Progressive velocity

This approach involves the measurement of the distribution of swimming distances made by the spermatozoa in various chambers, such as curved microchannels in microchips [87] or cervical mucus-fiUed capillaries [3, 82, 106]. The swimming distances are a measure of the progressive velocity and the percent motile cells in the sperm population. 

This approach involves determination of the extent to which spermatozoa can migrate through a membrane (e.g., a Nucleopore membrane with 5 xm pore size). This extent correlates primarily with the fraction of fast and straight-swimming cells in the sperm sample and with the sperm progressive velocity [68]. 

As m increases, At becomes progressively smaller (compare the difference between the square roots of 1 and 2 (= 0.4) with the difference between 100 and 101 (= 0.05). Thus, the difference in arrival times of ions arriving at the detector become increasingly smaller and more difficult to differentiate as mass increases. This inherent problem is a severe restriction even without the second difficulty, which is that not all ions of any one given m/z value reach the same velocity after acceleration nor are they all formed at exactly the same point in the ion source. Therefore, even for any one m/z value, ions at each m/z reach the detector over an interval of time instead of all at one time. Clearly, where separation of flight times is very short, as with TOF instruments, the spread for individual ion m/z values means there will be overlap in arrival times between ions of closely similar m/z values. This effect (Figure 26.2) decreases available (theoretical) resolution, but it can be ameliorated by modifying the instrument to include a reflectron. 

Stable Detonation A detonation that progresses through a confined system without significant variadon of velocity and pressure character-isdcs. Eor atmospheric condidons, typical velocides range between 1600 and 2200 m/s for standard test mixtures and test procedures. 

Figure 9-62. Flooding data for structured packings as reported by Billet [109]. Numbers following packing type indicate specific surface area in m /m. Reproduced by pennis-sion of the American Institute of Chemical Engineers, Fair, J. R. and Bravo, J. L., Chemical Engineering Progress, V. 86, No. 1 (1990) p. 19 all rights reserved. Note, Uq = vapor velocity, meters/sec.

Figure 9-119. Values of equivalent air mass velocity. Reproduced by permission of the American Institute of Chemical Engineers, Kelly, N. W., and Swenson, L. K., Chemical Engineering Progress, V. 52, No. 7 (1956) p. 263 8tll rights reserved.

Figure 9-130. Atmospheric cooling tower water loss for various wind velocities. Used by permission of Plastics Technical Service, The Dow Chemical Co., Midland Mich, with data added from Fuller, A. L, et al. Chemical Engineering Progress, V. 53, No. 10 (1957) p. 501 all rights reserved.

Figure 10-42. It is important to understand the relationships among velocity, surface temperature, and fouling resistance for a given exchanger. (Used by permission Knudsen, J. G., Chemical Engineering Progress. V. 87, No. 4, 1991. American Institute of Chemical Engineers. All rights reserved.)...

These velocities seem, at first, rather high compared to conventional pipework practice, but they are very localized in the exchanger and are progressively reduced as distribution into the flow passages occurs from the port manifold. 

Air inlet A suitable low-level inlet ventilation area must be provided for the expected airflow rate. Where personnel escape routes will be used for inlet, the inlet velocity must be low enough not to impede progress. 

In all tests, the temperature in the first- and second-stage reactors was kept within the necessary temperature limits of 288°-482°C. Because the carbon monoxide concentration was low in many of the tests, the second stage was not used to full capacity as is indicated by the temperature rise in runs 23, 24, and 27. The temperature profile shows the characteristic rise to a steady value. With the space velocities used (<5000 ft3/ft3 hr), the temperature profile is fully developed in the first stage within 30.0 in. of the top of the catalyst bed. A characteristic dip in temperature was observed over the first 8-10 in. of the catalyst bed in all runs. This temperature profile may indicate the presence of deactivated catalyst in this region, but, until the catalyst can be removed for examination, the cause of the temperature drop cannot be determined. There is no evidence that this low temperature zone is becoming progressively deeper. It is possible that an unrecorded brief upset in the purification system may have poisoned some of the top catalyst layers. 

Because the gas always flows at a velocity greater than that of the liquid, the in situ volumetric fraction of liquid at any point in a pipeline will be greater than the input volume fraction of liquid furthermore it will progressively change along the length of the pipe as a result of expansion of the gas. 

Equation 5.2 is found to hold well for non-Newtonian shear-thinning suspensions as well, provided that the liquid flow is turbulent. However, for laminar flow of the liquid, equation 5.2 considerably overpredicts the liquid hold-up e/,. The extent of overprediction increases as the degree of shear-thinning increases and as the liquid Reynolds number becomes progressively less. A modified parameter X has therefore been defined 16 171 for a power-law fluid (Chapter 3) in such a way that it reduces to X both at the superficial velocity uL equal to the transitional velocity (m )f from streamline to turbulent flow and when the liquid exhibits Newtonian properties. The parameter X is defined by the relation... 

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