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Tytuł:
Erbium-doped fiber ring laser dynamical analysis for chaos message masking scheme
Autorzy:
Ali, S. Z.
Islam, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/173276.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
erbium-doped fiber ring laser chaos
optical chaos
chaos message masking
Lyapunov exponent
secure optical communication
Opis:
A detailed dynamical analysis of erbium-doped fiber ring laser cavity loss configuration for the chaos message masking scheme is carried out to optimize the generation of high quality chaos. A threefold increase in Lyapunov exponent implying higher security, and a significant increase in chaos bandwidth is achieved, both ideal for secure optical communication and nonlinear chaotic applications. The pulsed chaos is chaotic in a pulse time interval in addition to the amplitude resulting in better concealment of data pulses in a time domain. The chaos spectrum is a flat broadband and rich in spikes making spectral detection of a message more difficult. The range of five key parameters for which erbium-doped fiber ring laser retains its chaotic behaviour is also increased significantly reducing the effectiveness of a brute force attack to guess the erbium-doped fiber ring laser parameters. The chaos message masking scheme provides a higher security in comparison with additive chaos modulation scheme for implementation of chaotic optical communication using erbium- doped fiber ring laser. The security of a complete end-to-end chaotic optical communication system is tested by launching a spectral attack to estimate the message signal. The message signal clearly hides in a stronger chaotic signal and its spectral contents are not discernible.
Źródło:
Optica Applicata; 2017, 47, 3; 395-410
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
De la Vallée Poussin Summability, the Combinatorial Sum $\sum_{k=n}^{2n-1}$ (2k/k) and the de la Vallée Poussin Means Expansion
Autorzy:
Ali, Z. S.
Powiązania:
https://bibliotekanauki.pl/articles/357696.pdf
Data publikacji:
2017
Wydawca:
Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Tematy:
complete metric space
hyperbolic space
infinite product
nonexpansive mapping
random weak ergodic property
przestrzeń metryczna całkowita
przestrzeń hiperboliczna
produkt nieskończony
mapowanie
własności ergodyczne
Opis:
In this paper we apply the de la Vallee Poussin sum to a combinatorial Chebyshev sum by Ziad S. Ali in [1]. One outcome of this consideration is the main lemma proving the following combinatorial identity: with $Re(z)$ standing for the real part of z we have \[ \sum_{k=n}^{2n-1}\left({2k \atop k}\right) = Re\left(\left({2k \atop k}\right) \text{}_{2}F_{1}(1, 1/2 + n; 1 + n; 4\right) - \left({4n \atop 2n}\right) \text{}_{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] Our main lemma will indicate in its proof that the hypergeometric factors \[ _{2}F_{1}(1, 1/2 + n; 1 + n; 4); \text{ and } _{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] are complex, each having a real and imaginary part. As we apply the de la Vallee Poussin sum to the combinatorial Chebyshev sum generated in the Key lemma by Ziad S. Ali in [1], we see in the proof of the main lemma the extreme importance of the use of the main properties of the gamma function. This represents a second important consideration. A third new outcome are two interesting identities of the hypergeometric type with their new Meijer G function analogues. A fourth outcome is that by the use of the Cauchy integral formula for the derivatives we are able to give a dierent meaning to the sum: \[ \sum_{k=n}^{2n-1}\left({2k \atop k}\right) \] A fifth outcome is that by the use of the Gauss-Kummer formula we are able to make better sense of the expressions \[ \left({2n \atop n}\right)\text{}_{2}F_{1}(1, 1/2 + n; 1 + n; 4), \text{ and } \left({4n \atop 2n}\right)\text{}_{2}F_{1}(1, 1/2 + 2n; 1 + 2n; 4) \] by making use of the series denition of the hypergeometric function. As we continue we notice a new close relation of the Key lemma, and the de la Vallee Poussin means. With this close relation we were able to talk about P the de la Vallee Poussin summability of the two innite series $\sum_{n=0}^{\infty}\cos n\theta$ and $\sum_{n=0}^{\infty}(-1)^{n}\cos n\theta$. Furthermore the application of the de la Vallee Poussin sum to the Key lemma has created two new expansions representing the following functions: \[ \frac{2^{(n-1)}(1+x)^{n}(-1+2^{n}(1+x)^{n})}{n(2x+1)}, \text{ where } x=\cos \theta \] and \[ \frac {-2^{(n-1)}(-1 + 2^{n}(1-x)^{n})(1-x)^{n}} {n(2x - 1)}, \text{ where } x=\cos \theta \] in terms of the de la Vall´ee Poussin means of the two infinite series \[ \sum_{n=0}^{\infty}\cos\theta, \] and \[ \sum_{n=0}^{\infty}(-1)^{n}\cos\theta, \]
Źródło:
Journal of Mathematics and Applications; 2017, 40; 5-20
1733-6775
2300-9926
Pojawia się w:
Journal of Mathematics and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Particle swarm optimization algorithm based low cost magnetometer calibration
Autorzy:
Ali, A.
Siddharth, S.
Syed, Z.
El-Sheimy, N.
Powiązania:
https://bibliotekanauki.pl/articles/129567.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Geodetów Polskich
Tematy:
artificial intelligence
systems
measurement
navigation
algorithm
sensor
sztuczna inteligencja
systemy
pomiar
nawigacja
algorytm
Opis:
Inertial Navigation Systems (INS) consist of accelerometers, gyroscopes and a microprocessor provide inertial digital data from which position and orientation is obtained by integrating the specific forces and rotation rates. In addition to the accelerometers and gyroscopes, magnetometers can be used to derive the absolute user heading based on Earth’s magnetic field. Unfortunately, the measurements of the magnetic field obtained with low cost sensors are corrupted by several errors including manufacturing defects and external electro-magnetic fields. Consequently, proper calibration of the magnetometer is required to achieve high accuracy heading measurements. In this paper, a Particle Swarm Optimization (PSO) based calibration algorithm is presented to estimate the values of the bias and scale factor of low cost magnetometer. The main advantage of this technique is the use of the artificial intelligence which does not need any error modeling or awareness of the nonlinearity. The estimated bias and scale factor errors from the proposed algorithm improve the heading accuracy and the results are also statistically significant. Also, it can help in the development of the Pedestrian Navigation Devices (PNDs) when combined with the INS and GPS/Wi-Fi especially in the indoor environments.
Źródło:
Archiwum Fotogrametrii, Kartografii i Teledetekcji; 2011, 22; 9-23
2083-2214
2391-9477
Pojawia się w:
Archiwum Fotogrametrii, Kartografii i Teledetekcji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Approach to Design Broadband Air Backed Piezoelectric Sensor
Autorzy:
Ali, M. G. S.
Elsayed, N. Z.
Eid, E. A.
Powiązania:
https://bibliotekanauki.pl/articles/176360.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
piezoelectric
equivalent circuits
impulse response
frequency response
matching layers
z-transform
Opis:
In this work, an approach to the design of broadband thickness-mode piezoelectric transducer is presented. In this approach, simulation of discrete time model of the impulse response of matched and backed piezoelectric transducer is used to design high sensitivity, broad bandwidth, and short-duration impulse response transducers. The effect of matching the performance of transmitting and receiving air backed PZT-5A transducer working into water load is studied. The optimum acoustical characteristics of the quarter wavelength matching layers are determined by a compromise between sensitivity and pulse duration. The thickness of bonding layers is smaller than that of the quarter wavelength matching layers so that they do not change the resonance peak significantly. Our calculations show that the −3 dB air backed transducer bandwidth can be improved considerably by using quarter wavelength matching layers. The computer model developed in this work to predict the behavior of multilayer structures driven by a transient waveform agrees well with measured results. Furthermore, the advantage of this this model over other approaches is that the time signal for optimum set of matching layers can be predicted rapidly.
Źródło:
Archives of Acoustics; 2015, 40, 1; 3-10
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Simulation for Detecting Nonlinear Echoes from Microbubbles Packets
Autorzy:
Ali, M. G. S.
Elsayed, N. Z.
Eid, E. A.
Powiązania:
https://bibliotekanauki.pl/articles/177697.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
microbubbles packets
harmonic component
acoustic
radial dynamic
pressure spectrum
Opis:
This work presents a simulation of the response of packets of microbubbles in an ultrasonic pulse-echo scan line. Rayleigh-Plesset equation has been used to predict the echo from numerically obtained radial dynamics of microbubbles. Varying the number of scattering microbubbles on the pulse wave form has been discussed. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signals from individual microbubbles as well as microbubbles packets were simulated as a function of size and pressure. Two different modes of harmonic generation have been distinguished. The strength and bandwidth of the subharmonic component in the scattering spectrum of microbubbles is greater than that of the second harmonic. The pressure spectra provide quantitative and detailed information on the dynamic behaviour of ultrasound contrast agent microbubbles packet.
Źródło:
Archives of Acoustics; 2015, 40, 2; 151-157
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Debt maturity and family related directors : evidence from a developing market
Zapadalność zadłużenia i dyrektorzy związani z rodziną : dowody z rozwijającego się rynku
Autorzy:
Hussain, H. I.
Abidin, I. S. Z.
Ali, A.
Kamarudin, F.
Powiązania:
https://bibliotekanauki.pl/articles/404736.pdf
Data publikacji:
2018
Wydawca:
Politechnika Częstochowska
Tematy:
debt maturity
capital structure
family related directors
board composition
corporate governance
family firms
zapadalność zadłużenia
struktura kapitałowa
dyrektorzy rodzinni
skład zarządu
ład korporacyjny
firmy rodzinne
Opis:
This paper examines the debt maturity structures of Malaysian firms based on the presence of family-related directors (FRDs) on boards. The motivation is derived from the board composition literature, which highlights reforms taken place over the years in order to ensure proper governance mechanisms. Conversantly, debt maturities are also linked to reductions in agency costs whereby firms with short-term borrowings will be subject to greater levels of monitoring by markets. Furthermore, this reduces information asymmetry. Thus, the paper evaluates the effectiveness of FRDs in alleviating the agency problem by studying the trade-off of such presence on debt maturity structures. The study finds that firms with the presence of FRDs tend to opt for longer maturity structures. These points towards a substitution effect where firms with FRDs will not rely on short-term borrowing as a mechanism for reducing agency problems. The findings of the study are further validated given that the presence of FRDs is not motivated by firms matching strategy of assets versus liabilities. However, these firms also opt for long-term borrowing in order to mitigate potential liquidity problems. The study further documents that these firms face lower bankruptcy costs. Interestingly, the authors also document that FRD opt to lengthen maturity structures during periods of increase in share prices indicating that control by family members tend to take into consideration shareholders’ wealth maximization. The finding is valid given that most firms with FRD also tend to have significant ownership by families.
W niniejszym artykule przeanalizowano strukturę zapadalności długu malezyjskich firm w oparciu o obecność dyrektorów rodzinnych (FRD) w zarządach. Motywacja pochodzi z literatury poświęconej składom zarządów, która podkreśla reformy, które miały miejsce od lat w celu zapewnienia odpowiednich mechanizmów zarządzania. Konsekwentnie, zapadalność długu jest również powiązana z obniżeniem kosztów pośrednictwa, w wyniku czego firmy o pożyczkach krótkoterminowych będą podlegać większemu monitorowaniu na rynkach. Ponadto zmniejsza to asymetrię informacji. W związku z tym, w artykule dokonano oceny skuteczności FRD w łagodzeniu problemu agencji poprzez zbadanie zysku takiej obecności w strukturach dojrzałości długu. Badanie wykazało, że firmy z obecnością FRD wybierają dłuższe struktury dojrzałości. Wskazuje to na efekt substytucyjny, w którym firmy z FRD nie będą polegać na pożyczkach krótkoterminowych jako mechanizmie zmniejszającym problemy agencji. Wyniki badania są dalej potwierdzane, ponieważ obecność FRD nie jest uzasadniona przez firmy, które dopasowują strategię aktywów do zobowiązań. Firmy te również wybierają długoterminowe pożyczki, aby złagodzić potencjalne problemy z płynnością. Badanie to dokumentuje również, że firmy te ponoszą niższe koszty bankructwa. Co ciekawe, autorzy dokumentują również, że FRD opowiadają się za przedłużeniem struktur zapadalności w okresach wzrostu cen akcji, wskazując, że kontrola członków rodziny ma tendencję do uwzględniania maksymalizacji zamożności akcjonariuszy. Stwierdzenie jest słuszne, biorąc pod uwagę, że większość firm z FRD ma również znaczny udział rodzinny w strukturze własności.
Źródło:
Polish Journal of Management Studies; 2018, 18, 2; 118-134
2081-7452
Pojawia się w:
Polish Journal of Management Studies
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Analysis of the Electron Density and Drift Rate of Solar Burst Type III During 13th of May 2015
Autorzy:
Ali, M. O.
Hamidi, Z. S.
Shariff, N. N. M.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/1192997.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Coronal Mass Ejections (CMEs)
Sun
X-ray region
radio region
solar burst
solar flare
type III
Opis:
During 13th of May 2015, the solar wind is very high velocity, which is 733 kms-1 as compared to 367.5 kms-1. It is believed that the plasma–magnetic field interactions in the solar corona can produce suprathermal electron populations over periods from tens of minutes to several hours, and the interactions of wave-particle and wave-wave lead to characteristic fine structures of the emission. An intense and broad solar radio burst type II was recorded by CALLISTO spectrometer from 20-85 MHz. Using data from a the Blein observatory, the complex structure of solar burst type III can also be found in the early stage of the formation of type III solar burst type event due to active region AR 12339. The drift rate of solar burst type III exceeds 1.0 MHz/s with 6.318 x1012 e/m3 a density of electron in the solar corona. There were also 2 groups of solar radio burst type III were observed. This CME was detected at 08:36 UT which is 1and ½ hour after the solar burst detected. This event shows a strong radiation in radio region, but not in X-ray region.
Źródło:
World Scientific News; 2016, 31; 1-11
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First Report on Fusarium brachygibbosum Isolate FIR 16_ITS Isolated from Iraqi Wheat Plant
Autorzy:
Ali, Hamdia Z.
Hameed, Mahdi S.
Abdulrahman, Abdulrahman A.
Saood, Hutham M.
Powiązania:
https://bibliotekanauki.pl/articles/123408.pdf
Data publikacji:
2020
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
phylogenetic analysis
rDNA
Iraq
Opis:
In this study, the Fusarium Brachygibbosum fungus isolate FIR 16_ITS was isolated for the first time from the infected wheat plants in Iraq, during the winter of 2018, in the AL-Tewatha region – 20 km south east of Baghdad. In order to verify the identity of the species of the F. brachygibbosum isolate FIR 16_ITS with the growth symptoms on the wheat plants, the wheat seeds and tissue plants were obtained and used as a source for the re-isolation of the infection agent. F. brachygibbosum isolate FIR 16_ITS was hardly identified using visual approach. However, a molecular technique is important in verifying the species of F. brachygibbosum isolate FIR 16_ITS. The isolate obtained was used for the extraction of DNA and later used for the molecular identification and phylogenetic analyses based on rDNA-internal transcribed region (ITS) primer sets. The authors successfully obtained the amplified products of the ITS-rDNA region, and a sequence analysis indicated that the Fusarium sp. isolate FIR 16_ITS species screened in this study belonged to the F. brachygibbosum species. It was recorded in the NCBI under the following information NCBI; BioSample; Accession no.; SAMN11408139; ID: 11408139 and NCBI; BioProject; Accession no.; PRJNA532637; ID: 679434 (Locus Tag Prefix; E7750).
Źródło:
Journal of Ecological Engineering; 2020, 21, 3; 81-86
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ethnobotanical knowledge and folk medicinal significance of the flora of district Gujrat, Punjab, Pakistan
Autorzy:
Ali, S.S.
Hussain, K.
Nawaz, K.
Bhatti, K.H.
Bashir, Z.
Nazeer, A.
Arif, U.
Jafar, S.
Siddiqi, E.H.
Powiązania:
https://bibliotekanauki.pl/articles/2049056.pdf
Data publikacji:
2020
Wydawca:
Instytut Włókien Naturalnych i Roślin Zielarskich
Tematy:
District Gujrat
medicine
ethnomedicinal flora
survey
native people
prowincja Gujrat
lek
rośliny lecznicze używane w medycynie ludowej
rdzenni mieszkańcy
badanie ankietowe
Opis:
Introduction: Medicinal plants are the natural source of medicines used in treatment of many diseases among local communities of various countries. It is also the raw material for the pharmaceutical industry. Pakistan is a country with a variety of medicinal plants, comprehensively studied in some areas, while others still need more studies of their flora. Objectives: The study was performed to catalogue the flora of district Gujrat, Punjab, Pakistan and to assess its ethnomedicinal importance. Methods: A field survey was conducted in the Gujrat district (including Sarai Alamgir, Gujrat and Kharian) in 2019–2020 to collect the flora. Nearly 200 people of various age groups were interviewed and the questionnaire was filled, the gender and professions of the participants were also noted. Results: The plant species collected belonged to 32 different Angiosperm families i.e. Poaceae, Brassicaceae, Fabaceae, Asteraceae, Moraceae, Amaranthaceae, Apiaceae, Myrtaceae, Rutaceae, Solanaceae, Malvaceae, Euphorbiaceae and Lamiaceae. The obtained material consisted of 30 herbs, 20 shrubs and 22 trees. The floral parts used most often were leaves (63%) followed by: flower (41%), fruit (28%), stem (16%), seed (16%), bark (14%), root (13%), whole plant (12%), underground part (3%) and latex (3%). According to the study, the highest RFC (Relative Frequency of Citation) values were 0.1 in Cassia fistula L. (0.25) and the smallest RFC values were observed in Stellaria media (L.) Vill. – 0.025. The highest UV (Use Values) were noted for Achyranthes aspera L. at 0.9. In disease category, the highest value (0.67) of ICF (Informant Consensus Factor) was observed for stomach and skin infections, while the lowest ICF value was noted for diabetes and gonorrhoea (0.27). Conclusions: It was concluded that the Gujrat district is rich in useful plants that can be used in the preparation of various medicines as well as be sold on the herbal market.
Źródło:
Herba Polonica; 2020, 66, 1; 37-51
0018-0599
Pojawia się w:
Herba Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
CO2 laser spot welding of thin sheets AISI 321 austenitic stainless steel
Autorzy:
Shehab, A. A.
Nawi, S. A.
Al-Rubaiy, A. AAG
Hammoudi, Z.
Hafedh, S. A.
Abass, M. H.
Alali, M. S.
Ali, S. D.
Powiązania:
https://bibliotekanauki.pl/articles/1818484.pdf
Data publikacji:
2020
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
thin sheet metal
austenitic stainless steel
CO2 CW LSW
mechanical properties
welding profile
FE analysis
blachy cienkie
stal austenityczna nierdzewna
właściwości mechaniczne
profil spawalniczy
analiza elementów skończonych
Opis:
Purpose: The present work aims to investigate the influence of CO2 laser spot welding (LSW) parameters on welding profile and mechanical properties of lap joint of AISI 321 thin sheet metals, and analyze the welding profile numerically by finite element (FE) method. Design/methodology/approach: The weld carried out using 150 W CO2 continues wave laser system. The impact of exposure time and laser power on the welding profile was investigated using an optical microscope. Microhardness and tensile strength tests were used to evaluate the mechanical properties of the joint. Ansys software was utilized to simulate the welding profile numerically. Findings: The results revealed that 2 s exposure time and 50 W power have led to uniform welding profile and highest shear force (340 N), lower hardness gradient across the heat affected zone (HAZ) and fusion zone (FZ). Finite element (FE) analysis of the welding profile showed good agreement with experimental analysis. Research limitations/implications: The selection of laser spot welding parameters for thin sheet metal was critical due to the probability of metal vaporisation with extra heat input during welding. Practical implications: Laser welding of AISI 321 steel is used in multiple industrial sectors such as power plants, petroleum refinement stations, pharmaceutical industry, and households. Thus, selecting the best welding parameters ensures high-quality joint. Originality/value: The use of CO2 laser in continuous wave (CW) mode instead of pulse mode for spot welding of thin sheet metal of AISI 321 austenitic stainless steel consider a real challenge because of the difficulty of control the heat input via proper selection of the welding parameters in order to not burn the processed target. Besides, the maintenance is easier and operation cost is lower in continuous CO2 than pulse mode.
Źródło:
Archives of Materials Science and Engineering; 2020, 106, 2; 68--77
1897-2764
Pojawia się w:
Archives of Materials Science and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An alternative and indirect statistical modeling method for viscosity estimation and its experimental validation for low styrene content polyester resin
Autorzy:
Nawaz, A.
Islam, B.
Ijaz, M. Z.
Saleem, U.
Khattak, M. S.
Ahmad, S. N.
Maqsood, N.
Ali, L.
Powiązania:
https://bibliotekanauki.pl/articles/778495.pdf
Data publikacji:
2018
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
indirect method
polyester resin
statistical relation
Ford viscosity cup
Opis:
We propose an indirect method of ASTM D-1200 for measurement of viscosity from 0.1 to 30 stokes (St) using Ford cup 5 (range 2~ 12 St) by developing a statistical relation. General purpose low styrene content polyester resin (without adding initiator, hardener and accelerator) was used for viscosity measurement. In existing ASTM D 1200 standard, ford cups (1-4) are used to measure the viscosity up to 2 St, while fifth cup is used for measurement from 2 to 12 St. Viscosity above 12 St is not estimated using existing ASTM D- 1200 method. In contrast, our method and statistical relation proposed in this paper estimates viscosity in the flexible range of 0.1 to 30 St by using Ford cup 5 only. The estimated values were confirmed by existing ASTM D-1200 (0.1 to 12 St) and by using Ubbelohde viscometer (12 to 30 St). Values estimated above 12 St are from the proposed model are also in good conformance (percentage error ~ 5% or less) with experimental results. The satisfaction level of the estimated values with the experiments suggests that the model has also the potential for application to paints, polymer and oil industry.
Źródło:
Polish Journal of Chemical Technology; 2018, 20, 4; 60-65
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heart-shape Active Region 2529 Producing Strong M6.7 class Solar Flare and Gradual Coronal Mass Ejections
Autorzy:
Hamidi, Z. S.
Omar Ali, M.
Nurul, Hazwani Husien
Sabri, S. N. U.
Zainol, N. H.
Shariff, N. N. M.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/1179601.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Gradual Coronal Mass Ejections
Heart-shape active region
Sun
X-ray region
solar flare
Opis:
The Centre of the Sun is very important to be study because this layer is where the nuclear reaction will be occurred. During large event pre-flare usually continues a few minutes and followed by impulsive phase about 3 to 10 minutes. Solar storms such as solar flare and Coronal Mass Ejections are frequently occurred on the area of the Sun that have strong magnetic field or known as active region The release of the stored free magnetic energy that probably drives a CME can take many forms including (predominantly) mechanical in the form of an expanding CME and erupting filament, electromagnetic emission in the form of a flare, and also in the acceleration of energetic particles, magnetic field reconfiguration and bulk plasma motion. In this study, the data of active region of the Sun was taken from official website of the Langkawi National Observatory. The image of the active region was observed by using 11-inch Celestron telescope with solar filter. This data confirms that there was a strong M class of solar flare during the day due to eruption of AR 2529 was occurred on 18th of April. From the x-ray flux data also, it can be observed that few days before M6.7 class solar flare occurred, there were several C classes of flare. The evolution of small AR 2529 to a big heart-shape forms an eruption that producing strong M6.7 class of flare and three gradual CMEs. This strong flare caused significant impact around the high technologies of Pacific Ocean by fading the signal at frequencies below 15 MHz.
Źródło:
World Scientific News; 2017, 74; 181-193
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Formation of Fundamental Structure of Solar Radio Burst Type II Due X6.9 Class Solar Flare
Autorzy:
Zainol, N. H.
Hamidi, Z. S.
Shariff, N. N. M.
Ali, Marhana Omar
Husien, Nurulhazwani
Sabri, S. N. U.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/1190115.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Sun
solar burst
type II
radio region
X-ray region
solar flare
Coronal Mass Ejections (CMEs)
Opis:
A vigorous solar flare event marked on the spectrometer of the CALLISTO data, being one of the highest solar flare event that successfully detected. The formation of solar burst type II in meter region and their associated with X6. 9-class solar flares have been reported. The burst has been observed at the Blein Obsevatory, Switzerland, which detected by the Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (CALLISTO) system in the range of 170-870 MHz in the two polarizations of left and right circular polarization. It occurred between 08:01 UT to 08:08 UT within 7 minutes. The Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory CALLISTO spectrometer is a solar dedicated spectrometer system that has been installed all over the world to monitor the Sun activity in 24 hours. The growth of this burst is often accompanied by abundance enhancement of particles which may take the form of multiple independent drifting bands or other forms of fine structure. Due to the results, the drift rate of this burst is 85.71 MHz s-1, which is considered as a fast drift rate. The burst detected using CALLISTO also being compared to results detected by X-ray GOES data. Both different electromagnetic spectrum shows the exact time. The observations of the burst being discussed in details.
Źródło:
World Scientific News; 2016, 35; 30-43
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Enlargement of Type II Burst After Type III at AR 12522 on 16th March 2016 In Conjunction With Flare-Related Coronal Mass Ejections Event
Autorzy:
Husien, Nurulhazwani
Hamidi, Z. S.
Shariff, N. N. M.
Ali, M. O.
Zainol, N. H.
Sabri, S. N. U.
Monstein, C.
Powiązania:
https://bibliotekanauki.pl/articles/1178545.pdf
Data publikacji:
2017
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Coronal Mass Ejections
Sun
X-ray emission
Opis:
On 16th March 2016 the solar radio burst type II is recorded to appear on spectrograph after the type III formation. These two bursts related to the Coronal Mass Ejections (CMEs) event that recorded by the SOHO spacecraft several minutes before the formation of Type III on the spectrograph. It has been reported that the Type III burst a fast drift compared to the Type II burst. In this paper, the calculation has been proved that the type III burst has a higher drift rate compared to Type II. These two events of Type II and III burst also has been contributing to the formation of C class flare with magnitude of C2.2 It is also proven that the type III burst has a fast drift rate compared to type II burst. In this case, the type III has a fast drift rate of 81% compared to the type II burst. During this event, the active region AR 12522 erupted the C-class X-ray emission with magnitude of C2.2 contribute to these type III and II burst
Źródło:
World Scientific News; 2017, 70, 2; 230-240
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production of Coronal Mass Ejections in Relation With Complex Solar Radio Burst Type III Correlated With Single Solar Radio Burst Type III
Autorzy:
Hussien, Nurul Hazwani
Hamidi, Z. S.
Ali, M. O.
Sabri, S. N. U.
Zainol, N. H.
Shariff, N. N. M.
Moinstein, C
Powiązania:
https://bibliotekanauki.pl/articles/1192988.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Sun
Solar radio burst
type III
single Solar Radio Burst Type (SRBT) III
complex Solar Radio Burst Type (SRBT) III
Coronal Mass Ejection (CMEs)
magnetic reconnection
Opis:
The complex solar radio burst type III is very related to generation of Coronal Mass Ejections (CMEs). In a previous study, they deduced that the burst was produced by electron beams accelerated in blast wave shocks and injected along open magnetic field lines, similar to the herringbone bursts at metric wavelengths. Usually, if there is another solar flare recorded during complex solar radio burst type III it should be type II burst. Different for this event, the single solar radio burst recorded occur 8 minutes 30 seconds before the complex solar radio burst type III. The Coronal Mass Ejections also recorded occurred 7 hours before the single and complex solar radio burst type III. It is noted that CMEs occurred several hours before this event recorded by the SOHO websites.It is proved that the production of coronal mass ejection contributed to the production of complex solar radio burst type III.
Źródło:
World Scientific News; 2016, 36; 96-108
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
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