Wind tunnel tests of modified cross, hemisflo, and disk-gap-band parachutes with emphasis in the transonic range

Transonic wind-tunnel studies were conducted with modified cross, hemisflo, and disk-gap-band parachute models in the wake of a cone-cylinder shape forebody. The basic cross design was modified with the addition of a circumferential constraining band at the lower edge of the canopy panels. The tests covered a Mach number range of 0.3 to 1.2 and a dynamic pressure range from 479 Newtons per square meter to 5746 Newtons per square meter. The parachute models were flexible textile-type structures and were tethered to a rigid forebody with a single flexible riser. Different size models of the modified cross and disk-gap-band canopies were tested to evaluate scale effects. Model reference diameters were 0.30, 0.61, and 1.07 meters (1.0, 2.0, and 3.5 ft) for the modified cross; and nominal diameters of 0.25 and 0.52 meter (0.83 and 1.7 ft) for the disk-gap-band; and 0.55 meter (1.8 ft) for the hemisflo. Reefing information is presented for the 0.61-meter-diameter cross and the 0.52-meter-diameter disk-gap-band. Results are presented in the form of the variation of steady-state average drag coefficient with Mach number. General stability characteristics of each parachute are discussed. Included are comments on canopy coning, spinning, and fluttering motions

A Recommended Approach to the Antarctic Resource Problem

As existing resource reserves dwindle, exploration in areas once considered to be beyond feasible exploitation is now being examined much more closely. The author suggests that the southern polar region is one such area ripe for future development. Since Antarctica lacks a political administration, however, problems arise concerning sovereignty rights over its resources. Claims of historical entitlement must be reconciled with the demands of the international community for general recognition to be realized. Currently, a treaty exists among states interested in Antarctica which is concerned primarily with the continued use of the continent for peaceful scientific investigation. Although the Antarctic Treaty provides a framework for a structured development scheme, it conspiciously fails to address the resource-sovereignty issue. The author proposes a plan which assimilates the existing Antarctic Treaty composition while resolving the polemic interests of states asserting territorial claims in the Antarctic and of the remainder of the world community

Residence Times of Minnesota Groundwaters

ABSTRACT-Tritium, 14C, and nitrate analyses for eighty groundwater samples from selected Minnesota aquifers indicate a range of residence times from a few days or weeks to tens of thousands of years. The presence of significant nitrate contamination in groundwater is confined to recent or mixed groundwaters. Isotopic studies can yield information that will be useful in the design of effective groundwater protection plans in Minnesota

Scaling the Hierarchy: How and Why Investment Banks Compete for Syndicate Co-Management Appointments

We investigate the empirical puzzle why banks pressured their analysts to provide aggressive assessments of issuing firms during the 1990s when doing so apparently had little positive effect on their chances of receiving lead-management appointments and ultimately led to regulatory penalties and costly structural reform. We show that aggressively optimistic research can attract co-management appointments and that co-management appointments eventually lead to more lucrative lead-management opportunities. Our results suggest a potential unintended anticompetitive effect of the Global Settlement if forcing greater separation of research and investment banking diminishes co-management opportunities for (and thereby potential competition from) marginal competitors in securities underwriting, especially in the debt markets

Observations of High Vibrational Levels of the 4fσ 41Σ+ u State of H2

Resonantly enhanced multiphoton ionization via the EF 1Σg+, v′ = 6 double-well state has been used to probe the energy region below the third dissociation limit of H2 where several high vibrational levels of the 41Σu+ state are expected. Theoretical ab initio potential energy curves for this state predict a deep inner well and shallow outer well where vibrational levels above v = 8 are expected to exhibit the double-well character of the state. Since the 41Σu+ state has f-state character, transitions to it from the ground state are nominally forbidden. However, the d character of the outer well of the EF 1Σg+ state allows access to this state. We report observations of transitions to the v = 9–12 levels of the 41Σu+ state and compare their energies to predicted energies calculated from an ab initio potential energy curve with adiabatic corrections. Assignments are based on measured energies and linewidths, rotational constants, and expected transition strengths. The amount of agreement between the predicted values and the observations is mixed, with the largest discrepancies arising for the v = 9 level, owing to strong nonadiabatic electronic mixing in this energy region