A surrogate-based cooperative optimization framework for computationally expensive black-box problems

Optimization and Engineering - Most parallel surrogate-based optimization algorithms focus only on the mechanisms for generating multiple updating points in each cycle, and rather less attention...     

Degradation of alachlor and pyrimethanil by combined photo-Fenton and biological oxidation

Biodegradability of aqueous solutions of the herbicide alachlor and the fungicide pyrimethanil, partly treated by photo-Fenton, and the effect of photoreaction intermediates on growth and DOC removal kinetics of the bacteria Pseudomonas putida CECT 324 are demonstrated. Toxicity of 30–120 mg L⁻¹ alachlor and pyrimethanil has been assayed in P. putida. The biodegradability of photocatalytic intermediates found at different photo-treatment times was evaluated for each pesticide. At a selected time during batch-mode phototreatment, larger-scale biodegradation kinetics were analysed in a 12 L bubble column bioreactor. Both alachlor and pyrimethanil are non-toxic for P. putida CECT 324 at the test concentrations, but they are not biodegradable. A 100 min photo-Fenton pre-treatment was enough to enhance biodegradability, the biological oxidation response being dependent on the pesticide tested. The different alachlor and pyrimethanil respiration and carbon uptake rates in pre-treated solutions are related to change in the growth kinetics of P. putida. Reproducible results have shown that P. putida could be a suitable microorganism for determining photo-Fenton pre-treatment time.     

n-CdS/p-ZnIn2Se4 thin film solar cell

The photovoltaic behaviour of a CdS/ZnIn₂Se₄ vacuum-evaporated thin film solar cell is reported for the first time. Because of the band gap of ZnIn₂Se₄ (1.93 eV) this combination of semiconductor materials seems to be suitable for use as one of the junctions in tandem solar cell configurations. Uncoated cells exhibited efficiencies of the order of 1.5% under an illumination of 100 mW cm^-2.     

Color encoding for polychromatic single-channel optical pattern recognition

The common multichannel system for recognizing colored images is replaced by a color-encoded single-channel system. Amethod inspired by the Munsell color system is used for encoding the different colors as phase and amplitude functions. It is shown that for many practical cases the phase information part of the color code is sufficient for obtaining good results. An implementation based on a liquid-crystal television panel that works in a phase-modulation mode is suggested. Computer simulations that demonstrate the capabilities of the suggested method are given as well as a comparison with previously published multichannel performance.     

Biodegradation of oxadiazon by a soil isolated Pseudomonas fluorescens strain CG5: Implementation in an herbicide removal reactor and modelling

An oxadiazon-degrading bacterial, Pseudomonas strain CG5, was isolated from an agricultural contaminated soil. This strain CG5 was able to grow on 10mg of oxadiazon per l, yielding 5.18+/-0.2 mg of protein biomass mol(-1). GC-MS analyses of the metabolites from oxadiazon catabolism revealed its dehalogenation and degradation to form non-toxic end-products, cells were then immobilized by adsorption on a ceramic support to be used as biocatalysts in herbicide removal biofilm-reactor processes. Seventy-two per cent of the oxadiazon was removed, and the maximum specific substrate uptake rate was 10.63+/-0.5 microg h(-1) mg(-1) prot. A new mathematical model was developed to interpret and predict the behaviour of the bacteria and pollutants in a biofilm-reactor system, to consider biofilm structural and morphological properties.     

North–South transfers vs biodiversity conservation: a trade differential game

Trade relationships connect developed and developing countries. The former produces a consumption good, using labor, capital, and an intermediate “natural” good which is produced in the developing countries using labor and natural species. A finite horizon differential game is settled out. The North decides about either the saving rate or the portion of its disposable income to transfer to the South or both variables jointly. The South selects the range of species used in the production of the intermediate “natural” good required in the North’s productive process. This is a measure of biodiversity loss. The aim of the paper is to study how transfers from North to South affect capital growth and biodiversity conservation.

Effects of two chelating agents (EDTA and DTPA) on the autochthonous vegetation of a soil polluted with Cu, Zn and Cd

Chelating agents are thought to be useful for the remediation of metal-polluted soils with adequate organic matter, but the effects of these substances on the plants or seed bank of plant communities that occur in the soils are relatively unknown. In this work, the effects of two chelating substances (EDTA and DTPA) on a wet grassland plant community affected by the presence of the abandoned copper mine "Fernandito" (Garganta de los Montes, Madrid) were compared. A microcosm bioassay (6 months) was designed using the soil's top layer containing the grassland's seed bank. This soil showed a high Cu pollution level, significant contents of Zn and Cd (1120, 190, and 15 ppm, respectively), a pH of 5 and an OM content of 6.2%. The soil was subjected to three different treatments: a) untreated soil (control), b) the addition of 1 g/kg EDTA, or of c) 1 g/kg DTPA. The results presented here are those related to the plant cover, species richness, aboveground and subterranean biomass and chemical composition of the most abundant plants. Neither EDTA nor DTPA caused intense negative effects on the plants rather they significantly increased the amount of copper accumulated in aboveground parts and roots. In particular, Agrostis castellana and Corrigiola telephiifolia extracted high amounts of copper when grown in the soil with added EDTA, although they showed some nutritional imbalances (lower P contents). In contrast, lower metal concentrations were detected in plants grown in the DTPA amended soil.     

A new analytical–experimental method for the identification of stability lobes in high-speed milling

Increased working speeds and accelerations of high-speed machining produce excitation of oscillations and cause dynamic problems. These problems affect the tool life (tool wear and tool failure), produce shoddy end surface, reduce productivity, produces scrap parts and affect the environment. A chatter’s analytical prediction method was combined with experimental multidegree-of-freedom systems modal analysis to achieve the objective of generating a new method to obtain the stability lobes information. This paper describes the development of this new method which obtains the stability information for some vibration modes that can be used to graph the stability lobes for high-speed milling, and these to help in the selection of parameters for chatter free operations. Some tests were carried out to demonstrate the quality of this method and the accomplishment of the proposed goals.     

Microstructure and properties of TiB/Ti-6Al-4V coatings produced with laser treatments

TiB/Ti-6Al-4V metal-matrix composite (MMC) layers were produced on Ti-6Al-4V substrates by laser cladding. A TiB₂/Ti powder mixture was used as a precursor to obtain a dispersion of TiB needles in the Ti alloy matrix, with the aid of an exothermic reaction between TiB₂ and Ti. A eutectic microstructure was obtained that consisted of an extremely homogeneous dispersion of TiB eutectic needles in the Ti alloy matrix, having a volume fraction as high as 0.33. Also, an equilibrium-like microstructure was found, consisting of a dispersion of both primary and eutectic TiB needles inside the Ti alloy matrix. An analysis of the geometry of the layers was performed and proved successful in determining the percentage of B. Further, it correctly predicted the variation of atomic B content as a function of laser power. The relative wear resistance coefficient, defined as the wear coefficient of the uncoated matrix divided by that of coating, shows an improvement by a factor as high as 1500 for the eutectic microstructure. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appeared on pp. 411–18 of the Proceedings.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.