Design and performance evaluation of small, two- and four-stage depressed collectors for a 4.8 to 9.6 GHz high-performance traveling wave tube

A program to improve the efficiency of traveling wave tubes (TWT's) for use in electronic countermeasure (ECM) systems by applying multistage depressed collector (MDC) and spent beam refocusing techniques is studied. Three dimensional electron trajectories are computed through-out the slow wave structure of the TWT, the spent beam refocuser, and the depressed collector. Both TWT and MDC performances are analytically evaluated

Optical monitoring system

Instrument can measure optical transmission, reflectance, and scattering. This information can be used to identify changes in optical properties or deviations from required optical standards. Device consists of monochromatic source, photo detector, transfer mirror, and hemiellipsoid. System might be used to measure optical properties of thin film

Nu sub 1 plus nu sub 3 combination band of SO2

The infrared-active vibration-rotation combination band nu sub 1 + nu sub 3 of sulfur dioxide was measured with moderately high spectral resolution. Quantum number identifications of spectral lines were made by comparison with theoretically computed spectra which include the effects of centrifugal distortion. Relative line intensities were also calculated. The band center for nu sub 1 + nu sub 3 was determined to be 2499.60 + or - 0.10/cm

Fundamental bands of S(32)O2(16)

The infrared-active vibration-rotation fundamentals of sulfur dioxide were measured with moderately high spectral resolution. Quantum number assignments were made for spectral lines from J = O to 57, by comparison with theoretically computed spectra which include the effects of centrifugal distortion. The following values for the band centers were determined: nu sub 1 = 1151.65 + or - 0.10/cm, nu sub 2 = 517.75 + or - 0.10/cm, and nu sub 3 = 1362.00 + or - 0.10/cm. Intensities of the observed lines have also been computed. Dipole moment derivatives were obtained

Machine Assisted Proof of ARMv7 Instruction Level Isolation Properties

In this paper, we formally verify security properties of the ARMv7 Instruction Set Architecture (ISA) for user mode executions. To obtain guarantees that arbitrary (and unknown) user processes are able to run isolated from privileged software and other user processes, instruction level noninterference and integrity properties are provided, along with proofs that transitions to privileged modes can only occur in a controlled manner. This work establishes a main requirement for operating system and hypervisor verification, as demonstrated for the PROSPER separation kernel. The proof is performed in the HOL4 theorem prover, taking the Cambridge model of ARM as basis. To this end, a proof tool has been developed, which assists the verification of relational state predicates semi-automatically

Materials for Biomedical Applications

This paper discusses two ceramic material systems for selective laser sintering (SLS) that are being developed for biomedical applications for use in repair of bone defects. SLS is the preferred method of fabricating ceramic implants that exhibit well defined porous microstructures. Implants fabricated in this. manner have proven effective in-vivo showing excellent biocompatibility as well as considerable osseous integration and remodeling of the imp'ant materialMechanical Engineerin

Potentialities of proteinoids for nutritional investigation

Simultaneous synthesis of amino acids and proteinoid production for nutritional investigatio

Bedload‐Bedrock Contrasts Form Enigmatic Low‐Relief Surfaces of the Pyrenees

Low-relief, high-elevation surfaces in mountain belts highlight the dynamic nature of landscapes and have provided evidence for changes in tectonics and/or climate. Yet quantifying when changes occurred from topographic data is challenging and relationships between erosion rate, lithology and precipitation are complex. In the Pyrenees, low-relief, high elevation surfaces are found across both plutonic massifs and the surrounding softer rocks and channel steepness values are relatively uniform between these lithologies. This suggests a weak relationship between erosion rate and lithology despite a clear relationship between the drainage network configuration and the location of the plutonic rocks. We explore this conflicting evidence for strength of the relationship between lithology and erosion rate using a landscape evolution model which accounts for the contrast between bedrock and bedload erodibility. This contrast produces dispersed channel steepness values and predicts the in situ development of low-relief surfaces, under steady forcing conditions

A Positivity Theorem for Gravitational Tension in Brane Spacetimes

We study transverse asymptotically flat spacetimes without horizons that arise from brane matter sources. We assume that asymptotically there is a spatial translation Killing vector that is tangent to the brane. Such spacetimes are characterized by a tension, analogous to the ADM mass, which is a gravitational charge associated with the asymptotic spatial translation Killing vector. Using spinor techniques, we prove that the purely gravitational contribution to the spacetime tension is positive definite.Comment: 8+1 page