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20 pages, 10035 KiB

Open AccessArticle

Reconfigurable Metasurface: Enabling Tunable Reflection in 6G Wireless Communications

by Monisha Selvaraj, Ramya Vijay, Rajesh Anbazhagan and Amirtharajan Rengarajan

Sensors 2023, 23(22), 9166; https://doi.org/10.3390/s23229166 - 14 Nov 2023

Cited by 10 | Viewed by 4748

With the continuous advancement of technology, there is an increasing need for innovative solutions that can handle complex applications such as haptic communications, Internet of Things for smart cities, automation, and manufacturing. One technology that has received much attention is the phase reconfigurable metasurface for reconfigurable intelligent surfaces (RISs). The RIS demands low-power consumption, simple configuration, angular stability, and polarization insensitivity. The use of phase reconfigurable metasurfaces provides benefits such as low cost, low power consumption, and improved communication coverage and quality. This article introduces a reconfigurable combined-loop metasurface that can effectively manipulate phase reflection. This is achieved by incorporating four PIN diodes between two meta-atoms of a 2 × 2 periodic array within a single-layer metallic structure. By controlling the state of the PIN diodes, which can be switched into 16 different states, the metasurface can achieve various phase reflections. The proposed structure has validated a 32× 32 metasurface through numerical simulations and experiments that exhibit promising results, demonstrating its potential for use in 6G applications. Full article

(This article belongs to the Special Issue Antennas and Propagation for 6G Communications and Wireless Sensor Networks)

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23 pages, 2843 KiB

Open AccessArticle

Neural Attractor-Based Adaptive Key Generator with DNA-Coded Security and Privacy Framework for Multimedia Data in Cloud Environments

by Hemalatha Mahalingam, Padmapriya Velupillai Meikandan, Karuppuswamy Thenmozhi, Kawthar Mostafa Moria, Chandrasekaran Lakshmi, Nithya Chidambaram and Rengarajan Amirtharajan

Mathematics 2023, 11(8), 1769; https://doi.org/10.3390/math11081769 - 7 Apr 2023

Cited by 35 | Viewed by 2779

Abstract

Cloud services offer doctors and data scientists access to medical data from multiple locations using different devices (laptops, desktops, tablets, smartphones, etc.). Therefore, cyber threats to medical data at rest, in transit and when used by applications need to be pinpointed and prevented preemptively through a host of proven cryptographical solutions. The presented work integrates adaptive key generation, neural-based confusion and non-XOR, namely DNA diffusion, which offers a more extensive and unique key, adaptive confusion and unpredictable diffusion algorithm. Only authenticated users can store this encrypted image in cloud storage. The proposed security framework uses logistics, tent maps and adaptive key generation modules. The adaptive key is generated using a multilayer and nonlinear neural network from every input plain image. The Hopfield neural network (HNN) is a recurrent temporal network that updates learning with every plain image. We have taken Amazon Web Services (AWS) and Simple Storage Service (S3) to store encrypted images. Using benchmark evolution metrics, the ability of image encryption is validated against brute force and statistical attacks, and encryption quality analysis is also made. Thus, it is proved that the proposed scheme is well suited for hosting cloud storage for secure images. Full article

(This article belongs to the Section E1: Mathematics and Computer Science)

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18 pages, 2707 KiB

Open AccessArticle

Non-Identical Inverter Rings as an Entropy Source: NIST-90B-Verified TRNG Architecture on FPGAs for IoT Device Integrity

by Hemalatha Mahalingam, Sivaraman Rethinam, Siva Janakiraman and Amirtharajan Rengarajan

Mathematics 2023, 11(4), 1049; https://doi.org/10.3390/math11041049 - 19 Feb 2023

Cited by 9 | Viewed by 2837

Abstract

True random key generator (TRNG) architectures play a notable role in strengthening information security infrastructure. The development of new entropy sources based on reconfigurable hardware is always in demand, especially for the integrity of devices in IoT applications. TRNGs can be adopted for generating unique device IDs that form the data network in the IoT. A ring oscillator (RO) is an efficient entropy source which can be implemented on FPGAs or realised as ASIC hardware. This work proposes a non-identical RO array as an entropy source. The TRNG architecture, based on an increasing odd number of inverters per ring, was extensively studied. The various statistical and hardware analyses provided encouraging results for this reliable entropy unit. The suggested device-independent non-identical RO structure was implemented on five different types of FPGA hardware belonging to the Xilinx and Intel families, consuming 13 registers and nearly 15 combinational functions. This TRNG achieved a throughput of 3.5 Mbps. While the emergence of the Gaussian response evaluated true randomness, the NIST 800-90B and NIST 800-22 tests yielded good results in terms of the justification of randomness evolving from the proposed TRNG architecture. Full article

(This article belongs to the Special Issue Recent Advances in Security, Privacy, and Applied Cryptography)

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23 pages, 10047 KiB

Open AccessArticle

Dual-Domain Image Encryption in Unsecure Medium—A Secure Communication Perspective

by Hemalatha Mahalingam, Thanikaiselvan Veeramalai, Anirudh Rajiv Menon, Subashanthini S. and Rengarajan Amirtharajan

Mathematics 2023, 11(2), 457; https://doi.org/10.3390/math11020457 - 15 Jan 2023

Cited by 49 | Viewed by 3385

Abstract

With the growing demand for digitalization, multimedia data transmission through wireless networks has become more prominent. These multimedia data include text, images, audio, and video. Therefore, a secure method is needed to modify them so that such images, even if intercepted, will not be interpreted accurately. Such encryption is proposed with a two-layer image encryption scheme involving bit-level encryption in the time-frequency domain. The top layer consists of a bit of plane slicing the image, and each plane is then scrambled using a chaotic map and encrypted with a key generated from the same chaotic map. Next, image segmentation, followed by a Lifting Wavelet Transform, is used to scramble and encrypt each segment’s low-frequency components. Then, a chaotic hybrid map is used to scramble and encrypt the final layer. Multiple analyses were performed on the algorithm, and this proposed work achieved a maximum entropy of 7.99 and near zero correlation, evidencing the resistance towards statistical attacks. Further, the keyspace of the cryptosystem is greater than 2¹²⁸, which can effectively resist a brute force attack. In addition, this algorithm requires only 2.1743 s to perform the encryption of a 256 × 256 sized 8-bit image on a host system with a Windows 10 operating system of 64-bit Intel(R) Core(TM) i5-7200U CPU at 2.5 GHz with 8 GB RAM. Full article

(This article belongs to the Special Issue Recent Advances in Security, Privacy, and Applied Cryptography)

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18 pages, 2966 KiB

Open AccessArticle

Predictive Controller Design for a Cement Ball Mill Grinding Process under Larger Heterogeneities in Clinker Using State-Space Models

by Sivanandam Venkatesh, Kannan Ramkumar and Rengarajan Amirtharajan

Designs 2020, 4(3), 36; https://doi.org/10.3390/designs4030036 - 15 Sep 2020

Cited by 3 | Viewed by 4942

Abstract

Chemical process industries are running under severe constraints, and it is essential to maintain the end-product quality under disturbances. Maintaining the product quality in the cement grinding process in the presence of clinker heterogeneity is a challenging task. The model predictive controller (MPC) poses a viable solution to handle the variability. This paper addresses the design of predictive controller for the cement grinding process using the state-space model and the implementation of this industrially prevalent predictive controller in a real-time cement plant simulator. The real-time simulator provides a realistic environment for testing the controllers. Both the designed state-space predictive controller (SSMPC) in this work and the generalised predictive controller (GPC) are tested in an industrially recognized real-time simulator ECS/CEMulator available at FLSmidthPvt. Ltd., Chennai, by introducing a grindability factor from 33 to 27 (the lower the grindability factor, the harder the clinker) to the clinkers. Both the predictive controllers can maintain product quality for the hardest clinkers, whereas the existing controller maintains the product quality only up to the grindability factor of 30. Full article

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20 pages, 11715 KiB

Open AccessFeature PaperArticle

Design, Simulation and Hardware Implementation of Shunt Hybrid Compensator Using Synchronous Rotating Reference Frame (SRRF)-Based Control Technique

by R. Balasubramanian, K. Parkavikathirvelu, R. Sankaran and Rengarajan Amirtharajan

Electronics 2019, 8(1), 42; https://doi.org/10.3390/electronics8010042 - 1 Jan 2019

Cited by 12 | Viewed by 5754

Abstract

This paper deals with the design, simulation, and implementation of shunt hybrid compensator to maintain the power quality in three-phase distribution networks feeding different types balanced and unbalanced nonlinear loads. The configuration of the compensator consists of a selective harmonic elimination passive filter, a series-connected conventional six-pulse IGBT inverter, acting as the active filter terminated with a DC link capacitor. The theory and modelling of the compensator based on current harmonic components at the load end and their decomposition in d-q axis frame of reference are utilized in the reference current generation algorithm. Accordingly, the source current waveform is made to follow the reference current waveform using a high-frequency, carrier-based controller. Further, this inner current control loop is supported by a slower outer voltage control loop for sustaining desirable DC link voltage. Performance of the compensator is evaluated through MATLAB simulation covering different types of loads and reduction of harmonic currents and THD at the supply side along with excellent regulation of DC link voltage are confirmed. The performance of a hybrid compensator designed and fabricated using the above principles is evaluated and corroborated with the simulation results. Full article

(This article belongs to the Special Issue Applications of Power Electronics)

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