A Body Modification to Reduce Drag Due to Wedge Angle of Wing with Unswept Trailing Edge

Ward's slender-body-theory formula for zero-lift drag contains three integrals plus a base-drag term. Two of these integral terms depend only upon the cross-sectional area distribution of the body. The third integral term depends only upon the body shape and axial slopes at the base of the body. This term is neglected in the transonic area rule because in many cases it is zero; however, there are also many cases in which it is not zero. This paper examines the term for the possibility of drag reduction for a particular case. The model considered consists of a body of revolution in combination with any wing that has an unswept trailing edge and a constant trailing-edge angle along its span. It is found that (neglecting any change in base drag) a drag reduction is obtainable which, for the case considered, is an additional 12 percent of that obtained with the area-rule modification. The probable effect of viscosity on this theoretical result is discussed

An 8-DPSK TCM modem for MSAT-X

This paper describes the real-time digital implementation of an 8-differentiated phase-shift keying (DPSK) trellis-coded modulation (TCM) modem for operation on an L-band, 5 kHz wide, land mobile satellite (LMS) channel. The modem architecture as well as some of the signal processing techniques employed in the modem to combat the LMS channel impairments are described, and the modem performance over the fading channel is presented

WHO IS A TOURIST? A COMPARISON OF STRAIGHT LINE AND DRIVING DISTANCES

The purpose of this study was to determine if the definition of a tourist calculated by travel distance and method used to calculate that distance has an effect on who is considered a tourist. Three commonly used travel distance oriented definitions of a tourist and two methods of calculation are offered for these purposes. The three definitions of a tourist used in this study were: (1) Travel distance of greater than 50 miles, (2) Travel distance of greater than 100 miles, and (3) Travel distance of greater than 50 miles including a night’s stay. The two methods of calculating travel distance were straight line distance and driving distance. This research found that both the definition of a tourist and the method of distance calculation had a significant effect on who was considered a tourist

Sensitivity analysis of the reactor safety study

Originally presented as the first author's thesis, (M.S.) in the M.I.T. Dept. of Nuclear Engineering, 1979.The Reactor Safety Study (RSS) or Wash-1400 developed a methodology estimating the public risk from light water nuclear reactors. In order to give further insights into this study, a sensitivity analysis has been performed to determine the significant contributors to risk for both the PWR and BWR. The sensitivity to variation of the point values of the failure probabilities reported in the RSS was determined for the safety systems identified therein, as well as for many of the generic classes from which individual failures contributed to system failures. Increasing as well as decreasing point values were considered. An analysis of the sensitivity to increasing uncertainty in system failure probabilities was also performed. The sensitivity parameters chosen were release category prob- abilities, core melt probability, and the risk parameters of early fatalities, latent cancers and total property damage. The latter three are adequate for describing all public risks identified in the RSS. The results indicate reductions of public risk by less than a factor of two for factor reductions in system or generic failure probabilities as hignh as one hundred. There also appears to be more benefit in monitoring the most sensitive systems to verify adherence to RSS failure rates than to backfitting present reactors. The sensitivity analysis results do indicate, however, possible benefits in reducing human error rates.Final report for research project sponsored by Northeast Utilities Service Company, Yankee Atomic Electric Company under the M.I.T. Energy Laboratory Electric Utility Program

The Influence of Mindfulness During the Travel Anticipation Phase on Search and Choice Behaviors, Search and Choice Outcomes, and Trip Evaluations

Tourists exhibit varying levels of mindfulness during the travel anticipation phase, when they are engaged in vacation planning (Clawson & Knetsch, 1966). Mindfulness is associated with analytic decision making through a heightened sensitivity to one’s environment and openness to new information (Langer & Moldoveanu, 2000). This study considered the influence that mindfulness during the travel anticipation phase has on: search and choice behaviors (planning horizon, size of the choice set, information source variety), search and choice outcomes (planning enjoyment, confidence in destination choice), and trip evaluations (satisfaction, behavioral loyalty, attitudinal loyalty). Additional analysis was conducted for mediating and moderating effects based on how much of the trip was planned in advance, whether the tourist visited a repeat or new destination, and whether the tourist considered the area to be their primary destination. The results of the study confirmed that mindfulness during the anticipation phase influenced the travel experience

Sensitivity analysis of the reactor safety study

Originally presented as the first author's thesis, (M.S.)--in the M.I.T. Dept. of Nuclear Engineering, 1979Includes bibliographical references (p. 232-233)Final research project reportFinal report for research project sponsored by Northeast Utilities Service Company, Yankee Atomic Electric Company under the M.I.T. Energy Laboratory Electric Utility Progra

Behavioural effects of juvenile hormone and their influence on division of labour in leaf-cutting ant societies

Division of labour in social insects represents a major evolutionary transition, but the physiological mechanisms that regulate this are still little understood. Experimental work with honey bees, and correlational analyses in other social insects, have implicated juvenile hormone (JH) as a regulatory factor, but direct experimental evidence of behavioural effects of JH in social insects is generally lacking. Here, we used experimental manipulation of JH to show that raised JH levels in leaf-cutting ants results in workers becoming more active, phototactic and threat responsive, and engaging in more extranidal activity – behavioural changes that we show are all characteristic of the transition from intranidal work to foraging. These behavioural effects on division of labour suggest that the JH mediation of behaviour occurs across multiple independent evolutions of eusociality, and may be a key endocrine regulator of the division of labour which has produced the remarkable ecological and evolutionary success of social insects

Deep ocean disposal of sewage sludge off Orange County, California: a research plan

Even though the discharge of sludge into the ocean via an outfall is not now permitted, this research plan has been prepared to show what could be learned with a full scale experimental sludge discharge of 150 dry tons/day by the County Sanitation Districts of Orange County into deep water (over 1000 feet). To provide a wide range of inputs and evaluation, a broad-based Research Planning Committee was established to advise the Environmental Quality Laboratory on the overall content and details of the research plan. Two meetings were held at EQL on: March 4-5, 1982: The entire Committee July 19-20, 1982: A working subgroup of the Committee The entire Committee is listed in Appendix B, with footnotes to indicate meeting attendance. Those unable to come to a meeting were asked to comment on the drafts by mail or telephone. We gratefully acknowledge the members of the Research Planning Committee for their generous help in formulating the research tasks and reviewing report drafts

Understanding Local Residents’ Contribution to Online Travel Communities

By exploring online helping behavior, this study developed and tested a conceptual framework to understand local residents’ contribution to online travel communities. The conceptual framework was established based on the attribution-empathy theory and the social identity theory. A web-based survey was conducted in the online travel community “CouchSurfing”, and a total of 377 cases were included in the analysis. The findings indicate that the conceptual framework is statistically significant, and variables of social identity of local resident, attachment to the online community, participation in the online community and personal distress are significant predictors of helping behavior. Based on the results, both theoretical and practical implications are discussed