TESTING, QUALITY, ELECTRONICS, RELIABILITY in engineering, MATHEMATICAL optimization, and MAINTAINABILITY (Engineering)
A new technique for reliability and quality optimization of electronic components and assemblies, the so called in situ accelerated ageing technique with electrical testing, is presented. This technique is extremely useful for the building-in approach to quality and reliability. First, it can be used to optimize an electronic component or assembly with respect to its quality and reliability performance at a very early stage, i.e. at the design level, at the level of materials selection, and at the level of identifying production techniques and defining production parameters. The typical test time is of the order of 24 hours, which is sufficiently short to allow a design of experiments type approach to quality and reliability optimization. Furthermore, the technique is also very useful for obtaining a deeper understanding of the physico-chemical processes which lead to failure. A number of practical examples where the technique has been successfully applied are discussed. [ABSTRACT FROM AUTHOR]
Heinrichs, E. A., Sy, A. A., Akator, S. K., and Oyediran, I.
International Journal of Pest Management. Oct-Dec1997, Vol. 43 Issue 4, p291-297. 7p.
PLANTING and RICE
Monthly plantings of the rice variety Bouake 189 were made under lowland irrigated conditions, to obtain information on the phenological and seasonal occurrence of pests and diseases on the West African Rice Development Association (WARDA) research farm near Bouake, Cote d'Ivoire. Regular sampling of insect pests and observations on rice yellow mottle virus (RYMV) disease infection throughout the year provided information on the occurrence of RYMV and potential insect vectors. RYMV incidence and grain yields varied depending on planting date, and for a given planting date, varied from one year to another. There was no evidence that RYMV incidence increases in successive seasons under continuous cropping. There was no significant correlation between RYMV incidence and either rainfall or wind speed. Leaf feeding damage by the beetle vector of RYMV, Trichispa sericea Guerin-Meneville (Coleoptera: Chrysomelidae), and percentage RYMV infected plants were severe in the July and August plantings in 1993, but whereas T. sericea was not observed thereafter, RYMV spread continued. The white leafhoppers Cofana spectra (Distant) and C. unimaculata (Signoret) (Hemiptera: Cicadellidae), the green leafhoppers Nephotettix spp. (Hemiptera: Cicadellidae), the spittle bug Locris rubra F. (Hemiptera: Cercopidae), the diopsids Diopsis longicornis Macquart and D. apicalis Dalman (Diptera: Diopsidae), and the grasshopper Oxy hyla Stal (Orthoptera: Acridadae) were the most abundant of the insect pests and had distinct population peaks within a year. However, population abundances were not correlated with RYMV incidence. The variability of RYMV in time and space and the potential role of weeds as alternative hosts for RYMV are discussed. [ABSTRACT FROM AUTHOR]
Explores the ecological aspects of dinitrogen fixation in the world's oceans. Diversity of dinitrogen-fixing microorganisms; Major controls on rates of oceanic dinitrogen fixation; Significance of dinitrogen fixation for the global carbon cycle; Role of human activities in the alteration of oceanic dinitrogen fixation.
The effects of secondary metabolites in different Vigna species on the development of Clavigralla tomentosicollis were investigated in an artificial seed system using different fractions of crude pod extracts, while the orientation response of this pod-bug to volatile extracts was studied using a dual-choice olfactometer. Feeding on the neutral fraction extracts, in contrast to the basic and acidic fractions, resulted in significantly higher mortalities, longer total developmental time, and lower growth index of the insects in comparison with controls. All volatile extracts elicited an avoidance reaction by C. tomentosicollis, except the volatile from the susceptible genotype IT84S-2246 which generally attracted as many insects as controls. Extracts from wild Vigna species showed higher activity than those from their cultivated relatives. The present study which has established that most secondary metabolites in cowpea pods were localized in the neutral fraction of the crude extract, could facilitate experiments on the separation and characterization of the toxic factors involved. [ABSTRACT FROM AUTHOR]