**Recent Developments in Potential Theories Applied to Diffraction of Water Waves**, Gauhati University, May 22, 1995.**Prospects of Higher Studies in Mathematics**, Morigaon College, November 18, 1998.**Differential Equations**, ADP College, Nagaon, Assam, November 1999.**Differential Equations and Vectors (Two Lectures)**, Bajali College, Pathsala, Assam, December 1999.**Differential Equations and Vectors (Two Lectures) ,**Goalpara College, Goalpara, Assam, March 2000.**Basic Mathematics**, Dimoria College, Khetri, Assam, February 16, 2004.**Special Functions and Integral Equations (Three Lectures)**, QIP-STC, IIT Guwahati, March 9-16, 2004.**Present Scenario of Mathematics Education and Research in Northeast India**, Mathematics Day, IIT Guwahati, August 21, 2004.**Boundary Value Problems**, Pub Kamrup College, September 10, 2004.**Special Functions and Fourier Series (Two Lectures) ,**Refreshers Course on Applied Mathematics, Tezpur Central University, December 16-30, 2004.**Present Scenario in Mathematics Education and Research in Northeast India with Special Emphasis to Assam**, Dibrugarh University, January 10, 2005.**Approximation of Functions (Three Lectures)**, QIP-STC on Fundmentals in Numerical Computing, IIT Guwahati, June 6-10, 2005.**How to Motivate Students**, Refreshers Course for Higher Secondary Teachers, Cotton College, Guwahati, June 22, 2005.**Circular Functions,**7 Days Excursion in Mathematics, Darrang College, Tezpur, Assam, July 10, 2005**.****Vector Analysis (Three Lectures),**7-day workshop for degree mathematics students, Dibrugarh University, Dibrugarh, September 18-20, 2005**.****Basics in Trigonometry and Coordinate Geometry,**Workshop for High School Students, Gurdon H.S. School, Nalbari, Assam, December 19-25, 2005.**Special Functions: Theory and their Applications (Three Lectures),**Training Programme on Theoretical and Numerical Aspects of Ordinary Differential Equations, IIT Guwahati, December 15-24, 2005.**Fourier Series, Integral Transforms and their Applications (Three Lectures),**Refresher Course on Mathematics, Gauhati University, January 30-February 19, 2006.**Water Wave Scattering Problem for Varying Ocean Depth,**Sikkim Manipal Institute of Technology, Majitar, Sikkim, March 28, 2006**.****Popularizing Mathematics in Colleges: Challenges and Solutions,**Assam University, Silchar, April 25, 2006**.****Water Wave Scattering by a Small Undulation on the Ocean Bottom,**Research and Development Section In-house Seminar, IIT Guwahati, June 5, 2006.**Special Functions and their Applications (Two Lectures)**, QIP-STC on Mathematical Techniques in Science and Engineering, IIT Guwahati, June 26-30, 2006.**Fourier Series to Fourier Transform via Fourier Integrals (Two Lectures)**, QIP-STC on Mathematical Techniques in Science and Engineering, IIT Guwahati, June 26-30, 2006.**Some Integral Transforms and their Applications (Two Lectures)**, QIP-STC on Mathematical Techniques in Science and Engineering, IIT Guwahati, June 26-30, 2006.**Some Basic Ideas in Trigonometry and Geometry (Two Lectures),**Mathematics Training Programme for High School Students, DCB Girls College, Jorhat, Assam, April 9-13, 2007.**Geometry: From Algebra to Trigonometry (Two Lectures),**Summer Training Programme for High School Students, Chaiduar College, Gohpur, Assam, July**26-30,**2007.**Sturm-Liouville Boundary Value Problems (Two Lectures),**QIP-STC on Theory, Numerics and Applications of Differential Equations, IIT Guwahati, December 10-14, 2007.**Green’s Functions for Elliptic Equation,**QIP-STC on Theory, Numerics and Applications of Differential Equations, IIT Guwahati, December 10-14, 2007.**Application of Green’s Function to Water Wave Problems,**QIP-STC on Theory, Numerics and Applications of Differential Equations, IIT Guwahati, December 10-14, 2007.**Green’s Functions: Construction, Theory and Applications (Three Lectures),**Special School on Basic Sciences, Departmnt of Physics, Manipur University, Imphal, Manipur, Oct 4-24, 2008.**Boundary Value Problems and Orthogonal Functions,**Department of Mathematics, Cotton College, Guwahati, Assam, November 14, 2008.**Mathematics: A Long Journey through Ages,**5^{th}Regional Science Congress, Jawahar Navodaya Vidyalay, Rangia, Assam, November 18, 2008.**Power Series Solution of Differential Equations, Special Functions and their Applications (Two Lectures),**Refreshers’ Course on Mathematics, Gauhati University, Nov 17 – Dec 7, 2008.**Boundary Value Problems and Green’s Functions (Two Lectures), 11**Refresher Course in Mathematics, Gauhati University, Nov 17 – Dec 7, 2008.^{th}**Power Series, Special Functions and their Applications****(Two Lectures) ,**QIP-STC on Mathematical Methods, Modeling and Optimal Control, IIT Guwahati, June 2-6, 2009.**Integral Transforms and Applications (Two Lectures)**, QIP-STC on Mathematical Methods, Modeling and Optimal Control, IIT Guwahati, June 2-6, 2009.**Boundary Value Problems and Green’s Functions**, QIP-STC on Mathematical Methods, Modeling and Optimal Control, IIT Guwahati, June 2-6, 2009.**Green’s Functions: Constructions and Applications,**QIP-STC on Analytical and Numerical Solutions of Differential Equations, IIT Guwahati, December 6-10, 2010.**Integral Equations: Basic Ideas and Applications**, QIP-STC on Analytical and Numerical Solutions of Differential Equations, IIT Guwahati, December 6-10, 2010.**Interpolating Polynomials: Construction, their Properties and Uses (Two Lectures),**12^{th}Refresher Course in Mathematics, Gauhati University, March 11-31, 2011.**Numerical Integration,**12^{th}Refresher Course in Mathematics, Gauhati University, March 11-31, 2011.**Integral Equations: Basic Ideas and Applications,**12^{th}Refresher Course in Mathematics, Gauhati University, March 11-31, 2011**Differential Equations: Occurrences and Applications,**Department of Mathematics, Dibrugarh University, March 22, 2011**.****Boundary Value Problems: Idealizations, Formulation and Application (to Water Wave Problems),**Department of Mathematical Sciences, Institute of Science and Technology, Gauhati University, September 22, 2012.**What is Higher Mathematics and Where Does it Lead us to**, Invited Talk at the**National Seminar on Mathematics for School and College, organized by Shillong College, Shillong, December 7, 2013.****Differential Equations and Boundary Value Problems: Where is the Destination**, Invited Talk at the**National Seminar on Mathematics for School and College, organized by Shillong College, Shillong, December 8, 2013.****Importance of Mathematics in Engineering and Technology,**Invited talk at Assam textile Institute, organized Indian Society for technical Education, Assam Chapter, March 1, 2013.**Boundary Value problems: Some Features and Applications - I,**13th Refresher Course at Gauhati University, March 6, 2013.**Boundary Value problems: Some Features and Applications - II,**13th Refresher Course at Gauhati University, March 8, 2013.**Fourier Series and Fourier Integrals,**13th Refresher Course at Gauhati University, March 16, 2013.**Understanding and Applying Differential Equations: A Passage to the Applied World**, 4th Prof. K. Rajendra Singh Memorial Lecture, Manipur University, March 18, 2013.**Boundary Value Problems for Trapped Waves in Two-layer Fluids of Finite Depth**, Invited talk at National Seminar on Contemporary Issues in Mathematics and Statistics, organized by Gargaon College, Sivasagar, Assam, March 22, 2013.-
**Occurrence of Differential Equations in Physical Problems with Emphasis to Fluid Dynamics**, Invited Talk at National Seminar on Trends in Mathematical Achievements: The Importance of Basic Skills, organized by Khaira College, Balasore, Odisha, March 31, 2013. -
**Interpolating Polynomials**, QIP-STC on Role of Numerical Analysis in Scientific Computing, IIT Guwahati, May 20-24, 2013. -
**Differential Equations: How They Occur in Physical Problems,**Invited talk in the Department of Mathematics, Mizoram University, Aizawl, June 5, 2013. -
**Mathematics: Journey through the ages: Motivation and applications**, Invited talk at Chhaygaon College, Assam for*High School Teachers' Training Programme*, August 22, 2013. -
**Scattering and Trapping of Water Waves in Two-layer Fluids,**Invited talk at National Seminar on Recent Trends in Mathematics and Applications**,**organized by Digboi College, Assam, October 7-8, 2013. -
**Learning and Understanding Mathematics: an Endless but a Fruitful Journey,**Invited lecture at**Innovation in Science Pursuit for Inspired Research (INSPIRE),**MC College, Barpeta, December 21, 2014. -
**Damping of water waves by vertical porous structures**, Invited lecture, Department of Mathematics (Numerical Analysis), KTH Royal Institute of Technology, Stockholm, Sweden, September 8, 2014.