Aerodynamic performance of a 1.25-pressure-ratio axial-flow fan stage

Aerodynamic design parameters and overall and blade-element performances of a 1.25-pressure-ratio fan stage are reported. Detailed radial surveys were made over the stable operating flow range at rotative speeds from 70 to 120 percent of design speed. At design speed, the measured stage peak efficiency of 0.872 occurred at a weight flow of 34.92 kilograms per second and a pressure ratio of 1.242. Stage stall margin is about 20 percent based on the peak efficiency and stall conditions. The overall peak efficiency for the rotor was 0.911. The overall stage performance showed no significant change when the stators were positioned at 1, 2, or 4 chords downstream of the rotor

Aerodynamic performance of a 1.35-pressure-ratio axial-flow fan stage

The overall blade element performances and the aerodynamic design parameters are presented for a 1.35-pressure-ratio fan stage. The fan stage was designed for a weight flow of 32.7 kilograms per second and a tip speed of 302.8 meters per second. At design speed the stage peak efficiency of 0.879 occurred at a pressure ratio of 1.329 and design flow. Stage stall margin was approximately 14 percent. At design flow rotor efficiency was 0.94 and the pressure ratio was 1.360

Stalled and stall-free performance of axial-flow compressor stage with three inlet-guide-vane and stator-blade settings

The performance of the first stage of a transonic, multistage compressor was mapped over a range of inlet-guide-vane and stator-blade settings. Both stall-free and deep-stall performance data were obtained. For the settings tested, as stall was encountered and flow was further reduced, a relatively sharp drop in pressure ratio occurred and was followed by a continuing but more gradual reduction in pressure ratio with reduced flow. The position of the stall line on the map of pressure ratio against equivalent weight flow was essentially unaffected over the range of inlet-guide-vane and stator-blade settings

Performance of inlet stage of transonic compressor

The overall and blade-element performances are presented over the stable flow operating range of the stage at the design tip speed of 426 m/sec. Stage peak efficiency of 0.83 was obtained at a weight flow of 28.8 kg/sec and a pressure ratio of 1.52. The stall margin for the stage was 8 percent based on weight flow and pressure ratio at peak efficiency and stall. The rotor appears to be stalling prematurely as evidenced by high rotor tip losses

Photosynthetic and respiratory responses of the mangrove-associated red algae, Bostrychia radicans and Caloglossa leprieurii

Net photosynthetic and respiratory rates of two estuarine algae, Bostrychia radicans Mont. and Caloglossa leprieurii (Mont.) J. Ag. collected from the Mgeni Estuary mangrove swamp, were studied. Both species are intertidal and common on Avicennia marina (Forssk.) Vierh. pneumatophores. Maximum photosynthetic rates of B. radicans were evident between 25% and 58% desiccation. Respiratory rates were constant up to 58% desiccation and decreased thereafter. C. leprieurii showed highest photosynthetic rates under submerged conditions, whilst respiratory rates were highest under saturated conditions. Both species showed increases in photosynthetic and respiratory rates with increase in temperature. Photosynthetic rates peaked at 32°C to 37°C, whilst respiratory rates peaked at 37°C. With increases in light intensity, maximum photosynthetic rates of C. leprieurii and B. radicans occurred at 140 to 225 μE m−2 s−1 and 225 to 550 μE m−2 s−1 respectively. Both species were tolerant of a range of salinities. The ecological implications of these results are discussed

Data dependent energy modelling for worst case energy consumption analysis

Safely meeting Worst Case Energy Consumption (WCEC) criteria requires accurate energy modeling of software. We investigate the impact of instruction operand values upon energy consumption in cacheless embedded processors. Existing instruction-level energy models typically use measurements from random input data, providing estimates unsuitable for safe WCEC analysis. We examine probabilistic energy distributions of instructions and propose a model for composing instruction sequences using distributions, enabling WCEC analysis on program basic blocks. The worst case is predicted with statistical analysis. Further, we verify that the energy of embedded benchmarks can be characterised as a distribution, and compare our proposed technique with other methods of estimating energy consumption

Supersonic through-flow fan design

The NASA Lewis Research Center has embarked on a program to experimentally prove the concept of a supersonic through-flow fan which is to maintain supersonic velocities throughout the compression system with only weak shock-wave flow losses. The detailed design of a supersonic through-flow fan and estimated off-design performance with the use of advanced computational codes are described. A multistage compressor facility is being modified for the newly designed supersonic through-flow fan and the major aspects of this modification are briefly described

USE OF PLASTIC DRIFT CARDS AS INDICATORS OF POSSIBLE DISPERSAL OF PROPAGULES OF THE MANGROVE AVICENNIA MARINA BY OCEAN CURRENTS

Plastic drift cards with the same buoyancy as propagules of Avicennia marina (Forssk.) Vierh. were used as an indicator of possible mangrove dispersal by ocean currents. The cards were dropped from an aircraft into the sea at the mouths of the Mhlathuze River off Richards Bay, the Mgeni River off Durban and the Nxaxo-Ngqusi rivers off Wavecrest on the east coast of South Africa. Details of the time and locality of strandings were recorded from cards returned. Of the 4 500 cards released, 133 (8.9&#37), 146 (9.7&#37) and 280 (18.7&#37) were returned respectively from the above locations. The high returns from Wavecrest were attributable to cards being washed ashore in the immediate vicinity of the dropping point. A high percentage of the cards dropped at Durban were transported northwards by the inshore counter-current. Approximately 68 and 32&#37 of the cards recovered for Richards Bay and Durban respectively were transported by the Agulhas Current and were stranded farther south along the East and South-East coasts. Cards that reached the Agulhas mixing area were deposited ashore on the Cape Peninsula and the West Coast (3&#37), or were transported either across the Atlantic Ocean to South America or the Indian Ocean to Australasia (4&#37). Estimated transport rates of cards to South America and Australasia were similar to previously published values. The results indicate that the northern estuaries could provide propagative material over a considerable portion of the South African coast, which could result in a wider distribution of mangroves in the Eastern Cape.Afr. J. mar. Sci. 25: 169–17

Virtues, ecological momentary assessment/intervention and smartphone technology

Virtues, broadly understood as stable and robust dispositions for certain responses across morally relevant situations, have been a growing topic of interest in psychology. A central topic of discussion has been whether studies showing that situations can strongly influence our responses provide evidence against the existence of virtues (as a kind of stable and robust disposition). In this review, we examine reasons for thinking that the prevailing methods for examining situational influences are limited in their ability to test dispositional stability and robustness; or, then, whether virtues exist. We make the case that these limitations can be addressed by aggregating repeated, cross-situational assessments of environmental, psychological and physiological variables within everyday life—a form of assessment often called ecological momentary assessment (EMA, or experience sampling). We, then, examine how advances in smartphone application (app) technology, and their mass adoption, make these mobile devices an unprecedented vehicle for EMA and, thus, the psychological study of virtue. We, additionally, examine how smartphones might be used for virtue development by promoting changes in thought and behavior within daily life; a technique often called ecological momentary intervention (EMI). While EMA/I have become widely employed since the 1980s for the purposes of understanding and promoting change amongst clinical populations, few EMA/I studies have been devoted to understanding or promoting virtues within non-clinical populations. Further, most EMA/I studies have relied on journaling, PDAs, phone calls and/or text messaging systems. We explore how smartphone app technology provides a means of making EMA a more robust psychological method, EMI a more robust way of promoting positive change, and, as a result, opens up new possibilities for studying and promoting virtues