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.     

Parent’s self-reported indoor environment-related symptoms and health worry increase symptom reports among their children at school—Study in two independent populations

Little is known whether parent's indoor environment quality (IEQ)-related symptoms or health perceptions influence the risk of self- or parent-reported symptoms in their children. We assessed (i) the association of parents’ IEQ-related symptoms with IEQ-related symptoms in their children at school and (ii) whether parental IEQ-related health worry increases the risk for children's symptoms. We used two Finnish studies: a national, population-based survey of indoor air and related health problems (n = 611 parents) and a subset of survey for all primary school pupils (grade 3–6) and their parents in Helsinki, which also included school IEQ-related symptoms reported by children (n = 1617 parent-child dyads). In the school survey, parent's own symptoms increased strongly their reporting of their children's symptoms at school (aOR 4.0, 95% CI 2.7–6.0 for parents experiencing a lot of symptoms) and also symptoms reported by the child itself (aOR 2.2, 95% CI 1.5–3.1). Similar, but slightly weaker associations were seen with parental IEQ-related health worries. Results remained unchanged when adjusted for the IEQ of school buildings or parental and children's allergic diseases. Similar associations were seen in the national survey between parent's symptoms at work and child's symptoms at school. The results suggest that parents’ health perceptions may increase the reporting of children's IEQ-related symptoms even more than is typically seen for many indoor air contaminants.     

A prognostic method for the embedded failure monitoring of solder interconnections with 1149.4 test bus architecture

This paper describes the feasibility of accurate low frequency measurements in predicting the breakdown of modern lead free ball grid array (BGA) interconnections. In these measurements, performed partly with 1149.4 analogue boundary scan, ceramic BGA modules measuring 15×15 mm in width, with 9×9 ball matrixes, were attached on an FR-4 printed wiring board (PWB) and thermally cycled over a temperature range of −40 to +125 °C. The condition of corner interconnections was monitored using the developed measurement methods and construction. In-situ measurements were performed with a datalogger during temperature cycling, accompanied with 1149.4 mixed-signal test bus measurements of corner interconnections performed between cycling intervals. In addition, the measurements were complemented by scanning acoustic microscopy and, X-ray. Monitoring corner interconnections by a simple, low-frequency voltage measurement method with embedded test constructions gives an early warning indication well before the electrical interconnection failures. Of two studied interconnection compositions, the ones with plastic core solder balls (PCSB) proved to be more reliable than the ones with 90/10 PbSn balls.     

Strong coupling between surface plasmon polaritons and Sulforhodamine 101 dye

We demonstrate a strong coupling between surface plasmon polaritons and Sulforhodamine 101 dye molecules. Dispersion curves for surface plasmon polaritons on samples with a thin layer of silver covered with Sulforhodamine 101 molecules embedded in SU-8 polymer are obtained experimentally by reflectometry measurements and compared to the dispersion of samples without molecules. Clear Rabi splittings, with energies up to 360 and 190 meV, are observed at the positions of the dye absorption maxima. The split energies are dependent on the number of Sulforhodamine 101 molecules involved in the coupling process. Transfer matrix and coupled oscillator methods are used to model the studied multilayer structures with a great agreement with the experiments. Detection of the scattered radiation after the propagation provides another way to obtain the dispersion relation of the surface plasmon polaritons and, thus, provides insight into dynamics of the surface plasmon polariton/dye interaction, beyond the refrectometry measurements.PACS: 42.50.Hz, 33.80.-b, 78.67.-n