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Karim, Afizul Hakem,Park, Ka-Young,Lee, Tae Hee,Muhammed Ali, S.A.,Hossain, Shahzad,Absah, Hidayatul Qayyimah Hj Hairul,Park, Jun-Young,Azad, Abul Kalam Elsevier 2017 Journal of Alloys and Compounds Vol.724 No.-
<P><B>Abstract</B></P> <P>A new series of double perovskite oxides Sr<SUB>2</SUB>Fe<SUB>1-x</SUB>Ti<SUB>x</SUB>NbO<SUB>6-δ</SUB> (x = 0, 0.05 & 0.1) were prepared by traditional solid state reaction method and characterized by X-ray diffraction, scanning electron microscope (SEM), energy dispersive x-ray (EDX), ac impedance and dc four point using Van Der Pauw method. The samples were sintered at 1200 °C for 12 h in air to get single phase. Rietveld refinement shows that all composition crystallizes in tetragonal symmetry in the space group <I>I</I>4/<I>m.</I> The lattice parameter were related to the ideal single perovskite a<SUB>p</SUB> as a ≈ b ≈ √2a<SUB>p</SUB>, and c ≈ 2a<SUB>p</SUB>. Scanning electron microscope shows increase in porosity with increase of Ti content. Sr<SUB>2</SUB>Fe<SUB>1-x</SUB>Ti<SUB>x</SUB>NbO<SUB>6-δ</SUB>/YSZ shows a good interface with no lamination problem between the two materials. EDX shows that the element contents of the materials synthesized in this study close to the nominal stoichiometry. Chemical compatibility studies with YSZ electrolyte shows no reaction with the anode. A symmetrical cell with the configuration of Sr<SUB>2</SUB>Fe<SUB>1-x</SUB>Ti<SUB>x</SUB>NbO<SUB>6-δ</SUB>|YSZ|Sr<SUB>2</SUB>Fe<SUB>1-x</SUB>Ti<SUB>x</SUB>NbO<SUB>6-δ</SUB> (x = 0.05 & 0.1) shows the lowest polarization resistance of 49.80 Ω cm<SUP>2</SUP> and the highest ac conductivity of 3.57 × 10<SUP>−3</SUP> S cm<SUP>−1</SUP> in dry H<SUB>2</SUB>/Ar for x = 0.1. The activation energy was found to be 1.20 eV which is almost similar to Sr<SUB>2</SUB>FeNbO<SUB>6-δ</SUB> as reported in literature. The dc conductivity measurement was highest for SFTN0.1 at 750 °C in dry 5% H<SUB>2</SUB>/Ar with a value of 1.17 S cm<SUP>−1</SUP>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Titanium was substituted for Iron in the mixed conducting perovskite oxide SFN. </LI> <LI> A single double perovskite phase was obtained in air. </LI> <LI> Titanium substitution improves porosity, a.c conductivity and area specific resistance. </LI> <LI> The enhancement has been explained by a simple defect chemistry model. </LI> <LI> Electrochemical performance are interesting for applicability as an SOFC anode material. </LI> </UL> </P>
Fiber Optic Network Infrastructure As Next Generation Power System Communications
Amanullah Maung Than Oo,A. Kalam,A. Zayegh 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
The great needs of the information exchange in the power system are pushing information technology (IT) to play an increasingly important role. A methodology for efficient information consolation, exchange and sharing is required. This need will become increasingly more critical as the volume of information holding increases. This paper reviews current power system communication media and discusses fiber optic network infrastructure for the next generation power system communication. It also systematically analyzes the new optical networking architectures and protocols enabled by recent advances in network and IT technologies.
DRAGOMIR, S.S.,KALAM, A. 한국산업정보응용수학회 2002 한국산업정보응용수학회 Vol.6 No.1
An approximation of the Fourier Sine Transform via Gru¨ss, Chebychev and Lupas¸ integral inequalities and application for an electrical curcuit containing an inductance L, a condenser of capacity C and a source of electromotive force EoP (t), where P ( t ) is an L_(2)-integrable function, are given.
Soft Start and solid state speed control of a D.C Shunt Drive
Mukul. M Mahajan,Amanullah Maung Than Oo,A.Kalam 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
DC drives even though considered obsolete in comparison to the AC induction motor drives, still retain several advantages in the control mechanism and operating characteristics. Despite the claims and counter-claims of suppliers over recent years there is no single drive technology that is ideal for all applications. The paper presents a full proof feedback loop speed control system and a soft start feature for a Shunt excited DC drive. Decisively such a control system can be adopted in tractive applications such as hybrid electric and Hydrogen fuel cell vehicles.