Oscillatory operation mode

In Figure 4.38 the effect of the flow rate and the inhibition constant A l Si on the concentration of B is shown. In this figure data are taken from Figures 4.36 (Q = 20 mL/h) and 4.37 (Q = 60 mL/h), with Kf Si = O.I mM (left panel) and with A i Si = 1 niM (right panel). In all cases the signals obtained are oscillatory with a time period of 10 min, which is also the time period of the input signal. However, various amplitudes and phase shifts are obtained when the parameters or the operational modes are changed. 

Contrary to the cases of cryogenic cooling of detectors and the application of optical methods for the increase of radiative lifetime, the device in operating mode is here in dynamical state. Although kinetic processes in detectors in a general case may be nonstationary (various transient phenomena and oscillatory modes of operation, e.g., in detectors utilizing the traveling wave mechanism [326] or hot electrons [327]), this work is dedicated solely to stationary phenomena. 

Combustion of a propellant in a rocket motor accompanied by high-frequency pressure oscillation is one of the most harmful phenomena in rocket motor operation. There have been numerous theoretical and experimental studies on the acoustic mode of oscillation, concerning both the medium-frequency range of 100 Hz-1 kHz and the high-frequency range of 1 kHz-30 kHz. The nature of oscillatory combustion instability is dependent on various physicochemical parameters, such... 

In [53], oscillatory wave patterns observed during electrochemical dissolution of a nickel wire in acidic media was reported. It was shown that space-averaged potential or current oscillations are associated with the creation of an inhomogeneous current distribution, and that the selection of a specific spatial current pattern depends on the current control mode of the electrochemical cell. In the almost potentiostatic (fixed potential) mode of operation, a train of traveling pulses prevails, whereas antiphase oscillations occur in the galvanostatic (constant average current) mode. 

In addition to the steady-state mode, the double-cell device of Fig.7 can be operated in the so-called transient and oscillatory modes of operation(18.). In the transient mode, one measures the slope dVg/dt when the pumping current is changed in a stepwise fashion from zero to a constant value. A simple analysis(18) gives the following differential equations for Vg and Pv,... 

Several companies supply density equipment which was considered suitable for automatic, continuous operation with sufficient precision for calculation of polymerization conversion. These break down into three classes based on mode of operation y-ray absorption, oscillatory frequency of a sample filled tube, and mass measurement at fixed volume. Only one of these, an oscillator-based system distributed by Mettler Instrument Corp. (representing Anton Paar Ag.) has models with dead volumes small enough for laboratory scale experimentation. The other units generally also suffered from narrow density spans when the precision was sufficient for conversion studies. Table... 

Before we can start to develop a model we also have to decide how to interpret the behavior observed in Fig. 2.1. The variations in insulin and glucose concentrations could be generated by a damped oscillatory system that was continuously excited by external perturbations (e.g. through interaction with the pulsatile release of other hormones). However, the variations could also represent a disturbed self-sustained oscillation, or they could be an example of deterministic chaos. Here, it is important to realize that, with a sampling period of 10 min over the considered periods of 20-24 h, the number of data points are insufficient for any statistical analysis to distinguish between the possible modes. We need to make a choice and, in the present case, our choice is to consider the insulin-glucose regulation to operate... 

As discussed in Section 12.5, the two oscillatory modes associated with the pressure and flow regulation in the individual nephron may operate in synchrony or... 

In modeling the interaction of a liquid with plate modes, the high frequency of operation necessitates the consideration of viscoelastic response by the liquid. For the simple liquids examined, good agreement was obtained by modeling the liquid as a Maxwellian fluid with a single relaxation time r. When the Maxwellian fluid is driven in oscillatory flow with cot < 1, it responds as a Newtonian fluid characterized by the shear viscosity, rj. For wt > 1, the oscillation rate approaches the rate of molecular motion in the liquid and energy ceases to be dissipated in... 

Machine (UTM), (Instron Engineering Corp., Canton, MA) and the UTM was operated in an oscillatory mode with a cross head speed of 0.05 cm min , plunger displacement of 0.1 mm (Okechukwu et al., 1991). At the end of the test, the length of the plunger covered by the slurry was measured and used in estimating the apparent storage rigidity modulus, G. ... 

A more direct evidence of the surface localized excitation mechanism has been obtained by a polarization dependence study. For K/Pt(lll) at 0.36 ML, it has been demonstrated that the coherent excitation of the K—Pt stretching mode occurs with p-polarized excitation and not with s-polarized exdtation. Since the s-polarization absorptance is about one fourth of that with p-polarization under the experimental conditions (2.19 eV photon energy, 70° angle of inddence), the coherent amplitude should be detectable with s-polarization if the substrate-mediated process operates. Therefore, the negligible oscillatory component with s-polarization is inconsistent with the substrate-mediated excitation model and it is indicated that some electronic transitions involving K-induced surface states are responsible for the coherent excitations. 

Service use in the brush commutator contact and the support bearings of the tachometer of a star tracker operating in an oscillatory mode Motion through an arc of 80° at 0.25°/s, 0.5°/s or 4°/s and a dither mode of 20 cycles/s through 7°... 

Interest in flowing systems focuses on (i) the existence of multiple steady-state solutions of the reactor equations and (ii) the stability of such solutions. These are not independent the existence of parametrically sensitive regions of dynamic behaviour can give rise to oscillations in both temperature and concentration, constant in period and amplitude. The anticipation and control of such oscillatory modes of reaction is clearly of no less importance to the successful operation of the reactor than is the prediction of its stability. 

Rotational rheometer n. An instrument for measuring the viscosity of molten polymers (any many other fluid types) in which the sample is held at a controlled temperature between a stator and a rotor. From the torque on either element and the relative rotational speed, the viscosity can be inferred. The most satisfactory type for melts is the cone-and-plate geometry, in which the vertex of the cone almost touches the plate and the specimen is situated between the two elements. This provides a uniform shear rate throughout the specimen. It may be operated in steady rotation or in an oscillatory mode. 

EXTAR 6000 Dynamic Mechanical Spectrometer This instrument applies various deformations, such as bending, tension, compression, and shear, to a solid sample and operates in the oscillatory mode as well as the static mode for stress relaxation and creep. For dynamic measurements, a new synthetic oscillation mode has been added to the existing high-precision sine wave oscillation mode. The synthetic oscillation mode can measure multiple frequencies at an extremely fast rate, which allows the instrument to measure samples with extremely rapid elastic modulus transformations. Measurements from -150 °C are fully automatic using the automatic gas cooling unit. 

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