Automated Pilot Advisory System

An Automated Pilot Advisory System (APAS) was developed and operationally tested to demonstrate the concept that low cost automated systems can provide air traffic and aviation weather advisory information at high density uncontrolled airports. The system was designed to enhance the see and be seen rule of flight, and pilots who used the system preferred it over the self announcement system presently used at uncontrolled airports

Studies of the auroral substorm. III CONCEPT of the magnetospheric substorm and its relation to electron precipitation and micropulsations

Concept of auroral magnetospheric substorm and relation to electron precipitation and micropulsation

Thermodynamic properties of Bi2Sr2CaCu2O8 calculated from the electronic dispersion

The electronic dispersion for Bi2Sr2CaCu2O(8+d) has been determined from angle-resolved photoelectron spectroscopy (ARPES). From this dispersion we calculate the entropy and superfluid density. Even with no adjustable parameters we obtain an exceptional match with experimental data across the entire phase diagram, thus indirectly confirming both the ARPES and thermodynamic data. The van Hove singularity is crossed in the overdoped region giving a distinctive linear-in-T temperature dependence in the superfluid density there.Comment: 5 pages, 4 figures, submitted to Physical Review Letter

BGK electron solitary waves: 1D and 3D

International audienceThis paper presents new results for 1D BGK electron solitary wave (phase-space electron hole) solutions and, based on the new results, extends the solutions to include the 3D electrical interaction (E ~ 1/r 2) of charged particles. Our approach for extending to 3D is to solve the nonlinear 3D Poisson and 1D Vlasov equations based on a key feature of 1D electron hole (EH) solutions; the positive core of an EH is screened by electrons trapped inside the potential energy trough. This feature has not been considered in previous studies. We illustrate this key feature using an analytical model and argue that the feature is independent of any specific model. We then construct azimuthally symmetric EH solutions under conditions where electrons are highly field-aligned and ions form a uniform background along the magnetic field. Our results indicate that, for a single humped electric potential, the parallel cut of the perpendicular component of the electric field (E?) is unipolar and that of the parallel component (E||) bipolar, reproducing the multi-dimensional features of the solitary waves observed by the FAST satellite. Our analytical solutions presented in this article capture the 3D electric interaction and the observed features of (E|| ) and E?. The solutions predict a dependence of the parallel width-amplitude relation on the perpendicular size of EHs. This dependence can be used in conjunction with experimental data to yield an estimate of the typical perpendicular size of observed EHs; this provides important information on the perpendicular span of the source region as well as on how much electrostatic energy is transported by the solitary waves

Monolithic microwave integrated circuit water vapor radiometer

A proof of concept Monolithic Microwave Integrated Circuit (MMIC) Water Vapor Radiometer (WVR) is under development at the Jet Propulsion Laboratory (JPL). WVR's are used to remotely sense water vapor and cloud liquid water in the atmosphere and are valuable for meteorological applications as well as for determination of signal path delays due to water vapor in the atmosphere. The high cost and large size of existing WVR instruments motivate the development of miniature MMIC WVR's, which have great potential for low cost mass production. The miniaturization of WVR components allows large scale deployment of WVR's for Earth environment and meteorological applications. Small WVR's can also result in improved thermal stability, resulting in improved calibration stability. Described here is the design and fabrication of a 31.4 GHz MMIC radiometer as one channel of a thermally stable WVR as a means of assessing MMIC technology feasibility

Angular dependence of the magnetization of isotropic superconductors: which is the vortex direction?

We present studies of the dc magnetization of thin platelike samples of the isotropic type II superconductor PbTl(10%), as a function of the angle between the normal to the sample and the applied magnetic field ${\bf H}$. We determine the magnetization vector ${\bf M}$ by measuring the components both parallel and normal to ${\bf H}$ in a SQUID magnetometer, and we further decompose it in its reversible and irreversible contributions. The behavior of the reversible magnetization is well understood in terms of minimization of the free energy taking into account geometrical effects. In the mixed state at low fields, the dominant effect is the line energy gained by shortening the vortices, thus the flux lines are almost normal to the sample surface. Due to the geometrical constrain, the irreversible magnetization ${\bf M}_{irr}$ remains locked to the sample normal over a wide range of fields and orientations, as already known. We show that in order to undestand the angle and field dependence of the modulus of ${\bf M}_{irr}$, which is a measure of the vortex pinning, and to correctly extract the field dependent critical current density, the knowledge of the modulus and orientation of the induction field ${\bf B}$ is required.Comment: 11 pages, 6 figure

Studies of the auroral substorm. I - Characteristics of modulated energetic electron precipitation occurring during auroral substorms

Characteristics of modulated energetic electron precipitation occurring during auroral substorm

Enhancing the Performance of the T-Peel Test for Thin and Flexible Adhered Laminates

Symmetrically bonded thin and flexible T-peel specimens, when tested on vertical travel machines, can be subject to significant gravitational loading; with the associated asymmetry and mixed-mode failure during peeling. This can cause erroneously high experimental peel forces to be recorded which leads to uncertainty in estimating interfacial fracture toughness and failure mode. To overcome these issues, a mechanical test fixture has been designed for use with vertical test machines, that supports the unpeeled portion of the test specimen and suppresses parasitic loads due to gravity from affecting the peel test. The mechanism, driven by the test machine cross-head, moves at one-half of the velocity of the cross-head such that the unpeeled portion always lies in the plane of the instantaneous center of motion. Several specimens such as bonded polymeric films, laminates, and commercial tapes were tested with and without the fixture, and the importance of the proposed T-peel procedure has been demonstrated

Charge-State Equilibrium and Nonequilibrium Modeling of the Carbon-Pellet Plasma Interaction

Self-consistent equilibrium and nonequilibrium charge-state models are formulated for the spherical expansion of low-Z pellet vapor as an inviscid perfect gas of constant ratio of specific heats being heated volumetrically by the incident electrons of a thermonuclear plasma. The two models are found to be in agreement in the region where the ratio of the ionization length ζj to pellet radius rp is less than unity, but a single parameter, such as the magnitude of this ratio on the sonic surface, is insufficient to determine whether an equilibrium model will be valid for all regions of the ablatant for carbon pellets. Thus a nonequilibrium model is necessary to model the outer regions of the ablatant cloud even for thermonuclear plasma conditions when the cloud is very dense. Also, the effect of the ionization of the ablatant by the incident plasma electrons is found to be 10% or less for even the C+3 region in the thermonuclear regime. Finally, although the model used for the healing of the ablatant by the plasma electrons is that for a neutral carbon ablatant, it is shown that the differences in heating by the plasma electrons between this model and that for an ionized ablatant are small

Application of the Results of Carbon Pellet Modeling to The Problem of Plasma Penetration

The assumptions of the evaporation model for low-Z pellets interacting with magnetic fusion plasmas developed by Parks are tested. These assumptions are that the vapor density profile in the region adjacent to the pellet surface falls off with radial distance as r-α , where 5 \u3cα\u3c6, and that the ionization time for the transition between charge states זf (i.e., for r \u3c ~3 sonic radii). The first assumption is tested by solving a two-parameter eigenvalue problem for the evaporation cloud in the region interior to the sonic radius; the results are found to be consistent with the low-Z evaporation model. The second assumption, that זzi «זf, is tested at the sonic radius using the results from atomic physics and the low-Z evaporation model. It is found that indeed זzi «זf for plasmas with parameters close to thermonuclear conditions (e.g. CIT), but not for those of smaller Tokamaks such as TEXT. The results of pellet penetration calculations for the conditions of the carbon-pellet injection experiments into TEXT and low-density TFTR plasmas are presented that show better agreement with experiment if the shielding fraction is calculated at each step of the pellet penetration calculation, the effect of ionization is ignored, and if the effect of possible uncertainties in the background plasma parameters is included