Fast writing

One important kind of exploratory writing that you may be asked to do is the learning journal. Learning journals are more elaborate than most exploratory writing and are sometimes formally assessed, which may alter how you approach them. We look at this possibility at the end of the chapter, but otherwise we focus on the learning journal as a non-graded, exploratory kind of writing. 

Learning journals may be kept for different purposes - for example  

There are many different kinds of iearning journai but they can aii be compared to a personai diary. Most peopie who have kept a personai diary find that a iearning journai is different, because the subject matter and situation is different, but there are aiso simiiarities. 

Have you ever kept a diary of any kind Make notes on what it was, why you kept it, who was the intended reader and what you gained from it. 

Learning journals usually begin with an account of the student s expectations of a course. Read the following extract from one student s first entry for a course about political theory. Note how the student writes about what she hopes to learn on the course and how she relates this to her own background - her arguments with her 

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Additional advantages offered by a NV-RAM over a conventional EEPROM are fast write-access (<30ns) and high number of write cycles (> 1013). 

From what we have said already, we can write down an energy balance which must be met if the crack is to advance, and fast fracture is to occur. Suppose a crack of length fl in a material of thickness t advances by 8a, then we require that work done by loads > change of elastic energy + energy absorbed at the crack tip, i.e. 

I sineerely hope that this new edition will be as interesting to read as it was for me to write and that it will be a useful referenee to the fast-growing field of turbomaehinery. 

The kinetic data based on the demonstration of specific acid catalysis in buffers, solvent isotope effects and acidity functions all support mechanisms where the proton-transfers are fast. It is possible to write equations which accommodate these facts together with the first-order dependence on hydrazo-compound and the concurrent first and second-order dependence on acidity. These are... 

The values of both E and 4 are likely to be very near to zero, since they are very fast radical recombination reactions known in general to require little activation. Thus, recalling that AE = A- AnRT for gas phase reactions, we may write j ] = (345-7) = 169 kJ mol"1. Equation (8-19) then gives 2 = 32 kJ mol"1. The value of 2 has been measured directly4 and is 31.4 kJ mol"1. 

BH h + HA and its reverse, both of which are fast, followed by HA- + B - BH+ + A2, which is slow. Find the rate law with HA treated as the intermediate and write the equation for the overall reaction. 

The difficulty disappears when the mixing and mass transfer steps are fast compared with the reaction steps. The contents of the reactor remain perfectly mixed even while new ingredients are being added. Compositions and reaction rates will be spatially uniform, and a flow term is simply added to the mass balance. Instead of Equation (2.30), we write... 

In this approximation we assume that one elementary step determines the rate while all other steps are sufficiently fast that they can be considered as being in quasi-equilibrium. If we take the surface reaction to AB (step 3, Eq. 134) as the rate-determining step (RDS), we may write the rate equations for steps (1), (2) and (4) as ... 

Consider the case when the equilibrium concentration of substance Red, and hence its limiting CD due to diffusion from the bulk solution, is low. In this case the reactant species Red can be supplied to the reaction zone only as a result of the chemical step. When the electrochemical step is sufficiently fast and activation polarization is low, the overall behavior of the reaction will be determined precisely by the special features of the chemical step concentration polarization will be observed for the reaction at the electrode, not because of slow diffusion of the substance but because of a slow chemical step. We shall assume that the concentrations of substance A and of the reaction components are high enough so that they will remain practically unchanged when the chemical reaction proceeds. We shall assume, moreover, that reaction (13.37) follows first-order kinetics with respect to Red and A. We shall write Cg for the equilibrium (bulk) concentration of substance Red, and we shall write Cg and c for the surface concentration and the instantaneous concentration (to simplify the equations, we shall not use the subscript red ). 

We certainly want to respond very differently if the temperature of a chemical reactor is changing at a rate of 100°C/s as opposed to l°C/s. In a way, we want to "project" the error and make corrections accordingly. In contrast, proportional and integral controls are based on the present and the past. Derivative controller action is based on how fast the error is changing with time (rate action control). We can write... 

When the government wishes to encourage construction it can give permission for a fast tax write-off. This means the company can depreciate the plant much faster than it will wear out. This practice has been prevalent in war years when the government needed to have certain defense plants built. It has been proposed that this method might be used to encourage companies to install pollution-reducing systems. 

This limit is actually nonphysical for inelastic collisions, as an excitation to a state with energy n cannot occur with zero momentum transfer. Nonetheless, it is an important limit, which serves to check on experiments on inelastic collisions (Lassettre and Francis, 1964), and it shows clearly the similarity between optical transitions and collision with fast chaiged particles for which K is small. From (4.13) and (4.14), one can write... 

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