Deadwood Decay in a Burnt Mediterranean Pine Reforestation

Dead wood remaining after wildfires represents a biological legacy for forest regeneration, and its decay is both cause and consequence of a large set of ecological processes. However, the rate of wood decomposition after fires is still poorly understood, particularly for Mediterranean-type ecosystems. In this study, we analyzed deadwood decomposition following a wildfire in a Mediterranean pine plantation in the Sierra Nevada Natural and National Park (southeast Spain). Three plots were established over an elevational/species gradient spanning from 1477 to 2053 m above sea level, in which burnt logs of three species of pines were experimentally laid out and wood densities were estimated five times over ten years. The logs lost an overall 23% of their density, although this value ranged from an average 11% at the highest-elevation plot (dominated by Pinus sylvestris) to 32% at an intermediate elevation (with P. nigra). Contrary to studies in other climates, large-diameter logs decomposed faster than small-diameter logs. Our results provide one of the longest time series for wood decomposition in Mediterranean ecosystems and suggest that this process provides spatial variability in the post-fire ecosystem at the scale of stands due to variable speeds of decay. Common management practices such as salvage logging diminish burnt wood and influence the rich ecological processes related to its decay.This study was supported by Project 10/2005 from the Organismo Autónomo de Parques Nacionales (Spanish Government), CGL2008-01671 from the Spanish Ministerio de Ciencia e Innovación, and P12-RNM-2705 from Junta de Andalucía. A.B.L. acknowledges funding from Juan de la Cierva grant by Ministerio de Economía y Competitividad (FJCI-2015-23687). C.R.M-G. had a Ph.D. grant from the National University of Asunción (Paraguay) and Carolina Foundation (Spain)

Effects of Post-Fire Deadwood Management on Soil Macroarthropod Communities

Dead wood comprises a vast amount of biological legacies that set the scene for ecological regeneration after wildfires, yet its removal is the most frequent management strategy worldwide. Soil-dwelling organisms are conspicuous, and they provide essential ecosystem functions, but their possible affection by different post-fire management strategies has so far been neglected. We analyzed the abundance, richness, and composition of belowground macroarthropod communities under two contrasting dead-wood management regimes after a large wildfire in the Sierra Nevada Natural and National Park (Southeast Spain). Two plots at different elevation were established, each containing three replicates of two experimental treatments: partial cut, where trees were cut and their branches lopped off and left over the ground, and salvage logging, where all the trees were cut, logs were piled, branches were mechanically masticated, and slash was spread on the ground. Ten years after the application of the treatments, soil cores were extracted from two types of microhabitat created by these treatments: bare-soil (in both treatments) and under-logs (in the partial cut treatment only). Soil macroarthropod assemblages were dominated by Hemiptera and Hymenoptera (mostly ants) and were more abundant and richer in the lowest plot. The differences between dead-wood treatments were most evident at the scale of management interventions: abundance and richness were lowest after salvage logging, even under similar microhabitats (bare-soil). However, there were no significant differences between microhabitat types on abundance and richness within the partial cut treatment. Higher abundance and richness in the partial cut treatment likely resulted from higher resource availability and higher plant diversity after natural regeneration.This study was supported by Project 10/2005 from the Organismo Autónomo de Parques Nacionales (Spanish Government), CGL2008–01671 from the Spanish Ministerio de Ciencia e Innovación, and P12-RNM-2705 from Junta de Andalucía. Programa Nacional de incentivo a investigadores (PRONII) and Programa de vinculación de científicos y tecnólogos from Comisión Nacional de Ciencia y Tecnología (Paraguay). A.B.L. acknowledges a postdoctoral grant from the Alexander von Humboldt Foundation. C.R.M-G. had a Ph.D. grant from the National University of Asunción (Paraguay) and Carolina Foundation (Spain)

An investigation on corrosion protection layers in pipelines transporting hydrocarbons

Chemical reactions between carbon steel, water and chemical species produce corrosion layers (scales) on the internal surface of pipelines transporting hydrocarbons. Scales act as a diffusion barrier and prevent the progress of corrosion, a dangerous failure initiator. The protective film (10-100 m thickness) can be removed locally by the action of the internal flow, or by other mechanisms. Adhesion with the substrate and the failure modes of the corrosion layer can be tested by indentation. Some results are presented of experiments performed on specimens with scales grown in a controlled environment

Dynamic Simulation Methods for Evaluating Motor Vehicle and Roadway Design and Resolving Policy Issues

This study had three objectives: (1) to develop a comprehensive truck simulation that executes rapidly, has a modular program construction to allow variation of vehicle characteristics, and is able to realistically predict vehicle motion and the tire-road surface interaction forces; (2) to develop a model of doweled portland cement concrete pavement that can be used to determine slab deflection and stress at predetermined nodes, and that allows for the variation of traditional thickness design factors; and (3) to implement these two models on a work station with suitable menu driven modules so that both existing and proposed pavements can be evaluated with respect to design life, given specific characteristics of the heavy vehicles that will be using the facility. This report summarizes the work that has been performed during the first year of the study. Briefly, the following has been accomplished: A two dimensional model of a typical 3-S2 tractor-trailer combination was created. A finite element structural analysis program, ANSYS, was used to model the pavement. Computer runs have been performed varying the parameters defining both vehicle and road elements. The resulting time specific displacements for each node are plotted, and the displacement basin is generated for defined vehicles. Relative damage to the pavement can then be estimated. A damage function resulting from load replications must be assumed that will be reflected by further pavement deterioration. Comparison with actual damage on Interstate 80 will eventually allow verification of these procedures

Dynamics of unvisited sites in presence of mutually repulsive random walkers

We have considered the persistence of unvisited sites of a lattice, i.e., the probability $S(t)$ that a site remains unvisited till time $t$ in presence of mutually repulsive random walkers. The dynamics of this system has direct correspondence to that of the domain walls in a certain system of Ising spins where the number of domain walls become fixed following a zero termperature quench. Here we get the result that $S(t) \propto \exp(-\alpha t^{\beta})$ where $\beta$ is close to 0.5 and $\alpha$ a function of the density of the walkers $\rho$. The number of persistent sites in presence of independent walkers of density $\rho^\prime$ is known to be $S^\prime (t) = \exp(-2 \sqrt{\frac{2}{\pi}} \rho^\prime t^{1/2})$. We show that a mapping of the interacting walkers' problem to the independent walkers' problem is possible with $\rho^\prime = \rho/(1-\rho)$ provided $\rho^\prime, \rho$ are small. We also discuss some other intricate results obtained in the interacting walkers' case.Comment: 6 pages, 7 figure

SISTEMI DI ACCUMULO DI IDROGENO AD IDRURI DI MAGNESIO: VERIFICA SPERIMENTALE DEGLI EFFETTI DI SCALA

CESI RICERCA ha in corso un programma di ricerca per valutare le potenzialità di sistemi di accumulo di idrogenobasati su idruri di magnesio in applicazioni stazionarie. L’attività è effettuata con la collaborazione del GruppoIdrogeno dell’Università di Padova e con Venezia Tecnologie. A partire da materiali sviluppati da UNIPD e VETEC,CESI RICERCA ha progettato, realizzato e sperimentato serbatoi di accumulo di capacità diversa al fine di valutare leprestazioni del sistema in termini di capacità totale di accumulo, cinetica di absorbimento e desorbimento di idrogenoed analizzare l’eventuale degrado a valle di cicli di carica e scarica di idrogeno. In particolare, per valutare gli effettidi scala (scale-up), che sono della massima importanza in applicazioni industriali, CESI RICERCA ha progettatoe sperimentato in differenti condizioni operative un sistema di accumulo contenente 0.5 kg di idruro di magnesio.La sperimentazione sull’accumulatore ha riguardato l’attivazione delle polveri e l’esecuzione di una serie di ciclidi absorbimento e desorbimento di idrogeno; i dati sperimentali sono stati confrontati con risultati di laboratorio.L’accumulatore ha presentato una capacità massima di accumulo di idrogeno in peso del 5.35%; gli effetti di scalasono stati evidenziati da una cinetica più lenta, da sensibili effetti termici locali e da un degrado delle prestazionidopo alcuni cicli di carica e scarica di idrogeno. Al fine di identificare le cause del degrado delle prestazioni, sono stateeffettuate ulteriori attività sperimentali su accumulatori di taglia ridotta (circa 30 grammi di polvere) sviluppandoe testando nuove configurazioni degli accumulatori tali da minimizzare gli effetti negativi legati allo scale-up delsistema

WARM UP LUBE SYSTEM (WULS) RELATION BETWEEN A NEW APPROACH TO LUBRICATION DURING START-UP PHASES AND THE THERMAL SHOCK ON THE DIE SURFACE AND SCRAP REDUCTION

The continuous research for efficiency, associated with higher and higher quality standards in the different industrial production processes, has led, in the last few years, to further and more exhaustive analysis of the various machine cycle phases in the light alloy diecasting sector. The result of these studies was the development of new interdisciplinary technologies, which have firstly highlighted, and then solved “chronic” inefficiencies during the start-up phases. Today, the WULS system is able to optimize the Warm Up phase, being based on the die surface temperature value (thanks to the C.T.C. - acquisition module) and retroacting on the lubrication equipment. In this paper the authors present the WULS technology and highlight the existing relation between the Warm Up phase and the thermal shock generated on the die surface, emphasizing its high level of influence. It has been well shown by means of several tests in an Italian foundry that WULS technology, together with a specific warm-up phase lubricant, ensure: - decreasing thermal shock (approx. 66% of reduction in temperature drop) - reduction of scrap pieces during production starting (approx. - 50%)