gebhart/patrepeval huggingface dataset:
Image Coding by Vector Quantization of M-Hadamard Transform Coefficients (1986)

Vector quantization (VQ) has been recognized to be a promising technique for low data rate image coding as a result of the development of effective codebook design algorithms and advances in digital processing. VQ in the transform domain of the so-called M-Hadamard Transform is proposed to avoid typical quantization noise of VQ, namely block contouring and the 'staircase' reconstruction of edges in the decoded image which is highly noticeable by the human observer. This contribution reports the application of this principle in an intra/interframe coder concept for encoding the luminance component of TV-sequences with fixed length codewords of 1 bit/sample. In particular a vector predictive quantizer is used for encoding the inter-frame block differences of the image sequence. This is supported by a memoryless VQ to improve prediction in blocks with strong movement. The codebook of the VQ is based on the well-known LGB-algorithm.
Characterization of one-dimensional capacitive micromachined ultrasonic immersion transducer arrays (2001)

In this paper, we report on the characterization of 1-D arrays of capacitive micromachined ultrasonic transducers (cMUT). A 275- x 5600-micron 1-D CMUT array element is experimentally characterized, and the results are found to be in agreement with theoretical predictions. As a receiver, the transducer has a 0.28-fm/square root of Hz displacement sensitivity, and, as a transmitter, it produces 5 kPa/V of output pressure at the transducer surface at 3 MHz with a DC bias of 35 V. The transducer has more than 100% fractional bandwidth around 3 MHz, which makes it suitable for ultrasound imaging. The radiation pattern of isolated single elements, as well as those of array elements are measured, and two major sources of acoustical cross talk are identified. A weakly dispersive non-leaky interface wave (Stoneley wave) is observed to be propagating at the silicon substrate-fluid interface at a speed close to the speed of sound in the fluid. This wave causes internal reflections, spurious resonance, and radiation from the edges of the silicon substrate. The large lateral component of the particle velocity generated by the membranes at the edge of the cMUT array elements is found to be the source of this interface wave. Lowest order Lamb waves in the silicon substrate are also found to contribute to the cross talk between elements. These waves are excited at the edges of individual vibrating membranes, where they are anchored to the substrate, and result in a narrowing of the beam profile of the array elements. Several methods, such as trench isolation and wafer thinning, are proposed and implemented to modify the acoustical cross coupling between array elements.
High-performance and tunable stereo reconstruction (2016)

Traditional stereo algorithms have focused their efforts on reconstruction quality and have largely avoided prioritizing for run time performance. Robots, on the other hand, require quick maneuverability and effective computation to observe its immediate environment and perform tasks within it. In this work, we propose a high-performance and tunable stereo disparity estimation method, with a peak frame-rate of 120Hz (VGA resolution, on a single CPU-thread), that can potentially enable robots to quickly reconstruct their immediate surroundings and maneuver at high-speeds. Our key contribution is a disparity estimation algorithm that iteratively approximates the scene depth via a piece-wise planar mesh from stereo imagery, with a fast depth validation step for semi-dense reconstruction. The mesh is initially seeded with sparsely matched keypoints, and is recursively tessellated and refined as needed (via a resampling stage), to provide the desired stereo disparity accuracy. The inherent simplicity and speed of our approach, with the ability to tune it to a desired reconstruction quality and runtime performance makes it a compelling solution for applications in high-speed vehicles.
Space-time coding for impulse radio (2003)

Impulse radio (IR) ultrawide band systems have well documented advantages for low-power peer-to-peer and multiple access communications. Space-time (ST) coding on the other hand, has gained popularity as an effective means of boosting rates and performance. Existing IR transmitters rely on a single antenna, while ST coders have so far focused on digital linearly modulated transmissions. In this paper, we develop an orthogonal ST coding scheme for the analog nonlinearly (pulse-position) modulated multi-antenna IR system. We show that the resulting analog noncoherent detector is equivalent to an existing digital ST decoder possessing maximum likelihood optimality. Simulations testing peer-to-peer and multi-access IR scenarios confirm considerable increase in both bit-error-rate performance and number of users that can be accommodated, when wedding ST coding with IR.
Biomass-derived electrocatalytic composites for hydrogen evolution (2013)

The production of hydrogen from water electrolysis calls for an efficient non-precious-metal catalyst to make the process economically viable because of the high cost and the limited supply of the currently used platinum catalysts. Here we present such a catalyst made from earth-abundant molybdenum and common, humble soybeans (MoSoy). This catalyst, composed of a catalytic β-Mo2C phase and an acid-proof γ-Mo2N phase, drives the hydrogen evolution reaction (HER) with low overpotentials, and is highly durable in a corrosive acidic solution over a period exceeding 500 hours. When supported on graphene sheets, the MoSoy catalyst exhibits very fast charge transfer kinetics, and its performance rivals that of noble-metal catalysts such as Pt for hydrogen production. These findings prove that the soybean (as well as other high-protein biomass) is a useful material for the generation of catalysts incorporating an abundant transition metal, thereby challenging the exclusivity of platinum catalysts in the hydrogen economy.
CASA-NLU: Context-Aware Self-Attentive Natural Language Understanding for Task-Oriented Chatbots (2019)

Natural Language Understanding (NLU) is a core component of dialog systems. It typically involves two tasks - intent classification (IC) and slot labeling (SL), which are then followed by a dialogue management (DM) component. Such NLU systems cater to utterances in isolation, thus pushing the problem of context management to DM. However, contextual information is critical to the correct prediction of intents and slots in a conversation. Prior work on contextual NLU has been limited in terms of the types of contextual signals used and the understanding of their impact on the model. In this work, we propose a context-aware self-attentive NLU (CASA-NLU) model that uses multiple signals, such as previous intents, slots, dialog acts and utterances over a variable context window, in addition to the current user utterance. CASA-NLU outperforms a recurrent contextual NLU baseline on two conversational datasets, yielding a gain of up to 7% on the IC task for one of the datasets. Moreover, a non-contextual variant of CASA-NLU achieves state-of-the-art performance for IC task on standard public datasets - Snips and ATIS.
Modulation and efficiency characteristics of miniature microchip green laser sources based on PPMgOLN nonlinear material (2011)

We report on highly efficient diode-pumped solid-state (DPSS) green laser source based on a monolithic cavity microchip laser platform. The use of periodically poled MgO-doped Lithium Niobate (PPMgOLN) as the nonlinear frequency doubler together with gain material Nd<sup>3+</sup>:YVO<sub>4</sub> allows obtaining a significant increase in the overall efficiency of green microchip laser in comparison with other compact green laser source architectures with comparable output power. We discuss our progress in miniaturization and efficient operation across a wide range of temperatures and application-specific modulation conditions. In particular, we demonstrate 50mW-120mW average green output power (30% duty cycle) with wall-plug efficiency over 13%. Efficient laser operation with duty cycle ranging from 10% to 60% in a wide range of repetition rates is also demonstrated. The laser is designed to be a part of the miniature and efficient RGB light source for microdisplay-based (LCOS, DLP or similar) mobile projector devices. While these projection architectures typically require modulation rates from 60Hz to about 2000Hz depending on design, we extended modulation speed up to 2MHz that can be of interest for other applications. A very efficient and small microchip as well as alignment-free design allow us to package this laser source into the very small volume of only 0.23cm3 (bounding box). We present results of performance tests for this packaged laser and demonstrate that such a miniature package can support laser operation with average power output of over 250mW.
Coherent-scatter computed tomography applying a fan-beam geometry (2001)

Recently, fan-beam geometry based Coherent Scatter Computed Tomography (CSCT) was proposed. Coherently scattered X-rays are used in order to reconstruct the spatial distribution of the material dependent structure function, allowing for superior tissue discrimination. In the present paper, the proposed 'third generation' CT geometry and acquisition scenario is simulated, taking into account effects like quantum noise and spectral smearing. A modified iterative algebraic reconstruction algorithm is used for reconstructing the structure function distribution from a number of two-dimensional projections acquired at different viewing angles. The visibility of small objects is investigated for several dose values. In addition to simulation studies, first results of an experimental fan-beam CSCT set-up are shown and discussed. Experiment and simulations indicate the feasibility of CSCT. Future investigations will deepen our understanding of the possibilities and limitations of this new imaging modality.
Iterative-Interpolated DFT for Synchrophasor Estimation: A Single Algorithm for P- and M-Class Compliant PMUs (2017)

We present a single synchrophasor estimation (SE) algorithm that is simultaneously compliant with both P and M phasor measurement unit (PMU) performance classes. The method, called iterative-interpolated discrete Fourier transform (i-IpDFT), iteratively estimates and compensates the effects of the spectral interference produced by both a generic interfering tone, harmonic or interharmonic, and the negative image of the fundamental tone. We define the three-point i-IpDFT technique for cosine and Hanning window functions and we propose a procedure to select the i-IpDFT parameters. We assess the performance of the i-IpDFT with respect to all the operating conditions defined in the IEEE Std. C37.118 for P- and M-class PMUs. We demonstrate that the proposed SE method is simultaneously compliant with all the accuracy requirements of both PMU performance classes.
Motor current signature analysis for determining operational readiness of Motor-Operated Valves (MOVs) (1987)

Motor current signature analysis (MCSA) is a novel diagnostic process for condition monitoring of electric-motor-driven mechanical equipment (e.g., pumps, motor-operated valves, compressors, and processing machinery). The MCSA process identifies, characterizes, and trends over time the instantaneous load variations of mechanical equipment in order to diagnose changes in the condition of the equipment (e.g., due to degradation or service wear), which, if allowed to continue, may lead to failure. It monitors the instantaneous variations (noise content) in the electric current flowing through the power leads to the electric motor that drives the equipment. The motor itself thereby acts as a transducer, sensing both large and small, long-term and rapid, mechanical load variations and converting them to variations in the induced current generated in the motor windings. This motor current noise signature is detected, amplified, and further processed as needed to examine its time domain and frequency domain (spectral) characteristics. The operational principles of MCSA and the nonintrusive data collection apparatus and procedure used with MOVs will be described. Data collected from MOVs in both laboratory and in-plant environments will also be shown to illustrate the ability of MCSA to ''see'' the detailed inner workings of the valve and operator and thus to detect degraded performance at an incipient stage. (Set of 18 vugraphs)
DEFT: Progress on Direct Electronic Fourier Transforms of Two-Dimensional Images. (1974)

Abstract : This report covers research on Direct Electronic Fourier Transforms of Images (DEFT). Progress was made along both theoretical and experimental avenues. The theoretical effort enabled us to identify alternatives in creating fully electronic two-dimensional transform imaging through the use of acoustically controlled light valves. Other activities included development of an automatic focusing application, the study of sampling techniques as they apply to DEFT cameras, and the development of 'Acoustic Computers' to provide automatic compensation for the frequency-dependent characteristics of the devices. Experimental work focused on improved sensors achieved by improving several aspects of sample construction. An elastobirefringent light valve for one-dimensional reconstruction was also built and tested.
Mitosis in circulating tumor cells stratifies highly aggressive breast carcinomas (2016)

Our data suggest that (1) mitotic CTCs are relativity common in aggressive late-stage breast cancer, (2) mitotic CTCs may significantly correlate with shortened overall survival, and (3) larger and more defined patient cohort studies are clearly called for based on this initial pilot study.
Fully-integrated 1-dimensional RF coupled-oscillator network for phase-shifterless phased array systems (2010)

A fully-monolithic 3-element array of coupled voltage-controlled-oscillator (VCO) network was fabricated in a 0.18μm SiGe BiCMOS process for potential use in a Rx/Tx modules. A digitally controlled on-chip passive network was designed and used for controlling the coupling strength across the array VCO units. The operational bandwidth of this core network resides in the S-Band from 1.2GHz to 1.7GHz. The integrated VCO network can be injection-locked via an external RF source to achieve excellent phase noise performance. These characteristics make this coupled-VCO network a very attractive choice for possible use in phased-array radar applications. The chip's total power consumption is 30mW (12mA at 2.5V).
Large Format Quantum Well Infrared Photodetector Focal Plane Arrays for Astronomical Instrumentations (2000)

Quantum Well Infrared Photodetectors (QWIPs) afford greater flexibility than the usual extrinsically doped semiconductor IR detectors.
Angiography by Synchrotron Radiation (1987)

Because coronary disease represents the principal health problem in the Western, industrialized world, and because of the risks and costs associated with conventional methods of visualizing the coronary arteries, an effort has been underway at the Stanford Synchrotron Radiation Laboratory to develop a less invasive coronary imaging procedure based on iodine K-edge dichromography. A pair of line images, recorded within a few milliseconds of each other, is taken with two monochromatic X-ray beams whose energy closely brackets the K-edge of iodine, 33.17 keV. The logarithmic subtraction of the images produced by these beams results in an image which greatly enhances signals arising from attenuation by iodine and almost totally suppresses signals arising from attenuation by soft tissue and bone. The high sensitivity to iodine allows the visualization of arterial structures after an intravenous injection of contrast agent and its subsequent 20-30 fold dilution.
Synthetic aperture angular scatter imaging: system refinement (2005)

Angular scatter imaging has been proposed as a new source of image contrast in medical ultrasound and as a parameter for tissue characterization. We describe a new method that combines the translating apertures algorithm (TAA) with synthetic aperture methods to coherently obtain angular scatter information with high resolution in both space and scattering angle. This method, which we term synthetic aperture angular scatter (SAAS) imaging effectively applies the TAA to single array elements and then focuses the data synthetically to form high resolution images at precisely defined scattering angles. In this paper, we present experimental results implementing SAAS to form angular scatter images of a 5-wire depth of field phantom, a tissue mimicking 3-wire phantom, and in vivo human thyroid. We discuss the degree of uniformity necessary in element response for successful SAAS imaging. These experiments show new image information previously unavailable in conventional B-mode images and suggest that angular scatter imaging may have applications in the breast, thyroid, and peripheral vasculature.
Effect of a Cutback Squealer and Cavity Depth on Film-Cooling Effectiveness on a Gas Turbine Blade Tip (2008)

Film-cooling effectiveness from shaped holes on the near tip pressure side and cylindrical holes on the squealer cavity floor is investigated. The pressure side squealer rim wall is cut near the trailing edge to allow the accumulated coolant in the cavity to escape and cool the tip trailing edge. Effects of varying blowing ratios and squealer cavity depth are also examined on film-cooling effectiveness. The film-cooling effectiveness distributions are measured on the blade tip, near tip pressure side and the inner pressure side and suction side rim walls using pressure sensitive paint technique. The internal coolant-supply passages of the squealer tipped blade are modeled similar to those in the GE-E3 rotor blade with two separate serpentine loops supplying coolant to the film-cooling holes. Two rows of cylindrical film-cooling holes are arranged offset to the suction side profile and along the camber line on the tip. Another row of shaped film-cooling holes is arranged along the pressure side just below the tip. The average blowing ratio of the cooling gas is controlled to be 0.5, 1.0, 1.5, and 2.0. A five-bladed linear cascade in a blow down facility with a tip gap clearance of 1.5% is used to perform the experiments. The free-stream Reynolds number, based on the axial chord length and the exit velocity, was 1,480,000 and the inlet and exit Mach numbers were 0.23 and 0.65, respectively. A blowing ratio of 1.0 is found to give best results on the pressure side, whereas the tip surfaces forming the squealer cavity give best results for M=2. Results show high film-cooling effectiveness magnitudes near the trailing edge of the blade tip due to coolant accumulation from upstream holes in the tip cavity. A squealer depth with a recess of 2.1mm causes the average effectiveness magnitudes to decrease slightly as compared to a squealer depth of 4.2mm.
Saving energy with an optimized two-stage reverse osmosis system (2017)

We optimize the design and operation of two-stage reverse osmosis desalination systems and identify the operating conditions that will maximize energy savings.
Laser range scanning for image‐guided neurosurgery: Investigation of image‐to‐physical space registrations (2008)

In this article a comprehensive set of registration methods is utilized to provide image-to-physical space registration for image-guided neurosurgery in a clinical study. Central to all methods is the use of textured point clouds as provided by laser range scanning technology. The objective is to perform a systematic comparison of registration methods that include both extracranial (skin marker point-based registration (PBR), and face-based surface registration) and intracranial methods (feature PBR, cortical vessel-contour registration, a combined geometry/intensity surface registration method, and a constrained form of that method to improve robustness). The platform facilitates the selection of discrete soft-tissue landmarks that appear on the patient's intraoperative cortical surface and the preoperative gadolinium-enhanced magnetic resonance (MR) image volume, i.e., true corresponding novel targets. In an 11 patient study, data were taken to allow statistical comparison among registration methods within the context of registration error. The results indicate that intraoperative face-based surface registration is statistically equivalent to traditional skin marker registration. The four intracranial registration methods were investigated and the results demonstrated a target registration error of 1.6 +/- 0.5 mm, 1.7 +/- 0.5 mm, 3.9 +/- 3.4 mm, and 2.0 +/- 0.9 mm, for feature PBR, cortical vessel-contour registration, unconstrained geometric/intensity registration, and constrained geometric/intensity registration, respectively. When analyzing the results on a per case basis, the constrained geometric/intensity registration performed best, followed by feature PBR, and finally cortical vessel-contour registration. Interestingly, the best target registration errors are similar to targeting errors reported using bone-implanted markers within the context of rigid targets. The experience in this study as with others is that brain shift can compromise extracranial registration methods from the earliest stages. Based on the results reported here, organ-based approaches to registration would improve this, especially for shallow lesions.
Optimal control of laser beams for propagation through a turbulent medium (2002)

Concerning the problem of transmitting a laser beam from one telescope to another telescope through a turbulent medium, it is established that using an adaptive optical system on both telescopes to precompensate an outgoing laser beam based on the aberrations measured on the received laser beam leads to an iteration that maximizes the transmission (neglecting attenuation losses) of laser power between the telescopes. Simulation results are presented demonstrating the effectiveness of this technique when the telescopes are equipped with either phase-only or full-wave compensation systems. Simulation results are shown that indicate that for a uniform distribution of the strength of turbulence, 95% transmission of laser power is attained when both telescopes can achieve full-wave compensation provided that the aperture diameter D of the two telescopes is greater than twice the Fresnel length square root of lambdaL, where A is the wavelength of propagation and L is the distance between the two telescopes.