Vol. 48 No. 1 (2016)

In this paper, a system of non nonlinear differential equations withimpulse effect at fixed time moments is considered and criteria for retention ofuniform eventual stability of its perturbed impulsive differential systems undervanishing perturbations are established. Sufficient conditions are obtained byusing piecewise continuous Lyapunov functions. An example is also worked outto illustrate the results.AMS Subject Classification: 34CXX, 34DXX, 34A37, 34K45.

The annual growth of Porites coral is represented by a pair of high- and low-density bands. Environmental changes in the ambient waters influence the pattern of these annual density bands. Five colonies of Porites corals from Nusa Penida, Bali were investigated to analyze their annual linear growth rates using coral densitometry. From the analysis it was found that the annual linear growth rates of the colonies varied between 0.8924 to 1.0012 cm/yr. The trends of the colonies growth rates also varied. Two colonies showed a decreasing trend, while the others showed an increasing trend. The…

In this paper we present approximate solutions of linearized delay differential equations using the matrix Lambert function. The equations arise from a microbial fermentation process in a metabolic system. The delay term appears due to the existence of a rate-limiting step in the fermentation pathway. We find that approximate solutions can be written as a linear combination of the Lambert function solutions in all branches. Simulations are presented for three cases of the ratio of the rate of glucose supply to the maximum reaction rate of the enzyme that experienced delay. The simulations are…

The locating-chromatic number of a graph G can be defined as the cardinality of a minimum resolving partition of the vertex set V(G) such that all vertices have distinct coordinates with respect to this partition and every two adjacent vertices in G are not contained in the same partition class. In this case, the coordinate of a vertex v in G is expressed in terms of the distances of v to all partition classes. This concept is a special case of the graph partition dimension notion. Previous authors have characterized all graphs of order n with locating-chromatic number either n or n-1. They…

ZnO nanorods were synthesized on silicon wafer substrate with a seed zinc layer using the aqueous solution method. The influence of various precursor compositions on the morphology of the ZnO nanorods, with substrate angles at 0° and 90°, was investigated. The various ratios of hexamethylenetetramine in zinc nitrate hexahydrate were used as precursors in the synthesis of ZnO. Scanning electron micrography indicated that the growth of the ZnO nanorods with a 0° substrate angle was smaller than with a 90° substrate angle. The substrate angle is defined as the angle between the plane of the…

Ba0.6Sr0.4Fe12-zMnzO19 (z = 0,1,2, and 3) were successfully synthesized by solid state reaction through a mechanical milling method. Stoichiometric quantities of analytical-grade MnCO3, BaCO3, Fe2O3, and SrCO3 precursors with purity greater than 99% were mixed. It was found that the best phase composition, having an absorber with high performance, was Ba0.6Sr0.4Fe11MnO19. Refinement of the X-ray diffraction patterns revealed that the Ba0.6Sr0.4Fe11MnO19 was single-phase and had a hexagonal structure (P63/mmc). Mechanical milling of Ba0.6Sr0.4Fe11MnO19 powders produced particles with a mean…

The Oligocene cycle of Pesada Well, Central Sumatra Basin, Indonesia is composed of a deepening-upward series of depositional cycles in a lacustrine environment affected by oscillations of the water level. Taphonomic analysis of gastropod molluscs was used to interpret the cycle architecture of the Brown Shale (Pematang Group). Four types of shell concentrations were identified. The early transgressive deposit has a distinct erosion surface at the base, contains concretions, is formed of coarse-grained sediment with abraded and broken shells, and is interpreted as reworked deposits. The late…