Timing devices

Inexpensive quartz-crystal digital stopwatches are convenient devices for time-interval measurements of durations ranging from 10 s to several hours, and they offer accuracies of 0.0001 to 0.01 percent. The principal error in the use of these is the reaction time of the 

Skoog and D. M. West, Fundamentals of Analytical Chemistiy, 4th ed., Saunders, New York (1982). 

Kolthoff, E. B. Sandell, E. J. Meehan, and S. Bruckenstein, Quantitative Chemical Analysis, 4th ed., chap. 19, Macmillan, New York (1969). 

Harris, Quantitative Chemical Analysis, 6th ed.. Freeman, New York (2002). 

Lashof and L. B. Macurdy, Precision Laboratory Standard of Mass and Laboratory Weights, Natl. Bur. Stand. Cir. 547, U.S. Government Printing Office, Washington, DC (1954). 

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Speed Devices. Many displacement pumps are connected by variable speed drives. When these pumps are used as a time device on a homogenizer, the setting is fixed, ie, the maximum speed is limited in order to meet the requirements of pasteurization. 

The cleaning cycles are usually controlled by a timing device which deactivates the section being cleaned. The dusts removed during cleaning are collected in a hopper at the bottom of the baghouse and then removed, through an air lock or star valve, to a bin for ultimate disposal. 

Oligosaccharide Cleavage as a Timing Device for Protein Degradation... 

Test mechanical action and polarity of equipment switch. Clean and test switches, pilot lamps, thermostats and timing devices. 

Two-position detectors such as thermostats can be fitted with an anticipatory bias to reduce the amount of overshoot. In such instruments, a small bias heater accelerates the action of the control. An alternative method to reduce overshoot is to introduce a timing device so that it acts intermittently. Where the two-position sensor is also the controller it provides only two plant outputs, maximum or zero. 

The radical rearrangement reaction, serving as a timing device, has been called a free radical clock 2 It provides a means of evaluating the rate constant for reactions of this radical with other substrates. The example shows how the radical-chromium(II) rate constant can be determined. A number of other instances have been summarized.13... 

Fig. 3.1. Schematic diagram of a TCSPC setup. Using a fast timing device (e.g., time-to-amplitude-converter) the time is measured between the excitation pulse and the detection of a photon. By repeating this procedure many times a decay curve is measured. TAC time to amplitude convertor, MCA multi channel analyzer, PC personal computer. 

Use of Separate Timing Device to Synchronize MS and HPLC Systems... 

Each selected test strain is grown for 10 h at 37°C in nutrient broth (Oxoid No. 2) or supplemented minimal media (Vogel-Bonner) on an orbital shaker. A timing device can be used to ensure that cultures are ready at the beginning of the working day. 

A bomb can be considered to contain four functional blocks, namely, a control system, a detonator, a booster, and a main charge. Although a simple ignition fuse can be used as a control system and timing device, the control system is usually more mechanical or electrical in nature. The detection of control systems may be visual, or by magnetometry, or by X-ray. It must be remembered that many of the items involved in the ignition system, that is, clockwork, batteries, or electronic circuitry, are commonplace in ordinary items, such as cameras, mobile telephones, and personal stereos, and are not unique indicators of the presence of a bomb. In fact, it is the presence of explosives that is the key indicator of a bomb. 

The kinetic data for the reaction of primary alkyl radicals (RCH2 ) with a variety of silanes are numerous and were obtained by applying the free-radical clock methodology. The term free-radical clock or timing device is used to describe a unimolecular radical reaction in a competitive study [2-4]. Three types of unimolecular reactions are used as clocks for the determination of rate constants for this class of reactions. The neophyl radical rearrangement (Reaction 3.1) has been used for the majority of the kinetic data, but the ring expansion rearrangement (Reaction 3.2) and the cyclization of 5-hexenyl radical (Reaction 3.3) have also been employed. 

Timing devices, including a pulser/sequencer unit... 

A typical fuel injection system is composed of the following components fuel tank, injection pump, mechanical or electronic governor, timing device, fuel supply pump, high-pressure fuel injection lines, and fuel injectors. The high-pressure fuel injection pump is the core of the fuel injection system. The in-line pump and distributor pump are the most common in fuel systems. 

The circadian cycle is not the only timing device used by animals. A short-term interval timer helps male doves to know how long to sit on a nest1085 and helps all of us in timing everyday tasks. 

The center section was the demolition part filled with HE and equipped with a delayed-action fuze that acted only after the bomb penetrated the target. The nose section contained about a dozen small incendiary bombs which were released by a timing device at the desired moment. The incendiary bombs scattered burning material setting numerous intense fires, thus completing the destruction caused by HE... 

Then the tap is closed and the strand ignited at the top. When flame reaches the upper "timing lead it breaks the fuse wire. This activates electrical relay causing a timing device to start. When the flame reaches the lower wire the relay would stop the timing device. Thus a measurement can be taken for the burning to travel betw the accurately known distance along the strand. This method... 

With fast reactions it is very important to ensure that there is rapid mixing, fast initiation and fast analysis. Special timing devices are needed. Consequently techniques special to fast reactions had to be developed. 

The time of analysis must be very rapid. Stopped flow methods always require an inbuilt timing device, and time intervals at which analysis is made are dictated by the speed at which successive analyses can be carried out. Spectroscopic methods using pulsed radiation are very useful here because they can be both analytical and timing devices. 

Some of the variable valve lift design and valve timing devices may prove to be sensitive to lubricant viscosity and formulation in a way which is unexpected. Some of the cylinder bore coatings, which will be deployed will show different... 

Lampl, I., and Yarom, Y. Subthreshold oscillations of the membrane potential a functional synchronizing and timing device./ Neurophysiol 1993, 70 2181-2186. 

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