Optimal Control Problems with Mixed and Pure State Constraints

This paper provides necessary conditions of optimality for optimal control problems, in which the pathwise constraints comprise both “pure” constraints on the state variable and “mixed” constraints on control and state variables. The proofs are along the lines of earlier analysis for mixed constraint problems, according to which Clarke's theory of “stratified” necessary conditions is applied to a modified optimal control problem resulting from absorbing the mixed constraint into the dynamics; the difference here is that necessary conditions which now take into account the presence of pure state constraints are applied to the modified problem. Necessary conditions are given for a rather general formulation of the problem containing both forms of the constraints, and then these are specialized to problems having special structure. While combined pure state and mixed control/state problems have been previously treated in the literature, the necessary conditions in this paper are proved under less restrictive hypotheses and for novel formulations of the constraints

Bioconversion of cellulosic biomass wastes by Azorean hot spring bacterial consortia

ECO-BIO 2016Enzymatic hydrolysis of cellulose is a fundamental step in the carbon cycle and in the industrial bioconversion of biomass to biofuels. In nature cellulose hydrolysis is often catalysed by enzymes from complex microbial communities, nevertheless these studies are limited to a few isolates. Actually the production of biofuels from biomass became a necessity and novel pre-treatments are mandatory to be discovered. Thereby the study of cellulose hydrolysing bacterial communities is a step in achieving a sustainable future in biofuels development. We propose the stabilization of an aerobic thermophilic bacterial consortia (BC) with the ability to adapt and hydrolyse different cellulose-rich wastes. Decaying cellulosic residues were sampled inside Azorean hot springs. Samples were enriched in cellulosic selective medium at 60ºC with growth monitored quantifying DNA. Hydrolysis efficiency was monitored and enzymatic activity was detected using xylan and carboxymetylcellulose (CMC). 16S rRNA hypervariable regions V3/V4 were amplified for phylogenetic characterization of BC using 454 pyrosequencing. Selected BC was able to hydrolyse 50% of cellulose-rich plant mix material in 4 days. Besides hydrolysing low content lignin material as non-wood plants, newspaper and cardboard, the consortia was able to hydrolyse high lignin content material, with lower efficiency. Celulase and xylanase were present in BC and reducing sugars were shown to be higher, compared with control. The phylogenetic results showed a large diversity in the BC with Thermobacillus representing 44% of the consortia, followed by Symbiobacterium 25%, Brevibacillus 16%, Geobacillus 12% and Hipomicrobium 3%. Three Geobacillus species were identified; G. stearothermophilus, G.thermodenitrificans and G.debilis. Further work will comply the isolation of enzyme producing bacteria isolates from the consortia for the construction of new consortia taking in consideration the efficiency of cellulose rich wastes. These results suggest that bacterial communities can be an alternative pre-treatment method of green wastes to obtain molecules to biofuels production.info:eu-repo/semantics/publishedVersio

Universal Critical Behavior of Aperiodic Ferromagnetic Models

We investigate the effects of geometric fluctuations, associated with aperiodic exchange interactions, on the critical behavior of $q$-state ferromagnetic Potts models on generalized diamond hierarchical lattices. For layered exchange interactions according to some two-letter substitutional sequences, and irrelevant geometric fluctuations, the exact recursion relations in parameter space display a non-trivial diagonal fixed point that governs the universal critical behavior. For relevant fluctuations, this fixed point becomes fully unstable, and we show the apperance of a two-cycle which is associated with a novel critical behavior. We use scaling arguments to calculate the critical exponent $\alpha$ of the specific heat, which turns out to be different from the value for the uniform case. We check the scaling predictions by a direct numerical analysis of the singularity of the thermodynamic free-energy. The agreement between scaling and direct calculations is excellent for stronger singularities (large values of $q$). The critical exponents do not depend on the strengths of the exchange interactions.Comment: 4 pages, 1 figure (included), RevTeX, submitted to Phys. Rev. E as a Rapid Communicatio

Bayesian analyses of five gene regions reveal a new phylogenetic species of Macrophomina associated with charcoal rot on oilseed crops in Brazil.

Macrophomina is a genus belonging to Botryosphaeriaceae that comprises well-known necrotrophic pathogens related to hundreds of plant hosts around the world. Historically, M. phaseolina is the causal agent of charcoal rot in several crops, mainly in tropical and subtropical areas around the world. However, after a recent genetic diversity study using morphological and molecular approaches, which resulted in the epitypification of M. phaseolina, and the description of a new Macrophomina species associated with charcoal rot disease, the hypothesis that other cryptic species could be present under the name M. phaseolina was raised. Previous studies in Brazil revealed a high genetic diversity and different levels of aggressiveness of M. phaseolina isolates associated with charcoal rot in oilseed crops. Thus, the aim of the present study was, through phylogenetic and morphological studies, to determine if isolates of Macrophomina obtained from different oilseed crops represent a single species or distinct taxa. Based on the results obtained, it was possible to identify three different Macrophomina species: M. phaseolina, M. pseudophaseolina and a new phylogenetic species, M. euphorbiicola. This is first report of M. pseudophaseolina in Brazil causing charcoal rot on Arachis hypogaea, Gossypium hirsutum and Ricinus communis and associated with seed decay of Jatropha curcas. In addition, a novel species described in the present study, M. euphorbiicola, is reported as the etiological agent of the charcoal rot on R. communis and Jatropha gossypifolia

Characterization of traditional raw materials used in housing construction in Huambo Region - Angola

The sustainability of buildings associated to the use of raw earth has motivated the studies and the development of techniques and methods in the context of this type of construction. In the region of Huambo, Angola, these construction techniques are widely used, especially for low-income families who represent the majority of the population. Much of the buildings in Huambo province are built with adobe. Due to the climate in this region, subtropical, hot and humid, with altitudes above 1000 meters and extensive river system, these buildings are particularly vulnerable to the action of water and develop, in many situations, early degradation. The Huambo Province is located in central Angola, has 36 km2 area and approximately 2 million inhabitants. This work aims to evaluate, by conducting in-situ tests, physical and mechanical properties of adobe blocks typically used in the construction of those buildings. The methodology is based on field campaigns where in-situ expeditious tests were performed in soils (smell test, color, touch, brightness, sedimentation, ball, hardness, etc.) and tests on adobes blocks made with traditional procedures, particularly in terms of durability and erodibility (erosion test at Geelong method; evaluation test of wet / dry cycle, applying the New Zealand standards 4297: 1998; 4297: 1998 and 4297: 1999). The results will contribute to the characterization of the geomaterials and methods used in construction with earth in Huambo Province, contributing to the improvement of these sustainable solutions, with a strong presence in this region. The results of this study will also contribute to the proposal of constructive solutions with improved performance characteristics, comfort, safety and durability

Soil mineralogical composition effects on the durability of adobe blocks from the Huambo region, Angola

After many years of war, great efforts have been made for the socio-economic development of Angola, particularly in the construction industry. Among the construction techniques, adobe is one of the most used in the province of Huambo, especially by low-income families, which constitute the majority. This technique was established as an intangible heritage in the culture of that population. Huambo province is located in the central region of Angola (Central Plateau). Adobe blocks are building elements with potential degradation by the action of water. Due to the subtropical climate, hot and humid, and geomorphology of the province, located at about 1000–2000 m of altitude and with an extensive river system, these buildings can be vulnerable and may present premature degradation, exacerbated by the lack of knowledge concerning the properties of the geomaterials used and techniques/solutions that allow their stabilization and conservation. This paper aims to present the main results of the study to investigate the influence on adobe performance in regard to the mineralogy and geochemistry of soils used in the production of adobes used in the construction of dwellings. The knowledge gained with this research can support the development of solutions for the common anomalies and problems in this construction, as well as to improve the strength and durability of the adobe units. For this purpose, soil samples were collected and mineralogical, geochemical, and physical tests were performed. Durability and erodibility tests were also performed on selected adobes, following the Geelong method. The results obtained with this research may contribute to the development of the knowledge concerning this sustainable building solution, which has a strong presence in the province of Huambo and neighbouring regions.FCT - UID/GEO/04035/201