AN IMPROVED COMPACT INTEGRATED ANALYTICAL SWATCH TESTING SYSTEM

A compact swatch testing system has been developed to precisely quantify the permeation and penetration of a chemical weapons agent simulant while reducing the system footprint, improving safety and usability, enhancing automation, and maintaining measurement precision comparable to its predecessor. With the addition of a new test cell design and temperature control mechanism, the improved system demonstrated higher steady-state permeation rates and shorter breakthrough times. In comparison to the earlier prototype, the compact configuration's footprint and volume are reduced substantially, thereby allowing for use inside a 6-foot laboratory hood. A reference device for assessing test cell performance was also developed.     

Residual strength of composite laminates containing scarfed and straight-sided holes

This investigation is motivated by the needs to quantify the load-carrying capacity of composite laminates with scarfed holes, a damage cut-out shape employed to achieve flush repairs of composites. Both experimental testing and analytical modelling were carried out to investigate the damage progression behaviour of composite laminates containing either straight-sided or scarfed holes. Hoop strains were recorded by strain gauges located along the scarf surface and the results indicate a much greater extent of damage progression than specimens containing straight-sided holes. Three different strength-prediction models were employed to quantify the residual strength, including an analytical cohesive zone model developed in this work, an analytical inherent-flaw fracture mechanics method and a finite element-based continuum damage model. Comparisons of the experimental results with the model predictions reveal that the continuum damage model, calibrated using data from coupons with straight-sided holes, provides promising correlation with experimental results.     

Context-aware broadcasting approaches in mobile ad hoc networks

The aim of this paper is to compare different context-aware broadcasting approaches in mobile ad hoc networks (MANETs) and to evaluate their respective performances. Message broadcasting is one of the core challenges brought up by distributed systems and has therefore largely been studied in the context of traditional network structures, such as the Internet. With the emergence of MANETs, new broadcasting algorithms especially geared at these networks have been introduced. The goal of these broadcasting algorithms is to ensure that a maximum number of nodes deliver the broadcasted message (reliability), while ensuring that the minimum number of nodes retransmit the broadcasted message (efficiency), in order to save their resources, such as bandwidth or battery. In recent years, as more and more mobile devices have become context-aware, several broadcasting algorithms have been introduced that take advantage of contextual information in order to improve their performance. We distinguish four approaches with respect to context: (1) context-oblivious approaches, (2) network traffic-aware approaches, (3) power-aware approaches, and (4) location-aware approaches. This paper precisely aims at presenting these four different broadcasting approaches and at measuring the performance of algorithms built upon them.     

Remarks and corrections to the triangular approximations of fuzzy numbers using ��-weighted valuations

A recent paper was dedicated to find the nearest fuzzy triangular approximations of a fuzzy number by using ??-weighted valuations. We prove, by simple examples, that the results of approximations are not always triangular fuzzy numbers and that in fact they are not fuzzy sets. We give a correct solution of the problem of approximation in a more general case, and we study the properties of identity, additivity, translation invariance, scale invariance, and monotonicity of the new approximation operator.     

Study on visual machine-learning on the omnidirectional transporting robot

We present a computer vision solution integrated to an omnidirectional transporting robot to perform the position tracking of multiple trays moving on its planar acrylic plate surface. The trays were designed to carry lightweight materials on top of their surface so that the mechanism could be implemented as an automated transporting system for applications that require the displacement of products and/or materials in any given space. One hurdle faced by the visual system for suitable detection was the partial occlusion of the image of a tray when placing arbitrary objects on its surface. Our strategy to overcome this challenge consisted on the implementation of machine learning algorithms, such as Support Vector Machines (SVM), using datasets of images containing trays with different occlusion patterns for fast object detection through rigorous training. The results of experimental tests validate the implementation of our proposal as a reliable approach for the object tracking of multiple trays on the robotic device, even under partial occlusion. We also studied the accuracy of the position measurements performed by our visual system with respect to the position measurements taken by the OPTITRACK motion capture system and evaluated the processing time per frame required by the software implementation.     

Optical planar waveguide for cell counting

Low cost counting of cells has medical applications in screening, military medicine, disaster medicine, and rural healthcare. In this report, we present a shallow, buried, planar waveguide fabricated by potassium ion exchange in glass that enables low-cost and rapid counting of metal-tagged objects that lie in the evanescent field of the waveguide. Laser light transmitted through the waveguide was attenuated proportionately to the presence of metal-coated microstructures fabricated from photoresist. This technology enables the low-cost enumeration of cells from blood, urine, or other biofluids.     

A mathematical model for skin burn injury induced by radiation heating

We modify the Pennes model by taking into account the thermal relaxation time of biological tissue. Specifically, we employ the Maxwell–Cattaneo thermal flux law, in conjunction with the fourth power law, to model the effects of high thermal radiation on such skin. The skin is considered to be a 3D triple-layered structure with embedded dendritic countercurrent multi-level blood vessels, artery and vein, where the dimensions and blood flow of the multi-level blood vessels are determined based on the constructal theory of multi-scale tree-shaped heat exchangers. The method is illustrated by a numerical example.     

Solution-processed single walled carbon nanotube electrodes for organic thin-film transistors

Airbrushed single walled carbon nanotube (SWCNT) thin films with sheet resistivity <1 kΩ/sq. and transparency >80% are used as electrodes for pentacene and regioregular poly(3-hexylthiophene) (P3HT) thin-film transistors (TFTs). Airbrushed SWCNT electrodes show low contact resistance in a bottom-contact configuration, comparable to (in the case of P3HT) or lower than (in the case of pentacene) Au bottom-contacts. The results show that airbrushed CNT electrodes yield similar performance to CVD-grown CNT electrodes.     

Size-controllable synthesis of chromium oxyhydroxide nanomaterials using a soft chemical hydrothermal route

Chromium oxyhydroxide nanomaterials were synthesised through a simple soft chemical hydrothermal method. The chromium oxyhydroxide materials display platelet morphology with clear edges, ~11 nm in diameter. CrO(OH) nanomaterials synthesised under different conditions were fully characterised by X-ray diffraction (XRD), transmission electron microscopy (TEM) combined with selected area electron diffraction (SAED), scanning electron microscopy (SEM), BET specific surface area analysis, X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Bonding of the trivalent chromium from the oxyhydroxide nanomaterials was defined through the analysis of their high resolution XPS spectra for Cr 2p_3/2 and O 1s. The thermal stability of the nanomaterials CrO(OH) was established. This research has developed methodology for the synthesis of chromium oxyhydroxide nanoplates.     

On the optimum support size in meshfree methods: A variational adaptivity approach with maximum‐entropy approximants

We present a method for the automatic adaption of the support size of meshfree basis functions in the context of the numerical approximation of boundary value problems stemming from a minimum principle. The method is based on a variational approach, and the central idea is that the variational principle selects both the discretized physical fields and the discretization parameters, here those defining the support size of each basis function. We consider local maximum‐entropy approximation schemes, which exhibit smooth basis functions with respect to both space and the discretization parameters (the node location and the locality parameters). We illustrate by the Poisson, linear and non‐linear elasticity problems the effectivity of the method, which produces very accurate solutions with very coarse discretizations and finds unexpected patterns of the support size of the shape functions. Copyright © 2009 John Wiley & Sons, Ltd.