Shape fixing time

Influences of shape fixing time on shape memory polymers... 

When the deformed T -SMPUs are cooled from T to T for shape fixing, the free volume in the amorphous region is squeezed out progressively, which is also time-dependent, similar to the physical aging in glassy polymers. Hence the shape fixing time (t ), the time for shape fixing in which the samples are constrained at Tg, can infiuence the shape fixity of the T -SMPUs. 

Figure 5.15 presents the influence of shape fixing time (t ) on shape fixity of PPG725-80. Evidently, the shape fixity augments with the growth of L. The... 

Slurry or slip casting provides a relatively inexpensive way to fabricate unifonn-thickness, thin-wall, or large cross section shapes [4o, 44, 45, 46, 42 aiid 48]. For slip casting, a slurry is first poured into a porous mould. Capillary suction then draws the liquid from the slurry to fonn a higher solids content, close-packed, leather-hard cast on the inner surface of the mould. In a fixed time, a given wall thickness is fonned, after which the excess slurry is drained. 

S02 is a very stable oxide and its thermal decomposition is only measurable at the very high temperatures attained in a shock tube. A study357 of the time-dependence of light emission from shock-heated S02/Ar mixtures in the region of 3000 °K has shown that S02 is removed in accordance with a sigmoid-shaped concentration-time curve typical of a chain or autoaccelerated reaction. The induction period observed357 prior to the onset of detectable decomposition corresponded closely with the time for the formation of a fixed concentration of O (or SO) calculated from the rate expression (Table 24) for the unimolecular decomposition... 

Step input. All the conclusions drawn for the pulse input can directly be transferred to the step input. The concentrations, if expressed for the nondimensional coordinates , and 9, are not affected by sorption the shape of the concentration curve along x for a fixed time is independent of sorption. Yet, when the front passes by a fixed location x, the time needed for the concentration to increase from, say, 5% to 95% of the maximum concentration, grows as (/w)-1. This can be directly deduced from Table 25.2, where the duration of the passage of the front is quantified by the nondimensional time interval A0 - 095 -05. This value does not depend on sorption, but after transformation back into real time it does (see Eq. 25-42) ... 

Delay Fast linear or shaped linear pulse Identical pulse after a fixed time delay... 

Integration of a time-dependent thermal-capillary model for CZ growth (150, 152) also has illuminated the idea of dynamic stability. Derby and Brown (150) first constructed a time-dependent TCM that included the transients associated with conduction in each phase, the evolution of the crystal shape in time, and the decrease in the melt level caused by the conservation of volume. However, the model idealized radiation to be to a uniform ambient. The technique for implicit numerical integration of the transient model was built around the finite-element-Newton method used for the QSSM. Linear and nonlinear stability calculations for the solutions of the QSSM (if the batchwise transient is neglected) showed that the CZ method is dynamically stable small perturbations in the system at fixed operating parameters decayed with time, and changes in the parameters caused the process to evolve to the expected new solutions of the QSSM. The stability of the CZ process has been verified experimentally, at least... 

Although common knowledge has it that fixed phase relations do not influence the perception of timbre [Zwicker and Fasti, 1990, Zwicker, 1982], this is not true for time-varying phases disturbing phase relations is known to introduce buzziness or reverberation in the modified signal [McAulay and Quatieri, 1986b], In Eq. (7.26), phase relations are controlled through the terms 0,(/). Therefore, an ideal shape-invariant time-scale modification would be... 

At a fixed time, the current-potential curve obtained from several potential step experiments has the sigmoidal shape shown in Fig. 2.4. This curve shows some interesting points ... 

The ratios given in Eq. (4.66) are only dependent on the electrode shape and size but not on parameters related to the electrode reaction, like the number of transferred electrons, the initial concentration of oxidized species, or the diffusion coefficient D. For fixed time and size, the values of f or Qf2 are characteristic for a simple charge transfer (see Fig. 4.4 for the plot of Qf2 calculated at time (ti + T2) for planar, spherical, and disc electrodes) and, as a consequence, deviations from this value are indicative of the presence of lateral processes (chemical instabilities, adsorption, non-idealities, etc.) [4, 32]. Additionally, for nonplanar electrodes, these values allow to the estimation of the electrode radius when simple electrode processes are considered. 

In most operating manuals, it is claimed that the time to reach the equilibrium values must remain, for all measurements, constant and equal to that required to set the bridge to zero. However, for a given drop size, the direction and rate of approach to the equilibrium value were found to vary (Morris 1977). The use of a recorder to show the shape of the bridge imbalance-time trace is therefore strongly recommended. Readings must only be taken when the system has reached a steady state, rather than after a fixed time interval. 

A simple calculation for the heating or cooling of a body of any shape is possible for the limiting case of small Biot numbers (Bi — 0). This condition is satisfied when the resistance to heat conduction in the body is much smaller then the heat transfer resistance at its surface, cf. section 2.1.5. At a fixed time, only small temperature differences appear inside the thermally conductive body, whilst... 

As in Section 10.2, only complete binary trees are considered formally, although one could use trees of any other shape. This time, one need not even fix the shape during key generation in particular, one can allow N = °° (see Remark 10.17). Moreover, the construction is first presented in a simple form (Construction 10.13), and then in a version with reduced storage (Lemma 10.15). 

Now suppose we sample the current at some fixed time r into each of these step experiments then we can plot the sampled current, /(r), V5. the potential to which the step takes place. As shown in Figures 5A.3b and 5.1.3c, the current-potential curve has a wave shape much like that encountered in earlier considerations of steady-state voltammetry under convective conditions (Section 1.4.2). This kind of experiment is called sampled-current voltammetry, several forms of which are in common practice. The simplest, usually operating exactly as described above, is called normal pulse voltammetry. In this chapter, we will consider sampled-current voltammetry in a general way, with the aim of establishing concepts that apply across a broad range of par-... 

In sampled-current voltammetry, our goal is to obtain an /(t)-E curve by (a) performing several step experiments with different final potentials E, (b) sampling the current response at a fixed time r after the step, and (c) plotting i r) V5. E. Here we consider the shape of this curve for a reversible couple and the kinds of information one can obtain from it. 

The phase refers to the value of a biological variable at a fixed time. The word phasing is often used to describe the shape of a curve that depicts the relationship of a biological function to time. Acrophase is a more limited term which refers to a specified reference standard or zero time and indicates the lag in the crest of the function used to describe the rhythm. 

The next model relaxed the condition of fixed film shape (allowed for curvature in the film surface) and analysed the effects of the menisci on the film drainage. Analysis of the Navier-Stokes equation was simplified by the application of the lubrication approximation. The results from this analysis agreed extremely well with experimental values both in terms of film drainage rate and the changes in film shape with time. The development and growth of bulges and waves on the bottom of the film were particularly intriguing. This phenomenon was experimentally observed in these films. 

From the Api (X) curves and the pressure-Mach number relation through the shock wave it is easy to calculate the space-time diagram (R, t) if the chemical energy E of the detonating charge is known. Then at fixed times t, the location and the shape of the front of the blast waves are well defined. In the near field the asymmetry of the shock front is observed and for increasing values of time the blast... 

Scott and Steve say that a supervisor, at one point said, We all walked over that grate...it would clatter around because it had warped its shape over time. I guess we all just started walking around it instead of over...I know I did. Ultimately I, heck, any of us, should have reported that and got it fixed. And poor Joe would still... ... 

The grid was photographed under a comparatively small zero load , sufficient to straighten the sample, and at a fixed time after application of further loads. The change in shape of the grid gave the extension and contraction parallel and normal to the draw direction and hence 533 and 533 respectively. 

---