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1
Content available remote Potamozooplankton communities in three different outlets from mesotrophic lakes located in lake-river system
100%
Czerniawski R. , Domagała J.
Oceanological and Hydrobiological Studies
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2012
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tom Vol. 41, No. 1
46-56
EN
Qualitative and quantitative composition of potamozooplankton was studied in three outlets from mesotrophic lakes. The greatest taxonomic and quantitative similarity of zooplankton occurred between the outflows of the second and third lake, located in the lake-river system. The farther the lake was located in the lake-river system, the greater was the quantity of zooplankton in the outflow. Within a short distance between the outflow and the downstream section, there was a strong reduction of cladocerans’ communities, followed by copepods, while the communities of rotifers were reduced in relatively small quantities. The hydrological conditions and transparency had a strong impact on the rate of changes in the zooplankton community.
2
Content available Assessment of Productivity Status Using Carlson’s TSI and Fish Diversity of Goronyo Dam, Sokoto State, Nigeria
88%
Maishanu H. M. , Mainasara M. M. , Magami I. M.
Path of Science
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2018
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tom 4
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nr 1
2001-2006
EN
Goronyo Dam is the largest lentic waterbody in Sokoto, it was constructed to serve as flood control and used for irrigation activities. The study was conducted to evaluate productivity status and fish diversity of Goronyo Dam in 2016. Water samples were collected monthly from the Dam at two sampling sites (Upstream and Downstream). Water samples were collected using sterilized sampling bottles and analyzed in the Laboratory for physicochemical variables and the diversity of fish was evaluated through the use of a structured questionnaire. Depth and transparency were the only variables that did not show any statistically significant difference between the months. Productivity status of the dam was evaluated using Carlson’s Trophic State Index. The downstream has high TSI value of 16.54 compared to upstream with 13.00. A diversity of fishes from the shows that 3 species were more abundant in the dam, these were; Mormyrops species, Alestes species and Clupeid species. Factors contributed to the survival of fish species were an abundance of water and plankton in the dam. While factors affecting the distribution of fish species were pollution and predation.
3
Content available Weryfikacja kryteriów doboru długości umocnień koryta w dolnym stanowisku jazu
75%
Urbański J.
Przegląd Naukowy Inżynieria i Kształtowanie Środowiska
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2012
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tom Vol. 21, No. 1
18--26
PL
W pracy przedstawiono wyniki laboratoryjnych badań modelowych, których celem była weryfikacja kryteriów doboru długości umocnień koryta w dolnym stanowisku jazu. Model budowli z wypływem wody spod zasuwy, niecką do rozpraszania energii i umocnionym dnem w dolnym stanowisku wykonano w korycie o przekroju prostokątnym. Podczas doświadczeń wykonywano pomiary prędkości w pionach położonych w osiowej płaszczyźnie koryta w różnej odległości od końca niecki wypadowej. Przeprowadzono analizę wyników pod kątem określenia minimalnej długości odcinka umocnień dna za wypadem. Pomierzone długości umocnień zestawiono z obliczonymi na podstawie kryteriów zalecanych do praktycznego stosowania. Długość umocnień pomierzona była w większości przypadków mniejsza od obliczonej. Kryteria stosowane w praktyce pozwalają wydłużyć umocnienia w dość szerokim zakresie, co zapewnia stabilność koryta na dłuższym odcinku w dolnym stanowisku i wpływa na poprawę bezpieczeństwa budowli.
EN
The paper presents results of laboratory tests, purpose was to verification of criteria for determining the length of bed protection in downstream of the weir. Investigations were conducted on model of weir with overflow under closure, water basins to disipate of energy and horizontal the bed protection in downstream. During the experiments measured velocity in verticals below the water basin located in the axial plane of the channel. An analysis of the results in terms of determining the minimum length of the bed protection in downstream. Measured length of the bed protection were compared with calculated on the basis criteria recommended for practical application. The measured length of bed protection was smaller than the calculated. The criteria used in practice allow longer the bed protection. This provides stability for the longer bed of channel in the downstream and influence to building safety.
4
Content available Experimental and numerical investigation of scour downstream contracted spillways
75%
Nasralla T. H.
Journal of Water and Land Development
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2022
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tom no. 52
53--59
EN
A study of scour downstream of free hydraulic jump in stilling basin of stepped spillways was carried out. This paper employed an experimental study to investigate the stepped spillway with the movable bed material of D50= 3.1 mm. The effect of the contraction ratio of the stepped spillway was highlighted. Different downstream divergent angle was studied to minimise the scour depth, the results showed that the relative scour depth was reduced by 23% for divergent angle is equal to 170°, different shapes of buffer in stilling basin were also studied to reduce the scour depth where the considered buffer decrease the relative scour depth up to 84%. This study was simulated by Flow 3D program to analyse the scour hole formed using velocity vectors at the bed. The simulated results well agreed with the measured data.
5
Content available remote Review of Voltage Sag Source Identification Methods for Power Quality Diagnosis
63%
Kazemi A. , Mohamed A. , Shareef H. , Zayandehroodi H.
Przegląd Elektrotechniczny
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2013
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tom R. 89, nr 8
143--146
EN
Voltage sag is considered as one of the most common power quality problems causing sensitive equipment to malfunction and many industrial process interruptions. Complains about the economic loss and equipment damage from industrial customers has stimulated the investigation on the voltage sag source location. As a result, many efforts have been made to know the location of voltage sags by utilizing various concepts. Generally, there are two broad categories of methods to locate voltage sags source, namely, single and multi-monitor based methods. Therefore, the purpose of this paper is to present a comprehensive review of articles that involves various methods to identify the location of voltage sag source. Accordingly, the concepts, advantages and disadvantages of these methods are discussed and tabulated for review. Although this paper does not exhibit a numerical performance comparison, most of the research publications under the subject of voltage sag source location methods have been sorted and appended for a rapid reference.
PL
Zapady napięcia są jednym z ważniejszych parametrów opisjących jakość energii. Mogą one powodować uszkodzenia urządeń i zakłócenia procesów przemysłowych. Artykuł omawia metody lokalizacji źródeł zapadów napięcia. Zaprezentowano przegląd publikacji opisujących ten problem uwypuklając zalety i wady każdej z metod.
6
The food preferences of three-spined stickleback, Gasterosteus aculeatus L., downstream from a dam reservoir
51%
Dukowska M. , Grzybkowska M. , Marszal L. , Zieba G.
Oceanological and Hydrobiological Studies
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2009
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tom 38
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nr 2
39-50
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