Eigensolution analysis of spectral/hp continuous Galerkin approximations to advection-diffusion problems: insights into spectral vanishing viscosity

AbstractThis study addresses linear dispersion–diffusion analysis for the spectral/hp continuous Galerkin (CG) formulation in one dimension. First, numerical dispersion and diffusion curves are obtained for the advection–diffusion problem and the role of multiple eigencurves peculiar to spectral/hp methods is discussed. From the eigencurves' behaviour, we observe that CG might feature potentially undesirable non-smooth dispersion/diffusion characteristics for under-resolved simulations of problems strongly dominated by either convection or diffusion. Subsequently, the linear advection equation augmented with spectral vanishing viscosity (SVV) is analysed. Dispersion and diffusion characteristics of CG with SVV-based stabilization are verified to display similar non-smooth features in flow regions where convection is much stronger than dissipation or vice-versa, owing to a dependency of the standard SVV operator on a local Péclet number. First a modification is proposed to the traditional SVV scaling that enforces a globally constant Péclet number so as to avoid the previous issues. In addition, a new SVV kernel function is suggested and shown to provide a more regular behaviour for the eigencurves along with a consistent increase in resolution power for higher-order discretizations, as measured by the extent of the wavenumber range where numerical errors are negligible. The dissipation characteristics of CG with the SVV modifications suggested are then verified to be broadly equivalent to those obtained through upwinding in the discontinuous Galerkin (DG) scheme. Nevertheless, for the kernel function proposed, the full upwind DG scheme is found to have a slightly higher resolution power for the same dissipation levels. These results show that improved CG-SVV characteristics can be pursued via different kernel functions with the aid of optimization algorithms

Charging ahead on the transition to electric vehicles with standard 120 v wall outlets

Electrification of transportation is needed soon and at significant scale to meet climate goals, but electric vehicle adoption has been slow and there has been little systematic analysis to show that today's electric vehicles meet the needs of drivers. We apply detailed physics-based models of electric vehicles with data on how drivers use their cars on a daily basis. We show that the energy storage limits of today's electric vehicles are outweighed by their high efficiency and the fact that driving in the United States seldom exceeds 100 km of daily travel. When accounting for these factors, we show that the normal daily travel of 85-89% of drivers in the United States can be satisfied with electric vehicles charging with standard 120 V wall outlets at home only. Further, we show that 77-79% of drivers on their normal daily driving will have over 60 km of buffer range for unexpected trips. We quantify the sensitivities to terrain, high ancillary power draw, and battery degradation and show that an extreme case with all trips on a 3% uphill grade still shows the daily travel of 70% of drivers being satisfied with electric vehicles. These findings show that today's electric vehicles can satisfy the daily driving needs of a significant majority of drivers using only 120 V wall outlets that are already the standard across the United States

Service scheduling in garden maintenance

Neoturf is a Portuguese company working in the area of project, building and garden’s maintenance. Neoturf would like to have a procedure for scheduling and routing efficiently the clients from garden maintenance services. The company has two teams available during the whole year and an additional team during summer to handle all the maintenance jobs. Each team consists of two or three employees with a vehicle fully equipped with the tools that allow to carry out every kind of maintenance service. In the beginning of each year, the number and frequency of maintenance interventions to conduct during the year, on each client, are accorded. Each client is assigned to the same team and, usually, time windows are established so that visits to the client should occur only within these periods. As the Neoturf costumers’ are geographically spread over a wide region, the total distance on visiting clients is a factor that has a heavy weight on the costs of the company. Neoturf is concerned with reducing these costs, while satisfying the agreements with the clients

Four dimensional R^4 superinvariants through gauge completion

We fully compute the N=1 supersymmetrization of the fourth power of the Weyl tensor in d=4 x-space with the auxiliary fields. In a previous paper, we showed that their elimination requires an infinite number of terms; we explicitely compute those terms to order \kappa^4 (three loop). We also write, in superspace notation, all the possible N=1 actions, in four dimensions, that contain pure R^4 terms (with coupling constants). We explicitely write these actions in terms of the \theta components of the chiral density \epsilon and the supergravity superfields R, G_m, W_{ABC}. Using the method of gauge completion, we compute the necessary \theta components which allow us to write these actions in x-space. We discuss under which circumstances can these extra R^4 correction terms be reabsorbed in the pure supergravity action, and their relevance to the quantum supergravity/string theory effective actions.Comment: 20 pages, no figures. Sec. 3 clarified; typos correcte

Effects of industrial heat treatments on the kinetics of inactivation of antimicrobial bovine milk xanthine oxidase.

Milk is a source of antimicrobial systems such as xanthine oxidoreductase, which has been proposed to modulate the oral and gut microbiota of infants. Heat treatments are applied to milk to ensure its microbial safety, however, the effects of heat on this antimicrobial enzyme are not known. The effects of batch pasteurization (BP), high-temperature short time (HTST), and ultra high temperature (UHT) on kinetics of inactivation of xanthine oxidase and its antimicrobial properties were determined. Xanthine oxidase activity was preserved by HTST (100%). Partial (8%) and nearly complete (95%) enzyme inactivation were observed for BP and UHT milks, respectively. K m values of 100 μM and V max values of 6.85, 5.12, 6.31, and 0.40 μmol/min/mg were determined for xanthine oxidase in raw, BP, HTST, and UHT milks, respectively. These results demonstrate that xanthine oxidase maintains apparent affinity and activity for its substrate when milk is treated by BP and HTST and yet the enzyme is inactivated with UHT. To investigate heat treatment-induced alterations in the biological activity of xanthine oxidase, heat treated milks were compared to raw milk for their ability to inhibit the growth of S. aureus. Raw, BP, and HTST milk xanthine oxidase efficiently inhibited S. aureus growth. However, these antibacterial properties were lost when milk was subjected to UHT. These results demonstrate that HTST and BP preserves bovine milk xanthine oxidase activity compared with UHT and that, the judicious selection of thermal treatments could be exploited to preserve the antimicrobial properties of bovine milk

Decentralized workload adaptive control plane for edge software-defined networked systems

There is a recent increasing interest on novel Software Defined Net-working (SDN) solutions for controlling edge networked systems. During the daily-basis operation of these systems some unexpected high and varied number of novel flows, trying to use the edge systems resources, could arise at the control system level to be efficiently handled. For this, the current work designs, deploys, and evaluates a new decentralized and online solution that orchestrates a variable number of SDN controllers, following the workload dynamics on the control channel protocol. The orchestration protocol is based on group communication over UDP. Our results show the merits of the proposed online decentralized de-sign on correctly adjusting the number of active controllers to the time-based load variations induced by new data flows traversing the edge networked system.info:eu-repo/semantics/publishedVersio