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The pole-phase modulated induction motor (PPMIM) drives facilitate the extended range of speed-torque characteristics, which is an essential requirement for traction and electric vehicle applications. For getting the wider speed-torque variations, $15-\Phi $ PPMIM drive is analyzed, which is capable to operate at 2-pole 15-phase, 6-pole 5-phase, and 10-pole 3-phase modes. In these pole-phase operations, in high-phase and low-pole mode of operation, the increment in the linear modulation range with space vector pulsewidth modulation (SVPWM) is not significant. In the low-phase and high-pole mode of operation, there will be higher torque ripples due to the higher magnitude of space harmonics. In this paper, these issues are addressed by using carrier phase-shifted SVPWM (CPS-SVPWM) and phase grouping concepts. In low-pole operation, the linear modulation is enriched by using conventional $3-\Phi $ SVPWM to drive 15-phase machine by appropriately reorganizing the phase winding connections. Similarly, in 6-pole 5-phase mode of operation, the linear modulation range of PPMIM drive is enriched by using $5-\Phi $ SVPWM. It is known that in high-pole mode of PPMIM drive operation, each effective phase is formed by the multiple number of equal voltage potential coils (EVPCs), which are electrically in phase. The carriers of these EVPCs per phase are phase shifted by an appropriate angle to minimize the harmonics in the effective phase voltage, which results in better torque ripple profile. In addition, the detailed comparison of three possible different CPS-SVPWMs is presented, with their pros and cons for selecting the proper carrier phase shift angle. The performance of the proposed scheme has been validated by ANSYS Maxwell two-dimensional as well as laboratory prototype on 5-hp, $15-\Phi $ PPMIM drive.

Ventilator device are external devices that are designed to assist a patient to perform a particular task. It is to keep up or improve a breathing ability of a person if he encounters problem in his own breathing. Ventilators play a vital role in human’s life. It is a piece of equipment, software program or product system that is used to increase, maintain, or improve the functional capabilities of persons with disabilities in breathing period. This paper deals with the hardware design of a lab model ventilator. A prototype model of the ventilator has been designed and tested

In this paper, we propose a configurable rotation matrix for Hyperbolic COordinate Rotation DIgital Computer (CORDIC) to compute any logarithm and inverse logarithm. The rotation matrix of the conventional Hyperbolic CORDIC computes only natural logarithm and natural inverse logarithm whereas the proposed rotation matrix configures the Hyperbolic CORDIC to compute any logarithm and inverse logarithm. Subsequently, an architecture for configurable Hyperbolic CORDIC has been designed based on the proposed rotation matrix. An extensive vector matching is performed to validate the proposed architecture. Finally, an ASIC implementation for configurable Hyperbolic CORDIC has been performed using TSMC 45-nm CMOS technology @ 1 GHz frequency. The accuracy of the proposed configurable Hyperbolic CORDIC is same as conventional Hyperbolic CORDIC. The proposed approach saves 19.22% on chip area and 17.52% power consumption for decimal logarithm computation and 18.55% on chip area and 16.12% power consumption for inverse logarithm computation when compared with the state of the art approaches.

We consider network coding for a noiseless broadcast channel, where each receiver demands a subset of the messages available at the transmitter and is equipped with noisy side information in the form of an erroneous version of the message symbols it demands. We view the message symbols as elements from a finite field and assume that the number of symbol errors in the noisy side information is upper bounded by a known constant. This communication problem, which we refer to as broadcasting with noisy side information (BNSI) , has applications in the re-transmission phase of downlink networks. We derive a necessary and sufficient condition for a linear coding scheme to satisfy the demands of all the receivers in a given BNSI network, and show that syndrome decoding can be used at the receivers to decode the demanded messages from the received codeword and the available noisy side information. We represent BNSI problems as bipartite graphs, and using this representation, classify the family of problems, where linear coding provides bandwidth savings compared to uncoded transmission. We provide a simple algorithm to determine if a given BNSI network belongs to this family of problems, i.e., to identify if linear coding provides an advantage over uncoded transmission for the given BNSI problem. We provide lower bounds and upper bounds on the optimal codelength and constructions of linear coding schemes based on linear error correcting codes. For any given BNSI problem, we construct an equivalent index coding problem. A linear code is a valid scheme for a BNSI problem if and only if it is valid for the constructed scalar linear index coding problem.

In this brief, we propose a low-complexity design methodology to compute square-root and division using circular coordinate rotation digital computer (CORDIC). Unlike the state of the art methods, the proposed methodology eliminates the requirement of a separate hardware for square root and division computation in the CORDIC-based applications without compromising the computational speed, throughput and accuracy. The ASIC implementation of the proposed architecture has been performed using UMC 90 nm Technology node with 1.08 V @1 MHz and subsequently Xilinx Virtex-6 (XC6v1x240t)-based FPGA-prototyping has been done. The performance of the proposed methodology has been compared with the reported literature and significant power consumption improvement was observed without any additional area overhead.

A fixed dimensional representation for action clips of varying lengths has been proposed in the literature using aggregation models like bag-of-words and Fisher vector. These representations are high dimensional and require classification techniques for action recognition. In this paper, we propose a framework for unsupervised extraction of a discriminative low-dimensional representation called action-vector. To start with, local spatio-temporal features are utilized to capture the action attributes implicitly in a large Gaussian mixture model called the universal attribute model (UAM). To enhance the contribution of the significant attributes in each action clip, a maximum aposteriori adaptation of the UAM means is performed for each clip. This results in a concatenated mean vector called super action vector (SAV) for each action clip. However, the SAV is still high dimensional because of the presence of redundant attributes. Hence, we employ factor analysis to represent every SAV only in terms of the few important attributes contributing to the action clip. This leads to a low-dimensional representation called action-vector. This entire procedure requires no class labels and produces action-vectors that are distinct representations of each action irrespective of the inter-actor variability encountered in unconstrained videos. An evaluation on trimmed action datasets UCF101 and HMDB51 demonstrates the efficacy of action-vectors for action classification over state-of-the-art techniques. Moreover, we also show that action-vectors can adequately represent untrimmed videos from the THUMOS14 dataset and produce classification results comparable to existing techniques.

Solar Photovoltaic Water Pumping (SPVWP) systems have established their potential as the most dependable and economically viable systems compared to the diesel based or grid-based electrical pumps. This paper presents an in-depth investigation of the energy efficiency of SPVWP system based on solar radiation, temperature, and operational heads. The study also identifies the shortcomings in the conventional design method based on Best Efficiency Point (BEP) concept that is applicable only in case of fixed frequency and voltage type pumps. However, in the case of SPVWP systems, due to variations in the solar intensity, ambient temperature, and water head, BEP concept does not offer the best efficiency design. The study experimentally proves that the model based on weighted system efficiency and Solar Operational Duty Head (SODH) increases the performance of SPVWP system (∼9% gain) and is consistently provide higher efficiencies in any season or under any climatic conditions.

The escalated targets for Solar Photovoltaic water pumping system (SPVWPS) installations in many Asian countries resulted in a huge demand for testing and certification of SPV pump samples. Test laboratories involved in testing and certifications are developing a generalized radiation and temperature profiles to cover various climatic conditions such as hot and dry, hot and humid, composite, cold and cloudy. The present paper addresses the challenges in the testing of a SPVWPS, through a step by step approach and devises solar radiation and temperature profile. Three types of testing profiles are designed to simulate “worst to worst”, “best to best” and “composite” conditions, so that evaluation of the sample can cover all the possibilities of pumping operation for the entire year. One of these three proposed testing profiles, the composite profile, reduces the total time of execution for testing of a sample, without comprising of any attributes of the testing method. Further, the developed composite radiation profile covers the large geographical area of the India and also other Asian countries and yet impart all realistic environmental conditions. The developed method of testing takes into consideration of the effects of individual components such as PV array, solar pump controller and motor pump set individually and collectively. The method also brings out superiorities and shortcomings in these components under the actual field conditions. All relevant experiment results are produced to verify the proposed testing methods.

Herein, we report cuprous oxide nanocubes decorated reduced graphene oxide (CNC-rGO) immersed in chitosan matrix as a versatile and enhanced electrochemically active electrode material for both supercapacitor and hydrogen peroxide (H2O2) sensor applications. The CNC-rGO was synthesized by one-pot scalable chemical precipitation method. The morphology and crystal structure of as-synthesized hybrid material was characterized by field emission scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The CNC-rGO hybrid material immersed in the chitosan matrix was used as an enhanced electrochemically active electrode material for supercapacitor and hydrogen peroxide (H2O2) sensor. The fabricated CNC-rGO hybrid in chitosan matrix as an electrode showed remarkable charge storage capacity of 772.3 F g−1 (12.87 mA h g−1) at a current density of 0.2 A g−1 with high cyclic stability over 2000 charge-discharge cycles. Similarly, H2O2 sensing performance of the same electrode exhibits very high sensitivity of 0.33 A M−1 cm−2 within a linear range of detection of 20–160 μM. Thus, the synthesized CNC-rGO hybrid material composed of numerous cuprous nanocubes on rGO nanosheets with large active sites showed enhanced electrochemical activity beneficial towards the supercapacitor and H2O2 sensor applications.

Multicasting $K$ independent messages via multiple-input multiple-output channels to multiple users where each user already has a subset of messages as side information is studied. A general framework of constructing layered space-time index coding (LSTIC) from a large class of space-time block codes (STBC), including perfect STBC, is proposed. We analyze the proposed LSTIC and show that it provides minimum determinant gains that are exponential with the amount of information contained in the side information for any possible side information . When constructed over a perfect STBC, the proposed LSTIC is itself a perfect STBC and hence many desired properties are preserved. To illustrate, we construct LSTIC over the following well-known STBCs: Golden code; $3\times 3$ , $4\times 4$ , and $6\times 6$ perfect STBCs; and Alamouti code. Simulation results show that the obtained side information gain can be well predicted by our analysis.

Herein we report a simple, one-step approach to prepare a low-cost and binder free MoS2-pencil graphite electrode (i.e., MoS2-PGE) for the electrochemical oxidation of DNA nucleobases i.e., guanine (G) and adenine (A) in physiological pH (7.4) buffer solution. MoS2-PGE was synthesised by hydrothermal method and the morphology of such hybrid was characterized by field emission scanning electron microscopy, X-ray diffraction, Raman and X-ray photoelectron spectroscopy. In cyclic voltammetry, MoS2-PGE displays two well-seprated and well-defined irresversible peaks at 0.58 and 0.90 V for electrochemical oxidation of G and A respectively when compared to bare PGE. Likewise, differential pulse voltammetry of MoS2-PGE showed well-seprated and sharp peak current responses for G and A at 0.56 V and 0.85 V respectively. Under optimized conditions, DPV was further adopted for simultaneous and separation-free determination of G and A in physiological pH. MoS2-PGE shows good stability with linear range of 15–120 μM and 15–120 μM for G and A detection respectively. Obtained sensitivity and limit of detection (signal-to-noise = 3) are comparable with the previous literature. As an immediate practical applicability, MoS2-PGE was used for quantification of G and A concentration in calf-thymus DNA and detected ratio of G and A (i.e., [G]/[A]) ratio is 0.85. The current approach provides a new avenue towards the development of affordable electrodes for a wide range of bioanalytical applications.

Herein, we report a facile synthesis of sodium niobiate (NaNbO3) perovskite nanomaterial using a solid-state reaction (SSR) via solvothermally grown niobium pentoxide (Nb2O5) nanopowder for the excellent sensitive detection of dopamine (DA) in simulated blood serum with high selectivity. The X-ray Diffraction (XRD) pattern and Raman spectrum revealed an orthorhombic phase formation for NaNbO3 and the presence of a NbO6 octahedra site, while the scanning electron microscopy (SEM) images confirmed berry-like cluster formations of NaNbO3. The NaNbO3 modified glassy carbon electrode (GCE) sensor showed an excellent selectivity against interfering species like Na+, Cl−, Ca2+, glucose, ascorbic acid (AA), anduric acid, a sensitivity of 99 nA nM−1 cm−2 in the wide dynamic range of 10 nM to 500 μM, and a limit of detection (LOD) of 6.8 nM towards DA sensing, making it suitable for detecting physiological levels of DA in human blood. The sensing mechanism for DA was ascribed to the presence of NbO6 octahedral sites in the NaNbO3 perovskite structure that interacted with the oxidase of DA (dopamine-o-quinone) through Nb5+/Nb4+ niobium states, resulting in an increase in the oxidation peak current. This sensor did not exhibit any kind of surface fouling effects due to the reduction mechanism and the Na+ ions stabilizing the perovskite structure. The as-fabricated NaNbO3/GCE sensor was further assessed for the detection of DA in simulated blood serum, which showed an excellent recovery percentage. This novel, binder-free, NaNbO3 perovskite-based modified electrode offers a promising platform for developing high performance, non-enzymatic electrochemical sensors for numerous bioanalytical applications.

While all reports on electrochemical uric acid (UA) sensors are on rigid electrodes and based on either complex fabrication procedures or multiple steps based synthesis techniques, this paper is the first demonstration of a single step hydrothermally grown MoS2 on aluminium foil (Al) based flexible electrochemical sensor for non-enzymatic detection of UA. FESEM images revealed MoS2 micro-flower like structure comprising of interlaced nanosheets while chemical characterization data confirmed the successful growth of few layered (>4 layers) MoS2 on Al foil. The as-fabricated flexible sensor exhibited a limit of detection of 1.169 μM, a response time of

Here, a controlled green synthesis route involving hydrothermal pre-carbonization cum pyrolysis is reported that converts cucumber into graphene-like carbon nanosheets for supercapacitor application. Transmission electron microscopy analysis reveals the formation of ultra-thin carbon nanosheets with distributed pores. This cucumber derived carbon exhibits high specific capacitance of 143 F g−1 in aqueous electrolyte. The two-electrode symmetric cell exhibits a specific capacitance of 58 F g−1 at high current density, and high capacitance retention of 97% after 1000 cycles. This simple low-cost process involving widely available cucumber as biomass precursor is a promising, commercially viable approach for developing high-performance supercapacitors.

Here, we report a Cadmium oxide (CdO) nanoparticles modified disposable screen-printed carbon electrode (SPCE) for non-enzymatic detection of ascorbic acid (AA) with excellent stability and nano-molar detection limit. CdO nanoparticles synthesized by a simple, low-cost one-step co-precipitation method exhibits uniform crystalline nature and surface functional groups confirmed by XRD and FTIR spectroscopy. As a model analyte, AA was used to evaluate the electrocatalytic activity of CdO by cyclic voltammetry and differential pulse voltammetry (DPV) methods. The newly developed electrode, i.e., CdO nanoparticles modified SPCE shows AA oxidation peak at potential, ∼ 0.2 V vs. Ag/AgCl. Under optimal DPV condition, CdO-SPCE detects a wide range of concentration from 5 to 150 μ M with a current sensitivity of 0.42 A M−1 cm−2 and ultra low-level detection (53.5 nM). Furthermore, the proposed sensor was highly stable and exhibited excellent selectivity towards the detection of AA in the presence of interfering electroactive agents such as urea, uric acid, glucose, citric acid, Na + ion and sucrose. For quick quality control assessment, a CdO modified SPCE (CdO-SPCE) was developed as a disposable sensor for real-time applications. A canned fruit juice (real sample) successfully analysed using CdO-SPCE exhibits a recovery value of ∼ 100%.

Herein, we report platinum (Pt) nanoflowers decorated reduced graphene oxide (rGO)–tin oxide (SnO2) composite as an efficient electro-catalyst for direct methanol fuel cells (DMFCs). rGO-SnO2 composite is synthesized by a novel, eco-friendly hydrothermal method using lemon extract followed by electro-deposition of Pt to yield high density Pt nanoflowers uniformly distributed over rGO-SnO2 for superior catalytic performance and optimal utilization of Pt nanostructures. Whilst Pt nanoparticles (NPs)-rGO-SnO2 composite exhibits higher CO tolerance ability (If/Ib = 3) and poor catalytic stability, Pt nanoflowers-rGO-SnO2 composite shows comparable CO tolerance ability (If/Ib = 1.81) with excellent stability. At 3000 s, the current density of Pt nanoflowers-rGO-SnO2 has been found to be 2.1 folds higher than Pt NPs-rGO-SnO2 composite. Excellent durability of Pt nanoflowers-rGO-SnO2 is attributed to the high surface area of Pt nanoflowers which provides more active sites during methanol oxidation without any agglomeration, thus, facilitating diffusion of methanol to Pt for catalytic activity. As per our knowledge, this is the first report on Pt nanoflowers-rGO-SnO2 composite based electro-catalyst for DMFCs that yields superior performances in terms of catalytic efficiency, CO tolerance activity and stability. The composite shows enormous potential to be used as binder free, cost-effective, efficient and durable electro-catalyst for DMFCs applications.

In this work, we report a novel, cost effective and environmental-friendly green synthesis method of reduced graphene oxide (rGO) – tin oxide (SnO2) composite using lemon extract by hydrothermal process for selective and ultra-sensitive electrochemical detection of ascorbic acid. The electrochemical behavior of ascorbic acid at the surface of rGO-SnO2 composite modified glassy carbon electrode (GCE) was investigated by cyclic voltammetry (CV) technique whilst ascorbic acid sensing was performed by using differential pulse voltammetry (DPV) technique. An excellent sensitivity of 1200 μA mM−1 cm−2 (R2 = 0.990) towards ascorbic acid in the wide dynamic range of 400 μM −1600 μM without any surface fouling effect was observed which is, to the best of our knowledge, ~1.6 folds higher than previously reported ascorbic acid sensors. The as-fabricated sensor exhibited lower limit of detection (38.7 μM), superior reproducibility and selectivity towards interfering species such as glucose, urea, uric acid and Na+ ions. This enhanced sensing ability was studied and discussed in terms of forward biased nano-Schottky barriers at the rGO-SnO2 interface. The sensor was successfully evaluated for the detection of ascorbic acid in the vitamin C tablets and to predict unknown concentrations of ascorbic acid in PBS solution. This ultrasensitive, binder free rGO–SnO2 composite based sensor can be used for a simple, low cost and voltammetric detection of ascorbic acid in clinical diagnostics, pharmaceutical and food industries.

In this work, we demonstrate platinum (Pt) nanoflowers-reduced graphene oxide (rGO) composite as an efficient electrocatalyst for methanol oxidation reaction (MOR) in acidic medium. rGO was prepared by low-cost, eco-friendly hydrothermal method and electro-deposition of Pt yielded three-dimensional large area Pt nanoflowers distributed over and among thin rGO nanosheets, thereby preventing restacking of rGO sheets. The composite exhibited outstanding electro-catalytic activity (15.3 mA cm−2), stability with CO tolerance ability (If/Ib = 6.99) which is, to the best of our knowledge, ∼2.2 folds greater than other previously reported carbon nanomaterials based catalysts. Values of If, Ib and If/Ib ratio of Pt-rGO based electrode were 13.2, 5.2 and 2.55 folds higher than only Pt respectively, which are ascribed to higher surface area of Pt nanoflowers that offers multidimensional pathways for easy diffusion of methanol to Pt, more catalytic active sites and excellent utilization of Pt for MOR. The composite shows huge potential to be used as binder free, cost-effective and durable electrocatalyst for electrochemical sensing and DMFCs applications.

Herein, we report a simple and eco-friendly method for the development of an ultra-low-cost carbon electrode for high-performance supercapacitor applications. Current work involves the electrochemical oxidation of pencil graphite electrode (PGE) to graphene oxide covered pencil graphite electrode (PGE*) by cyclic voltammetry in pH 2 acidic electrolyte (KCl-HCl). The release of intrinsic iron (Fe) from the PGE, which facilitates the electrochemical oxidation of graphite is confirmed by collective electro and physico-chemical characterizations. Potential segment analysis and studies of different pencil grades suggest that electrochemical oxidation of PGE depends upon anodic potential and concentration of intrinsic Fe. Among various pencil grades (8B-6H), 6H-PGE* displays ultra-high areal capacitance (105 mF cm−2 at 0.07 mA cm−2). A high concentration of intrinsic Fe in 6H-PGE facilitates the in-situ electrochemical oxidation of pencil graphite. Further, the cyclic stability over 1000 charge/discharge cycles renders excellent capacity retention of 95%, thus indicating the high rate capability of PGE* electrode. This strategy provides a novel, simple, cost-effective and eco-friendly approach for the preparation of a high-performance supercapacitor.

This paper presents a multilevel inverter (MLI) configuration for open-end-winding pole-phase-modulated-multiphase induction motor (PPMMIM) drives. The proposed MLI configuration consists of one nine-phase two-level inverter and three 3-Φ two-level inverters. In pole–phase modulation, increasing the number of poles decreases the number of phases that increases the space harmonics in air gap flux. Moreover, in high-pole mode of PPMMIM drives, two-level voltage supply causes the high torque ripple that degrades the performance of the drive. Usually, conventional MLIs are not preferred for reducing torque ripple, due to the capacitor-balancing issues and more number of semiconductor devices. To address these issues, the proposed MLI configuration effectively utilized the inherent availability of the three identical voltage coils in the high-pole mode for reducing the torque ripple. The 3-Φ carrier phase-shifted space vector pulse width modulation (SVPWM) is used for generating the multistep voltage across the effective phase in high-pole mode as well as for shifting the lower order harmonics to higher order frequencies. Moreover, in low-pole mode, the dc-link voltage utilization of the proposed MLI configuration is improved by 13.8% with third harmonic injected SVPWM as compared to conventional 9-Φ SVPWM. Another important feature of the proposed MLI configuration is its ability to supply the two-level voltage under fault conditions. This feature notably improves the reliability of the PPMMIM drive. The finite-element method model of 5-hp nine-phase PPMMIM is designed in ANSYS Maxwell 2-D and is cosimulated with the proposed MLI configuration in Simplorer environment. The effectiveness of the proposed MLI-fed 5-hp MIM drive is experimentally verified for the entire modulation range.

Surface electromyography (sEMG) data acquired during lower limb movements has the potential for investigating knee pathology. Nevertheless, a major challenge encountered with sEMG signals generated by lower limb movements is the intersubject variability, because the signals recorded from the leg or thigh muscles are contingent on the characteristics of a subject such as gait activity and muscle structure. In order to cope with this difficulty, we have designed a three-step classification scheme. First, the multichannel sEMG is decomposed into activities of the underlying sources by means of independent component analysis via entropy bound minimization. Next, a set of time-domain features, which would best discriminate various movements, are extracted from the source estimates. Finally, the feature selection is performed with the help of the Fisher score and a scree-plot-based statistical technique , prior to feeding the dimension-reduced features to the linear discriminant analysis . The investigation involves 11 healthy subjects and 11 individuals with knee pathology performing three different lower limb movements, namely, walking, sitting, and standing, which yielded an average classification accuracy of 96.1% and 86.2%, respectively. While the outcome of this study per se is very encouraging, with suitable improvement, the clinical application of such an sEMG-based pattern recognition system that distinguishes healthy and knee pathological subjects would be an attractive consequence.

Lattices possess elegant mathematical properties which have been previously used in the literature to show that structured codes can be efficient in a variety of communication scenarios, including coding for the additive white Gaussian noise channel, dirty-paper channel, Wyner–Ziv coding, coding for relay networks, and so forth. We consider the family of single-transmitter multiple-receiver Gaussian channels, where the source transmits a set of common messages to all the receivers (multicast scenario), and each receiver has coded side information , i.e., prior information in the form of linear combinations of the messages. This channel model is motivated by applications to multi-terminal networks, where the nodes may have access to coded versions of the messages from previous signal hops or through orthogonal channels. The capacity of this channel is known and follows from the work of Tuncel (2006), which is based on random coding arguments. In this paper, following the approach of Erez and Zamir, we design lattice codes for this family of channels when the source messages are symbols from a finite field $\mathbb {F}_{p}$ of prime size. Our coding scheme utilizes Construction A lattices designed over the same prime field $\mathbb {F}_{p}$ , and uses algebraic binning at the decoders to expurgate the channel code and obtain good lattice subcodes, for every possible set of linear combinations available as side information. The achievable rate of our coding scheme is a function of the size $p$ of underlying prime field, and approaches the capacity as $p$ tends to infinity.

In recent days, multilevel inverters are quite popular in the photovoltaic system to improve the power quality. One of the popular multilevel inverters for medium power applications is neutral point clamping inverter. However, with the limited number of switching combinations, energy balancing and fault-tolerant operation is a major issue. The absence of energy balance mechanism may lead to unequal charge and discharge patterns in the batteries used in off-grid applications, which in turn results in the un-equal voltage at the batteries terminals. The difference in voltage between the sources can introduce the DC voltage offset at AC output, which causes serious problems when fed to the transformers or inductive loads like the induction motor. To address this problem, a five-level inverter is proposed which is capable of energy balancing between the two DC sources, minimising the DC voltage offset and able to operate in some fault-tolerant conditions. At the same time, this topology uses less number of switches as compared to conventional three-phase five-level inverters. The proposed topology is developed by combining conventional two-level and three-level inverters. The topology is verified by simulation using Matlab Simulink and tested on a laboratory prototype. The control algorithm for prototype is implemented with the help of Xilinx SPARTAN-6 (XC6SLX9) FPGA board.

Base station sleeping (BSS) can result in significant reduction in energy consumption of cellular networks during low traffic conditions. We show that the coverage loss due to BSS can be compensated via coordinated multi-point (CoMP) -based transmission in a cluster of base stations. For a BSS with CoMP-based system, we propose various BSS patterns to achieve suitable trade-offs between energy savings and throughput. We formulate the CoMP resource allocation and $\alpha -$ Fair user scheduling as a joint optimization problem. We derive the optimal time fraction and user scheduling for this problem and use it to formulate a simplified BSS with CoMP optimization problem. A heuristic that solves this problem is presented. Through extensive simulations, we show that suitable trade-offs among energy, coverage, and rate can be achieved by appropriately selecting the BSS pattern, CoMP cluster, and rate threshold.

In this brief, we propose a low-complexity methodology to compute a complex square root using only a circular coordinate rotation digital computer (CORDIC) as opposed to the state-of-the-art techniques that need both circular as well as hyperbolic CORDICs. Subsequently, an architecture has been designed based on the proposed methodology and implemented on the ASIC platform using the UMC 180-nm Technology node with 1.0 V at 5 MHz. Field programmable gate array (FPGA) prototyping using Xilinx’ Virtex-6 (XC6v1x240t) has also been carried out. After thorough theoretical analysis and experimental validations, it can be inferred that the proposed methodology reduces 21.15% slice look up tables (on FPGA platform) and saves 20.25% silicon area overhead and decreases 19% power consumption (on ASIC platform) when compared with the state-of-the-art method without compromising the computational speed, throughput, and accuracy.

Conventional supercapacitors use insulating binders with active materials for fabricating working electrodes. Use of such binder reduces electrical conductivity of the electrode, thus causing energy wastage of supercapacitor. To overcome this, herein, we report binder free Platinum (Pt) nanoparticles (NPs) decorated Graphene–Polyaniline (Gr-PANi) composite modified electrode for supercapacitor application. Pt decorated Gr-PANi composite was prepared by template-free electrochemical polymerization method followed by electro-deposition of Pt NPs. Detailed structural and chemical characterization of the composite were done by SEM, EDX spectroscopy and Raman scattering. FESEM image of Pt decorated Gr-PANi composite revealed nano-fibrous structure of PANi (average diameter of 50–100 nm) with Pt NPs uniformly deposited on its surface. Interconnected network of PANi nanofibers made matrix highly porous, thereby, providing an improved electrode/electrolyte interface area and shorter diffusion lengths for electrolytic ions. The electrochemical behavior of Pt NPs decorated Gr-PANi composite film was studied by cyclic voltammetry while galvanostatic charge–discharge measurements were carried out to investigate its capacitive performances. Pt decorated Gr-PANi composite based supercapacitor exhibited higher specific capacitance of 922.5 F/g which was ∼ 1.75 folds greater than that of only Gr-PANi based electrode at same current density (1 A/g) and much higher than previously reported Gr-PANi composite based supercapacitors. The developed Pt decorated Gr-PANi composite modified electrode exhibited charge capacity of 0.57 mAh/cm2 and discharge capacity of 0.29 mAh/cm2 which were 2.4 folds and 1.81 folds higher than only Gr-PANi electrode respectively. The significant improvement in specific capacitance with excellent sustainability to higher current, superior rate capability, charge storage capacity and cycling stability can be attributed to the synergistic effect of electrical double-layer capacitance and pseudocapacitance resulting from Gr and PANi respectively and excellent catalytic ability of Pt NPs. The as-synthesized Pt decorated Gr-PANi composite offers simple, promising and binder free electrode material for energy storage devices.

Here, we report a grapheme–polyaniline (Gr-PANi) composite modified glassy carbon electrode (GCE) as an amperometric pH sensor. Gr-PANi composite was synthesized by electro-deposition of PANi on the surface of Gr modified GCE using the cyclic voltammetry technique. XRD and Raman analysis confirmed high crystallinity of Gr-PANi composite. FESEM analysis revealed that Gr flakes are surrounded by PANi film because of the heterogeneous nucleation and growth of PANi during electro-polymerization. In acidic region, current of the composite-based pH sensor increased with decreasing pH values of the solution, whereas in alkaline region, current increased with the increasing pH values of the solution. The as-fabricated pH sensor exhibits shorter response time with an excellent sensitivity of - $50.14~\mu \text{A}$ pH−1 cm $^{-2}$ in the range of pH 1–5 and $139.2~\mu \text{A}$ pH−1 cm $^{-2}$ in the range of pH 7–11. The composite-based sensor showed enhanced sensitivity compared with pure Gr-based pH sensor because unlike pristine Gr-based pH sensor, it utilizes both charge-storage mechanisms in EDLCs and pseudo-capacitors, thereby resulting in excellent synergy between Gr and PANi. Reproducibility of the pH sensor was also examined between three different electrodes in the solution of pH 5. Insignificant variation in the current response suggested excellent reproducibility of pH sensor. To the best of our knowledge, no other studies have been reported on the Gr-PANi composite-based pH sensor over wide pH range. This Gr-PANi-based pH sensor offers a simple, low-cost, promising, real-time amperometric pH sensor in chemistry, clinical diagnostics, bio-sensing, and environmental monitoring applications.

Line-of-sight (LoS) multiple-input multiple-output (MIMO) gives full spatial-multiplexing gain when the antenna array geometry and orientation are designed based on the interterminal distance. These known design methodologies that hold for antenna arrays with fixed orientation do not provide full MIMO gains for arbitrary array orientations. In this paper, we study LoS MIMO channels with random array orientations when the number of transmit antennas used for signaling is 2. We study the impact of common array geometries on error probability, and identify the code design parameter that describes the high signal-to-noise ratio (SNR) error performance of an arbitrary coding scheme. For planar receive arrays, the error rate is shown to decay only as fast as that of a rank 1 channel, and no better than SNR $^{-3}$ for a class of coding schemes that includes spatial multiplexing. We then show that for the tetrahedral receive array, which uses the smallest number of antennas among nonplanar arrays, the error rate decays faster than that of rank 1 channels and is exponential in SNR for every coding scheme. Finally, we design a LoS MIMO system that guarantees a good error performance for all transmit/receive array orientations and over a range of interterminal distances.

Detection of urea is of prime importance in food and water safety, dairy industries and environmental monitoring. Traditional methods to detect urea are either expensive and involve sophisticated instrumentation or are based on enzymatic approach of detection. Herein, we report a Graphene-Polyaniline (Gr-PANi) based electrochemical sensor for non-enzymatic detection of urea. Gr-PANi composite was synthesized by electro-deposition of PANi on the surface of Gr modified GCE using cyclic voltammetry (CV) technique. The presence of Gr and PANi in the composite was confirmed using a multitude of characterization techniques which included FESEM, XRD and Raman spectroscopy. The electrochemical behavior of urea at the surface of Gr-PANi modified GCE was studied by CV whereas urea sensing was performed by using simple current-potential (I–V) technique. The current response of the as-fabricated urea sensor was ∼ 4.74 folds greater than that of pure PANi based sensor and ∼ 67.2 times greater than that of pure Gr based sensor. The sensing performance of the composite based urea sensor was optimized by varying the thickness of PANi film. The optimized sensor exhibited lower limit of detection (5.88 μM), excellent reproducibility, selectivity and stability with an enhanced sensitivity of −226.9 μA/μM cm2 (R2 = 0.993) in the range of 10 μM–200 μM. The reliability of the as-fabricated sensor was successfully investigated by using it to detect urea concentrations in samples of tap water and milk samples. This highly-sensitive Gr–PANi composite based urea sensor provides a simple, low cost, non-enzymatic approach for detection of urea that find numerous applications in clinical diagnostics, dairy industries, fertilizer plants and environmental monitoring.

A temperature compensated under voltage lockout (UVLO) circuit for ultra-low power applications is presented. The UVLO operation is achieved using two transistors with different threshold voltages and a source follower. The difference in the thresholds of the two transistors is used to create a reference voltage. As the supply voltage rises, the generated reference voltage tracks the supply till its designed voltage value and thereafter becomes a constant. This reference voltage is applied to a self-referenced common-source stage and is further amplified by CMOS inverters to arrive at a decision to lock out the supply or not. The designed UVLO consumes 200 pA of current at 1.8 V supply. The measured low-to-high trip points (LHTP) and high-to-low trip points (HLTP) are 1.28 V and 1.12 V with a variability of 208 ppm/°C and 200 ppm/°C respectively. These trip points are programmable from 1.1 V to 1.4 V in steps of 100 mV. The design occupies 0.00723 mm2 in standard 180 nm CMOS.

An electrochemical dopamine (DA) sensor has been fabricated by modifying a glassy carbon electrode (GCE) with ruthenium disulfide (RuS2) nanoparticles (NPs). FESEM and TEM micrographs show the NPs to have an average size of ~45 nm. XRD, Raman and EDS, in turn, confirm the successful formation of cubic phased RuS2 NPs. The modified GCE displays has attractive features of merit that include (a) an ultra-low detection limit (73.8 nM), (b) fast response time (< 4 s), (c) a low oxidation potential (0.25 V vs. Ag|AgCl), (d) excellent reproducibility and stability, (e) an electrochemical sensitivity of 18.4 μA μM−1 cm−2 and 1.8 μA.μM−1.cm−2 in the linear ranges from 0.1–10 μM of DA (R2 = 0.97) and 10–80 μM of DA (R2 = 0.99), respectively. The sensor exhibits excellent specificity over potential interferents like ascorbic acid, glucose and uric acid. The superior performance of the sensor is attributed to its high electrical conductivity, large electro-active surface, and large numbers of exposed catalytically active sites resulting from the presence of unreacted sulfur atoms.