Light-related variation in sapling architecture of three shade-tolerant tree species of the Mexican rain forest

The crown architecture of three shade-tolerant tree species (two subcanopy and one mid-canopy) was analyzed in relation to the light regime of the forest understorey. The aim was to examine to which extent shade-tolerant species variate in their crown architecture. Tree saplings (265) between 50 and 300 cm height, and distributed from understorey to variously-sized canopy gaps, were measured for 13 architectural traits in the lowland rain forest of Los Tuxtlas, Mexico. The analysis showed that the three species changed their architecture as light increased but in a different way. No species conformed to the typical wide-crown type expected for shade-tolerant species, and in contrast they presented some traits of light demanding species. The two sub-canopy species tended to adopt a crown form between a narrow- and wide-crown type, and the mid-canopy species showed more traits of a narrow-crown type. The horizontal crown area appeared as the more related trait to the light and sapling height. It is concluded that despite being shade-tolerant, the Studied species make use of better-lit environments in the forest understorey. The crown architecture of shade-tolerant species is not Lis rigid Lis originally conceived

Using Uppaal for the secure and optimal control of AGV fleets

The design and realization of an on line control system for automated guided vehicles (AGV) is addressed. A synthesis method is proposed based on the use of the model checking tool for timed automata Uppaal. This system has to route the vehicles while ensuring the system safeness, a good coordination between vehicles and the optimization of performance criteria.This problem is like synthesizing a Ramadge and Wonham supervisor combined with routing and optimizing functions, that is an ongoing problem within the supervisory control theory. The proposed concepts are validated through a software tool suite based on Uppaal in order to generate optimal traces and interact with an AGV system emulated with Arena

Comparison of Microstructures and Mechanical Properties for Solid Cobalt-Base Alloy Components and Biomedical Implant Prototypes Fabricated by Electron Beam Melting

The microstructures and mechanical behavior of simple, as-fabricated, solid geometries (with a density of 8.4 g/cm3), as-fabricated and fabricated and annealed femoral (knee) prototypes all produced by additive manufacturing (AM) using electron beam melting (EBM) of Co-26Cr-6Mo-0.2C powder are examined and compared in this study. Microstructures and microstructural issues are examined by optical metallography, SEM, TEM, EDS, and XRD while mechanical properties included selective specimen tensile testing and Vickers microindentation (HV) and Rockwell C-scale (HRC) hardness measurements. Orthogonal (X-Y) melt scanning of the electron beam during AM produced unique, orthogonal and related Cr23C6 carbide (precipitate) cellular arrays with dimensions of ~2μm in the build plane perpendicular to the build direction, while connected carbide columns were formed in the vertical plane, parallel to the build direction.Mechanical Engineerin

Microstructure Architecture Development in Metals and Alloys By Additive Manufacturing Using Electron Beam Melting

The concept of materials with controlled microstructural architecture (MCMA) to develop and fabricate structural materials with novel and possibly superior properties and performance characteristics is a new paradigm or paradigm extension for materials science and engineering. In the conventional materials science and engineering paradigm, structure (microstructure), properties, processing, and performance features are linked in the development of desirable materials properties and performance through processing methodologies which manipulate microstructures. For many metal or alloy systems, thermomechanical treatment combining controlled amounts of plastic deformation with heat treatment or aging cycles can achieve improved mechanical properties beyond those attainable by conventional processing alone (such as rolling or forging for example) through controlled microstructure development. In this paper we illustrate a new concept involving the fabrication of microstructural architectures by the process development and selective manipulation of these microstructures ideally defining material design space. This allows for the additional or independent manipulation of material properties by additive manufacturing (AM) using electron beam melting (EBM). Specifically we demonstrate the novel development of a carbide (M23C6) architecture in the AM of a Co-base alloy and an oxide (Cu2O) precipitate-dislocation architecture in the AM of an oxygen-containing Cu. While more conventional processing can produce various precipitate microstructures in these materials, EBM produces spatial arrays of precipitate columns or columnar-like features often oriented in the build direction. These microstructural architectures are observed by optical microscopy and scanning and transmission electron microscopy. Prospects for EBM architecture development in precipitation-hardenable Al alloys is also discussed. In the EBM build process using precursor powders, the electron beam parameters (including beam focus, scan speed and sequencing) produce localized, requisite thermodynamic regimes which create or organize the precipitate-related spatial arrays. This feature demonstrates the utility of AM not only in the fabrication of complex components, but also prospects for selective property design using CAD for MCMA development: a new or extended processing-microstructure-property-performance paradigm for materials science and engineering in advanced manufacturing involving solid free-form fabrication (SFF).Mechanical Engineerin

Are galaxy distributions scale invariant? A perspective from dynamical systems theory

Unless there is evidence for fractal scaling with a single exponent over distances .1 <= r <= 100 h^-1 Mpc then the widely accepted notion of scale invariance of the correlation integral for .1 <= r <= 10 h^-1 Mpc must be questioned. The attempt to extract a scaling exponent \nu from the correlation integral n(r) by plotting log(n(r)) vs. log(r) is unreliable unless the underlying point set is approximately monofractal. The extraction of a spectrum of generalized dimensions \nu_q from a plot of the correlation integral generating function G_n(q) by a similar procedure is probably an indication that G_n(q) does not scale at all. We explain these assertions after defining the term multifractal, mutually--inconsistent definitions having been confused together in the cosmology literature. Part of this confusion is traced to a misleading speculation made earlier in the dynamical systems theory literature, while other errors follow from confusing together entirely different definitions of ``multifractal'' from two different schools of thought. Most important are serious errors in data analysis that follow from taking for granted a largest term approximation that is inevitably advertised in the literature on both fractals and dynamical systems theory.Comment: 39 pages, Latex with 17 eps-files, using epsf.sty and a4wide.sty (included) <[email protected]

Fisheries and reproductive biology of Octopus vulgaris (Mollusca: Cephalopoda) in the Gulf of Alicante (Northwestern Mediterranean)

The common octopus Octopus vulgarisCuvier, 1797 is the most fished cephalopod species along the Spanish coasts. Its catches are highly fluctuating due to the short life cycle of the species and to the annual variability of the recruitment pattern, strongly dependent on the environmental conditions affecting the eggs and paralarvae. This study examines the common octopus fishery, the catch composition, and the main features of the reproductive biology of this species in the Gulf of Alicante (Spanish Eastern coast, Western Mediterranean FAO division 37.1.1). The common octopus fishery was studied analysing the monthly landing and effort data by fishing gear from 1994 to 2005. Monthly samplings of the commercial O. vulgarislandings from trawlers and clay pots from January 2004 to December 2005 resulted in the measuring of 1833 specimens to enable analysis of the catch composition, and allowed the biological sampling of 1176 individuals to provide the reproductive parameters of the species in the study area. The length-weight relationship calculated for the species was BW = 0.51 * DML 2.87. The yearly sex ratios (males:females) were 1:1 (trawl, 2004), 1:0.74 (trawl, 2005), and 1:0.88 (clay pots, 2005). The size (dorsal mantle length, DML) at maturity of the species in the study area was 9.67 cm for males and 14.38 cm for females. The gonadosomatic index reached a peak between April and July for males and in July for females. The Fulton condition index was lower in both sexes between June and September, and for males in November-December, whereas for both sexes the values of the digestive gland index were at their maximum between June and December. The energy allocation between somatic and reproductive growth was investigated and the results suggested that the energy spent on reproduction mainly came from feeding, and not from energy stored in the mantle tissues or in the digestive glan

On the continuous contract verification using blockchain and real-time data

Supply chains play today a crucial role in the success of a company&#39;s logistics. In the last years, multiple investigations focus on incorporating new technologies to the supply chains, being Internet of Things (IoT) and blockchain two of the most recent and popular technologies applied. However, their usage has currently considerable challenges, such as transactions performance, scalability, and near real-time contract verification. In this paper we propose a model for continuous verification of contracts in supply chains using the benefits of blockchain technology and real-time data acquisition from IoT devices for early decision-making. We propose two platform independent optimization techniques (atomic transactions and grouped validation) that enhances data transactions protocol and the data storage procedure and a method for continuous verification of contracts, which allows to take corrective actions to reduce ¿This work has been partially supported by the project “CABAHLA-CM: Convergencia Big data-Hpc: de los sensores a las Aplicaciones” S2018/TCS-4423 from Madrid Regional Government and by the Spanish Ministry of Science and Innovation Project “New Data Intensive Computing Methods for High-End and Edge Computing Platforms (DECIDE)”. Ref. PID2019-107858GB-I00

Facile production of stable silicon nanoparticles: laser chemistry coupled to in situ stabilization via room temperature hydrosilylation

Stable, alkyl-terminated, light-emitting silicon nanoparticles have been synthesized in a continuous process by laser pyrolysis of a liquid trialkyl-silane precursor selected as a safer alternative to gas silane (SiH4). Stabilization was achieved by in situ reaction using a liquid collection system instead of the usual solid state filtration. The alkene contained in the collection liquid (1-dodecene) reacted with the newly formed silicon nanoparticles in an unusual room-temperature hydrosilylation process. It was achieved by the presence of fluoride species, also produced during laser pyrolysis from the decomposition of sulfur hexafluoride (SF6) selected as a laser sensitizer. This process directly rendered alkyl-passivated silicon nanoparticles with consistent morphology and size (<3 nm), avoiding the use of costly post-synthetic treatments