We introduce a parameter space for periodic point sets, given as a union of m translates of a point lattice. In it we investigate the behavior of the sphere packing density function and derive sufficient conditions for local optimality. Using these criteria we prove that perfect, strongly eutactic lattices cannot be locally improved to yield a denser periodic sphere packing. This in particular ...

PATRICK BARDSLEY†, LAJOS HORVÁTH‡, PIOTR KOKOSZKA§ AND GABRIEL YOUNG‖ †Institute for Computational Engineering and Sciences, University of Texas, Austin TX, USA. E-mail: [email protected] ‡Department of Mathematics, University of Utah, Salt Lake City UT, USA. E-mail: [email protected] §Department of Statistics, Colorado State University, Fort Collins CO, USA. E-mail: Piotr.Kokoszka@c...

This Letter is concerned with the determination of the transition paths attendant to nanovoid growth in aluminum under hydrostatic tension. The analysis is, therefore, based on energy minimization at 0 K. Aluminum is modeled by the Ercolessi-Adams embedded-atom method, and spurious boundary artifacts are mitigated by the use of the quasicontinuum method. Our analysis reveals several stages of p...

A crystalline solid exhibits thermally induced localised non-affine droplets in the absence of external stress. Here we show that upon an imposed shear, the size of these droplets grow until they percolate at a critical strain, well below the value at which the solid begins to yield. This critical point does not manifest in most thermodynamic or mechanical properties, but is hidden and reveals ...

Tree mapping grammars are used in natural language generation (NLG) to map non-linguistic input onto a derivation tree from which the target text can be trivially read off as the terminal yield. Such grammars may consist of a large number of rules. Finding errors is quite tedious and sometimes very time-consuming. Often the generation fails because the relevant input subtree is not specified co...

Neutralization of Acidic Sulfur Species by Calcite in Mineral Aerosols Collected in China and Japan Studied by Ca K-Edge X-Ray Absorption Near-Edge Structure Spectroscopy X-ray absorption near-edge structure studies at the calcium K-edge have been used to show that acidic sulfur species in the atmosphere (e.g., H2SO4), mainly released by human activities, can be neutralized by the calcite prese...

today, environment protection and safe crop production are very important. the management of soil elements by bio-fertilizers is considered as important point for sustainable agriculture. mode of action of fertilizers is very different in drought stress conditions. to evaluate biological fertilizers (agrohumic, nitroxin, superabsorbent and vermicompost) and compare them with current chemical fe...

olive oil is one of the oldest known vegetable oils, ranking sixth in world production. since it is extractedfrom fresh fruit and used without aging, the conditions of oil production are very important. during theextraction of virgin olive oil, the milling and malaxation steps are vital for increasing oil yield and quality.in this study, the effect of milling (single or double), temperature of ...

to assess the effect of non chemical management of weed control on forage sorghum (sorghum bicolor) a field study was conducted in varamin, iran during 2010 crop year in a three- replicated- split factorial experiment laid out in randomized complete block design with four weeding levels (w1= one time cultivation at 3-leaf stage using a duck foot cultivator, w2= two times cultivation at 3 and 5-...

lactide was synthesized by reverse polymerization of low molecular weight poly(lactic acid) with two different molecular weights:1500 and 2500. two different lactide purification processes such as: recrystallization in ethyl acetate and washing the crude lactide with ether before recrystallization in ethyl acetate were evaluated. it has been demonstrated that increasing the molecular weight of ...