Deep underwater image enhancement through colour cast removal and optimization algorithm

ABSTRACT

Blue–green colour cast effect and low contrast are common problems suffered by deep underwater images. This paper introduces a new method which consists of two major steps: red channel correction based on green and blue channels (RCCGB), and simultaneous contrast stretching and mean pixel enhancement (SCSMPE). The RCCGB is designed to minimize the effect of blue–green illumination. This step considers the differences between the red channel and other channels in terms of total pixel values. The second major step, SCSMPE is specifically designed to perform contrast stretching and improve the mean pixel value simultaneously through particle swarm optimization (PSO). Based on the visual observation, the proposed method significantly reduces the effect of the blue–green colour cast and improves the image contrast. Furthermore, the average quantitative values for 300 underwater images also demonstrate the superiority of the proposed method.     

Polynomial time solution to minimum forwarding set problem in wireless networks under disk coverage model

In this paper, we consider a practical problem, called Minimum Forwarding Set Problem (MFSP), that emerges within the context of implementing (energy efficient) communication protocols for wireless ad hoc or sensor networks. For a given node v, MFSP asks for a minimum cardinality subset of 1-hop neighbors of v to cover v’s 2-hop neighbors. MFSP problem is also known as multi-point relay (MPR) problem. It is shown to be an NP-complete problem for its general case that does not consider the coverage characteristics of wireless transmissions. In this paper, we present two polynomial time algorithms to solve the MFSP problem under disk coverage model for wireless transmissions. In our earlier work, we presented a polynomial time algorithm for this problem under unit disk coverage model. In the current work, we present several observations on the geometric characteristics of wireless transmissions under disk coverage model and build two alternative dynamic programming based solutions with different run time and space complexities to the problem. Disk coverage model is a more general model because it allows nodes to use arbitrary power levels for transmissions. As a result, the presented algorithms provide a more practical solution that can be used as a building block for energy efficient communication protocols designed for wireless ad hoc and sensor networks.     

A note on histamine levels in Turkish style fermented sausages

The histamine contents of Turkish style fermented sausages were determined on 46 samples of five different brands obtained from retail stores in Van in Turkey. Histamine was found in all samples in the range 19.64-87.47 mg/kg (mean 32.13 mg/kg). Histamine levels in the brands differed significantly (P<0.01). The results suggest that the histamine levels in the sausages were not hazardous in terms of public health although they may be a potential risk to sensitive individuals.     

Adsorption Studies of Chlorpropham and 3-Chloroaniline on Chemically Activated Halloysite

Chemically modified halloysite proved to be an effective adsorbent for the pesticide chlorpropham and 3-chloroaniline from an aqueous solution. Adsorption experiments were conducted using such procedures as the time-dependent （kinetic） procedure and the concentration dependent （isotherm） procedure. Results indicate that the adsorption process is related to the kind of the studied compound. The equilibrium data are well suited to a Freundlich isotherm in the case of both investigated compounds. Adsorption kinetics of chlorpropham and 3-chloroaniline on acid-treated halloysite was successfully described by pseudo-second order kinetic model and the model of Weber and Morris. From the present study, we suggest that the adsorption of chlorpropham and 3-chloroaniline on the modified halloysite is a rather complex process involving two steps： external mass transfer and intra-particle diffusion.     

Synthesis of mono-, di-, tri- and tetracarboxy azaphthalocyanines as potential dark quenchers

Mono-, di-, tri- and tetracarboxy-substituted metal-free azaphthalocyanines (AzaPc) were synthesized from 5,6-bis(diethylamino)pyrazine-2,3-dicarbonitrile and 6-(5,6-dicyano-3-(diethylamino)pyrazin-2-ylamino)hexanoic acid using a statistical condensation approach. AzaPc bearing eight diethylamino peripheral substituents was also isolated from the mixture. Analysis of the distribution of congeners in the statistical mixture using optimized HPLC method (Phenomenex Synergy RP Fusion column, acetonitrile/tetrahydrofuran/water (pH 5.5) 50:20:30) was performed. The analysis showed optimal ratios of starting materials to be 3:1 for AAAB, 1:3 for ABBB and 1:1 for AABB/ABAB types of the congeners. The distribution of the congeners corresponded well with calculated values indicating similar reactivity of both starting materials and no sterical constraint between adjacent isoindole units in the AzaPc ring. All investigated AzaPc showed no fluorescence, extremely low singlet oxygen quantum yields (Φ_? < 0.005) in monomeric form and strong absorption in a wide range from 300 nm to almost 700 nm. Such properties are highly promising for future investigation of these compounds as dark quenchers of fluorescence in DNA hybridization probes.     

Thermal,thermo‐mechanical,and dynamic mechanical properties of polypropylene/cycloolefin copolymer blends

Interaction of the components and physical properties of the polypropylene (PP)/cycloolefin copolymer (COC) blends were studied by means of differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), Vicat softening temperature (VST), and measurements of the coefficient of linear thermal expansion (CLTE) and of the density. The attention was focused on the blends with 90–60% of PP by wt, where the COC minority component was present in the form of short fibers. DSC, DMTA, and density measurements concurrently prove the immiscibility of PP and COC. DSC measurements reveal that crystallinity and melting temperature of the PP component slightly decrease with the fraction of COC in blends, in the range of 56–47% and 164–161°C, respectively. Storage modulus and loss modulus of the blends are in a good accord with the model predictions based on (i) the equivalent box model (EBM) and on (ii) modified equations of the percolation theory. The dependence of the VST on the blend composition is in a good correlation with the previous morphological analysis. Measurements of the coefficient of thermal expansion provide useful data as the functions of temperature and blend composition. Density of the blends was found to obey the volume additivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

SYNERGISTIC EXTRACTION OF LANTHANIDES(III) BY TRIOCTYLMETHYLAMMONIUM NITRATE AND TRIBUTYL PHOSPHATE

ABSTRACT

The synergistic action of tributyl phosphate in the extraction of La(III), Pr(III)Nd(III), Sm(III), Eu(III), Gd(III), Dy(III), Ho(III), Er(III)and Y(III) with trioc-tylmethylammonium nitrate was studied. The synergistic effect is diluent dependent. It is pronounced with a mixed dodecane/xylene diluent, and is weak with mixed heptane/xylene and hexane/xylene diluents as well as with pure xylene diluent. Two or three synergistic complexes are formed simultaneously in the organic phase. Their composition is (A₊)(Ln(N0₃)) ₄),.2B~), (A₊))(Ln(N0₃))J.3B"), and (A₊)) ₂) (Ln(N0₃)) ₅).BJ-) (Ln is a lanthanide(IM), A+ is a trioc-tylmethylammonium cation and B is a tributyl phosphate molecule). The stability of the synergistic complexes generally decreases with increasing atomic number of the lanthanides(III). The synergism enhaces the efficiency of the lanthanide(III) extraction with trioctylmethylammonium nitrate, but deteriorates its selectivity. The separation factors for the Pr(III)-Nd(III) and Eu(III)-Gd(III) pairs are gradually suppressed at increasing concentration of tributyl phosphate.     

Effect of Boron Addition on Micro-Aluminum-Particle-Based Multifunctional High-Temperature Coatings

A novel coating concept for high temperature protection based on spherical micro-sized aluminum particles in combination with boron micro-particles has been developed and investigated. Fractions of 10–20 % boron micro-particles were added to slurries of spherical micro-sized Al, and deposited by brushing on the surface of the austenitic steel alloy 321. A single-sized 3–5 μm Al and a multi sized 1–20 μm Al powder were used. After a heat treatment of 5 h at 650 °C, a homogeneous diffusion layer was formed in the substrate as well as an adherent topcoat. The latter consisted of sintered hollow alumina spheres, which has the potential to provide thermal barrier effect by gas phase insulation. The results from exposure experiments up to 3,000 h show that for the 1–20 μm Al particles, the addition of boron yields topcoats with improved adherence, higher stability and resistance to high temperatures, as well as an outstanding sintering degree. Nano-sized whiskers of Al₄B₂O₉ were observed on the surface of the Al₂O₃ particles when boron was added. The formation mechanism of the borate was studied in situ by high temperature X-ray diffraction.