TIPS model

Figure 9.5 Capillary forces vs. geometry, (a) Sketch of the modeled tip geometry and water meniscus, (b-f) Calculated adhesion force vs. humidity for different values of the tip apex form factor b/a [b/a = 25,1, 0.2, 0.04, and 0.01, respectively] and the ellipsoid transverse semiaxis a. In fb] the results for a quasi-conical tip [bja = 25, a = 5 nm] are shown for different aperture angles v. In (c-f] the solid lines are results for tips with v = 10° and different a values. In (f) the dashed line corresponds to a quasi-truncated tip with 0 = 5 nm and v = 30°. (Reprinted figure with permission from Ref 30, copyright 2010, Wiley]...

KLEIN - You utilize the primitive model and experimental bulk water dielectric constant to normalize your potential of mean force calculations. Would it not be more natural to use the value of the dielectric constant appropriate to your water model (TIP P) How could this affect your results ... 

Fig. 215. Ni(NHjCSNHj)2(NCS)2-Plot of log[(3k/2Nii )x T] against 1/T(one-dimensional Ising model). TIP taken as 340 -10" emu/mole. The broken line corresponds to 3/k=69 K and g=2.14 in emu/mole,...

The parameters of five representative and commonly used water models in MD simulations are listed in Table 52.1. SPC is the short term for simple point charge, and SPC/E denotes the extended simple point charge model with charges on the oxygen and hydrogen modified to improve the classical SPC water model, the SPC/E model results in a better density and diffusion constant than the SPC model. TIP in TlPnP stands for transferable intermolecular potential, while nP means there are n points used in the corresponding water model. 

When a negatively charged species adsorbs on a surface, the electron motion has the opposite direction. Similar effects have been found in modelling tip-surface interactions (Castanier, 1995). 

FULL 3D INJECTION MOLDING ANALYSIS AND MODELING TIPS... 

Carpick et al [M] used AFM, with a Pt-coated tip on a mica substrate in ultraliigh vacuum, to show that if the defonnation of the substrate and the tip-substrate adhesion are taken into account (the so-called JKR model [175] of elastic adliesive contact), then the frictional force is indeed proportional to the contact area between tip and sample. Flowever, under these smgle-asperity conditions, Amontons law does not hold, since the statistical effect of more asperities coming into play no longer occurs, and the contact area is not simply proportional to the applied load. 

Nassehi, V. and Ghoreishy, M. H. R., 2001. Modelling of mixing in internal mixers with long blade tips. Adv. Polym. TechnoL 20, 132-145. 

Fig. 4. (a) The crack tip plastic zone and (b) the Dugdale plastic zone model. Terms are defined in text. 

The criterion of maintaining equal power per unit volume has been commonly used for dupHcating dispersion qualities on the two scales of mixing. However, this criterion would be conservative if only dispersion homogeneity is desired. The scale-up criterion based on laminar shear mechanism (9) consists of constant > typical for suspension polymerization. The turbulence model gives constant tip speed %ND for scale-up. 

Correlations of nucleation rates with crystallizer variables have been developed for a variety of systems. Although the correlations are empirical, a mechanistic hypothesis regarding nucleation can be helpful in selecting operating variables for inclusion in the model. Two examples are (/) the effect of slurry circulation rate on nucleation has been used to develop a correlation for nucleation rate based on the tip speed of the impeller (16) and (2) the scaleup of nucleation kinetics for sodium chloride crystalliza tion provided an analysis of the role of mixing and mixer characteristics in contact nucleation (17). Pubhshed kinetic correlations have been reviewed through about 1979 (18). In a later section on population balances, simple power-law expressions are used to correlate nucleation rate data and describe the effect of nucleation on crystal size distribution. 

Advances have been made in directly measuring the forces between two surfaces using freshly cleaved mica surfaces mounted on supports (15), and silica spheres in place of the sharp tip of an atomic force microscopy probe (16). These measurements can be directly related to theoretical models of surface forces. 

Rietz disintegrators are normally supplied in rotor diameters from 10 to 60 cm (4 to 24 in), with rotational speeds to produce hammer tip speeds in ranges of 300 to 6700 m/min (1000 to 22,000 ft/min) and power ranges from 0.4 to 1.50 kW (V2 to 200 hp). Higher speeds and higher power are available. AC variable-frequency drives can eliminate belts and provide easier variation of speed. Models are available... 

MECHANICAL EQUIPMENT Fans Number Type or Model Manufacturer Diameter, ft. Number of Blades Fan Speed, RPM Tip Speed, FPM BHP per fan, driver output Blade Material Hub Material Total Static Pressure, in. HjO Velocity Pressure, in. H2O Air Delivery per Fan, ACFM Fan Static Efficiency ... 

Fig. 6. Lateral stiffness vs. load data for a silicon nitride tip vs. mica surface in ultra-high vacuum. Solid line is fit of the JKR model to the data. Reprinted with pennission from ref. [67].

Fig. 7. Voigt model analysis of (a) lateral contact stiffness and (b) the response time, t, for a silicon nitride tip vs. poly(vinylethylene) as a function of frequency and polymer aging times. Reprinted with permission from ref [71].

We have recently been exploring this technique to evaluate the adhesive and mechanical properties of compliant polymers in the form of a nanoscale JKR test. The force and stiffness data from a force-displacement curve can be plotted simultaneously (Fig. 13). For these contacts, the stiffness response appears to follow the true contact stiffness, and the curve was fit (see [70]) to a JKR model. Both the surface energy and modulus can be determined from the curve. Using JKR analyses, the maximum pull off force, surface energy and tip radius are... 

Depth-sensing nanoindentation is one of the primary tools for nanomechanical mechanical properties measurements. Major advantages to this technique over AFM include (1) simultaneous measurement of force and displacement (2) perpendicular tip-sample approach and (3) well-modeled mechanics for dynamic measurements. Also, the ability to quantitatively infer contact area during force-displacement measurements provides a very useful approach to explore adhesion mechanics and models. Disadvantages relative to AFM include lower force resolution, as well as far lower spatial resolution, both from the larger tip radii employed and a lack of sample positioning and imaging capabilities provided by piezoelectric scanners. 

---