Conservative and Free Stream Preserving Stabilized Finite Element Methods for Compressible Flow on Deforming Domains

This dissertation presents new fully-discrete methods for arbitrary Lagrangian-Eulerian (ALE) stabilized finite element methods for balance laws on moving and deforming domains. This work is primarily two new ALE methods with the desirable properties of preserving constant states and admitting a discrete balance law in the fully-discrete setting. Both methods rely on stabilized finite element spatial discretizations and are time-discretized with the method-of-lines approach. Before introducing our two new methods, we show that the second-order accurate generalized- &alpha; method on a uniform temporal mesh may be viewed as an implicit midpoint method on a shifted temporal mesh. With this insight, we demonstrate that the generalized-&alpha; time integration of a finite element spatial discretization of a balance law system results in a fully-discrete method admitting discrete balance laws. We rely on this alternative view of the generalized-&alpha; method to time-discretize our new ALE finite element spatial discretizations. Next, we introduce the two new fully-discrete ALE methods applied to general scalar balance laws. Then, their discrete constant state preserving and discrete balance law properties are dis- cussed and demonstrated with numerical examples. Finally, we extend the methods to systems of balance laws written in conservation and nonconservation variables and provide numerical tests of various complexity. In the first method, we achieve desired properties by applying the generalized-&alpha; time integration to the governing balance laws and the time evolution of the ALE Jacobian determinant. The added cost is transporting an ordinary differential equation in each element but produces an atypical dynamic conservation statement. The second method achieves the desired properties by introducing a multiscale decomposition to the mesh velocity field. In this case, we recover a more typical discrete balance law statement; however, the added cost is solving a Poisson equation at each time step. Both methods are simple modifications easily implemented into existing finite element codes.</p

Cost-minimized combinations of wind power, solar power and electrochemical storage, powering the grid up to 99.9% of the time

AbstractWe model many combinations of renewable electricity sources (inland wind, offshore wind, and photovoltaics) with electrochemical storage (batteries and fuel cells), incorporated into a large grid system (72 GW). The purpose is twofold: 1) although a single renewable generator at one site produces intermittent power, we seek combinations of diverse renewables at diverse sites, with storage, that are not intermittent and satisfy need a given fraction of hours. And 2) we seek minimal cost, calculating true cost of electricity without subsidies and with inclusion of external costs. Our model evaluated over 28 billion combinations of renewables and storage, each tested over 35,040 h (four years) of load and weather data. We find that the least cost solutions yield seemingly-excessive generation capacity—at times, almost three times the electricity needed to meet electrical load. This is because diverse renewable generation and the excess capacity together meet electric load with less storage, lowering total system cost. At 2030 technology costs and with excess electricity displacing natural gas, we find that the electric system can be powered 90%–99.9% of hours entirely on renewable electricity, at costs comparable to today's—but only if we optimize the mix of generation and storage technologies

Database resources of the National Center for Biotechnology Information

In addition to maintaining the GenBank® nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides analysis and retrieval resources for the data in GenBank and other biological data made available through the NCBI web site. NCBI resources include Entrez, the Entrez Programming Utilities, MyNCBI, PubMed, PubMed Central, Entrez Gene, the NCBI Taxonomy Browser, BLAST, BLAST Link (BLink), Electronic PCR, OrfFinder, Spidey, Splign, Reference Sequence, UniGene, HomoloGene, ProtEST, dbMHC, dbSNP, Cancer Chromosomes, Entrez Genomes and related tools, the Map Viewer, Model Maker, Evidence Viewer, Trace Archive, Sequence Read Archive, Retroviral Genotyping Tools, HIV-1/Human Protein Interaction Database, Gene Expression Omnibus, Entrez Probe, GENSAT, Online Mendelian Inheritance in Man, Online Mendelian Inheritance in Animals, the Molecular Modeling Database, the Conserved Domain Database, the Conserved Domain Architecture Retrieval Tool, Biosystems, Peptidome, Protein Clusters and the PubChem suite of small molecule databases. Augmenting many of the web applications are custom implementations of the BLAST program optimized to search specialized data sets. All these resources can be accessed through the NCBI home page at www.ncbi.nlm.nih.gov