Pengendali Motor Induksi 1 Fasa Dengan Metode PWM Sinusoida Berbasis Mikrokontroler 68HC11

Pada pengendalian motor induksi yang dilakukan secara konvensional tidak diperoleh pengaturan yang kontinyu dan linier, sehingga perlu dilakukan penelitian tentang pengendalian motor induksi dengan teknik inverter. Penelitian ini bertujuan melakukan pengembangan dan evaluasi unjuk kerja pengendalian motor induksi satu fasa dengan metode PWM sunusoida berbasis mikrokontroler. Pengendalian menggunakan rangkaian jembatan inverter jenis PWMVSI (DC-Link inverter) dengan teknik modulasi PWM menggunakan mikrokontroler 68HC11E9, dan diharapkan dapat menggerakkan motor induksi pada kecepatan yang berbeda-beda. Pada penelitian ini digunakan motor induksi satu fasa Z-406, 220 Volt, 50-60 Hz, 125W. Penelitian dimulai dengan pembuatan perangkat keras berupa inverter menggunakan MOSFET sebagai komponen pensaklaran dan diteruskan dengan menyusun rangkaian penggerak inverter satu fasa. Pola sinyal PWM sinusoida dibentuk dengan teknik perhitungan lima modulasi PWM yang berbeda. Dari pola gelombang tersebut dibuat program pembangkit pulsa PWM satu fasa dan perangkat pendukungnya. Selanjutnya dilakukan pengamatan bentuk gelombang PWM keluaran MCU, tegangan, arus keluaran inverter dan mengukur kecepatan putar motor untuk lima indeks modulasi, yaitu (1), (0,81), (0,59), (0,37), dan (0,15). Hasil penelitian menunjukkan bahwa pengaturan kecepatan putar motor induksi untuk frekuensi tetap 50 Hz dengan 5 indeks modulasi berbeda dengan metode PWM sinusoida berbasis mikrokontroler dapat menghasilkan putaran motor yang bervariasi

Stable isotope signatures of Holocene syngenetic permafrost trace seabird presence in the Thule District (NW Greenland)

Holocene permafrost from ice wedge polygons in the vicinity of large seabird breeding colonies in the Thule District, NW Greenland, was drilled to explore the relation between permafrost aggradation and seabird presence. The latter is reliant on the presence of the North Water Polynya (NOW) in the northern Baffin Bay. The onset of peat accumulation associated with the arrival of little auks (Alle alle) in a breeding colony at Annikitisoq, north of Cape York, is radiocarbon-dated to 4400 cal BP. A thick-billed murre (Uria lomvia) colony on Appat (Saunders Island) in the mouth of the Wolstenholme Fjord started 5650 cal BP. Both species provide marine-derived nutrients (MDNs) that fertilize vegetation and promote peat growth. The geochemical signature of organic matter left by the birds is traceable in the frozen Holocene peat. The peat accumulation rates at both sites are highest after the onset, decrease over time, and were about 2-times faster at the little auk site than at the thick-billed murre site. High accumulation rates induce shorter periods of organic matter (OM) decomposition before it enters the perennially frozen state. This is seen in comparably high C=N ratios and less depleted 13C, pointing to a lower degree of OM decomposition at the little auk site, while the opposite pattern can be discerned at the thick-billed murre site. Peat accumulation rates correspond to 15N trends, where decreasing accumulation led to increasing depletion in 15N as seen in the little-auk-related data. In contrast, the more decomposed OM of the thick-billed murre site shows almost stable 15N. Late Holocene wedge ice fed by cold season precipitation was studied at the little auk site and provides the first stable-water isotopic record from Greenland with mean 18O of 8:00:8, mean D of 36:25:7, mean d excess of 7:70:7, and a 18O-D slope of 7.27, which is close to those of the modern Thule meteoric water line. The syngenetic ice wedge polygon development is mirrored in testacean records of the little auk site and delineates polygon low-center, dry-out, and polygon-high-center stages. The syngenetic permafrost formation directly depending on peat growth (controlled by bird activity) falls within the period of neoglacial cooling and the establishment of the NOW, thus indirectly following the Holocene climate trends

R script Gonzalez Bergonzoni from Small birds, big effects: the little auk (<i>Alle alle</i>) transforms high Arctic ecosystems

In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk (<i>Alle alle</i>), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios (<i>δ</i>¹⁵N and <i>δ</i>¹³C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical–chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevated <i>δ</i>¹⁵N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algal <i>δ</i>¹⁵N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland

Dataisotopes from Small birds, big effects: the little auk (<i>Alle alle</i>) transforms high Arctic ecosystems

In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk (<i>Alle alle</i>), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios (<i>δ</i>¹⁵N and <i>δ</i>¹³C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical–chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevated <i>δ</i>¹⁵N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algal <i>δ</i>¹⁵N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland

Supplementary Methods S1 from Small birds, big effects: the little auk (<i>Alle alle</i>) transforms high Arctic ecosystems

In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk (<i>Alle alle</i>), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios (<i>δ</i>¹⁵N and <i>δ</i>¹³C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical–chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevated <i>δ</i>¹⁵N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algal <i>δ</i>¹⁵N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland

NOW-isotopic summary from Small birds, big effects: the little auk (<i>Alle alle</i>) transforms high Arctic ecosystems

In some arctic areas, marine-derived nutrients (MDN) resulting from fish migrations fuel freshwater and terrestrial ecosystems, increasing primary production and biodiversity. Less is known, however, about the role of seabird-MDN in shaping ecosystems. Here, we examine how the most abundant seabird in the North Atlantic, the little auk (<i>Alle alle</i>), alters freshwater and terrestrial ecosystems around the North Water Polynya (NOW) in Greenland. We compare stable isotope ratios (<i>δ</i>¹⁵N and <i>δ</i>¹³C) of freshwater and terrestrial biota, terrestrial vegetation indices and physical–chemical properties, productivity and community structure of fresh waters in catchments with and without little auk colonies. The presence of colonies profoundly alters freshwater and terrestrial ecosystems by providing nutrients and massively enhancing primary production. Based on elevated <i>δ</i>¹⁵N in MDN, we estimate that MDN fuels more than 85% of terrestrial and aquatic biomass in bird influenced systems. Furthermore, by using different proxies of bird impact (colony distance, algal <i>δ</i>¹⁵N) it is possible to identify a gradient in ecosystem response to increasing bird impact. Little auk impact acidifies the freshwater systems, reducing taxonomic richness of macroinvertebrates and truncating food webs. These results demonstrate that the little auk acts as an ecosystem engineer, transforming ecosystems across a vast region of Northwest Greenland