Free-field characterization via directional transmission through a nanoaperture

We propose a scheme based on extraordinary transmission of light through a single nanoaperture, surrounded by periodic corrugations, for direct characterization of focal-region optical fields with subwavelength-scale structure. We describe the design of the device on the basis of rigorous diffraction theory and fabricate a prototype using a process that involves electron beam lithography, dry etching, and template stripping. First experimental results performed with a transmission-type confocal optical microscope demonstrate the potential of the method.     

A survey on handling computationally expensive multiobjective optimization problems using surrogates: non-nature inspired methods

Computationally expensive multiobjective optimization problems arise, e.g. in many engineering applications, where several conflicting objectives are to be optimized simultaneously while satisfying constraints. In many cases, the lack of explicit mathematical formulas of the objectives and constraints may necessitate conducting computationally expensive and time-consuming experiments and/or simulations. As another challenge, these problems may have either convex or nonconvex or even disconnected Pareto frontier consisting of Pareto optimal solutions. Because of the existence of many such solutions, typically, a decision maker is required to select the most preferred one. In order to deal with the high computational cost, surrogate-based methods are commonly used in the literature. This paper surveys surrogate-based methods proposed in the literature, where the methods are independent of the underlying optimization algorithm and mitigate the computational burden to capture different types of Pareto frontiers. The methods considered are classified, discussed and then compared. These methods are divided into two frameworks: the sequential and the adaptive frameworks. Based on the comparison, we recommend the adaptive framework to tackle the aforementioned challenges.     

Behaviour of oat globulins in lactic acid fermentation of oat bran

Oat bran fermentation (OBF) is used to produce non-dairy yogurt-type products. Such products may be designed being rich in probiotic bacteria and/or dietary-fibre. Oat bran is, however, also rich in proteins, especially 12 S globulins. Understanding the behaviour of globulins in OBF would thus offer a basis for further exploitation of proteins in the product design. The behaviour of oat globulins was monitored during a model OBF in order to study changes in protein solubility and possible protein hydrolysis. Proteins were extracted from OBF samples with a buffered and a non-buffered extraction procedure. The extracts were analyzed with SDS-PAGE and a Lowry assay. Combined effect of pH and NaCl-concentration on the solubility of oat globulin isolate was studied. The solubility of oat globulins decreased during OBF; this appeared as their shift from the salt-soluble fraction to the residual protein fraction. The shift in oat globulin solubility was due to the acidifying conditions present in OBF, which lead to the unfolding of globulins and also apparently induced protein aggregation. No major protein hydrolysis was observed during OBF.     

Friction Paths for Cubic Boron Nitride: An Ab Initio Study

Friction coefficients for cubic boron nitride were determined with the use of hybrid density functional B3LYP calculations. Two cluster models and an infinite periodic model were applied. Various contacts between duplicated surfaces and different sliding paths of the surfaces with respect to each other were taken into consideration, and friction coefficients were derived. The calculations suggest that three different sliding paths contribute to the friction, the friction coefficient for the periodic model being 0.21 at its lowest. This value is in agreement with previous experimental studies, where a friction coefficient of 0.1–0.2 has been measured for cubic boron nitride.     

Cutting thin sheet metal with a water jet guided laser using various cutting distances, feed speeds and angles of incidence

This research deals with the cutting of thin sheet metals at various distances, feed speeds and angles of incidence using a water jet guided laser. In the water jet guided laser process a laser beam is focused into a jet of water, which transmits the beam to the workpiece. This eliminates the need for any focus control. Nevertheless, most of its applications are in planar cutting where this advantage is not utilized. For the laser parameters, jet pressure and diameter in question, the value of 50 mm was found to be a fairly reliable upper limit to the cutting distance for both normal and inclined surfaces. In addition to the laser beam being absorbed partially by the water jet, the jet was found to be susceptible to disturbances. Specimen vibration caused by the water jet also impeded cutting a continuous kerf.     

Consistent mapping of common cause failure rates and alpha factors

The problem addressed is how to combine event experience data from multiple source plants to estimate common cause failure (CCF) rates for a target plant. Alternative models are considered for transforming CCF parameters from systems with different numbers of similar components to obtain CCF-rates for a specific group of components. Two sets of rules are reviewed and compared for transforming rates and assessment uncertainties from larger to smaller systems, i.e. mapping down. Mapping down equations are presented also for the alpha-factors and for the variances of CCF rates. Consistent rules are developed for mapping up CCF-rates and uncertainties from smaller to larger systems. These mapping up rules are not limited to a binomial CCF model. It is shown how consistency requirements set certain limits to possible parametric values. Empirical alpha factors are used to estimate robust mapping parameters, and mapping up equations are derived for alpha factors as well. An assessment uncertainty procedure is presented for treating incomplete or vague information when estimating CCF-rates. Numerical studies illustrate mapping rules and procedures. Recommendations are made for practical applications.     

Efficient current reuse for low-power transceivers

Current boosting is a method where the performance of an active circuit block is optimized by placing a constant current source in parallel with the active signal path to provide optimal biasing for different components. In this paper, a technique to replace the constant dc current source with active building blocks typically required in transceivers is proposed. By using this method the total current consumption of the transceiver can be efficiently reduced without modifying its performance. A design example where the proposed technique reduces the receiver current consumption by 45% is given.     

From acacia honey monosaccharide content to a new external binary plasticizer applicable in aqueous whey protein films

Plasticizer is an essential adjuvant in food and pharmaceutical film coatings affecting the appearance, mechanical and permeation properties of the final coat. In the present study, film formation and plasticization of native whey proteins (potential future “green” coating agents for pharmaceuticals and food products), were studied with free isolated films. Special attention was paid to the effects of plasticizer, preheating and film forming solution pH on the mechanical stress–strain and moisture permeation properties of whey protein films. Glycerol, binary mixtures of fructose and glucose, and non-crystalline acacia honey were studied as external plasticizers. The type and amount of plasticizer affected the mechanical stress–strain properties of the whey protein films. A short preheating treatment of whey proteins prior to film casting resulted in mechanically strong films with a reduced elongation. The film forming properties of aqueous whey proteins could be modified by adjusting the pH above the isoelectric point of β-lactoglobulin prior to film coating. For effective plasticization, whey protein films required a high amount of monosaccharide containing plasticizer ranging from 80% to 120% (calculated from the protein weight). A new external binary plasticizer having the same ratio of monosaccharides as non-crystalline acacia honey (fructose and glucose 1.67:1) was found to be applicable in aqueous whey protein films.     

Mind reading with regularized multinomial logistic regression

In this paper, we consider the problem of multinomial classification of magnetoencephalography (MEG) data. The proposed method participated in the MEG mind reading competition of ICANN’11 conference, where the goal was to train a classifier for predicting the movie the test person was shown. Our approach was the best among ten submissions, reaching accuracy of 68 % of correct classifications in this five category problem. The method is based on a regularized logistic regression model, whose efficient feature selection is critical for cases with more measurements than samples. Moreover, a special attention is paid to the estimation of the generalization error in order to avoid overfitting to the training data. Here, in addition to describing our competition entry in detail, we report selected additional experiments, which question the usefulness of complex feature extraction procedures and the basic frequency decomposition of MEG signal for this application.