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At least 343 records · Page 19

Application of the Global Positioning System to crustal deformation measurement. II - The influence of errors in orbit determination networks

The errors introduced into GPS measurements of a geodetic network by means of adopting different sets of stations in central and southern California as fixed points (termed fiducial stations) were investigated. Solutions for a crustal deformation network spanning distances up to 350 km were computed with a variety of fiducial networks, using fiducial coordinates determined from VLBI. Results showed that three receivers collocated with VLBI sites provide a stable reference system at a few millimeter level in the horizontal components and at 10 mm in the vertical components, indicating that local survey errors between VLBI and GPS markers at fiducial sites do not severely affect the estimates of interstation vectors.

Larson, Kristine M.↗

Using Weather-Based Irrigation Scheduling to Optimize Red Cabbage Production

A replicated field trial was performed on a Chualar sandy loam in California’s Salinas Valley during 2020 to investigate the yield response of drip-irrigated red cabbage to applied water volume. The crop was transplanted on 29-April and established with approximately 4 inches of water uniformly applied by overhead sprinklers. At 22 days after transplanting (DAT), five drip-irrigation treatments were established at 50, 75, 100, 125, and 150% of estimated daily crop evapotranspiration (ETc). The treatments were replicated 6 times following a randomized complete block design. The 100% crop water requirement was specified by CropManage, an irrigation scheduling application that combines a crop coefficient approach with reference evapotranspiration data from the California Irrigation Management Information System. The crop was irrigated 3 times per week. Nitrogen fertilizer, totaling 320 lbs/ac, was applied through the drip system once per week. Commercial carton yields were evaluated 85 DAT. The 100% ETc treatment received a total of 18.3 inches of water including sprinkler establishment and had the highest yield at 57 tons/ac, while the 50% treatment (11.5 inches) yielded a low of 32 tons/ac. For reference, average applied water reported for this crop on the Central Coast is about 22.5 inches by way of a variety of irrigation methods including drip, sprinkler, and furrow. Aboveground biomass was evaluated 91 DAT. The 100% treatment had the highest fresh (105 tons/ac) and dry (7.7 tons/ac) biomass yield. Commercial bulk yields at 98 DAT and were maximized by 20-24 inches of water (100%, 125% treatments) and ranged from a high of 67 tons/ac for 125% ETc treatment (24.3 inches of water) to 35 tons/ac for the 50% treatment (12.6 inches). The results demonstrated that yield and quality targets for this crop can be met by drip irrigation, and CropManage is an effective decision support tool for evaluating crop water requirements based on weather data.

Weather-Based↗

Summer Final Report

The summer of 2012 has been filled with many memorable events and activities. As an intern, I had responsibilities that had to be fulfilled. My tour of duty was completed as an administrative student trainee in the Information Technology and Communications Services Business Office (IT-A). In accordance with the Business Objectives and Agreement of the Business Office and my performance plan, I was to provide business office support, improve business, project management, and technical work processes. With this being stated, I supported a project called "The Big Move Project" (TBMP), which will take course over the next several years. The Big Move Project is the planning of the Information Technology (IT) Directorate's relocation to various buildings in the course of upcoming years, when designs and the building of Central Campus have been completed. Working directly with my supervisor and the project manager, I was responsible for gathering both administrative and operational area requirements for the Information Technology (IT) Directorate, along with its outsourced support and contractors, such as IMCS, NICS, and ACES. My first action was to create rubrics that will serve as a guideline for the information that should be given by each branch of IT. After receiving that information via a few KAITS actions, I was able to start the consolidation process, and begin working on a presentation. A SharePoint was created shortly after for others to view the progression of the project, which I managed. During the consolidation ofthis information, I would occasionally present to the IT Deputy Director and IT Chiefs. The draft of this presentation was shown to employees of Center Operations (T A) and stakeholders-IT Chief Officers and contractor managers-in the relocation of IT to make them aware of what requirements must be met that will enable IT to be accommodated appropriately in the design of Central Campus Phase 11-the time in which IT and its contractors are scheduled to be relocated. Besides supporting TBMP, I also supported the Section 508 Policy Compliance Coordinator, R. Liang. Section 508 is a policy that requires employers to implement accessibility assurance of information and technology to disabled communities. On Thursday, July 19, 2012, I was able to go to Camp Boggy Creek-a camp for disabled children-for an education outreach, in collaboration with the Education Office. We shared with them information about how astronauts live and work in space, they were able to ride hovercrafts, build paper rockets, and then launch them outside. Although this outreach was quite fun with the kids at the camp, this was a learning opportunity to gain some insight to those with cognitive and physical disabilities, the problems they typically face, and in tum, how to accommodate those with disabilities in the work environment. In the process of implementing accessibility and Section 508 compliance, I attended various teleconferences, did field runs to supply closed-caption call phones to employees with limited hearing, and helped with the development of the charter ofthe Section 508 Compliance Working Group.

Makidi, Nitou↗

A Limited-In-Scope Comparison of Subsidence Scenarios For 3D Vadose Zone PORFLOW Trench Models

This technical memorandum summarizes the results from two separate sequences of 3D PORFLOW vadose zone flow and contaminant transport models that were used to test the impact of different spatial distributions of subsidence boundary conditions. More specifically, the two simulation setups used a general conceptual model for an engineered trench (ET): one with a subsided region specified in the center of the trench and one with a subsided region located at the end of the trench. Both subsided regions had the same geometric specifications (e.g., length, width, orientation), but used water infiltration rate boundary conditions that appropriately accounted for surface runoff and lateral drainage from the adjacent upslope intact regions of the final closure cap. Because of the substantially higher water infiltration rate associated with the subsided region at the end of the trench, this geometry produced higher absolute peak fluxes to the water table for all six radionuclides that were simulated. However, the slower release rate of the centrally located subsided hole geometry produced a higher flux to the water table in the time period subsequent to the absolute peak. A third model was implemented as a control, where the water infiltration rate that corresponds to the centrally located subsided region was applied at the end of the trench to highlight the purely geometric effects. The results show that a higher water infiltration rate produces a sharper peak, while a lower infiltration rate leads to a broader peak. A centrally located hole impacts more of the waste zone, producing a higher peak when an equal infiltration rate is applied. These generalized qualitative differences, and their impacts on the overall modeling workflow (i.e., from vadose zone models to limits and dose calculations), should receive appropriate consideration during the development of conceptual models.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Estimation of neutral wind velocity in the ionospheric heights by HF-Doppler technique

Three net stations located about 100 kilometers apart were set up around the station of the standard frequency and time signals (JJY) in central Japan and measurements of atmospheric gravity waves in the ionospheric heights (F-region, 200 to 400 km) were made by means of the HF-Doppler technique during the period of February 1983 to December 1983. The frequencies of the signals received are 5.0, 8.0 and 10.0 MHz, but only the 8.0 MHz signals are used for the present study, because no ambiguities due to the interference among other stations such as BPM, BSF, etc. exist by the use of 8.0 MHz. Two main results concerning the horizontal phase velocity of the atmospheric gravity waves with periods of 40 to 70 min may be summarized as follows: (1) the value of the phase velocity ranges from 50 m/s to 300 m/s; (2) the direction of the gravity wave propagation shows a definite seasonal variation. The prevailing direction of the gravity waves in winter is from north to south, which is consistent with the results obtained from other investigations. On the other hand, the two directions, from northeast to southwest and from southeast to northeast, dominate in summer.

Kitamura, T.↗

Space Radiation

Astronauts receive the highest occupational radiation exposure. Effective protections are needed to ensure the safety of astronauts on long duration space missions. Increased cancer morbidity or mortality risk in astronauts may be caused by occupational radiation exposure. Acute and late radiation damage to the central nervous system (CNS) may lead to changes in motor function and behavior, or neurological disorders. Radiation exposure may result in degenerative tissue diseases (non-cancer or non-CNS) such as cardiac, circulatory, or digestive diseases, as well as cataracts. Acute radiation syndromes may occur due to occupational radiation exposure.

Wu, Honglu↗

Verifying the Computational Integrity of Power Grid Controls with Zero-Knowledge Proof

The control of future power grids is migrating from a centralized to a distributed/decentralized scheme to enable a massive penetration of distributed energy resources with rising dependence on communication infrastructure. A common assumption made for most existing distributed/decentralized controllers is that local controllers would faithfully follow the designated controller dynamics based on the data received from communication channels. However, with increased probability of cyberattacks on Operational Technology infrastructure, such an assumption could be risky because proper execution of the controller dynamics is then built on trust in secure communication and computation. In this work, we leverage a cryptography technology known as zero-knowledge scalable transparent arguments of knowledge (zk-STARK) to verify the computational integrity of power grid control algorithms, with projected linear dynamics-based control schemes as the initial proof-of-concept test case. The method presented here converts the cybersecurity challenge of data integrity for grid control into a subset of computational integrity.

computational integrity↗

X-wing fly-by-wire vehicle management system

A complete, computer based, vehicle management system (VMS) for X-Wing aircraft using digital fly-by-wire technology controlling many subsystems and providing functions beyond the classical aircraft flight control system. The vehicle management system receives input signals from a multiplicity of sensors and provides commands to a large number of actuators controlling many subsystems. The VMS includes--segregating flight critical and mission critical factors and providing a greater level of back-up or redundancy for the former; centralizing the computation of functions utilized by several subsystems (e.g. air data, rotor speed, etc.); integrating the control of the flight control functions, the compressor control, the rotor conversion control, vibration alleviation by higher harmonic control, engine power anticipation and self-test, all in the same flight control computer (FCC) hardware units. The VMS uses equivalent redundancy techniques to attain quadruple equivalency levels; includes alternate modes of operation and recovery means to back-up any functions which fail; and uses back-up control software for software redundancy.

Fischer, Jr., William C.↗

Stabilization of Phase of a Sinusoidal Signal Transmitted Over Optical Fiber

In the process of connecting widely distributed antennas into a coherent array, it is necessary to synchronize the timing of signals at the various locations. This can be accomplished by distributing a common reference signal from a central source, usually over optical fiber. A high-frequency (RF or microwave) tone is a good choice for the reference. One difficulty is that the effective length of the optical fiber changes with temperature and mechanical stress, leading to phase instability in the received tone. This innovation provides a new way to stabilize the phase of the received tone, in spite of variations in the electrical length of the fiber. Stabilization is accomplished by two-way transmission in which part of the received signal is returned to the transmitting end over an identical fiber. The returned signal is detected and used to close an electrical servo loop whose effect is to keep constant the phase of the tone at the receiving end.

DAddario, Larry R.↗

Characterization and Oxidation Behavior of Rayon-Derived Carbon Fibers

Rayon-derived fibers are the central constituent of reinforced carbon/ carbon (RCC) composites. Optical, scanning electron, and transmission electron microscopy were used to characterize the as-fabricated fibers and the fibers after oxidation. Oxidation rates were measured with weight loss techniques in air and oxygen. The as-received fibers are approximately 10 micron in diameter and characterized by grooves or crenulations around the edges. Below 800 C, in the reaction-controlled region, preferential attack began in the crenulations and appeared to occur down fissures in the fibers.

Jacobson, Nathan↗

Carbon Monoxide in the Cold Debris of Supernova 1987A

We report spectroscopic and imaging observations of rotational transitions of cold CO and SiO in the ejecta of SN1987A, the first such emission detected in a supernova remnant. In addition to line luminosities for the CO J = 1-0, 2-1, 6-5, and 7-6 transitions, we present upper limits for all other transitions up to J = 13-12, collectively measured from the Atacama Large Millimeter Array, the Atacama Pathfinder EXperiment, and the Herschel Spectral and Photometric Imaging REceiver. Simple models show the lines are emitted from at least 0.01 M ☉ of CO at a temperature >14 K, confined within at most 35% of a spherical volume expanding at ~2000 km s-1. Moreover, we locate the emission within 1'' of the central debris. These observations, along with a partial observation of SiO, confirm the presence of cold molecular gas within supernova remnants and provide insight into the physical conditions and chemical processes in the ejecta. Furthermore, we demonstrate the powerful new window into supernova ejecta offered by submillimeter observations.

Cold↗

Spark-ignited direct-injection engine combustion systems

A direct-injection stratified charge internal combustion engine includes a combustion cylinder to receive an air-fuel mixture, and an air intake port to inlet air into the combustion cylinder. The direct-injection engine also includes a fuel injector configured to deliver fuel within the cylinder in a spray pattern substantially aligned to a cylinder central axis to create the air-fuel mixture. A spark igniter is located within a path of the spray pattern to ignite combustion of the air-fuel mixture. The direct-injection engine further includes a movable piston defining a lower boundary of the combustion cylinder to contain the combustion of the air-fuel mixture. The piston is configured to include a bowl portion having local geometric features located on an intake port side of the combustion cylinder to redirect fluid flow towards a vortex in fluid communication with a combustion location near the cylinder central axis.

42 ENGINEERING↗

High voltage systems (tube-type microwave)/low voltage system (solid-state microwave) power distribution

SPS satellite power distribution systems are described. The reference Satellite Power System (SPS) concept utilizes high-voltage klystrons to convert the onboard satellite power from dc to RF for transmission to the ground receiving station. The solar array generates this required high voltage and the power is delivered to the klystrons through a power distribution subsystem. An array switching of solar cell submodules is used to maintain bus voltage regulation. Individual klystron dc voltage conversion is performed by centralized converters. The on-board data processing system performs the necessary switching of submodules to maintain voltage regulation. Electrical power output from the solar panels is fed via switch gears into feeder buses and then into main distribution buses to the antenna. Power also is distributed to batteries so that critical functions can be provided through solar eclipses.

Nussberger, A. A.↗

Availability of Seasat synthetic aperture radar imagery

One of the sensors of the Seasat satellite was a synthetic aperture radar (SAR), which was operated over both oceanic and land areas. The Seasat SAR was an active imaging microwave system which transmitted and received horizontally polarized radiation at L-band frequency (1.275 GHz, 23-cm wavelength). Extensive coverage was obtained over North America, Europe, the Eastern Pacific Ocean, the Western and Northern Atlantic Ocean, and the Beaufort Sea. Surface coverage was also acquired over limited portions of Central America, the Gulf of Mexico, and the Caribbean Sea. The majority of the data has been optically processed in a so-called survey mode. Each optically processed Seasat pass has a swath width of 100 km at a scale of 1:500,000. A subset of the SAR data has been digitally processed in a so-called high-resolution mode. Digital processing has been performed upon selected scenes with dimensions of 100 x 100 km. Digitally processed imagery has a nominal ground resolution of 25 m.

Holt, B.↗

Spatial and Temporal Scaling of Thermal Infrared Remote Sensing Data

Although remote sensing has a central role to play in the acquisition of synoptic data obtained at multiple spatial and temporal scales to facilitate our understanding of local and regional processes as they influence the global climate, the use of thermal infrared (TIR) remote sensing data in this capacity has received only minimal attention. This results from some fundamental challenges that are associated with employing TIR data collected at different space and time scales, either with the same or different sensing systems, and also from other problems that arise in applying a multiple scaled approach to the measurement of surface temperatures. In this paper, we describe some of the more important problems associated with using TIR remote sensing data obtained at different spatial and temporal scales, examine why these problems appear as impediments to using multiple scaled TIR data, and provide some suggestions for future research activities that may address these problems. We elucidate the fundamental concept of scale as it relates to remote sensing and explore how space and time relationships affect TIR data from a problem-dependency perspective. We also describe how linearity and non-linearity observation versus parameter relationships affect the quantitative analysis of TIR data. Some insight is given on how the atmosphere between target and sensor influences the accurate measurement of surface temperatures and how these effects will be compounded in analyzing multiple scaled TIR data. Last, we describe some of the challenges in modeling TIR data obtained at different space and time scales and discuss how multiple scaled TIR data can be used to provide new and important information for measuring and modeling land-atmosphere energy balance processes.

Quattrochi, Dale A.↗

Survey: National Environmental Satellite Service

The national Environmental Satellite Service (NESS) receives data at periodic intervals from satellites of the Synchronous Meteorological Satellite/Geostationary Operational Environmental Satellite series and from the Improved TIROS (Television Infrared Observational Satellite) Operational Satellite. Within the conterminous United States, direct readout and processed products are distributed to users over facsimile networks from a central processing and data distribution facility. In addition, the NESS Satellite Field Stations analyze, interpret, and distribute processed geostationary satellite products to regional weather service activities.

Source record↗

Earth-Image Tracking in the IR for Deep Space Optical Communications

Sub-microradian level laser beam pointing to an Earth-based receiver is required for deep space optical communications. This requires a beacon emanated from Earth towards the spacecraft. The beacon could be a laser or reflected sunlight from Earth. Earth image tracking in the visible is hampered by significant albedo variations and/or crescent Earth image yielding large central errors. Here, we report results of Earth-image tracking in the infrared (8 to 13 micron) region of the spectrum with the aim of substantially alleviating the two challenges mentioned earlier.

earth image tracking↗

Sensing Electrical Networks Securely & Economically (SENSE)

The growing adoption of distributed energy resources (DERs) like battery energy storage systems and roof top solar/PV and the rapid penetration of electric vehicles (EVs), the electric grid is undergoing a major transformation with elevated stress on legacy grid assets. Despite a lot of expenditure to address these challenges, both in dollars and manpower, utilities have not been able to receive the value that was promised. The gains have been most visible at the transmission and substation level, especially where the main objective was improving operational and economic efficiency for the utility. Improving visibility and control at a few select points enhances the existing and established paradigm of centralized command and control. With changing load patterns, load types and the overall transition to an “active grid”, the centralized control and coordination paradigm gets challenged. To address the challenges, a new architecture and mechanism is needed, one that supports decentralized control and decision making, extracting value streams at the grid edge, particularly as the changes are fueled by transitions occurring in the distribution system. To address this, a communications and data processing platform, “GAMMA” was developed and demonstrated through the project. At the heart of the platform, are distributed, intelligent edge nodes with sensing and compute capabilities, that can record and analyze information locally. They are embedded in sensors and actuators specific to different distribution system applications. Phase 1 of the project focused on developing novel sensor technology that can be used for monitoring utility pole top distribution transformers. The sensors were designed with the objective of being low-cost, communicating with the GAMMA cloud using novel “delay-tolerant” networking using Bluetooth and a secure mobile application. They were non-intrusive in nature so that they can be installed quickly in the field, resulting in overall low cost of deployment and operations. Following the successful completion of Phase 1, the team manufactured 100 units for a field demonstration in Phase 2. The field demonstration was carried out on two real feeder systems with the local utility partner. In total, 100 sensors were installed and operated over a period of 6 months in the state of Georgia. The platform is operational end to end, with the cloud infrastructure deployed on a distributed, serverless environment that can serve multiple data streams, an analytics engine and a portal to securely view the data from multiple assets. The data collected through the GAMMA Mobile Phone app showcased the viability of the novel delay tolerant networking architecture, and the data processing algorithms developed through the course of the project, were successful in extracting important information about the overall network, improving the utility’s visibility and situational awareness in the distribution feeder.

24 POWER TRANSMISSION AND DISTRIBUTION↗