External DC Research Articles

New Zero Power Memristor Emulator Model and Its Application in Memristive Neural Computation

We present here a simple three P-type MOSFET-based grounded memristor emulator model. The model is designed to achieve zero static power dissipation and is done so by eliminating the external DC supply i.e., no DC bias. The proposed memristor emulator model has extremely low dynamic power dissipation as well which comes to around 175 nW i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim ~67\%$ </tex-math></inline-formula> improvement compared to recent work. A mathematical analysis is carried out to present the relevance of this design. Simulations were done on Cadence Virtuoso 90 nm technology node and fingerprints of the proposed memristor emulator were obtained. The layout area occupied by the model is approx <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1154.69~\mu \text{m}^{2}$ </tex-math></inline-formula> and an external capacitor is connected to add tunability to the circuit. Furthermore, Monte Carlo and corner analysis validate the robust nature of the design. Besides, simulations have been experimentally verified using CD-4007 CMOS integrated circuit (IC) to make the design practically feasible. Furthermore, the design offers advantages such as extremely less overall power consumption and smaller chip area that could possibly pave the path for fabrication using standard CMOS technologies. At last, an application of the proposed model depicting in-memory computation through a memristor emulator crossbar array is presented in brief.

A linearly/electronically controllable high gain VDGA and its applications

Since the transconductance gains of an active building block namely voltage differencing gain amplifier (VDGA) is directly proportional to nonlinear (square root) function of external DC bias currents, affecting the narrow range tunability and low transconductance gains. This article aims to introduce a high gain VDGA by using CMOS current squaring circuits biasing in each transconductance cell. It offers high transconductance gains, wide range of tunability, linearity of controllability, larger input voltage range and nearly infinite input impedance. The proposed circuit was designed using a 0.18 µm CMOS transistors technology. The test was performed using PSpice program, it is consistent with the theoretical expectation. The total power consumption is 2.9 mW at ±1.5 V power supply. Even its power consumption is more than about 3 times of their previously proposed VDGAs, the figure of merit (FOM) of the proposed VDGA is much better than that of the previously proposed VDGAs (about 10 times). Additionally, the applications of the proposed VDGA as a capacitance multiplier, current multiplier/divider, summing amplifier, independently/electronically tunable multifunction filter, precision half-wave and full-wave rectifiers are included to insist the workability of the proposed VDGA.

1011 HETEROGENEOUS ARRHYTHMIC PHENOTYPE IN A CASE OF LEFT VENTRICULAR NON COMPACTION CARDIOMYOPATHY

Abstract A young 47 years old female patient was hospitalized in our department for recurrent traumatic syncopal episodes in order to undergo Head Up Tilt Test and Electrophysiology Study (EPS). Her ECG was normal and also transthoracic echocardiography didn't show pathological findings. 24 hour Holter ECG recording showed a short run of polymorphic ventricular tachycardia. Regarding familiar history her mother had died at a young age of sudden death. Head-up tilt test resulted negative for induced-syncope. During hospitalization the patient complained onset of malaise rapidly exiting in syncope: telemetry showed two pauses of 3.8 and 5.1 sec respectively, due to paroxysmal III degree atrio-ventricular block. The day after, the patient underwent electrophysiological study. During programmed ventricular stimulation from RV apex with train and V extrastimolous S1 300 S2 220 induction of syncopal ventricular fibrillation was observed, promptly treated with external DC shock. Cardiac MRI was performed showing diagnostic signs of Left Ventricular non-Compaction Cardiomyopathy. Considering the history of traumatic syncope the patient underwent dual chamber ICD implantation and was discharged. No clinical events in a 6 month follow-up. Genetical analysis was performed and we are waiting for the results. The term left ventricular non-compaction (LVNC) identifies a cardiomyopathy, characterized by intrauterine arrest of the compaction process of the ventricular myocardium during the end of the fourth week, thus leading to the development of prominent trabeculae of the left ventricle, deep intertrabecular recesses and a ventricular wall divider into two different layers of myocardium, the first compact, the other not. This nosological entity is difficult to classify (the European Society of Cardiology considers it as not classifiable among other cardiomyopathies, unlike the American Heart Association) mostly from the point of view of clinical implications, often unpredictable. In fact, we may have completely asymptomatic forms, which, according to some authors, should be considered as normal and completely benign variants, and various manifestations, in which the lack of compaction represents a morphological trait shared by phenotypically distinct forms of cardiomyopathy, such as hypertrophic, dilated and restrictive. LVNC carries an increased risk of ventricular dysfunction resulting in chronic heart failure, thromboembolic events and especially arrhythmic, often ventricular and life-threatening manifestations. A large spectrum of arrhythmias has been observed in patients with non-compact ventricles: in particular, supraventricular and ventricular tachycardias, Wolff-Parkinson-White (WPW) syndrome, but also bradyarrhythmias, which include sinus bradycardia, Sick Sinus Syndrome and various degrees of atrioventricular block, up to complete block. Ventricular tachycardias, including those that progress to ventricular fibrillation, occur in 38–47% of adult patients with LVNC, hence sudden death is often the cause of clinical presentation. Seen the features of the pathology, early diagnosis and family clinical evaluation are necessary aspects in patient management.

Low coercivity magnetoplasmonic crystal based on a thin permalloy film for magnetic field sensing applications

This research is devoted to the fabrication of 5-nm thick permalloy film-based magnetoplasmonic crystal for magnetic field sensing applications. Optical and magneto-optical activity of the magnetoplasmonic crystal is studied with the means of numerical modeling and spectroscopy techniques. The studied sample achieves sensitivity to an external DC magnetic field of 7.5 mOe in the 5.1 Oe required modulation AC magnetic field. Obtained experimental and modeling results can be used for the fabrication of cheaper and more energy-efficient sensing elements for magnetoplasmonic crystal-based magnetic field sensors due to the reduction of required ferromagnetic material and modulation magnetic field.

Design and Implementation of Graphene-Based Tunable Microwave Filter for THz Applications.

A reconfigurable Substrate-Integrated Waveguide (SIW) filter operating in the THz region was designed in this work. Two SIW resonators were coupled through a magnetic iris to form a second-order filter with a double-layer substrate. The first substrate was silicon of permittivity 11.9; on top of it, silicon dioxide of permittivity 3.9 was placed. The ground and upper plane were composed of gold plates. Graphene material was then used for the tunability of the filter. A thin graphene sheet was sandwiched between the silicon dioxide substrate and the upper gold plate. An external DC bias voltage was then applied to change the chemical potential of graphene, which, in turn, managed to change the operational center frequency of the filter within the range of 1.289 THz to 1.297 THz, which translated to a bandwidth range of 8 GHz. The second part of this work centered on changing the aspect ratio of the graphene patch to change the center frequency. It was observed that the frequency changed within the range of 1.2908 THz to 1.2929 THz, which gave a bandwidth of 2.1 GHz change.

Break the superheat temperature limitation of induction skull melting technology

Overcoming the limitation of low superheat temperature problem is key for the applications of the induction skull melting technology in many important high melt point metals used in fields such as aerospace. The present paper presents an advanced numerical study to explain the mechanism of melt superheat temperature. A coupling model between electromagnetic, thermal, phase and fluid flow fields was established, which accurately predict the temperature and meniscus shape in the research domain. The simulation results show that the forced convective heat transfer caused by electromagnetic force in the melt and the current passing through phenomenon between molten melt and crucible were the key to influence the superheat temperature and electrical efficiency. Furthermore, it was discovered that convection suppression in the melt by employing an external DC coil and increasing the thermal resistance between the skull and the crucible could increase the melt superheat temperature effectively. Increasing the thermal resistance between the skull and the crucible also leads to an increase in the superheat temperature, which could be achieved by enhancing the interface roughness. The present work would shed lights on the design of new generation induction crucible to obtain high superheat temperature melt.

Real-time FMR lorentzian visualization through a novel synchronous VNA-FMR measurement apparatus.

It is shown in this work that a synchronous measurement setup is able to conveniently and accurately retrieve ferromagnetic resonance's (FMR) main physical properties from a permalloy sample. The apparatus used comprises a vector network analyzer (VNA), coupled with external DC coils, driven by a controllable power supply. A permalloy thin film sample was subjected to a microwave signal through a grounded coplanar waveguide. A square wave signal generated by an Arduino microcontroller drives the coils to a triangular, 65.4ms period magnetic field. This field's half-cycle is synchronized to match a zero-span sampling time at the VNA. The system has the advantage of fast results, as the typical FMR lorentzian curve is completed in a few seconds and shown immediately on the VNA's scattering parameter S21 trace graph. The system showed an improved signal-to-noise ratio of 51.7 at 10GHz over 24.3 for the 100nm thick permalloy- sample used in this work. A magnetic field resonance point, collected at 10GHz, showed a five-fold improvement in the standard-error.

Low-profile metasurface-based dual-band graphene patch nanoantenna

This paper proposes a graphene patch antenna for dual-band operation while maintaining a low profile. The antenna consists of the metasurface-based 4 x 4 AMC configuration and the square graphene patch driven through the aperture coupling. The fundamental TM10 mode of graphene patch excites the first resonance frequency, while the TM10 and antiphase TM20 modes of metasurface simultaneously excite the second wide frequency band. The first resonance frequency excited by the graphene patch can be reconfigured by varying the external DC bias voltage on the graphene patch. An equivalent circuit of antenna using lumped elements has also been proposed using a vector fitting algorithm. The proposed antenna with a profile height of 0.12λ0 (where λ0 is free space wavelength) at a center frequency of 1.14 THz achieves the gain from 7.06 dB to 10.4 dB in the first band and an average gain of 10 dB in the second band.

Event-driven MEMS vibration sensor: Integration of triboelectric nanogenerator and low-frequency switch

Triboelectric-nano-generator (TENG) is able to produce a very small current and a large voltage compared to piezoelectric or electromagnetic generators. The large voltages from the TENGs are suitable for operating MEMS devices without external AC or DC generators. Producing micro-sized TENG using MEMS fabrication process enables integration of them with MEMS sensors and actuators. This combination is useful because the required voltage for driving MEMS is obtained from the motion of the event that is being measured. In this work, an event-driven vibration sensor is introduced which actuates a switch as the frequency or amplitude of the vibration exceeds a desired threshold. Using CMOS micromachining, a 1.5 mm × 1.5 mm TENG in contact-separation (CS) mode is fabricated to convert ambient vibrations to a voltage generated between a conductive aluminum layer and a dielectric Polyimide layer. The large generated voltage between the electrodes can operate a low-frequency electrostatic MEMS switch. Two events are able to produce the resonant dynamic pull-in needed to close the switch. Event one is when the input amplitude exceeds the dynamic pull-in threshold which is called acceleration sensitive mode. Event two is when the frequency of the vibration exceeds a specified threshold. An electromechanical model for the MEMS switch part of the vibration sensor is also presented. Results show that MEMS-TENG is able to supply the MEMS switch in the frequency sensitive and acceleration sensitive modes with a good signal-to-noise-ratio, sensitivity, and accuracy.

Effect of external DC field on current transformers with amorphous and nanocrystalline cores

Nanocrystalline and amorphous stress-annealed and field annealed tapes are used for cores of DC-tolerant current transformers. We analyze the influence of external DC field of arbitrary direction on the performance of these transformers. For the realistic core shapes the demagnetization is high, which leads to effective external field suppression. However, DC tolerant transformers are tolerant to the DC component of the current and not to the external field - they can be saturated by 30 mT field from permanent magnet. This means that for the practical applications in domestic energy meters some external shielding is required.

Magneto Elasticity Modeling for Stress Sensors

In this article, the stress/stress sensing capability of FeSiB thin films is demonstrated and discussed. The sensing relies on the change in permeability by the application of stress, compressive and tensile, and the application of DC magnetic field. This susceptibility/permeability was tested by the exciting field (AC) being in the same direction with the applied stress. The susceptibility was shown to exhibit a maximal value at a given applied stress, the critical stress. Moreover, this maximal amplitude and position was changing with the application of an external DC magnetic field. For the DC field applied in the direction of the exciting field (AC) and longitudinal to the stress, the critical stress was shifted toward negative values and for the DC field applied perpendicularly, the critical stress was shifted toward larger positive values. This was experimentally demonstrated, and a model was constructed for a better understanding.

Negative Capacitance Phenomenon and Origin in Alkali Niobate Film with Self‐Assembled Lattice Faults

AbstractNegative capacitance (NC) is an important phenomenon both in terms of the underlying fundamental science and its potential device application value. Achieving NC with adequate tunability in a scalable and reliable way is highly demanded for industrial applications. Herein, an electric‐field‐induced NC phenomenon and inductance‐like behavior in alkali‐deficient potassium sodium niobate thin film with self‐assembled planar faults are demonstrated. Our in‐depth investigation with the help of atomic‐scale microscopy and high‐temperature dielectric, conductivity, and X‐ray studies revealed that the compensated electronic charge at the planar faults is localized as bound polarons which convert to free polarons at high temperature as well as by an increased electric field. The collective response of such polaronic charge along the planar faults under an oscillating electric field results in the observed NC phenomenon and inductance effect. Large NC values are obtained which can be tuned in terms of magnitude and operating frequency by controlling the concentration of the free polarons via external DC bias. This work underpins the unique feature of the defect architecture obtained in the alkali deficient KNN film and provides a novel material design strategy and fundamental framework to realize NC and related exotic phenomena in defect‐engineered oxide materials.

Ferromagnetic Coupling and Single-Ion Magnet Phenomenon in Mononuclear Ruthenium(III) Complexes Based on Guanine Nucleobase

Two mononuclear RuIII complexes of formula trans-[RuCl4(Hgua)(dmso)]·2H2O (1) and trans-[RuCl4(Hgua)(gua)]·3H2O (2) [Hgua = protonated guanine (gua), dmso = dimethyl sulfoxide] have been synthesized and characterized magnetostructurally. 1 and 2 crystallize in the monoclinic system with space groups P21/n and Pc, respectively. Each RuIII ion in 1 and 2 is bonded to four chloride ions and one (1) or two (2) nitrogen atoms from guanine molecules and one sulfur atom (1) of a dmso solvent molecule, generating axially compressed octahedral geometries in both cases. In their crystal packing, the RuIII complexes are connected through an extended network of N-H⋯Cl hydrogen bonds and π⋯Cl intermolecular interactions, forming novel supramolecular structures of this paramagnetic 4d ion. Variable-temperature dc magnetic susceptibility data were obtained from polycrystalline samples of 1 and 2 and their plots show a different magnetic behavior. While 1 is a ferromagnetic compound at low temperature, 2 exhibits a behavior of magnetically isolated mononuclear RuIII complexes with S = 1/2. The study on ac magnetic susceptibility data reveal slow relaxation of the magnetization, when external dc fields are applied, only for 2. These results highlight the presence of field-induced single-ion magnet (SIM) behavior for this mononuclear guanine-based RuIII complex.

The Electroconvective Flows of a Weakly Conducting Liquid in the External DC and AC Electric Fields

The Electroconvective Flows of a Weakly Conducting Liquid in the External DC and AC Electric Fields

Excitation of weak and strong guided waves in a semiconductor slab and their strong coupling with confined magnetoexcitons

We have obtained and analyzed optical spectra of a semiconductor slab, containing a quantum well which serves as a source of magnetoexcitons in the presence of an external dc magnetic field. Our setup corresponds to the optical technique based on the breaking of the total internal reflection. Specifically, the semiconductor slab is sandwiched between two external leads/prisms separated from the slab by two gap layers of a dielectric or metal. The reflectivity, transmissivity, and absorption spectra for such a system in a quantizing magnetic field were revealed to display a resonant structure originating from the excitation of electromagnetic modes localized on the semiconductor slab which are strongly coupled with the confined magnetoexcitons. It is surprising that the Rabi splitting for the setup with dielectric gap layers (weak guiding) turns out to be greater than that for metallic and even semiconductor microcavities (strong guiding). Our results were verified by comparing the calculated optical spectra with the dispersion curves for localized modes derived analytically.

Novel Active-C Voltage-Mode Quadrature Oscillator Realization Employing CCCIIs

Acurrent controlled sinusoidal voltage-mode quadrature oscillator circuit is presentedherewhich has employed three second-generation current-controlled-conveyors (CCCIIs) and two grounded capacitors(GCs). The condition of oscillation (CO) and frequency of oscillation (FO) of the proposed circuit are uncoupled and can be electronically controllable through an external dc bias current of CCCII. Sensitivities of active and passive elements are very low and the voltage outputs which are in 90ophase difference have high output impedances. Moreover, if apply the input at terminal Y of CCCII-03 it behaves as biquad filter which produce the band-pass (BP) and low-pass (LP) responses instantaneously and it have high input impedance which is very useful in cascading. The PSPICE simulation resultsverify the workability of the oscillator and filter circuit.

Effect of Ligand Chain Length for Tuning of Molecular Dimensionality and Magnetic Relaxation in Redox Active Cobalt(II) EDOT Complexes (EDOT=3,4-Ethylenedioxythiophene).

Four cobalt(II) complexes, [Co(L1)2 (NCX)2 (MeOH)2 ] (X=S (1), Se (2)) and {[Co(L2)2 (NCX)2 ]}n (X=S (3), Se (4)) (L1=2,5-dipyridyl-3,4,-ethylenedioxylthiophene and L2=2,5-diethynylpyridinyl-3,4-ethylenedioxythiophene), were synthesized by incorporating ethylenedioxythiophene based redox-active luminescence ligands. All these complexes have been well characterized using single-crystal X-ray diffraction analyses, spectroscopic and magnetic investigations. Magneto-structural studies showed that 1 and 2 adopt a mononuclear structure with CoN4 O2 octahedral coordination geometry while 3 and 4 have a 2D [4×4] rhombic grid coordination networks (CNs) where each cobalt(II) center is in a CoN6 octahedral coordination environment. Static magnetic measurements reveal that all four complexes displayed a high spin (HS) (S=3/2) state between 2 and 280 K which was further confirmed by X-band and Q-band EPR studies. Remarkably, along with the molecular dimensionality (0D and 2D) the modification in the axial coligands lead to a significant difference in the dynamic magnetic properties of the monomers and CNs at low temperatures. All complexes display slow magnetic relaxation behavior under an external dc magnetic field. For the complexes with NCS- as coligand observed higher energy barrier for spin reversal in comparison to the complexes with NCSe- as coligand, while mononuclear complex 1 exhibited a higher energy barrier than that of CN 3. Theoretical calculations at the DFT and CASSCF level of theory have been performed to get more insight into the electronic structure and magnetic properties of all four complexes.

On the possibility of technosphere safety by superionic

The purpose of this article is an attempt to substantiate the possibility of using a new technology for cleaning the industrial atmosphere in a separate workshop of the Taldykorgan battery plant "Kainar AKB", which produces, in particular, powerful batteries for K–700 tractors for agriculture. The innovative technology of air purification proposed by us in the technosphere of the manufacture of batteries for the agricultural production complex is based on the use of transport ion-conducting properties of solid electrolytes made of stabilized zirconium dioxide. The traditional methods of industrial atmosphere purification in enterprises and factories known to us, in our opinion, are morally outdated in terms of bulky external dimensions, noise generation, and need for systematic maintenance. The installation developed by us from a superionic conductor is devoid of these disadvantages, it is low-inertia, does not create a noise effect, compact and small-sized. Our ion conducting solid electrolyte is a ceramic material in the form of pipes, test tubes, tablets, initially containing impurity cations of lower valence, such as calcium, yttrium, scandium, in comparison with zirconium. Actually, these impurity cations create the presence of vacancies or holes in the solid cubic structure of zirconium dioxide. Only oxygen anions will be transported through these vacancies under the effect of external factors, high temperature, and DC electric field. The research method is based on the measurement of the electromotive force, which is recorded at the boundary section: air/superionic/air, which is uniquely mathematically related to oxygen concentration in air stream.

Study on gas production mechanism of medium- and low-rank coals excited by the external DC electric field

This study aims to further explain abnormal phenomena occurring during coal and gas outbursts and grasp the gas production effect of the micro-structure on outburst coal surface under the action of the electric field. To this end, in this study, an experimental system for gas production of coal excited by the external DC electric field was established. Then, gas production experiments were performed on medium- and low-rank coals excited by the different-strength electric fields to reveal the relationships between gas production and coal rank and excitation voltage. Subsequently, the variations of functional groups and chemical bonds on coal sample surface after the external DC electric field excitation (EFE) were measured and analyzed through Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). According to the results of the gas production experiment, gases produced by medium- and low-rank coals under EFE include CH4, CO and CO2, and the gas production volume rises with the increase in excitation voltage. The results of FTIR analysis show that the contents of hydroxyl, aliphatic hydrocarbons and oxygen-containing functional groups of medium- and low-rank coals decrease to varying extents after EFE. The results of XPS analysis disclose that the structure of C element on the surface of medium- and low-rank coals changes after EFE. Therefore, the CO, CH4 and CO2 produced by medium- and low-rank coals during EFE come from the breakage of chemical bonds and the falling-off of functional groups. The research results provide theoretical support for revealing the mechanism of coal rock dynamic disasters and exploring methods for the monitoring and pre-warning of these disasters.

A method of power-electronized supply accommodation capacity analysis for receiving-end grid based on multi-objective optimization

Abstract With the development of renewable energy and high voltage direct current (HVDC) system, the proportion of power-electronized supply in power system is increasing. It creates challenges to the safe and stable operation of the receiving power grid. Reasonable evaluation of the scale of power-electronized supply that can be carried by the receiving-end grid is of great significance to guide power grid construction and maintain its operational safety. Firstly, this paper explains the theory that the unified effective short circuit ratio (UESCR) can reflect the static voltage stability of buses. Then, a multi-objective optimization model, which considers the external dc feed-in, local renewable energy, unit output, and operation constraints, is established to obtain the power-electronized supply accommodation capacity. And it is solved repeatedly by means of cyclic increasing dc feed-in scale and renewable energy penetration. Finally, the effectiveness and practicability of the proposed method are verified in a modified IEEE 39 bus system.