Laser-induced temperature rise in a composite sandwich structure

Journal of Mathematical and Computational Science, Vol. 3 Issue 2, pages 577-593, 2013We investigate the transient temperature rise in a composite sandwich structure induced by a stationary, dithering, or rotating laser beam. We restrict our study to the composite sandwich structure with carbon fiber as skin materials and honeycomb as core materials. Our numerical simulations indicate that the maximum temperature rise behaves as a quadratic function of the reciprocal of the skin thickness or the effective beam size

Pacific fleet submarine tender optimization

In this thesis, we develop a mixed-integer, linear optimization model to guide the resourcing of submarine maintenance conducted by the U.S. Navys two submarine tenders in the Fifth and Seventh Fleets. We assume maintenance demands are known over a given planning horizon, e.g., one month. Inputs to the model include travel times and costs for fly-away teams and tenders to move to where the maintenance is needed. Each maintenance demand can be divided into tasks with characteristics such as: whether or not tender presence is required; the estimated total number of worker-days required; the maximum number of workers that can simultaneously work on each task; the types of maintenance workers that can perform the task; and task due dates. The models output determines the assignment of personnel to meet the demand at minimum cost, including delay penalties. It also guides personnel travel (as a fly-away team or by tender). In addition, the model can be used to accommodate emergent, unscheduled demands by producing an updated schedule that minimizes the impact on an existing schedule. We test our model on small and realistically sized notional examples to demonstrate the input and output of the models, as well as computational run-times.http://archive.org/details/pacificfleetsubm1094534722Major, United States ArmyApproved for public release; distribution is unlimited

Different plant viruses induce changes in feeding behavior of specialist and generalist aphids on common bean that are likely to enhance virus transmission

Bean common mosaic virus (BCMV), bean common mosaic necrosis virus (BCMNV), and cucumber mosaic virus (CMV) cause serious epidemics in common bean (Phaseolus vulgaris), a vital food security crop in many low-to-medium income countries, particularly in Sub-Saharan Africa. Aphids transmit these viruses "non-persistently," i.e., virions attach loosely to the insects' stylets. Viruses may manipulate aphid-host interactions to enhance transmission. We used direct observation and electrical penetration graph measurements to see if the three viruses induced similar or distinct changes in feeding behaviors of two aphid species, Aphis fabae and Myzus persicae. Both aphids vector BCMV, BCMNV, and CMV but A. fabae is a legume specialist (the dominant species in bean fields) while M. persicae is a generalist that feeds on and transmits viruses to diverse plant hosts. Aphids of both species commenced probing epidermal cells (behavior optimal for virus acquisition and inoculation) sooner on virus-infected plants than on mock-inoculated plants. Infection with CMV was especially disruptive of phloem feeding by the bean specialist aphid A. fabae. A. fabae also experienced mechanical stylet difficulty when feeding on virus-infected plants, and this was also exacerbated for M. persicae. Overall, feeding on virus-infected host plants by specialist and generalist aphids was affected in different ways but all three viruses induced similar effects on each aphid type. Specifically, non-specialist (M. persicae) aphids encountered increased stylet difficulties on plants infected with BCMV, BCMNV, or CMV, whereas specialist aphids (A. fabae) showed decreased phloem ingestion on infected plants. Probing and stylet pathway activity (which facilitate virus transmission) were not decreased by any of the viruses for either of the aphid species, except in the case of A. fabae on CMV-infected bean, where these activities were increased. Overall, these virus-induced changes in host-aphid interactions are likely to enhance non-persistent virus transmission, and data from this work will be useful in epidemiological modeling of non-persistent vectoring of viruses by aphids