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Bonding of the heterogeneous layers of polymers as a trilayered (or multilayered) transparent metamaterial absorber (MA) is challenging, since the hydrophobic nature of interfacial surfaces does not allow direct bonding. Apart from the mechanical challenges to bond, microwave and optical functionalities of the chosen material need to be studied quantitatively for an optimal choice. Therefore, simulations are performed to study the effect of dielectric constant and thickness of adhesive on the microwave characteristics of polyethylene terephthalate (PET)–polydimethylsiloxane (PDMS)-based microwave MA (MMA). Composites of polyvinyl butyral (PVB) and 3-aminopropyltriethoxy silane (APTES) that address the need for strongly adhesive yet transparent in optical regime and non-interacting in the microwave regime have been developed. Lap-shear tests with plasma-treated PET–PDMS adherends demonstrated to have lap-shear adhesion strengths greater than 0.21 MPa. The optical transmittance of electromagnetic (EM) waves through MA after being adhered with glue is 74.9%. A numerical analysis shows that the proposed microwave absorber absorbs more than 90% of EM waves within the range of 7.97–20.72 GHz after an additional layer of optimal adhesive, which is validated through experiments conducted in anechoic measurements. [ABSTRACT FROM AUTHOR]

Wide-area protection scheme (WAPS) provides system-wide protection by detecting and mitigating small and large-scale disturbances that are difficult to resolve using local protection schemes. As this protection scheme is evolving from a substation-based distributed remedial action scheme (DRAS) to the control center-based centralized RAS (CRAS), it presents severe challenges to their cybersecurity because of its heavy reliance on an insecure grid communication, and its compromise would lead to system failure. This article presents an architecture and methodology for developing a cyber-physical anomaly detection system (CPADS) that utilizes synchrophasor measurements and properties of network packets to detect data integrity and communication failure attacks on measurement and control signals in CRAS. The proposed machine leaning-based methodology applies a rules-based approach to select relevant input features, utilizes variational mode decomposition (VMD) and decision tree (DT) algorithms to develop multiple classification models, and performs final event identification using a rules-based decision logic. We have evaluated the proposed methodology of CPADS using the IEEE 39 bus system for several performance measures (accuracy, recall, precision, and F-measure) in a cyber-physical testbed environment. Our experimental results reveal that the proposed algorithm (VMD-DT) of CPADS outperforms the existing machine learning classifiers during noisy and noise-free measurements while incurring an acceptable processing overhead. [ABSTRACT FROM AUTHOR]

A planar array antenna consisting of 6 units of rectangular dielectric resonators fed by means of novel microstrip lines through aperture coupling is presented. The structure is designed in such a way that two different modes are excited in the array elements that yield a high bandwidth and gain. Based on the experimental results, the antenna is seen to have an impedance bandwidth of 6.98% centered at 24.09 GHz. Furthermore, the antenna gain is seen to lie between 7 and 9.5 dBi within its entire bandwidth, whereas the cross-polarization discrimination is better than 45 dB in the boresight. These features, along with its low-profile structure, make this antenna a suitable candidate for usage in short-range radars, wireless sensor nodes, and other sensors for the 24 GHz Industrial, Scientific, and Medical (ISM) band. [ABSTRACT FROM AUTHOR]

A streaming IoT environment like health monitoring system is characterized by continuous generation of data at a high rate. This stream of data can neither be stored on the nodes nor transmitted to the sink due to resource constraints. This demands continuous perusal of the data stream at nodes for in-situ event detection. In this WSN scenario, existing schemes that rely on inference based on stored data on the nodes or the sink become in-efficacious. In this paper, temporal and spatial correlation in such data streams is exploited to effectively reduce the use of these resources in decision making process. We propose an All In One Stream Processing (AIOSP) scheme which employs sampling using temporal correlation, load shedding using spatial correlation and approximation using drift and diffusion for efficient decision making process in data streaming environment where a large amount of data is continually generated by the sensor nodes. The performance of proposed scheme is evaluated through simulations over varied sample size and is found to ensure 85% to 95% accuracy with small sample size. [ABSTRACT FROM AUTHOR]

In this paper, a new data acquisition scheme is proposed based on compressed sensing (CS) with on-demand explosion of random walks (RWs) for improving the lifespan of wireless sensor networks (WSNs) without compromising its detection capability. From the perspective of sensor networks, the lifetime largely relies upon communication efficiency and load distribution on the nodes. CS with RW is proven to be an efficient mechanism for data gathering for sparse recovery, but requires minimum $O(s \times \log(n/s))$ measurements. To lift this assumption, we have exploited the rate of change of data, which works in a similar fashion as sparsity does. Moreover, it also yields a way for opportunistic initiation of RWs which ensures explicit event detection in the target region. Therefore, an on-demand explosion-based compressed sensing (ODECS) is proposed to reduce the required measurements dynamically and limits the required measurements to a constant in case of no events. Simulation and experimental analysis show that ODECS outperforms the existing schemes in terms of data transmission, energy consumption, and lifetime by reducing communication which depends upon the probability of occurrence of event in each data acquisition round. [ABSTRACT FROM AUTHOR]

This paper focuses on the design with experimental verification of a circular polarization (CP) and pattern reconfigurable triangular patch array simultaneously operating at various tunable frequencies. The resonant frequency of the antenna can be altered from 1.97 to 2.54 GHz (25.3% tunable bandwidth) by varying the capacitance values from 4.27 to 1.15 pF of the six varactors fixed between the annular slots on the three triangular patches. A wideband phase shifting network with switching capability is also designed which facilitates the antenna to operate it in both types of CP and pattern reconfigurable modes at each frequency. The antenna is tested in receiving mode and it shows a maximum realized gain of 3.1 dBc when operated in any of the CP mode and 1.45 dB for pattern reconfigurability mode. It has a very wideband axial ratio (AR) value (<3 dB) at each reconfigured frequency and also covers the entire frequency agility bandwidth. Investigation confirms that the antenna produces circularly polarized radiation pattern with minimum AR beamwidth of 24° at all frequency bands for both types of CP radiation. It is also observed that the antenna pattern can be rotated at 120° angle in the complete azimuth plane with a wide 3 dB beamwidth of ±45° at its operating frequencies. The multifaceted reconfiguring ability of the antenna enables it to serve many futuristic communication system requirements such as supporting multiple radios and maintaining signal quality in diverse climatic conditions. [ABSTRACT FROM AUTHOR]