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Performance Evaluation of Triple band Microstrip Antenna using Hybrid SRRs on Fractal Ground Plane
Get PDFA single-band monopole antenna, transformed into a triple-band antenna for S-band and C-band applications is reported in this paper. This transformation is done with the help of two different hybrid SRR unit cells, which are embedded on the truncated ground plane of the antenna. These hybrid SRR unit cells are created by combining square split ring and circular split ring into two different configurations. Simulated results are in coherence with the measured results and analysis is provided to evaluate the efficacy of the design. This analysis can be used to estimate the usefulness of metamaterial unit cells in generating multiple frequency bands. The operating frequency bands measured are 2.72-2.83GHz, 3.54-4.35 GHz, and 4.72-5 GHz respectively. These bands are being used in the mid-band frequency range of 5G communication in many countries. The developed antenna is miniaturized to the size of 0.19λ0 ×0.25λ0 (λ0 is the free space wavelength at 2.72 GHz). Two objectives i.e., miniaturization and multi-banding are fulfilled in a single design. The introduction of different hybrid SRR unit cells at defective ground plane causes multi-banding and resonance of a unit cell at a lower frequency leads to an increase in the effective electrical length of the antenna without increasing its physical size. The metamaterial characteristic of the unit cells is also verified in the article
A Comprehensive Study of Fracture Toughness Determination from Conventional and Unconventional Methods
Get PDFIn this work fracture toughness is determined by the Toughness model; Critical Stress-Strain Model and Energy release rate model using unconventional test method referred to as Spherical Indentation test (SIT) to reduce the large and costly experimental set up as required in Conventional Fracture Toughness Test. The toughness model correlates the indentation energy to fracture with fracture toughness, Critical Stress-Strain Model assumes that the critical fracture toughness is equal to the critical plastic work done by the material when a crack tends to propagate and as per the Energy release rate model, indentation depth is given by loading-unloading cycles. The unloading slope which is elastic provides the reduced Young’s Modulus of the material from each unloading cycle which reflects the occurrence of damage in the material. For the determination of contact radius at different indentation points, finite element analysis is performed using the material data obtained from the tensile test result obtained from the previous work of the author. Conventional method using the Compact Tension (CT) and Three-Point Bending (TPB) specimens for the same material is used to determine the fracture toughness and compared with the above-described model
Fault Detection and Prognostic Health monitoring of Towed array sonars
Get PDFSonars are used to detect underwater targets and are especially important in maintaining naval superiority. Towed array sonars can operate at very low frequencies thus giving larger ranges and can be deployed to any desired depth of operation. Towed array sonars offer long range surveillance capability and is the sensor of choice for sustained surveillance operations. Reliable operation and maintenance of towed array sonars need effective methods of health monitoring and reliability prediction. For any prognostic health monitoring to be done we need to identify certain parameters which can be observed and will give system health status in the present condition. This paper proposes some metrics which are easily measurable in-situ and which offer insights into the health of the sonar system. These metrics give direct measureable impact for each of the failure modes and offer insights into the current health of an operational towed array sonar. Simulation results are shown to demonstrate the effectiveness of the proposed metrics and detailed trial data results from different towed array trials are analysed to validate them in operational scenarios
Construction and Analysis of Petri Net Model for Distributed Cyber Physical Systems
Get PDFA Distributed Cyber-Physical System (DCPS) composition poses challenges in determining its emergent behaviour. These challenges occur due to (1) the appearance of causal loops of information and energy flow through cyber and physical channels and (2) inherent non-determinism in the temporally ordered flow of events within independently evolving interacting processes of Constituent Systems (CSs). Hence, there is a need to construct a model of the envisaged schematic of DCPS composition for analysis and verification of its significant properties in the conceptual design stage of the system development life cycle.
This paper presents a procedure to construct DCPS composition models in Petri net formalism using distributed abstractions. The model for each CS is obtained from elementary constructs using compositional operators. The interaction among CSs occurs through channels obtained by connecting send and receive constructs of two CSs participating in an interaction. The internal processing within a CS characterizing its primary function is abstracted in a generic passthrough construct. Representing these constructs with compositional operators results in the complete DCPS model in Petri net formalism. A toolchain with Reference net workshop (Renew) as an integrated Petri net editing and analysis platform is configured to support DCPS modelling, simulation and analysis. The Renew tool functionality has been enhanced with a plugin designed and developed by authors to facilitate the drawing of the distributed composition model.
A low-level Petri net analysis (Lola) v2.0 plugin is employed to verify the Petri net and temporal properties of the modelled DCPS scenarios. The properties of the resultant model are verified using well-established algorithms to analyze Petri nets. Further, system properties specified using temporal logic can be verified using model-checking algorithms for Petri nets. A moderately complex scenario involving interactions among six CSs illustrates the presented approach
A Defected Ground Structure Based Compact Circular Patch Antenna Design for mm Wave Application
Get PDFThis paper presents a novel defected ground structure-based slotted circular patch antenna for mm-Wave application. A circular patch antenna with a compact size of 10 mm×8 mm×0.75 mm is fabricated in the lab. The designed antenna has a 2 GHz impedance bandwidth that covers the frequency range of 42GHz to 44GHz. It achieves a directional radiation pattern for millimeter-wave applications and has a maximum realized gain of 6 dBi at the operating frequency of 42.65 GHz. Defected ground structure (DGS) is loaded on the bottom of the dielectric substrate, which improves the gain and reduces the surface wave propagation. The proposed antenna has achieved circular polarization which makes it suitable for the mm-Wave application
Effect of Aviation Turbine Fuel Exposure on Interlaminar and Inplane Shear Properties of Glass Fiber Reinforced Epoxy Composite
Get PDFThis study investigated the effect of aviation turbine fuel exposure on interlaminar and in-plane shear properties of E-glass/epoxy composite. The two types of test specimens, namely bare and resin-coated specimens with varying thicknesses as per the ASTM standard, were made out of E-glass/epoxy composite to evaluate their interlaminar and in-plane shear properties. These all types of specimens were immersed inside the aviation turbine fuel for two months and then afterward their effect on the reduction of mechanical properties like interlaminar and in-plane shear tests properties were experimentally investigated. Test results show that ATF fuel exposure has reduced the interlaminar shear strength by 10.04 %, 7.83 %, and 6.01 % for bare, with 0.1 mm and 0.2 mm resin coating, respectively. Similarly, in-plane shear strength was reduced by 14.75 %, 11.22 %, and 7.52 % for bare, with 0.1 mm and 0.2 mm resin coating, respectively, and in-plane shear modulus was reduced by 10.87 %, 8.94 %, and 6.52 % for bare, with 0.1 mm and 0.2 mm resin coating conditions as compared to as-received (without ATF exposure) specimens.SEM micrographs and results too showed that properties were reduced and indicated that the glass/epoxycomposite was resistive to fuel ingression. It was observed that bare specimens exhibited a reduction in shearproperties due to ATF ingression to the polymeric network and induced internal stresses, which not only degraded the matrix and fiber-matrix adherence but created micro-cracks too in the resin at interfaces. Resin-coated specimens limit fuel ingression, which has led to a reduction in properties
Multi GNSS IRNSS L5 IRNSS S1 and GPS L1 Hybrid Simulator A Reconfigurable Low cost Solution for Research and Defence Applications
Get PDFSatellite-based positioning field of research is growing rapidly as there is an increase in demand for precise position requirements in various civil and commercial applications. There are many errors that affect the GNSS signals while propagation from satellite to receiver, which eventually induces errors in pseudo-range measurements. In order to assess the receiver characteristics for a specific error condition, the real-time signals may not be appropriate, and it is challenging to perform repeated experiments with the same error condition. The advantage of the GNSS simulator is that users can model the different scenarios for any given location on the globe, which are repeatable at any point of time. The conventional hardware simulators are expensive and have few limitations. In this paper, a reconfigurable hybrid simulator is proposed with some advantages over traditional hardware simulators, such as low cost, reconfigurability, and controllability over fundamental parameters. It can be able to record intermediate stage data, which makes it more suitable for the GNSS research field. The proposed multi-GNSS simulator considered implementing IRNSS-L5, IRNSS-S1, and GPS-L1 band signals. A general-purpose computer can perform the necessary calculations for signal generation. The hybrid simulator can be able to generate the digital I/Q data, which can be stored as I/Q data or can be connected to a general-purpose SDR (Software Defined Radio) for RF signal generation (bladeRF in this case). The I/Q data can be used with the software receiver to analyse the receiver performance concerning the specific error. The generated GNSS signals are validated with software and hardware receivers, and the obtained position is observed as expected. 
A Design of Experiments Approach Towards Desired Flow Distribution Through Manifolds in Electronics Cooling
Get PDFFor rack-mounted electronics, flow distribution is desired as per the heat load characteristics. In the literature, attainment of flow uniformity through manifolds is highlighted and widely discussed as it has more applications. To attain desired flow distribution, the complexity of the problem increases. In the present paper, the Design of Experiments (DOE) along with response surface optimization is used to arrive at desired flow, which includes uniform flow also. A three-dimension, 10-channel Z-type manifold is considered for the study. This model is taken from experimentally verified and published data for which desired flow patterns are achieved. Flow requirement through each channel is set as a parameter for optimization and by the defined sample set under DOE, uniform flow and pattern flow are achieved by introducing suitable orifices. Multi-Objective Genetic Algorithm (MOGA) is used for obtaining orifice diameters. A good agreement is observed between the attained flow patterns and desired patterns. This approach is simple and can be implemented for industrial applications