Input instability

Y-caps are also present on output rails Y-caps may be required to be rated > 1500V Electrolytic (bulk) capacitor to damp out input instability Leakage Inductance of CM choke is DM choke... 

Since about 1971 the phenomena of input oscillations or input instability has received quite a lot of attention. It has been shown that instability can occur if the output impedance of the filter is not within a certain safe window, as related to the input impedance of the converter (we are talking about the impedances presented to the power flow now — not the CM or DM noise). So, with the modern trend of low-impedance all-ceramic solutions in dc-dc converters, the possibility of this particular type of instability is becoming more and more real. 

Of course, the best remedy to minimize downstream instabilities is to minimize the input disturbance. Pressure initiation is thus incorporated, and the simplest and most effective way of achieving this is by vertical screw... 

This first step makes necessary a correction of the atmosphere aberrations by means of an adaptive optics or at the minimum a tip tilt device. If the turbulence induces high aberrations the coupling efficiency is decreased by a factor VN where N is the number of spatial modes of the input beam. Note that tilt correction is also mandatory in a space mission as long as instabilities of the mission platform may induce pointing errors. Figure 10 (left) illustrates the spatial filtering operation. This function allows a very good calibration of... 

An ignition experiment at 1-butene concentrations as high as 5% was performed to test instability in reaction behavior as an indication of unsafe operation (5% 1-butene in air 0.1 MPa 400 °C) [103]. The degree of conversion increased linearly and converged without any sign of instability. The power input corresponded to 6.5 W with an adiabatic temperature rise of more than 2000 °C. Plugging, however, was the major concern under these severe conditions. 

It is usually not possible or practical to control a given system input at an exact level in practice, most inputs are controlled around set levels within certain factor tolerances. Thus, controlled system inputs exhibit some variation. Variation is also observed in the levels of otherwise constant system outputs, either because of instabilities within the system itself (e.g., a system involving an inherently random process, such as nuclear decay) or because of the transformation of variations in the system inputs into variations of the system output (see Figures 2.17 and 2.18) or because of variations in an external measurement system that is used to measure the levels of the outputs. This latter source of apparent system variation also applies to measured values of system inputs. 

Annaswamy, A. M., M. Fleifil, J.W. Rumsey, J. P. Hathout, and A.F. Ghoniem. 1997. An input-output model of thermoacoustic instability and active control design. MIT Report No. 9705. Cambridge, MA. 

Since little or no heat is evolved during the induction period, the initial energy input in the "hot spot is not immediately related to the heat of decomposition of the explosive. In such cases, thermal instability is not conditioned by the heat of explosion or the mass of explosive but by other less obvious factors which apparently are related to the nature and amount of the autocatalyst... 

For heat pumps based on flooded mine systems, where the heat abstracted is replenished seasonally by inputs from solar radiation and geothermal gradient, the longevity of the reservoir is, in principle, limitless. The sustainability of the operation will only be limited by the durability of the infrastructure (e.g., biofouling, clogging or physical instability of boreholes, longevity of collector coils). 

To demonstrate the instability of Equations 3 and 4, a symmetrical unimodal distribution f(M) was arbitrarily assumed, and the corresponding u( ) = c/co was determined by applying a straight operation on Equation 3. This newly obtained u( ) function was now used as an input to evaluate back f(M), by applying an inverse operation on the... 

There are many other interesting and complex dynamic phenomena besides oscillation and chaos which have been observed but not followed in depth both theoretically and experimentally. One example is the wrong directional behavior of catalytic fixed-bed reactors, for which the dynamic response to input disturbances is opposite of that suggested by the steady-state response [99, 100], This behavior is most probably connected to the instability problems in these catalytic reactors as shown crudely by Elnashaie and Cresswell [99]. Recently Elnashaie and co-workers [102-105] have also shown rich bifurcation and chaotic behavior of an anaerobic fermentor for producing ethanol. They have shown that the periodic and chaotic attractors may give higher ethanol yield and productivity than the optimal steady states. These results have been confirmed experimentally [105],... 

There are of course other causes for exit beam misalignment other than simply the process of optical retardation by mirror scanning. The overall alignment integrity of the cube-corner/beamsplitter/cube-corner module as well as its optical relationship to the collimated input beam from the NIR source, and the collinear HeNe laser are all critical. The thermal and mechanical instability of this whole assembly is roughly a function of its volume. Small compact FTIR modulators will perform better in process analytical... 

---