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31.
This study examined the effect of active pre-warming on speed and quality of performance during simulated firefighting exercise. Twelve male firefighters performed two trials in counterbalanced order. They were either pre-warmed by 20-min cycling at 1.5 Watt kg−1 body mass (WARM) or remained thermoneutral (CON) prior to a simulated firefighting activity. After the pre-warming, gastrointestinal temperature (P < 0.001), skin temperature (P = 0.002), and heart rate (P < 0.001) were higher in WARM than in CON. During the firefighting activity, rating of perceived exertion, thermal sensation and discomfort were higher for WARM than for CON. Finish time of the firefighting activity was similar, but the last task of the activity was completed slower in WARM than in CON (P = 0.04). In WARM, self-reported performance quality was lower than in CON (P = 0.04). It is concluded that pre-warming reduces the speed during the last part of simulated firefighting activity and reduces self-reported quality of performance. 相似文献
32.
Carl Yuheng Ren Victor Prisacariu Ian Reid 《International Journal of Computer Vision》2014,106(3):269-281
We propose a novel regression based framework that uses online learned shape information to reconstruct occluded object contours. Our key insight is to regress the global, coarse, properties of shape from its local properties, i.e. its details. We do this by representing shapes using their 2D discrete cosine transforms and by regressing low frequency from high frequency harmonics. We learn this regression model using Locally Weighted Projection Regression which expedites online, incremental learning. After sufficient observation of a set of unoccluded shapes, the learned model can detect occlusion and recover the full shapes from the occluded ones. We demonstrate the ideas using a level-set based tracking system that provides shape and pose, however, the framework could be embedded in any segmentation-based tracking system. Our experiments demonstrate the efficacy of the method on a variety of objects using both real data and artificial data. 相似文献
33.
Robert P. Kusy James M. Stuart John Q. Whitley Carl R. Saunders 《Journal of the American Ceramic Society》1993,76(2):299-304
Using laser specular reflectance, the optical rms roughnesses (σ0 'S) of 42 polycrystalline aluminas (PCA's) were determined. From these conventional experimental results, a nomogram was constructed so that single grazing angle (α) measurements could be used to predict σ0 . Subsequently, the nomogram was reassessed using five commercially important PCA's and one single-crystal sapphire (SC). The outcomes were twofold: that this nomogram was valid for PCA's over the range of 0.28 σ0 0.10 μm, but that the nomogram was invalid for SC sapphire. When the conventional experimental method was compared with the nomogram method at three different single-angle values, a 1:1 correspondence was observed for α= 78°, 80°, and 82°. The present noncontact method is advocated for speed and cleanliness, particularly when a quality assurance method is desired. 相似文献
34.
The objective of this research was to study the morphology and properties of PVC–polyurethane blends. Studies on blends of a segmented polyether polyurethane with PVC were carried out utilizing differential scanning calorimetry, Rheovibron, stress–strain, infrared peak position studies, and infrared dichroism experiments. This thermodynamically incompatible system was made kinetically compatible by precipitation from tetrahydrofuran (THF) solutions. THF–dioxane solution casting and melt processing produced an incompatible system. The compatible polyurethane–PVC system contains a well-mixed PVC–polyether matrix phase as evidenced by Tg shifts, orientation characteristics, and infrared peak position changes. The aromatic urethane segments which exhibit microphase separation in the pure polyurethane are not solubilized by blending with PVC by any of sample preparation methods used in this study. 相似文献
35.
Carl C. Gryte Christopher Koroneos Anil Agarwal Arie Hochberg 《Polymer Engineering and Science》1980,20(7):478-484
Graft copolymers were prepared by irradiation of poly(oxyethylene), PEO, aqueous solutions in presence of acrylic acid. Chain transfer to PEO controls the graft length, the measured chain transfer constant of the acrylic acid radicals to PEO being 4.11 × 10?4 at 25°C. The drag reduction characteristics of the graft copolymers were measured in the Reynolds number range 104–105 in a smooth-walled tube, 0.635 cm inside diameter. The drag reduction falls to near zero as the solution pH is lowered to 3, evidence of the formation of a PEO-poly(acrylic acid) coacervate. 相似文献
36.
Aronson Carl Lawrence Beloskur Douglas Frampton Isaac S. McKie Justin Montbriand Paul 《Polymer Bulletin》2004,52(6):409-419
Summary Functionalization of both linear poly(4-hydroxystyrene) (PHS) and branched poly(4-hydroxystyrene) (PHS-B) was accomplished via a Reimer-Tiemann electrophilic aromatic substitution reaction. Linear and branched poly(4-hydroxystyrene-co-5-vinylsalicylaldehyde) (pHS/5VSA and pHS-B/5VSA) copolymers were observed to undergo acid-catalyzed, novolac type self-crosslinking. Both the pHS/5VSA and pHS-B/5VSA copolymer systems possessed a lower deep ultra violet microlithographic sensitivity compared to linear PHS when formulated in negative photoresists. The sluggishness of the negative photoresists containing 5-vinylsalicylaldehyde functionalized copolymers was attributed to a combination of resonance stabilization and steric hindrance effects. 相似文献
37.
Summary A procedure is described by which bound or inactivated gossypol can be removed from cottonseed meal without the application
of heat which might damage the protein. The removal of bound gossypol increased the nutritional value of the protein as determined
by chick feeding tests, rat protein-repletion tests, and lysine availability tests. A procedure is described for the preparation
of a gossypol-cottonseed protein complex without heating the materials. As a result of the combination of the protein with
gossypol, marked reduction in nutritional value occurred. The nitrogen solubility of the complex was only about half that
of the original protein. The results are in accord with the concept that the inactivation of gossypol during the processing
of cottonseed meal is accomplished through the formation of an insoluble, inert gossypol-protein complex which results not
only in rendering the gossypol harmless but also in the loss of part of the nutritional value of the protein. 相似文献
38.
Nisha Sheth Carl Greenley Raul Bermejo John C. Mauro Carlo G. Pantano Seong H. Kim 《Journal of the American Ceramic Society》2021,104(9):4550-4558
Water or acid soaking surface treatments have been shown to increase the mechanical strength of soda-lime silicate (SLS) glasses. This increase in strength has traditionally been attributed to effects related to residual stress or changes in fracture resistance. In this work, we report experimental data that cannot be explained based on the existing knowledge of glass surface mechanics. In dry environments, annealed and acid-leached SLS surfaces have comparable crack initiation stress and fracture stress as measured by Hertzian indentation and biaxial bending tests, respectively. Yet, in the presence of humidity, acid-leached surfaces have higher failure stress than the annealed surfaces. This apparent enhancement in the crack resistance of the acid-leached surface of SLS glass in humid environments supports the hypothesis that acid-leached surface chemistry can lower the transport kinetics of molecular water to critical flaws. 相似文献
39.
Mollie B. Schear Arianna Neal Jadah S. Clarke Andrew P. Saab Carl B. Giller Riccardo Casalini Matthew Laskoski 《应用聚合物科学杂志》2021,138(12):50053
The preparation of highly aromatic elastomers from a bisphenol A-based divinyl-terminated resin and polymerization with various aromatic silane containing compounds utilizing a room temperature hydrosilylation reaction is demonstrated. The polymers exhibit high thermal and oxidative stability with 5% weight losses around 430 and 350°C and char yields ranging from 35% to 40%. The thermosets maintained their elastomeric properties with good hardness and mechanical properties as measured by elongation measurements. The toughness of the thermosets was not improved with the inclusion of aromatic moieties but the hardness did appear to increase with the addition of more aromatic groups. 相似文献
40.
The evolution of the profile of nanometer sized water drops on a mica surface has been studied through hydration scanning probe microscopy. A time range from a few seconds down to a fraction of millisecond after the formation of the drop has been explored. This high time resolution has been obtained by sampling a series of statistically equivalent drops. This approach also avoids any probe interference during the drop evolution process. 相似文献