Global Regular Solutions to a Kelvin-Voigt Type Thermoviscoelastic System

A classical 3-D thermoviscoelastic system of Kelvin-Voigt type is considered. The existence and uniqueness of a global regular solution is proved without small data assumption. The existence proof is based on the successive approximation method. The crucial part constitute a priori estimates on an arbitrary finite time interval, which are derived with the help of the theory of anisotropic Sobolev spaces with a mixed norm.Comment: 52 page

The Effects of fluctuations in solid ink density on color variation for conventional and grey component replacement separations when printing process color on newsprint

A color separation technique known as Gray Component Replacement, or GCR has been an option available to high-end drum scanner operators for the past eight years. Recently, GCR has been made available by lower-end color system vendors as well. GCR consists of removing the least predominant process color ink in a unit area, reducing the remaining colored inks by the same amount and replacing the gray component of the color with black ink. One of the reported benefits of the GCR technique is that more consistency can be realized during a pressrun. If this is in fact true, the first publication printers who would surely utilize the technique would be newspapers. The problem of consistency is particularly acute for newspapers. There are a number of reasons for this, but the primary ones relate to the types of materials used. Newspapers use the cheapest paper and ink and in many cases, they print with old or poorly maintained presses. They would surely welcome any process that offered better reproductive quality and more consistency, provided the investment was justifiable. Since their present color separation systems allow for the use of GCR in the majority of cases, its potential in the area of newspaper printing was investigated in this study. One factor determining consistency during a pressrun is the control of ink film thickness. As ink film thickness fluctuates, color variation takes place. This study compared the amount of color variation realized for a conventional separation and GCR separations as ink film thickness was varied on press. A separation was made conventionally and with five levels of GCR (however only 40% and 80% could be used for analysis). A Macbeth color checker, comprised of twenty-four color patches, was used as the test target. Ink film thickness was varied to three fluctuation magnitudes. Twenty-five press sheets were chosen from the fluctuation cycles. A spectrophotometer was used to obtain color difference magnitude data (AE) between the ink variation sheets and a sheet with nominal solid ink densities for both the conventional and GCR separations. A mean AE value was tabulated for each group. The GCR mean values were compared to the conventional mean value. Using both the z-Statistic (for multi-sheet comparisons) and the Student\u27s t-Statistic (for single sheet comparisons) tests were performed to determine if the difference in color variation between the conventional separation and the GCR separations was significant statistically. The t-Tests indicated that less color variation was realized for the GCR separation if the level of GCR was substantial (80% as opposed to 40%). Where the data was deemed valid, no cases existed where less color variation was realized for the conventional separation. The initial z-Test (when the number of samples was 192) revealed less color variation for the GCR separations and higher color variation for the conventional separation. The final z-Test (including all sample press sheets) revealed much less color variation for the GCR separations compared to the conventional separation. The amount of color variation was higher for the GCR separations compared to the conventional separation only in cases where the black ink film thickness was varied. However, in these cases the difference between the conventional and GCR color variation means (mean AEs) revealed that the difference was not statistically significant

A Cahn-Hilliard equation with singular diffusion

In the present work, we address a class of Cahn-Hilliard equations characterized by a singular diffusion term. The problem is a simplified version with constant mobility of the Cahn-Hilliard-de Gennes model of phase separation in binary, incompressible, isothermal mixtures of polymer molecules. It is proved that, for any final time T, the problem admits a unique energy type weak solution, defined over (0,T). For any s > 0 such solution is classical in the sense of belonging to a suitable Hoelder class over (s,T), and enjoys the property of being separated from the singular values corresponding to pure phases

Free Energy Approach to the Formation of an Icosahedral Structure during the Freezing of Gold Nanoclusters

The freezing of metal nanoclusters such as gold, silver, and copper exhibits a novel structural evolution. The formation of the icosahedral (Ih) structure is dominant despite its energetic metastability. This important phenomenon, hitherto not understood, is studied by calculating free energies of gold nanoclusters. The structural transition barriers have been determined by using the umbrella sampling technique combined with molecular dynamics simulations. Our calculations show that the formation of Ih gold nanoclusters is attributed to the lower free energy barrier from the liquid to the Ih phases compared to the barrier from the liquid to the face-centered-cubic crystal phases

Molecular dynamics simulations of the dipolar-induced formation of magnetic nanochains and nanorings

Iron, cobalt and nickel nanoparticles, grown in the gas phase, are known to arrange in chains and bracelet-like rings due to the long-range dipolar interaction between the ferromagnetic (or super-paramagnetic) particles. We investigate the dynamics and thermodynamics of such magnetic dipolar nanoparticles for low densities using molecular dynamics simulations and analyze the influence of temperature and external magnetic fields on two- and three-dimensional systems. The obtained phase diagrams can be understood by using simple energetic arguments.Comment: 6 pages, 6 figure

Über die Schmelztemperatur der Körner des Salols

n/

Particle-size dependence of orbital order-disorder transition in LaMnO3

The latent heat (L) associated with the orbital order-disorder transition at T_JT is found to depend significantly on the average particle size (d) of LaMnO3. It rises slowly with the decrease in d down to ~100 nm and then jumps by more than an order of magnitude in between d ~ 100 nm and ~30 nm. Finally, L falls sharply to zero at a critical particle size d_c ~ 19 nm. The transition temperature T_JT also exhibits an almost similar trend of variation with the particle size, near d ~ 30 nm and below, even though the extent of variation is relatively small. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization versus temperature study over a temperature range 10-300 K reveals that the antiferromagnetic transition temperature decreases with d while the temperature range, over which the ZFC and FC data diverge, increases with the drop in d. The FC magnetization also is found to increase sharply with the drop in particle size. A conjecture of nonmonotonic variation in orbital domain structure with decrease in particle size - from smaller domains with large number of boundaries to larger domains with small number of boundaries due to lesser lattice defects and, finally, down to even finer domain structures with higher degree of metastability - along with increase in surface area in core-shell structure, could possibly rationalize the observed L versus d and T_JT versus d patterns. Transmission electron microscopy data provide evidence for presence of core-shell structure as well as for increase in lattice defects in finer particles.Comment: 26 pages including 5 figures; pdf only; accepted for publication in Phys. Rev.