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At least 271 records · Page 15

Design and performance of a modularized NaI/Tl/ detector /The Crystal Ball prototype/

A prototype NaI(Tl) detector (the Cluster of 54) of spherical geometry subtending a solid angle of 7.5% of 4pi at its center, has recently been assembled and tested. This detector consists of 54 close-packed but optically isolated NaI(Tl) modules and the associated electronic circuitry. The Cluster of 54 is the predecessor of an almost complete spherical detector, the Crystal Ball, which will cover 94% of 4pi. The latter detector is now under construction and is especially designed for the study of gamma-rays produced in electron-positron collisions at colliding beam facilities. This article outlines the mechanical, optical, and electronic assembly of the prototype system.

Chan, Y.↗

Interpretation of Space Shuttle telemetry

This paper describes the Payload Deployment and Retrieval System (PDRS) Failure Analysis and Diagnosis problem, our planned use of an expert system employing the C Language Integrated Production System (CLIPS) language to solve it, and our progress to date. In addition, it will address the importance of the overall design within the context of automation in the RTDS architecture, the methodology used, and the validation approach taken. The Decision Support System will evolve as a modularized rule-based system programmed in the CLIPS expert system language. Each of five modules represents a subsystem of the RMS and includes the positioning and retention hardware (MPM/MRL), the Display & Control panel (D8C), the Arm Based Electronics (ABE), the End Effector (EE), and the Orbiter to RMS data interface unit (MCIU). The MPM/MRL subsystem was chosen as the target of a prototype development and its knowledge base is completed. Testing and validation of the software is conducted by experienced mission controllers. The initial design stages for the D&C panel module are beginning.

Culp, Donald R.↗

Firefighters' Radios

Public Technology Inc. asked for NASA assistance to devise the original firefighter's radio. Good short-range radio communications are essential during a fire to coordinate hose lines, rescue victims, and otherwise increase efficiency. Useful firefighting tool is lower cost, more rugged short range two-way radio. Inductorless electronic circuit replaced inductances and coils in radio circuits with combination of transistors and other low-cost components. Substitution promises reduced circuit size and cost. Enhanced electrical performance made radio more durable and improved maintainability by incorporating modular construction.

Source record↗

Medical Data Architecture Capabilities and Design

Mission constraints will challenge the delivery of medical care on a long-term, deep space explorationmission. This type of mission will be restricted in the availability of medical knowledge, skills, procedures and resourcesto prevent, diagnose, and treat in-flight medical events. Challenges to providing medical care are anticipated, includingresource and resupply constraints, delayed communications and no ability for medical evacuation. The Medical DataArchitecture (MDA) project will enable medical care capability in this constrained environment.The first version of thesystem, called Test Bed 1, includes capabilities for automated data collection, data storage and data retrieval to provideinformation to the Crew Medical Officer (CMO). Test Bed 1 seeks to establish a data architecture foundation and developa scalable data management system through modular design and standardized interfaces. In addition, it will demonstrateto stakeholders the potential for an improved, automated, flow of data to and from the medical system over the currentmethods employed on the International Space Station (ISS). It integrates a set of external devices, software andprocesses, and a Subjective, Objective, Assessment, and Plan (SOAP) note commonly used by clinicians. Medical datalike electrocardiogram plots, heart rate, skin temperature, respiration rate, medications taken, and more are collectedfrom devices and stored in the Electronic Medical Records (EMR) system, and reported to crew and clinician. Devicesintegrated include the Astroskin biosensor vest and IMED CARDIAX electrocardiogram (ECG) device with INEED MDECG Glove, and the NASA-developed Medical Dose Tracker application.The system is designed to be operated as astandalone system, and can be deployed in a variety of environments, from a laptop to a data center. The system isprimarily composed of open-source software tools, and is designed to be modular, so new capabilities can be added. Thesoftware components and integration methods will be discussed.

Exploration medical system↗

Approaching Angstrom-Scale Resolution in Lithography Using Low-Molecular-Mass Resists (<500 Da)

Resists that enable high-throughput and high-resolution patterning are essential in driving the semiconductor technology forward. The ultimate patterning performance of a resist in lithography is limited because of the trade-off between resolution, line-width roughness, and sensitivity; improving one or two of these parameters typically leads to a loss in the third. As the patterned feature sizes approach angstrom scale, the trade-off between these three metrics becomes increasingly hard to resolve and calls for a fundamental rethinking of the resist chemistry. Low-molecular-mass monodispersed metal-containing resists of high atom economy can provide not only very high resolution but also very low line-width roughness without sacrificing sensitivity. Here we describe a modular metal-containing resist platform (molecular mass <500 Da) where a molecular resist consists of just two components: a metal and a radical initiator bonded to it. This simple system not only is amenable to high-resolution electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL) but also unites them mechanistically, giving a consolidated perspective of molecular and chemical processes happening during exposure. Irradiation of the resist leads to the production of secondary electrons that generate radicals in the initiator bonded to metal. This brings about an intramolecular rearrangement and causes solubility switch in the exposed resist. We demonstrate record 1.9–2.0 nm isolated patterns and 7 nm half-pitch dense line-space features over a large area using EBL. With EUVL, 12 nm half-pitch line-space features are shown at a dose of 68 mJ/cm 2 . In both of these patterning techniques, the line-width roughness was found to be ≤2 nm, a record low value for any resist platform, also leading to a low-performance trade-off metric, Z factor, of 0.6 × 10 –8 mJ·nm 3 . With the ultimate resolution limited by instrumental factors, potential patterning at the level of a unit cell can be envisaged, making low-molecular-mass resists best poised for angstrom-scale lithography.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Extended performance solar electric propulsion thrust system design

A thrust system design has been established for an extended performance technology, 6.4 kW, 4800 sec specific impulse ion thruster. The configuration is comprised of ten thrusters configured with a power management and control subsystem in a modular thrust system design. The system design approach is an adaptation of that previously established for the baseline technology 2.7 kW, 3000 sec specific impulse ion thruster. The power management and control subsystem design includes a combination of individual electronics for each thruster and a set of electronics with redundancy that are common to all thrusters. The thermal dissipation from all electronics is removed with a common heat pipe/radiator assembly.

Cake, J. E.↗

Programmable Cadence Timer

Electronic metronome paces users through wide range of exercise routines. Conceptual programmable cadence timer provides rhythmic aural and visual cues. Timer automatically changes cadence according to program entered by the user. It also functions as clock, stopwatch, or alarm. Modular pacer operated as single unit or as two units. With audiovisual module moved away from base module, user concentrates on exercise cues without distraction from information appearing on the liquid-crystal display. Variety of uses in rehabilitative medicine, experimental medicine, sports, and gymnastics. Used in intermittent positive-pressure breathing treatment, in which patient must rhythmically inhale and retain medication delivered under positive pressure; and in incentive spirometer treatment, in which patient must inhale maximally at regular intervals.

Hall, William A.↗

Low-Complexity, Digital Encoder/Modulator Developed for High-Data-Rate Satellite B-ISDN Applications

The Space Electronics Division at the NASA Lewis Research Center is developing advanced electronic technologies for the space communications and remote sensing systems of tomorrow. As part of the continuing effort to advance the state-of-the-art in satellite communications and remote sensing systems, Lewis developed a low-cost, modular, programmable, and reconfigurable all-digital encoder-modulator (DEM) for medium- to high-data-rate radiofrequency communication links. The DEM is particularly well suited to high-data-rate downlinks to ground terminals or direct data downlinks from near-Earth science platforms. It can support data rates up to 250 megabits per second (Mbps) and several modulation schemes, including the traditional binary phase-shift keying (BPSK) and quadrature phase-shift keying (QPSK) modes, as well as higher order schemes such as 8 phase-shift keying (8PSK) and 16 quadrature amplitude modulation (16QAM). The DEM architecture also can precompensate for channel disturbances and alleviate amplitude degradations caused by nonlinear transponder characteristics.

Source record↗

A modular solid state detector for measuring high energy heavy ion fragmentation near the beam axis

A multi-element solid state detector has been designed to measure fluences of fragments produced near the beam axis by high energy heavy ion beams in thick targets. The detector is compact and modular, so as to be readily reconfigured according to the range of fragment charges and energies to be measured. Preamplifier gain settings and detector calibrations are adjustable remotely under computer control. We describe the central detector, its associated detectors and electronics, triggering scheme, data acquisition and particle identification techniques, illustrated by data taken with 600 MeV/u 56Fe beams and thick polyethylene targets at the LBL Bevalac. The applications of this work to space radiation protection are discussed.

NASA Center HQS↗

Reduction of the molecular hamiltonian matrix using quantum community detection

Abstract Quantum chemistry is interested in calculating ground and excited states of molecular systems by solving the electronic Schrödinger equation. The exact numerical solution of this equation, frequently represented as an eigenvalue problem, remains unfeasible for most molecules and requires approximate methods. In this paper we introduce the use of Quantum Community Detection performed using the D-Wave quantum annealer to reduce the molecular Hamiltonian matrix in Slater determinant basis without chemical knowledge. Given a molecule represented by a matrix of Slater determinants, the connectivity between Slater determinants (as off-diagonal elements) is viewed as a graph adjacency matrix for determining multiple communities based on modularity maximization. A gauge metric based on perturbation theory is used to determine the lowest energy cluster. This cluster or sub-matrix of Slater determinants is used to calculate approximate ground state and excited state energies within chemical accuracy. The details of this method are described along with demonstrating its performance across multiple molecules of interest and bond dissociation cases. These examples provide proof-of-principle results for approximate solution of the electronic structure problem using quantum computing. This approach is general and shows potential to reduce the computational complexity of post-Hartree–Fock methods as future advances in quantum hardware become available.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

SOFIP: A Short Orbital Flux Integration Program

A computer code was developed to evaluate the space radiation environment encountered by geocentric satellites. The Short Orbital Flux Integration Program (SOFIP) is a compact routine of modular compositions, designed mostly with structured programming techniques in order to provide core and time economy and ease of use. The program in its simplest form produces for a given input trajectory a composite integral orbital spectrum of either protons or electrons. Additional features are available separately or in combination with the inclusion of the corresponding (optional) modules. The code is described in detail, and the function and usage of the various modules are explained. A program listing and sample outputs are attached.

Stassinopoulos, E. G.↗

Medical Data Architecture Project Capabilities and Design

Mission constraints will challenge the delivery of medical care on a long-term, deep space exploration mission. This type of mission will be restricted in the availability of medical knowledge, skills, procedures and resources to prevent, diagnose, and treat in-flight medical events. Challenges to providing medical care are anticipated, including resource and resupply constraints, delayed communications and no ability for medical evacuation. The Medical Data Architecture (MDA) project will enable medical care capability in this constrained environment. The first version of the system, called "Test Bed 1," includes capabilities for automated data collection, data storage and data retrieval to provide information to the Crew Medical Officer (CMO). Test Bed 1 seeks to establish a data architecture foundation and develop a scalable data management system through modular design and standardized interfaces. In addition, it will demonstrate to stakeholders the potential for an improved, automated, flow of data to and from the medical system over the current methods employed on the International Space Station (ISS). It integrates a set of external devices, software and processes, and a Subjective, Objective, Assessment, and Plan (SOAP) note commonly used by clinicians. Medical data like electrocardiogram plots, heart rate, skin temperature, respiration rate, medications taken, and more are collected from devices and stored in the Electronic Medical Records (EMR) system, and reported to crew and clinician. Devices integrated include the Astroskin biosensor vest and IMED CARDIAX electrocardiogram (ECG) device with INEED MD ECG Glove, and the NASA-developed Medical Dose Tracker application. The system is designed to be operated as a standalone system, and can be deployed in a variety of environments, from a laptop to a data center. The system is primarily composed of open-source software tools, and is designed to be modular, so new capabilities can be added. The software components and integration methods will be discussed.

Data architecture↗

Spectral Addressability in a Modular Two Qubit System

The combination of structural precision and reproducibility of synthetic chemistry is perfectly suited for the creation of chemical qubits, the core units of a quantum information science (QIS) system. By exploiting the atomistic control inherent to synthetic chemistry, we address a fundamental question of how the spin–spin distance between two qubits impacts electronic spin coherence. To achieve this goal, in this study we designed a series of molecules featuring two spectrally distinct qubits, an early transition metal, Ti 3+ , and a late transition metal, Cu 2+ with increasing separation between the two metals. The spectral separation between the two metals enables us to probe each metal individually in the bimetallic species and compare it with monometallic control samples. Coherence times found to be governed by the distance to nuclear spins on the other qubit’s ligand framework. This finding offers guidance for the design of spectrally addressable molecular qubits.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Lunar deep drill apparatus

Proposed as a baseline configuration, this rotary drill apparatus is designed to produce 100-mm diameter holes in the lunar surface at depths up to 50 meters. The drill is intended to acquire samples for scientific analysis, mineral resource location, calibration of electronic exploration devices, and foundation analysis at construction sites. It is also intended to prepare holes for emplacement of scientific instruments, the setting of structural anchors, and explosive methods in excavation and mining activities. Defined as a deep drill because of the modular drill string, it incorporates an automatic rod changer. The apparatus is teleoperated from a remote location, such as earth, utilizing supervisory control techniques. It is thus suitable for unmanned and man-tended operation. Proven terrestrial drilling technology is used to the extent it is compatible with the lunar environment. Augers and drive tubes form holes in the regolith and may be used to acquire loose samples. An inertial cutting removal system operates intermittently while rock core drilling is in progress. The apparatus is carried to the work site by a three-legged mobile platform which also provides a 2-meter feed along the hole centerline, an off-hole movement of approximately .5 meters, an angular alignment of up to 20 deg. from gravity vertical, and other dexterity required in handling rods and samples. The technology can also be applied using other carriers which incorporate similar motion capabilities. The apparatus also includes storage racks for augers, rods, and ancillary devices such as the foot-plate that holds the down-hole tooling during rod changing operations.

Source record↗

Development of High Energy Density Diaminocyclopropenium‐Phenothiazine Hybrid Catholytes for Non‐Aqueous Redox Flow Batteries

Abstract This report describes the design of diaminocyclopropenium‐phenothiazine hybrid catholytes for non‐aqueous redox flow batteries. The molecules are synthesized in a rapid and modular fashion by appending a diaminocyclopropenium (DAC) substituent to the nitrogen of the phenothiazine. Combining a versatile C‐N coupling protocol (which provides access to diverse derivatives) with computation and structure‐property analysis enabled the identification of a catholyte that displays stable two‐electron cycling at potentials of 0.64 and 1.00 V vs. Fc/Fc + as well as high solubility in all oxidation states (≥0.45 M in TBAPF 6 /MeCN). This catholyte was deployed in a high energy density two‐electron RFB, exhibiting >90 % capacity retention over 266 hours of flow cell cycling at >0.5 M electron concentration.

Yan, Yichao↗

Assessment of the Impact of Realistic Sensor Physics and the Integration of Ex-Core Sensors on Reactor Power Synthesis

In the work documented in this report, a weighting function–based core power synthesis method was applied to multiple Monte Carlo N-Particle (MCNP) reactor models, which are informed based on simulated self-powered neutron detector (SPND) responses. The weighting function method used has been coined the point-based iterative (PBI) method. The goal of this application is to assess the impact of considering realistic sensor physics in the generation of the simulated SPND outputs as well as to consider how the synthesis is impacted based on the inclusion of ex-core detectors in the model. The NuScale small modular reactor (SMR) and Westinghouse AP1000 pressurized water reactor (PWR) are the models that served as the testbeds for the assessment of realistic sensor physics; this was achieved by using Geant4 SPND models in comparison with analytical models, such that the effect of electron transport in realistic SPND geometries in the Geant4 model can be understood in terms of synthesis error and convergence time. The comparison was considered for fuel burnup–induced perturbations, for a range of sensor string densities and synthesized power distribution axial fidelities. The Texas A&M Testing, Research, Isotopes, General Atomics Reactor (TAMU TRIGA) reactor MCNP model was used to assess the impact of ex-core sensors; this was done by performing synthesis with and without the ex-core detectors and by quantifying the synthesis error and number of iterations associated with Gaussian-type perturbations in many locations in the core. The TAMU TRIGA model was particularly pertinent for this study because of the interest in future experimental tests with SPNDs in this reactor, as well as the ease of modifying the MCNP model to include ex-core detectors with heterogeneously described response functions. Results from the comparison between the Geant4 and analytical SPND models indicate that similar average and maximum synthesis errors were obtained for burnup-induced perturbations in both the NuScale SMR and the AP1000. This was true for a range of sensor string densities and axial fidelities. However, there were marked differences between both the Geant4 and analytically informed models in terms of the iterations required to converge on the synthesized power distribution. Namely, the Geant4-informed models tended to lead to fewer iterations, except for a few sensor–core configurations that had particularly numerous iterations. Results from the ex-core sensor assessment with the TAMU TRIGA model indicate that the inclusion of ex-core sensors drastically reduces the synthesis error of Gaussian-type perturbations close to the edge of the core, and it slightly reduces synthesis errors for perturbations closer to the center of the core. This was achieved with a minimal increase in computational cost—that is, the number of iterations required for convergence. The errors were identified to be in the same location as the perturbation in the core, indicating that the methodology remains robust for unperturbed regions of the core. A secondary result from this study with the TAMU TRIGA was yielded by analysis of the neutron flux levels in the in-core and ex-core sensor locations of the core; these flux levels indicate that SPNDs could be used as both in-core and ex-core sensors, so long as the emitter material is sensitive to thermal neutrons. The results from these studies provide a quantitative understanding of the importance of considering realistic sensor physics and including ex-core sensors to perform accurate and timely power distribution synthesis of a reactor core.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Master Clock and Time-Signal-Distribution System

A timing system comprising an electronic master clock and a subsystem for distributing time signals from the master clock to end users is undergoing development to satisfy anticipated timing requirements of NASA s Deep Space Network (DSN) for the next 20 to 30 years. This system has a modular, flexible, expandable architecture that is easier to operate and maintain than the present frequency and timing subsystem (FTS).

Tjoelker, Robert↗