Technique cuts time and cost of bending jacketed piping

Technique uses a stiff medium in the annular space between inner and outer pipes of jacketed piping in transfer lines. The process eliminates splitting and welding and makes possible the use of standard pipe-bending tools

The effects of random path fluctuations on the accuracy of laser ranging systems

The precision of satellite ranging systems, limited in part by atmospheric refraction and scattering, is examined. The effects of atmospheric turbulence on the accuracy of single color and multicolor ranging systems is discussed. The statistical characteristics of the random path length fluctuations induced by turbulence are examined. Correlation and structure functions are derived using several proposed models for the variations of the optical path length. For single color systems it is shown that the random path length fluctuations can limit the accuracy of a range measurement to a few centimeters. Two color systems can partially correct for the random path fluctuations so that in most cases their accuracy is limited to a few millimeters. However, at low elevation angles and over long horizontal paths two color systems can also have errors approaching a few centimeters

Technique of elbow bending small jacketed transfer lines Patent

Elbow forming in jacketed pipes while maintaining separation between core shape and jacket pipe

Africa's growth prospects in a European mirror : a historical perspective

Drawing on recent quantitative research on Europe reaching back to the medieval period, and noting a relationship between the quality of institutions and economic growth, this paper offers a reassessment of Africa’s growth prospects. Periods of positive growth driven by trade, followed by growth reversals which wiped out the gains of the previous boom, characterized pre-modern Europe as well as twentieth century Africa. Since per capita incomes in much of sub-Saharan Africa are currently at the level of medieval Europe, which did not make the breakthrough to modern economic growth until the nineteenth century, we caution against too optimistic a reading of Africa’s recent growth experience. Without the institutional changes necessary to facilitate structural change, growth reversals continue to pose a serious threat to African prosperity. Only if growth continues after a downturn in Africa’s terms of trade can we be sure that the corner has been turned

History of marketing thought : an update / BEBR No. 857

Includes bibliographical references (p. 21-26)

Power processor design considerations for a solar electric propulsion spacecraft

Propulsion power processor design options are described. The propulsion power processor generated the regulated dc voltages and currents from a solar array source of a solar electric propelled spacecraft. The power processor consisted of 12 power supplies that provide the regulated voltages and currents necessary to power a 30-cm mercury ion thruster. The design options for processing unregulated solar array power and for generating the regulated power required by each supply are studied. The technical approaches utilized in the developed design and the technological limitation of the identified design options are discussed. Alternate approaches for delivering power to a number of mercury ion thrusters and methods of optimizing are described. It was concluded that this power processor design should be considered for application in solar electric propulsion missions of the future

The effects of atmospheric refraction on the accuracy of laser ranging systems

Correction formulas derived by Saastamoinen and Marini, and the ray traces through the refractivity profiles all assume a spherically symmetric refractivity profile. The errors introduced by this assumption were investigated by ray tracing through three-dimensional profiles. The results of this investigation indicate that the difference between ray traces through the spherically symmetric and three-dimensional profiles is approximately three centimeters at 10 deg and decreases to less than one half of a centimeter at 80 deg. If the accuracy desired in future laser ranging systems is less than a few centimeters, Saastamoinen and Marini's formulas must be altered to account for the fact that the refractivity profile is not spherically symmetric

Weibel Instabilities in Dense Quantum Plasmas

The quantum effect on the Weibel instability in an unmagnetized plasma is presented. Our analysis shows that the quantum effect tends to stabilize the Weibel instability in the hydrodynamic regime, whereas it produces a new oscillatory instability in the kinetic regime. A novel effect the quantum damping, which is associated with the Landau damping, is disclosed. The new quantum Weibel instability may be responsible for the generation of non-stationary magnetic fields in compact astrophysical objects as well as in the forthcoming intense laser-solid density plasma experiments.Comment: Submitted to PR

Electrostatic forces for personnel restraints

The feasibility of utilizing electrostatic forces for personnel retention devices on exterior spacecraft surfaces was analyzed. The investigation covered: (1) determination of the state of the art; (2) analysis of potential adhesion surfaces; (3) safety considerations for personnel; (4) electromagnetic force field determination and its effect on spacecraft instrumentation; and (5) proposed advances to current technology based on documentation review, analyses, and experimental test data