Determination of Poisson’s ratio of a beam by ESPI

Akhter Naseem(아흐터나심),H.C. Chung(정현철),H.S. Chang(장호섭),D.S. Kim(김동수),K.S.Kim(김경석) 한국정밀공학회 2009 한국정밀공학회 학술발표대회 논문집 Vol.2009 No.10월

Structural and Morphological Properties of Zn1−xZrxO with Room-Temperature Ferromagnetism and Fabricated by Using the Co-Precipitation Technique

M. Hassan,R. Irfan,S. Riaz,S. Naseem,S. S. Hussain,G. Murtaza 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.70 No.5

In this study, ZnO was doped with various concentrations of zirconium (xZr = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn1−xZrxO was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents (xZr < 3%); however, impurity peaks belonging to ZrO2 appeared at high impurity contents (xZr 3%). The calculated ZnO lattice constants ‘a’ and ‘c’ were found to be 3.256 °A and 5.203 °A, respectively, which are in close match to the values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 °A. The residual strains and the secondary phases of ZrO2 were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the otherhand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

전단 간섭법을 이용한 원통형 압력용기의 면외변형 정량계측

정덕운(D. W. Jung),장호섭(H. S. Chang),아흐터 나심(Naseem Akhter),박찬식(C. S. Park),홍성성(S. S. Hong),김경석(K. S. Kim) 한국정밀공학회 2010 한국정밀공학회 학술발표대회 논문집 Vol.2010 No.5월

Magnetohydrodynamic peristalsis of variable viscosity Jeffrey liquid with heat and mass transfer

S. Farooq,M. Awais,Moniza Naseem,T. Hayat,B. Ahmad 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.7

The mathematical aspects of Dufour and Soret phenomena on the peristalsis of magnetohydrodynamic(MHD) Jeffrey liquid in a symmetric channel are presented. Fluid viscosity is taken variably. Lubricationapproach has been followed. Results for the velocity, temperature, and concentration are constructed andexplored for the emerging parameters entering into the present problem. The plotted quantities lead tocomparative study between the constant and variable viscosities fluids. Graphical results indicate that fornon-Newtonian materials, pressure gradient is maximum, whereas pressure gradient is slowed down forvariable viscosity. Also both velocity and temperature in the case of variable viscosity are at maximumwhen compared with results for constant viscosity.

Metathesis of 2-pentene over Mo and W supported mesoporous molecular sieves MCM-41 and SBA-15

Mohamed Ali Ibrahim,Muhammad Naseem Akhtar,Ji rí Cejka,Erica Montanari,Hynek Balcar,Martin Kubu,Sulaiman S. Al-Khattaf 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.53 No.-

Molybdenum and tungsten oxides were supported on silica, MCM-22, MCM-41 and SBA-15. XRD and N2 adsorption–desorption revealed that architecture and textural character of supports were preserved. The catalysts were investigated in transformation of 2-pentene at different reaction temperatures. MoO3/ MCM-22 exhibited highest conversions with isomerization and cracking as major reactions. MoO2(acac)2, MoO3 and WO3 supported on MCM-41 and SBA-15 showed metathesis reaction of 2-C5 = producing propylene, C4 = and C6+ =as major products. Catalysts based on MCM-41 exhibited higher activity and stability than SBA-15. Addition of ethylene to 2-C5 = increased selectivity to propylene due to metathesis of ethylene with 2-pentene.

Hypergolicity and ignition delay study of pure and energized ethanol gel fuel with hydrogen peroxide

Jyoti, B.V.S.,Naseem, Muhammad Shoaib,Baek, Seung Wook Elsevier 2017 Combustion and flame Vol.176 No.-

<P><B>Abstract</B></P> <P>An experimental study of hypergolicity and ignition delay of pure and energized gelled ethanol with hydrogen peroxide was carried out. Experimental drop test results were obtained and discussed by using Photron high speed camera imaging. This study represented a sufficient repeatability of ignition delay for hypergolic gel bipropellant development. Gelled ethanol fuel (pure and energized with nano-Al/B/C particle substitution) mixture with metal catalysts were formulated to examine its hypergolicity with ignition delays on the order of 1–30ms in most of cases, which are comparable with the existing liquid hypergolic bipropellant systems. The minimum ignition delay time was recorded for boron case at 1.33ms. And the calculated activation energy for the gelled ethanol fuel with pure and energetic particle substitution system resided within the range of 7–13kJ/mole along with shear thinning behavior. Temperature profile also indicated an exothermic nature of the propellant system with 1000 to 1600K recorded. Parameters such as apparent viscosity of the fuel, drop height and drop volume also played an important role for the hypergolicity of the system in a drop experimentation. It was also observed that the formation of a cage encapsulating the high temperature gases in a network formed by the gelling agent could result in a longer ignition delay.</P>

Hypergolicity and ignition delay study of gelled ethanolamine fuel

Jyoti, Botchu Vara Siva,Naseem, Muhammad S.,Baek, Seung Wook,Lee, Hyung Ju,Cho, Sung June Elsevier Science Inc 2017 Combustion and Flame Vol.183 No.-

<P><B>Abstract</B></P> <P>An experimental investigation on achieving hypergolicity with a critical catalyst concentration and measuring ignition delay of non-metalized and metalized gelled ethanolamine was performed with hydrogen peroxide as an oxidizer. The experimental results of using high speed camera were obtained by adopting the drop tests in this work. This study represented a sufficient repeatability of ignition delay for hypergolic bipropellant system. Gelled ethanolamine fuel (non-metalized and metalized with nano-sized metal particle substitution) with metal catalysts presented the results in hypergolicity with ignition delays of the order of 1–5ms in most of the cases, which was comparable to the existing liquid hypergolic bipropellant systems. However, the minimum ignition delay time was recorded for pure-CCAT case. Moreover, the calculated activation energy (E<SUB>vis</SUB>) for the gelled ethanolamine fuel for non-metalized and metalized systems was within the range of 0.03–0.06kJ/mole along with shear thinning behavior. Parameters such as apparent viscosity of the fuels, blended energetic particle, catalyst type along with its critical concentration using the drop impact plays an important role in studying the hypergolicity and ignition delay time of the gel bipropellant.</P>

Ethernet‑Based Fault Diagnosis and Control in Smart Grid: A Stochastic Analysis via Markovian Model Checking

Riaz Uddin,Ali S. Alghamdi,Muhammad Hammad Uddin,Ahmed Bilal Awan,Syed Atif Naseem 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

The fault diagnosis and control through fault detection, isolation and supply restoration (FDIR) technique is the part of a commonly used distribution management system application in smart grid. When the fault occurs, it becomes essential to detect and isolate the faulty section of the distribution network at once and then restore back to its running condition through tie switches. The communication between IEDs is done through diferent communication mediums such as Ethernet, wireless, power line communication etc. Therefore, formal analysis of the FDIR mechanism is required with communication network (ideally Ethernet), which helps us to predict the behavior of FDIR response upon the occurrence of fault in terms of various important probabilities, reliability study and efciency (showing the system will work properly). In this regard, for the above said analyses, this article discusses (a) the development of the Markovian model of FDIR for distribution network of smart grid considering Tianjin Electric Power Network as case study with intelligent electronic devices (IEDs) using ideal communication medium (Ethernet); (b) utilized probabilistic model checker (PRISM tool) to predict the probabilities; (c) perform the reliability analyses and (d) study the efciency of FDIR behavior for future grid using logical properties. The detailed analysis and prediction (done for the fault occurrence scenario) mainly focus in determining the (1) the probability of switching failures of FDIR in smart grid; (2) the probability of isolating the defective switch from the system within limited time and (3) the probability of restoring the system automatically within the minimum possible interval.

Spin polarization and magneto-dielectric coupling in Al-modified thin iron oxide films -microwave mediated sol-gel approach

Sidra Khalid,Saira Riaz,Samia Naeem,Aseya Akbar,S. Sajjad Hussain,YB Xu,Shahzad Naseem 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.103 No.-

Production of single-phase materials with multifunctional properties is still a challenge faced by materialscientists. In addition, obtaining high spin polarization efficiency in the materials that exhibit multifunctionalproperties is a big issue. A novel approach is suggested in this work for obtaining multifunctionalityand spin polarization in the same material. This approach has combined the effect of microwave radiationsand aluminum (Al) doping in iron oxide thin films during synthesis. Combined effect of microwaveradiations and Al doping results in controlling / tuning the structural transitions in iron oxide thin films. Pristine and 2–10 wt% Al doped iron oxide thin films are prepared and studied in detail. Raman analysisshows that 2 and 4 wt% Al concentration results in c-Fe2O3 + Fe3O4 phase with 71.3% and 64.5% of c-Fe2O3content, respectively. XRD and Raman analyses confirm the transition from c-Fe2O3 to Fe3O4 thin films atAl concentrations of 6–10 wt%. Structural transformation shows that microwave radiations catalyzes thatAl3+ions to occupy the vacancies on B sites of iron oxide thus, lead to the formation of Fe3O4. Observationof Verwey transition ~ 126 K also supports the transition in phases of iron oxide with increase in saturationmagnetization from 251.3emu/cm3 (pristine films) to 405.6emu/cm3 (8 wt% Al concentration). Highdielectric constant of ~ 135.5 (log f = 5.0) is observed for 8 wt% Al concentration. Conductivity anddetailed impedance & modulus analyses depict Mott’s hopping phenomenon along with presence of differentrelaxation times. Coupling between magnetic and dielectric properties is observed at room temperature. Magnetoresistance curves indicate spin polarization efficiency of ~24%.