Preparation of asymmetric polysulfone/polyimide blended membranes for CO_2 separation

Sikander Rafiq,Zakaria Man,Saikat Maitra,Abdulhalim Maulud,Farooq Ahmad,Nawshad Muhammad 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.10

Asymmetric Flat sheet polysulfone-polyimide (PSF-PI) blended polymeric membranes (with PI content from 5-20%) have been fabricated following phase inversion technique. The membranes have been thoroughly characterized by the measurement of porosity, mechanical properties and also by SEM, FTIR and DSC analyses. With the increase in the PI content, the mechanical properties of the membranes, like Young’s modulus, tensile strength and elongation at break, increased. SEM investigations revealed that the surfaces of fabricated blended membranes possessed adequate homogeneity and their cross-sections showed non-porous top and diminutive porous substructure. From DSC analyses it has been observed that different compositions of the blended membranes exhibited single glass transition temperatures, implying proper compatibility of the polymers. The permeance of CO_2 and CH_4 through the membrane increased with the increase in PI content and it gradually decreased with the increase in the feed pressure in the range of 2-10 bar. Under the present investigation, the membrane with 20% PI content exhibited the maximum selectivity for the separation of CO_2 /CH-4 gas mixes.

ON DIFFERENT NOTIONS OF TRANSITIVITY FOR QTAG-MODULES

Sikander, Fahad,Hasan, Ayazul,Mehdi, Alveera The Honam Mathematical Society 2016 호남수학학술지 Vol.38 No.2

A module M over an associative ring R with unity is a QTAG-module if every finitely generated submodule of any homomorphic image of M is a direct sum of uniserial modules. Recently, the authors introduced the classes of QTAG-modules namely as socle-regular and strongly socle-regular QTAG-modules which properly contain the classes of transitive and fully transitive QTAG-modules respectively. Here we define strongly and quasi transitivities and study the inter relations between various type of transitivities.

RETRACTION

Sikander, Fahad The Honam Mathematical Society 2019 호남수학학술지 Vol.41 No.3

Investment and Management Strategies of Foreign Companies in Japan

Sikander Khan 慶北大學校 經濟經營硏究所 1993 經商論集 Vol.21 No.2

Exploring the electronic structure and optical properties of new inorganic luminescent materials Ba(Si,Al)5(O,N)8 compounds for lightemitting diodes devices

Sikander Azam,Saleem Ayaz Khan,Jan Minar,Souraya Goumri-Said 한국물리학회 2015 Current Applied Physics Vol.15 No.10

Due to growing demand on discovering new materials for light-emitting diodes devices, many efforts were made to discover and characterize new inorganic materials such as phosphors. Using the full potential method within density functional theory the electronic and optical properties of BaAl2Si3O4N4 and BaAlSi4O3N5 semiconductors have been investigated. The electronic structure and the optical properties of these phosphors were calculated through a reliable approach of modified Beck-Johnson (mBJ) approach. We found that BaAl2Si3O4N4 and BaAlSi4O3N5 have wide direct band gaps positioned at G about 5.846 and 4.96 eV respectively. The optical properties, namely the dielectric function, optical reflectivity, refractive index and electron energy loss, are reported for radiation up to 15 eV. Our study suggests that BaAl2Si3O4N4 and BaAlSi4O3N5 could be promising materials for applications in the LEDs devices and optoelectronics areas of research.

On different notions of transitivity for $\mathversion{bold}{QTAG}$-Modules

Fahad Sikander,Alveera Mehdi,Ayazul Hasan 호남수학회 2016 호남수학학술지 Vol.38 No.2

A module $M$ over an associative ring $R$ with unity is a $QTAG$-module if every finitely generated submodule of any homomorphic image of $M$ is a direct sum of uniserial modules. Recently, the authors introduced the classes of $QTAG$-modules namely as socle-regular and strongly socle-regular $QTAG$-modules which properly contain the classes of transitive and fully transitive $QTAG$-modules respectively. Here we define strongly and quasi transitivities and study the inter relations between various type of transitivities.

A Survey of Cluster-based Routing Schemes for Wireless Sensor Networks

Gulbadan Sikander,Mohammad Haseeb Zafar,Ahmad Raza,Muhammad Inayatullah Babar,Sahibzada Ali Mahmud,Gul Muhammad Khan 한국산학기술학회 2013 SmartCR Vol.3 No.4

In recent times, wireless sensor networks (WSNs) have become progressively more attractive and have found their way into a wide variety of applications and systems because of their low cost, self-organizing behavior, and sensing ability in harsh environments. A WSN is a collection of nodes organized into a network. Routing is a vital technology in WSNs and can be roughly divided into two categories: flat routing and hierarchical routing. In a flat routing topology, all nodes have identical functionality and carry out the same task in the network. Nodes in a hierarchical topology do different tasks in WSNs and are usually arranged into clusters. In this paper, a survey on cluster-based routing schemes for WSNs has been done and comparisons made on the basis of performance factors such as latency, scalability, and energy awareness. Strengths and limitations of each scheme are presented, and open issues that must be addressed in the design of cluster-based routing algorithms are discussed.

ON DIFFERENT NOTIONS OF TRANSITIVITY FOR QTAG-MODULES

( Fahad Sikander ),( Ayazul Hasan ),( Alveera Mehdi ) 호남수학회 2016 호남수학학술지 Vol.38 No.2

A module M over an associative ring R with unity is a QTAG-module if every finitely generated submodule of any ho- momorphic image of M is a direct sum of uniserial modules. Re- cently, the authors introduced the classes of QTAG-modules namely as socle-regular and strongly socle-regular QTAG-modules which properly contain the classes of transitive and fully transitive QTAG- modules respectively. Here we define strongly and quasi transitivi- ties and study the inter relations between various type of transitiv- ities.

An Object-Oriented Design Methodology Based on Object Service Tier (OST) Middleware in HLA Framework for the Distributed Simulation System Environment

Usman Sikander 보안공학연구지원센터 2014 International Journal of Database Theory and Appli Vol.7 No.5

Promising the developers with the facility of distributed collaborative development for complex simulation applications, HLA (High Level Architecture) provides a baseline supporting the reuse of capabilities available in different simulations with a significant reduction in cost and time. Along with improved execution process and reusability, the induction of object oriented model in the implementation design of HLA also enable to take the advantage of latest object oriented features making design, implementation and maintainability easier and at each level of federate development and execution. The important areas to be addressed for design reconsideration consists of data exchange model and HLA communication layer. The data exchange model comprises of federates in federation and between runtime infrastructure and federation. The Federate Object Model (FOM) architecture is not completely object oriented, the induction of Object Service Tier (OST) middleware may offer a degree of FOM agility which is the ability of an application to adjust according to different FOMs (behaviors for Federates). Whereas, in HLA communication layer, customary HLA systems are based upon bidirectional call/callback interactions between federate. Several enhancements and changes anticipated in object oriented communication layer (OOP-COMM) introduced in Object Service Tier (OST) as compared to native procedures, such as communication mechanisms, data encoding, session handling, distributed environment and performance analysis. The motivation behind the use of core object oriented modeling features and proposed Object Service Tier (OST) middleware is the reuse of legacy systems, features which may further enhance the integration of distributed simulation systems and extension types. So, this paper provides a multidimensional analysis of important design aspects of Object Service Tier (OST) middleware in HLA framework and devises some design constructs of Object Service Tier (OST) using object oriented model. This paper is intended to propose object-oriented model providing generalization through the Object Service Tier (OST) middleware in HLA framework for the distributed simulation system environment.

고주파 공진현상을 이용한 CW CO2 레이저의 출력리플 최소화

사쿠라(Sakura Sikander),권민재(Min-Jae Kwon),김희제(Hee-Je Kim),이동길(Dong-Gil Lee),허국성(Guo-Cheng Xu) 대한전기학회 2013 전기학회논문지 Vol.62 No.6

In a conventional DC power supply used for CO2 laser, the circuit elements such as a rectifier bridge, a current-limiting resistor, a high voltage switch, energy storage capacitors ans a high-voltage isolation transformer using high turn ratio are necessary. Consequently, those supplies are expensive and require a large space. Thus, laser resonator and power supply should be optimally designed. In this paper, we propose a new power supply using high frequency resonance phenomena for CW(Continuous wave) CO2 laser (maximum output of 23W with discharge length of 450mm). It consists of a transformer including leakage inductance, magnetizing inductance and half-bridge converter, a three-stage Cockcroft-Walton and PFC(Power factor correction) circuit. The output ripple voltage can be controlled the minimum of 0.24% under the high frequency switching of 231kHz. Furthermore, the output efficiency was improved to 16.4% and the laser output stability of about 5.6% was obtained in this laser system.