Tribological properties of dispersed carbon nanotubes in lubricant

This study examined the tribological properties of two lubricating oils, mobil gear 627 and paraffinic mineral oils, with multi-walled carbon nanotubes (MWCNTs) nanoparticles used as additives with various concentrations (0.1, 0.5, 1, and 2 wt.%). The friction and wear experiments were performed using a four ball tribotester. The samples were tested for their anti-wear, load carrying capacity, and friction coefficients according to ASTM D-2783, ASTM D-2596, and ASTM D-5183 standards. The experimental results show that the addition of MWCNTs to base oils exhibit good friction reduction and anti-wear properties. The wear test results show a decreased wear by 68% and 39% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. Furthermore, the friction reduction results show a decrease of friction about 57% and 49% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. The weld load of the base oil containing 1% MWCNTs was found to be 400 kgf and 125 kgf as compared with base mobil gear 627 and paraffinic mineral oils, respectively, which got welded at 200 kgf and 100 kgf. The morphologies and typical element distribution of the worn surfaces were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDX). The SEM micrographs and EDX chemical analysis confirm the formation of a tribolayer composed of the elements from the nanoparticles.     

Automated localization of retinal features

Retinal fundus images are widely used in the diagnosis and treatment of various eye diseases, such as diabetic retinopathy and glaucoma. A computer-aided retinal fundus image analysis could provide an immediate detection and characterization of retinal features prior to specialist inspection. This paper proposes an approach to automatically localize the main features in fundus images, such as blood vessels, optic disc, and fovea by exploiting the spatial and geometric relations that govern their distribution within the fundus image. The blood vessels are segmented by scale-space analysis. The average thickness of these blood vessels is then computed using the vessels centerlines and orientations from a Hessian matrix. The optic disc is localized using the circular Hough transform, the parabolic Hough transform fitting, and the localization of the fovea. The proposed method can be extended to establish a foveal coordinate system to facilitate grading lesions based on the spatial relationships between lesions and landmark features. The proposed method was evaluated on publicly available image databases, and the results have demonstrated a significant improvement over the current state-of-the-art methods.     

Detection of the effect of environmental toxicants on the synthetic peptide modified neural cell chip

A cell based chip was designed to differentiate and to detect the effects of environmental chemicals on the neurite outgrowth in PC12 cell. To fabricate platform of cell chip, gold surfaces were modified by RGD based synthetic oligopeptide. Nanoscale controlled self-assembled peptide layer was investigated by Atomic Force Microscopy (AFM). On the fabricated cell chip, PC12 cell was immobilized and the differentiation of neurite outgrowth in PC12 cells was done by neurite growth factor (NGF). Differentiation of PC12 cell was confirmed by immunofluorescence study. Further the differentiation and the length of neurite was confirmed by confocal microscopy study. Voltammetry behavior of the neurite induced PC12 and the electrochemical behavior of the environmental toxicants effect on the neurite outgrowth was measured by cyclic voltammetry (CV). Self-assembled layer mediated cell immobilization technique and voltammetric signal analysis system can be applied to construct the neural cell chip for the detection of large number of environmental toxins and various neurotoxicants.     

Chaotic Interleaving for Robust Image Transmission with LDPC Coded OFDM

To improve the error resilience and video quality over wireless networks, we propose a novel packet-level layer-based interleaving unequal forward error correction (LIU-FEC) method. First, a scalable layer-based interleaving architecture is proposed for improving the efficiency of FEC from successive packet losses in variable channel conditions. The interleaved transmission across different scalable layers can efficiently disperse the consecutive packet losses into different scalable layers. Second, a closed form FEC assignment solution is proposed for minimizing video quality degradation using simple layer-based error propagation metric in hierarchical prediction structure. The simulation results show that the proposed algorithm offers higher PSNR values in various channel status, compared to the conventional FEC algorithm.     

Development impacts on groundwater resources in Bahrain

The development process in Bahrain has led to a continuous depletion of its groundwater resources. The unplanned, excessive pumping of groundwater caused a sharp decrease in groundwater storage and the lowering of the aquifer's potentiometric levels by about 4 metres in the period from 1925 to 1991. As a result, more than half of the original groundwater reservoir has been completely polluted. Development activities will be hindered if the effects of these activities on the groundwater reservoir are not realized. In order to sustain the aquifer usefulness in the development process, the reservoir's natural balance must be re‐established. Therefore, the need for multi‐objective planning aiming at integrating Bahrain's limited water resources capacity and water demands is of paramount importance.     

All fiber on-axis coupling scheme between single mode fiber and GRIN fiber

In this paper we present a simple and novel method to maximize on-axis coupling efficiency to radially symmetric fibers without the need for extra free space optical elements. The method is based on inserting a segment of step-index multimode fiber (MMF), cleaved to a particular length, between the input fiber and the output fiber (OF). The MMF segment modifies the input field to match the guided modes in the OF. Using this technique we show that, by inserting an appropriate length MMF segment, it is theoretically possible to obtain a coupling coefficient as high as ?0.8 dB between a single mode fiber and a graded index ring-shaped fiber and ?0.32 dB for a multi-shell fiber. Our experimental measurements showed good agreement with theoretical predictions for the ring fiber.     

A Radon-Multiwavelet Based OFDM System Design and Simulation Under Different Channel Conditions

Finite Radon transform (FRAT) mapper has the ability to increase orthogonality of sub-carriers, it is non sensitive to channel parameters variations, and has a small constellation energy compared with conventional fast Fourier transform (FFT) based orthogonal frequency division multiplexing (OFDM). It is also able to work as a good interleaver which significantly reduces the bit error rate (BER). Due to its good orthogonality, discrete Multiwavelet transform (DMWT) is attractive for implementation in OFDM systems which reduces inter-symbol interference (ISI) and inter-carrier interference (ICI) and eliminates the need for cyclic prefix and increases the spectral efficiency of the design. In this paper both FRAT and DMWT are implemented in a new design for OFDM. The new structure was tested and compared with conventional FFT-based OFDM, Radon-based OFDM, and DMWT-based OFDM for additive white Gaussian noise channel, flat fading channel, and multi-path selective fading channel. Simulation tests were generated for different channels parameters values. The obtained results showed that proposed system has increased spectral efficiency, reduced ISI and ICI, and improved BER performance compared with other systems.     

Simultaneous Fusion and Denoising of Panchromatic and Multispectral Satellite Images

To identify objects in satellite images, multispectral (MS) images with high spectral resolution and low spatial resolution, and panchromatic (Pan) images with high spatial resolution and low spectral resolution need to be fused. Several fusion methods such as the intensity–hue–saturation (IHS), the discrete wavelet transform, the discrete wavelet frame transform (DWFT), and the principal component analysis have been proposed in recent years to obtain images with both high spectral and spatial resolutions. In this paper, a hybrid fusion method for satellite images comprising both the IHS transform and the DWFT is proposed. This method tries to achieve the highest possible spectral and spatial resolutions with as small distortion in the fused image as possible. A comparison study between the proposed hybrid method and the traditional methods is presented in this paper. Different MS and Pan images from Landsat-5, Spot, Landsat-7, and IKONOS satellites are used in this comparison. The effect of noise on the proposed hybrid fusion method as well as the traditional fusion methods is studied. Experimental results show the superiority of the proposed hybrid method to the traditional methods. The results show also that a wavelet denoising step is required when fusion is performed at low signal-to-noise ratios.     

Concentration and Exposure Assessment of Mercury in Commercial Fish and Other Seafood Marketed in Oman

The results of this study present analytical data of the mercury levels in several fish and shellfish species to create awareness among individuals of the risks associated with consuming fish contaminated with mercury. Mercury concentrations varied from a mean of 0.02 mg/kg in Indian mackerel to 0.19 mg/kg in shark in both fresh and frozen fish, from 0.02 mg/kg in sardines to 0.18 mg/kg in skipjack tuna in canned fish, and from 0.02 mg/kg in Indian mackerel to 0.79 mg/kg in shark in dried fish. Shellfish contained a slightly higher amount of mercury than fresh or frozen fish with a mean of 0.09 mg/kg. Trophic position, followed by habitat, was the most important factors for variability in mercury concentrations in fish and shellfish. The maximum safe weekly intake (MSWI) values of mercury were significantly higher for herbivores than for carnivores. The MSWI value for total mercury in the case of consuming most (72%) fish species was more than 5 kg; however, the MSWI value was never more than 5 kg in most (66%) shellfish species. Risks were identified upon consumption of 120 g of dried shark when exceeding the provisional tolerable weekly intake threshold (1.6 μg/kg) for methylmercury. Therefore, fish‐eating populations should reduce the quantity of dried shark to efficiently diminish the exposure to mercury.