Constrained optimization by radial basis function interpolation for high-dimensional expensive black-box problems with infeasible initial points

This article develops two new algorithms for constrained expensive black-box optimization that use radial basis function surrogates for the objective and constraint functions. These algorithms are called COBRA and Extended ConstrLMSRBF and, unlike previous surrogate-based approaches, they can be used for high-dimensional problems where all initial points are infeasible. They both follow a two-phase approach where the first phase finds a feasible point while the second phase improves this feasible point. COBRA and Extended ConstrLMSRBF are compared with alternative methods on 20 test problems and on the MOPTA08 benchmark automotive problem (D.R. Jones, Presented at MOPTA 2008), which has 124 decision variables and 68 black-box inequality constraints. The alternatives include a sequential penalty derivative-free algorithm, a direct search method with kriging surrogates, and two multistart methods. Numerical results show that COBRA algorithms are competitive with Extended ConstrLMSRBF and they generally outperform the alternatives on the MOPTA08 problem and most of the test problems.     

Bioethanol production from bio‐ organosolv pulps of Pinus radiata and Acacia dealbata

Wood chips from Pinus radiata and Acacia dealbata were pretreated with the white‐rot fungi Ceriporiopsis subvermispora and Ganoderma australe, respectively, for 30 days at 27 °C and 55% relative humidity, followed by an organosolv delignification with 60% ethanol solution at 200 °C for 1 h to produce pulps with high cellulose and low lignin content. Biotreatment for 30 days was chosen based on low weight and cellulose losses (lower than 4%) and lignin degradation higher than 9%. After organosolv delignification, pulp yield for P. radiata and A. dealbata pulps was 45–49% and 31–51%, respectively. P. radiata bio‐pulps showed higher glucan (93%) and lower lignin content (6%) than control pulps (82% glucan and 13% lignin). A. dealbata bio‐pulps also showed higher glucan (95%) and lower lignin content (2%) than control pulps (92% glucan and 4% lignin). Pulp suspensions at 2% consistency were submitted either to separate enzymatic hydrolysis and fermentation (SHF) or simultaneous enzymatic saccharification and fermentation (SSF) for bioethanol production. The yeast Saccharomyces cerevisiae was used for fermentation. Glucan‐to‐glucose conversion in the enzymatic hydrolysis of control and bio‐pulps of P. radiata was 55% and 100%, respectively, and it was 100% for all pulp samples case of A. dealbata. The highest ethanol yield (calculated as percentage of theoretical yield) during SHF of P. radiata control and bio‐pulps was 38% and 55%, respectively, and for A. dealbata control and bio‐pulps 62% and 69%, respectively. The SSF of P. radiata control and bio‐pulps yielded 10% and 65% of ethanol, respectively, and 77% and 82% for A. dealbata control and bio‐pulps, respectively. In wood basis, the maximum conversion obtained (g ethanol per kg wood) in SHF was 37% and 51% (for P. radiata and A. dealbata pulps, respectively) and 44% and 65% in SSF (for P. radiata and A. dealbata pulps, respectively) regarding the theoretical yield. The low wood‐to‐ethanol conversion was associated with low pulp yield (A. dealbata pulps), high residual lignin amount (P. radiata pulps) and the low pulp consistency (2%) used for SHF and SSF. Copyright © 2007 Society of Chemical Industry     

Detection of herbicide subclasses by an optical multibiosensor based on an array of photosystem II mutants

Massive use of herbicides in agriculture over the last few decades has become a serious environmental problem. The residual concentration of these compounds frequently exceeds the maximum admissible concentration in drinking water for human consumption and is a real environmental risk for the aquatic ecosystem. Herbicides inhibiting photosynthesis via targeting photosystem II function still represent the basic means of weed control. A multibiosensor was constructed for detecting herbicides using as biosensing elements photosynthetic preparations coupled to an optical fluorescence transduction system (Giardi et al. EU patent EP1134585, 01830148.1-2204); this paper is about its application in the detection of herbicide subclasses in river water. Photosynthetic material was immobilized on a silicio septum inside a series of flow cells, close to diodes so as to activate photosystem II (PSII) fluorescence. The principle of the detection was based on the factthat herbicides selectively modify PSII fluorescence activity. The multibiosensor has the original feature of being able to distinguish the subclasses of the photosynthetic herbicides by using specific immobilized biomediators isolated from mutated organisms. This setup resulted in a reusable, portable multibiosensor for the detection of herbicide subclasses with a half-life of 54 h for spinach thylakoids and limit of detection of 3 x 10(-9) M for herbicides present in river water.     

Clustering Search for the Berth Allocation Problem

This work presents a new approach to the Berth Allocation Problem (BAP) for ships in ports. Due to the increasing demand for ships carrying containers, the BAP can be considered as a major optimization problem in marine terminals. In this paper, the BAP is considered as dynamic and modeled in discrete case and we propose a new alternative to solve it. The proposed alternative is based on applying the Clustering Search (CS) method using the Simulated Annealing (SA) for solutions generation. The CS is an iterative method which divides the search space in clusters and it is composed of a metaheuristic for solutions generation, a grouping process and a local search heuristic. The computational results are compared against recent methods found in the literature.     

Yield behaviour of renewable biocomposites of dimer fatty acid-based polyamides with cellulose fibres

The yield behaviour of dimer acid-based polyamides (DAPA) and DAPA reinforced with cellulose fibres (CF) was examined in this study. Both dynamic mechanical analysis (DMA) and tensile tests were used to follow the effect of strain rate or frequency, temperature and filler content on the transitions temperatures, the storage modulus and the yield stresses. The DMA results show that the storage modulus increases with increasing CF concentration. The tensile tests reveal that the yield stress is strain rate, temperature and CF concentration sensitive. Both activation enthalpy and activation volume calculated by the Eyring’s model reveal a slight increase of activation energy with increasing filler content and a decrease of the activation volume. A micromechanically-model was used to predict the yield stress of both DAPA and DAPA/cellulose composites. The model predictions of the yield stress are in good agreement with the experimental data.     

A Contribution to the Acid Cleaning of Boilers

The dissolution rates of various types of magnetites are measured by a spectrophotometric technique allowing the determination of Fe³⁺/Fe²⁺ ratio as a function of time. Some tests are also performed on magnetite electrodes galvanically coupled to steel electrodes. The influence of copper on the dissolution rate of magnetite is evaluated and the effect due to the presence of organic corrosion inhibitors is determined. A circulating loop operating with some boiler tube electrodes was assembled in order to verify the possibility of monitoring the acid cleaning treatment by electrochemical measurements. Electrode potential-time curves, polarization curves and polarization resistance data are recorded; the calculated corrosion rates are compared to weight-loss data obtained in the same experimental conditions. From the overall results some conclusions are reached both on the dissolution process of magnetite and on the monitoring of the acid cleaning treatment.     

Phase noise performance of microwave analog frequency dividers: application to the characterization of oscillators up to the millimeter-wave range

The phase noise performance of two different microwave analog frequency dividers is characterized and compared with the values obtained using simple theories of noise in injection-locked systems. The direct measurement of the divider noise with a low phase noise synthesizer is not accurate enough, and the residual noise technique is used. The noise levels observed using this technique, between -120 and -155 dBc/Hz at a 10 kHz offset frequency, demonstrate that this divider noise is much lower than the phase noise of most microwave free running oscillators, even if this noise is still high with respect to the residual noise of amplifiers realized with the same active devices. The down conversion of microwave sources up to 40 GHz, is proposed as an application example.     

Differences in information sent to minority and nonminority prospective applicants to clinical, counseling, and school psychology programs.

Investigated whether doctoral-level professional psychology programs responded differently to initial requests for information from minority and nonminority applicants. A letter from a fictitious student was sent to 257 programs. Programs were randomly assigned to an ethnic condition (White, Black, or Hispanic). The minority students were more likely to receive a response than were nonminority students, and minority students received more personal forms of communication than did the nonminority student. However, the overall amount of minority recruitment information shared with applicants was the same for both minority and nonminority students. The findings suggest that few programs are using materials sent to prospective minority applicants as a method for implementing their affirmative action policy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of hydropeaking on the distribution and larval development of the Plecoptera from a mountain stream

The downstream distribution and larval development of the Plecoptera from a Pyrenean stream were studied upstream and downstream of a hydroelectric power plant with intermittent hypolimnetic releases. During power generation, flow and temperature were the two main environmental factors modified. The downstream distribution of the various taxa reflected both the impact of hydropeaking and the natural zonation. The lowest densities and biomasses were estimated at 700 m downstream from the plant, underlining the prominent role of hydropeaking. Above the plant, Plecoptera larvae showed a constant drift due to accidental dislodgement, and behavioural drift was mainly nocturnal. Below the plant, the flushing action of peaking flows added to this a catastrophic drift, which was even higher since the amplitude between natural flow and peak flow was elevated. The life cycle patterns and the growth rates of the five dominating species (Siphonoperla torrentium, Isoperla acicularis, Perla grandis, Amphinemura sulcicollis, Protonemura beatensis) were similar at the various sampling sites, and only slight differences in hatching and/or emergence periods were recorded. The Plecoptera of the Oriège complete their larval development during periods where artificial thermal fluctuations are low and have a minor effect on the populations: from autumn to spring—i.e. when the temperatures remain rather low and during snow melt flood (e.g. S. torrentium, I. acicularis, A. sulcicollis)–or in summer when hypolimnetic releases increase the daily thermal fluctuations but reduce the mean diel temperatures (e.g. P. beatensis). Therefore, under this kind of river regulation, the plecopteran population structure and distribution is mainly governed by hydraulic disturbances. © 1998 John Wiley & Sons, Ltd.