Acoustic emission in hafnium under tensile deformation

The paper addresses the dependence of acoustic emission produced in rolled hafnium GFé-1 under tensile deformation on the material’s structural state. A correlation has been established between the material structure, the level of mechanical properties and the values of acoustic parameters. Acoustic emission in non-recrystallized hafnium under tensile deformation is recorded only at the stages that precede fracture. Upon recrystallization annealing at temperatures of 1123 and 1373 K acoustic emission occurs at all the stages of tensile deformation. The highest level of acoustic emission activity in hafnium is observed during the transition from elastic to elastic-plastic strain.     

Glucan structure in a fragile mutant of Saccharomyces cerevisiae

The phenotype of VY1160 fragile Saccharomyces cerevisiae mutant is characterized by cell lysis upon transfer to hypotonic solutions and increased permeability of cells growing in osmotically stabilized media. Two mutations, srb1 and ts1, have been identified in VY1160 cells and previous studies have shown that the increased permeability is due to the ts1 mutation which causes a shortening of mannan side-chains. Here we report that the srb1 mutation, which is the genetic determinant of cell lysis, is responsible for quantitative and structural changes of glucans. Experiments with isogenic single mutation strains, genetic studies coupled with quantitative measurements of glucan content per cell, and methylation analysis of glucans provide evidence that srb1 mutation leads to i) formation of mechanically unstable cell wall network made of insoluble glucan fibrils which are shorter and contain beta(1-6) inter-residue linkages and ii) insufficient filling of the space between the fibrils due to a shortage of the alkali-soluble glucan. Although growing exponentially in osmotically stabilized media, the srb1 cells cannot resist an osmotic shock and, hence, burst immediately.     

Writer pole tip remanence in perpendicular recording

We studied the remanent field from perpendicular writer pole tips by micromagnetic modeling. The pole tip remanence has two causes: 1) the residual flux from the yoke due to undesirable material properties and/or yoke design and 2) the geometry of the pole tip. An optimal yoke design for low remanence includes a wide and short yoke with relatively shallow yoke flare angle around 30/spl deg/ that favors transverse major domains. Horizontal anisotropy in the yoke and the pole tip also helps suppress the vertical magnetization, mainly in the yoke, which yields less residual flux into the pole tip, hence lower remanence. The remanent field is also a strong function of the throat height, i.e., the pole tip length, due to the shape anisotropy effect. Micromagnetic modeling shows that multilayer lamination, both in the yoke and in the pole tip, is an effective way to achieve low remanence. It also eliminates the sensitivity of remanence to the throat height. To improve the robustness of the remanence against the stray field, an antiferromagnetic coupling (AFC) between the lamination layers may also be necessary. Our results apply to both single pole heads and shielded pole heads.     

Vibroacoustical selective agglomeration of coal slimes

Coal slimes from coking coal with an average ash content of about 45% and difficult separation characteristics have been studied. Investigations have also been carried out on two artificial mixtures of gangue and coal of low ash content. Two kinds of agitation have been tested: mechanical—rotational (with an impeller mixer) and vibroacoustical (with vibrating band) at a frequency of 50 Hz and an amplitude of 1 – 2 mm. Vibroacoustical agitation was much more efficient than mechanical-rotational. Second-degree orthogonal-central-compositional planning was used for studying slimes of appropriate size (−0.063 mm). In the most successful test with natural slimes, an efficiency of separation of 34.41% was obtained with the following technological parameters: yield of concentrate 27.93%, ash content of concentrate 22.00%, yield of refuse 72.07%, ash content of refuse 54.30%, the ash content of the run-of-mine coal being 45.28%. These results are close to the best ones obtained with the same slimes by fractional analysis in a liquid of density 1500 kg/m³. In this case, an efficiency of separation of 39.18% was obtained with yield of concentrate 35.04%, ash content of concentrate 24.01%, yield of refuse 64.96%, and ash content of refuse 56.01%.

The experiments on selective agglomeration have been carried out using kerosene at 14.8% consumption with respect to solids. The investigations are of a preliminary character.     

Hot-hole-induced degradation in depletion-mode n-channel MOSFETs

Injection and trapping of hot holes was studied in n-channel depletion-mode MOSFETs and compared to that in enhancement devices. The rate of device degradation was found to decrease with increasing channel doping. A model is proposed explaining this behaviour from the current transport in the buried channel and from the effect of the channel doping level on the field near the drain.     

Visualization and inference based on wavelet coefficients, SiZer and SiNos

SiZer (SIgnificant ZERo crossing of the derivatives) and SiNos (SIgnificant NOn-Stationarities) are scale-space based visualization tools for statistical inference. They are used to discover meaningful structure in data through exploratory analysis involving statistical smoothing techniques. Wavelet methods have been successfully used to analyze various types of time series. In this paper, we propose a new time series analysis approach, which combines the wavelet analysis with the visualization tools SiZer and SiNos. We use certain functions of wavelet coefficients at different scales as inputs, and then apply SiZer or SiNos to highlight potential non-stationarities. We show that this new methodology can reveal hidden local non-stationary behavior of time series, that are otherwise difficult to detect.     

Kaolin beneficiation by vibration

Conclusions Separation of sandy kaolinite suspensions in a vibration machine can be done quite reliably. The vibration method of beneficiation compared with the hydrocyclone method, which at the present time is the most promising, has a number of advantages including: it ensures high output per used area, there is no need to use high pressure pumps and the beneficiation equipment is less subject to wear compared with hydrocyclones.For practical realization it is possible to propose a scheme for a machine shown in Fig. 6 with an eccentric vibrator which can be developed in the concerns.     

Constrained Online Optimization Using Evolutionary Operation: A Case Study About Energy‐Optimal Robot Control

Optimization of full‐scale processes during regular production is a challenge that is often encountered in practice, requiring specialized approaches that only introduce small perturbations so that production does not need to be interrupted. Based on a case study, we discuss the potential of Evolutionary Operation (EVOP) derived methods. The case study relates to a badminton robot that has to perform point‐to‐point motions during a fixed time interval, based on two operation modes: time‐optimal motion, which ensures maximum precision but highest energy consumption, and energy‐optimal motion, which decreases the energy consumption, but as a trade‐off also lowers the precision. The current standard mode of operation is the energy‐optimal mode that is constructed from off‐line optimization on simulations. An online EVOP steepest ascent optimization to further reduce the energy consumption by fine‐tuning the implemented energy‐optimal mode was implemented. The constrained nature of the problem, where energy needs to be minimized subject to a time constraint, was transformed to an unconstrained single‐objective optimization using Derringer desirability functions. Two important contributions were made: (i) the online optimization of the energy‐optimal motion lowered the energy consumption by 4.7% while keeping the precision constant and (ii) the more stringent time‐constraints implemented in desirability functions lead to an operation mode with maximum precision and 51.7% less energy consumption than the current time‐optimal motion. Copyright © 2014 John Wiley & Sons, Ltd.