ECG steganography based on tunable Q‐factor wavelet transform and singular value decomposition

The article presents a novel ECG steganography scheme based on the tunable Q‐factor wavelet transformation (TQWT) and also singular value decomposition (SVD) techniques that ensure better safety and confidentiality of patient information. Initial parameters such as Q, r, and J are used to decompose the cover signal into individual frequency sub‐bands with the tunable Q‐factor wavelet transform (TQWT). The singular value decomposition (SVD) technique is used to further decompose high‐frequency sub‐band coefficients into singular values. The watermark information is then embedded with high‐frequency sub‐band coefficients by involving the quantization process. The performance of this proposed system is successfully evaluated by considering various metrics, such as peak signal to noise ratio (PSNR), structural similarity index (SSIM), percentage residual difference (PRD), and bit error rate (BER). The simulation results of the proposed scheme are observed to be better than other traditional algorithms.     

An Artificial Intelligence Approach for Solving Stochastic Transportation Problems

Recent years witness a great deal of interest in artificial intelligence (AI) tools in the area of optimization. AI has developed a large number of tools to solve the most difficult search-and-optimization problems in computer science and operations research. Indeed, metaheuristic-based algorithms are a sub-field of AI. This study presents the use of the metaheuristic algorithm, that is, water cycle algorithm (WCA), in the transportation problem. A stochastic transportation problem is considered in which the parameters supply and demand are considered as random variables that follow the Weibull distribution. Since the parameters are stochastic, the corresponding constraints are probabilistic. They are converted into deterministic constraints using the stochastic programming approach. In this study, we propose evolutionary algorithms to handle the difficulties of the complex high-dimensional optimization problems. WCA is influenced by the water cycle process of how streams and rivers flow toward the sea (optimal solution). WCA is applied to the stochastic transportation problem, and obtained results are compared with that of the new metaheuristic optimization algorithm, namely the neural network algorithm which is inspired by the biological nervous system. It is concluded that WCA presents better results when compared with the neural network algorithm.     

‘Green’ synthesis of silver polymer Nanocomposites of poly (2-isopropenyl-2- oxazoline-co- N-vinylpyrrolidone) and its catalytic activity

Metal-polymer nanocomposites are of great interest and mainly focused on advanced catalytic and sensor applications. Resulting from this, new copolymers composed of poly(2-isopropenyl-2-oxazoline) (PIPOx) and poly(N-vinylpyrrolidone) (PNVP) segments were prepared from highly water soluble 2-isopropenyl-2- oxazoline (IPOx) and N-vinylpyrrolidone (NVP) monomers. Finally, silver polymer nanocomposites of poly(2-isopropenyl-2-oxazoline-co-N-vinylpyrrolidone) were synthesized and reporting for the first time. All polymerizations were done in an aqueous phase with potassium persulfate as an initiator at 60 °C. The reaction time varied from 1 to 6 h in accordance with stoichiometric ratios of PIPOx and PNVP, leading to insoluble copolymers; which are termed as PIPOx_PNVP (75:25), PIPOx_PNVP (50:50), PIPOx_PNVP (25:75) and PIPOx_PNVP (10:90). Only, PIPOx_PNVP (10:90) showed adequate swelling behavior in water and some other organic solvents. All the polymers were distinguished by various physicochemical spectroscopic techniques such as UV/Visible spectroscopy, Scanning electron microscope (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and FTIR analysis. Thermogravimetry (TGA) and Differential scanning calorimetry (DSC) were used to investigate thermal stability of the samples. The metalo-polymer nanocomposites (PIPOx_PNVP-SNCs) showed an apparently improved stability even when the composites were stored in air, at room temperature. The PIPOx_PNVP-SNCs showed a remarkable catalytic activity during the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of sodium borohydride.     

Spatial distribution and temporal variability of arsenic in irrigated rice fields in Bangladesh. 1. Irrigation water

Around 38% of the area of Bangladesh is irrigated with groundwater to grow dry season crops, most importantly boro rice. Due to high As concentrations in many groundwaters, over 1000 tons of As are thus transferred to arable soils each year, creating a potential risk for future food production. We studied the reactions and changing speciation of As, Fe, P, and other elements in initially anoxic water during and after irrigation and the resulting spatial distribution of As input to paddy soils near Sreenagar (Munshiganj), 30 km south of Dhaka, in January and April 2005 and February 2006. The irrigation water had a constant concentration of 397 +/- 7 microg L(-1) As (approximately 84% As(III)), 11 +/- 0.1 mg L(-1) Fe, and 2 +/- 0.1 mg L(-1) P. During the fast flow along the longest irrigation channel (152 m) As, Fe, and P speciation changed, but total concentrations did not decrease significantly, indicating that As input to fields was independent of the length of the irrigation channels. In contrast, during slow water flow across the fields, As, Fe, and P concentrations decreased strongly with increasing distance from the water inlet, due to formation and settling of As- and P-bearing Fe aggregates and by adsorption to soil minerals. Total As concentrations in field water were approximately 3 times higher close to the inlet than in the opposite field corner shortly after irrigation, and decreased to below 35 microg L(-1) over the next 72 h. The laterally heterogeneous transfer of As, Fe, and P from irrigation waterto soil has important consequences for their distribution in irrigated fields and needs to be considered in sampling and in assessing the dynamics and mass balances of As fluxes among irrigation water, soil, and floodwater.     

ZnO-CdS core-shell quantum dots sensitized solar cell: influence of crystalline and amorphous CdS structures in photovoltaic performance

ZnO nanoparticles (NPs) coated with amorphous and crystalline CdS quantum dots (QDs) were successfully synthesized through chemical bath deposition (CBD) process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been utilized to characterize the samples morphology and structural properties. The conduction band of CdS QDs is much higher than the ZnO conduction band facilitates electron transfer process through cascade system. The thickness and crystallinity of the CdS QDs coated on ZnO NPs critically controls the electron diffusion length and photovoltaic performance of the solar cell. The red shift from 506 to 524 nm, increased optical absorption in the UV-visible range and electron diffusion length limited by the thickness of the amorphous/crystalline CdS QDs coated on ZnO NPs film, influences the performance of the QDs sensitized solar cell (QDSSCs) under one sun illumination intensity (AM 1.5, 100 mW/cm2). The results discuss the CBD process controlled growth of CdS QDs on ZnO NPs and its influence on the photovoltaic performance of QDSSCs.     

PH dependent morphological evolution of beta-Bi2O3/PANI composite for supercapacitor applications

Crystalline beta-Bi2O3 was synthesized through pH-dependent chemical bath deposition process, altering the morphology and evolution from nanoparticles (approximately 40 nm) at pH 9 to platelets (approximately 40 nm width and 0.8 microm length) at pH 12. In-situ aniline nucleation and growth at less basic condition on the beta-Bi2O3 increased the surface area and specific capacitance of the device. The morphological change of beta-Bi2O3/PANI composite from nanoparticles to platelets like nanostructure facilitated higher specific capacitance from 210 to 430 F/g at a scan rate of 10 mV/s with enhanced ionic diffusion and retention of specific capacitance up to 84% at higher scan rates.     

Study of pure and l-tartaric acid doped ammonium dihydrogen phosphate single crystals: A novel nonlinear optical non-centrosymmetric crystal

Single crystals of pure and l-tartaric acid (LTA) C₄H₆O₆ doped ammonium dihydrogen phosphate (ADP) (NH₄) H₂PO₄ were grown by slow evaporation solution technique (SEST) at ambient conditions. Powder X-ray diffraction (PXRD) analysis was carried out to confirm the crystal structure and no additional phase was observed due to doping except a systematic variation in peak intensities. Fourier transform infrared spectral analysis was done to examine the presence of various functional groups in the grown crystals. UV–VIS–NIR spectroscopic analysis was carried out to see the change in optical transparency of pure ADP and crystals due to LTA with different doping concentrations. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystals. The effect of LTA dopant on crystal morphology, thermal and mechanical properties of ADP have also been presented in this paper. The above studies reveal the effect of incorporation of LTA into the lattice of ADP crystals.     

搅拌针压入深度对搅拌摩擦成形AA 5052-H32和AA 6061-T6金属板的接头形成和力学性能的影响（英文）

研究不同等级的AA 5052-H32和AA 6061-T6铝合金搅拌摩擦成形连接的可能性。结果表明,当搅拌针压入深度为0.5~0.7 mm时,采用万能试验机测试得到的搭接剪切载荷为7.16 k N,横向拉伸载荷为3.51 k N,优于采用搅拌摩擦焊和搅拌摩擦点焊在相同材料上焊接的接头的性能。采用光学显微镜观察接头微观组织,发现接头的增强是由于机械销连锁或冶金结合。采用维氏硬度仪测量显微硬度,揭示搅拌针压入深度对搅拌区形成的作用和摩擦热流密度对低层金属薄片的影响。电子显微镜形貌显示,搅拌针压入深度对接头中机械销的形成和几何特征存在显著影响。不同的失效模式,例如销拔出、销剪切、部分结合分层和剥落,取决于不同的搅拌针压入深度形成的关键薄弱区。     

Effect of temperature and electron irradiation on the I–V characteristics of Au/CdTe Schottky diodes

The results of the studies on the effect of temperature and 8 MeV electron irradiation on the current–voltage (I–V) characteristics of the Au/CdTe Schottky diodes are presented in this article. Schottky diodes were prepared by evaporating Au onto n-type CdTe films electrodeposited onto stainless steel substrates. The forward and reverse current–voltage characteristics of these diodes were studied as a function of temperature. The diodes were subjected to 8 MeV electron irradiation at various doses and their effect on the I–V characteristics was studied. Some intrinsic and contact properties such as barrier height, ideality factor, and series resistance were calculated from the I–V characteristics. Diode ideality factor of the junctions were greater than unity. The ideality factor and the series resistance R_s increase with decrease in temperature. The conduction seems to be predominantly due to thermionic emission–diffusion mechanism. The resistance was found to increase with increasing dose. The leakage current, ideality factor and barrier height were found to be unaffected by electron irradiation up to, a dose of about 40 kGy.