A divide-and-conquer/cellular-decomposition framework for million-to-billion atom simulations of chemical reactions

To enable large-scale atomistic simulations of material processes involving chemical reactions, we have designed linear-scaling molecular dynamics (MD) algorithms based on an embedded divide-and-conquer (EDC) framework: first principles-based fast reactive force-field (F-ReaxFF) MD; and quantum-mechanical MD in the framework of the density functional theory (DFT) on adaptive multigrids. To map these O(N) algorithms onto parallel computers with deep memory hierarchies, we have developed a tunable hierarchical cellular-decomposition (THCD) framework, which achieves performance tunability through a hierarchy of parameterized cell data/computation structures and adaptive load balancing through wavelet-based computational-space decomposition. Benchmark tests on 1920 Itanium2 processors of the NASA Columbia supercomputer have achieved unprecedented scales of quantum-mechanically accurate and well validated, chemically reactive atomistic simulations—0.56 billion-atom F-ReaxFF MD and 1.4 million-atom (0.12 trillion grid points) EDC–DFT MD—in addition to 18.9 billion-atom non reactive space–time multiresolution MD. The EDC and THCD frameworks expose maximal data localities, and consequently the isogranular parallel efficiency on 1920 processors is as high as 0.953. Chemically reactive MD simulations have been applied to shock-initiated detonation of energetic materials and stress-induced bond breaking in ceramics in corrosive environments.     

An inpainting-based deinterlacing method.

Video is usually acquired in interlaced format, where each image frame is composed of two image fields, each field holding same parity lines. However, many display devices require progressive video as input; also, many video processing tasks perform better on progressive material than on interlaced video. In the literature, there exist a great number of algorithms for interlaced to progressive video conversion, with a great tradeoff between the speed and quality of the results. The best algorithms in terms of image quality require motion compensation; hence, they are computationally very intensive. In this paper, we propose a novel deinterlacing algorithm based on ideas from the image inpainting arena. We view the lines to interpolate as gaps that we need to inpaint. Numerically, this is implemented using a dynamic programming procedure, which ensures a complexity of O(S), where S is the number of pixels in the image. The results obtained with our algorithm compare favorably, in terms of image quality, with state-of-the-art methods, but at a lower computational cost, since we do not need to perform motion field estimation.     

Electrodialytic remediation of copper mine tailings

Mining activities in Chile have generated large amounts of solid waste, which have been deposited in mine tailing impoundments. These impoundments cause concern to the communities due to dam failures or natural leaching to groundwater and rivers. This work shows the laboratory results of nine electrodialytic remediation experiments on copper mine tailings. The results show that electric current could remove copper from watery tailing if the potential gradient was higher than 2 V/cm during 21 days. With addition of sulphuric acid, the process was enhanced because the pH decreased to around 4, and the copper by this reason was released in the solution. Furthermore, with acidic tailing the potential gradient was less than 2 V/cm. The maximum copper removal reached in the anode side was 53% with addition of sulphuric acid in 21 days experiment at 20 V using approximately 1.8 kg mine tailing on dry basis. In addition, experiments with acidic tailing show that the copper removal is proportional with time.     

Supervised machine learning using encrypted training data

International Journal of Information Security - Preservation of privacy in data mining and machine learning has emerged as an absolute prerequisite in many practical scenarios, especially when the...     

Specimen geometry and specimen size dependence of the $${mathcal {}}$$-curve and the size effect law from a cohesive model point of view

The directionality of electromagnetic radiation from tensile fracturing is calculated within our previously proposed model and shown to agree with experimental observations in the field. The best locations and orientations of measuring antennas are presented.     

Catalytic properties of carbon materials for wet oxidation of aniline

A mesoporous carbon xerogel with a significant amount of oxygen functional groups and a commercial activated carbon, were tested in the catalytic wet air oxidation of aniline at 200 degrees C and 6.9 bar of oxygen partial pressure. Both carbon materials showed high activity in aniline and total organic carbon removal, a clear increase in the removal efficiency relatively to non-catalytic wet air oxidation being observed. The best results in terms of aniline removal were obtained with carbon xerogel, an almost complete aniline conversion after 1h oxidation with high selectivity to non-organic compounds being achieved. The materials were characterized by thermogravimetric analysis, temperature programmed desorption, N(2) adsorption and scanning electron microscopy, in order to relate their performances to the chemical and textural characteristics. It was concluded that the removal efficiency, attributed to both adsorption and catalytic activity, is related to the mesoporous character of the materials and to the presence of specific oxygen containing functional groups at their surface. The effect of catalytic activity was found to be more important in the removal of aniline than the effect of adsorption at the materials surface. The results obtained indicate that mesoporous carbon xerogels are promising catalysts for CWAO processes.     

Planning and the Challenges of the Metropolitan Landscape: Innovation in the Netherlands

The physical appearance of the Netherlands is rapidly changing. The land of prosperous towns and villages embedded in rich, flat and open agricultural land is turning into a metropolis. A distinctive quality of this metropolis is the mix of highly urbanized centres and open, green areas that come in different shapes and sizes. But how to design an appropriate planning system for this environment? Mixing “red” (urban) and “green” (rural) land uses, for instance, now becomes problematic as Dutch spatial planning has always focused primarily on the urban domain whereas planning of green areas has its origins in agricultural land consolidation policy. A genuinely integrated approach to the planning of built-up areas and green areas in the open spaces is a distant ideal in this setting. In addition, the regional administrative level, being so important for metropolitan spatial challenges, needs reinforcing. The authors make a plea for a reframing of the notion of spatial planning at the national and provincial geographical and administrative scale. It takes a new object for planning, design and analysis to do the trick. The traditional rural–urban opposition is traded for “metropolitan landscape”, a new image reflecting the integration of built-up and non-built-up distinctively urban and rural land uses. Planning for the metropolitan landscape requires a reassignment of duties and responsibilities among national, provincial and municipal governments and other stakeholders.     

The resistance to detachment of dairy strains of Listeria monocytogenes from stainless steel by shear stress is related to the fluid dynamic characteristics of the location of isolation

Strains of Listeria monocytogenes isolated from artisanal Portuguese cheese-making dairies were divided into two categories on the basis of the locations from which they were isolated: strains from dynamic locations were those that were habitually exposed to flowing liquids during the process of cheese-making, whereas those from static locations were rarely, if ever, exposed to the shear stresses generated by liquid flows. The strength of attachment to stainless steel discs of all of these strains was obtained using a radial flow chamber. Initial attachment strengths to stainless steel (after a 0.5 h contact time) of L. monocytogenes strains were greater for the 5 isolates from surfaces exposed to flow (dynamic isolates) than for most (3 out of 4) of those that were not (static isolates). After a 24 h contact time, attachment strength of all isolates reached similar levels. These results suggest that strains having high initial attachment strength are more likely to persist on surfaces exposed to flow than strains having low initial attachment strength. The numerical values of shear forces obtained could prove useful in the rational design of cleaning and decontamination procedures in food processing facilities.     

Vertical (La,Sr)MnO3 Nanorods from Track‐Etched Polymers Directly Buffering Substrates

A novel and general methodology for preparing vertical, complex‐oxide nanostructures from a sol–gel‐based polymer‐precursor solutions is developed using track‐etched polymers directly buffering substrates. This method is able to develop a nanostructure over the entire substrate, the dimensions and localization of the vertical nanostructures being preset by the polymeric nanotemplate. Thereby, nanostructures with lateral sizes in the range of 100 to 300 nm and up to 500 nm in height have been grown. Two examples are presented herein, the latter being the evolution of the initial, metastable nanostructure. Specifically, La_0.7Sr_0.3MnO₃ polycrystalline rods are grown at mild temperatures (800 °C); upon strong thermal activation (1000 °C) they suffer a profound transformation into vertical, single‐crystalline (La,Sr)_xO_y nanopyramids sitting on a La_0.7Sr_0.3MnO₃ epitaxial wetting layer. The driving force for this outstanding nanostructural evolution is the minimization of the total energy of the system, which is reached by reducing the grain‐boundary, total‐surface, and strain‐relaxation energies. Finally, advanced electron‐microscopy techniques are used to highlight the complex phase separation and structural transformations occurring when the metastable state is overcome.