Discrete Components Research Articles

Modeling of integrated signal converters for biomedical sensor microsystems

The paper presents the results of computer modeling of the proposed functional-electrical circuit of integrated signal converters (ISC) from photosensitive elements based on CMOS operational amplifiers, which is intended for the construction of an element base of hybrid sensor microsystems for biomedical applications. A feature of this ISC is the regulation and filtering of the amplitude of the constant component in the amplified signal from the diode photosensitive element in the wave range of 400 - 1040 nm.
 Computer simulation of the functioning of the device was carried out, the constituent components were determined and their parametric optimization was carried out. The results of experimental studies and computer modeling agree well, which confirms the correct functioning of the proposed signal converter from photosensitive elements. The developed ISC is suitable for creating real devices, both on the basis of discrete components and in an integrated design, as an element of sensor microsystems-on-a-chip or intelligent sensors.

Comparison of Microcomb-Based Radio-Frequency Photonic Transversal Signal Processors Implemented with Discrete Components Versus Integrated Chips.

RF photonic transversal signal processors, which combine reconfigurable electrical digital signal processing and high-bandwidth photonic processing, provide a powerful solution for achieving adaptive high-speed information processing. Recent progress in optical microcomb technology provides compelling multi-wavelength sources with a compact footprint, yielding a variety of microcomb-based RF photonic transversal signal processors with either discrete or integrated components. Although they operate based on the same principle, the processors in these two forms exhibit distinct performances. This paper presents a comparative investigation of their performances. First, we compare the performances of state-of-the-art processors, focusing on the processing accuracy. Next, we analyze various factors that contribute to the performance differences, including the tap number and imperfect response of experimental components. Finally, we discuss the potential for future improvement. These results provide a comprehensive comparison of microcomb-based RF photonic transversal signal processors implemented using discrete and integrated components and provide insights for their future development.

Evaluation of angular resolution requirements in the finite-volume-method solution of the radiative transfer equation

The performance of the finite volume method (FVM) used to solve the radiative transfer equation (RTE) is investigated in a simple benchmark configuration corresponding to a hot plate radiating towards sensors located at various separation distances. The study is performed using the Fire Dynamics Simulator (FDS). The objective of this study is to evaluate angular resolution requirements in the FVM-RTE solver to provide suitable accuracy and to avoid ray effects. The FDS-simulated radiative heat fluxes are compared to exact analytical expressions based on view factors. It is found that the numerical error has spatial and angular discretization components. The spatial discretization error is controlled by the size of computational cells and is generally small. The angular discretization error is controlled by the number of radiation angles (NRA) and becomes large in the far-field unless NRA is sufficiently large. A design criterion is proposed to select suitable values of NRA to achieve converged numerical solutions. This criterion is applied to the case of radiant emissions from a benchmark pool fire configuration; this application illustrates how the choice of NRA should be adjusted depending on the size of the region where accurate calculations of radiative heat fluxes are expected.

Sustainable and effective catalytic particles for electrocatalytic combustion of refractory organic matter

The development of ultra-efficient, sustainable, and easily accessible catalytic particle (CP) is a useful strategy for hydroxyl radical generation in the three-dimensional electrolytic system (3D ECs). Herein, a crystalline fused CP composed of coal gangue, activated sludge, and iron sludge, were synthesized for refractory organic matter electrocatalytic combustion in a boron-doped diamond (BDD) 3D ECs. A rough and SnO2 semiconductor metal oxide pellet-anchored continuous interface was created through a one-pot calcination method. In determination of the CP agglomeration mechanism, XRD and XPS results displayed that discrete component of SiO2, Al2O3, and Na2O were transformed into a homogeneous quartz albite NaAlSi3O8 phase, and SnO2-Sb2O5 components formed and spread in the whole ball structure during high-temperature molding process. The newly designed CP exhibited incomparable phenol degradation capacity. The dichromate oxidizability (CODCr) removal efficiency of phenolic wastewater increased 14.3 % compared to the commercial active carbon packed system. The electrocatalytic oxidation capacity of CP was evaluated comprehensively under various working condition, e. g. different cathodes, present or absent of Cl- and persulfate agents, and with or without microbubble coupling. Our experimental results showed that considerable CODCr removal efficiency of 86.3 % was obtained with microbubble coupling oxidation using cell voltage 6.0 V and treating time 120 mins. Besides these, the designed CP presented outstanding stability, and CODCr removal efficiency slightly decreased 7.1 % after 10 cycle repetitions. The use of solid waste as the main material for CPs production not only realizes harmless treatment of solid wastes but also improve the 3D ECs significantly.

An augmented state Gaussian mixture probability hypothesis density filter for multitarget tracking of autonomous underwater vehicles

Multitarget tracking is an important task for autonomous underwater vehicles (AUVs). Due to the limited space on AUVs, the aperture of the sonar array mounted on an AUV is small. The finite resolution of AUV sonar systems results in weak targets being masked by strong targets when they are close in angular space, leading to the trajectory fracture problem of weak targets in the azimuth crossing scenario. To address this problem, an augmented state Gaussian mixture probability hypothesis density (GM-PHD) filter is proposed. Since the acoustic signals radiated by targets contain some narrowband discrete components (known simply as tonals or lines), we focus on leveraging the tonals to enhance tracking performance. First, we model the augmented state dynamics, which contain both direction-of-arrival (DOA) and tonal components, and DOA tracks can be generated by the augmented state GM-PHD filter. Second, track segments are clustered by the modified density-based spatial clustering of applications with noise (DBSCAN) algorithm according to the estimated tonals. Finally, track segments with the same clustering results are associated with the same target, and the track stitching method is applied to overcome the trajectory fracture problem. The effectiveness of the algorithm is verified by simulation experiments in different scenarios.

High resistivity free-standing crosslinked graphene oxide substrates: hopping conduction mechanism and application to recyclable electronics

Graphene oxide (GO) is an oxidized derivative of graphene that can be formed into free-standing wafers by aqueous processing methods. We propose GO as a potential alternative printed electronic substrate material to mitigate the waste electronic and electrical equipment problem. By dissolving these substrates in water, GO permits the mechanical separation and recovery of discrete components from defunct circuits, thus closing the life cycle of printed circuits. In this work we measure the anisotropic, frequency dependent resistivity of free-standing GO wafers under DC and AC (f = 0.1 Hz–500 kHz) excitation and in varying relative humidity (RH) conditions. Unmodified GO and GO crosslinked with calcium ions, borate ions, and glutaraldehyde were characterized. AC resistivity measurements reveal charge transport in free-standing GO occurs by several distinct hopping conduction mechanisms that are sensitive to the crosslinking formulation. GO crosslinked with calcium ions exhibits the highest DC resistivity, 4.6 × 105 Ωm and 2.6 × 104 Ωm, for out-of-plane and in-plane directions, respectively, at 17% RH. Both AC and DC resistivities decrease with increasing RH. We demonstrate that GO wafers can be used as dielectric substrates in the construction of simple electronic circuits with discrete electronic components. Finally, we present a proof-of-concept for electrical trace and component recovery via disassembly of GO wafers in water.

A Self-Bias-Flip With Charge Recycle Interface Circuit With No External Energy Reservoir for Piezoelectric Energy Harvesting Array

This paper presents a piezoelectric energy harvesting (PEH) interface circuit using a new self-bias-flip with charge recycle (SBFR) technique without employing any additional energy reservoir. Traditional designs, including synchronous-switch harvesting on inductor (SSHI), synchronous-switch harvesting on capacitor (SSHC), synchronous electric charge extraction (SECE), etc., require additional capacitors or inductors to reverse the voltage on the PEH at the zero-crossing point. This design innovatively uses the inherent capacitors of the piezoelectric harvesters as the flipping capacitors. In order to improve the extract efficiency of the interface, the zero-crossing state is split into charge recycle stage and voltage-flip stage. For a piezoelectric array with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2^{n}$</tex-math></inline-formula> PEHs, a configuration with (n-1) phases in the charge recycle stage is adopted to reduce the loss caused by direct charge neutralization. The charge redistribution loss is reduced by employing (2n+1) phases in the voltage-flip stage. The proposed principle has been implemented with discrete components and is verified by 3 different prototypes. The measurement results show that a flipping efficiency of 67% is achieved by utilizing SBFR with 4 PEHs. And the proposed interface can provide up to 5.2x improvement when compared with the full-bridge rectifier (FBR).

Part One: Stability Analysis of Hydrogen-CNG Powered Vehicle

Background: When conventional petroleum-based liquid fuels are combusted, several hazardous pollutants are produced. These pollutants are noxious for both human beings and the environment. Objective: This study aims to analyze the stability of Hydrogen-CNG powered vehicles. Hydrogen has the potential to be one of the most sustainable fuels of the future, decrease the global dependence on fossil fuel resources, and lower the pollutant emissions from the transportation industry. Though we have alternative non-conventional sources of energy, the perfect one to use as the energy source for vehicles is hydrogen. The mixture of Hydrogen and CNG provides excellent properties as fuel for transportation. A fast and accurate control system is designed that allows the combustion of pure Hydrogen. Methods: Combination of Hydrogen with CNG can increase the power and efficiency of the vehicle. The vehicle powered by Hydrogen-CNG needs an electronic control system assuring the operation of its discrete components. MIMO system models having brakes and acceleration inputs are considered. Results: Results are presented for the vehicle transfer function in the form of Bode plots, Root locus, and Routh Hurwitz judging the stability of the vehicle. Conclusion: The main goals of the paper that is to analyze the stability of the vehicle and design an efficient control system are achieved. Obtaining the transfer function for governing equations for understanding the stability of the plant and generating a visual representation showing the relation between the variable quantities have been achieved in this paper.

A New Class of Nonlinear Resonance Networks Modeled by Levinson–Smith and Liénard Equations

We propose a new class of nonlinear resonance networks which are modeled by standard second-order nonlinear differential equations of the Levinson-Smith type or its subset, the Liénard type. In particular, we modify series and parallel RLC resonance networks such that the passive resistor in these networks is composed of a fixed part and a variable voltage-or current-controlled part. The variable resistor is then made controllable by one of the circuit’s state-space variables leading to an embedded self feedback control mechanism. A possible discrete component circuit realizing the proposed concept is presented along with its simulations and experimental verification. The filter response behavior of one of the modified series resonance circuits is also experimentally verified using a Field Programmable Analog Array.

Wound-Induced Hair Follicle Neogenesis as a Promising Approach for Hair Regeneration.

The mammalian skin contains hair follicles, which are epidermal appendages that undergo periodic cycles and exhibit mini-organ features, such as discrete stem cell compartments and different cellular components. Wound-induced hair follicle neogenesis (WIHN) is the remarkable ability to regenerate hair follicles after large-scale wounding and occurs in several adult mammals. WIHN is comparable to embryonic hair follicle development in its processes. Researchers are beginning to identify the stem cells that, in response to wounding, develop into neogenic hair follicles, as well as to understand the functions of immune cells, mesenchymal cells, and several signaling pathways that are essential for this process. WIHN represents a promising therapeutic approach to the reprogramming of cellular states for promoting hair follicle regeneration and preventing scar formation. In the scope of this review, we investigate the contribution of several cell types and molecular mechanisms to WIHN.

Voltage-controlled oscillators using CFOAs with correction terminal Z

ABSTRACT In this work, a realization of a voltage-controlled LC oscillator (VCO), using monolithic current-feedback operational amplifiers (CFOAs) with accessible correction terminal Z, is proposed. The frequency variation for the developed oscillator is obtained by replacing the capacitor in the resonant LC circuit with pairs of varactor diodes that use a common cathode. The barrier capacitance of the varactor diodes is controlled by a DC voltage obtained from an external voltage source. The proposed circuit configurations include single active element, a small number of discrete components, an operating frequency range of up to about 10 MHz and a relatively high value of the equivalent quality factor. To verify the effectiveness of the realised oscillators, results of computer simulations and experimental studies of sample electronic circuits using commercially available monolithic CFOAs with correction terminal Z are presented. Moreover, the obtained experimental results confirm the theoretical analyses of the circuits and the obtained mathematical expressions for the basic parameters, and the differences between them are within 10% and are mainly due to tolerances in the technological parameters of the used electronic components.

Treatment of landfill leachate using photocatalytic based advanced oxidation process – a critical review

Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity. Innovative treatment and emerging technologies are being scrutinized to address the treatment of landfill leachate challenges. The leading target of this review was to examine the possibility of removing recalcitrant organic pollutants from landfill leachate by photocatalytic–based advanced oxidation processes. A summary of the systematic applicability of conventional treatment for landfill leachate is provided, with a focus on physico-chemical and biological processes. The biological treatment, such as aerobic and anaerobic digestion, is an excellent technique for treating highly concentrated organic pollutants in the wastewater. However, Leachate can scarcely be treated using conventional techniques since it is enriched with refractory organics and inorganic ions. It is clear from the literature review that none of the available combinations of physico-chemical and biological treatments are entirely relevant for the removal of recalcitrant organic pollutants from leachate. Recently, the photo–assisted TiO2/ZnO oxidation has shown an excessively potential and feasible way to treat landfill leachate. TiO2/ZnO photocatalysis is currently developing to treat recalcitrant organic pollutants from landfill leachate. The effect of operating parameters reveals that pH and temperature affect the reaction rate. The addition of oxidant H2O2 to the TiO2/ZnO suspension suggests that TiO2 leads to an increase in the rate of reaction when compared to ZnO. Photocatalytic remediation technique of landfill leachate would support the goal of environmental sustainability by greatly enhancing the effectiveness of treated leachate reutilization. In this review, the selection of the best photocatalytic treatment for leachate based on its systematic relevance and potential conditions, characteristics, cost-effectiveness, essential controlling, discharge limit, long-term environmental effects, and its future study perspectives are emphasized and discussed.

A Self-Powered DSSH Circuit with MOSFET Threshold Voltage Management for Piezoelectric Energy Harvesting.

This paper presents a piezoelectric (PE) energy harvesting circuit based on the DSSH (double synchronized switch harvesting) principle. The circuit consisted of a rectifier and a DC-DC circuit, which achieves double synchronized switch operation for the PE transducer in each vibration half-cycle. One of the main challenges of the DSSH scheme was precisely controlling the switch timing in the second loop of the resonant loops. The proposed circuit included a MOS transistor in the second loop to address this challenge. It utilized its threshold voltage to manage the stored energy in the intermediate capacitor per vibration half-cycle to simplify the controller for the DSSH circuit. The circuit can operate under either the DSSH scheme or the ESSH (enhanced synchronized switch harvesting) scheme, depending on the value of the intermediate capacitor. In the DSSH scheme, the following DC-DC circuit reused the rectifier's two diodes for a short period. The prototype circuit was implemented using 16 discrete components. The proposed circuit can be self-powered and started up without a battery. The experimental results showed that the proposed circuit increased the power harvested from the PE transducer compared to the full-bridge (FB) rectifier. With two different intermediate capacitors of 100 nF and 320 nF, the proposed circuit achieved power increases of 3.2 and 2.7 times, respectively. The charging efficiency of the proposed circuit was improved by a factor of 5.1 compared to the typical DSSH circuit.

Locally Active Memristor-Based Neuromorphic Circuit: Firing Pattern and Hardware Experiment

Analog circuit implementation of neuron model is an essential category of neuromorphic circuit since it can reproduce neuron firing patterns and assist in exploring neuron-based applications. The neuron models built by electrophysiological ion transport mechanism can effectively mimic the neuron firing patterns. However, they are rather difficult to implement on analog level because these neuron models involve complex exponential nonlinearities for characterizing the ion channels. Thanks to the superiorities of locally active memristor in constructing artificial neuron circuit, two locally active memristors are employed to characterize the sodium and potassium ion channels and then a memristive neuromorphic circuit is successfully built in this paper. Numerical simulations demonstrate that the memristive neuromorphic circuit can generate abundant firing patterns with respect to memristor-and stimulus-related parameters. Moreover, quasi-periodic bifurcation behavior and coexisting firing patterns are triggered by different memristor initial conditions. Employing off-the-shelf discrete circuit components, a PCB-based analog circuit is manually constructed and hardware experiments are executed. Experimental results captured from hardware measurements satisfactorily verify the numerically simulated ones and effectively show the feasibility of the memristive neuromorphic circuit in generating neuron firing patterns.

Optical Beamforming Networks for Millimeter-Wave Wireless Communications

With the rapid data growth driven by smart phone, high-definition television and virtual reality/augmented reality devices and so on, the launched 5G and upcoming 6G wireless communications tend to utilize millimeter wave (mmWave) to achieve broad bandwidth. In order to compensate for the high propagation loss in mmWave wireless communications and track the moving users, beamforming and beamsteering are indispensable enabling technologies. These have promising potential to be realized through the use of optical beamforming networks (OBFNs) that have a wider bandwidth and smaller size, lower power consumption, and lower loss compared to those of their electric counterparts. In this paper, we systematically review various OBFN architectures using true time delays and optical phase shifters, as well as discuss performances of different architectures, scalable technologies that promote the advancement of OBFNs, and the application potentials of OBFNs. Two-dimensional OBFNs with discrete components or integrated optical devices have been elaborated, in addition to one-dimensional architectures. Moreover, the state-of-the-art technologies relative to reducing the size, loss and nonlinearity of OBFNs have also been discussed here.

Broadband frequency modulation signal downconversion using a monolithic integrated mutual injection laser.

We propose a new, to the best of our knowledge, broadband signal downconversion scheme implemented by a monolithic integrated mutual injection laser. A mathematical derivation, simulation, and experimental verification are carried out. Because the period-one oscillation frequency can be selectively operated on a large scale by controlling the current on the integrated laser, the tuning downconversion range is realized without changing the experimental equipment. The experiment verifies that the downconversion of the linear frequency modulation signal with a bandwidth of 0.5GHz from the center frequency of 18.75 to 0.85GHz, and the spurious-free dynamic range (SFDR) has reached 71.7d B/H z 2/3. Compared with the scheme based on discrete components, the system has no electric local oscillator or external modulator, which provides a method for radar signal downconversion.

Approximation of Discrete Measures by Finite Point Sets

Abstract For a probability measure μ on [0, 1] without discrete component, the best possible order of approximation by a finite point set in terms of the star-discrepancy is &amp;inline as has been proven relatively recently. However, if μ contains a discrete component no non-trivial lower bound holds in general because it is straightforward to construct examples without any approximation error in this case. This might explain, why the approximation of discrete measures on [0, 1] by finite point sets has so far not been completely covered in the existing literature. In this note, we close the gap by giving a complete description for discrete measures. Most importantly, we prove that for any discrete measures (not supported on one point only) the best possible order of approximation is for infinitely many N bounded from below by &amp;inline for some constant 6 ≥ c&gt; 2 which depends on the measure. This implies, that for a finitely supported discrete measure on [0, 1]d the known possible order of approximation &amp;inline is indeed the optimal one.

Mechanism of single variable grey forecasting modelling: Integration of increment and growth rate

Grey forecasting models as a kind of time series model have been widely applied in different areas, which have achieved high-precision performance for different series with evolutionary characteristics. This paper aims to deconstruct its modelling mechanism from the perspective of data characteristics. First, classical increment and growth rate relationship is analysed and a unified representation of the mixed relationship with increment and growth rate is given. To establish the relationship between grey forecasting models and traditional models, the mechanism is analysed by deconstructing discrete structural components. Then, the series of evolutionary characteristics in main grey forecasting models are linked and summarized. The affine properties of parameter estimation and predicted value are analysed before simulation. Furthermore, through numerical simulations, the performance of grey forecasting models for different feature sequences and the difference between single variable models is demonstrated. Finally, results in the real case show that MAPEs of grey forecasting models have controlled under 4% for different sequences, which are suitable for mixed feature sequences.

Optimization With Simulated Annealing and Experimental Study of a Discretized Position Circuit (DPC) Network Using an Array of SiPMs

Arrays of tens or even hundreds of Silicon Photomultipliers (SiPMs) coupled to scintillators to build compact and robust position sensitive radiation detectors are becoming ubiquitous in nuclear medicine devices. In order to reduce the number of read-out electronic channels, and still be able to keep position information, multiplexing the SiPM signals with 2D resistor networks is fairly common. Good results are obtained with the DPC (Discretized Positioning Circuit) configuration. Even though it is a simple topology with a minimum number of discrete components, it yields good peak/valley ratios. However, it has the disadvantage that the network is asymmetric in X and Y directions, leading to different paths for the signal to reach the output depending on the position of the event. This causes the pulse shape to be also dependent on the position of the interaction in the detector, and creates a distortion (pincushion or barrel) of the position determined with center of energy algorithms. This effect can be partially remedied by a non-homogeneous choice of resistors in the network, but finding the best resistor values, in the case of large SiPM aggregations is very time consuming. We have developed a framework to optimize resistor values in DPC configurations to minimize position distortion and then impose that every SiPMs see an impedance to ground as similar as possible. We solved the DPC circuit and employed a simulated annealing algorithm to explore thousands of resistor combinations. The best combinations found in the computer were implemented in the laboratory confirming the results of the simulated annealing algorithm. In addition, we have verified that the optimized DPC network preserves the pulse shape to the extent that pulse shape discrimination makes it possible to disentangle two different scintillator layers (phoswich) of LYSO and GSO.

Nonlinear regimes of inertial wave attractors generated by a precessing lid: Zonal flows and Rossby waves

Fluid flow excited by inertial waves in a rotating annulus with a trapezoidal cross section is experimentally investigated. The forcing is introduced by the precession of a flat annular lid bounding the cavity. Such a setup allows to investigate interactions between inertial waves and zonal flows in the presence of equivalent topographic beta-effect, and its dynamic behavior under weak and strong forcing is experimentally studied for the first time. Due to the specific dispersion relation of inertial waves, a cavity shape supports wave attractors that appear only for retrograde lid precession. At a relatively low wave intensity, a zonal flow is generated in the vicinity of a “virtual” axial cylinder, the radius of which coincides with the radius of the focusing reflection from the conical bottom. A succession of non-linear regimes is observed as forcing increases, starting with a clearly identifiable case of triadic resonance. Further, the frequency spectrum is progressively enriched by emergence of additional discrete components, gradually reaching the state of “overheated” wave turbulence with a significant continuous background of the frequency spectrum. Finally, a strong low-frequency component develops in the frequency spectrum, and the continuous background of the spectrum decreases dramatically. The low-frequency component corresponds to azimuthally periodic structures identified as Rossby waves. In the case of strong forcing, a long-term variability of zonal-flow velocity at the timescale of tens of forcing periods is observed, which is likely a consequence of the interaction of azimuthal structures corresponding to a rich wave number set.