2,532 research outputs found

    Survey and analysis of research on supersonic drag-due-to-lift minimization with recommendations for wing design

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    A survey of research on drag-due-to-lift minimization at supersonic speeds, including a study of the effectiveness of current design and analysis methods was conducted. The results show that a linearized theory analysis with estimated attainable thrust and vortex force effects can predict with reasonable accuracy the lifting efficiency of flat wings. Significantly better wing performance can be achieved through the use of twist and camber. Although linearized theory methods tend to overestimate the amount of twist and camber required for a given application and provide an overly optimistic performance prediction, these deficiencies can be overcome by implementation of recently developed empirical corrections. Numerous examples of the correlation of experiment and theory are presented to demonstrate the applicability and limitations of linearized theory methods with and without empirical corrections. The use of an Euler code for the estimation of aerodynamic characteristics of a twisted and cambered wing and its application to design by iteration are discussed

    BT COTTON REFUGE POLICY

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    Since cotton producers do not own legal rights to kill insect populations that are susceptible to insecticides, individual producers may have no incentive to account for future, insecticide-resistance productivity losses arising from their pest-management decisions. As a result, the collective actions of producers may increase the rate of resistance development relative to the rate that maximizes social welfare. Concerns regarding insect-pest development of resistance to Bt cotton prompted the Environmental Protection Agency to establish legal limits on the proportion of total acres individual producers may plant, representing the first attempt to regulate the development of insecticide resistance and the first instance of the use of refuge as a policy instrument. Ever since Carlson and Castle first pointed out the resource characteristics of insecticide susceptibility, pest management in the presence of increasing resistance has been viewed as an exhaustible resource allocation problem, and many studies have examined efficient insecticide use in this setting. Resistance management studies found in the economics literature, however, have examined single-insect single-insecticide problems almost exclusively. The majority of genetic and entomological studies have followed suit. Since cotton producers routinely use multiple insecticides and insecticide mixtures to manage multiple insect pests, and since simulation and empirical evidence suggests that toxin mixtures can affect the rate of resistance development to component toxins, the standard model may not be well suited for the examination of refuge policies under cotton production settings. Static refuge policies that maximize the present value of profit flows attainable by producers over five- and 10-year planning horizons are examined using a deterministic, operational model that accounts for short- and long-run features of production and resistance development. The model accounts for the development of resistance in two cotton insect pests to Bt cotton and a popular conventional insecticide, and relationships between refuge policy, insecticide resistance, producer profit and producer behavior in Louisiana. The model is used to examine relationships between resistance simulation model parameters and refuge policies and comparative advantages between treated and untreated refuge policies.Agricultural and Food Policy,

    Brake Specific Fuel Consumption (BSFC) in Gasoline Powered Cars

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    The goal of this experiment was to determine which driving behaviors result in the highest fuel efficiency for a given trip. We collected data for speed (MPH), engine speed (RPM), engine power (Torque/LOD), and fuel consumption (MPG) using the ScanGauge II

    The Mid-IR Spectral Effects of Darkening Agents and Porosity on the Silicate Surface Features of Airless Bodies

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    We systematically measured the mid-IR spectra of different mixtures of three silicates (antigorite, lizardite, and pure silica) with varying effective porosities and amounts of darkening agent (iron oxide and carbon). These spectra have broad implications for interpretation of current and future mission data for airless bodies, as well as for testing the capabilities of new instruments. Serpentines, such as antigorite and lizardite, are common to airless surfaces, and their mid-IR spectra in the presence of darkening agents and different surface porosities would be typical for those measured by spacecraft. Silica has only been measured in the plumes of Enceladus and presents exciting possibilities for other Saturn-system surfaces due to long range transport of E-ring material. Results show that the addition of the IR-transparent salt, KBr, to simulate surface porosity affected silicate spectra in ways that were not predictable from linear mixing models. The strengthening of silicate bands with increasing pore space, even when only trace amounts of KBr were added, indicates that spectral features of porous surfaces are more detectable in the mid-IR. Combining iron oxide with the pure silicates seemed to flatten most of the silicate features, but strengthened the reststrahlen band of the silica. Incorporating carbon with the silicates weakened all silicate features, but the silica bands were more resistant to being diminished, indicating silica may be more detectable in the mid-IR than the serpentines. We show how incorporating darkening agents and porosity provides a more complete explanation of the mid-IR spectral features previously reported on worlds such as Iapetus

    Direct and indirect lactate oxidation in trained and untrained men.

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    Lactate has been shown to be an important oxidative fuel. We aimed to quantify the total lactate oxidation rate (Rox) and its direct vs. indirect (glucose that is gluconeogenically derived from lactate and subsequently oxidized) components (mg·kg(-1)·min(-1)) during rest and exercise in humans. We also investigated the effects of endurance training, exercise intensity, and blood lactate concentration ([lactate]b) on direct and indirect lactate oxidation. Six untrained (UT) and six trained (T) men completed 60 min of constant load exercise at power outputs corresponding to their lactate threshold (LT). T subjects completed two additional 60-min sessions of constant load exercise at 10% below the LT workload (LT-10%), one of which included a lactate clamp (LC; LT-10%+LC). Rox was higher at LT in T [22.7 ± 2.9, 75% peak oxygen consumption (Vo2peak)] compared with UT (13.4 ± 2.5, 68% Vo2peak, P < 0.05). Increasing [lactate]b (LT-10%+LC, 67% Vo2peak) significantly increased lactate Rox (27.9 ± 3.0) compared with its corresponding LT-10% control (15.9 ± 2.2, P < 0.05). Direct and indirect Rox increased significantly from rest to exercise, and their relative partitioning remained constant in all trials but differed between T and UT: direct oxidation comprised 75% of total lactate oxidation in UT and 90% in T, suggesting the presence of training-induced adaptations. Partitioning of total carbohydrate (CHO) use showed that subjects derived one-third of CHO energy from blood lactate, and exogenous lactate infusion increased lactate oxidation significantly, causing a glycogen-sparing effect in exercising muscle

    Investigating the Portrayal and Influence of Sustainability Claims in an Environmental Advertising Context

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    The ability of consumer judges to identify sustainable messages in environmental advertising and the effect of these messages is explored. A content analysis provides insight into these judges’ perceptions of the depth of environmental advertising messages. An experiment investigates the influence of sustainable messages and includes collection of cognitive response data to evaluate the cognitive dimension of sustainability messages. Content analysis results suggest that sustainability messages may influence how environmental advertisements are perceived. These findings are supported by the cognitive response data, which shows cognitive differences across advertisements, and the experimental manipulation that suggests sustainable ads may be more involving to consumers

    Comparison Of Knee Moments And Landing Patterns During A Lateral Cutting Maneuver: Shod Vs. Barefoot

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    Non-contact anterior cruciate ligament (ACL) injuries often occur during lateral cutting maneuvers where extension, adduction, and external rotation create high loads on the ACL. The aim of this study was to examine knee moments and foot strike patterns during lateral cutting while shod (SD) and barefoot (BF). Fifteen NCAA Division III athletes (7 female and 8 male; age 20.2 ± 1.5 yr; mass 71.5 ± 11.3 kg; height, 1.7 ± .06 m) without lower limb pathologies were analyzed during 5 trials of 45 degree lateral cutting maneuvers for each limb in both BF and SD conditions with the approach speed at 4.3 m/s. Kinetic and kinematic data were collected using an eight-camera motion capture system and a force plate with collection rates at 240 Hz and 2400Hz respectively. Paired t-tests were used to determine differences conditions. The SD condition produced a significantly (p\u3c0.05) greater peak adduction moment and cutting while BF caused a more anterior foot strike. Lateral cutting while BF places no more stress on the ACL than when SD. Our findings suggest that lateral cutting maneuvers while BF will not increase stress on the ACL
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