An Inclusive Structural Analysis on the Design of 1.2kV 4H-SiC Planar MOSFETs
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Engineering↗
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Large space erectable structures - building block structures study
A modular planar truss structure and a long slender boom concept identified as building block approaches to construction of large spacecraft configurations are described. The concepts are compatible in weight and volume goals with the Space Transportation System, use standard structural units, and represent high on-orbit productivity in terms of structural area or beam length. Results of structural trade studies involving static and dynamic analyses of a single module and rigid body deployment analyses to assess kinetics and kinematics of automatic deployment of the building block modules are presented.
Armstrong, W. H.↗
A Gaussian field approach to the planar electric double layer structures in electrolyte solutions
Here, in this work, the planar, electric, double-layer structures of non-polarizable electrodes in electrolyte solutions are studied with Gaussian field theory. A response function with two Yukawa functions is used to capture the electrostatic response of the electrolyte solution, from which the modified response function in the planar symmetry is derived analytically. The modified response function is further used to evaluate the induced charge density and the electrostatic potential near an electrode. The Gaussian field theory, combined with a two-Yukawa response function, can reproduce the oscillatory decay behavior of the electric potentials in concentrated electrolyte solutions. When the exact sum rules for the bulk electrolyte solutions and the electric double layers are used as constraints to determine the parameters of the response function, the Gaussian field theory could at least partly capture the nonlinear response effect of the surface charge density. Comparison with results for a planar electrode with fixed surface charge densities from molecular simulations demonstrates the validity of Gaussian field theory.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Simplified planar model of ground test verification structure, appendix B
The planar version of the structure is shown for which a model was developed. The model is 12th order including 6 structural modes. One mode results from the base translation, one from the gimbal rotation, three from the flex characteristics of the Astromast Boom and gyro package, and one from the tether and tripod. The model includes one input, one disturbance and one output which are a control torque at the gimbal, a translational force at the base, and the rotation rate of the Astromast tip, respectively.
Source record↗
Normal vector approach to Fourier modal scattering from planar periodic photonic structures
Not Available
Davids, Paul S. (ORCID:000000024498799X)↗
Quantum-inspired genetic algorithm for designing planar multilayer photonic structure
Not Available
36 MATERIALS SCIENCE↗
Planar Schottky barrier mixer diodes for space applications at submillimeter wavelengths
Available planar diodes for space-based applications at submillimeter wavelengths have not achieved either the required low junction capacitance or the low series resistance-junction capacitance product. Here, the development of a novel planar diode structure that overcomes both of these difficulties is outlined. The characteristics of these Schottky barrier mixer diodes are presented and electron micrographs are shown. The diode structure will allow planar technology to be extended throughout the submillimeter wavelength range.
Bishop, W. L.↗
Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings
Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.
Grant, Joseph↗
Nanometer scale nonvolatile memory device and method for storing binary and quantum memory states
Example implementations include an electronic memory device with a metallic layer having a first planar crystalline structure, a first encapsulating layer including an encapsulating material having a second planar crystalline structure, and disposed adjacent to a first planar surface of the metallic layer, and a second encapsulating layer including the encapsulating material, and disposed adjacent to a second planar surface of the metallic layer. Example implementations also include a method of depositing graphite crystals onto a substrate to form a gate bottom layer, depositing BN crystals onto the graphite bottom layer to form a BN bottom layer, depositing tungsten ditelluride (WTe2) crystals onto the BN bottom layer to form a metallic layer, depositing the BN crystals onto the BN bottom layer and the metallic layer to form a BN top layer, and depositing the graphite crystals onto the BN top layer to form a gate top layer.
Xiao, Jun↗
Electronic structure and correlations in planar trilayer nickelate Pr 4 Ni 3 O 8
The discovery of superconductivity in planar nickelates raises the question of how the electronic structure and correlations of Ni 1+ compounds compare to those of the Cu 2+ cuprate superconductors. Here, we present an angle-resolved photoemission spectroscopy (ARPES) study of the trilayer nickelate Pr 4 Ni 3 O 8 , revealing a Fermi surface resembling that of the hole-doped cuprates but with critical differences. Specifically, the main portions of the Fermi surface are extremely similar to that of the bilayer cuprates, with an additional piece that can accommodate additional hole doping. We find that the electronic correlations are about twice as strong in the nickelates and are almost k-independent, indicating that they originate from a local effect, likely the Mott interaction, whereas cuprate interactions are somewhat less local. Nevertheless, the nickelates still demonstrate the strange-metal behavior in the electron scattering rates. Understanding the similarities and differences between these two families of strongly correlated superconductors is an important challenge.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Computationally guided synthesis of carbon coated mesoporous silica materials
Mesoporous silica materials (MSMs) are well-suited for biomedical applications due to their unique features, including a large surface area and tunable pore size. To enhance their durability, the small pores in MSMs are filled with carbon precursors and then carbonized to prevent them from interacting with unreacted silicic acid. Here, in this study, we synthesized and healed MSMs using a combination of non-reactive and reactive molecular dynamics (MD) simulations. The non-reactive MD simulation revealed that the self-assembly of Pluronic® L64 polymers in water resulted in nearly 80 % hydrogen bonds between the hydrophilic sections of the micelle and water. In the bond-boosted ReaxFF MD simulations, silicic acid precursors were condensed on the micelle surface, with over 60 % of them leading to the creation of periodic mesoporous silica within the system. Condensation of silicic acid precursors at 300 K with bond-boosting and at 1500 K without it both significantly promoted the polymerization of Si(OH) 4 , with the latter doubling the rate compared to the former. Subsequently, we healed the MSM surface by carbonizing carbon precursors inside an MSM pore. Polyethylene (PE) and high-rank lignite were identified as the most suitable precursors due to their ability to form turbostratic graphene structures. High-rank lignite exhibited the highest carbon conversion ratio to 6-membered rings, closely followed by PE, in the carbon ring formation analysis. Additionally, the production of gases, such as H 2 , increased significantly for PE at both 2200 K and 2600 K, indicating the conversion of a considerable portion of carbon into graphitic or turbostratic structures. The carbonization of PE primarily led to the formation of planar (sp 2 ) structures, while sucrose yielded the least planar structures. Finally, we studied the protective blocking of unreacted silicic acid precursor by considering a PET turbostratic graphene structure in a silica mesopore formed at 2600 K. The trajectory analysis showed that the surface of the silica was effectively coated with PET tar, preventing unreacted silicic acid from interacting with the inner silica pore surface. These findings offer valuable insights into the synthesis and carbonization-based healing processes of MSMs, enhancing their potential for various biomedical applications.
36 MATERIALS SCIENCE↗
Derivation of generalized transition/boundary conditions for planar multiple-layer structures
Infinite-order generalized impedance boundary conditions (GIBCs) and generalized sheet transition conditions (GSTCs) for planar multilayer configurations are developed via the Taylor series expansion method. The conditions are derived in a matrix product form where each matrix corresponds to a specific layer. An overall composite boundary/transition condition is obtained by making finite-order approximations to the elements of each matrix for the cases of 'low-contrast' and 'high-contrast' material layers. The accuracy of the truncated boundary conditions is examined by comparing their implied reflection and transmission coefficients with the corresponding exact coefficients. Design curves are also given which relate the maximum order of the conditions required to simulate a coating or layer of specific thickness and contrast. Expressions are then derived for the reflection and transmission coefficients of the GIBC/GSTC sheets, and these are compared to exact coefficients to demonstrate the validity of the derived GIBCs/GSTCs.
Ricoy, M. A.↗
Multipoint observations of planar interplanetary magnetic field structures
IMF data made on November 1, 1984, by three spatially well-separated spacecraft in the solar wind are presented. The IMF measured by each of the spacecraft is found to consist of a multiplicity of structures within which the magnetic field varies in parallel planes. The orientations of these planes at the three spacecraft locations are similar. The planes are inclined at a large angle to the ecliptic, and they lie almost perpendicular to the nominal Parker spiral direction in the ecliptic. Intercomparisons of the measurements at the various spacecraft show that the IMF features at one spacecraft are clearly reproduced at another, with time delays required for signal propagation. From these time delays and the mutual separations of the spacecraft, it is inferred that the structures are convecting with the ambient flow. Simultaneous observations made downstream of the bow shock in the magnetosheath reveal that the magnetosheath magnetic field, too, is planar.
Farrugia, C. J.↗
OLEDs on planarized light outcoupling-enhancing structures in plastic
Light extraction from OLEDs remains a challenge. While consumer demand for OLEDs in display technology continues to grow as prices decline, commercial use of OLEDs in solid state lighting (SSL) applications is lagging due to low light extraction, which results in low efficiency. Previous studies have been directed toward increasing the light extraction factor η out , but cost effective approaches that will enable high throughput and potential upscaling, as well as elucidation of the extraction process, are still lagging. One promising approach is the use of buried light extraction enhancing patterns that are planarized with a high refractive index (RI) layer. When adding substrate mode extracting means, the highest external quantum efficiencies (EQEs) were achieved using a complex approach of planarized vacuum nano holes. Here we present η out -enhancing planarized extraction structures (PES) in plastic. While plastic substrates currently present long-term stability issues and other drawbacks, as we show, they provide a tool for simple, inexpensive, and rapid generation of various enhancing structures that importantly can be transferred to the preferred rigid and flexible glass substrates. Moreover, plastic substrates are attractive for biomedical applications. The successful structures we present are easily scalable periodic corrugations, e.g., with pitch a ~ 4.25 µm and pitch/depth ratio a/h ~2.4 planarized by a layer of RI ~1.9, resulting in maximal EQEs exceeding 60% for a green OLED and 48.5% for a white OLED. Comparable increased EQEs were achieved for structures with a ~ 15 and 16 µm, and a/h ~ 2.1 and 4, respectively. Enhanced extraction was also observed with a very simply fabricated quasiperiodic nanohole array, and surprisingly, with a random shallow design. The latter is at variance with simulations based on diffraction only. Results are discussed in terms of a, h, and structural parameters together with scattering matrix simulations to assess the effect of various PES parameters and the nanoparticle-embedded planarizing layer on η out . The experiments and simulations indicate contributions of diffraction, reflection, and scattering to EQE enhancement.
36 MATERIALS SCIENCE↗
Microstructural effects on the room and elevated temperature low cycle fatigue behavior of Waspaloy
Longitudinal specimens of Waspaloy containing either coarse grains with small gamma or fine grains with large gamma were tested in air at a frequency of 0.33 Hz or 0.50 Hz. The coarse grained structures exhibited planar slip on (III) planes and precipitate shearing at all temperatures. Cracks initiated by a Stage 1 mechanism and propagated by a striation forming mechanism. At 700 C and 800 C, cleavage and intergranular cracking were observed. Testing at 500 C, 700 C, and 800 C caused precipitation of grain boundary carbides. At 700 C, carbides precipitated on slip bands. The fine grained structures exhibited planar slip on (111) planes. Dislocations looped the large gamma precipitates. This structure led to stress saturation and propagation was observed. Increasing temperatures resulted in increased specimen oxidation for both heat treatments. Slip band and grain boundary oxidation were observed. At 800 C, oxidized grain boundaries were cracked by intersecting slip bands which resulted in intergranular failure. The fine specimens had crack initiation later in the fatigue life, but with more rapid propagation crack propagation.
Lerch, B. A.↗
Test Methodology Development for Experimental Structural Assessment of ASC Planar Spring Material for Long-Term Durability
A vibration-based testing methodology has been developed that will assess fatigue behavior of the metallic material of construction for the Advanced Stirling Convertor displacer (planar) spring component. To minimize the testing duration, the test setup is designed for base-excitation of a multiplespecimen arrangement, driven in a high-frequency resonant mode; this allows completion of fatigue testing in an accelerated period. A high performance electro-dynamic exciter (shaker) is used to generate harmonic oscillation of cantilever beam specimens, which are clasped on the shaker armature with specially-designed clamp fixtures. The shaker operates in closed-loop control with dynamic specimen response feedback provided by a scanning laser vibrometer. A test coordinator function synchronizes the shaker controller and the laser vibrometer to complete the closed-loop scheme. The test coordinator also monitors structural health of the test specimens throughout the test period, recognizing any change in specimen dynamic behavior. As this may be due to fatigue crack initiation, the test coordinator terminates test progression and then acquires test data in an orderly manner. Design of the specimen and fixture geometry was completed by finite element analysis such that peak stress does not occur at the clamping fixture attachment points. Experimental stress evaluation was conducted to verify the specimen stress predictions. A successful application of the experimental methodology was demonstrated by validation tests with carbon steel specimens subjected to fully-reversed bending stress; high-cycle fatigue failures were induced in such specimens using higher-than-prototypical stresses
fatigue testing machines↗
Investigation of Strain/Vorticity and Large-Scale Flow Structure in Turbulent Nonpremixed Jet Flames
Our study will use the microgravity environment to investigate the underlying flow structure of turbulent nonpremixed round jet flames. In particular, we aim to investigate the large-scale turbulent structure using planar laser Mie scattering (PLMS), and the strain rate and vorticity fields using particle image velocimetry (PIV). This work is motivated by recent studies in our laboratory that have led to several interesting observations of nominally momentum-driven turbulent nonpremixed planar flames. First of all, the organized large-scale turbulent structures that are observed in nonreacting planar jets may be substantially modified or suppressed in nonpremixed planar jet flames. Furthermore, a recent study using PIV and planar laser-induced fluorescence of OH has shown that in transitional and turbulent nonpremixed planar jet flames the presence of the flame seems to greatly influence the underlying vorticity and strain fields, as compared to nonreacting jets. For example, the reaction zones in the jet flames are strongly correlated with regions of high vorticity. A related study has demonstrated that vorticity is not correlated in the same way with either iso-scalar surfaces or scalar dissipation layers in nonreacting planar jets. Furthermore, the relationship between strain and the reaction zone appears to be modified by the presence of high levels of heat release. In particular, the strain rate field in planar jet flames exhibits a preferred direction of principal compressive strain that apparently is related to strong shear across the reaction zone. This preferred direction of strain was not observed in nonreacting jets. One of the major problems encountered when conducting these types of studies is that it is difficult to know to what extent buoyancy influences the results. Therefore, the microgravity environment provides us with an excellent opportunity to explore these issues without the complicating effects of buoyancy. This is particularly the case when studying flames that are transitional between laminar and turbulent states. For example, the strong correlation of vorticity with the reaction zone (discussed above) was observed in both transitional and turbulent planar flames, but the effect was stronger for the transitional case. To date, the reason for the presence of the vorticity-reaction zone correlation is not known, although vorticity production via baroclinic torque is a likely cause. The microgravity environment will allow us to specifically determine whether the vorticity is produced by baroclinic torque resulting from the flame density gradient acting with the hydrostatic pressure gradient.AAdditional details of the planned experiments are provided.
Clemens, N. T.↗
Effect of trifunctional planar monomer on the structure and properties of polyamide membranes
Not Available
Zhao, Lianrui↗