Nurunajah Ab Ghani

Application of bootstrap technique in power system risk assessment

This paper presents the risk assessment of power system that takes into account the system failure indices and uncertainty of unavailable load variations estimated by using the bootstrap technique. The risk of the system is measured by using the expected energy not supplied (EENS) index as well as the probability of load curtailment (PLC). The bootstrap technique is a tool which provides simplest way to perform risk assessment of a power system. Furthermore, it also requires very little assumptions to carry-out the risk analysis and it is imperative for a small size of available information. The application of bootstrap technique is important to assess the risk indices at every level of system uncertainty. The IEEE 24-bus Reliability Test System (RTS) is used as a case study in the analysis of system risk severity based EENS and PLC. Comparative studies have been made on the risk assessment of the power system determined by using the bootstrap technique and fuzzy set.

Secondary metabolites from endemic species Iris adriatica Trinajstić ex Mitić (Iridaceae)

Abstract This manuscript describes the first detailed chemical investigation of endemic species Iris adriatica, including isolation and structure elucidation. Chemical analyses of the rhizome CH2Cl2/MeOH (2:1) extract revealed fourteen secondary metabolites, mainly isoflavonoids. Among isoflavonoids, two groups have been found: nigricin-type and tectorigenin-type. Dominant group of the isolated compounds has been nigricin-type isoflavones: nigricin, nigricin-4′-(1-O-β-D-glucopyranoside) and nigricin-4′-(1-O-β-D-glucopyranosyl (1–6)-β-D-glucopyranoside) with 2.5, 10 and 1% of the total extract, respectively. Irisxanthone – xanthone C-glucoside, β-sitosterol, benzophenone and one of its derivatives have also been found. Nigricin-type isoflavonoids and irisxanthone can be considered as possible chemotaxonomic markers for I. adriatica. 5,3′,5′-Trimethoxy-6,7-methylenedioxyisoflavone-4′-(1-O-β-D-glucopyranoside) and benzophenone have been isolated from Iris species for the first time. Left-hand image of Iris adriatica (Adriatic potato) with redditsh purple flowers