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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Compilation and Analysis of 20- and 30-GHz Rain Fade Events at the ACTS NASA Ground Station: Statistics and Model Assessment

Since the beginning of the operational phase of the NASA Research Center's Advanced Communication Technology Satellite (ACTS), signal-fade measurements have been recorded at the NASA Ground Station located in Cleveland, Ohio, with the use of the 20- and 30-GHz beacon signals. Compilations of the daily data have been statistically analyzed on a monthly and yearly basis. Such analyses have yielded relevant parameters as (1) cumulative monthly and yearly probability distributions of signal attenuation by rain, (2) attenuation duration versus attenuation threshold probabilities, and (3) rate-of-fade probabilities. Not only are such data needed for a realistic data base to support the design and performance analysis of future satellite systems, but they are necessary to assess predictions made with the ACTS Rain Attenuation Prediction Model.

Manning, Robert M.↗
NASA NTRS2004

Statistical and Prediction modeling of the Ka Band Using Experimental Results from ACTS Propagation Terminals at 20.185 and 27.505 GHZ

With the increase in demand for wireless communication services, most of the operating frequency bands have become very congested. The increase of wireless costumers is only fractional contribution to this phenomenon. The demand for more services such as video streams and internet explorer which require a lot of band width has been a more significant contributor to the congestion in a communication system. One way to increase the amount of information or data per unit of time transmitted with in a wireless communication system is to use a higher radio frequency. However in spite the advantage available in the using higher frequency bands such as, the Ka-band, higher frequencies also implies short wavelengths. And shorter wavelengths are more susceptible to rain attenuation. Until the Advanced Communication Technology Satellite (ACTS) was launched, the Ka- band frequency was virtually unused - the majority of communication satellites operated in lower frequency bands called the C- and Ku- bands. Ka-band is desirable because its higher frequency allows wide bandwidth applications, smaller spacecraft and ground terminal components, and stronger signal strength. Since the Ka-band is a high frequency band, the millimeter wavelengths of the signals are easily degraded by rain. This problem known as rain fade or rain attenuation The Advanced Communication Technology Satellite (ACTS) propagation experiment has collected 5 years of Radio Frequency (RF) attenuation data from December 1993 to November 1997. The objective of my summer work is to help develop the statistics and prediction techniques that will help to better characterize the Ka Frequency band. The statistical analysis consists of seasonal and cumulative five-year attenuation statistics for the 20.2 and 27.5 GHz. The cumulative five-year results give the link outage that occurs for a given link margin. The experiment has seven ground station terminals that can be attributed to a unique rain zone climate. The locations are White Sands, NM, Tampa, Fly Clarksburg, MD, Norman, OK, Ft. Collins, COY Vancouver, BC, and Fairbanks, AK. The analysis will help us to develop and define specific parameters that will help system engineers develop the appropriated instrumentation and structure for a Ka-band wireless communication systems and networks.

Ogunwuyi, Oluwatosin O.↗
NASA NTRS1993

An Active K/K-Band Antenna Array for the NASA ACTS Mobile Terminal

An active K/K-band antenna array is currently under development for NASA's ACTS Mobile Terminal (AMT). The AMT task will demonstrate voice, data, and video communications to and from the AMT vehicle in Los Angeles, California, and a base station in Cleveland, Ohio, via the ACTS satellite at 30 and 20 GHz.

Antenna Array↗
NASA NTRS2010

The Atacama Cosmology Telescope (ACT): Beam Profiles and First SZ Cluster Maps

The Atacama Cosmology Telescope (ACT) is currently observing the cosmic microwave background with arcminute resolution at 148 GHz, 218 GHz, and 277 GHz, In this paper, we present ACT's first results. Data have been analyzed using a maximum-likelihood map-making method which uses B-splines to model and remove the atmospheric signal. It has been used to make high-precision beam maps from which we determine the experiment's window functions, This beam information directly impacts all subsequent analyses of the data. We also used the method to map a sample of galaxy clusters via the Sunyaev-Ze1'dovich (SZ) effect, and show five clusters previously detected with X-ray or SZ observations, We provide integrated Compton-y measurements for each cluster. Of particular interest is our detection of the z = 0.44 component of A3128 and our current non-detection of the low-redshift part, providing strong evidence that the further cluster is more massive as suggested by X-ray measurements. This is a compelling example of the redshift-independent mass selection of the SZ effect.

Hincks, A. D.↗
NASA NTRS2012

An Affordability Comparison Tool (ACT) for Space Transportation

NASA bas recently emphasized the importance of affordability for Commercial Crew Development Program (CCDP), Space Launch Systems (SLS) and Multi-Purpose Crew Vehicle (MPCV). System architects and designers are challenged to come up with architectures and designs that do not bust the budget. This paper describes the Affordability Comparison Tool (ACT) analyzes different systems or architecture configurations for affordability that allows for a comparison of: total life cycle cost; annual recurring costs, affordability figures-of-merit, such as cost per pound, cost per seat, and cost per flight, as well as productivity measures, such as payload throughput. Although ACT is not a deterministic model, the paper develops algorithms and parametric factors that use characteristics of the architectures or systems being compared to produce important system outcomes (figures-of-merit). Example applications of outcome figures-of-merit are also documented to provide the designer with information on the relative affordability and productivity of different space transportation applications.

McCleskey, C. M.↗
NASA NTRS2019

Validation of Regional CO2 Concentrations in the ECMWF Real-Time Analysis and Carbon-Tracker Reanalysis with Airborne Observations from ACT-A Field Campaign

Through verifying against hundreds of hours of airborne in-situ measurements from the NASA-sponsored Atmospheric Carbon and Transport – America (ACT-A) field campaign, this study systematically examines the regional uncertainties and biases of the carbon dioxide (CO2) concentrations from two of the state-of-the-art global analysis products, namely the real-time analysis from the European Center (EC) for Medium Range Forecasting and NOAA’s near real-time Carbon Tracker (CT) reanalysis. It is found that both the EC and CT-NRT analyses agree reasonably well with the independent ACT-A flight-level CO2 measurements in the free troposphere but the uncertainties are considerably larger in the boundary layer during both the summer months of 2016 and the winter months of 2017. There are also strong variabilities in accuracy and bias between seasons, and across three different subregions in the United States (Mid-Atlantic, Midwest and South). Overall, the analysis uncertainties of the EC and CT-NRT analyses in terms of root-mean square deviations against airborne data are comparable to each other, both of which are between 1-2 ppm in the free troposphere but can be as large as 10 ppm near the surface, which are grossly consistent with the difference between the two analyses. The current study not only provides systematic uncertainty estimates for both analysis products over North America but also demonstrated that these two independent estimates can be used to approximate the overall regional CO2 analysis uncertainties. Both statistics are important in future studies in quantifying the uncertainties of regional carbon concentration and flux estimates, as well as in assessing the impact of regional transport through more refined regional modeling and analysis systems.

Chen, Hans W.↗
NASA NTRS1993

Channel and Terminal Description of the ACTS Mobile Terminal

The Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT) is a proof-of-concept K/Ka-band mobile satellite communications terminal under development by NASA at the Jet Propulsion Laboratory. Currently, the AMT is undergoing system integration and test in preparation for a July 1993 ACTS launch and the subsequent commencement of mobile experiments in the fall of 1993. The AMT objectives are presented, followed by a discussion of the AMT communications channel, and mobile terminal design and performance.

communications↗
NASA NTRS2024

A Multiwavelength Approach to Constraining the Merger Properties of ACT-CL J0034.4+0225

ACT-CL J0034.4+0225 is a previously unrecognized merging galaxy cluster at z = 0.38588 ± 0.00068. Our primary evidence is provided by a 21 ks Chandra image that shows two surface brightness peaks separated by ∼49″ (259 kpc) surrounded by an extended cluster gas distribution. Each gas peak contains a brightest cluster galaxy, offset from the gas peak. We collect new South African Large Telescope optical spectra that, when augmented by archival data, yield redshifts for the two BGCs and 58 other cluster members. Archival Giant Metrewave Radio Telescope and MeerKAT data reveal a radio halo that encompasses the X-ray peaks. We provide and compare three X-ray-based mass estimates (5.0 × 1014Me, 6.4 × 1014Me, and 8.6 × 1014Me). The Planck and ACT Sunyaev–Zel’dovich masses are ≈5.8 × 1014 Me. We constrain the merger state and properties by comparing them to an existing suite of N-body/hydrodynamical models using the measured gas peak separation (259 kpc, projected) and radial velocity difference (0–1000 km s−1 ). This constrains the epoch of the merger to be within ∼100 Myr of first pericenter passage. A strong lensing analysis constrains the mass ratio to be in the range 1:1–1:20, while the cluster morphology prefers values near the equal-mass range.

Peter Doze↗
DOE OSTI2012

Science Goals for the ARM Recovery Act Radars

Science Goals for the ARM Recovery Act Radars. In October 2008, an ARM workshop brought together approximately 30 climate research scientists to discuss the Atmospheric Radiation Measurement (ARM) Climate Research Facility's role in solving outstanding climate science issues. Through this discussion it was noted that one of ARM's primary contributions is to provide detailed information about cloud profiles and their impact on radiative fluxes. This work supports cloud parameterization development and improved understanding of cloud processes necessary for that development. A critical part of this work is measuring microphysical properties (cloud ice and liquid water content, cloud particle sizes, shapes, and distribution). ARM measurements and research have long included an emphasis on obtaining the best possible microphysical parameters with the available instrumentation. At the time of the workshop, this research was reaching the point where additional reduction in uncertainties in these critical parameters required new instrumentation for applications such as specifying radiative heating profiles, measuring vertical velocities, and studying the convective triggering and evolution of three-dimensional (3D) cloud fields. ARM was already operating a subset of the necessary instrumentation to make some progress on these problems; each of the ARM sites included (and still includes) a cloud radar (operating at 35 or 94 GHz), a cloud lidar, and balloon-borne temperature and humidity sensors. However, these measurements were inadequate for determining detailed microphysical properties in most cases. Additional instrumentation needed to improve retrievals of microphysical processes includes radars at two additional frequencies for a total of three at a single site (35 GHz, 94 GHz, and a precipitation radar) and a Doppler lidar. Evolving to a multi-frequency scanning radar is a medium-term goal to bridge our understanding of two-dimensional (2D) retrievals to the 3D cloud field. These additional microphysical measurements would allow detailed cloud properties to be derived even in the presence of light precipitation. It is important to couple these detailed measurements of cloud microphysics to vertical motion on the cloud scale to couple microphysics with meteorological processes. Vertically pointing Doppler radars provide the vertical motion of cloud particles but, to separate particle motion from air motion, a wind profiler is required. The American Recovery and Reinvestment Act provided the means to address these needs and implement a multi-frequency suite of radars, including scanning radars, at each of the ARM sites. In addition, Doppler lidars have been deployed at several sites. With these new measurement capabilities, ARM has the measurement capabilities to tackle the problems of improving microphysical profile descriptions and evaluating the relationship between our current narrow-field-of view, zenith perspective on clouds to a description of the full 3D cloud field and its temporal evolution.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

The National Historic Preservation Act is Not Your Problem, But How You are Addressing it for Your CERCLA Project May Be - 12344

The 1995 Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE) joint 'Policy on Decommissioning of Department of Energy Facilities Under CERCLA was developed so that decommissioning could occur in a manner that ensures protection of worker and public health and the environment, that is consistent with Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), that provides for stakeholder involvement, and that achieves risk reduction without unnecessary delay'. The source of the 'unnecessary delays' the joint policy intended to avert could be attributed to numerous factors such as obtaining permits, conducting administrative activities, or implementing regulatory processes that could yield, among other things, differing preferred alternatives. Why, you might ask, more than fifteen years later, does DOE continue to struggle through CERCLA projects with unnecessary delays? From problem identification, to determination of nature and extent, to alternative analysis and ultimately remedy selection and implementation, reaching a compliant and effective clean-up end-point can be a process that seems to mimic geologic timescales. The source of these delays is often the failure to use all of the tools the CERCLA process offers. As one example, renewed commitment to follow the CERCLA process to address the regulatory reviews pursuant to the National Historic Preservation Act (NHPA) is called for. Project managers implementing CERCLA actions in any agency, not only DOE, do not need to be apprehensive about using the CERCLA process for NHPA review but should welcome it. It is critical that methods are used that address substantive NHPA requirements clearly and consistently, and that they are shared and communicated as frequently as needed to interested and questioning stakeholders. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

The Road to 2020: Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA): Cleanup of the East Tennessee Technology Park - 17425

Uranium enrichment activities at the 890-ha (2,200-acre) East Tennessee Technology Park (ETTP), formerly the Oak Ridge Gaseous Diffusion Plant, date back to the World War II Manhattan Project. The site produced nuclear fuel for weapons and reactors for four decades. Because of these operations, ETTP has a legacy of radiologically and chemically contaminated buildings, soil, sediment, and groundwater that required remedial action to reduce the risk to human health and the environment. Since the early 1990's, the DOE Oak Ridge Office of Environmental Management (OREM) has directed the environmental cleanup of this contaminated site through the Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA) process. Cleanup activities have included the demolition of contaminated facilities and structures, including five gaseous diffusion buildings; remediation of contaminated soils; disposal of associated waste; and treatment of contaminated groundwater. In August 2016, DOE realized its Vision 2016, demolition of all five gaseous diffusion buildings at ETTP. This milestone marked the first time that an entire uranium enrichment complex has been demolished. The landmark cleanup included deactivation and demolition of 418,064 m{sup 2} (4.5 million ft{sup 2}) of radiologically and chemically contaminated facilities, and disposal of more than 55,000 truckloads of debris. Fulfillment of Vision 2016 was a major step toward completing ETTP cleanup by 2020. To attain 2020 cleanup, DOE and its cleanup contractor, URS - CH2M Oak Ridge LLC (UCOR), must complete demolition of the following areas: - Poplar Creek Facilities; - K-731 Switch House; - Building K-1037; - Central Neutralization Facility; - K-1200 Complex; - Toxic Substances Control Act Incinerator facilities; - Balance of Site Facilities. In addition, DOE will complete all remedial actions in accordance with current Records of Decision (RODs); as well as cleanup activities involving surface water, sediment, and groundwater that will be addressed in a final site-wide ROD. All waste, including soils, debris, and rubble from demolition and remediation activities, will be dispositioned. Final cleanup of ETTP further advances DOE's goal for re-industrialization of the site as a private sector industrial park. With risks reduced, hazards removed, and the environment restored, DOE can transfer usable ETTP building and land assets to the community for redevelopment and reuse. A history center, equipment building, viewing tower, and wayside exhibits will tell the story of the site, honoring its contributions to the nation's defense and energy needs. Approximately 1,214 ha (3,000 acres) of adjoining lands, now the Black Oak Ridge Conservation Easement (BORCE), will be used for conservation and recreational purposes, including green-ways and trail systems. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Endangered species act impacts on office of legacy management activities at the Rocky Flats, Colorado, Site - 15268

The Endangered Species Act was passed by Congress in 1973 to protect and recover imperiled species and the ecosystems they rely on. The Preble's meadow jumping mouse (Preble's mouse, Zapus hudsonius preblei) was discovered living along the streams at the Rocky Flats Site on the Front Range of Colorado, in the early 1990's during baseline ecological monitoring. In 1998, the Preble's mouse was classified as a federally listed threatened species under the Endangered Species Act. As a result, the mouse and its habitat are protected and Section 7 consultation with the US Fish and Wildlife Service (US FWS) is required before activities may be conducted in Preble's mouse habitat. This requirement has the potential to impact Rocky Flats project schedules and costs since approval from US FWS is needed prior to conducting activities. To reduce the need to consult with US FWS for projects on a case-by-case basis, a programmatic approach was taken. A master list of ongoing activities and other potential future activities was developed and evaluated in a Programmatic Biological Assessment (PBA) that was written for site activities. The PBA that was approved in 2004 worked well during closure, but did not address many ongoing, postclosure US DOE Office of Legacy Management activities. As a result, the PBA was rewritten in 2013 to address postclosure routine and project-specific activities. The use of a programmatic approach has reduced the time and costs associated with getting individual US FWS approvals, which has in turn minimized impacts to schedules. The programmatic approach could prove useful for other US DOE sites with federally listed species. (authors)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Monitoring EERE's Recovery Act Portfolio

Performance monitoring of Recovery Act projects within EERE has been an ongoing effort. Project recipients have been reporting technical and financial progress to project officers on a quarterly basis.

Recovery, Act, Recovery Act, ARRA, DOE/GO 102011-3↗
DOE OSTI2019

Structural and pharmacological evaluation of a novel non-nucleoside reverse transcriptase inhibitor as a promising long acting nanoformulation for treating HIV

Combination antiretroviral therapy (cART) has been proven effective in inhibiting human immunodeficiency virus type 1 (HIV-1) infection and has significantly improved the health outcomes in acquired immune deficiency syndrome (AIDS) patients. The therapeutic benefits of cART have been challenged because of the toxicity and emergence of drug-resistant HIV-1 strains along with lifelong patient compliance resulting in non-adherence. These issues also hinder the clinical benefits of non-nucleoside reverse transcriptase inhibitors (NNRTIs), which are one of the vital components of cART for the treatment of HIV-1 infection. In this work, using a computational and structural based drug design approach, we have discovered an effective HIV -1 NNRTI, compound I (Cmpd I) that is very potent in biochemical assays and which targets key residues in the allosteric binding pocket of wild-type (WT)-RT as revealed by structural studies. Furthermore, Cmpd I exhibited very potent antiviral activity in HIV-1 infected T cells, lacked cytotoxicity (therapeutic index >100,000), and no significant off-target effects were noted in pharmacological assays. To address the issue of non-adherence, we developed a long-acting nanoformulation of Cmpd I (Cmpd I-NP) using poly (lactide-coglycolide) (PLGA) particles. The pharmacokinetic studies of free and nanoformulated Cmpd I were carried out in BALB/c mice. Intraperitoneal administration of Cmpd I and Cmpd I-NP in BALB/c mice revealed prolonged serum residence time of 48 h and 30 days, respectively. The observed serum concentrations of Cmpd I in both cases were sufficient to provide >97% inhibition in HIV-1 infected T-cells. The significant antiviral activity along with favorable pharmacological and pharmacokinetic profile of Cmpd I, provide compelling and critical support for its further development as an anti-HIV therapeutic agent.

60 APPLIED LIFE SCIENCES↗