Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Window”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Sci—Thur PM: Imaging — 04: An iterative triple energy window (TEW) approach to cross talk correction in quantitative small animal Tc99m and In111 SPECT

Dual isotope SPECT allows simultaneous measurement of two different tracers in vivo. With In111 (emission energies of 171keV and 245keV) and Tc99m (140keV), quantification of Tc99m is degraded by cross talk from the In111 photons that scatter and are detected at an energy corresponding to Tc99m. TEW uses counts recorded in two narrow windows surrounding the Tc99m primary window to estimate scatter. Iterative TEW corrects for the bias introduced into the TEW estimate resulting from un-scattered counts detected in the scatter windows. The contamination in the scatter windows is iteratively estimated and subtracted as a fraction of the scatter-corrected primary window counts. The iterative TEW approach was validated with a small-animal SPECT/CT camera using a 2.5mL plastic container holding thoroughly mixed Tc99m/In111 activity fractions of 0.15, 0.28, 0.52, 0.99, 2.47 and 6.90. Dose calibrator measurements were the gold standard. Uncorrected for scatter, the Tc99m activity was over-estimated by as much as 80%. Unmodified TEW underestimated the Tc99m activity by 13%. With iterative TEW corrections applied in projection space, the Tc99m activity was estimated within 5% of truth across all activity fractions above 0.15. This is an improvement over the non-iterative TEW, which could not sufficiently correct for scatter in the 0.15 and 0.28 phantoms.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Low RF Loss DC Conductive Ceramic for High Power Input Coupler Windows for SRF Cavities

Euclid Techlabs, LLC is developing a low RF loss/DC conductive MgTi ceramics for high power input coupler windows for SRF cavities, under DOE SBIR phase II grant DE-SC0017150. JLab was subcontracted to: fabricate two 500 kW capable pre-stressed coaxial windows; provide an RF testing fixture, and test the window with low power and high power RF. This collaboration helped to develop a better material for high power RF windows, with low RF loss and less prone to arcing, with the potential to improve the state of the art high power RF window performance.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Thermally Insulating Transparent Barrier (THINNER) coatings on single pane windows

Conventional silica aerogel monoliths can provide remarkable thermal insulation but the presence of large pores (> 30 nm) tends to scatter visible light and render the material opaque or translucent instead of transparent. In addition, they are prone to cracking during synthesis and handling which makes them difficult to integrate in products and in particular in window solutions. This project developed two new solgel synthesis methods using silica precursors or preformed silica nanoparticles and ambient drying to produce mesoporous organo-silica monoliths. The monoliths were (i) thermally insulating, (ii) optically transparent, (iii) flexible, and (iv) hydrophobic. They feature porosity ranging from 50% to 90% with narrow pore size distribution with pore less than 20 nm resulting in excellent optical clarity (haze < 2%) and very low thermal conductivity (< 30 mW/mK). Interestingly, not only porosity but also pore size and mass fractal dimension were found to affect the thermal conductivity of the mesoporous silica. The superior transparency of the monoliths was shown to be attributed to dependent scattering among silica nanoparticles. Flexibility was achieved through trimethylchlorosilane surface modification. Furthermore, process scale-up and integration of the ambigel monoliths into window solutions using optically clear adhesives were also demonstrated in 6”x6” double-pane windows. The aerogel and the window solution were shown to be durable to accelerated aging under UV, moisture, and/or temperature gradient and thermal cycling. Overall, the window solution achieved the technical performance and the cost target of $10/sqft set for the SHIELD program. However, scaling to industry relevant scale (> 10’x10’) remains a challenge due to requirements on the drying process and fume hood size and to the propensity of large aerogel slab to crack during drying.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Development of Wireless Power Technology for Use in Electrochromic Window Retrofit Applications

Electrochromic (EC) windows, often referred to as smart windows, have the ability to adjust their tint in response to electrical signals, thereby controlling the amount of sunlight and heat entering a building. This dynamic modulation can lead to significant energy savings by reducing the reliance on artificial lighting and minimizing the load on heating, ventilation, and air conditioning (HVAC) systems. However, the widespread adoption of electrochromic window technology, especially in existing buildings, faces challenges, particularly concerning the installation cost associated with the need for electrical wiring to power and control the EC glass (tinting). In this project, GuRu Wireless demonstrated that it’s mmWave-based wireless power energy transfer technology can provide the necessary power for operation of electrochromic windows, wirelessly, and address the wiring challenges of electrochromic windows in retrofit applications.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1971

Development of a collapsible reinforced cylindrical space observation window

Existing material technology was applied to the development of a collapsible transparent window suitable for manned spacecraft structures. The effort reported encompasses the evaluation of flame retardants intended for use in the window matrix polymer, evaluation of reinforcement angle which would allow for a twisting pantographing motion as the cylindrical window is mechanically collapsed upon itself, and evaluation of several reinforcement embedment methods. A fabrication technique was developed to produce a reinforced cylindrical space window of 45.7 cm diameter and 61.0 cm length. The basic technique involved the application of a clear film on a male-section mold; winding axial and girth reinforcements and vacuum casting the outer layer. The high-strength transparent window composite consisted of a polyether urethane matrix reinforced with an orthogonal pattern of black-coated carbon steel wire cable. A thin film of RTV silicone rubber was applied to both surfaces of the urethane. The flexibility, retraction system, and installation system are described.

Khan, A. Q.↗
NASA NTRS1972

Establishing an upper bound for window response to the sonic boom.

Study of the failure of glass windows, which is probably the most severe problem confronting the SST program outside of the psychological and sociological aspects. The structural configuration most likely to suffer a window failure due to sonic boom excitation is one representable by a single large room, a single large window, and an open door. It is suggested that if the open door were replaced with another window the resultant stresses in both windows would be substantially reduced.

Seshadri, T. V.↗
NASA NTRS1981

Development of a window protection assembly for a shuttle experiment

A window environmental protection assembly developed for the shuttle infrared leeside temperature experiment is described. The assembly consists of a carbon phenolic composite window mount which contains two silicon windows, a fibrous environmental protection plug to protect the windows during launch operations and ascent heating, a release mechanism used to jettison the plug just prior to atmospheric entry, and two pin puller mechanisms which retain the plug. The plug is released from the window mount assemblies using pneumatic pin pullers and separation springs in the release mechanism. The assembly was designed and tested to withstand the severe mechanical and thermal environments which could be experienced at the top of the shuttle orbiter vertical stabilizer during the ascent, on-orbit, and entry periods of the shuttle trajectory.

Bradley, O. H., Jr.↗
NASA NTRS1983

Study of noise transmission through double wall aircraft windows

Analytical and experimental procedures were used to predict the noise transmitted through double wall windows into the cabin of a twin-engine G/A aircraft. The analytical model was applied to optimize cabin noise through parametric variation of the structural and acoustic parameters. The parametric study includes mass addition, increase in plexiglass thickness, decrease in window size, increase in window cavity depth, depressurization of the space between the two window plates, replacement of the air cavity with a transparent viscoelastic material, change in stiffness of the plexiglass material, and different absorptive materials for the interior walls of the cabin. It was found that increasing the exterior plexiglass thickness and/or decreasing the total window size could achieve the proper amount of noise reduction for this aircraft. The total added weight to the aircraft is then about 25 lbs.

Vaicaitis, R.↗
NASA NTRS1985

Hypervelocity impacts on Skylab 4/Apollo windows

The three largest Skylab 4 Command Module windows that were exposed for 84 days to space were optically scanned for impact features as small as 30 microns in diameter. This scanning effort which was carried out at an opptical magnification of 35x, detected features approximately three times smaller than were found in the original 5x scanning effort over the entire window surface. Some 289 features were recorded from the 35x scan for later detailed analyses. Sixty of the largest and most promising features were cored from the windows for SEM and energy-dispersive X-ray spectrometer (EDS) analysis. Twenty-six of the cores contained craters with glassy pits, and of these, fourteen were found to contain strikingly obvious liners coating the interior of the glassy pit. The six largest features cored from the windows do not have a central glassy pit which leaves their previously reported hypervelocity origin in some doubt. The remaining twenty-eight features that were cored from the windows show no clear evidence for a hypervelocity origin and evidence available at this time is insufficient to identify an origin in Earth orbit or as ground damage. The EDS analysis of six of the seven liners that were examined show detectable aluminum in the liner or lip of the glassy pit. The source of aluminum is most probably an Earth orbiting population of aluminum oxide spherules, exhaust from solid rocket motors.

Clanton, U. S.↗
NASA NTRS1986

"Curtainless" Window

Liquid flow switches window from transparency to opacity. Pump transfers liquid from reservoir to window voids. Gas-venting pipe transfers gas to reservoir when window is filling and to window when window is emptying.

Connelly, D. L.↗
NASA NTRS1988

Space station proximity operations and window design

On-orbit proximity operations (PROX-OPS) consist of all extravehicular activity (EVA) within 1 km of the space station. Because of the potentially large variety of PROX-OPS, very careful planning for space station windows is called for and must consider a great many human factors. The following topics are discussed: (1) basic window design philosophy and assumptions; (2) the concept of the local horizontal - local vertical on-orbit; (3) window linear dimensions; (4) selected anthropomorphic considerations; (5) displays and controls relative to windows; and (6) full window assembly replacement.

Haines, Richard F.↗
NASA NTRS1987

Space station proximity operations windows: Human factors design guidelines

Proximity operations refers to all activities outside the Space Station which take place within a 1-km radius. Since there will be a large number of different operations involving manned and unmanned vehicles, single- and multiperson crews, automated and manually controlled flight, a wide variety of cargo, and construction/repair activities, accurate and continuous human monitoring of these operations from a specially designed control station on Space Station will be required. Total situational awareness will be required. This paper presents numerous human factors design guidelines and related background information for control windows which will support proximity operations. Separate sections deal with natural and artificial illumination geometry; all basic rendezvous vector approaches; window field-of-view requirements; window size; shape and placement criteria; window optical characteristics as they relate to human perception; maintenance and protection issues; and a comprehensive review of windows installed on U.S. and U.S.S.R. manned vehicles.

Haines, Richard F.↗
NASA NTRS1987

Acoustic transmissibility of advanced turboprop aircraft windows

Advanced turboprop technology allows propeller aircraft to reach cruise speeds comparable to current jet aircraft yet with considerable fuel savings. Due to the higher blade loading and higher tip speed of these propellers, noise levels of up to 150 dB are expected on the outside of the fuselage in the propeller plane. In this study the transmissibility of triple pane windows, designed to provide 69 dB noise transmission loss at the blade propeller frequency of 164 Hz, was experimentally investigated using insertion loss and three-dimensional intensity techniques. A modal analysis on the outer window panes was conducted to determine pane modal frequencies. Coherence and phase relation of outer panes and window frame were established to obtain double/triple wall and lump mass resonance frequencies. Double/triple wall resonances were found to degrade the transmission loss of the two windows. It was shown that, at the blade passage frequency and the first two overtones, the combinations of window plus scratch shield provide less transmission loss than the average transmission loss of the treated fuselage. Strong disagreement was obtained between the experimental transmission loss of this investigation and the theoretical predictions from another study.

Grosveld, Ferdinand W.↗
NASA NTRS1988

Fabrication of MgF2 and LiF windows for the Hubble Space Telescope Imaging Spectrograph

Two prototype test windows (MgF2 and LiF) to be used on the 75-mm UV MAMA detector tubes for the Hubble Space Telescope Imaging Spectrograph are described. The spatial and optical constraints of this instrument dictate that the thickness of the window materials be no greater than 2-3 mm to achieve a minimum 50-percent transmission at hydrogen Lyman alpha (121.6 nm), and that the window must be domed to minimize optical aberrations and provide structural strength. The detector window has an input diameter of about 100 mm with a radius-of-curvature of 70 mm. The manufacturing processes involved in the fabrication of these windows is discussed, as well as test programs (optical and structural) to be performed at Goddard Space Flight Center.

Gormley, Daphne↗
NASA NTRS1992

Three-dimensional laser window formation

The NASA Lewis Research Center has developed and implemented a unique process for forming flawless three-dimensional laser windows. These windows represent a major part of specialized, nonintrusive laser data acquisition systems used in a variety of compressor and turbine research test facilities. This report discusses in detail the aspects of three-dimensional laser window formation. It focuses on the unique methodology and the peculiarities associated with the formation of these windows. Included in this discussion are the design criteria, bonding mediums, and evaluation testing for three-dimensional laser windows.

Verhoff, Vincent G.↗
NASA NTRS1993

High performance sapphire windows

High-quality, wide-aperture optical access is usually required for the advanced laser diagnostics that can now make a wide variety of non-intrusive measurements of combustion processes. Specially processed and mounted sapphire windows are proposed to provide this optical access to extreme environment. Through surface treatments and proper thermal stress design, single crystal sapphire can be a mechanically equivalent replacement for high strength steel. A prototype sapphire window and mounting system have been developed in a successful NASA SBIR Phase 1 project. A large and reliable increase in sapphire design strength (as much as 10x) has been achieved, and the initial specifications necessary for these gains have been defined. Failure testing of small windows has conclusively demonstrated the increased sapphire strength, indicating that a nearly flawless surface polish is the primary cause of strengthening, while an unusual mounting arrangement also significantly contributes to a larger effective strength. Phase 2 work will complete specification and demonstration of these windows, and will fabricate a set for use at NASA. The enhanced capabilities of these high performance sapphire windows will lead to many diagnostic capabilities not previously possible, as well as new applications for sapphire.

Bates, Stephen C.↗
NASA NTRS1993

Compound curvature laser window development

The NASA Lewis Research Center has developed and implemented a unique process for forming flawless compound curvature laser windows. These windows represent a major part of specialized, nonintrusive laser data acquisition systems used in a variety of compressor and turbine research test facilities. This report summarizes the main aspects of compound curvature laser window development. It is an overview of the methodology and the peculiarities associated with the formulation of these windows. Included in this discussion is new information regarding procedures for compound curvature laser window development.

Verhoff, Vincent G.↗
NASA NTRS1993

Effects of window size and shape on accuracy of subpixel centroid estimation of target images

A new algorithm is presented for increasing the accuracy of subpixel centroid estimation of (nearly) point target images in cases where the signal-to-noise ratio is low and the signal amplitude and shape vary from frame to frame. In the algorithm, the centroid is calculated over a data window that is matched in width to the image distribution. Fourier analysis is used to explain the dependency of the centroid estimate on the size of the data window, and simulation and experimental results are presented which demonstrate the effects of window size for two different noise models. The effects of window shape were also investigated for uniform and Gaussian-shaped windows. The new algorithm was developed to improve the dynamic range of a close-range photogrammetric tracking system that provides feedback for control of a large gap magnetic suspension system (LGMSS).

Welch, Sharon S.↗