Search results for "Speed"
showing 10 items of 876 documents
Cohort Differences in Maximal Physical Performance: A Comparison of 75- and 80-Year-Old Men and Women Born 28 Years Apart
2020
Abstract Background Whether increased life expectancy is accompanied by increased functional capacity in older people at specific ages is unclear. We compared similar validated measures of maximal physical performance in 2 population-based older cohorts born and assessed 28 years apart. Method Participants in the first cohort were born in 1910 and 1914 and were assessed at age 75 and 80 years, respectively (N = 500, participation rate 77%). Participants in the second cohort were born in 1938 or 1939 and 1942 or 1943 and were assessed at age 75 and 80 years, respectively (N = 726, participation rate 40%). Participants were recruited using a population register and all community-dwelling pers…
Speeding up new product development through entrepreneurial orientation in SMEs: The moderating role of ambidexterity
2022
International audience; This paper analyzes the influence of small and medium-sized enterprises' (SMEs) entrepreneurial orientation (EO) on its capacity to quickly introduce new products to the market (namely, speed to market). Specifically, we suggest that firms will exhibit greater speed to market when displaying either low or high levels of EO. We also suggest that the EO – speed to market relationship will be contingent on firms' ambidexterity, or its capacity to simultaneously embrace exploratory and exploitative strategies. To test our hypotheses, we collected survey data from 384 SMEs belonging to four sectors in Spain: biotechnology, ceramic tiles, toys and footwear. Our findings co…
Damping of rotor conical whirl by asymmetric dry friction suspension
2009
Abstract A new technique for the rotor whirl damping in rotating machinery, based on the elastic suspension of the journal boxes and the use of dry friction surfaces normal to the shaft axis between their supports and the frame, is here analysed theoretically for several cases of rotor systems characterized by mass and constraint asymmetry, where gyroscopic effects are to be expected and conical whirl motions may grow up. The critical flexural speeds can be easily cut off by an adhesive state of the supports and the whirl amplitude can be minimized as well throughout the remaining sliding range. Confining the operative angular speed of the rotor in the range of adhesive contact between the …
Comparison of the friction and wear properties of titanium and oxidised titanium in dry sliding against sintered high speed steel HS18-0-1 and agains…
2005
Abstract The paper presents the results of conformal pin-on-disc tribological tests concerning the hard oxidised zone, α-Ti(O), created at the surface of a titanium specimens sliding against the sintered and hardened up to 850 HV30, Grade T1 high speed steel (HS18-0-1) counterspecimens. Comparison with the results obtained for the tests performed against hardened up to 620 HV30 C45 carbon steel counterspecimens has been done. Testing was carried out at room temperature and at unlubricated conditions. After tests the structures and compositions of the worn surfaces and wear debris were a subject of LOM, SEM observations and X-ray microanalyses. In comparison with the baseline—the Ti/T1 HSS c…
Effect of cavity preparation instruments (oscillating or rotating) on the composite-dentin interface in primary teeth.
2003
Abstract Objectives: To evaluate the effect of preparation of instruments on the interfacial integrity between cavity wall and composite restoration. Methods: Two class II slot preparations were done in 10 primary teeth either with SonicSys® or with a conventional bur. The cavities were filled using an adhesive system. One layer of a flowable composite and one layer of a condensable composite were applied. The specimens were analyzed by confocal laser scanning microscopy. Results: In the SonicSys® group the mean thickness of the hybrid layer was 6.12 (0.60) μm; in the control group it was 6.04 (0.63) μm. The difference was not statistically significant. Two fractures were observed in one to…
Enhanced Debye level in nano Zn1+xSb, FeSb2, and NiSb: Nuclear inelastic spectroscopy on121Sb
2014
The121 Sb partial density of phonon states (DPS) in nanopowder antimonides were obtained with nuclear inelastic scattering on , , and NiSb prepared by a wet chemistry route. The DPS is compared with the bulk counterpart. An increase of the Debye level indicative of a decrease of the isothermal speed of sound is systematically observed. This observation reveals that the decrease in speed of sound observed in nanostructured thermoelectric materials is not restricted to sintered nanocomposites.
Friction stir welding of lap joints: Influence of process parameters on the metallurgical and mechanical properties
2009
Abstract Aluminum alloys are widely used in the aircraft industries even if such materials present lower ductility with respect to steels, anisotropy phenomena and, more important, they are often “difficult” to be welded or even “non-weldable”. In the last years the friction stir welding process (FSW) was proposed and applied in order to get good mechanical and technological performances of the joints. In this paper, an experimental and numerical investigation on the lap joining of AA2198-T4 aluminum alloy blanks by FSW is presented. In particular the joints strength and metallurgical properties are investigated by varying the joint configuration and the tool geometry and rotational speed. …
Assembly and Speed in Ion-Exchange-Based Modular Phoretic Microswimmers.
2017
We report an experimental study on ion-exchange-based modular microswimmers in low-salt water. Cationic ion-exchange particles and passive cargo particles assemble into self-propelling complexes, showing self-propulsion at speeds of several micrometers per second over extended distances and times. We quantify the assembly and speed of the complexes for different combinations of ion-exchange particles and cargo particles, substrate types, salt types and concentrations, and cell geometries. Irrespective of the experimental boundary conditions, we observe a regular development of the assembly shape with increasing number of cargo. Moreover, the swimming speed increases stepwise upon increasing…
Effect of the loading rate on ultimate strength of composites. Application: Pressure vessel slow burst test
2013
International audience; The strength of unidirectional elastic fibre composites is shown to depend on the loading rate as the viscoelastic nature of the matrix results in a fall in breaking load as the rate is reduced. The simulation of the accumulation of fibre breaks leading to failure, takes into account all physical phenomena involved fibre failure, including the stochastic nature of fibre strength, stress transfer through the matrix between reinforcements, interfacial debonding and the viscoelastic nature of the matrix. The kinetics of composite failure are seen to involve the initial formation of random fibre breaks which at higher loads coalesce into clusters of broken fibres. The ra…
Deep-Learning-Enabled Fast Optical Identification and Characterization of 2D Materials.
2020
© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Advanced microscopy and/or spectroscopy tools play indispensable roles in nanoscience and nanotechnology research, as they provide rich information about material processes and properties. However, the interpretation of imaging data heavily relies on the “intuition” of experienced researchers. As a result, many of the deep graphical features obtained through these tools are often unused because of difficulties in processing the data and finding the correlations. Such challenges can be well addressed by deep learning. In this work, the optical characterization of 2D materials is used as a case study, and a neural-network-based algorithm is de…