Vol. 47 No. 2 (2015)

We discuss the problem of deriving an estimative prediction limit as well as a simulation-based improved prediction limit for a future realization from the stationary, first-order Poisson INAR(1) process. An assessment of these limits was carried out by calculating their coverage probability, conditional on the last observation. It was found that while an estimative prediction limit may always be calculated, an improved prediction limit may not be obtained due to its discreteness and expectation to obtain a coherent prediction.

The heat island (HI) effect in metropolitan Jakarta was studied using air temperature measurements at 9 meteorological stations in Jakarta, Tanjung Priok, Serang, Halim, Cengkareng, Pondok Betung, Curug, Bogor, Citeko during 1986-2008 and Serpong during 2008-2011 and 2013; land use for forest, industry, water, settlement, open/cleared land in 1997, 2004, 2009, 2012; and total number of industries and total number of vehicles during 1986-2011. Harmonic analysis was used to remove the seasonal component from the temperature time series data, which was filtered with the 30-day moving average…

In this paper, by using the fixed point method, we prove two new results on the Hyers-Ulam-Rassias and the Hyers-Ulam stability for the first order delay differential equation of the formy"²(t) = F(t, y(t), y(t −τ )).Our results improve some related results in the literature.

This paper deals with countable fuzzy topological spaces, a generalization of the notion of fuzzy topological spaces. A collection of fuzzy sets F on a universe X forms a countable fuzzy topology if in the definition of a fuzzy topology, the condition of arbitrary supremum is relaxed to countable supremum. In this generalized fuzzy structure, the continuity of fuzzy functions and some other related properties are studied. Also the class of countable fuzzy topological vector spaces as a generalization of the class of fuzzy topological vector spaces has been introduced and investigated.

Breakdown in Lanczos-type algorithms is a common phenomenon which is due to the non-existence of some orthogonal polynomials. It causes thesolution process to halt. It is, therefore, important to deal with it to improve the resilience of the algorithms and increase their usability. In this paper, we consider restarting from a number of different approximate solutions that seem to be attractive starting points. They are: (a) the last iterate preceding breakdown, (b) the iterate with minimum residual norm found so far, and (c) the approximate solution whose entries are the median values of…

Integrated studies of the stratigraphy, sedimentology and molluscan paleontology of several late Neogene localities in West and Central Java (Indonesia) showed that deposition took place under marine conditions until early in the Pleistocene in the Bobotsari Basin. In contrast, in the adjacent Bogor and North Serayu basins deposition was terrestrial (fluviatile) during the Pleistocene, as subsidence had ceased. Our interpretation is based mainly on the marine mollusks present in the Plio-Pleistocene Bantardawa-Talanggudang Formation in the Bobotsari Depression. This interpretation is…

The application of nanotechnology to produce nanomaterials from renewable bio-based materials, like wood bark, has great potential to benefit the wood processing industry. To support this issue, we investigated the production of bio-based nanomaterials using conventional balls milling. Jabon (Anthocephalus cadamba (Roxb.) Miq) wood bark (JWB), an organic waste material from a community forest was subjected to conventional balls milling for 96 h and was converted into bio-based nanomaterial. The morphology and particle size, chemical components, functional groups and crystallinity of the…