BUKU ABSTRAK - Universiti Putra Malaysia

An Embedded Explicit Runge-Kutta-Nystrom Method for Solving Oscillatory
Problems
Dr. Norazak Senu
Mohamed Suleiman and Fudziah Ismail
Faculty of Science, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 6848; razak@math.upm.edu.my
Keywords: Runge-Kutta-Nystrom method, phase-lag, oscillatory problem
A XML based, User-centered Privacy Model in Pervasive Computing Systems
Dr. Nur Izura Udzir
Ali Dehghantanha and Ramlan Mahmod
Faculty of Computer Science and Information Technology, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 6521; izura@fsktm.upm.edu.my
Keywords: Privacy, pervasive computing, identity privacy, location privacy, time privacy
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Science, Technology & Engineering
A new pair of embedded explicit Runge-Kutta-Nyström (RKN) methods are developed to integrate secondorder
differential equations of the form q” = f(t,q) where the solution is oscillatory. The embedded formula has
dispersion order eight and dissipation order seven for the fifth-order formula. The cost for this pair is four function
evaluations at each step of integration. Numerical comparisons with several codes in the scientific literature such
as RKN5(4)D, RKN5(4)B, RKN4(3)G and DOPRI5 show the efficiency of the new method developed.
Pervasive systems are typically embedded and invisible which make it difficult for users to know when,
where, and how these devices are collecting data. With that, privacy is a major issue for pervasive computing
applications and several privacy models have been proposed for pervasive environments. In this paper, we present
a XML based User-centered Privacy Model (UPM) which provides content, identity, location, and time privacy
with low unobtrusiveness.