Image Processing-Based Mine Detection Techniques: A Review

Various mine detection techniques are reviewed with particular emphasis on signal and image processing methods. Based on the target, mines are classified into two types; anti-tank mine (ATM) and anti-personnel mine (APM). Because of the variety of mine types, current mine detection techniques are diversified. The assumption is made that most mine detection techniques consist of sensor, signal processing, and decision processes. For the sensor part, ground penetration radar (GPR), infrared (IR), and ultrasound (US) sensors are reviewed and their characteristics are summarized for the corresponding output signals. For the signal processing and decision parts, a set of image processing techniques including filtering, enhancement, feature extraction, and segmentation are surveyed. Segmentation is used to extract mine signal from various competing signals. For most image processing techniques covered by this paper, mine detection related experimental results are included or reproduced from existing works.     

Lead removal from aqueous solutions by a Tunisian smectitic clay

The adsorption of Pb(2+) ions onto Tunisian smectite-rich clay in aqueous solution was studied in a batch system. Four samples of clay (AYD, AYDh, AYDs, AYDc) were used. The raw AYD clay was sampled in the Coniacian-Early Campanian of Jebel A?doudi in El Hamma area (South of Tunisia). AYDh and AYDs corresponds to AYD activated by 2.5 mol/l hydrochloric acid and 2.5 mol/l sulphuric acid, respectively. AYDc corresponds to AYD calcined at different temperatures (100, 200, 300, 400, 500 and 600 degrees C). The raw AYD clay was characterized by X-ray diffraction, chemical analysis, infrared spectroscopy and coupled DTA-TGA. Specific surface area of all the clay samples was determined from nitrogen adsorption isotherms. Preliminary adsorption tests showed that sulphuric acid and hydrochloric acid activation of raw AYD clay enhanced its adsorption capacity for Pb(2+) ions. However, the uptake of Pb(2+) by AYDs was very high compared to that by AYDh. This fact was attributed to the greater solubility of clay minerals in sulphuric acid compared to hydrochloric acid. Thermic activation of AYD clay reduced the Pb(2+) uptake as soon as calcination temperature reaches 200 degrees C. All these preliminary results were well correlated to the variation of the specific surface area of the clay samples. The ability of AYDs sample to remove Pb(2+) from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount, metal ion concentration and pH. Kinetic experiments showed that the sorption of lead ions on AYDs was very fast and the equilibrium was practically reached after only 20 min. The results revealed also that the adsorption of lead increases with an increase in the solution pH from 1 to 4.5 and then decreases, slightly between pH 4.5 and 6, and rapidly at pH 6.5 due to the precipitation of some Pb(2+) ions. The equilibrium data were analysed using Langmuir isotherm model. The maximum adsorption capacity (Q(0)) increased from 25 to 25.44 mg/g with increasing temperature from 25 to 40 degrees C. Comparative study between sulphuric acid activated clay (AYDs) and powder activated carbon (PAC) for the adsorption of lead was also conducted. The results showed that sulphuric acid activated clay is more efficient than PAC.     

Scintillation light emission studies of LSO scintillators

UV and γ-ray excited luminescence and nuclear spectroscopy were used to study the relationship between the scintillation mechanisms of LSO and the spectroscopic characteristics obtained with PMT and APD readouts at room temperature. No correlation was found between scintillation decay time and light output. Like other investigators, we observed the existence of two distinct luminescence centers, Ce1 and Ce2, that mainly give rise to short (420 nm) and long (440 nm) emission wavelengths. Our measurements showed that different LSO crystals excited by γ-rays have emission spectra with largely different shapes and maxima depending on the relative population and luminescence efficiency of these centers. It was also found that the poor energy resolution of LSO and YSO scintillators is well correlated with the coexistence of the two competing luminescence mechanisms. The prevalence of either Ce1 or Ce2 luminescence tends to reduce the variance of light emission and, thus, to improve energy resolution. Inversely, the coexistence of the two centers increases variance and degrades energy resolution     

On the controllability of linear juggling mechanical systems

This paper deals with the controllability of a class of nonsmooth complementarity mechanical systems. Due to their particular structure they can be decomposed into an “object” and a “robot”, consequently they are named juggling systems. It is shown that the accessibility of the “object” can be characterized by nonlinear constrained equations, or generalized equations. Examples are presented, including a simple model of backlash. The main focus of the work is about linear jugglers.     

Effect of storage of olive mill wastewaters on hydroxytyrosol concentration

This investigation was designed to determine the effect of olive mill wastewaters (OMW) storage on the continuous extraction of potentially high‐added‐value phenolic compounds from these effluents. Particular emphasis was made on the extraction of hydroxytyrosol, one of the major compounds occurring in OMW. The hydroxytyrosol concentration was constant in OMW supplemented with 10% ethanol during storage. However, with 5 and 0% ethanol, a noticeable increase was observed in the hydroxytyrosol concentration. At time zero, the main polyphenols detected in two samples of fresh OMW without ethanol addition were hydroxytyrosol, hydroxytyrosol‐4‐β‐glucoside, 3,4‐dihydroxyphenylacetic acid, p‐coumaric acid, ferulic acid, oleuropein, and some other unidentified compounds. After 5 months of storage, significant accumulation of hydroxytyrosol was observed. The corresponding concentration increased from 0.98 to 3.5 g/L for the OMW sample collected in November 2004 and from 0.77 to 3.1 g/L for the sample collected in January 2006. However, the concentrations of the other phenolic compounds were markedly decreased. Furthermore, it was deduced that the OMW storage facilitates the continuous extraction procedure and improves the extraction yield of hydroxytyrosol. This last parameter increased from 85.5 to 96.8%.     

Contribution des fillers calcaires à l’adhérence pâte-granulat. Exemples tunisiens

This article presents compressive test results carried out on a series of hydraulic concrete mixes without admixtures based on Tunisian limestones aggregates. Their estimated strength was calculated with the French model of LCPC (Laboratoire Central des Ponts et Chaussées), which takes into account the effect of bond to the paste and the ceiling effect of the aggregates. To check the experimental values, the parameter of bond had to be associated the content of fillers aggregates, because the performances predicted by the model are lower than the measurements, at least beyond 10% of fillers. The assumption is that the presence of these fine elements, of comparable nature that the aggregates, improves adherence or linking between paste and aggregate, thanks to bringing together the properties of rigidity of the two materials and to a better homogeneity of the system. The relationship found between the calcareous filler ratio and the bond coefficient then makes it possible to extend the forecasts of the model to the hydraulic mixtures containing aggregates crushed limestones, naturally rich in fillers.      

Effect of the etching time on the morphological, optical and electronic properties of silicon nanowires

ABSTRACT: Owing to their interesting electronic, mechanical, optical and transport properties, silicon nanowires (SiNWs) have attracted much attention, giving opportunities to several potential applications in nanoscale electronic, optoelectronic devices and silicon solar cells. For photovoltaic (PV) application, a superficial film of SiNWs could be used as an efficient antireflection coating (ARC). In this work, we investigate the morphological, optical and electronic properties of SiNWs fabricated at different etching time. Characterizations of the formed SiNWs films were performed using a Scanning Electron Microscope (SEM), UV-Vis-NIR spectrophotometer and Light-Beam-Induced-Current (LBIC) technique. The later technique was used to determine the effective diffusion length in SiNWs films. From LBIC investigations, we deduce that the homogeneity of the SiNWs film play a key role on the electronic properties.     

Synthesis and properties of hybrid alkyd–acrylic dispersions and their use in VOC-free waterborne coatings

Hybrid waterborne alkyd–acrylic dispersions with solid content of 40%, free from any surfactant and exempt of any organic solvent, were successfully synthesized by a melt co-condensation reaction between an acrylic prepolymer bearing carboxylic groups and a long-oil alkyd resin. Spontaneous emulsification of the ensuing hybrid resin was achieved by the addition of an aqueous ammonia solution that neutralized the carboxylic functions. The key role of the carboxylic groups on the stabilization process and on the storage stability of the dispersion was assessed and it was shown that the insertion of anhydride moieties within the acrylic prepolymer ensured the efficient coupling between the acrylic and the alkyd resin and prevented the phase separation. These dispersions are easy to implement and might be used to prepare high quality zero VOC coatings in terms of drying time, stability and gloss. The most stable dispersion was also used in the formulation of air-drying waterborne lacquers and their coating properties were evaluated.