Analytical determination of mesh phase relations in general compound planetary gears

This paper systematically studies the mesh phase relations of general compound planetary gears. The mesh phase relations are described by the relative phases between mesh tooth variation functions of all gear meshes. The analysis allows for compound planetary gears having multiple mesh periods. A numbering method is proposed for accurate definition of the relative phases in a general compound planetary gear. By introducing the concepts of system-level, stage-level, and train-level relative phases, the relative phases between any two gear meshes in a compound planetary gear are calculated systematically. Important relations among these relative phases are derived. The results from this study are necessary for analytical or computational multibody studies on the static or dynamic response of general compound planetary gears.     

Heuristic and probabilistic wind power availability estimation procedures: Improved tools for technology and site selection

The paper describes two investigative procedures to estimate wind power from measured wind velocities. Wind velocity data are manipulated to visualize the site potential by investigating the probable wind power availability and its capacity to meet a targeted demand. The first procedure is an availability procedure that looks at the wind characteristics and its probable energy capturing profile. This profile of wind enables the probable maximum operating wind velocity profile for a selected wind turbine design to be predicted. The structured procedures allow for a consequent adjustment, sorting and grouping of the measured wind velocity data taken at different time intervals and hub heights. The second procedure is the adequacy procedure that investigates the probable degree of availability and the application consequences. Both procedures are programmed using MathCAD symbolic mathematical software. The math tool is used to generate a visual interpolation of the data as well as numerical results from extensive data sets that exceed the capacity of conventional spreadsheet tools. Two sites located in Southern Ontario, Canada are investigated using the procedures. Successful implementation of the procedures supports informed decision making where a hill site is shown to have much higher wind potential than that measured at the local airport. The process is suitable for a wide spectrum of users who are considering the energy potential for either a grid-tied or off-grid wind energy system.     

Deuterons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ((2)H(+)) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder? 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by <3%. The greatest difference, 47%, occurred at 30 MeV.     

Analytical solutions for exposures and toxic loads in well-mixed shelters in support of shelter-in-place assessments

Understanding the exposure and toxic load for the interior of buildings during and following the passage of an external airborne hazard can be a critical piece of information in deciding the benefit from adopting a shelter-in-place strategy. Whilst numerical methods allow the calculation of such parameters for the general case, analytical solutions allow more rapid assessments to be made and highlight the key parameters more clearly. Analytical expressions are derived for the exposure due to the acute inhalation of toxic chemicals and the associated toxic load as a function of time, external hazard duration and building air change rate assuming a top-hat outdoor concentration profile and no indoor loss mechanism. It is shown that the internal exposure tends to the external exposure at long times for any external concentration profile. Expressions are derived for toxic loads with exponents n=m/2 where 2 ≤ m ≤ 7 is an integer to cover the range of typical values (1 ≤ n ≤ 3.5). At long times the ratio of internal to external toxic load for a top-hat outdoor concentration profile is shown to be a function of the product of the air change rate and the duration of the external hazard.     

Determination of friction coefficients, brush contact arcs and brush penetrations for gutter brush�Croad interaction through FEM

A 3-D, dynamic, non-linear Finite Element Model (FEM) involving contact is used to determine apparent coefficients of friction,???, for the interaction between the bristles of a flicking brush for street sweeping and concrete. Also, brush contact arcs, as well as suitable brush penetrations as functions of the debris height, are determined for cutting and F128 brushes. Available experimental results are used to determine the coefficients of friction. The bristles are modelled through beam elements, which are subjected to inertia forces. The results suggest that the model is valid and that the coefficient of friction affects the brush vertical force in the flicking brush, but it does not significantly affect its counterpart in the cutting brush. The results also indicate that the coefficient of friction for the flicking brush depends on the sliding velocity, v, and these were fitted to an exponential??? ? v curve.     

Decay of quantised vorticity by sound emission

No Heading It is thought that in a quantum fluid sound generation is the sink of turbulent kinetic energy in the absence of any other dissipation mechanism near absolute zero. We show that a suitably trapped Bose-Einstein condensate provides a model system to study the sound emitted by accelerating vortices in a controlled way.PACS numbers: 03.75.Lm, 47.32.Cc, 67.40.Vs.     

Egocentrism over e-mail: Can we communicate as well as we think?

Without the benefit of paralinguistic cues such as gesture, emphasis, and intonation, it can be difficult to convey emotion and tone over electronic mail (e-mail). Five experiments suggest that this limitation is often underappreciated, such that people tend to believe that they can communicate over e-mail more effectively than they actually can. Studies 4 and 5 further suggest that this overconfidence is born of egocentrism, the inherent difficulty of detaching oneself from one's own perspective when evaluating the perspective of someone else. Because e-mail communicators "hear" a statement differently depending on whether they intend to be, say, sarcastic or funny, it can be difficult to appreciate that their electronic audience may not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)