Fault diagnosis of an automobile cylinder head using low frequency vibrational data

This paper proposes a vibration-based fault-diagnosis method for mechanical parts. This method, after algorithm development, only requires a single inexpensive test to inspect the part which could take as short as half a second. The algorithm is developed in three major stages, (i) exciting specimens without or with known faults using a controlled force and recording acceleration of a single point for a short time (ii) finding a signature for each faulty specimen, using Fourier transform and statistical analysis. (iii) Developing a multi-layer perceptron, as a mathematical model, using the results of stage (ii). The elements of a part signature are the inputs to the model. The location (and possibly size and shape factor) of the fault is model output. Stage (i) can be performed experimentally or alternatively with a validated FEM, one experiment or simulation per specimen. The proposed technique was examined to locate (isolate) a fault on an automobile cylinder head. The presented accuracy is considerable, and the data collected at fairly low frequency range (below 1200 Hz) were found to be sufficient for this technique. In the case study of this paper, possible fault locations are on a line; as a result, fault location has one dimension. It is shown that the technique can be extended to higher dimensions.     

Chemical vapor deposition of poly(3‐alkylthiophene) nanoparticles on fabric: Chemical and electrochemical characterization

Chemical vapor deposition of poly(3‐methylthiophene) and poly (3‐hexylthiophene) as conductive polymers on the surface of polyester fabrics was successfully obtained. Fourier transform infrared spectroscopy confirmed the formation of polymers on surface of fabrics (the fingerprint of polythiophenes, υ 600–1500 cm^?1). The uniformity of deposition and nanoparticles (average size of 60 nm) were proved with scanning electron microscopy. Electrochemical impedance spectroscopy showed that P3HT‐coated samples offer higher conductivity in compared to P3MT‐coated samples. The impedance modulus of P3HT‐coated samples was lowered nine times to that of row materials and reached to c8000 Ω. The samples have also shown electrochromic properties under electrical current, changing its color from yellowish green at 0 V to dark green at +12 V for poly (3‐hexylthiophene) samples and from brown at 0 V to red at +12 V for poly(3‐methylthiophene)‐coated fabrics (V = 0 V, λ = 450 nm; V = 12 V, λ = 650 nm). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40673.     

Numerical investigation on the number of active surface sites of carbon catalysts in the decomposition of methane

The number of active sites on the surface of carbon catalysts is an important factor in determining their activity in the decomposition of methane. Although several studies have been performed to identify the nature of these sites, no method has been established to estimate their number. A method is presented to estimate this value, and its effect on hydrogen production is evaluated, along with that of temperature and residence time. For this purpose, the thermocatalytic decomposition of methane is modeled with the inclusion of the number of active sites of the catalyst in the kinetics. The results of the model indicate the high influence of variations of small residence times in this process, and the reduction of this effect at high temperatures. Also, the effect of the number of surface sites is shown to be more prominent at low residence times and temperatures. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2228–2234, 2014     

Feldspar/titanium dioxide/chitosan as a biophotocatalyst hybrid for the removal of organic dyes from aquatic phases

Feldspar/titanium dioxide/chitosan hybrid, a photoactive biocompatible adsorbent for anionic dyes, was synthesized, characterized, and successfully tested. The adsorbent characterization, pH role, adsorbent dose effect, equilibrium data, kinetic plats, and thermodynamic parameters are reported. The point of zero charge for the hybrid was measured to be 8.3, and the most favorable pH range for the adsorption process was found to be below this pH value. The adsorption equilibrium study demonstrated that the Freundlich model was best fitted to the experimental data. Without UV light exposure, the prepared adsorbent adsorbed 72 mg of Acid Black 1 (AB1)/g of sorbent (86% removal) from a 100‐mL solution with an initial dye concentration of 50 mg/L, whereas UV irradiation resulted in an increase in the elimination of AB1 dye (97% removal). The kinetic data was depicted well by the pseudo‐second‐order model. The thermodynamic parameters indicated that the reaction between the hybrid and the dye was exothermic and also spontaneous at lower temperatures. In the batch desorption process, several aqueous solutions adjusted to different pH values were tested, and the best desorption performance (90% desorption) was achieved at pH 11. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40247.     

Rheological,crystal structure,barrier, and mechanical properties of PA6 and MXD6 nanocomposite films

In this study, rheological, crystal structure, barrier, and mechanical properties of polyamide 6 (PA6), poly(m‐xylene adipamide) (MXD6) and their in situ polymerized nanocomposites with 4 wt % clay were studied. The extent of intercalation and exfoliation as well as type of crystals, crystallinity, and thermal transitions were investigated using X‐ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. Dynamic rheological measurements revealed that incorporation of nanoclay significantly increases complex viscosity of MXD6 nanocomposites at low frequencies, which was related to the formation of a nanoclay network and exchange reaction between MXD6 chains. The comparative study of dynamic characteristics (G′ (ω) and G″ (ω)) for aliphatic and aromatic polyamide nanocomposites with their neat resins as well as the relaxation spectra for both polymer systems confirmed the possibility of the aforementioned phenomena. Although, the crystallinity of MXD6 films was lower as compared to PA6 films, the permeability to oxygen was more than 5 times better for the former. Incorporating 4 wt% clay enhanced the barrier property, tensile modulus, and yield stress of PA6 and MXD6 nanocomposite films in both machine and transverse directions without sacrificing much puncture and tear resistances. The PA6‐based films showed higher tear and puncture strength as compared to MXD6 films. POLYM. ENG. SCI., 54:2617–2631, 2014. © 2013 Society of Plastics Engineers     

Poly(DL-lactide-co-ε-caprolactone) and poly(DL-lactide-co-glycolide) blends for biomedical application: Physical properties,cell compatibility,and in vitro degradation behavior

Poly(DL-lactide-co-ε-caprolactone) (PLCL) and poly(DL-lactide-co-glycolide) (PLGA) blends of various compositions were prepared. Fractured sections of PLCL/PLGA blends did not evidence phase separation and blend glass transition temperatures suggested some degree of blend compatibility. The elastic modulus showed a negative deviation from the additive law of mixture. Superior biocompatibility in terms of fibroblast NIH 3T3 cell adhesion and proliferation, better mechanical properties, and a more homogeneous phase were obtained with PLCL/PLGA 25/75 blend. Rapid degradation of PLCL phase (4–8 weeks) in PLCL/PLGA 25/75 blend led to a porous structure, which makes it a potential candidate for drug delivery systems.     

Electrooxidation of formaldehyde as a fuel for fuel cells using Fe2+-nano-zeolite modified carbon paste electrode

This study aimed to investigate the application of nano ZSM-5 zeolite for preparation of modified carbone paste electrode for electrocatalytic oxidation of formaldehyde. The electrochemical behavior of modified carbon paste electrodes in the forms of Fe/FeZSM-5CPE and unmodified carbon paste electrode were studied using cyclic voltammetric and chronoamprometric techniques. The obtained results show that the modified carbon paste electrode (Fe/FeZSM-5CPE) is the suitable electrode for electrooxidation of formaldehyde in the acidic solution. The transfer coefficient and current density for formaldehyde were calculated 0.23 and 19.8 mA/cm², respectively. The rate constant for catalytic reaction was calculated as 3.6 × 10³ cm³ s^?1 mol^?1 via Cottrell equation.     

PiSHi: click the images and I tell if you are a human

This paper introduces pictorial intelligent system for human identification (PiSHi), an image-based captcha which uses three human cognitive abilities to distinguish humans from machines. The first is the human ability to easily recognise the image’s upright orientation. The second is the human brain’s ability in recognising a picture’s content when it is only partially visible. And the third is the human ability in unconscious decision making when encountering pictorial challenges. This work models such complicated human patterns in problem solving for the first time. In order to extract these behavioural patterns and save them in a pattern database, we have implemented our own captcha and performed a series of experiments. PiSHi’s interface presents the user with a set of distorted pictures and asks her to click on the upright orientation of all the pictures in any preferred order. Next, it captures the user’s interaction patterns, compares them with the ones saved in the pattern database, and grants her a corresponding credit. Based on this credit, the user either passes or fails the test, and participates in updating the picture database. Our experiments indicate that human users can solve our proposed captcha effectively—with an accuracy of 99.44 %. Besides, our proposed system is secure against several types of attacks including random guessing and reverse image search engines. The results offer the possibility of utilising the identified human behavioural models in practical captchas.