VISIT:

44. Department of Mathematics, University of Sharjah, Sharjah, UAE (26.01.2020--02.02.2020).

43. School of Mathematics and Statistics, Qinghai Normal University, China (03.01.2020--14.01.2020).

42. School of Mathematics and Statistics, Qinghai Normal University, China (04.07.2019--11.07.2019).

41. Department of Studies in Mathematics, University of Mysore, Mysuru-570006, India (26.06.2019--03.07.2019).

40. Department of Mathematics, Kuwait university, Kuwait (20.04.2019--27.04.2019).

39. Faculty of Mathematics and Statistics, Central China Normal University, Wuhan 430079, PR China (07.01.2019--10.01.2019).

38. School of Mathematics and Information Science, Yantai University, Yantai, 264005, P. R. China (03.01.2019--07.01.2019).

37. School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, PR China (28.12.2018--03.01.2019).

36. Faculty of Mathematics and Physics, Huaiyin Institute of Technology, Huai’an, Jiangsu 223003, PR China (24.12.2018--28.12.2018).

35. School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, PR China (19.12.2018--24.12.2018).

34. Department of Mathematics, University of Tarbiat Modares, Tehran, Iran (9.05.2018--13.05.2018)

33. School of Mathematics and Statistics, Qinghai Normal University, China (24.01.2018--29.01.2018)

32. School of Mathematics and Information Science, Yantai University, China (18.01.2018--23.01.2018)

31. College of Science, Nanjing University of Aeronautics & Astronautics, China (15.01.2018--18.01.2018)

30. School of Mathematics and Statistics, Qinghai Normal University, China (23.12.2017--15.01.2018)

29. CGANT, The University of Jember, Indonesia (26.11.2017--04.12.2017)

28. GERAD and HEC Montreal, Montreal QC, Canada (27.01.2017--26.02.2017)

27. Department of Mathematics, Mongolian National University of Education, Ulaanbaatar, Mongolia (21.08.2016--28.08.2016)

26. Center of Combinatorics, Nankai University, Tianjin, China (09.07.2016--14.07.2016)

25. Department of Mathematics, Shanghai University, Shanghai, China (01.07.2016--01.07.2016)

24. Department of Mathematics, East China University of Science and Technology, Shanghai, China (28.06.2016--03.07.2016)

23. Kragujevac University, Kragujevac, Serbia (21.05.2016--25.05.2016)

22. Universidade Federal do Rio de Janeiro, Brazil (18.02.2016--29.02.2016)

21. Instituto de Matemtica, UFRGS Avenida Bento Gonalves, Porto Alegre, RS, Brazil (11.02.2016--18.02.2016)

20. Department of Mathematics, Delaware University, USA (01.02.2016--10.02.2016)

19. Department of Mathematics, University of Kashan, Kashan, Iran (22.08.2015--24.08.2015)

18. Department of Mathematics, Shahid Rajaee, Teacher Training University, Tehran, Iran (19.08.2015--22.08.2015)

17. Department of Mathematics, Universiti of Putra Malaysia, Kuala Lumpur, Malaysia (24.06.2015--30.06.2015)

16. Department of Mathematics, South China normal University, Guangzhou, China (12.01.2015--12.01.2015)

15. Department of Mathematics, South China Agricultural University, Guangzhou, China (11.01.2015--18.01.2015)

14. Department of Mathematics, Shanghai University, Shanghai, China (08.01.2015--08.01.2015)

13. Department of Mathematics, East China University of Science and Technology, Shanghai, China (04.01.2015--11.01.2015)

12. Department of Mathematics, Yantai University, Yantai, China (27.12.2014--04.01.2015)

11.Dept. of Mathematics, Nanjing University of Aeronautics & Astronautics, China (23.12.2014--27.12.2014,18.01.2015--22.01.2015)

10. Department of Mathematics, Beijing Institute of Technology, Beijing, China (28.11.2014--01.12.2014)

9. Dept. of Mathematics, Nanjing University of Aeronautics & Astronautics, China (28.05.2014--01.06.2014)

8. Dept. of mathematics, Uludag University, Bursa, Turkey (16.08.2013--25.08.2013)

7. Vijayanagara Sri Krishnadevaraya University, Bellary, India (23.02.2013--25.02.2013)

6. Dept. of Mathematics, Nanjing University of Aeronautics & Astronautics, China (17.01.2013--05.02.2013)

5. Dept. of mathematics, Uludag University, Bursa, Turkey (22.08.2012--31.08.2012)

4. Dept. of mathematics, Selcuk University, Konya, Turkey (13.08.2012--21.08.2012).

3. Indian Statistical Institute, Kolkata, India (18.01.2011--30.01.2011).

2. The Institute of Mathematical Sciences (IMSc), India, (22.01.2008--01.02.2008).

1. Indian Statistical Institute, New Delhi, India (18.02.2007--24.02.2007).

Conference Talk/Invited Talk:

22. On eigenvalues of adjacency, Laplacian, Signless Laplacian and $A_{\alpha}$ matrix of graphs, Qinghai Normal University, Xining, P. R. China (10.01.2020).

21. On Independence Number and Metric Dimension of trees, CID 2019, 18th Workshop on Graph Theory, Piechowice, Poland (15.09.2019--20.09.2019).

20. Laplacian eigenvalues to Laplacian energy, 2019 The Workshop on the theory of graph spectra and hypergraphs, Qinghai, PR China (05.07.2019--06.07.2019).

19. On Laplacian eigenvalues and Laplacian energy of graphs, Department of Studies in Mathematics, University of Mysore, Mysuru-570006, India (27.06.2019--29.06.2019).

18. On Laplacian eigenvalues and Laplacian energy of graphs, 2018 Workshop on Graph Theory and its Applications, Hangzhou Jijin Hotel, School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, PR China (21.12.2018--22.12.2018).

17. Comparison between topological indices of graphs, The Eight Conference And Workshop on Mathematical Chemistry (ECWMC 2018), University of Tarbiat Modares, Tehran, Iran (10.05.2018--11.05.2018)

16. On Laplacian eigenvalues and Laplacian energy of graphs, The First International Conference Combinatoric, Graph Theory and

Network Topology 2017, The University of Jember, Indonesia (24.11.2017--26.11.2017).

15. On energy, Laplacian energy and signless Laplacian energy of graphs, 12th Annual Meeting of the IAMC & 2016 ICMC, Nankai University, Tianjin, China (04.07.2016--08.07.2016).

14. On (Signless) Laplacian eigenvalues of graphs, Spectra of graphs and applications 2016, May 1820, 2016, Serbian Academy of Sciences and Arts, Belgrade, Serbia (18.05.2016--20.05.2016).

13. On Laplacian eigenvalues of graphs, 46th Annual Iranian Mathematics Conference (AIMC 46), Yazd University, Yazd, Iran (24.08.2015--29.08.2015).

12. Proof of conjectures on the distance signless Laplacian eigenvalues of graphs, Renmin University, Beijing, China (28.11.2014--30.11.2014) (The First International Conference on Big Data & Applied Stat.)

11. On Kirchhoff index, Laplacian energy and Laplacian-energy-like invariant of graphs, KSIAM, Jeju, South Korea (20.11.2014--23.11.2014)

10. Relation between energy of different matrices from graph, Shanghai Jio-Tang University, Shanghai, China (24.05.2014--28.05.2014) (The Eight Shanghai Conference on Combinatorics May 24th May 28, 2014 Shanghai)

9. Eigenvalues of graph matrices and graph parameters, Moscow State University, Russia (26.01.2014--02.02.2014) (Moscow Workshop on Combinatorics and Number Theory)

8. Relation between eigenvalues of the graph matrices and the graph parameters, Tohuku University, Japan (28.11.2013--01.12.2013).

7. Sharp bounds on the energy of graphs, Balikesir University, Turkey (12.08.2013--15.08.2013).

6. Eigenvalues and graph parameters, NCAAM, Reva Institute of Technology and Management, Bangalore, India (22.02.2013).

5. The number of spanning trees of a graph, Bursa Conference, Turkey (23.08.2012).

4. On conjectures involving second largest signless Laplacian eigenvalue of graphs, KMS-AMS meeting, Seoul, Korea, December 2009.

3. Bounds on the degree distance of a graph, Combinatorics workshop, Sungkyunkwan Unibversity, Korea, August 2008.

2. On the conjecture for certain Laplacian integral spectrum of graphs, International Conference on Linear Algebra, Shanghai University, Shanghai, China, July 2007.

1. Laplacian Spectrum of a Graph, Workshop on Graph Theory and Combinatorics in Ballarat University, Australia, October 2004.

Talk:

35. On the properties of the topological indices of graphs, Department of Mathematics, University of Sharjah, Sharjah, UAE (29.01.2020).

34. Comparison between topological indices of graphs, Kuwait College of Science and Technology, Kuwait (25.04.2019).

33. On Laplacian eigenvalues and Laplacian energy of graphs, School of Mathematics and Information Science, Yantai University, China (23.01.2018).

32. Comparison between topological indices of graphs, College of Science, Nanjing University of Aeronautics & Astronautics, China (16.01.2018).

31. On energy and Laplacian energy of graphs, School of Mathematics and Statistics, Qinghai Normal University, China (05.01.2018).

30. On the Graovac-Ghorbani index of graphs, School of Mathematics and Statistics, Qinghai Normal University, China (01.01.2018).

29. On Laplacian eigenvalues of graphs, School of Mathematics and Statistics, Qinghai Normal University, China (25.12.2017).

28. Comparison between topological indices of graphs, School of Mathematics and Statistics, Qinghai Normal University, China (24.12.2017).

27. On Laplacian eigenvalues of graph, GERAD and HEC Montreal, Montreal, QC, Canada (09.02.2017).

26. On Laplacian eigenvalues of graph, Department of Mathematics, Mongolian National University of Education, Ulaanbaatar, Mongolia (25.08.2016).

25. On the Laplacian spread of a graph, Shanghai University, Shanghai, China (01.07.2016).

24. On Laplacian eigenvalues of graphs, University of Kragujevac, Kragujevac, Serbia (24.05.2016).

23. Energy and Laplacian energy of graphs, Universidade Federal do Rio de Janeiro, Brazil (24.02.2016).

22. On Laplacian eigenvalues of graphs, Universidade Federal do Rio de Janeiro, Brazil (22.02.2016).

21. On (signless) Laplacian eigenvalues of graphs, Department of Mathematics, Delaware University, USA (08.02.2016).

20. Spectral graph theory: Four common spectra, Department of Chemistry, Korea University, Seoul, Republic of Korea (04.12.2015).

19. On (signless) Laplacian eigenvalues of graphs, Department of Mathematics, Shahid Rajaee, Teacher Training University, Tehran, Iran (22.08.2015).

18. Comparison between topological indices of graphs, Institut Penyelidikan Matematik, Universiti Putra Malaysia Kualalumpur, Malaysia (30.06.2015).

17. Comparison between the Szeged index and the eccentric connectivity index, South China Agricultural University, Guangzhou, China (13.01.2015).

16. On the distance signless Laplacian eigenvalues of graphs, South China normal University, Guangzhou, China (12.01.2015).

15. On Laplacian eigenvalues of graphs, Shanghai University, Shanghai, China (08.01.2015).

14. Proof of conjectures on the distance signless Laplacian eigenvalues of graphs, East China University of Science and Technology, Shanghai, China (05.01.2015).

13. On Kirchhoff Index and degree Kirchhoff index of graphs, Yantai University, China (31.12.2014).

12. Comparison between the Szeged index and the eccentric connectivity index, Nanjing University of Aeronautics & Astronautics, China (25.12.2014).

11. On Kirchhoff Index of graphs, Nanjing University of Aeronautics & Astronautics, China (29.05.2014).

10. Eigenvalues and Energy of He matrix of the Hexagonal Systems, Vijayanagara Sri Krishnadevaraya University, Bellary, India (25.02.2013).

9. On algebraic connectivity of graphs, Nanjing University of Aeronautics & Astronautics, China (19.01.2013).

8. The relation between eigenvalues of graphs with graph parameters, Nanjing University of Aeronautics & Astronautics, China (18.01.2013).

7. Graph, Eigenvalues and Applications, Selcuk University, Konya, Turkey (16.08.2012).

6. The Institute of Mathematical Sciences (IMSc), India, January, 2008.

5. Hannam University, Taejon, South Korea, March 2007.

4. Sungkyunkwan University, South Korea, December 2006.

3. LRI, University Paris-XI, Paris, France, December 2005.

2. Pohang University of Science and Technology, Pohang, South Korea, April 2005.

1. Ballarat University, Australia, November 2004.