6,667 research outputs found

    Pulse shaping with birefringent crystals: a tool for quantum metrology

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    A method for time differentiation based on a Babinet-Soleil-Bravais compensator is introduced. The complex transfer function of the device is measured using polarization spectral interferometry. Time differentiation of both the pulse field and pulse envelope are demonstrated over a spectral width of about 100 THz with a measured overlap with the objective mode greater than 99.8%. This pulse shaping technique is shown to be perfectly suited to time metrology at the quantum limit

    Performance tests with a 4.75 inch bore tapered-roller bearings at high speeds

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    The tapered-roller bearings were tested at speeds to 15,000 rpm which results in a cone-rib tangential velocity of 130 m/sec. (25,500 ft/min). Lubrication was applied either by jets or directly to the cone-rib, augmented with jets. Additional test parameters included thrust loads to 53,400 N (12,000 lbs), radial loads to 26,700 N (6,000 lbs), lubricant flow rates from 1.9 x 0.000 to 15.1 x 0.001 cubic meter/min. (0.5 to 4.0 gpm), and lubricant inlet temperatures of 350 K and 364 K (170 F and 195 F). Temperature distribution, separator speed, and drive-motor power demand were determined as functions of these test parameters

    ANALYZING LINKAGES BETWEEN NURSERY FARM GROWTH RATES, STRUCTURAL VARIABLES, AND FIRM CHARACTERISTICS

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    Production of ornamental plants is one of agriculture's successes. However, concentration of production and retailing is occurring, bringing additional competitive pressure. An econometric model is used to explain growth rate using a cross-sectional data set from 2001, self-reported growth rates for nursery firms, and firm and operator characteristics.Production Economics,

    Validity of the Adiabatic Approximation

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    We analyze the validity of the adiabatic approximation, and in particular the reliability of what has been called the "standard criterion" for validity of this approximation. Recently, this criterion has been found to be insufficient. We will argue that the criterion is sufficient only when it agrees with the intuitive notion of slowness of evolution of the Hamiltonian. However, it can be insufficient in cases where the Hamiltonian varies rapidly but only by a small amount. We also emphasize the distinction between the adiabatic {\em theorem} and the adiabatic {\em approximation}, two quite different although closely related ideas.Comment: 4 pages, 1 figur

    Forensic podiatry: A new path for podiatrists?

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    Treball Final de Grau de Podologia, Escola Universitària d'Infermeria, Universitat de Barcelona, curs: 2014-2015, Tutor: Carles Vergès SalasForensic podiatrists are specialised podiatrists in the field of Legal Medicine and Forensic Sciences. With their expertise level of the functioning foot, they are able to help the department of criminology. Their scope is divided in four subspecialties, in which each scope plays a very important part. Podiatry treatment records, barefoot prints, footwear and gait patterns are the main roles that forensic podiatrists employ. Forensic podiatry does not exist all over the world. It started in U.S.A and U.K. Currently in Catalonia, Spain, this field of podiatry still does not exist in 2015, but whether or not this will change in the future is questionabl

    Real-time distance measurement immune from atmospheric parameters using optical frequency combs

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    We propose a direct and real-time ranging scheme using an optical frequency combs, able to compensate optically for index of refraction variations due to atmospheric parameters. This scheme could be useful for applications requiring stringent precision over a long distance in air, a situation where dispersion becomes the main limitation. The key ingredient is the use of a mode-locked laser as a precise source for multi-wavelength interferometry in a homodyne detection scheme. By shaping temporally the local oscillator, one can directly access the desired parameter (distance) while being insensitive to fluctuations induced by parameters of the environment such as pressure, temperature, humidity and CO2_2 content

    Endurance tests with large-bore tapered-roller bearings to 2.2 million DN

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    Endurance life tests were run with standard design and optimized high-speed design 120.65-mm-(4.750-in.-) bore tapered-roller bearings at shaft speeds of 12,500 and 18,500 rpm, respectively. Standard design bearings of vacuum melted AISI 4320 and CBS-1000M, and high-speed design bearings of CBS-1000M and through-hardened AISI M-50 were run under heavy combined radial and thrust load until fatigue failure or until a preset cutoff time of 1100 hours was reached. Standard design bearings made from CBS 1000M material ran to a 10 percent life approximately six times rated catalog life. Twelve identical bearings of AISI 4320 material ran to ten times rated catalog life without failure. Cracking and fracture of the cones of AISI M-50 high-speed design bearings occurred at 18,500 rpm due to high tensile hoop stresses. Four CBS 1000M high-speed design bearings ran to twenty-four times rated catalog life without any spalling, cracking or fracture failures

    Effect of two inner-ring oil-flow distribution schemes on the operating characteristics of a 35 millimeter bore ball bearing to 2.5 million DN

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    Parametric tests were conducted with a 35-mm-bore, split-inner-ring ball bearing with a double-inner-land-guided cage. Provisions were made for through-the-inner-ring lubrication. Test condictions were either a thrust load of 667 N (150 lb) or a combined load of 667 N (150 lb) thrust and 222 N (50 lb) radial, shaft speeds from 32000 to 72000 rpm, and an oil-inlet temperature of 394 K (250 deg F). Outer ring cooling was used in some tests. Tests were run with either 50 or 75 percent of the total oil flow distributed to the inner-ring raceway. Successful operation was experienced with both 50% and 75% flow patterns to 2.5 million DN. Cooling the outer ring had little effect on inner-ring temperature; however, the outer-ring temperature decreased as much as 7% at 2.5 million DN. Maximum recorded power loss was 3.1 kW (4.2 hp), and maximum cage slip was 8.7 percent. Both occurred at a shaft speed of 72000 rpm, a lubricant flow rate of 1900 cu/min (0.50 gal/min), a combined load, and no outer-ring cooling
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