Bandwidth and frequency agile MIMO antenna for cognitive vehicular communications

A reconfigurable MIMO antenna for heterogeneous vehicular networks is reported in this paper. The frequency and bandwidth characteristics of the MIMO antenna can be reconfigured to meet multi-standard and multi-frequency requirements in automobiles. The antenna element evolved from an edge-chamfered ultra-wideband (UWB) antenna operating from 2.1 to >15 GHz. The bandwidth reconfiguration is achieved through the selection of excitation paths connecting the feed and radiator. The feedline selection is performed using PIN diodes, making the antenna operate in three distinct modes, namely, UWB mode (Mode 1: 2.1–>15 GHz), industrial, scientific and medical/Internet of Things (ISM/IoT) mode (Mode 2: 2.45 GHz), and wireless local area network (WLAN) mode (Mode 3: 5–6 GHz). The feed path corresponding to Mode 2 and Mode 3 is incorporated with a suitable filtering network to shape the frequency response of the antenna based on the user's requirements. Owing to the requirement of cognitive selection of frequency bands, the frequency tunability in Mode 2 is realized using varactor diodes. The varactor-incorporated feed path reconfigures the center frequency between 2.45 and 3.5 GHz. The proposed MIMO antenna offers gain and total efficiency greater than 2.94 dBi and 76%, respectively. The prototype of the 4-port MIMO antenna is being fabricated to test its functionality in real time.     

Delayed hydride cracking velocity in Zr-2.5Nb: detection by acoustic emission and theoretical model testing

Acoustic emission (AE) detects elastic waves generated during delayed hydride cracking (DHC). The detection of the first acoustic signal is used to measure the propagation time. This time and the crack length measured on the broken specimen are used to determine the DHC velocity. In this work, DHC tests were carried out on Zr-2.5Nb alloy from CANDU pressure tubes. Linear relationship between cumulative count rate and cracking velocity was corroborated. It is generally accepted that the hydrides crack when they reach a critical length; nevertheless, in this work the number of signals generated during typical DHC test were higher than expected from that assumption. Dutton and Puls DHC model with some parameters calculated by Shmakov et al. was used to test out against experimental data. This modification is an original approach that makes more rational the DHC velocity calculation, avoiding arbitrary parameter selection. Good agreement was obtained for two different CANDU pressure tubes.     

Social influence determination on big data streams in an online social network

Social networks have become a good place to promote products and also to campaign for causes. Maximizing the spread of information in an online social network at a least cost has attracted the attention of publicist’s. In general, influence user ranking methods are derived either by a network’s topological features or by user features but not both. Existing Influence Maximization Problem (IMP) operates as a modification of greedy algorithms that cannot scale streaming data. Which are time consuming and cannot handle large networks because it requires heavy Monte-Carlo simulation. This is also an NP hard problem in both linear threshold and independent cascade models. Our proposed work aims to address IMP through a Rank-based sampling approach in the Map-Reduce environment. This novel technique combines user and topological features of the network enabling it to handle real-time streaming data. Our experiment of influenced rank-based sampling approach to influence maximization is compared to the greedy approach with and without sampling that exhibits an accuracy of 82%. Performance analysis in terms of running time is reduced from O(n ³) to O(k n). Where ‘k’ is the size of the sample dataset and ‘n’ is the number of user’s.     

Study on the machining of Al–SiC functionally graded metal matrix composite using die-sinking EDM

Functionally graded aluminum matrix composites (FGAMCs) are new materials with excellent capabilities for design and development of complex engineering works. In this work, FGAMCs are machined using electrical discharge machining (EDM) with the process input parameters such as pulse current, pulse on time, and zone position in brake disk. Design of experiments is used for the experimental planning with full factorial method. The selected input process parameters are optimized using gray relational analysis to minimize the electrode wear ratio, overcut, power consumption, and surface roughness. The influential studies of input process parameters on the output responses are also conducted. The optimal EDM parameter setting for achieving better output parameters is pulse current at 5 A, pulse on time at 50?µs and 45?mm zone position distance in the brake disk. The pulse current (39.40%) contributed the maximum in minimizing the output responses. Further, the surface morphology is also analyzed on the material to observe the crater formation and the erosion mechanism.     

Mechanical and aging properties of cross‐linked ethylene propylene diene rubber / styrene butadiene rubber blends

The mechanical properties and aging characteristics of blends of ethylene propylene diene monomer (EPDM) rubber and styrene butadiene rubber (SBR) were investigated with special reference to the effect of blend ratio and cross‐linking systems. Among the blends, the one with 80/20 EPDM/SBR has been found to exhibit the highest tensile, tear, and abrasion properties at ambient temperature. The observed changes in the mechanical properties of the blends have been correlated with the phase morphology, as attested by scanning electron micrographs (SEMs). The effects of three different cure systems, namely, sulfur (S), dicumyl peroxide (DCP), and a mixed system consisting of sulfur and peroxide (mixed) on the blend properties also were studied. The stress‐strain behavior, tensile strength, elongation at break, and tear strength of the blends were found to be better for the mixed system. The influence of fillers such as high‐abrasion furnace (HAF) black, general‐purpose furnace (GPF) black, silica, and clay on the mechanical properties of 90/10 EPDM/SBR blend was examined. The ozone and water aging studies also were conducted on the sulfur cured blends, to supplement the results from the mechanical properties investigation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2606–2621, 2004     

Fabrication and Experimental Investigation on Deformation Behaviour of AlSi10Mg Foam-Filled Mild Steel Tubes

Aluminium (Al) alloy foam is an engineering material which has emerged in the automobile sector where crash energy absorption, vibration and sound damping and weight reduction are required. Al-alloy foam is a lightweight material providing high strength and stiffness at relatively low density. The paper aims to study the innovative approach of manufacturing AlSi10Mg foam. The low-density and high-strength Al-alloy foam (AlSi10Mg) is fabricated using the melt route process resulting in a density of 0.70–0.90 g/cm3. After that, square mild steel thin-walled empty tubes and Al-alloy foam-filled mild steel tubes are tested to study enhanced energy absorption characteristics. The tests are carried out on universal testing machine with strain rate 10/s. Al-alloy foam, AlSi10Mg, is assessed macroscopically and microscopically using field emission scanning electron microscope and energy-dispersive X-ray analysis. The experimental results indicate that foam-filled tubes feature more energy absorption than empty tubes at strain rate 10/s.     

Evaluating the Available Regional Groundwater Resources Using the Distributed Hydrogeological Budget

In this study, several hydrogeological catchments of Central Italy have been characterized focusing the attention on the presence of areas in which, over the last two decades, the hydrological equilibrium between recharge and discharge (phenomena of marked reduction of spring discharge and progressive drawdown of groundwater levels) has been compromised by overexploitation of groundwater resources. A GIS system has been used in order to develop the study and the homogenous distribution of the hydrological knowledge and of the existing imbalances has been performed. Characterizing elements of the research are: a) the definition of the hydrogeological units; b) the hydrogeological survey of around a thousand water-points; c) the monthly analysis of climatic data of numerous survey stations; d) the census and the recording of water concessions; e) the evaluation of agriculture hydro-exigency derived from the analysis of the use of soil; f) the withdrawals defined by a statistic analysis of data. These elements have allowed to define the Distributed Hydrogeological Budget which is a useful instrument to evaluate critical areas.     

Effect of base dissipation on the granular flow down an inclined plane

The effect of base dissipation on the granular flow down an inclined plane is examined by altering the coefficient of restitution between the moving and base particles in discrete element (DE) simulations. The interaction laws between two moving particles are kept fixed, and the coefficient of restitution (damping constant in the DE simulations) between the base and moving particles are altered to reduce dissipation, and inject energy from the base. The energy injection does result in an increase in the strain rate by up to an order of magnitude, and the temperature by up to two orders of magnitude at the base. However, the volume fraction, strain rate and temperature profiles in the bulk (above about 15 particle diameters from the base) are altered very little by the energy injection at the base. We also examine the variation of h _stop , the minimum height at the cessation of flow, with energy injection from the base. It is found that at a fixed angle of inclination, h _stop decreases as the energy dissipation at the base decreases.     

Optimization of friction welding of tube-to-tube plate using an external tool by Taguchi method and genetic algorithm

Numerous advancements have been occurring in the field of materials processing. Friction welding is an important solid-state joining technique. In this research project, friction welding of tube-to-tube plate using an external tool (FWTPET) has been performed, and the process parameters have been prioritized using Taguchi??s L₂₇ orthogonal array. Genetic algorithm (GA) is used to optimize the welding process parameters. The practical significance of applying GA to FWTPET process has been validated by means of computing the deviation between predicted and experimentally obtained welding process parameters.