996 research outputs found

    Plans for wind energy system simulation

    Get PDF
    A digital computer code and a special purpose hybrid computer, were introduced. The digital computer program, the Root Perturbation Method or RPM, is an implementation of the classic floquet procedure which circumvents numerical problems associated with the extraction of Floquet roots. The hybrid computer, the Wind Energy System Time domain simulator (WEST), yields real time loads and deformation information essential to design and system stability investigations

    Wind energy system time-domain (WEST) analyzers

    Get PDF
    A portable analyzer which simulates in real time the complex nonlinear dynamics of horizontal axis wind energy systems was constructed. Math models for an aeroelastic rotor featuring nonlinear aerodynamic and inertial terms were implemented with high speed digital controllers and analog calculation. This model was combined with other math models of elastic supports, control systems, a power train and gimballed rotor kinematics. A stroboscopic display system graphically depicting distributed blade loads, motion, and other aerodynamic functions on a cathode ray tube is included. Limited correlation efforts showed good comparison between the results of this analyzer and other sophisticated digital simulations. The digital simulation results were successfully correlated with test data

    Combinatorial and Algorithmic Aspects of Monadic Stability

    Get PDF
    Nowhere dense classes of graphs are classes of sparse graphs with rich structural and algorithmic properties, however, they fail to capture even simple classes of dense graphs. Monadically stable classes, originating from model theory, generalize nowhere dense classes and close them under transductions, i.e. transformations defined by colorings and simple first-order interpretations. In this work we aim to extend some combinatorial and algorithmic properties of nowhere dense classes to monadically stable classes of finite graphs. We prove the following results. - For every monadically stable class C and fixed integer s ? 3, the Ramsey numbers R_C(s,t) are bounded from above by ?(t^{s-1-?}) for some ? > 0, improving the bound R(s,t) ? ?(t^{s-1}/(log t)^{s-1}) known for the class of all graphs and the bounds known for k-stable graphs when s ? k. - For every monadically stable class C and every integer r, there exists ? > 0 such that every graph G ? C that contains an r-subdivision of the biclique K_{t,t} as a subgraph also contains K_{t^?,t^?} as a subgraph. This generalizes earlier results for nowhere dense graph classes. - We obtain a stronger regularity lemma for monadically stable classes of graphs. - Finally, we show that we can compute polynomial kernels for the independent set and dominating set problems in powers of nowhere dense classes. Formerly, only fixed-parameter tractable algorithms were known for these problems on powers of nowhere dense classes

    CC178 Revised 1985 Crop Varieties Suggested for Nebraska 1985

    Get PDF
    Campaign Circular 178 Revised 1985 Certified Crop Varieties Suggested for Nebraska 1985, talks about the variations of crops in Nebraska such as small grains, sorghums, soybeans, legumes, grasses, corn

    Bipolar spectrum disorders in a clinical sample of patients with Internet addiction: Hidden comorbidity or differential diagnosis?

    Get PDF
    Background and aims Behavioral addictions and bipolar disorders have a certain probability of co-occurrence. While the presence of a manic episode has been defined as an exclusion criterion for gambling disorder, no such exclusion has been formulated for Internet addiction. Methods A clinical sample of 368 treatment seekers presenting with excessive to addictive Internet use was screened for bipolar spectrum disorders using the Mood Disorder Questionnaire. Psychopathology was assessed by the Symptom Checklist 90R and a clinical interview was administered to screen for comorbid disorders. Results Comorbid bipolar disorders were more frequent in patients meeting criteria for Internet addiction (30.9%) than among the excessive users (5.6%). This subgroup showed heightened psychopathological symptoms, including substance use disorders, affective disorders and personality disorders. Further differences were found regarding frequency of Internet use regarding social networking sites and online-pornography. Discussion Patients with Internet addiction have a heightened probability for meeting criteria of bipolar disorders. It is not possible to draw conclusions regarding the direction of this association but it is recommended to implement screening for bipolar disorders in patients presenting with Internet addiction. Conclusion Similar to gambling disorder, it might prove necessary to subsume bipolar disorders as an exclusion criterion for the future criteria of Internet addiction

    Ubiquitin and AP180 Regulate the Abundance of GLR-1 Glutamate Receptors at Postsynaptic Elements in C. elegans

    Get PDF
    AbstractRegulated delivery and removal of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptors (GluRs) from postsynaptic elements has been proposed as a mechanism for regulating synaptic strength. Here we test the role of ubiquitin in regulating synapses that contain a C. elegans GluR, GLR-1. GLR-1 receptors were ubiquitinated in vivo. Mutations that decreased ubiquitination of GLR-1 increased the abundance of GLR-1 at synapses and altered locomotion behavior in a manner that is consistent with increased synaptic strength. By contrast, overexpression of ubiquitin decreased the abundance of GLR-1 at synapses and decreased the density of GLR-1-containing synapses, and these effects were prevented by mutations in the unc-11 gene, which encodes a clathrin adaptin protein (AP180). These results suggest that ubiquitination of GLR-1 receptors regulates synaptic strength and the formation or stability of GLR-1-containing synapses

    A Novel Algorithm for the Assessment of Blood-Brain Barrier Permeability Suggests That Brain Topical Application of Endothelin-1 Does Not Cause Early Opening of the Barrier in Rats

    Get PDF
    There are a number of different experimental methods for ex vivo assessment of blood-brain barrier (BBB) opening based on Evans blue dye extravasation. However, these methods require many different steps to prepare the brain and need special equipment for quantification. We here report a novel, simple, and fast semiquantitative algorithm to assess BBB integrity ex vivo. The method is particularly suitable for cranial window experiments, since it keeps the spatial information about where the BBB opened. We validated the algorithm using sham controls and the established model of brain topical application of the bile salt dehydrocholate for early BBB disruption. We then studied spreading depolarizations in the presence and the absence of the vasoconstrictor endothelin-1 and found no evidence of early BBB opening (three-hour time window). The algorithm can be used, for example, to assess BBB permeability ex vivo in combination with dynamic in vivo studies of BBB opening
    corecore