Time-delay constant

Keys et al. (2000) explored five approaches to modeling the pharmacokinetics of di- -butyl phthalate and mono- -butyl phthalate. In a flow-limited version of the model, transfers between blood and tissues are simulated as functions of blood flow, tissue concentrations of di- -butyl phthalate or mono-n-butyl phthalate, and tissue blood partition coefficients, assuming instantaneous partitioning of the compounds between tissue and blood (Ramsey and Anderson 1984). In an enterohepatic circulation version of the model, the transfer of mono-n-butyl phthalate from the liver to the small intestine is represented with a first order rate constant (diffusion-limited) and a time delay constant for the subsequent reabsorption of mono- -butyl phthalate from the small intestine. In a diffusion-limited version of the model, the tissue transfers include a first order rate term (referred to as the permeation constant) that relates the intracellular-to-extracellular concentration gradient to the rates of transfer. This model requires estimates of extracellular tissue volume (ECV) and intracellular volume (ICV) ECV is assumed to be equal to tissue blood volume and ICV is assumed to be equal to the difference between tissue blood volume and... 

The time delay of the heat transfer to the coolant and moderator water is an important factor in the mechanism of coupled neutronic and thermal-hydraulic instability. The Super LWR is a reactor system with a positive density coefficient of reactivity and a large time delay constant. If there is no time delay, a decrease in density would cause a decrease in power generation, which suppresses any further decrease in density, stabilizing the system. However, if there is a large time delay, it causes a decrease in the gain of the density reactivity transfer function, and reduces the effect of density reactivity feedback, making the system less stable. The time delay of the heat transfer to the water rods is much larger than that to the coolant. Thus the reactor system becomes less stable when the water rod model is included than the case without it. 

For coaxial cables, the following electrical properties related to the dielectric constant of the core material and the dimensions determine the quaUty of the signal impedance, capacitance, attenuation, crosstalk, and time delay and velocity of propagation. 

Time Delay and Velocity of Propagation. Time delay is direcdy proportional to the square root of the dielectric constant and describes the time that it takes for a signal to travel through a cable. The lower the dielectric constant, the less time required for a signal to travel through a cable. 

Complex models are often slow in execution owing to the large number of equations involved and the large range of time constants. Under these circumstances it is often useful to approximate the transient behaviour of the full model by a simpler model representation which is faster to compute. Such simplifications are commonly achieved by a combination of first-order lags and time delays and are often represented in Laplace transform form, especially when the sub-model is to be used as part of a control engineering application. 

The simplest settler model is that in which it is assumed that each phase flows through the settler in uniform plug flow, with no mixing and constant velocity, with the effect that the concentrations leaving the settler, X and Y , are simply the time delayed values of the exit mixer concentrations, Xmn and Ymn- In this the magnitude of the time delay is thus simply the time required for the phase to pass through the appropriate settler volume. 

Let say we have a high order transfer function that has been factored into partial fractions. If there is a large enough difference in the time constants of individual terms, we may try to throw away the small time scale terms and retain the ones with dominant poles (large time constants). This is our reduced-order model approximation. From Fig. E3.3, we also need to add a time delay in this approximation. The extreme of this idea is to use a first order with dead time function. It obviously cannot do an adequate job in many circumstances. Nevertheless, this simple... 

In a chemical plant, time delay is usually a result of transport lag in pipe flow. If the flow rate is fairly constant, the use of the Smith predictor is acceptable. If the flow rate varies for whatever reasons, this compensation method will not be effective. 

Figure 24 H2BC pulse sequence. Thin and thick bars represent 90° and 180° pulses, respectively, while, and the dashed boxes represent 13C decoupling, t = i2 = l/[ /max + Vminl T, = 0.5/[Vmln + 0.07(Vmax - Vmin)]. T3 = 0.5/[Vmax - 0.07(Vmax - Vmln)] and S = S + t(90H), where S is the gradient delay. T denotes the constant-time delay.

Where t is the total of the constant time delays in the CCR experiment and I represents the intensities of the peaks. 

The second stage is data acquisition. This stage is entered when the operator starts the instrument. The instrument makes the first injection and signals the microcomputer via Intelink. After a delay proportional to the void volume of the column set, data are collected on a time basis (constant flow rate assumed) at the predetermined rate from each of the detectors selected, up to a maximum of three simultaneous detectors. VHien the sample run is complete, the instrument again signals the microcomputer which places the instrument in a hold state while it reads the operational parameters from the instrument for that sample and... 

Single molecule pulUng experiments can be described with the formalism developed in Section lll.C.l. In the simplest setting the configurational variable C corresponds to the molecular extension of the complex (handles plus inserted molecule) and the control parameter X is either the force/measured in the bead or the molecular extension of the system, x. For small enough systems the thermodynamic equation of state is dependent on what is the variable that is externally controlled [87]. In the actual experiments, the assumption that either the force or the extension is controlled is just an approximation. Neither the molecular extension nor the force can be really controlled in optical tweezers [88]. For example, in order to control the force a feedback mechanism must operate at aU times. This feedback mechanism has a time delay response so the force is never really constant [89, 90]. By assuming that the force is constant. 

This may not be too clear. The full sinusoidal source can be exponentially damped, have a DC offset, and have a time delay as well as a phase delay. In the above equation, the phase ( ) is specified in degrees and is converted into radians by the constant 2jt/360. We note that for Td > t > 0, V, is constant. The sinusoid does not start until t = tphase delays, the above equation reduces to the exponentially damped sine wave ... 

The excitation of the unlabeled dibromide followed by a time-delayed probe pulse gives a time-dependent intensity profile for the 202 amu signal. It shows a rapid decay component near time zero (time constant Tq) followed by a slower decay (xi). The slower decay exhibits a periodic coherent modulation (Xc) and a gradual dephasing (Fig. 20.4). 

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