An evaluation of errors observed in the measurement of low wind velocities

Measurements of low wind velocities (the absolute value of V sub H is approx. equal to 6 m/s) with a VHF wind profiler can be difficult if ground clutter or other biases in the system dominate in altering the position of the perceived peak in the calculated power spectrum. A variety of methods for ground clutter suppression are used in profiler systems today (Cornish, 1983). An editing method called zero suppression takes the spectral value of selectable number of points (N) on each side of 0 velocity (one point on either side, in this study) and sets them equal to the mean value of the points exterior to the specified N points on either side of 0. Analysis done with the PSU VHF(1) radar, shows that this zero-suppression method can systematically bias horizontal wings V sub H below 6 m/s. With the zero suppression, an artificial increase in absolute wind velocities occurs when the spectral peaks fall within the plus or minus N points of the FFT (personal communication, Strauch, 1985). It was also established that the method artificially decreases the absolute wind velocities inferred from spectral peaks that are outside but near the suppressed region. Comparisons of wind profiles observed with and without zero suppression are given. The range of the biased velocities extends to about plus or minus 6 m/s. Biases have been deduced to be as much as 2 m/s, but more commonly they are on the order of 1.0 m/s

Study on utilization of advanced composites in fuselage structures of large transports

The potential for utilizing advanced composites in fuselage structures of large transports was assessed. Six fuselage design concepts were selected and evaluated in terms of structural performance, weight, and manufacturing development and costs. Two concepts were selected that merit further consideration for composite fuselage application. These concepts are: (1) a full depth honeycomb design with no stringers, and (2) an I section stringer stiffened laminate skin design. Weight reductions due to applying composites to the fuselages of commercial and military transports were calculated. The benefits of applying composites to a fleet of military transports were determined. Significant technology issues pertinent to composite fuselage structures were identified and evaluated. Program plans for resolving the technology issues were developed

Network ST radar and related measurements at Pennsylvania State University

Mesoscale meteorological measurements, analysis and prediction are some of the principal areas of research in the Department of Meteorology at Penn State. In anticipation of a staged turn-on of the three systems during the Summer and Fall of 1984, the nonconstruction-related efforts have focused on the software development necessary to allow essentially immediate use of network data. A 16-bit microcomputer has been programmed to serve as the network controller, communications interface and, at least for real-time purposes, the operational display system. Insofar as possible we have in this task built upon our substantial accumulated experience in working with the processing and display of Doppler sodar system signals. Once the radar-derived wind and turbulence profiles are communicated to the various interconnected Departmental computers they become just one component of a comprehensive data base which can be applied to a diverse set of ongoing basic and operational research programs

The effects of reinforcement interval on the acquisition of paired-associate responses

Effects of reinforcement interval on acquisition of paired-associate response

Energy Loss from Reconnection with a Vortex Mesh

Experiments in superfluid 4He show that at low temperatures, energy dissipation from moving vortices is many orders of magnitude larger than expected from mutual friction. Here we investigate other mechanisms for energy loss by a computational study of a vortex that moves through and reconnects with a mesh of small vortices pinned to the container wall. We find that such reconnections enhance energy loss from the moving vortex by a factor of up to 100 beyond that with no mesh. The enhancement occurs through two different mechanisms, both involving the Kelvin oscillations generated along the vortex by the reconnections. At relatively high temperatures the Kelvin waves increase the vortex motion, leading to more energy loss through mutual friction. As the temperature decreases, the vortex oscillations generate additional reconnection events between the moving vortex and the wall, which decrease the energy of the moving vortex by transfering portions of its length to the pinned mesh on the wall.Comment: 9 pages, 10 figure

Development of pressure containment and damage tolerance technology for composite fuselage structures in large transport aircraft

NASA sponsored composites research and development programs were set in place to develop the critical engineering technologies in large transport aircraft structures. This NASA-Boeing program focused on the critical issues of damage tolerance and pressure containment generic to the fuselage structure of large pressurized aircraft. Skin-stringer and honeycomb sandwich composite fuselage shell designs were evaluated to resolve these issues. Analyses were developed to model the structural response of the fuselage shell designs, and a development test program evaluated the selected design configurations to appropriate load conditions

Doctrine of the Protection of Nationals Abroad: Rise of the Non-Combatant Evacuation Operation

The purpose of this Article is to show that the doctrine of the protection of nationals abroad exists within the right of self-defense; with contours of the doctrine shaped in recent years by the practice of states in their conduct of NEO. This right is limited to the removal of the intervening state‘s citizens abroad through the use of force subject to necessity and proportionality in order to move the foreign nationals to a safe location, Part II discusses the origin of the doctrine of protection of nationals abroad and the legal bases that have been used to justify that protection. It also considers the impact of the misuse of the doctrine throughout its evolution. This explanation includes the claim that the protection of nationals abroad does not impugn Article 2(4) of the U.N. Charter which prohibits a state‘s use of force against another state and the justification that the protection of nationals is an exercise of the right of self-defense which complies with a state‘s right of self-defense enshrined in Article 51 of the UN Charter. It assesses the doctrine‘s place in self-defense at customary international law. Furthermore, this Article reviews state practice and the debate that has ensued among states and academics when states have asserted the doctrine to justify their use of force abroad. This Article also assesses the difficulties in determining the legality of the doctrine based upon the divided opinion of states. Part III surveys the military operational doctrine pertaining to NEO. Part IV assesses the recent invocation of the doctrine by the Russian Federation in its conflict in South Ossetia. Part V provides an analysis of the how NEOs as state practice have acted to limit the extent of protection to nationals abroad. Finally, in Part VI this Article concludes with an assessment of the state of the doctrine in contemporary international law

Vector acoustic miss distance indication

In 1981 the author decided to investigate means of accurately measuring the passage of anti-aircraft shells past a towed airborne target. This decision was based on the observation that available literature showed a need for low cost miss distance indication equipment. A feasibility study showed that the task would be multi-disciplinary entailing aerodynamics telemetry, weapons performance studies and investigation of the techniques of measurement of shell location currently in use. The decision was made by the author to concentrate on a study of the technique measurements of shell location and the analysis of such measurements in view of the fact that, at least in isolation, knowledge of the other factors mentioned was fairly complete although unevenly spread in South Africa. Initial work concerned a study of the General Requirements for such target systems and the classification of these. A literature survey was conducted by the author which indicated that systems already in service made use of several measurement techniques, including photographic, radar and acoustic phenomena. Of these, acoustic means appeared to offer a cheap and simple solution to the measurement problem. The author then explored the principles and potential of Acoustic Miss Distance indication and arrived at the conclusion that such a system, based on measurements of the period of the shockwave accompanying a supers6nic shell, would be feasible. This conclusion led to the Thesis presented in this document, that firstly measurement of the shock-wave period could enable deduction of the distance between the sensor and the flight path of a supersonic shell and secondly, that several such measurements would enable the miss vector to be calculated

Calculation of Elastic Green's Functions for Lattices with Cavities

In this Brief Report, we present an algorithm for calculating the elastic Lattice Greens Function of a regular lattice, in which defects are created by removing lattice points. The method is computationally efficient, since the required matrix operations are on matrices that scale with the size of the defect subspace, and not with the size of the full lattice. This method allows the treatment of force fields with multi-atom interactions.Comment: 3 pages. RevTeX, using epsfig.sty. One figur

Intrinsic Periodicity of Time and Non-maximal Entropy of Universe

The universe is certainly not yet in total thermodynamical equilibrium,so clearly some law telling about special initial conditions is needed. A universe or a system imposed to behave periodically gets thereby required ``initial conditions". Those initial conditions will \underline{not} look like having already suffered the heat death, i.e. obtained the maximal entropy, like a random state. The intrinsic periodicity explains successfully why entropy is not maximal, but fails phenomenologically by leading to a \underline{constant}entropy.Comment: 8 page