A simulation study of active feedback supression of dynamic response in helicopter rotor blades

A parameter study is presented for active feedback control applied to a helicopter rotor blade during forward flight. The study was performed on an electromechanical apparatus which included a mechanical model rotor blade and electronic analog simulation of interaction between blade deflections and aerodynamic loading. Blade response parameters were obtained for simulated vortex impinging at the blade tip at one pulse per revolution, and for a pulse which traveled from the blade tip toward its root. Results show that the response in a 1 - 10-per-rev frequency band is diminished by the feedback action, but at the same time responses at frequencies above 10-per-rev become increasingly more prominent with increased feedback amplitude, and can even lead to instability at certain levels. It appears that the latter behavior results from limitations of the laboratory simulation apparatus, rather than genuine potential behavior for a prototype helicopter

Some Notes on Liquid Sloshing in Compartmented Cylindrical Tanks Technical Report No. 1

Frequencies and total force response in rigid cylindrical tanks comparted into sectors by vertical walls and excited in translation to study liquid sloshin

Herders and Wetland Degradation in Northern Cameroon

Livestock rearing in Northern Cameroon is carried out under two majors systems: the nomadic and the transhumance production systems (Pamo & Pamo, 1991). Nomadism is the practice of wandering from place to place, while transhumance involves seasonal displacement of flocks from one area to another by herders. These production systems involved large grazing areas, which may encompass different ecosystems. The Yaére, the only wetland of the northern Cameroon, is the major dry season grazing lands for livestock and wildlife. The main characteristic of this wetland is that the whole area is excluded from grazing during the growing season as a result of large scale flooding. Thus the major forage species (i.e. Echinochloa pyramidalis, Oryza longistaminata, Hyparrhenia rufa, Echinochloa stagnina) can set seed thereby ensuring their continued dispersal, establishment, and survival during the subsequent rainy season. In 1979, an upstream dam of 28 km with an additional 20 km embankment along the Logone river was build to store water for a rice irrigation project. This suppressed flooding over some 60 000 ha, and seriously affected the hydrological regime over another 200 000 ha. Major perennial forage species were gradually replaced by less palatable annual species such as Sorghum arundinaceum. This paper investigates how herders coped with the induced degradation of this dry season grazing land

Herders and Wetland Degradation in Northern Cameroon

Livestock rearing in Northern Cameroon is carried out under two majors systems: the nomadic and the transhumance production systems (Pamo & Pamo, 1991). Nomadism is the practice of wandering from place to place, while transhumance involves seasonal displacement of flocks from one area to another by herders. These production systems involved large grazing areas, which may encompass different ecosystems. The Yaére, the only wetland of the northern Cameroon, is the major dry season grazing lands for livestock and wildlife. The main characteristic of this wetland is that the whole area is excluded from grazing during the growing season as a result of large scale flooding. Thus the major forage species (i.e. Echinochloa pyramidalis, Oryza longistaminata, Hyparrhenia rufa, Echinochloa stagnina) can set seed thereby ensuring their continued dispersal, establishment, and survival during the subsequent rainy season. In 1979, an upstream dam of 28 km with an additional 20 km embankment along the Logone river was build to store water for a rice irrigation project. This suppressed flooding over some 60 000 ha, and seriously affected the hydrological regime over another 200 000 ha. Major perennial forage species were gradually replaced by less palatable annual species such as Sorghum arundinaceum. This paper investigates how herders coped with the induced degradation of this dry season grazing land

Effect of CO2 enrichment on phytoplankton photosynthesis in the North Atlantic sub-tropical gyre.

The effects of changes in CO2 concentration in seawater on phytoplankton community structure and photosynthesis were studied in the North Atlantic sub-tropical gyre. Three shipboard incubations were conducted for 48 h at ∼760 ppm CO2 and control (360 ppm CO2) from 49°N to 7°N during October and November 2010. Elevated CO2 caused a decrease in pH to ∼7.94 compared to ∼8.27 in the control. During one experiment, the biomass of nano- and picoeukaryotes increased under CO2 enrichment, but primary production decreased relative to the control. In two of the experiments the biomass was dominated by dinoflagellates, and there was a significant increase in the maximum photosynthetic rate (PmB) and light-limited slope of photosynthesis (αB) at CO2 concentrations of 760 ppm relative to the controls. 77 K emission spectroscopy showed that the higher photosynthetic rates measured under CO2 enrichment increased the connection of reversible photosystem antennae, which resulted in an increase in light harvesting efficiency and carbon fixation

West African Dwarf Goat Response to Supplementary Feeding in Cameroon

The production of the West African Dwarf goat (WADG) in Cameroon is very low, because of lack of proper nutrition. Nitrogen content is generally very low and fibre content is high, both in the grass and the crop residues which form the basis of their diet particularly during the dry season. Supplementation of these roughages is a promising way of alleviating nutrient deficiencies. Different types of supplementary feeding have been advocated to boost goat production (Leng, 2003), of which supplementary feeding with leguminous tree leaves is of high merit. The present study was undertaken to evaluate the effects of supplementary feeding of Calliandra calothyrsus and Leucaena leucocephala leaves on growth and reproduction of WADG

Pengaruh Internal Marketing Dan Kualitas Pelayanan BPJS Kesehatan Terhadap Kinerja Melalui Kepuasan Dokter Di RSUD Ulin Banjarmasin)

Internal marketing dan kualitas pelayanan BPJS Kesehatan mempengaruhi kepuasan dokter yang selanjutnya menjadi faktor penentu kinerja dokter. Tujuan dari penelitian ini adalah mengalisis pengaruh internal marketing dan kualitas pelayanan BPJS Kesehatan terhadap kinerja dokter melalui kepuasan dokter di RSUD Ulin Banjarmasin. Jenis penelitian ini adalah analitik dengan desain cross sectional. Pengumpulan data dilakukan secara angket dengan menggunakan kuisioner terstruktur. Subjek penelitian adalah semua dokter spesialis penyakit anak, penyakit dalam,ilmu bedah serta kandungan dan kebidanan yang bertugas di RSUD Ulin Banjarmasin yang memenuhi kriteria inklusi sebanyak 52 orang. Analisis data dilakukan dengan korelasi Pearson dan regresi linear berganda. Hasil penelitian menunjukkan ada korelasi antara internal marketing dengan kepuasan dokter (r = 0,584, p = 0,000), antara kualitas pelayanan BPJS Kesehatan dan kepuasan dokter (r = 0,499, p = 0,001), antara kepuasan dokter dan kinerja dokter (r = 0,583, p = 0,0001). Hasil penelitian dengan analisis regresi linear berganda menunjukkan bahwa internal marketing dan kualitas pelayanan BPJS Kesehatan memiliki kontribusi pengaruh terhadap kepuasan dokter sebesar 44,6% sedangkan yang 55,4% dijelaskan faktor lain. Kepuasan dokter memiliki kontribusi pengaruh terhadap kinerja dokter sebesar 32,7% sedangkan yang 67,3% dijelaskan variabel lain diluar model. Disimpulkan bahwa internal marketing dan kualitas pelayanan berpengaruh terhadap kepuasan dokter yang selanjutnya berpengaruh terhadap kinerja dokter. Disarankan kepada BPJS Kesehatan untuk memperbaiki sistem pembiayaan INA-cbg's dan melakukan sosialisasi peraturan dan Perundangan dengan lebih baik