional example problems. The accuracy of the proposed method is verified using different mesh densities, material properties, and integration schemes. The proposed method was also implemented on a conformal mesh to verify that it filters out just the spurious stress concentration and not the realistic stress concentration.
Sequence2Self: Self-supervised image sequence denoising of pixel-level spray breakup morphology
Optical imaging of fast and transient phenomena such as the turbulent breakup of liquid sprays exhibit low signal-to-noise ratios due to the limited illumination intensity relative to the short exposure time. Image denoising is required to facilitate physical studies over these data but is challenging due to the absence of clean ground-truths and the stringency of the denoising task (e.g., strong and complex noise, limited resolution, preserving physical fidelity), preventing supervised and existing un-/self-supervised deep learning methods. To this end, Sequence2Self (Seq2S) is proposed, an extension of Self2Self (S2S) to image sequences that leverages both the signal’s spatial and temporal correlation. Seq2S is demonstrated on time-resolved x-ray phase contrast imaging of liquid jet fuel sprays in a gas turbine combustor, which possesses all of challenges detailed above. Experiments are conducted across four fuels with different breakup morphology using various state-of-the-art methods. Overall, many of the methods failed and Seq2S was most successful: (1) Accurate spray structures were reconstructed with consistent evolution across frames void of artifacts. (2) The performance was robust, invariant to the hyperparameter choice. (3) Computational time is short and can be made eligible for real-time denoising. In particular, the images denoised by Seq2S showed spray droplet diameter distributions with near-zero Kullback–Leibler divergence (0.01 ± 0.01) to a cleaner reference, whereas the second best method yielded 0.06 ± 0.03. In conclusion, this suggests that Seq2S can be reliably used prior to subsequent quantitative spray analyses as it retains (if not, improves) the statistical physical properties of the data.
Federated learning-based semantic segmentation for pixel-wise defect detection in additive manufacturing
Not Available
Data encoding efficiency in pixel detector readout with charge information
Not Available
CHICO2, a two-dimensional pixelated parallel-plate avalanche counter
CHICO 2 (Compact Heavy Ion COunter), is a large solid-angle, charged-particle detector array developed to provide both θ and Φ angle resolutions matching those of GRETINA (Gamma-Ray Energy Tracking In-beam Nuclear Array). CHICO 2 was successfully tested at the Argonne National Laboratory where it was fielded as an auxiliary detector with GRETINA for γ-ray spectroscopic studies of nuclei using a 252 Cf spontaneous fission source, stable beams, and radioactive beams from CARIBU. In field tests of the 72,76Ge beams on a 0.5 mg/cm 2 208Pb target at the sub-barrier energy, CHICO 2 provided charged-particle angle resolutions (FWHM) of 1.55° in θ and 2.47° in Φ. This achieves the design goal for both coordinates assuming a beam-spot size (>3 mm) and the target thickness (>0.5 mg/cm 2 ). The combined angular resolution of GRETINA/CHICO 2 resulted in a Doppler-shift corrected energy resolution of 0.60% for 1 MeV coincident de-excitation γ-rays. This is nearly a factor of two improvements in resolution and sensitivity compared to Gammasphere/CHICO. Kinematically-coincident detection of scattered ions by CHICO 2 still maintains the mass resolution (ΔM/M) of ~5% that enhanced isolation of scattered weak beams of interest from scattered contaminant beams.