Search

Medical microwave imaging (MWI) research has gained more attention in recent decades, particularly with regard to the early detection of brain tumors. It offers numerous benefits over existing imaging technologies, including magnetic resonance imaging (MRI) and computed tomography (CT) scans. Antennas represent a key element of MWI systems, so optimizing their performance is critical. A new, simple patch antenna for MWI is presented in this article. The radiating patch has a circular slot and a tiny triangular cut at the top right corner, and it is designed and manufactured with a low-cost FR4-epoxy substrate with a loss tangent of 0.02 and a dielectric constant of 4.4. The overall dimensions are 0.28λ × 0.22λ × 0.005λ (where λ is the wavelength of a lower frequency of 1.22 GHz). A total impedance bandwidth (

The presented manuscript represents the superlative 1 × 2 MIMO antenna structure. Eight designs were analyzed by the patch elements' varying shapes and inserting the slits in the ground regions. The overall dimensions of the structure are 50 × 39 × 1.6 (mm3). The low-profile substrate FR4 is used for the fabrication, and the reflectance response of simulated and measured designs are compared. The insertion L shaped slits in the ground region and engraving of the patch elements provide the wider isolation bands. The minimum S11 is −67.53 dB, a broader bandwidth of 5.653 GHz, and a peak gain of 8.72 dBi. The design concert also analyzed ECC, CCL, TARC and DG. These results reflect the presented design's behaviour as per the standard requirements. The response of the design is also compared with the previously published works to identify the improvement. The work targets wireless applications like WLAN, weather broadcast, Satellite and Military.

A novel single material-based anti-resonant fiber is designed, investigated, and explored in this article with supports of up to 64 OAM modes over the 0.6 μm to 1.0 μm as operating wavelength. The other properties of the designed fiber including confinement loss (CL), OAM purity, effective refractive index differences (ERIDs), and dispersion variations provide the exceptional output. This fiber, the CL approximately varies between the 5.7031 × 10−5 dB/m to 9.2537 × 10−4 dB/m, the OAM purity is 97% to 99%, the ERIDs are higher than 10-4 for all the modes, and the least dispersion variations is −8.838 ps/km-nm for the EH1,1 mode. All the outstanding properties of the presented fiber are calculated using the FEM and the PML within the COMSOL Multiphysics simulator. Therefore, to the ideal of our knowledge, the proposed anti-resonant fiber is mostly applicable in the high-quality long-distance fiber communications system.

Abstract This article presents a novel metamaterial (MTM) with a mirror symmetric resonator that exhibits multiple resonances of transmission coefficient covering the L, S, C, and X bands. The resonating patch is constructed on a low-loss Rogers (RT5880) substrate with a dimension of 20 × 20 × 1.575 mm3. It consists of four equal quartiles with each quartile made with interconnected split-ring resonators; the quartiles are in mirror symmetry with each other. The proposed MTM exhibits resonances at 1.98 GHz, 3.67 GHz, 4.74 GHz, 8.38 GHz, and 10.8 GHz, and electromagnetic characterization is performed through studies of permittivity, permeability, refractive index, and impedances. Power analysis is also performed, and the effect of polarized incident waves is studied. An electromagnetic characterization study reveals that the proposed MTM shows negative permittivity with near-zero permeability and refractive index. It also reveals very little power consumption in the vicinity of the resonances. The dielectric-based frequency tuning is studied by using different dielectric layers over the patch that provides good frequency tuning; this method provides flexibility for adjusting the resonance frequencies in accordance with the application demand. The measured result of the proposed unit cell with the dielectric layer is extracted using a vector network analyzer, and the results exhibit good similarity with the simulated ones. The above-mentioned properties, along with a good effective medium ratio (EMR) of 7.57 indicate that this MTM is suitable for frequency selective applications in microwave devices such as antenna performance improvement and sensing.

Abstract In this paper, we present an analytical study for the investigation of the effects of the magnetoelectric elements of a reciprocal and nonreciprocal bianisotropic grounded substrate on the input impedance, resonant length of a dipole antenna as well as on the mutual coupling between two element printed dipole array in three configuration geometries: broadside, collinear and echelon printed on the same material. This study examines also the effect of the considered bianisotropic medium on the electric and magnetic field distributions that has been less addressed in the literature for antenna structures. Computations are based on the numerical resolution, using the spectral method of moments, of the integral equation developed through the mathematical derivation of the appropriate spectral Green’s functions of the studied dipole configuration. Original results, for chiral, achiral, Tellegen and general bi-anisotropic media cases, are obtained and discussed with the electric and magnetic field distributions for a better understanding and interpretation. These interesting results can serve as a stepping stone for further works to attract more attention to the reciprocal and non-reciprocal Tellgen media in-depth studies.

Abstract A couple ring enclosed circular geometric resonator (CRECGR) based dual-band polarization insensitive metamaterial (MM) with high effective medium ratio (EMR), and excellent absorptance is proposed in this study, which can be utilized as a sensor and absorber in the 5G sub-6 GHz frequency range. A circular geometry-based unique patch has been introduced in the proposed unit cell to achieve high polarization insensitive properties with excellent absorption for the 5G sub-6 GHz spectrum. The distinctive feature of this proposed CRECGR unit cell is its simple and unique structure with a high EMR of 11.13, polarization insensitive up to 180°, and epsilon negative (ENG) properties, including a negative refractive index and near-zero permeability for 5G sub-6 GHz applications. Furthermore, this designed unit cell yields excellent absorption properties with high quality factor. The designed MM unit cell is fabricated on low loss Rogers RT5880 printed media with an electrical dimension of 0.089λ × 0.089λ × 0.017λ. The performance of the designed CRECGR metamaterial is determined using Computer Simulation Technology (CST), Advanced Design Software (ADS), and measurements. The CRECGR unit cell offers dual resonances at 3.37 GHz and 5.8 GHz, covering the 5G sub-6 GHz band with ENG, near-zero permeability and negative index. The polarization insensitive properties of the unit cell were also investigated for maximum angle of incidence, which confirmed the identical response. The simulated outcome is verified by experiment with excellent accordance. Moreover, the unit cell performance with a complete backplane is explored, noting a maximum absorption of 99.9% for all normal and oblique incidence waves, suitable for sensing and antenna systems. In addition, the suggested unit cell sensing performance is evaluated using the permittivity-based sensing model. The proposed MM outperforms recent related studies in terms of polarization insensitivity up to 180°, high insensitive absorptivity, high EMR, and sensing applications. These features prove that the proposed CRECGR metamaterial is perfect for 5G Applications.

A compact, dual polarized, multiband four-port flexible Multiple Input Multiple Output (MIMO) antennae with the connected ground and high isolation is designed with computation and experimental measurement studies. All four monopole radiators are embedded decagon-shaped flexible FR-4 substrate with an outer radius of 10 mm in order to accomplish circularly polarized (CP) radiations, bandwidth enhancement, and compact size of only $45\times 38\times 0.2$ mm3 ( $0.375\lambda \times 0.316\lambda \times 0.0016\lambda $ , at lowest resonating frequency 2.5GHz). The interconnected ground structure is loaded with an Interlaced Lozenge Structure (ILS) to suppress the surface wave radiations resulting in low mutual coupling between the radiators. The proposed MIMO antenna demonstrates measured 10-dB impedance bandwidths of 9.63% (2.37–2.61 GHz), 28.79% (3.30–4.41 GHz), and 16.91% (4.98–5.90 GHz) in the LTE 38/40, Sub-6 GHz 5G NR n77/n78, WLAN and Wi-Fi bands, respectively. Furthermore, broad 3-dB Axial Ratio Bandwidth (ARBW) of 28.79% (3.30–4.41 GHz) with gain greater than 4 dBi and efficiency above 80% are achieved. Finally, the bending analysis of the proposed flexible MIMO antenna along the X- and Y- directions shows good performances in terms of scattering parameters, 3 dB ARBW, and MIMO diversity parameters.

The revolutionary advancement in the capabilities of hardware tools, software packages, and communication techniques gave rise to the Internet of Things-supported drone networks (IoD), thereby enabling smooth communication among devices and applications, and impacting drastically the various aspects of human lives. However, with the increasing sophistication in the infrastructure of IoD, new security threats arise that require novel algorithms and schemes as solutions. To this end, several schemes have recently been proposed. However, some schemes cannot perfectly address the novel security aspects associated with IoD environments, while others cannot provide computational or communication efficiency. Motivated by these research gaps in the existing literature, we leverage elliptic curve cryptography along with symmetric encryption and hash function, and propose a novel and robust user authentication mechanism for the IoD, called RUAM-IoD. We validate the security of the established SK formally through the random oracle model. Similarly, we provide informal security analysis to demonstrate the security capabilities of RUAM-IoD against different pernicious security attacks. Likewise, we establish a comparison of the RUAM-IoD with several state-of-the-art authentication schemes to show that RUAM-IoD acquires less storage, communication, and computational cost.

In this work, a compact, light-weight, low-cost, and easy install and incorporate mmwave printed square loop antenna with a perturbed ground plane is proposed. The antenna is fabricated on an ultra-thin 0.254 mm Rogers RT/Duroid 5880 substrate. The antenna resonates between 26 GHz and 40 GHz providing the broad bandwidth of 13 GHz ( $\sim 47$ %). First, a single element consisting of three rectangular square loops and a transmission line with total dimensions of 9 mm $\times11$ mm ( $0.84\,\,\lambda _{0} \times 1\,\,\lambda _{0}$ ) is designed. The loop elements are arranged on top of each other and with the further insertion of square slot in ground plane, wideband resonance response has been achieved. The antenna demonstrates gain of more than 3.3 dBi, and radiation and a total efficiency of 98% at 28 GHz. The proposed design enables spatial diversity and minimize the effects of interference between adjacent channels by providing dual-beam within desired frequency band. In addition, a linear array ( $18.5\times22.5$ mm2) of four elements with a traditional feeding network is also designed, simulated, and measured. The gain of the array is 10.1 dBi, while the radiation and the total efficiency is more than 92 % at 28 GHz. A brief literature review and comparison of this work with other published works is also presented. To validate the proposed design and concept, a prototype is fabricated for both, a single element, and an array. It is found that the measured results and the computed results are in good agreement. Therefore, we believe that this system will find its applications within modern mmwave communication cellular devices.

Background: Estimated seroprevalence of Coronavirus Infectious Disease 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is a critical evidence for a better evaluation of the virus spread and monitoring the progress of COVID-19 pandemic in a population. In the Kingdom of Saudi Arabia (KSA), SARS-CoV-2 seroprevalence has been reported in specific regions, but an extensive nationwide study has not been reported. Here, we report a nationwide study to determine the prevalence of SARS-CoV-2 in the population of KSA during the pandemic, using serum samples from healthy blood donors, non-COVID patients and healthcare workers (HCWs) in six different regions of the kingdom, with addition samples from COVID-19 patients. Methods: A total of 11,703 serum samples were collected from different regions of the KSA including; 5395 samples from residual healthy blood donors (D); 5877 samples from non-COVID patients collected through residual sera at clinical biochemistry labs from non-COVID patients (P); and 400 samples from consented HCWs. To determine the seroprevalence of SARS-CoV-2, all serum samples, in addition to positive control sera from RT-PCR confirmed COVID-19 patients, were subjected to in-house ELISA with a sample pooling strategy, which was further validated by testing individual samples that make up some of the pools, with a statistical estimation method to report seroprevalence estimates. Results: Overall (combining D and P groups) seroprevalence estimate was around 11% in Saudi Arabia; and was 5.1% (Riyadh), 1.5% (Jazan), 18.4% (Qassim), 20.8% (Hail), 14.7% (ER; Alahsa), and 18.8% in Makkah. Makkah samples were only D group and had a rate of 24.4% and 12.8% in the cities of Makkah and Jeddah, respectively. The seroprevalence in Saudi Arabia across the sampled areas would be 12 times the reported COVID-19 infection rate. Among HCWs, 7.5% (4.95–10.16 CI 95%) had reactive antibodies to SARS-CoV-2 without reporting any previously confirmed infection. This was higher in HCWs with hypertension. The study also presents the demographics and prevalence of co-morbidities in HCWs and subset of non-COVID-19 population. Interpretation: Our study estimates the overall national serological prevalence of COVID-19 in Saudi Arabia to be 11%, with an apparent disparity between regions. This indicates the prevalence of asymptomatic or mild unreported COVID-19 cases.

This study presents a thin triple-band cross-polarization-conversion metasurface (CPCM) comprising square split-ring resonators (SSRR), metallic cross elements where four metal strips are housed inside the SSRR. The SSRR resonator and back-layer are designed with copper on FR-4 substrate, where substrate sandwiches the resonator and the back-layer. The SSRR and metallic cross elements are developed on a dielectric substrate and the backside block by a copper layer. CST MWS 2018 is used to design and perform analysis of the metasurface. The electrical dimension of the CPCM structure is 0.128 λ × 0.128 λ × 0.044 λ at a lower frequency of 5.49 GHz. The CPCM achieved a bandwidth of 5.35 to 5.69 GHz, 7.60 to 8.76 GHz, and 12.41 to 13.96 GHz covering the S, C, and X frequencies band. Moreover, the simulated result of the CPCM is verified through experimental development. An electrically thin substrate makes the proposed structure identical in polarization responses (up to 750) at normal and oblique incidents above the mentioned frequency band. The surface current distribution is analyzed to comprehend the structural mechanism behind the polarization conversion of the unit cell.

In multi-interconnected power system, keeping the changes in frequencies and tie-line powers at their specified values is vital process especially during operation under load disturbance. This target can be achieved by installing load frequency control (LFC), the main object of LFC is damping the deviations of frequencies and tie-line powers to zero. This paper proposes a new approach incorporated recent optimizer of movable damped wave algorithm (MDVA) to identify the unknown parameters of LFC represented by fractional-order proportional integral derivative (FOPID). FOPID controller is selected as it has better and robust performance, the controller is installed in multi-interconnected system with multi-sources considering renewable energy-based plants. Minimizing the integral time absolute error (ITAE) of the change in frequencies and tie-line powers is the main target. Two power systems are considered in this work, the first one comprises photovoltaic (PV) and thermal generating units while the second system includes four plants of PV, wind turbine (WT), and two thermal based plants. Moreover, the generation rate constraints and governor dead-band of thermal plant are considered. Different load disturbances in both studied systems are investigated and the obtained results via the proposed DMVA are compared to coronavirus herd immunity optimizer (CHIO), antlion optimizer (ALO), sooty tern optimization algorithm (STOA), manta ray foraging optimizer (MRFO), and sin-cos algorithm (SCA). Regarding the two-interconnected system, the proposed DMVA succeeded in achieving the best ITAE of 6.3911 during 10% disturbance applied on PV plant. Regarding to the multi-interconnected system, the best (minimum) fitness function is 0.015029 achieved via the proposed DMVA at 1% load disturbance on the first area. The results confirmed the robustness of the proposed algorithm in solving the LFC parameter estimation.

With the advancement of cloud computing technologies, there is an ever-increasing demand for the maximum utilization of cloud resources. It increases the computing power consumption of the cloud’s systems. Consolidation of cloud’s Virtual Machines (VMs) provides a pragmatic approach to reduce the energy consumption of cloud Data Centers (DC). Effective VM consolidation and VM migration without breaching Service Level Agreement (SLA) can be attained by taking proactive decisions based on cloud’s future workload prediction. Effective task scheduling, another major issue of cloud computing also relies on accurate forecasting of resource usage. Cloud workload traces exhibit both periodic and non-periodic patterns with the sudden peak of load. As a result, it is very challenging for the prediction models to precisely forecast future workload. This prompted us to propose a hybrid Recurrent Neural Network (RNN) based prediction model named BHyPreC. BHyPreC architecture includes Bidirectional Long Short-Term Memory (Bi-LSTM) on top of the stacked Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU). Here, BHyPreC is used to predict future CPU usage workload of cloud’s VM. Our proposed model enhances the non-linear data analysis capability of Bi-LSTM, LSTM, and GRU models separately and demonstrates better accuracy compared to other statistical models. The effect of variation of historical window size and training-testing data size on these models is observed. The experimental result shows that our model gives higher accuracy and performs better in comparison to Autoregressive Integrated Moving Average (ARIMA), LSTM, GRU, and Bi-LSTM model for both short-term ahead and long-term ahead prediction.

Improving the operation of wind energy generation system is a big challenge especially when it operates under unstable weather conditions. Therefore, installing a tracker for monitoring the maximum power expected to be generated from the wind energy system is essential, this controller is known as maximum power point tracker (MPPT). Hill climbing based approaches were applied for simulating the tracker, however they have limitations in tracking speed and efficiency. This paper proposes a recent efficient approach of Archimedes optimization algorithm (AOA) for simulating MPPT installed with the wind energy generation system. The constructed system composes wind turbine (WT) connected to a permanent magnet synchronous generator (PMSG), the AC output power from the generator is converted to DC via 3-phase rectifier, the DC voltage is the input of boost converter which is controlled via its MOSFET duty cycle. The designing process is presented as an optimization problem considering the electrical output power from the system as the target. The proposed AOA tunes the converter duty cycle to maximize the output power. Three scenarios are followed in this work which are fixed wind speed, variable wind speed, and real wind speed recorded at four sites in Saudi Arabia (Sakaka, Riyadh, Jeddah, and Jizan). The obtained results via the proposed approach are compared with the results obtained via cuckoo search (CS), grasshopper optimization algorithm (GOA), and electric charged particle optimization (ECPO). The results confirmed the robustness of the proposed AOA-MPPT in achieving the best performance of wind energy generation system.

Recently, IoT (Internet of Things) has been an attractive area of research to develop smart home, smart city environment. IoT sensors generate data stream continuously and majority of the IoT based applications are highly delay sensitive. The initially used cloud based IoT services suffers from higher delay and lack of efficient resources utilization. Fog computing is introduced to improve these problems by bringing cloud services near to edge in small scale and distributed nature. This work considers an integrated fog-cloud environment to minimize resource cost and reduce delay to support real-time applications at a lower operational cost. We first present a cooperative three-layer fog-cloud computing environment, and propose a novel optimization model in this environment. This model has a composite objective function to minimize the bandwidth cost and provide load balancing. We consider balancing load in both links' bandwidth and servers' CPU processing capacity level. Simulation results show that our framework can minimize the bandwidth cost and balance the load by utilizing the cooperative environment effectively. We assign weight factors to each objective of the composite objective function to set the level of priority. When minimizing bandwidth cost gets higher priority, at first, the demand generated from the traffic generator sensors continues to be satisfied by the regional capacity of layer-1 fog. If the demand of a region goes beyond the capacity of that region, remaining demand is served by other regions layer-1 fog, then by layer-2 fog, and finally by the cloud. However, when load balancing is the priority, the demand is distributed among these resources to reduce delay. Link level load balancing can reduce the queueing delay of links while server level load balancing can decrease processing delay of servers in an overloaded situation. We further analyzed how the unit bandwidth cost, the average and maximum link utilization, the servers' resources utilization, and the average number of servers used vary with different levels of priority on different objectives. As a result, our optimization formulation allows tradeoff analysis in the cooperative three-layer fog-cloud computing environment.

In this work, we present a highly compact multi-branch structure multi-band antenna with a grounded coplanar waveguide (GCPW)-fed structure printed on 26 × 13 × 1.6 mm3 sized FR-4 substrate having dielectric constant εr of 4.3 and loss tangent δ of 0.02. In the proposed antenna, five branches are extended from the main radiator to provide multi-band behavior. Two branches are introduced at the upper end of the main radiator, effectively covering the lower bands, while the other three branches are introduced near the center of the main radiator to extend operation to higher bands. The designed antenna covers five different bands: 2.4 GHz, 4.5 GHz, 5.5 GHz, 6.5 GHz, and 7.8 GHz, with respective gain values of 1.34, 1.60, 1.83, 1.80, and 3.50 dBi and respective radiation efficiency values of 90, 88, 84, 75, and 89%. The antenna shows a good impedance bandwidth, ranging from 170 MHz to 3070 MHz. The proposed antenna is simulated in CST Microwave Studio, while its performance is experimentally validated by the fabrication and testing process. The antenna has potential applications for IoT, sub-6 GHz 5G and WLAN (both enablers for IoT), C-band, and X-band services.

The future of wireless technology is moving towards millimeter wave bands due to a surge in the use of wearable gadgets in current wireless bands. The 60 GHz band is unlicensed around the world and has gathered high research interest. At this band, the atmospheric absorption is very high, which results in short-range communication. High gain antennas are a core requirement for operating at 60 GHz. In this paper, we are proposing three different arrays consisting of 2, 3, and 4 elements of a novel patch design. The radiating patch consists of a semicircular disc fed by a microstrip feed line. The ground plane has been etched into a novel shape. The radiator and the ground plane are attached to a 1.5 mm thick FR-4 substrate which has a relative permittivity of 4.3. The radiating elements are connected linearly to form arrays. In free space, all three arrays achieved a very wide bandwidth of more than 20 GHz, and the maximum gain varied from 3.44 dBi to 6.2 dBi. The arrays were also simulated under human body conditions by modelling a three-layer phantom. At different distances from the phantom, the maximum gain increased by more than 1 dBi. The antenna shows 4.855 dBi, 5.032 dBi, and 6.66 dBi gain for 2 array, 3 array, and 4 array, respectively, when simulated on the three-layer human model phantom. The antenna has a very good VSWR value for all three array structures. On the human body phantom, the proposed antenna design in this research shows 1.214, 1.120, and 1.023 VSWR values for 2 array, 3 array, and 4 array, respectively. The efficiencies were highly affected, as expected from patch antennas. The simulation results are obtained from CST Microwave Studio.

A miniaturized millimeter wave (mmWave) antenna for wireless body area networks is proposed in this paper. The antenna is found to be operational in the V-band, around the 60 GHz frequency range, with high efficiency of up to 99.98% in free space simulations. A multilayer, thin substrate was implemented in the design to enhance radiation efficiency and gain. The antenna seems to be most suitable for small electronic devices and wireless body area network (WBAN) applications because of its low profile and lighter weight concept. To enhance its performance, several arrays of different orders were created. The Parallel-Fed and Tapered Feed Line methods were followed to design the planar arrays with 1 × 2, 1 × 4, and 2 × 2 elements in the primary design. Free space results were compared, and a 2 × 2 element array was found to be the most balanced according to the simulations. To justify the eligibility of these designs for WBAN applications, a virtual human body model was created within the 3D computer-simulated environment and the simulations were repeated, where four equal-spaced distances were taken into account to identify the antenna and its array behavior more accurately. Simulations returned optimistic results for the 2 × 2 element planar array arrangement in almost all parameters, even when placed close to the human body at any distance greater than 2 mm.

The fluctuated nature represents the main obstacle for increasing the penetration level of photovoltaic (PV) generators in utility microgrids. The energy storage systems (ESSs) represent the main solutions to get over these fluctuations. Among various ESSs, the superconducting magnetic energy storage (SMES) systems have proven themselves as an effective solution. The SMES control systems in the literature result in a shortened lifetime, degraded thermal behavior, and high AC losses in the SMES. Thence, reliable operation of SMES systems and microgrids has been given wide concerns due to the large fluctuations in microgrids with high levels of PV penetrations. This paper presents a SMES-based fuzzy logic approach for improving the reliability of SMES and utility microgrids with high PV penetration levels. The proposed SMES controller employs the state of charge (SOC) of SMES as an input. This, in turn, can effectively extend the lifetime of SMES due to eliminating the overcharge and deep discharge operating states. Moreover, the proposed system controls smoothly the SMES current using the fuzzy rules' system. The superiority and effectiveness of the proposed SMES controller are verified using simulation-based case studies of utility grids with high PV penetration levels. The obtained results show the effective smoothing of fluctuated power and constant bus voltages in the studied microgrid under the proposed controller. In addition, the proposed SMES controller provides superior performance regarding the lifetime and reliability of the SMES systems and microgrid components.

The main objective of this work is to develop a variety of hybrid high-density polyethylene (HDPE) micro- and nanocomposites and to investigate their thermal, mechanical, and morphological characteristics as a function of number of fillers and their contents percentage. In this study, 21 formulations of the composites were prepared using fillers with different sizes including micro fillers such as talc, calcium carbonate (CaCO3), as well as nano-filler (fumed silica (FS)) though the melt blending technique. The morphological, mechanical, and thermal properties of the composite samples were evaluated. The morphological study revealed negligible filler agglomerates, good matrix–filler interfacial bonding in case of combined both CaCO3 and FS into the composites. Sequentially, improvements in tensile, flexural and Izod impact strengths as a function of fillers loading in the HDPE matrix have been reported. The maximum enhancement (%) of tensile, flexural and impact strengths were 127%, 86% and 16.6%, respectively, for composites containing 25% CaCO3 and 1% FS without any inclusion of talc filler; this indicates that the types/nature, size, quantity and dispersion status of fillers are playing a major role in the mechanical properties of the prepared composites more than the number of the used fillers.

This study provides an eight-component multiple-input multiple-output (MIMO) antenna architecture for fifth-generation (5G) mobile communication systems. The single antenna element is comprised of an L-shaped radiating component, an L-shaped parasitic element, and a ground plane with a rectangular slot. The main element with a slot-loaded ground plane helps to draw current from a coaxial feed from the other side of the board, while the parasitic element helps to elongate the current path and improve the impedance of the system. This enables the system to radiate at two different frequency ranges: 3.34–3.7 GHz and 4.67–5.08 GHz, with 360 MHz and 410 MHz bandwidths, respectively. For MIMO configuration, the radiating elements are designed on either side of a 0.8 mm thick FR-4 substrate, allowing space to accommodate a battery, radio frequency (RF) systems and subsystems, and camera and sensor modules. The corner and the middle elements are arranged in such a manner so that they can provide spatial and pattern diversity. Furthermore, at least 12 dB of isolation is established between any two radiating elements. Various MIMO performance parameters were evaluated, e.g., mean effective gain (MEG), channel capacity (CC), envelope correlation coefficient (ECC), realized gain, far-field characteristics, and efficiency. Single- and double-hand mode evaluations were performed to further demonstrate the capability of the proposed MIMO antenna. A prototype of the proposed MIMO antenna was manufactured and assessed to verify the simulated data. The measured and simulated results were found to be in good agreement. On the basis of its performance characteristics, the designed MIMO system could be used in 5G communication systems.

We have presented the borophene based refractive index sensor for the infrared frequency spectrum of 188 to 250 THz (1.2–1.6 µm) range. The proposed structure was formed by using the Silver-borophene-silica-Ag layered structure. The behaviour of the different analyte (with a different refractive index) material is numerically calculated by placing it on the top of the structure. The behaviour of the structure is identified in terms of absorption, reflectance, physical parameter variation, and oblique angle incident conditions. The presented results provide the basic idea of selecting optimized structure dimensions to get the specific resonating response. This sensor offers the Figure of Merit (FOM) of 444 RIU−1 with high sensitivity of 660 THz/RIU (4471 nm/RIU). The refractive index sensor also provides wide-angle stability for (0° to 80°) for the wide frequency range (239 to 245 THz and 207 to 209 THz). This sensor is developed on the silver metal layer (not required to separate borophene from its origin metal deposition process) and easily fabricated using standard boron fabrication and layered deposition techniques. The results of the proposed structure make it possible to design a basic biosensor structure. This device is also applicable for various THz and biomedical applications.

In this paper, we address the performance optimization of Holmium doped fiber amplifier (HDFA) for optical communications in 2–2.15 μm wavelength range based on a single in-band forward pump source. The performance of the HDFA is analyzed with the help of theoretical simulations by considering an optimized length of Holmium doped fiber (HDF), doping concentration of Ho3+, and pump power. The impact of signal wavelength and power on gain, amplified spontaneous emission (ASE) noise, and noise figure (NF) of the amplifier is investigated. Furthermore, we investigate the variations in the gain of the amplifier, its output power, and NF by varying the power and wavelength of the pump source. After optimizing the parameters of the amplifier, the peak gain observed is around 56.5 dB, the 3 dB saturated output power obtained is 33.3 dBm, and the output power is 3 W at signal wavelength of 2.0321 μm for HDF having an optimized length of 12 m and pump power of 3.5 W. Minimum NF of around 8.2 dB is observed at 2.0321 μm for signal power of −5 dBm. The impact of ion-ion interaction on the performance of HDFA is also investigated. A reduction of 24.2 dB and 0.051 W is observed in peak gain and output power of HDFA, respectively by considering the ion-ion interaction.

In this work, graphite nanoplatelets (GNP) were incorporated into poly (ethylene terephthalate) (PET) matrix to prepare PET-GNP nanocomposites using a melt compounding followed by compression moulding and then quenching process. Both static and dynamic mechanical properties of these quenched materials were characterized as a function of GNP contents using dynamic mechanical thermal analysis (DMTA) and tensile machine, respectively. The results demonstrated that the addition of GNP improved the stiffness of PET significantly. Additionally, the maximum increase in the storage modulus of 72% at 6 wt.% GNP. The incorporation of GNP beyond 6 wt.% into PET decreases the storage moduli, but they remain higher than pure PET. The observed reduction could be due to agglomeration, resulting in poorer dispersion and distribution of higher levels of GNP into the PET matrix. In contrast to the results for moduli, tensile strength and elongations at break reduce with increasing the GNP content. For example, tensile strength reduced from ∼46 MPa (neat PET) to ∼39 MPa (−15%) for the nanocomposites containing 2 wt.% GNP. This reduction is accompanied by a decline in elongation at break from ∼6.3 (neat PET) to ∼3.4 (−46%) for the same nanocomposites. Such reductions are followed by a gradual decrease in upon further addition of GNP. These reductions indicate that increasing GNP loadings, results in brittleness in nanocomposites. In addition, it was found that quenched PET and composite samples were not fully crystallized after processing and therefore (cold) crystallized during the first heating cycle DMTA, as indicated by a rise in storage moduli above the glass transition temperature during the DMTA first heat. Furthermore, mathematical models based on non-linear theories are developed to capture the experimental data. For this, a set of mechanical stress-strain data is used for model parameters’ identification. Another set of data is used for the model validation that demonstrates good agreements with the experimental study.

The design of a 4 × 4 MIMO antenna for UWB communication systems is presented in this study. The single antenna element is comprised of a fractal circular ring structure backed by a modified partial ground plane having dimensions of 30 × 30 mm2. The single antenna element has a wide impedance bandwidth of 9.33 GHz and operates from 2.67 GHz to 12 GHz. Furthermore, the gain of a single antenna element increases as the frequency increases, with a peak realized gain and antenna efficiency of 5 dBi and >75%, respectively. For MIMO applications, a 4 × 4 array is designed and analyzed. The antenna elements are positioned in a plus-shaped configuration to provide pattern as well as polarization diversity. It is worth mentioning that good isolation characteristics are achieved without the utilization of any isolation enhancement network. The proposed MIMO antenna was fabricated and tested, and the results show that it provides UWB response from 2.77 GHz to over 12 GHz. The isolation between the antenna elements is more than 15 dB. Based on performance attributes, it can be said that the proposed design is suitable for UWB MIMO applications.

Carbon felt (CF) is an inexpensive carbon-based material that is highly conductive and features extraordinary inherent surface area. Using such a metal-free, low-cost material for energy storage applications can benefit their practical implementation; however, only limited success has been achieved using metal-free CF for supercapacitor electrodes. This work thoroughly studies a cost-effective and simple method for activating metal-free self-supported carbon felt. As-received CF samples were first chemically modified with an acidic mixture, then put through a time optimization two-step electrochemical treatment in inorganic salts. The initial oxidative exfoliation process enhances the fiber’s surface area and ultimately introduced oxygen functional groups to the surface, whereas the subsequent reduction process substantially improved the conductivity. We achieved a 205-fold enhancement of capacitance over the as-received CF, with a maximum specific capacitance of 205 Fg−1, while using a charging current density of 23 mAg−1. Additionally, we obtained a remarkable capacitance retention of 78% upon increasing the charging current from 0.4 to 1 Ag−1. Finally, the cyclic stability reached 87% capacitance retention after 2500 cycles. These results demonstrate the potential utility of electrochemically activated CF electrodes in supercapacitor devices.

In this paper, we propose and simulate a novel Schottky barrier MOSFET (SB-MOSFET) with improved performance in comparison to the conventional SB-MOSFET. The proposed device employs charge plasma/electrostatic doping-based dopant segregation layers (DSLs) by using metal extensions (Hafnium) at the source and drain top and bottom edges. The metal hafnium induces charge plasma and hence realizes DSLs adjacent to source and drain regions. These charge plasma DSLs reduce the tunneling width and hence enhances the performance of the proposed device. The proposed electrostatically doped DSL-based SB-MOSFET has all the advantages of the conventional SB-MOSFET and it outperforms the state of the art doped DSL-based MOSFET. A two-dimensional calibrated simulation study has shown that the ON current (ION), ION/IOFF ratio, subthreshold-swing and cutoff frequency (fT) of the proposed device have been increased by ~420 times, ~1000 times, 14.5%, and 290 times in comparison to conventional SB-MOSFET, respectively. The transient analyses have shown that a reduction by 16 times in ON delay and 6 times in OFF delay in the proposed device-based inverter in comparison to the conventional SB-MOSFET-based inverter.

In this paper, an electrostatically-doped hetero-barrier tunnel-field-effect-transistor (EDHet-TFET) based on stepped broken-gap (type-III) is simulated, investigated, and compared with the conventionally-doped stepped broken-gap hetero-barrier TFET (Het-TFET). ED-Het-TFET employs GaSb source region, In0.85Ga0.15As-based channel-drain regions, and In0.2Ga0.8As as tunnel barrier, with a uniform p-type doping, done initially throughout the device layer. Two metal gates (c-gate and n-gate) with proper work-functions are used to invert the doping in In0.85Ga0.15As layer to realize n-type channel-drain regions. A 2-D calibrated simulations have shown improvement in the OFF-state current and the ION/IOFF ratio. OFF-state current in the ED-Het-TFET has improved by more than an order of magnitude. Furthermore, transient analysis reveals that ED-Het-TFET performs on par with its conventional counterpart in terms of rise propagation delay during circuit level implementation. A high ION/IOFF ratio of ~108 (average subthreshold slope of ~11 mV/decade) is obtained at 20-nm gate length for a very low operating voltage of 0.1 V, enabling it to be a device for future ultra-low power applications.

Recently, the triple-lobe behavior is found in the I-V characteristics of some memristive devices generating another non-zero pinchoff point. In this paper, a flux-controlled memristive model is developed to generate the triple-lobe behavior (double pinchoff points) based on a fractional second-order model. The conditions for observing triple lobes are derived besides the coordinates of the pinchoff points. Different scenarios have been considered by changing the model parameters and fractional order. Furthermore, the minimum and maximum achievable conductances are analyzed and mathematically derived. In addition, a floating emulation circuit is introduced and analyzed, which is able to generate the triple-lobe behavior and mimic the dynamics of the proposed fractional modeling equation, showing good matching with the mathematical model. Finally, the obtained triple-lobe behaviors have been verified using experiments with fractional orders: 0.3 and 0.4.

Carbon fiber-reinforced polymers are considered a promising composite for many industrial applications including in the automation, renewable energy, and aerospace industries. They exhibit exceptional properties such as a high strength-to-weight ratio and high wear resistance and stiffness, which give them an advantage over other conventional materials such as metals. Various polymers can be used as matrices such as thermosetting, thermoplastic, and elastomers polymers. This comprehensive review focuses on carbon fiber-reinforced thermoplastic polymers due to the advantages of thermoplastic compared to thermosetting and elastomer polymers. These advantages include recyclability, ease of processability, flexibility, and shorter production time. The related properties such as strength, modulus, thermal conductivity, and stability, as well as electrical conductivity, are discussed in depth. Additionally, the modification techniques of the surface of carbon fiber, including the chemical and physical methods, are thoroughly explored. Overall, this review represents and summarizes the future prospective and research developments carried out on carbon fiber-reinforced thermoplastic polymers.

Emerging memristor technology is recently drawing widespread attention due to its potential for diverse applications. Due to the lack of real solid-state memristive devices, there have been many initiatives to develop memristor emulators to study their behavior and applications. One of the most widely used ideal memristor models developed by the HP Lab does not fit the anticipated nonlinear behaviors of a real memristor. In this paper, we propose the concept and the design of a practical memristor emulator, which can be used to mimic the behavior of the well-known current controlled memristor models like-Simmons tunneling barrier model and the ThrEshold adaptive memristor model. Our proposed emulator model mimics the behavior of the electrical nonlinearity of the fabricated memristor. Prior emulators can only emulate the linear electrical behavior. In addition to the mathematical modeling and analysis of the proposed emulator, we provide SPICE simulation and experimental results. Furthermore, the proposed emulator has been used to verify some applications like Wien Oscillators. Finally, a brief comparison with the previously published emulators is presented to highlight the advantages of the proposed design.