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Tytuł:
Study of delta/polygon-connected transformer-based 36-pulse ac-dc converter for power quality improvement
Autorzy:
Abdollahi, R.
Powiązania:
https://bibliotekanauki.pl/articles/140490.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
jakość energii
prostownik 36-pulsowy
bezpośredni moment obrotowy silnika indukcyjnego sterowanego napędem
AC-DC converter
delta/polygon transformer
power quality
direct torque controlled induction motor drive (DTCIMD)
Opis:
Design of a delta/polygon-connected autotransformer based 36-pulse ac-dc converter is presented in this paper. The 36-pulse topology is obtained via two paralleled eighteen-pulse ac-dc converters each of them consisting of a nine-phase (nine-leg) diode bridge rectifier. For independent operation of paralleled diode-bridge rectifiers, two interphase transformers (IPT) is designed and implemented. A transformer is designed to supply the rectifier. The design procedure of magnetics is in a way such that makes it suitable for retrofit applications where a six-pulse diode bridge rectifier is being utilized. The proposed structure has been implemented and simulated using Matlab/Simulink software under different load conditions. Simulation results confirmed the significant improvement of the power quality indices (consistent with the IEEE-519 standard requirements) at the point of common coupling. Furthermore, near unity power factor is obtained for a wide range of DTCIMD operation. A comparison is made between 6-pulse and proposed converters from view point of power quality indices. Results show that input current total harmonic distortion (THD) is less than 4% for the proposed topology at variable loads.
Źródło:
Archives of Electrical Engineering; 2012, 61, 2; 277-292
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polyphase Comb Filter Based on Dispatching Input Bit-stream and Interlaying Multiplexer Techniques for Sigma-Delta ADCs
Autorzy:
Abdollahvand, S.
Goes, J.
Paulino, N.
Gomes, L.
Powiązania:
https://bibliotekanauki.pl/articles/397961.pdf
Data publikacji:
2012
Wydawca:
Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
Tematy:
filtr decymacyjny
filtr wielofazowy
modulator sigma-delta
field-programmable gate array
FPGA
decimation filter
Polyphase Comb filter
sigma-delta modulators
field programmable gate array (FPGA)
Opis:
This paper describes a new design approach for implementing a Polyphase Comb Filter (PCF) based on dispatching input bit-stream and interlaying multiplexer techniques. In order to make our solution more energy efficient in comparison with prior art, we start with a detailed analysis of the drawbacks and advantages of the existing classical techniques. A new structure based on a novel SINC3 design is proposed. This new design uses a controller unit to activate one sub-filter in each specific time interval. As a consequence, no input registers and switches are required. Since this decimation filter is working with a single-bit output bit-stream, the required multiplication function can be simply done by using interlaying multiplexers (MUXs). By interlaying different levels of MUXs along with the navigation of the input bit stream we can easily emulate the multiplication operation. The implementation in a Xilinx Spartan3 FPGA demonstrates the feasibility and hardware efficiency of our solution . The proposed new filter architecture can be readily applicable to any Sigma-Delta (ΣΔ) ADC with a single-bit output stream and it requires a reduced number of adders and registers when compared with the state-of-the-art approaches.
Źródło:
International Journal of Microelectronics and Computer Science; 2012, 3, 4; 152-158
2080-8755
2353-9607
Pojawia się w:
International Journal of Microelectronics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Channel dynamics and hydraulic geometry of two tropical deltaic catchments in Southern Nigeria
Autorzy:
Aisuebeogun, A. O.
Ezekwe, I. C.
Powiązania:
https://bibliotekanauki.pl/articles/294615.pdf
Data publikacji:
2014
Wydawca:
Stowarzyszenie Geomorfologów Polskich
Tematy:
Catchment morphometry
hydraulic processes
Sombreiro River
New Calabar River
Niger Delta
Opis:
This paper attempts to explain the channel processes and dynamics of two river systems running through a rapidly urbanizing humid tropical deltaic environment with visible threats from industrialization and pollution. Hydraulic processes and parameters were compared with established power function relations for hydraulic geometry and it was discovered that the fundamental relations between channel-geometry dimensions, velocity, and flow can be expressed for the catchments. Ten gauging stations in each catchment were studied and results showed that the studied catchments adjust their geometry to changing discharges. High values of coefficients of determination among variables indicated that much of the downstream variation in channel width to depth ratio can be accounted for by changes in discharge. Also in this study the width/depth ratio (F) was found to be related to the percentage of silt + clay (M) in channel perimeter and that downstream hydraulic-geometry relations are in general agreement with previously published hydraulic and channel adjustment data.
Źródło:
Landform Analysis; 2014, 27; 3-13
1429-799X
Pojawia się w:
Landform Analysis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sustainability, Corporate Community Engagement and Enterprise Development – Lessons from a Case Study in Emu-Ebendo Niger-Delta, Nigeria
Zrównoważenie, korporacyjne zaangażowanie społeczne i rozwój przedsiębiorstw – lekcja z Emu-Ebendo w delcie Nigru, Nigeria
Autorzy:
Ajide, O. E.
Strachan, P. A.
Russell, A.
Jones, D. R.
Powiązania:
https://bibliotekanauki.pl/articles/371199.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Komitet Człowiek i Środowisko PAN
Tematy:
community engagement
community enterprise development
sustainability
local content
Niger Delta
Nigeria
oil and gas
zaangażowanie społeczne
społeczny rozwój przedsiębiorstwa
zrównoważoność
lokalna zawartość
Delta Nigru
ropa i gaz
Opis:
Corporate community engagement remains an under researched area in sustainability debates. Presenting a case study, based on in-depth interviews and site visits, of how one indigenous company Energia Ltd has formed a strong partnership or bond with the Emu-Ebendo community in the oil rich Niger Delta, the dynamics of corporate community engagement are critically discussed. Evidence of how both the company and community has benefited from this relationship is presented. The case analysis concludes that the company has effectively utilised a clearer understanding of the culture of the host community, leading to a transformational relationship. The approach adopted by Energia Ltd in the Emu-Ebendo community is unique in context. The key conclusion reached is that community benefit funds and community enterprise development, as a derivative of corporate engagement, can play a transformational role in societal and economic development.
Kwestia korporacyjnego zaangażowania społecznego nie jest często podejmowana w ramach debat o rozwoju zrównoważonym. Lukę tę uzupełnia niniejsze studium przypadku, oparte na szczegółowych wywiadach i pracy w terenie. Pokazujemy, w jaki sposób kompania Energia Ltd wprowadziła zasadę partnerstwa, w wyniku której nawiązała się silna więź pomiędzy firmą a społecznością Emu-Ebendo zamieszkującą bogatą w ropę Deltę Nigru. Przedstawiono dowody, jakie korzyści odniosły zarówno kompania, jak i społeczność. Przeprowadzono analiza pokazuje, że firma efektywnie wykorzystała zasady wyznaczające ramy kultury lokalnej społeczności, co prowadziło do pozytywnych zmian odnoszących się do wzajemnej relacji. Podejście przyjęte przez Energia Ltd wobec społeczności Emu-Ebendo jest nowatorskie. Okazało się, że fundusze świadczeń społecznych i społeczny rozwój przedsiębiorstw, będące pochodną zaangażowania korporacyjnego, mogą odgrywać podstawową rolę w przemianach społecznego i ekonomicznego rozwoju.
Źródło:
Problemy Ekorozwoju; 2017, 12, 2; 59-67
1895-6912
Pojawia się w:
Problemy Ekorozwoju
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Channel characteristics and planform dynamics of the lower Niger River, Niger Delta Basin (1985–2015)
Autorzy:
Akana, Tombra
Adeigbe, Olubunmi
Powiązania:
https://bibliotekanauki.pl/articles/184736.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
delta
channel dynamics
avulsion
human activities
GIS
Niger River Valley
Opis:
This study used repeat satellite imagery and Geographic Information System analysis to assess the planform dynamics along the length of the lower Niger River Valley from Onitsha city to the coast between 1985 and 2015. The aim is to understand the altered dynamics and its plausible causes in this data-poor region. Analyses revealed that the Niger River has undergone change corresponding to enhanced instability in terms of an increased rate of erosion. In the study area, a change was observed from 3.7% of deposition in the first 10 years (1985–1995) to 3.9% of erosion in the next 10 years (1995–2005) and 4.7% of erosion in the last 10 years (2005–2015). Total erosion over the 30-year period (1985–2015) in the delta was calculated on 4.8%. The river channel has migrated toward the east in the upper and lower reaches while the mid-section of the channel is migrating towards the west. The east river bank is observed to be more unstable compared to west bank line through the study period. The maximum shifts identified were 3.35 km of deposition in 10 years (1985–1995), 3.31 km of erosion in the next 10 years (1995–2005), and another substantial erosional shift of 3.35 km in the next 10 years (2005–2015). Avulsion rates gradually moved from −42.1 m ∙ year−1 (1985–2005, segment F) to 100.2 m ∙ year−1 (1985–1995, segment D), large deposition in the first 10 years. Total avulsion rates of the delta in the last 30 years (1985–2015) has pointed on erosion (−2.2 m ∙ year−1). The altered dynamics observed would likely threaten the future of the fragile lower river system environment and raise concerns for operators with infrastructure within the Niger Delta.
Źródło:
Geology, Geophysics and Environment; 2019, 45, 4; 291-304
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biodiversity of zoosporic fungi in polluted water drainages across Niles Delta region, Lower Egypt
Autorzy:
Ali, E.H.
Powiązania:
https://bibliotekanauki.pl/articles/67773.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
biodiversity
zoosporic fungi
fungi
polluted water
water pollution
drainage
Nile River
Lower Egypt
Egypt
Nile Delta
Opis:
Thirty-four identified in addition to five unidentified species appertaining to ten genera of zoosporic fungi were identified and isolated from eighty four polluted water samples, which were randomly collected from different polluted sites of the water drainages along the Niles Delta in Lower Egypt. Baiting sesame seeds culture technique was employed at 20±2°C for the recovery of zoosporic fungi. The genera; Pythium and Saprolegnia (8 and 7 zoosporic fungal species, respectively) showed the broadest spectra of species diversity whereas Aqualinderella was only represented by one species (A. fermentans). Saprolegnia delica and Dictyuchus carpophorus(the greatest fungal populations) were the most dominant isolated zoosporic fungal species where they were highly occurred especially at the hyperpolluted waters with the heavy metals. These two species could be considered as indicators for the response of the structure and function of microbial communities for water pollution. Several zoosporic fungal species were rarely encountered. Both Aqualinderella fermentansand Pythium rostratumwere recovered in moderate frequency of occurrence. Water samples which had high concentrations in heavy metals were the poorest in the species diversity of zoosporic fungi. Despite that, fungal species belonging to the family Saprolegniaceaeflourished in hyper polluted water samples whilst those belonging to the family Pythiaceae predominated in more diluted water samples. Also, the prevalent species; S. delica andD. carpophoruswere not affected by heavy metals concentrations being as indicators for water pollution with the heavy metals. pH values of the polluted water samples had no influence on the occurrence of zoosporic fungi. Water samples characterized by high organic matter content and low total soluble salts were the richest in zoosporic fungal species.
Źródło:
Acta Mycologica; 2007, 42, 1
0001-625X
2353-074X
Pojawia się w:
Acta Mycologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review on delta wing against other wing designs for micro aerial vehicles
Autorzy:
Arun, M. P.
Satheesh, M.
Powiązania:
https://bibliotekanauki.pl/articles/2050259.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
micro aerial vehicles
wing
delta wing
materials
parameters
survey
Opis:
Wings play a vital role in the design of micro aerial vehicles (MAV), in view of aerodynamic performance, maneuverability and hovering capabilities of the vehicles. The wings are generally classified as flapping, delta, swept, and so on. In this paper, the literature is reviewed regarding the diverse techniques utilized for the design, experimentation, analysis, simulation, and modeling of different types of wings. Among these types, this paper focuses on the design of delta wings. Accordingly, we review 60 relevant research papers and provide an analysis, based on their content. First, the paper presents the chronological review of the contributions relevant for the design of different types of wings. Subsequently, we focus on various materials such as stainless steel, aluminum, carbon fiber, etc., and on parameters such as Reynolds number, angle of attack, aspect ratio, etc., which are utilized for the design of wings. The paper also provides a detailed performance study regarding the contribution to the design of delta wing. Finally, we present various research issues, which can be useful for the researchers in accomplishing further research on the design of delta wings.
Źródło:
Control and Cybernetics; 2020, 49, 4; 525-553
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pliocene-Quaternary stratigraphy and sedimentation at the Neretva River Mouth, on Croatian Adriatic Coast
Autorzy:
Balic, D.
Malvic, T.
Powiązania:
https://bibliotekanauki.pl/articles/2059719.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Adriatic
Neretva
delta
clastics
Pliocene
Opis:
The Adriatic Sea is an epicontinental, closed sea, part of the Mediterranean. It formed in the Late Miocene, and ended structurally during the Pliocene and Quaternary, when most of its sediments were deposited. The larger Pliocene and Quaternary depressions occur mostly by the western coast, where the deposits are several thousand metres thick, and were sourced from the Alps and the Apennines. The east coast is characterised by the large and elongated Dinarides Mts., that have continental drainage extremely close to the shoreline and a very small erosional rate. Consequently, eastern inflows were and are very short, including strongly tidal estuaries that erode only small volumes of mostly carbonate detritus, adjacent to frontal islands or mountains, with restricted depositional areas. The Neretva River deposits make up part of the largest contemporary delta system on the eastern Adriatic coast, and have been analysed in this study using three seismic sections and one exploration well. These deposits are recognized inside the Neretva and Korčula channels, assuming that processes operating during Quaternary glacial phases shifted the delta tens of kilometres to the west in the past on several occasions.
Źródło:
Geological Quarterly; 2013, 57, 2; 233--241
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
THREE PHASE WARSAW BOOST RECTIFIER FOR HIGH POWER VARIABLE SPEED POWER GENERATION
Trójfazowy „Warsaw Rectifier” w układzie wytwarzania energii dużej mocy o regulowanej prędkości generatora
Autorzy:
Bałkowiec, T.
Powiązania:
https://bibliotekanauki.pl/articles/1817906.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Warsaw rectifier
delta-switch rectifier
high power
PWM modulation
Vienna rectifier
Opis:
Artykuł przedstawia topologię prostownika „Warsaw Rectifier”, jego zasadę działania oraz wyniki symulacyjne, w których prostownik zasilany był ze źródła napięcia o zmiennej amplitudzie i częstotliwości, np. generatora z magnesami trwałymi. Wyniki symulacyjne potwierdzają poprawność opracowanego układu sterowania, opartego na modulacji szerokości impulsów o stałej częstotliwości łączeń. Przedstawione wyniki w tabeli 3 również potwierdzają, że topologia umożliwia pobór sinusoidalnego prądu oraz stabilizację napięcia wyjściowego prostownika w układach o dużej mocy, w których częstotliwość łączeń jest ograniczona. Układ prostownika umożliwia zapewnia małe pulsacje mocy, które w generatorze przekładają się na małe pulsacji momentu. Topologia Warsaw Rectifier jest podobna do topologii Vienna Rectifier, natomiast różni się sposobem połączeń. Co więcej, rozważany prostownik Warsaw Rectifier wytwarza dwupoziomowe napięcie wyjściowe, podczas gdy prostownik Vienna wytwarza stałe, trójpoziomowe napięcie.
Źródło:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały; 2015, 71, 35; 3--15
1733-0718
Pojawia się w:
Prace Naukowe Instytutu Maszyn, Napędów i Pomiarów Elektrycznych Politechniki Wrocławskiej. Studia i Materiały
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trend of arsenic pollution and subsequent bioaccumulation in Oryza sativa and Corchorus capsularis in Bengal Delta
Autorzy:
Bhattacharya, S.
Guha, G.
Gupta, K.
Chattopadhyay, D.
Mukhopadhyay, A.
Ghosh, U.C.
Powiązania:
https://bibliotekanauki.pl/articles/10831.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
trend
arsenic pollution
bioaccumulation
rice
Oryza sativa
jute
Corchorus capsularis
Bengal Delta zob.Ganges Delta
Ganges River
Ganges Delta
Opis:
Oryza sativa Linn. (rice) and Corchorus capsularis Linn. (jute) are the two major crops of the Bengal basin. Both rice and jute are generally grown in submerged flooded conditions, where arsenic bioavailability is high in soil. The consumers of the edible parts from both plants therefore face an inevitable source of exposure to arsenic, with consequent accumulation and toxicity. The objective of the study was to observe the in-vivo temporal variation of arsenic bioaccumulation in the different parts of O. sativa and C. capsularis. Rice plant specimens (Aman rice, Ratna variety) of different age groups (1, 2 and 3 months old) were analyzed in HG-AAS for absorbed arsenic content in different parts. The accumulation of arsenic remained significantly high in the initial phase of growth, but decreased with time. Amount of arsenic bioaccumulation followed the decreasing order: root > basal stem > median stem > apical stem > leaves > grains in all the three age groups of the rice plant samples. C. capsularis followed a trend of arsenic bioaccumulation similar to O. sativa. O. sativa had more accumulation potential than C. capsularis, but C. capsularis showed much higher efficiency of arsenic translocation in the above ground parts. This is the first ever report of time-dependent decrease in arsenic bioaccumulation in O. sativa and C. capsularis. The contamination level can reach the grain part in significant amount and can cause health hazards in more severely arsenic affected areas. Intensive investigation on a complete food chain is urgently needed in the arsenic contaminated zones for further risk assessments.
Źródło:
International Letters of Natural Sciences; 2014, 16
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Environmental, economic and health perspectives of arsenic toxicity in Bengal Delta
Autorzy:
Bhattacharya, Sayan
Ghosh, Uday Chand
Powiązania:
https://bibliotekanauki.pl/articles/1194026.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Arsenic
Bengal Delta
Bioaccumulation Groundwater
Phytoremediation
Toxicity
Opis:
Arsenic is a metalloid of great environmental concern because of its highly toxic nature and wide abundance. Arsenic contamination in groundwater has been reported in Bangladesh, India, China, Taiwan, Vietnam, USA, Argentina, Chile and Mexico. The clinical symptoms of arsenic toxicity in human body include skin itching to sun rays, burning and watering of the eyes, weight loss, loss of appetite, weakness, fatigue, limited physical activities and working capacities, chronic respiratory problems, moderate to severe anemia etc. The Bengal basin is regarded to be the most acutely arsenic infested geological province in the world. Heavy withdrawal of groundwater for fulfilling the needs of the increasing population in Bengal Basin resulted in increased arsenic level in the groundwater. Mobilization of arsenic in Bengal delta is further interfered by microbial activities and interactions. Different microbial strains have been isolated from Bengal Delta which can tolerate, transform and resist arsenic. The use of arsenic contaminated groundwater for irrigation purpose in crop fields elevates arsenic concentration in surface soil and in the plants grown in these areas. Several plant species have been studied for their ability to accumulate arsenic in the Bengal Delta. Rice is generally grown in submerged flooded condition, where arsenic bioavailability is high in soil. As arsenic species are very much toxic to plants and can execute oxidative stresses, they can also affect the overall production of rice and other vegetables, and can affect the agricultural and economic development of Bengal Basin. Cattle population also consume arsenic infested water in those areas and usually eat edible plants contaminated with arsenic, which, in turn, can further increase the toxicity level in their bodies and also can increase the arsenic bioaccumulation in meat and milk. In the rural areas of the Bengal Delta, arsenic contamination raised a number of social problems which are continuously weakening the structural integrity of rural society. Uses of phytoremediation and microbial remediation technologies, rainwater harvesting, use of arsenic resistant plant varieties for cultivation are some sustainable methods which can be applied for arsenic remediation. Besides, nano-agglomerates of mixed oxides have been synthesized and successfully employed for arsenic removal from aqueous solutions. Intensive investigation on a complete food chain is urgently needed in the arsenic contaminated zones, which should be our priority in future researches.
Źródło:
World Scientific News; 2015, 10; 59-87
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Jezioro Aralskie - największa katastrofa ekologiczna minionego stulecia
Aral sea - the bigger ecological disaster of the century
Autorzy:
Bielecki, Rafał
Powiązania:
https://bibliotekanauki.pl/articles/471691.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Pedagogiczny im. Komisji Edukacji Narodowej w Krakowie
Tematy:
jezioro reliktowe
delta Amu-darii
delta Syr-darii
kanały nawadniające
pustynnienie
relict lake
Amu-Darya delta
Syr-Darya delta
irrigation channels
deserfitication
Opis:
One of the best examples of environmental risk arising as a result of inefficient management of environmental resources is the disappearance of the Aral Sea. Aral Sea extends into the territories of Kazakhstan and Uzbekistan. About 10 thousand years ago, this vast body of water was under the influence of water from melting mountain glaciers, flowing directly into the Aral Basin. However, the climate change which started about 3500 years ago contributed to the drying process of the tank. This process became stronger in character at the beginning of the 1960s, when due to the planned economy of the USSR, it was decided to develop large-scale cultivation of cotton in areas too dry to be suitable for such crops. Therefore, the water from the rivers Syr-Darya and Amu-Darya, flowing into the Aral Sea, was directed to irrigation, without worrying about the ecological balance. Consequently, this led to irreversible environmental changes. The Aral Sea Area decreased by 40% and its volume decreased by two-thirds. Water level dropped about 13 feet and is still falling. Historically, the reservoir was fed by more than 60 km3 of water per year; currently it is only about 5 km3. There were years when the lake received virtually no water as a result of these processes. In 1988 a division of the lake into two parts was carried out: the Big Aral Sea in the south and the Small Aral Sea in the north. The salinity of water remaining in the basin has increased roughly three fold ,which has disastrous consequences for the world’s flora and fauna. The Aral Sea region’s economy disappeared completely, e.g. the fisheries and associated processing industries, a sin water with such high salt content no organisms are able to survive. As the lake shrank and large parts of it are now dry, when strong winds blow across the land, they carry huge amounts of tiny particles of salt remaining after the water has evaporated. It has been calculated that in the year after such a dust storm around 75 million tonnes of sand mixed with salt was spread. The toxic dust destroys settlings, fields, and plants, and it is difficult to find a way to counteract this process.
Źródło:
Annales Universitatis Paedagogicae Cracoviensis Studia Geographica; 2010, 1 Dynamika zmian środowiska geograficznego pod wpływem antropopresji; 6-13
2084-5456
Pojawia się w:
Annales Universitatis Paedagogicae Cracoviensis Studia Geographica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geological development of the Nemunas River Delta and adjacent areas, West Lithuania
Autorzy:
Bitinas, A.
Damusyte, A.
Stančikaite, M.
Aleksa, P.
Powiązania:
https://bibliotekanauki.pl/articles/2059891.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Lithuania
Lithuanian Maritime region
Nemunas Delta
Late Glacial
Holocene
geochronology
palaeogeography
Opis:
Geological mapping at a scale of 1:50 000 of the Lithuanian Maritime region has recently been focused on the delta of the Nemunas River and its surroundings. Pollen, diatom and mollusc analyses, lithological investigations, and radiocarbon and optically stimulated luminescence dates have enabled stratigraphic correlation of the Late Glacial and Holocene deposits which make up this delta. Palaeogeographical reconstructions of the southern part of the Lithuanian Maritime region during the maximum extent of the Baltic Ice Lake (~12 000-11 200 years BP), the Ancylus Lake (~8 700-8 500 years BP), the Litorina Sea (~6 100 years BP) and the Post-Litorina Sea (~4 000 years BP) have been made. A geological and geomorphological model of the Nemunas River Delta and its adjacent areas has been constructed. Our results suggest that that part of Nemunas River Delta in Lithuania is very young, having formed during the last 1 000-1 100 years.
Źródło:
Geological Quarterly; 2002, 46, 4; 375-390
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The lower reaches of the Nemunas River at the end of the Last (Weichselian) Glacial and beginning of the Holocene
Autorzy:
Bitinas, A.
Druzhinina, O.
Damušytė, A.
Napreenko-Dorokhova, T.
Guobytė, R.
Mažeika, J.
Powiązania:
https://bibliotekanauki.pl/articles/2060341.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baltic Sea
Nemunas Delta
Ancylus Lake
palaeogeography
hydrography
archaeology
Opis:
The Russian–Lithuanian cross-border area around the Nemunas and Šešupė rivers confluence is a key area for solving palaeogeographic issues important for this region: when the Nemunas Delta started to form, why the essential changes of hydrographic network occurred, and so on. The results of conventional radiocarbon (14C) dating and pollen analysis in the present dry valley between the Šešupė River and the Įrutis River as well as the results of former studies at the Riadino-5 archaeological site suggest that the essential changes in the Nemunas River hydrographic system occurred before 9.5 ka, most likely in Preboreal time, when the Nemunas River cut through the Vilkiškė Marginal Ridge and started to flow directly to the west from this ridge into one of the former basins of the Baltic Sea – to the Yoldia Sea, or to the Ancylus Lake. A new divide was formed between the Šešupė and Įsrutis rivers, and the basins of the Nemunas and Prieglius rivers (formerly a single hydrographic system) became two independent drainage basins of the Baltic Sea. The present Nemunas Delta formation started after the Litorina Sea transgression when the Nemunas River mouth moved from a Baltic Sea nearshore position to close to the western margin of the Vilkiškės Marginal Ridge. A set of palaeogeographic reconstructions of the Nemunas and Šešupė rivers confluence area for different periods of the very end of the Last (Weichselian) Glacial and the beginning of the Holocene have been constructed.
Źródło:
Geological Quarterly; 2017, 61, 1; 156--165
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analiza porównawcza właściwości bezszczotkowego silnika z magnesami trwałymi dla różnych konfiguracji uzwojenia stojana
Properties of brushless DC motor with permanent magnets and different winding configurations: a comparative study
Autorzy:
Bogusz, P.
Korkosz, M.
Prokop, J.
Powiązania:
https://bibliotekanauki.pl/articles/2056396.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Napędów i Maszyn Elektrycznych Komel
Tematy:
konfiguracja uzwojenia stojana
gwiazda
trójkąt
bezszczotkowy silnik prądu stałego z magnesami trwałymi
stator winding configuration
star
delta
brushless permanent magnet motor
Opis:
W artykule przedstawiono wyniki badań symulacyjnych i eksperymentalnych wielobiegunowego bezszczotkowego silnika prądu stałego z magnesami trwałymi. Rozpatrywano dwie konfiguracje uzwojeń silnika, tj. połączenie w gwiazdę i trójkąt przy założeniu stałych danych nawojowych. Na bazie obliczeń numerycznych wyznaczono momentowe charakterystyki statyczne silnika oraz ruchowe w pełnym zakresie zmiany prędkości obrotowej. W warunkach laboratoryjnych dokonano weryfikacji obliczeń numerycznych.
In the paper, results of simulation and laboratory tests of a multi-pole brushless DC motor with permanent magnets were presented. Studies were carried out for two cases (i.e. wye winding configuration and delta winding configuration) on the assumption that winding parameters are constant. The static torque characteristic and the torque-speed characteristic over full speed range were determined based on numerical calculations. Simulation results were validated by a comparison with the laboratory test results.
Źródło:
Maszyny Elektryczne: zeszyty problemowe; 2018, 2, 118; 87--90
0239-3646
2084-5618
Pojawia się w:
Maszyny Elektryczne: zeszyty problemowe
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 204

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