Transient events

The availability of lasers having pulse durations in the picosecond or femtosecond range offers many possibiUties for investigation of chemical kinetics. Spectroscopy can be performed on an extremely short time scale, and transient events can be monitored. For example, the growth and decay of intermediate products in a fast chemical reaction can be followed (see Kinetic measurements). 

The ESDs were then translated into associated event trees. A generic event tree was developed for all initiators not involving LOCA. The generic transient event tree for each category of the transient initiators and loss of offsite power were specialized by the impact of the initiators on the safety and support systems, from the success criteria of the mitigating systems, and the initiator-specific human actions which were modeled in the fault trees. 

Ten front line systems and 5 support systems were modeled using about 700 basic events. A generic transient event tree with 215 sequences was developed and quantified for 14 different transients and three loss-of-offsite-power events. Four LOCA event trees were de I and... 

For routine monitoring of machine vibration, however, this approach is not cost effective. The time required to manually isolate each of the frequency components and transient events contained in the waveform is prohibitive. However, time-domain data has a definite use in a total plant predictive maintenance or reliability improvement program. 

Steady-state analysis totally ignores variations in the vibration level or vibration generated by transient events... 

Most of the microprocessor-based instruments are designed to handle steady-state vibration data. Few have the ability to reliably capture transient events such as rapid speed or load changes. As a result, their use is limited in situations where these occur. 

In general, three to four samples are acceptable for good statistical averaging and keeping the time required per measurement point within reason. Exceptions to this include low-speed machinery, transient-event capture, and synchronous averaging. 

Once this common thermodynamic framework is established for the solubility of U02 under nominally reducing conditions, we have to ascertain the most probable pathway for the oxidative alteration of U02 spent fuel in geological repository conditions. There is a large body of evidence on the processes involved in the oxidative alteration of natural uraninites and unirradiated U02. Long-term unsaturated tests performed by Wronckiewicz et al. (1992) on groundwater from Yucca Mountain (the so-called J-13 groundwater), indicated that the formation of schoepite, as described by process (20) and (21), occurs, but is a transient event and that the alteration proceeds towards the precipitation of... 

The most convenient means of making time-resolved SH measurements on metallic surfaces is to use a cw laser as a continuous monitor of the surface during a transient event. Unfortunately, in the absence of optical enhancements, the signal levels are so low for most electrochemical systems that this route is unattractive. A more viable alternative is to use a cw mode-locked laser which offers the necessary high peak powers and the high repetition rate. The experimental time resolution is typically 12 nsec, which is the time between pulses. A Q-switched Nd YAG provides 30 to 100 msec resolution unless the repetition rate is externally controlled. The electrochemical experiments done to date have involved the application of a fast potential step with the surface response to this perturbation followed by SHG [54, 55,116, 117]. Since the optical technique is instantaneous in nature, one has the potential to obtain a clearer picture than that obtained by the current transient. The experiments have also been applied to multistep processes which are difficult to understand by simple current analysis [54, 117]. 

As shown in Fig. 14, the cathode potential changes abruptly across the H2/air-front. This fact warrants the inclusion of the pseudocapacitance into the previous steady-state kinetic model.12 It is clear that the electrode s pseudo-capacitance can supply protons in transient events and thereby reduce the cathode carbon-support corrosion rate in the case of fast moving H2/air- ronts. Figure 18... 

One of the more challenging unsolved problems is the representation of transient events, such as attacks in musical percussive sounds and plosives in speech, which are neither quasi-periodic nor random. The residual which results from the deterministic/stochastic model generally contains everything which is not deterministic, i.e., everything that is not sine-wave-like. Treating this residual as stochastic when it contains transient events, however, can alter the timbre of the sound, as for example in time-scale expansion. A possible approach to improve the quality of such transformed sounds is to introduce a second layer of decomposition where transient events are separated and transformed with appropriate phase coherence as developed in section 4.4. One recent method performs a wavelet analysis on the residual to estimate and remove transients in the signal [Hamdy et al., 1996] the remainder is a broadband noise-like component. 

Many different terms are associated with transients, such as spikes, bumps, power pulses, impulses, and surges. While some of these terms may indeed describe a particular transient, such terms are not recommended due to their ambiguity. We will use the term transient to denote all subcycle events and ascribe certain characteristics to these events, such as overvoltage, notch, noise, and ring. It may be that what we call transient is not as important as remembering that the underlying causes of the various transient events differ, as do the cures for the ill effects produced by the transients. 

The hypnogram of a patient with an underlying psychiatric illness may be characterized by a delay in sleep onset, the presence of residual muscular activity causing frequent awakenings, fragmented sleep, reduced REM and slow-wave sleep, and day-time drowsiness. Such disorders are generally not associated with a recent or transient event and the cause cannot usually be identified. Often such changes in the sleep architecture are associated with major psychiatric disorders such as depression, mania, psychosis or severe anxiety states. 

The other and much better established phenomena are transient events seen in specific limited areas of the moon and usually lasting for times on the order of hours or days. Any activity on the supposed "dead surface of the moon is of interest and catalogs have been made which, as of 1978, had logged 1468 observations (28-30). Many of the lunar transient phenomena take the form of patches of red luminescence, some blue luminescence, and various flashes and related features. A substantial percentage of the events are related to the crater Aristarchus. 

The lunar transient events could be excited by protons in the solar wind but experiments with silicate minerals in proton beams show that the process is inefficient, quantum efficiencies from lxl0 4 to 1x10 , and given the concentration of protons in the solar wind the mechanism cannot account for the intensity of the observed luminescence (33). Another possibility is that neutral particles in the background solar wind or associated with disturbances on the sunfs surface provide the excitation source (34). This would be a process very similar if not identical to the candoluminescence and radical recombination luminescence observed in the laboratory. 

These compounds are all unstable and all are involved in transient events such as inflammation, blood clotting, fertilization, and immune responses. They are produced locally and decay quickly and arc implicated in autoimmune diseases like asthma and arthritis. They are made by oxidation of arachidonic acid—you can see this best if you redraw the molecule in a different conformation. 

It is important to recognize that the plan to use carbon in ITER follows directly from the projected levels of thermal loads expected during plasma thermal transient events (e.g., type I ELMs and disruptions). Thus, efforts to better characterize power deposition during disruptions and ELMs, as well as to reduce ELM heat loads and to mitigate disruptions (see, for example, [55]) are very important due to the influence on these design choices. 

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