Observations on Factors Affecting the Behaviour of a First-Order Stream

1972 ◽  
pp. 171 ◽  
Author(s):  
R. P. C. Morgan
Keyword(s):  
Order Stream ◽  
Factors Affecting ◽  
First Order

scholarly journals Comparative investigations of nonlinear and linear observers for a highly manoeuvrable target in sliding mode guidance

2017 ◽  
Vol 65 (2) ◽  
pp. 233-245
Author(s):  
Y. Wang ◽  
M. Sun ◽  
S. Du ◽  
Z. Chen
Keyword(s):  
Sliding Mode ◽  
Guidance System ◽  
Key Factors ◽  
Factors Affecting ◽  
First Order ◽  
Guidance Law ◽  
Linear Observer ◽  
Overall Performance ◽  
Twisting Algorithm ◽  
Different Levels

Abstract Target manoeuvre is one of the key factors affecting guidance accuracy. To intercept highly maneuverable targets, a second-order sliding-mode guidance law, which is based on the super-twisting algorithm, is designed without depending on any information about the target motion. In the designed guidance system, the target estimator plays an essential role. Besides the existing higher-order sliding-mode observer (HOSMO), a first-order linear observer (FOLO) is also proposed to estimate the target manoeuvre, and this is the major contribution of this paper. The closed-loop guidance system can be guaranteed to be uniformly ultimately bounded (UUB) in the presence of the FOLO. The comparative simulations are carried out to investigate the overall performance resulting from these two categories of observers. The results show that the guidance law with the proposed linear observer can achieve better comprehensive criteria for the amplitude of normalised acceleration and elevator deflection requirements. The reasons for the different levels of performance of these two observer-based methods are thoroughly investigated.

scholarly journals Aquatic oligochaetes associated with bryophytes in an Atlantic Forest stream

2013 ◽  
Vol 13 (4) ◽  
pp. 371-375 ◽  
Author(s):  
Luciana Falci Theza Rodrigues ◽  
Lucas Deziderio Santana ◽  
Roberto da Gama Alves
Keyword(s):  
Water Flow ◽  
Atlantic Forest ◽  
Benthic Macroinvertebrates ◽  
Dry Season ◽  
Forest Fragment ◽  
Order Stream ◽  
First Order ◽  
Aquatic Oligochaetes ◽  
Forest Stream ◽  
Dry And Rainy Seasons

There are few reports in the literature about the colonization of benthic macroinvertebrates on bryophytes. The aim of the present study was to analyzed the oligochaetes established on bryophytes adhered to stones in a first-order stream. The collections were carried out in an Atlantic Forest fragment area during the dry and rainy seasons. We identified 15 taxa from a total of 422 oligochaetes specimens, of which the most abundant were Pristina sp.1, Enchytraeidae and Pristina jenkinae. Unlike other habitats, where the abundance of macroinvertebrates tends to be greater in the dry season, we did not find any significant differences in the abundance, richness, composition and diversity between the two periods. The results of this study indicate that bryophytes are possible areas of refuge for oligochaetes in periods of faster water flow.

Snowpack Ion Accumulation and Loss in a Basin Draining to Lake Superior

1987 ◽  
Vol 44 (11) ◽  
pp. 1812-1819 ◽  
Author(s):  
Robert Stottlemyer
Keyword(s):  
Lake Superior ◽  
Ionic Species ◽  
Winter Precipitation ◽  
Stream Chemistry ◽  
Order Stream ◽  
Freezing Soil ◽  
First Order ◽  
Stream Discharge ◽  
Biological Uptake ◽  
Thaw Period

The objective of this study was to relate winter precipitation ionic inputs, snowpack retention, and change in first-order stream chemistry with spring snowpack melt. During winter 1982–83, measurement of precipitation inputs, snowpack concentration and loading, and streamwater concentration and discharge of Ca2+, K+, H+, NO3−, and SO42− from a 176-ha watershed reveals that only H+ might be lost from the snowpack before first thaw. Above-freezing soil temperature beneath the snowpack may be a factor in H+ loss. An initial 1-d thaw resulted in loss of over one third (6 eq∙ha−1) of the snowpack Ca2+. Over one half the snowpack load of K+, H+, NO3−, and SO42−, was lost in a subsequent midwinter freeze–thaw period. Snowpack loading of ionic species was reduced by 70–90% before peak spring melting and stream discharge. Ecosystem H+ retention and biological uptake of NO3− further mitigate ionic "pulses" in streamwater. Sulfate discharge exceeds bulk inputs, which suggests significant dry deposition input and little forest soil retention of this anion. The snowpack was relatively small, which limits wider application of these results to the region.

scholarly journals Meiofauna in stream habitats: temporal dynamics of abundance, biomass and secondary production in different substrate microhabitats in a first-order stream

2020 ◽  
Vol 54 (4) ◽  
pp. 1079-1095
Author(s):  
Henrike Brüchner-Hüttemann ◽  
Christoph Ptatscheck ◽  
Walter Traunspurger
Keyword(s):  
Density Distribution ◽  
Leaf Litter ◽  
Secondary Production ◽  
Dead Wood ◽  
Temporal Dynamics ◽  
Seasonal Patterns ◽  
Order Stream ◽  
First Order ◽  
Relative Contribution ◽  
Meiofaunal Abundance

Abstract Meiofaunal abundance, biomass and secondary production were investigated over 13 months in an unpolluted first-order stream. Four microhabitats were considered: sediment and the biofilms on dead wood, macrophytes and leaf litter. The relative contribution of the microhabitats to secondary production and the influence of environmental factors on meiofaunal density distribution were estimated. We expected (1) meiofaunal abundance and biomass to exhibit seasonal patterns, with more pronounced seasonal fluctuations on macrophytes and leaf litter than in the other microhabitats, (2) annual secondary production to be highest in sediment; however, the relative contribution of the microhabitats to monthly secondary production would change during the year, and (3) a bottom-up driven influence on meiofaunal density distribution in the microhabitats. Meiofaunal annual mean abundance, biomass and secondary production were 7–14 times higher in sediment and on dead wood than on macrophytes and leaf litter. Significant seasonal patterns described the meiofaunal abundance in sediment and on leaf litter as well as the biomass in sediment, on macrophytes and leaf litter. Organisms in sediment and on dead wood contributed 48 and 43%, respectively, to secondary production m−2, but in regard to the stream area covered by the microhabitats, sediment had the highest share (80%). Significant determinants of the density distribution were AFDM, protozoans, bacteria and Chl-a, which influenced all meiofaunal groups. Our study clearly indicates that meiofaunal organisms in sediment and on dead wood have a remarkable share on total secondary production of lotic systems which is especially relevant for forested low-order streams.

scholarly journals Food-resource partitioning among fish species from a first-order stream in northwestern Paraná, Brazil

2012 ◽  
Vol 10 (2) ◽  
pp. 389-399 ◽  
Author(s):  
Jislaine Cristina da Silva ◽  
Rosilene Luciana Delariva ◽  
Karine Orlandi Bonato
Keyword(s):  
Resource Sharing ◽  
Poecilia Reticulata ◽  
Food Resource ◽  
Fish Fauna ◽  
Detrended Correspondence Analysis ◽  
Food Sources ◽  
Dietary Overlap ◽  
Order Stream ◽  
First Order ◽  
Allochthonous Resources

This study addressed the feeding ecology of fish fauna from a first-order stream located in a rural area. The purposes were to evaluate the influence of interspecific, seasonal and spatial factors on the diet, examine the dietary overlap, and determine the predominant food sources. Sampling was conducted in December 2007, September 2008, and March 2009, in three 50-m stretches of Itiz stream (upstream, intermediate, and downstream), through electrofishing. A total of 1,102 stomach contents were analyzed from 14 species, by the volumetric method. In general, allochthonous resources were predominant in the diets. Astyanax aff. fasciatus, Astyanax aff. paranae, Astyanax bockmanni, and Bryconamericus aff. iheringi consumed a higher proportion of plant remains, and Bryconamericus stramineus consumed predominantly Hymenoptera. The diets of Cetopsorhamdia iheringi, Characidium aff. zebra, Imparfinis schubarti, and Trichomycterus sp. consisted of aquatic insects, especially immature forms of Trichoptera, Ephemeroptera, Plecoptera, and Diptera. Hypostomus ancistroides, Hisonotus sp., Poecilia reticulata, and Rineloricaria aff. pentamaculata exploited mainly detritus, while Rhamdia quelen used a variety of items, predominantly terrestrial insects. Detrended Correspondence Analysis (DCA) showed a clear distinction among the species, with different morphology and feeding tactics. The Multi-Response Permutation Procedure (MRPP) supported this differentiation, and also indicated significant spatial and temporal variations in the dietary composition; the Indicator Value Method (IndVal) indicated the main items that contributed to these differences. The diet overlap among species was low (< 0.4) to around 78% of pairs, and the mean value did not vary significantly among the sites or between hydrological periods within each site. According to the null model of Pianka’s index, the values for dietary overlap were significantly higher than expected at random, showing evidence of resource sharing. This was related to the availability of allochthonous resources, highlighting the importance of riparian vegetation as a source of these resources for maintaining the fish fauna of the stream.

Ecology of juvenile Northern watersnakes (Nerodia sipedon) inhabiting low-order streams

2010 ◽  
Vol 31 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Kristen Cecala ◽  
Michael Dorcas ◽  
Steven Price
Keyword(s):  
North Carolina ◽  
Natural History ◽  
Stream Water ◽  
Juvenile Stage ◽  
Nerodia Sipedon ◽  
Order Stream ◽  
First Order ◽  
High Survivorship ◽  
History Of ◽  
Low Order

AbstractThe juvenile stage for many reptiles is considered “the lost years” because of low capture probabilities, however understanding factors impacting juvenile survivorship and recruitment is critical for conservation of populations. We studied the ecology of juvenile Northern watersnakes, Nerodia sipedon, by intensively sampling a first-order stream and determined the occupancy of juveniles in 30 low-order streams in the Piedmont of North Carolina. Juveniles were relatively abundant within a single stream (n = 62 ± 9), and their capture probabilities were positively related to increasing stream-water temperatures. We also found that juveniles had high survivorship (ϕ = 0.87 ± 0.017). Occupancy of juvenile N. sipedon in low-order, Piedmont streams may be greater at streams that have confluences with high order streams or lakes, which potentially support adult N. sipedon populations. This study provides important information regarding the natural history of juvenile reptiles and indicates the importance of low order streams as habitat for N. sipedon populations.

Noise-Reducing and Effect-Enhancing System for Communication Equipment Mounted on Vehicle

2014 ◽  
Vol 623 ◽  
pp. 161-168
Author(s):  
Lu Chen ◽  
Shi Hai Fan ◽  
Shi Nan Zhang
Keyword(s):  
Noise Reduction ◽  
Noise Control ◽  
Active Noise Control ◽  
Noise Measurement ◽  
Mathematics Model ◽  
Factors Affecting ◽  
Voice Transmission ◽  
First Order ◽  
Active Noise ◽  
Communication Equipment

The noise of communication equipment mounted on Vehicle is one of important factors affecting equipment efficiency. Active Noise Control (ANC) technology is applied to noise reduction of the equipment, and a noise reduction mathematics model is built based on accurate noise measurement. An approach to reduce noise based on first-order differential microphone (FDM) array and ANF technology is proposed, which collects and evaluates environmental noise precisely to enhance voice. This approach improves the conversation effects and realizes full fidelity of voice transmission.

scholarly journals Population Pharmacokinetic Analysis of Tiropramide in Healthy Korean Subjects

Pharmaceutics ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 374
Author(s):  
Seung-Hyun Jeong ◽  
Ji-Hun Jang ◽  
Hea-Young Cho ◽  
Yong-Bok Lee
Keyword(s):  
Digestive System ◽  
Genetic Factors ◽  
Population Pharmacokinetic Analysis ◽  
Pharmacokinetic Analysis ◽  
Population Pharmacokinetic ◽  
Factors Affecting ◽  
First Order ◽  
Basic Model ◽  
Dosing Algorithm ◽  
Subject Variability

The purpose of this study was to perform population pharmacokinetic (PPK) analysis of tiropramide in healthy Korean subjects, as well as to investigate the possible effects of various covariates on pharmacokinetic (PK) parameters of tiropramide. Although tiropramide is commonly used in digestive system-related diseases as an antispasmodic, PPK reporting and factors affecting PKs are not clearly reported. Thus, this study for healthy subjects is very significant because it could find new covariates in patients that had not been reported before or predict PPK for patients in the clinic by establishing PPK in healthy adults. By using Phoenix NLME, PK, demographic, and genetic data (collected to explain PK diversity of tiropramide in population) analyses were performed. As a basic model, a one-compartment with first-order absorption and lag-time was established and extended to include covariates that influenced the inter-subject variability. The total protein significantly influenced the distribution volume and systemic clearance of tiropramide, but genetic factors such as ABCB1 (1236C>T, 2677G>T/A, and 3435C>T), CYP2D6 (*1 and *10), OCT2 (808G>T), and PEPT1 (1287G>C) genes did not show any significant association with PK parameters of tiropramide. The final PPK model of tiropramide was validated, and suggested that some of the PK diversity in the population could be explained. Herein, we first describe the establishment of the PPK model of tiropramide for healthy Korean subjects, which may be useful as a dosing algorithm for the diseased population.

scholarly journals Fish trophic structure in a first order stream of the Iguatemi River basin, Upper Paraná River, Brazil

2016 ◽  
Vol 38 (4) ◽  
pp. 429 ◽  
Author(s):  
Evaneide Nogueira Lopes ◽  
Milza Celi Fedatto Abelha ◽  
Valéria Flávia Batista-Silva ◽  
Elaine Antoniassi Luiz Kashiwaqui ◽  
Dayani Bailly
Keyword(s):  
River Basin ◽  
Trophic Structure ◽  
Paraná River ◽  
Order Stream ◽  
First Order ◽  
Parana River ◽  
Upper Paraná River
Sign in / Sign up

Export Citation Format

Share Document