A systematic approach to integral snap-fit attachment design

Traditional integral snap-fit attachment design focuses almost exclusively on the individual locking features, such as cantilever hooks, bayonet-fingers, compressive hooks and others. The positioning and orientation of other significant features on parts, such as those that facilitate or enhance engagement and eliminate unwanted degrees of freedom left by locking features, i.e. locating features and enhancements, are not considered. This paper builds on relatively new methodologies and guidelines for arranging all attachment features on plastic parts comprising snap-fit assembly. Classification of features into categories of locking features, locating features and enhancements of these is used as the basis for discussion. A systematic approach to attachment design is presented.     

Top-Hat HELLISH-VCSOA for optical amplification and wavelength conversion for 0.85 to 1.3μm operation

The Top-Hat hot electron light emission and lasing in semiconductor heterostructure (HELLISH)-vertical cavity semiconductor optical amplifier (VCSOA) is a modified version of a HELLISH-VCSOA device. It has a shorter p-channel and longer n-channel. The device studied in this work consists of a simple GaAs p-i-n junction, containing 11 Ga_0.35In_0.65 N_0.02As_0.08/GaAs multiple quantum wells in its intrinsic region; the active region is enclosed between six pairs of GaAs/AlAs top distributed Bragg reflector (DBR) mirrors and 20.5 pairs of AlAs/GaAs bottom DBR mirrors. The operation of the device is based on longitudinal current transport parallel to the layers of the GaAs p-n junction. The device is characterised through I-V-L and by spectral photoluminescence, electroluminescence and electro-photoluminescence measurements. An amplification of about 25 dB is observed at applied voltages of around V = 88 V.     

Predictability of event occurrences in partially-observed discrete-event systems

This paper studies the problem of predicting occurrences of a significant event in a partially-observed discrete-event system. The predictability of occurrences of an event in a system is defined in the context of formal languages. The predictability of a language is a stronger condition than the diagnosability of the language. Two necessary and sufficient conditions for predictability of occurrences of an event in systems modeled by regular languages are presented. Both conditions can be algorithmically tested. The first condition employs diagnosers. The second condition employs verifiers and results in a polynomial-time (in the number of states) complexity test for verification of predictability. When predictability holds, diagnosers can be used online to predict the significant event.     

Self-assembly of highly charged polyelectrolyte complexes with superior proton conductivity and methanol barrier properties for fuel cells

The paper is concerned with the formation of Layer-by-Layer (LbL) self-assembly of highly charged polyvinyl sulfate potassium salt (PVS) and polyallylamine hydrochloride (PAH) on Nafion membrane to obtain the multilayered composite membranes with both high proton conductivity and methanol blocking properties. Also, the influences of the salt addition to the polyelectrolyte solutions on membrane selectivity (proton conductivity/methanol permeability) are discussed in terms of controlled layer thickness and charge density.The deposition of the self-assembly of PAH/PVS is confirmed by SEM analysis and it is observed that the polyelectrolyte layers growth on each side of Nafion membrane regularly. (PAH/PVS)₁₀-Na⁺ and (PAH/PVS)₁₀-H⁺ with 1.0 M NaCl provide 55.1 and 43.0% reduction in lower methanol permittivity in comparison to pristine Nafion, respectively, while the proton conductivities are 12.4 and 78.3 mS cm⁻¹. Promisingly, it is found that the membrane selectivity values (Φ) of all multilayered composite membranes in H⁺ form are much higher than those of Na⁺ form and perfluorosulfonated ionomers reported in the literature. These encouraging results indicate that composite membranes having both superior proton conductivity and improved methanol barrier properties can be prepared from highly charged polyelectrolytes including salt for fuel cell applications.     

Carrier trapping and escape times in p-i-n GaInNAs MQW structures

We used a semi-classical model to describe carrier capture into and thermionic escape from GaInNAs/GaAs multiple quantum wells (MQWs) situated within the intrinsic region of a GaAs p-i-n junction. The results are used to explain photocurrent oscillations with applied bias observed in these structures, in terms of charge accumulation and resonance tunnelling.     

Statistical Analysis and Multimodal Classification on Noisy Eye Tracker and Application Log Data of Children with Autism and ADHD

Emotion recognition behavior and performance may vary between people with major neurodevelopmental disorders such as Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD) and control groups. It is crucial to identify these differences for early diagnosis and individual treatment purposes. This study represents a methodology by using statistical data analysis and machine learning to provide help to psychiatrists and therapists on the diagnosis and individualized treatment of participants with ASD and ADHD. In this paper we propose an emotion recognition experiment environment and collect eye tracker fixation data together with the application log data (APL). In order to detect the diagnosis of the participant we used classification algorithms with the Tomek links noise removing method. The highest classification accuracy results were reported as 86.36% for ASD vs. Control, 81.82% for ADHD vs. Control and 70.83% for ASD vs. ADHD. This study provides evidence that fixation and APL data have distinguishing features for the diagnosis of ASD and ADHD.     

A layout algorithm for signaling pathways

Visualization is crucial to the effective analysis of biological pathways. A poorly laid out pathway confuses the user, while a well laid out one improves the user’s comprehension of the underlying biological phenomenon.We present a new, elegant algorithm for layout of biological signaling pathways. Our algorithm uses a force-directed layout scheme, taking into account directional and rectangular regional constraints enforced by different molecular interaction types and subcellular locations in a cell. The algorithm has been successfully implemented as part of a pathway visualization and analysis toolkit named Patika, and results with respect to computational complexity and quality of the layout have been found satisfactory. The algorithm may be easily adapted to be used in other applications with similar conventions and constraints as well.Patika version 1.0 beta is available upon request at http://www.patika.org.     

A simplified model based on clearness index for estimating yearly performance of hybrid PV energy systems

A simplified model for estimating the energy contribution of PV converter in a hybrid PV–wind system is presented. The simplified model determines the yearly solar fraction, that is the fraction of energy demand provided by PV, and the remaining loss of load (LOL) is assumed to be provided by wind turbines. The novel model is based on simulation results derived from 8 years of measured hour‐by‐hour solar irradiation data from five different locations in the world. The system performance is simulated by the PV–wind energy simulation program of the Cardiff School of Engineering (ARES). An hourly constant load profile is assumed. The performance of a PV system is primarily dependent on the solar irradiation distribution in a given location for the period of time in question. The new model correlates the location dependence observed in the yearly solar fraction curves of different data sets with one of the most characteristic solar irradiation distribution parameters, the yearly clearness index of the respective solar irradiation data. The new model requires the yearly clearness index value, which is commonly available for most locations throughout the world, as input. As the novel model is validated with solar irradiation data from different locations in the world, it could be used for predicting the solar fraction in a hybrid PV system with a very high level of accuracy, for a wide range of climates. Copyright © 2002 John Wiley & Sons, Ltd.     

Line defects, planar defects and voids in SrTiO3 films grown on MgO by pulsed laser and pulsed laser interval deposition

Two and three dimensional growth of SrTiO₃ films on (001) MgO substrate was achieved by pulsed laser interval and pulsed laser deposition respectively. The growth mode was monitored by in-situ reflection high energy electron diffraction. Interval deposition forces layer-by-layer growth of materials even with such a large lattice misfit (~ 7.9%). A titanium dioxide buffer monolayer was deposited to allow the film to wet the substrate to encourage two dimensional growth of the strontium titanate. A variety of defects was investigated using transmission electron microscopy and high resolution scanning transmission electron microscopy. Misfit dislocations, steps at the interface, Ti-rich defects and regularly shaped nano-holes connected by anti-phase boundaries were found to be the dominant defects in these films grown layer by layer. The edges of the nano-holes were mainly along [010] and [100] for a [001] growth direction. The large strain between the two crystal systems with large lattice mismatch leads to in-plane tensile stress during the layer-by-layer growth. The stress is relieved in part by the holes. The films with a three dimensional growth mode possess a uniform surface with dislocations as the dominant defects. The individual densities of the various defects, including a Ti-rich phase and misfit and threading dislocations, are determined by the kinetics of the deposition method.