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Three dimensional pressure distribution functions for lifting surfaces with trailing-edge controls based on integral equations for subsonic flow
Based on expressions for the linearized velocity potentials and pressure distributions given in NACA Technical Report 1268, formulas for the span load distribution, forces, and moments are derived for families of thin isolated vertical tails with arbitrary aspect ratio, taper ratio, and sweepback performing the motions constant sideslip, steady rolling, steady yawing, and constant lateral acceleration. The range of Mach number considered corresponds, in general, to the condition that the tail leading and trailing edges are supersonic. To supplement the analytical results, design-type charts are presented which enable rapid estimation of the forces and moments (expressed as stability derivatives) for given combinations of geometry parameters and Mach number.
Construction of leading edges of surfaces for aerial vehicles performing from subsonic to above transonic speeds
Electrothermal feedback in a transition edge sensor suppresses thermal fluctuations in the TES and regions in close thermal contact. We designed a heavily-metallized, leg-isolated membrane with a TES which serves as a thermal stabilization stage that can be lithographically integrated with other devices. Through modeling, fabrication and test of prototype devices, we examine whether the noise reduction in this stage can reduce thermal fluctuations (e.g. 1/f noise) in the other components by providing a more stable base temperature. In one implementation, a leg-isolated TES bolometer of higher superconducting transition temperature (Tc) is encircled by a second membrane region which is metallized and thermally stabilized by a second, lower-Tc TES. We present fabrication results on the dual-Tc design and testing of the simultaneous biasing of a two-stage, two-TES device. We explore varied heat capacity of the thermally stabilized stage in the single pixel design. We also present other designs to evaluate the use of an outer thermal stabilization stage for multiple pixel arrangements.
We examine the magnetic structure and dynamics of multiple jets found in coronal holes close to or on disk center. All data are from the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory (SDO). We report on observations of about ten jets in an equatorial coronal hole spanning 2011 February 27 and 28. We show the evolution of these jets in AIA 193 A, examine the magnetic field configuration and flux changes in the jet area, and discuss the probable trigger mechanism of these events. We reported on another jet in this same coronal hole on 2011 February 27, (is) approximately 13:04 UT (Adams et al 2014, ApJ, 783: 11). That jet is a previously-unrecognized variety of blowout jet, in which the base-edge bright point is a miniature filament-eruption flare arcade made by internal reconnection of the legs of the erupting field. In contrast, in the presently-accepted 'standard' picture for blowout jets, the base-edge bright point is made by interchange reconnection of initially-closed erupting jet-base field with ambient open field. This poster presents further evidence of the production of the base-edge bright point in blowout jets by internal reconnection. Our observations suggest that most of the bigger and brighter EUV jets in coronal holes are blowout jets of the new-found variety.
We have successfully fabricated the superconducting transition edge sensor (TES), bolometer technology that centers on the use of electron-phonon decoupling (EPD) to thermally isolate the bolometer. Along with material characterization for large format antenna coupled bolometer arrays, we present the initial test results of bolometer based on EPD designed for THz detection. We have selected a design approach that separates the two functions of photon absorption and temperature measurement, allowing separate optimization of the performance of each element. We have integrated Molybdenum/Gold (Mo/Au) bilayer TES and ion assisted thermally evaporated (IAE) Bismuth (Bi) films as radiation absorber coupled to a low-loss microstripline from Niobium (Nb) ground plane to a twin-slot antenna structure. The thermal conductance and the time constant of these devices have been measured, and are consistent with our calculations. The device exhibits a single time constant at 0.1 K of approx.160 IlS, which is compatible with readout by a high-bandwidth single SQUID or a time domain SQUID multiplexer. The effects of thermal conductance and electrothermal feedback are major determinants of the time constant, but the electronic heat capacity also plays a major role. The NEP achieved in the device described above is 2.5x10(exp -17)W(gamma)Hz. Our plan is to demonstrate a reduction of the volume in the superconducting element to 5 microns x 5 microns in films of half the thickness at Tc = 60mK. By calculation, this new geometry corresponds to an NEP reduction of two orders of magnitude to 2.5x10(exp -19)W/(gamma)Hz, with a time constant of ~130/ls.
We have successfully fabricated a superconducting transition edge sensor (TES), bolometer that centers on the use of electron-phonon decoupling (EPD) for thermal isolation. We have selected a design approach that separates the two functions of far-infrared and THz radiative power absorption and temperature measurement, allowing separate optimization of the performance of each element. We have integrated molybdenum/gold (Mo/Au) bilayer TES and ion assisted thermally evaporated (IAE) bismuth (Bi) films as radiation absorber coupled to a low-loss microstripline from niobium (Nb) ground plane to a twin-slot antenna structure. The thermal conductance (G) and the time constant for the different geometry device have been measured. For one such device, the measured G is 1.16 x 10(exp -10) W/K (plus or minus 0.61 x 10(exp- 10) W/K) at 60 mK, which corresponds to noise equivalent power (NEP) = 1.65 X 10(exp -18)W/vHz and time constant of approximately 5 microseconds.
A hybrid finite element boundary integral formulation is developed using tetrahedral and/or triangular elements for discretizing the cavity and/or aperture of microstrip antenna arrays. The tetrahedral elements with edge based linear expansion functions are chosen for modeling the volume region and triangular elements are used for discretizing the aperture. The edge based expansion functions are divergenceless thus removing the requirement to introduce a penalty term and the tetrahedral elements permit greater geometrical adaptability than the rectangular bricks. The underlying theory and resulting expressions are discussed in detail together with some numerical scattering examples for comparison and demonstration.
The Line Emission Mapper (or LEM) is an X-ray probe class mission aimed to study the physics of galaxy formation, with a large field-of-view, high-resolution transition-edge sensor (TES) microcalorimeter. Because of the diffuse and faint nature of LEM’s targets, a high-fidelity anticoincidence detector (anti-co) is essential to reduce instrument background below the level of sky background. Lying directly behind the LEM sensor, the anti-co will detect ~3 counts per second per square centimeter from background galactic cosmic rays and the secondary particles they induce to detect and flag any events that could be confused with a science photon in the 0.3-2 keV signal band of LEM. Our design spans an active region 4-cm in diameter. It consists of 12 quasiparticle-trap-assisted electrothermal-feedback (QET) channels, each with 100 parallel TESes with common bias lines. The TES is a narrow strip of Mo/Au bilayer. We present fabrication processes that maintain the transition temperature (T c ) in Mo/Au bilayer structures across the active region. We further present a new design based on a a-Si/W TES layer that has previously achieved reasonable uniformity in lab testing.
Neutron detection is widely used in many applications including nuclear physics, nuclear energy, nuclear technologies and nuclear safeguards. Developing an end-to-end neutron detection and imaging workflow paves way towards fully automated processes for many applications. We implemented an automated workflow for neutron detection experiments which use a solid state image sensor to capture neutron hits as a digital image. We deploy the workflow to an edge-based optical neural network (ONN) to increase the radiation-hardness and lifetime of neutron detection instruments. We present a two-stage neural network framework for detection of neutrons at sub-pixel resolution. The first stage uses a region proposal network to efficiently detect and extract neutron hits from the input camera image. The second stage feeds the extracted hits into a fully connected neural network to predict the sub-pixel hit position. The performance of the two-stage framework is evaluated using the edge-based ONN. The results show that we can achieve above 96% neutron detection accuracy as well as sub-pixel and sub-micron position resolution, while enjoying the advantages of the ONN hardware including radiation-hardness, low energy consumption and high computing speed for integrated edge camera and hardware deployment, when compared with electronic counterparts.
The functional equivalence of the HyperSolve unstructured edge-based, finite-volume computational fluid dynamics code to the Langley Aerothermodynamic Upwind Relaxation Algorithm multiblock structured grid code is documented for applications of interest to the Entry, Descent, and Landing community. A suite of cases using a range of thermochemical gas models on relevant vehicle configurations were analyzed with both codes and the results compared. A tolerance of ±4% difference in surface pressure and surface heat flux from a benchmark LAURA solution was used as the criterion for functional equivalence, and comparisons of flowfield quantities are also included to verify that the thermochemical nonequilibrium capabilities in HyperSolve match those of the LAURA code. The functional equivalence of the HyperSolve unstructured edge-based finite-volume computational fluid dynamics (CFD) code to the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) multiblock structured grid code is documented for applications of interest to the Entry, Descent, and Landing (EDL) community. A suite of cases using a range of thermochemical gas models on EDL-relevant vehicle configurations were analyzed with both codes and the results compared. A tolerance of ±4% difference in surface pressure and surface heat flux from a benchmark LAURA solution was used as the criterion for functional equivalence, and comparisons of flow field quantities are also included to verify that the thermochemical nonequilibrium capabilities in HyperSolve match those of the LAURA code. In general, HyperSolve predictions for surface pressure and surface heat flux are in close agreement with those predicted by LAURA.
The functional equivalence of the HyperSolve unstructured edge-based, finite-volume computational fluid dynamics code to the Langley Aerothermodynamic Upwind Relaxation Algorithm multiblock structured grid code is documented for applications of interest to the Entry, Descent, and Landing community. A suite of cases using a range of thermochemical gas models on relevant vehicle configurations were analyzed with both codes and the results compared. A tolerance of ±4% difference in surface pressure and surface heat flux from a benchmark LAURA solution was used as the criterion for functional equivalence, and comparisons of flowfield quantities are also included to verify that the thermochemical nonequilibrium capabilities in HyperSolve match those of the LAURA code. The functional equivalence of the HyperSolve unstructured edge-based finite-volume computational fluid dynamics (CFD) code to the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) multiblock structured grid code is documented for applications of interest to the Entry, Descent, and Landing (EDL) community. A suite of cases using a range of thermochemical gas models on EDL-relevant vehicle configurations were analyzed with both codes and the results compared. A tolerance of ±4% difference in surface pressure and surface heat flux from a benchmark LAURA solution was used as the criterion for functional equivalence, and comparisons of flow field quantities are also included to verify that the thermochemical nonequilibrium capabilities in HyperSolve match those of the LAURA code. In general, HyperSolve predictions for surface pressure and surface heat flux are in close agreement with those predicted by LAURA.
Year 1 progress can be characterized with four major achievements which are crucial toward the development of robust, easy to use antenna analysis code on doubly conformal platforms. (1) A new FEM code was developed using prismatic meshes. This code is based on a new edge based distorted prism and is particularly attractive for growing meshes associated with printed slot and patch antennas on doubly conformal platforms. It is anticipated that this technology will lead to interactive, simple to use codes for a large class of antenna geometries. Moreover, the codes can be expanded to include modeling of the circuit characteristics. An attached report describes the theory and validation of the new prismatic code using reference calculations and measured data collected at the NASA Langley facilities. The agreement between the measured and calculated data is impressive even for the coated patch configuration. (2) A scheme was developed for improved feed modeling in the context of FEM. A new approach based on the voltage continuity condition was devised and successfully tested in modeling coax cables and aperture fed antennas. An important aspect of this new feed modeling approach is the ability to completely separate the feed and antenna mesh regions. In this manner, different elements can be used in each of the regions leading to substantially improved accuracy and meshing simplicity. (3) A most important development this year has been the introduction of the perfectly matched interface (PMI) layer for truncating finite element meshes. So far the robust boundary integral method has been used for truncating the finite element meshes. However, this approach is not suitable for antennas on nonplanar platforms. The PMI layer is a lossy anisotropic absorber with zero reflection at its interface. (4) We were able to interface our antenna code FEMA_CYL (for antennas on cylindrical platforms) with a standard high frequency code. This interface was achieved by first generating equivalent magnetic currents across the antenna aperture using the FEM code. These currents were employed as the sources in the high frequency code.
High-quality, epitaxial superconductor(S)/normal(N)/S edge-geometry weak-link Josephson devices were fabricated.
This paper presents a review and comparison of the engineering and physiological optics literature on defocus detection. The equivalence of spatial frequency based detectors and the edge-based hypothesis, and variance-based detectors and the contrast- difference hypothesis is argued. Finally, variance-invariant transforms are introduced as a means of experimentally differentiating the hypotheses.
A new multigrid method with adaptive unstructured grids is presented. The three-dimensional Euler equations are solved on tetrahedral grids that are adaptively refined or coarsened locally. The multigrid method is employed to propagate the fine grid corrections more rapidly by redistributing the changes-in-time of the solution from the fine grid to the coarser grids to accelerate convergence. A new approach is employed that uses the parent cells of the fine grid cells in an adapted mesh to generate successively coaser levels of multigrid. This obviates the need for the generation of a sequence of independent, nonoverlapping grids as well as the relatively complicated operations that need to be performed to interpolate the solution and the residuals between the independent grids. The solver is an explicit, vertex-based, finite volume scheme that employs edge-based data structures and operations. Spatial discretization is of central-differencing type combined with a special upwind-like smoothing operators. Application cases include adaptive solutions obtained with multigrid acceleration for supersonic and subsonic flow over a bump in a channel, as well as transonic flow around the ONERA M6 wing. Two levels of multigrid resulted in reduction in the number of iterations by a factor of 5.
The three dimensional Euler equations are solved on unstructured tetrahedral meshes using a multigrid strategy. The driving algorithm consists of an explicit vertex-based finite element scheme, which employs an edge-based data structure to assemble the residuals. The multigrid approach employs a sequence of independently generated coarse and fine meshes to accelerate the convergence to steady-state of the fine grid solution. Variables, residuals and corrections are passed back and forth between the various grids of the sequence using linear interpolation. The addresses and weights for interpolation are determined in a preprocessing stage using linear interpolation. The addresses and weights for interpolation are determined in a preprocessing stage using an efficient graph traversal algorithm. The preprocessing operation is shown to require a negligible fraction of the CPU time required by the overall solution procedure, while gains in overall solution efficiencies greater than an order of magnitude are demonstrated on meshes containing up to 350,000 vertices. Solutions using globally regenerated fine meshes as well as adaptively refined meshes are given.
The three-dimensional Euler equations are solved on unstructured tetrahedral meshes using a multigrid strategy. The driving algorithm consists of an explicit vertex-based finite-element scheme, which employs an edge-based data-structure to assemble the residuals. The multigrid approach employs a sequence of independently generated coarse and fine meshes to accelerate the convergence to steady-state of the fine grid solution. Variables, residuals and corrections are passed back and forth between the various grids of the sequence using linear interpolation. The addresses and weights for interpolation are determined in a preprocessing stage using an efficient graph traversal algorithm. The preprocessing operation is shown to require a negligible fraction of the CPU time required by the overall solution procedure, while gains in overall solution efficiencies greater than an order of magnitude are demonstrated on meshes containing up to 350,000 vertices. Solutions using globally regenerated fine meshes as well as adaptively refined meshes are given.