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

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

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

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

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

Reconstructing the salinity and environment of the Limfjord and Vejlerne Nature Reserve, Denmark, using a diatom model for brackish lakes and fjords

Diatoms in surface sediments from a data set of 27 brackish lakes and nine fjords in Jutland, Denmark (range 0.2 – 31 g·L–1 total dissolved solids (TDS)), were analysed using multivariate methods to determine response to measured parameters (depth, total phosphorus (TP), total nitrogen (TN), TN/TP, salinity, water body type). Water body type, salinity, depth and TP together explained 25.3% of the variation in the diatom data and were all independently significant predictors. A diatom–salinity model (r2 jack = 0.887, root mean square error of prediction = 0.246 log salinity, g·L–1) was developed from the 36 sample training set and applied to fossil diatom assemblages in three sediment cores from the east Vejlerne wetland, Denmark, a nature reserve created after the damming of an embayment of the polyhaline Limfjord (~26 g·L–1 TDS) in the late 19th century. The diatom-inferred salinity reconstructions reflect the known salinity history of the Limfjord and the freshwater–subsaline Vejlerne lakes, and appear sensitive to documented North Sea storms in the 16th and 17th centuries, which had major impacts on the brackish Limfjord herring fishery. Diatom–salinity models may be useful tools in long-term studies of coastal and estuarine areas to test hypotheses concerning aquatic resources and ecological, hydrographic, and cultural change