Wave propagation in a composite with a wavy sublamina

The through-thickness waviness in a sublamina in a composite laminate is the subject of study for the purposes of nondestructive evaluation by ultrasound. The model consists of a flat composite laminate with one sublamina which has sinusoidal waviness. The theoretical analysis of a longitudinal wave propagating through such a laminate is presented and the reflection coefficients at various locations on the plate are calculated. The results are validated by experimental ultrasonic C-scan.     

Extra-pulmonary effects of inhaled nitric oxide in swine with and without phenylephrine

Whether radiofrequency (RF) fields are carcinogenic is controversial; epidemiological data have been inconclusive and animal tests limited. The aim of the present study was to determine whether long-term exposure to pulse-modulated RF fields similar to those used in digital mobile telecommunications would increase the incidence of lymphoma in E mu-Pim1 transgenic mice, which are moderately predisposed to develop lymphoma spontaneously. One hundred female E mu-Pim1 mice were sham-exposed and 101 were exposed for two 30-min periods per day for up to 18 months to plane-wave fields of 900 MHz with a pulse repetition frequency of 217 Hz and a pulse width of 0.6 ms. Incident power densities were 2.6-13 W/m2 and specific absorption rates were 0.008-4.2 W/kg, averaging 0.13-1.4 W/kg. Lymphoma risk was found to be significantly higher in the exposed mice than in the controls (OR = 2.4. P = 0.006, 95% CI = 1.3-4.5). Follicular lymphomas were the major contributor to the increased tumor incidence. Thus long-term intermittent exposure to RF fields can enhance the probability that mice carrying a lymphomagenic oncogene will develop lymphomas. We suggest that such genetically cancer-prone mice provide an experimental system for more detailed assessment of dose-response relationships for risk of cancer after RF-field exposure.     

Pyroelectric performance of porous Ba0.85Sr0.15TiO3 ceramics

Porous Ba_0.85Sr_0.15TiO₃ (BST) ferroelectric ceramics were synthesized by sintering compacts consisting of BST and Poly(methyl methacrylate) (PMMA) (2%, 4%, 6%, 8%, and 10% by wt.) as pore‐forming agent. Systematic investigation of role of porosity on microstructural, dielectric, and pyroelectric performance is carried out. It is observed that as PMMA increased from 0% to 10%, the porosity increased from 7.5% to 29.5%. Dielectric constant decreases and dielectric loss increases with increasing PMMA content at fixed frequency. When porosity reached 29.5%, the relative dielectric constant of the BST composition decreased by more than 78% (from 3500 to 750) at 10 kHz and 300 K. Porosity leads to a significant reduction in dielectric constant and volume‐specific heat capacity, which are of great interest for improving pyroelectric figure of merits (FOMs). Further, the pyroelectric figure of merits for current responsivity (F_i), voltage responsivity (F_v), detectivity (F_d), and energy harvesting (F_e and F_e*) are calculated for all investigated compositions. Compared with dense ceramic, porous BST (10% PMMA) showed an improvement of F_d by 19%, F_e by 61%, and F_e* by 98%. F_v increased by 210% at 300 K/10 kHz. All of these advancements are favorable for the development of pyroelectric devices.     

Understanding the Effect of Tamarind Gum Proportion on the Properties of Tamarind Gum-Based Hydroethanolic Physical Hydrogels

The present study reports the analysis of properties of tamarind gum-based hydroethanolic physical hydrogels. The extent of hydrogen bonding in hydrogels decreased with an increase in tamarind gum content. The hydrogel with the highest tamarind gum content was found to be highly stable in terms of mechanical properties. There was a decrease in the resistive component of the hydrogels with an increase in tamarind gum content. The drug release from the hydrogels increased with an increase in the tamarind gum content. The antimicrobial activity of the drug-loaded hydrogels against Escherichia coli was excellent.     

Secure energy aware routing protocol for trust management using enhanced Dempster Shafer evidence model in multi-hop UWAN

Wireless Networks - At present, underwater wireless ad hoc networks (UWAN) are widely used in enormous applications. At the same time, UWAN faced many security issues, like energy leaks. The energy...     

A secure multi-hop relay node selection scheme based data transmission in wireless ad-hoc network via block chain

In today’s scenario, data transmission is established through the single or multi-hop relay nodes in Wireless Ad-Hoc Networks (WANET). Traditional relay node selection techniques undergo collusion attacks, increased energy consumption, delay, and reduced network lifetime. To cope with these problems, we propose a Quantum Atom Search Optimization coupled with Blockchain aided Data Transmission (QASO-BDT) scheme for a relay node selection with security aided data transmission. This approach comprises three phases such as registration, clustering, and transmission. Initially, in the node registration phase every sensor node gets registered in the blockchain network through Capillary Gateway (CG). Next, in the clustering phase, a CH is selected and an enhanced multi-view clustering model is used to cluster the nodes into several clusters. Finally, the multi-hop transmission phase assists in best relay node selection for multi-hop transmission using QASO, and the blockchain-based transaction is carried out to ensure security in the system. The proposed scheme is simulated in the MATLAB platform and achieves a result of 91.5% throughput, the reduced energy value of 40%, end to end delay of 20.6%, and the exhaustion of node is 1% which results in an increased lifetime of the nodes. Also, security is evaluated in comparison with other traditional methods.

     

Reinforcement learning in robotic applications: a comprehensive survey

In recent trends, artificial intelligence (AI) is used for the creation of complex automated control systems. Still, researchers are trying to make a completely autonomous system that resembles human beings. Researchers working in AI think that there is a strong connection present between the learning pattern of human and AI. They have analyzed that machine learning (ML) algorithms can effectively make self-learning systems. ML algorithms are a sub-field of AI in which reinforcement learning (RL) is the only available methodology that resembles the learning mechanism of the human brain. Therefore, RL must take a key role in the creation of autonomous robotic systems. In recent years, RL has been applied on many platforms of the robotic systems like an air-based, under-water, land-based, etc., and got a lot of success in solving complex tasks. In this paper, a brief overview of the application of reinforcement algorithms in robotic science is presented. This survey offered a comprehensive review based on segments as (1) development of RL (2) types of RL algorithm like; Actor-Critic, DeepRL, multi-agent RL and Human-centered algorithm (3) various applications of RL in robotics based on their usage platforms such as land-based, water-based and air-based, (4) RL algorithms/mechanism used in robotic applications. Finally, an open discussion is provided that potentially raises a range of future research directions in robotics. The objective of this survey is to present a guidance point for future research in a more meaningful direction.

     

Discrimination of maize crop with hybrid polarimetric RISAT1 data

Microwave remote sensing provides an attractive approach to determine the spatial variability of crop characteristics. Synthetic aperture radar (SAR) image data provide unique possibility of acquiring data in all weather conditions. Several studies have used fully polarimetric data for extracting crop information, but it is limited by swath width. This study aimed to delineate maize crop using single date hybrid dual polarimetric Radar Imaging Satellite (RISAT)-1, Fine Resolution Stripmap mode (FRS)-1 data. Raney decomposition technique was used for explaining different scattering mechanisms of maize crop. Supervised classification on the decomposition image discriminated maize crop from other land-cover features. Results were compared with Resourcesat-2, Linear Imaging Self Scanner (LISS)-III optical sensor derived information. Spatial agreement of 91% was achieved between outputs generated from Resourcesat-2, LISS-III sensor and RISAT-1 data.     

A perceptible watermarking algorithm for audio signals

This paper proposes an unconventional method for removable audible watermarking system based on the requirements of a promising application .Given an audio file, the system makes some part of file available for preview and perceptual watermarking on the remaining portion. The watermark is embedded into selected DCT coefficients of host audio signal so that the signal to noise ratio is maintained at a level which is audibly annoying to human auditory system. An issue that arises here is generating huge number of copies of the audio file which are audibly similar and numerically different. Once the audio file is decoded using the secret key a new watermark is embedded in the audio that is perceptually transparent to the human auditory system. Hence this double watermarking i.e. imperceptible and perceptible watermarking provides a novel prototype for digital right management control. The subjective quality tests and robustness tests indicate that the audio quality is excellent and is robust to signal processing attacks.     

Evaluation of Prosopis juliflora as a potential feedstock for the production of sodium lignosulfonate from the spent liquor of a laboratory digester

Abstract

Chopped stems of Prosopis juliflora, an invasive xerophyte, were digested in a laboratory digester following alkaline sulfite pulping process to generate spent liquor whereby lignin underwent sulfonation to produce sodium lignosulfonate (SLS). SLS was concentrated from the spent liquor by ultrafiltration. Raw wood was featured by high lignin (23.5%), low extractives (1.0%), low wax (0.41), and low ash (2.25%) content thus making it an ideal feedstock to produce lignosulfonates with appreciable physico-chemical property and relatively high mechanical strength. Attempts were made to provide basic information on SLS structure and structural changes that might occur during pulping of P. juliflora under the present experimental conditions. Spectral and X-ray diffraction studies on as-produced SLS revealed substantial depolymerization and structural modification of lignin during sulfite pulping. The derived SLS had higher crystallinity index than the feedstock wood. Effect of average size of raw wood chip and dose of sodium sulfite in the overall yield of pulp and SLS along with the kappa number of the pulp were also analyzed. Findings from this study would serve to cultivate a better understanding of the potential of P. juliflora as a feedstock, so far unexplored, to produce SLS???a value-added product with numerous commercial applications. The use of this particular plant species in paper and pulp industry could also be considered as an effective means of integrated agro management in rural areas.