Secrecy Trade-off at the Physical Layer over Mixed Fading Multicast Channels Employing Antenna Diversity

This paper deals with the secrecy performance analysis of a multicast network over mixed fading scenarios in which a cluster of passive eavesdroppers is trying to overhear the secret transmission. Our key contribution is to prevent this malicious attack of the illegitimate receivers. Rayleigh/ Rician mixed fading channels are considered to model alternately the multicast/ eavesdropper and eavesdropper/ multicast channels as such mixed fading scenarios are often encountered in cellular communication where only one link (either multicast or eavesdropper) undergo a line-of-sight propagation path. At first, we derive the probability density functions for the single-input-multiple-output multicast scenarios and then the secrecy analysis is carried out by obtaining closed-form expressions for the performance matrices such as the probability of non-zero secrecy multicast capacity, ergodic secrecy multicast capacity, and secure outage probability for multicasting. The derived expressions are beneficial to investigate how the antenna diversity can combat the detrimental impact of fading as well as the number of multicast users and eavesdroppers, and improve the secrecy level to the acceptable limit. Moreover, the best secure scenario in terms of the secrecy parameters is obtained when the multicast channels undergo Rician fading whereas the eavesdropper channels experience Rayleigh fading. Finally, the analytical expressions are justified via the Monte-Carlo simulations.

     

Two stage image de-noising by SVD on large scale heterogeneous anisotropic diffused image data

Multimedia Tools and Applications - De-noising of images along with the edge enhancement has always been a challenging task in large scale heterogeneous image data. This paper presents a two stage...     

Edge preservation of impulse noise filtered images by improved anisotropic diffusion

This paper provides a robust scheme for random valued impulsive noise reduction along with edge preservation by anisotropic diffusion with improved diffusivity. The defective impulse noisy pixels are detected by Laplacian based second order pixel difference operation where these defective pixels are replaced by appropriate values with regard of the gray level of their four directional neighbors. This de-noised image undergoes the diffusion operation where diffusion coefficient function is modified to make it adaptive by incorporating local gray level variance information. The proposed modified diffusion scheme effectively restore the edges and fine details destroyed during impulse noise reduction process. The effect of proposed diffusion scheme has been studied on various images and the results are compared with some existing diffusion methods which are independently used for impulse noise reduction and edge preservation. The results shows that the prior removal of impulsive noise before the application of diffusion process is advantageous over the direct application of diffusion for removing the impulsive noise. In addition, the results of the proposed diffusion scheme are compared with some of the median filter based methods which are effectively used for impulse noise reduction without caring of edge preservation. The proposed diffusion scheme sufficiently preserves the edges without boosting of impulsive noise components on images corrupted up to 50 % of the impulsive noise density.     

Sputtered AZO Thin Films for TCO and Back Reflector Applications in Improving the Efficiency of Thin Film a-Si:H Solar Cells

We report the properties of Al doped ZnO (AZO) thin films on glass substrates and its effect on the efficiency of amorphous silicon (a-Si:H) solar cells as the back reflector. Oriented AZO thin films were grown using DC magnetron sputtering by varying Ar gas flow rates. The influence of Ar flow rate on the structural, electrical and optical properties of AZO thin films suitable for transparent conducting oxide (TCO) and back reflector applications was investigated. The (a-Si:H) solar cells, with and without AZO back reflector, were fabricated on FTO coated glass substrates using the PECVD technique. The solar cells were tested using a Sun simulator under AM 1.5 condition. Enhancement in current density from 12.46 to 14.24 mA/cm² with the AZO back reflector was observed, thereby increasing the efficiency of the solar cell from 6.38 to 7.82 %, respectively.     

Chemical kinetics of carbon dioxide in the blends of different amino acid salts and methyldiethanolamine

In the present study, the reaction kinetics of carbon dioxide (CO₂) with two blends of N-methyldiethanolamine; potassium salts of taurine and potassium salts of glycine were investigated. The experiments were performed using a stopped flow apparatus over a range of temperature varying from 293 to 313 K. The concentration of solution was varied from 0.2 to 0.8M in different proportions of potassium salts of taurine and glycine. For both cases, the overall reaction rate constant (k_ov) increased with increased temperature and amino acid salts proportions in the blends. Results also indicated that addition amino acid salts (AAS) could improve the overall reaction rate of methyldiethanolamine (MDEA) with CO₂ by more than 100 times. The kinetics data were interpreted using the widely accepted mechanisms namely; zwitterion and termolecular mechanisms. An average absolute deviation of 8.8% was observed for both mechanisms applied to MDEA-KTau blend, while an AAD% of 7.4 and 7.2 were observed for the case of MDEA-KGly system when applying the zwitterion and termolecular mechanisms, respectively. The results showed that blends of MDEA and potassium salts amino acids react faster with CO₂ compared to conventional amine systems. Hence, the use of both potassium salts of taurine and glycine as rate promotors can significantly enhance the reactivity of MDEA toward CO₂.     

Affective Temperature Control in Food SMEs using Artificial Neural Network

This paper highlights modeling affective temperature control in food small and medium-sized enterprises (SMEs). Modeling defined that workstation temperature set point could be controlled based on worker heart rate and workstation environment using Artificial Neural Network (ANN). The research objectives were: 1) to propose modeling affective temperature control in food SMEs based on heart rate and workstation environment; and 2) to develop an ANN model for predicting workstation temperature set point. Training and validation data were collected from six food SMEs in Yogyakarta Special Region, Indonesia. The data of temperature set points were verified using a simulated confined room. The inputs of the ANN model were worker heart rate, workstation temperature, relative humidity distribution and light intensity. The output was temperature set point. Research results concluded satisfactory performance of ANN. The model could be used to provide environmental ergonomics in food SMEs.     

An application of Pareto analysis and cause-and-effect diagram (CED) to examine stoppage losses: a textile case from Bangladesh

Spinning industries are facing challenges of improving productivity in the competitive market nowadays. Ring spinning, the most widely used yarn manufacturing process for short staple spinning, uses several types of machinery from blow room to ring frame for producing yarns from cotton fibers. An enterprise can improve utilization of resources by identifying unwanted machine stoppage and taking corrective actions at different points in the production cycle. This study focuses on the major six stoppage losses that are used to calculate Overall Equipment Efficiency (OEE) of ring frame section. The Pareto analysis reveals that idling and minor stoppage and breakdown losses are responsible 89.3% of total stoppage losses. According to cause-and-effect analysis, root causes for the stoppage losses are: high doffing time, high traveler changing time, broken end of yarn due to piles generation through the front roller, power failure and change in Draft Change Pinion (DCP) due to breakage of teeth of the gear during starting of machine by operators before lowering of ring rail and change of Twist Change Pinion (TCP) due to the displacement of TCP gear shaft. Finally, few recommendations are made to reduce stoppage losses and to increase the productivity of the ring frame section.     

Engineering of Mature Human Induced Pluripotent Stem Cell‐Derived Cardiomyocytes Using Substrates with Multiscale Topography

Producing mature and functional cardiomyocytes (CMs) by in vitro differentiation of induced pluripotent stem cells (iPSCs) using only biochemical cues is challenging. To mimic the biophysical and biomechanical complexity of the native in vivo environment during the differentiation and maturation process, polydimethylsiloxane substrates with 3D topography at the micrometer and sub‐micrometer levels are developed and used as cell‐culture substrates. The results show that while cylindrical patterns on the substrates resembling mature CMs enhance the maturation of iPSC‐derived CMs, sub‐micrometer‐level topographical features derived by imprinting primary human CMs further accelerate both the differentiation and maturation processes. The resulting CMs exhibit a more‐mature phenotype than control groups—as confirmed by quantitative polymerase chain reaction, flow cytometry, and the magnitude of beating signals—and possess the shape and orientation of mature CMs in human myocardium—as revealed by fluorescence microscopy, Ca²⁺ flow direction, and mitochondrial distribution. The experiments, combined with a virtual cell model, show that the physico‐mechanical cues generated by these 3D‐patterned substrates improve the phenotype of the CMs via the reorganization of the cytoskeletal network and the regulation of chromatin conformation.