149 research outputs found

    The effects of variable practice and subjective estimation on error-detection capabilities

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    Retention and transfer for ballistic open motor skills may best be achieved through specific + variable practice along with error estimation. Inconsistent support for the variability of practice hypothesis warrants a cross-testing of this hypothesis. Estimation had been used and found beneficial on ballistic closed motor skills, but what about ballistic open motor skills? This study tests ballistic open motor skills on an anticipation timer. Specific and specific + variable practice groups coupled estimation and no-estimation conditions for testing purposes. The results indicated that although there were no significant differences during acquisition, significant differences did exist for retention and transfer in support of the variability of practice hypothesis. In conclusion, no particular practice condition aided learning during acquisition. Specific practice was more beneficial for retention, which did not support S+V-enhancing retention. And finally, estimation and S+V practice benefited transfer, which supports the variable of practice hypothesis

    Vehicle conversion to hybrid gasoline/alternative fuel operation

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    The alternative fuels considered are compressed natural gas (CNG), liquefied natural gas (LNG), liquid petroleum gas (LPG), and methanol; vehicles were required to operate in a hybrid or dual-fuel gasoline/alternative fuel mode. Economic feasibility was determined by comparing the costs of continued use of gasoline fuel with the use of alternative fuel and retrofitted equipment. Differences in the amounts of future expenditures are adjusted by means of a total life-cycle costing. All fuels studied are technically feasible to allow a retrofit conversion to hybrid gasoline/alternative fuel operation except for methanol. Conversion to LPG is not recommended for vehicles with more than 100,000 km (60,000 miles) of prior use. Methanol conversion is not recommended for vehicles with more than 50,00 km (30,000 miles)

    A preliminary systems-engineering study of an advanced nuclear-electrolytic hydrogen-production facility

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    An advanced nuclear-electrolytic hydrogen-production facility concept was synthesized at a conceptual level with the objective of minimizing estimated hydrogen-production costs. The concept is a closely-integrated, fully-dedicated (only hydrogen energy is produced) system whose components and subsystems are predicted on ''1985 technology.'' The principal components are: (1) a high-temperature gas-cooled reactor (HTGR) operating a helium-Brayton/ammonia-Rankine binary cycle with a helium reactor-core exit temperature of 980 C, (2) acyclic d-c generators, (3) high-pressure, high-current-density electrolyzers based on solid-polymer electrolyte technology. Based on an assumed 3,000 MWt HTGR the facility is capable of producing 8.7 million std cu m/day of hydrogen at pipeline conditions, 6,900 kPa. Coproduct oxygen is also available at pipeline conditions at one-half this volume. It has further been shown that the incorporation of advanced technology provides an overall efficiency of about 43 percent, as compared with 25 percent for a contemporary nuclear-electric plant powering close-coupled contemporary industrial electrolyzers

    Miniature High-Force, Long-Stroke SMA Linear Actuators

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    Improved long-stroke shape-memory-alloy (SMA) linear actuators are being developed to exert significantly higher forces and operate at higher activation temperatures than do prior SMA actuators. In these actuators, long linear strokes are achieved through the principle of displacement multiplication, according to which there are multiple stages, each intermediate stage being connected by straight SMA wire segments to the next stage so that relative motions of stages are additive toward the final stage, which is the output stage. Prior SMA actuators typically include polymer housings or shells, steel or aluminum stages, and polymer pads between successive stages of displacement-multiplication assemblies. Typical output forces of prior SMA actuators range from 10 to 20 N, and typical strokes range from 0.5 to 1.5 cm. An important disadvantage of prior SMA wire actuators is relatively low cycle speed, which is related to actuation temperature as follows: The SMA wires in prior SMA actuators are typically made of a durable nickel/titanium alloy that has a shape-memory activation temperature of 80 C. An SMA wire can be heated quickly from below to above its activation temperature to obtain a stroke in one direction, but must then be allowed to cool to somewhat below its activation temperature (typically, less than or equal to 60 C in the case of an activation temperature of 80 C) to obtain a stroke in the opposite direction (return stroke). At typical ambient temperatures, cooling times are of the order of several seconds. Cooling times thus limit cycle speeds. Wires made of SMA alloys having significantly higher activation temperatures [denoted ultra-high-temperature (UHT) SMA alloys] cool to the required lower return-stroke temperatures more rapidly, making it possible to increase cycle speeds. The present development is motivated by a need, in some applications (especially aeronautical and space-flight applications) for SMA actuators that exert higher forces, operate at greater cycle speeds, and have stronger housings that can withstand greater externally applied forces and impacts. The main novel features of the improved SMA actuators are the following: 1) The ends of the wires are anchored in compact crimps made from short steel tubes. Each wire end is inserted in a tube, the tube is flattened between planar jaws to make the tube grip the wire, the tube is compressed to a slight U-cross-section deformation to strengthen the grip, then the crimp is welded onto one of the actuator stages. The pull strength of a typical crimp is about 125 N -- comparable to the strength of the SMA wire and greater than the typical pull strengths of wire-end anchors in prior SMA actuators. Greater pull strength is one of the keys to achievement of higher actuation force; 2) For greater strength and resistance to impacts, housings are milled from aluminum instead of being made from polymers. Each housing is made from two pieces in a clamshell configuration. The pieces are anodized to reduce sliding friction; 3) Stages are made stronger (to bear greater compression loads without excessive flexing) by making them from steel sheets thicker than those used in prior SMA actuators. The stages contain recessed pockets to accommodate the crimps. Recessing the pockets helps to keep overall dimensions as small as possible; and, 4) UHT SMA wires are used to satisfy the higher-speed/higher-temperature requirement

    Connective tissue activation. XVII. Radioimmunoassay of a human platelet derived connective tissue activating peptide (CTAP-III) and specificities of anti-CTAP-III sera

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    The platelet-derived connective tissue activating peptide (CTAP-III) has been shown to be an important factor stimulating the metabolism and proliferation of human connective tissue cell strains, including synovial tissue cells. The quantities of CTAP-III affecting the cellular changes and the amounts in various biologic fluids and tissues are small. The objectives of this study were to develop a radioimmunoassay (RIA) for CTAP-III and to ascertain the specificities of the anti-CTAP-III sera reagents. The antisera were shown not to cross-react with a number of polypeptide hormones. However, two other platelet proteins, [beta]-thromboglobulin and low affinity platelet factor-4, competed equally as well as CTAP-III for anti-CTAP-III antibodies in the RIA system. Thus, the three platelet proteins are similar or identical with respect to those portions of the molecules constituting the reactive antigenic determinants. The levels of material in normal human platelet-free plasma that inhibited anti-CTAP-III-12S!-CTAP-III complex formation were determined to be 34 +/- 13 (S.D.) ng/ml.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23085/1/0000002.pd

    Provenance Metadata for Statistical Data: An Introduction to Structured Data Transformation Language (SDTL)

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    Structured Data Transformation Language (SDTL) provides structured, machine actionable representations of data transformation commands found in statistical analysis software. The Continuous Capture of Metadata for Statistical Data Project (C2Metadata) created SDTL as part of an automated system that captures provenance metadata from data transformation scripts and adds variable derivations to standard metadata files. SDTL also has potential for auditing scripts and for translating scripts between languages. SDTL is expressed in a set of JSON schemas, which are machine actionable and easily serialized to other formats. Statistical software languages have a number of special features that have been carried into SDTL. We explain how SDTL handles differences among statistical languages and complex operations, such as merging files and reshaping data tables from “wide” to “long”.National Science Foundation grant ACI-1640575https://deepblue.lib.umich.edu/bitstream/2027.42/156015/1/SDTL_Intro_v14.pdfDescription of SDTL_Intro_v14.pdf : Main articl

    Automating the Capture of Data Transformation Metadata from Statistical Analysis Software

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    The C2Metadata (“Continuous Capture of Metadata for Statistical Data”) Project automates one of the most burdensome aspects of documenting the provenance of research data: describing data transformations performed by statistical software. Researchers in many fields use statistical software (SPSS, Stata, SAS, R, Python) for data transformation and data management as well as analysis. The C2Metadata Project creates a metadata workflow paralleling the data management process by deriving provenance information from scripts used to manage and transform data. C2Metadata differs from most previous data provenance initiatives by documenting transformations at the variable level rather than describing a sequence of opaque programs. Scripts used with statistical software are translated into an independent Structured Data Transformation Language (SDTL), which serves as an intermediate language for describing data transformations. SDTL can be used to add variable-level provenance to data catalogs and codebooks and to create “variable lineages” for auditing software operations. Better data documentation makes research more transparent and expands the discovery and re-use of research data.National Science Foundation grant ACI-1640575https://deepblue.lib.umich.edu/bitstream/2027.42/156014/3/Automating_metadata_capture_v15.pd
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