Effective mechanical power

Effective mechanical power The energy spent in overcoming external mechanical forces on the body, in W, normally ignored for most activity. 

Mucus gel is propelled toward the epiglottis by a two-phase ciliary beat cycle. Forward mucus movement occurs during the effective or power phase of the cycle, when cilia fully extend and traverse an arc perpendicular to the epithelial surface (Fig. 5.24). Claw-like structures, 25-35 nm long, project from each cilia tip and appear to assist in the mechanical transfer of momentum from cilia to mucus gel. Maximum mucus velocity depends on the extent cilia penetrate the epiphase during the power phase, periciliary and mucus gel viscosity, and cilia density. 

These types of inhibitors, which take advantage of the catalytic activity of a protease to trap and inhibit the enzyme, are effective and powerful inhibitors. As discussed in the following section, many small-molecule irreversible and protease-activated inhibitors have been developed that rely on the same fundamental mechanism of using enzyme activity to trap and inactivate a protease. 

Reconsider Prob. 6-41. Using EES (or other) software, investigate the effect of shaft velocity on the mechanical power wasted by viscous dissipation. Let the shaft rotation vary from 0 rpm to 5000 rpm. Plot the power wasted versus the shaft rpm, and discuss the results. 

Under the effect of viscosity, the fluid itself can be heated throughout the bulk. The importance of this effect can be appreciated with the help of the Brinkman number Br. It is the ratio between the mechanical power degraded in heat flow and the power transferred by conduction in the fluid. It is written as... 

In practice, pressure differences significantly greater than FI are used to effect osmotic separations. For example, seawater lias an osmotic pressure of about 25 bar, but working pressures of 50 to 80 bar are employed to enhance tlie rate of recoveiy of fresh water. A feature of such separations is tliat tliey require mechanical power only, for pumping the solution to an appropriate pressure level. Tliis contrasts with distillation schemes, where steam is tlie usual source of energy. A brief overview of reverse osmosis is given by Perry and Green.- ... 

Virtually all dentifrice formulations contain abrasive particles, typically composed of amorphous silica, calcium carbonate, alumina or calcium phosphate. The mechanism by which the toothbrush and dentifrice interact to clean the teeth is one of abrasive cleaning. Toothpaste manufacturers thus aim to provide formulations with effective cleaning power, whilst minimising any wear to the underlying substrate. However, in such a system it is inevitable that some degree of abrasivity will be present, as toothpastes without abrasive particles are unable to prevent the build-up of extrinsic stain [12], It is, therefore, important to understand any abrasion a dentifrice product may cause to the hard tissues in the mouth. 

A series of nine experiments was performed in the above manner, and nine experiments were made in order to eliminate the cooling or heating effects of the atmosphere. After reducing the result to the capacity for heat of a pound of water, it appeared that for each degree of heat evolved by the friction of water a mechanical power equal to that which can raise a weight of 8901b. to the height of one foot had been expended. 

The acoustic pressure can be measured through the effects produced in the propagation liquid, namely (1) heating, measured calorimetrically and (2) the action of radiation pressure, determined by measuring the force exerted on a surface (the radiometric method). While the former allows the measurement of the mechanical power of the vibrating source, the latter is associated with the acoustic power transmitted by the acoustic radiation. The acoustic pressure can also be determined using calibrated hydrophones (the acoustic method). 

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