1,443 research outputs found
Impact of rod projectiles against multiple- sheet targets
Blunt hypervelocity projectile lift-drag ratio and impact velocity effects on target penetration and impact damag
Methods for Rapid Estimation of Motor Input Power in HVAC Assessments
In preliminary building energy assessments, it is often desired to estimate a motor's input power. Motor power estimates in this context should be rapid, safe, and noninvasive. Existing methods for motor input power estimation, such as direct measurement (wattmeter), Current Method, and Slip Method were evaluated. If installed equipment displays input power or average current, then using such readings are preferred. If installed equipment does not display input power or current, the application of wattmeters or current clamps is too time-consuming and invasive for the preliminary energy audit. In that case, if a shaft speed measurement is readily available, then the Slip Method is a satisfactory method for estimating motor input power.
An analysis of performance data for 459 motors suggests comparable performance for predicting normalized (to the nominal motor input power) motor input power with the Current and Slip Methods: 10.0% and 9.9% RMSE, respectively. Both of these methods may be improved by applying regression on the predicted variable and/or nameplate parameters. For example, the Slip Method could be improved by applying a second-order regression, thereby reducing the predicted load factor residual RMSE of the data set from 9.0% to 8.2%. The Current and Slip Methods were also evaluated on two real motors. The normalized (to the nominal motor input power) predicted input power RMSE for the Current Method was on average 15% for the two motors; for the Slip Method the corresponding average was 17.5%.
In some cases, shaft speed measurements may not be available. A temperature-based approach for estimating motor input power was investigated. Other required parameters include ambient temperature, motor efficiency, and a motor thermal constant. The temperature approach offers quick, safe, and non-invasive motor power estimation. However, thermal coefficients may vary significantly across motors and a model to predict the thermal coefficients has yet to be developed. Furthermore, the temperature approach has a very strong dependence on motor efficiency uncertainty. Experiments were performed on two motors to determine their motor thermal constants. If a motor's thermal constants and running efficiency are known, then this method gave motor input power estimates with a RMSE (normalized to the nominal input power) on the order of 4% for the studied motors
(Un)Structuring for the Next Generation: New Possibilities for Library Data with NoSQL
For many years, libraries have relied upon relational databases (RDBMS) to store, manipulate, and query various types of data, and this database model works extremely well when data are highly structured. As the data become more complex, however, the relational database model strains under the burden of maintaining complex joins, which can decrease a database\u27s performance and limit its functionality. Furthermore, data are not always best represented in the RDBMS\u27s flat, tabular format. Library data often require flexibility and extensibility to accommodate the increasing volume and variety of library resources and metadata. To address these issues, transforming the underlying structure of data will be as important as transforming the data itself. NoSQL offers an alternative model for efficiently managing dynamic data
Superior Episodic Memory Is Associated With Interhemispheric Processing
The dependence of episodic memories on interhemispheric processing was tested. In Experiment 1, positive familial sinistrality (FS+; e.g., the presence of left-handed relatives) was associated with superior episodic memory and inferior implicit memory in comparison with negative familial sinistrality (i.e., FS-). This reflected a greater degree of interhemispheric interaction in FS+ participants, which was hypothesized as facilitating episodic memory. In Experiment 2, the authors directly manipulated inter- versus intrahemispheric processing using tests of episodic (recognition) and semantic (lexical decision) memory in which letter strings were presented twice within trial blocks. Semantic memory was superior when the 2nd presentation went to the same hemisphere as the 1st. Episodic memory, however, was superior when the 2nd presentation of a stimulus went to the opposite hemisphere. Results support an interhemispheric processing basis for episodic memories
Assessment Of An Engineering Technology Outreach Program For 4th-7th Grade Girls
This paper describes a workshop led by female Engineering Technology students, with support from female faculty, to provide an introduction to Engineering Technology to 4th – 7th grade girls through a series of interactive laboratory experiments. This outreach program was developed to improve attitudes towards science and engineering in middle school-aged girls by making science tangible and fun. The workshop takes place on a college campus and makes use of four different Engineering Technology laboratories. Each lab activity includes a hands-on experiment, beginning with an overview of the engineering technology discipline and a brief description of the theories related to the experiment. The day culminates with a panel session between the participants and the college students. An ancillary outcome of the program is that it serves as a community building event for female Engineering Technology college students. Connections are developed between the students and between students and faculty in the college. The college students gain the satisfaction of influencing the attitudes of participants and develop critical communication skills. An attitude survey given to participants before and after the workshop shows that participation in these workshops results in a more positive attitude towards science and technology. College student volunteers were also surveyed after the workshop to determine the impact of their participation. A full workshop description is given in this paper as well as analysis of the assessment results for the participants and the college students.
Reaction products of aquatic humic substances with chlorine.
A major concern of the chlorination of aquatic humic materials is the ubiquitous production of trihalomethanes. A large number of other chlorinated organic compounds, however, have been shown to be formed by chlorine's reaction with humic substances. In this study, humic material was concentrated from a coastal North Carolina lake and chlorinated at a chlorine to carbon mole ratio of 1.5 at pH 12. A high pH was necessary for complete dissolution of the humic material and for production of adequate quantities of oxidation and chlorination products for extraction, separation and mass spectrometric identification. After concentration in ether, samples were methylated, separated with a 50-m OV-17 glass capillary column or a 25 m SP-2100 fused-silica column and identified. A Hewlett-Packard 5710A gas chromatograph interfaced to a VG Micromass 7070F double-focusing mass spectrometer was used. Low resolution, accurate mass measurements were made with a combined EI-Cl source. The ability to do low resolution, accurate mass measurements made possible a rapid scan function necessary for capillary column gas chromatography. Accurate mass measurements allowed increased confidence in the identification of compounds, most of which are not available as standards. The products identified in these studies were chlorinated aliphatic straight-chain acids dominated by di- and trichloroacetic acid and the chlorinated dicarboxylic acids: succinic, fumaric and maleic acids. Chlorinated and unchlorinated aliphatic mono- and dicarboxylic acids and unchlorinated polycarboxylic aromatic acids comprise the remaining bulk of the compounds identified
Gene expression in the deep biosphere
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 499 (2013): 205-208, doi:10.1038/nature12230.Scientific ocean drilling has revealed a deep biosphere of widespread microbial life in sub-seafloor sediment. Microbial metabolism in the marine subsurface likely plays an
important role in global biogeochemical cycles1-3 but deep biosphere activities are not well
understood1. Here, we describe and analyze the first subseafloor metatranscriptomes from
anaerobic Peru Margin sediment up to 159 meters below seafloor (mbsf) represented by
over 1 billion cDNA sequence reads. Anaerobic metabolism of amino acids, carbohydrates,
and lipids appear to be dominant metabolic processes, and profiles of dissimilatory sulfite
reductase (Dsr) transcripts are consistent with porewater sulfate concentration profiles1.
Moreover, transcripts involved in cell division increase as a function of microbial cell
concentration, indicating that increases in subseafloor microbial abundance are a function of cell division across all three domains of life. These data support calculations1 and
models4 of subseafloor microbial metabolism and represent the first holistic picture of deep
biosphere activities.This work was fostered by a Center for Dark Energy Biosphere
Investigations (CDEBI) grant OCE-0939564 to WO and a NSF IOS grant 1238801 to JFB.2013-12-1
Overcoming challenges: Going mobile with your own video models.
This is the publisher's version, also found here: http://cec.metapress.com/content/xtv27p4270444543/?p=368d1858244d4b8d957b1ecaf7e99f37&pi=
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