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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 1,387 records · Page 77

All sources NASA NTRS DOE OSTI

DOE OSTI2011

Design of Low-Noise Output Amplifiers for P-channel Charge-Coupled Devices Fabricated on High-Resistivity Silicon

We describe the design and optimization of low-noise, single-stage output amplifiers for p-channel charge-coupled devices (CCDs) used for scientific applications in astronomy and other fields. The CCDs are fabricated on high-resistivity, 4000–5000 -cm, n-type silicon substrates. Single-stage amplifiers with different output structure designs and technologies have been characterized. The standard output amplifier is designed with an n{sup +} polysilicon gate that has a metal connection to the sense node. In an effort to lower the output amplifier readout noise by minimizing the capacitance seen at the sense node, buried-contact technology has been investigated. In this case, the output transistor has a p{sup +} polysilicon gate that connects directly to the p{sup +} sense node. Output structures with buried-contact areas as small as 2 μm × 2 μm are characterized. In addition, the geometry of the source-follower transistor was varied, and we report test results on the conversion gain and noise of the various amplifier structures. By use of buried-contact technology, better amplifier geometry, optimization of the amplifier biases and improvements in the test electronics design, we obtain a 45% reduction in noise, corresponding to 1.7 e{sup -} rms at 70 kpixels/sec.

42 ENGINEERING↗

DOE OSTI2014

Synergetic effects of II-VI sensitization upon TiO{sub 2} for photoelectrochemical water splitting; a tri-layered structured scheme

World's energy demands are growing on a higher scale increasing the need of more reliable and long term renewable energy resources. Efficient photo-electrochemical (PEC) devices based on novel nano-structured designs for solar-hydrogen generation need to be developed. This study provides an insight of the tri-layered-TiO2 based nanostructures. Observing the mechanism of hydrogen production, the comparison of the structural order during the synthesis is pronounced. The sequence in the tri-layered structure affects the photogenerated electron (e{sup −}) and hole (h{sup +}) pair transfer and separation. It is also discussed that not only the semiconductors band gaps alignment is important with respect to the water redox potential but also the interfacial regions. Quasi-Fermi-level adjustment at the interfacial regions plays a key role in deciding the solar to hydrogen efficiency. More efficient multicomponent semiconductor nano-design (MCSN) could be developed with the approach given in this study.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1966

Solar cell submodule design facilitates assembly of lightweight arrays

Solar cell submodules with bus bars that leave tabs along one end of the submodule and wires with raised portions along the other end are assembled by interlocking the tabs and wires of adjacent submodules. This structural design is lightweight and reliable and requires no metallic substructure.

Yasui, R. K.↗

DOE OSTI2014

Peppytides: Interactive Models of Polypeptide Chains

Peppytides are scaled, 3D-printed models of polypeptide chains that can be folded into accurate protein structures. Designed and created by Berkeley Lab Researcher, Promita Chakraborty, and Berkeley Lab Senior Scientist, Dr. Ron Zuckermann, Peppytides are accurate physical models of polypeptide chains that anyone can interact with and fold intro various protein structures - proving to be a great educational tool, resulting in a deeper understanding of these fascinating structures and how they function. Build your own Peppytide model and learn about how nature's machines fold into their intricate architectures!

3D PRINTING↗

DOE OSTI2022

Modeling and implementation of vertical excursion FFA in the Zgoubi ray-tracing code

Vertical Fixed Field Accelerators (vFFAs) feature complex and highly non-linear magnetic fields, which require simulation codes allowing step-wise particle tracking. Methods to model the 3D magnetic field of scaling vFFAs have been developed in the ray-tracing code Zgoubi. The field modeling and particle tracking methods include the field non-linearities, the fringe fields, and the field superposition of neighboring magnets. The procedure implements the vFFA analytical field expressions, allowing design studies and parameter optimizations using the Zgoubi built-in fit method. The vFFA procedure has been applied to a ten-fold symmetry ring with a triplet focusing structure designed to accelerate protons from 3 MeV to 12 MeV and studied under the ISIS-II proton driver prototype project. Results from particle tracking in externally generated 3D semi-analytical field maps and the developed vFFA analytical model are shown to be in excellent agreement.

43 PARTICLE ACCELERATORS↗

DOE OSTI2011

Photonic density of states of two-dimensional quasicrystalline photonic structures

A large photonic band gap (PBG) is highly favorable for photonic crystal devices. One of the most important goals of PBG materials research is identifying structural design strategies for maximizing the gap size. We provide a comprehensive analysis of the PBG properties of two-dimensional (2D) quasicrystals (QCs), where rotational symmetry, dielectric fill factor, and structural morphology were varied systematically in order to identify correlations between structure and PBG width at a given dielectric contrast (13:1, Si:air). The transverse electric (TE) and transverse magnetic (TM) PBGs of 12 types of QCs are investigated (588 structures). We discovered a 12mm QC with a 56.5% TE PBG, the largest reported TE PBG for an aperiodic crystal to date. We also report here a QC morphology comprising ''throwing star''-like dielectric domains, with near-circular air cores and interconnecting veins emanating radially around the core. This interesting morphology leads to a complete PBG of {approx}20% , which is the largest reported complete PBG for aperiodic crystals.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1972

Composites - Lighter and cheaper.

Composite engineering materials have two distinct parts, including the load-bearing filaments and the matrix. Fibers can range from glass to boron and graphite. Matrix constituents include epoxies for lower temperatures and metals for higher temperatures. Composites appear as tape or combined with metal in structural shapes. The increased use of composites will reduce over-all per pound manufacturing costs. Two major deterrents to further application of composites in advanced commercial transports include a shortage of cost-effective structural design concepts and a lack of confidence in the life characteristics. A program has been outlined by NASA that will, if implemented, provide considerable in-service life experience with structural components on commercial transports.

Goble, R. L.↗

NASA NTRS1972

Preliminary shuttle structural dynamics modeling design study

The design and development of a structural dynamics model of the space shuttle are discussed. The model provides for early study of structural dynamics problems, permits evaluation of the accuracy of the structural and hydroelastic analysis methods used on test vehicles, and provides for efficiently evaluating potential cost savings in structural dynamic testing techniques. The discussion is developed around the modes in which major input forces and responses occur and the significant structural details in these modes.

Source record↗

NASA NTRS1983

Energy Efficient Engine Flight Propulsion System Preliminary Analysis and Design Report

The final design and analysis of the flight propulsion system is presented. This system is the conceptual study engine defined to meet the performance, economic and environmental goals established for the Energy Efficient Engine Program. The design effort included a final definition of the engine, major components, internal subsystems, and nacelle. Various analytical representations and results from component technology programs are used to verify aerodynamic and structural design concepts and to predict performance. Specific design goals and specifications, reflecting future commercial aircraft propulsion system requirements for the mid-1980's, are detailed by NASA and used as guidelines during engine definition. Information is also included which details salient results from a separate study to define a turbofan propulsion system, known as the maximum efficiency engine, which reoptimized the advanced fuel saving technologies for improved fuel economy and direct operating costs relative to the flight propulsion system.

Bisset, J. W.↗

NASA NTRS2001

Simulation of Aircraft Engine Blade-Out Structural Dynamics

A primary concern of aircraft structure designers is the accurate simulation of the blade-out event and the subsequent windmilling of the engine. Reliable simulations of the blade-out event are required to insure structural integrity during flight as well as to guarantee successful blade-out certification testing. The system simulation includes the lost blade loadings and the interactions between the rotating turbomachinery and the remaining aircraft structural components. General-purpose finite element structural analysis codes such as MSC NASTRAN are typically used and special provisions are made to include transient effects from the blade loss and rotational effects resulting from the engine's turbomachinery. The present study provides the equations of motion for rotordynamic response including the effect of spooldown speed and rotor unbalance and examines the effects of these terms on a cantilevered rotor. The effect of spooldown speed is found to be greater with increasing spooldown rate. The parametric term resulting from the mass unbalance has a more significant effect on the rotordynamic response than does the spooldown term. The parametric term affects both the peak amplitudes as well as the resonant frequencies of the rotor.

Lawrence, Charles↗

NASA NTRS2001

Simulation of Aircraft Engine Blade-Out Structural Dynamics

Lawrence, Charles↗

NASA NTRS2003

Efficient, Low-Cost Fan System Research for General Aviation and Commuter Aircraft

This document reports research investigations into efficient, low-cost fan system concepts for high bypass turbofans for future general aviation and commuter aircraft. The research specifically addressed lower pressure ratio fans for good propulsive efficiencies in the 200 to 400 knot flight speed regime. Aerodynamic design analyses yielded predicted efficiency in area of 91 to 92 percent (adiabatic). Low-cost manufacturing studies yielded an aluminum blisk rotor and investment cast stator having lowest cost. Structural design analyses yielded a design having excellent vibratory characteristics and the ability to pass One- and Four-pound bird strikes satisfactorily. The low speed and low pressure fans of the study are estimated to have 24 to 30 EPNdB lower community noise levels than larger, high pressure ratio transonic fans.

Merrill, G. L.↗

NASA NTRS2016

Mechanical Design and Development of TES Bolometer Detector Arrays for the Advanced ACTPol Experiment

The next generation Advanced ACTPol (AdvACT) experiment is currently underway and will consist of four Transition Edge Sensor (TES) bolometer arrays, with three operating together, totaling 5800 detectors on the sky. Building on experience gained with the ACTPol detector arrays, AdvACT will utilize various new technologies, including 150 mm detector wafers equipped with multichroic pixels, allowing for a more densely packed focal plane. Each set of detectors includes a feedhorn array of stacked silicon wafers which form a spline pro le leading to each pixel. This is then followed by a waveguide interface plate, detector wafer, back short cavity plate, and backshort cap. Each array is housed in a custom designed structure manufactured from high purity copper and then gold plated. In addition to the detector array assembly, the array package also encloses cryogenic readout electronics. We present the full mechanical design of the AdvACT high frequency (HF) detector array package along with a detailed look at the detector array stack assemblies. This experiment will also make use of extensive hardware and software previously developed for ACT, which will be modi ed to incorporate the new AdvACT instruments. Therefore, we discuss the integration of all AdvACT arrays with pre-existing ACTPol infrastructure.

Advanced ACTPol (AdvACT)↗

NASA NTRS1994

A method for the probabilistic design assessment of composite structures

A formal procedure for the probabilistic design assessment of a composite structure is described. The uncertainties in all aspects of a composite structure (constituent material properties, fabrication variables, structural geometry, service environments, etc.), which result in the uncertain behavior in the composite structural responses, are included in the assessment. The probabilistic assessment consists of design criteria, modeling of composite structures and uncertainties, simulation methods, and the decision making process. A sample case is presented to illustrate the formal procedure and to demonstrate that composite structural designs can be probabilistically assessed with accuracy and efficiency.

Shiao, Michael C.↗

NASA NTRS1991

Technology needs for high speed rotorcraft (2)

An analytical study was conducted to identify rotorcraft concepts best capable of combining a cruise speed of 350 to 450 knots with helicopter-like low speed attributes, and to define the technology advancements needed to make them viable by the year 2000. A systematic approach was used to compare the relative attributes and mission gross weights for a wide range of concepts, resulting in a downselect to the most promising concept/mission pairs. For transport missions, tilt-wing and variable diameter tilt-rotor (VDTR) concepts were found to be superior. For a military scout/attack role, the VDTR was best, although a shrouded rotor concept could provide a highly agile, low observable alternative if its weight empty fraction could be reduced. A design speed of 375 to 425 knots was found to be the maximum desirable for transport missions, with higher speed producing rapidly diminishing benefits in productivity. The key technologies that require advancement to make the tilt-wing and VDTR concepts viable are in the areas of wing and proprotor aerodynamics, efficient structural design, flight controls, refinement of the geared flap pitch control system, expansion of the speed/descent envelope, and the structural and aerodynamic tradeoffs of wing thickness and forward sweep. For the shrouded rotor, weight reduction is essential, particularly with respect to the mechanism for covering the rotor in cruise.

Scott, Mark W.↗

DOE OSTI2019

Designing and transforming yield-stress fluids

We review progress in designing and transforming multi-functional yield-stress fluids and give a perspective on the current state of knowledge that supports each step in the design process. We focus mainly on the rheological properties that make yield-stress fluids so useful and the trade-offs which need to be considered when working with these materials. Thinking in terms of "design with" and "design of' yield-stress fluids motivates how we can organize our scientific understanding of this field. "Design with" involves identification of rheological property requirements independent of the chemical formulation, e.g. for 3D direct-write printing which needs to accommodate a wide range of chemistry and material structures. "Design of includes microstructural considerations: conceptual models relating formulation to properties, quantitative models of formulation-structureproperty relations, and chemical transformation strategies for converting effective yield-stress fluids to be more useful solid engineering materials. Finally, future research directions are suggested at the intersection of chemistry, soft-matter physics, and material science in the context of our desire to design useful Theologically-complex functional materials.

36 MATERIALS SCIENCE↗

DOE OSTI2014

Forced diffusion via electrically induced crystallization for fabricating ZnO–Ti–Si structures

Highlights: • ZnO–Ti–Si system is very important for the structural design. • The electrically induced crystallization method is useful to diffusion process. • Intermetallic compound characteristics have been presented using electrically induced crystallization. • Interface mechanism about diffusion of TZO–TiSi{sub x}–Si structure is presented. - Abstract: Electrically induced crystallization (EIC) is a recently developed process for material modification. This study is applied to EIC to fabricate ZnO–Ti–Si multi-layer structures of various thicknesses to dope Ti into ZnO thin film and to form TiSi{sub x} intermetallic compound (IMC) in a single step. The IMC layer was confirmed using transmission electron microscopy images. The Ti layer thickness was more than 40 nm, which enhanced electron transmission and decreased the total electrical resistance in the structure. Finally, the diffusion mechanisms of EIC and the annealing process were investigated. This study shows that the EIC process has potential for industrial applications.

36 MATERIALS SCIENCE↗

NASA NTRS1975

Redesigned rotor for a highly loaded, 1800 ft/sec tip speed compressor fan stage 1: Aerodynamic and mechanical design

A highly loaded, high tip-speed fan rotor was designed with multiple-circular-arc airfoil sections as a replacement for a marginally successful rotor which had precompression airfoil sections. The substitution of airfoil sections was the only aerodynamic change. Structural design of the redesigned rotor blade was guided by successful experience with the original blade. Calculated stress levels and stability parameters for the redesigned rotor are within limits demonstrated in tests of the original rotor.

Halle, J. E.↗