Heisenberg-type higher order symmetries of superintegrable systems separable in cartesian coordinates

Heisenberg-type higher order symmetries are studied for both classical and quantum mechanical systems separable in cartesian coordinates. A few particular cases of this type of superintegrable systems were already considered in the literature, but here they are characterized in full generality together with their integrability properties. Some of these systems are defined only in a region of $\mathbb R^n$, and in general they do not include bounded solutions. The quantum symmetries and potentials are shown to reduce to their superintegrable classical analogs in the $\hbar \to0$ limit.Comment: 23 Pages, 3 figures, To appear in Nonlinearit

Effect of prior cold work on the mechanical properties of weldments

Heat exchanger units used in steam raising power plant are often manufactured using many metres of austenitic stainless steel tubes that have been plastically formed (bent and swaged) and welded into complex shapes. The amount of plastic deformation (pre-straining) before welding varies greatly. This has a significant effect on the mechanical properties of the welded tubes and on the final residual stress state after welding. The aim of the present work was to measure and understand the combined effects of pre-straining and welding on the properties and residual stress levels in stainless steel tubing weldments. Effects of plastic deformation were simulated by plastically straining three identical stainless steel tubes to different strain levels (0%, 10% and 20%). Then each tube was cut into two halves and welding back together. The variation in mechanical properties across weldments was measured using digital image correlation (DIC) and a series of strain gauges (SG). Residual stresses were measured on the 0% (undeformed) and 20% prestrained and welded tubes by neutron diffraction. It was found that the welding process had a marked effect on the tensile properties of parent material within 25mm of the weld centre-line. Evidence of cyclic strain hardening was observed in the tube that had not been pre-strained, and evidence of softening seen in the 10% and 20% pre-strained tubes. Macroscopic residual stresses were measured to be near zero at distances greater than 25 mm from the weld centre-line, but measurements in the 20% pre-strained tube revealed the presence of micro residual stresses having a magnitude of up to 50 MPa

Molecular-dynamics simulations of stacking-fault-induced dislocation annihilation in pre-strained ultrathin single-crystalline copper films

We report results of large-scale molecular-dynamics (MD) simulations of dynamic deformation under biaxial tensile strain of pre-strained single-crystalline nanometer-scale-thick face-centered cubic (fcc) copper films. Our results show that stacking faults, which are abundantly present in fcc metals, may play a significant role in the dissociation, cross-slip, and eventual annihilation of dislocations in small-volume structures of fcc metals. The underlying mechanisms are mediated by interactions within and between extended dislocations that lead to annihilation of Shockley partial dislocations or formation of perfect dislocations. Our findings demonstrate dislocation starvation in small-volume structures with ultra-thin film geometry, governed by a mechanism other than dislocation escape to free surfaces, and underline the significant role of geometry in determining the mechanical response of metallic small-volume structures.Comment: 28 pages, 3 figure

Translating the Word, Translating the World: A Closer Look into Translation in Adult Education Research

This paper outlines a proposed approach to the issue of translation in the instrument adaptation process in adult education field, and describes a design ensuring effective use of translators to achieve a translation that is appropriate and adequate for a given task

Natural plant revegetation on reclaimed coal mine landscapes in Agacli-Istanbul

In this study, natural vegetation development was compared on one abandoned open coal mine spoil and three reclaimed coal mine areas with umbrella pine-Pinus pinea L., maritime pine-Pinus pinaster Ait. and leguminous black locust-Robinia pseudoacacia L. in Agacli-Istanbul. Soil data of these sample areas were determined in previous studies. These properties demonstrate physically and nutritionally poor conditions and some rehabilitative effects after tree species were introduced. The plant species composition and total coverage for each species (vertical projection onto the ground) was estimated visually and recorded on each sample plot. Naturally revegetated plant species, species composition, Shannon-Wiener diversity index values, species richness, evenness, total abundance and their coverabundance scales were evaluated by comparing each other. Generally, the best-represented species belong to Rosaceae in all investigated plots. Shannon diversity index and its components give the different results among sample plots. However, higher values were found on reclaimed sites. Highest Shannon diversity index (H') was found on the sample area reclaimed with maritime pine. Plant species richness (S) was highest under umbrella pine and plant species evenness (J') was highest on black locust sample plot. Despite the sample area reclaimed, black locust has the more fertile soil conditions, it has only the highest plant species evenness (J') value among areas.Key words: Coal mine, plant composition, reclamation, revegetation, species richness, species diversit

OPTIMIZATION AT SERVICE VEHICLE ROUTING AND A CASE STUDY OF ISPARTA, TURKEY

A typical application area of vehicle routing problem (VRP) is School Bus Routing Problem. In this problem, mainly, it is aimed to minimize total service time, length, number of vehicles operating etc. and maximize the capacity utility etc. under some constraints such as allowable time etc. The aim of this study is to construct a method that helps to organize the travel plans of students residing in an area and to apply this method at a pilot school determined under some requirements. The results of the study suggested that there are differences in the sense of the distance, time, and number of stops on the route of the service vehicles while it can be said that there is equality only in capacity utility

Electromigration-Induced Propagation of Nonlinear Surface Waves

Due to the effects of surface electromigration, waves can propagate over the free surface of a current-carrying metallic or semiconducting film of thickness h_0. In this paper, waves of finite amplitude, and slow modulations of these waves, are studied. Periodic wave trains of finite amplitude are found, as well as their dispersion relation. If the film material is isotropic, a wave train with wavelength lambda is unstable if lambda/h_0 < 3.9027..., and is otherwise marginally stable. The equation of motion for slow modulations of a finite amplitude, periodic wave train is shown to be the nonlinear Schrodinger equation. As a result, envelope solitons can travel over the film's surface.Comment: 13 pages, 2 figures. To appear in Phys. Rev.

Nonisocyanate based polyurethane/silica nanocomposites and their coating performance

A series of silica nano-particles with different size were prepared by sol–gel technique, then surface modification by using cyclic carbonate functional organoalkoxysilane (CPS) was performed. Various amounts of carbonated silica particles directly added into carbonated soybean oil (CSBO) and carbonated polypropylene glycol (CPPG) resin mixture to prepare polyurethane–silica nanocomposite coating compositions by nonisocyanate route using an aliphatic diamine as a curing agent. Cupping, gloss, impact, and taber abrasion tests were performed on aluminum panels coated with those nano-composite formulations and tensile tests, thermogravimetric and SEM analyses were conducted on the free films prepared from the same coating formulations. An increase in abrasion resistance of CSBO-CPPG resin combination with the addition of silica was observed. In addition, the maximum weight loss of CSBO-CPPG resin combination was shifted to higher temperatures with incorporation of silica nano-particles The positive effect of modified silica particles on thermal stability of CSBO-CPPG system could be explained in such a way that PPG chains are able to disperse particles in the medium throughout the interactions between ether linkages and silanol groups

Forging a potent vaccine adjuvant: CpG ODN/cationic peptide nanorings

Cataloged from PDF version of article.Type I interferon inducers may potentially be engineered to function as antiviral and anticancer agents, or alternatively, vaccine adjuvants, all of which may have clinical applications. We recently described a simple strategy to convert a Toll-like receptor 9 (TLR9) agonist devoid of interferon alpha (IFN alpha) stimulating activity into a robust Type I interferon inducer with potent vaccine adjuvant activity