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Wyszukujesz frazę "Raja, S." wg kryterium: Autor


Wyświetlanie 1-21 z 21
Tytuł:
Investigation on surface roughness and kerf analysis in abrasive water jet machining of silicon carbide
Autorzy:
Hynes, N.R.J.
Asirvatham, A.D.
Sankaranarayanan, R.
Raja, S.
Benita, B.
Atchaya, J.
Powiązania:
https://bibliotekanauki.pl/articles/24200627.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
ceramic
cutting
abrasive water jet machining
ceramika
cięcie
cięcie strumieniem wodno-ściernym
Opis:
Purpose: Machining silicon carbide (SiC) is challenging due to its brittle and maximum tensile nature. Lapping or laser beam are done with a high cost of manufacturing and low material removal rates. Water abrasive jet cutting is a promising candidate since the machining temperatures and processing force of ceramics are extremely low. Investigation into the abrasive water jet machining of silicon carbide is carried out in the present work. Design/methodology/approach: The variations in traverse speed while abrasive water jet cutting of silicon carbide and its effect on the surface roughness and kerf characteristics are studied. Silicon Carbide abrasive material is used as garnet consisting of 80 mesh. The surface roughness was calculated along with the depth of the cut made during the processing. Findings: The outcomes demonstrated that the traverse speed is more effective upon the surface roughness and is an important factor that damages the top kerf width and the kerf taper angle. Research limitations/implications: Based on the hardness and thickness of the SiC plate, the taper angle is high, and for a feed rate of 10 mm/min, the surface roughness is low. Less thickness of the SiC plate could have a lower taper angle than with high thickness. The erosive force is provided by abrasive material along with the jet stream. Practical implications: Water abrasive fine jet could effectively machinate silicon carbide ceramic material with a better surface finish accurately. Suitable surface roughness with higher productivity can be attained with medium traverse speed. Originality/value: The effect of process parameters on kerf taper angle and top kerf width in the abrasive water jet machining of silicon carbide is explored, considering surface roughness as an important output parameter.
Źródło:
Archives of Materials Science and Engineering; 2023, 120, 1; 30--35
1897-2764
Pojawia się w:
Archives of Materials Science and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An optimized design for non-zero dispersion shifted fiber with reduced nonlinear effects for future optical networks
Autorzy:
Raja, A S
Selvendran, S
Priya, R
Mahendran, C
Powiązania:
https://bibliotekanauki.pl/articles/173400.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
dense wavelength division multiplexing
non-zero dispersion shifted fiber
refractive index profile
effective area
dispersion slope
Opis:
Accommodation of many channels in dense wavelength division multiplexing networks raises the average power density of the optical networks. This results in severe nonlinear effects in the optical networks. An optimized design of non-zero dispersion shifted fiber with an enormous effective area can overcome this nonlinear effect and also offer a minimum bending loss and splice loss for a dense wavelength division multiplexing system. In this paper, the alpha-peak profile is utilized for calculating electrical field distribution and designing the refractive index profile of the non-zero dispersion shifted fiber. This fiber has a high effective area of about 120 μm2. Conjointly, the accomplished fiber has a very low bending loss of 1.40×10–14 dB/km and reduced splice loss of 4.46×10–3 dB. Due to this high effective area, the dense wavelength division multiplexing network performance is upgraded by diminishing nonlinear effects. In addition, the newly designed fiber has also a very low dispersion slope (0.057 ps/nm2km). Thus, the proposed fiber is optimized to handle high bandwidth and multiple high bit-rate wavelength channels without nonlinear impairments in the 1.55 μm window long-haul dense wavelength division multiplexing systems.
Źródło:
Optica Applicata; 2014, 44, 4; 503-519
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using Anthropogenic Waste (Steel Slag) to Enhance Mechanical and Wear Properties of a Commercial Aluminium Alloy A356
Autorzy:
Sridhar Raja, K. S.
Bupesh Raja, V. K.
Gupta, Manoj
Powiązania:
https://bibliotekanauki.pl/articles/353592.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
A356
steel slag
wear resistance
tensile strength
industrial waste
environmental hazard
Opis:
The present study addresses the utilization of induction furnace steel slag which is an anthropogenic waste, for enhancing the mechanical properties of a commercial aluminium alloy A356. Different weight percentage (3wt%, 6wt%, 9wt%, and 12wt%) of steel slag particles in 1 to 10 μm size range were used as reinforcing particles in aluminium alloy A356 matrix. The composites were prepared through stir casting technique. The results revealed an improvement in mechanical properties (i.e. microhardness and tensile strength) and wear resistance with an increase in weight percentage of the steel slag particles. This research work shows promising results for the utilization of the steel slag for enhancing the properties of aluminium alloy A356 at no additional cost while assisting at same time in alleviating land pollution.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 1; 279-284
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of a goal programming approach for safety management practices on the performance of a selected Indian construction organization
Autorzy:
Prasad, S.V.S. Raja
Powiązania:
https://bibliotekanauki.pl/articles/111769.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Menedżerów Jakości i Produkcji
Tematy:
safety management
occupational health safety
management systems
safety performance
goal programming
zarządzanie bezpieczeństwem
bezpieczeństwo i higiena pracy
systemy zarządzania
wskaźnik wypadków
wypadkowość
Opis:
The construction industry in India is the second most important contributor to its gross domestic product. However, high rate of accidents and fatalities have tarnished the image of industry in India. Although the industry contributes significantly to the Indian economy, safety management is the primary concern alongside with frequent workplace accidents. The role of safety management is vital to improve safety performance of an organization. The functions of safety management include planning, organizing, staffing, directing, controlling and coordinating safety activities with an aim to minimize accidents/injuries. Safety trainings, employee participation, compliance of safety procedures and motivational schemes are part of safety management which influences the overall safety performance. Several metrics were developed to measure the safety performance of an organization but not a single measure will reflect the overall performance. The present study considered parameters pertaining to the safety management which have influence on the safety performance of a construction organization in India. The parameters are analyzed by formulating a goal programming model. The results of the study suggests that much improvement is needed in the area of safety trainings and the revised targets were established.
Źródło:
Production Engineering Archives; 2019, 24; 43-47
2353-5156
2353-7779
Pojawia się w:
Production Engineering Archives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selection of Robot for Contour Crafting Using Analytical Hierarchy Process
Autorzy:
Senthilraja, S.
Raja, Muthaiah R.C.
Powiązania:
https://bibliotekanauki.pl/articles/27314864.pdf
Data publikacji:
2023
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
multi criteria decision making
MCDM
robotization in construction
contouring
analytical hierarchy process
AHP
wielokryterialne podejmowanie decyzji
robotyzacja w budownictwie
konturowanie
proces hierarchii analitycznej
Opis:
The use of robotic equipment and a new technique called contour crafting allows for the construction of buildings at lower labor and material costs. The selection of the type of robot is an important factor that affects the overall performance of the contour crafting (CC) system. Various robot configurations, such as gantry, cylindrical, and SCARA, may be employed for contour crafting. There are benefits and drawbacks to using different types of robots for various tasks, including cost, work volume, material compatibility, and precision. Identifying a proper robot using the multi-criterion decision-making (MCDM) technique is crucial for successful building automation. This article uses the analytical hierarchy process (AHP) method to rank the best robots according to several characteristics. Cartesian robots, cylindrical robots, and SCARA robots were evaluated based on cost, accuracy, work volume, surface finish, type of profile, and speed. The results showed that the gantry-type robot is the most suitable option, while the cylindrical robot is unsuitable for building construction due to lower accuracy.
Źródło:
Civil and Environmental Engineering Reports; 2023, 33, 4; 123--150
2080-5187
2450-8594
Pojawia się w:
Civil and Environmental Engineering Reports
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation of Air Entrapment and Resin Curing during Manufacturing of Composite Cab Front by Resin Transfer Moulding Process
Autorzy:
Raghu Raja Pandiyan, K.
Neogi, S.
Powiązania:
https://bibliotekanauki.pl/articles/354935.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resin transfer moulding
mould filling simulations
air entrapment
resin curing
process optimization
Opis:
Mould filling and subsequent curing are the significant processing stages involved in the production of a composite component through Resin Transfer Moulding (RTM) fabrication technique. Dry spot formation and air entrapment during filling stage caused by improper design of filling conditions and locations that lead to undesired filling patterns resulting in defective RTM parts. Proper placement of inlet ports and exit vents as well as by adjustment of filling conditions can alleviate the problems during the mould filling stage. The temperature profile used to polymerize the resin must be carefully chosen to reduce the cure time. Instead of trial and error methods that are expensive, time consuming, and non-optimal, we propose a simulation-based optimization strategy for a composite cab front component to reduce the air entrapment and cure stage optimization. In order to be effective, the optimization strategy requires an accurate simulation of the process utilizing submodels to describe the raw material characteristics. Cure reaction kinetics and chemo-rheology were the submodels developed empirically for an unsaturated polyester resin using experimental data. The simulations were performed using commercial software PAM RTM 2008, developed by ESI Technologies. Simulation results show that the use of increase in injection pressure at the inlet filling conditions greatly reduce the air entrapped. For the cab front, the alteration of injection pressure with proper timing of vent opening reduced the air entrapped during mould filling stage. Similarly, the curing simulation results show that the use of higher mould temperatures effectively decreases the cure time as expected.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1839-1844
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PSO based optimal location and sizing of SVC for novel multiobjective voltage stability analysis during N – 2 line contingency
Autorzy:
Mangaiyarkarasi, S. P
Sree Renga Raja, T.
Powiązania:
https://bibliotekanauki.pl/articles/140430.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
N – 2 contingency analysis
voltage severity
particle swarm optimization (PSO)
SVC
power system planning
Opis:
In this paper voltage stability is analysed based not only on the voltage deviations from the nominal values but also on the number of limit violating buses and severity of voltage limit violations. The expression of the actual state of the system as a numerical index like severity, aids the system operator in taking better security related decisions at control centres both during a period of contingency and also at a highly stressed operating condition. In contrary to conventional N – 1 contingency analysis, Northern Electric Reliability Council (NERC) recommends N – 2 line contingency analysis. The decision of the system operator to overcome the present contingency state of the system must blend harmoniously with the stability of the system. Hence the work presents a novel N – 2 contingency analysis based on the continuous severity function of the system. The study is performed on 4005 possible combinations of N – 2 contingency states for the practical Indian Utility 62 bus system. Static VAr Compensator is used to improve voltage profile during line contingencies. A multi- objective optimization with the objective of minimizing the voltage deviation and also the number of limit violating bus with optimal location and optimal sizing of SVC is achieved by Particle Swarm Optimization algorithm.
Źródło:
Archives of Electrical Engineering; 2014, 63, 4; 535-550
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative investigation of friction stir welding and fusion welding of 6061 T6 – 5083 O aluminum alloy based on mechanical properties and microstructure
Autorzy:
Jannet, S.
Mathews, P. K.
Raja, R.
Powiązania:
https://bibliotekanauki.pl/articles/202165.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
TIG
MIG
FSW
Opis:
This paper compares, the mechanical properties of welded joints 6061 T6 and 5083 O aluminium alloys obtained using friction stir welding (FSW) at four rotation speeds namely 450,560,710 and 900 rpm and that by conventional fusion welding. FSW welds were carried out on a milling machine. The performance of FSW and Fusion welded joints were identified using tensile test, hardness test and microstructure. The properties of FSW and fusion welded processes were also compared with each other to understand the advantages and disadvantages of these processes for welding applications for Al alloys. It was seen that the tensile strength obtained with FSW was higher as compared to conventional fusion welding process. The width of the heat affected zone of FSW was narrower than Fusion welded joints. The results showed that FSW improved the mechanical properties of welded joints.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2014, 62, 4; 791-795
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of process parameters of friction stir welded AA 5083-O aluminum alloy using Response Surface Methodology
Autorzy:
Jannet, S.
Mathews, P. K.
Raja, R.
Powiązania:
https://bibliotekanauki.pl/articles/202208.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
friction stir welding
optimization
Response Surface Analysis
Analysis of Variance
tensile strength
spawanie
tarcie
optymalizacja
RSA
wytrzymałość na rozciąganie
Opis:
A methodology was exhibited to create the experimental model for assessing the Ultimate Tensile Strength of AA 5083-O aluminum compound which is broadly utilized as a part of boat building industry by Friction Stir Welding (FSW). FSW process parameters, such as: tool rotational speed, welding speed, and axial force were optimized for better results. FSW was completed considering three-component 3-level Box Behnekn Design. Response surface Methodology (RSM) was implemented to obtain the relationship between the FSW process parameters and ultimate Tensile Strength. Analysis of Variance (ANOVA) procedure was utilized to check the aptness of the created model. The FSW process parameters were additionally streamlined utilizing Response Surface Methodology (RSM) to augment tensile strength. The joint welded at a rotational speed of 1100 rpm, a welding speed of 75 mm/min and a pivotal energy of 2.5 t displays higher tensile strength compared with different joints in comparison with other joints.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2015, 63, 4; 851-855
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and characterization of AA5083 and AA2024 reinforced with SiO2 particles
Autorzy:
Raja, R.
Jannet, S.
Thampy, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/200119.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
in situ reaction
SEM
wear rate
stir casting
tensile strength
EDX
reakcja in situ
szybkość zużywania
wytrzymałość na rozciąganie
Opis:
Among the types of different particulates, silica is a standout as one of the the cheapest and low-density particulates accessible in substantial amounts. The present study has been centered around the synthesis and study of aluminum matrix composite strengthened with nano-sized SiO2  particles of various weight percentage by means of the stir casting technique. The EDX emphasized the presence of various elements and augmented the in situ reaction. The tensile strength and wear studies were also carried out. The reinforcement materials percentage variation was one of the important factors for the present studies. The Aluminum Alloy 5083 and 2024, which are magnesium and copper-based alloys, had a significant effect on the material characterization.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2018, 66, 2; 127-132
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Advanced helical gear reducer design optimization through nature inspired algorithms
Autorzy:
Ebenezer, N. Godwin Raja
Saravanan, R.
Ramabalan, S.
Navaneethasanthakumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/1178368.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
CS
DIN Standards
FA
GA
Helical gear reducer design
MATLAB solvers fmincon
Nature inspired Algorithms SA
metaheuristics
optimization
Opis:
In this paper a high power helical gear pair design optimization problem is solved. It is a multi variable, complex non linear problem with derived objective function and constraints. The objective is to minimize the volume of the gear. The design parameters considered are module, face width, number of teeth on drive and driven and helix angle. The various factors for sizing and strength of gear geometry parameters are based on German Institute for Standardization (DIN) Standards. Nature inspired algorithms, namely, Simulated Annealing (SA), Fire fly (FA) and Cuckoo Search (CS) and MATLAB solvers fmincon, GA are used. Simulation results are analysed and compared with literature.
Źródło:
World Scientific News; 2017, 77, 2; 267-280
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Worm Gear Drive optimization Considering Industry Constraints Based on Nature Inspired Algorithms
Autorzy:
Ebenezer, N. Godwin Raja
Saravanan, R.
Ramabalan, S.
Navaneethasanthakumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/1179011.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
CS
FA
Gear optimization
Industry relevant constraints
MATLAB solvers GA
Nature inspired algorithms SA
Worm gear drive
fmincon
Opis:
This paper presents a novel method to obtain optimum design for a worm gear drive used in sugar industries taking into account certain constraints of industrial relevance. The objective of this research is to minimize volume of worm gear drive. Gear ratio, face width and pitch circle diameters of worm and worm wheel are considered as design variables. Industry relevant constraints viz. gear strength capacity, wear capacity, thermal capacity, dynamic load, self locking, and face width are considered. Besides this other constraints such as maximum power transmission capacity, centre distances, deflection of worm and beam strength of worm are also considered. Nature inspired optimization algorithms, namely, Simulated Annealing (SA), Firefly (FA), Cuckoo Search (CS) and MATLAB solvers fmincon and GA are used for solving this problem in MATLAB environment. Results of simulation are analysed and presented.
Źródło:
World Scientific News; 2017, 87; 205-221
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Proximate composition of bio potential seaweeds from mandapam South East coast of India
Autorzy:
Gokulakrishnan, S.
Raja, K.
Sattanathan, G.
Subramanian, J.
Powiązania:
https://bibliotekanauki.pl/articles/11731.pdf
Data publikacji:
2015
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
Proximate composition of the three green seaweeds viz., Chaetomorpha aerea, Enteromorpha intestinalis, Enteromorpha compressa one brown seaweed Dictyota dichotoma and one red seaweed Gracilaria corticata was investigated by determination of protein, carbohydrates, lipid, moisture and ash content. In the present study, the total protein was recarded upper most in E. intestinalis and bare minimum in E. compressa. The maximum carbohydrates recorded in C. aerea and minimum in G. corticata. The lipid content was acquired upper limit in E. compressa and least in C. aerea. The ash and moisture content in following of 5 different seaweeds are as follows: 7.45mg/g, 3.91mg/g were recorded in the C. aerea, 8.52mg/g, 3.42mg/g in the E. intestinalis, 8.58mg/g, 3.75mg/g in the E. compressa, 9.47mg/g, 4.23mg/g in the D. dichotoma and 6.95mg/g, 3.98mg/g in G. corticata. The proximate composition of 5 different seaweed species exhibited high nutritional value for human consumption.
Źródło:
International Letters of Natural Sciences; 2015, 45
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of flow pattern on a hydrofoil with structural and profile modification
Autorzy:
Chada, Jithendra Sai Raja
Rao, B. S. V. Rama
Powiązania:
https://bibliotekanauki.pl/articles/2106431.pdf
Data publikacji:
2022
Wydawca:
Politechnika Koszalińska. Wydawnictwo Uczelniane
Tematy:
hydrofoil
groves
angle of attack
CFD
fine mesh
validation
wodolot
kąt natarcia
walidacja
Opis:
Moving through water takes much more effort than walking through air, and this explains why ships travel much more slowly than automobiles and aircraft. Water is almost 1000 times denser than air, so most of the energy produced by a boat is taken up by dragging (water resistance). Hydrofoils travel much more quickly than ordinary boats, not by pushing through water but by raising the hull (the main body) of the boat upward so it can glide above the waves. Hydrofoil is one of the typical factors that affect the vortex structure and flow characteristics of hydraulic machinery. In order to enhance the utilisation efficiency of hydraulic machinery in marine energy, parallel grooves are proposed and applied to the hydrofoil. Following that, a numerical analysis is performed using the SST k- turbulence model, and the effects of the hydrofoil profile, the angle of attack and the flow are investigated. The profiles of NACA 0066, NACA 8412, NACA M2 and RAE 104 are considered for the study. The performance is analysed based on the lift to drag ratio. The best model from this is given with surface modification and the flow study is carried out at different angles of attack. The modified profile of NACA 8412 with parallel groves has shown the highest lift to drag ratio at a 12 degree angle of attack.
Źródło:
Journal of Mechanical and Energy Engineering; 2022, 6, 1; 27--32
2544-0780
2544-1671
Pojawia się w:
Journal of Mechanical and Energy Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studies on Viscoelastic, Thermal and Morphological Properties of Vinyl Ester - Mixed Diluents System
Autorzy:
Ranjan, J. K.
Raghu Raja Pandiyan, K.
Goswami, S.
Powiązania:
https://bibliotekanauki.pl/articles/354420.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vinyl ester resin
dynamic mechanical analysis
TGA
DSC
morphology
Opis:
Vinyl ester resin networks formed by using mixture of diluents were prepared. Methyl methacrylate (MMA) diluent was mixed in various proportions with vinyl ester resin which was already premixed with styrene diluent (45 wt. %). Weight ratios e.g. 80:20, 70:30 and 60:40 of VE resin: MMA diluents were studied. Viscoelastic properties of the cross-linked resin were studied by dynamic mechanical analyzer in terms of storage modulus and tanδ. Thermal analysis was performed using non-isothermal mode of Differential scanning calorimetry. The samples with mixed diluents, showed higher modulus, and glass transition temperature in comparison to that of the pure vinyl ester-styrene resin cross-linked in presence of styrene only. The difference in thermal stability between vinyl ester-styrene and vinyl ester-MMA-styrene was checked. Vinyl Ester – 20 wt. % MMA-Styrene samples have the best thermal property among all other prepared samples. Multiphase morphology was formed for the thermoset crosslinked with mixed diluents in contrast to that formed with single diluent. With increase in MMA content in the resin dispersed domain size increased.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1845-1850
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new ratio estimator: an alternative to regression estimator in survey sampling using auxiliary information
Autorzy:
Subzar, Mir
Maqbool, S.
Raja, T. A.
Sharma, Prayas
Powiązania:
https://bibliotekanauki.pl/articles/1186907.pdf
Data publikacji:
2019-12-10
Wydawca:
Główny Urząd Statystyczny
Tematy:
simple random sampling
Opis:
The most dominant problem in the survey sampling is to obtain the better ratio estimators for the estimation of population mean or population variance. Estimation theory is enhanced by using the auxiliary information in order to improve on designs, precision and efficiency of estimators. A modified class of ratio estimator is suggested in this paper to estimate the population mean. Expressions for the bias and the mean square error of the proposed estimators are obtained. Both analytical and numerical comparison has shown the suggested estimator to be more efficient than some existing ones. The bias of the suggested estimator is also found to be negligible for the population under consideration, indicating that the estimator is as good the regression estimator and better than the other estimators under consideration.
Źródło:
Statistics in Transition new series; 2019, 20, 4; 181-189
1234-7655
Pojawia się w:
Statistics in Transition new series
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antidiabetic and antiplatelet aggregation study of various methanol fractions of Nymphaea stellata Willd. leaves
Studium działania przeciwcukrzycowego i antyagregacyjnego różnych frakcji wyciągu metanolowego z liści Nymphaea stellata Willd
Autorzy:
Raja, M.M.
Mishra, S.H.
Tamboli, R.S.
Agilandeswari, D.
Powiązania:
https://bibliotekanauki.pl/articles/950585.pdf
Data publikacji:
2017
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Tematy:
stz-nad
ptp1b inhibition
adp induced
co-tlc
histopathology
Opis:
Introduction: Nymphaea stellata Willd. (Nymphaeaceae) is traditionally used for the treatment of diabetes. Alcohol extract of N. stellata leaves has been reported for hypoglycaemic activity. Objective: The aim of this study was to further investigate the different methanol fractions of N. stellata leaves for anti-diabetic activity and anti-platelet aggregation activity. Methods: Methanol extract was fractioned in to unsaponified petroleum ether fraction of methanol extract (UPFME), chloroform fraction of methanol extract (CFME) and residual fraction of methanol extract (RFME). All fractions were evaluated for in vivo anti-diabetic activity (STZ-NAD-induced rat model), in vitro anti-diabetic activity (PTP1B inhibition study) and anti-platelet aggregation activity. Results: UPFME showed significant changes in all studied parameters, compared to the diabetic control. UPFME also showed an IC50 value of 19.30±1.1 mg/ml and 13.11±0.7 μg/ml in PTP1B inhibition study and anti-platelet aggregation study, respectively. Conclusion: The study indicates that UPFME of N. stellata leaves exhibit anti-diabetic and anti-platelet aggregation activity.
Wstęp: Nymphaea stellata Willd. (Nymphaceae) jest tradycyjnie stosowana w leczeniu cukrzycy. Istnieją doniesienia o działaniu hipoglikemicznym wyciągu alkoholowego z liści tej rośliny. Cel: Celem pracy były dalsze badania właściwości przeciwcukrzycowych i antyagregacyjnych różnych frakcji metanolowego wyciągu z liści N. stellata. Metodyka: Ekstrakt metanolowy frakcjonowano na niezmydloną frakcję otrzymaną za pomocą eteru naftowego (UMFME), frakcję otrzymaną za pomocą chloroformu (CFME) oraz pozostałość ekstraktu metanolowego (RFME). Wszystkie frakcję były badane w kierunku działania przeciwcukrzycowego in vivo (w modelu szczurzym cukrzycy wywołanej przy pomocy STZ-NAD), w kierunku aktywności przeciwcukrzycowej w badaniach in vitro (badania hamowania PTP1B) oraz w celu określenia aktywności antyagregacyjnej. Wyniki: Stosowanie frakcji UMFME powodowało znaczące zmiany we wszystkich badanych parametrach zwierząt doświadczalnych (w porównaniu do grupy kontrolnej z wywołaną cukrzycą). Wartość IC50 dla frakcji UMFME wynosiła 19,30±1,1 μg/ml w badaniu hamowania PTP1B oraz 13,11±0,7 μg/ml w badaniu działania antyagregacyjnego. Wnioski: Otrzymane wyniki badań wskazują, że frakcja UMFME z liści N. stellata wykazuje aktywność przeciwcukrzycową i antyagregacyjną.
Źródło:
Herba Polonica; 2017, 63, 3
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability of impulsive Hopfield neural networks with Markovian switching and time-varying delays
Autorzy:
Raja, R.
Sakthivel, R.
Anthoni, S. M.
Kim, H.
Powiązania:
https://bibliotekanauki.pl/articles/907824.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
sieć neuronowa
stateczność stochastyczna
funkcja Lapunowa
Hopfield neural networks
Markovian jumping
stochastic stability
Lyapunov function
impulses
Opis:
The paper is concerned with stability analysis for a class of impulsive Hopfield neural networks with Markovian jumping parameters and time-varying delays. The jumping parameters considered here are generated from a continuous-time discrete-state homogenous Markov process. By employing a Lyapunov functional approach, new delay-dependent stochastic stability criteria are obtained in terms of linear matrix inequalities (LMIs). The proposed criteria can be easily checked by using some standard numerical packages such as theMatlab LMI Toolbox. A numerical example is provided to show that the proposed results significantly improve the allowable upper bounds of delays over some results existing in the literature.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2011, 21, 1; 127-135
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hypolipidemic action of rutin on triton WR-1339-induced hyperlipidemia in rats
Autorzy:
Livingston Raja, N.R.
Nair, A.R.
Senthilpandian, S.
Ravi, V.
Powiązania:
https://bibliotekanauki.pl/articles/2098294.pdf
Data publikacji:
2020
Wydawca:
Instytut Medycyny Wsi
Tematy:
rutin
flavonoids
triglyceride
atorvastatin
Triton WR-1339
hyperlipidemia
cholesterol
rat
Opis:
Introduction and objective. Hyperlipidemia is considered as a serious communal problem in developed countries, caused by an excess level of cholesterol in blood circulation. It leads to chronic illness and even death in human beings. As the currently available drugs cause unexpected side-effect, the aim of this study is to concentrate on naturally occurring flavonoids which can potentially provide defensive and therapeutic effects in atherosclerosis diseases, and investigate the hypolipidemic effect of rutin on Triton WR-1339 triggered hyperlipidemia in a rat blood sample. Materials and method. Rats were randomly prearranged into five different groups of five rats each. Group-I was the non-disease control and administered normal saline. Group-II was the atherogenic control, administered Triton WR 1339 (200 mg/kg BW). Group-III was standard and received Atorvastatin. The last two groups (IV, V) were tested (I&II) by administering administered Rutin (40 mg/kg, 80 mg/kg) orally. The test material (I&II) and the standard drug were administered for seven days. After the last dose, blood samples were collected and the lipid levels estimated in the blood samples. Results. Rats treated with rutin flavonoid at a dose of 40 mg/kg & 80mg/kg exhibited a reduction in Total Cholesterol, Triglycerides, Low Density Lipoprotein (LDL) and Very Low Density Lipoprotein (VLDL). Rutin also increases the High Density Lipoprotein (HDL), compared with control rats. Rutin treated rats exhibited dose-dependent hypolipidemic activity. The protection percentage of rutin against hyperlipidemia was observed as 41.89%, 55.57% whereas the atorvastatin treated group protection was observed at 60.63%. Conclusions. The results of the study revealed that rutin showed a significant hypolipidemic effectiveness on Triton WR- 1339 induced hyperlipidemia in rats.
Źródło:
Journal of Pre-Clinical and Clinical Research; 2021, 15, 2; 51-55
1898-2395
Pojawia się w:
Journal of Pre-Clinical and Clinical Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Utilization of wrightia tinctoria nano seed fibers as a reinforcement in the preparation of epoxy-based composites
Autorzy:
Syed, Habibunnisa
Nerella, Ruben
Madduru, Sri Rama Chand
Reddy S, Raja Gopal
Powiązania:
https://bibliotekanauki.pl/articles/2175204.pdf
Data publikacji:
2022
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
wrightia tinctoria nano seed fibers
WTNSFs
plain epoxy composite
tensile
flexural
impact strength
water absorption
test
nanowłókna nasienne
kompozyt epoksydowy
rozciąganie
zginanie
siła uderzenia
testy
absorpcja wody
Opis:
Natural seed fiber reinforced composite materials are replacing many conventional ones because of their excellent properties, less weight, easy availability, etc. Composite materials are used in many areas because of their superior features. Mechanical property is one of the vital parameters for choosing the material. The current investigation has revealed an importance of recently well-known Wrightia tinctoria nano seed fibers (WTNSFs), which are extracted physically. Wrightia tinctoria nano seed fiber reinforced composite was prepared with the epoxy resin by hand layup method. Epoxy resin is easy to handle and available at low cost. Mechanical tests are conducted reinforced composites of plain epoxy and WTNSFs to obtain strength properties like tensile, flexural, impact. Water absorption tests also performed on composites. Here, the developed composites are easy to handle, offered economically, and used primarily in marine applications due to less water absorption and good wax content. A comprehensive description of different tests and the properties of WTNSFs are studied and compared with the other existing natural fibers. This work showed that 35% combination of WTNSFs reinforced epoxy matrix offers enhanced mechanical properties with minimum water absorption compared with plain epoxy composites.
Źródło:
Acta Innovations; 2022, 45; 5--17
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
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