Dynamo, elementary

In distinction with thermal reactions, photochemical ones involve at least two potential surfaces. Attempts to understand them may be divided into two categories those treating the ground and excited states separately, and those considering the coupling between the two as an essential ingredient. The first category analyzes photochemical reactions in terms of a kinetic mechanism, and seeks transition states and intermediates, in a manner that is commonly used for thermal reactions [126-128]. The rate-determining step, as a rule, is considered to be on the excited-state surface and the mechanism for the return from the excited to the ground state is not specified—it is assumed that the system will somehow find its way down. This approach, which views the photochemical process as a sequence of elementary reactions, each proceeding  [c.387]

Particle diam., i Number of elementary electrical charges, Nq Particle migration velocity, u, ft/sec  [c.1611]

Transient response techniques supply far more information on any dynamic system than a steady-state test can. In multi-step processes where an overall change is accomplished through a series of elementary steps, the rate of all steps has to be equal to maintain a steady state. When a system in steady state is disturbed by a sudden change in one of its parameters or driving forces, then the different elementary steps will react to the disturbance at different speeds. During the upset, the elementary steps reveal their significance or the lack of it. With proper instrumentation, transient signals can be recorded and analyzed for their information content. The experimentally applied disturbing signals are the pulse (spike, or Dirac delta), the square pulse, frequency change of sinusoidal signals and square step up or down. The most appropriate one depends on the system to be tested, on the instrument that monitors the signal, and on the mathematical techniques available to analyze the resulting exit signal. The simplest and most frequently used is the step change technique.  [c.151]

The most elementary function of an air pollution control agency is its control function, which breaks down into two subsidiary functions enforcement of the jurisdiction s air pollution control laws, ordinances, and regulations and evaluation of the effectiveness of existing regulations and regulatory practices and the need for new ones.  [c.428]

Notice that one event has units of per-demand and the others have a per-unit-time dimension. From elementary considerations, the top event can only have dimensions of per-demand (pure probability) or per-unit-time dimensions. Which dimensions they have depends on the application. If the fault tree provides a nodal probability in an event tree, it must have per-demand dimensions, if the fault tree stands alone, to give a system reliability, it must have per-unit-time dimensions. Per-unit-time dimensions can be converted to probability using the exponential model (Section This is done by multiplying the failure rate and the "mission time" to give the argument of the exponential which if small may be  [c.304]

The technical basis of the THERP technique is identical to the event tree methodology employed in CPQRA. The basic level of analysis in THERP is the task, which is made up of elementary steps such as closing valves, operating switches and checking. THERP predominantly addresses action errors in well structured tasks that can be broken down to the level of the data contained in the THERP Handbook (Swain and Guttmann, 1983). Cognitive errors such as misdiagnosis are evaluated by means of a time-reliability curve, which relates the time allowed for a diagnosis to the probability of misdiagnosis.  [c.227]

The most widely accepted mechanism of reaction is shown in the catalytic cycle (Scheme 1.4.3). The overall reaction can be broken down into three elementary steps the oxidation step (Step A), the first C-O bond forming step (Step B), and the second C-O bond forming step (Step C). Step A is the rate-determining step kinetic studies show that the reaction is first order in both catalyst and oxidant, and zero order in olefin. The rate of reaction is directly affected by choice of oxidant, catalyst loadings, and the presence of additives such as A -oxides. Under certain conditions, A -oxides have been shown to increase the rate of reaction by acting as phase transfer catalysts.  [c.30]

Figure 2-69 is a schematic of perhaps the simplest rotating machine, the elementary dynamo. The elementary dynamo consists of a rectangular-shaped coil, which is free to rotate about an axis. In a practical device, the coil is physically attached to a shaft  [c.289]

Figure 2-69. Elementary dynamo construction and operation. Figure 2-69. Elementary dynamo construction and operation.
Note that the direction of the applied torque will dictate the direction of the induced current in the elementary dynamo.  [c.290]

If the rotor of the elementary dynamo is turned in a uniform magnetic field, an AC emf and current are produced. If the speed of rotation is constant, the emf and current are sinusoidal as shown in Figure 2-69.  [c.291]

If the slip rings of the elementary dynamo are replaced by a split-ring commutator, then a DC emf and current will be generated as shown in Figure 2-71. If the single  [c.291]

The remaining step is to write down a general expression consisting of these elementary operators that reproduces an arbitrary computation, such as a summer  [c.675]

An elementary account of the subject has been given in the previous Section. For the fractional distillation under diminished pressure of liquids diflfering only slightly in boiling point, a firactionating column (see Sections 11,15 and 11,17) must be used. Provision must, of course, be made for the insertion of a capillary tube into the fiask containing the mixture. This can be done by any of the following methods —  [c.119]

A computer must be instructed in the operations that it has to carry out. Although some instruction is built into the computer and appears as hardware (the physical constraction), most of the instraction set is written in a suitable language, and then the computer is programmed to do its job. At the lowest level of language, the so-called machine code, instructions are written in a very elementary fashion, and literally each step of the instraction sequence must be spelled out. For example, in everyday life one might say something like, Draw a square. This statement would be high-level language. In machine code, the same instruction might be, Put a dot on the video screen at location x, y move horizontally to the right for z squares stop move vertically down for z squares stop, and so on.  [c.309]

Transmitters. The use of sonic or ultrasonic sound pulses to measure level on a continuous basis is known as air sonar. In its most elementary form, an electronic circuit appHes multiple bursts of high voltage energy to a transducer crystal. The burst of electrical pulses causes the transducer crystal to generate an acoustical pulse at a specific oscillating frequency, typically 20 to 55 kH2. The pulse propagates through the air (or vapor) and is reflected back to the transducer from the Hquid surface (Fig. 17). At the transducer, the acoustical pulse is converted back into electrical signals by the transducer and receiver circuits. Based on the microprocessor s counter/timer, the instmment knows the precise time when the crystal was charged and the elapsed time between transmission and reception of the acoustical signal. This time function is represented by the relationship t = 2djV where t represents time, d s the distance between the transducer and the Hquid surface, and U is the velocity of sound in air (or gas). Solving for d, d = V t/2. The total transit time down and up through the air space is proportional to the distance from the transmitter to the Hquid surface.  [c.214]

In 1955, being a Spanish-speaking metallurgist, I was invited to spend some weeks in Buenos Aires to deliver a course in elementary modern metallurgy to some members of the mainly youthful staff of the Atomic Energy Commission. The person who invited me, a dynamo of energy and originality, was Jorge Sabato (1924-1983) (Fig. 14.5), an Argentinian metallurgist who had recently joined the Commission s laboratory from local industry. I proved to be just the first of a procession of foreign experts, and later on Sabato organized more ambitious courses for which auditors came from all over South America. The Atomic Energy Commission came to be South America s leading focus of expertise in metallurgical engineering.  [c.529]

Secular philosophers also perceived the unique nature of water. Thus, Thales of Miletus, who is generally regarded as the initiator of the Greek classical tradition of philosophy, ca. 585 BC, considered water to be the sole fundamental principle in nature. His celebrated dictum maintains It is water that, in taking different forms, constitutes the earth, atmosphere, sky, mountains, gods and men, beasts and birds, grass and trees, and animals down to worms, flies and ants. All these are but different forms of water. Meditate on water Though this may sound quaint or even perverse to modem ears, we should reflect that some marine invertebrates are, indeed, 96-97% water, and the human embryo during its first month is 93% water by weight. Aristotle considered water to be one of the four elements, alongside earth, air and fire, and this belief in the fundamental and elementary nature of water persisted until the epoch-making experiments of H. Cavendish and others in the second half of the eighteenth century (pp. 32, 601) showed water to be a compound of hydrogen and oxygen.  [c.621]

The following methods have been used to demonstrate a substantial degree of covalent hydration in the various ionic species. Usually, at least three of these methods have had to be applied before the phenomenon could be established beyond all doubt. Before enumerating these, it should be made clear that the presence or absence of strongly held water of crystallization is to be regarded as a competitive phenomenon which makes no contribution to a diagnosis of covalent hydration. Thus, 4,7-dihydroxy-6-methylpteridine, 2-hydroxypiuine, and 4,5-diamino-2-hydroxypyrimidine all retain one molecule of water obstinately at 130° but give no indications of covalent hydration in any of the following tests. On the other hand, pteridine, which the tests show to be covalently hydrated to the extent of 22% in solution, reveals no hydration upon elementary analysis after gentle drying at 20°.  [c.4]

See pages that mention the term Dynamo, elementary : [c.78]    [c.399]    [c.250]    [c.630]    [c.15]    [c.290]    [c.293]    [c.635]   
Standard Handbook of Petroleum and Natural Gas Engineering Volume 1 (1996) -- [ c.289 ]