Cycles per minute

A/ci =Rotor 1st critical, center frequency, cycles per minute A/gn =Critical speed, nth =Thp speed... 

Nc, - Rotor 1st critical, center frequency. Cycles per minute AF = Amplification Factor... 

The data presented in Figure 19.7 were obtained on a Sonntag-Universal machine which flexes a beam in tension and compression. Whereas the acetal resin was subjected to stresses at 1800 cycles per minute at 75°F and at 100% RH, the nylons were cycled at only 1200 cycles per minute and had a moisture content of 2.5%. The polyethylene sample was also flexed at 1200 cycles per minute. Whilst the moisture content has not been found to be a significant factor it has been observed that the geometry of the test piece and, in particular, the presence of notches has a profound effect on the fatigue endurance limit. 

The pH of the medium thus prepared is about 6.8. An 8 ml portion Is measured into an 8 inch 8rewer tube and sterilized at 120°C for 20 minutes. The sterilized medium is than inoculated with 0.5 ml of an aqueous spore suspension of a strain of S. aureofaciens capable of producing chlorodemethyltetracycline, such as S-604, containing approximately 40-60 million spores per milliliter. The inoculated medium is incubated for 24 hours at 28°C on a reciprocating shaker operated at 110 cycles per minute. 

In addition, 1 mg of sterile S-2-hydroxyethyl-DL-homocysteine Is added to the tube and the tube is shaken on a rotary shaker at 280 cycles per minute at 25°C for seven days. 

The flasks are then placed on a reciprocating shaker (120 one and one-half inch cycles per minute) and mechanically shaken at 25°C for 3 days. The contents of the flasks are then pooled and, after the pH of the culture is adjusted to about 4 0.2 with sulfuric acid, filtered through Seitz filter pads to separate the mycelium from the fermented medium. 

From a practical standpoint, simple harmonic vibration functions are related to the circular frequencies of the rotating or moving components. Therefore, these frequencies are some multiple of the basic running speed of the machine-train, which is expressed in revolutions per minute (rpm) or cycles per minute (cpm). Determining these frequencies is the first basic step in analyzing the operating condition of the machine-train. 

Frequency is defined as the number of repetitions of a specific forcing function or vibration component over a specific unit of time. Take for example a four-spoke wheel with an accelerometer attached. Every time the shaft completes one rotation, each of the four spokes passes the accelerometer once, which is referred to as four cycles per revolution. Therefore, if the shaft rotates at 100 rpm, the frequency of the spokes passing the accelerometer is 400 cycles per minute (cpm). In addition to cpm, frequency is... 

The fatigue strength is defined as that stress level at which the test specimen will sustain N cycles prior to failure. The data are generated on a machine that runs at 1800 cycles per minute. This test is of value to material manufacturers in determining consistency of their product (Chapter 2). 

Filter specifications are matched to the response times of the process. For example, a given process has a time constant of 5 minutes. That means that it can respond over the frequency range of 0 to 1/20 of a cycle per minute. Higher frequencies are attenuated naturally by the process. Thus, if the data contain components beyond 0.05 cycles per minute, then those components are likely to be unwanted interferences. The linear filter would pass the frequencies between 0 and 1/20 and reject frequencies outside this range. The filter should attenuate frequencies higher than one decade above the break-point frequency. Process measurements processed by this filter are transformed to a new sequence with less interference than the original data. In this way, an input mapping has been defined. 

To illustrate behaviors of different filters, consider a moving average filter that averages over 11 terms. Such a filter has the frequency response shown in Fig. 8. Note that this filter has a relatively low gain of 0.55 at the break-point frequency of 0.05 cycles per minute. So in the range of... 

Detectors of all types exhibit noise (IV). Noise is the amplitude (in detector response units) of the envelope of the baseline, which includes all random variations of the detector signal, whose frequency is on the order of one or more cycles per minute. Short-term noise is defined as that portion of the signal that consists of random periodic variations in the detector signal with a frequency of 1/min or greater. Long-term noise is similar to short-term noise except that the frequency range is between 6 and 60 cycles per hour. 

In addition, 1 mg of sterile S-2-hydroxyethyl-DL-homocysteine is added to the tube and the tube is shaken on a rotary shaker at 280 cycles per minute at 25°C for seven days. The contents of the tube were then acidified to pH 2 by the addition of sulfuric acid and centrifuged. Examination of the supernatant liquid by paper chromatography employing the methods of Bohonos et al. Antibiotics Annual (1953-4, page 49),demonstrates the presence of 7-chloro-6-demethyltetracycline,7-chlorotetracycline and tetracycline. 

Modern equipment for continuous production normally includes high-frequency induction generators, which are switched electronically, and speeds of hundreds of heating cycles per minute are becoming commonplace. 

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