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Wyświetlanie 1-12 z 12
Tytuł:
Noise Response and Stability in Injection Locked Semiconductor Ring Laser
Autorzy:
Memon, M.
Fathallah, H.
Powiązania:
https://bibliotekanauki.pl/articles/1195007.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Wd
42.65.Re
42.60.By
42.65.Pc
Opis:
Stability and effects of optical injection locking in semiconductor ring laser is modeled in detail. It is verified that the injection locking in slave semiconductor ring laser depends on detuning frequency and external optical injection ratio between the master laser and the slave semiconductor ring laser. The stability of injection was locked using the resonance frequency and damping factor. The parasitic phase modulation response due to amplitude modulation (chirp response) is derived and simulated. Similarly parasitic amplitude modulation due to phase modulation response is also investigated.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 454-455
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dependence of Modulation Bandwidth on Size of Optical Injection Locked Semiconductor Ring Laser
Autorzy:
Memon, M.
Fathallah, H.
Powiązania:
https://bibliotekanauki.pl/articles/1290582.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Wd
42.65.Re
42.60.By
42.65.Pc
Opis:
It has been successfully investigated for the first time that strength of optical injection locking also depends on the size of semiconductor ring laser. Theoretical study for frequency response of optical injection locking semiconductor ring laser in the master slave configuration using direct, amplitude and phase modulation of master laser is discussed. In the unidirectional regime the locking range of semiconductor ring laser becomes wider when semiconductor ring laser with smaller size is used. Simulation results predict an incredible enhancement in the modulation bandwidth (> 500 GHz) of the slave semiconductor ring laser when used with smaller laser cavity length (50 μm) in the stable unidirectional regime.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 462-464
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Video on Demand Over Optical Wireless Communication Links
Autorzy:
Siraj, M.
Memon, M.
Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/1191713.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.40.Ua
42.15.Eq
Opis:
Video on demand technology is a modern wireless communication application which requires a large bandwidth. Optical wireless networks, as a potential alternative to radio frequency, is an emerging technology that is easier to set up and provides a cost effective solution, where a physical network is difficult to deploy. Optical wireless networks can be used as a backbone to provide the much needed bandwidth for video on demand application. In this paper, Wavelength Division Multiplexing modulation scheme is proposed for the optical wireless networks due to its significance of transmitting distinct data channels at different wavelengths. Wavelength Division Multiplexing can be easily integrated with optical wireless networks, consequently resulting in an increased data rate. This paper presents a novel approach of integrating video on demand with the state of art Wavelength Division Multiplexing based optical wireless networks. Furthermore, the paper discusses the challenges and advantages over the convention modulation schemes.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 826-828
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical mm-Wave Synthesizer Using Semiconductor Ring Laser (a Review)
Autorzy:
Memon, M.
Siraj, M.
Fathallah, H.
Powiązania:
https://bibliotekanauki.pl/articles/1193216.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Px
42.65.Hw
84.40.-x
Opis:
Millimeter wave (mm-wave) technology is significant for military needs and applications due to its numerous advantages, such as huge bandwidth, deploying small antenna and high radar resolution. Due to atmospheric influence, mm-wave is important in short-range applications such as fire control radar. Similarly for the next-generation communication and military applications, high-speed radio over fiber networks are very crucial. In this paper, a review of the generation and modulation of millimeter-wave signal optically using semiconductor ring laser (SRL) has been done. The phenomena of optical injection locking and four-wave mixing are exploited in SRL to generate radio frequency (RF) optical signals. The signals with huge data rate can be transferred directly from an intensity modulated optical signal onto a RF optical signal with RF frequency tunable in steps of the free spectrum range (FSR) of SRL. They can be converted with flexible RF modulation formats over the optical carrier.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1274-1276
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast Speed Semiconductor Ring Lasers Using Optical Injection Locking
Autorzy:
Memon, M.
Fathallah, H.
Yu, S.
Powiązania:
https://bibliotekanauki.pl/articles/1399665.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.55.Px
42.55.Sa
42.60.By
42.60.Fc
42.65.Pc
Opis:
Theoretical study for frequency response and modulation bandwidth of slave semiconductor ring laser in the master-slave configuration using optical injection locking has been investigated. Equations for frequency response of optical injection locking-semiconductor ring laser to the direct modulation, amplitude modulation of master laser, respectively, are derived and simulated. Enhancement in the modulation bandwidth of >100 GHz is reported between negative to positive detuning frequency and increasing injection power ratio.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 180-182
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Radio Frequency Generator Using Four Wave Mixing in Cascaded Nonlinear Semiconductor Optical Amplifiers
Autorzy:
Memon, M.
Siraj, M.
Fathallah, H.
Khan, M.
Powiązania:
https://bibliotekanauki.pl/articles/1398795.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.60.Da
42.60.Fc
42.65.Hw
42.79.Nv
Opis:
For the last three decades, the phenomenon of four-wave mixing is a significant technique for generation of light at new distinct wavelength. When two distinct laser beams (pump and probe) beat together in a non-linear medium, few modes are increased in the power at same distance from the probe and pump, as a result of four-wave mixing. In this paper, cascading structure of two semiconductor optical amplifiers produces very strong four-wave mixing. This technique is exploited to devise a tunable radio frequency signal generator. The wavelength distance between pump and probe laser beams determines the radio frequency of the generated signal. Using this scheme, it can be observed from the experimental results, that there is an increase of more than 3 dB in signal to noise ratio at 7 Gbits/sec data rate of the 60 GHz generated mm-wave signal. Moreover, the radio frequency can be tuned to hundreds of GHz by varying the distance between the pump and probe signals. This scheme will readily serve as future all optical radars. It is also a key technique for short-range communication systems for military applications. The above scheme can also be monolithically integrated.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 832-834
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance Enhancement of Telemedicine Network by Free Space Optics Links Provisioning
Autorzy:
Siraj, M.
Shoaib, M.
Memon, I.
Powiązania:
https://bibliotekanauki.pl/articles/1033389.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.40.Ua
Opis:
Health care has benefited immensely with the implementation of fast moving information technology. It is a challenging assignment for the researchers to implement the present day technologies such as wireless mesh networks. Wireless mesh networks are deployed to guarantee a reliable and stable network infrastructure backbone to telemedicine systems. They are preferred to other wireless networks, as the solution which they provide is robust for broadband services. They are robust because if routing is not possible due to some mesh nodes failure, routing can be done by the other mesh nodes present. Wireless mesh network cannot only spread coverage but also save both cabling cost and human resource. However, their performance is degraded due to interference and varying load. Interference is a critical issue in wireless mesh networks. The interference occurs because of the congested unlicensed radio frequency spectrum. This problem can be addressed by applying free space optics technology for transmission instead of radio frequency technology in the unlicensed spectrum. Network capacity issue is addressed by provisioning free space optics links to generate the much needed throughput and to minimize interference. Telemedicine network is a network, which requires a high capacity bandwidth to cater for a large number of remote patients. It is observed that free space optics links provisioning results in a significant performance enhancement for the telemedicine network.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 43-45
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization and equilibrium studies of Pb(II) removal by Grewia Asiatica seed: a factorial design approach
Autorzy:
Siyal, A. N.
Memon, S. Q.
Khaskheli, M. I.
Powiązania:
https://bibliotekanauki.pl/articles/778329.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
optymalizacja
usuwanie Pb(II)
odpady nasion Grewiii
metodologia powierzchni odpowiedzi
badania równowagi
biosorpcja
optimization
Pb(II) removal
Grewia seed waste
response surface methodology
factorial design
equilibrium studiem
biosorption
Opis:
This study aims to explore the efficiency of an agro waste material for the remediation of Pb(II) contaminated water. A factorial design approach is adopted to optimize removal efficiency and to study the interaction between effective variables. A face-centered Draper-Lin composite design predicted 100% removal efficiency at optimum variables; pH 8, initial concentration of Pb(II) ion 12mg/L, sorbent dose 200mg and agitation time 110 min. Regration coefficient (R2 = 99.9%) of a plot of the predicted versus the observed values and p value (>0.05) confirms the applicability of the predicted model. Langmuir and Dubinin-Radushkevich (D-R) isotherm models were applicable to sorption data with the Langmuir sorption capacity of 21.61š0.78 mg/g. The energy of sorption was found to be 13.62š0.32 kJ/mol expected for ion-exchange or chemisorption nature of sorption process. Characterization of Grewia seed suggested a possible contribution of carboxyl and hydroxyl groups in the process of biosorption. The present study shows that Grewia seeds can be used effectively for the remediation of Pb(II) contaminated water.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 1; 71-77
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recycling of styrofoam waste: synthesis, characterization and application of novel phenyl thiosemicarbazone surface
Autorzy:
Siyal, A.N.
Memon, S.Q.
Khuhawar, M.Y.
Powiązania:
https://bibliotekanauki.pl/articles/778991.pdf
Data publikacji:
2012
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
recycling
styrofoam
functional polymer
Pb(II) ion removal
Phenyl thiosemicarbazone surface
Factorial Design Approach
Opis:
An attempt has been made to recycle Styrofoam waste to a novel functional polymer, Phenyl thiosemicarbazone surface (PTS). Polystyrene (PS) obtained from Styrofoam waste was acetylated and then condensed to PTS by reacting it with 4-Phenyl-3-thiosemicarbazide ligand and characterized by FT-IR spectroscopy and elemental analysis. Synthesized PTS was applied successfully for the treatment of lead contaminated water by batch extraction method. Sorption variables were optimized (pH 8, adsorbent dose 53mg, initial Pb(II) ion concentration 10mgl-1 and agitation time 90min) by factorial design approach. Lead uptake by PTS was found much sensitive to the pH of Pb(II) ion solution. The maximum removal (99.61%) of Pb(II) ions was achieved at optimum conditions. The Langmuir and D-R isotherm study suggested the monolayer, favorable (RL=0.0001-0.01) and chemisorption (E=20.41š0.12kJmol-1) nature of the adsorption process. The sorption capacity of PTS was found to be 45.25š0.69mgg-1. The FT-IR spectroscopy study showed the involvement of nitrogen and sulphur of thiosemicarbazone moiety of PTS for the uptake of Pb(II) ions by fi ve membered chelate formation.
Źródło:
Polish Journal of Chemical Technology; 2012, 14, 4; 11-18
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
LMPP Effects on Morphology, Crystallization, Thermal and Mechanical Properties of iPP/LMPP Blend Fibres
Wpływ polipropylenu o małej masie cząsteczkowej (LMPP) na morfologię, krystalizację, właściwości termiczne i mechaniczne włókien mieszanych iPP/LMPP.
Autorzy:
Hussain, M.
Zhu, F.
Yu, B.
Han, J.
Memon, H.
Yasin, S.
Powiązania:
https://bibliotekanauki.pl/articles/232887.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
polypropylene
iPP/LMPP blends
morphology
crystallinity
low molecular low modulus polypropylene
polipropylen
mieszanki iPP-LMPP
morfologia
krystaliczność
niski poziom cząsteczkowy
polipropylen o niskim module sprężystości
Opis:
The thermal properties and morphological characterisation of isotactic polypropylene (iPP) homopolymer and its blends with low molecular low modulus polypropylene (LMPP) were studied. Firstly blends were prepared with variant LMPP contents, and their properties were characterised using SEM, DSC, XRD, and DMA. Later the mechanical properties of iPP/LMPP blend fibres were investigated. SEM results showed that the iPP/LMPP blends produced smoother surfaces when the LMPP content was increased, as well as the miscibility. All the Tg values with different LMPP percentages were in-between pure iPP and LMPP. The XRD results indicated the LMPP percentage decreased along with the degree of crystallinity of the iPP/LMPP blends (5% to 15%), which increased and then decreased as compared to pure iPP. The elongation at break increased when the LMPP content increased, with the maximum elongation at break of the LMPP 25% blend reaching 12.95%, which showed great stretch-ability, whereas the elastic modulus of iPP/LMPP blends decreased.
W pracy badano właściwości termiczne i morfologię homopolimeru izotaktycznego polipropylenu (iPP) i jego mieszanek z polipropylenem o małej masie cząsteczkowej (LMPP). Zastosowano następujące proporcje mieszania iPP/LMPP (wt/wt): 95/5, 90/10, 85/15, 80/20 i 75/25, zdefiniowano je odpowiedni: 5%, 10%, 15 %, 20% i 25%. Właściwości włokien mieszanych iPP/LMPP porównano do właściwości czystego PP i LMPP. Włókna mieszane zbadano za pomocą SEM, DSC, XRD i DMA. Następnie zbadano mechaniczne właściwości włókien iPP/LMPP. Wyniki SEM wykazały, że wraz ze zwiększeniem zawartości LMPP powierzchnia włókien charakteryzowała się większą gładkością. Wszystkie wartości Tg włókien mieszanych były pośrednie pomiędzy czystym iPP i LMPP. Stwierdzono, że wydłużenie przy zerwaniu zwiększyło się wraz ze wzrostem zawartości LMPP, przy maksymalnym wydłużeniu przy zerwaniu 12,95%, dla włókien z zawartością 25% LMPP, co wskazywało na dużą rozciągliwość, podczas gdy moduł sprężystości wzdłużnej włókien iPP / LMPP zmniejszył się.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 2 (128); 26-31
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-variant Sorption Optimization for the Uptake Of Pb(II) Ions by Jamun Seed Waste
Autorzy:
Siyal, A.N.
Memon, S.Q.
Amanullah, M.
Pirzada, T.
Parveen, S.
Powiązania:
https://bibliotekanauki.pl/articles/779346.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
optimization
Pb(II) ions removal
Jamun seed waste
response surface methodology
Factorial Design Approach
Opis:
In the present study, jamun seed waste has been explored for the removal of Pb(II) ions from aqueous solution. The multi-variant sorption optimization was achieved by the factorial design approach. 99.91% of Pb(II) ions was removed from aqueous solution. The results predicted by the model were in good agreement with the experimental results (the values of R2 and R2 adj. were found to be 99.89% and 99.95%, respectively). Langmuir and D-R isotherm studies were carried out to fi nd adsorbent's capacities (183.9 š 0.31 mg/g and 184.5 š 0.16 mg/g respectively), sorption free energy 13.17 š 0.16 and RL values in the range of 0.05-0.77, suggested the favorable chemical and/or ion exchange nature of the sorption process. The FT-IR study was carried out for unloaded and Pb(II) ions loaded jamun seed, indicated, Pb(II) ions associated with nitrogen and oxygen of jamun seed containing moieties during the adsorption process. The proposed method was successfully validated and applied for the treatment of Pb(II) ions contaminating drinking water.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 1; 15-21
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Municipal Solid Waste Landfill Leachate Treatment by Phragmites australis, Typha latifolia and Scirpus validus through Constructed Wetlands
Autorzy:
Sial, Taufique Ahmed
Teewno, Abdul Majid
Memon, Sheeraz Ahmed
Mahar, Rasool Bux
Korai, M. Safar
Powiązania:
https://bibliotekanauki.pl/articles/24202906.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
MSW
municipal solid waste
landfill leachate
contamination
CWs
phytoremediation
macrophytes
sustainability
Opis:
A sustainable performance evaluation of pilot-scale was carried through horizontal sub-surface Constructed Wetlands system for treating the leachate from constructed Municipal Solid Waste Landfill at Institute of Environmental Engineering and Management, Mehran University of Engineering and Technology Jamshoro. The CWs were planted with Phragmites australis, Typha latifolia and Scirpus validus with sand and gravel. The leachate had been treated with two different cycles, first cycle was performed in the winter season whereas second cycle in summer, to differentiate the performance with seasonal variation. Chemical parameters of leachate pH, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids TSS, Ammonia-nitrogen (NH3-N), Nitrate-nitrogen (NO3-N), Total Phosphate PO43- (TP) and heavy metals, Lead (Pb) and Copper (Cu) were tested with intervals of certain weeks. The tests result showed that all parameters experienced a considerable reduction in their concentrations. Significant reduction efficiencies were recorded for parameters, BOD with 53–82%, COD with 32–46%, TSS with 59–75%, NH3-N with 90–92%, NO3-N with 85–87%, and TP with 48–64%, and heavy metals Pb and Cu with 28–48% respectively in four weeks of the first cycle by all three plants. Whereas, in the second cycle, the removal efficiencies of BOD 78–93%, COD 63–76%, TSS 52–83%, NH3-N 90–91% and NO3-N 91–92% and heavy metals Pb and Cu with 21–58% respectively in five weeks were observed by all three plants. Along with the experimentation, United Nations Sustainable Development Goals UN SDGs are also highlighted. This study helps achieving tremendous SDGs accompanying treatment of leachate.
Źródło:
Journal of Ecological Engineering; 2023, 24, 6; 303--314
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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