Radar Altimetry Aids Managing Gauge Networks

The hydrological observation network in the Amazon basin is made of conventional rainfall and water level stations presently maintained by the Agência Nacional de Águas (ANA), the National Agency for Waters. The water level network has long been plagued by difficulties associated with spatial coverage, timely delivery and data errors. Satellite observations are important means for providing hydrologic data with acceptable spatial and temporal resolution, and radar altimeters embarked onboard successive satellites since the early 1970s collect measurements of water level over rivers in a well-defined geodetic reference frame and can be used to address some of these problems. Nowadays, satellite altimetry can be used to collect the time variations of the water levels over many rivers throughout the word, as long as the reach are several hundred meters wide. This ability is particularly interesting in ungauge basins but it can also be used as an independent source of information to cross-check existing gauge series. In the present study, we focus on examples from the Amazon basin where radar altimetry has been used to provide an independent dataset that can be used to support the management of hydrological observation networks by including new data together with conventional field data,     

A single-phase model for liquid-feed DMFCs with non-Tafel kinetics

An isothermal single-phase 3D/1D model for liquid-feed direct methanol fuel cells (DMFC) is presented. Three-dimensional (3D) mass, momentum and species transport in the anode channels and gas diffusion layer is modeled using a commercial, finite-volume based, computational fluid dynamics (CFD) software complemented with user supplied subroutines. The 3D model is locally coupled to a one-dimensional (1D) model accounting for the electrochemical reactions in both the anode and the cathode, which provides a physically sound boundary condition for the velocity and methanol concentration fields at the anode gas diffusion layer/catalyst interface. The 1D model – comprising the membrane–electrode assembly, cathode gas diffusion layer, and cathode channel – assumes non-Tafel kinetics to describe the complex kinetics of the multi-step methanol oxidation reaction at the anode, and accounts for the mixed potential associated with methanol crossover, induced both by diffusion and electro-osmotic drag. Polarization curves computed for various methanol feed concentrations, temperatures, and methanol feed velocities show good agreement with recent experimental results. The spatial distribution of methanol in the anode channels, together with the distributions of current density, methanol crossover and fuel utilization at the anode catalyst layer, are also presented for different opperating conditions.     

Operating experience from the ehecatl wind turbines

This paper presents a summary of the mechanical features and the medium term operating experience from three small horizontal axis wind energy conversion systems covering a range of 500 to 5000 Watt, intented for rural and isolated communities. These turbines have a new regulator which reduces gyroscopic loads, is easy to adjust and could be manufactured stronger and in smaller sizes than the conventional tail vanes. It is concluded that is feasible to build cheaps and reliable wind turbine generators with an acceptable efficiency employing common-use elements, but is needed a careful and optimized design.     

Modification of vermiculite by polymerization and carbonization of glycerol to produce highly efficient materials for oil removal

Impregnation and reaction of glycerol (Gly) on the surface of expanded vermiculite (EV) was used to produce a highly efficient absorbent to remove water spilled oils. The vermiculite was impregnated by glycerol containing 1, 2 and 4 mol% of H₂SO₄ at EV/Gly ratios, i.e. 1/1, 1/2 and 1/3, and heated to 380, 580 and 750 °C. SEM, TG, BET specific surface area, and Raman analyses indicated that glycerol at 380 °C forms a polymer layer. At higher temperatures, the polymer decomposed to form porous carbon covering the EV surface. These materials were investigated for the removal of three different oils, i.e. diesel, soybean and engine oil spilled on water. The obtained results showed a remarkable increase on oil removal of 600% compared to the non-modified EV.     

Influence of EVA and acrylate polymers on some mechanical properties of cementitious repair mortars

In repair works of reinforced concrete, patch repairs tend to crack in the interfacial zone between the mortar and the old concrete. This occurs basically due to the high degree of restriction that acts on a patch repair. For this reason, the technology of patch repair needs to be the subject of a discussion involving professionals who work with projects, construction maintenance and mix proportioning of repair mortars. In the present work, a study is presented on the benefits that the ethylene vinyl acetate copolymer (EVA) and acrylate polymers can provide in the mix proportioning of a repair mortar with respect to compressive, tensile and direct-shear bond strength. The results indicated that the increase in bond strength and the reduction in the influence of the deficiency in curing conditioning are the main contributions offered by the polymers studied here.     

Sustainability metrics for eco-technologies assessment, Part II. Life cycle analysis

This work presents a sustainability analysis of CO₂ reuse to produce dimethyl carbonate (DMC) via ethylene oxide (ROUTE A) and via urea methanolysis (ROUTE B). Two different technologies are considered in ROUTE A: reaction followed by separation and reactive distillation. Life cycle analyses of the ROUTES are presented employing sustainability analysis performed in HYSYS process simulator, along with WAR Algorithm. Process economical optimization is performed to maximize the processes profitability. A sustainability function, defined as a 2D indicator involving both economical and environmental aspects, is calculated for the optimized processes. Additional sustainability indexes are evaluated: material index, energy index, and ecoefficiency. The results, under both economical and environmental aspects, show that ROUTE A is the most sustainable. The study also points to the relevance of the frontier set between the domains cradle-to-gate and gate-to-gate in assessing process sustainability during LCA.     

Physicochemical Investigation of the Reaction of Components of the Si — Al — O — N — Ti System in the Si3N4 — Al2O3 — AlN — SiO2 — TiN — TiO2 Region. Part 2. Subsystems Si3N4 — AlN,TiN — AlN,Al2O3 — AlN

The reaction of components of the Si — Al — O — N — Ti system in its elements Si ₃N₄ — AlN, TiN — AlN, and Al ₂O ₃ — AlN was investigated by differential thermal and x-ray diffraction analysis. It was established that upon hot pressing mixtures of Si₃N ₄ and AlN (up to 1950°C) free silicon is formed by the decomposition of Si ₃N₄, which reacts with oxygen present as an impurity to form SiO. When TiN reacts with AlN a phase with the spinel structure (Al₂₃O ₂₇N ₅), which can form only in the presence of excess oxygen, appears in addition to the initial components. Spinel is also produced by the reaction of Al ₂O₃ with AlN. In this case a eutectic between Al ₂₃O₂₇N₅ and Al₂O₃ is observed.     

Exploiting Narrow Values for Soft Error Tolerance

Soft errors are an important challenge in contemporary microprocessors. Particle hits on the components of a processor are expected to create an increasing number of transient errors with each new microprocessor generation. In this paper we propose simple mechanisms that effectively reduce the vulnerability to soft errors In a processor. Our designs are generally motivated by the fact that many of the produced and consumed values in the processors are narrow and their upper order bits are meaningless. Soft errors canted by any particle strike to these higher order bits can be avoided by simply identifying these narrow values. Alternatively soft errors can be detected or corrected on the narrow values by replicating the vulnerable portion of the value inside the storage space provided for the upper order bits of these operands. We offer a variety of schemes that make use of narrow values and analyze their efficiency in reducing soft error vulnerability of level-1 data cache of the processor     

Analysis of quality-of-service in a wide-area interactive distance learning system

Interactive distance learning (IDL) is an evolving paradigm of instruction and learning that attempts to overcome both distance and time constraints found in traditional classroom learning. The electronic classrooms at two sites of the University of Oslo and two further sites in Norway overcome separations in space by exchanging digital audio, video, and whiteboard information via the Norwegian academic ATM-based network Supernett II. The electronic classrooms are used since 1993 for teaching graduate level courses. This paper presents measurements and analysis results of transport, application, and user level Quality-of-Service (QoS) of the electronic classrooms. We describe our general experiences with this system for synchronous IDL. The lessons learned represent the motivation for the ongoing extension to support asynchronous IDL by a multimedia database system (MMDBS) to manage all data used and generated in the electronic classrooms.     

Advances in the purification of the mitochondrial Ca2+ uniporter using the labeled inhibitor 103Ru360

Seasonal affective disorder (SAD) is characterized by annual major depressive episodes. It occurs most commonly in young women during autumn and winter with full remission during the following spring. The patient's mood is a combination of depression and anxiety accompanied by fatigue, loss of libido, and a reduction of socialization. Most of these patients complain of atypical vegetative symptoms (e.g. hypersomnia, carbohydrate craving, and weight gain). Hypotheses on the underlying mechanisms of these behavioural disorders indicate that environmental variables, e.g. climate, latitude, light, and changes in neurotransmitter function that occur naturally with the seasons, may be important. Phototherapy is being used increasingly for the treatment of SAD. The antidepressant response is contingent on the exposure of the patients' eyes to light. The biological basis of the diverse psychological and biological changes in SAD and the underlying mechanism of action of phototherapy are still unclear and require further study.