Stability kinematic

The scope of the series covers the entire spectrum of solid mechanics. Thus it includes the foundation of mechanics variational formulations computational mechanics statics, kinematics and dynamics of rigid and elastic bodies vibrations of solids and structures dynamical systems and chaos the theories of elasticity, plasticity and viscoelasticity composite materials rods, beams, shells and membranes structural control and stability soils, rocks and geomechanics fracture tribology experimental mechanics biomechanics and machine design. 

Although there are numerous publications on the effect of natural and synthetic antioxidants on the stability of oils and fats used as food and feed, until recently relatively little publicly available information was available on the effect of antioxidants on the oxidative stability of biodiesel. One of the earliest studies reporting of the effects of antioxidants on biodiesel was that of Du Plessis et aL (1985), which examined storage stability of sunflower oil methyl esters (SFME) at various temperatures for 90 d. Effects of air temperature, presence of light, addition of TBHQ (see Figure 1.1) and contact with steel were evaluated by analysis of free fatty acid content, PV, kinematic viscosity, anisidine value, and induction period. Addition of TBHQ delayed oxidation of samples stored at moderate temperatures (<30°C). In contrast, under unfavorable (50°C) conditions, TBHQ was ineffective. 

The kinematic viscosity and density were measured by methods previously described (I) the only change was an improvement in the temperature stability of the air thermostat used for the viscometer. Short term control within 0.02°C and reproduction of setting to 0.05°C were achieved by substituting a thermistor device for the previously used bimetallic spiral thermoregulator. The improvement was not enough to enable satisfactory A coefficients to be obtained in all cases although the scatter has been reduced. 

Pauchon and Banerjee (1988), in their analysis of bubbly flows, have shown that the kinematic wave velocity based on a constant interfacial friction is weakly stable. They have also obtained a functional dependence of the interfacial friction factor on the void fraction by assuming the kinetic wave velocity equal to the characteristic velocity (kinetic waves are neutrally stable). They have assumed that turbulence provides the stabilizing mechanism through axial dispersion of the void fraction. 

Kinematic viscosities of the fluids were measured according to ASTM D-445, 1991b (63). For Oxidative Stability testing, micro-oxidation experiments were carried out using the Pennsylvania State University Micro-Oxidation Kit (64). ASTM D-97 was used for pour points and cold storage tests (65). 

Initially, kinematic viscosities at 40°C and pour points of the fluids were determined (results shown in Table 8). It appears that low-temperature properties of vegetable oils are much more inferior to those of synthetic basestocks or even mineral oil. Cold storage properties of vegetable oils do not appreciably respond to the pour point depressants (PPD), as opposed to mineral oils. This is consistent with earlier observations (35). Oxidative stabilities of the oils are compared in Table 9. 

The main conclusions of the Round Robin were Karl-Fischer titration is recommended for analysing water in pyrolysis oils. Solids content as ethanol insolubles is accurate for white wood oils but a more powerful solvent, like a mixture of methanol and methylene chloride (1 1) is needed for extractive-rich oils. For the elemental analysis at least triplicates are recommended. Kinematic viscosity is an accurate method for pyrolysis oils. Stability index needs more clarification and testing,- Results of chemical characterisation were not very consistent. It may be necessary to prepare standard solutions with known aniounts of conqiounds for... 

In case of inhomogeneous oils, some analyses like kinematic viscosity and stability index caimot be applied due to possible phase-separation of oil during viscosity determination. 

An important conclusion of the above approximate Analysis is that the effective kinematic viscosity of the emulsion is the dominant factor determining both the initial growth of instabilities and the most sensitive wave number. Thus, prediction of the effect of system properties on bubble stability depends on prediction of the effect on the effective kinematic... 

The authors propose an internal cyclizatlon via stepwise reaction to 1,4 diradical intermediates for which the closure step will be kinematically controlled. The observation that the 1,5 diene undergoes crossed cycloaddition while 1,6- and 1,7— dimers add "straight" can be interpreted in terms of strain, entropy effects, and radical stabilization. 

Shear stability Sequence VIll, ASTM D 10 h stripped KV at 100°C Kinematic viscosity must remain in original ... 

Increased kinematic viscosity v increases the stability of the flow. This role of viscous effects is fundamentally distinct from the preceding examples, in which the inclusion of viscosity was found to modify the growth rates of unstable disturbances, but not to modify the conditions for linear instability. 

The experimental evidence of the role of liquid viscosity in determining nonaqueous foam stability has been provided by several researchers. Brady and Ross (2) found that the foam stability of refined mineral oils increased linearly with kinematic viscosity. McBain and Robinson (5) showed that a high bulk liquid viscosity was often associated with high foam stability. Callaghan and Neustadter (4) measured the foam stability of crude oil foams and reported that the average lifetimes of such foams are almost linearly dependent on bulk viscosity. 

The various stabilities of complexes, the formation of an acidic front in the soil, and the unknown sorption/desorption processes of phenanthrene in the presence of heavy metals and kinematics of these processes necessitated the creation of eight experimental systems. Therefore, each electrokinetic cell (from Cl to C8), representing a different system, has introduced a new contribution to the entire experiment. Subsequently, each system had a different sequence of conditioning liquids supply and time of contaminant removal. 

Severin, I, Eberhardt, E., Leoni, L. Fortin, S. Use of ground-Based Synthetic Aperture Radar to Investigate Complex 3-d Pit Slope Kinematics. International Symposium on Rock Slope Stability in Open pit Mining and Civil Engineering, 2011 Vancouver. 

Ye and co-workers exploited the shear stability of highly branched, high molecular weight polyethylenes (PEs) as lubricant viscosity index improvers [252, 253]. Viscosity index of a lubricant is a critical parameter which defines its quality and application temperature range. They synthesized PEs with controllable chain topologies ranging from linear to a hyperbranched dendritic structure by chain walking polymerization [254]. The PE samples were blended into a base paraffinic oil (density 0.8659 g mL at 15 °C, kinematic viscosity 30.06 cST at 40 °C) to form lubricants. The lubricants were subjected to the Kurt Orbahn (KO) test to measure the shear stability index, which is expressed by... 

The time-domain methods enable a very realistic prediction of the behavior of the machine tool, since the effective kinematics of the machining process as well as nonlinear effects (e.g., tool jumping) are taken into account (Totis 2009). Adversely, such simulations cause a lot of computation time, due to the high complexity. Furthermore, the identification of the whole stability lobe diagram requires its complete simulation for each combination of process parameters. To determine the limit of stability, changes of the vibration response or of the force amplitudes are detected during each run of simulation. 

---