A Two-Stage Approach for Routing Multiple Unmanned Aerial Vehicles with Stochastic Fuel Consumption

The past decade has seen a substantial increase in the use of small unmanned aerial vehicles (UAVs) in both civil and military applications. This article addresses an important aspect of refueling in the context of routing multiple small UAVs to complete a surveillance or data collection mission. Specifically, this article formulates a multiple-UAV routing problem with the refueling constraint of minimizing the overall fuel consumption for all of the vehicles as a two-stage stochastic optimization problem with uncertainty associated with the fuel consumption of each vehicle. The two-stage model allows for the application of sample average approximation (SAA). Although the SAA solution asymptotically converges to the optimal solution for the two-stage model, the SAA run time can be prohibitive for medium- and large-scale test instances. Hence, we develop a tabu-search-based heuristic that exploits the model structure while considering the uncertainty in fuel consumption. Extensive computational experiments corroborate the benefits of the two-stage model compared to a deterministic model and the effectiveness of the heuristic for obtaining high-quality solutions.Comment: 18 page

PREDICTION OF GAS HOLD-UP IN A COMBINED LOOP AIR LIFT FLUIDIZED BED REACTOR USING NEWTONIAN AND NON-NEWTONIAN LIQUIDS

Many experiments have been conducted to study the hydrodynamic characteristics of column reactors and loop reactors. In this present work, a novel combined loop airlift fluidized bed reactor was developed to study the effect of superficial gas and liquid velocities, particle diameter, fluid properties on gas holdup by using Newtonian and non-Newtonian liquids. Compressed air was used as gas phase. Water, 5% n-butanol, various concentrations of glycerol (60 and 80%) were used as Newtonian liquids, and different concentrations of carboxy methyl cellulose aqueous solutions (0.25, 0.6 and 1.0%) were used as non-Newtonian liquids. Different sizes of spheres, Bearl saddles and Raschig rings were used as solid phases. From the experimental results, it was found that the increase in superficial gas velocity increases the gas holdup, but it decreases with increase in superficial liquid velocity and viscosity of liquids. Based on the experimental results a correlation was developed to predict the gas hold-up for Newtonian and non-Newtonian liquids for a wide range of operating conditions at a homogeneous flow regime where the superficial gas velocity is approximately less than 5 cm/

Transcranial direct current stimulation for mild cognitive impairment

Mild cognitive impairment (MCI) is recognized as a target for early intervention in elderly with high risk for dementia due to Alzheimer's disease (AD) and other related disorders. Transcranial direct current stimulation (tDCS) is reemerging as a novel method of noninvasive brain stimulation in various neuropsychiatric disorders including MCI and dementia based on the potential clinical applications of its utility in modulating neuroplasticity. In this article, we review the neurobiology of aging, AD, and MCI from the perspective of tDCS and summarize the findings from studies applying tDCS in MCI to improve cognitive function. Studies on therapeutic application of tDCS to improve cognitive function in MCI and other related disorders have shown mixed results. Limited studies available in this topic suggest a potential role for tDCS in MCI. Low risk for adverse effects, lower cost, and the possibility of self-administered home-based intervention are important advantages that encourage further research in this field. There is a need for more evidence from large systematic randomized controlled trials regarding the efficacy of tDCS in MCI. Standardization of stimulation protocols, evaluation of long-term outcome with the possibility of maintenance tDCS, and efficacy of combined intervention of tDCS and cognitive training are important areas for future research in this area

MOESM2 of Xylan epitope profiling: an enhanced approach to study organ development-dependent changes in xylan structure, biosynthesis, and deposition in plant cell walls

Additional file 2: Figure S2. Heat map showing gene expression from publicly available microarray data [29] of xylan genes in different stages of Col-0 stem development from immature (D1), intermediate (D2-D3), and mature (D4) stems. Levels of low (white) and high expression (red) are shown on a log2 scale for each xylan gene