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    Wyświetlanie 1-12 z 12
    Tytuł:
    A new algebraic LQR weight selection algorithm for tracking control of 2 DoF torsion system
    Autorzy:
    Elumalai, V. K.
    Subramanian, R. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/140978.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ARE
    high gain observer
    LQR
    Q and R matrices
    2 DoF torsion system
    trajectory tacking
    Opis:
    This paper proposes a novel linear quadratic regulator (LQR) weight selection algorithm by synthesizing the algebraic Riccati equation (ARE) with the Lagrange multiplier method for command following applications of a 2 degree of freedom (DoF) torsion system. The optimal performance of LQR greatly depends on the elements of weighting matrices Q and R. However, normally these weighting matrices are chosen by a trial and error approach which is not only time consuming but cumbersome. Hence, to address this issue, blending the design criteria in time domain with the ARE, we put forward an algebraic weight selection algorithm, which makes the LQR design both simple and modular. Moreover, to estimate the velocity of a servo angle, a high gain observer (HGO) is designed and integrated with the LQR control scheme. The efficacy of the proposed control scheme is tested on a benchmark 2 DoF torsion system for a trajectory tracking application. Both the steady state and dynamic characteristics of the proposed controller are assessed. The experimental results accentuate that the proposed HGO based LQR scheme can guarantee the system to attain the design requirements with minimal vibrations and tracking errors.
    Źródło:
    Archives of Electrical Engineering; 2017, 66, 1; 55-75
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental Investigation of Microstructure, Mechanical and Wear Characteristics of Cu-Ni/ZrC Composites Synthesized through Friction Stir Processing
    Autorzy:
    Velmurugan, T.
    Subramanian, R.
    Priyadharshini, G. Suganya
    Raghu, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/351128.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Cu-Ni/ZrC composite
    Friction Stir Processing
    mechanical properties
    wear
    Opis:
    Friction Stir Process (FSP) was employed to develop Cupro-Nickel/Zirconium Carbide (Cu-Ni/ZrC) surface composites. Five different groove widths ranging from 0 to 1.4 mm were made in CuNi alloy plate to incorporate different ZrC volume fraction (0, 6, 12, 18 and 24 %) to study its influence on the structure and properties of Cu-Ni/ZrC composite. Processing was performed at a Tool Rotational Speed (TRS) of 1300 rpm, Tool Traverse Speed (TTS) of 40 mm/min with a constant axial load of 6 KN. The study is performed to analyse the influence of ZrC particles and the volume fraction of ZrC particles on the microstructural evolution, microhardness, mechanical properties, and tribological characteristics of the Cu-Ni/ZrC composite. The fracture and worn-out surfaces are analysed using Field Emission Scanning Electron Microscope (FESEM) to identify the fracture and wear mechanisms. The results demonstrated a simultaneous increase in microhardness and tensile strength of the developed composite because of grain refinement, uniform dispersion, and excellent bonding of ZrC with the matrix. Besides, the wear resistance increases with increase in volume fraction of ZrC particles in the composite. The surface morphology analysis revealed that the wear mechanism transits from severe wear regime to mild wear regime with increase in volume fraction of ZrC particles.
    Źródło:
    Archives of Metallurgy and Materials; 2020, 65, 2; 565-574
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Characterization of Functionally Graded Al-6Cr-Y2O3 Composites
    Autorzy:
    Satish Kumar, T.
    Krishna Kumar, K.
    Shalini, S.
    Subramanian, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/353460.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Al-6Cr alloy
    powder metallurgy
    functionally graded materials
    wear resistance
    Opis:
    The present investigation aims at fabricating a functionally graded Al-6Cr-Y2O3 composite and its microstructural and property characterization. Al-6Cr-alloys with varying percentage of Y2O3 (5-10 vol. %) have been used to fabricate FGM by powder metallurgy route. The samples were subsequently subjected to solution treatment at 610°C for 4h followed by artificially aged at 310°C for 4h. The microstructure, hardness and wear behavior of these FGM have been evaluated. FGM exhibited superior hardness (360 ± 5 VHN) as compared to the unprocessed composites (220 ± 5 VHN) due to the uniform dispersion of Y2O3 particles. Wear resistance of Al-6Cr-10Y2O3 FGM were compared that of with pure Al-6Cr alloy by dry abrasive wear test. Al-6Cr-10Y2O3 FGM composites were found to exhibit higher wear resistance with the minimum wear rate of 0.009 mm3/m compared to the Al-6Cr alloy wear rate 0.02 mm3/m.
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 4; 1649-1655
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Star Coloring of Subcubic Graphs
    Autorzy:
    Karthick, T.
    Subramanian, C.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/30146582.pdf
    Data publikacji:
    2013-05-01
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    vertex coloring
    star coloring
    subcubic graphs
    Opis:
    A star coloring of an undirected graph G is a coloring of the vertices of G such that (i) no two adjacent vertices receive the same color, and (ii) no path on 4 vertices is bi-colored. The star chromatic number of G, χs(G), is the minimum number of colors needed to star color G. In this paper, we show that if a graph G is either non-regular subcubic or cubic with girth at least 6, then χs(G) ≤ 6, and the bound can be realized in linear time.
    Źródło:
    Discussiones Mathematicae Graph Theory; 2013, 33, 2; 373-385
    2083-5892
    Pojawia się w:
    Discussiones Mathematicae Graph Theory
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Induced acyclic tournaments in random digraphs: Sharp concentration, thresholds and algorithms
    Autorzy:
    Dutta, Kunal
    Subramanian, C.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/31232000.pdf
    Data publikacji:
    2014-08-01
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    random digraphs
    tournaments
    concentration
    thresholds
    algorithms
    Opis:
    Given a simple directed graph $D = (V,A)$, let the size of the largest induced acyclic tournament be denoted by $mat(D)$. Let $D ∈ \mathcal{D}(n, p)$ (with $p = p(n)$) be a random instance, obtained by randomly orienting each edge of a random graph drawn from $\mathcal{G}(n, 2p)$. We show that $mat(D)$ is asymptotically almost surely (a.a.s.) one of only 2 possible values, namely either $b^\ast$ or $b^\ast + 1$, where $b^\ast = ⌊2(log_rn) + 0.5⌋$ and $r = p^{−1}$. It is also shown that if, asymptotically, $2(log_rn) + 1$ is not within a distance of $w(n)//(ln n)$ (for any sufficiently slow $w(n) → ∞$) from an integer, then $mat(D)$ is $⌊2(log_rn) + 1⌋$ a.a.s. As a consequence, it is shown that $mat(D)$ is 1-point concentrated for all $n$ belonging to a subset of positive integers of density 1 if $p$ is independent of $n$. It is also shown that there are functions $p = p(n)$ for which $mat(D)$ is provably not concentrated in a single value. We also establish thresholds (on $p$) for the existence of induced acyclic tournaments of size i which are sharp for $i = i(n) → ∞$. We also analyze a polynomial time heuristic and show that it produces a solution whose size is at least $log_rn + Θ(\sqrt{log_rn})$. Our results are valid as long as $p ≥ 1//n$. All of these results also carry over (with some slight changes) to a related model which allows 2-cycles.
    Źródło:
    Discussiones Mathematicae Graph Theory; 2014, 34, 3; 467-495
    2083-5892
    Pojawia się w:
    Discussiones Mathematicae Graph Theory
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Intersection Dimension and Graph Invariants
    Autorzy:
    Aravind, N.R.
    Subramanian, C.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/32083820.pdf
    Data publikacji:
    2021-02-01
    Wydawca:
    Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
    Tematy:
    circular dimension
    dimensional properties
    forbidden-subgraph colorings
    Opis:
    We show that the intersection dimension of graphs with respect to several hereditary properties can be bounded as a function of the maximum degree. As an interesting special case, we show that the circular dimension of a graph with maximum degree Δ is at most \(O\Big(\Delta\frac{log\Delta}{log log\Delta}\Big)\). It is also shown that permutation dimension of any graph is at most $\Delta(log \Delta)^{1+o(1)}$. We also obtain bounds on intersection dimension in terms of treewidth.
    Źródło:
    Discussiones Mathematicae Graph Theory; 2021, 41, 1; 153-166
    2083-5892
    Pojawia się w:
    Discussiones Mathematicae Graph Theory
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Enhanced IMC synthesis for tracking control of magnetic levitation system
    Autorzy:
    Elumalai, V. K.
    Subramanian, R. G.
    Reddipogu, J. S. D.
    Srinivasan, S.
    Agrawal, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/140742.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    IMC
    magnetic levitation
    time delay
    Q-parameterization
    robustness
    Opis:
    This paper presents an enhanced internal model control (EIMC) scheme for a time-delayed second order unstable process, which is subjected to exogenous disturbance and model variations. Even though the conventional internal model control (IMC) can provide an asymptotic tracking response with desired stability margins, the major limitation of conventional IMC is that it cannot be applied for an unstable system because a small exogenous disturbance can trigger the control signal to grow unbounded. Hence, modifying the conventional IMC structure to guarantee the internal stability, we present an EIMC scheme which can offer better trade-off between setpoint tracking and disturbance rejection characteristics. To improve the load disturbance rejection characteristics and attenuate the effect of sensor noise, we solve the selection of controller gains as an H∞ optimization problem. One of the key aspects of the EIMC scheme is that the robustness of the closed loop system can be tuned via a single tuning parameter. The performance of the EIMC scheme is experimentally assessed on a magnetic levitation plant for reference tracking application. Experimental results substantiate that the EIMC scheme can effectively counteract the inherent time delay in the model and offer precise tracking, even in the presence of exogenous disturbance. Moreover, by comparing the trajectory tracking performance of EIMC with that of the proportional integral velocity (PIV) controller through cumulative power spectral density (CPSD) of the tracking error, we show that the EIMC can offer better low frequency servo response with minimal vibrations.
    Źródło:
    Archives of Electrical Engineering; 2018, 67, 2; 293--306
    1427-4221
    2300-2506
    Pojawia się w:
    Archives of Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microplankton size structure induced by a warm-core eddy in the Western Bay of Bengal: Role of Trichodesmium abundance
    Autorzy:
    Chinnadurai, K.
    Retnamma, J.
    Nagarathinam, A.
    Subramanian, P.R.
    Singaram, P.
    Shoba, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2078908.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    microplankton
    size structure
    biomass
    Trichodesmium
    sea surface temperature
    wind
    sea level
    geostrophic current circulation
    chlorophyll a
    Bengal Bay
    Opis:
    Mesoscale warm-core eddies are common in the Bay of Bengal (BoB), and this study in the western BoB during Pre-Southwest Monsoon (April 2015) presents how a prolonged warmcore core eddy could modify the microplankton biomass and size structure. To investigate this, field sampling and laboratory analyses were augmented with satellite data sets of sea surface temperature (SST), winds, mean sea level anomaly (MSLA), geostrophic currents and chlorophyll-a. High SST with positive MSLA (≥ 20 cm) and a clockwise circulation, represented the occurrence of a large warm-core eddy in the western BoB. Time series data evidenced that it was originated in the mid of March and persistent there till early June, which in turn caused a decrease in the surface nutrients and chlorophyll-a. The abundance and biomass of microplankton were negligible in the warm-core eddy region. FlowCAM data showed a significant decrease in the autotrophic microplankton parameters in the warm-core eddy (av. 13 ± 9 ind. L−1 and 0.1 ± 0.04 μgC L−1, respectively) as compared to the surrounding locations (av. 227 ± 143 ind. L−1 and 0.8 ± 0.5 μgC L−1, respectively). Low nutrients level in the warm core eddy region favoured high abundance of needle-shaped phytoplankton cells dominated by Trichodesmium cells. As a result, the size of micro-autotrophs in the warm-core eddy was larger (av. 91,760 ± 12,902 μm3 ind.−1) than its outside (av. 50,115 ± 21,578 μm3 ind.−1). This is a deviation from our belief that the oligotrophy decreases the phytoplankton size. We showed here that the above understanding might not be infallible in warm-core eddies in the northern Indian Ocean due to its inducing effect on the Trichodesmium abundance.
    Źródło:
    Oceanologia; 2021, 63, 3; 283-300
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Implications of an extensive salt water barrage on the distribution of black clam in a tropical estuarine system, Southwest coast of India
    Autorzy:
    Nagarathinam, A.
    Retnamma, J.
    Loganathan, J.
    Singaram, P.
    Kannampally Madam, S.M.
    Jose, A.K.
    Subramanian, P.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/2078884.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    backwater
    salt water
    water barrage
    black clam
    abundance
    distribution
    tropical estuary
    India coast
    Opis:
    Based on a monthly field sampling over a year in the Kochi backwaters (KBW), this study presents the larval ecology of black clam and discusses how an extensive saltwater barrage [Thannermukkom barrage (TB)] impacted the natural black clam resource distribution. Spatial variations in salinity were found minimal during the Southwest Monsoon (June—September) due to the predominance of the freshwater associated with heavy monsoonal rainfall. Conversely, significant spatial changes in salinity were evident during the Pre-Southwest Monsoon (March—May) and Post-Southwest Monsoon (October—February). Monthly sampling exercises revealed that the black clam stock in the KBW breeds throughout the year, as their larvae were found (8 indiv. m—3—494 indiv. m—3) in all the locations. This observation is the modification of the traditional belief that black clam in the KBW breeds only twice a year. Mesohaline condition (salinity 5—18) is the most conducive for peak spawning and larval production. There were two peaks of larval production in the KBW over a year, mainly associated with the prevalence of the optimum salinity conditions on different spatial scales. The closing of the TB after the Southwest Monsoon (September) causes shrinkage of the area of the oligohaline and mesohaline conditions, the most conducive environment for the peak spawning and larval production of black clam in the KBW. This study presents a clear case of how human alterations of the natural environment impact valuable biological resources, which may apply to many similar aquatic ecosystems across the globe.
    Źródło:
    Oceanologia; 2021, 63, 3; 343-355
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on the Change in Characteristics of Ring Yarn during Post Spinning and Yarn Dyeing Operations
    Badanie zmian właściwości przędz pierścieniowych podczas przędzenia i barwienia
    Autorzy:
    Saravanan, A. R.
    Subramanian, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/231968.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
    Tematy:
    yarn abrasion
    cone winding
    hairiness
    ring spinning
    ring yarn
    singeing
    yarn imperfections
    yarn tenacity
    yarn dyeing
    ścieranie przędzy
    nawijanie stożka
    włochatość
    wirowanie pierścienia
    przędza pierścieniowa
    niedoskonałości przędzy
    wytrzymałość przędzy
    barwienie przędzy
    Opis:
    The origin of yarn hairiness has been attributed to the escape of fibres from the twisting action from within the spinning triangle. The protruding fibres entangle themselves due to the rubbing of yarn with parts of the machinery during post spinning operations and form thin places, thick places and neps. In this study, cotton combed yarns were produced by removing 14, 16 and 18% of the noil at the comber. These samples were dyed before and after singeing. The hairiness, imperfections and tenacity of the yarns were measured. The results revealed that an increase in comber noil causes a decrease in imperfections at the ring bobbin stage. The imperfections changed at different stages of post spinning operations and dyeing, and finally the difference was not appreciable, especially when the noil % was extracted beyond a certain level. The tenacity of yarn decreased when the ring bobbin was converted into a cone form, singed and dyed. Removal of a higher level of comber noil or singeing did not make a significant difference at the dyed yarn stage, although there was difference at the ring bobbin and cone stages.
    Pochodzenie włochatości przędzy przypisuje się ucieczce włókien podczas procesu skręcania. Wystające włókna splątują się w wyniku styczności przędzy z częściami maszyn podczas operacji przędzenia i tworzą pocienienia i wzgrubienia. W pracy wytworzono przędze czesankowe, które następnie barwiono przed i po opalaniu. Zmierzono włochatość, niedoskonałości i wytrzymałość przędz. Wyniki ujawniły, że niedoskonałości przędz zmianiły się na różnych etapach operacji po przędzeniu i farbowania, a na końcu różnica nie była znacząca. Wytrzymałość przędzy zmniejszyła się, gdy cewka pierścieniowa została przekształcona w postać stożka. Usunięcie wyższego poziomu zgrubienia lub uskoki nie spowodowało istotnej różnicy w poziomie wybarwienia przędzy.
    Źródło:
    Fibres & Textiles in Eastern Europe; 2018, 3 (129); 35-39
    1230-3666
    2300-7354
    Pojawia się w:
    Fibres & Textiles in Eastern Europe
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The random of lacunary statistical on χ2 over p-metric spaces defined by Musielak
    Autorzy:
    Subramanian, N.
    Babu, R.
    Thirunavukkarasu, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/357913.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
    Tematy:
    analytic sequence
    double sequences
    χ2 space
    Musielak-modulus function
    random p-metric space
    lacunary sequence
    statistical convergence
    analiza funkcjonalna
    ciąg podwójny
    funkcja Musielaka
    zbieżność statystyczna
    przestrzeń metryczna
    przestrzeń Banacha
    Opis:
    Mursaleen introduced the concepts of statistical convergence in random 2-normed spaces. Recently Mohiuddine and Aiyup defined the notion of lacunary statistical convergence and lacunary statistical Cauchy in random 2-normed spaces. In this paper, we define and study the notion of lacunary statistical convergence and lacunary of statistical Cauchy sequences in random on χ2 over p- metric spaces dfined by Musielak and prove some theorems which generalizes Mohiuddine and Aiyup results.
    Źródło:
    Journal of Mathematics and Applications; 2015, 38; 133-150
    1733-6775
    2300-9926
    Pojawia się w:
    Journal of Mathematics and Applications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Screening and characterization of Fibrinolytic protease producing Bacillus circulans from mangrove sediments pitchavaram, South East Coast of India
    Autorzy:
    Sadeesh Kumar, R.
    Rajesh, R.
    Gokulakrishnan, S.
    Subramanian, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/11234.pdf
    Data publikacji:
    2015
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Opis:
    Regulation and production of Fibrinolytic enzymes from bacterial sources especially from Bacillus strains has taken a leading role in the medical sciences for the treatment of cardiovascular disorders as it removes thrombus or clots adding to its significant role in curing human health issues saving millions. Significant progress has been made during the last few years on the studies of fibrinolytic enzymes in identifying, cloning, purification, characterization and overproduction of these for commercialization in medical sciences and in fields like detergents development. Production of fibrinolytic enzyme from Bacillus circulans was done using Nutrient broth medium. In addition, a strong fibrinolytic enzyme was purified from the cultivation media. The purified enzyme was almost homogeneous with other species of same genus, as examined by SDS−PAGE and sephadex G-75 column chromatography. The enzyme had an optimal pH of 7-12, an optimal temperature of 50 °C, for fibrin hydrolysis. The molecular mass estimated by gel filtration was 24 to36 KDa. Further studies for characterization and structural elucidation are necessary for their medicinal applications and molecular biological characteristics.
    Źródło:
    International Letters of Natural Sciences; 2015, 01
    2300-9675
    Pojawia się w:
    International Letters of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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