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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Electromagnetic field strength prediction in an urban environment: A useful tool for the planning of LMSS

A model for the prediction of the electromagnetic field strength in an urban environment is presented. The ray model, that is based on the Uniform Theory of Diffraction (UTD), includes effects of the non-perfect conductivity of the obstacles and their surface roughness. The urban environment is transformed into a list of standardized obstacles that have various shapes and material properties. The model is capable of accurately predicting the field strength in the urban environment by calculating different types of wave contributions such as reflected, edge and corner diffracted waves, and combinations thereof. Also, antenna weight functions are introduced to simulate the spatial filtering by the mobile antenna. Communication channel parameters such as signal fading, time delay profiles, Doppler shifts and delay-Doppler spectra can be derived from the ray-tracing procedure using post-processing routines. The model has been tested against results from scaled measurements at 50 GHz and proves to be accurate.

Vandooren, G. A. J.↗
NASA NTRS1996

Cross-Cultural Barriers to Effective Communication in Aviation

Communication is essential to safe flight, as evidenced by several accidents in which crew communicates was found to have contributed to the accidents. This chapter documents the essential role of explicit efficient communication to flight safety with a global context. It addresses communication between flight crews and air traffic controllers in regions a the world where pilots and controllers speak different native languages, as well as cases in which crew members within the flight deck represent different native languages and cultures. It also addresses problems associated with "exporting" crew resource management training programs to parts of the world which values and norms differ from those of the United States, where these programs were initially developed. This chapter is organized around several central questions: (1) What are various kinds of communication failures and what are their consequences; (2) What are the causes of communication failure; (3) What are features of effective crew communication; (4) What can be done to enhance communication success? To explore a wider range of communication failures than available from accident reports, we examined a set of incident reports from the Aviation Safety Reporting System. These could be classified into three major categories: those in which language actually interfered with transmission of a message; those in which transmission was adequate but the context was not expressed unambiguously and thus the message received was not the same as the message intended; and those in which the message was received as intended, but was not adequately understood or acted upon, mainly because of cultural factors. The consequences of failed communication can be flight errors (such as when a clearance is not received correctly), loss of situation awareness, or failure of crew members (or ATC and pilots) to build a shared understanding of a situation. Causes of misunderstanding can be traced to a number of sources, often grounded in faulty assumptions held by one or both parties to a conversation. Speakers and listeners often experience "illusionary understanding" in which they think they understand each other, but in fact do not. While this problem can exist within a single culture, it is much more serious across cultures. Training in effective explicit communication is a component of Crew Resource Management training programs developed in the U.S. These programs are being adopted by airlines around the world, with varying degrees of success. The level of success in part depends on how similar the conversational and social styles of those cultures are to those of the U.S. A factor that influences conversational style is a culture's relative positioned on two major dimensions that distinguish national cultural groups: individualism vs. collectivism and degree of power distance. The chapter concludes with a discussion of techniques for overcoming the various classes of communication failures and for effectively adapting training programs to fit the values and norms of cultures around the globe.

Fischer, U.↗
NASA NTRS2001

Automatic Synthesis of UML Designs from Requirements in an Iterative Process

The Unified Modeling Language (UML) is gaining wide popularity for the design of object-oriented systems. UML combines various object-oriented graphical design notations under one common framework. A major factor for the broad acceptance of UML is that it can be conveniently used in a highly iterative, Use Case (or scenario-based) process (although the process is not a part of UML). Here, the (pre-) requirements for the software are specified rather informally as Use Cases and a set of scenarios. A scenario can be seen as an individual trace of a software artifact. Besides first sketches of a class diagram to illustrate the static system breakdown, scenarios are a favorite way of communication with the customer, because scenarios describe concrete interactions between entities and are thus easy to understand. Scenarios with a high level of detail are often expressed as sequence diagrams. Later in the design and implementation stage (elaboration and implementation phases), a design of the system's behavior is often developed as a set of statecharts. From there (and the full-fledged class diagram), actual code development is started. Current commercial UML tools support this phase by providing code generators for class diagrams and statecharts. In practice, it can be observed that the transition from requirements to design to code is a highly iterative process. In this talk, a set of algorithms is presented which perform reasonable synthesis and transformations between different UML notations (sequence diagrams, Object Constraint Language (OCL) constraints, statecharts). More specifically, we will discuss the following transformations: Statechart synthesis, introduction of hierarchy, consistency of modifications, and "design-debugging".

Schumann, Johann↗
NASA NTRSDate not supplied

Efficient Mirrorlet Array Based Integral Field Spectrometer for HWO

Habitable World Observatory (HWO) is a NASA strategic mission recommended by 2020 astronomical decadal survey. Integral spectrometers play an important role to verify if the observed exoplanet is habitable. The traditional lenslet array based Integral Field Spectrometer (IFS) has the advantage of simplicity and compactness. However, it does not use detector pixels efficiently in order to prevent wavelength crosstalk among adjacent spectra. The efficient lenslet/mirrorlet IFS combines the advantages from both lenslet based and imager slicer based IFSes—keeping lenslet IFS’s simplicity and compactness, concurrently adding slicer IFS’s detector efficiency. This paper discusses the principle of efficient lenslet/mirrorlet IFS, design philosophy, and efficient spectral trace layout ideals. It uses HWO NIR IFS requirement as an example to provide an efficiency mirrorlet IFS optical design. The high detector efficiency not only reduces Needed detector pixel numbers, but also reduce the high communication rate demanding for much a large multiple instrument mission. The basic idea of the efficient lenslet/mirrorlet array IFS is to design a lenslet/mirrorlet array in such a way that the images from multiple mirrorlets are grouped and aligned as a spectrum from a single slit. Therefore, the number of detector rows used to prevent wavelength crosstalk is no longer needed. This paper is also going to address how to lay the traces on the detector and what is the difference from the traditional lenslet IFS. Our goal is to show that such an IFS is capable to lay all spectral traces onto a 2k x 2k detector array using HWO NIR requirement that has a higher spectral resolving power R = 70 and a large Field of View (FOV) of 96 λ/D.

Exoplanet↗
DOE OSTI2018

Interwell Communication Study of UWC and MWC Wells in the HFTS

The focus of this paper is to examine the water, oil and proppant communication between wells at the Hydraulic Fracturing Test Site (HFTS) in the Permian Basin. Unique tracers were employed during the stimulation of the HFTS pad in conjunction with many additional diagnostic technologies to evaluate interwell communication, fracture behavior, proppant transport and reservoir drainage. Water and oil chemical tracers were utilized on four Upper Wolfcamp (UWC) and four Middle Wolfcamp (MWC) horizontal wells on the HFTS pad. Each traced well was divided into three or four uniquely traced segments. The segments consisted of consecutive stage groupings that were stimulated with the same water and oil tracers. During the production phase of the project, oil and water samples from a combined total of 33 horizontal and vertical wells were analyzed for the presence of the tracers from the eight wells. Additionally, proppant tracers were employed in the stimulation of two UWC and one MWC horizontal well. After all the wells were completed, a spectral gamma ray log was run on each well to identify the proppant coverage, cluster efficiency, near-wellbore (NWB) fracture behavior and/or any proppant communication that occurred. The results of this project provide a better understanding of the fluid and hydrocarbon communication that is taking place between and within the UWC and MWC wells over an initial short-term period as well as the long term. Additionally, the target zone, stimulation design, production methodology and stimulation sequencing are discussed so that comparisons could be made with other diagnostic data from this project. The insights from this two-year study highlight the continued need to optimize completion designs, even while targeting different benches of the same formation. Additionally, future fracture modeling and design criteria can be enhanced with the hydraulic fracture and propped

Wood, Tanner↗
NASA NTRS2010

Influence of Ionizing Radiation on Stromal-Epithelial Intercellular Communication in Esophageal Carcinogenesis

Esophageal cancer is the 6th leading cause of cancer death worldwide. Its development is associated with a variety of risk factors including tobacco use, heavy alcohol consumption, human papilloma virus infection, and certain dietary factors such as trace mineral and vitamin deficiencies. An association with ionizing radiation exposure is revealed by the high excess relative risk for squamous cell carcinoma of the esophagus observed in the survivors of the atomic bomb detonations in Japan. It is also seen as a secondary malignancy in patients who received radiotherapy for breast and thoracic cancers; additionally, patients with head/neck and oral squamous cell cancers are at increased risk for metachronous esophageal squamous cell cancers. This malignancy is rapidly fatal, mainly because it remains asymptomatic until late, advanced stages when the disease is rarely curable. The stromal microenvironment plays an essential role in the maintenance and modulation of normal epithelial cell growth and differentiation and cross talk between the epithelial and stromal compartments can influence many aspects of malignant progression, including tumor cell proliferation, migration, invasion and recruitment of new blood vessels. To test the hypothesis that radiation exposure plays a role in esophageal carcinogenesis via non-targeted mechanisms involving stromal-epithelial cell communication, we are studying radiation effects on hTERT-immortalized human esophageal epithelial cells and genetic variants grown in co-culture with human esophageal stromal fibroblasts (Okawa et al., Genes & Dev. 2007. 21: 2788-2803). We examined how radiation treatment of stromal fibroblasts affected epithelial migration and invasion, behaviors associated with cancer promotion and progression. Chemotactic and haptotactic migration of epithelial cells stimulated by conditioned media from irradiated fibroblasts was measured using assays conducted in Transwell cell culture chambers. Our results using low LET radiation showed a dose-dependent increase in migration of epithelial cells when exposed to conditioned media from irradiated vs. non-irradiated fibroblasts. We also observed enhanced invasion through a basement membrane simulant. To identify chemotactic proteins secreted by irradiated stromal fibroblasts, we used antibody capture cytokine arrays and have identified several proteins as candidates. Increased secretion of these factors by irradiated fibroblasts was confirmed using ELISA. We are currently analyzing the contribution of these individual factors on epithelial migration and invasion, as well as their influence on cell survival and DNA repair. Studies using high-LET radiation will help determine radiation quality effects on these processes. These results should further our understanding of the mechanisms by which radiation impacts the tissue microenvironment and how it influences cancer development processes.

Patel, Zarana S.↗
NASA NTRS1987

The NASA tracking and data acquisition networks - Their history and their future

The NASA Tracking and Data Acquisition Networks were begun in the late 1950s as a part of the U.S. activities associated with the 1958-59 International Geophysical Year. The first network, the Minitrack Net, evolved into the Space Tracking and Data Acquisition Network (STADAN) for support of scientific satellites in earth orbit. The NASA Mercury and Apollo manned flight programs produced more demanding requirements for near real-time tracking, communications, and orbit determination, thus providing the impetus for new, more sophisticated networks. The Deep Space Network was also created to meet unique requirements of the planetary exploration programs. All of these programs necessitated establishing ground stations in various countries around the world, thus promoting the concept of international cooperation in space activities which NASA has fostered in many programs. This paper traces these networks from their beginnings through the various stages of development and introduction of new technologies to meet the requirements of increasingly more complex space missions. The paper also discusses the planning for new capabilities for tracking, data acquisition and communications support of future programs, including particularly the Space Station in the next decade.

Force, Charles T.↗
DOE OSTI2021

Parasitic erbium photoluminescence in commercial telecom fiber optical components

Noiseless optical components are critical for applications ranging from metrology to quantum communication. Here, we characterize several commercial telecom C-band fiber components for parasitic noise using a tunable laser. We observe the spectral signature of trace concentrations of erbium in all devices from the underlying optical crystals including YVO 4 , LiNbO 3 , TeO 2 , and amorphous material transmitting infrared radiation glass. Furthermore, due to the long erbium lifetime, these signals are challenging to mitigate at the single photon level in the telecom range and suggests the need for higher purity optical crystals.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Chimbuko: A Workflow-Level Scalable Performance Trace Analysis Tool

Due to the sheer volume of data it is typically impractical to analyze the detailed performance of an HPC application running at-scale. While conventional small-scale benchmarking and scaling studies are often sufficient for simple applications, many modern workflow-based applications couple multiple elements with competing resource demands and complex inter-communication patterns for which performance cannot easily be studied in isolation and at small scale. This work discusses Chimbuko, a performance analysis framework that provides real-time, in situ anomaly detection. By focusing specifically on performance anomalies and their origin (aka provenance), data volumes are dramatically reduced without losing necessary details. To the best of our knowledge, Chimbuko is the first online, distributed, and scalable workflow-level performance trace analysis framework. We demonstrate the tool's usefulness on Oak Ridge National Laboratory's Summit system.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1998

Utility of Lava Tubes on Other Worlds

On Mars, as on Earth, lava tubes are found in the extensive lava fields associated with shield volcanism. Lunar lava-tube traces are located near mare-highland boundaries, giving access to a variety of minerals and other resources, including steep slopes, prominent heights for local area communications and observation, large-surface areas in shade, and abundant basalt plains suitable for landing sites, mass-drivers, surface transportation, regolith harvesting, and other uses. Methods for detecting lava tubes include visual observations of collapse trenches and skylights, ground-penetrating radar, gravimetry, magnetometry, seismography, atmospheric effects, laser, lidar, infrared, and human or robotic exploration.

Walden, Bryce E.↗
DOE OSTI2020

Chimbuko: A Workflow-Level Scalable Performance Trace Analysis Tool

ABSTRACT Due to the sheer volume of data it is typically impractical to analyze the detailed performance of an HPC application running at-scale. While conventional small-scale benchmarking and scaling studies are often sufficient for simple applications, many modern workflow-based applications couple multiple elements with competing resource demands and complex inter-communication patterns for which performance cannot easily be studied in isolation and at small scale. This work discusses Chimbuko, a performance analysis framework that provides real-time, in situ anomaly detection. By focusing specifically on performance anomalies and their origin (aka provenance), data volumes are dramatically reduced without losing necessary details. To the best of our knowledge, Chimbuko is the first online, distributed, and scalable workflow-level performance trace analysis framework. We demonstrate the tool's usefulness on Oak Ridge National Laboratory's Summit system.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1989

Method and apparatus for implementing a traceback maximum-likelihood decoder in a hypercube network

A method and a structure to implement maximum-likelihood decoding of convolutional codes on a network of microprocessors interconnected as an n-dimensional cube (hypercube). By proper reordering of states in the decoder, only communication between adjacent processors is required. Communication time is limited to that required for communication only of the accumulated metrics and not the survivor parameters of a Viterbi decoding algorithm. The survivor parameters are stored at a local processor's memory and a trace-back method is employed to ascertain the decoding result. Faster and more efficient operation is enabled, and decoding of large constraint length codes is feasible using standard VLSI technology.

Pollara-Bozzola, Fabrizio↗
NASA NTRS2006

Automatic Locking of Laser Frequency to an Absorption Peak

An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems. The operation of this system is completely automatic: Unlike in the operation of some prior laser-frequency-locking systems, there is ordinarily no need for a human operator to adjust the frequency manually to an initial value close enough to the peak to enable automatic locking to take over. Instead, this system also automatically performs the initial adjustment. The system (see Figure 1) is based on a concept of (1) initially modulating the laser frequency to sweep it through a spectral range that includes the desired absorption peak, (2) determining the derivative of the absorption peak with respect to the laser frequency for use as an error signal, (3) identifying the desired frequency [at the very top (which is also the middle) of the peak] as the frequency where the derivative goes to zero, and (4) thereafter keeping the frequency within a locking range and adjusting the frequency as needed to keep the derivative (the error signal) as close as possible to zero. More specifically, the system utilizes the fact that in addition to a zero crossing at the top of the absorption peak, the error signal also closely approximates a straight line in the vicinity of the zero crossing (see Figure 2). This vicinity is the locking range because the linearity of the error signal in this range makes it useful as a source of feedback for a proportional + integral + derivative control scheme that constantly adjusts the frequency in an effort to drive the error to zero. When the laser frequency deviates from the midpeak value but remains within the locking range, the magnitude and sign of the error signal indicate the amount of detuning and the control circuitry adjusts the frequency by what it estimates to be the negative of this amount in an effort to bring the error to zero.

Koch, Grady J.↗
DOE OSTI2015

A Framework for Batched and GPU-Resident Factorization Algorithms Applied to Block Householder Transformations

As modern hardware keeps evolving, an increasingly effective approach to developing energy efficient and high-performance solvers is to design them to work on many small size and independent problems. Many applications already need this functionality, especially for GPUs, which are currently known to be about four to five times more energy efficient than multicore CPUs. We describe the development of one-sided factorizations that work for a set of small dense matrices in parallel, and we illustrate our techniques on the QR factorization based on Householder transformations. We refer to this mode of operation as a batched factorization. Our approach is based on representing the algorithms as a sequence of batched BLAS routines for GPU-only execution. This is in contrast to the hybrid CPU-GPU algorithms that rely heavily on using the multicore CPU for specific parts of the workload. But for a system to benefit fully from the GPU's significantly higher energy efficiency, avoiding the use of the multicore CPU must be a primary design goal, so the system can rely more heavily on the more efficient GPU. Additionally, this will result in the removal of the costly CPU-to-GPU communication. Furthermore, we do not use a single symmetric multiprocessor(on the GPU) to factorize a single problem at a time. We illustrate how our performance analysis, and the use of profiling and tracing tools, guided the development and optimization of our batched factorization to achieve up to a 2-fold speedup and a 3-fold energy efficiency improvement compared to our highly optimized batched CPU implementations based on the MKL library(when using two sockets of Intel Sandy Bridge CPUs). Compared to a batched QR factorization featured in the CUBLAS library for GPUs, we achieved up to 5x speedup on the K40 GPU.

Dong, Tingzing Tim↗
DOE OSTI2016

A Framework for Counterfeit Smart Grid Device Detection

The core vision of the smart grid concept is the realization of reliable two-­way communications between smart devices (e.g., IEDs, PLCs, PMUs). The benefits of the smart grid also come with tremendous security risks and new challenges in protecting the smart grid systems from cyber threats. Particularly, the use of untrusted counterfeit smart grid devices represents a real problem. Consequences of propagating false or malicious data, as well as stealing valuable user or smart grid state information from counterfeit devices are costly. Hence, early detection of counterfeit devices is critical for protecting smart grid’s components and users. To address these concerns, in this poster, we introduce our initial design of a configurable framework that utilize system call tracing, library interposition, and statistical techniques for monitoring and detection of counterfeit smart grid devices. In our framework, we consider six different counterfeit device scenarios with different smart grid devices and adversarial seZings. Our initial results on a realistic testbed utilizing actual smart-­grid GOOSE messages with IEC-­61850 communication protocol are very promising. Our framework is showing excellent rates on detection of smart grid counterfeit devices from impostors.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS2002

Trace level detection of analytes using artificial olfactometry

The present invention provides a device for detecting the presence of an analyte, such as for example, a lightweight device, including: a sample chamber having a fluid inlet port for the influx of the analyte; a fluid concentrator in flow communication with the sample chamber wherein the fluid concentrator has an absorbent material capable of absorbing the analyte and capable of desorbing a concentrated analyte; and an array of sensors in fluid communication with the concentrated analyte to be released from the fluid concentrator.

Lewis, Nathan S.↗
DOE OSTI2015

Experiment vs simulation RT WFNDEC 2014 benchmark: CIVA results

The French Atomic Energy Commission and Alternative Energies (CEA) has developed for years the CIVA software dedicated to simulation of NDE techniques such as Radiographic Testing (RT). RT modelling is achieved in CIVA using combination of a determinist approach based on ray tracing for transmission beam simulation and a Monte Carlo model for the scattered beam computation. Furthermore, CIVA includes various detectors models, in particular common x-ray films and a photostimulable phosphor plates. This communication presents the results obtained with the configurations proposed in the World Federation of NDEC 2014 RT modelling benchmark with the RT models implemented in the CIVA software.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗