Variable-speed Generators with Flux Weakening

A cost-competitive, permanent-magnet 20 kW generator is designed such that the following criteria are satisfied: an (over) load capability of at least 30 kW over the entire speed range of 60-120 rpm, generator weight of about 550 lbs with a maximum radial stator flux density of 0.82 T at low speed, unity power factor operation, acceptably small synchronous reactances and operation without a gear box. To justify this final design four different generator designs are investigated: the first two designs are studied to obtain a speed range from 20 to 200 rpm employing rotor field weakening, and the latter two are investigated to obtain a maximum speed range of 40 to 160 rpm based on field weakening via the stator excitation. The generator reactances and induced voltages are computed using finite element/difference solutions. Generator losses and efficiencies are presented for all four designs at rated temperature of Tr=120C

Arkansas Soybean Performance Tests 2018

Soybean variety and strain performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Crop Variety Improvement Program. The tests provide information to companies developing varieties and/or marketing seed within the State, and aid the Arkansas Cooperative Extension Service in formulating variety recommendations for soybean producers

Clearing sandplain country

THE greatest scope for development of new land in Western Australia lies in the millions of acres of sandplain country along the west and south coasts and to a lesser extent in the Newdegate area. With the development, or at least alienation, of the South-West and the wheatbelt nearing completion, attention has been focused on these tracts of sandplain country

Light land development in the West Midlands

Although it has not received the widespread publicity which has attended land settlement schemes on the south coastal plain some very successful light land development has taken place in the West Midlands during the past 10 years. Large areas of what was once unattractive scrub country are now carrying highly productive pastures and the progress made by Mr. J. W. White at Badgingarra is an example of what may be achieved in this district by using proven techniques

Barrel Medic for wheatbelt pastures - Demonstrations show promise

Investigations with Barrel Medic (Medicago tribuloides) have indicated that this has a wide range of usefulness as a leguminous pastoral plant for the heavier soils those areas receiving less than 18 inches of rainfall annually There has been a continued emphasis on improved pasture as the basis for better and more productive rotations and the outstanding part played by subterranean clover in utilising large areas of light sandplain in the higher rainfall districts is well known. Barrel medic (or Barrel Clover as it is sometimes called) should fill a somewhat similar position under the conditions for which it is suited

Hot Oil Eggs- Do They Make Good Cakes?

In their search for a way to keep eggs fresh and maintain high quality during long commercial storage, researchers have come up with a new method called hot oil or thermostabilization. But do the eggs keep their culinary properties? Here are some of the answers from research

Stocking rate and pasture management

FARMERS west of the Great Southern Railway, raising sheep and beef cattle, frequently associate soil deficiencies with difficulties in holding sub. clover in their pastures. Field observations and some trials in those districts indicate that in many paddocks the problem arises through undergrazing rather than a deficiency in the soil

Holiday Foods with a Honey Flavor

Substituting honey for some of the sugar normally used in baking keeps food moist longer, gives a unique flavor, and prevents crystallization

Large K-exciton dynamics in GaN epilayers: the non-thermal and thermal regime

We present a detailed investigation concerning the exciton dynamics in GaN epilayers grown on c-plane sapphire substrates, focussing on the exciton formation and the transition from the nonthermal to the thermal regime. The time-resolved kinetics of LO-phonon replicas is used to address the energy relaxation in the excitonic band. From ps time-resolved spectra we bring evidence for a long lasting non-thermal excitonic distribution which accounts for the rst 50 ps. Such a behavior is con rmed in di erent experimental conditions, both when non-resonant and resonant excitation are used. At low excitation power density the exciton formation and their subsequent thermalization is dominated by impurity scattering rather than by acoustic phonon scattering. The estimate of the average energy of the excitons as a function of delay after the excitation pulse provides information on the relaxation time, which describes the evolution of the exciton population to the thermal regime.Comment: 9 pages,8 figure