In this article, unmanned aerial vehicles (UAVs) are expected to play a key role in improving the safety and reliability of transportation systems, particularly where data traffic is nonhomogeneous ...and nonstationary. However, heterogeneous data sharing raises plenty of security and privacy concerns, which may keep UAVs out of future intelligent transportation systems (ITS). Some of the well-known security and privacy issues in the UAV-enabled ITS ecosystem include tracking UAVs and vehicle locations, unauthorized access to data, and message modification. Therefore, in this article, we contribute to the sum of knowledge by combining the hyperelliptic curve cryptography (HECC) techniques, digital signature, and hash function to present a privacy-preserving authentication scheme. The security features of the proposed scheme are assessed using formal security analysis methods, i.e., real-or- random (ROR) oracle model. To examine the performance of the proposed scheme, a comparison with other existing schemes has been carried out. The results reveal that the proposed scheme outperforms its counterpart schemes in terms of computation and communication costs.
A series containing five samples of nickel substituted copper spinel ferrite (NixCu1-xFe2O4) nanoparticles with five different nickel concentrations varying as x = 0.00, 0.03, 0.06, 0.09, 0.12, ...fabricated with the aid of sol-gel auto-combustion technique. Through X-ray diffraction analysis, the structural properties of the compound were determined, which revealed that the prepared nanomaterials possess a spinel nature which was confirmed due to the existence of a secondary phase. The crystallite size was ascertained by applying the Scherrer formula, which was brought up in the range of 8–11 nm. The experimental parameters such as magnetic stirring speed, the molarity of reactants, synthesis temperature, the quantity of citric acid, and annealing were kept controlled. The substitution of nickel in copper spinel ferrite made a significant effect on the structural variables such as crystallite size stacking fault, lattice strain, micro-strain, dislocation density, bulk density, Impedance Analyzer (LCR meter) was used to get the dielectric properties in the frequency extended from 1 Hz to 20 MHz. From the obtained results it was depicted that the synthesized nanomaterials might be able to give response to the electromagnetic radiations, hence these can be usefully applied in microwave devices. Tangent loss and dielectric constant are varied due to Ni2+ content. Impedance loss shows the grain boundaries are dominant as a function of Ni2+ content. Inverse relation of AC frequency with the dielectric constant exposed the existence of Maxwell–Wagner type interfacial polarization. The various dielectric plots give awareness about the conducting grains and resistive grain boundaries that play a vital role in understanding the dielectric relaxation in the material. The ac conductivity is also determined due to Ni2+ content. From the observed electrical parameters, it can be propounded that the prepared nanocrystalline particles hold semiconducting nature and can be employed as a dielectric in low-frequency devices, and might be utilized as a conductor in high-frequency devices.
•Nickel substituted copper spinel ferrites nanoparticles were successfully synthesized by sol–gel auto-combustion method.•The effect of Nickel doping in copper ferrites, on structural and electrical properties were investigated.•The structural parameters such as lattice constant, crystallite size, lattice strain, micro-strain were determined.•Frequency dependent dielectric, impedance and electric modulus properties are investigated in microwave region.•Ac conductivity in microwave region is also investigated.
The study aimed to explore the association between hip flexors tightness and lumbar instability in adults. The study design was correlational and 64 subjects of both genders (male and female) with ...age range from 20 to 50 years were selected with a history of low back pain (LBP) with or without referred pain. Two examiners were assigned for application of the Modified Thomas Test (MTT) for hip flexors tightness and lumbar prone Instability Test (LPIT) and Prone Lumbar Extension Tests (PLET) for lumbar instabilities. The numeric pain rating scale (NPRS) was used for pain assessment. The two examiners were not aware of each other’s findings. The lambda value 0.238 which shows there is a weak association between MTT and PLET. The Cramer’s V value 0.179 also shows a weak relationship between MTT and LPIT. This study observed that there is a weak association between tight hip flexors and lumbar instability.
The precise selection of suppliers to fulfill production requirements is a fundamental component of all manufacturing and process industries. Due to the increasing consumption levels, green supplier ...selection (GSS) has been one of the most important issues for environmental preservation and sustainable growth. The present work aims to develop a technique based on Fermatean hesitant fuzzy rough set (FHFRS), a robust fusion of Fermatean fuzzy set, hesitant fuzzy set, and rough set for GSS in the process industry. On the basis of the operational rules of FHFRS, a list of innovative Fermatean hesitant fuzzy rough weighted averaging operators has been established. Further, several intriguing features of the proposed operators are highlighted. To cope with the ambiguity and incompleteness of real-world decision-making (DM) challenges, a DM algorithm has been developed. To illustrate the applicability of the methodology, a numerical example for the chemical processing industry is presented to determine the optimum supplier. The empirical findings suggest that the model has a significant application of scalability for GSS in the process industry. Finally, the improved FHFR-VIKOR and TOPSIS approaches are employed to validate the proposed technique. The results demonstrate that the suggested DM approach is practicable, accessible, and beneficial for addressing uncertainty in DM problems.
Cerium (Ce3+) substituted Co0·7Zn0.3CexFe2-xO4 spinel ferrites were prepared by using the sol-gel route. To characterize the structural, surface morphology, vibrational, dielectric, and magnetic ...properties, X-ray diffraction (XRD), Fourier transformation infrared (FTIR), UV spectroscopy, LCR meter, Energy dispersive X-ray analysis (EDX) and vibrating sample magnetometer (VSM) were used. The XRD patterns showed nano-crystallite single-phase structure formation. Powder XRD, SEM, and EDX analyses verified the pure phase development of Ce3+ doped Co0·7Zn0.3CexFe2-xO4 NPs. TEM analysis revealed random-shaped, sharp-edged nanoparticles with a facetted morphology. The appearance of discrete diffraction spots on the SAED pattern suggested the development of extremely crystallite nanoparticles. The dielectric loss was found to be decreasing with increasing frequency application for high-frequency devices. Microwave frequency decrease with the increase of Ce3+ ions into spinel ferrites. With a low value of Hc and a high value of Ms, shows an application for the transformer core.
•Sol-gel route was used to prepare Ba3Co2-xMgxFe24O41 hexaferrites.•The occupancy of Mg2+ ions at the octahedral site was altered by Fe3+ ions.•The dielectric permittivity was decreased by ...incorporating of Magnesium.•Cole – Cole plots revealed a single semi-circle.•Magnetic investigations unfolded ferrimagnetic nature of all samples.
The Ba3Co2-xMgxFe24O41 hexaferrites were prepared by the sol–gel combustion route. The materials were annealed at 1350 °C and displayed the single-phase characteristics. X-ray density (Dx) decreases owing to increasing Mg-concentration. Crystallite size was calculated with the help of Debye Scherrer's formula and found within the 17–18 nm range. Fourier transform infrared spectroscopy was used to determine the specific absorption peaks of hexagonal ferrites. It was executed in the region of 420–700 cm−1—the occupancy of Mg2+ ions at the octahedral site at delayed alternation of Fe3+ ions. As a result, the dielectric permittivity decreased. The grain boundary contribution was clearly seen in synthesized ferrites' cole plots. The cole – cole plots show a single semi-circle which reveals that grain boundaries play a significant role in the conduction process. Magnetic measurement indicated the ferrimagnetic behavior of all samples.
Dysprosium (Dy
3+
) substituted cobalt-zinc spinel ferrites were synthesized having composition (Co
0.7
Zn
0.3
Dy
3+
xFe
2−x
O
4
) with the concentration ranges from (0.00, 0.5, 0.10, 0.15, and 0.20) ...by using the Sol–Gel synthesis. XRD analysis confirmed the FCC spinel structure of the prepared samples. Lattice constant and X-ray density were calculated in variance ranging from 8.40–8.46 Å and 5.28–5.77 g/cm
3
, respectively. Fourier Transformation Infrared Spectroscopy (FTIR) were used to measure the frequency band in between 411–562 cm
−1
for the tetra and octahedral positions. Scanning electron microscopy was used to study the surface morphology of the prepared samples. The field emission transmission electron microscopy (FE-TEM) was used for the confirmation of particle size. The calculated value of crystalline size was 13 nm, while particle size was the best on 23 nm. It was observed that, on applied field frequency the dielectric parameters exhibits decreasing trend. Magnetic properties were examined by Vibrating Sample Magnetometer (VSM) method and found out saturation magnetization (63.99 emu/g), anisotropy (K) (5366.82 J/m
3
) and magnetic moment (2.77) were in decreasing while retentivity (2.38 emu/g), squareness ratio (0.07) and coercivity H
c
(133.71Oe) were in increasing trend respectively. These features of Dy
3+
substituted Co–Zn spinel ferrites recommend their better use in sensors and high frequency devices.
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•Single phase spinel structure was revealed with crystallite size of 10.94–25.44 nm.•The microstructural investigations disclosed average particle size of ≈ 26.87 nm.•Ferrimagnetic ...nature of Ni-Co-Pr nanoparticles was revealed in magnetic studies.•ε′ and ε″ followed decreasing tendency with increase in applied field frequency.•These ferrites have potential uses in high density memory and high frequency devices.
Praseodymium (Pr3+) substituted Nickel-Cobalt ferrites with composition Ni0.3Co0.7PrxFe2-xO4 and concentration (x = 0.00, 0.05, 0.10, 0.15, 0.20) were synthesized via sol–gel approach. The crystallite size was lying in 10.94–25.44 nm range having decreasing tendency and lattice constant was varying between 8.30 and 8.39 Å. Two absorption bands were seen in infrared spectroscopy around 550 cm−1 and 430 cm−1, representing spinel structure. Morphological analysis revealed particle size of ≈ 26.87 nm. Magnetic investigations disclosed decreasing trend in saturation magnetization (Ms), retentivity (Mr) and coercivity (Hc) and were determined in 19.77–50.75 emu/g, 0.77–19.48 emu/g, and 87.23–943.27 Oe range, respectively. Dielectric parameters showed decreasing trend with increase in frequency. Dielectric constant and loss were decreased from 3.64 to 2.59 and 0.502–0.420 for Pr3+ concentration × = 0.00–0.20 at 0.5 GHz, respectively. AC conductivity showed elevation with increasing applied frequency. These reported magneto-dielectric features suggest possible use of material in high density memory and high frequency devices.
When the Wireless Sensor Network (WSN) is combined with the Internet of Things (IoT), it can be employed in a wide range of applications, such as agriculture, industry 4.0, health care, smart homes, ...among others. Accessing the big data generated by these applications in Cloud Servers (CSs), requires higher levels of authenticity and confidentiality during communication conducted through the Internet. Signcryption is one of the most promising approaches nowadays for overcoming such obstacles, due to its combined nature, i.e., signature and encryption. A number of researchers have developed schemes to address issues related to access control in the IoT literature, however, the majority of these schemes are based on homogeneous nature. This will be neither adequate nor practical for heterogeneous IoT environments. In addition, these schemes are based on bilinear pairing and elliptic curve cryptography, which further requires additional processing time and more communication overheads that is inappropriate for real-time communication. Consequently, this paper aims to solve the above-discussed issues, we proposed an access control scheme for IoT environments using heterogeneous signcryption scheme with the efficiency and security hardiness of hyperelliptic curve. Besides the security services such as replay attack prevention, confidentiality, integrity, unforgeability, non-repudiations, and forward secrecy, the proposed scheme has very low computational and communication costs, when it is compared to existing schemes. This is primarily because of hyperelliptic curve lighter nature of key and other parameters. The AVISPA tool is used to simulate the security requirements of our proposed scheme and the results were under two backbends (Constraint Logic-based Attack Searcher (CL-b-AtSER) and On-the-Fly Model Checker (ON-t-FL-MCR)) proved to be SAFE when the presented scheme is coded in HLPSL language. This scheme was proven to be capable of preventing a variety of attacks, including confidentiality, integrity, unforgeability, non-repudiation, forward secrecy, and replay attacks.
High-performance multicrystalline silicon (HPMC-Si) wafers were produced using upgraded metallurgical-grade silicon (UMG-Si) materials in the seed-assisted growth system at the industrial scale. The ...HPMC-Si wafers yielded low dislocation density and fine and uniform grain size. We observed that fine grain size suppressed the segregation effect of metal impurities. The effective segregation coefficients of Fe, Al, and total metal impurities approximated 0.265, 0.492, and 0.386, respectively. The concentration of impurities within 10–90% of the solidified fraction in the ingot was relatively uniform based on the improved crystal structure control. The heterogeneous nucleation mechanism of concave and planocera nucleation was discussed intensively. HPMC-Si wafers were obtained under the crystal structure control coupled with behavior regulation of impurity segregation in the seed-assisted growth system. The average conversion efficiency of Al-BSF processed solar cells reached 18.65%.
•HPMC-Si wafers were produced using UMG-Si materials with a seed-assisted method.•Discarded silicon wafers were selected as nucleation layers for seed-assisted growth system.•Efficiency of solar cells prepared by HPMC-Si wafers reached 18.65%.•Fine grain size suppressed the segregation effect of metal impurities.•The mechanism of heterogeneous nucleation was proposed and discussed intensively.
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