Boundary Interactions of Rough non-Gaussian Surfaces

Surface topography is important as it influences contact load-carrying capacity and operational efficiency through generated friction, as well as wear. As a result, a plethora of machining processes and surface finishing techniques have been developed. These processes yield topographies, which are often non-Gaussian, with roughness parameters that alter hierarchically according to their interaction heights. They are also subject to change through processes of rapid initial running-in wear as well as any subsequent gradual wear and embedding. The stochastic nature of the topography makes for complexity of contact mechanics of rough surfaces, which was first addressed by the pioneering work of Greenwood and Williamson, which among other issues is commemorated by this contribution. It is shown that their seminal contribution, based on idealised Gaussian topography and mean representation of asperity geometry should be extended for practical applications where surfaces are often non-Gaussian, requiring the inclusion of surface-specific data which also evolve through process of wear. The paper highlights a process dealing with practical engineering surfaces from laboratory-based testing using a sliding tribometer to accelerated fired engine testing for high performance applications of cross-hatched honed cylinder liners. Such an approach has not hitherto been reported in literature

Comparison of the efficacy of long-lasting insecticidal nets PermaNet® 2.0 and Olyset® against Anopheles albimanus under laboratory conditions

Insecticide-treated nets provide a reduction in human-vector contact through physical barrier, mortality and/or repellent effects that protect both users and non-users, thereby protecting the wider community from vector-borne diseases like malaria. Long-lasting insecticide-treated nets (LLINs) are the best alternative. This study evaluated the bioefficacy of LLINs PermaNet® 2.0 and Olyset® under laboratory conditions with Anopheles albimanus. The laboratory strain was evaluated for insecticide susceptibility with selected insecticides used for malarial control. Regeneration time and wash resistance were evaluated with the standard bioassay cone technique following WHO guidelines. Heat assistance was used for Olyset® nets; the nets were exposed to four different temperatures to speed the regeneration process. The regeneration study of PermaNet® 2.0 showed that efficacy was fully recovered by 24 h after one and three washes and wash resistance persisted for 15 washes. Regeneration of Olyset® nets was not observed for nets washed three times, even with the different temperature exposures for up to seven days. Thus, for Olyset® the wash resistance evaluation could not proceed. Differences in response between the two LLINs may be associated with differences in manufacturing procedures and species response to the evaluated LLINs. PermaNet® 2.0 showed higher and continuous efficacy against An. albimanus

Plant-level dynamics and aggregate productivity growth in the Turkish meat-processing industry: Evidence from longitudinal data

The authors examine how plant-level dynamics contribute to aggregate productivity growth in the Turkish meat-processing industry. An aggregate productivity decomposition approach that utilizes plant-level longitudinal data is used to achieve this goal. Their results are consistent with the empirical literature in the sense that productivity enhancement within existing plants is the main source of aggregate productivity growth in this sector. However, their analysis generally suggests that plants that exit the meat-processing industry tend to be more productive than entering plants, especially in the posteconomic crisis period studied. Even though the latter insight is not consistent with the existing empirical literature, they show that these results tend to support R. Caballero and M. Hammour's (2000) contention that institutional factors such as industry structure (i.e., mature vs. infant industry) and economic crisis conditions (i.e., pre- vs. postcrisis periods) affect the nature of plant dynamics' contributions to aggregate productivity growth. Overall, the study's results reveal that industry-specific institutional factors must be taken into consideration when shaping policies aimed to improve and sustain aggregate productivity growth. [JEL Classifications: D24, L25, O12]. © 2006 Wiley Periodicals, Inc. Agribusiness 22: 91-107, 2006.