RAMP

The ramp function is one that changes continuously with time at a constant rate K. 

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There are two main applications for such real-time analysis. The first is the detemiination of the chemical reaction kinetics. Wlien the sample temperature is ramped linearly with time, the data of thickness of fomied phase together with ramped temperature allows calculation of the complete reaction kinetics (that is, both the activation energy and tlie pre-exponential factor) from a single sample [6], instead of having to perfomi many different temperature ramps as is the usual case in differential themial analysis [7, 8, 9, 10 and H]. The second application is in detemiining the... 

After 60 minutes of aimealing, all the Pt has reacted to fonn Pt2Si. Almost immediately thereafter the reaction between Pt2Si and Si to fonn PtSi starts and after a fiirther 60 minutes all the Pt2Si has reacted, resulting in a stable PtSi film on Si. The data of silicide thickness versus ramped temperature can be plotted in reduced fonn in an Arrhenius-like plot to give the activation energy [6, 14] ... 

Colgan E G 1995 Activation energy for Pt2Si and PtSi formation measured over a wide range of ramp rates J. Mater. Res. 10 1953... 

Thenual desorption spectroscopy (TDS) or temperature progranuned desorption (TPD), as it is also called, is a simple and very popular teclmique in surface science. A sample covered with one or more adsorbate(s) is heated at a constant rate and the desorbing gases are detected with a mass spectrometer. If a reaction takes place diirmg the temperature ramp, one speaks of temperature programmed reaction spectroscopy (TPRS). 

Chiral hydrazones for asymmetric alkylations (RAMP/SAMP hydrazones- D. Enders "Asymmetric Synthesis" vol 3, chapt 4, Academic Press 1983)... 

Truck scales weigh highway vehicles they may be installed in a pit or above-ground with inclined approach ramps. A capacity of 100-t is typical. For monitoring axle weights, the scale deck can be broken into three scales, which are monitored independently the individual axle weights or total vehicle weight can be displayed by the indicator. 

A typical heat treatment cycle, as illustrated in Figure 1, comprises both nucleation and crystallization temperature holds, but some glass-ceramics are designed to nucleate and/or crystallize during the ramp itself, eliminating the need for multiple holds. 

Amide yields of up to 90—95% are reported from lauric acid and urea (1 1 mole ratio) by ramping the reaction temperature from 140 to 190°C over 4 hours. Oleic, stearic, linoleic, and ricinoleic acids gave similar results (19,20). The reaction does not form significant quantities of bisamides, but rehes on the decomposition of a substituted urea amide, releasing CO2 and NH. ... 

Because of the time constants and dynamics associated with the top level s control and manipulated variables, setpoints are usually ramped incrementally to their new values in a manner such that the process is not disturbed and the proximity to constraints can be periodically checked before the next increment is made. 

J. W. Ramp, Tappi Notes, 1990 Coating Binders Short Course, Tappi Piess, Adanta, Ga., 1990. 

Kinds oi Inputs Since a tracer material balance is represented by a linear differential equation, the response to anv one kind of input is derivable from some other known input, either analytically or numerically. Although in practice some arbitrary variation of input concentration with time may be employed, five mathematically simple input signals supply most needs. Impulse and step are defined in the Glossaiy (Table 23-3). Square pulse is changed at time a, kept constant for an interval, then reduced to the original value. Ramp is changed at a constant rate for a period of interest. A sinusoid is a signal that varies sinusoidally with time. Sinusoidal concentrations are not easy to achieve, but such variations of flow rate and temperature are treated in the vast literature of automatic control and may have potential in tracer studies. 

FIG. 25-62 Dii( ct-(liscliargc transfer station with open-top triiilers located in a depressed ramp under the loading hoppers. 

Another auxiliaiy unloading system that has proven to be very effective and efficient involves the use of moveable, hydraulically operated truck dumps located at the disposal site. Operationally, the trailer is backed up onto one of the tipping ramps, with or without its tractor. The back of the trailer is opened, and the unit is then tilted upward until the wastes fall out by gravity. The time required for the entire unloading operation typically is about 5 min per trip. 

There are several methods for relating the corrosion current, the apphed potential, and the polarization resistance. These methods involve various ways of stepping or ramping either the potential or current. Also, a constant value of potential or current can be applied. 

Asymmetric electrophilic substitution of aldehydes and ketortes via (S) or (R)-1-amino-2-methoxymethylpyrrolldine (SAMP or RAMP) hydrazones. 

Continued) Provide crush protection (e.g., ramp) when... 

The next stage in the zone-refining process is to move the furnace slowly and steadily to the right. The left-hand end of the bar will then cool and refreeze but with the equilibrium composition /cCq (Fig. 4.4c). As the furnace continues to move to the right the freezing solid, because it contains much less impurity than the liquid, rejects the surplus impurity into the liquid zone. This has the effect of inereasing the impurity concentration in the zone, which in turn then increases the impurity concentration in the next layer of freshly frozen solid, and so on (Fig. 4.4d). Eventually the concentrations ramp themselves up to the situation shown in Fig. 4.4(e). Flere, the solid ahead of the zone has exactly the same composition as the newly frozen solid behind the zone. This means that we have a steady state where as much impurity is removed from the... 

The final stage takes place when the furnace runs up to the end of the bar (Fig. 4.4f). The freshly frozen solid behind the zone continues to pump surplus impurity into an ever-shortening zone, and the compositions of the liquid and the solid frozen from it ramp themselves up again, eventually reaching in theory (but not in practice) infinite values. 

Because we need to know how long the refined section of the bar is, it is important to describe the ramping up of the compositions in a quantitative way. We can do this by writing a differential equation which describes what happens as the zone moves from some general position x to a new position x + 8x (Fig. 4.4g). For a bar of unit cross-section we can write the mass conservation equation... 

Ramping-up to full load with the power eontribution from the expander... 

The operation of the buek regulator ean be seen by breaking its operation into two periods (refer to Figure 3-2). When the switeh is turned on, the input voltage is presented to the input of the L-C Alter. The induetor eurrent ramps linearly upward and is deseribed as... 

The eurrent waveform, this time, is a negative linear ramp whose slope is -VoJL. When the power switeh onee again turns on, the diode snaps off and the eurrent now flows through the input power souree and the power switeh. The induetor s eurrent (imin) just prior to the switeh being turned on, beeomes the initial eurrent the power switeh must then initially pass. 

As one can notice, the boost-mode converter has the same parts as the forward-mode converter, but they have been rearranged. This new arrangement causes the converter to operate in a completely different fashion than the forward-mode converter. This time, when the power switch is turned on, a current loop is created that only includes the inductor, the power switch, and the input voltage source. The diode is reverse-biased during this period. The inductor s current waveform (Figure 3-4) is also a positive linear ramp and is described by... 

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