A Robust Peak-to-Average Power Ratio Reduction Scheme by Inserting Dummy Signals with Enhanced Partial Transmit Sequence in OFDM Systems

Peak-to-average power ratio (PAPR) is one of the main drawbacks in orthogonal frequency division multiplexing (OFDM) systems. High PAPR forces the power amplifier to back off in order to operate in its linear region, which degrades the power efficiency of the system. Several PAPR reduction techniques have been developed, but most of them have not considered both complexity and PAPR reduction. In this paper, a novel PAPR reduction scheme based on the insertion of dummy sequences to an enhanced partial transmit sequence is proposed. By applying this scheme the PAPR performance is enhanced compared to the conventional methods while the complexity is significantly reduced. Numerical analysis is carried out with OFDM signal and QPSK modulation.     

Nanoelectromechanical Chip (NELMEC) Combination of Nanoelectronics and Microfluidics to Diagnose Epithelial and Mesenchymal Circulating Tumor Cells from Leukocytes

An integrated nano‐electromechanical chip (NELMEC) has been developed for the label‐free distinguishing of both epithelial and mesenchymal circulating tumor cells (ECTCs and MCTCs, respectively) from white blood cells (WBCs). This nanoelectronic microfluidic chip fabricated by silicon micromachining can trap large single cells (>12 µm) at the opening of the analysis microchannel arrays. The nature of the captured cells is detected using silicon nanograss (SiNG) electrodes patterned at the entrance of the channels. There is an observable difference between the membrane capacitance of the ECTCs and MCTCs and that of WBCs (measured using SiNG electrodes), which is the key indication for our diagnosis. The NELMEC chip not only solves the problem of the size overlap between CTCs and WBCs but also detects MCTCs without the need for any markers or tagging processes, which has been an important problem in previously reported CTC detection systems. The great conductivity of the gold‐coated SiNG nanocontacts as well as their safe penetration into the membrane of captured cells, facilitate a precise and direct signal extraction to distinguish the type of captured cell. The results achieved from epithelial (MCF‐7) and mesenchymal (MDA‐MB231) breast cancer cells circulated in unprocessed blood suggest the significant applications for these diagnostic abilities of NELMEC.     

A computer-aided diagnosis system for malignant melanomas

The aim of this study is to provide an efficient way to segment the malignant melanoma images. This method first eliminates extra hair and scales using edge detection; afterward, it deduces a color image into an intensity image and approximately segments the image by intensity thresholding. Some morphological operations are used to focus on an image area where a melanoma boundary potentially exists and then used to localize the boundary in that area. The distributions of texture and a new feature known as AIBQ features in the next step provide a good discrimination of skin lesions to feature extraction. Finally, we rely on quantitative image analysis to measure a series of candidate attributes hoped to contain enough information to differentiate malignant from benign melanomas. The selected features are applied to a support vector machine to classify the melanomas as malignant or benign. By our approach, we obtained 95 % correct classification of malignant or benign melanoma on real melanoma images.     

Effect of vegetated-banks on local scour around a wing-wall abutment with circular edges

Failure of bridges due to local scour in the vicinity of bridge abutments is a common occurrence. In this study, experiments under two different channel conditions were conducted to assess the impacts of vegetation on channel banks on local scour around a wing-wall abutment with circular edges. Some experiments were conducted in channel with vegetation on channel banks, and other experiments in channel without vegetation on channel bank. The flow velocity and Reynolds stress distributions in scour holes around a wing-wall abutment with circular edges were compared under these 2 different channel conditions. Results reveal that the vegetated-banks can reduce the time for achieving the equilibrium condition from 17 h to 9 h. Also, vegetated-bank channels can result in a significant decrease in the maximum scour depth from 0.084 m（for bare channel bank） to 0.00032 m. Additionally, around the abutment, vegetated-banks play a significant role in diminishing the Reynolds stress（RS） near the bed and removing negative values in RS distribution by weakening unfavorable pressure gradient and down-flow in the upstream of abutment.     

Microwave-assisted encapsulation of citric acid using hydrocolloids

This study elucidates the capability of a novel technique for producing microcapsules at an enormously short time and low cost. This technique is based on the difference between dielectric constants of core and coat materials. Edible citric acid was mixed with various biomacromolecules at ratios of 1:5, 1:10, and 1:100. Each mixture was treated up to 600 s at various powers (120–1200 W) in a microwave oven. Subsequently, the microcapsules were separated by distinct sieves, and their apparent structure and quality were evaluated using binoculars, and photographs were taken for visual comparisons. Our observations showed that only five hydrocolloids were able to produce high-quality and efficient encapsulation [casein > inulin > carboxymethylcellulose (CMC) > low methoxyl (LM) pectin (9/5%) > sorbitol]. Moreover, the highest coating efficiency was seen at highest intensity (1200 W) at a mixing ratio of 1:10. Furthermore, the optimum treating time periods for those five efficient coating materials were about 400, 75, 400, 100, and 100 s.     

Effects of chemical surface pretreatment on tensile properties of a single glass fiber and the glass fiber reinforced epoxy composite

The aim of this article is to determine the effect of surface pretreatments, prior to the silanization, on the structure and tensile properties of the glass fibers and their epoxy composites. Commercial glass fibers were washed with acetone to remove the soluble portion of sizing, calcinated for the removal of organic matter, activated for surface silanol regeneration, and silanizated with glycidoxypropyltrimethoxysilane (GPS). Tensile test was carried out. The morphology of pretreated glass fibers and the fracture surfaces of the epoxy composites were observed with a scanning electron microscope (SEM). The results revealed that both apparent modulus and strength of a single glass fiber and the glass fiber/epoxy resin composites strongly depend on the fiber surface pretreatments. The acetone treatment did not change appreciably the composition and tensile properties of glass fibers, but there was a weak interface between fibers and matrix. In calcinated and acid activated fibers, the two competitive effects was observed: (1) degradation of the fibers themselves and (2) improved interfacial adhesion between the glass fibers and the epoxy matrix, once the samples was silanizated. The ATR‐FTIR results show that the surface content of Si OH increases as reflected by the increasing of the Si O band, resulting in an interaction between silane coupling agent and glass fiber. POLYM. COMPOS., 91–100, 2016. © 2014 Society of Plastics Engineers     

Irradiation grafting of methyl methacrylate monomer onto ultra‐high‐molecular‐weight polyethylene: An experimental design approach for improving adhesion to bone cement

The grafting of methyl methacrylate (MMA) onto ultra‐high‐molecular‐weight polyethylene (UHMWPE) and chromic acid etched UHMWPE was conducted with a preirradiation method in air in the presence of a Mohr salt and sulfuric acid. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, a gravimetric method, differential scanning calorimetry, scanning electron microscopy (SEM), and interfacial bonding strength measurements. The FTIR results showed the presence of ether and carbonyl groups in the MMA‐grafted UHMWPE (MMA‐g‐UHMWPE) samples. The Taguchi experimental design method was used to find the best degree of grafting (DG) and bonding strength. The efficient levels for different variables were calculated with an analysis of variance of the results. SEM micrographs of MMA‐g‐UHMWPE samples showed that with increasing DG and chromic acid etching, the MMA‐g‐UHMWPE rich phase increased on the surface; this confirmed the high interfacial bonding strength of the grafted samples with bone cement. The grafting of the MMA units onto UHMWPE resulted in a lower crystallinity, and the crystallization process proceeded at a higher rate for the MMA‐g‐UHMWPE samples compared to the initial UHMWPE; this suggested that the MMA grafted units acted as nucleating agents for the crystallization of UHMWPE. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis, characterization and application of allyl phenol modified amberlite XAD-4 resin for preconcentration and determination of copper in water samples

A new chelating resin was prepared by coupling Amberlite XAD-4 with phenol through an azo spacer, then modified by allyl bromide and characterized (by elemental analysis and IR) and studied for preconcentration of Cu(II) using flame atomic absorption spectrometry (FAAS) for metal monitoring. The optimum pH value for sorption of the above mentioned metal ion was 4.5. The resin was subjected to chemical evaluation through batch binding and column chromatography of Cu(II). The chelating resin can be reused for 15 cycles of sorption-desorption without any significant change in sorption capacity. A recovery of 98% was obtained for the metal ion with 0.5 M HNO₃ as eluting agent. The equilibrium adsorption data of Cu(II) on modified resin were analyzed by Langmuir, Freundlich and Temkin models. Based on equilibrium adsorption data the Langmuir, Freundlich and Temkin constants were determined to be 0.061, 0.193 and 0.045 at pH 4.5 and 25 °C. The method was applied for the copper determination from industrial waste water sample.     

Properties of waste‐poly(ethylene terephthalate)/acrylonitrile butadiene styrene blends compatibilized with maleated acrylonitrile butadiene styrene

Waste poly(ethylene terephthalate) (W‐PET)/acrylonitrile‐butadiene‐styrene (ABS) blends were prepared with a variety of compositions at several rotor speeds in an internal mixer, replacing ABS with different maleated ABS (ABS‐g‐MA) samples in compatibilized blends. A Box–Behnken model for three variables, with three levels, was chosen for the experimental design. ABS‐g‐MA‐based samples exhibited finer particles with a more uniform particle size distribution than ABS‐based ones, as a consequence of the compatibilizing process. Rheological results implied a greater elastic nature for compatibilized blends which increased in the presence of more ABS content; the same trend was observed for complex viscosity. With increasing ABS‐g‐MA or MA concentration, more shear thinning behavior was observed similar to that of ABS; whereas the uncompatibilized blends showed Newtonian behavior like that of W‐PET. The observed shifting in T_gW‐PET and T_gABS obtained from dynamic mechanical thermal analysis confirmed the good compatibility in W‐PET/ABS‐g‐MA blends in contrast with that in ordinary W‐PET/ABS blends. The mechanical properties were measured and modeled versus the various factors considered in a response surface methodology. The experimental data found a good fit with the obtained equation models. The mechanical properties of the compatibilized blends showed a large positive deviation from the mixing rule, while the uncompatibilized samples had lower properties, even compared to those predicted by the mixing rule. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers