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Tytuł:
Semiconductor Superlattices with Small Band Offsets - feature article
Autorzy:
Yang, G.
Lewandowski, L. A.
Furdyna, J. K.
Ram-Mohan, L. R.
Powiązania:
https://bibliotekanauki.pl/articles/1968871.pdf
Data publikacji:
1998-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.-w
Opis:
Optical transitions in small band offset superlattices are studied within the framework of the nearly free electron approximation, in which the weak superlattice potential is treated as a perturbation. Interband selection rules are derived for transitions involving conduction and valence band states at the superlattice Brillouin zone center and the zone edge. It is found that a number of new transitions can occur in such small-offset superlattices due to wave function mixing of different subband states. The effect of the effective mass on the optical transitions is also discussed. The theory is used to explain the results observed in magneto-optical absorption experiment in ZnSe/Zn$\text{}_{1-x}$Mn$\text{}_{x}$Se small-offset superlattices. Furthermore, the nearly free electron formulation is found to be in excellent agreement with rigorous multi-band numerical calculation on superlattices involving small band offsets.
Źródło:
Acta Physica Polonica A; 1998, 93, 4; 567-600
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Far-Infrared Magneto-Optical Studies of HgTe-CdTe Superlattices in the Semimetallic Regime
Autorzy:
Wojtowicz, T.
Dobrowolska, M.
Furdyna, J.K.
Meyer, J. R.
Bartoli, F. J.
Hoffman, C. A.
Ram-Mohan, L. R.
Powiązania:
https://bibliotekanauki.pl/articles/1888086.pdf
Data publikacji:
1991-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.65.Fa
78.30.Fs
Opis:
We review recent magneto-optical investigations performed on HgTe-CdTe semimetallic superlattices. Far infrared magnetotransmission data obtained as a function of temperature, photon energy, and sense of circular polarization are compared with the predictions of a comprehensive new theory which fully incorporates the complexities of type-III superlattice band structure. It is found that the theory accounts for nearly all of the many unusual features which have been observed experimentally. These include the occurrence of two cyclotron resonances due to holes; the coexistence of electron and hole cyclotron resonances in the low temperature limit; the observation of three distinct CRA minima; a step-like change in the temperature dependence of the electron cyclotron mass; and a dramatic increase of the CRI absorption peak intensity with increasing magnetic field.
Źródło:
Acta Physica Polonica A; 1991, 80, 2; 245-254
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biochemical constituents in leaf of Carica papaya - ethnomedicinal plant of Kachchh region
Autorzy:
Vyas, S.J.
Khatri, T.T.
Ram, V.R.
Dave, P.N.
Joshi, H.S.
Powiązania:
https://bibliotekanauki.pl/articles/11094.pdf
Data publikacji:
2014
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
biochemical constituent
leaf
fruit
seed
Carica papaya
papaya
medicinal plant
ethnomedicine
treatment
Kachchh region
India
Opis:
Carica papaya Linn. is one of the valuable plant used for various purposes in medicinal field. Leaves, fruit and seeds of the C. papaya are used as ethnomedicine. This work describes biochemical constituents of leaves of C. papaya. Fresh leaves samples of the plant were collected during the month of January, 2013 from different parts of Bhuj in Kachchh district (Gujarat), India. The purpose of the study was to evaluate the biochemical composition in leaves of C. papaya growing in the semi-arid region of Gujarat and based on the result to justify its importance in various treatments of diseases. The dried leaves were further analyzed for biochemical constituents like Ca2+, Mg2+, Na+, K+, Clˉ and Li+. The results indicated that the leaf extract of C. papaya has high potentiality for curing number of diseases.
Źródło:
International Letters of Natural Sciences; 2014, 07
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency magnitude distribution and spatial correlation dimension of earthquakes in north-east Himalaya and adjacent regions
Autorzy:
Tiwari, Ram Krishna
Paudyal, Harihar
Powiązania:
https://bibliotekanauki.pl/articles/2204361.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
north-east India
b value
maximum likelihood estimation
correlation dimension
Indie północno-wschodnie
parametr b
największa wiarygodność
estymacja
wymiar korelacyjny
Opis:
The north-east sector of the Himalaya is one of the most active tectonic belts, with complex geological and tectonic features. The b-value and spatial correlation dimension (Dc) of earthquake distribution in the north-east Himalaya and its adjacent regions (20–32°N and 88–98°E) are estimated in the present study. Based on seismicity and faulting pattern, the region is divided into five active regions, namely the (i) South-Tibet, (ii) Eastern-Syntaxis, (iii) Himalayan-Frontal Arc, (iv) Arakan-Yoma belt and (v) Shillong-Plateau. A homogeneous catalogue of 1,416 earthquakes (mb ≥ 4.5) has been prepared from a revised catalogue of the ISC (International Seismological Centre). The b-value has been appraised by the maximum likelihood estimation method, while Dc values have been calculated by the correlation integral meth-od; b-values of 1.08 ± 0.09, 1.13 ± 0.05, 0.92 ± 0.05, 1.00 ± 0.03 and 0.98 ± 0.08 have been computed for the South-Tibet, Eastern-Syntaxis, Himalayan-Frontal Arc, Arakan-Yoma belt and Shillong-Plateau region, respectively. The Dc values computed for the respective regions are 1.36 ± 0.02, 1.74 ± 0.04, 1.57 ± 0.01, 1.8 ± 0.01, and 1.83 ± 0.02. These values are > 1.5, except for the South-Tibet (1.36 ± 0.02). The b-values around the global average value (1.0) reflect the stress level and seismic activity of the regions, while high Dc values refer to the heterogeneity of the seismogenic sources.
Źródło:
Geologos; 2022, 28, 2; 115--128
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neural network-based allocation and self-improved firefly-based optimal sizing of fuel cells in distributed generation systems
Autorzy:
Subramanyam, T. C.
Tulasi Ram, S. S.
Subrahmanyam, J. B. V.
Powiązania:
https://bibliotekanauki.pl/articles/1839111.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
DG system
fuel cells
location
sizing
multiple objectives
firefly algorithm
self-improved firefly algorithm
Opis:
The notion of Distributed Generation (DG) refers to the production of power at the level of consumption. Production of energy on-site, instead of offering it centrally, reduces the cost, internal dependencies, difficulties, inefficiencies, and risks that are related to transmission and distribution systems. In case DG is realized with fuel cells, several issues exist in respect to allocating and sizing of these fuel cells in the system. For solving those issues, dual stage intelligent technique is employed in this paper. First, the Neural Networks (NN) technique is adopted for determining the required location to place the fuel cells. Secondly, an enhanced version of Self Improved Fire-Fly (SIFF) algorithm is adopted for finding the optimal size of the fuel cells. The implemented technique is simulated in four IEEE benchmark test bus systems, and the respective performance analysis along with statistical analysis serves for validation purposes. The here proposed technique is compared with six other known algorithms, namely Particle Swarm Optimization (PSO), Firefly (FF) algorithm, Artificial Bee colony (ABC) algorithm, Improved Artificial Bee colony algorithm (IABC), Genetic Algorithm (GA) and Global Search Optimizer (GSO). The results obtained from the comparative analysis show the enhanced performance of the proposed mechanism.
Źródło:
Control and Cybernetics; 2018, 47, 4; 357-381
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indebtedness, Fiscal Discipline and Development Spending – A Non-parametric Approach
Autorzy:
Sinha, Ram Pratap
Powiązania:
https://bibliotekanauki.pl/articles/2075409.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Indian states
fiscal performance
efficiency
data envelopment analysis
bootstrap
Opis:
Indian states exhibit considerable heterogeneity in terms of revenue mobilizing capacities and efforts, development spending and fiscal dependence on the central government. In this context, the paper compares the fiscal performance of major Indian states in terms of two non-parametric performance evaluation models for the period 2009–10 to 2014–15. The study thus uses the conventional two stage framework for efficiency evaluation as well as the two stage conditional performance model. The outcomes enable us to identify front-runners as well as laggards in the area of fiscal management. Further, the study showed that the gross capital formation experienced by the states significantly influences state performance in India. However, the impact of outstanding liabilities on efficiency performance was statistically insignificant
Źródło:
Central European Journal of Economic Modelling and Econometrics; 2021, 2; 147-173
2080-0886
2080-119X
Pojawia się w:
Central European Journal of Economic Modelling and Econometrics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Markovian Epidemic Queueing Model with Exposed, Infection and Vaccination based on Treatment
Autorzy:
Singh, Ram
Preeti, Preeti
Raina, Ather Aziz
Powiązania:
https://bibliotekanauki.pl/articles/1166188.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Epidemic Model
Infection
Markov model
Runge kutta method
Vaccination
Opis:
In this investigation, an epidemic Markov queueing model with alert, infection, vaccination and death has been considered. The main focus of this work is on the vaccination to provide the infection in a population. Healthy person may be affected from some disease that may cause death. The vaccination is the power tool for the prevention of the diseases spreading over the population size. Healthy person become alert when symptoms of the disease can be seen on them and the alert may be injected due to more infection. The provision of vaccination is provided in both alert and infected stages. The transition rates as followed by exponential distribution. A Markov model is developed by using inflow and outflow transition rates of the model. The transient state probabilities are evaluated by solving the transient state equations by using runge kutta method which are further used for calculating the model performances. A numerical illustration is also provided to validate the model.
Źródło:
World Scientific News; 2018, 106; 141-150
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of the Mechanical and Electrical Properties of Spark Plasma Sintered Titanium Carbide Reinforced Alumina Ceramic Composite
Autorzy:
Selvakumar, G.
Prakash, S. Ram
Rajkumar, K.
Powiązania:
https://bibliotekanauki.pl/articles/2049356.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Spark Plasma Sintering
alumina composite
TiC
mechanical properties
fracture toughness
Opis:
Spark Plasma Sintering (SPS) is identified as a suitable technique to prepare the alumina titanium carbide composite to overcome the difficulty in fabricating it through other consolidation method. The present work focuses on the fabrication and characterization of a series of titanium carbide reinforced alumina ceramic composites using a spark plasma sintering process. The titanium carbide reinforcement on the alumina matrix is varied between 20 and 35 wt.%, in order to improve the electrical conductivity and fracture toughness of the composites. The particle size of the starting powders at received and ball milled conditions was analysed through Particle size analyser and Scanning Electron Microscope (SEM). Microstructural analysis revealed that the TiC reinforcement is uniformly dispersed in the sintered composite. XRD report showed that α-alumina and titanium carbide were the two dominant phases without the formation of any reaction phases. Further, the correlation between mechanical and physical properties of the prepared composite was investigated as a function of TiC. Various fracture toughening indicators like crack deflection, bridging and branching were analysed by Vicker’s indentation method. Electrical resistivity of the sintered compact decreases proportionally with the increase in titanium carbide constituents. Maximum density (98.80%) and hardness (20.56 GPa) was obtained for 30 wt. % reinforced composite. Almost 40% improvement in fracture toughness is noted for 25 wt. % reinforced composite. This work demonstrates the synthesis and fabrication of alumina titanium carbide composites at low temperature via SPS resulted in obtaining an intact compact with improved mechanical and electrical properties.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 3; 831-838
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shot peening effects on fatigue life, corrosion behavior and surface roughness of low carbon alloy steel
Autorzy:
Selva Senthil Prabhu, C.
Ashoka Varthanan, P.
Ram Kumar, T.
Powiązania:
https://bibliotekanauki.pl/articles/2086823.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surface roughness
shot peening
fatigue life
chropowatość powierzchni
śrutowanie
trwałość zmęczeniowa
Opis:
In this present study, the effect of the shot peening process on fatigue life, surface hardness and corrosion properties of a low carbon alloy steel is examined at room temperature. The research article addresses the effect of shot peening by varying the process parameters such as peening distance and pressure with amachrome as shots. The experiment is designed by means of full factorial design. The experimental result reveals that the pressure and distance are the most significant factors in the shot peening process. The results illustrate that the average pressure of 7 bar and distance of 100 mm improves fatigue life by 1.5% of unpeened material under 20 Hz frequency while corrosion resistance improves by 4% with unpeening of the low carbon alloy steel by using amachrome as a shot.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; art. no. e136214, 1--7
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Shot peening effects on fatigue life, corrosion behavior and surface roughness of low carbon alloy steel
Autorzy:
Selva Senthil Prabhu, C.
Ashoka Varthanan, P.
Ram Kumar, T.
Powiązania:
https://bibliotekanauki.pl/articles/2090715.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surface roughness
shot peening
fatigue life
chropowatość powierzchni
śrutowanie
życie zmęczeniowe
Opis:
In this present study, the effect of the shot peening process on fatigue life, surface hardness and corrosion properties of a low carbon alloy steel is examined at room temperature. The research article addresses the effect of shot peening by varying the process parameters such as peening distance and pressure with amachrome as shots. The experiment is designed by means of full factorial design. The experimental result reveals that the pressure and distance are the most significant factors in the shot peening process. The results illustrate that the average pressure of 7 bar and distance of 100 mm improves fatigue life by 1.5% of unpeened material under 20 Hz frequency while corrosion resistance improves by 4% with unpeening of the low carbon alloy steel by using amachrome as a shot.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; e136214, 1--7
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radiation stability of 125I-brachytherapy sources
Autorzy:
Saxena, S.
Ram, R.
Dash, A.
Joshi, P.
Venkatesh, M.
Powiązania:
https://bibliotekanauki.pl/articles/148254.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
retinoblastoma
125 I-brachytherapy sources
radiation stability
SEM
leach rate
Opis:
Low energy 125I-brachytherapy sources are used for the treatment of retinoblastoma and many other forms of eye cancer. Such sources were prepared by adsorption of 125I on palladium coated silver rods and were critically evaluated for safety aspects, as per AERB standards. In order to attain low leachability and to facilitate leak free laser encapsulation of sources within titanium capsules of size 0.8 mm (f) ´ 4.75 mm (l), the radioactive source core was coated with polystyrene. With a view to study the radiation stability of such sources over a period of three weeks, both polymer coated radioactive sources and inactive source cores were separately subjected to an integrated gamma dose of ~(17.85 ´ 104) Gy (17.85 MRad), which is the dose expected to be received in three weeks from a source containing ~ 111 MBq of 125I. This was carried out to test their suitability for reuse within such period. SEM pictures of inactive source cores were taken to observe the effect of gamma radiation on palladium coating. Post-irradiation leachability and uniformity of activity of radioactive sources were evaluated and found to be satisfactory. The sources were found to be reusable safely, for repeated brachytherapy procedures over a practically useful time of at least three weeks.
Źródło:
Nukleonika; 2007, 52, 1; 13-16
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and Analysis of a Hybrid Circularly Polarized Multi-Band MIMO Antenna for Sub 6 GHz Applications
Autorzy:
Salma, S.
Khan, Habibulla
Madhav, B. T. P.
Sandeep, D. Ram
Suman, M.
Powiązania:
https://bibliotekanauki.pl/articles/2055219.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
axial ratio
circular polarization
MIMO antennas
SEA
single element antenna
Opis:
In this article, a hybrid circularly polarized Multiple-Input Multiple-Output (MIMO) antenna for multi-band operation from 2.3 to 9.2 GHz with an impedance bandwidth of 7 GHz is proposed and investigated experimentally. The designed MIMO antenna model has a compact size of 20mm×40mm×1.6mm on the FR-4 substrate. The microstrip feed of the proposed slot antenna consists of a tapered structure, and the radiating element consists of the inverted L- shaped slots, which were opened on both sides of the radiating elements to introduce notches at the sub-6 GHz frequencies. L-shaped stubs are also introduced on another side of the substrate in the common ground plane to attain high isolation between the radiating elements of the proposed antenna. In the operating band from 2.3 to 9.2 GHz, isolation of less than -20 dB is achieved by the proposed model. The performance of the circularly polarized MIMO antenna in terms of RHCP and LHCP radiation patterns, axial ratio, surface current distributions, isolation between the ports, diversity gain (DG), envelope correlation coefficient (ECC), total active reflection coefficient (TARC), and peak gain are studied and presented in this work. The obtained characteristics of the proposed antenna make it suitable for sub-6-GHz frequency applications.
Źródło:
International Journal of Electronics and Telecommunications; 2021, 67, 4; 570--577
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of multiple-area renewable integrated hydro-thermal system considering artificial rabbit optimized PI (FOPD) cascade controller and redox flow battery
Autorzy:
Saha, Arindita
Chiranjeevi, Tirumalasetty
Devarapalli, Ramesh
Babu, Naladi Ram
Dash, Puja
Garcìa Màrquez, Fausto Pedro
Powiązania:
https://bibliotekanauki.pl/articles/27324511.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
solar thermal
automatic generation control
geothermal
artificial rabbit optimization
redox flow battery
PI(FOPD) controller
Opis:
The current task explores automatic generation control knowledge under old-style circumstances for a triple-arena scheme. Sources in area-1 are thermal-solar thermal (ST); thermalgeothermal power plant (GPP) in area-2 and thermal-hydro in area-3. An original endeavour has been set out to execute a new performance index named hybrid peak area integral squared error (HPA-ISE) and two-stage controller with amalgamation of proportional-integral and fractional order proportional-derivative, hence named as PI(FOPD). The performance of PI(FOPD) has been compared with varied controllers like proportional-integral (PI), proportional-integralderivative (PID). Various investigation express excellency of PI(FOPD) controller over other controller from outlook regarding lessened level of peak anomalies and time duration for settling. Thus, PI(FOPD) controller’s excellent performance is stated when comparison is undergone for a three-area basic thermal system. The above said controller’s gains and related parameters are developed by the aid of Artificial Rabbit Optimization (ARO). Also, studies with HPA-ISE enhances system dynamics over ISE. Moreover, a study on various area capacity ratios (ACR) suggests that high ACR shows better dynamics. The basic thermal system is united with renewable sources ST in area-1 also GPP in area-2. Also, hydro unit is installed in area-3. The performance of this new combination of system is compared with the basic thermal system using PI(FOPD) controller. It is detected that dynamic presentation of new system is improved. Action in existence of redox flow battery is also examined which provides with noteworthy outcome. PI(FOPD) parameters values at nominal condition are appropriate for higher value of disturbance without need for optimization.
Źródło:
Archives of Control Sciences; 2023, 33, 4; 861--884
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł

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