Impulse signal

The methods used in determining the RTD are an impulse signal and a step-ehange or a periodie input of the traeer. The following reviews these methods of injeeting a traeer to analyze the RTD in flow systems. 

The biochemical neuron has another role as a transducer of external analog signals to impulse signals, where the external signals are received at the receptive field and transduced to impulse signals by cutting off at a certain threshold value. 

External random input signals are filtrated by the threshold value a,/2 = 0.9 and transformed into impulse signals. 

Another group of drugs that relax heart muscle are the calcium-channel blockers. One example is nifedipine, shown in Figure 14.46. Muscle contraction is initiated as a nerve impulse signals calcium ions to enter muscle cells. As their name implies, calcium-channel blockers inhibit the flow of calcium ions into muscles, thereby inhibiting muscle contraction. The heart rate slows down, and muscles of blood vessels relax and dilate, lowering blood pressure. 

It should be noted, however, that most of these techniques assume a plug-type inlet flow into the system. If this is not the case, special care must be taken in introducing the tracer material (e.g., in an impulse signal, the amount of tracer must be proportional to the local velocity, otherwise complex corrections may be required). 

Figure 9.18. The bolometer shown at left responds to the energy deposited by ionizing particles passing through its absorber, leading the the impulsive signals known as glitches shown at right.

Function F(x) represents the apparatus response to a unitary impulsion signal where Cq is the concentration in the input flow. By measuring the signal concentration in the exit flow we can write F(x) with the relation (3.62). When the condition of pure unitary signal is respected, we can easily observe that F(0) =0 and F(oo) = 1. In this case, function F(x) can be written as ... 

For the unitary impulse signal (relation (3.100)) the axial dispersion flow model has an analytical solution ... 

The multiplication P (n)AT gives the existence probability or the probability to have the fluid element in compartment k in the interval of time defined by nAt and (n + 1)At. In other words, it is the response of compartment k to an impulse signal. For k = N, we can observe that the probability Pjj(n)AT makes it possible for the fluid element to leave the cells assembly in the same interval of time T = nAr and t + At = (n + 1)At. Furthermore, because PN-i(n) gives the distribution of the residence time for our assembly of compartments, then we can conclude that the response to one step impulse can be written as ... 

Some definitions from linear system theory are required. The weighting function h(t) is the response (output) of a linear system applied to an impulse signal, theoretically a Dirac-delta function 6(t), or more precisely, a 6-distribution with the properties ... 

Of all atomic spectroscopic methods, ICP-MS is unrivalled concerning its detection power (Bencs et al. 2003). Its capability to process fast transient signals is crucial for the combination with sample preparation methods that generate impulse signals, like e.g. ablation techniques or most on-line preconcentration systems. 

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