Evaluation of hidden Markov models using deep CNN features in isolated sign recognition

Multimedia Tools and Applications - Isolated sign recognition from video streams is a challenging problem due to the multi-modal nature of the signs, where both local and global hand features and...     

Learning multi-scale features for foreground segmentation

Pattern Analysis and Applications - Foreground segmentation algorithms aim at segmenting moving objects from the background in a robust way under various challenging scenarios....     

Drying of solids in vacuum fluidized bed

A drying process in a fluidized bed under vacuum conditions is experimentally and theoretically studied. A fluidized bed operating in reduced pressure presents a possibility for a better quality of production, with safer process conditions. A mathematical model is developed for the reduced‐pressure drying process in a fluidized bed. Some parameters were analyzed by comparing experimental results with model predictions. The predictions from the model agreed quite closely with the experimental data. The results showed that a decrease in pressure reduces the interparticular resistance. A good agreement was also found applying the model to data, at atmospheric pressure, from other authors.     

Templated growth of carbon nanotubes with controlled diameters using organic-organometallic block copolymers with tailored block lengths

Block copolymer thin films fabricated from polystyrene-polyferrocenylsilane (PS-b-PFS) block copolymers on silicon substrates were used as precursors of well-ordered, nanosized growth catalysts for carbon nanotubes (CNTs). The size of the catalytic domains was tuned by changing the molecular weight of the block copolymer, enabling control of the diameter of the CNTs grown from these substrates. CNT growth on catalytic substrates with larger organometallic domain sizes, using acetylene as a carbon source, resulted in enhanced amounts of CNT deposition compared to smaller PFS domains, which exhibited low catalytic activity. The inner and outer diameters of the multi-walled CNTs obtained were typically 8 and 16 nm, respectively, and were not influenced by the catalytic domain sizes. Various annealing strategies in inert or in hydrogen atmosphere were investigated. The use acetylene with an additional hydrogen flow as gas feed resulted in a significant increase in deposition on all PS-b-PFS decorated substrates. Under these conditions, the CNT diameters could be controlled by the catalyst domain sizes, resulting in decreasing diameters with decreasing domain sizes. Multiwalled CNTs with inner and outer diameters of 4 and 7 nm, respectively, and a narrow diameter distribution were obtained.     

Performance of an HT‐PEMFC having a catalyst with graphene and multiwalled carbon nanotube support

In this study, the effect of multiwalled carbon nanotube and graphene nanoplatelet‐based catalyst supports on the performance of reformate gas‐fed polybenzimidazole (PBI)‐based high‐temperature proton exchange membrane fuel cell (HT‐PEMFC) was investigated. In addition, the effect of several microwave conditions on the performance of the Pt‐Ru/multiwalled carbon nanotube (MWCNT)–graphene nanoplatelet (GNP) catalyst was assessed. Through X‐ray diffraction, thermal gravimetric analysis, transmission electron microscopy, scanning electron microscopy, and energy dispersive spectroscopy, the catalysts' chemical structure and morphology were characterized. Cyclic voltammetry analysis was used for the electrochemical characterization of catalysts through an electrochemical cell with three electrodes connected to a potentiostat. The results showed that the best performing catalyst is the catalyst produced using 800‐W power for 40 seconds. The electrochemically active surface area values of this catalyst ranged from 54 to 45 m²/g. Single‐cell performance tests of the HT‐PEMFC were then carried out. In these tests, reformate gas mixture, consisting of H₂, CO₂, and CO, was fed to the anode side at 160°C without humidification. These tests for the best performing catalyst yielded peak power density of 0.280 W/cm² and current density (at 0.6 V) of 0.180 A/cm² in the H₂/air environment and peak power density of 0.266 W/cm² and current density (at 0.6 V) of 0.171 A/cm² in the reformate gas/air environment. As a result of the experiments, it was found that Pt‐Ru/MWCNT‐GNP hybrid material is a suitable catalyst for HT‐PEMFC.     

A Facile Technique to Produce Open Cell Titanium Foams

Nature prefers open cell order in most structures such as trees and skeletons. Engineers have been imitating the nature, to obtain high specific strength, to transfer heat, energy absorbance and filtering for various applications such as filters, heat exchangers, impact absorbers, bone implants. Although ceramic foams have been produced and used as heat shields and filters, recently a great effort has been put on metallic foams produced from aluminium, copper, iron, stainless steel, nickel and titanium. Studies on open cell structured titanium foams are steps forward among these materials due its good biocompatibility and high specific strength. In this study, open cell titanium foams are produced utilizing polymer impregnation process accompanied by a facile sintering method. In traditional foam making, long sintering durations reduce the efficiency as far as cost and delivery time for producers. In order to overcome these problems, an alternative solution is made in the production of open cell titanium foams. A facile method is designed to sinter the impregnated polymers by using induction heating. Titanium foams with open cell structures are successfully produced. SEM, XRD, metallographic characterizations are performed. Average hardness value is calculated as 815.093 ± 6.59 Hv0.1.     

Utilizing inkjet printing to fabricate electrical interconnections in a system-in-package

The printed interconnections for encapsulated electronic packages using nanoparticle metal inks and polymer dielectrics have been demonstrated. The printing has utilized a digital printing method, inkjet printing. The printing process has been adopted rather well, but process yield improvement required more attention to the control of individual manufacturing stages and error sources. The sources for possible errors can be roughly divided into separate groups: the substrate-ink interaction and treatment procedure related, ink jetting related, and moving stage related. In this paper, the individual stages were taken under consideration. The process performance was studied using statistical methods. The affecting factors were classified, and designed experiments were carried out to determine the most significant factors and to create a model to describe the behavior. According to the models, optimized process parameters were achieved, and implemented in practice.