26,446 research outputs found
Tool for installing or extracting small bulbs in limited-access spaces
Installing and extracting component of tool is plastic tubing with inside diameter which provides snug fit over bulb. Other components, which provide sturdiness and ease of operation, consist of metal tube, with collar near one end, and plunger, with knob on one end and Teflon tip on the other
Contemporary Seismicity in and Around the Yakima Fold-and-Thrust Belt in Eastern Washington
We examined characteristics of routinely cataloged seismicity from 1970 to the present in and around the Yakima fold-and-thrust belt (YFTB) in eastern Washington to determine if the characteristics of contemporary seismicity provide clues about regional-scale active tectonics or about more localized, near-surface processes. We employed new structural and hydrologic models of the Columbia River basalts (CRB) and found that one-third to one-half of the cataloged earthquakes occur within the CRB and that these CRB earthquakes exhibit significantly more clustered, and swarmlike, behavior than those outside. These results and inferences from published studies led us to hypothesize that clustered seismicity is likely associated with hydrologic changes in the CRB, which hosts the regional aquifer system. While some general features of the regional groundwater system support this hypothesis, seismicity patterns and mapped long-term changes in groundwater levels and present-day irrigation neither support nor refute it. Regional tectonic processes and crustal-scale structures likely influence the distribution of earthquakes both outside and within the CRB as well. We based this inference on qualitatively assessed alignments between the dominant northwest trends in the geologic structure and the seismicity generally and between specific faults and characteristics of the 2009 Wooded Island swarm and aseismic slip, which is the only cluster studied in detail and the most vigorous since regional monitoring began.USGS-NAGTGeological Science
Analysis techniques for residual acceleration data
Various aspects of residual acceleration data are of interest to low-gravity experimenters. Maximum and mean values and various other statistics can be obtained from data as collected in the time domain. Additional information may be obtained through manipulation of the data. Fourier analysis is discussed as a means of obtaining information about dominant frequency components of a given data window. Transformation of data into different coordinate axes is useful in the analysis of experiments with different orientations and can be achieved by the use of a transformation matrix. Application of such analysis techniques to residual acceleration data provides additional information than what is provided in a time history and increases the effectiveness of post-flight analysis of low-gravity experiments
Cyclopentadiene evolution during pyrolysis-gas chromatography of PMR polyimides
The effect of formulated molecular weight (FMW), extent of cure, and cumulative aging on the amount of cyclopentadiene (CPD) evolved from Polymerization of Monomeric Reactants (PMR) polyimides were investigated by pyrolysis-gas chromotography (PY-GC). The PMR polyimides are additional crosslinked resins formed from an aromatic diamine, a diester of an aromatic tetracarboxylic acid and a monoester of 5-norbornene-2, 3-dicarboxylic acid. The PY-GC results were related to the degree of crosslinking and to the thermo-oxidative stability (weight loss) of PMR polyimides. Thus, PY-GC has shown to be a valid technique for the characterization of PMR polyimide resins and composites via correlation of the CPD evolved versus the thermal history of the PMR sample
Exponential Smoothing for Inventory Control: Means and Variances of Lead-Time Demand
Exponential smoothing is often used to forecast lead-time demand for inventory control. In this paper, formulae are provided for calculating means and variances of lead-time demand for a wide variety of exponential smoothing methods. A feature of many of the formulae is that variances, as well as the means, depend on trends and seasonal effects. Thus, these formulae provide the opportunity to implement methods that ensure that safety stocks adjust to changes in trend or changes in season.Forecasting; inventory control; lead-time demand; exponential smoothing; forecast variance.
Monitoring Processes with Changing Variances
Statistical process control (SPC) has evolved beyond its classical applications in manufacturing to monitoring economic and social phenomena. This extension requires consideration of autocorrelated and possibly non-stationary time series. Less attention has been paid to the possibility that the variance of the process may also change over time. In this paper we use the innovations state space modeling framework to develop conditionally heteroscedastic models. We provide examples to show that the incorrect use of homoscedastic models may lead to erroneous decisions about the nature of the process. The framework is extended to include counts data, when we also introduce a new type of chart, the P-value chart, to accommodate the changes in distributional form from one period to the next.Control charts, count data, GARCH, heteroscedasticity, innovations, state space, statistical process control
Interplay between geometry and flow distribution in an airway tree
Uniform fluid flow distribution in a symmetric volume can be realized through
a symmetric branched tree. It is shown here, however, that the flow
partitioning can be highly sensitive to deviations from exact symmetry if
inertial effects are present. This is found by direct numerical simulation of
the Navier-Stokes equations in a 3D tree geometry. The flow asymmetry is
quantified and found to depend on the Reynolds number. Moreover, for a given
Reynolds number, we show that the flow distribution depends on the aspect ratio
of the branching elements as well as their angular arrangement. Our results
indicate that physiological variability should be severely restricted in order
to ensure uniform fluid distribution in a tree. This study suggests that any
non-uniformity in the air flow distribution in human lungs should be influenced
by the respiratory conditions, rest or hard exercise
Forecasting Compositional Time Series with Exponential Smoothing Methods
Compositional time series are formed from measurements of proportions that sum to one in each period of time. We might be interested in forecasting the proportion of home loans that have adjustable rates, the proportion of nonagricultural jobs in manufacturing, the proportion of a rock's geochemical composition that is a specific oxide, or the proportion of an election betting market choosing a particular candidate. A problem may involve many related time series of proportions. There could be several categories of nonagricultural jobs or several oxides in the geochemical composition of a rock that are of interest. In this paper we provide a statistical framework for forecasting these special kinds of time series. We build on the innovations state space framework underpinning the widely used methods of exponential smoothing. We couple this with a generalized logistic transformation to convert the measurements from the unit interval to the entire real line. The approach is illustrated with two applications: the proportion of new home loans in the U.S. that have adjustable rates; and four probabilities for specified candidates winning the 2008 democratic presidential nomination.compositional time series, innovations state space models, exponential smoothing, forecasting proportions
CAN-HK : An a priori crustal model for the Canadian Shield
ACKNOWLEDGMENTS The United Kingdom component of the Hudson Bay Lithospheric Experiment (HuBLE) was supported by the Natural Environment Research Council (NERC) Grant Number NE/F007337/1, with financial and logistical support from the Geological Survey of Canada (GSC), Canada-Nunavut Geoscience Office (CNGO), SEIS-UK (the seismic node of NERC), and the First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. I. D. B. was funded by the Leverhulme Trust and acknowledges support through Grant Number RPG-2013- 332. The authors thank three anonymous reviewers for their constructive comments.Peer reviewedPublisher PD
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