B-52B/DTV (Drop Test Vehicle) flight test results: Drop test missions

The NASA test airplane, B-52B-008, was a carrier for drop tests of the shuttle booster recovery parachute system. The purpose of the test support by Boeing was to monitor the vertical loads on the pylon hooks. The hooks hold the Drop Test Vehicle to the B-52 pylon during drop test missions. The loads were monitored to assure the successful completion of the flight and the safety of the crew

A study of model deflection measurement techniques applicable within the national transonic facility

Moire contouring, scanning interferometry, and holographic contouring were examined to determine their practicality and potential to meet performance requirements for a model deflection sensor. The system envisioned is to be nonintrusive, and is to be capable of mapping or contouring the surface of a 1-meter by 1-meter model with a resolution of 50 to 100 points. The available literature was surveyed, and computations and analyses were performed to establish specific performance requirements, as well as the capabilities and limitations of such a sensor within the geometry of the NTF section test section. Of the three systems examined, holographic contouring offers the most promise. Unlike Moire, it is not hampered by limited contour spacing and extraneous fringes. Its transverse resolution can far exceed the limited point sampling resolution of scanning heterodyne interferometry. The availability of the ruby laser as a high power, pulsed, multiple wavelength source makes such a system feasible within the NTF

Dynamic assessment of B-52B-008 carrier aircraft for the revised Space Shuttle solid rocket booster decelerator subsystem drop test vehicle

The structural integrity of B-52B-008, pylon, and hooks for the drop test missions was determined by theoretical analysis. The results of the analysis and conclusions are presented in this document. The major modification to the drop test vehicle was shortening it about 54 inches, which resulted in the forward hook attach structure being located at the base of the nosecone. The shims that are located in the aft hook structures are increased from two inches to three inches. Airspeed, aerodynamic configuration, and load charts are included

On the Construction of Fiber-Optic Cables

In recent years, much research has been devoted to the improvement of RAID; however, few have enabled the analysis of active networks. After years of structured research into thin clients, we prove the visualization of virtual machines. Our focus in this paper is not on whether red- black trees can be made flexible, omniscient, and modular, but rather on introducing an algorithm for context-free grammar (Toph)

Hole Spin Mixing in InAs Quantum Dot Molecules

Holes confined in single InAs quantum dots have recently emerged as a promising system for the storage or manipulation of quantum information. These holes are often assumed to have only heavy-hole character and further assumed to have no mixing between orthogonal heavy hole spin projections (in the absence of a transverse magnetic field). The same assumption has been applied to InAs quantum dot molecules formed by two stacked InAs quantum dots that are coupled by coherent tunneling of the hole between the two dots. We present experimental evidence of the existence of a hole spin mixing term obtained with magneto-photoluminescence spectroscopy on such InAs quantum dot molecules. We use a Luttinger spinor model to explain the physical origin of this hole spin mixing term: misalignment of the dots along the stacking direction breaks the angular symmetry and allows mixing through the light-hole component of the spinor. We discuss how this novel spin mixing mechanism may offer new spin manipulation opportunities that are unique to holes.Comment: 13 pages, 9 figure

Large-area submillimeter resolution CdZnTe strip detector for astronomy

We report the first performance measurements of a sub-millimeter CdZnTe strip detector developed as a prototype for space-borne astronomical instruments. Strip detector arrays can be used to provide two-dimensional position resolution with fewer electronic channels than pixellated arrays. Arrays of this type and other candidate technologies are under investigation for the position-sensitive backplane detector for a coded-aperture telescope operating in the range of 30 - 300 keV. The prototype is a 1.4 mm thick, 64 multiplied by 64 stripe CdZnTe array of 0.375 mm pitch in both dimensions, approximately one square inch of sensitive area. Pulse height spectra in both single and orthogonal stripe coincidence mode were recorded at several energies. The results are compared to slab- and pixel-geometry detector spectra. The room-temperature energy resolution is less than 10 keV (FWHM) for 122 keV photons with a peak-to-valley ratio greater than 5:1. The response to photons with energies up to 662 keV appears to be considerably improved relative to that of previously reported slab and pixel detectors. We also show that strip detectors can yield spatial and energy resolutions similar to those of pixellated arrays with the same dimensions. Electrostatic effects on the pulse heights, read-out circuit complexity, and issues related to design of space borne instruments are also discussed

The Power of Duples (in Self-Assembly): It's Not So Hip To Be Square

In this paper we define the Dupled abstract Tile Assembly Model (DaTAM), which is a slight extension to the abstract Tile Assembly Model (aTAM) that allows for not only the standard square tiles, but also "duple" tiles which are rectangles pre-formed by the joining of two square tiles. We show that the addition of duples allows for powerful behaviors of self-assembling systems at temperature 1, meaning systems which exclude the requirement of cooperative binding by tiles (i.e., the requirement that a tile must be able to bind to at least 2 tiles in an existing assembly if it is to attach). Cooperative binding is conjectured to be required in the standard aTAM for Turing universal computation and the efficient self-assembly of shapes, but we show that in the DaTAM these behaviors can in fact be exhibited at temperature 1. We then show that the DaTAM doesn't provide asymptotic improvements over the aTAM in its ability to efficiently build thin rectangles. Finally, we present a series of results which prove that the temperature-2 aTAM and temperature-1 DaTAM have mutually exclusive powers. That is, each is able to self-assemble shapes that the other can't, and each has systems which cannot be simulated by the other. Beyond being of purely theoretical interest, these results have practical motivation as duples have already proven to be useful in laboratory implementations of DNA-based tiles

High-fidelity simulations of CdTe vapor deposition from a new bond-order potential-based molecular dynamics method

CdTe has been a special semiconductor for constructing the lowest-cost solar cells and the CdTe-based Cd1-xZnxTe alloy has been the leading semiconductor for radiation detection applications. The performance currently achieved for the materials, however, is still far below the theoretical expectations. This is because the property-limiting nanoscale defects that are easily formed during the growth of CdTe crystals are difficult to explore in experiments. Here we demonstrate the capability of a bond order potential-based molecular dynamics method for predicting the crystalline growth of CdTe films during vapor deposition simulations. Such a method may begin to enable defects generated during vapor deposition of CdTe crystals to be accurately explored

CdZnTe strip detectors as sub-millimeter resolution imaging gamma radiation spectrometers

We report γ-ray detection performance measurements and computer simulations of a sub-millimeter pitch CdZnTe strip detector. The detector is a prototype for γ-ray measurements in the range of 20-600 keV. The prototype is a 1.5 mm thick, 64×64 orthogonal stripe CdZnTe detector of 0.375 mm pitch in both dimensions, with approximately one square inch of sensitive area. Using discrete laboratory electronics to process signals from an 8×8 stripe region of the prototype we measured good spectroscopic uniformity and sub-pitch (~0.2 mm) spatial resolution in both x and y dimensions. We present below measurements of the spatial uniformity, relative timing and pulse height of the anode and cathode signals. We simulated the photon interactions and signal generation in the strip detector and the test electronics and we compare these results with the data. The data indicate that cathode signal-as well as the anode signal-arises more strongly from the conduction electrons rather than the holes