Search results for "Earing"
showing 10 items of 867 documents
Factors affecting peak impact force during soccer headers and implications for the mitigation of head injuries
2020
It has been documented that up to 22% of all soccer injuries are concussions. This is in part due to players purposely using their head to direct the ball during play. To provide a more complete understanding of head trauma in soccer athletes, this study characterized the effects of four soccer ball characteristics (size, inflation pressure, mass, velocity) on the resulting peak impact force as it relates to the potential for incurring neurophysiological changes. A total of six hundred trials were performed on size 4 and 5 soccer balls as well as a novel lightweight soccer ball. Impact force was measured with a force plate and ball velocity was determined using motion capture. These data we…
Synthesis and Catalytic Use of Polar Phosphinoferrocene Amidosulfonates Bearing Bulky Substituents at the Ferrocene Backbone
2021
International audience; Anionic phosphinoferrocene amidosulfonates bearing sterically demanding t-butyl substituents in positions 3 and 3' of the ferrocene scaffold, viz. rac-(Et3NH)[Fe(η5-tBuC5H3PR2)(η5-tBuC5H3C(O)NHCH2SO3)] (R = phenyl and cyclohexyl) were synthesized by amidation of the corresponding phosphinocarboxylic acids, [Fe(η5-tBuC5H3PR2)(η5-tBuC5H3CO2H)]. These ditopic polar phosphinoferrocenes and their non-t-butylated analogues have been used as lig-ands to prepare zwitterionic (η3-allyl)palladium(II) complexes [Pd(η3-C3H5){Fe(η5-R'C5H3PR2)(η5-R'C5H3C(O)NHCH2SO3)}] (R' = H, tBu, R = Ph, Cy). Depending on the isolation procedure and crystallization condi-tions, some complexes we…
X-Ray crystallographic and computational study on uranyl-salophen complexes bearing nitro groups.
2017
In the solid state, salophen–UO2 complexes bearing one, two, or three NO2 groups lack the pronounced ligand curvature that represents a structural hallmark for this class of compounds. A detailed structural study based on single-crystal X-ray crystallography and computational methods, comprising molecular dynamics, gas-phase Hartree Fock, and DFT calculations, was carried out to investigate the coordination properties of the uranyl cation.
Performance of Steel Fibrous Reinforced Concrete Corbels Subjected to Vertical and Horizontal Loads
2009
A softened strut-and-tie macromodel able to reproduce the flexural behavior of corbels in plain and fibrous concrete and with the presence of steel bars, including softening of compressed struts and yielding of main and secondary steel bars, is presented in this paper. The main focus of the proposed model is the determination of the load-deflection curves of corbels subjected to the coupled effects of vertical and horizontal forces bearing in mind the influence of the type of concrete (normal or high strength), of the fiber percentage and of the arrangement and percentage of the main and secondary (horizontal stirrup) steel bars. A validation of the proposed model is made therefore with ref…
Chiral/Achiral Copolymers of Biphenylylacetylenes Bearing Various Substituents: Chiral Amplification through Copolymerization, Followed by Enhancemen…
2020
A series of dynamic helical homo- and copolymers of chiral and/or achiral biphenylylacetylenes (PBPAs) bearing achiral methoxymethoxy or acetyloxy groups at the 2,2′-positions along with a chiral o...
Polymerized Ionic Liquids with Polythiophene Backbones: Self-Assembly, Thermal Properties, and Ion Conduction
2018
Single ion conductors, based on polymerized ionic liquids (PILs) with a polythiophene backbone bearing imidazolium salts with butyl, hexyl, octyl, and decyl side groups and six different counterani...
The Relevance of Kneading and Extrusion Parameters in the Manufacture of Active Porous Aluminas from Pseudoboehmites
1987
In order to study the effect-on crushing strength, attrition resistance, specific pore volume, and pore volume distribution of extrudates-of kneading and extrusion parameters in the manufacture of active porous aluminas, a commercial pseudoboehmite (Pural SB from Condea Chemie, Brunsbuttel, FRG) was employed. A minimum kneading torque was required to prepare an extrudable paste, predetermined by extrusion conditions. The torque had an upper limit with respect to certain extrudate properties. The amount of water and the concentration of nitric acid as binder solutions were found to have a decisive bearing on the mechanical properties and the distribution of the pore volume. Crushing strength…
The influence of the cycloid disc bearing type on the cycloidal speed reducer efficiency
2021
The robotics industry has experienced a rapid expansion in the last decade. As a result, the market of speed reducers with high gear ratios, high precision and a compact design is growing rapidly. In addition to these characteristics, it is very important for gear trains to have high efficiency. Because of their compact design, cycloidal speed reducers are not exposed to axial forces, which is their important characteristic. This means that radial bearings can be used in their supports. The bearing type has significant effects not only on the design and dimensions of the cycloid speed reducer but also on its efficiency. In this paper, an analysis of power losses for different types of rolli…
Influence of variability and uncertainty of wind and waves on fatigue damage of a floating wind turbine drivetrain
2021
Abstract This study investigates the effect of variability and uncertainty of wind and wave conditions on the short-term fatigue damage of a 10-MW floating wind turbine drivetrain. Global dynamic responses of a semi-submersible wind turbine are calculated by aero-hydro-servo-elastic simulations in various environmental conditions. Then, rotor and generator loads, as well as nacelle motions from the global analysis are provided to a drivetrain model to investigate its dynamics. One-hour fatigue damage of the drivetrain bearings is calculated based on the bearing loads and speeds, and the effect of uncertainties related to wind and waves is assessed. The results indicate that the variations o…
Acene-type donors bearing one 1,3-dithiole ring
1999
Abstract A series of acene-type donors bearing only one 1,3-dithiole ring have been synthesized by following a Wittig-Horner reaction from 7 H -benz[ d,e ]anthracen-7-one and several phosphonate esters. The excellent donor properties have been studied using both experimental techniques and quantum-chemical calculations and reveal that the extraction of the first electron in the oxidation process occurs from the dithiole ring (0.42 e) and the acene unit (0.58 e).