Non-modal analysis of spectral element methods: Towards accurate and robust large-eddy simulations

We introduce a \textit{non-modal} analysis technique that characterizes the diffusion properties of spectral element methods for linear convection-diffusion systems. While strictly speaking only valid for linear problems, the analysis is devised so that it can give critical insights on two questions: (i) Why do spectral element methods suffer from stability issues in under-resolved computations of nonlinear problems? And, (ii) why do they successfully predict under-resolved turbulent flows even without a subgrid-scale model? The answer to these two questions can in turn provide crucial guidelines to construct more robust and accurate schemes for complex under-resolved flows, commonly found in industrial applications. For illustration purposes, this analysis technique is applied to the hybridized discontinuous Galerkin methods as representatives of spectral element methods. The effect of the polynomial order, the upwinding parameter and the P\'eclet number on the so-called \textit{short-term diffusion} of the scheme are investigated. From a purely non-modal analysis point of view, polynomial orders between $2$ and $4$ with standard upwinding are well suited for under-resolved turbulence simulations. For lower polynomial orders, diffusion is introduced in scales that are much larger than the grid resolution. For higher polynomial orders, as well as for strong under/over-upwinding, robustness issues can be expected. The non-modal analysis results are then tested against under-resolved turbulence simulations of the Burgers, Euler and Navier-Stokes equations. While devised in the linear setting, our non-modal analysis succeeds to predict the behavior of the scheme in the nonlinear problems considered

Selection of bioantagonistic bacteria to be used in biological control of Rhizoctonia solani in tomato

http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602011000100002&lng=es&nrm=isoBacteria from the rhizoplane and surrounding soil of healthy and Rhizoctonia solani diseased tomato plants, cropped in greenhouse of the V Region of Chile, were collected. The best bacterial strains, based on their ability to control development of three R. solani isolates (identified as belonging to the anastomosis groups AG-2-1, AG-4), were identified as B. subtilis (one isolate) and B. lentimorbus (two different isolates). All bacterial isolates resulted effective for the in vitro control of growth of all R. solani isolates, where the control mechanisms used by the bacteria do not involve the secretion of fungal cell wall hydrolytic enzymes. R. solani AG-2-1 was more sensitive than R. solani AG-4. On the other hand, all bacteria grew well in conditions similar to those that can be found at the field level (considering pH, salinity, Fe3+ and temperature) and showed a good capacity of tomato root colonization. These results suggest that the B. subtilis and B. lentimorbus isolates studied have an excellent potential to be used as biocontrol agents of R. solani in tomato greenhouses at the field level

Hardware-software model co-simulation for GPU IP development

This Master's thesis project aims to explore the possibility of a mixed simulation environment in which parts of a software model for emulating a hardware design may be swapped with their corresponding RTL description. More specifically, this work focuses on the sofware model for Arm's next-generation Mali GPU, which is used to understand system on chip properties, including functionality and performance. A component of this model (written in C++) is substituted with its hardware model (written in SystemVerilog) to be able to run simulations in a system context at a faster emulation speed, and with higher accuracy in the results compared to a pure-software model execution. For this, a "co-simulation" environment is developed, using SystemVerilog's DPI-C as the main communication interface between C++ and SystemVerilog. The proposed environment contains new software and hardware blocks to enable the desired objective without major modifications in neither the software Mali model nor the substituted component. Metrics and results for characterizing this co-simulation environment are also provided, namely timing accuracy, data correctness and simulation time with respect to other previously available simulation options. These results hope to show that the proposed environment may open new use-cases and improve development and verification time of hardware components in a system such as the Mali GPU.The possibility of combining hardware designs and software in the same simulation environment opens new options and improves significantly the flexibility of verification processes as well as characterization time of electronic designs. A practical method to realize this is developed and presented in this work for the case of a real Graphics Processing Unit IP. Nowadays electronics designers and manufacturers compete in an increasingly faster race to be able to provide the best and most efficient solutions to the market's expectations. The easiest example is the tendency of smartphone designers to provide a brand-new mobile phone model every year to meet consumers' demand. To meet these tighter and tighter deadlines, these companies need to find new ways of designing and verifying their products faster and more efficiently. In this context enters the work presented in this thesis: One of many possible solutions to improve the verification time of a hardware unit/block. Digital electronic circuits are commonly designed and modelled using Hardware Design Languages (HDLs), which are similar to computer languages such as C or Java, but different in the sense that HDLs actually describe the physical layout and connections of a digital circuit. These HDL designs can be simulated to verify their correct performance and characteristics with very high detail but, at the same time, this type of simulations are costly in terms of computational time and resources, due to the nature of the magnitudes and mechanisms being replicated on the computer running the simulation. On the other hand, software is written in computer languages directly, compiled to machine language and run sequentially by computers, in a much faster and efficient manner. Therefore, what if the best of the two could be combined to simulate a digital design in which only a specific internal block is described in a HDL while the rest of the design is a software program? This would allow to reduce the simulation time of that block greatly, while at the same type preserve the accuracy that a simulation of a HDL design can provide. This thesis work is based on a specific part of Arm's next-generation Mali Graphics Processing Unit (GPU), for which a solution for mixing hardware and software in the same simulation is proposed. For this specific case, such mechanism will allow to improve the development and testing time of new features for a Mali hardware IP, while at the same time open new use-cases for future work in this direction

A new model of Port Safety Management: The analysis and risk management based on the Formal Safety Assessment (FSA)

The present study aims to create a new model of port safety management in our country based on the analysis and assessment of the risk with the Formal Safety Assessment methodology to make it a first level instrument in the planning of the safety management of Port safety and also maritime port emergencies.Postprint (published version

Perspectiva del negocio marítimo para la próxima década

Postprint (author’s final draft

El Salvamento maritimo y el derecho humanitario

El presente estudio pretende analizar la crisis de las operaciones de salvamento realizado por ONGs y su adecuación al derecho internacional. Igualmente se estudia la acción de los estados a la luz del Derecho del Mar, el Derecho Marítimo y el derecho Humanitario.El presente estudio pretende analizar la crisis de las operaciones de salvamento realizado por ONGs y su adecuación al derecho internacional. Igualmente se estudia la acción de los estados a la luz del Derecho del Mar, el Derecho Marítimo y el derecho Humanitario.Preprin

Biocontrol of root and crown rot in tomatoes under greenhouse conditions using Trichoderma harzianum and Paenibacillus lentimorbus. Additional effect of solarization

Indexación: ScieloTrichoderma harzianum 650 (Th650) and Paenebacillus lentimorbus 629 (Pl629) selected earlier for their ability to control Rhizoctonia solani, Fusarium solani and F. oxysporum in vitro, were applied alone or combined with solarization (summer assay) and/or with methyl bromide (MeBr) (summer and winter assays) to a soil with a high inoculum level, for the control of tomato root rot caused by the complex F. oxysporum f. sp. lycopersici - Pyrenochaeta lycopersici - Rhizoctonia solani. Evaluations were also performed independently for root damage caused by P. lycopersici, and also for R. solani in the summer assay. MeBr decreased tomato root damage caused by the complex from 88.7% to 21.2% and from 78.4% to 35.7% in the summer and in the winter assay, respectively. None of the bio-controllers could replace MeBr in the winter assay, but Th650 and Pl629 reduced root damage caused by this complex in the summer assay. Treatments with bio-controllers were improved by their combination with solarization in this season. Independent evaluations showed that the positive control of Th650 towards R. solani and the lack of effect on P. lycopersici correlates well with the endochitinase pattern expressed by Th650 in response to these phytopathogens. Root damage caused by R. solani can be controlled at a similar level as it does MeBr in summer assays, thus representing an alternative to the use of this chemical fungicide for the control of this phytopathogen.Financial support: Fondecyt 1990785

las emergencias marítimas: el "sin modelo español": reflexiones después de la tormenta

La perspectiva de España como Estado ribereño, en el que se suceden y sucederán importantes y graves siniestros marítimos, dada la intensidad de los tráficos marítimos, especialmente con mercancías peligrosas, justifican el tratamiento riguroso y con estándares internacionales de las emergencias marítimas como un objetivo prioritario e irrenunciable. Nuestro país presenta un histórico de desastres realmente notable: POLYCOMANDER (1970); ERKOWIT (1970); URQUIOLA (1976); ANDROS PATRIA (1978);); CASON (1987); AEGEAN SEA (1992); ROBERT MAERSK (1993); PRESTIGE (2002); OSTEDJIK (2007). El propósito de este artículo, en línea con anteriores pronunciamientos personales sobre la cuestión, es hacer una breve reflexión sobre la falta de un modelo para gestionar con eficiencia las emergencias marítimas, una carencia que los recientes siniestros del SORRENTO y el OLEG NAYDENOV han puesto de nuevo en evidencia.Preprin