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Oral Tissue Engineering Progress and Challenges
Muhammad Sohail Zafar,Zohaib Khurshid,Khalid Almas 한국조직공학과 재생의학회 2015 조직공학과 재생의학 Vol.12 No.6
Tissue engineering is a multidisciplinary science. The progress of tissue engineering for dental tissues is promising and various dental soft and hard tissues have been regenerated successfully in vitro using stem cells. Prior to their applications practically, there are a number of challenges and unanswered questions that need to be resolved for further progress. It is expected that in next two to three decades, the field of dentistry will be changed significantly by the availability of innovative tissue engineered products in dental office. The objective of this review paper is to highlight the progress of tissue engineering for various dental hard and soft tissues such as enamel, dentin, alveolar bone, periodontium, oral mucosa, and salivary glands. In addition, the challenges in the progress of tissue engineering and future expectations have been discussed.
A Clustering Based Study of Classification Algorithms
Muhammad Husnain Zafar,Muhammad Ilyas 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.1
A grouping of data objects such that the objects within a group are similar (or related) to one another and different from (or unrelated to) the objects in other groups. Many of clustering algorithm is available to analyze data. This paper intends to study and compare different clustering algorithms. These algorithms include K-Means, Farthest First, DBSCAN, CURE, Chameleon algorithm. All these algorithms are compared on the basis of their pros and cons, similarity measure, their working, functionality and time complexity.
Natural convection effects on heat and mass transfer of slip flow of time-dependent Prandtl fluid
Muhammad Hamid,Tamour Zubair,Muhammad Usman,Zafar Hayat Khan,Wei Wang 한국CDE학회 2019 Journal of computational design and engineering Vol.6 No.4
We proposed a mathematical model for an incompressible, viscous, natural convection, and stagnation point slip flow of MHD Prandtl fluid over an infinite plate. The governing flow equations are constructed using the Prandtl rheological model. In account of physical relevance, we investigated the Soret and Dufour effects on the flow field. The complex natured flow equations are transformed to a set of PDEs using a suitable similarity variables. The non-dimensionalized ruling problem together with physical boundary conditions is numerically analyzed via Crank-Nicolson scheme. The velocity, temperature and concentration of the diffusing species distributions are enhanced for higher values of unsteadiness parameter. It is noted that velocity is slightly decreasing for higher values of Reynolds number while smaller values of Re providing more dominant effects on the velocity, temperature and concentration of the diffusing species profiles and enhanced heat and mass transfer rates is noticed. The physical behav-ior of reduced Nusselt and Sherwood numbers, friction factor, for distinct values of emerging parameters is examined and representative set of graphs are presented.
Highly stable inverted organic photovoltaic cells with a V2O5 hole transport layer
Muhammad Zafar,윤주영,김도형 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
The stability of the hole transport layer (HTL) in inverted organic photovoltaic cells is of great interest because the conventional HTL material, PEDOT:PSS, shows limited stability. In this work, solution processed vanadium pentoxide (V2O5) was adopted as the HTL, and the effect of annealing on the properties of the HTL was investigated. The inverted organic photovoltaic cell fabricated with V2O5 and annealed for 5min at 165 oC showed the highest power conversion efficiency (PCE) of 3.92%, which is an enhancement of 16% relative to the cell with PEDOT: PSS (PCE=3.36%). The cell with V2O5 was also found to be more stable than the PEDOT: PSS cell, in which a 51% decrease in PCE was observed after 96 h. In contrast, over the same interval, the V2O5 device maintained a PCE 85% of the original value.
Multiple input describing function analysis of non-classical aileron buzz
Zafar, Muhammad I.,Fusi, Francesca,Quaranta, Giuseppe Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.2
This paper focuses on the computational study of nonlinear effects of unsteady aerodynamics for non-classical aileron buzz. It aims at a comprehensive investigation of the aileron buzz phenomenon under varying flow parameters using the describing function technique with multiple inputs. The limit cycle oscillatory behavior of an asymmetrical airfoil is studied initially using a CFD-based numerical model and direct time marching. Sharp increases in limit cycle amplitude for varying Mach numbers and angles of attack are investigated. An aerodynamic describing function is developed in order to estimate the variation of limit cycle amplitude and frequency with Mach number and angle of attack directly, without time marching. The describing function results are compared to the amplitudes and frequencies predicted by the CFD calculations for validation purposes. Furthermore, a limited sensitivity analysis is presented to demonstrate the potential of the approach for aeroelastic design.
Muhammad Zafar,윤주영,김도형 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2
Atomic layer deposition (ALD) was used to synthesize titanium oxide (TiO2) film as an electron transport layer (ETL) in inverted organic photovoltaic cells (IOPVs). By adjusting the ALD precursor ratio and deposition temperature, the thickness of the TiO2 film was 5 nm, and its effect on the photovoltaic performances was evaluated. We also investigated the effect of nitrogen doping of TiO2 on the power conversion efficiency (PCE) of the cells. An IOPV cell fabricated with a 0.6%-nitrogen-doped TiO2 (N-TiO2 A) ETL exhibited a PCE of 2.27%, which is a 6% increase compared with an equivalent cell containing an undoped TiO2 ETL. Furthermore, the XPS results confirmed the doping of nitrogen into the samples. The doping improved the electrical properties of the TiO2 films evidenced by the Hall measurements in terms of conductivity, hall electron mobility and carrier density.
Muhammad Shahid,Abdul Khaliq,Naveed Ahmad,Khawar Jabran,Mohsin Zafar,Muhammad Rafiq,Mubshar Hussain 한국국제농업개발학회 2012 韓國國際農業開發學會誌 Vol.24 No.1
This study was conducted to determine the influence of irrigation levels on spring planted sunflower (Helianthus annuus L.) sown with different planting methods. Sunflower was sown either on 60 cm apart single rows on flat seed-bed or on ridges. Three irrigation treatments were I0 (irrigation at early vegetative stage, at bud visible stage, at anthesis and at achene development stage), I1 (irrigation at early vegetative stage, at bud visible stage and at achene development stage) and I2 (irrigation at early vegetative stage, at bud visible stage and at anthesis stage). In I1, irrigation was missing at anthesis and in I2 irrigation was missing at achene development stage. Sunflower yield and yield components showed positive response to ridge sown sunflower with normal four irrigations. Maximum achene yield 3.33 t ha-1 was recorded in ridge sown sunflower with four irrigations. Oil content percentage was highest in case of I0 (42.25%) while the effect of planting methods on oil content was insignificant.