Non-monotonic Course Research Articles

Evolution and verification of a kinematic hypothesis for splitting of the strain energy

Splitting of the strain energy into its “non-membrane” and membrane percentage provides insight into the load-carrying mechanism of structures, subjected to proportional loading. It may be useful, for example, for sensitivity analysis of the initial postbuckling behavior of beams, arches, plates, and shells, and assemblies of such structures. The task of this work is to determine this percentage without computing insignificant numbers such as the values of the strain energy and its membrane part. It is hypothesized that this percentage is proportional to the acceleration of a fictitious particle, moving along a curve on the unit sphere. The curve is described by the vertex of the normalized “fundamental eigenvector” of the so-called “consistently linearized eigenvalue problem”. The proportionality factor is obtained from the initial condition for the “non-membrane” percentage of the strain energy, hypothesized as twice the initial velocity of the particle. The lower bound of this factor signals the constancy of this percentage with increasing load, whereas the upper bound indicates a monotonic increase or decrease up to its ab initio predictable value at a stability limit or to an unphysical asymptotic limiting value. The proof of the universal validity of the two hypotheses begins with their verification for the special cases of a membrane stress state and pure bending. The assertion that this is a sufficient condition for the universal validity of these hypotheses is subsequently verified for an example with a monotonically increasing “non-membrane” percentage of the strain energy. It is finally confirmed by an indirect proof of their validity for a non-monotonic course of this percentage. A by-product of this work are conditions for extreme values of the stiffness of structures, subjected to proportional loading.

Non-monotonic course of protein solubility in aqueous polymer-salt solutions can be modeled using the sol-mxDLVO model.

Protein purification is often performed using cost-intensive chromatographic steps. To discover economic alternatives (e.g., crystallization), knowledge on protein solubility as a function of temperature, pH, and additives in solution as well as their concentration is required. State-of-the-art models for predicting protein solubility almost exclusively consider aqueous salt systems, whereas "salting-in" and "salting-out" effects induced by the presence of an additional polymer are not considered. Thus, we developed the sol-mxDLVO model. Using this newly developed model, protein solubility in the presence of one salt and one polymer, especially the non-monotonic course of protein solubility, could be predicted. Systems considered included salts (NaCl, Na-p-Ts, (NH(4))(2) SO(4)) and the polymer polyethylene glycol (MW: 2000 g/mol, 12000 g/mol) and proteins lysozyme from chicken egg white (pH 4 to 5.5) and D-xylose ketol-isomerase (pH 7) at 298.15 K. The results show that by using the sol-mxDLVO model, protein solubility in polymer-salt solutions can be modeled in good agreement with the experimental data for both proteins considered. The sol-mxDLVO model can describe the non-monotonic course of protein solubility as a function of polymer concentration and salt concentration, previously not covered by state-of-the-art models.

The theoretical partition curve of the hydrocyclone

In many cases, the hydrocyclone partition curve exhibits a non-monotonic course in the fine particle range. The so-called fish-hook effect indicates an increased separation of the fine fraction, which is of practical interest and has a positive effect on solid/liquid separation. However, for classification purposes, the separation is less distinct. In this contribution an equation of a partition curve containing a fish-hook is derived considering the laws of disturbed settling in dense, polydisperse suspensions. The following effects are considered: the entrainment of fine particles in the boundary layer of the coarse settling particles, the hindered settling due to the increased effective density and viscosity of the fluid, and the counter flow of the displaced fluid caused by the settling particles. The calculations indicate that the fish-hook effect is primarily caused by fine particle entrainment, which is influenced by the feed solid content and the feed particle size distribution. An approximated analytical solution for the partition curve is presented for aRosin–Rammler–Sperling–Bennet (RRSB)-distributed feed. Experiments using 25-mm hydrocyclone confirm the calculations.

Computer simulations of the Fish-Hook effect in hydrocyclone separation

This contribution is dedicated to the direct modelling the non-monotonic course of the separation function of a hydrocyclone. To calculate the separation curve it is necessary to know the concentration field of particles of each size fraction in the apparatus. The system of equations describing the steady-state turbulent flow of a polydisperse suspension consisting of a liquid phase (water) and N fractions of the dispersed phase (particles) in the hydrocyclone, in line with the “mixtures model” can be written in a form of conservation equations. This system is investigated numerically. The main feature of these calculations is that previously developed model for the settling velocity of a polydisperse suspension in a centrifugal field is used. The results can be summarised as following: The consideration of the interaction of particles in a polydisperse suspension can explain the non-monotonic character of the separation curve (the Fish-Hook-effect) by the deviation of the particles’ sedimentation rate from the law of Stokes. The magnitude of the Fish-Hook-effect depends on the concentration of the solid phase.

Effect of dissolved hydrogen on electron transport in nickel–chromium alloys

The thermoelectric power and electrical resistance of Ni 0.95Cr 0.05H c alloys (0≤ c≤0.96), obtained by high pressure hydrogenation, have been measured between 80 and 300 K. The electrical resistance of two other Ni 1− x Cr x –H alloys ( x=0.025 and 0.11) has been measured in the range from 4 to 300 K. The absorbed hydrogen acting as electron donor induces qualitative changes in the behavior of both properties. The negative temperature coefficient of resistance over a wide T-range and the non-monotonic course of the thermoelectric power are attributed to a Kondo-like effect, i.e., spin-flip scattering of electrons on magnetic moments localized at the chromium atoms.

Apparent Molar Volume of Solubilized Water in AOT/Isooctane/Water Reverse Micellar Aggregates

States of the solubilized water in reverse micellar solution of aerosol-OT (AOT, bis(2-ethylhexyl) sodium sulfosuccinate) in isooctane were investigated by determining the apparent molar volume of water, Vw, through density measurements at different temperatures and water contents wo ([H2O]/[AOT]) of the solution. The low Vw values in the range up to wo = ∼ 2 are due to the strong interaction of H2O molecules with the ionic headgroup of AOT. Then, Vw exhibits a steep rise with water content in the range of wo = 2−6 owing to the swelling of the spherical reverse micelle, which is caused by the weaker binding of the additional water molecules to the ester group of AOT. In the range of wo = 6−12, Vw exhibits a complex behavior as a function of the water content with a distinct minimum in the vicinity of wo = 10. This nonmonotonic course of Vw as a function of water content in this range cannot be rationalized in terms of monotonic changes of the characteristics of the solubilized water in the micelle, or in ...

The precedence effect and its possible role in the avoidance of interaural ambiguities.

The precedence effect, the observation that sound-source localization is determined largely by the interaural cues associated with the earlier-arriving direct sound to the neglect of later-arriving reflections, was investigated in several psychophysical experiments. The first experiment employed a stimulus composed of a continuous noise and its delayed repetition to simulate a direct sound and a single reflection. Comparison of the interaural amplitude and phase differences in this stimulus with its judged lateral position showed that the interaural amplitude and phase differences in this stimulus with its judged lateral position showed that the interaural differences do not predict lateralization judgments as simply as does a knowledge of the temporal pattern of stimulation, given the precedence effect. Most of the experiments were attempts to outline the time course of the precedence effect by measuring just-noticeable differences in interaural time and intensity of brief (less than 5 ms) wide-band noise bursts. The principal finding of these experiments was that interaural sensitivity to changes in both time and intensity follows a nonmonotonic course after the abrupt onset of as ound. Sensitivity is degraded for a period from approximately 0.5 to 10 ms after onset, with the largest jnd's at delays of 2-3 ms. The precedence effect can be understood as resulting from this temporary lapse of interaural sensitivity. It was speculated that this temporal variation in interaural acuity serves to inhibit: (1) the representation of multiple and ambiguous interaural time delays between corresponding points on the waves of periodic stimuli; and (2) the extraction of interaural phase at frequencies greater than approximately 1400 Hz.

The peripheral critical flicker frequency

Measurements of critical flicker frequency (CFF) were taken in steps of 5° along the horizontal meridian in the nasal visual field under systematic variation of luminance, area and temporal modulation (ripple ratio) of the test stimulus: for photopic luminances CFF increases from the fovea to the periphery for about 5–15 c/sec. passes several maxima and minima and falls off again at greater values of eccentricity (individually different at 30–60°). showing that parts of the retinal periphery clearly surpass the fovea in the capability of processing temporal information. It is shown that the Ferry-Porter and Granit-Harper laws are only valid in the fovea and at several points in the periphery up to about 30° of eccentricity: for greater values of eccentricity deviations occur from a strongly logarithmic relationship. The non-monotonic course of peripheral CFF is compared to Payne's measurements of reaction times to peripherally presented stimuli ( Vision Res. Vol. 6, p. 729) revealing a similar behaviour.

Backward conditioning to a CS following an expected vs. a surprising UCS

Rabbits were trained in eyelid conditioning with a “backward” arrangement of unconditioned stimulus (UCS) followed by conditioned stimulus (CS). When such a CS was tested alone it was observed to produce substantial conditioned responding if the UCS had been arranged to be “surprising” during the backward pairings, but not if it had been arranged to be “expected.” The comparisons were made in a within-subjects design where the surprisingness of the UCS on the different pairing occasions was manipulated by preceding the UCS by discriminative CSs which were otherwise either never followed by the UCS (CS−) or consistently followed by the UCS (CS+). The results may have implications for the nonmonotonic course of responding seen during backward conditioning, as a UCS is at first surprising, but then expected on the basis of contextual cues.