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RISS 인기검색어
- 검색키워드
- 저자 : Muhammad Shahzad (검색결과 85 건)
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Optical thermometry probe via fiber containing β-NaLuF4:Yb3+/Er3+/ Tm3+
Muhammad Khuram Shahzad,Yundong Zhang,Muhammad Usman Khan,Harse Sattar,Muhammad Ikram 한국물리학회 2019 Current Applied Physics Vol.19 No.6
In this article, β-NaLuF4:Yb3+/Tm3+/Er3+ were synthesized by thermal decomposition technique. Yb3+/Tm3+/ Er3+ has been firstly manifested to fabricate the microfibers after co-doping with polymer solution. The guiding performance of a microfiber was observed under 980 nm excitation source to prove that it could be used as an active and passive waveguides. The characteristics of optical thermal sensing of Tm3+ and Er3+ ions in a single microfiber were demonstrated. The FIR method was utilized to evaluate the sensitivity of a single microfiber and maximum sensitivity of activator ions in a microfiber was achieved as 0.00124 and 0.00311 K-1 with temperature ranging from 303 to 363 K, respectively. Our results suggest that a single microfiber has good sensing stability and has potential applications in the field of thermometry.
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Modeling and preparation of practical optical filters
Muhammad H. Asghar,Muhammad Shoaib,Frank Placido,Shahzad Naseem 한국물리학회 2009 Current Applied Physics Vol.9 No.5
Multilayer bandpass and bandstop filters have been produced using electron beam evaporation. Initially bandstop filter is modeled with non absorbing zinc sulphide (ZnS) and zinc selenide (ZnSe). When the absorption data was incorporated for the said materials significant absorption was observed at shorter wavelengths of the spectral band restricting the practical usage of the filter. ZnS and ZnSe were then replaced by dispersive silicon dioxide (SiO2), tantalum penta oxide (Ta2O5) and titanium dioxide (TiO2) along with their absorption and the filters are optimized to get desired bandpass and bandstop data. Bandpass and bandstop filters with desired performance were experimentally characterized with two combinations SiO2/Ta2O5/glass and SiO2/TiO2/glass. The measured average transmission for both combination (bandpass) in the pass band was about 92% with T < 1% in the stop band. Slightly narrow bandwidth was observed for SiO2/TiO2/glass as compared to SiO2/Ta2O5/glass which is attributed to layers densification. Similarly Tavg ≽ 80% was achieved for two combinations of bandstop filters with T < 0.1% in the stop band. The structure and surface morphology of the prepared filters were characterized by X-ray diffraction and scanning electron microscopy. XRD analysis reveals amorphous structure. SEM analysis also reveals that the layers are compact and have good surface quality. Multilayer bandpass and bandstop filters have been produced using electron beam evaporation. Initially bandstop filter is modeled with non absorbing zinc sulphide (ZnS) and zinc selenide (ZnSe). When the absorption data was incorporated for the said materials significant absorption was observed at shorter wavelengths of the spectral band restricting the practical usage of the filter. ZnS and ZnSe were then replaced by dispersive silicon dioxide (SiO2), tantalum penta oxide (Ta2O5) and titanium dioxide (TiO2) along with their absorption and the filters are optimized to get desired bandpass and bandstop data. Bandpass and bandstop filters with desired performance were experimentally characterized with two combinations SiO2/Ta2O5/glass and SiO2/TiO2/glass. The measured average transmission for both combination (bandpass) in the pass band was about 92% with T < 1% in the stop band. Slightly narrow bandwidth was observed for SiO2/TiO2/glass as compared to SiO2/Ta2O5/glass which is attributed to layers densification. Similarly Tavg ≽ 80% was achieved for two combinations of bandstop filters with T < 0.1% in the stop band. The structure and surface morphology of the prepared filters were characterized by X-ray diffraction and scanning electron microscopy. XRD analysis reveals amorphous structure. SEM analysis also reveals that the layers are compact and have good surface quality.
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Effects of angle on the transport velocity in an inclined fluidized-bed
Muhammad Shahzad Khurram,최정후,Yoo Sube Won,A Reum Jeong,박영철,류호정,이창근 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12
The transport velocity (utri) in an inclined fluidized-bed was investigated by varying the bed angle relative to the horizontal plane (0o-90o), the particle diameter (0.021-0.925mm), and density (1,272-4,503 kg/m3). This study employed the emptying time method to determine the transport velocity. The transport velocity for the vertical fluidized- bed (utr90) was revealed to increase appreciably with the aspect ratio of the fluidized-bed. The transport velocity decreased as the bed angle increased. The ratio of the transport velocity to that for the vertical bed (utri/utr90) decreased with an increase in either the bed angle or the ratio of the particle diameter (dp) to the critical particle diameter (dp *), i.e., the maximum particle diameter at which the sum of the interparticle adhesion forces had a dominant influence on particle entrainment. Correlations for the transport velocity according to the bed angle relative to the horizontal plane were proposed successfully, based on the experimental data.
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Muhammad Hasnain,Imran Ghani,Muhammad Fermi Pasha,Ishrat Hayat Malik,Shahzad Malik 한국인터넷방송통신학회 2019 International Journal of Internet, Broadcasting an Vol.11 No.2
Research classification of software modules was done to validate the approaches proposed for addressing limitations in existing classification approaches. The objective of this study was to replicate the experiments of a recently published research study and re-evaluate its results. The reason to repeat the experiment(s) and re-evaluate the results was to verify the approach to identify the faulty and non-faulty modules applied in the original study for the prioritization of test cases. As a methodology, weconducted this study to re-evaluate the results of the study. The results showed that binary logistic regression analysis remains helpful for researchers for predictions, as it provides an overall prediction of accuracy in percentage. Our study shows a prediction accuracy of 92.9% for the PureMVC Java open source program, while the original study showed an 82% prediction accuracy for the same Java program classes. It is believed by the authors that future research can refine the criteria used to classify classes of web systemswritten in various programming languages based on the results of this study.
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An improved indirect evaporative cooler experimental investigation
Shahzad, Muhammad Wakil,Burhan, Muhammad,Ybyraiymkul, Doskhan,Oh, Seung Jin,Ng, Kim Choon ELSEVIER 2019 Applied Energy Vol. No.
<P><B>Abstract</B></P> <P>Air conditioning has enhanced the work efficiency and improved life style by maintaining comfortable environment. The growing demand of air conditioning has negative impact on energy and environment. In 2015, air conditioning consumed 6% of total global electricity produced and it is expected to increase to 20% by 2050. The leveling-off conventional chiller’s efficiency at 0.85 ± 0.03 kW/Rton due to pairing of dehumidification and cooling processes in one machine is not only the major reason of high energy consumption but also the key limitation in efficiency improvement. The de-coupling of dehumidification and cooling processes can be one of the solution to achieve the quantum jump in the performance, 0.6 ± 0.03 kW/Rton, by improving individual processes. We proposed an improved indirect evaporative cooler system for sensible cooling that can be combined with dehumidification processes to achieve sustainable cooling goals. The experimentation on 800 mm long and 280 mm wide generic cell showed that it can produce temperature differential up to 10 °C with small area of heat transfer. It was showed that the proposed vertical heat exchanger configuration with multi point injection of working air is the best configuration of the indirect evaporative cooler, achieving coefficient of performance level of 78 for cooling alone. We expect that overall coefficient of performance level of 7–8 is achievable by incorporating efficient dehumidification processes. We also presented detailed design parameters that can be used as a reference for commercial system design.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Decoupling of latent and sensible load in cooling is the key for sustainability. </LI> <LI> The indirect evaporative cooler integrated with dehumidification is one of the solution. </LI> <LI> Improved IEC with three major modification can achieve COP up to 78 for cooling only. </LI> <LI> The dehumidification system COP around 4–5 can help to achieve overall COP of 7–8. </LI> <LI> The proposed multi injection vertical heat exchanger design has the best performance. </LI> </UL> </P>
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An Energy Rating Methodology for Long Term Performance Evaluation of Renewable Energy Systems
Muhammad Wakil Shahzad,Kyaw Thu,YounCheol Park,Seung Jin Oh,Kim Choon Ng 한국에너지기후변화학회 2013 에너지기후변화학회지 Vol.8 No.2
This paper describes a simple methodology for determining the long term performance of renewable energy systems (solar, photovoltaics, wind turbines, etc) that is important for project evaluation. Overall efficiency of solar collector hot water plants, photovoltaics and wind turbines are examined by using a ratio of output of useful effects to energy input. Long-term efficiency of class A solar collectors is typically higher ≥ 50%in thermal energy whilst the silicon-based photovoltaics has only <10% efficiency in electricity: In these mentioned cases, the useful output differ in form, obscuring the comparison of one renewable system to the other.The thermal or electricity rating proposed here enable one to make a performance comparison across a host of renewable energy systems. Based on the long term performance rating, itwill assist engineers and managers topredict accurately the payback periods of renewable energy plants as well as the annual carbon emissions.
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Parametric Investigation of Metals (Au, Ag, Pt and Cu) Using Analytical Hierarchy Process
Muhammad Asif,Faiz Rasool,Zubair Butt,Muhammad Shahzad,Nouman Ahmad,Abdul Rehman Chishti 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2
Metals especially gold, silver, platinum and copper are getting more attention for application in electronics fi eld due to their versatile properties. In this paper, we selected the materials after comparison on the basis of their signifi cant properties. Those properties are conductivity, physical properties, reactivity, cost and demand and supply. We investigate the conductivity of metals at various temperature values, their historically monthly prices along with their worldwide demand and supply. First, we compare their conductivity and resistivity for various values of temperature as well as by adding impurity into them. Secondly, we examined their responses when they are in contact with the atmosphere, their historically monthly prices, availability in the earth crust, and a brief discussion on the structure of these metals. These metals are widely used in electronics and jewelry because of their good conductivity, chemical stability and long lasting. We implemented the analytical hierarchy process for the parametric investigation of these metals which is a general theory of measurement. It has been used to derive ratio scales from both continuous and discrete paired comparison. This comparison is taken from actual measurement which refl ects the relative strength of preferences. The metals are also useful to design electrical stimulator with low-frequency current to regulate the blood of the human body. By using the stimulator at acupuncture points to pass through small electrical signal is useful to control blood fl ow in the human body as well as provides relief in pain.
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