Computers and Devices for Communication

The proposed architecture implements IEEE 754 floating point pipelined multiplier merge single and double precision using Karatsuba. This paper is presented in order to reduce power and area expenditures to fast the process of the adder and reduce delay. To achieve, the design Verilog language is used and targeted on Xilinx Virtex-5 (XC5VLX155FF1760-3) and Cadence on TSMC-180 nm CMOS technology. The architecture reduces the processing block as it uses exception block as replacement, whereas in the Karatsuba multiplier, the adders are replaced with different adder to obtain reduce results of area and power. Karatsuba is used in placing the mantissa in the multiplier, and in the Karatsuba architecture, the previous design is replaced in order to reduce the numbers of operations in block processing; here, left shifting is in the 27 * 27 bits multiplier. By implementation of various adders, better results are obtained when compared to the previous work in terms of DSP 6 (4%), LUTs 1367 (1%), frequency 168.741 MHz, dynamic power 123.61 mW.

The testing and detection of faults in digital circuits has become extremely relevant to both industry as well as academia in recent years. Effective and cheap testing procedures and algorithms help to decrease the manufacturing costs for digital circuits to a significant extent. The present work discusses state-of-the-art digital fault detection techniques. Specific emphasis is laid on a relatively new class of techniques that employ machine learning techniques to classify and detect faults in digital circuits and systems, especially focusing on Bayesian networks and support vector machines (SVMs). The work is concluded by the proposal of a machine learning-based fault probability estimation technique and brief deliberations on the enhancements that can be made in future to the technique.

Rain attenuation is an important factor affecting wireless communication systems throughout the world. Rain attenuation and rain rate data are collected using multichannel radiometer and laser precipitation monitor at a tropical location. The dataset obtained is used to initially propose an empirical model for prediction of rain attenuation from rain rate data. An alternative model using linear spline regression-based machine learning is also used to predict rain attenuation. The machine learning-based model is found to be more accurate by an appreciable degree compared to the empirical model proposed in the previous instance.

One of the most promising applications of Internet of things (IoT) is to interconnect the available medical resources and offer smart, reliable, and effective healthcare service, to meet the demands of growing population and increasing medical expenses. In remote places where people do not have easy and fast access to healthcare facilities, IoT enabled system can easily cater to such issues. IoT-based remote healthcare service allows patients to take quality medical advice from any corner of the world. Electrocardiogram (ECG) is a common diagnostic tool used to detect heart problems. This paper presents an IoT-based real-time ECG monitoring system design for remote patients. AD8232 sensor is used to acquire ECG signal which is interfaced with notch filter, for removal of power-line frequencies and is then sent to Arduino Uno for further processing. This signal is further processed in MATLAB platform, for removal of baseline wander and then uploaded to the cloud, which is then accessed via an external web page.

Detection of coronal holes (CHs) in the solar disk is one of the important tasks in the domain of astronomy. In this work, a technique based on image segmentation has been used for the detection of the CHs in the solar disk image. Here in the work, the task of image segmentation has been carried out using fast fuzzy c-means algorithm (FFCM). In the work, modified classical fuzzy c-means clustering technique has been induced for the segmentation of solar-disk image and detection of CHs in the image. For the purpose, the histogram of image intensities has been taken into account in order to faster the clustering and segmentation process. The output of the proposed algorithm has been compared visually with other existing technique of CHs detection in order to validate the capability of the proposed technique.

The early detection and proper treatment of brain tumor are essential to prevent permanent damage of brain. Present study proposes an automatic and effective approach to detect brain lesion in early stage that refers to the process of automated contrast enhancement of magnetic resonance (MR) brain images by incorporating simple power law transformation followed by segmentation and identification of the region of interest (ROI) using fuzzy c-means clustering technique and then finally classification of ROI into benignancy/malignancy classes by capturing six significant morphological feature selection. Finally, benignancy/malignancy of masses is examined and assessed by using well-known receiver operating characteristic method of ANN classifier based on significant feature selection. The result of the proposed method is enterprising with very low computational time and accuracy of 90.8%.

In the present study, we have merged functional and anatomical information to study the prognosis of Alzheimer’s disease (AD). To restore all possible directional information of the source images, the shift-invariant non-subsampled shearlet transform (NSST)-based decomposition technique is employed. Then, principle component analysis (PCA) and position-based maximum energy selection scheme are applied for lower subband and higher subbands, respectively, to combine multimodal information in a single frame. Finally, fused images have been generated by inverse NSST. Efficiency of the proposed fusion scheme has been reflected in the experimental results.

An approach of performance analysis-based system modeling of artificial lower limb has a very significant role in the control action applications. The control system stability checking is performed in this research paper to identify the system efficiency and design requirements. The efforts have been made to initiate different approaches to achieve the best effective model using the mathematical model. The state-space analysis has been incorporated to analyze different control parameter performances such as controllability, observability and stability testing of the artificial limb model. The closed loop representation by the simulation approach using Jury stability and Lyapunov stability analysis has been involved. The control action analysis shows the relevancy and the precision of the proposed mathematical model.

Satellite DNA is a very small DNA sequence which repeats in tandem (array) inside noncoding DNA. We have identified two different Satellite DNA (SatDNA) structures in Transposon of different species and detected its Frequency of Occurrence (FO) using ‘IdenSatDNA’ algorithm. We have found that SatDNA structures are present in both AT-rich and GC-rich sequences, and most of the samples we have tested contain at least one SatDNA structure. We have also pointed out that Frequency of Occurrence (FO) of both DNA structures is very high in at least one NCBI reference sequence for every species. This may play a significant role to unfold the hidden riddle of human evolution.

The p53, “Guardian of Genome,” is a special type of protein acting as a tumor suppressor and transcription factor for Mdm2. The interaction between p53-Mdm2 protein pathway forms a negative feedback network where p53 activates Mdm2 and Mdm2 deactivates p53 through ubiquitination. The interaction between p53-Mdm2 plays an important role in cancer progression. In this paper, ordinary differential equation (ODE) is derived based on mass action kinetics of the chemical reactions of the protein pathway under normal condition of DNA. A system model of p53-Mdm2 pathway is derived for normal cells using Michealis-Menten kinetics. The system model describing the dynamics of the pathway is simulated in MATLAB R2014a environment.

The notion of incremental learning is to train an ANN algorithm in stages, as and when newer training data arrives. Incremental learning is becoming widespread in recent times with the advent of deep learning. Noise in the training data reduces the accuracy of the algorithm. In this paper, we make an empirical study of the effect of noise in the training phase. We numerically show that the accuracy of the algorithm is dependent more on the location of the error than the percentage of error. Using perceptron, feedforward neural network and radial basis function neural network, we show that for the same percentage of error, the accuracy of the algorithm significantly varies with the location of error. Furthermore, our results show that the dependence of the accuracy with the location of error is independent of the algorithm. However, the slope of the degradation curve decreases with more sophisticated algorithms.

In this article, the conductivity, dielectric, activation and optical behaviour of Y1-xNdxCrO3 nanoparticles have been explained. The characterization is followed by XRD and TEM and measurements. The resistivity behaviour shows that the samples are semiconducting in nature and the resistivity decreases with the increase of doping concentration. From the resistivity analysis, it has been observed that the value of the activation energy decreases with the increase of the doping concentration. The band gap of the samples decreases with increasing doping concentration. The frequency variation of dielectric permittivity for different temperatures is measured for the samples. The variation of dielectric loss with temperature for different frequencies is also estimated.

In this work, we ‘derived’ the famous Pythagorean theorem from the measurements of the sides of right-angled triangles with machine learning. In classical Euclidean geometry, this result is proved with rigorous geometrical argument, but we have followed a data-driven approach and got the same result without entering a single step in the domain of geometry. We used symbolic regression with genetic programming to reach the model. As far as our knowledge goes, this result is a novel one and may open up a new avenue of applying machine learning tool in geometry. We have used Python programming language 3.7 and libraries such as DEAP (v1.2) and pygraphviz. The whole project can be found on https://github.com/snigdhasjg/Pythagorean-Triplate.git.

The essence of this paper is to design a mechanism for detecting emotional state of person using different bio-potential signals like electroencephalogram (EEG) signals of frontal lobe, pulse rate and SpO2. We record EEG signals of Fp1, Fp2, F3 and F4 electrodes, pulse rate and SpO2 of thirty subjects and extract twenty-two features from the recorded bio-potential signals. We design a k-nearest neighbor (KNN) classifier model for predicting the emotional state of a person. The designed KNN classifier model is trained with the extracted feature values of the thirty subjects. We again record the same bio-potential signals of ten new subjects and extract features. These extracted feature values are used for validating the performance of the trained KNN classifier model. The obtained overall efficiency of our designed emotion detection mechanism is 95.4%.

Severe thunderstorm is the convective weather feature, originated from cumulonimbus cloud. It has devastating effect in the society. Accurate prediction with enough lead time is needed to make the people alert from such destructive event. In this study, analysis of grayscale cloud imageries and histograms has been used to nowcast severe thunderstorm.

This paper presents the design of a triple-band antenna for mobile handset covering frequency bands of GSM 900, GSM 1800, and ISM 2450. The proposed antenna includes two open rings attached with the transmission line and a slotted partial ground plane for the three operating bands. This antenna is printed on a less expensive FR4 substrate, occupying very small volume of 26 × 27 × 1.6 mm3. The ground plane of the proposed structure is extended to meet the dimension of a standard smart mobile phone to verify its applicability as a mobile handset antenna. The results of the proposed triple-band antenna and extended ground plane antenna for the mobile handset are in good agreement. The details of design consideration, working principle and the parametric analysis are discussed.

Orthogonal frequency division multiplexing (OFDM) has proved itself as a proficient multicarrier transmission technique to be successfully utilized in 5G and next-generation wireless communication. However, conventional OFDM suffers from the limitation of high peak-to-average-power ratio (PAPR). Subcarrier index modulation (SIM) has already been established as one of the efficient techniques to mitigate this high PAPR problem. In this work, we have proposed a novel modulation algorithm named as reduced subcarrier index modulation-OFDM (RIM-OFDM), which offers further considerable reduction in PAPR value and improved bandwidth utilization. In this paper, this newly proposed scheme has been mathematically established and block diagram for its realistic implementation has been described in detail. PAPR performance along with improvement in spectral efficiency of this technique, over SIM, has been investigated. Bit error rate (BER) performance is also studied and compared with that of classical OFDM. The results reveal that RIM-OFDM has come up as an optimized scheme, in terms of PAPR mitigation, bandwidth efficiency enhancement and low BER, for future wireless communication.

With the objective of improving the reliability of an operational 28 GHz full duplex line of sight (LOS) link even during rain, authors have initiated the link experiment with uplink power control procedure between a 28 GHz transmitter and receiver. The degradation of the said link is monitored at the receiver by measuring its power level which in turn is used to control the transmit power. One threshold level of fade margin has been set at the receiver, below which the control of transmit power is initiated to establish the link. Thus, in reality, the above-experimental facts are ensuring the establishment of a 28 GHz link and are thus useful for the future 5G millimeter-wave communication system which will face strong rain attenuation particularly in a tropical country like India.

In this paper, preliminary results from the artificial neural network (ANN)-based model developed at IIT Indore have been presented. One year hourly total electron content (TEC) database has been created from the International Reference Ionosphere (IRI)—2016 model. For the first time, a reverse problem has been addressed, wherein the training has been performed for predicting the three indices: 13-month running sunspot number, ionospheric index and daily solar radio flux also called targets to the network when hourly TEC values are the inputs. The root mean square errors (RMSEs) of these targets have been compared and minimized after several training of the dataset using different sets of combinations. Unknown data fed to the network yielded 0.99%, 3.12% and 0.90% errors for Rz12, IG12 and F10.7 radio flux, respectively, thus signifying ~97% prediction accuracy of the model.

The objective of this study is to investigate the cloud and rain attenuation at frequencies above 30 GHz, using radiosonde observations and TRMM satellite measurements, respectively, at a tropical location, Kolkata. The location experiences high value of liquid water content (LWC), the main reason for cloud attenuation, during Indian summer monsoon and pre-monsoon season. The rain height variation from TRMM satellite data has also been observed. Rain height varies from 3992 m to 5191 for the years 2004–2010 showing significant interannual variability. The exceedance curve shows higher occurrence in pre-monsoon than in monsoon season for rain attenuation values greater than 10 dB.

Intense geomagnetic storms can have a strong impact on the signals (termed as ionospheric scintillations) emitted by any global navigation satellite system (GNSS). The paper reports the first ever scintillations at Indore region on the NavIC signals due to impact of the intense geomagnetic storm event reported on September 8, 2017 at 01:51 and 13:04 UT. The variation of the planetary indices as well as the DST index which dropped to value of −124 nT on September 8, 2017 indicates the occurrence of an intense geomagnetic storm on September 8, 2017. The observations presented are carried out at Indore, which is located at the equatorial anomaly crest. The S4 index measurements of co-located GNSS receiver showed values ≥0.5 on the disturbed day between 15 and 18 UT. The analysis presented clearly signifies the degradation of carrier–noise measurements of NavIC L5 signal during the same time, which in turn affected the positional accuracy of NavIC, an important consideration for performance.

Raindrop size distribution (DSD) characteristics of monsoon and pre-monsoon seasons over Kolkata are analyzed by using three years raindrop size data from Joss–Waldvogel disdrometer located at Kolkata. The probability of occurrence DSD for different rain rate cluster has been observed for monsoon and pre-monsoon season. The mean raindrop concentration at a particular drop diameter and rain rate has been observed for both the seasons. The variations of number concentration with drop diameter and time have also been shown for monsoon and pre-monsoon season. The diurnal variations of DSD have also been investigated.

The main challenges of 5G cellular network are capacity increase of the existing cellular system, providing seamless and ubiquitous communication with very less delay. In future, femtocells and mobile femtocells will be deployed with macrocell base stations. The handoff algorithms which are available cannot be implemented efficiently in femtocell/mobile femtocell/macrocell network scenario. The essence of this paper is to propose a new handoff algorithm for 5G cellular network and evaluate its performance in 5G network scenarios. The performance of the proposed handoff algorithm is compared with a conventional handoff algorithm in terms of number of handoff, number of disconnection and efficiency for 10,000, 20,000, 30,000 randomly generated instances of 5G network scenarios.

OFDM-SIM offers the advantage of reduced peak-to-average power ratio (PAPR) and improved spectral efficiency in comparison with classic OFDM. Due to frequency selective channel fading, OFDM frames undergo non-uniform attenuation and this results in different SNR values for different frames. Consequently, BER of the system is degraded. This problem can be mitigated by using adaptive modulation scheme depending on SNR values estimated by channel estimator. In this paper, a simple model of OFDM-SIM with adaptive modulation is proposed. Switching decision is implemented by fuzzy interface system. The output BER performance of the OFDM-SIM has been investigated for two types of modulations: 8-PSK and 8-QAM with 10 dB SNR as threshold level.

An active phased-array VHF Doppler radar operated at 53 MHz is being established by University of Calcutta, Kolkata, at Ionosphere Field Station (latitude: 22.93 °N, longitude: 88.50 °E), Haringhata of the University near the transition between tropical-to-sub-tropical regions. A Pilot Array is presently operational. When completed, the main radar will be a unique facility to study the lower atmospheric dynamics over the eastern and north-eastern parts of India. Initial results of three components of wind profiles, i.e. zonal wind (u), meridional wind (v), and vertical wind (w) and their validation through balloon-borne GPS Radiosonde measurements made during July 2019 have been presented in this paper.

A fully active phased-array Stratosphere Troposphere (ST) radar at 53 MHz is being established by University of Calcutta at Ionosphere Field Station (22.93 °N, 88.50 °E geographic; magnetic dip: 34 °N), Haringhata, near the northern crest of equatorial ionization anomaly (EIA). When completed, this will be a unique facility at this frequency in the eastern and north-eastern parts of India and also in the south-east Asian longitude sector. Initial results of ionospheric backscatter of irregularities observed at the range of 120–140 km during early evening hours to midnight of the months of May through June 2019 from a Pilot Array are presented in this paper.

Single error correction (SEC) codes have been employed to protect the data bits as well as control bits in wireless sensor networks (WSNs) for Internet of Things (IoT) applications. In these systems, soft error typically single event upset (SEU) has been occurred. A low delay and power efficient error correcting codes are desirable in most of the wireless sensor networks. In this paper, three schemes have been proposed to construct the H-matrix of SEC codes. Based on these schemes, a low power and fast SEC codec has been designed and implemented for data width of 128 bits. Performances of the proposed SEC codes are observed in terms of area, power and delay. The maximum improvements in terms of number of LUTs and delay are 21.43% and 5.47%, respectively, compared to Reviriego et al. codes in FPGA platform. ASIC-based synthesis result shows that maximum power reduction of three proposed schemes are 16.06%, 14.8% and 6.06%, respectively, and delay reduction are 14.34%, 21.70% and 39.63%, respectively, compared to existing designs. The proposed codes may be used in WSNs for IoT applications such as smart cities, smart home and smart health care.

This paper aims at designing a thin low profile frequency-selective surface (FSS)-based absorber without an air gap in the frequency range of 6.1–12.5 GHz. A resistive FSS-based impedance surface of 11 Ω/square is designed on a two-layered FR4 substrate backed by a metallic plate. The return loss exhibited by the absorber is below −10 dB in the operating frequency range, yielding more than 90% absorption. The absorber shows an angular stability upto 50° for both TE and TM polarizations. The absorber is polarization insensitive due to its fourfold symmetric structure. Parametric studies of different impedance surfaces have been conducted. Finally, an equivalent circuit model is proposed which is used for deriving various circuit parameters.

The RF energy harvesting, a new booming research area during last decade for generating a small amount of electrical power, and its application in low-power electronics. A novel approach of Schottky diode-based Villard voltage multiplier circuit for energy harvesting application is proposed. A two-port Wilkinson power combiner circuit followed by Villard voltage multiplier circuit to combine output power from different energy sources is also studied. A Monte Carlo simulation has also been carried out for 10% tolerance value of the circuit components and results show proximity to the nominal or actual outcome. 30 mW power is achieved for Wilkinson power combiner circuit for 1 V input voltage.

In this work, the effect of emitter layer thickness variation on the frequency performance of GeSn heterojunction phototransistors (HPTs) is studied. Various characteristics parameters such as capacitance and transit time with respect to the emitter layer thickness ( $${t}_{E}$$ t E ) are calculated over the surface of the GeSn/Ge HPT. In addition, we have also calculated the cut-off frequency ( $${f}_{T}$$ f T ) and maximum frequency ( $${f}_{max}$$ f max ) with respect to the $${t}_{E}$$ t E of GeSn/Ge HPT. The calculated results show that the proposed device exhibits excellent $${f}_{T}$$ f T > 16 GHz and >  $${f}_{max}$$ f max 90 GHz for $${t}_{E}=100 \mathrm{nm}$$ t E = 100 nm .

High-dimensional modulation schemes have become the preferred choice for high data rate transmission. Compared to the conventional square 16QAM, hexagonal 16QAM configuration is less vulnerable to noise. This paper presents a theoretical error performance of uncoded hexagonal 16QAM using a lower computational complex approach.

A bilayer metasurface constituting of asymmetric split-ring resonator (ASRR) array as top layer and an E-Shaped resonator (ER) array as a bottom layer has been discussed in this paper. The former is aimed to make the waves passing through it go unaltered while the latter behaving as a bandstop filter through which polarization selectivity feature has been achieved. The measured transmission is maximized to 0.68 at 1.15 THz leading to realization of polarization conversion ratio (PCR) up to 99.9%. The PCR is above 90% in the range of 1.07–1.21 THz. The proposed structure has been compared with the other conventionally used optical devices. The polarization conversion of the structure has been carried out for various substrate materials used in the terahertz region like silicon dioxide and preperm L270(lossy).

In this manuscript, an ultra-thin (~λ/18.75), transmittive-type linear to circular (LTC) electromagnetic wave polarization converter in X-band employing metasurface (MS) has been reported. The proposed MS-based LTC polarization converter consists of two mirrored L-shaped structure and a thin strip designed over the top surface of 1.6 mm thick FR4 substrate while meander structure has been designed on the bottom side of the substrate. Numerical simulation results show the conversion of 45° linearly polarized incident wave into circularly polarized transmitted wave having axial ratio (AR) less than 3-dB over the frequency range 7.42–12.00 GHz; thereby yielding fractional bandwidth of 47.02% under normal incidence.

Mach–Zehnder modulator (MZM)-based energy-efficient scheme for 25 GHz RF generation, using frequency octupling technique is proposed. By employing a lower phase modulation index (PMI) of RF drive to MZM and utilizing phase cancelation of optical carrier by symmetric X-couplers, the ±fourth-order optical sidebands are generated efficiently. With the proposed scheme, a good optical and RF sideband suppression ratios of 26.2 dB and 25 dB, respectively, are achieved along with a reasonable output RF carrier power of 0 dBm.

A compact high-gain-printed antenna with triple band characteristics has been proposed in this paper. The design consists of microstrip-printed antenna embedded with bident-shaped metamaterial unit cells in the top side along with defected ground structure in which Rogers RT/duroid 6006 has been used as the substrate. The antenna resonates at three frequencies viz., 6.34, 9.79, and 10.30 GHz making the design versatile with a high gain of 7.9 dBi. A bandwidth of 1.08 GHz lying between the frequency range from 10.11 to 11.19 GHz has also been realized at 10.30 GHz. The proposed antenna finds diverse application in the fields of radar engineering, satellite communication, and defence tracking. It is also suitable for future 5G mobile communication services.

A low-cost intensity detection-based refractive index (RI) sensor is proposed and developed for rapid RI sensing. The sensor is composed of a planar waveguide structure on a low-cost glass substrate with an integrated microfluidic channel, which was fabricated using a simple, low-cost, vacuum-less and lithography-less process, making it suitable for mass production. Variation in the output light intensity, proportional to the RI of input solutions, is used as the simple and real-time mechanism for RI detection. A good RI resolution of $$4.65\times {10}^{-4}\mathrm{ RIU}$$ 4.65 × 10 - 4 RIU is achieved through RI experiments. These results suggest that the developed waveguide optofluidic sensors are promising for rapid and sensitive bio-medical detection.

This paper presents the computer-aided design of Ka-band RF cavities of a multibeam klystron. The state-of-the-art electromagnetic simulation tool CST microwave studio has been used for the design and optimization of the 28 GHz cavity with four beams. Different cavity parameters such as the quality factor, shunt impedance have been estimated with the help of the simulation tool for comparison among them.

Investigations are carried out on the space charge dependence of the negative resistances of avalanche and drift layers of double-drift region (DDR), indium phosphide (InP) and impact ionization avalanche transit time (IMPATT) diodes at high bias current levels near avalanche frequency by using computer simulation techniques. It is observed that DDR InP diodes behave like uniformly avalanching p-i-n diodes under the above situation, and the device negative resistance degrades sharply above a bias current density of 3 × 108 A/m2.

Generation of a self-similar parabolic pulse (PP) in presence of virtually gained normal dispersion tapered chalcogenide fibers is presented in this work. The variations of group velocity dispersion and mainly nonlinearity along the fiber length produce the proposed nonlinearity varying chalcogenide fibers (NVCFs) which can induce sufficient amount of virtual gain leading to obtain desired PPs at smaller optimum length. While studying the interaction among such pair of PPs, it is observed that an oscillating pulse train is created in the overlapping zone. The so generated beat frequency can be tuned in a range of 575– 832 GHz when a lengthwise variation of fiber is considered.

To achieve higher-order soliton pulse compression, single-mode anomalous dispersion silica-based fibers are chosen. Time transformation (TT) approach and symmetrized split step Fourier method (SSFM) are compared here to obtain the compressed optical pulses. The results obtained from TT method match quite well with the results of symmetrized SSFM, which validates the TT method in the domain of pulse compression. Variations of external chirp and input pulse width are also studied to achieve high compression factor in single-mode fibers within a shorter optimum length.

A tunable dual-band metamaterial absorber for terahertz range operation is illustrated in this paper. The tunability can be attained using the variable resistive property of diodes in reverse bias operation. The absorption bands are observed at ~45 μm (6.719 THz) and ~80 μm (3.765 THz). The structure exhibits variation in absorptivity with the variation in the resistance of diode. The proposed structure is with the dimensions having a periodicity of (~λ/4) and the thickness of (~λ/53). The tunable dual-band metamaterial absorber can have potential applications in the area of sensing, stealth technology, etc.

In this paper, a dual-band fractal-based printed wearable antenna backed with frequency selective surface (FSS) array is proposed for C- and X-band applications. The proposed antenna is designed to operate at 6 and 8 GHz with a high realized gain of 8.5 dBi and 9.4 dBi, respectively. The realized antenna provides a narrow band impedance bandwidth of 70 MHz centered at 6.01 GHz in the first band and UWB bandwidth of 780 MHz centered at 8.05 GHz for the second band, with maximum realized gain of 8.5 dBi and 9.4 dBi, respectively. The ground, FSS unit cell, reflector sheet and the radiating patch of antenna have been made using copper while styrofoam is used as the substrate material. The proposed design can be embedded on fabrics and is a potent candidate for wearable applications.

A microwave sensor is designed to operate at 2.4 GHz for measuring vital signs in human body. A double-layer patterned ground plane (GP) has been conceived to minimize the sensor size and experimentally verified. More than 360 MHz of 10 dB bandwidth and 2.28 dBi of gain over this band makes this sensor suitable for medical application. The simulated SAR value is found to be 0.5 W/kg for 30 mW of input power, which is much less than maximum limit 1.6 W/kg average over 1 g provided by FCC.

A small signal equivalent circuit model of uni-traveling carrier photodiode (UTC-PD) is developed from integral carrier density rate equation and parasitics are included with it. The technique to obtain scattering parameters from circuit model is given and simulation results are in good agreement with the measurement.

In this paper, the performance of a metasurface-based slot antenna in THz region has been studied. A rectangular slot has been designed on the bottom side of the antenna, where a square-shaped patch behaving as radiating element has been designed on the centre of the slot. The antenna offers fractional bandwidths of 6.04%, 12.84% and 2.76% at the frequencies 0.32 THz, 0.35 THz and 0.41 THz, respectively. The maximum realized gain of 7.51 dBi has been achieved at 0.35 THz, and unidirectional radiation pattern has been observed at all the operating frequencies.

Waveguide structure having a rectangular trench on top of its core has been studied. Variation of optical power overlapping with cladding of the waveguide has been shown as a function of trench dimension. Appropriate dimension for the trench to obtain large amount of optical power in the cladding has been shown, and the reason has been discussed. Usefulness of this study for suitable design of photonic phase actuator and sensor in photonic integrated circuit has also been discussed.

In this paper, a novel circular patch antenna model with added ring structures has been proposed and numerically simulated using CST Microwave Studio Suite. Various progressive stages of the antenna model have been shown with corresponding improvements in response. The final antenna model shows a good simulated response in the X band (10 GHz) and 5G communication band (27 GHz) with a decent gain value ranging from 3.25 to 4.77 dB.

In this study, the distribution of photons within a quantum dot (QD) light-emitting diode (LED) structure is presented by solving steady-state rate equations. The results show that the total photon density within the structure is distributed in a nonlinear manner along the direction of light propagation. Then the variation of photon density, contributing to LED power output, with facet reflectivity is shown for different injection current densities.

The parabolic pulse (PP) generation within an optical fiber occurs in the presence of gain. The required amount of gain can be supplied either physically or virtually by suitably tapering the core radius throughout the length of the fiber. Regarding PP generation, designing a dispersion increasing fiber (DIF) is undesirable as it introduces negative gain within the fiber. In this work, we have developed a special kind of a dispersion increasing chalcogenide fiber (DICF) where the nonlinearity-induced virtual gain plays the dominant function. In spite of the role of dispersion in reducing the effective gain, an efficient PP is generated in a sufficiently shorter fiber length without supplying any physical gain due to the much more substantial contribution from the nonlinearity of the fiber.

This paper presents a study on the propagation of modes of electromagnetic wave through a homogeneous multicore fiber. Complete view for fundamental modes for each core and other linearly polarized modes are obtaining here. Coupling between fundamental modes and other different cladding modes are presented in this paper. This study includes the coupling coefficient between multiple modes under periodic perturbation conditions for hexagonal seven core configuration.

This paper presents a miniaturized novel frequency-selective surface (FSS) absorber having ultra-wide absorption band. The proposed FSS absorber consists of a single-layer FSS printed on a grounded lossy dielectric with an air spacer and lumped resistors. The proposed design shows almost more than 90% absorptivity from 3.61 to 10.63 GHz, i.e., fractional bandwidth is 98.6%. A wide absorption band has been achieved by combining the effect of dielectric loss and ohmic loss of lumped resistors. The proposed structure is polarization insensitive being fourfold symmetric in nature. The structure shows more than 80% absorptivity upto 45° under oblique incidence at TE polarization.

Measurements of the 2.7 K CMB radiation provide the most stringent constraints on cosmological models. The power spectra of the temperature anisotropies and the E-mode polarization of the CMB are explained well by the inflationary paradigm. The next generation of CMB experiments aim at providing the most direct evidence for inflation through the detection of B-modes in the CMB polarization, presumed to have been caused by gravitational waves generated during inflation. B-mode polarization signals are very small (~10–8 K) compared with the temperature anisotropies (~10–4 K). Systematic effects in CMB telescopes can cause leakage from temperature anisotropy into polarization. Bolometric interferometry is a novel approach to measuring this small signal with lower leakage. Subdividing the frequency passband of a Fizeau interferometer would mitigate the problem of “fringe smearing.” The sub-band splitting method described here is general and can be applied to broadband Fizeau interferometers across the electromagnetic spectrum.

The study presented in this paper has been focused on the investigation of the WDM receiver performance in presence of the nonlinear crosstalks—namely, stimulated Raman scattering and four-wave mixing—and, hence, suggesting optimum detection thresholds to minimize bit error rate. To calculate the bit error rate, good representative models which are valid for any finite number of interferers are followed and the models are non-Gaussian in nature. The optimum detection thresholds calculated for different number of interfering channels keeping signal-to-noise ratio fixed are also summarized in tabular form.

This study presents enhancement of AlGaN/GaN HEMT device electrical characteristics by employing different gate engineered architectures. The dual-metal gate (DMG) structure is combined in different forms with recessed AlGaN and gate dielectric (HfSiO4) in order to extract the advantages offered by the individuals. A remarkable improvement in transconductance (8%) and drain current (~13 & 7%) is achieved with dual-metal-gated HEMT as well as with the proposed dielectric pocket (DP) dual-metal-gated HEMT device. The increased OFF-state leakage with the incorporation of dual-metal gate is suppressed successfully with the implication of dielectric pocket dual-metal gate structure. Apart from this, DP-DMG HEMTs has a 0.15 V positive shift in the threshold voltage in comparison with conventional SMG-HEMT, and therefore, this dielectric pocket HEMT can be seen as an upgradation to the next generation of HEMT devices.

High-field mobility characteristics of a degenerate two-dimensional gas (2DEG) are obtained under the condition of low lattice temperature. The characteristics are obtained by adopting two methods: (1) by solving the energy balance equation of the electron–phonon system and (2) from the current density of the non-equilibrium carriers. The quasi-elastic interactions with the deformation potential acoustic and the piezoelectric phonons have been considered. Some qualitative agreement of the numerical results thus obtained for wells of GaAs with the available experimental data has been observed.

A new current-mode sinusoidal quadrature oscillator is presented using current differencing transconductance amplifier (CDTA). This oscillator circuit is designed using one CDTA and two grounded capacitors. By adjusting the bias of CDTA, the oscillation condition and the oscillation frequency can be controlled. The output of the oscillator is current and has high output impedance. It is resistorless and uses grounded capacitors, which ease the IC implementation. PSPICE simulation satisfies the theoretical results.

At low lattice temperatures $$\left( {T_{{\text{L}}} \le 20\,K} \right)$$ T L ≤ 20 K , an apparently low electric field may effectively serve as high enough to significantly perturb an electron ensemble in a semiconductor from the state of thermodynamic equilibrium with the lattice atoms. The energy loss rate by an electron of the ensemble through impact ionization and excitation of neutral impurities may turn out to be comparable with the loss rate through interactions with the prevalent phonons and this takes part in controlling the non-Ohmic characteristics of the material. The present analysis deals with the calculation of the net energy loss rate of an electron and the subsequent effective electron temperature characteristics. The results obtained for InSb are compared with other theoretical and available experimental data. The agreement with the experiments is quite satisfactory. Moreover, the effects of impact ionization and neutral impurities at low temperatures are indeed not always negligible.

Studies are carried out to design and optimize the performance of next-generation dual-material double-gate (DMDG) P-channel TFET for low power digital application using Si as the channel material and SiO2 as gate dielectric. The channel length of the device has been varied in the range of 20–30 nm. The DC properties and performance of DMDG TFET have been compared with that of a dual-material single-gate (DMSG) TFET with respect to low power application of the device. 2D Poisson’s equation is solved to obtain the band diagrams for both on and off states, the electric field profile and surface potential of the device. The performance parameters of the optimized DMDGTFET such as on–off current ratio and subthreshold swing (SS) are compared with those of DMSG TFET. The results show that the DC properties of next-generation DMDG TFET excel those of DMSG TFET for a channel length of 20 nm. The on–off current ratio in DMDG TFET is 2.18 × 104 while the same in its DMSG counterpart is one order of magnitude lower. The values of SS in DMDG and DMSG TFET are found to be 20.1 and 36 mV/decade, respectively.

In this paper, we study the nonlinear channel electron mobility μ in an asymmetrically doped double quantum well field-effect transistor (QWFET) structure. The double quantum well consists of V-shaped channels by tailoring the conduction band edge of AlxGa1−xAs alloy through suitable variation of the alloy concentration x. We vary the widths of the wells asymmetrically and analyze their effect on the potential profile which causes drastic changes in the subband electron wave functions (ψn) and energy levels (En). In V-shaped potential, ψn are more localized than that of a square well. The change in the subband electronic structure induces change in occupation of subbands leading to intersubband interactions. We show that oscillatory enhancement in mobility under double subband can be obtained through the ionized impurity scattering through intersubband effects. The typical change of alloy concentration affects the alloy scattering which influences the overall total mobility μ.

In this paper, we develop analytical model of threshold characteristics for a Dual Material Double Gate tunnel FET to obtain compact and useful expressions. For the first time in literature, the influence of quantum confinement effects on threshold characteristics in short-channel tunnel FET are measured. For this purpose, we deploy the novel ‘surface potential-based approach’ which incorporates solutions of Schrodinger equation and Poisson’s equation. Using these models, a detailed quantitative comparison between classical and quantum models is plotted. The analytical results are validated with simulation results.

The excellent electronic properties of single crystal (sc) ultra-high pure (UHP) diamond, such as wide band gap, high carrier mobility and high displacement energy of atoms make it the current material of choice for radiation detection applications. This paper presents the suitability of commercially available free standing single crystal diamond plate from Soni CVD Diamonds, India, for fabrication, optical, and electrical characterization of diamond-based bulk photodetectors intended for use in radiation detection applications. The optical characterization includes Raman spectroscopy and the electrical characterizations include leakage current, capacitance–voltage, and ultra-violet response current measurements. Numerical simulations using SYNOPSYS© Sentaurus TCAD have also been carried out to determine the optimum thickness and doping density of a boron-doped diamond film intended to be grown on a type-IIa diamond substrate, for its potential use in alpha-particle spectroscopy.

The conversion of freely available energy to electrical energy is termed as energy harvesting. The sources of energy can be solar, light, vibration, thermal, and electromagnetic signals. Scavenging energy from these sources will reduce the use of batteries which need to be replaced regularly. RF energy is opted in this work due its high energy density and reliability. This paper presents an 8-stage RF-to-DC converter to convert 1800 MHz input radio frequency signal to a constant output voltage of 3.5 V for a load of 5 MΩ.

In this article, we examine the influence of separate gate biasing on independent gate FinFET and related circuit through RF performance, gain and harmonic distortion analysis. Non-quasi static channel approach is considered in the small-signal modelling of 4 T-IG-FinFET. Intrinsic parameters such as Cgs, Cgd, Rgd, τm, ft, fmax are investigated over an wide range of frequency (10–100 GHz). The device is then employed to simulate a single stage cascode amplifier, which offers flexibility in controlling its noise margins, gain and HDs through the applied back gate bias.

In the present work, the reliability issues of GaAs/Al2O3 Junctionless FinFET have been investigated by considering interface trap charges at semiconductor/oxide interface. RF/Analog performance of GaAs/Al2O3 Junctionless FinFET has been studied by evaluating different figures of merit such as drain current, Ion/Ioff ratio, transconductance, output conductance, capacitance (gate to source) and cut-off frequency. To analyze the effect of temperature on trap charges, the simulation study has been done at 300, 400 and 500 K temperature. In addition to this, a comparative analysis between GaAs/Al2O3 and Si/SiO2 Junctionless FinFET has also been carried out using a 3D device simulator (ATLAS). The results express that GaAs/Al2O3 Junctionless FinFET shows better performance in terms of the Ion/Ioff ratio and gives better immunity to trap charges as compared to Si/SiO2 Junctionless FinFET.

Ever-increasing power consumption due to continuous increase in circuit complexity in nanoscale electronic circuits and systems design is playing a pivotal role today. The necessity of mitigating higher power consumption issues and exploring different types of power minimization techniques are gaining rising importance. Search and exploration with different emerging circuit design technologies are also of increasing importance. A memristor is one such viable candidate with its inherent ability of low power consumption. Proper modeling and intelligent use of memristors in hybrid mode with CMOS can show a bright direction for future design. Here we tried to focus the light on this issue by inspecting the problem with a specific case study of the Wien-bridge oscillator circuit. The basic nonlinear modeling approach of the memristor is followed. Different configurations of circuit replacement are simulated to bring heterogeneity. Thus, an effort is presented in this paper to identify the proper and judicious use of memristors for power optimization. Simulation results are quite encouraging to predict the appropriate configuration for power reduction properly.

QWIP using group IV elements are of great research attention for its potential application in optical communication and in optical interconnects. The high-frequency performance of GeSn–SiGeSn QWIP has been studied considering the intersubband transition and transit time effect of electrons. The band structure of GeSn–SiGeSn QWIP and the analytical results of responsivity are also presented in this paper.

This paper evaluates the RF performance of an Asymmetric π - Gate MOSHEMT and HEMT architecture for high frequency applications through extensive TCAD simulations. To ensure that the simulation results conform with the actual device, simulation results have been calibrated with respect to experimental data. The calibrated device then acts as a primer for realizing the π - Gate HEMT and its Asymmetric MOSHEMT architecture. The performance has been investigated by introducing MOSHEMT architecture under both legs of the π - structure. Comparisons demonstrate an improvement in terms of current gain cut - off frequency by 20% (under right leg) — 25% (under left leg) when compared with the original π - Gate HEMT.

In this work, TCAD-based investigation has been performed to explore the influence of AlN cap layer on the reliability of AlGaN/GaN HEMT. Effect of cap layer thickness (AlN) and gate length on gate leakage current, drain current and off-current (Ioff) has also been demonstrated in this study. Using AlN cap layer, higher drain current has been achieved with significantly lower gate leakage current. However, almost same off-state current is achieved by using AlN material instead of GaN-based cap layer. With the enhancement in drain voltage, significant enhancement in gate leakage current is observed which is significantly higher in the device having GaN cap layer. Also, the improvement in gate leakage current with positive gate bias is significantly higher than the negative gate bias.

Hardware efficient digital systems have drawn significant attention to the researchers throughout the world over the last few years. In order to achieve this objective, this paper presents the design scheme of sharp cut-off FIR filter using an optimal value of interpolation factor, that produces minimum hardware complexity without affecting the filter performance. Simulation results help to achieve the favourable value of interpolation factor from a set of values. Moreover, the designed filter has subsequently been synthesized using Altera’s Cyclone IV FPGA board and the superiority of the design has been established by comparing its hardware cost with the other state-of-the-art design frameworks.

With the increasing demand of low-power integrated circuit for the RF transreceiver, it is always desirable to design the low-power phase lock loop. Nowadays, the demand of ultra-low-power PLL is increasing rapidly. Loop filter is one of the power consuming building block that takes large amount of power. This paper deals with the designing of the low-power transconductance-capacitance based loop filter with the help of dynamic threshold MOS technique. The simulation results show transconductance-capacitance loop filter operating at −3 dB frequency of 39.9 MHz with the power consumption of 252.78 µW along with the supply voltage of 1 V.

The effect of introducing an InAlN or AlGaN IL (interlayer) in between the barrier and QW for the green emission has been studied. The tensile strain of AlGaN compensates the compressive strain of InGaN/GaN interface. The IL increases the barrier potential and reduces the carrier leakage from the QW. These increase the device efficiency. By changing the doping in the barrier, the optical output can be increased for green QW LEDs with and without interlayer. The best results are obtained for the AlGaN IL which increases the transition probability up to 2 times, as compared to the QW LEDs, without IL.

This paper represents a novel approach of an inductor design having a high-quality factor using cascode topology. The proposed inductor consists of gyrator-C-based active inductor and parallel resonance circuit which are basically comprised of low value of spiral inductor and capacitor. This is validated in Cadence Virtuoso Tool using TSMC 180 nanometer technology CMOS process with power supply of 1.8 V. The designed inductor represents the inductance of above 40 nH with quality factor of over 880 around 2.45 GHz.

This paper explores the working principles of mixers, which is an integral part of superheterodyne transceiver system. Special emphasis has been led on the design of subharmonic mixers, which is a subclass of the mixer system by using 180-nm CMOS technology. The present paper highlights the design implementation of a 2× subharmonic mixer. From simulation results, it has been observed that the mixer attains 19 dBm IIP3, 12 dB conversion gain, 10 dB noise figure at 2–2.4 GHz RF range and 300–500 MHz of IF range. From 1.8 V supply, total power dissipation has been measured to be 3.8 mW.

The present work compares the reliability of AlGaN/GaN HEMT and MOS-HEMT using ATLAS TCAD software in terms of positive gate bias-induced stress. The applied positive gate bias stress modulates the 2DEG density in the channel region, thereby resulting in change in off-state current and threshold voltage with marginal change in on-state current. The work presented in this paper also analyzes the influence of barrier thickness, passivation permittivity and oxide permittivity on the parameters such as: Vth (threshold voltage), Ioff current and electron concentration. Maximum variation in Ids (drain current) and Vth has been seen with Al2O3-based AlGaN/GaN MOS-HEMT compared to SiN-based MOS-HEMT. The observed change in device performance with positive gate bias-induced stress has been higher in AlGaN/GaN MOS-HEMT as compared to HEMT. The effect of oxide thickness and operating temperature has also been investigated, and it has been seen that the change in device performance is tremendously high in MOS-HEMT compared to AlGaN/GaN-based HEMT.

Memristor field-effect transistor based on TiOx layer has been fabricated; 15-nm active switching layer and position of the different gates are confirmed from the scanning electron microscope structure. Forming voltage of  ~7 V is required to initiate the switching process. The set/reset voltages are strongly influenced by the gate voltage. As the gate voltage increases, the set/reset voltages also increase. The effect of gate on switching mechanism is also briefly discussed.

Multi-recessed Buffer Gate Field Plate AlGaN/GaN HEMT is considered in this paper for improving various device characteristics such as: breakdown voltage, threshold voltage. Recessed buffer layer spreads the electric field along the gate to drain region resulting in high breakdown voltage. In the present work, 119.5 V of breakdown voltage has been obtained at 0.25 µm gate length, when both gate to source and gate to drain buffer regions are recessed. Positive shift in threshold voltage (−5.8 V (for conventional GFP HEMT) to −0.1 V (for present structure) has also been observed from the GFP-AlGaN/GaN HEMT with multi-recessed buffer. Thus, by further optimizing the device parameter, enhancement mode behavior can be achieved from the device along with superior breakdown voltage. The high breakdown voltage is because of the lower ion-generation rate below the gate electrode as compared to conventional GFP-AlGaN/GaN HEMT.

A flash memory cell may store a single bit (single-level cell-SLC) or multi-bit binary data (multi-level cell-MLC). MLC devices are of less cost and allowed for higher storage density. Here, a dual-bit storage flash memory cell is presented which is capable to store two bits of information. It consists of two floating gates. One is present at the drain side, and the other one is present at the source side. The floating gates are electrically isolated from all the other electrodes by an inter-gate dielectric. The control gate and floating gate are separated by the control oxide layer, and the floating gate and substrate are separated by the tunnel oxide layer. Programming of the memory can be achieved by hot-carrier injection or F-N tunneling while erasing of the memory can be achieved by F-N tunneling.

In this paper, a tri-gate N-channel Ga0.47In0.53Sb-based FinFET is compared with conventional Si-based device for high-frequency applications. TCAD simulation tool is used to investigate the DC behavior of device for different bias voltages. Capacitative analysis is utilized to investigate the RF parameters such as intrinsic delay, power and energy dissipation, transconductance generation factor, and high cut-off frequency of the device. Si-FinFET exhibits better DC performance whereas Ga0.47In0.53Sb-FinFET excels in terms of RF performance factors such as lower gate delay, lesser power consumption, and energy dissipation with higher cut-off frequency. All these findings conclude that InGaSb-based FinFETs can serve as suitable candidates for novel nanoelectronic devices operating in the high-frequency regime.

The hybrid solar cells (HSCs) are the most abundant solar cell structures with higher charge collection efficiency, newer power conversion mechanisms, coupled with low cost. Recent studies have shown that metallic nanoparticles (MNPs) embedded with nanopyramid (NP) structures help to improve the photo-absorption over a wide range of wavelengths. Nanopyramidal structures, which consist of the tapered sidewalls, ensure gradual increment in the refractive index as light travels from air to the optical nerve of NP. In our study, we have used gold (Au) MNPs, which absorb and scatter the incident light into the substrate with the help of plasmonic resonance effects. In the proposed ITO/PEDOT:PSS/c-Si HSC structure, Au MNPs are located in the gap between nanopyramid arrays and the bottom of silicon (Si) substrate with molybdenum trioxide (MoO3) coating. The optical simulation of HSCs is carried out using finite difference time domain (FDTD) module of Lumerical solutions software package.

Historically Fenton’s reaction, under darkness or under light conditions, is considered a homogeneous process. The most important characteristic of Fenton’s reagent is related to its preparation due to it is an effective catalyst just using iron (II) ions, from specifically iron(II) sulphate salt (FeSO4), and hydrogen peroxide (H2O2). But with advancement of technology researchers are shifted to nano dimension and the traditional Fenton’s oxidation reactions are replaced by heterogeneous Fenton type reactions using various forms of nano zero-valent iron. It has been observed that there occurs a marked difference among various forms of nZVI, bare, ligand stabilized and composites towards the reaction with hydrogen peroxide. Primarily rate of hydroxyl radical production is greatly affected. The rate of pollutant’s removal from synthetic or industrial wastewater was also influenced. In this review article, we have summarized the reason of varying reactivity and tried to find out the best possible solution towards water pollution abetment

Values of intrinsic carrier density ni in Ge1−xSnx alloy (0 ≤ x  ≤ 0.2) are calculated by including composition dependent effective masses in Γ and L valleys in the conduction band, in light hole (LH) and heavy hole (HH) valence bands, and composition-dependent band gaps. The maximum temperatures of operation of the alloys are also determined over a range of dopant densities and alloy compositions. The temperature dependence of intrinsic density around room temperature is obtained by using x-dependent α and β parameters in Varshney’s equation. The maximum achievable electron mobility based on ni is estimated.